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1.  Results of the cementless Plasmacup in revision total hip arthroplasty: a retrospective study of 72 cases with an average follow-up of eight years 
Background
There are multiple revision implant systems currently available for socket revision in revision total hip arthroplasty. Up until now, not all of these systems have been followed up with regards to their long-term use as a revision implantation.
For the first time, this study presents the hemispherical porous-coated socket Plasmacup SC, produced by Aesculap, Tuttlingen, Germany, and the clinical and radiological mid-term results of this revision cup implant.
Methods
Over a period of ten years the Plasmacup SC press-fit-cup was used as a revision implant in 72 consecutive aseptic cases which were included in this retrospective study. The mean follow-up period was 8 years. Bone graft transplantation was performed in 32% of all cases. In 90%, the cup was fixed with additional screws. The follow-up radiographs were analysed with regards to cup migration, osteointegration and osteolysis in the DeLee zones using a computer aided program taking the teardrop figure as a main point of reference. For clinical evaluation the Harris-Hip-Score and the WOMAC-Score were utilized.
Results
At the follow up examination, the mean Harris-Hip-Score was 83.5 points and the mean WOMAC-Score 34.7 points. 93% of all patients were satisfied with the result of the operation. No aseptic cup loosening could be observed and only one cup had to be removed due to infection. No significant longitudinal or transversal cup migration could be observed.
Conclusion
Aesculap's Plasmacup SC is suitable as a cementless cup revision implant. There is stable cup osteointegration, post press-fit implantation, even in the case of major acetabular bone defects.
doi:10.1186/1471-2474-11-101
PMCID: PMC2887774  PMID: 20507578
2.  Cup Press Fit in Uncemented THA Depends on Sex, Acetabular Shape, and Surgical Technique 
Background
Uncemented press-fit cups provide bone fixation in primary THA, but the use of screws is sometimes necessary to achieve primary stability of the socket. However, it is unclear whether and when screws should be used.
Question/Purposes
We analyzed the factors related to screw use with a press-fit uncemented cup and assessed whether screw use is associated with the same rates of loosening and revision as a press-fit technique.
Methods
We retrospectively reviewed 248 patients who underwent THA using the same prosthetic design. Eighty-eight hips had screws to achieve primary cup fixation (Group 1), and 189 did not (Group 2). Mean age was 50 years (range, 14–73 years). We analyzed factors related to the patient, acetabular type, and reconstruction of the rotation center of the hip. Minimum followup was 5 years (mean, 8.9 years; range, 5–12 years).
Results
We found higher screw use in women, patients with less physical activity, Acetabular Types A or C, and a distance from the center of the prosthetic femoral head to the normal center of rotation of more than 3 mm. There were four revisions in Group 1 and five in Group 2. Eight hips had radiographic loosening in Group 1 and nine in Group 2. Cups with a postoperative abduction angle of more than 50° had a higher risk for loosening.
Conclusions
Press fit was achieved less frequently in women and patients with Acetabular Types A or C and less physical activity; a closer distance to the normal center of rotation decreased screw use. Screw use to augment fixation achieved survival similar to that of a press-fit cup.
Level of Evidence
Level II, prognostic study. See Instructions for Authors for a complete description of levels of evidence
doi:10.1007/s11999-012-2381-9
PMCID: PMC3462870  PMID: 22576930
3.  Superior fixation of pegged trabecular metal over screw-fixed pegged porous titanium fiber mesh 
Acta Orthopaedica  2011;82(2):177-186.
Background and purpose
Lasting stability of cementless implants depends on osseointegration into the implant surface, and long-term implant fixation can be predicted using radiostereometric analysis (RSA) with short-term follow-up. We hypothesized that there would be improved fixation of high-porosity trabecular metal (TM) tibial components compared to low-porosity titanium pegged porous fiber-metal (Ti) polyethylene metal backings.
Methods
In a prospective, parallel-group, randomized unblinded clinical trial, we compared cementless tibial components in patients aged 70 years and younger with osteoarthritis. The pre-study sample size calculation was 22 patients per group. 25 TM tibial components were fixed press-fit by 2 hexagonal pegs (TM group) and 25 Ti tibial components were fixed press-fit and by 4 supplemental screws (Ti group). Stereo radiographs for evaluation of absolute component migration (primary effect size) and single-direction absolute component migration (secondary effect size) were obtained within the first postoperative week and at 6 weeks, 6 months, 1 year, and 2 years. American Knee Society score was used for clinical assessment preoperatively, and at 1 and 2 years.
Results
There were no intraoperative complications, and no postoperative infections or revisions. All patients had improved function and regained full extension. All tibial components migrated initially. Most migration of the TM components (n = 24) occurred within the first 3 months after surgery whereas migration of the Ti components (n = 22) appeared to stabilize first after 1 year. The TM components migrated less than the Ti components at 1 year (p = 0.01) and 2 years (p = 0.004).
Interpretation
We conclude that the mechanical fixation of TM tibial components is superior to that of screw-fixed Ti tibial components. We expect long-term implant survival to be better with the TM tibial component.
doi:10.3109/17453674.2011.566139
PMCID: PMC3235288  PMID: 21434781
4.  A cementless elastic monoblock socket in young patients: a ten to 18-year clinical and radiological follow-up 
International Orthopaedics  2010;35(10):1445-1451.
