The ulnar collateral ligament (UCL) of the elbow, also known as the medial collateral ligament, plays an important role in stabilizing the elbow to valgus stress. There are three discreet anatomic structures that collectively form the UCL, namely the anterior bundle, posterior bundle, and the transverse ligament.
The anterior bundle is the strongest of these structures and is the most important ligamentous restraint to valgus deformation of the elbow joint. The anterior bundle originates from the anteroinferior aspect medial epicondyle and courses obliquely to attach near the base of the coronoid, at the sublime tubercle of the ulna. Injury to the UCL can result in disabling instability of the elbow. In addition to a complete clinical assessment to diagnose valgus instability due to UCL insufficiency, a thorough assessment of the patient’s functional requirements and expectations is necessary to determine the best treatment option.
There are several mechanisms of injury commonly associated with UCL dysfunction. These include elbow dislocation, acute valgus or hyperextension strain, and chronic valgus overload. Elbows are the most commonly dislocated joint in the child, and the second most common in adults. Dislocations without associated bony injury are classified as simple, while those with associated fracture are termed complex.
Athletes with a higher incidence of UCL injury secondary to mechanisms of acute valgus/hyperextension or chronic valgus overload include baseball pitchers, javelin throwers, quarterbacks, and tennis players.
In cases of acute valgus overload, patients may complain of sudden onset medial-sided elbow pain during throwing, with subsequent swelling and bruising. In chronic overload injury, pain tends to worsen over time, with progressive decline in performance as the UCL attenuates. Athletes may also present with acute-on-chronic UCL insufficiency, with a precipitous decline in function over a short period, after a seemingly acute event.
Pitchers typically correlate UCL-related pain with the late cocking/early acceleration phase of throwing. Throwers may also complain of symptoms such as numbness in the ulnar nerve distribution. This may develop secondary to ulnar neuritis, which usually resolves uneventfully with rest. In younger throwers who have not yet undergone physeal closure, overload of the UCL may result in avulsion of the medial apophysis, leaving the UCL intact.
Physical examination findings may vary depending on the acuity of presentation. A more acute or traumatic injury to the UCL typically presents with medial elbow pain and discomfort on palpation along the medial soft tissue structures. Swelling may be present and range of motion reduced comparatively to the contralateral elbow. Signs and symptoms consistent with ulnar neuropathy may be identified secondary to stretch injury.
Special tests to identify UCL insufficiency include the valgus stress test, the milking maneuver, and the moving valgus stress test.
The valgus stress test is performed with the elbow in 30 degrees of flexion, to unlock the ulnohumeral articulation. It is important to compare perceived laxity to the contralateral elbow, to ensure the findings are consistent with pathologic instability.
The milking maneuver is performed by pulling on the patient’s thumb to provide a valgus stress with the elbow in 90 degrees of flexion and the forearm supinated. Pain or medial-sided elbow instability indicate a positive test.
Originally described by O’Driscoll, the moving valgus stress test is performed by quickly ranging the elbow through a full arc from flexion to extension while maintaining a valgus stress. Pain or instability between 70 degrees and 120 degrees denotes a positive test.
Radiographic investigation begins with standard AP and lateral views of the elbow. With isolated elbow UCL insufficiency, static radiographs may be normal. Instability secondary to avulsion of the medial epicondyle is readily identified. Radiographic changes more commonly seen in throwers include ossification along the UCL, and posteromedial osteophytes. An oblique axial view with the elbow in 110 degrees of flexion may allow for better visualization of posteromedial osteophytes in throwers.
Valgus stress imaging with the elbow flexed to 30 degrees may be used, with ulnohumeral joint widening of > 2mm considered positive. However, positive valgus stress radiograph findings in patients with non-pathologic laxity, and inconsistent reproducibility of this test have lead some to question the value of obtaining stress views.
MRI or MR arthrogram are the most sensitive and specific imaging modalities to diagnose elbow UCL injury and remain the imaging modalities of choice. MRI can be used to localize ligamentous pathology about the elbow, and to characterize the extent of partial or full-thickness tears. Associated intra- or extra-articular pathology is also readily identified by MRI.
