A1 PULLEY: AN ANATOMIC STUDY OF BIOMECHANICAL PROPERTIES WITH IMPLICATION IN TRIGGER FINGER RELEASE

Samiksha Mehare, Vikas Singh, Anup Thapa

Abstract


Purpose: Trigger finger is a common problem leading to hand incapacitation disproportionate to the pathology. The simple complete release of A1 pulley for triggering is based on the premise that its functionality is minimal, and sacrifice will lead to negligible drawbacks. This anatomical study objectively assesses A1 pulley function and evaluates biomechanical disadvantages of its sacrifice.

Methods: An anatomic study on fresh cadavers and amputated upper extremities was conducted to assess the role of A1 flexor pulley in digit function.  With all pulleys intact, tendon excursion needed to attain complete finger flexion and force required to attain so were measured for each digit. These parameters were reassessed after partial ‘functional’ pulley release by the technique of ‘N enlargement’ plasty, and standard complete A1 pulley release. A statistical analysis of biomechanics of intact A1 pulley, and after the standard or ‘N’ plasty techniques is done.

Results: In five upper limbs, twenty-five digits were sequentially analyzed. The increased force and tendon excursion required after A1 pulley release is statistically significant compared to intact pulley or ‘N’ plasty partial release.

Conclusion: Complete finger flexion after standard release of A1 pulley, requires statistically significant increased force and tendon excursion than with the pulley intact or partially enlarged.

Clinical Relevance:  A1 pulley has significant role in hand biomechanics and should be preserved whenever feasible. ‘N’ plasty is a simple and effective technique to enlarge A1 pulley while preserving significant function.


Keywords


A1 pulley, Trigger Finger, Pulley release, Pulley biomechanics, Flexor pulley preservation, Stenosing tenosynovitis

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References


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