CHAPTER 47 Diagnosis and Treatment of Ulnar Collateral Ligament Injuries in Athletes
INTRODUCTION
Injury to the elbow medial ulnar collateral ligament (MUCL) from valgus forces was first recognized in a javelin thrower in 1946.32 The injury has since become well recognized in baseball pitchers and other overhead throwing athletes. Frank W. Jobe developed the original MUCL reconstruction and described the technique with initial results in 1986.17 The technique transected and reflected the flexor-pronator mass, transposed the ulnar nerve to a submuscular position, and created humeral tunnels that penetrated the posterior humeral cortex. Excellent exposure was achieved at the expense of morbidity to the flexor-pronator mass and handling the ulnar nerve. Since that initial report, modifications in the surgical technique have been made to ease technical demands and decrease soft tissue morbidity. A muscle-splitting approach has been developed to safely avoid detachment of the flexor-pronator mass with or without subcutaneous transposition of the ulnar nerve.29,30 Modifications in bone tunnel creation have also been made that direct the tunnels anterior on the humeral epicondyle to avoid risk of ulnar nerve injury while still allowing figure-of-eight graft passage and configuration.30 Further changes in bone tunnel configuration have reduced the total number of tunnels and facilitate easier graft tensioning.1,27 Results with these modified techniques have proven effective in returning high-level athletes back to throwing. In addition to advancements in surgical technique, advancements have been made in the pathophysiology and diagnosis of MUCL injuries. This chapter describes MUCL pathophysiology, patient evaluation, and surgical indications, and describes three popular surgical techniques.
PATHOPHYSIOLOGY
The anterior bundle of the MUCL is the strongest component and the primary restraint and stabilizer to valgus stress.5,16,22,25 The AOL is functionally composed of anterior and posterior bands that provide a reciprocal function in resisting valgus stress through the range of flexion-extension motion.20,25 Valgus stress is generated at the elbow during throwing maneuvers in baseball, softball, football, tennis serving, and volleyball spiking. The calculated valgus torque during the acceleration phase of throwing is 64 N-m,14,33 and more than 60 N-m with the tennis serve.11,13 These estimated forces exceed the known ultimate tensile strength of cadaveric MUCL specimens (33 N-m).38 Thus the MUCL is at risk for injury from these repetitive forces. A cadaver model has demonstrated that the flexor carpi ulnaris is the primary dynamic contributor to valgus stability and the flexor digitorum superficialis is a secondary stabilizer.24 Thus, the muscular dynamic stability to the medial elbow is essential and must be included in rehabilitation programs and morbidity from surgical techniques must be minimized.
DIAGNOSIS
HISTORY
Patients with MUCL injuries complain of medial elbow pain during the acceleration phase of throwing (Fig. 47-1). Chronic injuries present gradually and often with pain occurring only when throwing greater than 50% to 75% of maximal effort. Acute injuries may present suddenly with a pop, sharp pain, and inability to continue throwing. Patients may be affected with valgus extension overload syndrome associated with MUCL insufficiency. Occasionally, the presenting symptoms of VEO overshadow the symptoms of MUCL insufficiency, especially in the setting of chronic slowly progressive ligament attenuation. In these cases, the symptoms of sharp posteromedial elbow pain in both the acceleration (flexion) and more so in deceleration (extension) phases of throwing are also associated with limited extension and mechanical catching resulting from impinging osteophytes, chondromalacia, and loose bodies.
PHYSICAL
Physical examination features indicating MUCL injury include point tenderness directly over the MUCL or toward its insertion sites. Valgus instability is tested with the patients’ elbow flexed between 20 and 30 degrees to unlock the olecranon from its fossa as valgus stress is applied (Fig. 47-2). The milking maneuver is performed by either the patient or the examiner pulling on the patient’s thumb to create valgus stress with the patients’ forearm supinated and elbow flexed beyond 90 degrees. The moving valgus stress test is performed by applying valgus torque while the elbow is then flexed and extended and is considered positive if the medial elbow pain is reproduced at the MUCL and is maximum between 70 and 120 degrees (Fig. 47-3). The moving valgus stress test is highly sensitive and specific.
