In vivo quantification of capsular end-point in the nonimpaired glenohumeral joint using an instrumented measurement system

• Published in: The journal of orthopaedic and sports physical therapy 2001-08, Vol.31 (8), p.419-431
• Main Authors: Borsa, P A, Sauers, E L, Herling, D E, Manzour, W F
• Format: Article
• Language: English
• Subjects: Adult; Analysis of Variance; Anthropometry - methods; Biomechanical Phenomena; Endpoint Determination; Equipment Design; Female; Humans; Joint Capsule - physiology; Joint Instability - diagnosis; Male; Shoulder Joint - physiology
• ISSN: 0190-6011; 1938-1344
• DOI: 10.2519/jospt.2001.31.8.419

Single-group factorial. Quantify glenohumeral joint translations as a function of force using an instrumented measurement system. Our first specific aim was to compare the magnitude of force (N) required to reach capsular end-point between the anterior, posterior, and inferior directions. Our second specific aim was to compare the magnitude of translation (mm) at capsular end-point between the anterior, posterior, and inferior directions. Manual force-displacement techniques are subjective in nature, and the clinician must rely on "feel" to determine capsular end-point. Several investigators have attempted to utilize more objective measures at the glenohumeral joint, however none have quantified the force or displacements necessary to achieve a true capsular end-point. An arthrometric technique was used to measure anterior, posterior, and inferior glenohumeral translations in 20 nonimpaired shoulders (11 women and 9 men with a mean age of 20.9 +/- 3.6 years). The magnitude of applied force required to reach capsular end-point was significantly different between directions of translations. Anterior-directed translations required a significantly greater magnitude of applied force to reach capsular end-point than inferior-directed translations. The magnitude of translation was not significantly different between directions at capsular end-point. Applied forces in the range of 181 to 203 N are necessary to reach capsular end-point in subjects with nonimpaired shoulders. Anterior translation required significantly higher forces (203.1 +/- 13.1 N) to reach capsular end-point than inferior translation (181.4 +/- 31.9 N).