Loosening Of Femoral Component Research Articles

Cemented and uncemented total hip arthroplasty using the same femoral component.

The purpose of this study was to evaluate the same femoral component after cemented and uncemented total hip arthroplasty. The results were compared in terms of hip scores, subsidence, and survivorship. Between 1986 and 1996, 1017 primary THAs were implanted in 882 patients using the same porous-coated, titanium-alloy, femoral component. 507 cemented stems (441 patients) and 510 uncemented stems (441 patients) were compared. The primary diagnosis was osteoarthritis in 866 hips (85%). 541 patients were female (61%). The clinical results were evaluated based on the Harris hip score. Radiographs were evaluated at each follow-up for stem subsidence and loosening. Kaplan-Meier survival analysis was used to determine stem survivorship. The average follow-up of the entire cohort was 13.2 years (range, 2-26 y). The average Harris Hip Scores at 20 years follow-up was 87 points in the cemented group and 85 points in the uncemented group. Pain scores averaged 42 and 38 in the cemented and uncemented group, respectively, at 20 years. There were 6 loose stems identified in the cemented group (1.2%) and 2 loose stems in the uncemented group (0.4%). Cemented and uncemented stem survivorship at 20 years was 98.1% and 99.6%, respectively. There was no difference in cemented or uncemented stem survivorship at any time period. Although there were more cases of aseptic cemented femoral component loosening, there was no significant difference in stem survivorship out to 20 years whether this stem was implanted with or without cement.

Clinical value of SPECT/CT in the painful total knee arthroplasty (TKA): a prospective study in a consecutive series of 100 TKA.

Bone single photon emission computed tomography (SPECT)/CT is considered as beneficial in unhappy patients with pain, stiffness or swelling after total knee arthroplasty (TKA). The purpose of this study was to identify typical patterns of bone tracer uptake (BTU), distribution and intensity values in patients after TKA. The above findings were correlated with the type and fixation of TKA, the time from TKA and intraoperative findings at revision surgery. A total of 100 knees of 84 consecutive patients (mean age ± SD 70 ± 11 years) after TKA with persistent knee pain were prospectively included. All patients underwent clinical examination, standardized radiographs and (99m)Tc-hydroxymethane diphosphonate (HDP) SPECT/CT as part of a routine diagnostic algorithm. The diagnosis before and after SPECT/CT and final treatment were recorded. TKA component position was determined on 3-D reconstructed images. Intensity and anatomical distribution of BTU was determined. Maximum intensity values were recorded as well as ratios in relation to the proximal midshaft of the femur. Univariate analyses (chi-square test, Pearson's correlation and t test for independent samples) were performed (p < 0.05). SPECT/CT changed the clinical diagnosis and final treatment in 85/100 (85 %) knees. Intraoperative findings confirmed the preoperative SPECT/CT diagnosis in 32/33 knees (97 %). TKA loosening as well as progression of patellofemoral osteoarthritis (OA) was correctly diagnosed in 100 % of knees. Typical patterns of BTU for specific pathologies were identified. Loose femoral TKA components significantly correlated with increased BTU at the lateral femoral regions (p < 0.05). Loose tibial TKA components significantly correlated with increased BTU at all tibial regions (p < 0.05) and around the tibial peg (p > 0.01). The diagnostic benefits of SPECT/CT in patients after TKA have been proven. Typical pathology-related BTU patterns were identified, which will improve reporting quality. Due to the benefits in establishing the correct diagnosis, SPECT/CT should be part of the routine diagnostic algorithm for patients with pain after TKA.

Surface replacement: A viable option for the right patient

Surface replacement of the hip was established in the 1970s as a bone preserving alternative to total hip replacement. However, problems with femoral neck fracture, osteolysis, and component loosening led to early failures and an abandonment of the procedure. The modern hip resurfacing has improved upon past results with new implant designs and materials. The benefits include the preservation of bone, lower dislocation rate, and more physiologic bone loading, factors which may lead to an ability for a higher activity level. National joint registry results find that a certain group of patients has greater survivorship with resurfacing than with total hip replacement. Therefore, we believe that surface replacement arthroplasty is a viable alternative in this subgroup of patients.

High rate of implant loosening for uncemented resurfacing-type medial unicompartmental knee arthroplasty.

