Subsidence of the BFX standard stem after canine total hip replacement: A case series of 177 consecutive procedures.

To compare femoral stem subsidence and determine contributing factors in dogs undergoing total hip replacement (THR) with the traditional BFX, collared BFX, and BFX lateral bolt stems. Retrospective radiographic study. Ninety-three dogs with 101 THR including dogs undergoing THR with a BFX lateral bolt femoral stem (n = 40), BFX collared stem (n = 21), and traditional BFX stem (n = 40). Radiographs of traditional BFX (n = 40), collared BFX (n = 21), and BFX lateral bolt (n = 40) THR performed from 2015 to 2018 were reviewed. Subsidence, canal flare index (CFI), stem canal fill (CF), stem orientation, and complications confirmed on radiographs were recorded at postoperative and recheck radiographs. Analysis of variance tests were used to compare subsidence, CFI, stem orientation, and CF. A χ2 analysis was performed to compare complication rates between groups. Subsidence was lower after placement of BFX lateral bolt stems (median, 0.24 mm; interquartile range [IQR; 1.49) compared with collared (1.27 mm [2.29]) and BFX (1.35 mm [2.26]) stems. No difference in subsidence was detected between collared and BFX implants. Coronal CF was greater after placement of BFX (mean ± SD, 0.72 ± 0.06) compared with lateral bolt (0.69 ± 0.05) or collared (0.66 ± 0.07) stems. Sagittal CF differed between all groups (BFX 0.7 ± 0.05, lateral bolt 0.67 ± 0.06, and collared 0.61 ± 0.06). No differences were identified in CFI or stem orientation in the coronal and sagittal planes or in complication rates between implants. The BFX lateral bolt femoral stem was associated with less postoperative subsidence compared with the BFX collared and traditional BFX stems. No consistent changes in CF, CFI, or stem orientation or complication rates were identified in association with increased subsidence in this study. Implantation of a lateral bolt femoral stem should be considered during THR to prevent subsidence.

To evaluate the clinical outcomes of total hip replacements (THR) utilizing a BFX lateral bolt stem in dogs with coxofemoral joint disease. Retrospective study. A total of 149 dogs representing 195 THR. Consecutive THRs utilizing a BFX lateral bolt stem were studied. Preoperative, immediate postoperative, 1-, 2-, 3-, 4-, and 12-month postoperative radiographs were performed. All major and minor complications, revisions, outcomes, subsidence, canal flare index (CFI) were recorded. An intraoperative complication rate of 11.8% was observed. The postoperative complication rate was 13.6%, with 9.2% major and 4.4% minor complications. Complications included: postoperative femur fractures (3.6%), coxofemoral luxation (3.6%), stem failure (0.5%), septic loosening (0.5%), aseptic loosening (0.5%), and acetabular fracture (0.5%). Three dogs underwent prophylactic plating after subjective assessment of cortical thickness. Five of 195 (2.6%) cases underwent explant of their prostheses (median=3months). Mean stem subsidence at 1 month postoperatively was 1.22 ± 0.16 mm. An increased CFI was associated with postoperative femur fractures (p < .05). A total of 190 of 195 (97.4%) cases returned to normal function in the long-term follow-up period. Use of the BFX lateral bolt stem resulted in minimal postoperative subsidence, a low femoral stem complication rate, and a high rate of achieving normal limb function. The BFX lateral bolt stem should be considered in canine THR as the femoral failure rate is low and the long-term success rate is high.

Inadequate Metadiaphyseal Fill of a Modern Taper-Wedge Stem Increases Subsidence and Risk of Aseptic Loosening: Technique and Distal Canal Fill Matter!

