One health: translating latest ACL research to dogs

Post-operative prevention of the loss in quadriceps muscle strength is the priority. Interestingly, the loss of quadriceps muscle strength seen may be attenuated by strength training of the contralateral limb! (Minshall et al. 2021). This has been theorised to be through activation of the corticomotor pathway. Using maximal strength training this provides maximal stimulation of the corticomotor pathway which also links to the contralateral limb. Therefore, keeping the dog off the underwater treadmill and giving it high resistance strengthening exercises, to be done with both hindlimbs, at home in the first 10 weeks post-operatively may be the way to go to gain maximum outcomes.

Quadriceps strength is also an important measure in determining gait asymmetries . Persistent asymmetries in quadriceps strength commonly exists and may be a predisposing to early onset osteoarthritis (Minshull et al. 2021). In humans, quadriceps strength has been assessed using isometric strength whereas in dogs we commonly use thigh circumference. However, how does thigh circumference translate to strength? Thigh circumference is not quadriceps specific. If it were, would it matter? It seems that it may not. In a study by Arhos et al. (2021) found that after a threshold level of quadriceps strength was obtained despite additional strength gains gait asymmetries may still be exist.

So, if the threshold of quadriceps strength has been achieved how else can these be addressed and are these reasoning for the high rates of contralateral CCL rupture? Movement is a collaboration of neuromuscular, biomechanical, sensorimotor and neurocognitive factors and therefore, through physiotherapy, each of these may be encompassed into task-specific activities to enhance motor learning and generate new functional movement patterns. If these were to be included into every dog's CCL rehabilitation would contralateral CCL injury rates decrease? A question yet to be answered but theorectically it makes sense.