The fate of the remaining knee(s) or hip(s) in osteoarthritic patients undergoing a primary TKA or THA.

The purpose of this study was to determine the fate of the remaining hip(s) and knee(s) following an initial total hip or knee arthroplasty in 5352 patients with idiopathic osteoarthritis who were followed for a minimum ten years (mean 17.8 ± 5.7 years). Following an initial primary TKA, 46.0% of patients had a contralateral TKA, 2.3% had an ipsilateral THA and 1.3% had a contralateral THA. Following an initial primary THA, 30.5% of patients had a contralateral THA, 6.8% had an ipsilateral TKA and 2.9% had a contralateral TKA. Cox regression analysis demonstrated that BMI was the sole risk factor for a second THA, but both age less than sixty years and a higher BMI were significant factors for patients requiring an additional primary TKA.

Calf serum constituent fractions influence polyethylene wear and microbial growth in knee simulator testing.

Calf serum lubricants consisting of various polypeptide constituent fractions are routinely used in knee wear simulators as part of the standardized test protocol. Three calf sera (bovine, new-born and alpha) were diluted as per the recommendation of ISO 14243-3 and used in displacement-controlled knee wear simulators to investigate their effects on polyethylene wear. Biochemical analyses included measuring total polypeptide degradation, electrophoretic profiles and low-molecular weight polypeptide concentrations to elucidate their involvement in the wear process. The effects of the various calf sera constituent fractions on microbial growth were also explored. The polyethylene wear rates and the results from the biochemical analyses for the three calf serum lubricants were all found to be statistically significantly different from each other. The lubricant derived from the alpha-calf serum was closest in constituent fractions to human synovial fluid. It also showed the lowest polyethylene wear rate (14.38 +/- 0.85 mm3/million cycles) and the lowest amount of polypeptide degradation (7.77 +/- 3.87%). Furthermore, the alpha-calf serum lubricant was associated with the least amount of change in the electrophoretic profile, the least change in low-molecular weight polypeptide concentration, and the lowest microbial growth in the presence of sodium azide (a microbial inhibitor conventionally used in implant wear testing). Replacing sodium azide with a broad spectrum antibiotic-antimycotic eradicated the microbial growth. Some speculation was entertained regarding the effect of alpha-calf serum on colloid-mediated boundary lubrication. Based on the results, it was recommended that ISO 14243-3 be modified to include guidelines on calf serum constituent fractions that would favour using alpha-calf serum in order to improve the fidelity of the simulation in knee implant wear testing.

What works best, a cemented or cementless primary total hip arthroplasty?: minimum 17-year followup of a randomized controlled trial.

BACKGROUND: Total hip arthroplasty (THA) has been associated with high survival rates, but debate remains concerning the best fixation mode of THA. QUESTIONS/PURPOSES: We conducted a randomized controlled trial (RCT) with 250 patients with a mean age of 64 years between October 1987 and January 1992 to compare the results of cementless and cemented fixation. PATIENTS AND METHODS: Patients were evaluated for revision of either of the components. One hundred twenty-seven patients had died (51%) and 12 (4.8%) were lost to followup. The minimum 17-year followup data (mean, 20 years; range, 17-21 years) for 52 patients of the cementless group and 41 patients of the cemented group were available for evaluation. RESULTS: Kaplan-Meier survivorship analysis at 20 years revealed lower survival rates of cemented compared with cementless THA. The cementless tapered stem was associated with a survivorship of 99%. Age younger than 65 years and male gender were predictors of revision surgery. CONCLUSIONS: The efficacy of future RCTs can be enhanced by randomizing patients in specific patient cohorts stratified to age and gender in multicenter RCTs. Including only younger patients might improve the efficacy of a future RCT with smaller sample sizes being required. A minimum 10-year followup should be anticipated, but this can be expected to be longer if the difference in level of quality between the compared implants is smaller. LEVEL OF EVIDENCE: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Midterm results of 506 solid trispiked reflection cementless acetabular components for primary total hip arthroplasty.

