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Year of Publication
1.  [No title available] 
PMCID: PMC3692610  PMID: 23370983
2.  All-inside suture device is superior to meniscal arrows in meniscal repair: a prospective randomized multicenter clinical trial with 2-year follow-up 
Purpose
Multiple techniques and implants are available for all-inside meniscal repair, but the knowledge about their failure rates and functional outcome is still incomplete. The hypothesis was that there might be differences between meniscal arrows and suture devices regarding reoperation rates and functional outcome. Thereby, the aim of this study was to compare clinical results following repair with the Biofix® arrows or the FasT-Fix® suture devices.
Methods
In this RCT, 46 patients were treated either by Biofix® (n = 21) or FasT-Fix® (n = 25). The main outcome was reoperation within 2 years. Knee function and activity level were evaluated by KOOS and Tegner activity scale.
Results
Twelve out of 46 (26 %) patients were reoperated within 2 years, nine out of 21 (43 %) in the Biofix®-group versus three out of 25 (12 %) in the FasT-Fix®-group (p = 0.018). The relative risk of reoperation was 3.6 times higher for Biofix® compared to FasT-Fix® (95 % confidence interval 1.1–11.5). Both treatment groups had significant increase in all KOOS subscales, but there were no major differences between the groups. The subgroup of reoperated patients differed from the other patients with higher Tegner score preoperatively (median 5 vs. 4) (p = 0.037) and at 3-month follow-up (median 4 vs. 3) (p = 0.010).
Conclusions
These results indicate that FasT-Fix® suture is superior to Biofix® arrows with significant lower failure rate. Functional outcome did not depend on repair technique. Higher activity score preoperatively and at 3-month follow-up in the reoperated patients indicates that activity level may influence on the risk of reoperation.
Level of evidence
I.
doi:10.1007/s00167-014-3423-5
PMCID: PMC4284382  PMID: 25381468
All-inside; Meniscal repair; Meniscal suture; Meniscus arrow; Biofix®; FasT-Fix®
3.  Sex comparison of familial predisposition to anterior cruciate ligament injury 
Purpose
In an effort to identify risk factors for anterior cruciate ligament (ACL) injury, many potential risk factors have been proposed, including familial predisposition. However, no study has evaluated familial predisposition in male or females separately. The purpose of this study was to determine whether a familial predisposition to ACL injury exists in both males and females.
Methods
One hundred and twenty (78 males and 42 females) patients who had undergone surgical ACL reconstruction were recruited as the ACL group, and 107 patients (67 males and 40 females) that had undergone arthroscopic partial menisectomy, with no previous history of ACL injury, were recruited as the referent control group. A familial ACL injury and subject particulars questionnaire was completed.
Results
When all subjects were combined, the ACL group (20.0 %, 24 of 120) did not demonstrate a higher familial (first-degree relative) prevalence (n.s.) of ACL injury compared to the referent control group (15.0 %; 16 of 107 patients). When the data were stratified by sex, the male ACL group (19.2 %, 15 of 78) demonstrated a significantly higher familial (first-degree relative) prevalence (P = 0.02) of ACL injury compared to the male referent control group (7.5 %; 5 of 67 patients). There were no differences among the females (n.s.).
Discussion
The results of this study show that male patients with ACL tears are more likely to have a first-degree relative with an ACL tear compared to male referent control subjects. Future research is warranted to better delineate sex-specific risk factors for ACL injuries could help guide intervention programs aimed at preventative treatment strategies, especially in high-risk families.
doi:10.1007/s00167-013-2822-3
PMCID: PMC4217283  PMID: 24402048
Genetics and sport; Genetics and neuromuscular performance; Family history of injury; Injury prevention
4.  Tibial base design and patient morphology affecting tibial coverage and rotational alignment after total knee arthroplasty 
Purpose
To understand interactions between total knee arthroplasty tibial base design attributes, variations in tibial morphology, and the resulting tibial coverage and rotational alignment.
Methods
Tibial anthropometric measurements, including aspect ratio (medial–lateral width/anterior–posterior length) and tibial asymmetry, were taken for 14,791 total knee arthroplasty patients and compared with the ability of four different commercial tibial base designs to cover the resected plateau. The anthropometric measurements were also compared with the resulting tibial base rotation, which occurred when rotating the base to maximize coverage.
Results
All four tibial base designs resulted in similar coverage ranging from 80.2 (4.7) % to 83.8 (4.6) %. Mean tibial base rotation when placed to maximize coverage ranged from 3.7 (4.4)° (internal) to 3.8 (4.5)° (external) relative to the medial third of the tibial tubercle. More asymmetric tibiae and tibiae with a lower aspect ratios resulted in increased internal tibial base rotation.
