Total hip arthroplasty for femoral fractures other than capital physeal fractures in dogs: 14 cases (2012-2020)

OBJECTIVES

The goals of this retrospective study were to assess the clinical and radiographic outcomes in dogs with proximal femoral fractures, other than capital physeal fractures, treated via total hip arthroplasty.

MATERIALS AND METHODS

Medical records as well as pre-operative, immediate post-operative and 2 to 3 months post-operative radiographs of 14 dogs with femoral head and neck fractures treated via total hip arthroplasty were reviewed. A Liverpool Osteoarthritis in Dogs questionnaire was completed by owners to assess long-term outcomes.

RESULTS

Seven femoral head fractures, and seven femoral neck fractures were included. Four of the femoral head fractures were acute in nature, the three remaining femoral head fractures and all seven femoral neck fracture cases were chronic fractures. Malorientation of the femoral stem was more common in the chronic femoral fracture cases when compared to the acute femoral fracture cases. Two of the acute fracture cases and five chronic fracture cases experienced a change in femoral stem position post-operatively. One femoral fissure fracture occurred and was repaired intraoperatively. One case had a post-operative complication that resulted in implant removal. All dogs had good to excellent owner-perceived outcome.

CLINICAL SIGNIFICANCE

Femoral head and neck fractures, and in particular the chronic cases, represented a challenging subset of cases presenting for total hip arthroplasty, resulting in suboptimal stem alignment in many cases. However, clinical outcomes were considered good to excellent in all dogs in the study, indicating that total hip arthroplasty is a viable treatment option for these types of fractures.

Proximal femoral deformity correction and total hip arthroplasty in a dog using 3D printed custom guides

OBJECTIVE

To report the successful correction of a proximal femoral deformity (PFD) and total hip arthroplasty (THA) in a dog with the use of three-dimensionally (3D) printed custom surgical guides (CSGs).

STUDY DESIGN

Case report.

ANIMALS

One-year-old, male neutered, Goldendoodle.

METHODS

Uniapical proximal varus and recurvatum femoral deformity (PFD) precluded femoral stem placement for THA, which was indicated for severe hip dysplasia. Using CT-derived bone and implant models, custom ostectomy and reduction guides for deformity correction were designed. A 13-hole 3.5 mm locking compression plate was contoured and applied to 3D printed models of the corrected femur and screw trajectory holes were incorporated into the CSGs.

RESULTS

A caudolateral closing wedge ostectomy of the proximal femur was achieved with the aid of the CSGs and precontoured plate to within 2° of varus and 1° of recurvatum of the virtual surgical plan. Placement of a press-fit femoral stem was achieved with 7° of varus and 9° of caudal angulation. The plate was secured using six locking screws, two cortical screws, and two 18-gauge double-loop cerclage wires. No lameness and normal range of motion of the hip were observed on clinical examination 3 months after surgery. Radiographs at 3 and 6 months revealed static implant positioning, and complete bony union at the ostectomy site.

CONCLUSION

Virtual surgical planning and CSGs led to successful concurrent THA and femoral deformity correction.

Clinical outcomes of canine total hip replacement utilizing a BFX lateral bolt femoral stem: 195 consecutive cases (2013-2019)

OBJECTIVE

To evaluate the clinical outcomes of total hip replacements (THR) utilizing a BFX lateral bolt stem in dogs with coxofemoral joint disease.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

A total of 149 dogs representing 195 THR.

METHODS

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.

RESULTS

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 = 3 months). 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.

CONCLUSION

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.

CLINICAL SIGNIFICANCE

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.

Case factors for selection of femoral component type in canine hip arthroplasty using a modular system

OBJECTIVE

To describe a femoral stem selection process based on case features in dogs treated with total hip replacement (THR) by an expert surgeon, compare complications between implant types, and develop an algorithm for stem type selection.

STUDY DESIGN

Retrospective study.

ANIMALS

128 dogs, 135 THR.

