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    Posterior Shoulder Instability with Labral Tear

    A 19-year-old college student who plays basketball and baseball presents with a history of left shoulder pain, restricted range of motion and occasional numbness. Conservative treatment provides only temporary relief. When he’s diagnosed with posterior glenohumeral instability, shoulder arthroscopy is recommended.

    Author

    Fotios Paul Tjoumakaris, MD

    Disclosures

    The author has disclosures relevant to this article.

    Background

    Posterior shoulder instability is much less frequent than anterior glenohumeral instability, comprising approximately 5% of all shoulder instability cases [1]. Most patients present with recurrent posterior subluxation, or RPS. Less commonly, trauma may be the cause and may require emergent, closed reduction in the emergency department or operating room.

    For patients with traumatic injuries, assessing the damage to the joint after closed reduction is paramount in achieving an optimal outcome. For patients with RPS, the signs and symptoms of their pathology may be subtler, and diagnosis may often be delayed or missed [2]. A careful history, detailed physical examination, and utilization of advanced imaging often lead to an accurate diagnosis in these instances.

    Arthroscopic repair can restore normal glenohumeral translation, improve pain, and optimally restore performance in patients who are high-level recreational or competitive athletes. The following case illustrates a classic presentation of a patient with RPS who underwent successful treatment via arthroscopic repair.

    Case Presentation

    A 19-year-old college student presented with a 1-year history of pain in his left shoulder. His initial injury was from playing basketball: He fell after a blocked jump shot and landed on an outstretched arm. At the time of impact, he had slight pain in his shoulder; however, he was able to finish his entire season of play with intermittent pain.

    After his season concluded, he rested his shoulder and noticed mild improvement in his symptoms. When he returned to sports during the spring intramural baseball season, he noticed soreness in his shoulder during and after pitching. He reported decreased velocity, anterior shoulder pain, and restriction in range of motion that would last several days. On occasion, he would feel that his arm would transiently go numb.

    He stopped playing sports and now reports intermittent pain with any attempt at working out. The symptoms have progressed to pain with any loading of the shoulder, inability to perform push-ups, and mild nighttime symptoms. Anti-inflammatory drugs and rest only provide temporary relief of his symptoms.

    Physical Examination

    • Inspection of both shoulders reveals no asymmetry or atrophy
    • Palpation demonstrates mild anterior capsular tenderness
    • Range of motion both supine and elevated is symmetric and full
    • Strength testing of the rotator cuff musculature is 5/5 in all planes
    • Provocative testing demonstrates:
      • Positive Neer impingement sign
      • Positive O’Briens active compression test
      • Positive Kim test
      • Pain with posterior load and shift test with 1+ laxity
      • Negative sulcus sign

    Imaging

    • Plain radiographs are reviewed and found to be normal (AP/Y view/axillary)
    • MRI arthrography shows evidence of a posterior labral tear and partial undersurface rotator cuff pathology (Figure 1)

    Figure 1. Axial T2 MRI scan of a patient with a posterior labral tear. A small paralabral cyst is identified at the site of the tear.

    Differential Diagnosis

    • Superior labral anterior posterior tear (SLAP)
    • Rotator cuff tear
    • Humeral avulsion of the glenohumeral ligament (HAGL)
    • Multidirectional instability (MDI)

    Diagnosis

    • Recurrent posterior subluxation, posterior shoulder instability, and labral tear without significant capsular laxity

    Treatment

    The patient underwent left shoulder arthroscopy with posterior labral repair and rotator cuff debridement.

      • The patient was placed in the lateral decubitus position with an interscalene nerve block and general anesthesia.
      • Posterior and anterior arthroscopic working portals were established and 7-mm cannulas were placed for easy access of arthroscopic instrumentation.
      • A detailed arthroscopic examination was performed and the labral tear is identified (Figure 2).

    Figure 2. The labral tear is identified with the arthroscope in the anterior portal and viewing the posterior shoulder. The tear is displaced into the glenohumeral joint.

      • The undersurface partial rotator cuff tear is debrided with a full radius shaver device.
      • The labrum was then elevated off of the posterior margin of the glenoid and the bone edge was slightly debrided with an arthroscopic shaver or burr.
      • Once the labrum was adequately mobilized, 2.9-mm anchors were placed along the posterior glenoid face for arthroscopic fixation (Figure 3).

