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    Augmented Reverse Shoulder Arthroplasty for Complex Instability with Glenoid Fracture

    A 67-year-old female patient who presents with a 3-week history of right shoulder pain is diagnosed with recurrent dislocation and a bony abnormality on her glenoid.

    Author

    Daniel E. Davis, MD, MS

    Introduction

    Reverse total shoulder arthroplasty (RTSA) has continued to increase in prevalence in the United States since its approval by the US Food and Drug Administration in 2004. [1] Although the original indication of the implant design was to combat the anterior superior escape and pseudoparalysis patients experienced with rotator cuff arthropathy, its indications have expanded. [2] RTSA is now used for many salvage and complex problems of the shoulder including:

    • Proximal humerus fractures
    • Revision arthroplasty surgery
    • Chronic or complex instability
    • Some instances of primary osteoarthritis

    The case reported in this article describes a patient with a traumatic shoulder dislocation and glenoid fracture who underwent RTSA with a metal augment to fill the defect created by the glenoid fracture.

    Case Presentation

    A 67-year-old, right-hand dominant female patient presents with a 3-week history of right shoulder pain. She had a trip and fall injury while at home, landing on her right side. She did not lose consciousness.

    At the emergency department, shoulder dislocation was diagnosed and reduced. The patient followed up with a non-operative physician, but after her first visit, she experienced increasing pain in the right shoulder.

    Repeat radiographs demonstrated recurrent dislocation with a bony abnormality noted on her glenoid. She was referred to an orthopaedic shoulder surgeon for further evaluation.

    Physical Examination

    • Height: 5 feet, 1 inch; weight: 200 pounds; BMI: 37.8
    • Inspection: No ecchymosis, skin intact, notable depression distal and anterior to the acromion
    • Palpation: Gross tenderness about the shoulder
    • Range of motion (ROM): Shoulder ROM deferred secondary to pain; full ROM of elbow, wrist, and hand
    • Strength testing: Positive activation of all 3 heads of the deltoid; full strength with elbow flexion and extension, wrist extension, hand intrinsics, and finger flexion
    • Neurovascular: Sensation intact to light touch in axillary, median, ulnar, and radial nerve distribution; palpable radial pulse

    Imaging: Radiographs

    • Recurrent anterior-inferior dislocation with probable fracture of the anterior-inferior glenoid on AP and scapular Y lateral views (Figure 1)
    • Initial dislocation and reduction radiographs unavailable for review

     

    Figure 1. AP (left) and scapular Y (right) views demonstrate the recurrent anterior dislocation with likely anterior-inferior glenoid fracture.

    Imaging: CT Scan

    • Comminuted anterior inferior glenoid fracture with anterior inferior dislocation of the humerus (Figure 2)

    Figure 2. Axial CT imaging demonstrates the large glenoid deformity, with humerus dislocated anteriorly.

    Imaging: MRI

    • Anterior-inferior shoulder dislocation with comminuted glenoid fracture
    • Edema in the humeral head suggesting Hill-Sachs deformity
    • High-grade partial-thickness rotator cuff tear (Figure 3)

     

    Figure 3. MRI imaging demonstrates the anterior glenoid deformity with Hill-Sachs defect (left) and rotator cuff tear (right).

    Diagnosis

    • Recurrent anterior-inferior shoulder dislocation with comminuted anterior-inferior glenoid fracture, small Hill-Sachs deformity, and high-grade partial-thickness rotator cuff tear

    Treatment

    The patient sustained a traumatic shoulder dislocation with a bipolar bony lesion, more significant on the glenoid side than on the humeral side, leading to atraumatic recurrent dislocation. Further treatment options were discussed with the patient:

    • Continued non-operative treatment was not likely to be successful in maintaining a stable shoulder.
    • Fixation of the glenoid fracture was discussed but determined not to be feasible due to the fracture comminution and the patient’s age.
    • Treatment with RTSA was presented as an option that would allow the patient to return to activity with a stable shoulder.

    The patient agreed to RTSA and the procedure was scheduled.

    Preoperative Planning

    As part of the preoperative planning, the CT scan was loaded into a preoperative planning software tool (Blueprint, Wright Medical; Lyon, France). This software would assess the need for an augmented baseplate to fill in the defect created by the comminuted glenoid fracture and, if deemed necessary, help plan the most appropriate position for an augmented baseplate on the fractured glenoid.