The purpose of this prospective study was to evaluate the outcomes and survivorship of a trispiked, sintered bead-coated titanium shell with a polished inner surface, no screw holes, and an improved locking mechanism. A total of 506 total hip arthroplasties with a minimum 5-year follow-up were available for review at a mean of 7 years (range, 5-11 years). Three sockets (0.6%) were revised for reasons other than aseptic loosening, and 14 (2.8%) polyethylene liners were exchanged. There was no difference in revision rate between non-cross-linked and highly cross-linked liners (P = .4). There were no cases of radiographic loosening. Retroacetabular osteolysis was identified in 2%. The overall 5-year and 10-year Kaplan-Meier survivorship was 97.5% and 97.4%, respectively, whereas survivorship of the shell was 99.8%.

Comparing patient outcomes after THA and TKA: is there a difference?

UNLABELLED: Both primary total hip (THA) and knee (TKA) arthroplasty relieve pain, restore function, and increase mobility. Despite these successes, there is controversy as to whether THA or TKA provides greater or similar improvement. We therefore compared primary THA and TKA patient results in terms of (1) willingness to have surgery again; (2) WOMAC change score; (3) whether expectations were met; and (4) satisfaction. Patients undergoing primary THA were more willing to undergo their surgery again (THA 96%, TKA 89%), demonstrated greater WOMAC change scores, more frequently reported their expectations were met (THA 78%, TKA 70%), and expressed greater overall satisfaction (THA 89%, TKA 81%). In addition, patients undergoing THA expressed higher satisfaction with pain reduction while performing activities (ie, walking, stairs, and sitting/lying) and their ability to perform daily activities (ie, stairs, transportation, getting up, lying in bed, and light domestic duties) when compared with patients undergoing TKA. Our data suggest primary THA offers superior short-term outcomes when compared with primary TKA. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

The role of polyethylene design on postoperative TKA flexion: an analysis of 1534 cases.

UNLABELLED: The range of motion after TKA depends on many patient, surgical technique, and implant factors. Recently, high-flexion designs have been introduced as a means of ensuring or gaining flexion after TKA. We therefore evaluated factors affecting postoperative flexion to determine whether implant design influences longterm flexion. We prospectively collected data on patients receiving a primary Genesis II total knee replacement with a minimum of 1-year followup (mean, 5.4 years; range, 1-13 years). We recorded pre- and postoperative outcome measures, patient demographics, and implant design (cruciate retaining [CR, n = 160], posterior stabilized [PS, n = 1177], high-flex posterior stabilized [HF-PS, n = 197]). Backward stepwise linear regression modeling identified the following factors affecting postoperative flexion: preoperative flexion, gender, body mass index, and implant design. Independent of gender, body mass index, and preoperative flexion, patients who received a HF-PS and PS design implant had a mean of 8 degrees and 5 degrees more flexion, respectively, than those who received a CR implant. Patients with low flexion preoperatively (<100 degrees) were more likely to gain flexion, whereas those with high flexion preoperatively (>120 degrees) were most likely to maintain or lose flexion postoperatively. Controlling for implant design, patients with high flexion preoperatively (>120 degrees) were more likely to gain flexion with the HF-PS design implant (HF-PS = 32.0%; PS = 15.1%; CR = 4.5%). LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Patient satisfaction after total knee arthroplasty: who is satisfied and who is not?

UNLABELLED: Despite substantial advances in primary TKA, numerous studies using historic TKA implants suggest only 82% to 89% of primary TKA patients are satisfied. We reexamined this issue to determine if contemporary TKA implants might be associated with improved patient satisfaction. We performed a cross-sectional study of patient satisfaction after 1703 primary TKAs performed in the province of Ontario. Our data confirmed that approximately one in five (19%) primary TKA patients were not satisfied with the outcome. Satisfaction with pain relief varied from 72-86% and with function from 70-84% for specific activities of daily living. The strongest predictors of patient dissatisfaction after primary TKA were expectations not met (10.7x greater risk), a low 1-year WOMAC (2.5x greater risk), preoperative pain at rest (2.4x greater risk) and a postoperative complication requiring hospital readmission (1.9x greater risk). LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Three-dimensional surface deviation maps for analysis of retrieved polyethylene acetabular liners using micro-computed tomography.

