Total hip replacement for the treatment of atraumatic slipped femoral capital epiphysis in dogs

Fluoroscopic Categorization of Cementless Acetabular Component Positioning

OBJECTIVES

 The purpose of this study was to evaluate a fluoroscopic method of angle of lateral opening (ALO) categorization based on identification of the visible portion of a pre-existing, circular recess within the metal shell of the BioMedtrix BFX acetabular component, which projects as an ellipse at clinically relevant ALO values. Our hypothesis was that there will be an association between the actual ALO and the categorization of ALO based on identification of the visible portion of the elliptical recess on a lateral fluoroscopic image at clinically relevant values.

METHODS

 A custom plexiglass jig was fitted with a two-axis inclinometer and a 24 mm BFX acetabular component attached to its tabletop. Fluoroscopic reference images were obtained with the cup positioned at an ALO of 35, 45 and 55 degrees with a fixed 10 degrees of retroversion. Thirty study fluoroscopic images (10 images at each ALO) were obtained based on randomization at an ALO of 35, 45 and 55 degrees (±0.5 degrees) with 10 degrees of retroversion. The order of the study images was randomized, and a single, blinded observer categorized the 30 study images as representing an ALO of 35, 45 or 55 degrees by comparison to the reference images.

RESULTS

 Analysis showed perfect (30/30) agreement with a weighted kappa coefficient of 1 (95% confidence interval: -0.717 to 1).

CLINICAL RELEVANCE

 The results demonstrate that accurate categorization of ALO can be achieved using this fluoroscopic method. This method may prove to be a simple but effective method of estimating intraoperative ALO.

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.

Femoral Stem Fracture and Successful Reimplantation Using Femoral Window Technique in Canine Cemented Total Hip Replacement: Case Report

A fractured stem is a very rare, late complication in total hip replacement procedure in dogs. Here, we present one case after cemented total hip replacement with successful reimplantation, including clinical signs and radiographic findings.

Zürich cementless total hip arthroplasty as a treatment option for capital physeal fractures in dogs: Outcome in 53 cases

OBJECTIVE

To review the outcome of dogs that underwent Zürich cementless total hip arthroplasty (Z-THA) for the repair of acute and chronic capital physeal fractures (CPF) and document the CPF-related hip remodeling.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

Fifty-three Z-THA in 53 dogs.

METHODS

Medical records of dogs (2006-2019) that underwent Z-THA for CPF management were reviewed. Dogs were divided into two groups on the basis of the days elapsed between CPF diagnosis and Z-THA, acute (≤30 days) and chronic (>30 days). Hip remodeling variables were determined from preoperative radiographs or intraoperatively. Descriptive statistics were performed, and the complication rates, outcome, and coxofemoral remodeling were recorded. Comparisons of remodeling variables and rates between groups were performed by using Fisher's exact test.

RESULTS

In total, 23 of 53 (43.4%) cases were acute, and 30 of 53 (56.6%) cases were chronic. There was no difference in the femoral remodeling rates between the acute and chronic groups (P = .184), whereas acetabular remodeling was more prevalent in the chronic group (P < .001). Intraoperative complications occurred in four of 53 (7.5% [1/23 acute, 3/30 chronic]) cases, and postoperative complications occurred in six of 53 (11.3% [2/23 acute, 4/30 chronic]) cases. Good clinical outcomes were achieved in 51 of 53 (96.2% [21 acute, 30 chronic]) cases.

CONCLUSION

Complication rates of Z-THA for CPF repair were similar to the complication rates reported for Z-THA of dysplastic hips. Hip remodeling was common regardless of CPF chronicity.

CLINICAL SIGNIFICANCE

Zürich cementless total hip arthroplasty is viable for surgical management of CPF. There is a high likelihood that hip remodeling will be encountered, even in fractures treated within 30 days of presenting for hind limb lameness.

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.