Posterior Capsular Reconstruction for Recurrent Posterior Shoulder Instability

    A 34-year-old male patient sustained a posterior shoulder dislocation in a motor vehicle accident. Three surgeries later, he is still experiencing recurrent posterior shoulder instability. What are the treatment options at this point?


    Ryan M. Cox, MD, and Daniel E. Davis, MD, MS


    Recurrent posterior shoulder instability is a relatively uncommon problem that can be difficult to manage. [1,2] Patients are usually younger males who are active or contact athletes. [1] The recurrent instability usually presents not as a discrete dislocation requiring reduction, but as recurrent subluxation episodes. [2] Consistent diagnostic criteria for accurately classifying this pathology are lacking, however, and it may be better to think of recurrent posterior shoulder instability as a spectrum of disease.

    Operative treatment has not been associated with the best outcomes. It is recommended that patients with posterior shoulder instability undergo an adequate trial of physical therapy prior to attempted shoulder stabilization. Accurately assessing all causes of instability is essential so that they can be addressed during surgical stabilization, including the opportunity for a successful outcome.

    Typical stabilization options for recurrent posterior shoulder instability include: [3-8]

    • Posterior labral repair
    • Posterior capsular shift
    • Posterior glenoplasty or osteotomy
    • Bone block procedure with various bone grafts
    • Shoulder arthrodesis

    Capsulorraphy and augmentation with tendon allograft reconstruction has been described for rare situations. [9,10]

    In this article, we describe the care of a 34-year-old male patient with recurrent posterior shoulder instability despite 3 previous surgical procedures. The case highlights the difficulty in managing recurrent posterior shoulder instability, the reconstructive treatment options, and the technique for utilizing an Achilles tendon allograft in reconstruction of the posterior capsule.

    Case Presentation

    A 34-year-old, right-hand dominant male patient presented to the authors’ office with recurrent right shoulder posterior instability after being involved in a motor vehicle accident. He was the driver of a car that was rear-ended by an 18-wheeler approximately 20 months prior. He felt his right shoulder dislocate posteriorly during the accident and he was able to reduce it on his own. He denies any previous episodes of shoulder instability.

    Three months after the injury, he underwent a posterior labral repair. He had atraumatic recurrent instability 6 months postoperatively and underwent another arthroscopic procedure with anterior and posterior stabilization. At 8 months and 14 months from his arthroscopic stabilization procedures, he underwent an open posterior capsular shift due to continued episodes of posterior instability. All 3 procedures were done at another institution.

    The patient was immobilized in a gunslinger brace for approximately 2 months postoperatively but continued to experience posterior instability after a complete period of immobilization and physical therapy. He was able to voluntarily and occasionally non-voluntarily dislocate and reduce his shoulder. Despite the instability, his shoulder was not painful at rest, but he was unable to perform some of his activities at waist level. He presented to the authors’ office for another opinion.

    Physical Examination

    • Active forward elevation to 160°, with a visible shift of the shoulder posteriorly at approximately 90° of forward elevation
    • Active external rotation to 45°
    • 5/5 external rotation strength
    • Active internal rotation to the mid-lumbar spine, compared with active internal rotation to the mid-thoracic spine on the contralateral side
    • Negative abdominal compression test
    • Positive posterior jerk test with painful posterior subluxation
    • Negative exam findings for anterior instability


    The patient’s initial post-injury imaging was not available for review. Radiographs of the right shoulder on presentation to our institution demonstrate persistent posterior subluxation of the humeral head.


    Figure 1. (A) Anteroposterior, (B) axillary, and (C) scapular-Y views of the right shoulder demonstrate persistent posterior subluxation of the humeral head.

    After initial assessment of the patient in the office, a right shoulder computed tomography (CT) scan and magnetic resonance (MR) arthrogram were obtained for surgical planning.

    Figure 2. Axial CT scan demonstrates minimal posterior humeral head subluxation with minimal posterior glenoid bone loss.


    Figure 3. (A) Coronal cut of the MR arthrogram demonstrates an intact rotator cuff. (B) Axial cut of the MR arthrogram demonstrates a degenerative posterior capsule and labrum with no evidence of an anterior labral tear.