Conclusions
The four tibial base designs assessed provided similar levels of tibial bone coverage across the patient population, despite different design features. Rotating the tibial base to maximize coverage did not significantly increase the tibial coverage, but induced variability in tibial base alignment. Certain tibial anthropometrics may predispose particular patients to internal tibial base mal-rotation.
doi:10.1007/s00167-014-3402-x
PMCID: PMC4237925  PMID: 25358691
Total knee arthroplasty; Tibial coverage; Tibial anthropometrics; Surgical technique
5.  Compensatory muscle activation caused by tendon lengthening post Achilles tendon rupture 
Purpose
The purpose of this study was to establish a relationship between the lengthening of the Achilles tendon post rupture and surgical repair to muscle activation patterns during walking in order to serve as a reference for post-surgical assessment.
Method
The Achilles tendon lengths were collected from 4 patients with an Achilles tendon rupture 6 and 12 month post-surgery along with 5 healthy controls via ultrasound. EMG was collected from the triceps surae muscles and tibialis anterior during over-ground walking.
Results
Achilles lengths at 6 and 12 months post-surgery were significantly longer (p < 0.05) on the involved side compared to the uninvolved side but there were no side to side differences in the healthy controls. The integrated EMG (iEMG) of the involved side was significantly higher than the uninvolved side in the lateral gastrocnemius at 6 months and for the medial gastrocnemius at 12 months in the patients with Achilles tendon rupture; no side to side difference was found in the healthy controls. The triceps surae muscles’ activations were fair to moderately correlated to the Achilles lengths (0.38 < r < 0.52).
Conclusions
The increased Achilles tendon length and iEMG from the triceps surae muscles indicate that loss of function is primarily caused by anatomical changes in the tendon and the appearance of muscle weakness is due to a lack of force transmission capability. This study indicates that when aiming for full return of function and strength an important treatment goal appears to be to minimize tendon elongation.
Level of evidence
Prognostic prospective case series. Level IV.
doi:10.1007/s00167-013-2512-1
PMCID: PMC3778146  PMID: 23609529
EMG; gait; neural inhibition; surgery; ankle
6.  Femoral and tibial insert downsizing increases the laxity envelope in TKA 
Purpose
This study examines the effect of component downsizing in a modern total knee arthroplasty (TKA) system on the laxity envelope of the knee throughout flexion.
Methods
A robotic testing system was utilized to measure laxity envelopes in the implanted knee by in the anterior–posterior (AP), medial–lateral (ML), internal–external (IE) and varus–valgus (VV) directions. Five fresh-frozen cadavers were tested with a modern cruciate retaining TKA implantation, a 1-mm thinner polyethylene insert and a femoral component 2 mm smaller in the AP dimension.
Results
The downsized tibial insert was more lax throughout the flexion arc with up to 2.0 mm more laxity in the AP direction at full extension, a 43.8 % increase over the original implantation. A thinner insert consistently increased laxity throughout the arc of flexion in all degrees of freedom. Downsizing the femoral component resulted in 8.5 mm increase in AP laxity at 90°, a 73.9 % increase. In mid-flexion, downsizing the femur produced similar laxity values to the downsized insert in AP, ML, IE and VV directions.
Conclusion
Downsizing the TKA components had significant effects on laxity throughout flexion. Downsizing a femoral component 2 mm had an equivalent increase in laxity in mid-flexion as downsizing the tibial insert 1 mm. This study quantifies the importance of choosing the appropriate implant component size, having the appropriate size available and the effect of downsizing. The laxity of the implanted knee contributes to how the implant feels to the patient and ultimately the patient’s satisfaction with their new knee.
doi:10.1007/s00167-014-3339-0
PMCID: PMC4237933  PMID: 25274088
Knee; Total knee arthroplasty; Kinematics; Laxity; Cadaver; Robotic testing
7.  A morphometric study of normal and varus knees 
Purpose
The aim of the study was to investigate varus and normal knee morphologies to identify differences that may affect knee replacement alignment or design for varus knees.
Methods
Computed tomography scans of varus and normal knees were analyzed, and geometric shapes, points and axes were fit to the femur and tibia independently. These points were then projected in the three anatomical planes to measure the variations between the two groups.
Results
In the femur, varus knees had less femoral anteversion (p < 0.0001) and a larger medial extension facet (p < 0.05) compared with normal knees. In the tibia, the tubercle was found to be externally rotated in varus knees (12°), with a significant increase in the coronal slope (p = 0.001) and the extension facet angle (p = 0.002).
Conclusions
The study highlighted the differences and similarities found between the two groups, which raises awareness on changes required during surgical intervention and component placement or design for a varus knee. This is particularly relevant for the design of patient-specific instrumentation and implants.
Levels of evidence
Diagnostic study, Level III.
doi:10.1007/s00167-014-3337-2
PMCID: PMC4237928  PMID: 25261224
Morphometry; Varus knee; Morphology; Rotational alignment; Axes
8.  Landing adaptations following isolated lateral meniscectomy in athletes 
Purpose
Objective functional outcomes following isolated radial lateral meniscus tears in the athlete between the ages of 14–25 are not clearly defined. The objective of this study was to determine whether patients following lateral meniscectomy demonstrate lower extremity asymmetries relative to control athletes 3 months after surgery. We hypothesized that following lateral meniscectomy, athletes aged 14–25 years old would demonstrate altered landing biomechanics compared to sex, age, height, weight, and sport-matched controls.
