Prior high tibial osteotomy is not a contraindication for medial unicompartmental knee arthroplasty.

PURPOSE: To report on the outcome and complications of minimal invasive medial unicondylar knee arthroplasty (UKA) after failed prior high tibial osteotomy (HTO) as treatment for medial osteoarthritis in the knee. The hypothesis was that good results can be achieved, if no excessive postoperative valgus alignment and abnormal proximal tibial geometry is present. METHODS: All medial UKAs after failed prior HTO (n = 30), performed between 2010 and 2018 were retrospectively reviewed. The patients were followed for revision surgery and survival of the UKA (defined as revision to TKA). Clinical examination using the Knee Society Score (KSS), Oxford Knee Score (OKS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), as well as radiological examination was performed. Radiographs were studied and the influence of the demographic factors and the radiographic measurements on the survival and the clinical outcome was analysed. RESULTS: After a follow-up of 4.3 ± 2.6 years (2.1-9.9) 27 UKAs were available. The survival rate was 93.0%. Two UKAs were revised to TKA (excessive valgus alignment and tibial loosening with femoropatellar degeneration). Two further patients had revision surgery (hematoma and lateral meniscus tear). Follow-up clinical and radiological examination was performed in 21 cases: KSS 82.9 ± 10.1 (54.0-100.0), KSS (function) 93.3 ± 9.7 (70.0-100.0); OKS 42.7 ± 6.0 (25.0-48.0); WOMAC 7.9 ± 15.6 (0.0-67.1). No significant influence of demographic factors or radiological measurements on the clinical outcome was present. CONCLUSION: Prior HTO is not a contraindication for medial UKA, because good-to-excellent results can be achieved in selected patients with medial osteoarthritis and previous HTO, treated with medial UKA, in a midterm follow-up. Excessive mechanical valgus axis should be avoided; therefore, patient selection and accurate evaluation of medial laxity, preoperative mechanical axis, joint line convergence and proximal tibial geometry are important. LEVEL OF EVIDENCE: III.

Fixation of a modular curved revision stem with a taper of 2° in the femur.

INTRODUCTION: Modular revision stems with a short distal component can prevent the bypassing of the femoral isthmus and hereby theoretically have advantages concerning risk of periprosthetic fractures, breakage of the junction and a technically easier revision procedure. MATERIALS AND METHODS: Radiological evaluation of 202 stem revision operations with the modular curved revision stem "Revitan Curved" with a 2° taper was carried out after a mean follow-up period of 7.44 ± 2.09 years (3-13 years) to investigate whether short-stem combinations are effective in Paprosky 2 and 3A defects with respect to rate of subsidence and loosening. RESULTS: Sixty of 62 endofemoral (96.8%) and 137 of 140 transfemoral implantations (97.9%) involved the short, 140 mm distal component. Significant subsidence was seen in 3.3% of cases following endofemoral implantation and in 2.1% of cases following transfemoral implantation. Neither aseptic loosening nor periprosthetic fracture were observed. CONCLUSION: The use of combinations of short modular components leads to reproducibly good outcomes in femoral revision with respect to subsidence and loosening.