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A 68-year-old woman with right shoulder pain
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An active 68-year-old right-handed woman with inflammatory arthritis, presented to clinic with right shoulder pain. She denied any antecedent trauma and noted progressive right shoulder pain during the past 6 years. Over the previous years, she had been managed with physical therapy and activity modification. She received two separate corticosteroid injections into the right glenohumeral joint, with the latter providing only short-term relief.
On physical examination, the patient had normal skin overlying the right shoulder with no obvious effusion. She was tender to palpation along the posterior joint line with no pain at the acromioclavicular (AC) joint. Shoulder range of motion was limited compared to the contralateral side: elevation 50° vs. 145°, external rotation 20° vs. 40° and internal rotation posterior ileum vs. L4. Both passive and active range of motion produced palpable painful crepitus. Strength was measured in flexion (4/5), abduction (3/5), external rotation (3/5) and internal rotation (3/5). Sensation was intact to light touch over the median, radial, ulnar and axillary nerve distributions. Pulses were preserved distally.
Radiographs and CT scans were obtained (Figure 1). The patient was found to have severe central glenoid erosion. In addition, moderate superior subluxation of the humeral head was noted.
Figure 1. Grashey (A) axillary (B) lateral radiographs and an axial CT cut (C) of the right shoulder show end-stage arthritis with severe glenoid bone loss.
Images: Sperling JW
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Shoulder arthritis
The patient presented with end-stage arthritis of the right shoulder with significant glenoid bone loss. Much like lower extremity arthroplasty practices, the incidence of shoulder arthroplasty in the United States has been increasing. With the introduction of reverse shoulder arthroplasty (RSA), indications for arthroplasty are also expanding. Surgeons are now able to restore function to patients, who a decade ago, would have had limited surgical options.
History and physical exam
When considering shoulder arthroplasty for a patient, it is important to pick the right operation for the right patient. First, a patient’s baseline functional status, hand dominance and expectations are garnered through a careful history. The physical exam should focus on range of motion and strength of the affected shoulder. Identifying rotator cuff deficiencies is an important part of the evaluation. Active range of motion and strength can be used to screen for an absent or poorly functioning rotator cuff. Specific tests, such as a Jobe’s test and a Hornblower’s sign, can be used to test the status of the rotator cuff. The integrity of the subscapularis should also be confirmed with a lift-off or belly-press test. If the rotator cuff remains functional, total shoulder arthroplasty (TSA) remains a valid surgical option. For those with a disrupted rotator cuff, a RSA may provide the best outcome.
At the time of initial consultation, three views of the shoulder are routinely obtained. These include a true AP of the glenohumeral joint (Grashey view) with the arm in internal and external rotation. In addition, an axillary radiograph is obtained which may help clarify subtle glenoid bone loss or dysplasia. A scapular Y view may also be used to assess for humeral head subluxation and acromial morphology, but does not provide the detail needed to assess the glenoid vault. We routinely obtain CT scans for all patients undergoing shoulder arthroplasty to assist with intraoperative glenoid positioning in reference to the glenoid vault. For more challenging cases with glenoid bone loss and glenoid dysplasia, 3-D reconstructions can provide added detail to help improve implant fixation. Iannotti and colleagues have shown preoperative 3-D CT scans improve surgeons’ ability to properly place the guide pin for optimal glenoid positioning.
Glenoid bone loss classification
Early in life, the glenoid may develop in a dysplastic fashion secondary to muscle paralysis or skeletal dysplasia. Inflammatory arthritis and advanced primary osteoarthritis can also lead to challenging glenoid bone loss, making shoulder arthroplasty significantly more challenging.
Figure 2. Intraoperative glenoid exposure (A) and guide placement (B) are shown.
All patients presenting with chronic conditions leading to end-stage arthritis of the shoulder should first fail nonoperative treatment modalities. These include activity modification, physical therapy, over-the-counter pain medications and intra-articular injections. Patients with glenoid bone loss deserve special consideration when planning any surgical intervention. Failure of the glenoid is the most common reason for shoulder arthroplasty revision, and inaccurate placement of the component may precipitate early failure. Severe bone loss can preclude placement of a glenoid component, and thus, prevent patients from gaining meaningful use of their arm. Numerous surgical options exist for managing glenoid bone deficiencies. It is vital that surgeons locate the best bone for glenoid implant fixation, which is typically found within the vault, the posterosuperior glenoid and along the axillary border of the scapula. For RSA, previous biomechanical and clinical studies have shown the importance of placing screws into good bone to provide stability and allow for ingrowth into the glenoid component. The availability of eccentric glenospheres have allowed surgeons to place the baseplate in the best bone and then “dial” the glenosphere inferiorly to prevent notching.