The survival of acetabular components depends on several factors: wear, osteolysis and septic or aseptic loosening. Osteolysis seems to be the main cause for concern in cementless arthroplasties. Acetabular osteolysis results from particle debris and segmental unloading of acetabular bone by rigid sockets. We investigated a cementless elastic monoblock socket with regard to acetabular osteolysis and aseptic loosening in a cohort of young patients. We evaluated 158 hip arthroplasties with a minimum follow-up of ten years (ten to 18) and a mean age of 42 years (18–50). The overall revision rate at 14 years was 80% with a 98% survival rate for aseptic loosening. The mean polyethylene wear rate was 0.11 mm/year. Progressive acetabular osteolysis was seen in 3% of patients evaluated. In conclusion, we found low pelvic osteolysis rates, acceptable overall wear rates, satisfactory overall survival and excellent survival rates for aseptic loosening of a cementless elastic monoblock socket in patients younger than 50 years. Ongoing tribology developments and knowledge about acetabular bone adaptations behind acetabular implants will further lower wear and osteolysis rates and optimise survival rates of cementless sockets.
doi:10.1007/s00264-010-1120-7
PMCID: PMC3174288  PMID: 20820777
5.  High Survivorship of Cemented Sockets with Roof Graft for Severe Acetabular Dysplasia 
Background
Socket fixation in patients with acetabular dysplasia can be technically demanding but the use of structural grafts can help to reconstruct the original center of hip rotation. Because reported survival rates differ, construct survival seems to depend on the technique of graft preparation and fixation.
Questions/purposes
What is the survivorship of cemented sockets with acetabular roof graft in patients with severe acetabular dysplasia? Do clinical scores equal those of patients without acetabular grafting?
Methods
We retrospectively reviewed 62 patients (74 hips) who had undergone cemented THA with acetabular roof graft. Mean age at surgery was 45 years (range, 19–71 years). Revisions and radiographic failures were determined and clinical scores (Oxford, SF-12) were obtained and matched to a control group. Kaplan-Meier analysis was used to determine survivorship at a minimum followup of 5 years (mean, 10.4 years; range, 5–16 years).
Results
Survivorship for all-cause revision was 98% (95% CI, 92.5%–100.0%) at 10 years followup. Two hips were revised for aseptic acetabular loosening and one hip for polyethylene wear. All grafts incorporated and no additional radiographic loosenings were seen. Patients with grafting had higher Oxford scores compared with the control group but other scores were equal.
Conclusions
In contrast to reported series and the common use of cementless cups in patients with developmental dysplasia of the hip, we found high survivorship of cemented sockets with roof graft in severe acetabular dysplasia at a mean followup of more than 10 years. These patients showed higher Oxford scores than patients in a control group. This technique that restores bone stock is a reasonable solution for often young patients with dysplasia.
Level of Evidence
Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2346-z
PMCID: PMC3462842  PMID: 22492173
6.  Extensively coated revision stems in proximally deficient femur: Early results in 15 patients 
Indian Journal of Orthopaedics  2008;42(3):287-293.
Background:
Hip replacement following failed internal fixation (dynamic hip screw for intertrochanteric fractures) or previous hip arthroplasty presents a major surgical challenge. Proximal fitting revision stems do not achieve adequate fixation. Distal fixation with long-stemmed extensively coated cementless implants (like the Solution™ system) affords a suitable solution. We present our early results of 15 patients treated with extensively coated cementless revision stems.
Materials and Methods:
Fifteen patients with severely compromised proximal femora following either failed hip arthroplasty or failed internal fixation (dynamic hip screw fixation for intertrochanteric fractures) were operated by the senior author over a two-year period. Eight patients had aseptic loosening of their femoral stems following cemented hip replacements, with severe thinning of their proximal cortices and impending stress fractures. Seven had secondary hip arthritis following failure of long implants for comminuted intertrochanteric or subtrochanteric femoral fractures. All patients were treated by removal of implant (cemented stems/DHS implants) and insertion of long-stemmed extensively coated cementless revision (‘Solution™ DePuy, Warsaw (IN), US’) stems along with press-fit acetabular component (Duraloc Cup, DePuy, Warsaw (IN), US). All eight hip revisions needed extended trochanteric osteotomies.
Results:
All patients were primarily kept in bed on physiotherapy for six weeks and then gradually progressed to weight-bearing walking over the next six to eight weeks. The Harris Hip Scores and patient satisfaction were used for final evaluation. We achieved good results in the short term studied. In our first three patients (all following failed cemented total hip replacements), we resorted to cerclage wiring to hold osteotomised segments (done to facilitate stem removal). The subsequent 12 proceeded without the need for cerclage wiring. One patient had a intraoperative severe comminuted fracture extending into the supracondylar region while hammering in the stem. Post cerclage wiring, she was put on a long knee brace and her mobilization was delayed to 12 weeks.