To determine the medium-term implant survivorship, the clinical results and the failure mechanisms of a novel unicompartmental arthroplasty for uncemented resurfacing of the medial tibio-femoral compartment. Seventy-six consecutive patients were prospectively evaluated with a mean final follow-up of 6years (SD 5.3months). In 44 patients, the diagnosis was osteoarthritis, and in 32 patients, it was avascular necrosis of the medial femoral condyle. The Hospital for Special Surgery Score was used for objective clinical evaluation, and a self-administered visual analogue scale was used to quantify residual pain at each observation point. Implant survivorship was determined assuming revision for any reason as endpoint. Nineteen patients were revised (6 with osteoarthritis and 13 with avascular necrosis of the medial femoral condyle). The mean interval time from index surgery to revision was 11.2months (SD 4.66months). Implant survivorship was higher in patients with osteoarthritis with respect to those with avascular necrosis of the medial femoral condyle (p=0.018). Aseptic loosening was the most frequent failure mechanism. Femoral component loosening was reported in five patients and tibial component loosening was reported in other six patients. Assuming revision for any reason as endpoint, an implant survivorship of 74.3% at 6-year follow-up was determined. In the remaining 57 patients, satisfactory clinical results were obtained. Hospital for Special Surgery Score and visual analogue scale for residual pain showed significant improvements (p<0.03 and p<0.045, respectively). At the present time, the standard cemented implants and the conventional designs for unicompartmental knee replacement still represent the optimal solution. The authors do not recommend the widespread use of this technique. IV.

Periprosthetic fractures around loose femoral components.

The development of periprosthetic fractures around loose femoral components can be a devastating event for patients who have undergone total hip arthroplasty (THA). As indications for THA expand in an aging population and to use in younger patients, these fractures are increasing in incidence. This review covers the epidemiology, risk factors, prevention, and clinical management of periprosthetic femoral fractures. Treatment principles and reconstructive options are discussed, along with outcomes and complications. Femoral revision with a long-stem prosthesis or a modular tapered stem is the mainstay of treatment and has demonstrated good outcomes in the literature. Other reconstruction options are available, depending on bone quality. Surgeons must have a sound understanding of the diagnosis and treatment of periprosthetic femoral fractures.

Twenty-year followup of an uncemented stem in primary THA.

Uncemented stems have been used in THA for well over two decades, but there are relatively few studies reporting on the results after 20years. The purpose of this study was to evaluate at a minimum followup of 20years (1) hip scores; (2) radiographic findings, including stem fixation and osteolysis; (3) reoperations; and (4) survivorship free from aseptic loosening in a group of patients who underwent primary THA using a proximally porous-coated, plasma-sprayed, straight-stemmed, titanium-alloy femoral component. Between 1987 and 1993, we performed 1517 primary THAs, of which 447 were cementless, and 157 used the implant under study here (representing 10% of the THAs during the period in question). General indications for the use of the study stem included (1) younger age with relatively stronger bone (average age 55years in this study); (2) patients not involved in another study protocol (as were the 278 other cementless hips implanted during this time); and (3) patients who, at the surgeon's discretion, would be compliant with protected weightbearing. Of those, 111 were available for followup at a minimum of 20years (mean, 20years), whereas 36 had died and nine (6%) were lost to followup or declined participation. The primary diagnosis was osteoarthritis in 77 hips (69%). The mean age at operation was 55years. The clinical result was evaluated on the basis of the Harris hip score. Radiographic analysis was performed at each followup visit for distal cortical hypertrophy, spot welds, radiolucencies, stem subsidence, varus or valgus shift, osteolysis, and femoral component loosening. Kaplan-Meier analysis was performed to evaluate the survival of the femoral component. The mean Harris hip score improved from 46 points to 87 points (of a possible 100 points) at the most recent followup. All hips had evidence of proximal femoral remodeling consistent with osseous ingrowth. Femoral osteolyis was seen in 22 hips (20%). One stem was revised as a result of a periprosthetic fracture. No femoral component had evidence of loosening, and none was revised. Thirty-three acetabular components (30%) were revised. This femoral component provided durable long-term fixation for over two decades after THA. The porous stem geometry is still in use today and will continue to be studied into the third decade of use. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Revision Total Hip Arthroplasty with Retained Acetabular Component.

