Indications, clinical outcome and survival of rotating hinge total knee arthroplasty in a retrospective study of 63 primary and revision cases

Purpose The purpose of this study is to report and compare outcome data of both primary and revision cases using a rotating hinge knee (RHK) implant. Methods This study retrospectively analyzed 63 cases (19 primary, 44 revisions) at a mean follow-up of 34 +/- 8 months after RHK implantation. Outcome parameters were stability, range of motion (ROM), loosening, Hospital of Special Surgery Score (HSS), Knee Society Score (KSS), Oxford Knee Score (OKS), EQ-5D-3L, and Visual Analog Scale (VAS) for overall function. Revision rates and implant survival are reported. Results Eleven percent showed medio-lateral instability < 5 mm, a mean ROM of 115 degrees +/- 17 degrees and radiologic loosening occurred in 8% (2% symptomatic). PROMS showed the following results: HSS 79 +/- 18, KSS 78 +/- 27, OKS 26 +/- 10, EQ-5D index 0.741 +/- 0.233 and VAS 70 +/- 20. Primary cases revealed better outcomes in HHS (p = .035) and OKS (p = 0.047). KSS, EQ-5D index and VAS did not differ between primary and revision cases (p = 0.070; p = 0.377; p = 0.117). Revision rate was 6.3% with an implant survival of 96.8%. Conclusions RHK arthroplasty can be performed with good clinical outcome and low revision rate in revision and complex primary cases. RHK is an option in cases where standard arthroplasty and even implants with a higher degree of constraint have reached their limits.