Posterior Shoulder Instability









Introduction



Demetris Delos, MD
Travis G. Maak, MD
Russell F. Warren, MD

Epidemiology




  • •

    Posterior shoulder instability is less frequently encountered than anterior instability, accounting for only 2% to 10% of all instability cases.


  • •

    Treatment of this condition can be challenging, and a high index of suspicion is often required for an accurate diagnosis.


  • •

    The literature is primarily limited to small case series and retrospective studies; however, from this, an epidemiological pattern emerges.



Age




  • •

    Most series describing outcomes after surgical treatment for symptomatic posterior instability report a median patient age between 20 and 30 years.


  • •

    In a recent report that included the largest series of patients with posterior glenohumeral dislocation to date, the median age at time of diagnosis of posterior dislocation was 43 years.



Sex




  • •

    Males constitute the majority of patients in most operative series of patients with posterior instability (51% to 100%).



Sport




  • •

    Sports commonly associated with posterior shoulder instability include



    • •

      American football


    • •

      Overhead weight lifting


    • •

      Rowing


    • •

      Racket sports


    • •

      Swimming


    • •

      Golf




Position




  • •

    Lineman in American football


  • •

    Bench press, overhead press in weight lifting



Pathophysiology


Intrinsic Factors


Intrinsic factors that may contribute to posterior glenohumeral joint (GHJ) instability may be classified as biological or anatomical in nature.



  • •

    Biological



    • •

      Collagen disorders such as Ehlers-Danlos syndrome


    • •

      Generalized ligamentous laxity



  • •

    Anatomical



    • •

      Glenohumeral bony abnormalities:



      • •

        Glenoid hypoplasia/dysplasia


      • •

        Glenoid retroversion


      • •

        Humeral retroversion




  • •

    Activities such as the following place the shoulder in the provocative position



    • •

      Heavy bench pressing


    • •

      Blocking during American football (such as demonstrated by football linemen)


    • •

      The backswing in golf



  • •

    Provocative positions include



    • •

      Flexion


    • •

      Adduction


    • •

      Internal rotation (IR)



  • •

    Provocative positions increase the risk of posterior instability (both microinstability and frank dislocation).


  • •

    These repetitive activities can lead to microtrauma and attenuation of the posterior inferior glenohumeral ligament (PIGHL) and posterior capsulolabral structures over time.


  • •

    Pathological attenuation of the posterior structures of the shoulder that can manifest in clinically significant instability can be caused by



    • •

      Overhead weight lifting


    • •

      Rowing


    • •

      Racket sports


    • •

      Swimming


In most cases subluxation events may be painless because of capsular redundancy, which may initiate labral breakdown and injury with subsequent pain. However, acute traumatic dislocation events typically produce frank labral tears.


Classic Pathological Findings




  • •

    Pain and/or sense of glenohumeral instability with the shoulder placed in the provocative position (flexion, adduction, IR)


  • •

    Attenuation of the posterior inferior glenohumeral ligament and posterior capsulolabral structures


  • •

    For frank posterior glenohumeral dislocations, patients often demonstrate a prominent coracoid anteriorly and humeral head posteriorly on examination.


  • •

    The shoulder is typically maintained in the adducted, internally rotated position.


  • •

    This is why posterior dislocations may be missed in that the patient is most comfortable in a traditional sling.


  • •

    Shoulder external rotation (ER) and abduction are limited because of mechanical block.



Clinical Presentation


History




  • •

    The patient history is a crucial component of diagnosis and management in posterior shoulder instability.


  • •

    Complaints of generalized posterior shoulder discomfort, pain, and weakness are commonly associated with this pathology. Nevertheless, patients may also complain of anterior shoulder pain during shoulder adduction.


  • •

    Difficulty with or reduced performance during athletic activities may also be described, including poor performance during bench press or push-ups.


  • •

    Although these complaints are less common, the patient may also report mechanical symptoms, including



    • •

      Catching


    • •

      Clicking


    • •

      Popping



  • •

    Background regarding the inciting event, including



    • •

      History of trauma


    • •

      Position of the shoulder and arm



  • •

    Specifics regarding associated external forces should also be elicited.


  • •

    Underlying laxity should be evaluated in the absence of trauma, including



    • •

      Patient history of shoulder or other joint instability


    • •

      Family history of instability or other diagnosed collagen disorders



  • •

    Any history of prior surgical procedures, including anterior stabilizations, especially those performed on the injured shoulder, should be ascertained and reviewed.


