BACKGROUND: Patella tendinopathy is an overuse condition. Pathogenesis and identification of intrinsic risk factors have largely eluded the orthopaedic world. The cranial cruciate ligament (CrCL) in dogs is the equivalent to the human anterior cruciate ligament (ACL). We report the effect of two canine proximal tibial osteotomy procedures in the veterinary literature on patella tendon moment arm and describe the biomechanical rationale for a tibial tubercle osteotomy for treatment of patella tendinopathy in the human.
METHODS: A literature review of studies reporting clinical complications of TTA and TPLO to form an observational animal cohort study in dogs.
RESULTS: The veterinary literature reports an overall clinical complication rate of up to 61% for TTA and up to 50% for TPLO respectively. Complications associated with the extensor mechanism of the knee are <1% for TTA compared to 1.9-19% for TPLO. Radiographic thickening of the patella tendon and tendinopathy is seen in one to 80% of TPLO cases. The TPLO decreases the moment arm of the extensor mechanism meaning increased force is required in the patella tendon to achieve the same torque when compared to the TTA which increases the efficiency of the extensor mechanism. This difference may account, in part, for the post-operative complications reported to the patella and patella tendon following TPLO.
CONCLUSION: This observational animal cohort study demonstrates a biomechanical rationale for investigating diagnostic and potential treatment options, including a tibial tubercle osteotomy, for patella tendinopathy in humans based on this principle.