Femoral stress shielding in cementless THA is a potential complication commonly observed in cementless distally loading press-fit stems. Long-term metaphyseal fixation and proximal load transfer is desired. Is routine autologous metaphyseal bone impaction and proximal primary stability an answer to this goal?

This prospective study describes long-term femoral bone remodeling and load transfer in cementless THA at a mean of 17 years (range: 15 to 20 years) in 208 consecutive fully HA-coated stems (Corail). All primary THA were performed by one group of surgeons between 1986 and 1991. The concept of surgical technique included impaction of autologous metaphyseal bone using bland femoral broaches until primary stability was achieved without distal press-fit.

Radiographic evaluation revealed a total of five (2.4%) stems with periprosthetic osteolysis, which were associated with eccentric polyethylene wear. They were either revised or awaiting revision. The remaining 97.6% stems revealed desired proximal load transfer in the metaphysis (52%) or in both metaphysis and diaphysis (48%). Distal stress shielding was not observed and was considered to be related to: impaction of metaphyseal bone, bland broaches, HA coating, and prosthetic design.

Biological autologous bone impaction of the metaphysis provides both primary stem stability and successful longterm osteointegration with the Corail stem after 20 years. The surgical technique of proximal autologous bone impaction rather than extraction of cancellous bone material and the use of a fully HA coated stem without distal press-fit show encouraging longterm results in THA.

Introduction

The addition of hydroxyapatite in cementless total knee arthroplasty is believed to reduce the time for implant fixation and rehabilitation, reduce the incidence of RLLs and provide long lasting implant stability, through improved osseointegration. We report the results of a prospective, randomised controlled single blinded study comparing the post operative pain, biological fixation and clinical outcomes with the LCS Complete Porocoat and the hydroxyapatite-coated, LCS Complete Duofix mobile-bearing knee systems.

Femoral stress shielding in cementless THA is a potential complication commonly observed in distally loading press-fit stems. This prospective study describes long-term femoral bone remodeling in cementless THA at a mean of 17 years (range: 15 to 20) in 208 consecutive fully HA-coated stems (Corail, DePuy Int. Ltd, Leeds, UK).

All THA were performed by one group of surgeons between 1986 and 1991. The concept of surgical technique included impaction of metaphyseal bone utilizing bland femoral broaches until primary stability was achieved without distal press-fit. Radiographic evaluation revealed a total of five (2.4%) stems with periprosthetic osteolysis, which were associated with eccentric polyethylene wear. They were either revised or awaiting revision surgery. The remaining 97.6% stems revealed biologic load transfer in the metaphysis alone (52%) or in both metaphysis and diaphysis (48%).

Stem survival of 97.6% after 15 to 20 years without stress shielding were considered to be related to: impaction of metaphyseal bone, bland broaches, HA coating, and unique prosthetic design.

Femoral stress shielding in cementless THA is a potential complication commonly observed in distally loading press-fit stems. This prospective study describes long-term femoral bone remodeling in cementless THA at a mean of 17 years (range: 15 to 20) in 208 consecutive fully HA-coated stems (Corail, DePuy Int. Ltd, Leeds, UK). All THA were performed by one group of surgeons between 1986 and 1991. The concept of surgical technique included impaction of metaphyseal bone utilizing bland femoral broaches until primary stability was achieved without distal press-fit. Radiographic evaluation revealed a total of five (2.4%) stems with periprosthetic osteolysis, which were associated with eccentric polyethylene wear. They were either revised or awaiting revision surgery. The remaining 97.6% stems revealed biologic load transfer in the metaphysis alone (52%) or in both metaphysis and diaphysis (48%). Stem survival of 97.6% after 15 to 20 years without stress shielding were considered to be related to: impaction of metaphyseal bone, bland broaches, HA coating, and unique prosthetic design.

