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1.  Tertiary osteochondral defect of the talus treated by a novel contoured metal implant 
The primary treatment of most osteochondral defects of the talus is arthroscopic debridement and bone marrow stimulation. There is no optimal treatment for large lesions or for those in which primary treatment has failed. We report a 20-year-old female patient with persistent symptoms after two previous arthroscopic procedures. Computed tomography showed a cystic defect of the medial talar dome, sized 17 × 8 × 8 mm. The patient was treated with a novel contoured metal implant. At 1 and 2 years after surgery, the patient reported considerable reduction in pain and had resumed playing korfball at competitive level.
Level of evidence IV.
PMCID: PMC3096766  PMID: 21409468
Osteochondral lesions; Bone cyst; Talus; Ankle; Metal implant; Treatment
2.  CAM-Type Impingement in the Ankle 
Anterior ankle impingement with and without ankle osteoarthritis (OA) is a common condition. Bony impingement between the distal tibia and talus aggravated by dorsiflexion has been well described. The etiology of these impingement lesions remains controversial. This study describes a cam-type impingement of the ankle, in which the sagittal contour of the talar dome is a non-circular arc, causing pathologic contact with the anterior aspect of the tibial plafond during dorsiflexion, leading to abnormal ankle joint mechanics by limiting dorsiflexion.
A group of 269 consecutive adult patients from the University of Iowa Hospitals and Clinics who were treated for anterior bony impingement syndrome were evaluated as the study population. As a control group, 41 patients without any evidence of impingement or arthrosis were evaluated. Standardized standing lateral ankle radiographs were evaluated to determine the contour of the head/neck relationship in the talus. Two investigators made all the radiographic measurements and intra- and inter-observer reliability were measured.
34% of patients were found to have some anterior extension of the talar dome creating a loss of the normal concavity at the dorsal medial talar neck. A group of 36 patients (13%) were identified as having the most severe cam deformity in order to assess any correlation with coexisting radiographic abnormalities. In these patients, a cavo-varus foot type was more commonly observed. Comparison with a control group showed much lower rates of anterior-medial cam-type deformity of the talus.
Cam type impingement of the ankle is likely a distinct form of bony impingement of the ankle secondary to a morphological talar bony abnormality. Based on the findings of this study, this form of impingement may be related to a cavovarus foot type. In addition, there may be long term implications in the development of ankle OA.
Level of Evidence
Level III
PMCID: PMC3565388  PMID: 23576914
3.  Treatment principles for osteochondral lesions in foot and ankle 
International Orthopaedics  2013;37(9):1697-1706.
Osteochondral lesion of the talus (OLT) is a broad term used to describe an injury or abnormality of the talar articular cartilage and adjacent bone. A variety of terms have been used to refer to this clinical entity, including osteochondritis dissecans (OCD), osteochondral fracture and osteochondral defect. Whether OLT is a precursor to more generalised arthrosis of the ankle remains unclear, but the condition is often symptomatic enough to warrant treatment. In more than one third of cases, conservative treatment is unsuccessful, and surgery is indicated. There is a wide variety of treatment strategies for osteochondral defects of the ankle, with new techniques that have substantially increased over the last decade. The common treatment strategies of symptomatic osteochondral lesions include nonsurgical treatment, with rest, cast immobilisation and use of nonsteroidal anti-inflammatory drugs (NSAIDs). Surgical options are lesion excision, excision and curettage, excision combined with curettage and microfracturing, filling the defect with autogenous cancellous bone graft, antegrade (transmalleolar) drilling, retrograde drilling, fixation and techniques such as osteochondral transplantation [osteochondral autograft transfer system (OATS)] and autologous chondrocyte implantation (ACI). Furthermore, smaller lesions are symptomatic and when left untreated, OCDs can progress; current treatment strategies have not solved this problem. The target of these treatment strategies is to relieve symptoms and improve function. Publications on the efficacy of these treatment strategies vary. In most cases, several treatment options are viable, and the choice of treatment is based on defect type and size and preferences of the treating clinician.
PMCID: PMC3764304  PMID: 23982639
Osteochondral lesions; Osteochondritis dissecans; Talus; Foot and ankle; Cartilage damage; Subchondral bone
4.  Effects of a contoured articular prosthetic device on tibiofemoral peak contact pressure: a biomechanical study 
Many middle-aged patients are affected by localized cartilage defects that are neither appropriate for primary, nor repeat biological repair methods, nor for conventional arthroplasty. This in vitro study aims to determine the peak contact pressure in the tibiofemoral joint with a partial femoral resurfacing device (HemiCAP®, Arthrosurface Inc., Franklin, MA, USA). Peak contact pressure was determined in eight fresh-frozen cadaveric specimens using a Tekscan sensor placed in the medial compartment above the menisci. A closed loop robotic knee simulator was used to test each knee in static stance positions (5°/15°/30°/45°) with body weight ground reaction force (GRF), 30° flexion with twice the body weight (2tBW) GRF and dynamic knee-bending cycles with body weight GRF. The ground reaction force was adjusted to the living body weight of the cadaver donor and maintained throughout all cycles. Each specimen was tested under four different conditions: Untreated, flush HemiCAP® implantation, 1-mm proud implantation and 20-mm defect. A paired sampled t test to compare means (significance, P ≤ 0.05) was used for statistical analysis. On average, no statistically significant differences were found in any testing condition comparing the normal knee with flush device implantation. With the 1-mm proud implant, statistically significant increase of peak contact pressures of 217% (5° stance), 99% (dynamic knee bending) and 90% (30° stance with 2tBW) compared to the untreated condition was seen. No significant increase of peak contact pressure was evaluated with the 20-mm defect. The data suggests that resurfacing with the HemiCAP® does not lead to increased peak contact pressure with flush implantation. However, elevated implantation results in increased peak contact pressure and might be biomechanically disadvantageous in an in vivo application.
PMCID: PMC2190783  PMID: 17934718
Osteochondral defect; Tibiofemoral joint; Articular prosthetic device; Peak contact pressure; Knee biomechanics
5.  Ankle Morphometry on 3D-CT Images 
Understanding three-dimensional (3D) morphology of the ankle is essential for a better total ankle replacement. Current designs neither mimic the articular geometry at the bearing surface interfaces nor match the native bony bed with the implant's external dimensions. This is likely due to insufficient anthropometric data on sizing and geometry. We performed this study to determine the range of possible sizes of ankle joints based on high-resolution 3D-CT images. Clinical 3D-CT images from twenty-one normal ankles (11 males, 10 females) were subjected to morphometric evaluation. A local coordinate system for measurement was established based on talar anatomic landmarks. Measurements included the width of the superior talar dome surface (measured at the anterior, middle, and posterior portions) and the arc radius of the talar dome. The results yielded an average anterior width of 29.9 ± 2.6 mm, a middle width of 27.9 ± 3.0 mm, and a posterior width of 25.2 ± 3.7 mm. The talar dome radius was 20.7 ± 2.6 mm. The width linearly decreased from anterior to posterior (p < 0.001). A significant gender difference was found in both the width and the radius (p-values < 0.05), except at the middle width (p = 0.07). The data describe talar topography in a Caucasian U.S. adult cohort, suggesting the capability of the 3D-CT approach for ankle morphometric evaluation and sizing for the fabrication of total ankle replacements.
