Triple Antiluxation Patellar Suture Surgery for Medial Patellar Luxation in Dogs - a Pilot Study with Short-Term Outcomes

Abstract

Background: Patellar luxation surgery in dogs is aimed at correction of patellar misalignment in relation to the trochlear groove, stabilization of the joint and tension balance in the peripatellar soft tissues. Timely surgery especially in immature dogs, is essential to shape a trochlear groove of adequate width and depth, to modify abnormal forces on growing bones and prevent long-term joint damage. In dogs up to 2 years of age, soft tissue techniques may be attempted to mitigate the negative effects of the abnormal loading on the developing joint and the potential risk of joint disease associated with arthrotomy and trochleoplasty. Recent advancements in veterinary orthopaedics are focused on the development of less invasive surgical techniques. They not only enhance the return of patients to normal activity levels, but also offer several potential benefits, as smaller incisions, reduced anaesthesia time and blood loss compared to traditional open surgeries. The present pilot study describes a new, less invasive surgical method for treatment of low-grade medial patellar luxation (MPL) in young dogs - the triple antiluxation patellar suture (TAPS) and presents the short-term outcomes on the basis of clinical and diagnostic imaging data.

Materials, Methods & Results: The TAPS surgery was applied in 19 dogs (23 joints) with grade II MPL. The technique does not involve arthrotomy: only the skin, subcutaneous tissue and fascia latae are incised while the joint capsule remained intact. After alignment of the patella in the centre of the trochlear groove, the soft tissues are fixed in 3 points with non-absorbable Mayo sutures arranged in a checkerboard pattern. The results were monitored at the end of the 2^nd and 6^th postoperative months using the Bologna Healing Stifle Injury Index (BHSII) and computed tomography imaging. The median (IQR) time for the TAPS method was 29 (26-30.75) min. The dogs began to bear weight on the operated leg after median (IQR) 4 (2-4) days. The evaluation of the patients’ condition by the BHSII tool showed a statistically significant increased scores 2 months after surgery in all groups of parameters with exception of the joint stiffness. By the 6^th post-operative month, the differences were significant (P < 0.001) for all studied indicators. The greatest improvement occurred in the parameters assessed visually (gait, lameness) - by 71.5% compared to the preoperative period. The limb function scores increased by 26.3% on the 2^nd month and by 47.4% on the 6^th month.

Discussion: Apart the lower risk of postoperative infection, the short TAPS surgery time, respectively the short time under anaesthesia is especially suited for juvenile and young patients as the immaturity of their hepatic and renal systems associated with slower drug metabolism and elimination poses specific risks from prolonged effect of anaesthetics. One of the main advantages of the presented operative technique is that it is less invasive as the joint remains intact. That is probably the cause for the substantially earlier beginning of weight bearing with the operated leg - on the 4^th post-operative day. Although trochleoplasty was not performed in our study, the rate of reluxation was relatively moderate. This may be due to the fact that all dogs had grade II MPL, weighed less than 5 kg; moreover, although shallower, the trochlear groove morphology was preserved. The reluxation rate is comparable to that obtained in dogs treated with arthroscopic fascia imbrication without trochleoplasty. The presented surgical technique can be suitable for correction of intermittent MPL in dogs with trochlear groove shallower than normal but with preserved trochlear morphology due to the short recovery period and the lack of some risks associated with open joint surgery (e.g. infection).

Keywords: medial patellar luxation, small-breed dogs, surgery without arthrotomy.