Conclusions:
The extensively coated cementless (‘Solution™’) femoral stem provides a reasonable ‘solution’ to the deficient femur in hip revision. The proximal femoral deficiences can be relatively easily bypassed and distal fixation can be achieved with this stem. Extreme care needs to be taken to avoid fractures and penetration of the femoral shaft, which can, however, be managed by cerclage wiring. Principles of a successful outcome include preservation of the functional continuity of the abduction apparatus, care to recognize and prevent distal extension of fracture while inserting the stem (preemptive cerclage wiring) and supervised rehabilitation.
doi:10.4103/0019-5413.39554
PMCID: PMC2739478  PMID: 19753154
Cementless fixation; extensively coated; proximally deficient femur
7.  Is a Cementless Dual Mobility Socket in Primary THA a Reasonable Option? 
Background
Dislocation after THA continues to be relatively common. Dual mobility sockets have been associated with low dislocation rates, but it remains unclear whether their use in primary THA would not introduce additional complications.
Questions/Purposes
We therefore asked whether a current cementless dual mobility socket (1) reduced the dislocation rate after primary THA, (2) provided a pain-free and mobile hip, and (3) provided durable radiographic fixation of the acetabular component without any unique modes of failure.
Methods
We retrospectively reviewed 168 patients who underwent primary THA using a dual mobility socket between January 2000 and June 2002. The average age at surgery was 67 years. We assessed the rate of dislocation, hip function, and acetabular fixation on serial radiographs. Of the 168 patients, 119 (71%) had clinical and radiographic evaluation at a minimum of 5 years (mean, 6 years; range, 5–8 years).
Results
A long-neck option left the base of the Morse taper uncovered in 53 hips. Four patients underwent revision for dislocation between the femoral head and the mobile insert (intraprosthetic dislocation) at a mean 6 years; all four revisions occurred among the 53 hips with an incompletely covered Morse taper.
Conclusions
A current cementless dual mobility socket was associated with a pain-free and mobile hip and durable acetabular fixation without dislocations if the long-neck option was not used. However, intraprosthetic dislocation related to contact at the femoral neck to mobile insert articulation required revision in four hips. Surgeons should be aware of this specific complication.
Level of Evidence
Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-012-2395-3
PMCID: PMC3462877  PMID: 22639330
8.  Function and Fixation of Total Hip Arthroplasty in Patients 25 Years of Age or Younger 
Background
The treatment of end-stage hip disease in very young patients is controversial, with advocates for nonoperative treatment, hip arthrodesis and replacement procedures. The functional improvements in this group of patients are not well documented and whether the condition for which the surgery is performed influences function.
Questions/purposes
We determined whether (1) modern THA provides major functional improvements; (2) disease-specific factors impact the magnitude of improvement; (3) these procedures are associated with early failures and complications; and (4) radiographically secure implant fixation is achieved with contemporary implants.
Methods
We retrospectively reviewed 88 patients (102 hips) who had THA and were 25 years or younger at surgery. The most common diagnoses were osteonecrosis (44%) and secondary osteoarthritis (41%). All patients received a cementless socket of varying designs and all except five a cementless stem. Demographic data, Harris hip score, and Charnley classification were recorded. Radiographic evaluation was used to determine implant fixation. We identified complications and failure mechanisms. The minimum followup was 2 years (median, 4.2 years; range, 2–16 years).
Results
The 95 nonrevised hips were followed clinically an average of 61 months. The mean Harris hip scores improved from 42 preoperatively to 83 postoperatively. Lower Harris hip scores were associated with systemic disease (Charnley Class C). Seven hips (7%) underwent revision. There were nine (9%) major complications. One hundred percent of femoral stems and 98% of acetabular components were well-fixed at last followup.
Conclusion
Contemporary total hip arthroplasty in patients 25 years of age and younger is associated with improved hip function, and secure fixation of cementless implants at early followup.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1468-4
PMCID: PMC2974894  PMID: 20668972
9.  Is there evidence for a superior method of socket fixation in hip arthroplasty? A systematic review 
International Orthopaedics  2011;35(8):1109-1118.
Purpose
Total hip arthroplasty has been a very succesful orthopaedic procedure. The optimal fixation method of the acetabular component however, has not yet been defined.
Methods
We performed a systematic review using the Medline and Embase databases to find evidence for the superiority of cemented or cementless acetabular components on short- and long-term clinical and radiological parameters. Methodological quality for randomised trials was assessed using the van Tulder checklist, and for the non randomised studies we used the Newcastle-Ottawa quality assessment scale.
Results
Our search strategy revealed 16 randomised controlled trials (RCT) and 19 non RCT studies in which cemented and cementless acetabular components are compared. A best evidence analysis for complications, wear, osteolysis, migration and clinical scores showed no superiority for either cemented or cementless socket in the RCTs. A best evidence analysis for non RCT studies revealed better osteolysis, migration properties and aseptic loosening survival for cementless sockets; however, wear and overall survival favoured the cemented sockets.
