Surgical variables may predict varus collapse in proximal humerus fracture fixation
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Published results showed an association between failure to restore the medial calcar and use of locking cross-threaded screws with varus collapse among patients with proximal humerus fractures who underwent open reduction and internal fixation.
Surena Namdari, MD, and colleagues assessed known predictors of fixation failure among 112 patients with proximal humerus fractures who underwent open reduction and internal fixation. The predictors included calcar distance, calcar ratio and calcar restoration. Researchers also determined the presence of cross-threaded screws and analyzed varus collapse of the fracture, defined as a change in neck shaft angulation to less than 120°, as the primary outcome.
Results showed 17 patients experienced varus collapse, of whom seven patients had Neer type 2 fractures; five patients had Neer type 3 fractures; and five patients had Neer type 4 fractures. Researchers found 64.7% and 41.1% of patients had medial hinge displacement and medial comminution, respectively. According to results, 64.7% of patients who experienced varus collapse had cross-threaded screws vs. 32.6% of patients who did not experience varus collapse.
Patients who experienced varus collapse had an average calcar distance of approximately 10.9 mm, as well as an average calcar ratio of approximately 21%, results showed. Researchers noted 47.1% of patients who experienced varus collapse did not have restoration of the calcar compared with 16.8% of patients who did not experience varus collapse.
“When screws are cross-threaded into a fixed-angle locking plate, there is a higher risk of fixation failure in proximal humerus fractures,” Namdari told Healio Orthopedics. “While the priorities in fixation remained anatomic reduction of the fracture and restoration of the medial calcar, cross-threading occurred in over 35% of the reviewed cases and was associated with failure. Technique strategies or evolutions in product design to avoid cross- threading may help to reduce fixation failures in these challenging cases.” – by Casey Tingle
Disclosures: Namdari reports he receives research funding from DePuy, Zimmer, DJO Surgical, Tornier, Integra Life Sciences and Arthrex; is a consultant for DJO Surgical, DePuy-Synthes and Miami Device Solutions; and receives royalties from DJO Surgical, Miami Device Solutions and Elsevier. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Vani Sabesan, MD
Overall this study is from a strong academic center and focuses on examining factors that attribute to successful healing for a proximal humerus fracture. This can be a very difficult problem to treat and therefore examining factors that predict good and bad outcomes can be critical to predict outcomes for surgical treatment of these injuries. Specifically, surgical treatment with plate and screws can fail with collapse at the fracture site and this study identified two surgical factors that are associated with this failure mechanism – cross threading of the locking screws and failure to restore the medial calcar. There are other studies that have similar findings and surgeons must be aware and account for these factors during surgery as they can be a function of implant design, surgical technique and bone quality. Bone quality and implant factors can contribute to higher failure rates for patients who are treated surgically for proximal humerus fractures. Patients should be aware and discuss this with their surgeons.
Cleveland Clinic Weston
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