The femoral head and neck ostectomy.

163 W ith apologies to the bard, “I come not to bury the femoral head and neck ostec­ tomy, but to praise it! ” At the outset, let us clarify terminology; the surgical removal of the femoral head and neck resulting in the formation of a pseudoarthrosis between the cut surface and the aceta­ bulum has been referred to variously as an excision or excisional arthroplasty of the hip, a femoral head and neck excision, or a femoral head and neck ostectomy (FHO). Whatever the terminology, the orthopedic litera­ ture has been consistent about one thing when discussing the FHO: almost without exception, textbooks and journal articles refer to the FHO as a “salvage procedure” (1–6). The Winston Dictionary lists “salvage” as coming from the Latin “salvare,” which is “to save. ” It is defined as “to save, from a wreck, fire, or any other danger. ” The implication in the literature is that FHO should be per­ formed only as a last resort, when no other options are available, presumably “to save” the patient from eutha­ nasia (1). A review of the published clinical results with FHO, over the more than 4 decades that it has been in use (3,7), would suggest a high degree of success and owner sat­ isfaction with it. Indeed, far from just a “salvage proce­ dure,” there are several patients for whom the FHO is clearly the treatment of choice and few for whom it would be contraindicated. A survey of 127 owners whose dogs had undergone FHO indicated that there was a 93% satisfaction rate with the procedure (7). Another survey of 75 dog and cat owners whose pets had undergone FHO claimed that 95% of results were good or excellent (8). Results from these surveys and from our own practice indicate 4 main situations for the FHO procedure: Fractures of the femoral head, neck, or acetabulum, as well as chronic coxofemoral luxations, account for virtually all situations in the cat and a good number in the dog. In the dog, chronic hip dysplasia and Legg­Perthes disease account for up to one­third of cases (8). In our experience, 23 FHOs were performed on 21 animals aged 7 mo to 12 y and weighing 5.7 to 47 kg from May 1999 to March 2003. Of 12 cats in the group, mild lameness was reported in 1 cat after the postoperative rehabilitation period. Two of 11 dogs reported periodic lameness after surgery: 1 was a 24 kg rottweiler­cross, while the other was a 5.7 kg bichon frise. There is general agreement that many FHO patients do not have a completely normal gait in the operated hip and that this is more apparent in larger dogs. Whether this is reflective of chronic pain is far less clear. Rather, it would appear that the anomalous gait is due to a more pronounced craniodorsal displacement of the proximal femur during weight­bearing, which seems to be greater the more weight that must be supported (the larger the dog) (3,7–9). The joint that has been operated on is also “weaker,” as evidenced by decreased circumference of the quadriceps muscle in at least 50% of patients (7), periodic lameness after strenuous exercise, and, subjec­ tively, a lesser ability to jump, which is most common in large dogs. All of these observations are confirmed by force plate analysis, which shows a significantly decreased peak propulsive force in the hind limbs of FHO dogs (9). In other words, these dogs are just not able to push­off as vigorously with their hind limbs. Several factors have been identified as contributing to the success or failure of FHO in a given patient. The mantra that has been repeated almost as frequently as the label of “salvage procedure” intones that success rates decrease with increase in patient size. Some would go as far as to say that the procedure should be avoided in larger patients (1). The evidence does not support such a conclusion. While it is true that consistently excellent results can be expected in cats and small dogs and while there is no doubt that alteration in gait is more evident in larger dogs for the reasons we have outlined, it does not necessarily correlate with decreased function, and there has been no statistically proven link between suc­ cess rates and patient size (2–4,8). In small dogs with Legg­Perthes disease, FHO has long been the treatment of choice. The same may be true in small dogs and cats with chronic coxofemoral luxa­ tions or femoral head and neck, or acetabular, fractures. The justification for the use of other repair procedures is hard to find when the FHO consistently provides excellent results, few postsurgical complications, mini­ mal gait alterations, reduced surgical costs, a technique that can be readily mastered in private practice, and uncomplicated rehabilitation. Indeed, the FHO will fre­ quently be the best alternative in dogs up to 22 kg (3). Where patient size is concerned, the evidence suggests that lean body mass and activity level are the key factors. Active patients with good muscle tone and lean body Animal Clinic of Regina, 1800 Garnet Street, Regina, Saskatchewan S4T 2Z2. ORTHOPEDICS ORTHOPÉDIE