Valgus Instability of the Elbow Due To Ulnar Collateral Ligament Injury
By Marc R. Safran, MD
Valgus instability of the elbow is characterized by pain and instability at the medial aspect of the elbow due to the sprain, attenuation, or rupture of the ulnar collateral ligament (UCL). As more is being learned about this ligament, it appears that there may be a spectrum of asymptomatic laxity, especially in athletes who perform overhead throwing maneuvers. Thus, instability should be characterized by symptomatic laxity. The UCL may be injured by a sudden, excessive valgus stress applied to the elbow acutely or with dislocation of the elbow. However, it more commonly is the result of repetitive valgus stress in overhead sports such as baseball, tennis, javelin, or water polo.
The athlete with a UCL injury may complain of medial elbow pain that started with a single "pop" or giving away of the elbow during a throw. This may indicate acute rupture of the UCL or acute rupture of a chronically attenuated UCL. More often, many athletes experience low-grade medial elbow pain worsening with continued throwing with no history of 1 single throw as the initiating event and often note they are able to throw to 75% without problem, but are unable to throw harder than 75-80%. Pain is frequently described during the late cocking or early acceleration phase of throwing, a sensation of the elbow "opening" during throws, and/or decreased velocity or distance of throws.
They may also complain of multiple secondary problems, including ulnar nerve symptoms, medial epicondylitis, valgus extension overload syndrome (VEOS), or radiocapitellar overload syndrome (RCOS). With continued activity in the presence of persistent laxity of the UCL, the subject may develop ulnar nerve symptoms. This is usually due to excessive traction on the nerve as a result of the medial laxity, though it may also be the result of compression from scarring of the injured ligament, abrasion from osteophytes and/or the inflammation that occurs with acute injury. Furthermore, the nerve is susceptible to nerve subluxation at the cubital tunnel. Medial epicondylitis symptoms result from attempts at dynamic medial stabilization or overuse of the flexor pronator muscles. VEOS occurs due to the excessive shearing of the olecranon within the fossa when there is increased medial joint laxity. RCOS may occur as the radiocapitellar joint serves as a secondary restraint to valgus stress. When the UCL is incompetent, valgus stress results in radiocapitellar degeneration. Symptoms of loose bodies resulting in lateral elbow pain and locking may result from RCOS or VEOS.
Physical exam of the UCL begins with inspection and palpation of the elbow. There may be pain on palpation 2 cm distal to the medial epicondyle at the insertion of the UCL on the ulna. This pain may be worsened by valgus stress applied to the elbow. Valgus stress test to detect medial elbow instability may be performed several ways. The key is to not have the ulna engaged within the olecranon (flex more than 20°). One classic method is to firmly lock the athlete’s hand and wrist between the examiner’s elbow and trunk. Bend the athlete’s elbow 30° and with the heel of the examiner’s hand, gently apply valgus stress to the elbow. Palpate the medial joint line with a finger over the UCL feeling for laxity. Increased laxity as compared with the other elbow and/or no firm end point indicates incompetence of the UCL due to rupture or attenuation. Of note, humeral rotation may confound the examination. Other methods to examine the elbow include the patient grabbing the thumb of the arm to be examined with the other arm brought underneath the arm being examined. The joint line is palpated while the patient pulls down on the thumb, imparting a valgus stress to the elbow. Recently, a dynamic stress test has been identified where the arm is held in abduction and external rotation, and the elbow taken through flexion-extension. This should reproducibly cause pain in the arc between 80° and 120°.
Due to the small amount of laxity necessary to cause instability, diagnosis of this injury may be underestimated, missed, or misdiagnosed. Success of clinically determining laxity on physical examination ranges between 26% and 82%.1, 4
Plain radiographs cannot diagnose acute UCL injury but can identify chronic injury (traction spurs, calcification within the ligament) and help rule out osteophytes, loose bodies, avulsion fractures, and degenerative joint disease. Stress radiographs may be of value, as a 2-3 mm increase in medial joint opening compared with the normal elbow is consistent with a UCL tear. This may be done with the gravity stress test, a commercially available stress device, or with manual stress. Each has their benefits and drawbacks. Stress tests have been shown to be 45-88% sensitive.
MRI can show partial or full-thickness tears of the UCL in addition to other intra-articular pathology. The sensitivity of MRI in the diagnosis of UCL injury ranges from 57-79% without contrast and 97% sensitive when intra-articular contrast is added.
Treatment of UCL injuries begins with icing the elbow (to protect the ulnar nerve), taking nonsteroidal anti-inflammatory medications as needed, and short-term immobilization with sling as needed. Relative rest for 2- 4 weeks is followed by active range of motion when pain-free. Physical therapy modalities can be used to aid healing. Once pain-free, a strengthening program is initiated followed by a throwing program when range of motion is full and strength equal to the contralateral side. One study noted 42% return to sports with nonoperative treatment of nearly half a year.3
Surgical reconstruction is indicated for the complete rupture of the UCL in a thrower, or failed nonsurgical treatment after 3 months in the athlete who desires a return to high-level competitive throwing or overhead sports. Acute UCL avulsions may be repaired with suture anchors to bone, though this is not as common as with lateral UCL injuries because lateral UCL injuries tend to be avulsions off the humerus with a sliver of bone, which are quite amenable to suture anchor repair as opposed to midsubstance UCL injuries. The gold standard for reconstruction of the UCL is use of a free autogenous graft.2 This traditionally has been done through a Y’-shaped tunnel on the humeral side and straight tunnel on the ulnar side in a 3-ply figure-of-8 technique. However, newer techniques, including a single blind-ended tunnel on the humerus for a 2-ply reconstruction (docking procedure), a blinded tunnel on both the ulnar and humeral sides fixed with an interference screw, or an onlay technique fixed with suture anchors have been performed with reduced morbidity perhaps due to muscle sparing. However, long-term studies are still needed to confirm the success of these reconstruction modifications. Postoperative rehabilitation programs vary, but most incorporate hand and wrist exercises immediately with transfer from a posterior splint to a functional brace at 2 weeks. Full elbow range of motion is expected by about 6 weeks. Throwing generally can begin by 4 months with return to competitive throwing between 6 months and 1 year. The success rate of surgery is reported as 79-96% in recent studies for return to sports at the same level.
References
1 Azar FM, et al. Operative treatment of ulnar collateral ligament injuries of the elbow in athletes. Am J Sports Med. 2000;28:16-23.
2. Conway JE, et al. Medial instability of the elbow in throwing athletes. Treatment by repair or reconstruction of the ulnar collateral ligament. J Bone Joint Surg Am. 1992;74A:67-83.
3. Rettig AC, et al. Non-operative treatment of ulnar collateral ligament injuries throwing athletes. Am J Sports Med. 2001;29(1):15-17.
4. Thompson WH, et al. Ulnar collateral ligament reconstruction in athletes: Muscle splitting approach without transposition of the ulnar nerve. J Shoulder Elbow Surg. 2001;10:152-157.
Valgus instability of the elbow is characterized by pain and instability at the medial aspect of the elbow due to the sprain, attenuation, or rupture of the ulnar collateral ligament (UCL). As more is being learned about this ligament, it appears that there may be a spectrum of asymptomatic laxity, especially in athletes who perform overhead throwing maneuvers.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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