PMCID: PMC1888582  PMID: 16789441
6.  One-step Bone Marrow-derived Cell Transplantation in Talar Osteochondral Lesions 
The ideal treatment of osteochondral lesions is debatable. Although autologous chondrocyte implantation provides pain relief, the need for two operations and high costs has prompted a search for alternatives. Bone marrow-derived cells may represent the future in osteochondral repair. Using a device to concentrate bone marrow-derived cells and collagen powder or hyaluronic acid membrane as scaffolds for cell support and platelet gel, a one-step arthroscopic technique was developed for cartilage repair. We performed an in vitro preclinical study to verify the capability of bone marrow-derived cells to differentiate into chondrogenic and osteogenic lineages and to be supported onto scaffolds. In a prospective clinical study, we investigated the ability of this technique to repair talar osteochondral lesions in 48 patients. Minimum followup was 24 months (mean, 29 months; range, 24–35 months). Clinical results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) score and the influence of scaffold type, lesion area, previous surgeries, and lesion depth was considered. MRI and histologic evaluation were performed. The AOFAS score improved from 64.4 ± 14.5 to 91.4 ± 7.7. Histologic evaluation showed regenerated tissue in various degrees of remodeling although none showed entirely hyaline cartilage. These data suggest the one-step technique is an alternative for cartilage repair, permitting improved functional scores and overcoming the drawbacks of previous techniques.
Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC2772930  PMID: 19449082
7.  Bone Microarchitecture of the Talus Changes With Aging 
Fractures of the talus in the elderly are rare and usually result from high-impact injuries, suggesting only minor age-related bone structure changes. However, total ankle replacement failures with age often result from talar subsidence, suggesting age-related bone loss in the talus. Despite a number of histological analyses of talar microarchitecture, the effects of age and sex on talar microarchitecture changes remain poorly defined.
The aim of this study was to analyze changes or differences in the trabecular microarchitecture of the talus with regard to (1) age and (2) sex.
Sixty human tali were harvested from 30 patients at autopsy of three different age groups (20–40, 41–60, 61–80 years). The specimens were analyzed by radiography, micro-CT, and histological analysis. Given that there was no difference between the left and right talus, static histomorphometric parameters were assessed in three regions of interest of the right talus only (body, neck, head; n = 30).
The talar body, neck, and head were affected differently by age-related changes. The greatest loss of bone volume with age was seen in the talar body (estimate: −0.239; 95% confidence interval [CI], −0.365 to −0.114; p < 0.001). In the talar neck (estimate: −0.165; 95% CI, −0.307 to −0.023; p = 0.025), bone loss was only moderate and primarily was the result of reduction in trabecular thickness (estimate: −1.288; 95% CI, −2.449 to −0.127; p = 0.031) instead of number (estimate: −0.001; 95% CI, −0.005 to −0.003; p = 0.593). Bone structure changes were independent of sex.
Age-related bone structure changes predominantly occur in the talar body, which poses a potential risk factor for total ankle replacement loosening. The moderate changes in the talar neck might explain the persistent low incidence of talar neck fractures with age.
Clinical Relevance
Our findings suggest that before total ankle replacement implantation, careful patient selection with dual-energy xray absorptiometry evaluation may be necessary to reduce the risk of talar implant subsidence.
PMCID: PMC3792264  PMID: 23893363
8.  Cartilage repair techniques of the talus: An update 
World Journal of Orthopedics  2014;5(3):171-179.
Symptomatic chondral or osteochondral defects of the talus reduce the quality of life of many patients. Although their pathomechanism is well understood, it is well known that different aetiologic factors play a role in their origin. Additionally, it is well recognised that the talar articular cartilage strongly differs from that in the knee. Despite this fact, many recommendations for the management of talar cartilage defects are based on approaches that were developed for the knee. Conservative treatment seems to work best in paediatric and adolescent patients with osteochondritis dissecans. However, depending on the size of the lesions, surgical approaches are necessary to treat many of these defects. Bone marrow stimulation techniques may achieve good results in small lesions. Large lesions may be treated by open procedures such as osteochondral autograft transfer or allograft transplantation. Autologous chondrocyte transplantation, as a restorative procedure, is well investigated in the knee and has been applied in the talus with increasing popularity and promising results but the evidence to date is poor. The goals of the current article are to summarise the different options for treating chondral and osteochondral defects of the talus and review the available literature.
PMCID: PMC4095009  PMID: 25035819
Cartilage defect; Talus; Repair techniques; Arthroscopy; Marrow stimulation; Mosaicplasty; Autologous chondrocyte implantation
9.  Matrix-Associated and Autologous Chondrocyte Transplantation in the Ankle 
Cartilage  2011;2(1):81-91.
New matrix-associated autologous chondrocyte transplantation (MACT) techniques may facilitate the treatment of chondral defects in talar cartilage and provide good clinical outcome in the long term. The aim of this prospective case series was to monitor the clinical outcome after autologous chondrocyte transplantation (ACT) and MACT in the ankle to gain data on the mid-term efficacy of the procedure.
Seventeen cases of talar cartilage defects were assessed with the American Orthopaedic Foot and Ankle Score (AOFAS), a modified Cincinnati score, and a subjective ankle-hindfoot score (AHS) at a mean of 61 (24-135) months after surgery. Nine patients consented to an additional magnetic resonance imaging (MRI) exam, including T2 mapping at 3T. ACT was carried out with a periosteal flap (4 cases) or with a matrix-assisted ACT technique (Hyalograft C; 13 cases).
Significant improvement was found in all cases. The AOFAS improved from 50.0 to 87.3, the AHS from 43.8 to 84.1, and the modified Cincinnati score from 2.9 to 6.9. MRI data demonstrated good defect filling, and T2 mapping results indicated that the collagen and water content of the repair tissue was comparable to adjacent cartilage.
MACT and ACT in the ankle can provide good and excellent long-term outcome and resulted in repair tissue with T2 properties similar to native cartilage in the majority of cases. Matrix-assisted implantation with the hyaluronan matrix allows for a less invasive surgical procedure.
Level of evidence:
4; prospective case series study.
PMCID: PMC4300785  PMID: 26069572
ACI; autologous chondrocyte transplantation; ankle; cartilage repair; T2 mapping; 3T
10.  Improved Visualization of the 70° Arthroscope in the Treatment of Talar Osteochondral Defects 
Arthroscopy Techniques  2013;2(2):e129-e133.
Osteochondral defects (OCDs) of the talus are a common cause of residual pain after ankle injuries. When conservative treatment fails, arthroscopic debridement combined with drilling/microfracturing of the lesion (bone marrow stimulation [BMS] procedures) has been shown to provide good to excellent outcomes. Not uncommonly, talar OCDs involve the borders of the talar dome. These uncontained lesions are sometimes difficult to visualize with the 30° arthroscope, with potential negative effect on the clinical outcome of an arthroscopic BMS procedure. The use of the 70° arthroscope has been described for a multitude of common knee, shoulder, elbow, and hip procedures. The purpose of this article is to show the usefulness of the 70° arthroscope in arthroscopic BMS procedures, pointing out which kinds of talar OCDs can benefit most from its use.
