Lifetime cost of surgical treatment for canine hip osteoarthritis is less than conservative management in dogs under eight years of age.

OBJECTIVE: To determine the lifetime cost of 3 treatments for canine hip osteoarthritis: (1) conservative management, (2) femoral head and neck excision (FHNE), or (3) total hip replacement. We hypothesized that FHNE would be the least expensive treatment at all ages. SAMPLE: Cost estimates from 11 private and academic referral centers from 8 randomly chosen cities across the US. METHODS: Costs of surgeries were collected from practices in 8 US cities. The literature was used to determine expected postoperative costs. For conservative management, costs of pain medications and diet were obtained by use of online pharmacies. A 4.5% inflation adjustment was used for costs in subsequent years. RESULTS: For a dog aged 1 to 7 years, FHNE had the lowest lifetime cost. Total hip replacement had the second lowest cost until age 4, after which conservative management was lower. For dogs > 8 years, conservative management was the most cost-effective. CLINICAL RELEVANCE: For dogs presenting with clinical signs at or under 1 year of age, the perceived benefits of total hip replacement may not be financially prohibitive if lifetime cost of care is considered. Femoral head and neck excision was also less expensive than long-term conservative management. This can help veterinarians inform owners on costs of treatments over the lifetime of their pet. This type of analysis is limited to financial costs alone and does not account for differences in outcomes, as these are not well established. It should be expanded in the future as better data on outcomes and impacts of care become available.

Preclosure povidone-iodine lavage in total hip replacement surgery: Infection outcomes and cost-benefit analysis.

OBJECTIVE: To report the outcomes and cost-benefit analysis of preclosure povidone-iodine lavage (PrePIL) used to reduce the risk of infection following total hip replacement (THR) surgery. STUDY DESIGN: Retrospective study. ANIMALS: One thousand six hundred ninety-nine dogs, 17 cats. METHODS: The medical records of 2213 consecutive THR cases were reviewed to determine the incidence of infection. The last 102 were treated with PrePIL using a commercially sourced 0.035% povidone-iodine solution. Postoperative infection rates were compared. A cost-benefit analysis was used to calculate if a PrePIL protocol is economically feasible. RESULTS: Twenty-one THRs out of 2111 (0.99%) that did not have PrePIL developed infection. Infection occurred in none of the 102 PrePIL cases. Cost analysis revealed a PrePIL break-even cost at $49.74 and a break-even infection rate of 0.949%. No complications were identified related to the use of PrePIL. CONCLUSION: Preclosure povidone-iodine lavage appeared to be efficacious in lowering THR infection rates, and it appeared to be safe for this use based on our 102 consecutive cases. The cost of the PrePIL was minimal compared to the overall cost to resolve THR infection and the potential effect on hip function prognosis. The math formulas developed can be used by surgeons to calculate cost effectiveness and break-even cost based on their THR infection rate, and to compare to the cost of a THR revision and infection resolution. CLINICAL SIGNIFICANCE: At current costs, PrePIL can be used in 2415 THR cases at a similar cost of a single revision surgery and resolution of a periprosthetic infection.

Greater trochanter morphology and association with patient demographics, surgical factors, and post-operative stem position: a retrospective assessment of 150 cementless THRs in 135 dogs.

BACKGROUND: Total hip replacement (THR) in the gold standard surgical treatment for the canine hip. While it has been shown that greater trochanter morphology affects post-operative cementless stem position in humans, trochanter morphology and the effect on cementless stem position has not been extensively evaluated in dogs. The objective of this study was to classify greater trochanter morphology and identify potential associations between trochanter morphology and patient demographics, femoral canal geometry, surgical time, technique modifications, and post-operative stem position in client-owned dogs undergoing cementless THR. RESULTS: In this retrospective study, medical records and radiographs of 135 dogs undergoing 150 cementless total hip replacements from 2013 to 2020 were included. Trochanters were classified in the frontal plane using an ordinal grading system adapted from human THR. A Grade I trochanter denoted a trochanter positioned lateral to the periosteal surface of the lateral femoral cortex, whereas a Grade IV trochanter denoted a trochanter positioned medial to the anatomic axis of the femur. Associations between trochanter grade and other variables were examined using ANOVA, Kruskall-Wallis, or chi-squared tests. Significance was assumed at P ≤ .05. Trochanters were classified as follows: Grade I (44/150, 29.3%), Grade II (56/150, 37.4%), Grade III (44/150, 29.3%), Grade IV (6/150, 4.0%). Grade IV trochanters had lower anatomic lateral distal femoral angle (aLDFA; 91.0 ± 6.2°), angle of inclination (117.7 ± 10.5°), and canal flare index (1.53 ± 0.27). When compared to all groups, Grade IV trochanters were associated with longer surgical times (Grade IV: 227.0 ± 34.2 min; all grades: 183.2 ± 32.9 min) and technique modifications (Grade IV: 83.3%; all grades: 18%). Grade I trochanters had stems placed in valgus (- 1.8 ± 2.33°), whereas Grade II (0.52 ± 2.36°), III (0.77 ± 2.58°), and IV (0.67 ± 2.73°) trochanters exhibited varus stems. Depth of stem insertion was greater (11.2 ± 4.2 mm) for Grade IV trochanters. CONCLUSIONS: Trochanter grade was associated with post-operative stem alignment and translation in the frontal plane. Grade IV trochanters were associated with altered femoral geometry, increased surgical time, technique modifications, and stem insertion depth. Pre-operative greater trochanter classification may prove useful in identifying cases requiring prolonged surgical times or technique modifications.