Introduction:In the United States, tapered splined titanium stems (TSTSs) are the most frequently used femoral stem design in revision total hip arthroplasty. Despite encouraging and favorable results with TSTS, complications including femoral stem subsidence persist and subsidence >5 mm has been associated with implant failures and the need for aseptic rerevision surgery. We sought to investigate whether an extended trochanteric osteotomy (ETO) at the time of TSTS insertion increased mean subsidence and whether the amount of cortical contact was associated with subsidence, failure, and revision.Methods:This is a single-center retrospective cohort study of a prospectively collected database including all patients who received a TSTS from 2016 to 2020. Data collected include surgery type, presence of an ETO, and stem specifications. Radiographs were reviewed to analyze cortical contact and postoperative subsidence. Pearson’s correlation coefficient was used to determine the association between contact length and subsidence.Results:This cohort consisted of 299 hips, and 66 hips necessitated an ETO at the time of TSTS. Patients who required an ETO were more likely to subside (2.5 ± 0.2 mm vs 5.0 ± 0.7 mm, p < 0.001) and were more likely to subside >5 mm (32.3% vs 14.5%, p = 0.001). After controlling for other variables, an ETO was an independent risk factor for significant subsidence (adjusted OR: 3.4, p = 0.02). Contact length below the ETO was inversely related to stem subsidence (correlation coefficient of −0.26; p = 0.037), and multivariable logistic regression demonstrated bicortical contact > 30 mm to be a protective factor for significant subsidence (adjusted OR: 0.12, p < 0.001). Patients who received an ETO had a higher aseptic rerevision rate than patients who had a TSTS implanted without an ETO (16.1% vs 6.6%, p = 0.018).Conclusions:Patients who receive an ETO during revision hip arthroplasty have a higher mean subsidence and 3-fold increase in odds for subsiding >5 mm. However, bicortical contact of 30 mm or greater below the ETO was protective against significant TSTS subsidence. Although not all patients with >5 mm of subsidence were revised, the aseptic rerevision rate was significantly higher in patients who received an ETO.Clinical Relevance:An extended trochanteric osteotomy is an excellent technique to gain direct visualization of the femoral canal. However, it is not without its associated morbidity and postoperative complications, specifically stem subsidence. The results of this study suggest that when preparing for a TSTS after an ETO, careful consideration should be taken to confirm 3 cm of cortical engagement below the transverse limb of the ETO. The scaffolding technique, which prioritizes stem preparation followed by ETO closure, facilitates achieving sufficient cortical contact in the intact canal below the ETO segment. Consideration for intraoperative radiographs to confirm appropriate contact length and location may ensure sufficient fixation that will minimize the risk of postoperative stem subsidence.Level of Evidence:Level III. See Instructions for Authors for a complete description of levels of evidence.

BackgroundFemoral component subsidence is a known risk factor for early failure of total hip arthroplasty (THA) using cementless stems. The aim of the study was to compare an enhanced recovery concept with early full weight-bearing rehabilitation and partial weight-bearing on stem subsidence. In addition, the influence of patient-related and anatomical risk factors on subsidence shall be assessed.MethodsOne hundred and fourteen patients underwent primary cementless THA and were retrospectively analyzed. Sixty-three patients had an enhanced recovery rehabilitation with early full weight-bearing and 51 patients had rehabilitation with partial weight-bearing (20 kg) for 6 weeks. Postoperative subsidence was analyzed on standing pelvic anterior–posterior radiographs after 4 weeks and 1 year. Subsidence was measured in mm. Anatomical and prosthetic risk factors (stem size, canal flare index, canal fill ratio as well as BMI and demographic data) were correlated.ResultsFemoral stem subsidence rate was significantly higher for the group with an enhanced recovery concept compared to the group with partial weight-bearing at the first radiological follow up after 4 weeks [2.54 mm (SD ± 1.86) vs. 1.55 mm (SD ± 1.80)] and the second radiological follow up after 1 year [3.43 mm (SD ± 2.24) vs. 1.94 (SD ± 2.16)] (p < 0.001, respectively). Stem angulation > 3° had a significant influence on subsidence. Canal flare index and canal fill ratio showed no significant correlation with subsidence as well as BMI and age.ConclusionIn the present study, cementless stem subsidence was significantly higher in the group with enhanced recovery rehabilitation compared to partial weight-bearing. Small absolute values and differences were demonstrated and therefore possibly below clinical relevance. Anatomical radiological parameters and anthropometric data did not appear to be risk factors for stem subsidence.

