JSES - 2026-05-01 - Journal Article
Low glenoid vault bone density is a risk factor for failure of proximal humerus fracture fixation.
Czerwonka N, Mastroianni MA, Hellwinkel JE, Malka M, Kirkwood G, Arvind V, Knudsen ML
Topics
Key Takeaway
Glenoid vault CT Hounsfield units <160 HU confer a 3-fold increased risk (RR 3.00, 95% CI 1.28–7.02) of ORIF failure requiring revision to arthroplasty in displaced proximal humerus fractures.
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Summary
This study asked whether preoperative glenoid vault CT Hounsfield units independently predict ORIF failure in displaced proximal humerus fractures treated with locking plates. Among 135 patients, 40 required revision to arthroplasty; their mean glenoid vault CTHU was significantly lower than those without revision (110.9 ± 42.6 vs. 170.5 ± 45.9, P < .001). A threshold of <160 HU tripled revision risk and correlated strongly with deltoid tuberosity index (R=0.72).
Key Limitation
Fracture complexity (Neer type distribution and degree of comminution) was not confirmed as equally distributed between the revision and non-revision cohorts, leaving residual confounding as the primary threat to the causal inference.
Original Abstract
HYPOTHESIS AND/OR BACKGROUND
We aimed to determine whether computed tomography Hounsfield units (CTHU) are an independent predictor of proximal humerus fracture fixation failure following open reduction and internal fixation (ORIF). We hypothesize that CTHU of the glenoid vault <160 Hounsfield units (HU) would be associated with a higher rate of failure of ORIF and need for subsequent revision to arthroplasty.
MATERIALS AND METHODS
A retrospective cohort study was performed at a single academic center, including patients who sustained a displaced proximal humerus fracture treated with ORIF using locking plates over a 20-year period. A minimum follow-up of 6 months was required. Exclusion criteria included concomitant glenoid fractures, humeral shaft fractures, primary bone malignancies, metastatic disease, or lack of preoperative CT scan. CTHU were measured at 4 distinct regions with the glenoid vault to assess bone density. Patients were categorized into those requiring subsequent revision to arthroplasty and those who did not. Statistical analyses were performed using standard tests for categorical and continuous variables, with significance set at P <.05.
RESULTS
A total of 135 patients were identified, with 95 patients who successfully underwent ORIF and 40 who required revision to arthroplasty. Patients who required revision to arthroplasty had lower mean CTHU than those without revision (110.9 ± 42.6 vs. 170.5 ± 45.9, P < .001). Patients with 2-part (166.9 ± 44.9 vs 113.9 ± 43.3, P < .0001) and 3-part (175.7 + 47.3 vs 118.4 + 54.0) proximal humerus fractures who underwent revision arthroplasty had significantly decreased mean CTHU than patients who did not undergo revision. CTHU of the glenoid vault <160 HU significantly increased the risk of revision to arthroplasty after ORIF (P < .001, relative risk 3.00, 95% confidence interval 1.28-7.02). Within the failed cohort who required revision to arthroplasty, there was no difference in CTHU between those who failed within 6 months or after 6 months from ORIF (92.9 ± 37.7 vs. 134.3 ± 50.9, P = .057); there was a significant difference in revision rates of 2-part proximal humerus fractures with CTHU <160 than those with CTHU >160 (P = .004). CTHU of the glenoid vault were found to be positively correlated to the deltoid tuberosity index (R = 0.72, P < .001) and combined cortical thickness of the humerus (R = 0.21, P = .02).
DISCUSSION AND/OR CONCLUSION
CTHU of the glenoid vault <160 HU is an independent risk factor for ORIF failure in patients with displaced proximal humerus fractures, leading to a higher likelihood of requiring revision to arthroplasty. This opportunistic measurement CTHU can assist surgeons in informed decision making between ORIF and primary arthroplasty in the management of these fractures.