  • •

    Although it is frequently difficult to discriminate between purely voluntary and traumatic instability, any history regarding previous instability including chronic voluntary dislocation may be useful in this regard.



Physical Examination




  • •

    Aids to supplement the information acquired during the patient history may be focused based on this information.


  • •

    In addition to a detailed shoulder examination, previous history suspicious for laxity should prompt a general examination for hypermobility. Use of the Beighton criteria for hyperlaxity is most helpful in this regard.


  • •

    Physical exam tests include



    • •

      Approximating the thumb to the volar surface of the forearm


    • •

      Hyperextension of the second metacarpophalangeal (MCP) greater than 90°


    • •

      Hyperextension of the elbow


    • •

      Recurvatum/hyperextension of the knee


    • •

      The ability to lay the palm of the hand flat on the floor with the knees straight



  • •

    If at least three of these five test results are positive, then laxity is likely present.


  • •

    The sulcus test is an important test that can be used to assess for inferior glenohumeral laxity/instability of the shoulder.


  • •

    To perform this test



    • •

      Apply downward traction to the patient’s elbow or wrist.


    • •

      Observe the shoulder for dimple (sulcus) lateral or inferior to the acromion.



  • •

    If the size of the sulcus does not reduce with ER, a defect in the rotator interval may be present.


  • •

    Side-to-side comparisons should always be performed for accurate diagnosis.


  • •

    A thorough shoulder examination should begin with observation.



    • •

      Contour should first be inspected.


    • •

      Any prior incisions should be thoroughly reviewed.



  • •

    Muscle atrophy is not typically present except in chronic cases of rotator cuff tear or nerve palsy.


  • •

    Tenderness to palpation may be elicited along the posterior GHJ line.


  • •

    Evaluate



    • •

      Range of motion (ROM; both active and passive)


    • •

      Motor strength



  • •

    Compare with the contralateral side.


  • •

    Useful provocative tests for suspected posterior instability include



    • •

      The posterior stress test


    • •

      The jerk test


    • •

      The load and shift


    • •

      The modified load and shift


    • •

      The Kim test ( Figure 2-1 )




      FIGURE 2-1


      The load and shift test should be performed with the patient in a supine position to stabilize the scapula. The arm should then be placed in the plane of the scapula with an axial load placed on the elbow while the humerus is shifted on the glenoid as demonstrated here.



  • •

    The current authors suggest performing these provocative tests with the patient in the supine position to stabilize the scapula and isolate the GHJ.


  • •

    The posterior stress test is performed with the examiner applying a posterior force to the humerus with the arm flexed and internally rotated in an attempt to subluxate or dislocate the joint.


  • •

    The jerk test is performed with the patient seated or standing; the shoulder is flexed to 90° and internally rotated. With the elbow flexed the examiner applies a load posteriorly—the test result is positive if a sudden “jerk” occurs when the subluxated humeral head relocates into the glenoid fossa.


  • •

    The load and shift (patient seated) and modified load and shift (patient supine) are also useful to gauge the degree of posterior humeral head translation across the glenoid.


  • •

    Finally, the Kim test was recently described and has been shown, in conjunction with the jerk test, to have sensitivity for detecting posterior instability as high as 97%. To perform the Kim test, the examiner should abduct the affected arm 90°, forward flex 45°, and then apply a posteroinferior load to the humerus. The exam is positive if pain is elicited with this maneuver.

Any prior history of cervical pathology or neuropathic symptoms should prompt a more focused examination of dermatomal sensation and motor strength.


Imaging




  • •

    Plain radiographs should be obtained in all patients, such as



    • •

      An anteroposterior view of the GHJ (Grashey view)


    • •

      Scapular-Y view


    • •

      Axillary view



  • •

    Specific views including the West Point or Stryker-Notch views may be included if clinical concern exists for a glenoid rim or a reverse Hill-Sachs lesions, respectively.


  • •

    These images should be critically evaluated for



    • •

      Evidence of posterior glenoid rim fractures (reverse bony Bankart lesions)


    • •

      Anterior humeral head impaction fractures (reverse Hill-Sachs lesions)


    • •

      Bennett lesions


    • •

      Early osteoarthrosis


    • •

      Increased humeral or glenoid retroversion


    • •

      Dynamic radiographs may also be indicated in patients with voluntary instability.



  • •

    A computed tomography (CT) scan may be used to more clearly delineate the osseous morphology and identify previously unrecognized humeral and glenoid fractures ( Figure 2-2 ).




