Fracture of Two Moderately Cross-Linked Polyethylene Tibial Inserts in a TKR Patient

Highly cross-linked polyethylene has become the gold standard in total hip replacement for its wear resistance. Moderately crosslinked polyethylene is now available for total knee replacement (TKR), although concerns about reduced mechanical strength have prevented widespread adoption. The purpose of this report is to describe an unusual case where a patient underwent cruciate retaining TKR using a moderately crosslinked polyethylene tibial insert that went on to fracture twice in the same location across the primary and first revision surgery. The first tibial insert was 10 mm thick and was implanted for 16 months. The second tibial insert was 15 mm thick and was implanted for 11 months. Both fractured along the posterior aspect of the medial articular surface. The lack of a specific event leading to these fractures and the fact that they occurred twice in the same location in the same patient suggest that caution is still necessary regarding the introduction of crosslinked polyethylene for TKR surgery

Modified complete synovectomy prevents recurrence in synovial chondromatosis of the hip

Synovial chondromatosis of the hip is a rare disorder with few published reports regarding treatment and outcomes, and therefore, selecting the optimal surgical treatment is difficult. We reviewed eight patients with monoarticular synovial chondromatosis of the hip who had joint débridement and a modified total synovectomy performed through a surgical hip dislocation with a trochanteric flip osteotomy. Patients were evaluated for recurrence of disease, progression of osteoarthritis, clinical outcomes, and subsequent reoperations. The minimum followup was 4 years (mean, 6.5 years). At final review, no patient had recurrence of disease. Two patients had progression of osteoarthritis requiring total hip arthroplasties at 5 and 10 years after the initial surgical intervention. These patients did not show recurrent disease on histologic examination of the synovial membrane at the time of the arthroplasty. The six patients with preserved joints were followed up for a mean of 6.2 years. The mean Merle d'Aubigné and Postel score in this group was 16.5 points (range, 15-18 points) at the latest followup. There were no major or minor complications related to this treatment. Our midterm results suggest that open débridement with modified total synovectomy is an effective treatment that prevents recurrence of disease and provides substantial pain relief. Surgical hip dislocation allows safe and complete access to the joint for débridement and synovectomy with no added morbidity

The Role of Polyethylene Design on Postoperative TKA Flexion: An Analysis of 1534 Cases

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° and 5° more flexion, respectively, than those who received a CR implant. Patients with low flexion preoperatively (< 100°) were more likely to gain flexion, whereas those with high flexion preoperatively (> 120°) were most likely to maintain or lose flexion postoperatively. Controlling for implant design, patients with high flexion preoperatively (> 120°) were more likely to gain flexion with the HF-PS design implant (HF-PS = 32.0%; PS = 15.1%; CR = 4.5%)

Effect of Acetabular Component Positioning on Functional Outcomes in Primary Total Hip Arthroplasty

© 2016 Elsevier Inc. Background Acetabular component positioning is crucial to a successful total hip arthroplasty (THA). This study evaluated the effect of absolute acetabular component position as well as acetabular position relative to bony anatomy on patient-reported functional outcomes after primary THA. Methods Primary, press fit, hemispherical metal-on-polyethylene THA performed between 2003 and 2011 were analyzed. Western Ontario and McMaster Osteoarthritis Index (WOMAC), Harris Hip Score (HHS), Short Form-12 scores, and radiographs between 2 and 3 years after the index procedure were assessed. Results Of the 1241 primary THA included, the mean abduction and anteversion angles were 44.4 ± 6.94 and 21.7 ± 11.9 degrees, respectively. The mean anterior and lateral overhang were 1.9 ± 3.6 and 2.5 ± 3.4 mm, respectively. There was no correlation between functional outcomes and acetabular inclination. A weak positive correlation between anteversion and HHS (P \u3c .001) and WOMAC (P = .02) scores was found. For relative position, anterior overhang of the acetabular component beyond the bone resulted in inferior Short Form-12 physical function (P = .001), HHS (P = .004), and WOMAC (P \u3c .001) scores compared to those with bony coverage. Mean HHS pain score was 41.20 ± 5.69 in patients with lateral overhang and 41.97 ± 5.04 in those who had bony coverage of the lateral edge of the acetabular component (P = .02). Conclusion The tribology and biomechanics of acetabular component position have been extensively studied without examination of how it affects patient function. Although statistical significance was seen, clinical outcome scores were not sensitive enough to show a clinically significant effect of the absolute or relative position of the acetabular component

The John Insall Award: Gender-specific Total Knee Replacement: Prospectively Collected Clinical Outcomes

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