HipResidual dysplasia of the hip after successful ultrasound-monitored treatment: how does an infant’s hip evolve?Dornacher, Daniel; Lutz, Bernd; Freitag, Tobias; Sgroi, Mirco; Taurman, Rita; Reichel, Heiko Author Information Department of Orthopedics, University of Ulm, Ulm, Germany Received 13 July 2021 Accepted 27 February 2022 Correspondence to Daniel Dornacher, MD, Department of Orthopedics, University of Ulm, Oberer Eselsberg 45, 89081, Ulm, Germany, Tel: +49 731 1775104; fax: +49 731 1771118; e-mail: [email protected] Journal of Pediatric Orthopaedics B: November 2022 - Volume 31 - Issue 6 - p 524-531 doi: 10.1097/BPB.0000000000000984 Buy Metrics Abstract Despite that normal values for the hip joint are reached at the end of ultrasound-monitored-treatment, the development of the acetabulum can be compromised during the growth phase. The acetabular index (AI) measured on a pelvic radiograph has been proven to be a reliable parameter. The aim of this study is to gain a better understanding of the dynamics of once-treated, residually dysplastic hips. This should be achieved by radiographically following these hips up to a milestone-examination at the end of preschool age. A total of 120 hips of consecutive 60 infants were included in this examination, each presenting with a residual developmental dysplasia of the hips (DDH) after successful ultrasound-monitored harness treatment. Radiographic follow-up was assessed retrospectively around 18 months, 3 years and 6 years of age, and the AI was measured. The age-dependent Tönnis classification was applied. The hips were assigned normal, mildly or severely dysplastic. Dependent t-test for paired samples indicated a highly significant improvement of the AI-values, including from the first to the second and from the second to the third follow-up. The percentage distribution into the Tönnis classification changed remarkably: in the first follow-up, 36 of the 120 hips were evaluated ‘severely dysplastic’, in the third follow-up only 1. On the other hand, three hips underwent acetabuloplasty. Even after normal values have been achieved at the end of ultrasound-monitored treatment, there remains a risk of residual dysplasia of the hips. Particularly, when the first radiographic examination shows nonphysiological findings, further close-meshed follow-up is recommended. Level of evidence: retrospective study of therapeutic outcome, consecutive patients, level II. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.