Rotating hinge knee versus constrained condylar knee revision: a single centre, retrospective comparative study

Introduction
In revision total knee arthroplasty, rotating hinge implants (RHK) have been presumed to result in higher complication rates and lower survivorship when compared to constrained condylar implants (CCK). This study aimed to compare patient-reported outcome measures (PROMs), complication rates and survivorship of RHK and CCK used in revision arthroplasty at a single, high-volume elective orthopaedic centre with a previously validated bespoke database.

Methods
Patients (n=108) who underwent revision knee arthroplasty with either CCK or RHK and matched our inclusion criteria were identified. EuroQol Five Dimensions (EQ5D), EuroQol Five Dimensions (EQ5D)-Health State and Oxford Knee Scores were collected pre-operatively and at one year post-operatively. Complication data was collected at six weeks, six months and one year post-operatively. National Joint Registry (NJR) data were interrogated, in addition to our orthopaedic database, to investigate implant survival with a maximum follow-up of 12 years.

Results
There was no statistical significant difference between RHK and CCK in implant survival at two to 12 years of follow up. In addition, we observed no statistical significant difference in the PROMs scores and complication rates of the two implants.

Conclusion
This study shows that both the RHK and CCK remain viable options in revision arthroplasty; the implant survival and complication rates were comparable. We recommend future research through prospective randomised control trials with long-term follow up to further investigate the use of CCK and RHK implants in revision knee arthroplasty.