Methods
A total of 18 subjects were included in this study. Nine patients (7 men and 2 women, 20.1 ± 2.8 years) who had undergone first-time isolated radial lateral meniscus tears were tested 3 months following partial lateral meniscectomies and compared to nine sex, age, height, weight, and sport-matched controls (7 men and 2 women, 19.7 ± 3.1 years). A ten-camera motion analysis system and two force platforms were used to collect three trials of bilateral drop landings. A 2X2 ANOVA was used to test the interaction between side (involved vs. uninvolved) and group (patient vs. control).
Results
The patient group landed with a decreased internal knee extensor moment compared to the uninvolved side and controls (interaction P < 0.05). The involved limb quadriceps isokinetic torque was not decreased compared to the contralateral or control (n.s.). Decreased knee extensor moments were significantly associated with reduced measures of function (IKDC scores: r = 0.69; P < 0.05).
Conclusions
Athletes who return to sport at approximately 3 months following a partial lateral meniscectomy may employ compensation strategies during landing as evidenced by reduced quadriceps recruitment and functional outcome scores. Clinicians should focus on improving quadriceps function during landing on the involved leg in an attempt to decrease residual limb asymmetries.
Level of evidence
Case–control study, Level III.
doi:10.1007/s00167-011-1490-4
PMCID: PMC4166406  PMID: 21468616
Landing biomechanics; Knee surgery; Knee function; Case–control study
9.  Relationship of anterior knee laxity to knee translations during drop landings: a bi-plane fluoroscopy study 
Purpose
Passive anterior knee laxity has been linked to non-contact ACL injury risk. High deceleration movements have been implicated in the non-contact ACL injury mechanism, and evidence suggests that greater anterior tibial translations (ATT) may occur in healthy knees that are lax compared to a tight knee. The purpose of this study was to determine the relationship between anterior knee laxity scores and ATT during drop landings using biplane fluoroscopy.
Methods
Sixteen healthy adults (10 women; 6 men) performed stiff drop landings (40 cm) while being filmed using a high-speed, biplane fluoroscopy system. Initial, peak and excursions for rotations and translations were calculated and regression analysis used to determine the 6DoF kinematic relationships with KT1000 scores with peak ATT occurring during the landing.
Results
KT1000 values were (+) correlated with peak ATT values for group (r = 0.89; P < 0.0001) and both genders (males, r = 0.97; P = 0.0003; females, r = 0.93; P = < 0.0001). Regression analysis yielded a significant linear fit for the group (r2 = 0.80; YATT-group = −0.516 + 1.2 × XKT1000-group) and for each gender (females: r2 = 0.86; YATT-females = 0.074 + 1.2 × XKT1000-females and males: r2 = 0.94; YATT-males = −0.79 + 1.2 × XKT1000-males).
Conclusion
A strong relationship was observed between passive anterior knee laxity measured via KT1000 and peak ATT experienced during dynamic activity in otherwise healthy persons performing a stiff drop-landing motion.
doi:10.1007/s00167-010-1327-6
PMCID: PMC4166423  PMID: 21153545
ACL; Landing; Anterior tibial translation; Biomechanics
10.  Anatomic tibial component design can increase tibial coverage and rotational alignment accuracy: a comparison of six contemporary designs 
Purpose
The aim of this study was to comprehensively evaluate contemporary tibial component designs against global tibial anatomy. We hypothesized that anatomically designed tibial components offer increased morphological fit to the resected proximal tibia with increased alignment accuracy compared to symmetric and asymmetric designs.
Methods
Using a multi-ethnic bone dataset, six contemporary tibial component designs were investigated, including anatomic, asymmetric, and symmetric design types. Investigations included (1) measurement of component conformity to the resected tibia using a comprehensive set of size and shape metrics; (2) assessment of component coverage on the resected tibia while ensuring clinically acceptable levels of rotation and overhang; and (3) evaluation of the incidence and severity of component downsizing due to adherence to rotational alignment and overhang requirements, and the associated compromise in tibial coverage. Differences in coverage were statistically compared across designs and ethnicities, as well as between placements with or without enforcement of proper rotational alignment.
Results
Compared to non-anatomic designs investigated, the anatomic design exhibited better conformity to resected tibial morphology in size and shape, higher tibial coverage (92 % compared to 85–87 %), more cortical support (posteromedial region), lower incidence of downsizing (3 % compared to 39–60 %), and less compromise of tibial coverage (0.5 % compared to 4–6 %) when enforcing proper rotational alignment.
Conclusions
The anatomic design demonstrated meaningful increase in tibial coverage with accurate rotational alignment compared to symmetric and asymmetric designs, suggesting its potential for less intra-operative compromises and improved performance.
Level of evidence
III.
doi:10.1007/s00167-014-3282-0
PMCID: PMC4237921  PMID: 25217314
Total knee arthroplasty; Tibia; Fit; Morphology; Compromise; Rotational alignment; Coverage; Overhang
11.  Time from ACL injury to reconstruction and the prevalence of additional intra-articular pathology: Is patient age an important factor? 