Conclusions
We recommend that an orthopaedic surgeon should choose an established cemented or cementless socket for hip replacement based on patient characteristics, knowledge, experience and preference.
doi:10.1007/s00264-011-1234-6
PMCID: PMC3167434  PMID: 21404024
10.  Total hip replacement in developmental dysplasia using an oval-shaped cementless press-fit cup 
International Orthopaedics  2012;36(7):1355-1361.
Purpose
Acetabular roof deficiency due to subluxation of the femoral head (Hartofilakidis type II) increases the complexity of total hip arthroplasty. In these cases some form of support is usually required, to reach stable fixation of the acetabular component. Pursuing this aim, the oval-shaped cementless cranial socket could be an alternative to conventional treatment options.
Methods
Between 1998 and 2008, 37 patients (40 hips) underwent primary total hip arthroplasty using the cranial socket (mean follow-up 5.6 years, range 26 to 133 months). In a retrospective study we compared these clinical and radiological results with the results of a matched control group consisting of 35 patients (40 hips) treated with a standard cementless hemispherical cup in combination with bulk femoral autografting (mean follow-up 6.9 years, range 30 to 151 months).
Results
There were no statistically significant differences in the HHS (p = 0.205) or the SF-36 (p = 0.26) between both groups. There was no prosthesis failure due to septic or aseptic loosening. Time of surgery was significantly shorter in the cranial socket group (p < 0.001). The acetabular component could be placed in the ideal rotational hip centre in 24 (60%) hips in the cranial socket group and 32 (80%) hips in the control group, respectively.
Conclusions
Our study indicates, that the cranial socket can be an alternative treatment option for the reconstruction of acetabular deficiency in osteoarthritis secondary to developmental dysplasia.
doi:10.1007/s00264-012-1510-0
PMCID: PMC3385904  PMID: 22382394
11.  Is wear debris responsible for failure in alumina-on-alumina implants? 
Acta Orthopaedica  2009;80(2):162-167.
Background and purpose Ceramic-on-ceramic articulation is an attractive alternative to metal-on-polyethylene (PE) bearings, but little is known about the in vivo effects induced by dissemination of alumina wear debris in the periprosthetic tissues. We hypothesized that wear debris is not the main factor responsible for loosening and failure of the implant but that mechanical problems caused by incorrect surgical technique, prosthetic design, or trauma, may cause instability of the implants and result in production of wear debris.
Patients and methods Clinical, radiographic, laboratory, and microbiological data from 30 consecutive patients with failed alumina-on-alumina arthroplasties, 19 with screwed socket and 11 with press-fit socket, were systematically collected and evaluated. Retrieved peri-implant tissues and prosthesis wear were also analyzed.
Results and Interpretation Loosening was due to malpositioning, primary mechanical instability, trauma, or infection. Bone stock was generally preserved, even if screwed implants showed higher levels of osteolysis. Variable implant wear and tissue macrophage reaction were present but activation of giant cells/osteoclasts was not induced, and no correlation between histocytic reaction and the level of osteolysis was found. These findings indicate that, in contrast to the situation with metal-on-PE bearings, wear debris and occasional osteolysis were the effect rather than the cause of failure of ceramic-on-ceramic implants, and that press-fit socket fixation was the socket fixation design of preference.
doi:10.3109/17453670902876730
PMCID: PMC2823169  PMID: 19404796
12.  Migration pattern of cementless press fit cups in the presence of stabilizing screws in total hip arthroplasty 
The aim of this study was to evaluate the initial acetabular implant stability and late acetabular implant migration in press fit cups combined with screw fixation of the acetabular component in order to answer the question whether screws are necessary for the fixation of the acetabular component in cementless primary total hip arthroplasty. One hundred and seven hips were available for follow-up after primary THA using a cementless, porous-coated acetabular component. A total of 631 standardized radiographs were analyzed digitally by the "single-film-x-ray-analysis" method (EBRA). One hundred 'and one (94.4%) acetabular components did not show significant migration of more than 1 mm. Six (5.6%) implants showed migration of more than 1 mm. Statistical analysis did not reveal preoperative patterns that would identify predictors for future migration. Our findings suggest that the use of screw fixation for cementless porous- coated acetabular components for primary THA does not prevent cup migration.
doi:10.1186/2047-783X-16-3-127
PMCID: PMC3352209  PMID: 21486725
cementless; acetabular; fixation; with screws; without screws; EBRA; Total Hip Arthroplasty
13.  10-year results of the uncemented Allofit press-fit cup in young patients 
Acta Orthopaedica  2014;85(4):368-374.
Background and purpose
Uncemented acetabular components in primary total hip arthroplasty (THA) are commonly used today, but few studies have evaluated their survival into the second decade in young and active patients. We report on a minimum 10-year follow-up of an uncemented press-fit acetabular component that is still in clinical use.
Methods
We examined the clinical and radiographic results of our first 121 consecutive cementless THAs using a cementless, grit-blasted, non-porous, titanium alloy press-fit cup (Allofit; Zimmer Inc., Warsaw, IN) without additional screw fixation in 116 patients. Mean age at surgery was 51 (21–60) years. Mean time of follow-up evaluation was 11 (10–12) years.