Aseptic loosening and osteolysis commonly limit the survivorship of total hip prostheses. Retention of a well-fixed acetabular component, rather than full acetabular revision, has multiple advantages, but questions have lingered regarding the clinical success and prosthetic survivorship following this procedure. We examined the impact of acetabular component position, polyethylene type, liner insertion technique, femoral head size, and simultaneous revision of the entire femoral component (as opposed to head and liner exchange) or bone-grafting on mid-term to long-term prosthetic survival following such limited revisions. One hundred hips in 100 patients with osteolysis, polyethylene wear, or femoral component loosening underwent revision total hip arthroplasty with retention of the acetabular component. Acetabular component inclination and anteversion were measured on prerevision radiographs and were categorized according to predetermined positional safe zones (inclination of 35° to 55° and anteversion of 5° to 25°). Operative reports were reviewed for femoral head size, polyethylene liner type (conventional or highly cross-linked), liner insertion technique (use of the existing locking mechanism or cementation), whether the patient had revision of the entire femoral component, and use of bone graft. Outcomes of interest included the Harris hip score, University of California at Los Angeles (UCLA) activity score, episodes of instability, and need for repeat revision. At an average of 6.6 years (range, two to fourteen years) postoperatively, the Harris hip and UCLA activity scores were both significantly improved compared with the preoperative scores (p < 0.0001 and p < 0.01, respectively). Overall, the failure rate was 13%. In addition, 6% of the patients had postoperative instability. Hips in which the acetabular component was outside of the safe zone for inclination had a higher rate of failure (p = 0.048). Use of conventional, rather than highly cross-linked, polyethylene at the time of revision was also associated with an increased rate of repeat revision (p = 0.025). Revision total hip arthroplasty with retention of the acetabular component is associated with good outcomes in hips with an appropriately positioned, well-fixed acetabular component. Acetabular components outside the safe zone for inclination were at a higher risk for failure, as was use of conventional polyethylene. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Mid-term result of ceramic bearings in total hip arthroplasty.

The purpose of this study was to evaluate our clinical experience with ceramic-on-ceramic cementless total hip arthroplasty (THA) and complications after an average follow-up of more than eight years. From January 2001 to December 2008, 540 THA with ceramic-on-ceramic bearings were performed in 448 patients (92 bilateral, 54 of which were operated simultaneously) with a mean age 49.9 years (range 18-84) by a senior surgeon. Pre-operative aetiological reasons were developmental dysplasia of the hip (DDH) in 205 hips, degenerative arthritis in 157 hips, avascular necrosis in 51 hips, rheumatoid diseases in 40 hips, posttraumatic arthritis in 40 hips, other reasons in 25 hips and revision surgery in 22 hips. Patients were evaluated with Harris hip score (HSS), and radiological findings of acetabular and femoral component loosening or osteolysis with ceramic bearing related complications like squeaking, liner and head fractures were recorded. The average duration of follow-up time was 8.2 years (range, five to 13.2). The main Harris hip score increased from 42.4 points preoperatively to 94.9 points at the time of last follow-up. We had one fracture of the ceramic head, 11 clicking and four squeaking; one of them was revised because of terrible squeaking due to acetabular liner fracture, the other three were seldom audible from the outside and followed conservatively. We did not observed loosening or osteolysis due to ceramic bearings at the time of the final follow-up. Our study has demonstrated that ceramic-on-ceramic bearings can be used safely in different etiological problems. Incidences of noisy hips are becoming less frequent.

Outcomes After Revision of Metal-on-Metal Hip Resurfacing Arthroplasty

We report the results of 58 hip resurfacing arthroplasties (HRA) revised by a single surgeon with an average of 5.2±2.6years follow-up. The four most common causes for revision were acetabular component loosening, femoral neck fracture, femoral component loosening, and adverse wear related failure (AWRF). In 95% of cases (55/58), the revision bearing was a large metal-on-metal type including all seven AWRF cases; three cases were revised to ceramic-on-polyethylene. There were two repeat revisions due to acetabular component loosening. Revision of AWRF had an excellent outcome using limited debridement and a stable large metal bearing placed in the correct position. The only problematic group was the one revised for acetabular loosening in which 2/16 (6%) required repeat revision for failure of acetabular fixation.

