Functional Outcomes of Cementless Total Hip Arthroplasty in Avascular Necrosis of the Hip: A Prospective Study

Introduction

Avascular necrosis occurs due to impaired blood supply to the bone. It can be caused by fractures, dislocations, chronic steroid use, chronic alcohol use, coagulopathy, congenital source, and many other factors. It mostly affects the femoral head (hip joint). Its management can be conservative or invasive. Total hip arthroplasty is the treatment of choice for third and fourth stage avascular necrosis that can be cemented or uncemented. The purpose of this study is to access the functional outcomes of cementless total hip arthroplasty in patients with avascular necrosis of the hip.

Materials and methods

This prospective study was conducted at a major metropolitan hospital in Karachi, Pakistan over a period of six months. A total of 30 patients of age <60 years, either gender, and a confirmed diagnosis of avascular necrosis of hip with no other associated hip pathologies were included in this study. Demographic features, comorbidities, level of activity, range of movement before the development of avascular necrosis, Charnley’s class, and laterality were noted. Cementless press-fit extensively porous-coated acetabular cup with or without cancellous screws and cementless press-fit extensively hydroxyapatite coated femoral stem were used through modified Gibson’s posterior approach. The patients were checked for early and late complications, the position of acetabular and femoral components by radiography, and overall performance by Harris Hip Score (HHS) and modified HHS over a period of 12 months. All statistical analyses were performed using Statistical Package for Social Sciences (SPSS) version 19.0 (IBM Corp, Armonk, NY).

Results

The mean age was 43.9±6.7 years with 21 (70%) patients ranging from 40 to 60 years of age. There were 22 (73%) male and 8 (27%) female patients. Nine (30%) patients had diabetes mellitus, eight (27%) had hypertension, two (7%) had other comorbidities, and eleven (37%) had no comorbidities. A total of 11 (37%) patients were highly active, 18 (60%) were moderately active, and 1 (3%) was non-active before developing avascular necrosis. There were 4 (13%) patients in Charnley’s class I, 15 (50%) in Charnley’s class II, and 11 (37%) in Charnley’s class III. Fifteen (50%) patients were operated on the left side, seven (23%) on the right side, and eight (27%) bilaterally. No significant early or late complications were noted. Acetabular component was found to be anteverted in 22 (73%), retroverted in zero (0%), neutral in 8 (27%), <35^o inclined in 0 (0%), 35^o-50^o inclined in 23 (77%), and >50^o inclined in 7 (23%) patients, while femoral component was found neutral in 28 (93%), valgus in 2 (7%), and varus in zero (0%) patients on radiography at follow-up. On functional assessment, the HHS was 100% in 27 (90%) patients, 96% in 2 (7%) patients, and 83% in 1 (3%) patient with an average of 99.2%, while 29 (97%) patients had excellent and only 1 (3%) patient had a good outcome on modified HHS.

Conclusions

Cementless total hip arthroplasty, performed in patients <60 years of age and avascular necrosis of the hip with no other associated hip pathologies, has excellent functional outcomes with no pain, limping, physical deformity, difficulty in walking, difficulty in climbing stairs, difficulty using public transport, difficulty in sitting, or difficulty in wearing shoes and socks. They usually attain normal limb length and range of movement.