Outcome and Complications following Stabilization of Coxofemoral Luxations in Cats Using a Modified Hip Toggle Stabilization-A Retrospective Multicentre Study

OBJECTIVES

 The main aim of this study was to report the surgical technique, the complications and the clinical outcomes of the mini-Tight Rope system (mini-TR) for a modified hip toggle stabilization of coxofemoral luxation in cats.

STUDY DESIGN

 A multicentre retrospective study.

ANIMALS

 Thirty-two client-owned cats.

METHODS

 Medical records (2009-2017) of cats, which underwent stabilization of a coxofemoral luxation with the mini-TR and had at least a 3-month follow-up, were reviewed. The femoral tunnel diameter, the use of one or two FiberWire loops, perioperative complications and clinical outcomes were recorded. Follow-up information was obtained through clinical and radiographic examinations and an owner questionnaire.

RESULTS

 Thirty-two cats met the inclusion criteria. Concurrent injuries were present in 16 cats. A single or double loop mini-TR was used in 21 and 12 cats respectively. One double loop (1/12 cats) and four single loop (4/16 cats) sutures failed. Moderate-to-severe coxofemoral osteoarthritis developed in 14/27 cats. Owner questionnaires revealed excellent clinical outcomes.

CLINICAL SIGNIFICANCE

 Mini-TR with a double-stranded implant is recommended to decrease the risk of suture failure. Osteoarthritis is common after open reduction of hip luxations.

Surgical Stabilisation of a Coxofemoral Luxation in a Northern Goshawk (Accipter gentilis) with Transarticular Pinning

A 3-year-old male northern goshawk (Accipiter gentilis) used in falconry for hunting was diagnosed with a craniodorsal coxofemoral luxation of the left leg after an unsuccessful hunting flight. Closed reduction in the dislocation was unsuccessful and the hip joint reluxed again with slight abduction of the limb. An open surgical reduction with a transarticular stabilization using a normogradely inserted Kirschner wire was performed. The implant was removed surgically after five weeks. After about seven weeks, the owner saw no abnormalities in the loading of the limbs, and the goshawk was successfully used for hunting after nine months in the next hunting season.

Validation of a biomechanical testing protocol of craniodorsal hip luxation in feline cadavers and comparison of two ultra-high molecular weight polyethylene materials used for extra-articular hip stabilisation

OBJECTIVES

The aim of our study was to describe a biomechanical testing protocol to reproduce ex vivo craniodorsal hip luxation specific to the feline model, and evaluate the biomechanical properties of an intact hip joint compared with the fixation strength of two different techniques of extra-articular hip stabilisation.

METHODS

Eighteen hip joints (femur and hemipelvis) were harvested from nine mature feline cadavers. CT was performed for each hip joint so that a biomechanical base specific to each joint morphotype could be created using computer-aided design. The biomechanical bases were then produced using a three-dimensional printer to secure the hip joints during testing. A total of 34 biomechanical compression tests were performed. Eighteen compression tests were performed in the control group, of which two fractured. The remaining 16 hip joints were then randomly assigned either to group A (hip joints stabilised with an extra-articular ultra-high molecular weight polyethylene (UHMWPE) implant secured by an interference screw [n = 8]) or to group B (hip joints stabilised with a UHMWPE iliofemoral suture [n = 8]).

RESULTS

Mean ± SD yield, failure load and linear stiffness in the control group were 616 ± 168 N, 666 ± 158 N and 231 ± 50 N/mm, respectively. The relative fixation strength (% of intact joint) before hip luxation in groups A and B was 43.8% and 34.7%, respectively. No statistical difference was found between groups A and B for yield and failure load. However, the reoccurrence of craniodorsal hip luxation was higher in group B than in group A, in 5/8 and 0/8 tests, respectively. Moreover, in group A, the extra-articular UHMWPE implant induced caudodorsal hip luxation, reported as failure mode in 7/8 cases.

CONCLUSIONS AND RELEVANCE

This modified biomechanical protocol for testing craniodorsal hip luxation in a feline model was validated as repeatable and with acceptable variance. The extra-articular UHMWPE implant stabilisation technique proved to be more efficient in avoiding reoccurrence of craniodorsal hip luxation than UHMWPE iliofemoral suture.

Traumatic Coxofemoral Luxation in Cats Treated with Hip-Toggle Stabilization Using the Mini Tightrope® Fixation System

The aim of this retrospective study was to evaluate the clinical and radiographic outcomes of 21 cats that underwent coxofemoral toggle stabilization using the Mini TightRope® Fixation System (mTR®). Data were compiled from client-owned cats with traumatic hip luxation. Each cat underwent the same protocol including orthopedic assessment, preoperative radiographic evaluation, surgical procedure, postoperative management and clinical re-examination at 14 days, 8 weeks and 12 months following surgery. Age, body weight, implants and osteoarthritis progression were recorded. A lameness score 0-4 was assigned to each cat. Pain upon hip extension was not quantified but as pain reaction or no pain reaction. Major complications and osteoarthritic (OA) changes were recorded. Osteoarthritic changes were classified on a 0-4 scale. Twenty-one cats were included in the study. Coxofemoral luxations were stabilized using a mTR®. At 8 weeks, weight bearing was considered normal (grade 0) in all cats and no pain reaction was elicited during hip extension. One year after surgery, orthopedic examination was within the normal limits and according to the owners, all animals exhibited a normal physical activity. No complications were recorded. Evidence of slight OA changes were observed in 5 out of 21 cats. The final outcome was considered excellent in 16/21 patients and good in 5/21 cats. The application of the mTR® system can be considered a suitable surgical treatment in cats affected by traumatic hip luxation.