What is the survivorship of fully coated femoral components in revision hip arthroplasty?

Femoral revision using fully coated femoral components offers distinct advantages in patients with notable bone loss. With the increasing concerns being raised about the problems of stem modularity, the results and complications of revision arthroplasty using devices with limited modularity are important. We therefore asked: (1) What is the frequency of infection, aseptic loosening, and reoperations after use of these components? (2) What is the frequency of intraoperative fracture of the femur when using these components and are there any identifiable factors related to these fractures? (3) What is the 10-year survivorship of these components, and are there any identifiable factors related to survival and rerevision? We retrospectively reviewed prospectively obtained data on 96 patients undergoing 104 revisions with fully coated components of two different manufacturers; six patients had died (6%) and six were lost to followup (6%) before 2 years. Data on intraoperative fracture, aseptic loosening, and reoperation were analyzed. Ninety-two hips, with a minimum followup of 2 years (mean, 8 years; range, 2-16 years), were evaluated for radiographic evidence of loosening. Intraoperative fracture frequency and Kaplan-Meier survivorship was calculated to 10 years for the entire cohort of 104 hips. Demographic, radiographic, and operative factors associated with implant survival and intraoperative fracture were analyzed using chi-square and Wilcoxon tests. There were three infections, nine hips (10%) had femoral component loosening (six rerevised), and there were seven other reoperations. Intraoperative complications in 17 hips (17%; 11 diaphyseal fractures, four perforations, two proximal fractures) were treated with allograft strut and cable fixation in 14 hips. Intraoperative femoral complication was more likely with the use of a curved stem [17 of 76, 22% curved; 0 of 28 straight stems (p=0.005)]. With failure defined as femoral component revision for aseptic loosening or radiographic evidence of loosening, implant survival was 88% at 10 years. Those femurs with Paprosky Grades 3B and 4 defects had a higher risk of loosening (3 of 10 for Grades 3B and 4 versus 6 of 94 hips [6%] for Grades 1, 2, 3A; p=0.03). As concerns about stems with more modularity become more prominent, we find the durability of the approach using fully coated femoral components reassuring, but we will continue to follow these patients in the longer term. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Should primary care physicians perform routine long-term follow-up of total hip arthroplasty patients?

BackgroundIt has been suggested by some that follow-up of primary total hip arthroplasty (THA) patients should be performed by primary care physicians (general practitioners or GP’s in the UK), rather than by orthopaedic specialists. Such follow-up would, most likely, include radiographic follow-up based on review of radiographic reports. AimTo look at the quality of the radiographic reports to determine their usefulness as a method of radiographic follow-up of THAs. MethodsPre-revision radiographs of 50 patients were interpreted by a senior orthopaedic registrar, supervised by a consultant with a revision THA practice. This acted as the control against which the findings stated on the radiologist’s report of the same radiograph were compared. Signs of failure were categorised into loosening, bone lysis and polyethylene wear. ResultsComparison to previous radiographs was performed by radiologists in only 42% of cases. Fixation type (cemented/uncemented) was stated in the radiologists report in only 2 cases (4%) and was correct in one. Acetabular component loosening was missed by radiologists in 24% of cases and femoral component loosening in 55%. Radiologists missed osteolysis on the acetabular side in 67% of cases and on the femoral side in 57%. Radiologists failed to report polyethylene wear in 93% of cases. DiscussionThe radiographs reviewed contained definite evidence of failure, being pre-revision radiographs. Vital information, essential in prompting specialist review, was lacking in the radiologists' report and primary care physicians using these reports for radiographic follow-up would have been falsely reassured that all was well with the prosthesis in a significant number of cases. We feel that proposals for primary care based follow-up of THAs that depend on review of radiological reports as a surrogate for specialist review of the radiographs themselves are not safe.

Squatting-related tibiofemoral shear reaction forces and a biomechanical rationale for femoral component loosening.