METHODS

Data collected included breed, age, weight, canal flare index (CFI), and implant type: cementless (BFX), cementless with a collared stem (BFX-C), hybrid (cementless acetabular component with cemented stem), and cemented (CFX).

RESULTS

Of the 135 THRs, 69 BFX, 47 hybrid, and 18 BFX-C were performed. Dogs receiving hybrid (mean 5.5 years) were older than those receiving BFX (2.5 years, p < .0001) and BFX-C implants (2.5 years, p = .0014). The mean weights of dogs with hybrid, BFX, and BFX-C implants were 40.0, 31.0, and 35.3 kg, respectively, with dogs receiving hybrid heavier than those receiving BFX (p < .0001). Mean CFI for hybrid (1.52) was lower than for BFX (1.79, p < .0001) and BFX-C (1.76, p = .0021). Total complication rate was 14.0% with catastrophic complications in 1.5% and no association between implant type and risk of complications (p = .36). Femur fractures occurred in 2.9% of all cases and 1.1% of cementless THR cases.

CONCLUSIONS

Dogs receiving hybrid THR were older with lower CFI than dogs receiving BFX and BFX-C and heavier than dogs receiving BFX. There was no difference in complications between groups. Catastrophic complications and femur fractures occurred less frequently compared to recent studies of BFX THR.

CLINICAL SIGNIFICANCE

Careful preoperative assessment and implant selection can reduce complications of canine THR.

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.

Evaluation of a novel method to calculate cementless femoral stem level on craniocaudal projection radiographs

OBJECTIVE

To assess the accuracy of a proportion-corrected radiographic cementless femoral stem level calculation in a cadaver model.

STUDY DESIGN

Cadaveric study.

SAMPLE POPULATION

Twelve cadaveric canine femurs.

METHODS

Cementless femoral stems were implanted in 12 cadaver femurs at three stem levels. Craniocaudal projection radiographs of the implanted femurs were obtained at 0°, 10°, 20°, 30°, and 45° angulations in the sagittal plane (relative to the radiographic plate) and at 0°, 15°, and 30° internal and external axial rotation. A proportional calculation including actual stem length, radiographically measured stem length, and radiographically measured stem level relative to the greater trochanter (uncorrected stem level) was solved to yield a corrected stem level. The errors of the stem level measurements were compared.

RESULTS

With 0° or 15° of internal rotation, the true stem level differed by more than 0.5 mm from corrected stem level in 2 of 30 tested femoral positions. It differed from the uncorrected stem level in 10 of 30 positions. With 15° and 30° external rotation or 30° internal rotation, the corrected stem level was not more accurate than the uncorrected stem level for any femoral position.

CONCLUSION

Use of a proportion correction minimized variability in the stem-level measurements due to sagittal angulation (up to 30°) of the femur at 0° or 15° of internal rotation.

CLINICAL SIGNIFICANCE

A proportion correction can improve the accuracy of femoral stem-level assessment on craniocaudal projection radiographs, which may aid in the detection of subsidence after cementless total hip replacement.

Biomechanical evaluation of a new femoral stem design for total hip replacement in a canine model

PURPOSE

To evaluate the biomechanical properties of a novel total hip replacement femoral stem.

METHODS

Eight pairs of femurs from dog cadavers were used. The femurs were separated into different groups. A novel femoral stem with a convex proximal portion (Stem B) was biomechanically evaluated and compared to awell-known veterinary collared stem (Stem A). Femoral stems were inserted into the contralateral femurs from the same dog, forming 16 constructs. A flexo-compression load was applied on the axial axis of each sample. Maximum strength, deflection, stiffness, and energy absorption were analysed.

