In the presented prospective study 35 consecutive patients with displaced 3- and 4-part fractures of the proximal humerus, including fracture dislocations, were treated with a fixator plate comprising angular stability between May 2001 and December 2002. After 18.5 (8-29) months 31 (89%) fractures were available for follow-up. Good and very good results were obtained in 64%. A poor result was documented in 23%. 64% of the patients had no or mild pain, 71% were able to abduct the arm over 90 degrees . Fracture classification according to Neer and AO had no influence on the outcome, with a mean Constant Score of 76 points. Partial avascular necrosis (AVN) of the humeral head was seen in 16% of all cases representing 4% of the fractures without dislocation and 80% of the fracture dislocations. Fracture dislocation (p=0.02) and AVN (p=0.005) had a negative effect on the Constant Score, with AVN being a predictor for a high level of pain (p=0.04). Secondary dislocation of the greater tuberosity was seen in two patients, loosening of screws in one patient and a fracture below the plate in another one. Secondary dislocation or loss of reduction of the head was not recorded. Angle stable plate fixation with tension band wiring of the tuberosities is an effective and safe option to treat this difficult fractures, also in elderly patients with osteoporotic bone. Because 40% of the 4-part fractures with fracture dislocation yielded a satisfactory or better result, the plate fixator with angular stability may be an alternative to prosthetic replacement in selected cases.

We recommend to position an inferomedial support screw, and at least 5 screws in the head fragment, when using a locking plate in proximal humerus fractures with disrupted medial hinge.