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The influence of joint posture on intra-articular pressure. A study of transient synovitis and Perthes' disease
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Perthes
Area of Science:
- Pediatric Orthopedics
- Hip Pathophysiology
- Biomechanical Engineering
Background:
- Perthes' disease pathogenesis is linked to elevated intra-articular pressure from joint effusions.
- Understanding hip joint pressure dynamics is crucial for pediatric hip conditions.
Purpose of the Study:
- To investigate hip intra-articular pressure in children with transient synovitis and Perthes' disease.
- To determine the effect of hip position on intra-articular pressure in the presence of synovial effusion.
Main Methods:
- Direct measurement of intra-articular hip pressure in children.
- Testing various hip positions, including supine, comfortable, and prone with medial rotation.
- Comparison of measured pressures against arteriolar and systolic blood pressure.
Main Results:
- Intra-articular pressure remained below arteriolar blood pressure in the position of comfort.
- Supine positions did not exceed systolic blood pressure.
- Extension with medial rotation and stable lateral positions significantly elevated intra-articular pressure, exceeding systolic blood pressure.
Conclusions:
- Hip extension with medial rotation, and stable lateral positions, can critically increase intra-articular pressure in effused hips.
- This elevated pressure may compromise blood supply to the capital femoral epiphysis, contributing to Perthes' disease.
- Positional management of the pediatric hip may be important in effused states.
Abstract:
The pathogenesis of Perthes' disease has been related to increased intra-articular pressure secondary to a joint effusion. The pressure within the hip in different positions was measured in eight children with transient synovitis and four with the synovial stage of Perthes' disease. In the position of comfort for the hip this pressure was always less than the arteriolar blood pressure and in a supine position it did not exceed the systolic blood pressure. However, in extension with medial rotation the intra-articular pressure always became several times the systolic blood pressure. This high pressure was also recorded in the stable lateral position which occurs normally during sleep. It is concluded that in the presence of a synovial effusion in the hip, a position of extension and medial rotation causes an increase in intra-articular pressure which may compromise the blood supply to the capital epiphysis of the femur.