Short-Term Clinical Assessment of Hip Hemi-Arthroplasty in 11 Dogs.

OBJECTIVE: The aim of this study was to assess the short-term clinical outcome in dogs following a hip hemi-arthroplasty for the treatment of primary pathological disorders of the hip and as a salvage procedure following failure of the cup component of a total hip replacement. STUDY DESIGN: Medical records of dogs that had a unilateral hip hemi-arthroplasty performed between 2015 and 2020 were reviewed. Data collected included follow-up orthopaedic examinations performed at 0, 2, 8 and 52 weeks postoperatively, pelvic radiography at 0, 8 and 52 weeks postoperatively and an owner questionnaire (Helsinki chronic pain index [HCPI]). RESULTS: Eleven unilateral hip hemi-arthroplasty procedures were identified. The median age at time of surgery was 3.6 years (8 months-10 years) and the median follow-up time was 13 months (range: 2 months-3 years). The HCPI for all dogs at follow-up was median 8 ± 7.30 (range: 5-25). Total HCPI was < 12 for 7/10 dogs and ≥ 12 for 3 dogs. Pelvic radiographs at 1 year confirmed osteointergration of the femoral stem implant and no evidence of implant subsidence or progression of osteoarthritis. However, there was some evidence of mild lucency of the acetabular bed around the prosthetic femoral head and mild peri-acetabular sclerosis in four cases. CONCLUSION: Hip hemi-arthroplasty provides a clinically acceptable treatment for disabling disease of the coxofemoral joint with 10/11 patients achieving acceptable short-term clinical function. Long-term assessment of the hip hemi-arthroplasty and comparison with total hip replacement is indicated.

Radiographic and Biomechanical Assessment of Three Implant Designs for Canine Cementless Total Hip Replacement.

OBJECTIVE: The aim of this study was to evaluate the relationship between radiographic fit/fill measurements and biomechanical performance of three canine cementless total hip implant designs using an in vitro biomechanical testing protocol that replicates compression and torsion. STUDY DESIGN: Eighteen (six/group) canine cadaveric femurs were implanted with one of three cementless total hip implant designs: (1) collarless, (2) collared or (3) lateral bolt stems. Femoral length, canal flare index (CFI), canal fill, stem fit, stem level and stem angle were measured as independent variables. Biomechanical performance was tested using physiological, non-destructive gait loading (loading protocols) and destructive testing (failure protocols). RESULTS: During loading protocols, compressive stiffness was influenced by stem level (p < 0.05) and torsional stiffness was influenced by stem level and CFI for collarless stems (p < 0.05). During failure protocols, peak load was influenced by mediolateral (ML) stem angle (p < 0.05) and CFI (p < 0.01) for collarless stems and CFI for lateral bolt stems (p < 0.05). Peak torque was influenced by ML stem angle, craniocaudal stem angle and CFI for collarless stems (p < 0.05) and average ML fill for collared stems (p < 0.05). CONCLUSION: Biomechanical performance of collarless stems in cementless hip arthroplasty is more impacted by radiographic fit/fill than lateral bolt and collared stems. As a result, collarless stems may be more dependent on preoperative fit and intraoperative precision.

Measurement of Acetabular Component Position in Total Hip Arthroplasty in Dogs: Comparison of a Radio-Opaque Cup Position Assessment Device Using Fluoroscopy with CT Assessment and Direct Measurement.

