Smith c/b ratio and teardrop figure measurements; Can it be used in the follow-up of patients who underwent salter innominate osteotomy?

Background: This study aimed to investigate the effectiveness of radiological parameters used in the follow-up of patients who underwent salter innominate osteotomy (SIO) for the treatment of developmental dysplasia of the hip.

Methods: Acetabular index, c/b ratio, teardrop width, femoral head teardrop distance (TDD), and acetabular teardrop angle were measured on anteroposterior pelvic radiographs of patients who underwent SIO between 2017 and 2020. The patients were divided into 2 groups according to their preoperative Tönnis stage. Twenty-five (51%) hips of 23 patients with Tönnis stage 2 were classified into group 1, and 24 (49%) of 17 patients with Tönnis stages 3 and 4 were classified into group 2. Changes in radiologic parameters over time and between the groups were statistically evaluated.

Results: The study included 49 hips of 40 patients (37 female and 3 male). The age at surgery was 26.53 (18-53) months. After a mean follow-up period of 33.7 ± 12.8 months, there was no statistically significant difference between Groups 1 and 2 in terms of clinical, radiological and femoral head avascular necrosis results (P = .591, P = 956, P = .492). The changes in radiological parameters over time and between groups were statistically significant. (P < .001). Only the TDD and c/b ratio were significantly different between groups 1 and 2 (P = .002 and P < .001, respectively).

Conclusion: In our study, along with acetabular index, the c/b ratio, teardrop width, TDD, and acetabular teardrop angle significantly changed after SIO and could be used as a guide for patient follow-up.