# Preoperative humeral computed tomography may be a useful indicator of low bone mineral density in patients undergoing rotator cuff repair

## TL;DR

This study shows that preoperative CT scans of the humerus can help identify patients with low bone density undergoing rotator cuff repair.

## Contribution

The study introduces the use of CT-based Hounsfield unit values in anchor-relevant regions of the humerus as a novel indicator of systemic bone mineral density.

## Key findings

- HU values at the greater tuberosity showed the strongest correlation with systemic T-scores and BMD.
- Lower HU values in lateral and greater tuberosity regions suggest increased bone fragility risk.
- GT HU values remained independently associated with BMD after adjusting for age, sex, and tear size.

## Abstract

Bone fragility can compromise rotator cuff repair, particularly in patients with osteoporosis. Although previous studies have demonstrated correlations between systemic bone mineral density (BMD) and bone quality, only a few have focused on the anchor-relevant regions in patients with rotator cuff tears. We hypothesized that preoperative computed tomography (CT)-based Hounsfield unit (HU) values at anchor-relevant areas in the proximal humerus could be used to estimate systemic BMD in these patients.

This retrospective study included 58 patients (62 shoulders) who underwent arthroscopic rotator cuff repair and had both preoperative shoulder CT and dual energy X-ray absorptiometry scans. HU values were measured in 4 regions of interest within the proximal humerus: medial, central, lateral, and greater tuberosity (GT). Systemic BMD was assessed using femoral neck and lumbar spine T-scores and BMD values. Pearson correlation coefficients were used to evaluate the association between the HU values and systemic T-score/BMD. Multivariate linear regression analyses were performed using HU values at the GT after adjusting for age, sex, and rotator cuff tear size.

HU values were significantly lower in the lateral and GT regions than in the medial and central regions (P < .01). Among regions, the HU values at the GT showed the highest correlations with the systemic T-scores and BMD (all moderate): femoral neck T-score (r = 0.57), lumbar spine T-score (r = 0.55), femoral neck BMD (r = 0.60), and lumbar spine BMD (r = 0.56) (all P < .01). Multivariate regression confirmed that GT values were independently associated with both femoral and lumbar T-score/BMD (adjusted R2 = 0.37-0.45, P < .001), even after controlling age, sex, and tear size.

Preoperative CT-derived HU values, particularly at the GT, have a moderate correlation with systemic T-scores and BMD in patients with rotator cuff tears. Given the lower HU values observed at the anchor insertion sites (GT and lateral regions), clinicians should consider the risk of bone fragility during surgical planning.