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Measurement of the forces and movements involved in neonatal hip testing
Y W Chow1, I Turner, W G Kernohan
1Queen's University of Belfast, Department of Orthopaedic Surgery, Musgrave Park Hospital, Northern Ireland, UK.
Insights
Standardizing infant hip screening requires sufficient abduction angles and controlled forces during Ortolani and Barlow tests to safely detect developmental dysplasia of the hip.
Area of Science:
- Orthopedics
- Pediatric Medicine
- Biomechanical Engineering
Background:
- Developmental Dysplasia of the Hip (DDH) screening in infants typically uses Ortolani and Barlow tests.
- These manipulative tests are frequently performed incorrectly, potentially compromising diagnostic accuracy.
- A need exists to standardize safe practices for these crucial infant hip examinations.
Purpose of the Study:
- To investigate the forces and maneuvers used in Ortolani and Barlow tests for DDH screening.
- To define standards for safe and effective physical examination of infant hips.
- To analyze the biomechanical requirements for detecting hip abnormalities.
Main Methods:
- Eight subjects examined two training models simulating infant hip pathologies.
- A custom force and displacement transducer system recorded forces and maneuvers.
- Analysis focused on peak forces and critical biomechanical conditions for abnormality detection.
Main Results:
- Specific abduction angles beyond critical points were necessary to dislocate/relocate unstable femoral heads.
- The force to dislocate a hip (12 N) was significantly less than the peak force applied (33 N).
- The Palmen test showed comparable diagnostic performance to the Barlow test but with lower peak forces (28 N vs 47 N).
Conclusions:
- Current training for DDH screening needs revision to ensure adequate abduction range and appropriate force application.
- Medical staff training should emphasize sufficient maneuver angles and forces to avoid joint overstress.
- Standardizing these techniques will improve the safety and efficacy of infant hip screening.
Abstract:
The screening for Developmental Dysplasia of the Hip in infants relies on the two manipulative tests developed by Ortolani and Barlow which are often poorly performed. This study investigated the forces applied and the sequences of physical manoeuvres underlying the tests in order to define a standard of safe practice. Eight subjects examined the hips of two training models that closely simulated the behaviour of a range of infant hip pathologies. The forces applied and the manoeuvres employed during each examination were recorded using a purpose-built force and displacement transducer system. The analysis concentrated on the peak forces and the biomechanical conditions necessary to detect an abnormality. The models' legs had to be abducted beyond certain critical angles in order to dislocate and relocate an unstable femoral head and the magnitude of the force required to dislocate the femoral head was significantly less than the peak force applied (12 N vs 33 N, p < 0.001). Also, the Palmen test, a less well known technique, provided the same level of diagnostic performance as the Barlow test but with a lower peak applied force (28 N vs 47 N, p < 0.001). Changes are therefore necessary to the training programmes for medical staff to ensure that the range of abduction during the manoeuvres is large enough to encompass the likely range of critical angles and that the forces applied are just sufficient so as not to overstress the joints.