Abstract
Medial patellar luxation in dogs is one of the most common patellar problems presented to the veterinary practitioner. It is observed in toy and miniature breed and the majority of cases is a congenital form. Because of extensor mechanism's instability, it causes deformity and disorder in the growth of the affected limb when the luxation is left without treatment As lameness is not easily detectable in puppies, early diagnosis and correction are essential for therapy. Up to now, there has not been any reports refering to the diagnostic methods and the optimal age for correction in young dogs. Thirteen 45-90 days old puppies, have grade I and/or II medial patellar luxation. Only by palpation, all 13 dogs were diagnosed of patelar luxation. Skyline radiographic view was useful to interpret patellar morphology and depth of trochlear groove only above 60 days old. However, it was difficult to make definite diagnosis patellar luxation. The caudocranial and lateral radiographic view as well as ultrasonographic skyline view were not showed of patellar luxation. 2 puppies had unilateral patellar luxation and 11 puppies had bilateral patellar luxation which more serious on the left than on the right. Only 3 puppies among 11 puppies with bilateral patellar luxation were observed of lameness degree 1. Regardless of grade of patellar luxation and lameness, we performed trochlear chondroplasty using a U-shape sculpture blade to minimize cartilage injury, transposition of tibia tuberosity with No. 1 Supramid to align extensor mechanism and lateral imbrication. After surgery, we examined the operated animal daily for 10 days and on 15, 30 and 60 days after surgery respectively. After operation, pain and fever became normal on 7 days, swelling on 10 days, respectively. On 10 days after surgery, dogs showed normal standing position, and normal walking was observed in 15 days after surgery. In force plate analysis, the operated legs were normal weight bearing at 30 days after operation. After surgery, not only patellar luxation and clinical signs have been gradually reduced but also bone growth have become normal without showing growth physeal plate injury. The survival rate of puppies over 62 days old was 100%, while 42-45 days old 37.5%. The above results suggest that optimal age for surgical correction of congenital medial patellar luxation is recommended over 60 days old. In conclusion, combination of trochlear chondroplasty, transposition of tibia tuberosity, and lateral retinacular imbrication is appropriate for over 60 days old puppies to efficiently correct patellar luxation.
