The Endo-Model(®) rotating hinge for rheumatoid knees : Functional results in primary and revision surgery

Major joints of the lower limbs are commonly affected by rheumatoid arthritis (RA), with consequent pain, loss of function, and progressive disability. Knee replacement represents a useful solution, but a highly constrained implant design is often needed in order to face the severe anatomical deformities and the gross instability that the surgeon may encounter in the rheumatoid knee.

The aim of this work was to evaluate the Endo-Model(®) rotating hinge knee prosthesis implanted in patients affected by RA and severely damaged knees.

We retrospectively evaluated a series of 38 patients with RA implanted with the Endo-Model(®) rotating hinge knee prosthesis for primary or revision surgery (mean follow-up 6.1 years; mean age at surgery 71.5 years). At the time of surgery, the mean duration of RA was 13.2 years. Patients were evaluated clinically and radiographically and the Knee Society Score (KSS) was used.

Implant survival at most recent follow-up was 91.7 %. Mean final knee flexion was 102.7 °. The mean KSS was 93.5 (excellent) and 67.1 (good) for clinical and functional score, respectively. Mild pain was present in 10 patients. No sign of malalignment or residual instability was found. No evidence of loosening or implant failure was observed in x-rays.

The Endo-Model(®) rotating hinge knee prosthesis provides excellent pain relief, functional recovery, and intrinsic knee stability both in complex primary and in revision knee arthroplasty in the majority of patients with severely affected rheumatoid knees.