Moet, is a three year old Bull Arab, with lameness in her right hind leg for over a year. Initial presentation for hip dysplasia with definitive diagnosis at NCVS of right partial functional cruciate tear (always check the stifle). Exam moderate quads atrophy (quads for stifle, gluteals for hip), stifle joint effusion and mild medial buttress. Stifle stable in tibial thrust and drawer. Moderate stifle pain.
Radiographs revealed moderate stifle effusion and periarticular osteophyte formation. Diagnosis of partial cruciate disease. Tibial plateau not excessively steep at 27 degrees. Stifle arthroscopy (as recommended in all our cruciate dogs due to superior visualisation, minimal tissue trauma and rapid recovery) revealed a largely intact ACL with tearing of the caudolateral band only. The remaining ligament was taut and functioning to limit tibial subluxation. A TPLO was performed through a mini-medial incision just enough to allow the saw blade and plate to be inserted. Uneventful recovery, weightbearing and discharged the following day. Advised owners excellent prognosis with greater than 90%of dogs will return to function 3-6 months.
Partial ACL tearing is common and is, I believe, the precursor to complete ACL rupture. Confusion still exists that a stable stifle cannot be cruciate but this is incorrect. Effusion and osteophyte formation with either a stable or unstable knee is cruciate disease until proven otherwise (patella luxation will not have effusion unless full thickness chondromalacia or concurrent ACL disease). Early identification of functional partial ACL is important as early TPLO will largely minimise progression of ligament degeneration with maintenance of a stable knee. Second look arthroscopic studies confirm preservation of articular cartilage, non-progressive ligament degeneration and elimination of risk for meniscal injury. These findings are in direct contrast to the unstable knee with complete rupture. I always recommend contralateral stifle x-rays at the time of initial surgery as at least 50% will have concurrent disease.