We present a prospective study focused on radiographic long-term outcomes and bone remodeling at a mean of 17.0 years (range: 15 to 20) in 208 cementless fully HA-coated femoral stems (Corail®, DePuy, Johnson & Johnson). Total hip replacements in this study were performed by three members of the surgeon design team (Artro Group) in France between 1986 and 1991. Radiographic evaluation focused on periprosthetic osteolysis, bone remodeling, osseous integration, subsidence, metaphyseal or diaphyseal load transfer, and femoral stress shielding. The radiographs were digitized and examined with contrast enhancing software (DICOM Anonymizer 1.1.2) for analysis of the trabecular architecture. Radiographic signs of aseptic stem loosening were visible in two cases (1%). Three stems (1.4%) showed metaphyseal periprosthetic osteolysis in two of seven Gruen zones associated with eccentric polyethylene wear awaiting metaphyseal bone grafting and cup liner exchange. One stem (0.5%) was revised due to infection. No stem altered in varus or valgus alignment more than two degrees and mean subsidence was 0.1 mm (range: 0 to 2) after a mean of 17.0 years. Five stems (2.4%) required or are awaiting revision surgery. Trabecular orientation and micro-anatomy suggested proximal load-transfer patterns in all except three cases (98.6%). Combined metaphyseal and diaphyseal osseo-integration and bone remodeling were visible in one hundred stems (48%). Diaphyseal stress shielding and cortical thickening were observed in three stems (1.4%). Other radiographic features are discussed in depth. This long-term study of 208 fully HA-coated Corail stems showed highly satisfactory osseo-integration and fixation in 97.6% after a mean of 17.0 years follow-up.

Patella management in total knee arthroplasty remains controversial. Minimizing patella related problems is the main goal in any type of knee arthroplasty. This can be achieved with and without resurfacing. However, patella resurfacing resulted in, at times, catastrophic failures, which increased the popularity of patella non resurfacing, particularly with anatomical femoral groove designs. If patella non resurfacing is to be recommended, clinical outcomes must be equal or better than those of routine patella resurfacing in the specific prosthesis utilized.

From a large cohort of over 6000 TKA five studies were conducted to analyze isokinetic strength, subjective, clinical, and radiographic outcomes as well as histopathological data.

Isokinetic strength, subjective, clinical, and radiographic outcomes favor nonresurfacing in TKA with proper femoral component rotation and conforming patellar groove. Our data indicate that patella subluxation and femoral component malrotation is significantly associated with development of arthrofibrosis.

On the base of our studies we propose specific surgical techniques for optimal patella treatment (patelloplasty) in TKA.

Aims: The purpose of this study was to evaluate the clinical outcome of 457 LCS mobile bearing TKA from one centre.

Methods: From a cohort of over 3.500 mobile bearing TKA in one large center, 457 cases were performed more than 10 years ago (mean 11 years). Drop-out were 63 (13.8%) cases, 128 patients were known to have died and 63 (13.2%) cases could not be included leaving 86.2% that entered the study. Patient demographics included 76% females and 8% rheumatoids. There were 275 (60%) meniscal bearing and 182 rotating platform design components. The patella was resurfaced in 95 (21%) cases.

Results: Preoperative KSS scores improved from a mean of 84 to 157 points and mean range of motion from 97 to 110 degrees postoperatively. Clinical scores were excellent or good in 88%, fair in 10% and poor in 2%. Kaplan Meier survival analysis was 96.9% after a mean of 11 years taking any revision into account. Worst track records were polyethylene meniscal bearings with 91.2% and best the femoral component with 99.8% after a mean of 11 years. Other complications will be listed in depth.

Conclusion: Best track record was noted with the all cruciate sacrificing rotating bearing device and worst with the ACL and PCL retaining meniscal bearing device. Patella also jeopardized the long-term results.

Aims: Cementless fixation in TKA remains controversial because of less predictable osseointegration and difficulty interpreting fixation interfaces.

Methods: This study evaluated 567 consecutive primary LCS mobile-bearing TKA with in-depth RLZ analysis of all cases by one author (T.K.). Mean follow-up was 5.7 years (2.0–14.9), mean age 69 years (70% females). Diagnosis included 8.3% rheumatoids. The same poro-coated femoral and patella components were utilized. Tibial components included a 3-fin (ACL/PCL-retaining) or tapered-cone design (PCL-retaining/substituting). Bone treatment included generous use of autograft: cortico-cancellous struts for slope-off deformities and soft bone, morselized impaction for central zones, slurry to achieve interference fit.

Results: Good/excellent results were 94.7%. Minimal femoral/patella lucencies; Tibial tapered cone (n = 523) had one (0.2%) failure. Lucencies of 1–2 mm (usually isolated) were noted in 2% medial, lateral, posterior and 4% anterior/central zones, all of which remained stable; 3) Tibial 3-fin tibial design (n = 44) had 3 failures (6.8%) with RLZ > 2mm in multiple zones.

Conclusion: Cementless fixation with LCS porocoat prosthesis was successful in all femoral/patellar and 99% of the tibial-cone design. The 3-fin design had multiple RLZ and a higher failure rate (not recommended).