    FIGURE 2-2


    Axial CT image demonstrating a reverse bony Bankart injury. Care should be placed on complete evaluation of these injuries to ensure adequate preservation of bone stock before surgical stabilization.


  • •

    Calculation of the glenoid and humeral version and the degree of glenoid bone loss can be performed on axial cross-sectional images at the level of the mid-glenoid.

Some authors have also used CT arthrography to evaluate the posterior and superior labrum and the capsule. However, the intracapsular injection that is required to perform CT arthrography may artificially distend the glenohumeral capsule and hinder identification of a patulous capsule. Although the current authors routinely used CT to evaluate the glenohumeral osseous morphology, magnetic resonance imaging (MRI) with cartilage sensitive sequences is preferred for evaluation of soft tissue structures.

  • •

    MRI and MR arthrography (MRA) is used to evaluate the associated soft tissues, including



    • •

      Labrum and capsule


    • •

      Rotator cuff


    • •

      Biceps complex


    • •

      Rotator interval



  • •

    Care should be placed on complete evaluation of the images, including humeral-based injuries such as a posterior humeral avulsion of the glenohumeral ligament (PHAGL), especially when no glenoid-based pathology is identified ( Figure 2-3 ).




    FIGURE 2-3


    Axial MRI images demonstrating a posterior humeral avulsion of the glenohumeral ligament. A, Periosteum and subchondral bone can be seen attached to the capsule and ( B ) the donor defect in the humerus can be visualized.


  • •

    The presence and extent of posterior labral injury should also be identified, including extension of injury to the anterior labrum. In this regard, Kim et al. have suggested a classification scheme for posterior labral tears. Preoperative identification of all associated pathology will facilitate planning and optimize postoperative outcomes.



Differential Diagnosis




  • •

    As previously described, posterior glenohumeral instability presents with



    • •

      Complaints of posterior shoulder pain


    • •

      Sensation of instability with the arm in the following position



      • •

        Forward flexed


      • •

        Adducted


      • •

        Internally rotated




  • •

    Pain in this position may mimic pathology with the acromioclavicular joint or superior labrum, including a SLAP lesion.


  • •

    Nevertheless, this complete constellation of symptoms may not exist, but rather, the patient may demonstrate only a subset of signs and symptoms.


  • •

    In this vein, the differential diagnosis and fundamental differences among these diagnoses should be considered.

The following pathologies must be included in the differential diagnosis of posterior shoulder pain in addition to traumatic or atraumatic posterior glenohumeral instability:

  • •

    Posterior osteoarthritis


  • •

    Tear of the superior labrum from anterior to posterior (SLAP)


  • •

    Subluxating tendon of the long head of the biceps


  • •

    Acromioclavicular pathology


  • •

    Rotator cuff tear


  • •

    Proximal humerus fracture


  • •

    Scapular fracture


  • •

    Cervical radiculopathy


  • •

    Oncological lesions

The vast majority of these etiologies may be eliminated with a

  • •

    Careful history


  • •

    Physical examination


  • •

    Plain radiographic imaging

Nevertheless, more subtle differentials exist such as posterior instability with concomitant radiculopathy. In these circumstances, both diagnoses should be completely evaluated, including

  • •

    Imaging


  • •

    Electromyography


  • •

    Nerve conduction studies, if applicable, such that management and patient outcome can be optimized

Additionally, differentiating between multidirectional instability (MDI) and atraumatic unidirectional instability with mild generalized laxity can be difficult. In this circumstance, the data obtained during the aforementioned history and physical examination can significantly aid the surgical or nonsurgical options, which are detailed in the following.

  • •

    Adding to the diagnostic difficulty of posterior instability is the fact that the patient may present with anterior shoulder pain, particularly with shoulder adduction and have no sensation of posterior pain.


  • •

    Finally, concomitant or previously unappreciated pathology may be identified at the time of the arthroscopic or open surgery and may confirm or alter the preoperative plan. For this reason, the current authors perform a diagnostic arthroscopy before any posterior stabilization procedure to augment the preoperative plan and ensure that all contributing pathology is appropriately addressed.



Treatment




  • •

    In general, an initial course of nonoperative management including the following should be attempted before surgical intervention.



    • •

      Physical therapy


    • •

      Rehabilitation for posterior glenohumeral instability


Strengthening dynamic muscular stabilizers allow patients to compensate for damaged or deficient static stabilizers, resulting in improved stability and pain control in a majority of those with posterior subluxation.

  • •

    This approach is successful in 65% to 80% of atraumatic patients with MDI.


