Technique for Canine Total Hip Replacement

Between August 1976 and April 1980, a total of 132 canine total hip replacements using a commercially available prosthesis, were performed on clinical patients at The Ohio State University Veterinary Hospital and Berwyn Veterinary Hospital, Chicago. The technique for total hip replacement is described. Details of preoperative evaluation, the operative procedure, and postoperative care are presented.     

The Effect of Surgical Approach on Femoral Stem Position in Canine Cemented Total Hip Replacement

A prospective clinical study was designed to determine the effect of surgical approach on femoral stem position in canine cemented total hip replacement. Candidates for total hip replacement were randomly placed into one of two groups. In one group (n = 10), a craniolateral approach to the hip joint was made, incorporating a femoral trochanteric osteotomy. In the other group (n = 11), a craniolateral approach to the hip joint was made without performing a femoral trochanteric osteotomy. Radiographs obtained immediately after the operation were evaluated by two independent examiners for femoral stem position (neutral, varus, or valgus) and percentage of femoral canal fill, using a defined protocol. There was no statistical difference in femoral stem position between the study groups, whereas a greater percentage of canal fill was associated with the neutral femoral stem position.     

Cementless Total Hip Replacement in an Alpaca

Objective— To report management of a chronic slipped capital femoral epiphysis (SCFE) in an alpaca using cementless total hip replacement (THR).
Study Design— Case report.
Animal— An 18-month-old, 47 kg alpaca male.
Methods— Cementless THR was performed in an alpaca with a chronic, right SCFE, and secondary osteoarthritis. Force plate gait analysis was performed before and 8 weeks after surgery. Outcome was determined through clinical evaluation, radiography, and force plate gait analysis.
Results— Cementless THR resulted in marked improvement in the alpaca's comfort level, degree of lameness, and range of motion. On preoperative force plate gait analysis there was decreased contact time ( P =.01) and vertical impulse ( P <.01) of the affected limb, whereas at 8 weeks postoperatively significant differences in gait analysis between pelvic limbs were not apparent.
Conclusion— THR using a BioMedtrix^® canine cementless modular prosthesis restored hip function in an alpaca with coxofemoral osteoarthritis from chronic SCFE.
Clinical Relevance— THR may be an appropriate treatment for selected traumatic and degenerative conditions of the coxofemoral joint in alpacas.     

A Clinical Study of Canine Total Hip Arthroplasty

Our intent was to evaluate clinically total hip arthroplasty in the dog using the same procedures and prostheses. We replaced 20 hips in 15 dogs of both sexes and various breeds, weights, and ages. All animals exhibited pain caused by degenerative joint disease of one or both coxofemoral joints. Using Amstutz's system of grading at a minimum of 12 months post-operatively, none of the hips replaced were graded poor, 12.5% were graded fair, 12.5% good, and 75% excellent. Loosening of prosthetic components was by far the most common problem encountered in this study. Luxations were virtually eliminated by the use of the Richards Canine II total hip replacement system. Infections were found to be directly proportional to surgery time, number of operations performed, or both. Component failure occurred only when the size of the prosthesis was not properly matched to the size of the dog. Although these problems still must be overcome, we conclude that total hip arthroplasty is a valuable adjunct to veterinary medicine in selected cases.     

Canine Total Knee Replacement: Surgical Technique and One-Year Outcome

Objective— To describe a surgical technique for total knee replacement (TKR) in dogs with severe osteoarthritis (OA) and report 1-year outcome.
Study Design— Prospective clinical case study.
Animals— Dogs (n=6) with severe stifle OA.
Methods— Preoperative and postoperative evaluations were compared after 6 dogs had TKR. Data gathered included radiographs, goniometric measures of passive range of motion, ground reaction forces, and girth measurements of the thigh before surgery and at 6 weeks, 3 months, 6 months, and 1 year.
Results— Stifle extension and excursion angles were significantly improved by 3 months after TKR. Mean peak vertical force and impulse were significantly improved by 6 months.
Conclusions— TKR is a viable treatment option for dogs with severe stifle OA.
Clinical Relevance— With continued refinement of surgical technique, instrumentation, and implants, TKR could become a reliable treatment for dogs with disabling, painful nonseptic stifle OA.     