    The planning software determined that a 25-mm baseplate with a half-wedge 35° augment would most appropriately fill the defect, with 85% coverage of the glenoid surface (Figure 4). Measurements were then taken from the predicted central point to identify the best position to place the guide pin intraoperatively (Figure 5).

    Figure 4. Preoperative planning software helped to determine that a half-wedge with 35° augment would provide the maximum baseplate coverage in this patient.

     

    Figure 5. Preoperative planning software demonstrated the ideal position for the guide pin to be able to execute the preoperative plan intraoperatively on the coronal (left) and sagittal (right) views.

    Procedure

    • The patient was positioned in the beach chair positioner, with her right upper extremity prepped and draped in a standard fashion.
    • A standard deltopectoral approach was performed, taking the cephalic vein laterally with the deltoid.
    • Due to the chronicity of the dislocation, there were adhesions between the subscapularis and conjoint tendon. Therefore, dissection was not performed in this plane with the humerus dislocated.
    • Dissection was performed beginning at the bicipital groove, peeling the subscapularis and underlying capsule from the humerus as a sleeve to allow for humeral dislocation. The long head of the biceps was tenodesed to the pectoralis major tendon prior to dislocation.
    • The humerus was delivered from the wound and the humeral head was osteotomized with a saw along the native anatomic neck of the humerus.
    • The humerus was then retracted posteriorly and laterally.
    • At this point, dissection was able to be safely performed between the subscapularis and the conjoint tendon to allow for palpation and protection of the axillary nerve. A 360° release of the subscapularis was performed.
    • The glenoid was exposed, revealing a 40% defect in the anterior-inferior portion of the bony glenoid face. The stump of the biceps tendon and labrum were circumferentially removed. The fractured portion of the glenoid was extremely comminuted and left in place.
    • A guide pin was placed in the face of the glenoid in the position as determined on preoperative planning and with the use of the half-wedge 35° guide.
    • A reamer was used to gently ream the intact portion of the posterior glenoid. An angled reamer set to 35° was then used in the anterior- inferior portion, but little bone was present to ream.
    • The half-wedge guide was again repositioned into the defect and demonstrated appropriate coverage of the glenoid face consistent with the preoperative plan.
    • The central drill hole was drilled and the baseplate with a 35° metal augment was placed in the appropriate position and secured with a 6.5-mm x 35-mm screw, gaining excellent fixation. Peripheral screws were drilled, measured, and then placed in all positions except anterior-inferiorly.
    • A 36-mm glenosphere with 3 mm of lateralization was placed and secured with a central screw.
    • The humerus was then delivered from the wound and prepared to accept an appropriately sized short-stemmed component, which achieved excellent fixation after being countersunk by a few millimeters to inset the tray. The tray was inset and a 36-mm polyethylene component with +6 mm of lateralization was implanted.
    • The shoulder was reduced, demonstrating excellent ROM and stability with no lift-off or dislocation. The final humeral components were placed after trialing all final sizes.
    • The incision was closed in a standard fashion and the patient was placed in an abduction sling.

    Postoperative Followup

    The patient was seen at 2 weeks postoperatively for a wound evaluation and advancement of activity. Her range of motion was 10° of external rotation and 70° of forward elevation passively. The abduction brace was discontinued, and the patient was advanced to a home exercise program of passive and active motion with forward elevation and external rotation. She was instructed to limit internal rotation, with no arm behind the back and no pushing up from a seated position.

    At her 6-week follow-up visit, she had advanced to active forward elevation to 100°; external rotation remained at 10°. Her pain was well controlled, and she had 4/5 strength with resisted external rotation and Jobe’s testing. Due to failure to advance more with home exercise for ROM, she started formal physical therapy. All restrictions were lifted at this time.

    By the 3-month follow-up visit, she had completed 6 weeks of physical therapy and had advanced to 120° of active forward elevation and 30° of external rotation, with internal rotation to the sacrum. She had excellent maintained strength. She wanted to continue with physical therapy and was given a prescription for another 6 weeks.

    The 6-month follow-up visit revealed continued advancement with ROM, with forward elevation to 140°, external rotation to 40°, and internal rotation to the sacrum. At the final 1-year follow-up visit, the patient demonstrated the same ROM parameters with full strength and no pain.