PMCID: PMC3716212  PMID: 23875138
11.  Radiographic Predictability of Cartilage Damage in Medial Ankle Osteoarthritis 
Radiographic grading has been used to assess and select between treatment options for ankle osteoarthritis. To use radiographic grading systems in clinical practice and scientific studies one must have reliable systems that predict the fate of the cartilage.
We therefore asked whether (1) radiographic grading of ankle osteoarthritis is reliable and (2) grading reflects cartilage damage observed during arthroscopy. We then (3) determined the sensitivity, specificity, and predictive values of the radiographic findings.
Patients and Methods
We examined 74 ankles with medial osteoarthritis and 24 with normal articular cartilage based on arthroscopy. Arthroscopic findings were graded according to the modified Outerbridge grades and all radiographs were graded using the modified Kellgren-Lawrence, Takakura et al., and van Dijk et al. grading systems. The reliability of each radiographic grading system was evaluated. We correlated the radiographic grades and severity of cartilage damage for each radiographic grading system. Sensitivity, specificity, and predictive values of spurs and joint space narrowing with or without talar tilting then were determined.
The interobserver weighted kappa ranged from 0.58 to 0.89 and the intraobserver weighted kappa from 0.51 to 0.85. The correlation coefficients for the Kellgren-Lawrence, Takakura et al., and van Dijk et al. grades were 0.53, 0.42, and 0.42, respectively. Ankles with medial joint space narrowing (Stage 2 of Takakura et al. and van Dijk et al. grades) showed varying severity of cartilage damage. The positive predictive value of cartilage damage increased from 77% for medial joint space narrowing regardless of the presence of talar tilting to 98% for medial joint space narrowing with talar tilting.
Our observations suggest the inclusion of talar tilting in grading schemes enhances the assessment of cartilage damage.
Level of Evidence
Level II, diagnostic study. See the Guidelines for Authors for a complete description of level of evidence.
PMCID: PMC2895860  PMID: 20393817
12.  One-step bone marrow-derived cell transplantation in talarosteochondral lesions: mid-term results 
Joints  2014;1(3):102-107.
to verify the capability of scaffold-supported bone marrow-derived cells to be used in the repair of osteochondral lesions of the talus.
using a device to concentrate bone marrow-derived cells, a scaffold (collagen powder or hyaluronic acid membrane) for cell support and platelet gel, a one-step arthroscopic technique was developed for cartilage repair. In a prospective clinical study, we investigated the ability of this technique to repair talar osteochondral lesions in 64 patients. The mean follow-up was 53 months. Clinical results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) scale score. We also considered the influence of scaffold type, lesion area, previous surgery, and lesion depth.
the mean preoperative AOFAS scale score was 65.2 ± 13.9. The clinical results peaked at 24 months, before declining gradually to settle at a score of around 80 at the maximum follow-up of 72 months.
the use of bone marrow-derived cells supported by scaffolds to repair osteochondral lesions of the talus resulted in significant clinical improvement, which was maintained over time.
Level of Evidence
level IV, therapeutic case series.
PMCID: PMC4295704  PMID: 25606518
bone marrow-derived cells; cartilage; osteochondral defect; repair; talus
13.  Osteochondritis Dissecans of the Talar Dome in a Collegiate Swimmer: A Case Report 
Journal of Athletic Training  1998;33(4):365-371.
To present the case of an intercollegiate swimmer with a stage IV lateral talar dome injury and associated bony fragments.
Lack of distinct diagnostic symptoms, low index of clinical suspicion, and the difficulty of visualizing the early stages of this injury on standard x-rays cause frequent misdiagnosis of talar dome lesions.
Differential Diagnosis:
Ganglion cyst, with inflammatory synovitis secondary to rupture of cyst; loose bodies from previous occult fracture; osteochondral fracture.
Initial treatment with nonsteroidal antiinflammatory drugs and a posterior splint for comfort, followed by arthroscopic excision of loose bodies with abrasion and drilling arthroplasty.
Patient presented to the team physician for care of acute left medial ankle pain after the athletic trainer had attempted to rupture a ganglion cyst on the anterolateral aspect of the patient's ankle.
Increased clinical suspicion is necessary to correctly diagnose osteochondral lesions, particularly in the early stages. Aggressive treatment of talar dome lesions has a good success rate and may be an attractive option for competitive athletes.
PMCID: PMC1320590  PMID: 16558537
ganglion cyst; inflammatory synovitis; osteochondral fracture
14.  The use of fibrin matrix-mixed gel-type autologous chondrocyte implantation in the treatment for osteochondral lesions of the talus 
This study assessed the clinical results and second-look arthroscopy after fibrin matrix-mixed gel-type autologous chondrocyte implantation to treat osteochondral lesions of the talus.
Chondrocytes were harvested from the cuboid surface of the calcaneus in 38 patients and cultured, and gel-type autologous chondrocyte implantation was performed with or without medial malleolar osteotomy. Preoperative American orthopedic foot and ankle society ankle-hind foot scores, visual analogue score, Hannover scoring system and subjective satisfaction were investigated, and the comparison of arthroscopic results (36/38, 94.7 %) and MRI investigation of chondral recovery was performed. Direct tenderness and relationship to the active daily life of the donor site was evaluated.
The preoperative mean ankle–hind foot scores (71 ± 14) and Hannover scoring system (65 ± 10) had increased to 91 ± 12 and 93 ± 14, respectively, at 24-month follow-up (p < 0.0001), and the preoperative visual analogue score of 58 mm had decreased to 21 mm (p < 0.0001). Regarding subjective satisfaction, 34 cases (89.5 %) reported excellent, good or fair. Chondral regeneration was analysed by second-look arthroscopy and MRI. Complications included one non-union and two delayed-unions of the osteotomy sites, and 9 ankles (9/31, 29.0 %) sustained damaged medial malleolar cartilage due to osteotomy. Marked symptoms at the biopsy site did not adversely affect the patient’s active daily life.
Fibrin matrix-mixed gel-type autologous chondrocyte implantation using the cuboid surface of the calcaneus as a donor can be used for treating osteochondral lesions of the talus.
Level of evidence
Therapeutic study, prospective case series, Level IV.
PMCID: PMC3657090  PMID: 22752415
Talus; Osteochondral lesion; Autologous chondrocyte implantation; Arthroscopy; Donor
15.  No Effect of Hole Geometry in Microfracture for Talar Osteochondral Defects 
Débridement and bone marrow stimulation is an effective treatment option for patients with talar osteochondral defects. However, whether surgical factors affect the success of microfracture treatment of talar osteochondral defects is not well characterized.
