Corrective surgery for canine patellar luxation in 75 cases (107 limbs): landmark for block recession

Canine medial patellar luxation (MPL) is a very common orthopedic disease in small animals. Because the pathophysiology of this disease involves various pathways, the surgical techniques and results vary according to the veterinarian. Further, the landmark for block recession is not completely clear. We retrospectively evaluated 75 dogs (107 limbs) with MPL in whom our landmark for block recession was used from July 2008 to May 2013. Information regarding the breed, age, sex, body weight, body condition score (BCS), lateral vs bilateral, pre-operative grading, surgical techniques, removal of implants, concomitance with anterior cruciate ligament (ACL) rupture, re-luxation, re-operation, and rehabilitation was obtained from the medical records. The breeds were as follows: Chihuahua (n=23), Pomeranian (n=12), Yorkshire Terrier (n=9), and so on. The study group consisted of 33 males (castrated n=13) and 42 females (spayed n=21). The median age was 53.3±35.9 months (32-146 months); 13 cases were less than 12 months of age (17.3%). The pre-surgical BCSs were as follows: 1 (n=0), 2 (n=20), 3 (n=24), 4 (n=24) and 5 (n=7). The body weight was 4.51±3.48 kg (1.34-23.0 kg); 71 cases (94.7%) were less than 10 kg. The MPL grades (each limb) were G1 (n=1), G2 (n=18), G3 (n=78), and G4 (n=10); 32 cases were bilateral and 43 cases were unilateral (right n=27; left n=16). The specific surgical procedure (distal femoral osteotomy) was 3 stifles in Chihuahuas. Concurrent with ACL rupture was 16/107 stifles (15.0%) corrected with the over-the-top method or the extracapsular method in Papillons (5/6), Chihuahuas (5/23), and so on. The occurrences of re-luxation and re-operation were 3 out of 107 stifles (2.8%) and 0%, respectively. In this retrospective study, we present a potentially good surgical landmark for block recession of MPL in dogs.