    Radiographs at all follow-up visits demonstrated a stable implant with no fracture or dislocation (Figure 6).

     

    Figure 6. Postoperative imaging demonstrates reconstruction of the shoulder on the AP radiograph (a), with the augment appropriately filling in the bony defect on the axillary lateral radiograph (b).

    Discussion

    Reverse shoulder arthroplasty indications have continued to advance beyond the original rotator cuff arthropathy. A common use of RTSA is for complex fractures in the shoulder. Most reported cases, however, focus on 3- and 4-part comminuted proximal humerus fractures. There are few reported cases of traumatic glenoid bone loss and instability treated with RTSA.

    In a matched cohort study, Hasler et al [3] compared 11 cases of shoulder instability treated with RTSA with 22 cases of RTSA for rotator cuff arthropathy. Patients with rotator cuff arthropathy trended toward improved ROM parameters, but no significant difference was found. Patient-reported outcome measures were equal between groups, with no cases of recurrent instability in either group. [3]

    Olszewski et al [4] reported on a patient with a chronic, locked anterior shoulder dislocation, a large Hill-Sachs defect, and 30% glenoid bone loss who was treated with RTSA. They were able to secure the base plate without bone or metal augment. At 2 years after surgery, the patient had excellent ROM and a subjective shoulder score of 90%. [4]

    The use of bony augmentation for posterior glenoid wear has been well described, with many reports of good results. Paul et al [5] described 393 patients with bone grafting who demonstrated excellent bony union with a low revision rate. Garofalo et al [6] described a series of 26 patients with glenohumeral instability and anterior glenoid fractures treated with RTSA and bone grafting of the anterior glenoid. They reported a mean Constant score of 68.2, with 24 of the 26 patients having good to excellent outcomes. [6]

    However, the use of bony augments may create increased complications if larger bone grafts are needed, as reported by Ho et al [7] In their retrospective review, 44 patients had undergone structural bone graft for severe glenoid bone. Failure occurred in 25% of cases, with graft resorption and hardware failure. [7]

    Recently, metal augments have been designed to correct bony glenoid deformity, with early reports of success. Sandow et al [8] described 10 patients treated with metal augments for glenoid deformity. At 2-year follow-up, patients reported good satisfaction with no complications. [8]

    The case presented in this article utilizes the new technology of glenoid augments for an indication for which they were not originally intended. Although posterior glenoid wear is a common and frequently difficult problem to treat, anterior glenoid bone loss and recurrent instability is not typically managed with arthroplasty, as there often is not enough glenoid support for a baseplate.

    In rare circumstances, such as this case, however, excessive bone loss may lead to the necessity of adding augmentation. Although bony augmentation has been shown to be a successful option, there is the risk of graft resorption and hardware failure. Therefore, the use of metal augmentation is an attractive option to allow for more bony support of the augment and secure ingrowth.

    This case presents another option for managing the rare problem of recurrent instability with significant glenoid bone loss in the older adult population.

    Author Information

    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 the Shoulder and Elbow Editor for Rothman Institute Grand Rounds on ICJR.net.

    Disclosures: Dr. Davis has no disclosures relevant to this article.

    References

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    2. Urch E, Dines JS, Dines DM. Emerging Indications for Reverse Shoulder Arthroplasty. Instr. Course Lect. 2016;65:157–169.
    3. Hasler A, Fornaciari P, Jungwirth-Weinberger A, Jentzsch T, Wieser K, Gerber C. Reverse shoulder arthroplasty in the treatment of glenohumeral instability. J. Shoulder Elbow Surg. 2019 Aug;28(8):1587–1594. doi:10.1016/j.jse.2019.02.001
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    7. Ho JC, Thakar O, Chan WW, Nicholson T, Williams GR, Namdari S. Early radiographic failure of reverse total shoulder arthroplasty with structural bone graft for glenoid bone loss. J. Shoulder Elbow Surg. 2019 Oct 11;doi:10.1016/j.jse.2019.07.035
    8. Sandow M, Schutz C. Total shoulder arthroplasty using trabecular metal augments to address glenoid retroversion: the preliminary result of 10 patients with minimum 2-year follow-up. J. Shoulder Elbow Surg. 2016 Apr;25(4):598–607. doi:10.1016/j.jse.2016.01.001