Coronoid process and radial head as posterolateral rotatory stabilizers of the elbow.

BACKGROUND The purpose of this study was to evaluate the role of the radial head and the coronoid process as posterolateral rotatory stabilizers of the elbow and to determine the stabilizing effect of radial head replacement and coronoid reconstruction. METHODS The posterolateral rotatory displacement of the ulna was measured after application of a valgus and supinating torque (1). in seven intact elbows, (2). after radial head excision, (3). after sequential resection of the coronoid process, (4). after subsequent insertion of each of two different types of metal radial head prostheses (a rigid implant and a bipolar implant with a floating cup), and (5). after subsequent reconstruction of the coronoid with each of two different techniques in the same cadaveric elbow. RESULTS The posterolateral rotatory laxity averaged 5.4 degrees in the intact elbows. The surgical approach used in this study insignificantly increased the mean laxity to 9 degrees. Excision of the radial head in an elbow with intact collateral ligaments caused a mean posterolateral rotatory laxity of 18.6 degrees (p < 0.0001). Additional removal of 30% of the height of the coronoid fully destabilized the elbows, always resulting in ulnohumeral dislocation despite intact ligaments. Implantation of a rigid radial head prosthesis stabilized the elbows. However, a mean laxity of 16.9 degrees persisted after insertion of a floating prosthesis (p < 0.0001). The elbows with a defect of 50% or 70% of the coronoid, loss of the radial head, and intact ligaments could not be stabilized by radial head replacement alone, but additional coronoid reconstruction restored stability. CONCLUSIONS The results of this study suggest that the coronoid and the radial head contribute significantly to posterolateral rotatory stability.

[1]  B F Morrey,et al.  The unstable elbow: An evidence-based approach to evaluation and management , 2017 .

[2]  H. Jacob,et al.  Physical Equilibrium of the Normal Wrist and Its Relation to Clinically Defined “Instability” , 1995, Journal of hand surgery.

[3]  B F Morrey,et al.  Biomechanical study of ligaments around the elbow joint. , 1991, Clinical orthopaedics and related research.

[4]  B. Morrey,et al.  Chronic posterior subluxation and dislocation of the radial head. , 1991, The Journal of bone and joint surgery. American volume.

[5]  James A. Johnson,et al.  Ligamentous Stabilizers Against Posterolateral Rotatory Instability of the Elbow , 2001, The Journal of bone and joint surgery. American volume.

[6]  Charles A. Rockwood,et al.  Rockwood and Green's Fractures in Adults , 1991 .

[7]  J. O. Søjbjerg,et al.  Elbow joint kinematics after excision of the radial head. , 1999, Journal of shoulder and elbow surgery.

[8]  J. O. Søjbjerg,et al.  Posterolateral elbow joint instability: the basic kinematics. , 1998, Journal of shoulder and elbow surgery.

[9]  H. Moritomo,et al.  Reconstruction of the coronoid for chronic dislocation of the elbow. Use of a graft from the olecranon in two cases. , 1998, The Journal of bone and joint surgery. British volume.

[10]  L. Rogers,et al.  Fractures and dislocations of the elbow. , 1978, Seminars in roentgenology.

[11]  B F Morrey,et al.  Functional anatomy of the ligaments of the elbow. , 1985, Clinical orthopaedics and related research.

[12]  B. Morrey,et al.  Fractures of the coronoid process of the ulna , 1989, The Journal of bone and joint surgery. American volume.

[13]  H. Hastings,et al.  Rotatory Instability of the Elbow. The Anatomy and Role of the Lateral Stabilizers* , 1997, The Journal of bone and joint surgery. American volume.

[14]  B. Morrey,et al.  Ligamentous reconstruction for posterolateral rotatory instability of the elbow. , 1992, The Journal of bone and joint surgery. American volume.

[15]  J. Macdermid,et al.  Arthroplasty with a Metal Radial Head for Unreconstructible Fractures of the Radial Head , 2001, The Journal of bone and joint surgery. American volume.

[16]  D. Ring,et al.  Posterior Dislocation of the Elbow with Fractures of the Radial Head and Coronoid , 2002, The Journal of bone and joint surgery. American volume.

[17]  J. O. Søjbjerg,et al.  Lateral collateral ligament of the elbow joint: anatomy and kinematics. , 1996, Journal of shoulder and elbow surgery.

[18]  B F Morrey,et al.  Contribution of Monoblock and Bipolar Radial Head Prostheses to Valgus Stability of the Elbow , 2001, The Journal of bone and joint surgery. American volume.