912 An Evaluation of Outcomes in G7 Dual Mobility Cup Arthroplasty for Primary Total Hip Arthroplasty: A Single Centre Retrospective Study

Background

Hip instability is one of the commonest complications of total hip replacement (THR) and remains a leading indication for revision surgery. The G7 Dual Mobility Cup (G7-DMC) was designed to improve hip stability and increase range of movement. Our study aims to look at the use of G7-DMC in patients with varying risk of dislocation, to observe rates of hip instability, as well as their short and long term post-operative outcomes.

Method

Between 2017 and 2021, 177 patients received a G7-DMC for primary hip arthroplasty. These patients were divided into three groups: elective surgery with low risk for dislocation, elective surgery with high risk of dislocation or THR for trauma. Outcome measures included dislocation rate, Oxford Hip Score (OHS), short- and long-term complications and revision surgery.

Results

One traumatic dislocation (1.9%) was seen in the high-risk group following a fall in the post-operative period, no dislocations were seen in the low-risk or trauma groups. No patients required revision surgery for dislocation or hip instability.

OHS was significantly lower in the high-risk group (39.4 +/- 8.9) compared with low-risk (43.5 +/- 6.5) (P = 0.012), however no significant difference was seen against the trauma group (41.5 +/- 7.8). Long-term complications were similar in all three groups.

Conclusions

Despite higher rates of short-term complications and poorer OHS seen in the high-risk group of patients, no spontaneous dislocation or revision surgery for hip instability has been seen in any of the three groups. We therefore support its use in primary THR, particularly in those with high risk of dislocation.