We hypothesized (1) holes that reach deeper into the bone marrow-filled trabecular bone allow for more hyaline-like repair; and (2) a larger number of holes with a smaller diameter result in more solid integration of the repair tissue, less need for new bone formation, and higher fill of the defect.
Talar osteochondral defects that were 6 mm in diameter were drilled bilaterally in 16 goats (32 samples). In eight goats, one defect was treated by drilling six 0.45-mm diameter holes in the defect 2 mm deep; in the remaining eight goats, six 0.45-mm diameter holes were punctured to a depth of 4 mm. All contralateral defects were treated with three 1.1-mm diameter holes 3 mm deep, mimicking the clinical situation, as internal controls. After 24 weeks, histologic analyses were performed using Masson-Goldner/Safranin-O sections scored using a modified O’Driscoll histologic score (scale, 0–22) and analyzed for osteoid deposition. Before histology, repair tissue quality and defect fill were assessed by calculating the mean attenuation repair/healthy cartilage ratio on Equilibrium Partitioning of an Ionic Contrast agent (EPIC) micro-CT (μCT) scans. Differences were analyzed by paired comparison and Mann-Whitney U tests.
Significant differences were not present between the 2-mm and 4-mm deep hole groups for the median O’Driscoll score (p = 0.31) and the median of the μCT attenuation repair/healthy cartilage ratios (p = 0.61), nor between the 0.45-mm diameter and the 1.1-mm diameter holes in defect fill (p = 0.33), osteoid (p = 0.89), or structural integrity (p = 0.80).
The results indicate that the geometry of microfracture holes does not influence cartilage healing in the caprine talus.
Clinical Relevance
Bone marrow stimulation technique does not appear to be improved by changing the depth or diameter of the holes.
PMCID: PMC3792274  PMID: 23893362
16.  Osteochondral Allograft Transplant to the Medial Femoral Condyle Using a Medial or Lateral Femoral Condyle Allograft: Is There a Difference in Graft Sources? 
Osteochondral allograft (OCA) transplantation is an effective treatment for defects in the medial femoral condyle (MFC), but the procedure is limited by a shortage of grafts. Lateral femoral condyles (LFCs) differ in geometry from MFCs but may be a suitable graft source. The difference between articular surface locations of the knee can be evaluated with μCT imaging and 3D image analysis.
We tested the hypothesis that LFC OCAs inserted into MFC lesions can provide a cartilage surface match comparable to those provided by MFC allografts by comparing the surgical placement of human MFC and LFC allografts into MFC defects ex-vivo.
Study Design
Controlled laboratory study
20 MFC and 10 LFC were divided into three groups, 10 MFC recipients (MFCr), 10 MFC donors (MFCd) and 10 LFC donors (LFCd). A 20 mm defect was created in the weight-bearing portion of the MFCr. Two grafts, one MFCd and one LFCd, were implanted sequentially into each MFCr recipient condyle. Images of the MFCr using a Skyscan 1076 μCT at 18 μm voxel size were acquired and analyzed to compare the surface contours of the original recipient site with the MFCd- and LFCd-repaired sites. 3D transformations were defined to localize the defect site in the three scans of each MFCr condyle. Vertical heights from each cartilage surface voxel to a plane were determined to delineate the contour of each image. Vertical deviations from each voxel of the graft cartilage surface, relative to the intact recipient cartilage surface, were calculated and assessed as root mean square deviation (sRMS), percent graft area that was proud, sunk, and within the “acceptable” (±1.00mm) distance. The effect of repair (with MFC versus with LFC) on each of the surface match parameters (ARMS, Aacc, A unacc,proud, Aunacc,sunk, hRMS, hacc, h unacc,proud, and hunacc,sunk,) is presented as mean±StDev and was assessed by t-test. Percentage data were arcsin transformed before statistical testing. An alpha level of 0.05 was used to conclude if variations were statistically significant.
MFCr defects were filled using both orthotopic MFCd and non-orthotopic LFCd. Registered μCT images of the MFCr illustrate the cartilage surface contour in the sagittal and coronal planes, in the original intact condyle as well as after OCA repairs. Specimen-specific surface color-maps for the MFCr after implant of the MFCd and after implant of LFCd were generally similar with some deviation near the edges. On average, the MFCr site exhibited a typical contour, and the MFCd and LFCd were slightly elevated. Both types of OCA, MFCd and LFCd, matched well, with overall height deviations of 0.63mm and 0.0.47 for area and stepoff, respectively, with no difference between MFCd and LFCd (p=0.92 and p=0.57, respectively) and acceptable deviation based on area (87.6% overall) and stepoff (96.7% overall) with no significant difference between MFCd and LFCd (p=0.87 and p=0.22, respectively). A small portion of the implant was proud, (12.1% of area and 2.6% of circumference stepoff height) with no significant difference between MFCd and LFCd (p=0.26 and p=0.27, respectively). A very small portion of the implant area and edge was sunk (0.3% of area and 0.6% of circumference) with no significant difference between MFCd and LFCd (p=0.29 and p=0.86, respectively).
The achievement of excellent OCA surface match with either an MFC or LFC donor graft into the common MFC recipient site suggests that non-orthotopic LFC OCA are acceptable graft options for MFC defects.
PMCID: PMC4151880  PMID: 25035174
17.  Bone stress injury of the ankle in professional ballet dancers seen on MRI 
Ballet Dancers have been shown to have a relatively high incidence of stress fractures of the foot and ankle. It was our objective to examine MR imaging patterns of bone marrow edema (BME) in the ankles of high performance professional ballet dancers, to evaluate clinical relevance.
MR Imaging was performed on 12 ankles of 11 active professional ballet dancers (6 female, 5 male; mean age 24 years, range 19 to 32). Individuals were imaged on a 0.2 T or 1.5 T MRI units. Images were evaluated by two musculoskeletal radiologists and one orthopaedic surgeon in consensus for location and pattern of bone marrow edema. In order to control for recognized sources of bone marrow edema, images were also reviewed for presence of osseous, ligamentous, tendinous and cartilage injuries. Statistical analysis was performed to assess the strength of the correlation between bone marrow edema and ankle pain.
Bone marrow edema was seen only in the talus, and was a common finding, observed in nine of the twelve ankles imaged (75%) and was associated with pain in all cases. On fluid-sensitive sequences, bone marrow edema was ill-defined and centered in the talar neck or body, although in three cases it extended to the talar dome. No apparent gender predilection was noted. No occult stress fracture could be diagnosed. A moderately strong correlation (phi = 0.77, p= 0.0054) was found between edema and pain in the study population.
Bone marrow edema seems to be a specific MRI finding in the talus of professional ballet dancers, likely related to biomechanical stress reactions, due to their frequently performed unique maneuvers. Clinically, this condition may indicate a sign of a bone stress injury of the ankle.
