Evaluation of a stepped, fixed-height magnification marker stand for use with a 100-mm marker in implant sizing prediction in 52 total hip replacement procedures in dogs.

OBJECTIVE: To describe the use of a 100-millimeter marker placed on a stepped, fixed-height magnification marker stand to measure radiographic magnification on accuracy of implant size prediction when used for canine total hip replacement (THR) implant size selection. STUDY DESIGN: Retrospective study. ANIMALS: Fifty-two hips in 45 dogs. METHODS: This study evaluated 52 consecutive canine total hip replacement surgery pre-planning procedures involving 45 dogs with 7 undergoing staged bilateral THRs. Data collected included demographic information, measured radiographic magnification for magnification recalibration, implant size prediction of the cups (52) and the stems (52) based on digital templates superimposed on digital radiographs, and the actual implant sizes used during surgery. RESULTS: Use of the magnification marker stand (MMS) and template application system resulted in an accurate prediction of implant size of 98/104 implants (94.2%) implants. CONCLUSION: A 100-mm marker placed on a magnification marker stand was a viable method to measure and recalibrate for magnification on digital radiographs during the template process to predict the THR implant sizes that should be available when the surgery begins. CLINICAL SIGNIFICANCE: This stepped calibration marker stand is helpful in determination of an accurate preoperative THR implant size prediction, lowering implant stock thresholds, operating time, and associated complications. Additionally, the radiographic documentation of the marker's step height allows for indefinite confirmation of the magnification marker height used and for accurate repeatability for all follow-up imaging examinations and contralateral procedure planning.

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.

Tibial Tuberosity Transposition Fixation with a Locking Plate during Medial Patellar Luxation Surgery: An Ex Vivo Mechanical Study.

OBJECTIVES: The purpose of this study was to compare the load at failure, stiffness and mode of failure between three types of tibial tuberosity transposition fixation techniques: (a) pin and figure-8 tension band wire (Pin-TBW), (b) locking plate with pin and a tension band wire (Plate-Pin-TBW) and (c) locking plate with a pin (Plate-Pin). METHODS: Six pairs of raccoon dog cadaveric tibiae were tested in Phase I Pin-TBW versus Plate-Pin-TBW and seven pairs in Phase II Plate-Pin-TBW versus Plate-Pin. One limb of each pair was randomly assigned to one of two groups for each phase. A tensile force was applied to the patellar ligament until construct failure. RESULTS: Pin-TBW (342N ± 54.7N) failed at a lower load than Plate-Pin-TBW (469N ± 77.3N), p = 0.00748, with all Pin-TBW failing by fracture and the majority of Plate-Pin-TBW failing by rupture of patellar ligament. Pin-TBW group Phase I, normalized with Plate-Pin-TBW Phase I, failed at a lower load than Plate-Pin group Phase II, normalized with Plate-Pin-TBW Phase II, p = 0.00467. There was no significant difference in mean load at failure, stiffness or mode at failure between the groups in the Phase II study. CLINICAL SIGNIFICANCE: Although ex vivo mechanical testing does not replicate the postoperative live dog or cat, these results demonstrate lower construct strength of the Pin-TBW construct compared with the Plate-Pin construct in the raccoon dog cadaver model.

Outcome of canine cementless collared stem total hip replacement with proximal femoral periprosthetic cerclage application: 184 consecutive cases.

OBJECTIVE: To report outcomes of cementless collared stem total hip replacement (THR) with proximal femoral periprosthetic cerclage application in dogs. STUDY DESIGN: Retrospective case series. ANIMALS: Client-owned dogs (n = 150) with THR (n = 184). METHODS: Serial postoperative radiographs and medical records of dogs that underwent consecutive index cementless THR, with a single full cerclage wire placed distal to the femoral neck osteotomy line and proximal to the lesser trochanter, were reviewed for intraoperative and postoperative complications. RESULTS: No proximal femoral fractures occurred. No complications associated with the use of the cerclage wire were encountered. A fissure (n = 1) or fractures (n = 2) occurred near the tip of the femoral stem in three cases postoperatively. All three cases required plate and screw fixation. All dogs returned to subjectively normal function at home and all owners were satisfied with the outcome. CONCLUSION: A single full cerclage wire may minimize the risk of a proximal femur fracture following cementless collared stem total hip replacement in dogs. No complications were encountered with the cerclage wire. CLINICAL SIGNIFICANCE: Application of a cerclage wire is a simple and economically feasible procedure that requires minimal additional instrumentation, takes little time, and may decrease the risk of proximal femur fractures after cementless press-fit THR.

