Slocum
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Course 2008
Sept 12-13th TPLO course now accepting registration. |
Canine Hip Classification By Barclay Slocum, DVM and Theresa Devine Slocum, MS Accurate diagnosis of the degeneration of the hip has long been an area of debate and creative thought in veterinary medicine. Physical examination, radiography and palpation have all contributed invaluable information to defining this process. The difficulty has been to determine the stage of degeneration of the hip joint in terms of acetabular filling, degeneration of the dorsal acetabular rim, articular cartilage integrity, and damage to the joint capsule. As experienced clinically, the degenerative process of the dysplastic hip has been divided into seven categories.
The first category is normal hip in which the femoral head remains congruently in the acetabulum at all times. No pathologic changes are present in this joint.
The second category is the subluxation of the hip in which the femoral head prefers to reside in the acetabulum but a lateral translation routinely occurs. This is an ideal case for a Femoral Neck Lengthening procedure and/or 20 degree Pelvic Osteotomy procedure or Minor DARthroplasty procedure. Normal function can be expected to return.
The third category is intermittent luxation of the hip in which the femoral head resides both in the acetabulum and the joint capsule with equal preference, but a lateral translation occurs with adduction. Significant damage to the joint capsule is usually present. This is an ideal case for a Femoral Neck Lengthening Procedure and/or 20-30 degree Pelvic Osteotomy procedure or a Minor DARthroplasty.
The fourth category is the reducible luxated hip in which the femoral head resides in the damaged joint capsule. The femoral head will easily return to the acetabulum during the combined contraction of the abductor, internal rotator and external rotator muscle groups, or abduction of the limb. The hip often "clunks" when the young dog walks. The pathological changes include early wear of the medial aspect of the femoral head, damage to the dorsal acetabular rim, damage to the joint capsule, beginning filling of the acetabulum with pannus and beginning acetabular osteophytes. In this case a Femoral Neck Lengthening procedure and a 20-30 degree Pelvic Osteotomy procedure or a Standard DARthroplasty will return the patient to normal function. The prognosis is good to fair, and near normal function is anticipated with the above treatment.
The fifth category is severe reducible luxation of the hip. In this chronic stage of the degenerative process of the hip joint, the femoral head will not return to the acetabulum unless the combined abductor, internal rotator and external rotator muscle groups are contracted, and the limb is abducted. This hip is not stable and will reluxate immediately. The pathological changes include definite wear of the medial aspect of the femoral head, damage to the dorsal acetabular rim, damage to the joint capsule and filling of the acetabulum with mature central acetabular osteophytes. A Femoral Neck Lengthening procedure or Femoral Neck Lengthening procedure and 30 degree Pelvic Osteotomy procedure will be of benefit to the patient. The efficacy of this reconstructive surgery is limited by the incongruency produced by the hypertrophy of the ligament of the femoral head and central filling of the acetabulum by osteophytes. The prognosis is fair to poor depending on how advanced the osteophytic process is in the central portion of the acetabulum. A Major DARthroplasty will provide good function to the patient provided that articular cartilage is present on the femoral head.
The sixth category is irreducible luxation of the hip. The femoral head resides within the joint capsule only, and cannot be replaced in the acetabulum. Although the femoral head can place in the approximate center of the acetabulum by using the power of the Pelvic Osteotomy and Femoral Neck Lengthening procedures, failure of the surgery is likely to occur. Failure of the Pelvic Osteotomy procedure will occur if the central acetabular osteophytes are mature and irregular, and produce eburnation of the cartilage of the femoral head by forced wear. Failure of the Pelvic Osteotomy procedure will occur if the femoral neck has large osteophytes with produce eburnation of articular cartilage of both the dorsal acetabular cartilage and lateral portion of the femoral head where it joins the articular cartilage of the osteophytes of the femoral neck. With eburnated articular cartilage a DARthroplasty will not provide relief of symptoms and return of function. If the acetabular osteophytes or the central acetabular osteophytes are severe, then the appropriate Total Hip Replacement is the only surgery which will return the patient to normal function. An excision arthroplasty of the femoral head cannot predictably return the patient to function indistinguishable from normal.
The seventh category is a dislocated hip in which the femoral head resides outside of both the acetabulum and the joint capsule. If the hip was normal prior to the trauma which produced the dislocation, then the hip can probably be returned to function indistinguishable from normal by use of the Slocum Sling, Single Suture technique, or Pelvic Osteotomy. The limitation in the return of function is fracture of the acetabulum, neurologic damage or destruction of the rotators of the hip. The dysplastic hip presents a diagnostic challenge to the veterinary orthopedist who must discriminate between the severe hip which is filled with mature acetabular osteophytes and has a damaged dorsal acetabular rim, and the less than severe case which has pannus and mild acetabular osteophytes. This distinction will determine whether the case will be successful.
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