RESULTS

Group B constructs showed significantly higher values (p ? 0.05) for the variables, except stiffness. The mean maximum strength was 1,347 ± 357 N for Group A and 1,805 ± 123 N for Group B (p ? 0.0069). The mean deflection was5.54 ± 2.63 mm for Group A and 10.03 ± 3.99 mm for Group B (p ? 0.0056). For the energy variable, the force was 6,203 ± 3,488 N/mm for Group A and 12,885 ± 5,056 N/mm for Group B (p ? 0.0054). Stem B had greater maximum strength, deflection, and energy.

CONCLUSIONS

The new stem was effective in neutralizing the impact of axial flexion-compression stresses during biomechanical tests in cadaveric models.

Comparison of radiographic and tomographic evaluations for measurement of the Canal Flare Index in dogs

ABSTRACT The outcome of total hip arthroplasty (THA) in dogs is directly related to surgical planning. Templating of radiographs prior to THA should help the surgeon anticipate prosthesis size and femoral shape allowing canal fill of the proximal metaphysis by the implant ensuring primary stable fixation. The canal flare index (CFI) obtained from radiograph has been used as a measure of risk of complications for the technique in human beings and dogs. However, standard radiographs only provide limited data for the selection of cementless prostheses and the assessment of their fit within the femoral canal, due to factors like radiographic magnification and femoral rotation. Therefore, three-dimensional evaluation based on computed tomography (CT) may be a better tool for CFI measurement. The aim of this study was to compare anatomical measurement with CFI values obtained from craniocaudal radiography and CT. Craniocaudal radiographs using a horizontal radiographic beam (CR), CT, and anatomical macroscopic measurements (A) were obtained from 45 femurs from 23 canine cadavers. The differences between the values of CFI obtained from radiograph (CFI-R), computed tomography on transverse (CFI- TT) and longitudinal axis (CFI-TL) compared to the CFI obtained from macroscopic measurements - gold standard - (CFI-A), and 95% limits of agreement (LOA) between the values, were evaluated by the Bland-Altman method. Dimensions obtained from CT techniques had a greatest mean difference from anatomical and CFI values were also different (P=0.032). Under the experimental conditions, the craniocaudal radiograph, provided the most accurate measurement of the CFI (mean difference: 0.087 ± 0.42).

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.

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.

Treatment Outcomes for Periprosthetic Femoral Fractures in Cementless Press-Fit Total Hip Replacement

OBJECTIVE

 The aim of this study was to report outcomes in dogs with periprosthetic femoral fractures associated with a press-fit cementless femoral total hip replacement implant.

MATERIALS AND METHODS

 Electronic medical records and digital radiographs were used to identify dogs with periprosthetic femoral fractures associated with press-fit cementless total hip replacement. Data collected included signalment, weight, time of fracture, cause of fracture, presence of intra-operative fissure, fracture type, repair technique, and clinical and radiographic outcomes. Long-term patient outcome was assessed by communication with owners or referring veterinarians.

RESULTS

 Twenty-eight dogs with femoral fracture repair associated with cementless press-fit total hip replacement were identified. Eight of the fractures occurred intraoperatively and 20 occurred at a median of 2 days postoperatively. An oblique or spiral configuration was noted in 19 cases and 15 occurred at the distal end of the femoral stem (type B), with thirteen type B1, one type B2 and one type B3 fractures. Fractures were repaired with non-locking (18/28) or locking-plate fixation (10/28). Cerclage wire was applied around the plate and proximal bone segment in 17/28 dogs. Major complications occurred in 7/28 cases (five deep infection, two mechanical failures). Bone healing was noted in 21/23 cases, for which follow-up radiographic interpretation was available. Return to function was complete in 17 cases, acceptable in 8 cases and unacceptable in 3 cases.

CONCLUSIONS

 While cementless total hip replacement periprosthetic femoral fractures can be successfully repaired with lateral plate fixation, the risk of infection appears to be high.

Evaluation of cementless femoral stem level on mediolateral projection radiographs

OBJECTIVE

To evaluate the accuracy of measuring cementless femoral stem level on mediolateral projection radiographs.

