UTILITY OF REPEAT ARTHROGRAPHY FOLLOWING CLOSED REDUCTION FOR DEVELOPMENTAL DYSPLASIA OF THE HIP: A RETROSPECTIVE ANALYSIS OF 60 HIPS

Closed reduction (CR) and spica casting is an established treatment for developmental hip dysplasia (DDH). While hip arthrograms are routinely performed at CR, they are not always repeated at spica change 4–6 weeks later. The aims of this study were to analyse changes in arthrographic parameters at spica change and assess whether they can predict outcomes. This single centre retrospective study included all hips managed by CR that underwent repeat arthrogram at spica change with minimum of six months’ follow-up. Arthrograms were performed following a standard technique, with injection of a fixed quantity of dye to allow meaningful comparison. Radiologic parameters were calculated as percentages of femoral head diameter to avoid magnification error. Sub-optimal outcomes were defined as re-dislocation, osteonecrosis and/or need for further surgery. Sixty hips (58 children, 90% female) treated over 10 years were eligible for this study. Mean age at CR was 10.75 months (range 1–32), and repeat arthrograms were performed on average 32.7 days (range 25–49) after CR. At mean follow-up of 3.7 years, 79% hips had satisfactory outcomes and 21% had sub-optimal outcomes (re-dislocation, osteonecrosis and further surgery in seven, five and 11 respectively). Repeat arthrograms demonstrated statistically significant improvements in bony and cartilaginous femoral head coverage, limbus morphology, capsular laxity, femoral head medialisation and medial dye pool. Inadequate improvement of femoral head bony coverage on repeat arthrograms was predictive of need for further surgery but did not reach statistical significance. We conclude that repeat arthrograms following CR demonstrate significant improvements in reduction quality but fall short of predicting outcomes.