Orthopedic and ultrasonographic examination findings in 128 shoulders of 64 ultra-endurance Alaskan sled dogs.

OBJECTIVE: To determine the location and periarticular shoulder-muscle-abnormalities detected via orthopedic examinations and ultrasonography in ultra-endurance Alaskan sled-dogs, returned from an ultra-endurance sled-dog-race prior to finishing it. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Sixty-four dogs (128 shoulders). METHODS: Dogs were classified based on clinical evidence of shoulder pain (SP versus control). Orthopedic examination findings, shoulder-abduction-angles (SAA; before- and during-anesthesia), and ultrasonographic findings were recorded. Relationships between orthopedic and ultrasonographic abnormalities were compared. RESULTS: Pain was elicited on 55/128 shoulders; 73 shoulders were pain-free. The most common painful structures included the biceps-tendon (BT; 30%), triceps-muscle (28%), and infraspinatus-muscle (25%). SAA ranged between 25° and 75° among groups, including pain-free shoulders in dogs without lameness. SAA was greater when dogs were anesthetized (46.3° ± 14.0° vs. 47.8° ± 12.0°; p = .03), especially in SP (mean increase of 3.49° ± 8.85°) compared to control (0.03° ± 7.71°, p = .009). Overall, 103 ultrasonographic abnormalities were detected (SP: 44; control: 59). The most common ultrasonographic abnormality was fluid surrounding the biceps tendon, similarly distributed between groups (SP: 39/44; control: 57/59). Most chronic ultrasonographic abnormalities affected the BT (15/103 abnormalities). No associations were detected between ultrasonographic abnormalities and clinical findings. CONCLUSION: Shoulder abduction varied greatly and reached up to 75° in normal joints. Ultrasonographic shoulder-muscle abnormalities were common but did not seem associated with clinical findings. CLINICAL SIGNIFICANCE: Interpretation of shoulder abduction warrants caution, and the presence of fluid around the BT may reflect a physiologic adaptation to racing, rather than a pathologic change in ultra-endurance Alaskan sled-dogs.

Idiopathic arteriopathy-induced focal osteonecrosis of the femoral head in a young dog.

CASE DESCRIPTION: A 15-month-old 6.5-kg (14.3-lb) castrated male mixed-breed dog was evaluated because of a 4-month history of progressive intermittent non-weight-bearing lameness of the left pelvic limb. CLINICAL FINDINGS: Orthogonal radiography of the hip joints revealed a 4-mm atypical radiolucent lesion on the distal caudomedial aspect of the left femoral head and a disproportionately large-diameter femoral medullary canal with a low canal flare index. Prolonged unresponsiveness to medical management and progressive enlargement of the lesion prompted the recommendation for total hip replacement (THR). TREATMENT AND OUTCOME: THR was performed to restore pain-free function of the left pelvic limb and normal activity. A circular osteochondral flap was grossly evident on the femoral head. Histopathologic findings for this portion of the bone indicated an arteriopathy-induced focal subchondral osteonecrosis that had resulted in articular surface collapse. The noted idiopathic arteriopathy had disrupted the normal blood supply to the affected area. On reexamination and radiographic evaluation 13 months after THR, the dog appeared to have pain-free function of the affected limb and had returned to normal activity with no reported complications or problems. CLINICAL RELEVANCE: To the authors' knowledge, this report represented the first description of arteriopathy-induced focal osteonecrosis of the caudomedial aspect of the femoral head and its successful treatment in a young dog. This type of lesion may more commonly be the cause of hip joint osteoarthritis in young dogs than previously recognized because establishing a definitive diagnosis requires early recognition and histologic evaluation before advanced degenerative changes develop that obscure the underlying etiology.

Total hip replacement in dogs with contralateral pelvic limb amputation: A retrospective evaluation of 13 cases.

