Posterolateral Rotatory Instability of the Elbow

Publicado em: 2 de fevereiro de 2021 por Naeon
Publicações Científicas

Jose Carlos Garcia Jr.*, PhD

Felipe Machado do Amaral*, MD

Matheus Ribeiro Barcelos*, MD

*NAEON-São Paulo-Brazil

Correspondence josecarlos@especialistadoombro.com.br

Introduction

O’Driscoll et al., in 1991, described posterolateral rotatory instability (PLRI) of the elbow as a condition resulting from an injury to the lateral ulnar collateral ligament (LUCL)¹. This lesion leads to posterolateral subluxation and/or dislocation of the radius over the capitellum without disruption of the proximal radioulnar joint and is most often caused by a traumatic event resulting in significant valgus stress combined with axial load and forearm supination.

Iatrogenic causes of PLRI include multiple corticosteroid injections and aggressive debridement for the treatment of lateral epicondylitis. Ligamentous attenuation resulting from chronic cubitus varus is also considered a potential cause.

Although O’Driscoll et al. initially described an injury to the LUCL as the primary cause of PLRI, this theory has become controversial in the literature. Some authors have shown that additional injuries to the remaining lateral soft-tissue structures of the are also required in order for a patient to develop PLRI^2,3.

Pathoanatomy of Posterolateral Rotatory Instability

The osseous structures of the elbow stabilize the joint at the extremes of flexion (>120°) and extension (0° to 20°), whereas the lateral and medial ligamentous complexes are the primary stabilizers throughout the remainder of motion.

The LUCL is a thickening of the capsule that extends from the lateral epicondyle to the tubercle on the supinator crest. The LUCL is a restraint to varus stress and stabilizes the radial head against posterior subluxation or dislocation.

The concept of the LUCL as the only soft-tissue stabilizer of the radiocapitellar joint is controversial. Multiple anatomical studies have demonstrated that, in order to create radiocapitellar instability, additional lateral elbow structures must also be injured, including the radial collateral ligament, part of the annular ligament, and/or the common extensor mechanism^2,3.

Clinical Presentation

Patients often present with lateral elbow pain, especially following activities in which the elbow is placed into extension and supination. Lateral elbow pain may be accompanied by mechanical symptoms such as clicking, locking, or snapping, which are most prominent at 40° of flexion as the arm is extending¹.

Stability of the lateral collateral ligaments (the radial collateral ligament and LUCL) and medial collateral ligaments (MCL) should be assessed with varus and valgus stress tests at 30° of flexion to unlock the olecranon from its fossa. A valgus stress test should be performed with the forearm in both full supination and full pronation. When the forearm is in full pronation, the interosseous membrane is not tense, which allows for proximal migration of the radius and thereby enhances the stability of the radiocapitellar joint. Thus, one can test the MCL with no risk of a false-positive valgus stress test. However, when the forearm is in supination, bone stability of the radiocapitellar joint is decreased and use of the LUCL is increased. If the patient has PLRI during the exam, this finding may be a false-positive result.

The pivot-shift test, described this by O’Driscoll et al., is used to confirm PLRI¹. This test is performed with the patient supine on the examination table with the arm overhead, the shoulder in full external rotation to stabilize the shoulder joint, and the forearm in full supination. The maneuver starts with the elbow extended and supinated; in this position, the radial head will be subluxated. As the examiner brings the arm from extension to flexion, valgus stress and axial compression are applied to the elbow and the forearm is allowed to become less supinated. This allows the forearm to pivot around the MCL and results in reduction of the elbow joint as the triceps becomes taught at around 40° flexion, often causing an audible or palpable click. In the awake patient, it is unusual to be able to detect a positive pivot shift because of guarding by the patient. Therefore, apprehension during the pivot-shift maneuver is often considered to be a positive result even without frank instability.

The chair-up test can also be used to test for PLRI. For this test, the patient pushes up from a chair with the hands on the armrests. If apprehension or dislocation occurs, the test is considered to be positive for PLRI.

Imaging

The diagnosis of PLRI is often based on clinical findings, but radiographs of the elbow should still be made to assess for any evidence of fracture, subluxation, and/or dislocation. Advanced imaging such as magnetic resonance imaging (MRI) is controversial as a lesion of the LUCL is not always identified on such studies.

Nonoperative Treatment

Nonoperative treatment is often unsuccessful in cases of chronic PLRI. For mildly symptomatic or asymptomatic patients, the avoidance of provocative activities may be attempted. Physical therapy, analgesics, and anti-inflammatory medications can also be used.

Operative Treatment

The majority of patients with chronic PLRI require operative treatment. Patients with acute lesions who present with good-quality ligamentous tissue may be treated with LUCL repair. Patients with chronic lesions usually do not have adequate tissue for direct repair and therefore require an open ligamentous reconstruction with use of either autograft or allograft. The two main reconstruction techniques are the overlay technique and the docking technique.

Overlay Technique

The overlay technique is performed through the Kocher approach with use of three transosseous tunnels at the humerus and two at the ulna and an overlay autologous graft. Our preferred graft is the ipsilateral palmaris longus tendon.

A small burr is used to create 2 holes just posterior to the supinator crest in the ulna. A snap is placed on the sutures to identify the point where even tension is maintained throughout flexion and extension of the elbow. This isometric point is then marked for later drilling of the docking humeral tunnel. This location is typically slightly posterior to the tip of the lateral epicondyle.

The tendon is then passed through the ulnar tunnels. The docking hole is then drilled with a 4.5-mm drill, just posterior and proximal to the isometric point on the lateral epicondyle. A 3.5-mm drill is then used to make two proximal tunnels in order to create a Y-shaped bone tunnel configuration in the lateral epicondyle. The tendon is then passed through the distal and proximal tunnels and is sutured to its other tip where they cross at the joint. The new ligament is also sutured into the capsule with use of non-absorbable number-2 sutures.

