Vivien C. Lees

The Radiological Demonstration of Dynamic Ulnar Impingement

The diagnosis of ulnar impingement is often missed because of a low index of clinical suspicion. Furthermore there has been no investigation that will demonstrate it. Most commonly impingement is seen as a complication of surgical procedures involving resection of all or part of the distal ulna, with or without resection or arthrodesis of the distal radioulnar joint. We demonstrate a simple radiological investigation that clearly confirms the diagnosis.

Lessons Learned from the Management of Complex Intra-Articular Fractures at the Base of the Middle Phalanges of Fingers

The use of dynamic traction splintage is established in the treatment of complex intra-articular phalangeal fractures. Several different systems have been used and we report our experience with one of these, the Pins and Rubber Traction System. A cohort of 14 patients with complex intra-articular fractures at the base of the middle phalanges of the fingers were treated and assessed prospectively over a 2.5-year period (mean, 20 months; range, 7–28 months). The mean active range of motion regained, at the proximal interphalangeal joint, was 74° (range, 0–100°). The mean total active motion of the injured digit was 196° (range, 40–275°). Refinements in the regime are suggested as a result of this investigation.

A prospective investigation of the healing of grafted pretibial wounds with early and late mobilisation.

The aims of this study were to determine whether early mobilisation delays wound healing after meshed split skin graft repair of pretibial wounds and to identify other factors delaying the healing of these wounds. A prospective randomised controlled trial was conducted to compare the time to complete healing of patients mobilised early (the first postoperative day) against those who mobilised late (the tenth postoperative day). There was no difference in time to complete healing. Patients with a history of oral steroid therapy had a mean delay in wound healing of approximately 8 days (p < 0.02). The severity of tissue damage, as indicated by undermining of the skin margins, damage to the fascia and exposure of the periosteum, correlated with delayed wound healing (p < 0.05).

Fibre bundles in the human extensor carpi ulnaris tendon are arranged in a spiral

The extensor carpi ulnaris musculotendinous unit has important agonist and antagonist action in wrist motion, including the dart-throwing action, and is a dynamic stabilizer of the distal radioulnar joint during forearm rotation. Despite its functional and clinical importance, little is known about its internal structure. Investigation of the ultrastructure of the human extensor carpi ulnaris (ECU) tendon was undertaken using plane polarized light microscopy and microcomputer tomography with 3D reconstruction. The study demonstrates that the tendon comprises fibre bundles (fascicles) approximately 0.1 mm in diameter that are arranged in a gradual spiral. The spiralling fibres make an angle of 8º to the longitudinal axis of the tendon. The spiral structure of the human ECU tendon has important biomechanical implications, allowing fascicular sliding during forearm rotation. The observed features may prevent injury.

THE EFFECT OF ELBOW POSITION ON THE RANGE OF SUPINATION AND PRONATION OF THE FOREARM

A kinematic study was performed to examine the influence of elbow position on the range of supination and pronation of the forearm. The ranges of supination and pronation were measured in 50 volunteers (25 men and 25 women) using a custom-designed jig which constrained unwanted and confounding movements of the limb. Measurements were taken with the elbow in full extension, 45° flexion, 90° flexion and full flexion. The data showed a reciprocal relationship between the range of supination and the range of pronation of the forearm which depended on the degree of elbow flexion. As the elbow is flexed, the maximum angle of supination increases while the maximum angle of pronation decreases (p<0.001). The converse is true as the elbow is extended (p<0.001).

The biomechanical and functional relationships of the proximal radioulnar joint, distal radioulnar joint, and interosseous ligament.

This biomechanical study assessed integrated function of the proximal radioulnar joint (PRUJ), interosseous ligament (IOL), and distal radioulnar joint (DRUJ). Tekscan™ pressure sensors were inserted into the DRUJ and PRUJ of 15 cadaveric specimens. MicroStrain® sensors were mounted onto the IOL on nine of these specimens. A customized biomechanical jig was used to apply axial loads and take measurements through pronosupination. The PRUJ, IOL, and DRUJ were shown to function as an integrated osseoligamentous system distributing applied load. The PRUJ has transmitted pressure profiles similar to those of the DRUJ. Different IOL components support loading at different stages of pronosupination. The IOL is lax during pronation. Mid-IOL tension peaks in the midrange of forearm rotation; distal-IOL tension peaks in supination. Axial loading consistently increases IOL strain in a non-linear fashion. There are clinical implications of this work: disease or surgical modification of any of these structures may compromise normal biomechanics and function.

