Similar Outcomes between Monoblock and Modular Femoral Stems in Total Hip Arthroplasty with Shortening Osteotomy for Dysplastic Hips at Five Years: A Systematic Review with Meta-analysis.

We aimed to examine the outcomes of arthritic congenital dislocation of hip in adults after subtrochanteric shortening derotation osteotomy (SSDO) with cementless hip arthroplasty at a minimum follow-up period of five years. Bibliographic databases were searched and isolated studies were divided into three groups (1, 2, and 3) based on the femoral stem type (modular, monoblock, or mixed). We pooled 931 hips/737 patients from 20 studies. The mean difference in the Harris hip score (HHS) before and after the operation was 47.55 (95% confidence interval [CI] 43.16, 51.94). On subgroup analysis the mean differences of 46.59 (95% CI 41.67, 51.51), 48.24 (95% CI 41.37, 55.11), and 47.30 (95% CI 43.85, 50.75), respectively in HHS were noted in groups 1, 2, and 3. The incidence of uncontrolled proximal femur fractures was comparable at 7.9% and 4.2% in groups 1 and 2; however, it was 0% and 16.6% for controlled fractures. The incidences of nonunion, dislocation, nerve paralysis, heterotopic ossification and revision due to any cause were 0.3%, 6.5%, 1.7%, 2.1%, and 7.9% for group 1 and 1.9%, 4.3%, 1.6%, 5.6%, and 7.4% for group 2. Similar improvements in functional outcome for both monoblock and modular stems can be expected. An increased incidence of controlled proximal femur fractures was observed with use of modular stems. The nonunion at the SSDO site was sporadic.