[Functional results of Neer II type hemi-arthroplasty joint replacement of multi-fragment humerus head fractures].

Among the fractures of the proximal humerus--a typical kind of injury affecting elderly people, as well as gainfully employed patients, the comminuted and dislocated humeral head fractures have a specific position because of therapeutical reasons. By means of a retrospective analysis, a review is given of the results of 26 comminuted humeral head fractures type IV-VI according to Neer, treated with a Neer prosthesis type II at the surgical clinic of the Kantonsspital Lucerne between 1983 and 1989. Our interest is mainly concentrated on the functional results and on their correlation with biomechanical and perioperative factors. We use the fracture-classification and functional evaluation as described by Neer. For the results classified as "failures" (13 cases) the functional deficits of the glenohumeral joint mobility are essential. The scores reveal no significant correlation to the age of the patients, to the time interval between trauma and operation, as well to the duration of the postoperative physiotherapy. On the other hand the scores of patients with preoperative manipulation of the fractured joint (i.e. osteosynthesis, reduction attempts, physiotherapy) were significantly worse than those with primary prosthetic replacement. Furthermore, because of the insufficient restitution of the lever arm conditions, the implantation of the small-head component (15 mm) leads to significantly less favorable functional scores, with a corresponding radiological hyperpression in the cranial articular space. Our analysis leads to the following conclusions: 1. Under the condition of a conclusive preoperative diagnosis a primary prosthetic procedure is recommended depending on the type of fracture.(ABSTRACT TRUNCATED AT 250 WORDS)