Complications and the quality of life after surgical correction of medial patellar luxation in dogs

Sammanfattning: Medial patellar luxation is one of the most common orthopedic disorders in dogs, especially in small breed dogs. It is, in most cases, a developmental disorder associated with skeletal deformities and malalignment of the extensor mechanism. Patellar luxation is classified into four grades, see Table 2. Surgical treatment is composed of bone reconstructive techniques and soft tissue reconstructive techniques and is often performed in dogs with patellar luxation grade 2-4. The most common complications after surgery are patellar reluxation and implant related complications, according to previous studies. In many studies, an increased risk of complications has been associated with the severity of the luxation. In most previous studies assessing the outcome of surgery, the objective has been the short-term outcome. Owner questionnaires that evaluate surgical outcome, compare treatment methods, assess chronic pain, function and quality of life has recently been used in several studies with dogs affected by orthopedic diseases. The purpose of this thesis is to evaluate complications, the long-term outcome and the quality of life in dogs treated surgically for medial patellar luxation. The purpose is also to analyze if there exist any factors that affect the complication rate and the long-term quality of life. Retrospective data such as patellar grade, surgical methods, complications, and bilateral or unilateral disease, have been recorded from the medical records of 45 dogs treated surgically for medial patellar luxation at the University Animal Hospital in Uppsala year 2012-2015. In this study, owners of the surgically treated dogs answered an online questionnaire regarding their dog’s stiffness, function, lameness, and quality of life in October-November 2017. The answers were converted into a score. To assess the quality of life in the surgically treated dogs, the answers and the total scoring of the questionnaire has been compared with the answers of a control group composed of dogs without any orthopaedic disease. The total postoperative complication frequency within one year was 31.7% among the cases with available medical data (41 out of 49 cases). Gastrointestinal symptoms were the most common complication. All dog owners in the case group who answered the questionnaire (29 out of 45) except one rated their dog’s comfort to be better today than before the surgery, but some dogs still experience discomfort. Most of the surgically treated dogs had a good or acceptable score on the questionnaire, but there was a significant difference in scoring between the case group and the control group. This finding indicates that even after a successful surgical correction of medial patellar luxation, the expectation cannot be to regain equal mobility and function in the stifle joint compared to a dog without any orthopedic disorder. There was a great variation in total scoring among the surgically treated dogs, but the reason for this variation could not be concluded. Lameness was the most common problem for the surgically treated dogs according to the owners. Mobility and function were also affected but to a lower extent. The dogs’ mood, willingness to participate in play, vocalization, and quality of life seems to be comparable between surgically treated dogs and dogs without any orthopedic disorder. Further research is needed to study the factors that could affect the long-term outcome, quality of life and lameness in surgically treated dogs.