OBJECTIVE: To report the clinical characteristics, surgical management, and medium-term outcomes of total hip replacement (THR) performed in dogs with previous contralateral pelvic limb amputation. ANIMALS: Thirteen client-owned dogs. STUDY DESIGN: Multi-institutional retrospective clinical study. METHODS: Data recorded from medical records included signalment, indication for amputation and THR, and surgical complications. Implant positioning and complications were assessed on radiographs. Clinical outcomes were evaluated during follow-up examinations by one of the authors and through a mobility- and lifestyle-based questionnaire completed by owners. RESULTS: All 13 dogs had satisfactory clinical results at follow-up a median of 3 months (range, 2-36) after THR. No postoperative luxation was recorded. Four dogs had minor complications that did not require additional treatment. The only major complication was one failure of osseointegration of a cementless acetabular cup, and it was successfully revised. CONCLUSION: Total hip replacement resulted in satisfactory clinical results and acceptable morbidity in this population. CLINICAL SIGNIFICANCE: Total hip replacement should be considered in dogs with severe coxofemoral joint disease and contralateral pelvic limb amputation.

Polar gap after cementless total hip replacement in dogs.

OBJECTIVE: To determine the incidence and outcomes of total hip replacements with polar gaps in dogs. STUDY DESIGN: Retrospective case series. ANIMALS: One hundred fifty-five client-owned dogs. METHODS: Serial postoperative and follow-up digital orthogonal radiographs of 200 hips in 155 dogs that underwent consecutive index total hip replacement (THR) were examined for the presence of polar gaps. Length and depth of polar gaps were measured and monitored on serial radiographs. RESULTS: A polar gap was identified in at least 1 zone in 136 (68%) of the ventral-dorsal (VD) radiographs and in 80 (40%) of the lateral radiographs obtained immediately after surgery. Gaps were more common in zones 2 and 5, measuring ≤1 mm in depth in 94 hips on the VD and in 78 hips on the lateral views. No gaps were radiographically visible after 5 weeks postsurgery. No continuous interface radiolucency or lysis was detected, and none of the THR required revision because of loosening. CONCLUSION: Polar gaps were identified on the majority of radiographs immediately after THR in our clinical setting and all resolved without complications. CLINICAL SIGNIFICANCE: Recognition and incidence of postoperative polar gaps after THR may vary among surgeons. Gaps do not warrant clinical intervention.

Morbidity and Mortality Following Total Hip Replacement in Dogs.

OBJECTIVE: The objective of this study was to determine morbidity and mortality rates in dogs that had undergone a total hip replacement surgery with implantation of either a cemented or a cementless prosthesis (BioMedtrix LLC, Whippany, NJ). METHODS: The survival time after surgery, the date of death and the cause of death were collated from an ongoing registry maintained on consecutive total hip replacement procedures by a single surgeon. RESULTS: A review of the 1,864 dogs entered in the total hip replacement registry revealed 642 in which the date of death and cause of death were known. The mean life span of the dogs in this study was 11.3 years, with the longest being 17.1 years. The mean survival after total hip replacement was 4.66 years, with the longest being 16.1 years. Multiorgan system failure was more common than any single organ system failure. The most common pathophysiological process leading to death was neoplasia. CLINICAL SIGNIFICANCE: Morbidity and mortality rates are helpful for surgeons to compare outcomes and to inform animal owners about anaesthesia and procedural risks when contemplating this surgery. This information can be used for a better understanding of expectations for a dog's health after total hip replacement surgery.

Use of an Electron Beam Melting Manufactured Titanium Collared Cementless Femoral Stem to Resist Subsidence After Canine Total Hip Replacement.

OBJECTIVES: To evaluate the effect of a collared electron beam melting (EBM)-manufactured titanium cementless femoral stem on implant subsidence after total hip replacement (THR). STUDY DESIGN: Prospective study ANIMALS: Dogs (n = 26); 33 THR. METHODS: Records were maintained on the first 110 consecutive THR using an EBM collared femoral stem. Radiographs on the first 33 THR that had 6-months follow-up were evaluated for implant subsidence. These results were compared to 27 dogs with subsidence after THR with a Co Cr collarless stem. RESULTS: Dogs that had EBM collared stem THR had a mean body weight of 35.4 kg, body condition score (BCS) of 6.21, and mean canal flare index (CFI) of 1.56. EBM stem sizes used (number implanted) were #7 (13), #8 (10), #9 (8), and #10 (2). Subsidence of collared stems did not occur if the collar was in contact with cortical bone during surgery. Subsidence of 1-3 mm occurred closing a gap between the collar and bone if contact was not made during surgery, but subsidence stopped once contact was made. No major complications directly related to the EBM collared stem were encountered. CONCLUSIONS: A collar on a cementless femoral stem in contact with cortical bone resists subsidence.