Micro-computed tomography (micro-CT) has previously been validated for measuring wear volume in polyethylene acetabular liners. The creation of 3-dimensional (3D) articular and backside surface deviation maps using micro-CT is described. An acetabular liner was retrieved after 16.7 years of implantation and scanned with micro-CT along with a new, never-implanted liner of the same size and type. The liner surface geometries were reconstructed and co-aligned. A 3D comparison and cross-sectional analysis was performed. Maximum 3D deviation of the articular surface was -2.48 +/- 0.02 mm, with maximum backside deviation of 0.46 +/- 0.02 mm. Micro-CT can measure surface deviation and therefore calculate the volume of wear plus creep of retrieved acetabular liners, and may be applicable for wear simulator studies and analyzing other polyethylene components including tibial inserts.

Comparison of steady state femoral head penetration rates between two highly cross-linked polyethylenes in total hip arthroplasty.

Given that the manufacture of highly cross-linked polyethylene (HXLPE) is not standardized, the behavior of these materials may vary. Our study compares minimum 5-year steady state femoral head penetration rates using the Martell method, in 2 HXPLEs produced by different manufacturers. Patients received a primary hip arthroplasty using an uncemented acetabular component with an HXLPE liner and a 28-mm femoral head. Forty-seven patients in group A received an HXLPE liner (Reflection XLPE, Smith and Nephew Inc, Memphis, Tenn), and 36 patients in group B received a different HXLPE liner (Longevity, Zimmer Inc, Warsaw, Ind). Average follow-up was 6.42 years in group A and 7.64 years in group B. The steady state head penetration rates were not significantly (P > .05) different between the HXPLE groups over the midterm with 0.026 mm/y and 0.025 mm/y in groups A and B, respectively.

The John Insall Award: gender-specific total knee replacement: prospectively collected clinical outcomes.

UNLABELLED: Gender-specific total knee replacement design is a recent and debated topic. We determined the survivorship and clinical outcomes of a large primary total knee arthroplasty cohort, specifically assessing any differences between gender groups. A consecutive cohort of 3817 patients with 5279 primary total knee replacements (3100 female, 2179 male) with a minimum of 2 years followup were evaluated. Preoperative, latest, and change in clinical outcome scores (WOMAC, SF-12, KSCRS) were compared. While men had higher raw scores preoperatively, women had greater improvement in all WOMAC domains including pain (29.87 versus 27.3), joint stiffness (26.78 versus 24.26), function (27.21 versus 23.09), and total scores (28.35 versus 25.09). There were no gender differences in improvements of the SF-12 physical scores. Men had greater improvement in Knee Society function (22.1 versus 18.63) and total scores (70.01 versus 65.42), but not the Knee Society knee score (47.83 versus 46.64). Revision rates were 10.2% for men and 8% for women. Women demonstrated greater implant survivorship, greater improvement in WOMAC scores, equal improvements in SF-12 scores, and less improvement in only the Knee Society function and total scores. The data refute the hypothesis of inferior clinical outcome for women following total knee arthroplasty when using standard components. LEVEL OF EVIDENCE: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Twenty-three-year outcome of the porous coated anatomic total hip replacement: a concise follow-up of a previous report.

We previously reported the ten to fourteen-year results for 311 Porous Coated Anatomic total hip replacements that had been inserted by two surgeons in 279 patients. The purpose of the present report is to update that study and to report the outcome beyond twenty years. The patients were followed prospectively with clinical assessment with use of the Harris hip score and radiographic analysis, and the results were collected in a database. Two hundred and sixty-eight hips were functioning at the time of death or at the time of the latest follow-up. A total of forty-three hips (14%) underwent major revision for all causes, and an additional four hips underwent minor revision. At a mean of twenty-three years of follow-up, Kaplan-Meier analysis revealed a survival rate of 83% with revision for any reason as the end point. The survival rate was 95% for the femoral component and 88% for the acetabular component with revision for any reason as the end point. The rate of survival of the acetabular component was significantly higher in hips with a 26-mm femoral head than in those with a 32-mm femoral head (91% compared with 80%; p = 0.026).