PMCID: PMC2329634  PMID: 18371230
18.  Treatment of osteochondral lesions of the talus: a systematic review 
The aim of this study was to summarize all eligible studies to compare the effectiveness of treatment strategies for osteochondral defects (OCD) of the talus. Electronic databases from January 1966 to December 2006 were systematically screened. The proportion of the patient population treated successfully was noted, and percentages were calculated. For each treatment strategy, study size weighted success rates were calculated. Fifty-two studies described the results of 65 treatment groups of treatment strategies for OCD of the talus. One randomized clinical trial was identified. Seven studies described the results of non-operative treatment, 4 of excision, 13 of excision and curettage, 18 of excision, curettage and bone marrow stimulation (BMS), 4 of an autogenous bone graft, 2 of transmalleolar drilling (TMD), 9 of osteochondral transplantation (OATS), 4 of autologous chondrocyte implantation (ACI), 3 of retrograde drilling and 1 of fixation. OATS, BMS and ACI scored success rates of 87, 85 and 76%, respectively. Retrograde drilling and fixation scored 88 and 89%, respectively. Together with the newer techniques OATS and ACI, BMS was identified as an effective treatment strategy for OCD of the talus. Because of the relatively high cost of ACI and the knee morbidity seen in OATS, we conclude that BMS is the treatment of choice for primary osteochondral talar lesions. However, due to great diversity in the articles and variability in treatment results, no definitive conclusions can be drawn. Further sufficiently powered, randomized clinical trials with uniform methodology and validated outcome measures should be initiated to compare the outcome of surgical strategies for OCD of the talus.
PMCID: PMC2809940  PMID: 19859695
Ankle; Osteochondral lesion; Defect; Talus; Systematic review; Arthroscopy
19.  All-Arthroscopic Autologous Matrix-Induced Chondrogenesis for the Treatment of Osteochondral Lesions of the Talus 
Arthroscopy Techniques  2015;4(3):e255-e259.
Several surgical techniques have been described for the treatment of talar chondral lesions. Among them, microfracture is well established. Autologous matrix-induced chondrogenesis (AMIC), using microfracture and biomaterials, has shown promising results for the treatment of knee osteochondral lesions and has been proposed for the ankle as an open technique. We describe an all-arthroscopic AMIC technique. The benefits of an all-arthroscopic procedure include smaller incisions with less soft-tissue dissection, better visualization of the joint, and a quicker recovery compared with open surgery. The use of matrix to support cartilage regeneration promotes good-quality cartilage tissue with satisfactory long-term outcomes. Our all-arthroscopic AMIC technique uses a type I–type III porcine collagen matrix (Chondro-Gide; Geistlich Pharma, Wolhusen, Switzerland) and is characterized by 2 different arthroscopic surgical phases. First, adequate exposure is achieved through use of a Hintermann spreader (Integra LifeSciences, Plainsboro, NJ) with sufficient joint distraction and wet lesion preparation. The second surgical step is performed dry, involving matrix placement and fixation. The all-arthroscopic AMIC technique for the treatment of osteochondral lesions of the talus allows a very precise reconstruction in the case of cartilage defects and avoids the need for a more invasive operation associated with higher morbidity and a longer surgical time.
PMCID: PMC4523902  PMID: 26258040
20.  Sodium Magnetic Resonance Imaging of Ankle Joint in Cadaver Specimens, Volunteers, and Patients After Different Cartilage Repair Techniques at 7 T 
Investigative radiology  2015;50(4):246-254.
The goal of cartilage repair techniques such as microfracture (MFX) or matrix-associated autologous chondrocyte transplantation (MACT) is to produce repair tissue (RT) with sufficient glycosaminoglycan (GAG) content. Sodium magnetic resonance imaging (MRI) offers a direct and noninvasive evaluation of the GAG content in native cartilage and RT. In the femoral cartilage, this method was able to distinguish between RTs produced by MFX and MACT having different GAG contents. However, it needs to be clarified whether sodium MRI can be useful for evaluating RT in thin ankle cartilage. Thus, the aims of this 7-T study were (1) to validate our sodium MRI protocol in cadaver ankle samples, (2) to evaluate the sodium corrected signal intensities (cSI) in cartilage of volunteers, (3) and to compare sodium values in RT between patients after MFX and MACT treatment.
Materials and Methods
Five human cadaver ankle samples as well as ankles of 9 asymptomatic volunteers, 6 MFX patients and 6 MACT patients were measured in this 7-T study. Sodium values from the ankle samples were compared with histochemically evaluated GAG content. In the volunteers, sodium cSI values were calculated in the cartilages of ankle and subtalar joint. In the patients, sodium cSI in RT and reference cartilage were measured, morphological appearance of RT was evaluated using the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system, and clinical outcome before and after surgery was assessed using the American Orthopaedic Foot and Ankle Society score and Modified Cincinnati Knee Scale. All regions of interest were defined on morphological images and subsequently transferred to the corresponding sodium images. Analysis of variance, t tests, and Pearson correlation coefficients were evaluated.
In the patients, significantly lower sodium cSI values were found in RT than in reference cartilage for the MFX (P = 0.007) and MACT patients (P = 0.008). Sodium cSI and MOCART scores in RT did not differ between the MFX and MACT patients (P = 0.185). No significant difference in sodium cSI was found between reference cartilage of the volunteers and the patients (P = 0.355). The patients showed significantly higher American Orthopaedic Foot and Ankle Society and Modified Cincinnati scores after treatment than they did before treatment. In the volunteers, sodium cSI was significantly higher in the tibial cartilage than in the talar cartilage of ankle joint (P = 0.002) and in the talar cartilage than in the calcaneal cartilage of subtalar joint (P < 0.001). Data from the cadaver ankle samples showed a strong linear relationship between the sodium values and the histochemically determined GAG content (r = 0.800; P < 0.001; R2 = 0.639).
This study demonstrates the feasibility of in vivo quantification of sodium cSI, which can be used for GAG content evaluation in thin cartilages of ankle and subtalar joints at 7 T. A strong correlation observed between the histochemically evaluated GAG content and the sodium values proved the sufficient sensitivity of sodium MRI to changes in the GAG content of cartilages in the ankle. Both MFX and MACT produced RT with lower sodium cSI and, thus, of lower quality compared with reference cartilage in the patients or in the volunteers. Our results suggest that MFX and MACT produce RT with similar GAG content and similar morphological appearance in patients with similar surgery outcome. Sodium MRI at 7 T allows a quantitative evaluation of RT quality in the ankle and may thus be useful in the noninvasive assessment of new cartilage repair procedures.
PMCID: PMC4365439  PMID: 25436618
sodium MRI; ankle joint; 7 T; cartilage repair; glycosaminoglycan content
21.  Osteochondral Allograft of the Talus 
Osteochondral lesions of the talus are being recognized as an increasingly common injury. They are most commonly located postero-medially or antero-laterally, while centrally located lesions are uncommon. Large osteochondral lesions have significant biomechanical consequences and often require resurfacing with osteochondral autograft transfer, mosaicplasty, autologous chondrocyte implantation (or similar methods) or osteochondral allograft transplantation. Allograft procedures have become popular due to inherent advantages over other resurfacing techniques. Cartilage viability is one of the most important factors for successful clinical outcomes after transplantation of osteochondral allografts and is related to storage length and intra-operative factors. While there is abundant literature about osteochondral allograft transplantation in the knee, there are few papers about this procedure in the talus. Failure of non-operative management, initial debridement, curettage or microfractures are an indication for resurfacing. Patients should have a functional ankle motion, closed growth plates, absence of cartilage lesions on the tibial side. This paper reviews the published literature about osteochondral allograft transplantation of the talus focusing on indications, pre-operative planning, surgical approaches, postoperative management, results and complications of this procedure.