Purpose
Meniscus and cartilage lesions have been reported to be prevalent during delayed reconstruction of ACL injuries. Relatively little work has been done exploring the influence of patient age on this relationship. The purpose of this study is to determine whether the effect of time from ACL injury to reconstruction on the prevalence of associated meniscal and chondral injury is influenced by patient age. It was hypothesized that patients in whom the time from ACL injury to reconstruction exceeds 12 weeks will exhibit an increased prevalence of medial compartment pathology relative to those reconstructed within 12 weeks of injury in patients of all ages.
Methods
Data detailing time from ACL injury to reconstruction and the prevalence of intra-articular findings were obtained in 311 of 489 consecutive patients undergoing primary isolated ACL reconstruction. Patients were divided into two groups based on whether the time from ACL injury to reconstruction was less than 12 weeks or at least 12 weeks. The prevalence of associated intra-articular injury was then compared between the two groups. Patients were then stratified based on age (22 years and under versus over age 22) and the analysis was repeated on both groups.
Results
Analysis of all patients together revealed a significantly higher prevalence of medial meniscus injury (p = 0.013) and medial compartment chondral injury (p < 0.0005) in patients in whom the time from ACL injury to reconstruction exceeded 12 weeks. The prevalence of lateral meniscal injury did not increase with increasing time ACL injury to surgery. Among patients age 22 and under, there was no increase in the prevalence of intra-articular pathology in any compartment in the late reconstruction group. In contrast, among patients over age 22, there was a significant increase in the prevalence of medial chondral injury (p = 0.042) in the late reconstruction group.
Conclusion
The prevalence of injuries to the meniscus and articular cartilage in the medial compartment of the knee is increased with increasing time from ACL injury to reconstruction. This relationship may vary depending on patient age. Patients over age 22 exhibit a higher prevalence of intra-articular injury with delayed reconstruction, while no such differences are noted among younger patients.
doi:10.1007/s00167-013-2380-8
PMCID: PMC3652911  PMID: 23334624
ACL reconstruction; chronicity; meniscus injury; chondral injury
12.  Retention of the posterior cruciate ligament does not affect femoral rotational alignment in TKA using a gap-balance technique 
Purpose
Previous studies have evaluated the ability of the gap technique to achieve accurate rotational placement in both posterior cruciate ligament (PCL)-retaining and PCL-substituting total knee arthroplasty (TKA). The purpose of the present study was to determine (1) the accuracy of this technique in degrees and (2) whether retention of the PCL affects the rotational alignment of the femoral component relative to the transepicondylar axis during TKA. The hypothesis of this study was that retention of the PCL does not affect the femoral rotational alignment in TKA using a gap-balancing technique because both procedures are reported to have good long-term clinical outcomes.
Methods
The femoral rotation angle (FRA) relative to the transepicondylar axis was examined in 206 patients who underwent primary TKA using either PCL-retaining (104 knees) or PCL-substituting (102 knees) prostheses to determine the effect of PCL retention on FRA. Quantitative three-dimensional computed tomography was used to assess the FRA in both groups. All values are expressed as median (25th percentile, 75th percentile).
Results
Postoperative FRA in the PCL-retaining group was −1.1° (−2.8°, 2.2°) and in the PCL-substituting group was −0.1° (−2.5°, 2.8°). The groups were not statistically different. One outlier was found in the PCL-retaining group, and none was found in the PCL-substituting group.
Conclusions
The gap technique reliably allows accurate rotational alignment of the femoral component during TKA despite the retention of the PCL.
Level of evidence
Therapeutic study, Level II.
doi:10.1007/s00167-014-3218-8
PMCID: PMC4237913  PMID: 25119053
PCL retention; Femoral rotational alignment; TKA; Gap-balance technique
13.  Return to sport after patellar dislocation or following surgery for patellofemoral instability 
Patellofemoral instability may occur in a young population as a result of injury during sporting activities. This review focuses on return to sport after one episode of dislocation treated no operatively and as well after surgery for chronic patellofemoral instability. With or without surgery, only two-thirds of patients return to sports at the same level as prior to injury. A high-quality rehabilitation programme using specific exercises is the key for a safe return to sporting activities. To achieve this goal, recovery of muscle strength and dynamic stability of the lower limbs is crucial. The focus should be directed to strengthen the quadriceps muscle and pelvic stabilizers, as well as lateral trunk muscle training. Patient education and regularly performed home exercises are other key factors that can lead to a successful return to sports. The criteria for a safe return to sports include the absence of pain, no effusion, a complete range of motion, almost symmetrical strength, and excellent dynamic stability.
Level of evidence IV.
doi:10.1007/s00167-014-3172-5
PMCID: PMC4169614  PMID: 25047793
Patellofemoral; Return to play; Rehabilitation; Dislocation; Dynamic stability
14.  Increased shape and size offerings of femoral components improve fit during total knee arthroplasty 
Purpose
Contemporary total knee arthroplasty femoral component designs offer various degrees of fit amongst the global population. The purpose of this study was to assess component fit of contemporary femoral component design families against multiple ethnicities.
