Rupture of the cranial cruciate ligament (CCL) is the most common orthopaedic injury encountered in dogs; it is also the injury for which the highest number of therapeutic approaches exist, with more than 100 different methods currently being proposed. Paradoxically, results obtained exhibit a high degree of uniformity, being judged satisfactory in 80% of cases despite wide disparity between different situations, namely origin of the rupture, size and breed of the dog, the owner's wishes and prevailing financial conditions. ACL rupture in the dog is associated with osteoarthritis. The majority of ruptures are of degenerative origin and development of osteoarthritis is a common finding after CCL rupture, as evidenced by clinical and experimental data (Pond-Nuski model). Our own approach to CCL rupture is the result of our experience of over 1500 surgical cases stored in a computer data base. Using this information, we have been able to study and publish findings on certain aspects of CCL rupture, namely origin of the rupture, treatment using the modified over the top method, meniscal injury, predispositions of different breeds and efficacy of supplementary medical therapy (carprofen). We consider it essential to select the therapeutic approach and prognosis in accordance with the origin of the rupture, the size and breed of the dog concerned, the owner's wishes and financial conditions. Our approach is based upon clinical cases and the results of our respective studies.
Diagnosis is principally based on clinical evaluation with demonstration of cranio-caudal instability by means of the "drawer sign". The tibial compression mechanism described by Henderson is also useful. Prior functional examination of the animal's gait during walking and trotting can be used to determine the intensity and location of the limp as well as the existence of any abnormal movements; functional examination involving manipulation and palpation of the entire limb can be performed to gauge the existence of pain as well as any periarticular reactions. Following these different examinations, the animal is examined for joint instability. These examinations are completed by a careful neurological examination. Radiological examination is performed in two positions: latero-lateral and cranio-caudal. This examination can be used to identify tibial anteversion, articular pinching and the presence of osteoarthritis; it can also be used to exclude other lesions such as fractures or tumour. High-quality radiographs will demonstrate soft-tissue lesions such as tearing of the CCL or caudal compartment reaction.
Surgical treatment is recommended for CCL rupture. More than 100 surgical techniques, either original or modified, have been described. Intra-articular methods can be used for reconstitution or the cranial cruciate ligament. Extra-articular methods are based on the principle of joint stabilisation without actual opening of the joint. We mainly use a modified over the top method. Following lateral arthrotomy, exploration and cleaning of the joint is carried out. Investigation for meniscal injury is performed and treatment comprises systematic meniscectomy. A strip of tibial-patellar ligament and fascia is taken from the lateral face of the joint. The neo-ligament is passed in front of the tibial-patellar ligament and secured by means of 3 sutures; it is then passed intra-articularly using a special introducer and is brought out above the lateral condyle (over the top) before being passed through the femoral sesamoid ligament. In middle-sized and large dogs, the neo-ligament is attached by means of a screw and notched washer. In smaller dogs, where rotational instability is more pronounced, the neo-ligament is attached by suture between the fascia and the tibial-patellar ligament near its tibial insertion, thereby creating a structure capable of maintaining joint stability during rotation. The joint is not immobilised; we recommend moderate and controlled exercise for one month.
Recently, other techniques have been proposed based upon a new approach to the biomechanics of the canine knee. The underlying principle of these techniques is correction of the angle of the tibial plateau in order to offset tibial thrust. We use a correction method involving cuneiform osteotomy, with the osteotomy angle being determined by the degree of tibial slope. Osteosynthesis is performed using special Slocum plates or human AO plates for 4.5 screws, T plaques (for 2.7 and 2.0 screws) or in certain cases, standard plates. These techniques can be used to modify tibial thrust in event of modification of the architecture of the tibial plateau or the mechanics of the knee in larger breeds. Antibiotics (amoxicillin/clavulanic acid 12.5 mg/kg, b.i.d.) are prescribed for 5 days and the wound is disinfected twice daily. Close monitoring of the animal is recommended for 1 month, with 2 to 3 daily walks, keeping the animal on a lead.
