TREATMENT

RESULTS OF TOTAL KNEE ARTHROPLASTY IN OSTEONECROSIS OF THE KNEE

Mont, M.A.; Rifai, A.; Baumgarten, K.M.; Hungerford, D.S.
Johns Hopkins University School of Medicine; Department of Orthopaedic Surgery; Baltimore, MD

Introduction: There have been few published reports of the results of total knee arthroplasty in osteonecrosis. None of these studies have differentiated between secondary osteonecrosis and spontaneous osteonecrosis. This study examined the results of total knee arthroplasty in patients with secondary as well as spontaneous osteonecrosis.

Methods: Between Jan. 1, 1987 and Dec. 31, 1995, 26 cemented primary knee arthroplasties were performed in 23 patients who had a diagnosis of osteonecrosis were studied. There were 19 women and 4 men with a mean age of 55 years (range, 32 to 78). In the secondary osteonecrosis group all patients had used steroids and 11 of 19 patients had a diagnosis of systemic lupus erythematosus. In the spontaneous osteonecrosis group, no patients had used steroids and no other risk factors for osteonecrosis were identified. Clinical and radiographic information was collected on these patients at presentation and final follow up. A successful result was reported in patients with a Knee Society Score of 80 points or greater. Knees were evaluated radiographically for change of position of the prosthesis as well as progressive radiolucencies or any evidence of loosening.

Results: Twenty-five of 26 patients (96%) had a successful clinical outcome at a mean follow up of 93 months (range 48 to144 months). Radiographically, no progressive radiolucencies or change in position of the prosthesis was noted. The only failure was noted in a patient with secondary osteonecrosis who had a revision for pain and instability with no aseptic loosening.

Discussion and Conclusion: Most studies have reported less than optimal results in patients with spontaneous or secondary osteonecrosis. Most of these reports were on first generation cemented or cementless total knee replacements. None of these reports differentiated between secondary and spontaneous osteonecrosis. In the present study, the use of second generation cemented prosthetic designs after 1986 have led to excellent results in both groups of patients with osteonecrosis of the knee.