OBJECTIVES: The aim of this study was to compare measurements of angle of lateral opening (ALO) and version determined using a radioopaque cup position assessment device imaged with fluoroscopy to measurements obtained by CT and direct measurement in a cadaveric model. Our null hypothesis was that there would not be any difference in the angles measured by the techniques. METHODS: Six cadavers were implanted with BFX acetabular components. The CPAD was placed and images were obtained with fluoroscopy. Measurements were obtained from the radiopaque marker bars on the CPAD device, and version and ALO were calculated. The ALO and version were determined by CT and DM. Comparisons were made using a two-way analysis of variance and a generalized linear model procedure analysis. RESULTS: There were no significant differences between the measurements for ALO (p = 0.275) or version (p = 0.226). Correlation between methods was 0.948 and 0.951 for ALO and version, respectively. The mean difference (standard deviation [SD], and 95% confidence interval [CI]) for ALO were: CT versus CPAD 1.85 degrees (± 2.32 degrees [-2.99-3.31]), CT versus DM 1.96 degrees (± 1.99 degrees [-2.2-4.27]), CPAD versus DM1.74 degrees (±2.21 degrees [-1.13 and 5.24]). The mean difference (SD [CI]) for version was CT versus CPAD 2.86 degrees (±1.56 degrees [ -2.63-1.69]), CT versus DM 1.10 degrees (±1.42 degrees [-1.57-2.09]), CPAD versus DM 1.07 degrees (±0.76 degrees [0.13-2.09]). CLINICAL RELEVANCE: The results demonstrate that intraoperative imaging in cadaveric specimens with the CPAD is an accurate method to determine ALO and version of the acetabular component.

Assessment of acetabular cup positioning from a lateral radiographic projection after total hip replacement.

OBJECTIVE: To demonstrate first that a ventrodorsal radiographic (VDR) projection is inadequate for obtaining accurate acetabular cup position (ACP) measurements after total hip replacement (THR), and second to validate use of the lateral radiographic (LR) projection to measure ACP. STUDY DESIGN: In vitro study. METHODS: Eleven VDRs were obtained after insertion of a cup into the acetabulum of a Sawbones pelvis fixed at an approximated angle. For each VDR, the pelvis was placed in varying degrees of craniocaudal pelvic tilt (CCPT). Fifteen LRs were obtained of a Sawbones pelvis with varying ACPs. Five blinded observers made previously described measurements of ACP on each VDR and angle of lateral opening (ALO) and coronal retroversion (CR) on each LR. RESULTS: An almost perfect level of agreement was observed between 5 observers for the repeatability of both VDR and LR measurements. When varying degrees of CCPT were introduced, there was no agreement in the measurements of ACP from VDRs. In all cases, and at all ACPs, measurements taken from LRs were in agreement. CONCLUSION: Undetectable CCPT causes significant variability in ACP measurements on VDRs predisposing postoperative radiographic measurements to inaccuracy. Measurements obtained from an LR of CR and ALO are accurate and consistent between observers and it should be used to measure ACP. The VDR should be performed to assess bone and implant integrity but not to obtain measurements of ACP because of CCPT causing measurements to be unreliable. Measurements of ACP obtained from an LR in conjunction with femoral anteversion may allow for investigation of the influence of ACP on coxofemoral joint luxation after THR.

Complications and owner assessment of canine total hip replacement: a multicenter internet based survey.

OBJECTIVE: To assess the variables associated with the complications of total hip replacement (THR) and report owner-assessed outcomes, through surgeon-based registration of cases via an online database, informed owner consent, and prospective outcomes assessment using a client-administered clinical metrology instrument. STUDY DESIGN: Prospective case series ANIMALS: Dogs (n = 170) METHODS: Entries into the British Veterinary Orthopaedic Association-Canine Hip Registry (BVOA-CHR) between January 2010 and August 2011 were reviewed. Variables evaluated included dog age, body weight, breed, and indication for THR and prosthesis. Associations between each variable and the incidence of complications were assessed using logistic regression. Additionally, an on-line, owner-administered outcomes assessment questionnaire (modified from the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire) was used to collect data from owners. RESULTS: One hundred and seventy cases met the inclusion criteria. Surgical indications included hip dysplasia and coxofemoral osteoarthritis (n = 150), Legg-Calves-Perthes disease (7), coxofemoral luxation (6), fracture (4), slipped capital physis (2), and femoral head and neck ostectomy revision (1). Surgical implants were from 4 systems. The incidence of surgeon-reported complication was 9.4%. No significant association was identified between weight, age, sex, breed, indication for THR, surgical technique and prosthesis, and the incidence of complications. In 82% of the cases, owners described their satisfaction with the outcome of THR as "very good" and a total of 20% complication rate was reported. There was a statistically significant improvement in owner-assessed questionnaire score before and after THR (P < .001). CONCLUSIONS: The BVOA-CHR offers a novel framework for the prospective studies on THR and on a national/international scale. Initial complication rates from the BVOA-CHR are similar to previous studies.

Total hip arthroplasty outcomes assessment using functional and radiographic scores to compare canine systems.