  • •

    However, prior data have demonstrated that this nonoperative approach is less successful in patients with a history of trauma, with 70% to 89% success rate in atraumatic patients compared with 16% success in patients with a traumatic history.


  • •

    Patients with a specific identified injury or posterior labral tear can also have documented recurrent instability following nonoperative management.



Nonoperative Management


Nonoperative management represents the mainstay for primary treatment of posterior shoulder instability. Physical therapy, including



  • •

    Improving scapular stability


  • •

    Strengthening the dynamic stabilizers surrounding the GHJ will facilitate postoperative recovery and may obviate the need for surgical management in some cases. Physical therapy and rehabilitation has been particularly effective in patients with atraumatic posterior instability and MDI.


  • •

    Prior studies have documented success rates between 65% and 80% in patients with MDI and up to 89% in those with atraumatic, unidirectional posterior instability.


  • •

    Nonoperative management of patients with traumatic, unidirectional posterior instability, however, has demonstrated success in only 16% of cases.


  • •

    High recurrence rates following nonoperative management have also been documented in patients with a specific identified injury or radiographic evidence of a posterior labral tear.

These data are in accordance with the current authors’ clinical experience; thus, the suggested nonoperative treatment algorithm is similar. Nonoperative treatment is suggested as the first management modality in patients with an atraumatic instability etiology or with clinical evidence of MDI. Athletes competing in contact sports, however, typically exist in the traumatic, unidirectional posterior instability category; thus, early operative management is often recommended for this population.


Surgical Indications


The principal indication for open or arthroscopic surgical management of posterior glenohumeral instability is pain or perceived instability that is refractory to nonoperative measures.



  • •

    Although the main etiology of both symptoms is underlying glenohumeral instability, pain represents the most common presenting symptom.


  • •

    Optimal surgical outcomes have been associated with patients who have posttraumatic, unidirectional recurrent instability.


  • •

    Nevertheless, these patients represent a subset of patients with posterior glenohumeral instability, which also includes MDI, voluntary instability, and atraumatic posterior instability, among others.


  • •

    Surgical management may include either arthroscopic or open approaches, and both approaches may be combined in some situations depending on the identified pathology.


  • •

    Open surgical stabilization has been previously recognized as the gold standard for recurrent posterior instability with excellent outcomes ; however, recent advancements in arthroscopic techniques and instrumentation have resulted in many surgeons using this approach as the primary treatment method.


  • •

    It is the current authors’ opinion that at this time posterior instability can be more effectively managed with an arthroscopic approach.


  • •

    Open surgical stabilization, on the other hand, may be indicated in cases including



    • •

      Contact athletes


    • •

      Revision stabilization


    • •

      Significant generalized laxity or poor tissue quality


    • •

      Excessive capsular insufficiency


    • •

      Bony deficiency


    • •

      Glenohumeral retroversion



  • •

    Open posterior stabilization has many advantages over an arthroscopic approach, including a complete visualization of the posterior capsule, which provides the opportunity for the treating surgeon to address labral pathology as well as perform a full posterior capsular shift.


  • •

    In addition, bone loss that is identified at the time of surgery can be addressed with a variety of osseous procedures in combination with the posterior capsular shift.


  • •

    Pollack et al. suggested the capsular shift as the workhorse procedure for addressing posterior glenohumeral instability, with good to excellent results in up to 80% to 90% of patients.


  • •

    These authors also noted that concomitant procedures should be used when necessary to address all apparent pathology.


  • •

    They suggested using bone block augmentation only in the setting of revision surgery with bony deficiency or glenoid hypoplasia.


  • •

    This suggestion is based on the higher incidence of recurrent instability following posterior stabilization in patients with



    • •

      Large posterior bony Bankart lesions


    • •

      Glenoid hypoplasia


    • •

      Significant humeral or glenoid retroversion



  • •

    Increased failure because of recurrent instability has also been identified in contact athletes and patients with significant capsular laxity or engaging reverse Hill-Sachs lesions.


  • •

    Notably, although open surgical stabilization has been suggested in these patient populations, recent data have demonstrated improved outcomes following arthroscopic posterior stabilization in contact athletes.


  • •

    Contraindications to surgery include voluntary instability with a psychogenic etiology and poor patient compliance.

