Introduction: A 6yo MN Collie from Brookvale presented with significant LHS hindlimb lameness. The clients had noted he was slow to rise and unable to complete longer walks. He was being medicated with Beransa and NSAIDs.
Examination: On physical examination the animal appeared overweight with vitals within normal limits. Gait examination confirmed LHS hindlimb lameness. No ataxia or paresis was present. Orthopaedica examination of the LHS hip confirmed gluteal muscle atrophy, crepitus and grating. Pain was present on extension. The contralateral hip was comfortable. The stifles were WNL. Neurological exam was normal.
Diagnostic Imaging: Plain radiographs of the pelvis confirmed lateral LHS coxofemoral incongruency and severe luxation. Significant chronic degenerative changes were present. The femoral head was luxated craniodorsally with a misshapen femoral and thickened femoral neck. The acetabulum was worn, sclerotic and filled.
Client Discussion: We discussed total hip replacement in detail. Complications such as infection, dislocation of the prosthesis, fracture, subsidence and wear were discussed in detail.
Operative Management: The patient 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.
The limb was surgically prepared and a povidine iodine impregnated adhesive skin film applied. We then used a surgical stockinet.
A lateral approach to the LHS hip was made and the stockinette sowed into the wound. Muscle sparing techniques were applied. Profound secondary osteoarthritis and osteophyte formation were noted. Complete cartilage loss and eburnation were present on the acetabulum and corresponding femoral head.
A standard press fit titanium in growth Biomedtrix BFX total hip replacement was performed. We used a number 9 BFX Lateral Bolt Stem with a 17mm + 3 BFX Cup-Poly-XVE Cup. We used an intraoperative mini C-arm to assess position and size of the implants.
Outcome: George recovered well overnight and was discharged from hospital the following morning. The clients were instructed to keep him quiet for 6 weeks. Short toilet walks were taken 4 times daily outside on the lawn. At the 2 and 6 week recheck exams he was walking comfortably and the wound had healed well. Nine months postoperatively he is leading a normal life with full athleticism and no hip pain.
Discussion: Over 60,000 Biomedtrix THRs have been performed worldwide since being introduced in 1990. There is an overall success rate of 95% in THR cases. I initially trained on the CFX (Cemented) system in Tennessee in 1999 then started on the BFX (Cementless) system on its launch in 2003. Since then there have been numerous improvements made to the system. There are now far more sizes for patients ranging between 3kg and 70kg. There has been considerable development of the BFX stem and cup materials away from cobalt chromium to advanced titanium alloy systemsmanufactured by Electron Beam Melting (EBM). There has been a shift from coatings to integrative porous textures resulting in enhanced frictional resistance promoting superior bone ingrowth.
Recent developments including BFX EBM Collared stems and Lateral Bolt systems aid in reducing stem subsidence. Acetabular cup technology has also progressed with the liners containing Highly Cross-lLinked Polyethylene (HXLPE) and Vitamen E stabilized Polyethylene (Poly-XVE).
Another modality which has improved safety we have used in hundreds of cases over the past 10 years is intra-operative C arm imaging.