Methods
Using a multi-ethnic dataset including Caucasian, Indian, and Korean subjects, this study investigated component fit in six contemporary femoral component design families (A: Persona™, B: NexGen®, C: Sigma®, D: GENESIS™ II, E: Triathlon®, F: Vanguard®). Component overhang/underhang was measured between the resected distal femur and its corresponding component size and compared across design families and ethnicities. The severity of overhang/underhang and propensity of downsizing due to clinically significant overhang were quantified for the overall dataset and each ethnicity.
Results
In all the overhang cases, Designs A and B had significantly lower component overhang than the other designs (p < 0.02). In all the underhang cases, Designs C and E had significantly greater underhang than the other designs (p < 0.01). Component design influenced the occurrence (% bones) of component downsizing due to clinically significant overhang (>3 mm), with the highest incidence observed in Designs D (20.5 %) and F (17.7 %), and the lowest incidence observed in Designs A (0 %) and B (0.4 %). Variation in component fit was significantly impacted by designs (p < 0.01) but not ethnicities (n.s.).
Conclusions
The inclusion of multiple ML/AP shape offerings and the increased number of available sizes in Design A, as compared to other contemporary femoral component design families studied, result in improved femoral component fit across various ethnicities.
doi:10.1007/s00167-014-3163-6
PMCID: PMC4237918  PMID: 25026932
TKA; Femoral component; Morphological fit; Overhang
15.  Symmetry Restoration and Functional Recovery before and after Anterior Cruciate Ligament Reconstruction 
Purpose
The aims of this study were to evaluate the functional recovery before and after ACL reconstruction and to evaluate the sensitivity to change in performance-based and self-report outcomes prior to and after ACL reconstruction and to determine if these changes represent clinically relevant improvement.
Methods
Eighty-three athletes participated in this study. Athletes were tested after an ACL injury, after pre-operative training, and 6 and 12 months after ACL reconstruction. Athletes completed quadriceps strength testing, hop testing, and self-reported questionnaires for knee function (International Knee Documentation Committee subjective knee form, Knee Outcome Survey-Activities of Daily Living Scale, and the Global Rating Scale of Perceived Function) at each testing period.
Results
A significant interaction of limb by time was seen in normalized quadriceps strength, and single, triple, and 6-meter timed hop, where the involved limb improved more than the uninvolved limb over time. A main effect of time was noted for performance-based limb symmetry indexes and self-report measures.
Conclusion
Limb-to-limb asymmetries are reduced and normal limb symmetry is restored after perturbation training and aggressive quadriceps strengthening and returned to similar levels 6 months after reconstruction. Performance-based values on the involved limb and self-reported outcomes are sensitive to change over time and these were clinically relevant improvements.
Level of evidence
Level II prognostic study
doi:10.1007/s00167-012-1929-2
PMCID: PMC3381049  PMID: 22349604
Knee surgery; Anterior cruciate ligament; functional recovery; performance-based measures; self-reported outcomes
16.  Radiographic parameters associated with lateral patella degeneration in young patients 
Purpose
Localized articular cartilage degeneration in the patellofemoral joint is a common but yet understudied condition in younger patients. The purpose of this paper was to determine whether there are significant differences in radiographic alignment between those with and without isolated lateral patellofemoral degeneration.
Methods
Subjects with isolated symptomatic lateral patellofemoral degeneration and control subjects with no radiographic degeneration participated in the study. Variables of interest included the Caton-Deschamps index, sulcus angle, lateral patellofemoral angle, Dejour classification of trochlear dysplasia, patella linear displacement and the tibial tubercle-trochlear groove distance.
Results
We found significant differences between the patellofemoral degeneration group versus control group, respectively, for the Caton-Deschamps index (1.12 ± 0.1 vs. 1.00 ± 0.1), lateral patellofemoral angle (10.6 ± 4.3 vs. 16.6 ± 5.5) and tibial tubercle-trochlear groove distance (16.6 ± 4.0 vs. 9.0 ± 4.3). However, we found no difference in the sulcus angle (141.2 ± 8.2 vs. 137.0 ± 6.0), patella linear displacement (3.7 ± 1.9 vs. 4.0 ± 1.7) or in the Dejour Classification.
Conclusion
It appears that isolated lateral patellofemoral degeneration is associated with specific radiographic indices. Even though the radiographic measures in patients with degeneration may not be considered pathologic, they are “high normal” and may represent a risk factor for the development of focal chondral degeneration in the lateral trochlea and patella.
doi:10.1007/s00167-012-1884-y
PMCID: PMC3964584  PMID: 22258652
Patellofemoral; Patellofemoral osteoarthritis; Radiographic alignment; Knee
17.  Microfracture technique versus osteochondral autologous transplantation mosaicplasty in patients with articular chondral lesions of the knee: a prospective randomized trial with long-term follow-up 
Purpose
To compare long-term functional and radiological outcome following microfracture technique (MF) versus osteochondral autologous transplantation (OAT) mosaicplasty for treating focal chondral lesions of the knee.