Aims: The purpose of this study was to determine whether internal mal-rotation of the femoral component is associated with arthrofibrosis in TKA. We hypothesized arthrofibrosis may be triggered by a combination of non-physiological kinematics (femoral component internal rotation) and a tight medial compartment.

Methods: From a consecutive cohort of 3058 mobile bearing TKA forty-four (1.4%) cases were diagnosed as having arthrofibrosis, of which thirty-eight (86%) cases could be recruited. Thirty-eight patients with a well functioning TKA served as matched controls. Evaluation included CT investigation to determine femoral component rotation with reference to the transepicon-dylar axis (TEA).

Results: Femoral components in the AF group were significantly (p< 0.00001) internally mal-rotated by a mean of 4.7 degrees ranging from ten degrees internal rotation (IR) to one degree external rotation (ER). Mean femoral rotational in the control group was parallel (0.3 degrees IR) to the TEA (six degrees IR to four degrees ER). Arthrofibrosis was not associated with age, gender, body-mass-index, or preoperative diagnosis.

Conclusions: There is a highly significant association between arthrofibrosis in TKA and internal mal-rotation of the femoral component. On the base of these results it was hypothesized that non-physiological kinematics in TKA with mal-aligned femoral components influence and/or trigger arthrofibrosis in TKA. In TKA with arthrofibrosis, we now consider femoral CT evaluation with the view to surgically rebalancing the flexion gap and realigning the femoral component, when internal mal-rotation is confirmed.

Aims: Patellectomized knees perform poorly with respect to extensor mechanism function and anterior knee pain.

Methods: In the period of 1990 to 1995, nine previously patellectomized patients with a mean age of 55 years (range: 38 to 67) underwent cementless Low-Contact-Stress TKA with autologous reconstruction of a new patella. One patient deceased 5 years post surgery. Mean follow-up was 8.0 years (range: 6 to 12) The autograft was taken in five cases from the iliac crest, in two cases from the posterior femoral condyle and in another two cases from the opposite patella at time of simultaneous bilateral TKA surgery. Evaluation included clinical investigation, specific patella score, radiographic analysis and isokinetic strength measurement at 60 degrees per second (Biodex).

Results: Clinical scores had a mean of 27 out of 30 points (range: 19 to 30) and mean isokinetic strength of knee extension reached 71Nm (81%) compared with the opposite site. One patient with bilateral patellectomy and unilateral TKA showed an increase of 50 % strength (51Nm versus 77Nm) in the knee with TKA and neo-patella. Radiographs in three planes showed minor signs of neo-patella bone resorption in three cases, but evidence of retrabeculation and bone remodelling in all neo-patellae.

Conclusions: Reconstruction of a neo-patella in TKA using autograft provides near to normal isokinetic strength, no evidence of considerable autograft resorption, excellent or good clinical outcome and high patients satisfaction after a mean of 8 years. The study provides encouraging data for reconstructing a new patella in patellectomized knees during TKA.

Accepted landmarks for determining rotation include the posterior condyles, Whiteside’s line, arbitrary 3-4° of external rotation, and transepicondylar axis (TEA). All methods require anatomical identification, which may be variable.

The purpose of this study was to radiologically evaluate femoral component rotation (CT analysis) based on a method that references to the tibial axis and balanced flexion-tension.

Methods: CT scans of 38 randomly selected TKA were evaluated to determine femoral component positioning. Spiral CT scans of the femoral epicondylar region with eight 4mm cuts were performed to accurately identify medial and lateral epicondyles. Rotational alignment was measured in relation to the transepicondylar axis using CT-implemented software by two independent radiologists.

Results: Femoral component rotation ranged from 4° internal rotation to 5° external rotation with a mean of 0.0° = parallel to the TEA. All 38 cases had satisfactory clinical results, range of motion of over 90°, and showed perfect patello-femoral tracking and patellar congruency.

Conclusions: Femoral rotation position based on tibial axis and balanced flexion tension is patient specific, reproducible and results in predictable patella tracking. CT analysis in this study confirms that the tibial axis method produces a consistent femoral component positioning that relates accurately to the TEA. Tibial axis method avoids the need for arbitrary landmark identification, placing the femoral component predictably in an optimum position in relation to the tibia and patella.

The purpose of this study was to analyse and to recommend solutions for early complications with a new total knee mobile bearing device, that promises a logical synthesis of combined A/P translation and rotation ability, but has shown early surgical technique related complications.

