Valgus instability of the elbow: acute and chronic form

In the assessment of valgus elbow instability, valuable information can be gained from a thorough patient history. Details of the exact moment of the injury, the events leading up to and following it, prior injuries, changes in training regimen, racket tension and grip, and professional occupation must be obtained. In acute cases, the patient may recall a sudden tangible or audible “pop” accompanied by acute pain and a limitation in ROM [27]. More often, patients with chronic injuries will report insidious but gradually worsening or fluctuating symptoms, specifically during a particular causative motion such as throwing. Athletes may also report progressive loss of ball control and throwing performance. The pain usually reaches maximal intensity during the late cocking and early acceleration phases, but with VEOS, athletes may also report posteromedial pain during the deceleration phase caused by posterior osteophyte impingement. Ulnar nerve symptoms at rest or during the provoking motion should also be recorded.

Clinical examination typically starts with inspection of the joint in resting position. Ecchymosis may be present in the case of elbow dislocation (Fig. 4). Palpable fullness of the soft spot is a sign of intra-articular effusion. In the case of acute effusion, the patient will hold the elbow at a flexion angle of 70°, to accommodate the increased intracapsular volume. The carrying angle, between the humerus and forearm, may be higher than the average 11° and 13° in men and women, respectively, as a result of repetitive valgus stretch and MCL elongation [5]. Palpation of the bony structures is paramount during the examination. Point tenderness at the MCL insertion on the sublime tubercle, which is a frequent site of pain in valgus injuries, is indicative of valgus stress injury. Medial epicondyle pain in skeletally immature patients may indicate an avulsion injury after elbow trauma. Active and passive ROM should be assessed with special attention to pain, crepitus, and locking or loss of motion. A hard extension block may indicate a loose body or posterior osteophyte.

While the diagnosis of medial elbow instability is primarily based on the patient history and clinical findings, imaging studies may reveal unsuspected concomitant lesions.

Plain static radiographs may reveal calcifications of the MCL, indicating chronic valgus instability (Fig. 5). Loose bodies, osteophytes, and radiocapitellar pathology may also be seen on standard radiographs.

Valgus stress radiographs can be helpful in cases with equivocal clinical findings. A medial joint line opening of more than 3 mm is considered consistent with valgus instability [19, 38]. Advanced imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) can be valuable tools in the diagnosis of valgus instability (Fig. 6). CT is most helpful in cases with associated bone lesions such as osteochondritis dissecans, fractures, osteophyte formation, and loose bodies (Fig. 7). Contrast-enhanced CT scans allow for the visualization of the medial ligamentous structures. However, we prefer the use of MRI for soft tissue evaluation. MRI can aid in the detection of MCL tears, osteochondral injuries, olecranon osteophytes, loose bodies, and sites of neurologic compression [11, 23, 26]. The addition of contrast arthrography to MRI improves visualization of partial under-surface MCL tears [17]. Saline-enhanced MRI facilitates the evaluation of leakage through the MCL, increasing the sensitivity of the examination from 57 to 92% [25].

Conservative treatment consists of a rehabilitation program after a period of rest and adequate pain control. Immediate mobilization is important in the prevention of stiffness and has been shown not to increase the risk of recurrent instability [22]. A dynamic brace can be applied for comfort and for reducing valgus stress on the elbow, with a stepwise increase to full extension. The program should include strengthening of the wrist flexor–extensor [16] and flexor–pronator muscle groups together with retraining of throwing mechanics in the case of overhead athletes. Optimizing the technique is most important in patients with VEOS without an MCL tear.

The risk of recurrent symptoms is extremely high if the underlying cause is not corrected, even when conservative treatment is successful initially. Rettig et al. noted that only 42% of baseball pitchers returned to their pre-injury sports level after an average time of 24.5 weeks [32]. Chronicity of the injury and patient age did not seem to influence the prognosis of conservative treatment in their study.

Indications for surgical MCL reconstruction require a confirmatory history, physical examination, and imaging studies. High-demand patients with a diagnosis of MCL insufficiency for whom nonoperative treatment has failed are candidates for surgical reconstruction [21].

Some authors advocate elbow arthroscopy before formal MCL repair for two reasons: (a) arthroscopy may play a role in the diagnosis of valgus instability (Fig. 8)—a gap of more than 1 mm at the medial ulnohumeral joint line is indicative of valgus instability [12]; and (b) arthroscopy may be able to address potential concomitant lesions such as posteromedial impingement and loose body removal.

Early surgery may be indicated in the case of acute valgus instability, confirmed on imaging studies, in a high-demand patient. Patients presenting with a partial tear and the absence of bony abnormalities, yet who are resistant to conservative treatment, present a decision-making challenge.

Direct repair of the ruptured MCL is only indicated in cases of acute avulsion from either the humeral origin or the coronoid insertion (Fig. 9; [6, 7, 19]). The direct repair may be reinforced with a tendon graft via a hybrid technique. Most MCL reconstruction techniques involve a free tendon graft, typically placed in bone tunnels through the humerus and ulna (Fig. 10). Graft options that have been previously described include autologous and allograft palmaris longus tendon, plantaris tendon, hamstring tendons, and strips of Achilles or triceps tendon. Jobe and colleagues [19, 37] described the original MCL reconstruction technique consisting of (a) tendinous transection and reflection of the flexor–pronator mass, (b) submuscular transposition of the ulnar nerve, and (c) creation of humeral tunnels that penetrate the posterior humeral cortex. Although this technique was successful, it was technically demanding and associated with a high complication rate, most often related to ulnar nerve problems [19, 31]. Since then, the technique has been modified. A muscle-splitting approach has been developed to avoid detachment of the flexor–pronator mass and tunnels are drilled anteriorly on the humeral epicondyle to avoid the risk of ulnar nerve injury. The number of bone tunnels has also been reduced to facilitate graft tensioning and avoid the risk of iatrogenic fracture [1, 2, 33].

Several methods of graft fixation have been described, including transosseous figure-of-eight reconstruction, docking technique, hybrid interference screw fixation, and EndoButton fixation [2, 4, 33].

Recent studies have demonstrated a 93% success rate [2, 8, 9, 29, 38] with current ligament reconstruction techniques. A high rate of return to play (RTP) in elite athletes and a high rate of return to a pre-injury or higher level have been reported [4, 20, 33]. Azar et al. [4] noted an 81% return to pre-injury level, Rohrbough et al. [33] found a 92% RTP, and Erickson et al. [10] found that 83% of patients were able to return to the same level.