The number of reverse total shoulder arthroplasties done annually is increasing steadily,10Registry N.J. National Joint Registry's 19th annual report.https://www.njrcentre.org.uk/njr-annual-report-2022/Date: 2022Date accessed: January 8, 2024Google Scholar even when in a systematic review of literature, the complication rate after a reverse total shoulder arthroplasty (rTSA) was found to be around 24%.16Zumstein M.A. Pinedo M. Old J. Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review.J Shoulder Elbow Surg. 2011; 20: 146-157https://doi.org/10.1016/j.jse.2010.08.001Abstract Full Text Full Text PDF PubMed Scopus (637) Google Scholar A common complication after this surgery is the presence of persistent pain in the postoperative period which could be due to a variety of reasons such as intraoperative fractures, instability, infection, or neurologic injuries.5Ekelund A.L. Management of painful reverse shoulder arthroplasty.Shoulder Elbow. 2017; 9: 212-222https://doi.org/10.1177/1758573217702333Crossref PubMed Scopus (9) Google Scholar Frequently, it is difficult to establish a clear cause for persistent postoperative pain following rTSA implantation. Per the National Joint Registry's (NJR's) 19th annual report, the 5 most commonly used shoulder arthroplasty systems in the United Kingdom include Aequalis Ascend Flex, Comprehensive, Equinoxe, Delta Xtend, and SMR Stem.10Registry N.J. National Joint Registry's 19th annual report.https://www.njrcentre.org.uk/njr-annual-report-2022/Date: 2022Date accessed: January 8, 2024Google Scholar The rTSA systems of all these systems include a glenoid base plate that is fixed with screws inserted into the glenoid vault. There are biomechanical studies that suggest that the best bone for optimal screw placement is located in the base of the coracoid, lateral suprascapular fossa, spine of scapula, and the inferior glenoid pillar.3DiStefano J.G. Park A.Y. Nguyen T.-Q.D. Diederichs G. Buckley J.M. Montgomery III, W.H. Optimal screw placement for base plate fixation in reverse total shoulder arthroplasty.J Shoulder Elbow Surg. 2011; 20: 467-476https://doi.org/10.1016/j.jse.2010.06.001Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar,11Stephens B.F. Hebert C.T. Azar F.M. Mihalko W.M. Throckmorton T.W. Optimal baseplate rotational alignment for locking-screw fixation in reverse total shoulder arthroplasty: a three-dimensional computer-aided design study.J Shoulder Elbow Surg. 2015; 24: 1367-1371https://doi.org/10.1016/j.jse.2015.01.012Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar However, directing screws toward the base of the coracoid process carries a theoretical risk of piercing the floor of the supraspinatus fossa and injuring the suprascapular nerve (SSN) from a misdirected or overlength screw. In a cadaveric study, the average distance from the exiting point of the superior screw in the scapula to the SSN was 9.2 ± 6.3 mm, with the shortest distance being 3.9 mm.13Vance D.D. O'Donnell J.A. Baldwin 3rd, E.L. Cheah J.W. Pereira G. Klifto C. et al.Risk of suprascapular nerve injury during glenoid baseplate fixation for reverse total shoulder arthroplasty: a cadaveric study.J Shoulder Elbow Surg. 2021; 30: 532-537https://doi.org/10.1016/j.jse.2020.07.008Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar The aim of this study is to highlight the importance of SSN irritation, through a case discussion, as a cause of postoperative pain after rTSA and describe a technique for its management. A 69-year-old woman underwent a left rTSA (Equinox; Exactech Inc., Gainsville, FL, USA) for a cuff-deficient left shoulder with proximal humeral migration, after a previous fracture dislocation (Fig. 1). In the immediate postoperative period, she complained of persistent pain of a severe nature, particularly on the lateral aspect of the shoulder. Of note, her pain was present at rest and was made worse on movement, and the severity had worsened, compared with the pain experienced prior to surgery. On examination, there were no clinical signs of infection around the shoulder. She complained of tenderness on the lateral aspect of the shoulder as well as in the supraspinatus fossa. Her active range of motion was 80° of forward flexion and 80° of abduction, both of which were limited by severe pain, and attempted passive assistance to range of motion caused significant exacerbation of her painful symptoms. Her internal rotation was to L5 level, although she could not actively externally rotate beyond neutral. Even with her pain, she demonstrated MRC grade 4 power in flexion as well as abduction. There was no neurovascular deficit in the left upper limb, specifically in the distribution of the axillary nerve. Systematic investigation for common causes of postoperative shoulder pain following a rTSA noted no abnormalities in blood markers, including her inflammatory profile. Plain