Materials and Methods: There were 244 Low Contact Stress (LCS) A/P glide total knee replacements (TKA) performed in the time between 1995 and 1999. Mean age was 67.2 years (range: 53-83). Mean follow-up was 16.5 months (range: 1-51). There was an unusual high incidence of anterior knee pain in this group compared with excellent results utilising rotating platform LCS TKA in this centre. Diagnostic evaluation included radiographs, arthroscopical evaluation, and positron emission tomography in five selected cases.

Results: There were 11 (4.5%) cases with Hoffa fatpad impingement, progressive ligament instability in 5 (2.0%) cases, arthrofibrosis in 4 (1.6%) cases, one malposition of tibial component, and one proximal tibial AVN. Five PET 18F-FDG scans prior to revision surgery revealed increased up-take correlated with intraoperative findings of fatpad fibrosis and/or necrosis.

Conclusion: The LCS A/P glide mobile bearing TKA has theoretical advantages over both meniscal and rotating mobile bearing knee designs. Early occurrence of Hoffa fatpad impingement was caused by surgical mal-technique in this centre that usually retains the vast majority of the fat pad. Revision surgery revealed evidence of impingement and all cases revealed clinical improved after partial excision of the fatpad. We, therefore, recommend partial to total excision of the Hoffa fat pad for utilisation of the A/P glide prosthesis.

Cementless fixation in TKA remains controversial because of less predictable osseointegration and difficulty interpreting fixation interfaces. Radiolucent zone analysis (RLZ) of plain radiographs is the only practical method of evaluating the fixation interface.

Methods: This study evaluated 567 consecutive primary LCS mobile-bearing TKA with in-depth RLZ analysis of all cases by one author (T.K.). Mean follow-up was 5.7 years (2.0-14.9), mean age 69 years (70% females). Diagnosis included 8.3% rheumatoids. The same porocoated femoral and patella components were utilized. Tibial components included a 3-fin (ACL/PCL-retaining) or tapered-cone design (PCL-retaining/substituting). Bone treatment included generous use of autograft: cortico-cancellous struts for slope-off deformities and soft bone, morselized impaction for central zones, slurry to achieve interference fit.

Results: Good/excellent results were 94.7% with 4 fixation failures. Sequential RLZ of six patellar, four femoral, six tibial zones revealed: 1). Minimal femoral/patella lucencies---no failures; 2) Tibial tapered cone (n = 523) had one (0.2%) failure. Lucencies of 1–2 mm (usually isolated) were noted in 2% medial, lateral, posterior and 4% anterior/central zones, all of which remained stable; 3).Tibial 3-fin tibial design (n = 44) had 3 failures (6.8%) with RLZ > 2mm in multiple zones.

Conclusion: Cementless fixation with LCS porocoat pros-thesis was successful in all femoral/patellar and 99% of the tibial-cone design. The 3-fin design had multiple RLZ and a higher failure rate (not recommended). RLZ analysis with plain X-rays (over time) is a practical method of evaluating cementless fixation and correlates with clinical outcomes in our study.

The purpose of this study was to analyse a potential correlation of arthrofibrosis (AF) and femoral rotational mal-alignment in total knee arthroplasty (TKA). We hypothesized an increased internal mal-rotation of the femoral component leading to unphysiological kinematic motion of the arthroplastic knee joint. These repetitive microtrauma may then induce increased synovial hyperplasia leading to arthrofibrosis. Arthrofibrosis is an ill-defined entity that results in unsatisfactory outcome following TKA. Biological and mechanical factors have been suggested as etiology, but specific causes have not been identified.

Methods: From a cohort of 3058 mobile bearing TKA 44 (1.4%) cases were diagnosed with arthrofibrosis, of which 38 (86%) cases underwent clinical examination and CT investigation to determine femoral component rotation taking the transepicondylar (TEA) axis as reference point. A control group with 38 well functioning TKA was compared.

Results: Increased internal mal-rotation of the femoral component of 5.0° in the AF group (reference to the TEA) was highly significant (p < 0.001) ranging from 10°IR to 1°ER compared with the control group (0.0° parallel to TEA, 4°IR to 5°ER). Men younger than average for index TKA in this center with a decreased BMI, previous knee surgery (particularly correcting osteoto-mies), poliomyelitis, and OA had an increased risk of developing arthrofibrosis. PCL retaining or sacrificing, patella resurfacing or retaining had no increased prevalence for AF. Rheumatoid patients had a decreased risk of developing arthrofibrosis .

