Methods/results

49 patients with acetabular dysplasia treated by shelf procedure were reviewed retrospectively. Group 1 (19 children) and group 2 (12 adults) had shelf acetabuloplasty using autogenous bone graft and CaSO4. Group 3 (18 children) underwent shelf acetabuloplasty using autogenous bone graft alone. Group 2 was assessed separately to avoid age bias. Within group 3 we compared 10 patients managed in plaster for six weeks with 8 mobilized on crutches post operatively.

Total shelf and graft area, total shelf length, extra-osseous shelf length and speed of graft incorporation were measured radiologically.

There was no difference in shelf indices between patients treated in plaster and those mobilized on crutches.

Use of CaSO4 significantly enlarged shelf volume by 3 months post-operative with less resorption, which was maintained throughout follow-up. In contrast the non-CaSO4 group showed a steady decrease in shelf volume. The extra-osseous shelf length was initially similar in groups 1 & 3. By 6 weeks the group 1 extra-osseous shelf was significantly greater than for group 3 and was maintained throughout follow-up. Graft incorporation was faster in group 1.

Shelf area and extra-osseous shelf length improved significantly in group 2. However total shelf length decreased slightly by 6 months.