Bilaterally altered hindlimb muscle function as assessed by acoustic myography in dogs with unilateral cranial cruciate ligament disease

Cranial cruciate ligament disease (CCLD) is a leading cause of lameness and joint instability in dogs. Clinical signs may be the result of a combination of ligament deficiency and altered muscle function. The objective of this study was to evaluate hindlimb muscle function in dogs with CCLD using acoustic myography (AMG) - a non-invasive method to assess muscle activity, pressure sensitive walkway (PSW), and limb circumference. Dogs with unilateral CCLD underwent AMG recordings of four hindlimb muscles related to the stifle: vastus lateralis, cranial part of biceps femoris, semitendinosus, and cranial sartorius. Gait patterns were assessed using PSW data. Measurements were obtained pre-operatively and compared with existing data from healthy dogs. Twenty-one CCLD dogs were included in the study. The AMG recordings revealed significantly lower E -scores in both the affected and unaffected hindlimb compared with healthy dogs, suggesting less efficient muscle work in CCLD dogs. Further, S- and T-scores were significantly lower in the unaffected cranial sartorius muscle compared with healthy dogs, and T-scores were significantly lower in the unaffected limb compared with the affected hindlimb, reflecting some degree of increased muscular effort in the unaffected hindlimb. Limb circumference and gait patterns were asymmetric; reflecting unilateral lameness. The AMG findings suggest bilaterally altered muscle function in dogs with unilateral lameness due to CCLD.