A survey on orthopedic injuries during a marathon sled dog race.

PURPOSE: This prospective observational study aimed to describe and quantify orthopedic injuries (OI) during a marathon sled dog race that led to discontinuation of racing (dropped dogs [DDs]) and to suggest potential associations with risk factors during the event. STUDY DESIGN: Prospective observational study. ANIMALS: A total of 989 Nordic breed endurance sled dogs that participated in the 2011 Iditarod Sled Dog Race. Data were collected via an extensive questionnaire, medical records, and speed calculations based on Global Positioning System equipment on each dog sled. OI risk factors and DD incidence were statistically analyzed on dogs and teams completing at least half the race distance, including Student's t-test, Pearson's chi-squared test, Poisson regression, and various frailty analysis models as indicated. Significance was set at P<0.10 for inclusion in the models with trends established at P≤0.10 and significance declared at P<0.05. RESULTS: Questionnaire response was 40.3%. DD incidence was 38.3%, most often due to OI (50.6%). OI occurred most frequently in the thoracic limb (43.3%) compared with pelvic limb injuries (7.3%). Increased speed was associated with fewer shoulder injuries (Ratio=0.65, P=0.03). Carpal injuries were positively related with increased conditioning distance (defined as training miles; Hazard ratio =1.61, P=0.02). The risk to become a DD decreased with every year of increased age of the dogs (Hazard ratio =0.92, P=0.03). CONCLUSION: OI, specifically of the shoulder and carpus, are common in marathon sled dogs. Injury risk may be speed-related and decreases with increasing age of the dog. Further study of environmental, dietary, and trail conditions in sled dog racing orthopedic research is needed.

In vitro effects of meloxicam on metabolism in articular chondrocytes from dogs with naturally occurring osteoarthritis.

OBJECTIVE: To assess effects of in vitro meloxicam exposure on metabolism in articular chondrocytes from dogs with naturally occurring osteoarthritis. SAMPLE: Femoral head cartilage from 16 dogs undergoing total hip replacement. PROCEDURES: Articular cartilage samples were obtained. Tissue sulfated glycosaminoglycan (SGAG), collagen, and DNA concentrations were measured. Collagen, SGAG, chondroitin sulfate 846, NO, prostaglandin E2 (PGE2), and matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, and MMP-13 concentrations in culture medium were analyzed. Aggrecan, collagen II, MMP-2, MMP-3, MMP-9, MMP-13, ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS)-4, ADAMTS-5, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, TIMP-3, interleukin-1ß, tumor necrosis factor-α, cyclooxygenase-1, cyclooxygenase-2, and inducible nitric oxide synthase gene expression were evaluated. Comparisons between tissues cultured without (control) and with meloxicam at concentrations of 0.3, 3.0, and 30.0 µg/mL for up to 30 days were performed by means of repeated-measures analysis. RESULTS: Meloxicam had no effect on chondrocyte SGAG, collagen, or DNA concentrations. Expression of ADAMTS-5 was significantly decreased in all groups on all days, compared with the day 0 value. On day 3, culture medium PGE2 concentrations were significantly lower in all meloxicam-treated groups, compared with values for controls, and values remained low. Culture medium MMP-3 concentrations were significantly lower on day 30 than on day 3 in all meloxicam-treated groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that in vitro meloxicam treatment of osteoarthritic canine cartilage for up to 30 days did not induce matrix degradation or stimulate MMP production. Meloxicam lowered PGE2 release from this tissue, and effects on tissue chondrocyte content and matrix composition were neutral.

Treatment of avascular necrosis of the femoral head in small dogs with micro total hip replacement.

