Intraoperative measurements of the subacromial distance

Purpose: The purpose of this study was 2-fold: to document the accuracy of a new measuring device and to intraoperatively compare the subacromial distance between controls and patients with impingement syndrome before and after arthroscopic subacromial decompression (ASD). Type of Study: Clinical study. Methods: When performing an ASD, it is important that bone resection is adequate. Today the correct subacromial distance after bone resection is only assessed by eye, directly or indirectly. The subacromial distance was measured between the anterolateral corner of the acromion and the supraspinatus tendon in the lateral decubitus position. The device was inserted 2 to 3 cm below the anterolateral acromion. There was no subacromial pathology among the controls (n = 15, mean age, 28 years). In 30 patients with impingement syndrome (average age, 53 years) an ASD was performed. The subacromial distance was measured after bursectomy and then after bone resection. Intraindividual and interindividual assessment was performed. Results: The mean value of the subacromial distance in controls was 16 mm, the 95% confidence limits between 14 and 18 mm. The mean value in the group of patients with impingement syndrome was 8 mm before and 16 mm after the decompression. Due to the pressure within the subacromial space, the subacromial distance increased 1 mm. Intraindividual measurements never varied more than 1 mm (n = 5). The correlation coefficient between the measurements by both authors was 0.99. Conclusions: In this study, we assessed and described the use of a measuring device that enables the surgeon to quantify the subacromial distance before and after bone resection. After bone resection, the mean value of the subacromial distance was well within the control values. The amount of bone resected varied from 5 to 13 mm. This new device enables documentation in clinical work as well as in research. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 18, No 4 (April), 2002: pp 347–352