Surgical Management of Displaced Fractures of the Proximal Humerus
Abstract
Displaced proximal humerus fractures are on the rise and, in many cases, are still the source of painful loss of function if not adequately treated. Many treatment options exist depending on the fracture pattern, the bone stock and the vascular status of the fractured fragments. Recently, many fixation techniques using various implants have been introduced; some implants have been successful, others less so. The indications for the newer plates with locking screws or locked nails have yet to be evaluated. Arthroplasty remains a useful option when the fracture is not reconstructible due to extensive comminution or inadequate osteoporotic bone. Whether the fracture is reconstructed or a prosthesis inserted, the rehabilitation protocol is a very important part of the treatment plan and must be strictly adhered to if good results are to be expected.
Introduction
Displaced fractures of the proximal humerus are frequent articular injuries that are a source of pain, functional loss and disability. These articular fractures are complex injuries involving the glenohumeral space, the subacromial space, the rotator cuff and the capsule. Furthermore, adjacent neurological and vascular structures are also at risk when these fractures occur.
Definition of ‘Displaced’
A fracture is said to be displaced when the morphologic disruption of the fragments hampers normally smooth and painless articular function. This concerns about 20% of all proximal humerus fractures. In the past, authors have used measurements (1cm translation and/or 45° angular displacement) to define the fragment displacement necessary for surgical intervention.1 Today, any displacement presumably leading to poor function may qualify for surgical fixation. However, surgical indication is obviously not related solely to fracture displacement and must be associated with patient expectations and activity.
Pathophysiology
These fractures are essentially related to osteoporosis, which accounts for many of the difficulties encountered when performing internal fixation.2,3 This signifies that the bone fragments will be of a low mineral content and that the holding power of the implants will be compromised. This implies using techniques or implants designed for fragility fractures. The vascularisation of the proximal humerus is of a terminal type, similar to other epiphyses such as the femoral head or talus. The main sources of blood supply are the anterior circumflex and posterior circumflex arteries, the vessels of the rotator cuff and the intraosseous metaphyseal artery. If the main nutrient arteries to the humeral head are interrupted, avascular necrosis with subsequent collapse of the articular surface will occur.4 Neer has contributed to establishing an estimation of prognosis with the fragment classification of proximal humeral fractures, which other authors have refined.5 Other factors affecting outcome are the complexity of the surgical approach, the obligatory use of indirect reduction techniques because the articular surfaces cannot be visualised intra-operatively and the lack of perfect fixation techniques. Once the purely surgical hurdles have been passed, there remains the rehabilitative process, which is also a cause for controversy. All these problems have led some authors to refer to this fracture as being still ‘unsolved’.6