Following appropriate patient indication for surgical stabilization, the surgeon must decide among the various stabilization options. As previously mentioned, the posterior capsular shift is commonly used as the principal stabilization procedure. This capsular shift is performed through an open approach. The arthroscopic capsular plication and posterior labral repair can also be used in a similar fashion to effectively address soft tissue deficiency and laxity ( Figure 2-4 ). Other soft tissue procedures may include

  • •

    Posterior biceps tendon transfer


  • •

    Subscapularis transfer


  • •

    Posterior capsule reconstruction with the tensor fascia lata


  • •

    Posterior Putti-Platt repair

If the aforementioned indications for bony procedures are identified pre- or intraoperatively, then the following may be performed for bony deficiency greater than 20%, glenoid retroversion greater than 15°, or humeral retroversion greater than 60°, respectively:

  • •

    Bone block augmentation


  • •

    Glenoid opening wedge osteotomy


  • •

    A humeral rotational osteotomy

Despite the multitude of treatment options, however, the current authors use an arthroscopic posterior capsular plication and labral repair with suture anchor fixation in the vast majority of patients, including contact athletes with recurrent posterior instability ( Figure 2-5 ). Bony procedures are very rarely used and only in revision cases or patients with significant bony deficiency or glenoid retroversion.


FIGURE 2-4


Open posterior stabilization may be required in the setting of significant capsular deficiency, as seen in this image.



FIGURE 2-5


Arthroscopic posterior stabilization represents the current authors’ preferred treatment method for posterior shoulder instability. A, The posterior labral tear can be easily visualized from the anterior portal and ( B ) repaired with suture anchor glenoid fixation.


Complications


Although surgical management of posterior glenohumeral instability has been associated with excellent patient outcomes, complications also have been reported, including



  • •

    Stiffness


  • •

    Neurological injury to the suprascapular and axillary nerves


  • •

    Early osteoarthritis


  • •

    Recurrent instability and subcoracoid impingement

Recurrent instability represents the most common complication, with reported rates up to 23% following open posterior capsular shift, and may require revision surgical stabilization. Recurrence may be caused by failed index stabilization or recurrent trauma. If revision stabilization is necessary, postoperative outcomes have been improved in posttraumatic patients compared with failure of the index stabilization.

  • •

    Axillary and suprascapular nerve injury has also been reported, mainly following open posterior stabilization. Fortunately, these injuries are rare and have been associated with



    • •

      Excessive dissection


    • •

      Retraction


    • •

      Suture entrapment


Stiffness has been reported in up to 36% of patients with reduced ROM in IR and abduction. Fortunately, the majority of these patients do not require intervention, except for athletes, who require increased ROM, including overhead-throwing athletes such as football quarterbacks. In this circumstance, stiffness may impede return to play, and intervention may be required, including

  • •

    Manipulation under anesthesia


  • •

    A capsular release at 6 months postoperatively

Care should be taken, however, to perform a minimal release and not produce recurrent instability.

  • •

    Stiffness owing to overtightening during the posterior capsular shift or plication may not only produce decreased IR and abduction but may also lead to



    • •

      Increased GHJ reaction forces


    • •

      Altered mechanics


    • •

      Scapular winging


    • •

      Arthropathy



  • •

    Previous data have hypothesized that postcapsulorrhaphy arthropathy may be caused by increased shear forces that are concentrated at the posterior glenoid rim. These forces may lead to



    • •

      Chondral injury


    • •

      Early glenohumeral osteoarthritis



  • •

    On the other hand, post-stabilization osteoarthritis has also been associated with iatrogenic etiologies, including



