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.     

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.     

Total Hip Prosthesis for Revision of Unsuccessful Excision Arthroplasty

Two types of total hip prostheses were implanted in three dogs that had been previously treated by excision arthroplasty, two for degenerative joint disease secondary to hip dysplasia and one for removal of a fractured femoral neck. Complications occurred in one case when the femoral shaft was split during the reaming process for implantation of the prosthesis and at three weeks after surgery when an oblique fracture of the distal femur occurred. Both complications were treated successfully. The time since surgery varied between eight and 18 months. All three dogs had excellent functional results evidenced by increased joint mobility and freedom from pain.     

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.     

Biomechanical Evaluation of Acetabular Cup Implantation in Cementless Total Hip Arthroplasty

Objective: To report biomechanical properties of the Biologic Fixation System (BFX) acetabular cup impacted into a normal canine pelvis and to compare the effect of implant positioned to and beyond the medial acetabular wall. Study Design: In vitro cadaveric study. Animals: Hemipelves of mature, large‐breed dogs (n=6). Methods: For each dog, 1 hemipelvis was reamed to the depth of the acetabular wall (group A) and 1 was reamed an additional 6 mm after penetration of the medial cortex of the acetabulum (group B). The hemipelves were implanted with acetabular cups and loaded in compression through a matching femoral prosthetic component until failure. Specimen stiffness, and failure displacement, load, and energy were determined from load and displacement data and results between groups compared with a paired t‐test. Results: Mean failure load was greater in group A (3812 ± 391 N) than group B (2924 ± 316 N; P<.014). No other differences (P>.05) were observed between groups. Bone fracture (n=5) and cup displacement (1) occurred in group A whereas in group B there were 3 fractures and 3 cup displacements. Conclusions: Although medial placement of the BFX cup affected compressive failure loads, failure loads for both groups exceeded normal physiologic loads. Clinical Relevance: Medial positioning of the acetabular cup does not appear to compromise acetabular implant‐pelvic stability under normal physiologic loads. Because arthroplasty candidates often have abnormal acetabular architecture, mechanical properties of the cup placed in acetabula without a dorsal rim should be investigated.     

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.     

Vascular and Morphologic Changes in Canine Femora after Uncemented Hip Arthroplasty

The effects on femoral remodeling of medullary reaming and insertion of a porous endopros-thesis in uncemented hip arthroplasty (UHA) were measured. A unilateral hip hemiarthroplasty (HA) was performed in 12 dogs, with six dogs receiving full-sized and six dogs receiving undersized femoral endoprostheses. A prosthetic head and neck, or acetabular cup, was not implanted. A control group of six dogs underwent femoral head and neck excision (FHNE) only. All dogs were killed 4 weeks after the surgical procedure. Porosity, vascularity, and bone formation were quantified in each femur of the dogs that had been operated on and in each femur of two unoperated dogs. Full-sized did not differ from undersized HA bones in vascularity, porosity, or bone formation. Femurs in which hemiarthroplasties had been performed (full-sized and undersized) had a three-fold increase in porosity, vascularity, and bone formation compared to the contralateral and the FHNE femurs. Changes in porosity and vascularity were greatest (p < .05) at the metaphyseal level and in the medial and caudal quadrants. There was a strong correlation (R² 0.77 to 0.93, and p − .0001) between the increase in porosity and vascularity. These results support the hypothesis that medullary reaming followed by uncemented prosthetic stem implantation contribute to remodeling of the proximal portion of the femur after UHA.     

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.     

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.     

Subsidence of an Uncemented Canine Femoral Stem

Factors contributing to subsidence were analyzed by radiographic evaluation and mechanical testing of 36 canine cadaver femora during and after insertion of an uncemented porous-coated femoral stem and by radiographic evaluation of 35 canine total hip arthroplasties. Mean percentage of canal fill in immediate postoperative radiographs, and percentage of canal fill at midimplant and distal implant locations, were accurate predictors of subsidence. Force required to implant the femoral stem was strongly correlated with force required for implant subsidence. Femoral morphology and percentage of canal fill at the middle and distal sites were accurate predictors of subsidence. Implants in femora with a stovepipe morphology (canal flare index ≤ 1.8) were six times more likely to subside than implants in femora that had a normal appearance (canal flare index 1.8 to 2.5), and 72 times more likely to subside than implants in champagne-fluted femora (canal flare index ≥ 2.5). Femora with more than 85% mean, middle, or distal canal fill were less likely to subside.     

Cemented Total Knee Replacement in 24 Dogs: Surgical Technique, Clinical Results, and Complications

Objective— To characterize the performance of cemented total knee replacement (TKR) in dogs.
Study Design— Preclinical research study.
Animals— Skeletally mature, male Hounds (25–30 kg; n=24) with no preexisting joint pathology.
Methods— Dogs had unilateral cemented TKR and were evaluated at 6, 12, 26, or 52 weeks (6 dogs/time point) by radiography, bone density analysis, visual gait assessment, and direct measurement of thigh circumference and stifle joint range of motion as indicators of functional recovery. At study end, the stability of the cemented tibial component was determined by destructive mechanical testing.
Results— Joint stability was excellent in 16 dogs (67%) and good in 8 dogs. None of the tibial components had evidence of migration or periprosthetic osteolysis whereas 1 femoral component was loose at 52 weeks. There was an early and significant decrease in tibial bone density, likely because of disuse of the operated limb. Dogs returned to full activity by 12 weeks. The tibial cement–bone interface maintained its strength over 52 weeks.
Conclusions— Cement provides stable fixation of the tibial component in canine TKR.
Clinical Relevance— Cemented TKR yields adequate clinical function and stifle joint excursion in the dog. Clinical studies are needed to determine the long-term fate of cemented TKR implants, to assess the influence of implant design on implant fixation and wear, and to obtain objective functional data.     

