What Is Your Diagnosis?

Thomas O'Brien Pferdeklinik Bern, Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland.

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Christoph Koch Pferdeklinik Bern, Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland.

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 Dr Med Vet, DACVS
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Michael A. Livesey Department of Surgical Sciences, Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706.

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 BVM&S, MSc, DACVS

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History

An 8-year-old Saddlebred gelding was referred for further evaluation of severe right hind limb lameness of 8 weeks' duration. A preceding traumatic event could not be determined, and a favorable response to conservative management, which included stall rest and treatment with phenylbutazone (4.4 mg/kg [2 mg/lb], PO, q 24 h), was observed. However, the degree of lameness returned to original severity within 48 hours after discontinuation of anti-inflammatory medication. Radiographic examinations of the right stifle joint and tarsus, performed following the onset of lameness, were unremarkable.

On initial evaluation, the gelding had a grade 4 of 5 lameness1 and severe atrophy of the gluteal muscles of the right hind limb. The affected limb was held in adduction with mild outward rotation of the toe and stifle joint, and flexion of the affected limb was strongly resisted. Crepitus, in the region of the right hip joint, was both palpable and audible when the gelding was rocked from side to side. No further localizing signs were evident, and the rest of the physical examination findings were unremarkable.

Because of the degree of lameness, the static and chronic nature of the lameness, and the negative results of previous imaging studies, nuclear scintigraphy of the pelvis and hind limbs was performed while the horse was sedated and standing. Increased radiopharmaceutical uptake at the level of the right hip joint was observed on nuclear scintigraphy. Digital radiography was then performed with the horse in dorsal recumbency under general anesthesia to obtain radiographs of the areas of increased radiopharmaceutical uptake (Figure 1).

Figure 1—
Figure 1—

Ventrodorsal radiographic view of the right hip joint of an 8-year-old Saddlebred gelding referred for further evaluation of severe right hind limb lameness of 8 weeks' duration. The patient was in dorsal recumbency and under general anesthesia during imaging.

Citation: Journal of the American Veterinary Medical Association 240, 9; 10.2460/javma.240.9.1059

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Radiographic Findings and Interpretation

Digital radiography of the right hip joint, performed while the horse was in dorsal recumbency under general anesthesia, revealed incongruity of the articular surface of the caudodorsal aspect of the femoral head (Figure 2). Two articular steps (one at the fovea of the head of the femur and the other further caudally, halfway between the fovea and the caudal margin of the curvature of the head of the femur) are seen. The steps are connected by 2 radiolucent lines that converge to form an almost equilateral triangle, and this wedge of bone appears displaced. Secondary degenerative joint disease is not evident radiographically. Although orthogonal views of this area are not possible, considering our clinical, nuclear scintigraphic, and radiographic findings, a diagnosis of an avulsion fracture of the insertion of the round ligament of the head of the femur was made.

Figure 2—
Figure 2—

Same radiographic image as in Figure 1. A displaced, triangular, intra-articular fragment (arrows) extending caudally from the fovea of the head of the femur is appreciable.

Citation: Journal of the American Veterinary Medical Association 240, 9; 10.2460/javma.240.9.1059

Comments

Stability of the hip joint is maintained by a number of ligaments, the largest and strongest of which is the round or accessory ligament of the head of the femur.2 Severe trauma, such as a violent fall during which the entire limb is extended with or without hip joint luxation, may result in disruption of this ligament.3 Following disruption of the round ligament, the resulting marked instability of the hip joint is primarily responsible for the clinical signs.3

Clinical signs that characterize disruption of the round ligament of the head of the femur are limb adduction with outward rotation of the toe and the stifle joint. Similar signs also characterize hip joint luxation, but in those cases, a disparity in hind limb length is obvious. Crepitation over the joint is due to either joint instability or severe degenerative joint disease, which develops secondary to the instability. In cases of chronic hip joint disease, severe gluteal muscle atrophy develops and limb manipulation is resented.3

Avulsion fractures of the insertion of the round ligament have been reported for horses. Reports4,5 in other species recommend arthroscopic removal of smaller fragments (less than one-third the size of the femoral head), and a favorable outcome is reported. Typically, horses with complete rupture of the round ligament of the head of the femur remain chronically lame, and the diagnosis is associated with a poor prognosis.3 Although arthroscopic examination of the hip joint has been described, successful debridement of lesions involving the round ligament is restricted to smaller patients. Effective treatment of complete rupture and avulsion fracture of the round ligament of the head of the femur in a mature horse, through arthroscopic debridement and removal of avulsed fragments, would be challenging, if not impossible.

In the horse described in the present report, the owners elected further conservative management, but because of progressive deterioration in clinical signs, the horse was euthanized shortly thereafter. Postmortem examination of the hip joint at that time confirmed the diagnosis and revealed severe secondary degenerative joint disease of the hip joint.

  • 1.

    Ross MW. Movement. In: Ross MW, Dyson SJ, eds. Diagnosis and management of lameness in the horse. Philadelphia: WB Saunders Co, 2003;6073.

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  • 2.

    Budras KD, Sack WO, Rock S. Synovial structures of the pelvic limb. In: Anatomy of the horse. 5th ed. Hannover, Germany: Schlutersche GmbH & Co KG, Verlag und Druckerei, 2003;2627.

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  • 3.

    Hendrickson DA. The coxofemoral joint. In: Stashak TS, ed. Lameness in horses. 5th ed. Philadelphia: Lea & Febiger, 2001;10371043.

  • 4.

    Simpson DJ, Lewis DD. Canine femoral fractures. In: Slatter D, ed. Textbook of small animal surgery. 3rd ed. Philadelphia: WB Saunders Co, 2003;20592089.

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  • 5.

    Kusma M, Jochen J, Dienst M, et al. Arthroscopic treatment of an avulsion fracture of the ligamentum teres of the hip in an 18-year-old horse rider. Arthroscopy 2004; 6:6466.

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