STUDY DESIGN

Benchtop cadaveric.

SAMPLE POPULATION

Twelve canine cadaver femurs.

METHODS

Cementless femoral stems were inserted into 12 canine cadaver femurs at three levels of subsidence. Mediolateral radiographs were obtained for each femur at 0°, 10°, and - 10° frontal plane angulation and at 0°, 15°, 30°, -15°, and - 30° axial plane rotation. Stem level was measured physically on specimens and on radiographs, and a proportion was used to calculate corrected stem level. Stem level was assessed relative to the greater trochanter and relative to the intertrochanteric fossa. Analysis of variance tests were used to compare actual, radiographically measured, and corrected stem level.

RESULTS

No differences were detected between radiographically measured and actual stem level relative to the greater trochanter at 0°, 15°, 30°, and - 30° axial rotation with 0° frontal plane angulation; introduction of 10° or - 10° frontal plane angulation resulted in differences between radiographically measured and actual stem level. Errors >0.5 mm were observed in 82% of radiographic measurements on the basis of the intertrochanteric fossa. The use of a corrective proportion did not improve the accuracy of radiographic measurements.

CONCLUSION

Femoral stem level was accurately quantitated on mediolateral projection radiographs in this cadaver model. Frontal plane angulation distorted this measurement.

CLINICAL SIGNIFICANCE

Femoral stem subsidence may be assessed on well-positioned mediolateral projection radiographs if the landmarks are visible.

Comparison of femoral stem subsidence between three types of press-fit cementless total hip replacement in dogs

OBJECTIVE

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.

STUDY DESIGN

Retrospective radiographic study.

SAMPLE POPULATION

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).

METHODS

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.

RESULTS

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.

CONCLUSION

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.

CLINICAL SIGNIFICANCE

Implantation of a lateral bolt femoral stem should be considered during THR to prevent subsidence.

Total hip arthroplasty to address chronic hip luxation with pseudoacetabulum formation in seven dogs

OBJECTIVE

To compare the outcome of dogs treated with total hip arthroplasty (THA) for chronic hip luxation and pseudoacetabulum formation to that of dogs with simple hip dysplasia and secondary osteoarthritis.

STUDY DESIGN

Retrospective, case-controlled study.

ANIMALS

Seven dogs with pseudoacetabulum (group 1) and 21 matched control dogs (group 2).

METHODS

Each dog in group 1 was matched with three control dogs, primarily according to similarity of THA implant type and size. Patterns of radiographic pathology were characterized in each dog. Outcome measures included operative time, acetabular cup position/orientation (inclination angle, angle of lateral opening, version angle) complications, and long-term outcomes. Outcome measures were compared between groups using linear regression (P = .05).

RESULTS

The presence of a pseudoacetabulum was associated with ilial remodeling and heterotopic bone formation concentric to the luxated femoral head. Exposing the native acetabulum and reducing the prosthesis were surgically challenging. The mean (SD) operative time of dogs in group 1 (96 [18] minutes) was longer than that of dogs in group 2 (63 [14] minutes; P = .00002). Cup position/orientation was not different between dogs in group 1 and group 2. One intraoperative complication and two minor postoperative complications occurred in group 1 dogs. All dogs had good long-term outcomes.

CONCLUSION

Total hip arthroplasty in dogs with a pseudoacetabulum was more challenging than in control dogs. However, the procedure provided good to excellent long-term clinical outcomes in all dogs.

CLINICAL SIGNIFICANCE

Surgeons should be prepared for the specific surgical challenges associated with THA in dogs with pseudoacetabulum formation.

Management of total hip replacement luxation with triple pelvic osteotomy

OBJECTIVE

To report the outcome of dogs treated with triple pelvic osteotomy (TPO) for dorsal luxation after total hip replacement (THR).

STUDY DESIGN

Retrospective clinical case series.

ANIMALS

Seventeen client-owned animals.