IMAGING
Anteroposterior, lateral, and axillary views of the elbow are assessed for joint space narrowing, osteophytes, and loose bodies. Valgus stress radiographs may be used to measure medial joint line opening, and an opening greater than 3 mm has been considered diagnostic of valgus instability.6,17,30 However, mild increased valgus elbow laxity has been observed in uninjured, asymptomatic dominant elbows of professional baseball pitchers when compared with their nondominant elbow.10 Computed tomography and magnetic resonance imaging (MRI) may further define loose bodies and osteophytes. Conventional MRI is capable of identifying thickening within the ligament from chronic injury or more obvious full-thickness tears. MR arthrography enhanced with intra-articular gadolinium improves the diagnosis of partial undersurface tears.7,15,21 Therefore the preferred imaging technique is MR enhanced with intra-articular gadolinium contrast, high-field closed magnet, and narrow slice images. Figure 47-4 demonstrates a full thickness tear of the MUCL from its attachment to the medial humeral epicondyle.
FIGURE 47-4 Magnetic resonance imaging scan with arrow indicating ulnar collateral ligament tear.
(From Ahmad, C. S.: Elbow injuries and the throwing athlete. In Galatz, L. M. [ed.]: Orthopaedic Knowledge Update: Shoulder and Elbow 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2007, with permission.)
Dynamic ultrasonography has recently been studied as a means to evaluate the MUCL and is capable of detecting increased laxity with valgus stress.28 Advantages of ultrasound is that it is noninvasive, inexpensive, and dynamic. A disadvantage lies in dependence on operator experience.
TREATMENT
INDICATIONS AND CONTRAINDICATIONS
Treatment decisions require consideration of the patient’s athletic demands and the degree of MUCL injury. Nonoperative treatment includes a 6-week period of rest from throwing and flexor-pronator strengthening.24 If the patient becomes asymptomatic and the physical examination normalizes, then return to throwing with optimizing throwing mechanics is started. Rettig and colleagures26 demonstrated a 42% return to same level of play with an average return at 24.5 weeks with nonoperative treatment. No history or physical examination features are predictive for athletes who will respond to nonoperative treatment. Local steroid injections should be avoided because it may risk further injury to the MUCL.
SURICAL TECHNIQUES
Several surgical techniques have evolved, and each has advantages and disadvantages. The modified Jobe technique has been considered the gold standard and has a reported success rate as high as 93% in returning throwing athletes back to competition (Fig. 47-5). This technique is technically demanding, however, in regard to number of tunnels, exact placement and connecting of tunnels, graft passing, and graft fixation. The docking technique has the advantages of reducing the complex ity of tunnel creation, passing and tensioning, and fixation. A potential disadvantage is that the graft is reduced from a triple strand used in the Jobe technique to a double-strand graft. However, a modification of the technique now allows doubling the graft on itself to form a quadruple limb graft. Finally, the hybrid interference screw technique has the advantage of further reducing the number and complexity of tunnel creation. With a single tunnel required on the ulna, there is less manipulating and risk of injury to the ulnar nerve. Furthermore, this technique allows independent tensioning of the anterior and posterior bands of the anterior bundle of the UCL, which is not accomplished with the other described techniques. A disadvantage is potential inflammatory reaction to the bioabsorbable screws.
FIGURE 47-5 Classic Jobe UCL reconstruction.
(Redrawn from Safran, M., Ahmad, C. S., and ElAttrache, N. S.: Ulnar collateral ligament of the elbow. Arthroscopy 21:1381, 2005, with permission.)
Jobe Technique
The patient is positioned supine with a pneumatic tourniquet on the upper arm. A skin incision centered over the medial epicondyle is extended 5 cm both proximally and distally. Dissection is carried down to the muscle fascia, and sensory branches of the medial antebrachial cutaneous nerve are consistently identified just anterior and distal to the medial epicondyle. These branches are protected to avoid painful neuroma. A muscle-splitting approach is created by incising the raphe of the flexor carpi ulnaris. A periosteal elevator is used to separate the flexor muscle mass from the MUCL. The ligament is inspected and palpated as valgus stress is applied (Fig. 47-6A). A longitudinal split is made in the ligament and valgus stress applied with the elbow at 30 degrees flexion will reveal opening of the ulnohumeral articulation if the MUCL is insufficient (Fig. 47-6B). Tunnels are then created for graft placement (Fig. 47-7). Converging 3.2-mm drill holes are made in the ulna anterior and posterior to the sublime tubercle with a minimum 5 mm bridge (Fig. 47-8A). The drill holes are connected with an angled curette.