The functional anatomy of forearm rotation

The elbow, forearm and wrist act as a unified structure to provide a stable, strong and highly mobile strut for positioning the hand in space and for conducting load-bearing tasks. An understanding of the relevant anatomy and biomechanics is important for the surgeon assessing and treating disorders of forearm function. This paper is concerned with illuminating the principles and concepts governing forearm rotation and load-bearing functions.

A multicentre, randomized, double-blind trial of the safety and efficacy of mannose-6-phosphate in patients having Zone II flexor tendon repairs.

The safety, tolerability and preliminary efficacy of mannose 6-phosphate in enhancing the outcome in Zone II flexor tendon repair was studied in a multicentre parallel double-blinded randomized controlled trial. Eight UK teaching hospitals were involved in treating repaired flexor tendons with a single intraoperative intrathecal dose of 600 mM mannose 6-phosphate, with follow-up over 26 weeks. A total of 39 patients (mannose 6-phosphate, n = 20; standard care, n = 19) were randomized. Seven were excluded from the safety and tolerability analysis because of intraoperative findings and eight were excluded due to early dropout (n = 4) or tendon rupture (n = 4), leaving 24 (mannose 6-phosphate, n = 13; standard care, n = 11) for assessment of total active motion. The safety, tolerability and other side effects were comparable between the groups. There was no significant difference between the two groups in the total active motion at Week 26. We concluded that mannose 6-phosphate, although safe and tolerable, had no beneficial effect on finger range of motion after Zone II tendon division. Level of evidence 1b

Subluxation-related ulnar neuropathy (SUN) syndrome related to distal radioulnar joint instability.

Ulnar neuropathy coexistent with distal radioulnar joint (DRUJ) instability has previously been observed in our practice. The aim of this study was to define this phenomenon and investigate the hypothesis that the cause of this intermittent, positional ulnar neuropathy is related to kinking of the ulnar nerve about the DRUJ. Ulna neuropathy was present in 10/51 (19.6%) of a historical cohort of patients who presented with DRUJ instability. Nine subsequent patients with DRUJ instability and coexistent ulnar neuropathy underwent 3-T magnetic resonance imaging to better understand the mechanism of the observed syndrome. Both 3D qualitative and quantitative analyses were used to assess the presence of nerve ‘kinking’, displacing the nerve from its normal course and causing nerve compression/distraction in the distal forearm and Guyon’s canal. Results of the quantitative analysis were statistically significant (p < 0.05). The clinical features of the condition have been delineated and termed subluxation-related ulnar neuropathy or SUN syndrome. The imaging study was a level II diagnostic study.

Dynamic Skin Tension in the Forearm: Effects of Pronation and Supination

PURPOSE Longitudinal scars on the radial quadrant of the distal forearm skin envelope are typically observed to be wider than those on the ulnar quadrant and have an increased incidence of hypertrophic change. Forearm rotation movements may produce differential skin tensions within the forearm skin envelope, and this may lead to differential scarring patterns. This study was designed to measure skin tension changes in the forearm as a result of rotational position to see if these would be consistent with the hypothesis that greater tension changes are observed on the radial aspect of the forearm. METHODS The effect of forearm position on the magnitude and direction of skin tension was measured on human volunteers. Standardized circles were marked in circumferential fashion at specified intervals on forearm skin, and the angular and dimensional distortion of these circles that occurred with forearm rotation was measured with caliper and goniometer. Data were analyzed for statistical significance using paired t-test. RESULTS Pronation and supination resulted in marked angular rotation of the lines of maximal skin tension at all sites on the forearm. Supination resulted in a greater angular deviation of the lines of maximal skin tension from the longitudinal line of usual surgical incision, particularly on the radial aspect of the forearm. In supination, the magnitude of ellipsoid deformation at the distal forearm was greater on the radial aspect compared with that of the ulnar. Similar significant changes were also demonstrated at the mid-forearm and proximal forearm levels. CONCLUSIONS This study systematically maps the effects of pronation and supination on skin tension within the forearm skin envelope. The significant changes occurring in both the ellipsoid deformation and ellipsoid orientation support our hypothesis that the magnitude of skin tension changes significantly with forearm rotation. The radial aspect of the distal forearm experiences the greatest changes, particularly as the forearm supinates.