Knee salvage in revision arthroplasty after massive bone loss of the femur condyles (≥Engh III) with a single-modular-hinged knee revision implant

PURPOSE

Massive bone loss of the femur condyles in revision arthroplasty often requires modular-hinged revision implants to restore a stable joint situation. In the present series, the outcome after knee revision surgery using a single modular-hinged revision implant in patients with severe bone defects (>Engh III) is investigated.

METHODS

Sixty patients with severe bone defects (≥Engh III) after failed primary and revision knee arthroplasty were included. Medium follow-up was 47 (range 10-84) months after knee revision surgery. Medium patient age was 70 (range 33-87) years at the time of surgery. An average of 2.3 prior knee operations per patient was performed. 70 % of the patients required the knee revision implant after two-stage revision because of a deep implant infection.

RESULTS

Estimated 5 year extremity survival was 95 and 65 % implant survival. Reasons for implant revision in decreasing order were reinfection (30 %), aseptic loosening (13 %), and periprosthetic fracture (9.8 %). The average active range of motion in the knee joint was 88° (range 40°-115°) for flexion. An extension deficit of a mean of -6° was (range -50-5° hyper-extension) observed. Patient age influenced the functional results significantly in terms of reduced walking distances and decreased modified WOMAC score.

CONCLUSION

In consideration of this complex study, population acceptable functional results can be achieved using a modular knee revision endoprosthesis. In younger patients (<60 years), satisfying results in terms of walking ability and overall satisfactory can be expected. The outcome in older multimorbid patients is worse. Yet, operation in these patients can be feasible to restore enough mobility for daily household activities.