    • •

      Bone block humeral head impingement


    • •

      Prominent intraarticular hardware


    • •

      Glenoid fracture




Evidence


  • Bigliani LU, Pollock RG, McIlveen SJ, et. al.: Shift of the posteroinferior aspect of the capsule for recurrent posterior glenohumeral instability. J Bone Joint Surg Am 1995; 77: pp. 1011-1020.
  • This study used open posterior capsulorrhaphy to manage patients with posterior shoulder instability and reduced the preoperative instability in 83% of patients. Subjective 5-year follow-up good to excellent results were obtained in 80% of shoulders and 71% of these patients returned to full activity. An 11% recurrence rate was documented and revision outcomes were noted to be worse than primary stabilization procedures. (Level IV evidence)
  • Fuchs B, Jost B, Gerber C: Posterior-inferior capsular shift for the treatment of recurrent, voluntary posterior subluxation of the shoulder. J Bone Joint Surg Am 2000; 82: pp. 16-25.
  • A unique subset of patients with recurrent, voluntary posterior shoulder instability was treated with open posterior capsulorrhaphy. Good to excellent results were reported in 93% of these patients, although a recurrent instability rate of 23% was documented. (Level IV evidence)
  • Kim SH, Park JS, Jeong WK, et. al.: The Kim test: A novel test for posteroinferior labral lesion of the shoulder—a comparison to the jerk test. Am J Sports Med 2005; 33: pp. 1188-1192.
  • A prospective cohort study of 172 painful shoulders was conducted, of which 33 had a positive Kim test result demonstrating a posteroinferior labral lesion. Twenty-four of these patients had radiographic evidence of a posteroinferior labral lesion. Among the remaining 133 shoulders with a negative Kim test, only six had radiographic evidence of a posteroinferior labral tear. Sensitivity of the Kim test was 80%, and specificity of the test was 94%.
  • Provencher MT, Bell SJ, Menzel KA, et. al.: Arthroscopic treatment of posterior shoulder instability: Results in 33 patients. Am J Sports Med 2005; 33: pp. 1463-1471.
  • Thirty-three consecutive patients with posterior instability caused by traumatic and atraumatic etiologies were treated with arthroscopic posterior stabilization with suture anchor technique. Seven failures were reported because of recurrent instability or pain. Significant improvements were noted in multiple outcome measures; however, worse outcomes occurred with patients with voluntary instability or prior shoulder surgery. (Level IV evidence)
  • Wolf BR, Strickland S, Williams RJ, et. al.: Open posterior stabilization for recurrent posterior glenohumeral instability. J Shoulder Elbow Surg 2005; pp. 157-164.
  • Open posterior capsulorrhaphy was used to successfully treat 84% of patients with posterior shoulder instability and produce a 74% rate of return to play at the baseline level. Additionally, only 19% of patients experienced postoperative instability symptoms, and no evidence of radiographic arthrosis was identified. (Level IV evidence)



    • Multiple Choice Questions




    • QUESTION 1.

      Posterior glenohumeral joint instability accounts for what percent of all shoulder instability cases?



      • a.

        90%


      • b.

        60%


      • c.

        30%


      • d.

        10%



    • QUESTION 2.

      Patients with posterior glenohumeral instability often report symptoms when the shoulder is placed in



      • a.

        extension, adduction, and external rotation.


      • b.

        extension abduction, and internal rotation.


      • c.

        flexion, adduction, and external rotation.


      • d.

        flexion, adduction, and internal rotation.



    • QUESTION 3.

      Intrinsic causes of posterior glenohumeral instability include



      • a.

        glenoid hypoplasia.


      • b.

        collagen disorder (e.g., Ehlers-Danlos).


      • c.

        humeral retroversion.


      • d.

        all of the above.



    • QUESTION 4.

      What is the most common complication after surgical management of posterior shoulder instability?



      • a.

        Axillary nerve palsy


      • b.

        Axillary artery laceration


      • c.

        Recurrent instability


      • d.

        Intraoperative fracture



    • QUESTION 5.

      All of the following provocative tests can be used to help diagnose posterior instability except:



      • a.

        Jerk test


      • b.

        Kim test


      • c.

        Martin test


      • d.

        Load and shift






    Answer Key







    Postoperative Rehabilitation after Open or Arthroscopic Posterior Shoulder Stabilization



    Emilie Schmidt, DPT, SCS, ATC, CSCS
    Amy Resler, DPT, CMP, CSCS
    Michael D. Rosenthal, PT, DSc, SCS, ECS, ATC, CSCS, CAPT
    Matthew T. Provencher, MD, MC, USN

    Indications for Surgical Treatment




    • •

      Failure of nonoperative treatment


    • •

      Persistent activity-related pain and/or pain with instability with desire to continue in these sports/activities


    • •

      Optimized nonoperative care, especially optimization of the scapular stabilizers, pectoralis minor stretching, and subscapularis strengthening


    • •

      In the nonathletic population, conservative treatment is recommended for a minimum of 3 to 6 months and would discern their level of symptoms and activities in which they are limited before deciding on surgery.


    • •

      Surgery may be recommended earlier in an athlete.



    Brief Summary of Surgical Management


    Major Surgical Steps




    • •

      General anesthesia and shoulder arthroscopy


    • •

      Patient in lateral decubitus position


    • •

      Diagnostic arthroscopy to document all pathology


    • •

      Keep scope posterior and start preparation of the posterior labrum


    • •

      Preparation of the glenoid labrum at the labrum–bone junction for adequate healing after repair ( Figures 2-6 and 2-7 ).




      FIGURE 2-6


      Magnetic resonance arthrogram of a posterior labral tear.



      FIGURE 2-7


      Posterior labral tear. Preparing the tear for surgical repair with an elevator device.