Outcome of coxofemoral luxation treated with closed reduction in 51 cats

OBJECTIVES

The aim of this study was to describe the outcomes and determine the reluxation rate of cats undergoing closed coxofemoral joint reduction, and to investigate potential risk factors for reluxation of the affected coxofemoral joint.

METHODS

Case information was obtained from electronic medical records from Ocean State Veterinary Specialists and Bay State Veterinary Emergency and Specialty Services between January 2008 and May 2020. Data obtained from 51 cats with coxofemoral joint luxations included patient signalment, direction of coxofemoral joint luxation, concurrent injuries, ease of reduction, time of injury to closed reduction, bandage application and outcome. Data were analyzed for association with outcomes.

RESULTS

Closed reduction of coxofemoral joint luxation in cats had a 51% success rate. The only risk factor demonstrating a statistically significant benefit to the success of closed coxofemoral joint reduction was the application of a bandage (P = 0.02).

CONCLUSIONS AND RELEVANCE

It may be worth attempting closed coxofemoral joint reduction in cats prior to recommending surgery. Placing a bandage (Ehmer or hobbles) after closed reduction may decrease the risk of the coxofemoral joint reluxating, but more studies are needed to evaluate this further. The outcome after closed reduction management for coxofemoral joint luxation in cats is similar to the previously reported success rate in dogs.

Successful Treatment of Acute Craniodorsal Coxofemoral Luxation in a Scarlet Ibis (Eudocimus ruber) Using Closed Reduction and a Modified Ehmer Sling

Whereas craniodorsal displacement of the coxofemoral joint is the most common luxation reported in small and large mammals, it occurs less often in avian species. Closed reduction and external coaptation with a modified Ehmer sling is the initial treatment, in most cases, for small animals (eg, dogs, cats) that present with a coxofemoral luxation. However, the Ehmer sling is reported to have a low success rate in treating coxofemoral luxations in these animals. Intractable coxofemoral luxations require an open surgical reduction. A few successful closed reductions of coxofemoral luxations have been reported in avian patients, as well as open reduction surgical techniques to repair avian coxofemoral luxations. The successful treatment of an acute craniodorsal coxofemoral luxation in a scarlet ibis (Eudocimus ruber) with a closed reduction and a modified Ehmer sling is described in this clinical report. The specific characteristics of both the patient and the injury are thought to have contributed to the success in this case.

Complications and outcomes of cats with coxofemoral luxation treated with hip toggle stabilization using ultrahigh-molecular-weight-polyethylene or nylon (2009-2018): 48 cats

OBJECTIVE

To report overall rate and type of complications and outcomes of cats with coxofemoral luxation managed with hip toggle stabilization (HTS), to compare rate of postoperative complications and outcomes of cats treated with ultrahigh-molecular-weight-polyethylene (UHMWPE) or nylon, and to identify risk factors for reluxation and non-excellent outcomes.

STUDY DESIGN

Multi-institutional retrospective cohort study.

SAMPLE POPULATION

Forty-eight client-owned cats.

METHODS

Medical records of cats that underwent HTS from 2008-2018 using UHMWPE or nylon were reviewed. Univariable and multivariable logistic regression was performed to assess for factors associated with reluxation and non-excellent outcome. Final outcome was obtained from owner questionnaire.

RESULTS

Intraoperative and postoperative complications were recorded in two (4.2%) and 11 (24.4%) cats, respectively. The most common postoperative complication was reluxation (n = 5 [11.1%]). Outcome was classified as excellent in 81.1% and good in 16.2% of cats after a median of 445.5 days (range, 53-3720). No difference in rate of complications or outcomes was identified between UHMWPE and nylon. Performance of additional orthopedic procedures, occurrence of intraoperative complications, and non-performance of capsulorrhaphy were associated with reluxation. Performance of additional non-hip procedures (orthopedic/nonorthopedic) was associated with non-excellent outcome.

CONCLUSION

Hip toggle stabilization was associated with a low rate of intraoperative complications and reluxation and excellent long-term outcomes in most cats. No difference in rate of postoperative complications or outcomes of cats treated using UHMWPE or nylon was identified. Cats that underwent additional orthopedic procedures had greater risk of reluxation.

CLINICAL SIGNIFICANCE

Hip toggle stabilization is an effective technique for management of coxofemoral luxation in cats. Comparable results are expected using UHMWPE or nylon.

