PAST LETTERS FROM THE PRESIDENT
Jones, L.C.; Hungerford, D.S.; Khanuja, H.; Pietryak, P.; and Hungerford, M.W.
Introduction: In a previous study (ARCO, 2002), we reported that the clinical results for osteonecrosis patients were less satisfactory than those found for matched group of osteoarthritis patients. The aim of this study was to evaluate the potential factors that may have contributed to these findings.
Methods: This study included 34 hips in 30 osteonecrosis patients who had undergone revision of a femoral component of a prior THA. There were 19 males (22 hips) and 11 females (12 hips) with a mean age of 46.1 years (range, 28 to 69 years). The surgeries were performed between March 1984 and January 2001. Most femoral stems (91%) were implanted without cement. Prostheses were of different stem lengths, but most (97%)_ were proximally porous coated. The mean follow-up was 8.2 years [range, 0.1 (a re-revision) to 19.8 years]. A physical examination as well as patient and physician outcome forms were collected at each visit. Preoperative x-rays were categorized according to Della Valle & Paprosky. A Kaplan-Meier survival analysis was performed (PEPI statistical software package).
Results: Etiologic associations included 15 corticosteroid, 8 alcohol, 7 trauma, and 4 unknown. This was the first revision in 27 cases, 2nd in 5 cases, and 3rd in 2 cases. Preoperatively, the defects included 4 Type I, 9 Type II, 15 Type IIIA, 2 Type IIIB, 1 Type IV, and 3 unknown. Of the 34 hips, the femoral component was re-revised in 12 cases. One of the failures was the only fully porous coated stem that was implanted. One of the 3 cemented implants failed, as compared to 11 of the 31 implanted without cement. Survival rates were 90.9% (74.4%-97.1%) at 5 years, 54.8% (24.9%-81.6%) at 10 years, 54.8% (19.9%-85.6%) at 15 years, and 27.4% (1.7%-88.9%) at 20 years. There was no relationship between frequency of re-revision and defect category, etiology, or age.
Conclusions: Although there was a high failure rate (12/34; 34%) in this patient cohort, over 50% survived at least 10-15 years. The lack of a relationship between the patient age or the extent of defect and re-revision suggest that other factors concerning the disease need to be examined.