Abstract
Introduction: Stable cup anchorage in dysplastic hips is a key problem of THA. The pupose of this study was to evaluate the usefulness of a cementless cup without acetabuloplasty based on medium term Results: Method 53 patients, 47 females and 6 males aged 20 to 76 (mean 49) years at surgery were followed-up after 4.9 to 11.4 (mean 8.8) years. Crowe’s dysplasia classification showed 30 hips to be grade I, 23 grade II and 1 grade III pre-operatively. All patients were implanted with threaded pure-titanium double-cone cups. Acetabuloplasty was omitted and care was taken to achieve primary stability in the bone stock available. Pre-operative leg length discrepancy versus contralateral was 0 to 7 (mean 3.9) cm.
Results: On postoperative radiography 45 cups were completely covered by bone in position I. Of 6 cups 3 quarters were covered, of 1 cup 2 thirds and of another one ½ of the cranial circumference. All of the incompletely covered cups were stable at follow-up. Altogether 51 cups had maintained their position by radiographic evidence and were firmly anchored in bone. Cup loosening in Crowe grade I and II necessitated 2 revisions. Leg length was equalized in 39 patients with mean lengthening by 3.4 (1.2 to 4.5) cm.
Conclusion: In the management of dysplastic hips the system used provides stable anchorage in the bone stock without additional acetabuloplasty. Even pronounced soft tissue tension on substantial leg lengthening does not impair implant stability.
Summary: Primary stable implantation of a cementless titanium cup in hip dysplastia cases without additional acetabuloplasty is achieving good medium term results.
Correspondence should be addressed to Ms Larissa Welti, Scientific Secretary, EFORT Central Office, Technoparkstrasse 1, CH-8005 Zürich, Switzerland