    • •

      Arthroscopic capsulolabral repair with suture anchors (usually 2.4 to 3.0 mm in diameter) and repair of the capsule and labral structures ( Figures 2-8 and 2-9 ).




      FIGURE 2-8


      Posterior labral repair.



      FIGURE 2-9


      If the tear extends anteriorly, this is repaired posteriorly and then extended anteriorly for a balanced inferior 180 ° repair of the glenoid labrum.


    • •

      Reduction of glenohumeral joint (GHJ) volume, especially in the posteroinferior quadrant (noting that posterior instability most commonly occurs at the 7 o’clock position), with capsular imbrication and repair with sutures.


    • •

      Padded abduction sling postoperatively for a total of 5 to 6 weeks. Consider use of an external rotation (ER) sling to reduce strain on repaired posterior capsular structures.



    Factors That May Affect Rehabilitation


    Anesthetic




    • •

      For regional anesthesia: the block may wear off 8 to 24 hours after the case. Be cognizant of rebound pain and use subsequent modalities.


    • •

      Surgical


    • •

      Amount of capsulolabral repair:



      • •

        Posterior only (centered at 7 o’clock): 90° posterior quadrant repair versus more extensive repair


      • •

        Posterior with some anterior augmentation (if tear extends anteriorly): will need to work on anterior capsule and note that an anterior repair was done for rehabilitation considerations. It is key to understand that the pathology of posterior instability is at 7 o’clock as the shoulder subluxes posteroinferiorly out of the joint.



    • •

      Additional repair construct (e.g., rotator interval closure): may lead to a tighter shoulder with ER at the side ( Figure 2-10 ).




      FIGURE 2-10


      Typical arthroscopic rotator interval closure: Two sutures are placed to arthroscopically imbricate the superior to middle glenohumeral ligaments after the posterior instability repair is completed.


    • •

      If case is performed open, the posterior rotator cuff (infraspinatus and teres minor) will need to be protected for 6 weeks.



    Before Surgery: Overview of Goals, Important Milestones, and Guidelines


    Steps to Minimize Debilitation and Atrophy




    Clinical Pearl


    Pursuit of normal motor patterns, correction of scapular dyskinesis, and restoration of glenohumeral and scapulohumeral arthrokinematics preoperatively will aid in postoperative recovery. Thorough movement-pattern evaluation is a key component to preoperative posterior instability rehabilitation. Recognition of faulty motor patterns associated with pain complaints will assist the therapist in developing a treatment program that will effectively and efficiently address movement pattern dysfunctions.



    Supervised Exercises




    • •

      Open and closed chain scapular stability: Scapular clocks with and without manual resistance, scapular depression (manual, resisted with tubing, Graviton).


    • •

      Rotator cuff isokinetic/progressive resistive exercises (PREs): tubing, Thera-Band, cable column IR/ER at 0, 45 °, and 90 ° of abduction


    • •

      Serratus anterior exercises: wall slides ( Figure 2-11 ) with and without resistance, supine punch ( Figure 2-12 ), standing cable/band punch. (Care should be taken to avoid posterior-directed forces during traditional serratus anterior strengthening exercises such as plank-plus and pushup-plus.)




      FIGURE 2-11


      A,B, Wall slides.



      FIGURE 2-12


      A,B, Supine punch.


    • •

      Scapular stability: prone Y, T, W, I ( Figure 2-13 ), closed chain Swiss ball movement patterns, standing shoulder flexion/scaption (open can position with scapular setting)




      FIGURE 2-13


      A,B, Prone Y, T, W, I.


    • •

      PNF patterns and rhythmic stabilization



    Modalities During Treatment




    • •

      Transcutaneous electrical nerve stimulation (TENS) to control pain as well as inhibit muscular guarding when performing both passive (PROM) and active (AROM) ROM exercises


    • •

      Interferential current (IFC) electrical stimulation to assist with pain and inflammation following treatment sessions


    • •

      Thermal agents and/or cryotherapy for muscle guarding and inflammation


    • •

      Neuromuscular electrical stimulation (NMES) in patients with a concomitant nerve injury such as suprascapular nerve neurapraxia



    Steps to Relieve Disability of Acute Injury


    Exercise




    • •

      Joint protection following an acute traumatic subluxation or posterior dislocation via sling for comfort


    • •

      Supported Codman’s pendulum exercises for passive and active assisted ROM with the modification of elbow support of the contralateral side ( Figure 2-14 )




      FIGURE 2-14


      Supported Codman’s pendulum exercises.