Total Hip Replacement in an Alpaca Using a Cementless Implant

Objective— To report use of a cementless total hip prosthesis in an alpaca.
Study Design— Case report.
Animals— Alpaca (n=1) with chronic craniodorsal coxofemoral luxation.
Methods— A 2.5-year-old Suri alpaca, 3 months pregnant, was admitted for evaluation of acute onset severe left hind limb lameness (grade 4/5) of 6 weeks duration. After diagnosis of craniodorsal luxation of the left femoral head, total hip replacement (THR) using a cementless implant was performed because of the poor prognosis for reduction of a chronic luxation.
Results— A press-fit prosthesis was used and the alpaca delivered a live cria 8 months later. Persistent mild mechanical lameness remained after surgery, with moderate reduction in mobility of the coxofemoral joint. The prosthesis was stable and correctly positioned at 7 weeks and at 9 months. There was mild exostosis surrounding the proximal aspect of the femur at 9 months, and Steinmann pins used to repair the trochanteric osteotomy were removed because of migration. At 1 year, the alpaca has a slight gait abnormality, remains with the herd on pasture and has been re-bred.
Conclusion— Chronic coxofemoral luxation in an alpaca can be managed by THR.
Clinical Relevance— THR is a viable treatment option in alpacas with severe coxofemoral disease.     

Radiographic Criteria for Evaluation of Uncemented Total Hip Replacement in Dogs

A zonal analysis system and corresponding nomenclature were developed to describe the location and nature of radiographic changes in canine uncemented total hip arthroplasties. Criteria to assess prosthetic component alignment, percentage of femoral canal fill, resorptive and formative bony changes, and alterations in the bone at the implant-bone interface were derived by studying serial radiographs of 100 consecutive canine uncemented total hip arthroplasties for up to 30 months after surgery.     

Radiographic Assessment of a Canine Uncemented Porous-Coated Anatomic Total Hip Prosthesis

Thirty uncemented porous-coated anatomic total hip prostheses in 24 dogs were evaluated radiographically at 6 months, 12 months, or 18 months after arthroplasty. All dogs were fully weight bearing and free of lameness at the time of follow-up. Radiographs were assessed for prosthetic component alignment, percentage of femoral canal fill, resorptive and formative bony changes, and changes at the implant bone interface. No evidence of infection, loosening, or failure of component fixation was seen. Settling of the acetabular component and subsidence of the femoral stem was seen early after surgery. Cortical atrophy was seen in all femurs and was the most significant bony remodeling change. Early results of clinical and radiographic evaluation of uncemented total hip arthroplasty in dogs have been encouraging.     

Total Hip Arthroplasty in Nine Canine Hind Limb Amputees: A Retrospective Study

OBJECTIVE: To determine the outcome of total hip arthroplasty in canine hindlimb amputees. STUDY DESIGN: Retrospective evaluation of clinical cases. METHODS: Data recorded from the medical records of nine dogs included patient signalment, indication for amputation and total hip arthroplasty (THA), interval between amputation and THA, and surgical complications. Radiographs were used to assess implant orientation and evidence of complications. Functional outcome was assessed using direct patient evaluation by one of the authors or primary surgeons, or through telephone interview between the primary author and the owner. RESULTS: Seven dogs ultimately had a good or excellent clinical results. Complications occurred in five dogs. Four dogs luxated the prosthetic joint without an obvious traumatic event within 9 weeks of the initial surgery. Revision surgeries resulted in successful coxofemoral reduction in three of four dogs. There were no clinical or radiographic findings suggestive of implant loosening or infection. CONCLUSION: THA can be a successful salvage procedure in the canine hindlimb amputee with disabling, non-neoplastic, noninfectious coxofemoral disease. The risk of luxation in the early postoperative period is high and revision surgery is required for stabilization.     

Femoral Medullary Infarction Prevalence with the Zurich Cementless Canine Total Hip Arthroplasty

Objective— To document the prevalence of femoral medullary infarction associated with the Zurich Cementless Total Hip Replacement (ZCTHR) system in dogs.
Study Design— Case series.
Animals— Dogs (n=35) with 41 ZCTHR implants.
Methods— Medical records (February 1999–December 2002) were reviewed for dogs that had ZCTHR and at least 1 year follow-up with radiographic evaluation. Thirty-five dogs (41 ZCTHR) met the inclusion criteria. Femoral morphologic data, implant to bone relationships, and medullary infarcts were recorded. Data were analyzed for associations between infarct occurrence and morphologic details and dog characteristics.
Results— Eight of 41 femurs had radiographic evidence of infarcts (19.5%). Dogs with infarcts were significantly younger (mean [±SD] age, 18.5±5.2 months) compared with those without infarction (mean age, 44.4±5.6months; P =.027). None of the other variables were significantly different between dogs with and without infarcts. Three femurs with infarcts ultimately developed stem loosening.
Conclusion— A higher prevalence of femoral medullary infarcts was identified with ZCTHR compared with incidence reported for other total hip systems. Younger dogs were more likely to develop infarction.
Clinical Relevance— Femoral infarction appears to be associated with stem loosening. Adjustments in surgical technique or delaying surgery beyond 18 months of age may reduce incidence of infarction but needs further evaluation.     