Previous gait studies on squatting have described a rapid reversal in the direction of the tibiofemoral joint shear reaction force when going into a full weight-bearing deep knee flexion squat. The effects of such a shear reversal have not been considered with regard to the loading demand on knee implants in patients whose activities of daily living require frequent squatting. In this paper, the shear reversal effect is discussed and simulated in a finite element knee implant-bone model, to evaluate the possible biomechanical significance of this effect on femoral component loosening of high flexion implants as reported in the literature. The analysis shows that one of the effects of the shear reversal was a switch between large compressive and large tensile principal strains, from knee extension to flexion, respectively, in the region of the anterior flange of the femoral component. Together with the known material limits of cement and bone, this large mismatch in strains as a function of knee position provides new insight into how and why knee implants may fail in patients who perform frequent squatting.

A new design of cemented stem using functionally graded materials (FGM).

One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem.

Material tailoring of the femoral component in a total knee replacement to reduce the problem of aseptic loosening

Aseptic loosening of femoral components is a significant problem affecting the life of current total knee replacements. To help reduce the problem of aseptic loosening, a new metal–ceramic poros functionally graded biomaterial (FGBM) has been designed to replace the existing metal alloy material normally used. In order to investigate the effect of using a FGBM on distal femur stresses compared to using standard material in a femoral component, a three-dimensional finite element model of the knee prosthesis has been developed. The results of the modeling and subsequent analysis indicate that by using the new FGBM compared to the existing material in a femoral component, higher levels of stress can be realized in the adjacent bone area of the femur and as a consequence reduce harmful atrophy effects. Also, by a judicious choice of material combinations and variation of porosity in the FGBM, the surface properties can be tailored to improve wear resistance at the articular interface and bone anchorage at the femoral end, as well as varying the stiffness in the core of the femoral component. Therefore, the use of the new FGBM improves the performance of knee prostheses by addressing concurrently the three current leading causes of failure; stress-shielding of the bone by the implant, wear of the articular surfaces, and the development of soft tissue at the bone/prosthesis interface as a result of relative implant motion.

Probability of mechanical loosening of the femoral component in high flexion total knee arthroplasty can be reduced by rather simple surgical techniques

BackgroundSome follow-up studies of high flexion total knee arthoplasties report disturbingly high incidences of femoral component loosening. Femoral implant fixation is dependant on two interfaces: the cement–implant and the cement–bone interface. The present finite-element model (FEM) is the first to analyse both the cement–implant interface and cement–bone interface. The cement–bone interface is divided into cement–cancellous and cement–cortical bone interfaces, each having their own strength values. The research questions were: (1) which of the two interfaces is more prone to failure? and (2) what is the effect of different surgical preparation techniques for cortical bone on the risk of early failure.? MethodsFEM was used in which the posterior-stabilized PFC Sigma RP-F (DePuy) TKA components were incorporated. A full weight-bearing squatting cycle was simulated (ROM=50°–155°). An interface failure index (FI) was calculated for both interfaces. ResultsThe cement-bone interface is more prone to failure than the cement implant interface. When drilling holes through the cortex behind the anterior flange instead of unprepared cortical bone, the area prone to early interface failure can be reduced from 31.3% to 2.6%. ConclusionThe results clearly demonstrate high risk of early failure at the cement–bone interface. This risk can be reduced by some simple preparation techniques of the cortex behind the anterior flange. Clinical relevanceHigh-flexion TKA is currently being introduced. Some reports show high failure rates. FEM can be helpful in understanding failure of implants.

Outcomes at least 10 years after cemented PF® (Zimmer) total hip arthroplasty: 83 cases

Cementless total hip arthroplasty (TKA) is gaining ground over cemented TKA. The objective of this study was to assess survival rates of a cemented THA implant (PF(®), Zimmer), after at least 10 years and to assess changes in acetabular bone structure. Eighty-three ceramic-on-polyethylene THA prostheses were implanted between 1998 and 2001.Clinical outcomes were assessed using the Harris hip score and Postel Merle d'Aubigné score. For each hip, radiographs were examined for acetabular radiolucent lines, geodes, and granulomas; in addition, changes in bone structure and trabeculae were assessed comparatively to the other hip and classified from no change to severe osteolysis. Changes in trabeculae served to assess the loads applied to the bone. Polyethylene wear was assessed using the Livermore method. A single patient was lost to follow-up. At last follow-up, 16 patients had died and six were contacted and had not required revision surgery; the remaining 52 patients (59 THAs) were re-evaluated and none had evidence of loosening. The Harris hip score at last evaluation was 91.6 compared to 60.5 preoperatively. No hips had evidence of acetabular osteolysis. For two hips, the radiographs showed complete acetabular radiolucent lines less than 2mm in width, with no mobilisation. Trabecular distribution was homogeneous with no stress shielding. Mean annual rate of wear was 0.08mm. No instances of femoral component loosening were recorded; granulomas involving no more than five Gruën zones were seen in three cases. This study confirms the reliability of cemented THA, with a 12-year survival rate of 98.3%, in keeping with earlier data. Thus, our results establish that cemented ceramic-on-polyethylene prostheses remain valid options for THA. IV.