Methods
Twenty-five patients (mean age 32.3 years, SD 7.7) with a full-thickness (International Cartilage Repair Society grade 3 or 4) chondral lesion of the articulating surface of the femur were randomized to either MF (n = 11) or OAT mosaicplasty (n = 14). At a median follow-up of 9.8 years (range 4.9–11.4), the patients were evaluated using Lysholm score (n = 25), Knee Injury and Osteoarthritis Outcome Score (KOOS, n = 25), isokinetic quadriceps measurement and hamstring strength measurement (n = 22) and standing radiographs (n = 23).
Results
There were no significant differences in Lysholm score, KOOS, isokinetic muscle strength or radiographic osteoarthritis between MF-treated patients and OAT mosaicplasty-treated patients at follow-up. Mean Lysholm score at follow-up was 69.7 [95 % confidence interval (CI), 55.1–84.4] for the MF group and 62.6 (95 % CI, 52.6–72.6) for the OAT mosaicplasty group.
Conclusion
At long-term follow-up, there were no significant differences between patients treated with MF and patients treated with OAT mosaicplasty in patient-reported outcomes, muscle strength or radiological outcome.
Level of evidence
Therapeutic study, Level II.
doi:10.1007/s00167-014-2843-6
PMCID: PMC4028546  PMID: 24441734
Chondral lesion; Microfracture; Mosaicplasty; Long-term follow-up; Lysholm; KOOS
18.  No difference in blood loss between posterior-cruciate-ligament-retaining and posterior-cruciate-ligament-stabilized total knee arthroplasties 
Purpose
Posterior-cruciate-ligament-retaining (PCR) and posterior-cruciate-ligament-stabilized (PS) arthroplasties are two major common practices in total knee arthroplasty (TKA). The hypothesis of the present study was that compared with the PCR technique, the PS technique is associated with a higher amount of postoperative blood loss and greater need for blood transfusion in cemented TKA.
Methods
In this prospective, randomized study, 100 patients diagnosed with primary knee osteoarthritis were randomly assigned to either the PCR group (Group I) or the PS group (Group II). The exclusion criteria were rheumatological joint disease, previous knee surgery, anticoagulant therapy and hypertension. There were no significant differences in age, body mass index and gender, between the groups. The haemoglobin and haematocrit levels of each patient were recorded preoperatively and on postoperative days 1, 3 and 5. The postoperative suction drainage and blood transfusion volumes were also recorded.
Results
There were no statistically significant differences in haemoglobin or haematocrit levels between the groups on postoperative days 1, 3 and 5. There were also no statistically significant differences in the total measured blood loss volume, postoperative drainage amounts or transfusion rates between the groups.
Conclusion
Use of the PS technique during cemented TKA does not appear to influence the amount of perioperative blood loss or the need for postoperative blood transfusion in general. The clinical relevance of this study is that the difference in blood loss between the PCR and PS techniques does not need to be considered by surgeons when performing TKA.
Level of evidence
I.
doi:10.1007/s00167-013-2818-z
PMCID: PMC4104005  PMID: 24384945
Total knee arthroplasty; Posterior cruciate ligament substituting; Drainage; Blood loss
19.  Patellofemoral pain syndrome 
The patellofemoral pain syndrome (PFPS) is a possible cause for anterior knee pain, which predominantly affects young female patients without any structural changes such as increased Q-angle or significant chondral damage. This literature review has shown that PFPS development is probably multifactorial with various functional disorders of the lower extremity. Biomechanical studies described patellar maltracking and dynamic valgus in PFPS patients (functional malalignment). Causes for the dynamic valgus may be decreased strength of the hip abductors or abnormal rear-foot eversion with pes pronatus valgus. PFPS is further associated with vastus medialis/vastus lateralis dysbalance, hamstring tightness or iliotibial tract tightness. The literature provides evidence for a multimodal non-operative therapy concept with short-term use of NSAIDs, short-term use of a medially directed tape and exercise programmes with the inclusion of the lower extremity, and hip and trunk muscles. There is also evidence for the use of patellar braces and foot orthosis. A randomized controlled trial has shown that arthroscopy is not the treatment of choice for treatment of PFPS without any structural changes. Patients with anterior knee pain have to be examined carefully with regard to functional causes for a PFPS. The treatment of PFPS patients is non-operative and should address the functional causes.
Level of evidence V.
doi:10.1007/s00167-013-2759-6
PMCID: PMC4169618  PMID: 24221245
Functional malalignment; Dynamic valgus; Hip strength; Rear-foot eversion; Single-leg squat; Hip strength
20.  Increased cartilage volume after injection of hyaluronic acid in osteoarthritis knee patients who underwent high tibial osteotomy 
Purpose
High tibial osteotomy (HTO) is a surgical procedure used to correct abnormal mechanical loading of the knee joint; additionally, intra-articular hyaluronic acid injections have been shown to restore the viscoelastic properties of synovial fluid and balance abnormal biochemical processes. It was hypothesized that combining HTO with intra-articular hyaluronic acid injections would have benefit to improve the cartilage volume of knee joints.
