Coxofemoral Luxations in Dogs and Cats

Introduction

Hip luxation accounts for 90% of all joint luxations in cats and dogs, often secondary to vehicular trauma.  Craniodorsal luxation is most common (caudo-ventral luxation is relatively rare), making the affected limb appear shorter, the stifle rotated laterally, and the calcaneus medially. Diagnosis involves palpation and plain orthogonal radiographs of the pelvis (assess for underlying hip dysplasia, secondary osteoarthritis, avulsion fracture associated with the origin/insertion of the round ligament). A discussion can now take place with the owner regarding appropriate treatment options and the likelihood of their success.

Treatment

1. If there is no or minimal underlying hip dysplasia (decent amount of acetabular depth, normal femoral head and neck, on the non-affected side), and no boney fragment within the joint, closed reduction is an option. Ideally, this should be performed under general anesthesia (not just sedation) and within 48 hours of the original injury. Owners should be informed that reluxation has been reported in more than 50% of cases with closed reduction alone. Augmentation with an Ehmer sling is an option, but still, reluxation rates with a sling have been reported from 15% to 71%. Reluxation rates are highest if the sling is placed more than five days after the luxation, and forget about placing an Ehmer sling on a cat!
2. If there is an avulsion fragment within the joint, or if the owner wants to increase the odds of success, open reduction should be performed. Toggle pin (or toggle rod) is a frequently used intra-articular technique that augments the reduction by replicating the torn round ligament. At the same time, the torn joint capsule can be defined, repaired, and imbricated. An 11% reluxation rate was reported in one study of 62 dogs. In another, reluxation was significantly more likely in dogs with acetabular or femoral fractures, preexisting hip osteoarthritis, or caudoventral luxation, compared with those with uncomplicated craniodorsal luxations. Toggle pin can enable earlier return of function and weight bearing; however, strict rest is required for four weeks post-surgery, since unsupervised, excessive activity is a known risk factor for failure.
3. If the hip is dysplastic, in the absence of secondary osteoarthritis, theoretically, a double or triple pelvic osteotomy may be an option in combination with open hip reduction; however, this would be an extremely unusual scenario. Hip dysplasia leading to hip luxation, secondary to more minor trauma, is often characterized by a particularly shallow acetabulum that usually negates a DPO or TPO as a valid surgical option.
4. If the hip is dysplastic and has significant secondary osteoarthritis, closed or open reduction will prove problematic. In these cases, discussion should include options for femoral head and neck ostectomy (FHO) or total hip replacement (THR). Although FHO is commonly considered a primary surgical option, particularly in small dogs and cats following traumatic hip luxation, a study in cats one year after FHO returned to a long-term residual gait abnormality that could be detected using a pressure-sensitive plate — but not always with an orthopaedic examination — even when owner satisfaction was good. Other studies have suggested persistent muscle atrophy in 50–82% of FHO cases greater than a year post-op and an abnormal gait in 30–88% of cases. Given the option for total hip replacement to include small dog breeds and cats, THR should be a consideration (cost notwithstanding) for a dog or cat with traumatic luxation of a dysplastic/osteoarthritic hip.

References

1. Demko JL, Sidaway BK, Thieman KM, et al. “Toggle rod stabilization for treatment of hip joint luxation in dogs: 62 cases (2000–2005).” J Am Vet Med Assoc. 2006;229:984.
2. Engstig M, Vesterinen S, Morelius M, Junnila J, Hyytiäinen HK. “Effect of Femoral Head and Neck Osteotomy on Canines’ Functional Pelvic Position and Locomotion.” Animals (Basel). 2022 Jun 24;12(13):1631.
3. Evers P, Johnston GR, Wallace LJ, et al. “Long-term results of treatment of traumatic coxofemoral joint dislocation in dogs: 64 cases (1973-1992).” JAVMA. 1997;210(1):59-64.
4. Garnier P, Cabon Q, Collard C, Guillaumot P, Dembour T. “Outcome and complications following modified prosthetic capsule technique for treatment of craniodorsal hip luxation in dogs.” Can Vet J. 2023 Aug;64(8):758-764.
5. Schnable-Feichter E, Schnabl S, Tichy A, Gumpenberger M, Bockstahler B. “Measurement of ground reaction forces in cats 1 year after femoral head and neck ostectomy.” J Feline Med Surg. 2021 Apr; 23(4) 302-309.