What Are the Long-term Outcomes of Locking Plates for Nonosteoporotic Three-part and Four-part Proximal Humeral Fractures With a Minimum 10-year Follow-up Period?
Authors: Zhang Zhijun , Li Yijun , Zhao Yang , Lu Yi , Zhu Yiming , Jiang Chunyan 
Published: October 2023

Abstract

Background
Proximal humeral fractures (PHFs) often occur in elderly individuals who experience low-energy falls. Open reduction and internal fixation (ORIF) of the proximal humerus is typically performed in young, active patients because of their good bone quality and high functional demands. Although good short-term results have been reported after ORIF in young patients, few studies have specifically evaluated long-term outcomes.

Questions/purposes
(1) What are the long-term clinical outcomes scores and (2) radiologic outcomes of nonosteoporotic three-part and four-part PHFs treated with locking plates? (3) What complications occurred after treatment, and what factors are associated with poor postoperative functional outcomes scores and avascular necrosis (AVN) of the humeral head after ORIF?

Methods
Between June 2005 and December 2012, we surgically treated 774 patients for displaced two-, three-, and four-part PHFs. Approximately 75% (581 of 774) underwent ORIF, 10% (77 of 774) underwent hemiarthroplasty, 7% (54 of 774) underwent intramedullary nailing, 5% (39 of 774) underwent reverse shoulder arthroplasty, and the remaining 3% (23 of 774) underwent other surgical treatments. We considered those who had ORIF as potentially eligible. Based on that criterion, 75% (581) were eligible. However, only patients with nonosteoporotic three- and four-part PHFs (cortical thickness of the proximal humeral diaphysis greater than 6 mm on a preoperative AP radiograph of the affected shoulder) and a minimum of 10 years of follow-up were included. Sixty-four percent (498 of 774) of the patients were excluded because of simple or osteoporotic fractures, 1% (7 of 774) were excluded because of ipsilateral limb multiple fractures, 0.3% (2 of 774) were excluded because of pathologic PHFs, and another 2% (13 of 774) were lost before the minimum study follow-up of 10 years, leaving 8% (61 of 774) for analysis here. The mean age at surgery was 45 ± 12 years, with a mean follow-up of 13 years. Fifty-seven percent (35 of 61) of the patients were men. Patient-reported outcomes were evaluated using the University of California Loas Angeles (UCLA) score (range 0 to 35; higher scores represent better shoulder function) and Constant score (range 0 to 100; higher scores represent better shoulder function) at least 10 years postoperatively. Postoperative radiographs were reviewed to assess the cortical bone thickness of the proximal humerus, neck-shaft angle, head-to-tuberosity distance, and radiologically confirmable complications. Logistic regression analysis was performed to evaluate factors associated with poor postoperative functional scores (UCLA score ≤ 27 or Constant score ≤ 70) and AVN of the humeral head; the association between AVN and postoperative functional outcomes was also assessed.

Results
At the most-recent follow-up, these patients had a mean UCLA score of 31 ± 3 and a Constant score of 88 ± 10. The mean neck-shaft angle was 133° ± 10°, and 23% (14 of 61) of patients experienced AVN of the humeral head during follow-up. Twenty-nine complications in 30% (18 of 61) of patients were reported. After controlling for potentially confounding variables such as age and gender, we found that the presence of greater tuberosity malposition (odds ratio 18 [95% confidence interval 2 to 167]; p = 0.01) and immediate postoperative neck-shaft angle less than 130° (OR 19 [95% CI 3 to 127]; p = 0.002) were associated with poor postoperative functional scores. Four-part PHFs (OR 13 [95% CI 2 to 82]; p = 0.008) and metaphyseal extension less than 8 mm (OR 7 [95% CI 1 to 35]; p = 0.03) were associated with AVN of the humeral head. For patients who met the criteria for anatomic reduction (achievement of all of the following three criteria: neck-shaft angle ≥ 130°, head-shaft displacement < 5 mm, and head-to-tuberosity distance greater than or equal to 3 mm and less than or equal to 20 mm), there were no differences in postoperative functional scores between patients with AVN and those without.

Conclusion
ORIF of nonosteoporotic proximal humeral fractures with locking plates led to favorable functional and radiologic outcomes at a minimum of 10 years of follow-up. When encountering complex PHFs in patients with good bone quality, every effort must be made to achieve an anatomic reduction of the fracture as far as possible, which may not reduce the risk of AVN (this occurred in nearly one-fourth of patients). However, good outcomes can usually be expected, even in patients with AVN. Because this was a retrospective study with a high risk of bias owing to sparse data, the factors associated with poor postoperative functional outcomes must be further investigated in large prospective studies.

Level of Evidence
Level III, therapeutic study.