radiographs demonstrated well-fixed implants with no obvious fractures (Fig. 2). A nuclear medicine bone scan revealed mildly increased uptake within the glenoid component, which was concluded to be due to ongoing remodeling and integration of the prosthesis in the first postoperative year (Fig. 3). She underwent a tissue biopsy to rule out indolent infection, including extended cultures for Cutibacterium acnes, which were negative. She also underwent a computed tomography scan that failed to demonstrate any stress fractures around the scapula. However, the scan demonstrated the possibility of penetration of the superior screw into the supraspinatus fossa, around the course of the SSN in the region (Fig. 4).Figure 3Postoperative nuclear medicine scan.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 4Postoperative computed tomography scan.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The case was discussed in the local Shoulder and Elbow multidisciplinary team meeting and the patient underwent an arthroscopic assessment of the shoulder and exploration of the SSN in the supraspinatus fossa. During the procedure, the superior screw of the base plate was observed to have pierced the superior cortex of the vault and had entered the suprascapular fossa and was abutting the SSN, leading to formation of a neuroma (Fig. 5). The SSN was divided along with the release of the transverse ligament, while preserving the accompanying suprascapular artery. Postoperatively, the patient noted immediate improvement in her pain and range of motion. During her last follow-up visit 5 years after her surgery, she had an active forward flexion and abduction of 90°, with an external rotation of 20° and an internal rotation to the L5 level. Her last visual analog scale pain score improved to 2/10 and her Oxford Shoulder Score was 36/48. Overall, she felt that the outcome of her surgery has been good on a subjective scale. Reverse TSA was first introduced for cuff tear arthropathy7Grammont P. Baulot E. Delta shoulder prosthesis for rotator cuff rupture.Orthopedics. 1993; 16 (SLACK Incorporated Thorofare, NJ): 65-68Crossref PubMed Scopus (34) Google Scholar; subsequently, the indications have rapidly expanded for treatment of complex fractures,14Wall B. Walch G. Reverse shoulder arthroplasty for the treatment of proximal humeral fractures.Hand Clin. 2007; 23: 425-430https://doi.org/10.1016/j.hcl.2007.08.002Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar irreparable cuff tears,4Ek E.T. Neukom L. Catanzaro S. Gerber C. Reverse total shoulder arthroplasty for massive irreparable rotator cuff tears in patients younger than 65 years old: results after five to fifteen years.J Shoulder Elbow Surg. 2013; 22: 1199-1208https://doi.org/10.1016/j.jse.2012.11.016Abstract Full Text Full Text PDF PubMed Scopus (313) Google Scholar as well as failed hemiarthroplasty or anatomic shoulder arthroplasty.1Abdel M. Hattrup S. Sperling J. Cofield R. Kreofsky C. Sanchez-Sotelo J. Revision of an unstable hemiarthroplasty or anatomical total shoulder replacement using a reverse design prosthesis.Bone Joint J. 2013; 95: 668-672https://doi.org/10.1302/0301-620X.95B5.30964Crossref Scopus (46) Google Scholar Because of the rapid expansion of indications of this prothesis, the number of rTSAs done in the United Kingdom has risen steadily over the last 10 years and currently about 2850 are done every year, roughly accounting for two-thirds of all shoulder arthroplasties done.10Registry N.J. National Joint Registry's 19th annual report.https://www.njrcentre.org.uk/njr-annual-report-2022/Date: 2022Date accessed: January 8, 2024Google Scholar Postoperative pain remains a common complication after this procedure, the cause of which is frequently clinically challenging to diagnose. Previously, algorithms for management of a patient with a painful rTSA have been reported in literature.5Ekelund A.L. Management of painful reverse shoulder arthroplasty.Shoulder Elbow. 2017; 9: 212-222https://doi.org/10.1177/1758573217702333Crossref PubMed Scopus (9) Google Scholar,6Fossati C. Vitale M. Forin Valvecchi T. Gualtierotti R. Randelli P.S. Management of painful shoulder arthroplasty: a narrative review.Pain Ther. 2020; 9: 427-439https://doi.org/10.1007/s40122-020-00186-0Crossref PubMed Scopus (6) Google Scholar Our management approach for such a case includes careful history regarding the site and onset of pain, noting any history of trauma, followed by a physical examination to identify any signs of infection, ascertain the location of tenderness, record active and passive range of motion, and finally, assessment of any motor or sensory loss in the arm. It is also standard to perform anteroposterior, axillary, and lateral radiographs, along with blood tests for inflammatory markers like neutrophil count, C-reactive protein level, and erythrocyte sedimentation