To evaluate the effect of a collared electron beam melting (EBM)-manufactured titanium cementless femoral stem on implant subsidence after total hip replacement (THR). Prospective study Dogs (n = 26); 33 THR. 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. 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. A collar on a cementless femoral stem in contact with cortical bone resists subsidence.

Total hip arthroplasty effectively restores near-normal gait in most dogs with hip dysplasia unresponsive to conservative treatment. Total hip replacement (THR) requires high surgical accuracy for all surgeons, though errors and deviations are more common during the learning phase (Hayes et al.Vet Surg 40(1):1-5, 2011a). This study aimed to evaluate the technical performance and identify common intraoperative deviations in cemented THR performed by a novice surgeon using canine cadavers. Twelve adult cadavers underwent unilateral THR following a standardized protocol, with implant sizes determined through both radiographic and CT-based preoperative templating. All procedures were performed under expert supervision, with intraoperative corrections made when necessary. Postoperative radiographs were obtained not to detect missed errors but to objectively quantify final implant orientation after correction, thereby documenting technical inaccuracies, including those corrected intraoperatively. Postoperative radiographs were assessed for acetabular cup orientation, femoral stem alignment, canal fill, cement mantle quality, tip-to-cortex distance and cement quality. Overall, > 80% agreement was noted between templated and implanted components. A statistically significant association (p = 0.04) was observed between the matched acetabular cup and femoral stem. While implant positioning, including stem orientation, canal fill, and cement mantle thickness, cementation quality was within acceptable limits, increased canal fill correlated with mild varus or valgus deviations (r = 0.702, p = 0.01). These findings suggest that novice surgeons may achieve reproducible and acceptable outcomes through cadaver-based training with structured mentoring. However, optimal implant placement was not consistently achieved, indicating that further refinement is needed. Larger-scale cadaveric studies and more intensive surgical training protocols are recommended to enhance accuracy, reduce variability, and improve learning outcomes clinically in canine THR.

Stem subsidence and thigh pain can cause significant patient dissatisfaction after cementless THA. The purpose of this study was to examine the effect of proximal-femoral morphology and stem alignment on clinical outcomes using a double-tapered, cementless titanium femoral component. We retrospectively reviewed 281 consecutive, primary THAs from 2012 to 2014 with a mean follow-up of 4 years. Preoperative radiographs were used to assess femoral neck shaft angle (FNS), canal flare index (CFI), Dorr classification, and greater trochanter (GT) overhang. Postoperative radiographs were used to determine stem alignment and 6-week follow-up radiographs were used to determine subsidence. Clinical outcomes included thigh pain, leg-length discrepancy (LLD), patient-reported outcome measures (PROMs) and revision surgeries. 271 stems (96%) did not subside (<4 mm) and 10 (4%) showed evidence of subsidence (>4 mm). Subsidence was significantly associated with subsequent revision surgery (p < 0.01). 278 stems (99%) were in neutral alignment and 3 in varus (1%). Alignment did not significantly influence subsidence, thigh pain, LLD, revisions, or PROMs. Femoral morphology measures (FNS, CFI, Dorr classification, and GT overhang) were not significantly associated with stem alignment, subsidence, LLD, or revisions. CFI was significantly associated with intraoperative calcar fractures (p = 0.02). GT overhang was associated with thigh pain (p = 0.03) and FNS was inversely associated with postoperative HOOS scores. Subsidence and proximal-femoral morphology are potential sources of postoperative morbidity in certain cementless THA patients. In accordance with prior studies, CFI was identified as a potential risk factor for intraoperative calcar fractures. More research into preoperative femoral morphologies, such as GT overhang and FNS, is warranted as these may contribute to unsatisfactory results related to cementless THA.

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 less than or equal to 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 greater than or equal to 2.5). Femora with more than 85% mean, middle, or distal canal fill were less likely to subside.