OBJECTIVES: To evaluate clinical outcome of small dogs with avascular necrosis (AVN) of the femoral head treated with Micro total hip replacement (THR). STUDY DESIGN: Nonrandomized, retrospective efficacy case series. ANIMALS: Dogs (n = 7; 7 hips) that had Micro THR. METHODS: Medical records (December 2005-March 2009) of dogs affected with AVN treated with Micro THR were reviewed. Data analysis included age, sex, breed, body weight, and body condition. All dogs were evaluated at least 6 months after Micro THR was performed on the affected AVN limb. Physical, orthopedic, and radiographic examination, owner questionnaire, thigh girth, and ground reaction force were evaluated. RESULTS: Seven dogs (7 Micro THR) met the inclusion criteria. Mean age at time of onset of clinical signs was 7.7 months and mean age at time of Micro THR was 9.6 months. Mean body weight was 4.2 kg. Median body condition score was 5.0 (range, 4-6). Mean cumulative functional scores from client questionnaires before (19.5; range, 11-25) and after Micro THR (8.2; range, 7-14) were significantly different (P = .004). There was no significant difference between thigh girths of the Micro THR (17.8 ± 2.6 cm; range, 14.5-21.5 cm) limbs when compared with contralateral (17.5 ± 2.9 cm; range, 14.5-22.0 cm) limbs (P = .38). Peak vertical force (P = .20), vertical impulse (P = .81), peak braking force (P = .91), braking impulse (P = .19), peak propulsion force (P = .32), and propulsion impulse (P = .19) were not significantly different in Micro THR limbs compared with contralateral limbs. CONCLUSION: There was no relationship between age, sex, and breed for development of AVN in this study. Dogs that received Micro THR for the treatment of AVN had no significant differences in thigh girth and ground reaction forces when Micro THR limb was compared with the contralateral limb.

Total hip replacement as a treatment option for capital physeal fractures in dogs and cats.

OBJECTIVES: To evaluate outcome of capital physeal fractures (CPFs) treated by total hip replacement (THR) in dogs and cats. STUDY DESIGN: Retrospective phase II nonrandomized efficacy study. ANIMALS: Dogs (n = 21), cats (n = 4). METHODS: Medical records (1991-2009) and radiographs of dogs and cats with CPF treated by THR were reviewed. Physical examination findings, radiographs, thigh circumference (TC), force plate gait analysis, and an owner questionnaire were reviewed. RESULTS: Signalment and median interval between CPF and THR of all 25 animals had no clinical correlation with post-THR outcome. Force plate gait analysis and TC were available for 12 dogs. No significant difference in TC or force plate analyses between the THR limb and the normal contralateral limb was identified. Owner questionnaires (13 dogs) revealed improvement after THR with minimal (n = 2) or no lameness (n = 11). CONCLUSION: Animals with CPF treated by THR did not have statistically significant differences in any subjective (21 dogs, 4 cats) or objective (12 dogs) variable when compared with the normal contralateral limb.

Duration of clinical signs prior to total hip replacement in dogs.

OBJECTIVE: To compare the duration of clinical signs in dogs prior to total hip replacement (THR) for 2 time periods and to determine whether a previous THR influenced the duration of clinical signs prior to THR of the contralateral hip joint. DESIGN: Retrospective cohort study. ANIMALS: 833 dogs that underwent unilateral THR (334 dogs between 1992 and 2000 [group 1] and 499 dogs between 2001 and 2009 [group 2]; part 1) and 272 dogs that underwent staged bilateral THR between 1992 and 2009 (part 2). PROCEDURES: Duration of pelvic limb lameness prior to THR was recorded in an in-house data registry. Mean duration of clinical signs was determined for both groups of dogs in part 1. For part 2, duration of clinical signs prior to the first THR was compared with the interval between surgeries in dogs that underwent bilateral THR. RESULTS: In part 1, duration of clinical signs was significantly longer for group 2 dogs than for group 1 dogs. In part 2, the duration of clinical signs prior to the first THR was significantly longer than the interval between surgeries. CONCLUSIONS AND CLINICAL RELEVANCE: Between 1992 and 2009, the duration of clinical signs prior to THR in dogs increased significantly. In dogs that underwent bilateral THR, the interval between surgeries was shorter than the duration of clinical signs before the first THR. Developments in medical treatments of osteoarthritis, surgical preferences, and veterinarian recommendations may influence the interval between initial clinical signs and surgery.

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.

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.