    • Recurrent posterior shoulder instability after multiple shoulder stabilization procedures due to a deficient posterior labrum and capsule with minimal glenoid bone loss


    Arthroscopic Posterior Labral Repair

    Arthroscopic treatment of posterior instability is becoming more popular as surgeons develop a familiarity with the techniques. It is primarily utilized in cases without significant posterior glenoid bone loss (less than 15% to 20%).


    • Mostly useful in cases with minimal glenoid bone loss
    • Arthroscopic technique allows for assessment of other intra-articular pathology that may not have been recognized preoperatively
    • Can easily convert to an open procedure if necessary


    • May not be able to address larger defects

    Open Posterior Capsular Shift

    This technique involves mobilizing the inferior capsule and shifting it superiorly. It can be utilized in cases with minimal glenoid bone loss (less than 15% to 20%) or deformity.


    • Useful in patients who have a greater amount of subluxation and minimal glenoid bone loss
    • Useful in patients who failed prior arthroscopic stabilization


    • Not able to correct glenoid bone loss or deformity

    Posterior Bone Block Procedure

    Guidelines on treating posterior glenoid bone loss with bone augmentation are less well defined for posterior shoulder instability than for anterior shoulder instability. In addition, glenoid retroversion or hypoplasia may require the surgeon to perform a bone block or bone augmentation procedure with less glenoid bone loss compared with anterior glenoid lesions. These procedures can be performed with a variety of graft options, including iliac crest autograft and distal tibial osteoarticular allograft.


    • Able to reconstruct a glenoid with more significant bone loss (more than 15% to 20%)
    • Useful in patients who failed prior arthroscopic stabilization
    • Able to address glenoid bone loss and glenoid retroversion


    • Donor site morbidity with iliac crest autograft
    • Cost and availability

    Capsular Reconstruction with Allograft

    This technique has been primarily utilized in patients with underlying connective tissue disorders or in patients with insufficient capsule and labral tissue with minimal glenoid bone loss.


    • Useful in patients with underlying connective tissue disorder
    • Variety of graft options available, including Achilles tendon or acellular dermal matrix graft


    • Rare technique with limited evidence
    • Potential of graft stretch or failure leading to continued recurrent instability

    Shoulder Arthrodesis

    Shoulder arthrodesis is primarily reserved as a salvage option for patients who have failed all other surgical stabilization options.


    • Effective salvage procedure for failed stabilization procedures


    • Greater decrease in postoperative range of motion and limitations in activities compared with other techniques
    • Requires adequate arthrodesis healing for adequate stability and pain relief

    These repair options were discussed in detail with the patient, as were non-operative measures. The findings on MR arthrogram suggested that little to no native capsule remained for repair. Given the exam and radiologic findings, as well as the patient’s strong desire for another procedure to provide more stability, the decision was made to undergo reconstruction of the posterior capsule with an Achilles tendon allograft.


    Diagnostic Shoulder Arthroscopy

    • The patient was taken to the operating room and positioned in a well-padded beach chair position. General anesthesia was induced.
    • Examination under anesthesia demonstrated complete posterior instability of the glenohumeral joint.
    • The arthroscope was then inserted into the shoulder using a standard posterior viewing portal in the surgical incision from the patient’s previous open posterior capsular shift procedure.
    • The biceps anchor was stable, with no tearing or tenosynovitis of the biceps tendon. The rotator cuff tendons were intact.
    • We observed significant degeneration of the posterior labrum and capsule, as well as loose and torn sutures from the previous capsulorrhaphy.
    • The labrum was intact anteriorly, and sutures remained in place from the previous stabilization procedure.
    • Some small inferior humeral osteophytes were present; however, no full-thickness cartilage loss was observed.
    • The arthroscope was then placed in an anterior portal, which again demonstrated significant degeneration and tearing of the posterior labrum and capsule.

