Early and mid-term results of Tönnis lateral acetabuloplasty for the treatment of developmental dysplasia of the hip.

This study aimed to present the clinical and radiological results of a large patient group operated by Tönnis lateral acetabuloplasty (TLA) for developmental dysplasia of the hip (DDH). The retrospective study was conducted with 66 hips of 41 patients (5 males, 36 females; mean age: 32.3±18 months; range, 11 to 132 months) operated for DDH using the TLA technique in a single center between February 2012 and December 2016. Adductor tenotomy was performed on 52 (79%) hips. There was a need for additional femoral shortening and derotation-varization osteotomy in 14 (21%) hips. Clinical outcomes were evaluated with modified McKay criteria. The acetabular index and lateral migration index for the subluxated hip were calculated, and the femoral head position was evaluated according to Perkin's line and Shenton's line. The Severin classification was used to assess the outcome of the hips. The mean follow-up period was 27±11 months. According to the modified McKay criteria for DDH, 77.3% of hips were classified as excellent, 16.6% as good, and 6.1% as fair. The mean acetabular index decreased from 36.1° preoperatively to 18.6° postoperatively. The mean postoperative improvement for the acetabular index was 17.5±5. The lateral migration index improved from 89.7 to 10.6%. A statistically significant difference was determined between the preoperative and postoperative measurements of the acetabular index and lateral migration index (p<0.001). Tönnis lateral acetabuloplasty was found to be safe and effective with a low learning curve, and successful treatment decreases the duration of follow-up required in patients with DDH.