Salvage revision total knee replacement using the Endo-Model® rotating hinge prosthesis

Inability to balance a knee in complex revision total knee replacement has led to the use of rotating hinged knee devices in these cases as a salvage procedure.

We conducted a retrospective study of 50 patients receiving 51 Endo-Model® rotating hinge prosthesis with an average follow-up of 4 years (range 2–6 years). Clinical and radiological results were reviewed at latest follow-up. Five patients died from unrelated causes. Reasons for revision were infection (23), aseptic loosening (23), implant failure (3), stiffness (1) and peri-prosthetic fracture (1). The average number of previous surgery from and including the primary arthroplasty was three (ranges 1–14). Seven patients required plastic surgery for soft tissue cover.

There was notable improvement in the pain, stability, range of motion and mobility of the patients with an improvement in the Hospital for Special Surgery Score (35.9 to 72.17). Postoperatively, 11 (22%) had an excellent HSS grade, 22 (44%) good grade, 10 (19%) fair grade and 8 (15%) poor grade. A significant number of our patients had an extremely low preoperative HSS score, and for these patients, an improvement to a fair grade HSS score was a satisfactory and realistic outcome. Forty-four (86%) patients were satisfied with the outcome of the revision surgery, 3 (6%) noncommittal and 4 (8%) disappointed. Comparing revision for infection vs. aseptic loosening, 22 (95%) patients out of 23 were satisfied in the aseptic loosening group vs. 17 (74%) out of 23 were satisfied in the infected group.

In selected complex cases, salvage revision surgery shows encouraging results in the short to medium term using the Endo-Model® rotating hinge prosthesis. A knee score such as the Hospital for Special Surgery score (objective outcome) should be used in conjunction with a patient satisfaction questionnaire (subjective outcome) in assessing the clinical outcome of complex, salvage revision knee surgery. Revision for infected total knee replacement is less likely to produce a satisfactory outcome as compared to revision for aseptic loosening.