Acute Total Hip Arthroplasty in Acetabular Fractures in the Elderly Using the Octopus System: Mid Term to Long Term Follow-Up

Patients older than 55 years presenting with acetabular fractures fulfilling the criteria for acute total hip arthroplasty (THA) were included. Cementless THA was done using the Octopus System and autologous bone grafting. 15 patients were available for latest follow up. The average follow-up was 81.5months (62–122months). Mean Harris Hip Score was 91.1. 10 patients were walking without any support while 5 were using a cane. There were no cases of acetabular or femoral component loosening. This method of treatment is promising in the older population as there is deficiency of bone stock which may lead to fixation failures. It is, therefore, worthwhile to recommend primary THA using the Octopus system in the successful management of selected types of acetabular fractures in the elderly.

Prevalence, Risk Factors, and Management of Proximal Femoral Remodeling in Revision Hip Arthroplasty

The prevalence of, risk factors, and management of proximal femoral remodeling in revision total hip arthroplasty is unknown. Therefore, we reviewed the files of 200 consecutive femoral revision arthroplasties to study this phenomenon. Remodeling was considered present if a properly sized diaphyseal-engaging acrylic template had appropriate distal canal fill but lied within 2mm of the proximal lateral endosteal cortex (definition 1) or completely outside the femoral canal (definition 2) on anteroposterior femoral radiographs. The prevalence of remodeling was 42% by definition 1 and 21% by definition 2. The strongest risk factors were loose femoral components and more severe femoral bone loss. Orthopedic surgeons performing revision arthroplasty should be prepared to encounter remodeling as its presence can complicate femoral component revision.

Fracture of an Oxford femoral component: A case report

Component fracture is a rare complication after knee replacement, especially in contemporary designs. We report the first case of a fractured femoral component in a cemented Oxford unicondylar knee prosthesis, 9years after its implantation. Factors leading to this rare kind of component failure are discussed. Revision should be warranted in cases of unicondylar femoral component loosening, eliminating the risk of component fracture, especially in obese patients.

Brief Followup Report: Does High-flexion Total Knee Arthroplasty Allow Deep Flexion Safely in Asian Patients?

The long-term survivorship of TKA in Asian countries is comparable to that in Western countries. High-flexion TKA designs were introduced to improve flexion after TKA. However, several studies suggest high-flexion designs are at greater risk of femoral component loosening compared with conventional TKA designs. We previously reported a revision rate of 21% at 11 to 45 months; this report is intended as a followup to that study. Do implant survival and function decrease with time and do high-flexion activities increase the risk of premature failure? We prospectively followed 72 Nexgen LPS-flex fixed TKAs in 47 patients implanted by a single surgeon between March 2003 and September 2004. We determined the probability of survival using revision as an end point and compared survival between those who could and those who could not perform high-flexion activities. Minimum followup was 0.9 years (median, 6.5 years; range, 0.9-8.6 years). Twenty-five patients (33 knees) underwent revision for aseptic loosening of the femoral component at a mean of 4 years (range, 1-8 years). The probability of revision-free survival for aseptic loosening was 67% and 52% at 5 and 8 years, respectively. Eight-year cumulative survivorship was lower in patients capable of squatting, kneeling, or sitting crosslegged (31% compared with 78%). There were no differences in the pre- and postoperative mean Hospital for Special Surgery scores and maximum knee flexion degrees whether or not high-flexion activities could be achieved. Overall midterm high-flexion TKA survival in our Asian cohort was lower than that of conventional and other high-flexion designs. This unusually high rate of femoral component loosening was associated with postoperative high-flexion activities.