Micro Total Hip Replacement for Dogs and Cats: Surgical Technique and Outcomes

Objective: To describe the surgical technique for the micro total hip replacement (Micro THR) system and report clinical outcomes. Study Design: Prospective study. Animals: Dogs (n=49) and cats (n=8) with coxofemoral arthropathy. Methods: Small breed dogs and cats with coxofemoral arthritis were enrolled for Micro THR. Patient data were recorded. Implant positioning and cement mantle quality were evaluated radiographically. Orthopedic examinations and client interviews were used to assess outcome. Results: Micro THR was performed unilaterally (40 dogs, 8 cats) and staged bilaterally (9 dogs) to resolve pain associated with osteoarthritis or trauma. Mean body weight was 7.2 kg. Postoperative complications included prosthesis luxation (9), cup aseptic loosening (1), and sciatic neurapraxia (1). Mean radiographic follow up was 96.1 weeks; 10 joints were followed for ≥3.0 years. Sixty of the 66 (91%) Micro THRs had excellent outcomes. Two dogs (<2.75 kg) were too small for the prosthesis and 4 dogs with unmanageable luxation had explantation. Conclusions: Micro THR is considered a satisfactory procedure for management of small breed dogs and cats with coxofemoral disease unresponsive to medical management. Clinical Relevance: Micro THR is a viable option to treat disabling disorders of the hip. More than 170 cat and small dog breeds, and many mixed breeds, could benefit from Micro THR surgery.     

Descriptive Histomorphometric Ingrowth Analysis of the Zurich Cementless Canine Total Hip Acetabular Component

Objectives— To (1) determine bone contact with the outer surface and ingrowth into the perforated outer shell of the Kyon acetabular component at 2, 6, and 12 months after total hip replacement (THR) and (2) determine correlation between radiographic lucency surrounding the cup–bone interface and bone contact and ingrowth.
Study Design— Experimental study.
Animals— Large breed dogs (n=11) with and without hip dysplasia.
Methods— Force platform gait analysis was performed preoperatively and 2, 6, and 12 months after THR. Curvilinear length of lucency (CLL) was measured on pelvic radiographs. Tissue contact with the outer cup and ingrowth into the cup were determined histomorphometrically at 2, 6, and 12 months.
Results— Peak vertical force and vertical impulse of the treated and control hind limb were not significantly different at any time. Median bone contact with the outer cup surface was 77%, 48%, and 76% at 2, 6, and 12 months, respectively. Median bone ingrowth into the cup perforations was 50%, 20%, and 44% at 2, 6, and 12 months, respectively. Median bone ingrowth to the inner cup surface was minimal at any time. CLL did not correlate with bone ingrowth.
Conclusions— Bone ingrowth into cup perforations occurred in each dog and was already present 2 months after THR, but most of the inner cup space remained vacant.
Clinical Relevance— Radiographic lucency surrounding the cup–bone interface does not allow assessment of bone contact with the outer surface or bone ingrowth into the Kyon cup in dogs without clinical problems.     

Changes in Cardiopulmonary Variables and Platelet Count During Anesthesia for Total Hip Replacement in Dogs

Changes in cardiopulmonary function and platelet count were determined in 22 dogs of various breeds that underwent total hip replacement with cemented femoral prostheses. In 11 dogs (group I) polymethylmethacrylate (PMMA) was inserted without venting the reamed and lavaged femoral canal. In a second group of 11 dogs (group II) a urethral catheter (ID: approximately 2.7 mm) was placed into the medullary cavity before the insertion of PMMA. The application of PMMA resulted in a decrease in end-tidal carbon dioxide tension (PETco₂) until 5 minutes after insertion of bone cement. Increases in arterial to end-tidal pCO₂ gradient [P(a-ET)co₂] and physiological dead space (V_D/V_T) were recorded between 2 minutes before and 5 minutes after insertion of PMMA in 12 dogs. A significant decrease in platelet count occurred in both groups of dogs. Decreases in arterial pO₂ (Pao₂), arterial/alveolar oxygen tension ratio (Pao₂/PAo₂), and percent O₂ saturation of hemoglobin in arterial blood (Sao₂) were not statistically significant. No significant differences could be detected between data obtained from both groups of dogs. An increase in femoral intramedullary pressure caused by the insertion of PMMA and subsequent pulmonary microembolism by medullary contents has been considered the most likely cause for changes in pulmonary function. The lack of statistically significant differences in cardiopulmonary variables and platelet count between the two groups of dogs could have been related to inefficient pressure reduction by the method used.