Docking Technique

The docking technique is performed through the Kocher approach with use of an autologous palmaris tendon graft, which does not need to be as long as the graft used for the overlay technique. After the avulsed or attenuated ligament is identified, a number-1 non-absorbable braided suture is placed through one end of the tendon with use of either a Krackow or running stitch.

The capsule and the common extensor tendon are then incised longitudinally, immediately anterior to the posterior border of the extensor tendon, to expose the supinator crest and the lateral epicondyle. Two drill holes are made in the ulna with use of a 4-mm burr, with a 1 to 2-cm bridge between the holes to prevent fracture. The first hole is near the supinator crest, and the second is approximately 2 cm proximal, near the base of the annular ligament. The 4-mm burr is used to drill a hole at the isometric point on the humerus to a depth of approximately 15 mm.

A drill is then used to drill 2 small 15-mm exit holes slightly superoanterior and superoposterior to the isometric point. Non-absorbable sutures are then placed in the anterior and posterior capsules to later dock with the graft for capsular plication if deemed necessary. The graft is placed through the ulnar tunnel. The elbow is flexed to 30° to 40°. A suture passer is then used to pull the graft and the capsular sutures into the anterior humeral tunnel. The sutures are tied over the osseous bridge with the arm in 40° of flexion and full pronation.

Authors’ Preferred Technique

We prefer to use small-diameter interference screws with a double palmaris longus tendon graft for this procedure. Such screws are typically 15 mm in length and 4.75, 5.5, or 6.25 mm in diameter, depending on the diameter of the graft[AH1] . One screw is inserted at the supinator crest, and another is inserted at the isometric point (Figs. 1 to 5). This kind of fixation is easy and fast and will allow for suitable strength and resistance for cycling load, similar to bone tunnels and superior to anchors [AH1] . If the palmaris longus tendon is absent, regardless of the technique that is chosen, then the gracilis or semitendinosus tendon can be used. Allografts also can be used.

Clinical Results

Better results can be achieved with operative treatment than with a conservative approach. Sanchez-Sotelo et al.⁴ assessed 44 patients (including 12 who underwent repair and 32 who underwent ligamentous reconstruction) after an average duration of follow-up of 6 of years. Four patients in the repair group had some residual instability, and three of them required revision. Overall, the results in the reconstruction group were better than those in the repair group. Savoie et al.⁵, in a study of 54 patients who underwent arthroscopic or open repair of the LUCL for the treatment of PLRI, reported no statistical difference between the groups after an average duration of follow-up of 41 months. It should be noted that the arthroscopic approach requires a high level of skill.

For patients presenting with acute injuries and appropriate-quality tissues, a direct repair can achieve good results. However, for the majority of patients who present with chronic PLRI, reconstruction with use of autograft or allograft is required to prevent recurrent instability.

Rehabilitation and Return to Sport

Rehabilitation protocols vary among authors. Bracing with a limited range of motion to 30° of elbow extension is one of the main postoperative approaches. The duration of immobilization ranges from 1 day to 6 weeks postoperatively, depending on the technique and fixation method used.

We prefer to use a brace in a position of pronation and 30° of extension for a week and then to increase passive motion with use of an articulated brace for 2 more weeks. In the third week, active movement with use of the brace and assisted exercises with the arm in the overhead position are begun. Passive supination is also allowed with care at this time. Active forced exercises are started 6 weeks after surgery. At 3 months, regular sports activities with low load are allowed in order to restore proprioception. Exercise load is progressively increased during the following 3 months. A return to regular sports activities is allowed at 6 months.

Although rehabilitation protocols typically are based on specific time frames following surgery, the decision to return to sport is ultimately based on a critical assessment of when acceptable function has been restored and the risk of reinjury is believed to be acceptably low.

Conclusion

PLRI of the elbow is due to a ligamentous lesion that is commonly the result of a traumatic event.
Lateral elbow pain is the most common clinical presentation, making diagnosis challenging. Some patients also will present with mechanical symptoms such as locking, catching, or clicking.
The diagnosis is usually based on clinical findings. Provocative tests tend to demonstrate apprehension rather than frank subluxation or dislocation because of pain and guarding by the patient.
Conservative measures are often unsuccessful for the treatment of chronic PLRI. In these cases, operative treatment with either LUCL repair or reconstruction is suggested as the best treatment option.
Good and excellent outcomes have been achieved with surgical treatment, mainly in patients with isolated injuries without arthritic joint damage.
Repair should only be performed when the ligamentous tissue is is of sufficient quality ; otherwise, a reconstruction with autograft or allograft is preferred.

References

O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 1991 Mar;73(3):440-6.
Dunning CE, Zarzour ZD, Patterson SD, Johnson JA, King GJ J. Ligamentous stabilizers against posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 2001 Dec; 83 A(12):1823-8.
Dunning CE, Zarzour ZD, Patterson SD, Johnson JA, King GJ Muscle forces and pronation stabilize the lateral ligament deficient elbow. Clin Orthop Relat Res. 2001 Jul; (388):118-24.
Sanchez-Sotelo J, Morrey BF, O’Driscoll SW. Ligamentous repair and reconstruction for posterolateral rotatory instability of the elbow. J Bone Joint Surg Br. 2005 Jan;87(1):54-61.
Savoie FH 3rd, O’Brien MJ, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Clin Sports Med. 2010 Oct;29(4):611-8.

[AH1]This part of the sentence (particularly the phrase “so as”) is unclear to me. Do you mean “This kind of fixation is easy and fast and provides suitable strength and resistance to cyclical load (similar to that provided by bone tunnels and superior to that provided by anchors [AH1])”, or something similar? Please advise.