Conclusion: The correlation of AF to femoral component internal mal-rotation was statistically significant (p < 0.001). These results confirm that unphysiological kinematics in TKA appear to be a major etiopathological factor for arthrofibrosis (AF). In this study femoral component internal mal-rotation has shown to be a significant risk factor in the development of arthrofibrosis. We, therefore, recommend consideration of early CT evaluation in cases with AF and, when internally mal-rotated, revision of the femoral component.

This study has been cleared by the Ethical Committee, University of Zurich, Switzerland.

Correction of fixed valgus is a challenge in primary TKA. Achieving patello-femoral and femoral-tibial stability requires superficial/deep lateral side releases if non-constrained prostheses are utilized. The medial approach has disadvantages with more reported complications. The direct lateral approach, with/without tubercle osteotomy, is an approach option utilized in two reporting centers.

Methods: 255 valgus TKAs with 5- to15-year follow-up were reviewed. Demographics included 91% females, 15% rheumatoid, mean age 69. Prostheses utilized were LCS mobile-bearing (meniscal PCL-retaining/rotating PCL-sacrificing). Patella was non-resurfaced in 90%; cementless fixation in 86%. The direct lateral approach with similar lengthening techniques was used with tubercle osteotomy in one center and osteo-periosteal joint exposure in another.

Results: Good/excellent 91%, modified HSS score improvement 57 to 85. Deformity (12) improved < 8 to 12 points (> 15o valgus to < 5o valgus). ROM improved from mean 11o/97o to 1/110o latest. Technical/prosthetic-related complications included: 7 bearing failures (5 meniscal, 2 rotating platform), 2 aseptic loosenings (tibial), 1 patella ligament rupture and 2 screw loosenings in the osteotomy group, 1 patella re-dislocation in a 75-year-old female with dislocation since age 15 (non-osteotomy group), 2 infections, and 1 re-operation for arthrofibrosis .

Discussion/Conclusion: Valgus TKA using LCS move-able bearings implanted via a direct lateral approach are highly successful regarding stability and patella tracking. Failures correlate with inadequate/de-stabilizing releases and meniscal PCL-retaining prostheses. Rotating bearings allow for better stability and self-adjustment of common mal-rotation variables. The lateral approach allows for direct (step-wise) lengthening releases, improved patellar tracking, and precise gap balancing.

Aims: The purpose of this study was to evaluate the clinical outcome of 457 LCS mobile bearing TKA from one centre. Methods: From a cohort of over 3.500 mobile bearing TKA in one large center, 457 cases were performed more than 10 years ago (mean 11 years). Drop-out were 63 (13.8%) cases, 128 patients were known to have died and 63 (13.2%) cases could not be included leaving 86.2% that entered the study. Patient demographics included 76% females and 8% rheumatoids. There were 275 (60%) meniscal bearing and 182 rotating platform design components. The patella was resurfaced in 95 (21%) cases. Results: Preoperative KSS scores improved from a mean of 84 to 157 points and mean range of motion from 97 to 110 degrees postoperatively. Clinical scores were excellent or good in 88%, moderate in 10% and poor in 2%. Kaplan Meier survival analysis was 96.9% after a mean of 11 years taking any revision into account. Worst track record were polyethylene meniscal bearings with 91.2% and best the femoral component with 99.8% after a mean of 11 years. Other complications will be listed in depth. Conclusion: Best track record was noted with the all cruciate sacrificing rotating bearing device and worst with the ACL and PCL retaining meniscal bearing device. Patella also jeopardized the long-term results

Aims: Fixed valgus requires lateral releases for stable patellar tracking and gap balancing. Adequate extension space must be achieved without weakening the lateral sleeve. This complication can occur with sub-periosteal femoral LCL/popliteus releases. Distal LCL lengthening and/or lateral epicondylectomy with advancement maintaining soft tissue strength/stability. Methods: 174 valgus TKAs with 5- to 15-year follow-up were reviewed. Demographics included 93% females, 13% rheumatoid, mean age 69. Prostheses utilized were LCS meniscal (30%) and rotating (70%). Fixation was cementless in 86%. The direct lateral approach was used in all cases. Results: Good/excellent results were 91% (HSS scores 54 to 84). Deformity correction mean > 15° to < 5° valgus. Of the failures, 5 were meniscal PCL-retaining (1 malposition, 2 subluxations, 2 wear). Four meniscal and one rotating bearing spin-out were related to inadequate (over/under) concave side balancing, all in early cases with standard femoral sub-periosteal releases. Conclusion: Release of contracted concave side soft tissues, without compromising strength/integrity of the LCL/popliteus complex, is required to achieve stable flexion-extension gap balance and correction of the biomechanical axis in fixed valgus TKA. Improved techniques of lateral side releases that maintain ligament attachments and allow more precise lateral extension gap adjustment have eliminated failures related to soft-tissue imbalance with non-constrained implants. Key technique points of the lateral approach, with emphasis on the deep releases, will be illustrated.

