Capsular Constraint Mechanism

Overview

The concept of Capsular Constraint Mechanism can be applied to a tight join capsule of the shoulder where the humeral head translates in the direction opposite to that of capsular tightness. This concept is typically applied to the shoulder to understand the arthrokinematic movement within the shoulder joint.

Clinical Significance

Mobilization for a stiff or restricted shoulder traditionally follows Kaltenborns' Convex-Concave rule which states that when a convex surface moves over a concave surface the direction of glide or arthrokinematic movement must be opposite to that of the osteokinematic movement. Taking the example of Adhesive Capsulitis, capsular pattern restriction is seen with maximal restriction of external rotation. An anterior glide would improve the restriction and range of motion. However based on the Capsule Constraint Mechanism, the capsular restriction is at the anterior aspect of the shoulder, hence, a posterior glide would stretch the tight capsule rather than an anterior glide.