The Naked Capitellum: A Surgeon's Guide to Intra-Operative Identification of Posterolateral Rotatory Instability
Michael S Guss, MD1; Lindsay K Hess, BS1; Mark E. Baratz, MD2
1University of Pittsburgh, Pittsburgh, PA, 2Hand and Upper Extremity Surgery, University of Pittsburgh Medical Center, Washington, PA
Introduction: This study's aim was to provide an easy and reproducible way for surgeons to intra-operatively assess the status of the lateral ulnar collateral ligament (LUCL) origin and determine if there is posterolateral rotatory instability (PLRI) despite an intact common extensor origin. We hypothesized that we could recreate clinically relevant disruption of lateral supporting structures and illustrate progressive posterolateral instability of the elbow.
Methods: Using eight human cadaveric upper extremities the radiocapitellar joint was approached through an extensor-splitting approach. The lateral capsule posterior to the mid-axis of the radiocapitellar joint contains the LUCL. The relationship of the lateral capsule to the articular surface of the capitellum was noted. Next, the lateral capsule and extensor origin were sequentially sectioned. The posterior and lateral translation of the radial head (RH) relative to the capitellum was measured at 4 stages of sectioning: intact, release of capsule to the lateral epicondyle, release of posterior capsular insertion and release of the common extensor origin. All measurements were made with a digital caliper.
Discussion: The elbow's lateral capsule and LUCL complex plays an important role in preventing PLRI. The lateral capsule normally originates within 1-2 mm of the capitellar artiicular margin. Progressively larger degrees of elbow laxity are associated with further peel-back of the capsule despite an intact extensor origin.
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