When placing a glenoid component in the setting of mild posterior or anterior glenoid erosions, eccentric reaming of the glenoid can be considered. This allows for correction of the glenoid version up to 15° and quickly allows the procedure to commence with standard techniques. However, aggressive reaming sacrifices bone stock and subchondral reaming may affect implant support. For cases in which the glenoid cannot safely be eccentrically reamed, glenoid augmentation or bone grafting is considered. Contained cavitary defects can be bone grafted with either local autograft from the humeral head resection or with bone bank allograft. Bulk allograft or tricortical iliac crest autograft can also be utilized to supplement peripheral bone defects, but may not have the same longevity as unaugmented primary implants. In addition, newer implants are being developed with metal/poly augments that function similar to structural bone grafts. For glenoids with severe bone loss, custom glenoid components can be used, but only limited reported outcomes results are available.
Figure 3. Postoperative Grashey (A) and axillary radiographs (B) of the right shoulder following reverse total shoulder arthroplasty 12 months postoperatively are seen.
Patient-specific instrumentation has started to be used in the shoulder. These guides have been shown to improve the accuracy of component placement, particularly in glenoids with significant wear. These guides allow the glenoid component to be placed in the optimal location and theoretically provide the best chance for long-term survival. Patient-specific reaming guides have also become available that allow a glenoid component to be placed without any intraoperative navigation equipment (such as Biomet’s Signature Glenoid, Zimmer’s PSI Shoulder and DJO’s Match Point System).
When large central cavitary defects preclude the placement of a standard total shoulder glenoid component, surgeons may need to proceed directly to RSA, which will allow initial screw fixation. This allows the screws to provide initial stabilization while ongrowth/ingrowth of the glenoid baseplate occurs.
Management of our patient
After failing nonoperative treatment measures, our patient decided to pursue shoulder arthroplasty. Given her cuff deficiency on exam and severe glenoid bone loss, the decision was made to proceed with RSA. Preoperatively, she presented with severe superior glenoid wear, having worn to the base of the coracoid. Her glenoid was classified as a Walch A2. Given her significant bone loss, it was imperative to identify and utilize the small portion of the glenoid bone stock remaining. Because of her symmetric severe wear pattern, bulk allograft and autograft options were not indicated, as these are designed to replace an uncontained segmental defect. The lack of peripheral containment also precluded local impaction grafting. To optimize glenoid placement with the lack of native bone stock, the decision was made to use patient specific instrumentation for placement of the glenoid baseplate.
Preoperatively, a CT scan was obtained. From this, a custom centering pin guide was manufactured by the implant company and delivered for surgery. The guide is manufactured with centering options for both an anatomic TSA and RSA. This allows the surgeon to proceed with RSA when intraoperative evaluation of the rotator cuff indicates. A single, versatile guide minimizes operative time while simultaneously guiding accurate placement of the glenoid component. Once the glenoid is exposed, it is imperative to remove the anterior labrum to allow the guide to sit down accurately. The guide is fabricated based purely on the bony architecture analyzed by CT. A centering pin was placed and reaming was performed. The glenoid baseplate was placed with one central screw and four peripheral locking screws. A short, uncemented humeral stem was placed and the wound closed in routine fashion.
At 1-year postoperatively, the patient was doing well with minimal to no pain. Elevation had improved to 120°. External rotation improved to 40°, and internal rotation remained relatively similar with motion to the sacrum. She returned to her daily activities.
References:
Chebli C. J Shoulder Elbow Surg. 2008;doi:10.1016/j.jse.2007.07.015.
Iannotti J. J Bone Joint Surg Am. 2014;doi:10.2106/JBJS.L.01346.
Kim SH. J Bone Joint Surg Am. 2011;doi:10.2106/JBJS.J.01994.
Klika BJ. J Shoulder Elbow Surg. 2014;doi:10.1016/j.jse.2013.09.017.
Lehtinen JT. J Shoulder Elbow Surg. 2004;doi:10.1016/j.jse.2004.01.012
Nowak DD. J Shoulder Elbow Surg. 2009;doi:10.1016/j.jse.2009.03.019.
Rice RS. Clin Orthop Relat Res. 2008; doi:10.1007/s11999-007-0104-4.
Stubig T. Int J Med Robot. 2013;doi:10.1002/rcs.1519.
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For more information:
Bradley S. Schoch, MD; and John W. Sperling, MD, MBA, can be reached at the Mayo Clinic, 200 1st St. SW Rochester, MN 55905; Schoch’s email: brad.schoch@gmail.com; Sperling’s email: sperling.john@mayo.edu.
Disclosures: Schoch has no relevant financial disclosures. Sperling receives royalties from Biomet.