Long-term clinical outcomes and retrieval analysis of a cementless total knee replacement in a dog.

Objective: The aim of the study was to describe long-term outcomes and report post-retrieval implant analysis following cementless total knee replacement (TKR) in a dog.

Animal: A seven-year-old, male neutered, Labrador retriever.

Methods: The dog presented for evaluation of chronic left pelvic limb lameness. Orthopedic examination identified bilateral cranial drawer and medial buttress. Radiographs revealed severe bilateral osteoarthritis with moderate joint effusion/synovial hypertrophy. Given the end-stage osteoarthritis, TKR was considered more appropriate than tibial plateau leveling osteotomy (TPLO). The dog underwent a left cementless TKR.

Results: Immediate postoperative radiographs showed appropriate implant positioning. Moderate left pelvic limb lameness with full, pain free and stable stifle range of motion (ROM) was documented at 2 weeks. Increased left hindlimb weight-bearing with a peak vertical force of 70% bodyweight (BW) versus 50% BW on the contralateral leg was reported at 6 weeks. Radiographs showed good implant osseointegration. Left stifle ROM was 50°/170°, a 30° increase compared to preoperative values. Additional rechecks at 14 and 30 weeks showed gradual improvement in stifle ROM and weight-bearing. The dog was euthanized 6 years after surgery for reasons unrelated to TKR. Radiographs demonstrated static implant position without signs of osteolysis and gross examination revealed mild polyethylene wear on the caudal aspects of the tibial insert. Histological evaluation of the implant-bone interface showed extensive and robust osseointegration.

Conclusion: This case demonstrates that cementless TKR can be associated with excellent clinical function over the course of at least 6 years and suggests that early surgical intervention could be considered.