PMCID: PMC4127728  PMID: 25328456
22.  Bone-Induced Chondroinduction in Sheep Jamshidi Biopsy Defects with and without Treatment by Subchondral Chitosan-Blood Implant 
Cartilage  2013;4(2):131-143.
Delivery of chitosan to subchondral bone is a novel approach for augmented marrow stimulation. We evaluated the effect of 3 presolidified chitosan-blood implant formulations on osteochondral repair progression compared with untreated defects.
In N = 5 adult sheep, six 2-mm diameter Jamshidi biopsy holes were created bilaterally in the medial femoral condyle and treated with presolidified chitosan-blood implant with fluorescent chitosan tracer (10 kDa, 40 kDa, or 150k Da chitosan, left knee) or left to bleed (untreated, right knee). Implant residency and osteochondral repair were assessed at 1 day (N = 1), 3 weeks (N = 2), or 3 months (N = 2) postoperative using fluorescence microscopy, histomorphometry, stereology, and micro–computed tomography.
Chitosan implants were retained in 89% of treated Jamshidi holes up to 3 weeks postoperative. At 3 weeks, biopsy sites were variably covered by cartilage flow, and most bone holes contained cartilage flow fragments and heterogeneous granulation tissues with sparse leukocytes, stromal cells, and occasional adipocytes (volume density 1% to 3%). After 3 months of repair, most Jamshidi bone holes were deeper, remodeling at the edges, filled with angiogenic granulation tissue, and lined with variably sized chondrogenic foci fused to bone trabeculae or actively repairing bone plate. The 150-kDa chitosan implant elicited more subchondral cartilage formation compared with 40-kDa chitosan-treated and control defects (P < 0.05, N = 4). Treated defects contained more mineralized repair tissue than control defects at 3 months (P < 0.05, N = 12).
Bone plate–induced chondroinduction is an articular cartilage repair mechanism. Jamshidi biopsy repair takes longer than 3 months and can be influenced by subchondral chitosan-blood implant.
PMCID: PMC4297102  PMID: 26069656
chitosan; osteochondral repair; micro–computed tomography; large animal model; marrow stimulation; bone plate; chondrogenesis; coagulation; Jamshidi
23.  Intrastromal Corneal Ring Implants for Corneal Thinning Disorders 
Executive Summary
The purpose of this project was to determine the role of corneal implants in the management of corneal thinning disease conditions. An evidence-based review was conducted to determine the safety, effectiveness and durability of corneal implants for the management of corneal thinning disorders. The evolving directions of research in this area were also reviewed.
Subject of the Evidence-Based Analysis
The primary treatment objectives for corneal implants are to normalize corneal surface topography, improve contact lens tolerability, and restore visual acuity in order to delay or defer the need for corneal transplant. Implant placement is a minimally invasive procedure that is purported to be safe and effective. The procedure is also claimed to be adjustable, reversible, and both eyes can be treated at the same time. Further, implants do not limit the performance of subsequent surgical approaches or interfere with corneal transplant. The evidence for these claims is the focus of this review.
The specific research questions for the evidence review were as follows:
Corneal Surface Topographic Effects:
Effects on corneal surface remodelling
Impact of these changes on subsequent interventions, particularly corneal transplantation (penetrating keratoplasty [PKP])
Visual Acuity
Refractive Outcomes
Visual Quality (Symptoms): such as contrast vision or decreased visual symptoms (halos, fluctuating vision)
Contact lens tolerance
Functional visual rehabilitation and quality of life
Patient satisfaction:
Disease Process:
Impact on corneal thinning process
Effect on delaying or deferring the need for corneal transplantation
Clinical Need: Target Population and Condition
Corneal ectasia (thinning) comprises a range of disorders involving either primary disease conditions such as keratoconus and pellucid marginal corneal degeneration or secondary iatrogenic conditions such as corneal thinning occurring after LASIK refractive surgery. The condition occurs when the normally round dome-shaped cornea progressively thins causing a cone-like bulge or forward protrusion in response to the normal pressure of the eye. Thinning occurs primarily in the stoma layers and is believed to be a breakdown in the collagen network. This bulging can lead to an irregular shape or astigmatism of the cornea and, because the anterior part of the cornea is largely responsible for the focusing of light on the retina, results in loss of visual acuity. This can make even simple daily tasks, such as driving, watching television or reading, difficult to perform.
Keratoconus (KC) is the most common form of corneal thinning disorder and is a noninflammatory chronic disease process. Although the specific causes of the biomechanical alterations that occur in KC are unknown, there is a growing body of evidence to suggest that genetic factors may play an important role. KC is a rare condition (<0.05% of the population) and is unique among chronic eye diseases as it has an early age of onset (median age of 25 years). Disease management for this condition follows a step-wise approach depending on disease severity. Contact lenses are the primary treatment of choice when there is irregular astigmatism associated with the disease. When patients can no longer tolerate contact lenses or when lenses no longer provide adequate vision, patients are referred for corneal transplant.
Keratoconus is one of the leading indications for corneal transplants and has been so for the last three decades. Yet, despite high graft survival rates of up to 20 years, there are reasons to defer receiving transplants for as long as possible. Patients with keratoconus are generally young and life-long term graft survival would be an important consideration. The surgery itself involves lengthy time off work and there are potential complications from long term steroid use following surgery, as well as the risk of developing secondary cataracts, glaucoma etc. After transplant, recurrent KC is possible with need for subsequent intervention. Residual refractive errors and astigmatism can remain challenging after transplantation and high refractive surgery rates and re-graft rates in KC patients have been reported. Visual rehabilitation or recovery of visual acuity after transplant may be slow and/or unsatisfactory to patients.
Description of Technology/Therapy
INTACS® (Addition Technology Inc. Sunnyvale, CA, formerly KeraVision, Inc.) are the only currently licensed corneal implants in Canada. The implants are micro-thin poly methyl methacrylate crescent shaped ring segments with a circumference arc length of 150 degrees, an external diameter of 8.10 mm, an inner diameter of 6.77 mm, and a range of different thicknesses. Implants act as passive spacers and, when placed in the cornea, cause local separation of the corneal lamellae resulting in a shortening of the arc length of the anterior corneal curvature and flattening the central cornea. Increasing segment thickness results in greater lamellar separation with increased flattening of the cornea correcting for myopia by decreasing the optical power of the eye. Corneal implants also improve corneal astigmatism but the mechanism of action for this is less well understood.
Treatment with corneal implants is considered for patients who are contact lens intolerant, having adequate corneal thickness particularly around the area of the implant incision site and without central corneal scarring. Those with central corneal scarring would not benefit from implants and those without an adequate corneal thickness, particularly in the region that the implants are being inserted, would be at increased risk for corneal perforation. Patients desiring to have visual rehabilitation that does not include glasses or contact lenses would not be candidates for corneal ring implants.
