Among the frequent causes of hind leg limping in dogs, a Cranial Cruciate Ligament (CCL) injury stands out. Comparable to the ACL in humans, the CCL is a crucial ligament in a dog’s knee. Its primary function is to prevent the shin bone (tibia) from sliding forward concerning the thigh bone (femur). When the CCL is partially or completely torn, it leads to an unstable and painful knee, which manifests as a limp.
In some cases, dogs experience a complete CCL tear, resulting in an abrupt cessation of weight-bearing on the injured leg. However, a more common scenario involves sporadic limping. Over the course of weeks, months, or even years, dogs might exhibit on-and-off limping. Initially, rest and pain relief measures might alleviate the limping, but eventually, the situation worsens. This progression often occurs when a partial CCL tear transforms into a full tear or when dogs with a CCL tear also damage their medial meniscus, a knee shock absorber. Around 50-60% of dogs with full CCL tears and 5-7% with partial tears end up injuring their meniscus.
Diagnosing a CCL tear hinges on identifying “cranial drawer” instability during an orthopedic examination. While most dogs can undergo this examination while awake, some may require sedation due to pain, tension, or anxiety.
Multiple approaches exist for treating CCL tears in dogs. One widely employed technique is the Tibial Plateau Leveling Osteotomy (TPLO). The objective of TPLO is to modify the forces within the knee, creating stability even without a functional CCL. This involves making a curved cut in the shin bone, repositioning the cut bone segment, and securing it with a bone plate and screws. This adjustment provides a more stable platform for the thigh bone, enlisting other muscles and ligaments to aid in knee stability.
Having personally performed and assisted in over 1,000 TPLOs, I hold the procedure in high regard for its reliability and success. With an experienced surgeon at the helm, TPLO can offer dogs a favorable chance of complete recovery with minimal complications. Nonetheless, as with any endeavor, TPLO has its limitations, and individual factors can impact its effectiveness.
Precise preparation for TPLO mandates accurately positioned x-rays of the knee and shin bone, allowing measurements and surgical planning. This information guides the choice of tools, bone cut placement, and joint surface rotation. Tailoring the approach to factors like your dog’s shin bone shape, meniscus condition, or additional problems such as a dislocated kneecap may be necessary. In certain situations, an alternative procedure could be recommended.
If your dog is dealing with a continuous or worsening limp, we encourage you to reach out to Sunstone Veterinary Specialists for an estimate of the costs involved.
Lillian Su, DVM, MVSc, CCRP, Diplomate ACVS-SA
Certified Specialist in Small Animal Surger