METHODS

Medical records were searched at a single institution for dogs that had been treated with TPO for dorsal THR luxation. The angle of lateral opening (ALO), version angle (VA), and inclination angle (IA) were measured from radiographs after THR and TPO and corrected for pelvic rotation. A paired t test was performed to compare cup orientation after THR and TPO. Functional outcome was assessed at follow-up examination and during telephone interviews.

RESULTS

Eighteen TPOs were performed in 17 dogs, and radiographs were available for 15 cases. Open and/or closed hip reduction with additional stabilization was attempted unsuccessfully in 6 dogs prior to TPO. Triple pelvic osteotomy reduced the ALO by a mean of 23.0 ° ± 10.9 ° (P ≤ .001), increased VA by 9.0 ° ± 4.9 ° (P < .001), and increased IA by 2.9 ° ± 5.8 ° (P = .126). An excellent or good outcome was achieved in 12 dogs. Ventral luxation occurred in 3 dogs, and dorsal luxation occurred in 1 dog after TPO. Triple pelvic osteotomy excessively reduced ALO in 2 dogs with ventral luxation.

CONCLUSION

Triple pelvic osteotomy with cup retention is a viable alternative to cup revision for treatment of dorsal luxation of cemented and cementless THR. Triple pelvic osteotomy significantly reduces ALO and increases VA. Careful patient selection is recommended because excessive ventroversion can lead to ventral luxation.

CLINICAL SIGNIFICANCE

Triple pelvic osteotomy offers a revision option that preserves the implant-bone interface and significantly reduces ALO. This technique may be appropriate in dogs with high ALO, luxoid hips, and prior failed revision attempts.

Complications of porous-coated press-fit cementless total hip replacement in dogs

Objective: To report postoperative complications using a commercially available porous-coated press-fit cementless total hip replacement (THR) system in dogs.

Methods: Medical records were reviewed for client-owned dogs with hip pathologies requiring THR. A minimum of six-week postoperative orthopaedic examination and orthogonal pelvic radiographs were used to assess outcome and complications in the perioperative period. Referring veterinarian medical records, phone interviews with clients, or both were used to assess long-term functional outcome and complications.

Results: Bilateral THR was performed in 36 dogs, and unilateral in 147 dogs, making a total of 219 THR procedures in 183 dogs. A total complication rate of 31.1% (68/219) was observed. A catastrophic complication was observed in 8.2% (n = 18), a major complication in 9.6% (n = 21), and a minor complication in 13.2% (n = 29) of procedures. The most common complications were intra-operative femoral fissure (n = 46), diaphyseal femoral fracture (n = 15), and coxofemoral luxation (n = 9). Full return to function was achieved in 88.1% of procedures with a median follow-up period of 42 months.

Clinical significance: Porous-coated press-fit cementless collarless total hip replacements have a high complication rate. The majority of complications occur intra-operatively or perioperatively, with few complications occurring beyond 12 weeks postoperatively. Both fissure fractures and diaphyseal femoral fractures carry a favourable prognosis with immediate cerclage wiring and plate fixation, respectively.

Revision of a BFX total hip replacement stem using a Kyon stem and a head adaptor in two dogs

OBJECTIVE

To report revision of BFX cementless press-fit stem loosening with a Kyon cementless stem and a head adaptor in two dogs.

METHODS

Total hip arthroplasty stem revision was performed in two dogs with loosening of a previously implanted Biomedtrix press-fit BFX stem. Both dogs had a well-integrated BFX cup and single stage revision was performed using a standard Kyon stem and a head adaptor in order to couple with a 17 mm head and maintain the BFX cup.

RESULTS

Revisions resulted in a stable functional prosthesis with successful bone integration at the one-year postoperative re-evaluation.

CONCLUSIONS

Use of a Kyon stem with a head adaptor may be a successful option to provide immediate stem stability for revision of a loosened BFX stem with a properly osseointegrated cup.