Vet360 Vet360 Vol 05 Issue 03 - Page 7

EXOTICS The craniomedial band is taut in both flexion and extension, while the caudolateral band is only taut in extension. For this reason, the craniomedial band is often the first portion of the ligament to fail. 1 These patients are considered to have a partial tear, and medical management of these cases has shown variable success depending on the techniques used. Diagnosing a CCL tear High suspicion of partial or complete CCL tear is typically identified on physical examination coupled with two-view stifle radiographs. The most common physical exam findings include stifle joint effusion, medial buttress (with chronicity) along with cranial drawer sign and tibial thrust. Cranial drawer sign may only be present on flexion of the limb in patients with a partial CCL tear. These patients also tend to be painful on hyperextension of the stifle. Radiographs will typically confirm evidence of joint effusion and may show signs of osteoarthritis in the joint. Some patients may also show the tibia cranially displaced (in drawer) when compared with the femur (Figure 1). Minimally invasive procedures including standard stifle arthroscopy or, more recently, arthroscopy via needle scope may also be used as a diagnostic tool to confirm the diagnosis of a partial or complete CCL tear Magnetic resonance imaging (MRI) is an uncommon diagnostic tool used for identification of CCL tears or meniscal disease in veterinary medicine at this time. Non-surgical management articular structures should be evaluated, with special attention paid to the articular surfaces of the femur, tibia and patella as well as the long digital extensor tendon, both the cranial and caudal cruciate ligaments and the medial and lateral menisci. Meniscal tears should be debrided if present. There’s also continued debate over the procedure known as a “meniscal release.” This technique involves transection of the caudal attachments of the medial meniscus with the goal of reducing the risk of subsequent meniscal tearing. However, it has been shown to result an increased contact area of the medial joint compartment, contributing to accelerated development of osteoarthritis in the stifle joint. 7 Intra-articular stabilisation techniques are the mainstay of human anterior cruciate ligament (ACL) repairs. These techniques employ harvesting a biologic graft from another tendon in the body or from a cadaver and then drilling bone tunnels and replacing the torn ACL. The graft will then go through a period of devitalisation, followed by revascularisation and ligamentisation over an approximately 20-week period. During this time, the graft is at a diminished tensile strength, and overuse may lead to graft failure and returned stifle instability. More recent research has focused on synthetic intra-articular replacement or biologic scaffolds as opposed to the biological replacement techniques that have fallen out of favour in the veterinary surgical field. Today, however, most surgeons are finding themselves electing extra- articular or biomechanical stabilisation techniques. Medical management options for partial CCL tears may consist of varying combinations of rest, nonsteroidal anti-inflammatory drugs (NSAIDs), nutraceutical use and physical therapy. But more recently platelet- rich plasma (PRP) and/or canine stem cells derived from bone or fat have been used with varying and, unfortunately, inconsistent success. 5 There’s also an argument that early surgical intervention in patients with partial tears may help in preserving the remainder of the intact ligament and that these patients may have a better postoperative success. Surgical management options Surgical options for these patients are broken down into two general categories: ligament replacement versus biomechanical techniques. More recent literature has suggested that using a combination of a ligament replacement and biomechanical techniques may result in a more stable stifle joint postoperatively. 6 Ligament replacement techniques can be further subdivided into intra-articular or extra-articular techniques. Regardless of stabilisation procedure, it’s routine to first perform a joint exploration. This may be achieved by an open arthrotomy or arthroscopically. All intra- Figure 2: Left Stifle, lateral view. Immediate postoperative TPLO. Issue 03 | JULY 2018 | 7