The cruciate ligament is crucial in maintaining the stability of the knee joint. When the anterior cruciate ligament of the knee sustains a partial or complete rupture, it results in lameness.
It remains the most common cause of posterior lameness in dogs. Most commonly, it is non-traumatic, and the rupture occurs as a result of abnormal stresses of the ligament. Over time there is degeneration and weakening of the ligament exacerbated by overweight and the carry of the hind limb. The ligament begins as a partial rupture due to continuous strain and progresses to complete rupture. There may not have any obvious trauma, and yet joint instability, meniscal damage, and early development of osteoarthritis render complete rupture of the ligament. Lameness may be subtle in the beginning. As the condition progresses, the dog becomes a bit stiff and shows a varying degree of lameness until a complete tear of the ligament and the dog becomes acutely lame.
Cruciate rupture can be diagnosed readily. We will look for an anterior draw, medial joint swelling, crepitus, wasting of the hind limb and fat pad sign, and degenerative changes in the lateral view of the radiograph. We should proceed with an x-ray of the limbs and pelvis to rule out other concomitant problems or another differential diagnosis.
Surgical intervention is often warranted, especially in large breed dogs. Various surgical techniques are pursued accordingly to the experience of the veterinary surgeon and their preference. Tibial plateau leveling (TPLO) is one of the most widely practiced procedures by experienced veterinary surgeons and specialists. During surgery, we will attend to any meniscal lesions and remove remnants of the torn ligament.
It is one of the most common problems in toy breed dogs in Hong Kong. It can also occur in medium or large dogs. Luxation can be medial, common in small breed dogs, and lateral in large dogs. The patella will luxate automatically and slides in and out of the patellar groove. The patellar ridge might be flattened due to this constant sliding of the patella during developmental growth. This is a congenital problem, and the conditions might not associate with lameness until a very late stage. Yet, the disease process in some cases might be noted when the dog is only a few months old. The severity of the condition might worsen as the dog grows until at about 9 months old when the anatomical grade of luxation becomes final.
We generally grade it according to the severity of the disease; grade 1 is mild and usually do not show any clinical sign; grade 4 is the most severe condition and can result in lameness and abnormal posture even at a few months old. Conditions are usually bilateral, affecting both knees. The patella will luxate automatically and slides in and out of the patellar groove. It was once believed that cruciate rupture bears a direct positive correlation with medial patellar luxation.
There is a difference of opinion regarding dogs with a mild grade of luxation at a young age yet not showing any clinical signs. Each case should be assessed individually by an experienced orthopedic veterinarian.
The surgical procedure usually involves deepening of the patellar groove, tightening of the fascia, and transposition of the tibial tuberosity. More advanced conditions with limb deformity might warrant the correction of the limb alignment. If there is a severe erosion of the patellar cartilage and irreversible arthritic changes, the placement of a prosthetic groove might be considered.
This remains an uncommon condition in dogs. Etiology could be multifactorial and thought to be related to genetic, nutritional, and related traumatic causes. Usually, there is a detached cartilage flap involving one of the femoral condyles. Signalment indicated dogs under 12 months old is more prone to this disease. Surgical treatment removal of the cartilage fragment warrants a good prognosis.