    • •

      Rest, ice, compression, and elevation (RICE) for 7 to 10 days


    • •

      Gradual return to AROM activities: pulleys, wands, wall walks, table slides


    • •

      Progressive strengthening and motor control per preceding recommendations


    • •

      Continuation of cardiovascular activities


    • •

      Pain should be respected and thereby serve as an indication of safe progression during this phase.



    Modalities




    • •

      IFC electrical stimulation for pain and inflammation


    • •

      Cryotherapy for pain and spasm reduction



    Steps to Relieve Disability of Chronic Injury


    Exercise




    • •

      Avoid instability and pain-producing activities. Educate the patient about positions and activities likely to create episodes of instability, such as cross-chest horizontal adduction and posterior axial loading with the arm elevated greater than 90°.


    • •

      Posterior rotator cuff (infraspinatus/teres minor) exercises are essential, as is eccentric control of the subscapularis.


    • •

      Emphasis on scapulohumeral rhythm


    • •

      Concomitant injuries of the rotator cuff must be recognized and accurately diagnosed to avoid undue stresses on other injured tissues during rehabilitation of chronic injuries


    • •

      See the preceding for supervised and home exercises for rehabilitation recommendations.



    Modalities




    • •

      IFC electrical stimulation and/or TENS to reduce pain


    • •

      Biofeedback and NMES to assist in restoring motor control


    • •

      Thermal agents and cryotherapy to reduce spasm, pain, and inflammation



    Phase I (days 0 to 14 postop)


    Protection




    • •

      Postoperative immobilization is achieved via sling use with the arm in slight abduction and neutral rotation.


    • •

      A sling with an abduction pillow is preferred because of patient comfort and proper positioning to prevent stress to the healing posterior structures.


    • •

      Sling is to be used at all times, including sleep.



    Management of Pain and Swelling




    • •

      Regional anesthetic block or a regional pain pump (not intraarticular)


    • •

      Oral pain medications


    • •

      Therapeutic modalities for pain and inflammation to include TENS, Hi-Volt, and IFC electrical stimulation


    • •

      TENS to control pain as well as inhibit muscular guarding when performing PROM


    • •

      Continuous cryotherapy for pain and inflammation reduction


    • •

      Patient education: using pillows or bolsters to find a “position of comfort” to reduce stress on contractile structures of the shoulder as well as repaired structures



    Techniques for Progressive Increase in Range of Motion


    Manual Therapy Techniques




    • •

      ROM precautions: IR 0°, humeral elevation in scapular plane 90° (precautions adjusted for other concurrent surgical repairs such as SLAP or Bankart repairs)


    • •

      PROM: manual range of humerus (per precautions) as well as affected elbow, wrist, and scapula. Muscular guarding should be considered and manual therapy adjusted as necessary to facilitate relaxation to avoid undue stresses on the posterior capsulolabral complex.



    Stretching and Flexibility Techniques for the Musculotendinous Unit




    • •

      Shoulder stretching is not to be performed during this stage with the exception of the cervical musculature (i.e., levator scapula, upper trapezius) as needed.



    Other Therapeutic Exercises




    • •

      Athletes are encouraged to participate in low-intensity cardiovascular conditioning activities such as stationary biking or treadmill walking. The sling must be worn during these activities, and if there is increased pain or muscle guarding, the activity should be adjusted.



    Activation of Primary Muscles Involved in Injury Area or Surgical Structures




    • •

      Hand gripping and active wrist flexion-extension ROM activities initiated


    • •

      Codman’s pendulum exercises to maintain passive motion at the GHJ. Because of improper technique, which is often observed clinically, the authors recommend the use of assisted Codman’s with sound-side support of the affected arm (see Figure 2-14 ).



    Milestones for Progression to the Next Phase


    Goals of the immediate postoperative phase:



    • •

      Protect the repaired structures.


    • •

      Minimize the effects of immobilization.


    • •

      Decrease pain and inflammation.

    Assuming the athlete is progressing without complications (signs of infection, frank signs and symptoms of instability or repair failure, or intractable pain limiting ROM tolerance), progression to the next phase is allowed.


    Phase II (weeks 2 to 6 postop)


    Protection




    • •

      Use of the sling is continued. If arthroscopic labral repair was performed without involvement of the rotator cuff musculature or biceps tendon, the sling may be discontinued at 4 to 5 weeks postoperatively depending on surgeon preference and patient compliance with ROM restrictions.


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    Apr 5, 2019 | Posted by in PHYSICAL MEDICINE & REHABILITATION | Comments Off on Posterior Shoulder Instability

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