Effect of surgical approach on functional outcome and component positioning in total hip arthroplasty

Abstract

Context: Total hip arthroplasty (THA) is commonly performed through a posterior or a direct lateral (Hardinge) approach, and each one has merits and demerits. Aims: The purpose of this study was to examine the difference between the lateral and posterior approaches with respect to functional outcome, component positioning, intraoperative blood loss, and patient satisfaction. Settings and Design: This is a prospective comparative study of short- to mid-term outcome of cementless THA using two approaches. Subjects and Methods: Seventy hips satisfying our inclusion criteria were selected, of which 21 hips operated by lateral approach in supine position were included in lateral approach group (LAG), and 49 hips operated by posterior approach in lateral position were included in posterior approach group (PAG). Functional assessment was performed 1 day before surgery, 1 year after surgery, and at the latest follow-up using Harris Hip score (HHS). Component positioning of acetabular cup and femoral stem was assessed in plain radiographs at the latest follow-up. Generic satisfaction questionnaire was used to measure satisfaction after THA at the latest follow-up. Radiographic measurements (cup inclination, cup version, and femoral stem tip position) were performed postoperatively using low-centered pelvic anteroposterior and cross-table lateral hip radiographs. Results: At an average of 3 years and 6 months of follow-up, the mean HHSs were 88.05 and 90.32, respectively, in LAG and PAG; the difference was not significant (P = 0.178). The average inclination of the cup in LAG was 37.9° and in PAG was 45.02° with a significant difference (P = 0.00027), both of which are in the normal range. The cups were significantly (P ≤ 0.0001) more anteverted in the PAG (average angle of 27.69° vs. 16.14°). The mean blood loss was significantly more in PAG (510 ml vs. 436.67 ml; P = 0.04). Majority of femoral stems in lateral approach had their tips directed posterior. Nineteen out of 21 LAG patients and 45 out of 49 PAG were very satisfied/satisfied with their outcomes after THA. Statistical Analysis Used: Data were collected using prestructured data forms and analyzed with unpaired Student's t-test with 95% confidence interval. Conclusions: There was no significant difference in functional outcome and patient satisfaction at short- to mid-term follow-up between both approaches. The cup anteversion was significantly more in PAG. For better conclusions, other factors (i.e. immediate postoperative pain, and long-term survival), combined anteversion and spinopelvic parameters, have to be included in the study with a larger sample size.