Results
At final follow-up, 8 patients had died (8 hips), and 1 patient (1 hip) was lost to follow-up. 3 hips in 3 patients had undergone acetabular revision, 2 for deep infection and 1 for aseptic acetabular loosening. There were no impending revisions at the most recent follow-up. We did not detect periacetabular osteolysis or loosening on plain radiographs in those hips that were evaluated radiographically (n = 90; 83% of the hips available at a minimum of 10 years). Kaplan-Meier survival analysis using revision of the acetabular component for any reason (including isolated inlay revisions) as endpoint estimated the 11-year survival rate at 98% (95% CI: 92–99).
Interpretation
Uncemented acetabular fixation using the Allofit press-fit cup without additional screws was excellent into early in the second decade in this young and active patient cohort. The rate of complications related to the liner and to osteolysis was low.
doi:10.3109/17453674.2014.925351
PMCID: PMC4105767  PMID: 24875058
14.  Knee Arthroplasty With a Medially Conforming Ball-and-Socket Tibiofemoral Articulation Provides Better Function 
Background
A knee design with a ball-and-socket articulation of the medial compartment has a femoral rollback profile similar to the native knee. Compared to a conventional, posterior-stabilized knee design, it provides AP stability throughout the entire ROM. However, it is unclear whether this design difference translates to clinical and functional improvement.
Questions/purposes
We asked whether the medially conforming ball-and-socket design differences would be associated with (1) improved ROM; and (2) improved American Knee Society, WOMAC, Oxford Knee, SF-36, and Total Knee Function Questionnaire scores compared to a conventional, fixed-bearing posterior-stabilized TKA.
Patients and Methods
We enrolled 82 patients in a single-center, single-blinded, randomized, controlled trial comparing the medially conforming ball-and-socket design knee prosthesis to a posterior-stabilized total knee prosthesis. Our primary end point was ROM. Our secondary end points were American Knee Society, WOMAC, Oxford Knee, SF-36, and Total Knee Function Questionnaire scores. All patients were followed at 1 and 2 years.
Results
The mean ROM was 100.1° and 114.9° in the posterior-stabilized and medially conforming ball-and-socket groups, respectively. The physical component scores of SF-36 and Total Knee Function Questionnaire were better in the medially conforming ball-and-socket group. We found no difference in American Knee Society, WOMAC, and Oxford Knee scores.
Conclusions
Both implant designs similarly relieved pain and improved function. The medially conforming ball-and-socket articulation provided better high-end function as reflected by the Total Knee Function Questionnaire.
Level of Evidence
Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1493-3
PMCID: PMC3008885  PMID: 20700674
15.  A new technique in double-bundle anterior cruciate ligament reconstruction using implant-free femoral fixation 
International Orthopaedics  2012;36(7):1479-1485.
Purpose
The study is a prospective case-series analysis to demonstrate a new double bundle technique for anterior cruciate ligament (ACL) reconstruction with the use of hamstring tendons through a single tibial tunnel, a double femoral socket with implant-free femoral fixation and interference screw for tibial fixation.
Materials and methods
Twenty-one patients were treated with the same technique. Hamstring tendons were not removed from the tibial side, and using a single tibial and a double femoral tunnel of 8 and 6 mm, respectively, anatomic ACL reconstruction was performed. Graft passage was performed from the tibial side to the posterolateral femoral tunnel and was looped back to the anteromedial femoral tunnel to be fixed on the tibial tunnel with an interference screw and additional extracortical fixation. Follow-up of the study group was performed for a two-year period, documenting standard clinical and radiographic parameters.
Results
Post-operative follow-up (mean 24 months) revealed radiological widening of tibial tunnel (mean 133.6%) in all patients and minor femoral tunnels widening (119.4% and 117.5%). Clinical evaluation showed no signs of instability, and knee evaluation using the IKDC score was performed.
Conclusion
The manuscript describes a novel technique in ACL reconstruction, and reports the radiographic results of tunnel widening and clinical scores. Implant-free femoral fixation led to minor tunnel widening similar to previously published data. Further studies need to be performed to compare the long-term results with different published techniques of cost-effective implant-free ACL reconstruction.
doi:10.1007/s00264-012-1488-7
PMCID: PMC3385895  PMID: 22323087
16.  Fixation Failures of Dual Mobility Cups: A Mid-term Study of 2601 Hip Replacements 
Background
The use of dual-mobility cups has increased because of a low rate of dislocations combined with a 96% 15-year survival rate. However, late cup migrations have been attributed to their fixation (tripod - exact fit with two pegs and one extraacetabular screw) and the absence of porous coating. In a second-generation device, the designs were modified to achieve press-fit fixation and a layer of titanium beads was sintered on stainless steel cups.
Questions/purposes
We therefore (1) determined the midterm survival of press-fit, grit-blasted, second-generation cups with or without additional screws, compared with original tripod and (2) compared survival of grit-blasted dual-mobility cups with bimetallic porous-coated cups.
Methods
From a multiinstitutional trial, we reviewed 2408 patients with osteoarthritis implanted with 2601 prostheses of seven designs of a second-generation dual-mobility cup. The criteria for failure were migration, widening radiolucencies in any zone of the interface, or revision for cup loosening. The minimum followup was 5 years (mean, 7.7 years; range, 5–11 years).
