Proximal humerus fracture fixation is challenging when there is insufficient bone density, more than 2 parts, an associated dislocation, and more importantly bone loss or impaction of the head in the setting of an obese patient or large deltoid which makes the exposure difficult.
The deforming forces can be eliminated to a certain extend when the patient is placed in the supine position with the arm on a hand table and abducted to 90 degrees which relaxes the deltoid to allow for space retraction and application of the plate. The most significant deforming forces are:
1. Pectoralis major pulls the shaft anterior and medial
2. The greater tuberosity is pulled superiorly and posteriorly by the supraspinatus, infraspinatus and teres minor
Those forces can be significant and suture passing around the fragments can help with manipulation of the bone fragments. In the majority of cases the difficulty is in raising the articular surface, filling the defects of the bone without overstuffing and repairing the tuberosities. The head shaft angle is better tolerated in the valgus than in the varus position.
It is important to achieve the following after ORIF if possible:
a. Avoid long head screws as the most common complication is head screw penetration
b. Choose isolated screw fixation only in the young patient with good bone stock
c. Restore medial disrupted bone hinge
d. avoid step off in head splits
e. try to proceed with ORIF of head splits in young patients and avoid arthroplasty.
f. avoid superior migration of the greater tuberosity - or posterior superior migration - of more than 5 mm.
g. Pass sutures around the rotator cuff and tight them to the plate.
h. Avoid superior placement of the plate as it may impinge to the acromion with elevation of the shoulder or arm
Below is a fracture treated with ORIF taking into consideration those principles.
