Nicholas Farrar

The assessment and management of patients with instability of the shoulder joint can be challenging, due to the varying ways patients present, the array of different classification systems, the confusing terminology used and the differing potential management strategies. This review article aims to provide a clear explanation of the common concepts in shoulder instability and how they relate to the assessment and management of patients. There are sections covering the mechanisms of shoulder stability, the clinical assessment of patients and imaging techniques. Beyond that there is a discussion on the common classifications systems used and the typical management options. Some patients fall into reasonably well defined categories of classification and in these cases, the management plan is relatively easy to define. Unfortunately, other patients can elude simple classification and in these instances their management requires very careful consideration. Further research may help to facilitate a better understanding of management of the patients in this latter group.

Background. Radial subluxation of the extensor communis tendons at the metacarpophalangeal (MCP) joints is a rarely reportedvinjury. These injuries have proved difficult to reproduce in cadaveric studies and have a low biomechanical likelihood of occurrence due to the ulnar direction of pull of the extensor communis tendons. It has been suggested that the juncturae tendinum may have a stabilising role, preventing radial subluxation after ulnar sagittal band rupture; however this has not been established. Methods. 40 cadaveric digits were dissected to reveal the extensor mechanism around the MCP joints. The ulnar sagittal bands were released and then the juncturae tendinum divided, in stages, before observing for radial subluxation or dislocation during finger flexion. Results. Radial subluxation of the extensor tendon was observed in only one digit after complete ulnar sagisttal band release. When all the fingers were flexed, after the juncturae tendinorum were divided, four additional tendons subluxed radially and a fifth tendon dislocated in this direction. When the digits were then flexed individually, there were eight unstable tendons in total. Conclusions. The juncturae tendinum appear to have a role in stabilising the extensor communis tendons at the MCP joints and preventing radial subluxation after ulnar sagittal band rupture.

Background: Though ubiquitously used in orthopaedic trauma, lower extremity splints may have associated iatrogenic risk of morbidity. Although clinicians pad bony prominences to minimize skin pressure, the effect of joint position on skin pressure and, more specifically, changing joint position, is understudied. The purpose of this biomechanical study is to determine the effect of various short-leg splint application techniques on anterior ankle surface pressure in the development of iatrogenic skin pressure ulcers. Methods: Various constructs of lower extremity, short-leg splints were applied to 3 healthy subjects (6 limbs total) with an underlying pressure transducer (Tekscan I-Scan system) on the skin surface centered on the tibialis anterior tendon at the level of the ankle. All subjects underwent anterior ankle surface pressure assessment when padding was applied in maximum plantar flexion and neutral position for conventional short-leg splints application in clinically relevant patient scenarios. Percentage change from initial contact pressure centered on the tibialis anterior with cast padding were calculated. Results: The percentage change in anterior ankle contact pressure when padding was applied in maximum plantar flexion (PF) and then definitively placed in neutral was increased at least 2-fold without the addition of plaster in lower extremity short-leg splints. Removing anterior ankle padding following final splint application in neutral reduced contact forces at the anterior ankle 46% and 59% in splints applied in maximum PF and neutral ankle position, respectively. Conclusion: The present study is the first of its kind to underscore and quantify clinically relevant technical pearls that can be useful in reducing risk of iatrogenic risk of skin breakdown at the anterior ankle when placing short-leg splints, mainly, that it is imperative to apply padding in the intended final splint position and to remove anterior ankle padding following splint application when able. Level of Evidence: Level IV, biomechanical study with clear hypothesis.