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The underused hip in ipsilaterally orthotics-dependent children
Asser Sallam1, Christian M Ziegler1, Volkmar Jansson1
1Department of Orthopedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistr. 15, 81377 Munich, Germany.
Insights
Children with leg deformities needing orthotics/prosthetics develop hip issues like coxa valga. Lack of weight-bearing alters hip shape, necessitating monitoring.
Area of Science:
- Pediatric Orthopedics
- Biomechanics
- Developmental Dysplasia
Background:
- Children requiring long-term orthotics/prosthetics for leg deformities often exhibit in-toeing gait and Duchenne's limp.
- These conditions can lead to coxa valga antetorta and hip decentration in otherwise healthy hips.
- Investigating the risk of hip decompensation and structural changes due to underuse is crucial.
Purpose of the Study:
- To assess the development of healthy hips in children with long-term orthotics/prosthetics dependency.
- To determine if underused hips are at risk of decompensation.
- To understand how external shape and internal architecture of hips change with disuse.
Main Methods:
- Instrumental gait analysis was performed on ten children with healthy hips and unilateral orthotics/prosthetics dependency.
- Results were correlated with clinical findings, activity scores, and radiographic data.
- A Level II retrospective study design was employed.
Main Results:
- Significant changes were observed in the affected hips, including increased internal rotation and decreased external rotation.
- Radiological analysis revealed increased angles (caput-collum-diaphyseal, head-shaft, Sharp, acetabular) and distance (lesser trochanter to articular surface).
- Gait analysis showed increased stride length, shortened stance phase, reduced ground forces, and increased hip abduction.
Conclusions:
- Duchenne's limp and reduced weight-bearing stress are key factors in developing coxa valga and acetabular dysplasia.
- These hip changes align with the mechanobiological principle that function influences bone and joint design.
- A precautionary pelvic radiograph at puberty is recommended for children with these conditions.
Background:
The aim of this investigation is the development of primarily healthy hips in children who have required orthoses/protheses over the long term due to ipsilateral distally located deformities of the leg. These children show ipsilateral in-toeing gait and Duchenne's limping followed by a coxa valga antetorta and facultative hip decentration. A practical question is whether these hips are in danger of decompensation. An additional theoretical question is how the external shape and internal architecture changes if a primarily healthy hip is underused.
Methods:
Ten children with healthy hips who are unilaterally long-term orthotics/prosthetics-dependent agreed to undergo an instrumental gait analysis. The results were analyzed and correlated with clinical findings, a common activity score and planimetric radiographic data.
Results:
The intra-individual comparison revealed a number of significant changes in the hip of the deformed leg (p < 0.05). Clinically, the internal rotation was increased (15° ± 4.2°), while the external rotation was diminished (13° ± 1.3°). Radiologically, the projected caput-collum-diaphyseal angle, the lesser trochanter to articular surface distance and the head-shaft angle were increased by 11.1° ± 15.4°, 5.8 ± 4.2 mm and 11.9° ± 0.6°, respectively. Both the Sharp and acetabular angles were increased, the former by 3.6° ± 0.6° and the latter by 3.2° ± 0.6°. Kinetic gait analysis showed increased stride length (6.8 ± 3.7 cm), shortened stance phase (6.6 ± 1.6 %) and reduced forces transmitted to the ground (92.2 ± 34.3 N). The kinematic analysis showed increased hip abduction (14.0° ± 8.2°), while the pelvic obliquity was not significantly changed (0.01° ± 0.01°).
Conclusions:
Duchenne's limp and lack of weight-bearing stress are the decisive pathogenic factors of the underused coxa valga and acetabular dysplasia. These changes follow the mechanobiological concept of "function modifies design", which means function influences external shape and internal architecture of bones and joints. As a practical consequence we recommend that one pelvic radiograph be performed as a precaution at the end of puberty of children with these conditions.
Level Of Evidence:
Level II retrospective study.
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