    Open Posterior Capsular Reconstruction with Achilles Allograft

    • The arthroscope was removed and a skin incision was made over the posterior shoulder utilizing the previous posterior incision.
    • The deltoid fascia was identified and the most inferior portion was bluntly dissected to elevate the entire deltoid anterolaterally along with its fascial sleeve.
    • The fat stripe between the infraspinatus and teres minor muscles was identified. Blunt dissection was utilized between this interval to access the posterior-inferior aspect of the glenohumeral joint.
    • There was some capsular tissue present but it was very degenerative and torn. The articular surface could be easily visualized (Figure 4A).
    • The medial border of the glenoid was then debrided of all soft tissues and lightly decorticated. Two single-loaded, 3.0-mm suture anchors were placed on the glenoid at approximately the 6 o’clock and 8 o’clock positions (Figure 4B).
    • Blunt dissection was utilized laterally to identify the bare area of the posterior-inferior humeral head. A double-loaded, 4.5-mm suture anchor was placed at the most lateral aspect of the bare area (Figure 4B).
    • The arm was placed in abduction and approximately 20° of external rotation. The distance between the most inferior glenoid suture anchor and the humeral suture anchor was measured to be 2 cm. An approximately 4.5-cm Achilles allograft was then prepared to allow the graft to be folded over twice for the capsular reconstruction.
    • The sutures from the inferior glenoid anchor were passed in a horizontal mattress fashion through one end of the Achilles allograft. An arthroscopic knot pusher was used to securely tighten the knots against the glenoid.
    • The graft was then tensioned and 1 of the medial sutures from the humeral anchor was passed through the Achilles allograft in a horizontal mattress fashion. It was tied using an arthroscopic knot pusher.
    • The arm was then placed in approximately 45° of abduction and 40° of external rotation. The graft was doubled over and the sutures from the superior glenoid anchor were passed in a horizontal mattress fashion through the graft to reconstruct the posterior-inferior capsule.
    • The second suture from the humeral anchor was then passed through the folded over Achilles allograft in a horizontal mattress fashion to secure the graft to the humerus (Figure 4C).
    • The arm was removed from the arm holder and taken through a gentle range of motion. The graft demonstrated increased tension with internal rotation, but the arm was not taken past neutral rotation to avoid failure of the graft reconstruction.


    Figure 4. Intraoperative photos of the posterior capsular reconstruction with Achilles tendon allograft. (A) Exposure of posterior glenohumeral joint with deficient posterior-inferior capsule and labrum. (B) Anchor placement with 2 anchors on the posterior glenoid and 1 anchor on the bare area on the humeral head. (C) Final tensioned Achilles tendon allograft reconstruction of the posterior-inferior capsule.

    Postoperative Course

    The patient was placed in a gunslinger brace with the arm in 30° of abduction and 20° of external rotation.

    2 Weeks Postoperatively

    The surgical incision was healing appropriately at the 2-week postoperative visit. The patient had been compliant with wearing the gunslinger brace and was instructed to continue using it at all times.

    6 Weeks Postoperatively

    The patient remained compliant with the gunslinger brace. Passive elevation was at 160°, with no posterior subluxation. Active forward elevation was deferred. Passive external rotation was at 45° and passive internal rotation was to his stomach.

    The patient was instructed on how to do passive forward elevation and external rotation exercises on his own and was told to avoid active motion. Formal physical therapy would be started at a later date.

    He was allowed to remove the gunslinger brace at home but continued to use it when out in public.

    6 Months Postoperatively

    The patient’s postoperative course was delayed due to the COVID-19 pandemic. When he was finally able to follow up, he indicated that he had been using his shoulder for everyday activities and thought it was 90% better than it had been preoperatively.

    He still experiences occasional instability when doing activities that are high over his head, but he stated that it feels different than the complete instability he felt preoperatively. At the 6-month postoperative visit, he was able to actively elevate his shoulder to 150° with no pain.


    Recurrent posterior shoulder instability is a difficult problem to manage, with limited treatment options. Posterior capsular reconstruction with an Achilles tendon allograft is an available reconstruction option in cases with minimal glenoid bone loss, but it may still be associated with recurrent instability and limitations in activities postoperatively.

    Author Information

    Ryan M. Cox, MD, is an orthopaedic surgery resident at Thomas Jefferson University Hospital. Daniel E. Davis, MD, MS, is an orthopaedic surgeon with The Rothman Institute, Philadelphia, Pennsylvania, specializing in the treatment of shoulder and elbow conditions. He is also the Shoulder Section Editor for Rothman Institute Grand Rounds on ICJR.net.

    Disclosures: Dr. Cox has no disclosures relevant to this article. Dr. Davis has disclosed that he is a consultant for Arthrex, Inc, and that owns stock/stock options in Catalyst OrthoScience.


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