Mechanism of injury is an important consideration when deciding between management options. In the event of an acute simple elbow dislocation, the majority of cases of valgus instability can be treated with a brief period of immobilization, typically no longer than 1 week, followed by progression of range of motion. At the time of reduction, physical examination should determine the stable arc within which the elbow remains well-articulated. In the case of UCL injury, immobilization in pronation may improve stability. Should instability after reduction remain near extension, gradual increases in range of motion may be accomplished in a hinged brace, with increases in extension of 10 degrees per week after an initial brief period of immobilization.
In cases of an acute UCL injury in throwing athletes, a period of complete rest from throwing should be initiated and will typically last 3 months. During this time the athlete should be protected in a hinged brace and perform regular flexor-pronator strengthening exercises. A throwing program may begin at the 3-month mark as long as the athlete remains comfortable. Rehabilitation should progress slowly with expected return-to-play anywhere from 6-12 months after injury.
Chronic valgus overload injuries in the athlete should also initially be treated with complete removal from the inciting activity. As in cases of acute injury, flexor-pronator strengthening exercises should be performed regularly under the guidance of a physical therapist. Sport specific rehabilitation should not be initiated until after 2-3 months of rest, and gradually progressed at that time if the athlete remains asymptomatic. With respect to acute UCL strain or chronic valgus overload injuries in the athlete, attention should be paid to sport specific techniques, alteration of which may help reduce risk of re-injury. Surgical stabilization should be considered in those athletes who continue to have instability after an appropriate course of rehabilitation, and who wish to return to their previous level of play.
Indications for Surgery
In cases of UCL injury associated with simple elbow dislocation, sufficient stabilization is often achieved without surgical intervention. In the event of complex dislocation, surgical treatment to address the associated fractures and lateral soft tissue injury typically results in stable ulnohumeral and radiocapitellar articulation. Surgical management of UCL injury in the setting of elbow dislocation is reserved for those uncommon instances where there is persistent valgus or ulnohumeral instability.
Symptomatic elbow instability in the athlete due to an acute valgus strain or chronic valgus overload often responds well to non-operative management. Ensuring a thorough assessment of the degree of dysfunction and understanding the expectations of the patient are essential. Should the athlete continue to be unable to compete at an acceptable level after appropriate rest and rehabilitation, surgical reconstruction of the UCL may allow for successful return-to-play. Comprehensive scrutiny of a thrower’s technique is imperative whether the athlete undergoes operative or non-operative treatment. Making the necessary alterations to technique will quicken rehabilitation advancement, and reduce risk of re-injury.
Surgical treatment necessitates reconstruction of the anterior bundle of the UCL, although repair of a ligamentous avulsion may be possible after acute injury. In the setting of UCL reconstruction, there are a number of graft types to consider. Good outcomes have been demonstrated with both autograft and allograft tendons. Autograft palmaris longus or gracilis tendon are commonly used, as are allograft hamstring and extensor hallucis longus tendon. In our practice, autograft is used whenever possible.
An examination under anaesthesia is performed. The patient is placed in the supine position, with the operative extremity placed on an arm board with the shoulder externally rotated and forearm supinated to adequately visualize the medial elbow. A tourniquet is typically placed on the upper arm and inflated over the course of the procedure. Should a palmaris longus or hamstring tendon autograft be used, appropriate draping should be used to expose the graft harvest site, and procurement of the graft should proceed as usual.
Exposure begins with a 10 cm incision centered over the medial epicondyle. Dissection is carried down to the flexor-pronator mass where the overlying myofascia is incised. Identify and protect the medial antebrachial nerve and its branches. Ulnar nerve exposure and/or transposition is not routinely necessary. However, in our practice, routine release and transposition is performed to protect the nerve throughout the procedure. Also, a release or transposition of the ulnar nerve should be considered if there are preoperative symptoms consistent with ulnar nerve pathology. After exposure of the flexor-pronator mass, a longitudinal split is made to expose the underlying UCL.
This split is continued to the level of the medial epicondyle of the humerus. In the absence of an UCL tear that can be exploited, a longitudinal split is created along the length of the UCL to expose the ulnohumeral articulation. The joint space should be visualized to identify any intra-articular pathology, or remove loose bodies. In addition, posterior olecranon osteophytes, if present, can be removed through a posterior arthrotomy through the same incision.
