Glenoid Bone Loss in Reverse Shoulder Arthroplasty Treated with Bone Graft Techniques

The tricortical iliac crest bone graft (TICBG) offered a structural graft that worked well for these cases of bone loss. When the graft is performed in 1 stage, the glenoid is exposed, and the defect measured after removing the osteolytic, polyethylene-laden tissue from the glenoid. The iliac graft is harvested and placed with the long post base plate engaging the native scapula medially (Figures 5A-5C).

This technique worked well with the type 1 and 2 defects, but when attempted with the type 3 glenoid defect with global glenoid bone loss, adequate fixation for a single-stage reconstruction could not be predictably obtained with type 3 loss of the vault and both walls. In this situation, the base plate post is wider than the remaining medialized glenoid vault (Figures 6A-6C). The iliac crest provides better bone for this global loss when harvested sideways, fixed with screws, and after secure healing, the second-stage base plate is placed (Figures 7A-7F).

An alternative to the iliac crest as a bone graft donor site is the femoral neck allograft.²¹ It avoids the additional surgery and pain at the donor site, but healing is less assured. Scalise and Iannotti²² have had good clinical results but noted substantial graft resorption when revising a total shoulder to a humeral head arthroplasty. In a recent report by Ozgur and colleagues,²³ 64% of femoral neck allografts were still intact at 1-year follow-up. The technique involved harvesting the graft with a hole saw, shaping and affixing it to the deficient glenoid, and gaining central fixation with a threaded or solid post base plate and peripheral screws. Poor results were obtained with the use of the femoral shaft, as it is brittle. Angled peripheral screws caused the allograft shaft to fracture. Low-grade sepsis remained an unanswered problem in the patient group, which averaged 6 prior procedures, and often led to another revision. Less favorable results were found using the 1-piece threaded post base plate with grafts.²⁴ It is assumed that the allograft has less healing potential, and micro motion plays a role when the long central screw has no on-growth healing potential in the native scapula. This graft choice is the author’s least favorite, but is available in desperate situations. Jones and colleagues²⁵ report promising results with bulk allografts and autografts for large glenoid defects with good clinical results. The results in the graft cohort were inferior to those in a matched group not requiring grafts. Their complications were consistent with the revision setting for shoulders having multiple operations. It is well known that preoperative factors are strong predictors of postoperative outcomes.²⁶

CONCLUSION

The author’s current technique is to use the native humeral head when available, or iliac crest for structural support to the base plate and glenosphere. Secure fixation to the native scapula is necessary if the operation is to be done in 1-stage. Incorporation with calcium orthophosphate bone substitution does not replace the need for structural support as shown in Figures 8A-8D.

For the type 2 vault and 1 wall glenoid bone loss defects, the TICBG is still the most useful option. For the type 3 global bone loss defects, a 2-stage approach is the safer option. Additional options that may replace some of these grafting techniques are the introduction of the metallic augmented ingrowth base plates to correct for superior, anterior, and posterior glenoid bone losses. The early unpublished experiences by Wright and colleagues are very promising. All of the above options should be available in the operating room for a busy arthroplasty surgeon.