Results
The 8-year survival rate of press-fit, grit-blasted cups was lower than that for press-fit, grit-blasted cups fixed with screws (91% versus 100%) and for tripod fixation (98%). The 8-year survival rate of press-fit, grit-blasted cups was less than that for press-fit, porous-coated cups made of the same alloy (91% versus 95%).
Conclusions
The data suggested primary fixation of grit-blasted dual-mobility cups should be secured with screws. Porous coating sintered on the convex side improved midterm survivorship. No deleterious effect of metallosis resulted from sintered titanium beads on stainless steel. Long-term followup is required to confirm these findings.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-011-2213-3
PMCID: PMC3369083  PMID: 22161085
17.  High Long-term Survival of Bulk Femoral Head Autograft for Acetabular Reconstruction in Cementless THA for Developmental Hip Dysplasia 
Background
Deficient acetabula associated with acetabular dysplasia cause difficulty achieving adequate coverage of the acetabular component during THA. Autografting with the removed femoral head has been used for several decades to achieve better coverage, but the long-term benefits of this technique remain controversial, with some series reporting high rates of graft resorption and collapse.
Questions/purposes
We evaluated the fate of bulk femoral head autograft for acetabular reconstruction in cementless THA for developmental hip dysplasia.
Patients and Methods
We retrospectively reviewed 70 patients (83 hips) (68 women, two men) with a mean age of 57 years at index surgery. According to the classification of Crowe et al. for hip dysplasia, 10 hips were classified as Type I, 45 as Type II, 19 as Type III, and nine as Type IV. Minimum followup was 9 years (mean, 11 years; range, 9–14 years).
Results
We observed no collapsed grafts. In all patients we observed disappearance of the host-graft interface and appearance of radiodense bands in the grafts bridging host iliac bone and at the lateral edges of the acetabular sockets; remodeling with definite trabecular reorientation was seen in 90%. The 10-year survival rate without acetabular revision for any reason was 94%. The mean Merle d’Aubigné and Postel hip score improved from a mean of 9.1 preoperatively to 17.2 at last followup.
Conclusions
Cementless THA combined with autologous femoral bone graft in patients with developmental dysplasia resulted in a high rate of survival. Structural bone grafting achieved a stable construct until osseointegration occurred. We believe the radiodense bands represent a radiographic sign of successful completion of repair of the deficient acetabulum. Congruous and stable contact of the cancellous portion of the graft to the host bed by impaction and use of improved porous cementless sockets may be associated with successful socket survival.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1288-6
PMCID: PMC2865593  PMID: 20309659
18.  High Long-term Survival of Bulk Femoral Head Autograft for Acetabular Reconstruction in Cementless THA for Developmental Hip Dysplasia 
Background
Deficient acetabula associated with acetabular dysplasia cause difficulty achieving adequate coverage of the acetabular component during THA. Autografting with the removed femoral head has been used for several decades to achieve better coverage, but the long-term benefits of this technique remain controversial, with some series reporting high rates of graft resorption and collapse.
Questions/purposes
We evaluated the fate of bulk femoral head autograft for acetabular reconstruction in cementless THA for developmental hip dysplasia.
Patients and Methods
We retrospectively reviewed 70 patients (83 hips) (68 women, two men) with a mean age of 57 years at index surgery. According to the classification of Crowe et al. for hip dysplasia, 10 hips were classified as Type I, 45 as Type II, 19 as Type III, and nine as Type IV. Minimum followup was 9 years (mean, 11 years; range, 9–14 years).
Results
We observed no collapsed grafts. In all patients we observed disappearance of the host-graft interface and appearance of radiodense bands in the grafts bridging host iliac bone and at the lateral edges of the acetabular sockets; remodeling with definite trabecular reorientation was seen in 90%. The 10-year survival rate without acetabular revision for any reason was 94%. The mean Merle d’Aubigné and Postel hip score improved from a mean of 9.1 preoperatively to 17.2 at last followup.
Conclusions
Cementless THA combined with autologous femoral bone graft in patients with developmental dysplasia resulted in a high rate of survival. Structural bone grafting achieved a stable construct until osseointegration occurred. We believe the radiodense bands represent a radiographic sign of successful completion of repair of the deficient acetabulum. Congruous and stable contact of the cancellous portion of the graft to the host bed by impaction and use of improved porous cementless sockets may be associated with successful socket survival.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1288-6
PMCID: PMC2865593  PMID: 20309659
19.  Atlantoaxial fusion using anterior transarticular screw fixation of C1–C2: technical innovation and biomechanical study 
European Spine Journal  2005;14(5):512-518.