Results are satisfactory (excellent or good) in over 80% of cases. Despite the wide range of treatments proposed, the results appear similar, with a mean 80% of satisfactory results in spite of differences in terms of breed, age, origin of rupture and evaluation methods. Surgery alone cannot address all problems involved, particularly that of osteoarthritis. None of the proposed methods appears able to significantly halt progression of this disease. By extrapolation from human surgery, CCL rupture in the dog was long considered to be a trauma-induced condition. In a retrospective clinical study of 400 cases of CCL rupture, a degenerative character of this condition was suspected in 77% of cases. Various factors militate in favour of degenerative origin: over 70% of animals affected were aged over 6 years, despite the fact that this age group constituted only 20% of the total population. Bilateral lesions were seen in 27% of cases together with presence of arthritis in dogs presenting clinical signs very recently (less than two weeks). In most cases, the ligament was absent or "degenerate". Absence of direct or functional trauma in over 90% of cases is a further factor in favour of a degenerative cause of rupture.
In order to improve the quality of results, we feel it is necessary to provide supplementary drug treatment.
The study included 100 dogs undergoing cranial cruciate ligament repair surgery using a modified over the top intra-articular method. 50 dogs received post-operative carprofen per os at a dose of 4 mg/kg/day for 1 month. A control group of 50 dogs received no antiinflammatory treatment. Results in terms of post-operative progress in these two groups were studied at D30, D90 and D180 using a score sheet completed by the veterinarian and the animal owners. The results indicate that carprofen improved the quality and swiftness of functional recovery both during the month of treatment and over the subsequent 2 months. The efficacy of carprofen during the first month of treatment with regard to total score and the various study parameters may be due in part to its anti-inflammatory and analgesic properties. Persistence of this efficacy beyond the treatment period may be the result of various factors. A recent study has shown that rapid post-surgical utilisation of the affected limb by means of a specific rehabilitation programme for dogs undergoing cranial cruciate ligament repair surgery improves the quality of post-operative recovery. Marsalis showed that a 4-month rehabilitation programme produced superior functional recovery after 6 months (peak vertical force and vertical impulsion) compared with limited exercise alone. By reducing postoperative pain, carprofen may allow better utilisation of the affected limb during the initial phases of convalescence. This earlier and more intensive mobilisation in the treatment group may account for the difference seen two months after discontinuation of analgesic therapy. Greater mobilisation of the operated limb during the initial phases could also explain the greater laxity observed at D30 in the treatment group. Furthermore, it has been demonstrated that post-operative laxity does not adversely affect good post-surgical recovery of animals. This greater laxity should not be considered as a limitation to the use of carprofen in the postoperative phase of treatment for CCL rupture but rather as a sign of improved utilisation of the joint. Following joint surgery, early use of the affected limb must always be a priority. Another hypothesis that may account for the favourable residual effects two months after discontinuation of treatment concerns the potential influence of carprofen on progression of osteoarthritis. The studies by Benton and Pelletier suggest a beneficial effect of this drug on cartilage and on progression of osteoarthritis.
Meniscal lesions are very commonly associated with CCL rupture. We observed such lesions in 67% of animals in a series of 400 cases and in 83% of cases in a recent series of 1000 animals; the incidence of such injuries reported in the literature ranges from 10 to 76%. These variations may be due to the meniscal examination methods used, and in particular, the method used to explore the posteromedial compartment; lesions are found practically solely in the posterior horn of the medial meniscus. Clinical examination provides only an approximate diagnosis; while arthrography, arthroscopy and MRI are considered essential laboratory examinations in man, their use is restricted in veterinary surgery due to lack of available methods or high costs. In dogs, exploratory arthrotomy constitutes the most reliable diagnostic method. The posterior horns and 2 menisci can be examined by means of a lever maneuver using a Hohmann retractor. The most commonly seen lesion is complete dislocation of the posterior horn. We perform partial meniscectomy of the injured region; our study shows that meniscectomy does not affect the quality of subsequent functional recovery.
Post-operative use of Rimadyl in combination with a stabilisation method effective over time, such as the over the top method, has produced significant improvement in the quality of our results and probably retards the progression of arthritis. We consequently recommend the use of Rimadyl for 3 weeks to 1 month during the post-operative period. We advocate the same therapeutic approach for other joint diseases leading to arthritis (e.g., elbow and hip diseases, osteochondrosis).