Methods
Forty patients with medial compartment knee osteoarthritis (OA) were randomly placed into 1 of 2 groups. The study group (n = 20) received 2 cycles (at 6-month intervals) of 5 weekly intra-articular hyaluronic acid injections after HTO operation. The control group (n = 20) did not receive any intra-articular injections after HTO surgery. Cartilage volume (primary outcome) was assessed by magnetic resonance imaging (MRI) pre-operatively and 1 year post-operatively. Treatment efficacy (secondary outcomes) was evaluated with the Western Ontario and McMaster Universities OA Index (WOMAC) and by the comparison of the total rescue medication (paracetamol/diclofenac) used (weeks 6, 12, 24, 48).
Results
MRI studies showed a significant increase in total cartilage volume (p = 0.033), lateral femoral cartilage volume (p = 0.044) and lateral tibial cartilage volume (p = 0.027) in the study group. Cartilage volume loss was detected at the lateral tibial plateau in the control group. There were significant improvements after surgery in both groups for all subscales of WOMAC scores (p < 0.001) compared to the baseline. However, no difference was found between the two groups. The study group had significantly lower amounts of diclofenac consumption (p = 0.017).
Conclusion
Based on the findings of the present study, intra-articular hyaluronic acid injections may be beneficial for increasing total cartilage volume and preventing the loss of lateral tibiofemoral joint cartilage after HTO.
Level of evidence
Therapeutic study, Level I.
doi:10.1007/s00167-013-2735-1
PMCID: PMC4028547  PMID: 24162762
Viscosupplementation; Osteoarthritis knee; High tibial osteotomy; Cartilage volume; MRI
21.  The Effect of Tibial Tuberosity Realignment Procedures on the Patellofemoral Pressure Distribution 
Purpose
The study was performed to characterize the influence of tibial tuberosity realignment on the pressure applied to cartilage on the patella in the intact condition and with lesions on the lateral and medial facets.
Methods
Ten knees were loaded in vitro through the quadriceps (586 N) and hamstrings (200 N) at 40°, 60° and 80° of flexion while measuring patellofemoral contact pressures with a pressure sensor. The tibial tuberosity was positioned 5 mm lateral of the normal position to represent lateral malalignment, 5 mm medial of the normal position to represent tuberosity medialization, and 10 mm anterior of the medial position to represent tuberosity anteromedialization. The knees were tested with intact cartilage, with a 12 mm diameter lesion created within the lateral patellar cartilage, and with the lateral lesion repaired with silicone combined with a medial lesion. A repeated measures ANOVA and post-hoc tests were used to identify significant (p < 0.05) differences in the maximum lateral and medial pressure between the tuberosity positions.
Results
Tuberosity medialization and anteromedialization significantly decreased the maximum lateral pressure by approximately 15% at 60° and 80° for intact cartilage and cartilage with a lateral lesion. Tuberosity medialization significantly increased the maximum medial pressure for intact cartilage at 80°, but the maximum medial pressure did not exceed the maximum lateral pressure for any testing condition.
Conclusions
The results indicate that medializing the tibial tuberosity by 10 mm reduces the pressure applied to lateral patellar cartilage for intact cartilage and cartilage with lateral lesions, but does not overload medial cartilage.
doi:10.1007/s00167-011-1802-8
PMCID: PMC3312931  PMID: 22134408
malalignment; patellofemoral; tuberosity realignment; lesions; pressure; kinematics
22.  Intra-articular remodelling of hamstring tendon grafts after anterior cruciate ligament reconstruction 
Purpose
A summary is provided on the existing knowledge about the specific healing phases of the intra-articular hamstring tendon graft used for ACL reconstruction. Differences between human and animal in vivo studies are explained, and implications for the postoperative time period are laid out.
Methods
A systematic review of the existing literature was performed on the topic of tendon remodelling of hamstring grafts in ACL reconstruction using Medline database. Publications between 1982 and 2012 were included. Special focus was directed on in vivo human and animal studies analysing intra-articular free tendon graft remodelling.
Results
Animal and human in vitro and vivo researches have demonstrated three characteristic stages of graft healing after ACL reconstruction: an early graft healing phase with central graft necrosis and hypocellularity and no detectable revascularization of the graft tissue, followed by a phase of proliferation, the time of most intensive remodelling and revascularization and finally, a ligamentization phase with characteristic restructuring of the graft towards the properties of the intact ACL. However, a full restoration of either the biological or biomechanical properties of the intact ACL is not achieved.
Conclusion
Significant knowledge on human cruciate ligament remodelling has been added in the understanding of the processes during the course of graft healing. Most importantly, the remodelling process in humans is prolonged compared to animal studies. While today´s rehabilitation protocols are often extrapolated from findings of animal in vivo healing studies, current findings of human in vivo healing studies might require new post-operative regimens following hamstring ACL reconstruction.
doi:10.1007/s00167-013-2634-5
PMCID: PMC4142140  PMID: 23982759
Graft remodelling; ACL; Hamstring tendon; Accelerated rehabilitation; Ligamentization
23.  Does autograft choice determine intermediate term outcome of ACL reconstruction? 
Purpose
Many clinical studies and systematic reviews have compared the short-term (2 year) outcomes of ACL reconstruction with hamstring and patellar tendon autograft. Few differences have been observed, with the exception of increased kneeling pain with patellar tendon grafts. The goal of this systematic review is to determine where there are differences in clinical, patient reported, or radiographic outcomes based on graft choice at a minimum of 5 years after ACL reconstruction.
