ANTERIOR IMPINGEMENT OF THE FEMORAL HEAD IN PERTHES' DISEASE

MASAFUMI HOMMA, M.D.,D.M.Sc, Research Fellow of Orthopaedic Surgery

J. RICHARD BOWEN, M.D., Chairman of Pediatric Orthopaedic Surgery

April. 9,1996

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE:

F.T. is a 44 y. male. Perthes disease on the right hip.

The parents first noted at the time the patient was 10y and 9 m old that he would limp on the right side after a full day of activity. He also started to have a occasional hip pain. Since the hip pain became progressively worse, he visited local clinics and was referred to AIDI at the age of 11y and 3 m. At the first examination abduction was 40 degrees bilaterally but internal rotation was limited to 0 degree on the right. The leg lengths were equal and no Trendelenburg sign was observed. X-ray showed the decreased epiphyseal height and medial joint opening. Snyder sling was started. At 12 years of age, internal rotation was still limited 20 degrees compared to 35 degrees on the left side but the left hip pain was asymptomatic. At 13 years of age, X-ray showed the regenerated head, so the Snyder sling was stopped and weight bearing was started. The Snyder sling had been applied for 2 years. At 16 years of age, ten degrees limitation of internal rotation as compared to the opposite side was still observed but the patient was asymptomatic.

11 yrs 3 mos, , 12 yrs, 13 yrs 8 mos , 17 yrs , 18 yrs.

At 28 years of age, he had been having increasing pain in his right hip. He had a limp when he was tired. Positive Trendelenburg's sign was observed on the right. Internal rotation was limited to 25 degrees. All other motions were normal. X-ray showed cystic change. At the 29 years of age, he underwent bone graft of the right femoral head for degenerative cyst. At 35 years of age, only internal rotation was limited to 20 degrees. He still had pain in his hip that relates primarily to weather or to excessive walking. Only internal rotation was limited to 20 degrees. He had hip pain at the extremes of flexion and internal rotation. X-ray showed the progression of the cystic change. CT which was performed because of the question of loose bodies in the hip did not seem likely that the densities were actually in the hip joint. The antero-medial location of the cysts facing the anterior margin of the acetabulum was well depicted in CT.

28 yrs, 29 yrs, 30 yrs, 35 yrs .

DISCUSSION:

Snow S.W. et al. (A.I. duPont Institute) first reported four cases of this phenomenon in 1993. There were three boys and one girl. Age at onset ranged from 5+3 to 10 years (Table1. in the article).

DIAGNOSIS:

Clinical features:

• Symptom (hip pain) and sign (limitation of internal rotation and hip pain at maximum internal rotation or flexion) come late after the asymptomatic period.
• Asymptomatic period was averaged 6+8 years in the report. This particular case had fifteen years.

RADIOLOGICAL FEATURES:

• The joint space of weight bearing area is usually well preserved in antero-posterior view although the femoral head appears oval with marked flattening.
• Lateral view could demonstrate incomplete coverage of varying degree of the anterior portion of the femoral head.
• A depressed area similar to an osteochondritis dissecans was observed in two cases in the report. But no hip had evidence of loose bodies.
• The combined CT scan and arthrogram could demonstrate anterior impingement very well. The functional CT in internal rotation makes the definite diagnosis of this condition.

ARTHROSCOPE:

• Anterior impingement could be directly observed and diagnosed by internal rotation using an arthroscope.

TREATMENT:

• Arthroscopic removal of fragments and/or debridement of the impinged lesion could relieve the symptoms in the hip joint.
• Possible Osteotomy

POSSIBLE PATHOGENESIS:

• The necrotic lesion is always located anteriorly, which has potential risk to be impinged to the anterior acetabular margin in internal rotation.
• The pathological anteversion secondary to the growth plate injury could make the anterior extrusion of the femoral head worse.
• The reason of late occurrence of this phenomenon: Hinged abduction in antero-posterior view usually occurs in fragmentation or recovery phase. Anterior impingement occurs after these phases.

REFERENCES:

1. Snow S W, Keret D, Scarangella S, Bowen J R: Anterior impingement of the femoral head: A late phenomenon of Legg-Calve-Perthes' disease. J Pediat Orthop. 13: 286-289,1993.
2. Catterall S Q: Hinge abduction of the hip. J Bone and Joint Surg. 68-B:61-64,1986.
3. Gabos P G, Bowen J R: Hinge subluxation in Perthes disease. MAPFRE MEDICINA.6 supl. III: 237-242, 1995.
4. Green N E, Beauchamp R D, Griffin P P: Epiphyseal extrusion as a prognostic index in Legg-Calve-Perthes disease. J Bone and Joint Surg. 63-A: 900-905,1981.
5. Bowen JR, Kumar VP, Joyce JJ, Bowen JC: Osteochondritis dissecans following Perthes' disease. Arthroscopic-operative treatment. Clin Orthop. 209: 49 , 1986.