Abstract
Peri-prosthetic fractures around implants in the proximal humerus can present substantial challenges. Most individuals who undergo upper limb arthroplasty tend to be osteopenic to begin with, and the anatomy of the proximal humerus does not provide an excess of bone to work with. Therefore, peri-prosthetic fractures pose difficulties to rotator cuff function and implant stability. There are multiple classification systems, but series are small and the classification does not always lead to treatment algorithms. Risk factors for humeral fractures after shoulder arthroplasty include endosteal notching, cortical perforation, varus malalignment, stem perforation, ipsilateral shoulder and elbow arthroplasties, and loose stems. Many of these risk factors are directly related to technical errors at the time of surgery. Poor exposure can lead to aberrant starting point and errors in reaming. Oversized prostheses can lead to cortical perforation or even stem perforation. Proper positioning of the patient on the table and surgical releases help avoid these technical errors. Peri-prosthetic fractures should be carefully evaluated radiographically for stability. Two important considerations: 1. Is the implant stable? 2. Is the fracture stable? Generally, if the implant is unstable, the implant must be revised. In the setting of a stable implant, many humeral fractures can be treated nonoperatively. Many fractures at or below the level of the tip of the implant can be treated as typical humeral fractures. Options for fixation include plates with cables or long stem prostheses which bypass the fracture. Displaced tuberosity fractures are treated with suture or wire fixation. Risk factors for a poor outcome include increased time to union, skin breakdown, and stiff shoulder.
