[Humeral bone defects in revision shoulder arthroplasty]

Revision shoulder arthroplasty is mainly performed with reverse TSA and should consider proper adjustment of the length and the amount of bone loss in humeral reconstruction. Whilst epi-/metaphyseal bone loss can mostly be compensated easily by stemmed standard implants, advanced bone loss exceeding 2° requires the support of longer revision stems.

Cementless fixation in the intact diaphyseal humerus is recommended in bone loss exceeding 2°, preferably with modular revision systems, because cemented reverse revision stems have higher loosening rates in the mid to long-term follow-up. In cases of advanced bone loss 3°-4° (more than 6-7 cm), structural humeral allografts should be considered to prevent instability and early loosening. Unfortunately, the access to fresh frozen allografts is very limited due to regulation of the German government in contrast to the situation in the US or Switzerland. Reverse tumor arthroplasty is an option with a higher complication rate and inferior function even when polyester mesh is used for ingrowth of soft tissues.

In bone loss 4°-5° the minimal anchorage length is mostly critical due to the curvature of the medullary canal. The fixation of a revision stem is only possible when at least 2-3 widths of the diaphyseal diameter are available. Custom-made implants with flanges or distal locking screws, or bipolar tumor arthroplasty may be required. Additionally, strut allografts can be useful to achieve stable fixation. Two-stage biological reconstruction in impaction-bone-graft or the Masquelet technique are rarely used as a salvage procedure.