This study is an attempt to describe a new technique for anterior transarticular screw fixation of the atlantoaxial joints, and to compare the stability of this construct to posterior transarticular screw fixation with and without laminar cerclage wiring. Nine human cadaveric specimens were included in this study. The C1–C2 motion segment was instrumented using either anterior transarticular screws (group 1), posterior transarticular screws alone (group 2), or posterior screws with interlaminar cerclage wires (group 3). Using an unconstrained mechanical testing machine, the specimens were tested in rotation, lateral bending, and flexion-extension using nondestructive loads of ±2 N m. The specimens were also tested in translation using nondestructive loads of ±100 N. All values for the three groups with regards to anterior-posterior displacement, rotation, and lateral bending were similar as determined using a Kruskal–Wallis rank sum test with a significance level of p<0.05. The only significant difference was registered in flexion-extension where the cerclage wire added some strength to the construct. Anterior transarticular screw fixation of the atlantoaxial spine has several advantages over posterior fixation techniques, and is as stable as posterior transarticular fixation in all clinically significant planes of motion. The addition of posterior interlaminar cerclage wiring further improves resistance to flexion-extension forces. Anterior transarticular screw fixation of the atlantoaxial joint is a useful technique for achieving C1–C2 stabilization.
doi:10.1007/s00586-004-0823-0
PMCID: PMC3454666  PMID: 15668776
Atlas; Axis; Fracture; Spinal instability; Transarticular fixation
20.  Excellent results with cementless total hip arthroplasty and alumina-on-alumina pairing: minimum ten-year follow-up 
International Orthopaedics  2010;35(2):195-200.
Ceramic-on-ceramic coupling is thought to be a durable alternative to metal- or alumina-on-polyethylene pairing. No evidence exists suggesting superior clinical and radiological results for hydroxyapatite-coated stems versus uncoated stems. The aim of this study is to report the performance of an alumina-on-alumina bearing cementless total hip arthroplasty and to compare stems with a tapered design with and without hydroxyapatite coating. We prospectively analysed the results of cementless tapered femoral stems (40 hydroxyapatite-coated versus 22 uncoated stems), a metal-backed fibre mesh hydroxyapatite-coated socket and alumina-on-alumina pairing. Of 75 hips studied, 62 were available for follow-up (mean of 10.5 years after surgery). The average Harris hip score was 90. Only one hydroxyapatite-coated stem was revised for aseptic loosening. One instance of non-progressive osteolysis was detected around a screw of a cup. All other components showed radiographic signs of stable ingrowth. Hydroxyapatite coating of the stem had no significant impact on the clinical or radiological results. Total hip arthroplasty with the presented implant and pairing provides a durable standard for all patients requiring hip joint replacement against which all newer generations of cementless implants should be judged.
doi:10.1007/s00264-010-1150-1
PMCID: PMC3032123  PMID: 21079952
21.  Behaviour of the ultra-short anatomic cementless femoral stem in young and elderly patients 
International Orthopaedics  2013;37(12):2323-2330.
Purpose
The question arises as to whether it is possible to obtain rigid fixation of the ultra-short metaphyseal-fitting anatomic cementless stem without diaphyseal fixation in the elderly as well as younger patients. We investigated whether ultra-short, metaphyseal-fitting anatomic cementless femoral stem would provide similar functional improvements in the younger and elderly patients, radiographically secure implant fixation would be achieved in both groups, the bone content would be preserved in both groups, and complication rates would be similar in both groups.
Methods
A total of 100 patients (114 hips) in the younger patient group and 100 patients (112 hips) in the elderly patient group were included in the study. Their mean age was 43.9 ± 6.11 years (range, 31–65 years) in the younger patient group and 78.9 ± 12.1 years (range, 66–91 years) in the elderly patient group. The mean duration of follow-up was 7.5 years (range, six to nine years) in the younger patient group and 7.6 years (range, six to nine years) in the elderly patient group.
Results
The mean postoperative Harris hip scores (95 points versus 91 points), WOMAC scores (11 points versus 15 points), thigh pain (none in either group), UCLA activity scores (6.5 points versus 4.5 points), and radiographic results were not significantly different between the two groups. No hip in either group had an aseptic loosening. No hip in either group had clicking or squeaking sounds or ceramic fractures.
Conclusion
The cementless ultra-short, metaphyseal-fitting anatomic cementless femoral component provides stable fixation without any need of diaphyseal fixation in both younger and elderly patients. Despite the concern, the poor bone quality in elderly patients did not compromise the stability, and osseointegration of this ultra-short, anatomic cementless femoral stem was achieved in all elderly patients.
doi:10.1007/s00264-013-2044-9
PMCID: PMC3843203  PMID: 23925881
Ultra-short stem; Ultra-short stemmed hip replacement; Metaphyseal fitting anatomic cementless femoral component; Osteoarthritis; Osteonecrosis; Hip replacement
22.  The Use of a Cemented Dual Mobility Socket to Treat Recurrent Dislocation 
Background
The treatment of recurrent dislocation after total hip arthroplasty remains challenging. Dual mobility sockets have been associated with a low rate of dislocation but it is not known whether they are useful for treating recurrent dislocation.
Questions/purposes
We therefore asked whether a cemented dual mobility socket would (1) restore hip stability following recurrent dislocation; (2) provide a pain-free and mobile hip; and (3) show durable radiographic fixation.