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.     

Pharmacokinetic Disposition of Cefazolin in Serum and Tissue during Canine Total Hip Replacement

Intraoperative cefazolin concentrations were measured in serum, joint capsule, cancellous bone of the acetabulum, and proximal cancellous bone of the femur in 15 dogs undergoing total hip replacement. Cefazolin (22 mg/kg intravenously [IV]) was administered every hour for three doses. The mean peak serum concentrations (+/- SEM) were 387.79 +/- 27.56 micrograms/mL, 521.71 +/- 28.00 micrograms/mL, and 542.20 +/- 30.91 micrograms/mL, respectively. Mean serum concentrations just before administration of doses 2 and 3 were 51.77 +/- 2.39 micrograms/mL, and 64.84 +/- 3.46 micrograms/mL, respectively. The mean cefazolin concentrations in the joint capsule, cancellous bone of the acetabulum, and cancellous bone of the femur were 34.71 +/- 2.50 micrograms/g, 28.70 +/- 7.40 micrograms/g, and 36.20 +/- 3.80 micrograms/g, respectively. The minimum inhibitory concentration of cefazolin for 90% of the common contaminants (MIC90) in this clinic is less than or equal to 2 micrograms/mL or per gram of tissue. Serum concentrations never fell below 15 times the MIC90 (lowest trough, 35.93 micrograms/mL), and the lowest tissue concentration (6.57 micrograms/mL in cancellous bone from the acetabulum) was still more than 3 times the MIC90. The mean tissue concentration was 15 times the MIC90.     

Mandibular Condylectomy Technique and Results in Normal Horses

A technique of mandibular condylectomy and menisectomy is described. Unilateral condylectomy and menisectomy were performed in two horses, and two horses were treated by bilateral condylectomy and unilateral meniscectomy. Minor temporary alterations in mastication occurred following unilateral condylectomy; more severe and longer lasting abnormalities of prehension and mastication occurred following bilateral condylectomy. Malocclusion occurred in all horses following surgery but was only clinically significant in one horse that developed occlusion of the lower incisor teeth 3 mm caudal to the upper incisor teeth following bilateral condylectomy. Maximal mouth opening was normal following unilateral condylectomy and increased following bilateral condylectomy, both immediately following surgery and after 16 weeks. Maximal lateral deviation of the mandible was increased immediately following unilateral and bilateral condylectomy; 16 weeks following surgery one joint had increased, and two had normal and three had decreased maximal lateral deviations. On radiographic, gross, and histological evaluation, the condylectomy sites underwent remodelling and bony proliferation to produce "pseudo" condyles. At necropsy, 16 weeks following surgery, five of the six operated temporomandibular joints contained fibrous tissue with single or multiple cavities lined by synoviocytes. The nonoperated temporomandibular joints were normal. Functional use of the mandible was good in three horses; the fourth horse developed significant malocclusion and had satisfactory function following bilateral condylectomy.     

Revision of Cemented Total Hip Arthroplasty with Cementless Components in Three Dogs

Objective— To report revision of cemented total hip arthroplasty failure with cementless components in 3 dogs.
Study Design— Clinical case reports.
Animals— Dogs with total hip arthroplasty failure (n=3).
Methods— Cementless total hip arthroplasty revision was performed in 3 dogs with previously cemented femoral and acetabular components. All dogs required revision of the femoral component and 1 dog also required revision of the acetabular component.
Results— Revisions resulted in a stable functional prosthesis with successful bone integration.
Conclusions— Use of cementless components may be a viable option for revision of loosened cemented prosthesis after explantation of failed cemented canine total hip replacements.
Clinical Relevance— Failed canine-cemented total hip arthroplasties can be successfully revised with cementless components.     

Implantation of temperature loggers in 100 Danish dairy calves: surgical procedure and follow-up.

One hundred Danish dairy calves had temperature loggers implanted subcutaneously on the neck. Post-operatively, the calves were given a single antibiotic treatment, and tissue reactions were assessed on 6 post-operative visits. After approximately 5 months, the loggers were removed and material submitted for histologic examination. This paper presents 1) the surgical procedure, 2) the prevalence of tissue reaction at the post-operative visits, 3) the degree of implant recovery, 4) the results of histopathologic examinations, 5) an evaluation of age at implantation or veterinary practitioner as risk factors for tissue reaction and missing implant recovery 5 months after implantation, and 6) evaluation of tissue reaction as a risk factor for lack of recovery 5 months after implantation. The implant was rejected on 7 calves (7%). Additionally, 5 calves (5%) had the temperature logger removed because of presence of an abcess. No migration of the temperature loggers were observed. The results of a repeated measures analysis and the histopathological findings indicate that contamination during the surgery resulted in inflammation and abcess formation. It is recommended that in the presence of an abcess, the temperature logger should be removed.     

奶牛粪便检测试验

试验采用单因素重复试验设计,按泌乳天数分为11个组.每组选择有代表性的6头健康荷斯坦初产奶牛粪样进行检测.检测项目包括粪便颜色、高度、pH值、稠度分值、谷物或秸秆颗粒大小.试验数据显示,不同泌乳阶段乳牛粪便稠度分值基本为正常值,粪便干物质含量基本在20%以上,粪便中玉米颗粒较少,秸秆相对较多.