Residual dysplasia of the hip after successful ultrasound-monitored treatment: how does an infant’s hip evolve?

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.

Residual acetabular dysplasia after Pavlik harness treatment for Graf type II hips

“…Residual hip dysplasia after the treatment of PH has been reported by many authors. 7 , 12 , 13 , 18 , 19 Several potential risk factors were associated with residual hip dysplasia. The severity of dislocation was reported as one of the predictors in patients treated with PH.…”

“…In some studies, the treatment goal was defined as an α angle more than 64°. 18 , 39 Some authors argued rounding or blunt acetabular rim might affect the measurement of the α angle and influence the treatment strategy. 40 – 42 Hareendranathan et al 42 proposed a contour-based α angle and a rounding index to improve the reliability and accuracy of DDH diagnosis, and they found that the apex point moved 8 mm leading to a 10° change of α angle.…”

What’s New in Pediatric Orthopaedics

“…A study of 108 infants with hip dysplasia found that elevated acetabular indices on radiographs before treatment were associated with residual acetabular dysplasia after Pavlik harness treatment 26 . However, Dornacher et al found that, in hips with residual acetabular dysplasia after Pavlik harness treatment, a majority reach normative values by preschool age, with 35 of 36 hips improving from a severe Tönnis classification by the third follow-up 27 . In the treatment of hip dislocation with closed reduction, a retrospective review of 182 hips found that 20% had an infolded labrum, but noted that this was not associated with an increased rate of residual acetabular dysplasia or need for a secondary surgical procedure 28 .…”