These authors analyzed the characteristics of patients having surgical revision of a prior primary humeral hemiarthroplasty with the goal of answering three questions
(1) What are the common characteristics of shoulder hemiarthroplasties having a revision?
(2) What are the common characteristics of the subset of revised shoulder hemiarthroplasties that were performed for fracture?
(3) What are characteristics of the subset of all revised hemiarthroplasties that were associated with glenoid bone erosion?
These patients had severe loss of self-assessed shoulder comfort and function, with Simple Shoulder Test (SST) scores averaging 2.2 +/- 2.2 of the maximum score of 12. The average time from index arthroplasty to revision was 3.4 years.
Common characteristics of the revised hemiarthroplasties included
female sex (81%),
rotator cuff (89 of 359; 25%) or subscapularis (81 of 359; 23%) failure,
problems related to prior fracture (154 of 359; 43%),
glenoid erosion 125 of 359; 35%), and
component malposition (89 of 359; 25%).
Hemiarthroplasties performed for fracture-related problems often were associated with tuberosity malunion or nonunion (58 of 79; 73%) and decentering of the humeral component on the glenoid surface (45 of 71; 63%).
Major erosion of the bony glenoid (Grade 3 or 4) was more common in decentered hemiarthroplasties (42 of 102; 41%) than for centered hemiarthroplasties (36 of 146; 25%) (Fisher's exact p = 0.008) and more common for hemiarthroplasties positioned in valgus (28 of 50; 56%) than for those positioned in neutral or varus (40 of 188; 21%) (Fishers' exact p < 0.0001).
Based on these findings the authors suggested that some revisions of primary hemiarthroplasties may be avoided by surgical techniques directed at centering the prosthetic humeral articular surface on the glenoid concavity using proper humeral component positioning and soft tissue balance, by avoiding valgus positioning of the humeral component, and by managing glenoid disorders with a primary glenohumeral arthroplasty rather than a hemiarthroplasty alone. When durable security of the subscapularis, rotator cuff, and tuberosities is in question, the surgeon may consider a reverse total shoulder arthroplasty.
Comment: Primary shoulder hemiarthroplasty is a commonly used procedure for the treatment of various shoulder disorders. In the treatment of a proximal humeral fracture, primary hemiarthroplasty is considered when displaced fracture fragments cannot be treated with internal fixation or when there is concern regarding head collapse. In the treatment of shoulder arthritis, capsulorrhaphy arthropathy, or avascular necrosis, a primary hemiarthroplasty may be performed if there is minimal glenoid disease, if the patient is young, if the shoulder is too tight to admit a glenoid component, if there is insufficient bone stock to support a prosthetic glenoid, if there is concern for possible infection, if the patient wishes to avoid the risks and limitations associated with a glenoid component, or if the surgeon is not comfortable with performing another type of shoulder arthroplasty. Each of these indications can be associated with an increased risk of failure and subsequent revision.
This study calls attention to some of the factors that can be associated with a poor outcome and provides some possible approaches for reducing the need for surgical revision of a failed hemiarthroplasty.
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