Bony landmarks are adequately exposed in preparation for graft placement. Proximally, the attachment site of the anterior bundle of the UCL at the medial epicondyle should be identified. Distally, the sublime tubercle adjacent to the base of the coronoid should be exposed.
A number of techniques have been described for graft placement and fixation. Originally, the technique by Jobe consisted of the creation of two drill holes at the sublime tubercle, taking care to leave a bone bridge of at least 5 mm, for distal passage of the graft. Proximally, a hole is then drilled at the medial epicondylar UCL attachment site from distal to proximal. Two additional holes are then drilled at the proximal aspect of the medial epicondyle, one biased anteriorly, and the second posteriorly. This creates a Y-type configuration about the medial epicondyle for graft passage. Appropriate drill diameter will vary depending on graft size.
After whipstitching the ends of the graft with heavy non-absorbable suture, a passing suture is used to pass the graft in a figure-of-eight configuration through the tunnels distally and proximally. With the forearm supinated and elbow flexed to 50-70 degrees, a varus stress is applied. The graft is tensioned and heavy non-absorbable suture is used to secure the tails of the graft onto itself to complete the figure-of-eight construct. A valgus stress is applied through a range of flexion and extension to ensure adequate stabilization.
Variations of this technique include fixation with interference screws, and use of a docking technique or a hybrid technique.
Fixation with an interference screw both distally and proximally allows for less soft tissue dissection to expose the insertion sites for graft placement, as only a single drill hole is used at each end. Proper tensioning of the graft with the use of interference screws may be more problematic.
The docking technique involves placing the graft tails through a common drill hole proximally at the medial epicondyle, with the suture tails exiting through two smaller drill holes. The two graft ends are then tensioned and the suture tails are tied over a bony bridge.
A hybrid technique utilizes suture anchors for fixation proximally at the humerus to avoid potential complications associated with drilling tunnels.
After stability of the reconstruction is confirmed, the native UCL remnant is sutured closed over the graft. Suturing of the native UCL may incorporate the graft to enhance fixation. Overlying flexor-pronator fascia is then closed, followed by the subcutaneous and skin layers in standard fashion. The tourniquet should be released prior to final closure to ensure adequate hemostasis.
Pearls and Pitfalls of Technique
Care should be taken to make certain appropriate bone bridges are maintained between tunnels. Commercial guides are now available that can facilitate drilling.
When utilizing the docking technique, graft tensioning on the humeral side needs to be carefully planned.
Nerve palsy affecting the ulnar nerve or branches of the medial antebrachial cutaneous nerve is the most common post-operative complication. Paraesthesias are the typical presenting symptom, and this usually completely resolves.
There is a risk of painful neuroma formation should transection of the medial antebrachial cutaneous nerve occur, and this has a less predictable course of recovery. Avoiding exposure and handling of the ulnar nerve intra-operatively has been shown to reduce the incidence of post-operative ulnar nerve palsy.
Should the patient require a release or transposition due to pre-operative ulnar nerve symptoms, careful manipulation of the nerve will minimize risk of post-operative paraesthesia. Furthermore, meticulous hemostasis may reduce hematoma formation and subsequent ulnar nerve compression in the early post-operative period.
Stiffness and reduced elbow range of motion compared to pre-operative movement is not a common occurrence. Minimizing restriction of elbow range of motion post-operatively will help prevent stiffness.
The elbow is briefly immobilized until the first post-operative visit and wound check. At this time a hinged elbow brace may be fitted to ensure maintained stability of the reconstruction, however, good outcomes have also been demonstrated without use of a hinged brace post-operatively. While some surgeons choose to fix the brace range of motion and gradually allow increases on a weekly basis, biomechanical studies have demonstrated full elbow extension to be safe. It is reasonable to allow the brace to remain unlocked in order to minimize stiffness post-operatively.
Active shoulder, elbow, and wrist range of motion exercises are begun as soon as the patient is comfortable. Strengthening exercises may begin at 6 weeks. Bracing should be discontinued by 12 weeks. With the exception of competitive throwers, unrestricted activity may typically resume at 6 months. In the case of throwers, a gradual throwing program may resume 4 months post-operatively if comfortable for the athlete. This should begin with gentle ball tossing exercises (throwing program), and progress to competitive throwing at 1 year.
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