Osteonecrosis of the femoral head associated with pregnancy - A preliminary report

Background Osteonecrosis is usually associated with trauma, use of corticos teroids, or alcohol abuse. We investigated the rare association of osteonec rosis of the femoral head and pregnancy, and we defined differences between the disorder in pregnant women and that in women of childbearing age who w ere not pregnant, The results of treatment with a free vascularized fibular graft were evaluated in terms of relief of pain and improvement of the Har ris hip score after a minimum of two years of follow-up. Methods: Thirteen women (seventeen hips) had the onset of pain in the hip d uring pregnancy or within the first four weeks after delivery, and the pain persisted until a diagnosis of osteonecrosis of the femoral head was made on the basis of magnetic resonance imaging. No patient had any other risk f actor for this disease. Information was obtained by means of clinical asses sment, a review of the records and radiographs, and a telephone survey. Ele ven women (fifteen hips) were managed with a free vascularized fibular graf t, and nine of them (eleven hips) were evaluated, with regard to relief of pain and the Harris hip score, at a minimum of two years postoperatively, Results: The average age when the pain began was 31.5 years (range, twenty- five to forty-one years). Eleven of the thirteen women were primigravid, an d the patients typically first had the pain late in the second trimester or in the third trimester of pregnancy. The women tended to have a small body frame and a relatively large weight gain during the pregnancy. Eight of th e thirteen patients had swelling and varicosity of the lower extremities. T he diagnosis was delayed an average of 10.3 months, with a range of three t o thirty months. A common misdiagnosis was transient osteoporosis of the hi p during pregnancy, A correct diagnosis was established for all hips on the basis of the finding of a double-density signal on magnetic resonance imag ing or evidence of progression of the dis-ease on plain radiographs, Accord ing the system of Marcus et al,, the stage at the time of diagnosis ranged from II to V, All women had involvement of the left hip, and four had bilat eral involvement. Of the eleven women (fifteen hips) who were managed with a free vascularize d fibular graft, nine noted marked or complete relief of the preoperative p ain. Two hips in a patient who had progressive pain were treated with a tot al hip arthroplasty, Two hips (one patient) were lost to follow-up, The nin e patients (eleven hips) who were available for follow-up at a minimum of t wo years had an average improvement in the Harris hip score of 24 points, Conclusions: Occasionally, pain in the hip that begins during pregnancy is caused by osteonecrosis of the femoral head. A high index of suspicion and use of magnetic resonance imaging may lead to an earlier diagnosis and a be tter prognosis in this population of women. In this study, treatment with a free vascularized fibular graft was a useful option with which to obviate or postpone the need for total hip arthroplasty.