# Changes in Lower Limb Axial Alignment, Gait Biomechanics, and Plantar Force in Crowe Type IV Hip Dysplasia After Total Hip Arthroplasty: A Mean Ten‐Year Follow‐Up Retrospective Cohort Study

## TL;DR

This study examines long-term effects of hip replacement surgery on leg alignment, walking patterns, and foot pressure in patients with severe hip dysplasia.

## Contribution

This is the first study to analyze global lower limb alignment, gait biomechanics, and plantar force in Crowe IV DDH patients after THA with over 10 years of follow-up.

## Key findings

- THA improved functional scores and quality of life in Crowe IV DDH patients over a 10-year period.
- Postoperative alignment showed partial correction of valgus deformities, but gait and plantar force abnormalities persisted.
- Unaffected limb alignment normalized post-surgery, while the affected side showed reduced but not fully corrected valgus.

## Abstract

Total hip arthroplasty (THA) is the gold standard for treating Crowe IV developmental dysplasia of the hip (DDH). However, its long‐term effects on lower limb alignment, gait biomechanics, and plantar force in these patients remain underexplored, which is discussed in this article.

We conducted a retrospective cohort study that included 43 DDH Crowe IV patients who underwent THA between February 2008 and October 2019 and a control group of 43 matched healthy volunteers. Postoperative functional outcomes and quality of life were assessed using the Harris Hip Score, KOOS, AOFAS, and WOMAC scores. Lower limb alignment parameters (MAD, HKA, aTFA, mLDFA, mMPTA, and FO), knee alignment (HMFC, HLFC), and ankle alignment (mLDTA, FACO, and TT) were measured preoperatively, postoperatively, and at follow‐up. Gait analysis and plantar force measurements were performed at the final follow‐up.

With an average follow‐up of 10.2 years, patients showed significant improvement in functional and quality of life scores compared to pre‐surgery. Preoperatively, all patients had knee valgus and ankle varus on the affected side. After THA, most parameters showed reduced valgus alignment, except for HKA and HLFC. On the unaffected side, MAD, aTFA, and HKA indicated preoperative valgus, which was fully corrected post‐THA. Gait analysis revealed restricted lower limb motion and abnormal plantar force distribution that persisted postoperatively in Crowe IV DDH patients.

THA partially corrected abnormal lower limb alignment, gait parameters, and plantar force distribution in DDH Crowe IV patients over long‐term follow‐up.

This is the first study to examine the global alignment of the hip, knee, ankle, and lower limb after total hip arthroplasty in DDH Crowe type IV patients with a follow‐up period of more than 10 years.This is also the first study of its kind (as far as we know) in which both the unaffected and the affected sides were monitored, and full normalization of the alignment of the healthy lower limb was observed after surgery.We studied patients' gait biomechanics and plantar force, trying to figure out the functional change after THA.

This is the first study to examine the global alignment of the hip, knee, ankle, and lower limb after total hip arthroplasty in DDH Crowe type IV patients with a follow‐up period of more than 10 years.

This is also the first study of its kind (as far as we know) in which both the unaffected and the affected sides were monitored, and full normalization of the alignment of the healthy lower limb was observed after surgery.

We studied patients' gait biomechanics and plantar force, trying to figure out the functional change after THA.