To evaluate the effects of different cementing techniques on radiographic cement mantle grade and short-term aseptic loosening of the femoral component in canine total hip replacement (THR). Retrospective study. Radiographs of 284 dogs that had THR. Immediate postoperative radiographs of 284 dogs that had cemented THR were reviewed by 4 surgeons and 1 radiologist and assigned a cement mantle grade using a 4-grade classification system. Dog age and weight at surgery, cementing technique (1st, 2nd, 3rd generation), complications (type and timing), and follow-up time were retrieved and analyzed. Mean cement mantle score for 2nd generation technique was significantly higher than 3rd generation technique and both were significantly higher than 1st generation technique (P<.001). Aseptic loosening was the 2nd most common complication observed with an incidence of 2.1%. Mean time from surgery to last follow-up examination was 122 days. No statistically significant difference in incidence of aseptic loosening was identified among different cement mantle grades or cementing techniques. Advanced cementing techniques resulted in better cement mantles based on grading of immediate postoperative radiographs, however grading did not predict short-term aseptic loosening. Cementing technique seemingly did not affect the incidence of short-term aseptic loosening of the femoral component for dogs in this study. Our study suggests that advances in cementing technique may result in improvements in the radiographic grade of cement mantles. With respect to aseptic loosening of the femoral component, our data only suggest that short-term (3 months-3 years) loosening cannot be predicted by immediate postoperative radiographic evaluation of cement mantle.

Numerous cementless total hip replacement (THR) systems are available for application in dogs and one of the potential differences among these systems is the technique for performing a femoral osteotomy and the amount of bone preserved in the calcar region. However, no quantitative comparison of osteotomy level has been performed for canine THRs to date. To develop and validate a method for quantifying the level of the osteotomy at its most distomedial aspect in conjunction with canine THR and to compare osteotomy level between multiple different THRs. Immediate post-operative cranial-caudal or caudal-cranial radiographs of 33 dogs treated with 17 Helica and 17 BFX THR were assessed and osteotomy level was quantified using a novel radiographic assessment by 3 independent observers. Correlation among observers was quantified using a Spearman rank order correlation. Osteotomy location was subsequently quantified for an additional 10 Zurich THRs. The osteotomy level for each THR was subsequently compared between Helica, BFX, and Zurich THRs using one-way non-parametric Mann-Whitney rank sum tests and significance set at p < 0.05. R-values assessing correlation between observers were 0.87, 0.72, and 0.60. Osteotomy location was significantly more proximal in conjunction with the Helica (0.75 ± 0.22) versus the BFX (0.97 ± 0.13; p < 0.001) and Zurich (1.1 ± 0.15; p < 0.001) femoral prostheses. Osteotomy location was also significantly more proximal with the BFX prosthesis in comparison to the Zurich THR (p < 0.05). The strong correlations among three different observers indicate that the technique for measuring the location of the distomedial aspect of the osteotomy was acceptably precise. The osteotomies made in conjunction with the short-stemmed Helica implants were significantly more proximal than those made with both of the long-stemmed (BFX and Zurich) femoral prostheses. The distomedial aspect of the osteotomy with the BFX system was significantly more proximal than that with the Zurich THR, indicating that between these two long-stemmed systems the osteotomy level is unique.

To identify risk factors associated with ventral luxation (VL) of canine total hip replacement (THR), and outcome. Retrospective study. Dogs (n=602) that had THR (563 cemented, 35 cementless, 4 hybrid). Dogs (1999-2004) with VL after THR were compared with dogs with uncomplicated THR. Data included signalment, body weight, diagnosis, implant size, acetabular cup orientation, and femoral displacement ratio (FDR). VL was diagnosed in 11 (1.8%) dogs after primary THR. Including 2 other dogs that had VL after the study period, 10 (77%) of 13 dogs had VL within 7 days of surgery. Risk factors for VL included Saint Bernard-type dogs (P=.0001), short neck extension (P=.0005), and high angle of lateral opening in other breeds (P=.018). There were trends toward higher risk of VL with lower FDR in Saint Bernard types (P=.060), and with cementless implants (P=.061). Twelve dogs had revision arthroplasty that was successful in all cementless and 2 cemented VL cases. Five dogs had recurrent VL and a poor outcome. VL is generally an early complication of THR, with no single common risk factor identified. Saint Bernard types and short neck extensions are associated with increased risk of VL. Poor cup orientation is a determining factor for VL in some dogs, but a protective orientation of the acetabular cup was not found. Revision is successful in most dogs, but recurrent VL merits a guarded prognosis.

