Short stems in the treatment of post-traumatic humeral head avascular necrosis with retained hardware

Fixation of the humeral stem in the humeral canal is achieved at the tip of the stem and at the calcar area of the humeral head. Patients with retained proximal humerus plates and avascular necrosis of the humeral head are good candidates for short stems as long as they have good bone density proximally at the humerus for fixation of the stem. It seems that this is the ideal case scenario to avoid loosening and failure of the implant.

The following x-rays are of a patient who had two prior surgeries and had zero degrees of shoulder external rotation in full adduction. In 90 degrees of abduction the external rotation was to 0 and internal rotation to 45 degrees. Active forward elevation was to 70 degrees.

There is post-collapse avascular necrosis with dense bone proximally on the Grashey view. On the axillary view the there is posterior subluxation on a Walch type B glenoid.

Preop planning to assess how much bone needs to be removed with humeral cut

Posterior subluxation of the humerus relative to glenoid

Based on the work of Saltzman, Mercer et al.

J Shoulder Elbow Surg. 2011 Apr;20(3):363-71. A reproducible and practical method for documenting the position of the humeral head center relative to the scapula on standardized plain radiographs.

Center of rotation in normal shoulders is seen above, by the work done at UW.




The dense AVN and hard bone required the use of the flexible reamers for reaming to avoid iatrogenic fracture or penetration

The plate was retained and the center of rotation reproduced with a short stem hemi prosthesis

Anterior inferior eccentric head and anterior eccentric humeral canal reaming and implant position eliminated the subluxation

The surgery was completed with implantation of a short non cemented stem by removing proximal locking and non locking screws. The benefit of this approach is the following:

1. Less soft tissue dissection
2. Preservation of the plate, eliminates the risk of stress riser development through the screw holes of the plate
3. If cemented is required there is no distal cement extravasation
4. Overlapping of the prosthesis with the plate minimizes the risk of stress riser between the two implants
5. Eccentric humeral head directed anteriorly or anterio-inferiorly corrects the posterior subluxation of the humeral head as seen on axillary x-ray.
6. Most importantly, a future revision surgery is not complicated as removal of the undersized non cemented stem is easy with preserved proximal humeral bone.

Patient selection is important when a decision is made to use this approach in revision cases.