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Updated: Jul 9, 2025
In Vivo Quantification of Hip Arthrokinematics during Dynamic Weight-bearing Activities using Dual Fluoroscopy
Published on: July 2, 2021
Joint instability in patients with borderline developmental dysplasia of the hip
Fumiya Kizawa1, Daisuke Suzuki2, Satoshi Nagoya3
1Division of Rehabilitation, Hokkaido University Hospital, Kita-14, Nishi-5, Kita-ku, Sapporo 060-8648, Japan; Department of Musculoskeletal Biomechanics and Surgical Development, Sapporo Medical University, Minami-1, Nishi-17, Chuo-ku, Sapporo 060-8556, Japan.
Background:
The treatment strategy for developmental dysplasia of the hip is determined based on the lateral center-edge angle. Nonetheless, an evaluation of joint instability may be important in determining the treatment strategy. This study classified the displacement patterns of the femoral head center during hip abduction.
Methods:
Ten patients with borderline developmental dysplasia of the hip, 10 patients with developmental dysplasia of the hip, and 10 patients with normal hips were analyzed. Image matching was performed using X-ray images of hip abduction with a three-dimensional hip model. The displacement of the femoral head center and its trajectory length were measured. A cluster analysis was conducted to classify the displacement pattern of the femoral head center, and trajectory lengths were compared.
Findings:
Displacement was classified into three patterns: medialization, hinge abduction, and centering. Patients with borderline developmental hip dysplasia exhibited all three patterns. Almost all patients with developmental dysplasia of the hip showed medialization and hinge abduction, whereas all normal patients had the centering type. The mean trajectory length indices for the medialization and hinge abduction types were significantly longer than those for the centering type (P = 0.01 and P = 0.016, respectively).
Interpretation:
Borderline developmental dysplasia of the hip is a heterogeneous condition characterized by varying hip instability levels. Our findings suggest that uniform evaluation based on the lateral center-edge angle is inappropriate and that joint instability must be evaluated in each patient with borderline developmental dysplasia of the hip.
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