To report femur fracture as a complication of canine total hip replacement (THR) and to report the incidence, predisposing factors, treatment options, and outcome. Prospective clinical study. Twenty-two client-owned dogs with 24 femoral fractures occurring during or after THR. Cemented THR (BioMedtrix, Boonton, NJ) was performed. Medical records and radiographs were used to identify dogs that had femur fracture and to identify risk factors. Follow-up was obtained until dog death or study end. The overall incidence of femur fracture after THR was 2.9%. Femoral fractures occurred intraoperatively, immediately postoperatively, and up to 2196 days after THR. In 17 dogs, fractures resulted from a traumatic event. Osteopathy was present at THR in 5 dogs; all developed femoral fissures during reaming. Three dogs had fractures associated with cortical thinning secondary to aseptic loosening. Fracture treatment included euthanasia (1 dog), strict confinement (3 dogs), full cerclage wires on long oblique fractures (3 dogs), or plate and screw fixation (10 with, and 7 without, cerclage wires). All fractures extended near the distal tip of the femoral stem and all aggressively treated fractures healed. Predisposing risk factors for femur fracture after THR include osteopathy and iatrogenic fissures created during reaming. Trauma, excessive load concentration, and increased torque can lead to mid-diaphyseal fracture near the end of the femoral stem. Fracture did not disrupt THR implants. Cement fracture exposing the tip of the femoral stem did not affect fracture healing or rehabilitation. Immediate plate and screw fixation resulted in the most favorable outcome; healing occurred in 6-10 weeks. Femur fractures that occur after THR should be repaired using plate and screw fixation augmented with cerclage wire when needed. Forces on fissures should be neutralized to prevent propagation and fracture. Owners of high-risk patients (old dogs with osteopathies or previous hip surgery) should be counseled before THR. The prognosis is excellent when fractures are treated correctly.

The objective of this study was to assess the variables associated with complications of total hip replacement (THR) and report owner-assessed outcomes. Entries into the British Veterinary Orthopaedic Association-Canine Hip...

To assess the influence of age on perioperative stem-associated complications when total hip replacement (THR) was performed with a BFX lateral bolt stem. Retrospective (2017-2022). A total of 197 client-owned dogs. Medical records of dogs that underwent THR with a lateral bolt stem were reviewed. Perioperative complications were recorded. Stem and femoral features were measured on postoperative and follow-up radiographs. The population was divided into juveniles (6-10 months), adults (>10 months to <7 years), and older dogs (≥7 years old). Association between groups and perioperative complications was assessed. Two-hundred and fifty five THRs were recorded: 139 unilateral and 58 bilateral. Intraoperative and early postoperative stem complication rates were 8.6% and 2%, respectively. Juveniles were at increased risk of developing intraoperative fissures. Age was not associated with early postoperative stem complications. German shepherd dogs were associated with postoperative fractures. Subsidence was weakly, but positively, associated with weight and canal flare index. Juveniles were at increased risk of developing fissures. There was no difference in postoperative stem complications among age groups. German shepherds were at increased risk of postoperative fracture despite the use of a lateral bolt stem. More studies are required to assess the effect of giant breeds on the risk of subsidence, as well as the effect of young age on fissure development. Age influenced the development of intraoperative, but not postoperative, stem complications with a lateral bolt stem. Prophylactic cerclage application could be considered in juvenile and German shepherd dogs.