    Figure 3. Anchors are placed along the posterior glenoid articular margin. In this instance, an accessory posterior and lateral portal was established to assist with anchor placement.

      • The posterior suture limb of the anchor was passed through the labrum and capsule complex with a suture hook device (using standard shuttling techniques) to restore the labrum to the glenoid articular margin (Figure 4).

    Figure 4. A suture shuttle can be used to shuttle the suture limb around the posterior labrum and capsule.

      • Each suture anchor was then tied using arthroscopic knot tying techniques.
      • This sequence was repeated until the labrum was completely repaired (Figure 5). Anchors are typically spaced 3-mm apart to allow for adequate bone bridge between fixation points.

    Figure 5. Anchors are placed apart by 3mm and sequentially restore the labrum and capsule to the glenoid articular margin. In this case, a combination of both suture tying (blue suture) and knotless fixation (white suture) is demonstrated

      • The posterior portal can be closed to prevent postoperative capsular laxity in instances of significant posterior subluxation (Figure 6).

    Figure 6. The final repair is completed with closure of the posterior capsule.

    Postoperative Course

    • The patient was placed in a well-padded postoperative sling and abduction pillow.
    • Early passive range of motion of the shoulder was allowed after 3 days and continued for up to 4 weeks.
    • At 4 weeks, active assisted range of motion was begun, with full active motion begun at 8 weeks.
    • When range of motion was nearly 80% of the contralateral shoulder, the patient was started on a light-strengthening program, which was then advanced based on patient tolerance and ability.
    • Most patients are allowed to return to competitive sport between 4 and 6 months. Patients who are overhead throwing athletes begin a structured throwing program during this time and are advanced with the prospect of full throwing by 9 to 12 months after surgery. Overhead athletes are monitored with pitch counts and rest days to maintain shoulder health and are placed on a routine posterior capsular stretching program to prevent future injury.

    Final Follow-Up

    • The patient presented for a 1-year follow-up with full range of motion.
    • He reported no pain in his shoulder and full participation in all athletics, including overhead throwing without difficulty.
    • He was discharged from care with a posterior capsular stretching program.

    Discussion

    Posterior shoulder instability has become an increasingly recognized source of shoulder pain and dysfunction in recent years. Patients often present with more vague symptoms than those who have anterior dislocation and instability.

    Rarely is the typical chief complaint: “my shoulder dislocates or subluxates.” Rather, patients often present with pain, fatigue, and soreness with activities that place a posteriorly directed load across the shoulder in a flexed or adducted position.

    Offensive linemen, overhead athletes, and those who lift weights are particularly susceptible to injuring their shoulder in this capacity, and a high index of suspicion is warranted when treating this patient population. High-resolution MRI arthrography combined with increased awareness has led to more accurate diagnosis.

    While physical therapy can be an initial treatment for many patients, it is not typically successful for the athlete who wishes to resume competitive sport. Recent studies have shown excellent results of arthroscopic repair in high-demand, competitive athletes, with low rates of recurrence and low morbidity [3,4].

    Arthroscopy has become the gold standard to treat the majority of patients with posterior instability and subluxation, except in cases of glenoid or humeral osseous deficiency or abnormal retroversion.

    Author Information

    Fotios Paul Tjoumakaris, MD

    Sports Medicine Section Editor, Rothman Institute Grand Rounds

    Fotios Paul Tjoumakaris, MD

    References

    1. Robinson CM, Aderinto J. Recurrent posterior shoulder instability. J Bone Joint Surg Am 2005;87;883-892.
    2. Bradley JP, Tejwani SG. Arthroscopic management of posterior shoulder instability. Orthop Clin North Am 2011;41(3): 339-356.
    3. Kim SH, Ha KI, Park JH, et al. Arthroscopic posterior labral repair and capsular shift for traumatic unidirectional recurrent posterior subluxation of the shoulder. J Bone Joint Surg Am 2003;85-A: 1479-1487.
    4. Bradley JP, Baker CL 3rd, Kline AJ, et al. Arthroscopic capsulolabral reconstruction for posterior instability of the shoulder: a prospective study of 100 shoulders. Am J Sports Med 2006;34(7): 1061-1071.