Placement of the implants is an outpatient procedure with topical anesthesia generally performed by either corneal specialists or refractive surgeons. It involves creating tunnels in the corneal stroma to secure the implants either by a diamond knife or laser calibrated to an approximate depth of 70% of the cornea. Variable approaches have been employed by surgeons in selecting ring segment size, number and position. Generally, two segments of equal thickness are placed superiorly and inferiorly to manage symmetrical patterns of corneal thinning whereas one segment may be placed to manage asymmetric thinning patterns.
Following implantation, the major safety concerns are for potential adverse events including corneal perforation, infection, corneal infiltrates, corneal neovascularization, ring migration and extrusion and corneal thinning. Technical results can be unsatisfactory for several reasons. Treatment may result in an over or under-correction of refraction and may induce astigmatism or asymmetry of the cornea.
Progression of the corneal cone with corneal opacities is also invariably an indication for progression to corneal transplant. Other reasons for treatment failure or patient dissatisfaction include foreign body sensation, unsatisfactory visual quality with symptoms such as double vision, fluctuating vision, poor night vision or visual side effects related to ring edge or induced or unresolved astigmatism.
Evidence-Based Analysis Methods
The literature search strategy employed keywords and subject headings to capture the concepts of 1) intrastromal corneal rings and 2) corneal diseases, with a focus on keratoconus, astigmatism, and corneal ectasia. The initial search was run on April 17, 2008, and a final search was run on March 6, 2009 in the following databases: Ovid MEDLINE (1996 to February Week 4 2009), OVID MEDLINE In-Process and Other Non-Indexed Citations, EMBASE (1980 to 2009 Week 10), OVID Cochrane Library, and the Centre for Reviews and Dissemination/International Agency for Health Technology Assessment. Parallel search strategies were developed for the remaining databases. Search results were limited to human and English-language published between January 2000 and April 17, 2008. The resulting citations were downloaded into Reference Manager, v.11 (ISI Researchsoft, Thomson Scientific, U.S.A), and duplicates were removed. The Web sites of several other health technology agencies were also reviewed including the Canadian Agency for Drugs and Technologies in Health (CADTH), ECRI, and the United Kingdom National Institute for Clinical Excellence (NICE). The bibliographies of relevant articles were scanned.
Inclusion Criteria
English language reports and human studies
Any corneal thinning disorder
Reports with corneal implants used alone or in conjunction with other interventions
Original reports with defined study methodology
Reports including standardized measurements on outcome events such as technical success, safety, effectiveness, durability, vision quality of life or patient satisfaction
Case reports or case series for complications and adverse events
Exclusion Criteria
Non-systematic reviews, letters, comments and editorials
Reports not involving outcome events such as safety, effectiveness, durability, vision quality or patient satisfaction following an intervention with corneal implants
Reports not involving corneal thinning disorders and an intervention with corneal implants
Summary of Findings
In the MAS evidence review on intrastromal corneal ring implants, 66 reports were identified on the use of implants for management of corneal thinning disorders. Reports varied according to their primary clinical indication, type of corneal implant, and whether or not secondary procedures were used in conjunction with the implants. Implants were reported to manage post LASIK thinning and/or uncorrected refractive error and were also reported as an adjunctive intervention both during and after corneal transplant to manage recurrent thinning and/or uncorrected refractive error.
Ten pre-post cohort longitudinal follow-up studies were identified examining the safety and effectiveness of INTAC corneal implants in patients with keratoconus. Five additional cohort studies were identified using the Ferrara implant for keratoconus management but because this corneal implant is not licensed in Canada these studies were not reviewed.
The cohorts implanted with INTACS involved 608 keratoconus patients (754 eyes) followed for 1, 2 or 3 years. Three of the reports involved ≥ 2 years of follow-up with the longest having 5-year follow-up data for a small number of patients. Four of the INTAC cohort studies involved 50 or more patients; the largest involved 255 patients. Inclusion criteria for the studies were consistent and included patients who were contact lens intolerant, had adequate corneal thickness, particularly around the area of the implant incision site, and without central corneal scarring. Disease severity, thinning pattern, and corneal cone protrusions all varied and generally required different treatment approaches involving defined segment sizes and locations.
A wide range of outcome measures were reported in the cohort studies. High levels of technical success or ability to place INTAC segments were reported. Technically related complications were often delayed and generally reported as segment migration attributable to early experience. Overall, complications were infrequently reported and largely involved minor reversible events without clinical sequelae.
The outcomes reported across studies involved statistically significant and clinically relevant improvements in corneal topography, refraction and visual acuity, for both uncorrected and best-corrected visual acuity. Patients’ vision was usually restored to within normal functioning levels and for those not achieving satisfactory correction, insertion of intraocular lenses was reported in case studies to result in additional gains in visual acuity. Vision loss (infrequently reported) was usually reversed by implant exchange or removal. The primary effects of INTACS on corneal surface remodelling were consistent with secondary improvements in refractive error and visual acuity. The improvements in visual acuity and refractive error noted at 6 months were maintained at 1 and 2-year follow-up
Improvements in visual acuity and refractive error following insertion of INTACS, however, were not noted for all patients. Although improvements were not found to vary across age groups there were differences across stages of disease. Several reports suggested that improvements in visual acuity and refractive outcomes may not be as large or predictable in more advanced stages of KC. Some studies have suggested that the effects of INTACs were much greater in flattening the corneal surface than in correcting astigmatism. However, these studies involved small numbers of high risk patients in advanced stages of KC and conclusions made from this group are limited.
INTACS were used for other indications other than primary KC. The results of implant insertion on corneal topography, refraction, and visual acuity in post-LASIK thinning cases were similar to those reported for KC. The evidence for this indication, however, only involved case reports and small case series. INTACS were also successfully used to treat recurrent KC after corneal transplant but this was based on only a single case report. Corneal implants were compared to corneal transplantation but these studies were not randomized and based on small numbers of selected patients.
The foremost limitation of the evidence base is the basic study design in the reports that involved longitudinal follow-up only for the treated group; there were no randomized trials. Follow-up in the trials (although at prescribed intervals) often had incomplete accounts of losses at follow-up and estimates of change were often not reported or based on group differences. Second, although standardized outcome measures were reported, contact lens tolerance (a key treatment objective) was infrequently specified. A third general limitation was the lack of reporting of patients’ satisfaction with their vision quality or functional vision. Outcome measures for vision quality and impact on patient quality of life were available but rarely reported and have been noted to be a limitation in ophthalmological literature in general. Fourth, the longitudinal cohort studies have not followed patients long enough to evaluate the impact of implants on the underlying disease process (follow-up beyond 3 years is limited). Additionally, only a few of these studies directly examined corneal thinning in follow-up. The overall quality of evidence determined using the GRADE hierarchy of evidence was moderate.