Aims: The purpose of this study was to determine whether internal malrotation of the femoral component is associated with arthroþbrosis in TKA. We hypothesized arthroþbrosis may be triggered by a combination of nonphysiological kinematics (femoral component internal rotation) and a tight medial compartment. Methods: From a consecutive cohort of 3058 mobile bearing TKA forty-four (1.4%) cases were diagnosed as having arthroþbrosis, of which thirty-eight (86%) cases could be recruited. Thirty-eight patients with a well functioning TKA served as matched controls. Evaluation included CT investigation to determine femoral component rotation with reference to the transepicondylar axis (TEA). Results: Femoral components in the AF group were signiþcantly (p< 0.00001) internally mal-rotated by a mean of 4.7 degrees ranging from ten degrees internal rotation (IR) to one degree external rotation (ER). Mean femoral rotational in the control group was parallel (0.3 degrees IR) to the TEA (six degrees IR to four degrees ER). Arthroþbrosis was not associated with age, gender, body-mass-index, or preoperative diagnosis. Conclusions: There is a highly signiþcant association between arthroþbrosis in TKA and internal mal-rotation of the femoral component. On the base of these results it was hypothesized that non-physiological kinematics in TKA with mal-aligned femoral components inßuence and/or trigger arthroþbrosis in TKA. In TKA with arthroþbrosis, we now consider femoral CT evaluation with the view to surgically rebalancing the ßexion gap and realigning the femoral component, when internal mal-rotation is conþrmed.

Aims: This study evaluated the outcome of bilateral hip and knee arthroplasty in the same patient with special regards to schedule planning, postoperative complications and follow-up. Methods: Since 1985 more than 6000 THA and 5500 TKA were implanted in one large center, of which 8% were rheumatoid patients. Quadruple THA and TKA were performed in a total of 58 (0.1%) of which 88% were RA. Mean follow-up of knees was 8.5 years (1–17), of hips 9.5 years (1–18). On average 67% of implants were uncemented. In 21% of the cases all four prostheses were implanted within one year and over 50% within five years. Results: Taking revision of components as failure there were three infections (CLS hip, GSB and LCS knee), two aseptic loosenings (Endler cup, GSB knee), two recurrent hip dislocations, three knee bearing exchanges (LCS, INNEX), and four patella component removal (GSB, PCA). Discussion and Conclusion: Quadruple arthroplasty in the lower extremity did not show an increased failure rate compared with single arthroplasty in this center. The results of this study support the indication for quadruple procedure with early postoperative rehabilitation and full weight bearing. Data suggest a procedure with hips before knees and at least three weeks between any arthroplasty operations.

Aims: This study evaluates the long-term results of cementless Zweymueller stems in total hip arthroplasty (TKA) from 13 to 18 years. Methods: This study evaluated 171 cementless Zweymueller stems. Two different acetabular cups were utilised and the minimum follow-up was 13 years. Of 171 cases 62 had complete follow-up in 1999 with a mean follow-up of 15.1 years (13 to 18). The remaining 109 patients were lost to follow-up, most of which have either died or were not available for other reasons. Results: Of the 62 cases, 41 (66.1%) cases had excellent or good results, 11 cases had moderate (17.7%), and 10 (16.2%) cases had poor results. Radiographic assessment revealed distal migration of more than 3 mm in only one (1.6%) case and no stem demonstrated varus or valgus tilt. Radiolucent lines of 2 mm occurred in 19.4% of the cases, but were limited to less than three of seven zones. Osteolytic cysts were present in 5 cases (7%) and calcar resorption appeared in 5 (7%) cases as well. Of the 171 cases 16 (9.4%) required revision surgery of the stem after a mean of 5.2 years (1 to 15), 8 of which were due to PE wear and osteolysis, 5 due to undersizing of the stem, 3 due to increased thinning of the femoral cortices, and one incidentally at revision of the acetabular cup. Of the 56 cases in which an Endler PE cup was utilised, 29 (51.8%) were revised without revision of the stem. Conclusions: These long-term data support the utilisation of uncemented Zwey-mueller stems in THA.