Opportunistic Screening for Local Osteoporosis of the Proximal Humerus on the Basis of Hounsfield Units: A Study of Patients With Rotator Cuff Tears.

Abstract

Objectives: The accuracy of dual-energy x-ray absorptiometry (DXA) in predicting proximal humerus osteoporosis in patients with rotator cuff tears (RCTs) undergoing arthroscopic rotator cuff repair (ARCR) is uncertain. The aim of this study was to assess the correlation of computed tomography (CT) Hounsfield units (HU) and the deltoid tuberosity index (DTI) with bone mineral density (BMD), and to evaluate the predictive value of HU values for implant selection.

Methods: This study analyzed the preoperative shoulder CT scans and x-rays of 184 patients who underwent ARCR. Preoperative CT scans were utilized to assess the multiple anatomical parts of the proximal humerus to ascertain the HU values, whereas preoperative x-rays were analyzed to derive the DTI. Among them, 104 patients with preoperative DXA data were grouped according to the WHO diagnostic criteria for osteoporosis to establish the threshold HU values. The correlation between HU values and DTI and the lowest T score on DXA was studied, and the relationship between the HU value and the type of implant selected was discussed. The Pearson correlation coefficient was employed to examine the relationship between HU values, DTI, and T scores. And the Spearman correlation coefficient was employed to examine the relationship between HU values and enhanced fixation.

Results: There was a significant correlation between the HU values and DTI and the lowest T score (r_{HU&T score} = 0.539-0.576, r_{DTI&T score} = 0.288, p < 0.05). On the basis of the lowest T score grouping, the threshold HU values for diagnosing proximal humeral osteoporosis were obtained: proximal humerus = 47.44, humeral head = 97.62, greater tuberosity = 10.9, and lesser tuberosity = 5.38. There was no correlation between HU values and enhanced fixation (using 5.5-mm anchors or metal anchors instead of 4.5-mm anchors or all-suture anchors) (r = -0.143 to -0.027, p > 0.05).

Conclusion: Proximal humeral HU values were significantly correlated with DTI and the lowest T score on DXA. When the HU values in the proximal humerus in patients with RCTs fall below the thresholds, the surgery should be carefully planned. No correlation exists between HU values and enhanced fixation, thus further investigation through group studies is warranted.

Level of evidence: Level III, study of nonconsecutive patients, diagnostic study.