Early migration in unicompartmental knee arthroplasty: a radiostereometric study of 26 patients with 24 months of follow-up.

BACKGROUND AND PURPOSE: Aseptic loosening, mainly caused by migration, is one of the most common indications for revisions in unicompartmental knee arthroplasty (UKA). In this study, we investigated the early migration of the Persona Partial Knee (PPK, Zimmer Biomet, Warsaw, IN), a cemented medial fixed-bearing unicompartmental knee prosthesis, and evaluated the clinical results. PATIENTS AND METHODS: 26 primary PPKs were implanted. Radiographs were obtained direct postoperatively, at 6 weeks, 6, 12 and 24 months postoperatively. Migration of the femoral and tibial component was calculated using model-based radiostereophotogrammetric analysis (mRSA) in terms of translations and rotations. Patient-reported outcome measures (PROMs) were also registered. RESULTS: At 24 months postoperatively, we found low migration of both the femoral and tibial component in the first 6 months, after which both components stabilized. Only the rotation of the tibial component about the z-axis did not stabilize. All PROMs improved after 24 months compared with preoperative PROMs. CONCLUSION: The Persona Partial Knee shows low migration of both the femoral and tibial component and PROMs were improved at 24 months follow-up. Long-term follow-up is needed to investigate the performance of the prosthesis compared with other prostheses.

More complications in uncemented compared to cemented hemiarthroplasty for displaced femoral neck fractures: a randomized controlled trial of 201 patients, with one year follow-up.

BACKGROUND: It is unclear whether cemented or uncemented hemiarthroplasty is the best treatment option in elderly patients with displaced femoral neck fractures. Previous randomized trials comparing cemented and uncemented hemiarthroplasty have conflicting results. We conducted a randomized controlled trial to compare cemented and uncemented hemiarthroplasty. METHODS: This multicenter parallel-randomized controlled trial included patients of 70 years and older with a displaced femoral neck fracture (Garden type III or IV). Inclusion was between August 2008 and June 2012. Patients were randomized between a cemented hemiarthroplasty, type Müller Straight Stem or an uncemented hemiarthroplasty, type DB-10. Primary outcomes were complications, operation time, functional outcome (measured by Timed-Up-and-Go (TUG) and Groningen Activity Restriction Scale (GARS)) and mid-thigh pain. Health Related Quality of Life (HRQoL, expressed with the SF-12) was measured as an secondary outcome. Follow up was 1 year. RESULTS: In total 201 patients were included in the study (91 uncemented, 110 cemented hemiarthroplasties) The uncemented group showed more major local complications (intra- and postoperative fractures and dislocations) odds ratio (95% confidence interval) 3.36 (1.40 to 8.11). There was no difference in mean operation time (57.3 vs 55.4 min). There were no differences in functional outcomes (TUG 12.8 (9.4) vs. 13.9 (9.0), GARS 43.2 (19.7) vs. 39.2 (16.5)) and mid-thigh pain (18.6 vs 21.6%). Physical component SF-12 HRQoLwas lower in the uncemented group (30.3 vs. 35.3 p < 0.05 after six weeks, 33.8 vs 38.5 p < 0.05 after 12 weeks). CONCLUSION: A cemented hemiarthroplasty in elderly patients with a displaced femoral neck fracture results in less complications compared to an uncemented hemiarthroplasty. TRIAL REGISTRATION: Netherlands Trial Registry; NTR 1508 , accepted date 27 okt 2008.