Humeral head inferior subluxation in proximal humerus fractures
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The objectives of this study are to propose a reliable radiologic method for detecting static inferior subluxation of humeral head, to calculate the relative intra- and inter-observer reliability, and to evaluate its presence pre- and post-surgery.
This is a retrospective observational study of patients surgically treated for a fracture of the proximal humerus. Fractures were classified using Codman-Lego criteria (radiographic, CT images), osteoporosis was assessed. To identify inferior subluxation, an original method is proposed. This measurement was done pre-operatively, at three and 12 month post-operatively. Clinical evaluation was recorded at final follow-up using Constant Score.
One hundred fifty fractures surgically treated were studied. Intra- and inter-observer reliabilities were excellent and high, respectively. In pre-operative x-rays, a significant inferior subluxation was noted in 17/150 cases (11.3%), with significant correlation with fracture pattern (p=0.045), female sex (p=0.038), age older than 70 (p=0.003), obesity (BMI>30, p=0.03), and local osteoporosis (p=0.002). At three month of follow-up, 22 cases (14.6%) had inferior subluxation, with significant correlation with female sex (p=0.04), age older than 70 (p=0.002), obesity (p=0.02), pin or screw articular surface perforation (p<0.001). At 12 month of follow-up, seven cases showed persistent inferior subluxation, with significant correlation with age older than 70 (p=0.032), obesity (p=0.041), screw joint perforation and lower Constant Score (p<0.001).
Inferior subluxation was mostly found in osteoporotic fractures of the elderly, obese, and of female sex both pre- and post-operatively. The intra- and inter-observer reliabilities of proposed radiographic measurement were high and excellent, respectively.
In the early postoperative months, we found a high correlation between inferior subluxation and articular surface perforation; when persisting at later follow-ups, we might speculate that it could represent an early phase of avascular necrosis of the humeral head.
Level of evidence
Level III, observational study.
KeywordsStatic inferior subluxation Proximal humerus fractures Osteoporosis Screw joint perforation Avascular necrosis
Conflict of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
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