Lars F.H. Theyse, PhD, DVM, DECVS
Associate Professor Orthopaedic-Neuro-Oral & Craniofacial Surgery, Department Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
Cranial cruciate ligament disease (CCLD) is the most common cause of hind limb lameness in the dog. The disease is characterized by a chronic synovitis and progressive degeneration of the cranial cruciate ligament. The degeneration of the cranial cruciate leads to instability of the stifle joint with caudocranial shift and endorotation of the tibial plateau. The instability can cause an overloading of the medial meniscus. This typically results in a crushing injury of the caudal horn of the medial meniscus. The clinical diagnosis is based on a positive drawer test in which the tibial plateau is manually displaced cranially with a fixed distal femur. The drawer test can be best performed with the stifle in a 135 degree angle which also is the regular standing angle. Instability of the stifle decrease coming from the standing angle with increasing flexion and extension. As CCLD is a chronic progressive syndrome, most of the dogs present with clear signs of osteoarthritis, even if the symptoms seem to be acute. Osteophyte formation can be appreciated by manually assessing the trochlear ridges of the patella and the region of the medial collateral ligament. Effusion of the joint can be determined by palpating the joint space medial and lateral of the patellar tendon. Radiography of the stifle joint can give additional information of joint effusion, and osteophyte and enthesophyte formation. As stated earlier, progressive osteoarthritis on radiography is a common finding. Rupture of the caudal horn of the medial meniscus will exacerbate the clinical signs of lameness but cannot be appreciated radiographically. The integrity of the menisci can be assessed using ultrasonography of MR imaging. Cranial cruciate ligament disease usually affects both stifle joints.
Treatment of cranial cruciate ligament disease initially aimed at removing remnants of the cranial cruciate ligament, treating meniscus injury by partial meniscectomy and restoring stifle joint stability by using intra- or extraarticular autogenous or artificial ligaments.1,2 One of the recent additions to group of the lateral stabilization procedures is the introduction of the TightRope technique. The TightRope procedure uses femoral and tibial bone tunnels and a multifilament artificial ligament to stabilize the CCL deficient stifle. The bone tunnels are positioned on the lateral side of the joint isometrically to the origin and insertion of the CCL. This means that the bone tunnels are drilled just distal of the femorofabellar joint and caudal in the tibial groove of the tendon of the long digital extensor muscle. Although all of these techniques are successful in restoring joint function, the recovery after these arthrotomies takes a considerable amount of time and slow improvement of lameness. Meniscal injuries during or after the recovery period may still be a complicating factor attributed to insufficient stability of the stifle joint.
The introduction of stifle osteotomy procedures was aimed at improving stability and decreasing recovery time. The first change in managing the cranial tibial instability was the introduction of the tibial plateau levelling osteotomy (TPLO).3,4 Rational behind this procedure was to eliminate cranial tibial thrust by levelling the tibial plateau slope, characterised by the tibial plateau angle, to perpendicular to the long axis of the tibia. The procedure started as a cranial closing wedge osteotomy of the proximal diaphysis of the tibia. The procedure evolved in a radial osteotomy of the tibial plateau in combination with cranial rotation and levelling of the tibial plateau. The tibial plateau is stabilized with a designated plate. The TPLO procedure results in a dynamic stabilisation of the stifle joint which is in part attributed to the caudal cruciate ligament. The cranial drawer sign is not eliminated by this procedure. Secondary meniscal injury remained a common complicating factor and intraoperative meniscal release was introduced to overcome this problem. Recent studies have shown that meniscal release in itself results in severe stifle osteoarthritis and is not the treatment of choice.5
The second osteotomy procedure is the tibial tuberosity advancement (TTA) technique.6 The TTA aims at eliminating cranial tibial thrust by altering the angle of attack of the patellar ligament to perpendicular to the tibial plateau. The technique relies on a cranial advancement of the tibial tuberosity after an osteotomy of the tibial crest. The crest is stabilised with a cage and forked tension plate. The TTA procedure results in a stable stifle joint and eliminates the drawer sign. The advancement of the tibial tuberosity not only alters the angle of the patellar ligament but also tensions the medial and lateral fascia of the stifle joint. The TTA is less invasive then the TPLO procedure.
The third osteotomy procedure is the triple tibial osteotomy (TTO).7 The TTO aims at combining the theoretical basis of the TPLO and TTA. The TTO relies on a tibial cranial closing wedge osteotomy in combination with an incomplete osteotomy of the tibial crest. By closing the tibial cranial wedge, the tibial plateau is levelled and the tibial tuberosity is advanced. The tibial wedge osteotomy is stabilised using a plate without the need of osteosynthesis of the tibial crest. This procedure is intermediate invasive compared to the TPLO and the TTA. These three procedures can be combined with arthroscopy of the stifle joint eliminating the need for an arthrotomy and decreasing subsequent postsurgical pain.
Although these stifle osteotomy procedures may result in a faster recovery time, the final outcome is not better than the classic cranial cruciate surgery techniques.
Therefore a cost-effective lateral capsular imbrication technique may be the best solution in many cases. Stability is achieved by imbricating the lateral capsule at the level of the patellar tendon. The procedure is performed as a mini-arthrotomy with a skin and capsule incision immediately lateral and parallel to the patellar tendon and extending from the distal patellar pole to insertion of the tendon on the tibial crest. The lateral femoropatellar ligament is left intact. Through this approach the joint is opened, remnants of the CCL are removed, the menisci are inspected and palpated, and if indicated partial meniscectomy can be performed. The lateral joint capsule can be imbricated using interrupted horizontal mattress sutures in an overlapping fashion with monofilament absorbable suture material (PDS). During tightening, the sutures the stifle should be in the 135 degree standing angle while reducing the tibial plateau in a caudal direction and preventing inward rotation. The flap which is created in this way can be stabilized using a modified Lembert suture. A proper imbrication prevents inward rotation of the tibial plateau, thus protecting the medial meniscus and augments the caudocranial stability of the patellar tendon. The procedure is applicable in most dogs with moderate-to-severe osteoarthritis and thus limited stifle instability.
In conclusion, there is no gold standard procedure in treating CCLD in dogs. As CCLD is a chronic degenerative disease with a presumed genetic background, emphasis should be eliminating the disease by breeding efforts.8 As long as dogs are referred with CCLD, the treatment of choice is mainly determined by the preference of the surgeon.
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