Comparison of total hip arthroplasty performed with and without cement: a randomized trial. A concise follow-up, at twenty years, of previous reports.

Total hip arthroplasty has been associated with excellent implant survival rates, but debate remains concerning the best fixation method for the components. A randomized controlled trial, which included 250 patients (mean age, sixty-four years) with osteoarthritis who were managed with total hip arthroplasty between October 1987 and January 1992, was conducted to compare the results of fixation with and without cement. Patients were followed for a mean of twenty years (range, seventeen to twenty-one years). Kaplan-Meier survivorship analysis at twenty years revealed significantly lower survival rates for cemented implants as compared with cementless implants. The cementless tapered stem had an extremely good survival rate of 99%. Radiographs showed evidence of mild stress-shielding around 95% of the cemented stems and 88% of the cementless stems; stress-shielding of grade 3 or greater was seen around the remaining 12% of the cementless stems.

Highly cross-linked polyethylene acetabular liners retrieved four to five years after revision surgery: a report of two cases.

There is currently considerable interest in the use of highly cross-linked polyethylene (XLPE) acetabular liners for total hip arthroplasty (THA). In literature, only a single retrieval analysis of one type of XLPE liner implanted for greater than four years exists. The purpose of the present report is to quantify surface deviations in two XLPE liners implanted during revision THA and retrieved between four to five years after implantation. The two XLPE acetabular liners (Reflection, Smith and Nephew Inc., Memphis, TN) were retrieved from patients undergoing their second revision surgery, at 4.90 and 4.07 years. The retrieved liners and a new, non-implanted, unworn liner of the same size were scanned using micro-computed tomography (micro-CT). Articular surface deviation maps were created by comparing the retrievals to the unworn liner, based on the liner geometry obtained from micro-CT. The linear penetration rates were found to be 0.018 and 0.008 mm/year. Localized scratches and pits with deviations greater than 0.205 mm were also found on the articular surfaces of both liners. The XLPE liners retrieved from the two cases demonstrated low linear penetration rates. Regions with greater focal deviations were also apparent, likely due to third-body wear. The results are consistent with previously published clinical follow-ups of other XLPE liners.

Wear rate of highly cross-linked polyethylene in total hip arthroplasty. A randomized controlled trial.

BACKGROUND: Highly cross-linked polyethylene was introduced for clinical use in total hip arthroplasty with the expectation that it would exhibit less wear when compared with conventional polyethylene. The purpose of this study was to report the clinical and radiographic results, after a minimum of five years of follow-up, of a randomized, blinded, controlled trial comparing a conventional polyethylene with a first-generation highly cross-linked polyethylene. METHODS: One hundred patients were enrolled in a prospective, randomized controlled study comparing highly cross-linked and conventional polyethylene acetabular liners in total hip arthroplasty. Fifty patients were in each group. At the time of follow-up, clinical outcomes were assessed and steady-state femoral head penetration rates (after bedding-in) for each patient were calculated with use of a validated radiographic technique. In addition, a statistical comparison of polyethylene wear between groups was performed with use of generalized estimating equations. RESULTS: At a mean of 6.8 years postoperatively, there were no differences between the two polyethylene groups with regard to the Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), or Short Form-12 (SF-12) score. The mean femoral head penetration rate in the first through fifth years was found to be significantly lower in the group treated with the highly cross-linked polyethylene (0.003 mm/yr [95% confidence interval, +/-0.027]) than it was in the group treated with conventional polyethylene (0.051 mm/yr [95% confidence interval, +/-0.022]) (p=0.006). Men treated with a conventional polyethylene liner had a significantly higher (p

The next generation of acetabular shell design and bearing surfaces.

The R3 Acetabular component represents the next generation of acetabular shell with an enhanced porous ingrowth surface (StikTite, Smith & Nephew, Memphis, Tenn) to meet the needs of both primary and revision hip arthroplasty; an optimized locking mechanism; and the ability to accomodate polyethylene, metal, or ceramic liners. This prospective clinical study reports on the safety and efficacy of the new StikTite porous ingrowth surface using radiostereometric analysis (RSA). StikTite provides a superior "sctratch-fit" due to its greater coefficient of friction and less micromotion using RSA measurements.