Patient-reported outcomes after primary rotating hinge total knee arthroplasty: a multi-centre clinical cohort study.

Purpose: Rotating hinge prostheses for total knee arthroplasty (TKA) are mostly used in revision setting; however, evidence on the use of these constrained devices in primary setting is scarce and inconsistent. Therefore, we aimed to evaluate the functional outcomes after third-generation rotating hinge implants in primary TKA with a minimal follow-up of two years in a large dual-centre observational retrospective clinical trial.

Methods: The hospital databases of two centres were searched for primary rotating hinge arthroplasty from January 2007 to January 2015. A minimum follow-up of at least two years was assured. Patients meeting the inclusion criteria were asked to fill out two self-reported functional scores, the Oxford Knee Score (OKS) and Forgotten Joint Score (FJS), to measure the functional status of the knee.

Results: In total, 267 primary rotating hinge knee arthroplasties in 242 patients were performed in two centres. The three major indications were axial malalignment (valgus/varus > 15°), 87/267 (33%), persistent ligamentous instability (28%) and neuromuscular disorders (12%). 184 patients with 202 primary rotating hinge knee arthroplasties could be included that provided data of the self-reported outcome measures (OKS and FJS). A mean OKS score of 37.71 (± 9.23) and a mean FJS score of 63.65 (± 31.01) could be obtained.

Conclusion: This large clinical study suggests that constrained devices provide the best results when treating bone-on-bone tricompartimental osteoarthritis of the knee with severe axial deviation (valgus/varus > 15°) and/or persistent ligamentous instability.