A retrospective multi-centre study was carried out in order to compare outcomes between cemented and uncemented total hip arthoplasties (THA). A quantitative orthopaedic outcome assessment scoring system was devised in order to relate functional outcome to a numerical score, to allow comparison between treatments and amongst centres. The system combined a radiographic score and a clinical score. Lower scores reflect better outcomes than higher scores. Consecutive cases of THA were included from two specialist practices between July 2002 and December 2005. The study included 46 THA patients (22 uncemented THA followed for 8.3 +/- 4.7M and 24 cemented THA for 26.0 +/- 15.7M) with a mean age of 4.4 +/- 3.3 years at surgery. Multi-variable linear and logistical regression analyses were performed with adjustments for age at surgery, surgeon, follow-up time, uni- versus bilateral disease, gender and body weight. The differences between treatment groups in terms of functional scores or total scores were not significant (p > 0.05). Radiographic scores were different between treatment groups. However, these scores were usually assessed within two months of surgery and proved unreliable predictors of functional outcome (p > 0.05). The findings reflect relatively short-term follow-up, especially for the uncemented group, and do not include clinician-derived measures, such as goniometry and thigh circumference. Longer-term follow-up for the radiographic assessments is essential. A prospective study including the clinician-derived outcomes needs to be performed in order to validate the outcome instrument in its modified form.

The effects of femur and implant position on the radiographic assessment of total hip femoral implants in dogs.

OBJECTIVE: To determine the effect of femur positioning and femoral implant placement on the radiographic assessment of total hip femoral implants in dogs. STUDY DESIGN: Cadaveric study. ANIMALS: Five canine femurs. METHODS: Five canine femurs were fitted with total hip implants, in predetermined locations, postmortem. Each femur was moved through a defined range of motion and radiographed at specific intervals. Radiographs were then digitized, and implant position was measured using previously described methods. Regression analysis was conducted to determine whether varied femoral position resulted in a consistent (linear) pattern of change in the value of each particular measurement. RESULTS: Change in the position of the femur relative to the film cassette caused significant variation in the perceived position of the implant. The placement of the implant within the femur determined which measurements were affected and to what degree. CONCLUSIONS: The information obtained from standard clinical radiographs and conventional methods of quantitative analysis does not consistently provide an accurate assessment of the placement of the femoral implant within the femoral canal. Such data cannot be used to correlate implant position with implant failure.

Owner assessment of the outcome of total hip arthroplasty in dogs.

OBJECTIVE: To evaluate owners' perceptions of the outcomes of dogs that have undergone total hip arthroplasty (THA). DESIGN: Survey. SAMPLE POPULATION: Owners of 145 dogs that had undergone THA. PROCEDURE: Surveys were mailed to owners of 353 dogs that underwent THA between 1982 and 1996. Owners were asked to answer multiple-choice questions and provide written comments. RESULTS: The response rate was 41%. For owners who responded to the survey, time from surgery to completion of the questionnaire ranged from 6 months to 11 years. Overall, 122 respondents (84.1%) rated results of THA in their dog as excellent or good. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that owners are generally satisfied with the results of THA in their dogs.

In vitro evaluation of antibiotic elution from polymethylmethacrylate (PMMA) and mechanical assessment of antibiotic-PMMA composites.

OBJECTIVE: To determine whether different methods of sterilization of antibiotic vials or the heat of polymerization altered the antimicrobial activity or mechanical properties of antibiotic/polymethylmethacrylate (PMMA) composites when compared to antibiotic-free PMMA. STUDY DESIGN: In vitro study. METHODS: Steam-sterilized, gas-sterilized, and non-sterilized 1 gram vials of cefazolin and injectable gentamicin sulfate (high and low doses) were mixed with PMMA to prepare composites for antibiotic elution evaluation, compression, and elongation testing. Blocks of PMMA that contained antibiotic were assayed for antibacterial activity using an agar gel diffusion method or were placed in phosphate buffered saline (PBS) to assess elution of antibiotic. Phosphate buffered saline samples from steam-sterilized cefazolin and high-dose gentamicin groups were assayed on days 1, 2, 5, and 9 for cefazolin or gentamicin concentration by high-pressure liquid chromatography or fluorescent polarization immunoassay, respectively. RESULTS: PMMA blocks containing antibiotic inhibited bacterial growth of Staphylococcus aureus 25923 for an average of 9 days. Cefazolin and gentamicin concentration in PBS decreased dramatically after the first 24 hours, but remained above minimum inhibitory concentration (MIC) throughout the experiment for all groups except low-dose gentamicin. Compressive strength of plugs made from plain cement and plugs made from PMMA mixed with untreated and steam-sterilized cefazolin was similar, but was significantly different from the other groups. There appeared to be an inverse relationship between compressive strength and elongation. CONCLUSION: PMMA/antibiotic composites inhibited bacterial growth for 7 to 10 days. Compressive strength was affected by different additions of antibiotic. CLINICAL RELEVANCE: Bacteria introduced during a surgical procedure may be inhibited by elution of antibiotic from PMMA at the time of contamination.