Methods
A systematic review was performed to identify all prospective outcome studies comparing patellar tendon and hamstring autograft ACL reconstruction with minimum follow-up of at least five years. Seven studies were identified and meta-analysis of select data determined to be sufficiently homogenous was performed (failure and laxity).
Results
Five randomized controlled trials and two prospective cohorts comparing hamstring and patellar tendon autografts were identified. Clinical assessment [failure rate, International Knee Documentation Committee (IKDC) class, Lachman, pivot shift, and KT 1000 testing] showed no difference between grafts. Patient-reported outcomes (Lysholm, Cincinnati, and IKDC) showed no difference. Both anterior knee pain (3/3 studies) and kneeling pain (4/4 studies) were more frequent in the patellar tendon group. However, the patient-reported outcomes in these studies were not different. Radiographic evidence of osteoarthritis was inconsistent between autograft choices.
Conclusion
This Level II systematic review demonstrates no difference in major clinical results between graft types with the exception of increased anterior knee and kneeling pain. There exists a potential for increased incidence of osteoarthritis in the patellar tendon group but increased sample size is required. These longer-term outcomes are similar to results of prior systematic reviews with two-year follow-up.
doi:10.1007/s00167-010-1277-z
PMCID: PMC3745218  PMID: 20953764
24.  Quantitative magnetic resonance imaging (MRI) morphological analysis of knee cartilage in healthy and anterior cruciate ligament-injured knees 
Purpose
To analyze the morphological change in the cartilage of the knee after anterior cruciate ligament (ACL) injury by comparing with that of the intact contralateral knee.
Methods
A total of 22 participants (12 male and 10 female patients) who had unilateral ACL injury underwent MRI scan of both the injured and intact contralateral knees. Sagittal plane images were segmented using a modeling software to determine cartilage volume and cartilage thickness in each part of the knee cartilage that were compared between the ACL-injured and the intact contra-lateral knees. Furthermore, the male and female patients’ data were analyzed in subgroups.
Results
The ACL-injured knees had statistically significant lower total knee cartilage volume than the intact contralateral knees (P = 0.0020), but had similar mean thickness of total knee cartilage (not significant: n.s.). In the male subgroup, there was no significant difference in cartilage volume and thickness between normal and ACL-injured knees. In the female subgroup, the ACL-injured knees demonstrated statistically significant difference in total knee cartilage volume (P = 0.0004) and thickness (P = 0.0024) compared with the normal knees. The percentage change in the cartilage thickness in women was significantly greater than that in men.
Conclusion
Cartilage volume was significantly smaller in the ACL-injured knees than in the contralateral intact knees in this cohort. Women tended to display greater cartilage volume and thickness change after ACL injury than men. These findings indicated that women might be more susceptible to cartilage alteration after ACL injuries.
Level of evidence
III.
doi:10.1007/s00167-011-1723-6
PMCID: PMC3740362  PMID: 22037812
MRI; Cartilage; Knee; Anterior cruciate ligament
25.  The effect of distal femur bony morphology on in vivo knee translational and rotational kinematics 
Purpose
Tibio-femoral kinematics are clearly influenced by the bony morphology of the femur. Previous morphological studies have not directly evaluated relationships between morphology and knee kinematics. Therefore, the purpose of this study was to examine the relationship between distal femur bony morphology and in vivo knee kinematics during running. It was hypothesized that the posterior offset of the transcondylar axis would be related to the magnitude of anterior/posterior tibio-femoral translation and that the rotational angle of the transcondylar axis would be related to the magnitude of internal/external knee rotation.
Methods
Seventeen contralateral (uninjured) knees of ACL-reconstructed patients were used. Distal femoral geometry was analyzed from 3D-CT data by determining the anteroposterior location (condyle offset ratio—COR) and rotational angle (condylar twist angle—CTA) of the femoral transcondylar axis. Six degree-of-freedom knee kinematics were obtained during running using a dynamic stereo radiograph system. Knee kinematics were correlated with the femoral morphologic measures (COR and CTA) to investigate the influence of femoral geometry on dynamic knee function.
Results
Significant correlations were identified between distal femur morphology and knee kinematics. Anterior tibial translation was positively correlated with the condyle offset ratio (R2 = 0.41, P < 0.01). Internal tibial rotation was positively correlated with the condylar twist angle (R2 = 0.48, P < 0.01).
Conclusions
Correlations between knee kinematics and morphologic measures describing the position and orientation of the femoral transcondylar axis suggest that these specific measures are valuable for characterizing the influence of femur shape on dynamic knee function.
Level of evidence
III.
doi:10.1007/s00167-011-1661-3
PMCID: PMC3269529  PMID: 21909723
Bony morphology; In vivo knee kinematics; Dynamic stereo radiograph (DSX) system; Transcondylar axis

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