There is some evidence in these studies to support the claim that corneal implants do not interfere with, or increase the difficultly of, subsequent corneal transplant, at least for those performed shortly after INTAC placement. Although it’s uncertain for how long implants can delay the need for a corneal transplant, given that patients with KC are often young (in their twenties and thirties), delaying transplant for any number of years may still be a valuable consideration.
The clinical indications for corneal implants have evolved from management of myopia in normal eyes to the management of corneal thinning disorders such as KC and thinning occurring after refractive surgery. Despite the limited evidence base for corneal implants, which consists solely of longitudinal follow-up studies, they appear to be a valuable clinical tool for improving vision in patients with corneal thinning. For patients unable to achieve functional vision, corneal implants achieved statistically significant and clinically relevant improvements in corneal topography, refraction, and visual acuity, providing a useful alternative to corneal transplant. Implants may also have a rescue function, treating corneal thinning occurring after refractive surgery in normal eyes, or managing refractive errors following corneal transplant. The treatment offers several advantages in that it’s an outpatient based procedure, is associated with minimal risk, and has high technical success rates. Both eyes can be treated at once and the treatment is adjustable and reversible. The implants can be removed or exchanged to improve vision without limiting subsequent interventions, particularly corneal transplant.
Better reporting on vision quality, functional vision and patient satisfaction, however, would improve evaluation of the impact of these devices. Information on the durability of the implants’ treatment effects and their affects on underlying disease processes is limited. This information is becoming more important as alternative treatment strategies, such as collagen cross-linking aimed at strengthening the underlying corneal tissue, are emerging and which might prove to be more effective or increase the effectiveness of the implants, particularly in advances stages of corneal thinning.
Ontario Health System Considerations
At present there are approximately 70 ophthalmologists in Canada who’ve had training with corneal implants; 30 of these practice in Ontario. Industry currently sponsors the training, proctoring and support for the procedure. The cost of the implant device ranges from $950 to $1200 (CAD) and costs for instrumentation range from $20,000 to $30,000 (CAD) (a one time capital expenditure). There is no physician services fee code for corneal implants in Ontario but assuming that they are no higher than those for a corneal transplant, the estimated surgical costs would be $914.32(CAD) An estimated average cost per patient, based on device costs and surgical fees, for treatment is $1,964 (CAD) (range $1,814 to $2,114) per eye. There have also been no out of province treatment requests. In Ontario the treatment is currently being offered in private clinics and an increasing number of ophthalmologists are being certified in the technique by the manufacturer.
KC is a rare disease and not all of these patients would be eligible candidates for treatment with corneal implants. Based on published population rates of KC occurrence, it can be expected that there is a prevalent population of approximately 6,545 patients and an incident population of 240 newly diagnosed cases per year. Given this small number of potential cases, the use of corneal implants would not be expected to have much impact on the Ontario healthcare system. The potential impact on the provincial budget for managing the incident population, assuming the most conservative scenario (i.e., all are eligible and all receive bilateral implants) ranges from $923 thousand to $1.1 million (CAD). This estimate would vary based on a variety of criteria including eligibility, unilateral or bilateral interventions, re-interventions, capacity and uptake
Keratoconus, corneal implants, corneal topography, corneal transplant, visual acuity, refractive error
PMCID: PMC3385416  PMID: 23074513
24.  Spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect created in the femoral condyle using a novel double-network hydrogel 
Functional repair of articular osteochondral defects remains a major challenge not only in the field of knee surgery but also in tissue regeneration medicine. The purpose is to clarify whether the spontaneous hyaline cartilage regeneration can be induced in a large osteochondral defect created in the femoral condyle by means of implanting a novel double-network (DN) gel at the bottom of the defect.
Twenty-five mature rabbits were used in this study. In the bilateral knees of each animal, we created an osteochondral defect having a diameter of 2.4-mm in the medial condyle. Then, in 21 rabbits, we implanted a DN gel plug into a right knee defect so that a vacant space of 1.5-mm depth (in Group I), 2.5-mm depth (in Group II), or 3.5-mm depth (in Group III) was left. In the left knee, we did not apply any treatment to the defect to obtain the control data. All the rabbits were sacrificed at 4 weeks, and the gross and histological evaluations were performed. The remaining 4 rabbits underwent the same treatment as used in Group II, and real-time PCR analysis was performed at 4 weeks.
The defect in Group II was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen. The Wayne's gross appearance and histology scores showed that Group II was significantly greater than Group I, III, and Control (p < 0.012). The relative expression level of type-2 collagen, aggrecan, and SOX9 mRNAs was significantly greater in Group II than in the control group (p < 0.023).
This study demonstrated that spontaneous hyaline cartilage regeneration can be induced in vivo in an osteochondral defect created in the femoral condyle by means of implanting the DN gel plug at the bottom of the defect so that an approximately 2-mm deep vacant space was intentionally left in the defect. This fact has prompted us to propose an innovative strategy without cell culture to repair osteochondral lesions in the femoral condyle.
PMCID: PMC3050780  PMID: 21338528
25.  Osteochondral regeneration with a novel aragonite-hyaluronate biphasic scaffold: up to 12-month follow-up study in a goat model 
The regeneration of articular hyaline cartilage remains an elusive goal despite years of research. Recently, an aragonite-hyaluronate (Ar-HA) biphasic scaffold has been described capable of cartilage regeneration over a 6-month follow-up period. This study was conducted in order to assess the fate of the regenerated osteochondral tissue in a 12-month-long validated caprine model.
The hypothesis was that the implantation of the Ar-HA implant leads to tissue regeneration and maturation.
Study design
A two-arm caprine model of a critical osteochondral defect compares the fate of acute osteochondral defects (group A) to Ar-HA implanted defects (group B).
Critical 6 mm in diameter and 10-mm in depth osteochondral defects were created in the load-bearing medial femoral condyle of 20 mature goats and randomized into two groups. In group A (n = 6), a blood clot spontaneously filled the defect; in group B (n = 14), a single Ar-HA implant reconstructed the defect. The animals were sacrificed after either 6 or 12 months. Parameters assessed included clinical evaluation, x-rays, micro-CT, ultrasound and histology at both time points, and specimen high-field magnetic resonance imaging with T2 mapping at the 12-month time point.
In most group A animals, the defects were not reconstructed (1/3 at 6 months, and 0/3 at 12 months). Defects in group B were mostly reconstructed (5/7 at 6 months and 6/7 at 12 months). Group A defects were either empty or contained fibrous repair tissue; while group B filling was compatible with hyaline cartilage and normal bone.
Ar-HA scaffolds implanted in critical osteochondral defects result in hyaline cartilage formation and subchondral bone regeneration. The results improved at the 12-month time point compared to the 6-month time point, indicating a continuous maturation process without deterioration of the repair tissue.
Clinical relevance
Osteochondral defects are common in humans; the results of the current study suggest that an acellular Ar-HA scaffold might induce cartilage and subchondral bone regeneration.
PMCID: PMC4486417  PMID: 26018574
Osteochondral defect; Cartilage regeneration; Aragonite-hyaluronate; Agili-C

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