Implant fixation of primary total hip arthroplasty using a cementless cup for osteoarthritis secondary to developmental dysplasia of the hip: A prospective multicenter study in Japan

Purpose

This prospective multicenter study investigated the implant fixation of a cementless cup in primary total hip arthroplasty (THA) for osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) in Japanese patients.

Methods

Ten hospitals in Japan were enrolled in this study. The cohort comprised 267 hips in 228 Japanese patients who underwent primary THA for OA secondary to DDH. An acetabular cup with advanced in-growth, GRIPTION™ coating, was used in all patients. Mean age at surgery was 66.9 (range 45–89) years, and 201 patients (239 hips) were female. Of these patients, 89.1 ​% (238/267) was Crowe group I. Radiolucent lines around the cup, osteolysis, cup migration, grafted bone status, and clinical scores were evaluated preoperatively and at 6 months, 1 year, and 2 years postoperatively. Adverse events were evaluated throughout the study. Implant survivorship was assessed using the Kaplan–Meier method.

Results

Nine hips had radiolucent lines ≥2 ​mm that resolved by 6 months. All cups showed bone in-growth and no cups loosened. At 2 years, the bone grafts had remodeled and incorporated in 68 ​% (43/63) of hips. There were four systemic and five surgical site events, and one procedure-related dislocation. The survivorship with cup revision as the endpoint was 99.6 ​% (95 ​% confidence interval, 97.3–99.9). All clinical scores were improved at 2 years compared with preoperatively (p ​< ​0.01).

Conclusions

An advanced in-growth coated cup showed good fixation without complications in primary THA, even in patients with OA secondary to DDH.