rate in all cases. Depending on the history and examination, further tests such as computed tomography scans and aspiration or biopsy of the shoulder implant may be done to rule out fractures or indolent infection, respectively. Following exclusion of common causes of pain, other causes such as acromioclavicular joint pathology, SSN irritation, and referred pain from cervical spine should be considered. SSN irritation following rTSA, causing persistent postoperative pain, has rarely been reported.15Wang J. Singh A. Higgins L. Warner J. Suprascapular neuropathy secondary to reverse shoulder arthroplasty: a case report.J Shoulder Elbow Surg. 2010; 19: e5-e8https://doi.org/10.1016/j.jse.2009.10.004Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar However, glenoid baseplate screw implantation during rTSA has been identified as being a risk for SSN injury.12Vajapey S.P. Contreras E.S. Cvetanovich G.L. Neviaser A.S. Neurologic complications in primary anatomic and reverse total shoulder arthroplasty: a review.J Clin Orthop Trauma. 2021; 20101475https://doi.org/10.1016/j.jcot.2021.06.005Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar A cadaveric study has shown that a 44-mm bicortical superior screw contacted the SSN in 8 of 12 specimens whereas a similar-size posterior screw contacted the SSN in 6 of 12 specimens.13Vance D.D. O'Donnell J.A. Baldwin 3rd, E.L. Cheah J.W. Pereira G. Klifto C. et al.Risk of suprascapular nerve injury during glenoid baseplate fixation for reverse total shoulder arthroplasty: a cadaveric study.J Shoulder Elbow Surg. 2021; 30: 532-537https://doi.org/10.1016/j.jse.2020.07.008Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar This likely implies that SSN injuries might be more common than currently recognized, and therefore it is an important differential diagnosis to be considered in a diagnostic algorithm for the investigation and management of a patient with a painful rTSA. We propose that the likelihood of SSN injury from baseplate screws can be reduced by the use of preoperative planning software and monitoring the direction of screw insertion in real time with computer-guided navigation systems. This case was reported before the routine adoption of performing glenoid base plate implantation under computer navigation guidance at our center, which has eliminated further instances of this complication (Fig. 6). There have been very few previous reports of SSN irritation by the superior screw of the base plate, which have described varying methods of treatment. Treatment has included exchange with a shorter screw,5Ekelund A.L. Management of painful reverse shoulder arthroplasty.Shoulder Elbow. 2017; 9: 212-222https://doi.org/10.1177/1758573217702333Crossref PubMed Scopus (9) Google Scholar burring of the protruding portion of the screw,9Long J. Liles J. Anakwenze O. Klifto C. Iatrogenic injury to the suprascapular nerve following reverse shoulder arthroplasty: a case report.J Shoulder Elb Arthroplast. 2022; 624715492221103518https://doi.org/10.1177/24715492221103518Crossref Google Scholar,15Wang J. Singh A. Higgins L. Warner J. Suprascapular neuropathy secondary to reverse shoulder arthroplasty: a case report.J Shoulder Elbow Surg. 2010; 19: e5-e8https://doi.org/10.1016/j.jse.2009.10.004Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar or removal of the superior baseplate screw entirely.2Child C. Jaberg L. Fischer J. Welter J. Hess F. Irritation of the suprascapular nerve during screw placement in the glenoid component implantation in reverse total shoulder arthroplasty: a case report.World J Surg Surgical Res. 2022; 5: 1391Google Scholar,8Kahan J.B. Iannotti J. Donohue K. Suprascapular neuropathy from malpositioned baseplate screws in primary reverse shoulder arthroplasty: two case reports.JBJS Case Connect. 2020; 10e20.00096https://doi.org/10.2106/jbjs.cc.20.00096Crossref Google Scholar We consider that removal or exchange of the superior screw will not address the injury to the SSN, including neuroma formation, and risks ongoing pain even after resolving the metalwork impingement on the nerve. Burring of the screw risks leading to the deposition of metal debris in the vicinity of the joint and can subsequently lead to third body wear in the prosthetic articulation. Our described technique of arthroscopic division of the SSN is minimally invasive and addresses the root cause of the postoperative pain. Pain after reverse shoulder arthroplasty (rTSA) is a common complication. Because of the requirement to use screws to secure glenoid baseplates in the vast majority of implant systems, SSN irritation due to malpositioning of these screws is likely to be a more common cause of postoperative pain than is currently recognized. We recommend that this be part of a systematic algorithm for assessing a painful rTSA.
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