Initial Repair Strengths of Two Methods for Acute Medial Collateral Ligament Injuries of the Elbow James E. Pichora, 1,2 Keizo Furukawa, 6 Louis M. Ferreira, 1,3 Kenneth J. Faber, 1,5 James A. Johnson, 1,2,3,4,5 Graham J.W. King 1,2,5 1 Bioengineering Research Laboratory, Hand and Upper Limb Centre, St. Joseph’s Hospital, London, Ontario, Canada 2 Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada 3 Department of Biomedical Engineering, University of Western Ontario, London, Ontario, Canada 4 Department of Mechanical Engineering, University of Western Ontario, London, Ontario, Canada 5 Department of Surgery, University of Western Ontario, London, Ontario, Canada 6 Nagasaki University School of Medicine, Nagasaki, Japan Received 19 July 2006; accepted 2 November 2006 Published online 8 February 2007 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jor.20353 ABSTRACT: The purposes of this study were to compare the initial repair strength of the medial collateral ligament (MCL) of the elbow using trans-osseous sutures and suture anchor methods and to determine the effect of repair pretensioning. Twelve, fresh-frozen upper extremities (66  5 years) were mounted in a valgus-loading system. MCL repairs were performed using trans-osseous suture and suture anchor methods with 20 N or 40 N pretensioning. A cyclic (0.5 Hz), valgus 40 N load was applied 12 cm distal to the elbow axis of flexion. The load was increased by 10 N every 200 cycles until a length increase of 5 mm or catastrophic failure of the repair occurred. Repairs pretensioned with 40 N endured a significantly higher number of cycles and failed at higher loads than those pretensioned with 20 N (p < 0.05). No difference was found in the cycles or load to failure between trans-osseous sutures and suture anchors (p > 0.05). A higher magnitude of pretensioning of MCL repairs was found to increase initial repair strength suggesting that pretensioning should be performed clinically. Despite the comparable failure loads of the trans-osseous suture and suture anchor methods, the failure mechanism differed between the two techniques. The suture anchors usually failed catastrophically when the sutures broke as they passed through the anchor eyelet, while the trans-osseous sutures gradually elongated to the defined failure length by stretching and sliding through the ligament. The use of different suture anchors, suture sizes, or suture materials would likely influence the findings of this study and should be considered when applying these findings clinically. ß 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:612–616, 2007 Keywords: elbow; ligament; strength; repair; biomechanics INTRODUCTION Disruption of the medial and lateral collateral ligaments are consistent findings following elbow dislocation. 1 Acute repairs of the medial collateral ligament (MCL) and lateral collateral ligament (LCL) are indicated in selected unstable disloca- tions and fracture dislocations. 2,3 In the case of comminuted radial head fractures treated with excision, the integrity of the MCL is essential to prevent gross valgus instability, because the MCL is the primary stabilizer for valgus stresses. 1,2,4–13 In one cadaveric study on elbows with radial head excision, isolated MCL repair returned internal rotatory laxity to that of the intact state, while valgus stability approached that of the intact elbow. 14 Currently, both suture anchor and trans-osseous suture repairs are commonly performed for collateral ligament repairs. How- ever, the optimal repair method has not been established. The purpose of this in vitro study was to compare the initial strengths of trans-osseous suture (TS) and suture anchor (SA) methods for MCL repair. Additionally, the effects of suture pretensioning loads on repair strength were evaluated. We hypothesized that the two repair methods would 612 JOURNAL OF ORTHOPAEDIC RESEARCH MAY 2007 Correspondence to: Graham J.W. King (Telephone: 519-646- 6011; Fax: 519-646-6049; E-mail: gking@uwo.ca) ß 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.