Methods
We retrospectively reviewed 51 patients treated with a cemented dual mobility socket for recurrent dislocation after total hip arthroplasty between August 2002 and June 2005. The mean age at the time of the index procedure of was 71.3 years. Of the 51 patients, 47 have had complete clinical and radiographic evaluation data at a mean followup of 51.4 months (range, 25–76.3 months).
Results
The cemented dual mobility socket restored complete stability of the hip in 45 of the 47 patients (96%). The mean Merle d’Aubigné hip score was 16 ± 2 at the latest followup. Radiographic analysis revealed no or radiolucent lines less than 1 mm thick located in a single acetabular zone in 43 of 47 hips (91.5%). The cumulative survival rate of the acetabular component at 72 months using revision for dislocation and/or mechanical failure as the end point was 96% ± 4% (95% confidence interval, 90%–100%).
Conclusions
A cemented dual mobility socket was able to restore hip stability in 96% of recurrent dislocating hips. However, longer-term followup is needed to ensure that dislocation and loosening rates will not increase.
Level of Evidence
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
doi:10.1007/s11999-010-1404-7
PMCID: PMC2974879  PMID: 20532718
23.  The Influence of a Suction Device on Fixation of a Cemented Cup using RSA 
The quality of technique used at the time of socket cementation is crucial in ensuring a durable long-term result of the implant. We asked whether a new instrument, an aspirator retractor introduced into the wing of the ilium before socket preparation and cementation, would enhance cement fixation as defined by RSA and radiographic examination. We randomized 38 patients into two groups. The surgical technique was identical between the groups with the exception of the use of the aspirator retractor. Patients were followed clinically and with radiostereometry at a minimum of 2 years. We compared gross radiographic appearances, including the depth of penetration of cement and the incidence of postoperative and 2-year radiolucent lines. There was no difference in proximal migration between the two groups. No improvement of fixation was proven from the measured translations and rotations of the socket in the suction group. We found no difference in the number or extent of radiolucent lines or the depth of cement penetration when the iliac suction device was used in conjunction with contemporary cementing techniques. Although the data suggest no short-term advantage in this small study, we will continue to follow these patients presuming there will be improved outcomes in the longer term and since the device provides an easier method of obtaining adequate fixation, especially if technical difficulties are encountered during the pressurization procedure.
doi:10.1007/s11999-008-0574-z
PMCID: PMC2635462  PMID: 18998193
24.  Press-fit cementless acetabular fixation with and without screws 
International Orthopaedics  2013;38(1):7-12.
Purpose
Cementless acetabular fixation for total hip arthroplasty (THA) is widely used. The question of using screws for a better primary and secondary acetabular fixation has been discussed in the literature in recent years. The aim of this meta-analysis was to compare fixation of acetabular cups with and without screws in total hip arthroplasty.
Methods
Electronic databases Embase, PubMed and Cochrane Library were used to search for randomised controlled trials reported through May 2013 of cementless acetabular fixation for THA with and without screws. Two independent reviewers assessed the trials for eligibility and quality. All related data matching our standards were abstracted for meta-analysis by RevMan 5.0. Evaluation criteria included revisions, migration and osteolysis.
Results
A total of 1,130 THAs enrolled into five trials were included in this meta-analysis. All studies compared fixation of acetabular cups with and without screws, and our pooled data showed no statistical significance between the two surgical methods in revision, migration and osteolysis.
Conclusion
There is no significant difference between cementless acetabular fixation for THA with and without screws in revisions, migration or osteolysis.
doi:10.1007/s00264-013-2075-2
PMCID: PMC3890122  PMID: 23982638
Press fit acetabular fixation; With screws; Without screws; No difference
25.  One-Screw Fixation Provides Similar Stability to That of Two-Screw Fixation for Type II Dens Fractures 
Background
Anterior screw fixation has been widely adopted for the treatment of Type II dens fractures. However, there is still controversy regarding whether one- or two-screw fixation is more appropriate.
Questions/Purposes
We addressed three questions: (1) Do one- and two-screw fixation techniques differ regarding shear stiffness and rotational stiffness? (2) Can shear stiffness and rotational stiffness after screw fixation be restored to normal? (3) Does stiffness after screw fixation correlate with bone mineral density (BMD)?
Methods
We randomly assigned 14 fresh axes into two groups (seven axes each): one receiving one-screw fixation and another receiving two-screw fixation. Shear and torsional stiffness were measured using a nondestructive low-load test in six directions. A transverse osteotomy then was created at the base of the dens and fixed using one or two screws. Shear and torsional stiffness were tested again under the same testing conditions.
Results
Mean stiffness in all directions after screw fixation was similar in both groups. The stiffness after one- and two-screw fixation was not restored to normal: the mean shear stiffness restored ratio was less than 50% and the mean torsional stiffness restored ratio was less than 6% in both groups. BMD did not correlate with mean stiffness after screw fixation in both groups.
Conclusions
One- and two-screw fixation for Type II dens fractures provide similar stability but neither restores normal shear or torsional stiffness.
Clinical Relevance
One-screw fixation might be used as an alternative to two-screw fixation. Assumed BMD should not influence surgical decision making.
doi:10.1007/s11999-012-2389-1
PMCID: PMC3369094  PMID: 22585352

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