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Title: Biomechanics of the human forearm in health and disease
Author: Malone, Paul
ISNI:       0000 0004 2733 9645
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2012
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Introduction: The forearm is a complex biological unit, which has allowed man's evolution. This PhD commenced with an analysis of the normal biomechanical functioning of the key components of the forearm: notably the distal radioulnar joint (DRUJ), interosseous ligament (IOL) and proximal radioulnar joint (PRUJ). Understanding normal forearm physiology, a clinical study followed to delineate the pathophysiology of a new clinical entity, related to DRUJ dysfunction. Methods: Biomechanical Study: A biomechanical testing jig was developed to facilitate collection of data about normal functioning of the DRUJ, IOL and PRUJ in both unloaded and loaded states. This permitted testing throughout the range of forearm pronosupination. Thawed fresh frozen cadaveric upperlimbs were mounted into the jig. Using Microstrain® strain gauges and Tekscan™ pressure sensors, the functional anatomy of the key components of the forearm was delineated, both with the forearm flexed at 90° and maximally extended at the elbow. Clinical Study: A series of 3-Tesla MRI scans was undertaken on patients symptomatic of an intermittent ulnar neuropathy. The causative pathophysiology was determined using 3D qualitative and quantitative analyses. Results: Biomechanical Study: Reproducible patterns of force transmitted and joint contact area have been determined for the DRUJ, and for the first time, the PRUJ. With the exception of PMax and P60 for the PRUJ, application of load increases contact areas and transmitted forces across the joints (P<0.05). The converse is true for PMax and P60 in the PRUJ. The IOL is lax during pronation, strain gradually increasing as the arm moves to neutral. In neutral the middle-portion of the IOL (m-IOL) demonstrates most strain, this decreasing again in supination, whilst the distal and proximal portions (d- & p-IOL) exhibit more strain (P<0.05). Axial loading consistently increases strain in all ligaments (P<0.05). Observed behaviour patterns across the joints and in the ligaments alter with elbow extension (P<0.05). Clinical Study: Salient symptoms of the new syndrome were described. Displacement of the ulnar nerve from its normal course was seen with compression/distraction in the distal forearm and Guyon’s canal. This was considered causative of the syndrome. As a by-product of the research, a new clinical device was also developed, which improves the patient pathway when investigating DRUJ dysfunction. Conclusions and Outcomes: This research has analysed normal forearm biomechanics determining that the PRUJ is a load-bearing joint, interrelated with the DRUJ and IOL. Elbow extension has been shown to alter the normal biomechanics of the forearm. A clinical entity of a dysfunctional forearm has been defined, called subluxation-related ulnar neuropathy or SUN syndrome. Finally, a new clinical device has been developed, which it is anticipated will translate into visible improvements in patient care.
Supervisor: Terenghi, Giorgio; Lees, Vivien Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Distal radioulnar joint (DRUJ) ; Proximal radioulnar joint (PRUJ) ; Forearm biomechanics ; Distal radioulnar ligaments ; Interosseous membrane (IOM) ; interosseous ligament (IOL) ; Forearm loading