Traumatic joint luxations in cats: Reduce, repair, replace, remove

PRACTICAL RELEVANCE

Traumatic joint luxations are usually associated with significant trauma and there may be concomitant systemic injury. Joints are unstable as a result of injury to one or more supporting structures and the clinician should aim to determine which structures are damaged with physical examination, diagnostic imaging and careful assessment under sedation/anaesthesia. The aim is to reduce the joint back to its anatomical position, and then to maintain this through repair of damaged structures. However, where this is not possible, replacement or removal (arthrodesis/excision arthroplasty) of the joint remain viable options.

CLINICAL CHALLENGES

Owing to the small size of feline joints and the severity of damage often seen, surgical management of these cases can be challenging. The first priority is to ensure the patient is systemically well before embarking on any specific surgical treatment of a luxated joint. Cats also present challenges in the postoperative period and a lack of patient and owner compliance can be detrimental to postoperative outcomes.

AIMS

This article aims to help the reader diagnose joint luxations and to assist decision-making with an overview of the management and treatment options available.

EVIDENCE BASE

There are a number of original articles and textbook chapters in the literature covering aspects of different joint luxations, particularly for the more common luxations. This article draws on information from key feline research and, where necessary, extrapolates from relevant canine research. The authors also offer practical guidance based on their own clinical experience.

Coxofemoral Joint Luxation in Dogs Treated with Toggle Rod Stabilization: A Multi-Institutional Retrospective Review with Client Survey

Coxofemoral luxation is the most common type of joint luxation observed clinically in dogs. This retrospective study determines the complications and outcomes of open reduction and internal fixation of coxofemoral luxations using a toggle rod stabilization in 58 dogs. The purpose of the study was to compare the results with previous studies to ascertain commonalities and differences. A majority of the canine luxations were stabilized using a 4.0 or 3.2 mm commercial toggle rod and either one or two strands of OrthoFiber, FiberWire, or monofilament nylon suture. Postoperative complications developed in 25 of the 58 (43%) dogs, with major complications in 9 cases (15.5%). The most common major complication was reluxation, which occurred in 6 dogs (10%). Five of the 6 cases of reluxation received monofilament suture, although there was not a statistically significant relationship between suture type and reluxation. Owner responses to a questionnaire reported good to excellent results for satisfaction with the procedure in 90% of cases. Results of the present study suggest that toggle rod stabilization remains an effective method for the treatment of coxofemoral joint luxation in dogs.

Correction of craniodorsal coxofemoral luxation in cats and small breed dogs using a modified Knowles technique with the braided polyblend TightRope™ systems

Objectives: To report the surgical technique and short-term radiographic and functional outcome data for a series of client owned, small breed dogs and cats treated for traumatic craniodorsal coxofemoral luxation using open reduction and internal fixation with the Arthrex Mini TightRope (mTR) and TightRope (TR) systems.

Methods: Data were collected retrospectively from the clinical case records, including the initial clinical and radiographic findings, surgical technique, and postoperative short-term clinical and radiographic data. Functional data collected after the six weeks reassessment were obtained via owner questionnaire.

Results: Four cats (mTR = 4) and five small breed dogs (mean weight 15 kg; TR = 4, mTR = 1) were included. Median time to postoperative weight bearing was one day. Median lameness score at six weeks postoperatively was 0 out of 5. Coxofemoral joint congruity was radiographically confirmed at the six weeks postoperative visit. Telephone follow-up (at a median of 16 weeks) revealed all animals had returned to their previous level of activity. Complications were minor, and limited to postoperative swelling (n = 1).

Clinical significance: Clinical use of the Arthrex Mini TightRope™ and TightRope™ systems can be recommended for traumatic craniodorsal coxofemoral luxation in this novel application as short-term results are at least comparable to existing surgical techniques. Long-term follow-up studies are needed.

Minimally invasive technique for coxofemoral luxation stabilisation using transarticular toggle system: a cadaveric study

OBJECTIVE

To present a novel, semi-closed, surgical technique for coxofemoral luxation stabilisation using a transarticular toggle rod.

STUDY DESIGN

Cadaveric study.

MATERIALS AND METHODS

Craniodorsal luxation was generated by transecting the ligamentum teres in 12 coxofemoral joints and was then reduced using a closed technique. Anteversion and inclination angles were measured using fluoroscopic projections. An arthroscope was inserted through a bone tunnel drilled from the third trochanter through the femoral neck. Following retraction of the arthroscope, a hole was drilled through the acetabular fossa via the femoral bone tunnel. A standard Arthrex® TightRope toggle button was pushed through the femoral bone tunnel into the acetabular fossa hole and tied over the oval metallic button above the third trochanter site. The exit point of the drill hole over the femoral head and that in the acetabular fossa were evaluated by surgical exposure of the coxofemoral articular surfaces.

RESULTS

The TightRope entrance point into the acetabular fossa was accurate in all joints, with a mean distance from the acetabular fossa centre of 0·06 ±0·1 mm. The measured distance of the TightRope exit point from the femoral head to the fovea capitis was 2·04 ±1·7 mm. Femoral head cartilage damage was detected in nine of 12 joints.

CONCLUSION AND CLINICAL RELEVANCE

Closed reduction and stabilisation of coxofemoral luxations can be achieved using this minimally invasive technique. Refinements to the technique may be needed for its application in clinical cases due to relative high incidence of femoral head cartilage damage.