Introduction: A 4yo MN merle Pomeranian called Bubblegum presented with LHS hindlimb lameness and skipping. He had been diagnosed with bilateral patella luxation and was referred for stabilisation.
Examination: General examination was unremarkable. Orthopaedic examination of both stifles confirmed bilateral grade III MLP. There was no concurrent cranial drawer or tibial thrust. No furter orthopaedic abnormalities were found.
Diagnostic Imaging: Plain radiographs and CT scan of the pelvis, femurs and stifles were obtained. No substantial angular limb deformity or femoral neck inclination issues were present. Medialisation of the patella ws present.
Client Discussion: Given this was a straight forward case we discussed traditional approaches to MLP management such as sulcoplasty, tibial tuberosity transposition etc. Complications outlined included reluxation of the patella (lower than 2% in our hands), infection, implant failure (pin loosening/seroma), ACL disease etc.
Operative Management: Bubblegum was premedicated with acepromazine and methadone before being induced for anaesthesia with propofol and maintained on isoflurane. Intraoperative patient monitoring included Spo2, ETCO2,BP, ECG, HR and Temp. Preoperative, operative and postoperative IV Fluids were given. Temperature was maintained with a Bair Hugger and warm fluid underblanket. Ioban adhesive second skin was applied.
A lateral parapatellar approach to the LHS stifle was made. The femoral sulcus was quite shallow with some medial condylar full thickness and ulceration. The ACL and menisci appeared WNL.
Medial desmotomy was performed using monopolar electrocautery through the stifle retinaculum extending proximally.
A block recession sulcoplasty was performed using a Stryker micro reciprocating saw, osteotome and mallet. Following this the patella was well recessed and covered. Tibial tuberosity transposition was performed again using the reciprocating power saw. The base was maintained to act as a tension band and secured with three fine K wires. The lateral retinaculum and para patellar tissues were imbricated, before lavage and suction. Routine closure was performed.
Outcome: Bubblegum was discharged on strict confinement instructions. He was crate rested for much of the time with short leash walks. Bandages were changed twice weekly for two weeks before removal. Recheck xrays at 6 weeks postop revealed stable patella and implants with good early healing.
Discussion: Patella luxation remains one of the most commonly observed orthopaedic conditions seen in practice. The most common presentation is a medial luxation in a small breed dog. Surgical case selection is determined by grade, severity of discomfort or dysfunction (lameness/skipping).
Most cases are congenital with occasional traumatic luxations presenting. The majority of patients can be safely managed with the traditional techniques outlined in this report. Cases with substantial femoral varus require DFO (Distal Femoral Ostectomy) to correct the angular deformity. Wedge recession and block recession can be employed (block provides better proximal coverage) dependant on surgeon choice. In severely diseased joint a PGR (Patella Groove Replacement) is recommended.
In large active patients a tension band may be required on the tuberosity transposition.
Complication rates in routine patella luxation rates are quite low. The main risk is repeat luxation which occurs in less than 1 in 50 cases. Revision requires re-operation typically to tighten the para-patellar tissues. Pin loosening and resultant seroma require pin removal. Infection is very rare. Overall return to function is excellent.
