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Pectoralis Minor Tenotomy in Shoulder Arthroplasty: A Novel Therapeutic Approach

Contributor

Jaicharan Iyengar MD, Ketan Sharma, MD, and James Friedman, MD
Orthopaedic Surgeon, Shoulder & Elbow Specialist
Stockton Shoulder Institute in Stockton, Calif.

 

Introduction: A Persistent Challenge in Shoulder Arthroplasty

The incidence of post-operative distal neuropathy after shoulder arthroplasty remains significant despite advances in surgical technique and implant design (1). While the true incidence is not known, the rate of post-surgical neurapraxia has been reported as high as 25% in reverse shoulder arthroplasty (2). Moreover, the incidence of sub-clinical nerve lesions documented by EMG is significantly higher and warrants consideration (3,4,5). The cause of this is likely multi-factorial, including pre-existing cervical disease, patient positing, arm traction, retractor placement during surgery and iatrogenic injury during surgical dissection and implant placement. For RSA, in particular, multiple studies have implicated increased lateralization and distalization of the shoulder as significant risk factor for causing mechanical traction on the brachial plexus (6).  While the majority of these cases achieve clinical resolution through observation alone, studies have shown that a significant number of these nerve injuries (around 2-4%) remain persistent at six months and require further intervention.

Scapular Biomechanics and the Problem of Rhythm Disruption

In addition to neuropathic sequalae, implant designs that aim to achieve increased deltoid recruitment through lateralization of humerus relative to the shoulder center of rotation also challenge normal scapulothoracic biomechanics.  Indeed, there remains a problem of alteration to the scapulohumeral rhythm after reverse shoulder arthroplasty that has been well documented by stereoradiographic imaging analysis (7). This alteration has consistently demonstrated the relative increase in scapulo-thoracic motion relative to glenohumeral motion following RSA that facilitates overall functional range of motion (8). However, increases in scapulothoracic motion are highly variable and contribute to inconsistent range of motion and functional outcomes after reverse arthroplasty, despite the overall success of the procedure (9). To date, efforts to facilitate scapular motion after RSA have been focused on implant design factors and post-operative rehabilitation protocols without elucidating the underlying pathologic mechanism.

Reframing Pectoralis Minor Syndrome: The Friedman-Sharma Loop

A recent study by Sharma & Friedman describes the role of the pectoralis minor as both a causative agent of scapular dyskinesis (“The human disharmony loop”) along with a concomitant pattern of upper trunk neuropathy that can be predictably addressed by pectoralis minor tenotomy (10). While “Pectoralis Minor Syndrome” is a historically known clinical entity, it has previously been described mechanistically as a compressive neuropathy of the retro-coracoid space that is a secondary consequence of scapular dyskinesia. The Friedman-Sharma loop model instead suggests a primary etiology of the contracted pectoralis minor that displaces the scapula causing a secondary traction neurapraxia of the upper brachial plexus and offers an insight into both persistent neuropathy and abnormal scapular mechanics.

Surgical Insight: Incorporating Pectoralis Minor Tenotomy in RSA

The implications of this model to shoulder arthroplasty are potentially significant, in that they offer a possible therapeutic strategy to pre-emptively address neuropathic pain and facilitate scapular rhythm after RSA. For these reasons, in my own clinical practice, I have started routinely performing a pectoralis minor tenotomy at the time of primary and revision reverse shoulder arthroplasty. I also do this in select cases of anatomic arthroplasty; particularly in patients who describe a constellation of pre-operative symptoms consistent with distal C4-C6 neuropathy. While mid-term outcomes of this technique are not yet available pending case control analysis, anecdotally I am seeing fewer complaints of post-operative distal neuropathy in short term follow-up. In addition, this mitigates a source of ROM limitation following reverse shoulder arthroplasty by “untethering” the anterior aspect of the scapula. While this is mechanistically sound, I acknowledge that post-operative stereoradiographic analysis is necessary to verify this in clinical practice.

Ongoing Research: Awaiting Evidence from Controlled Trials

To our knowledge, there is one ongoing clinical trial by Wagner et al. at Emory University examining the effects of pectoralis minor tenotomy at the time of RSA in a randomized, controlled study. We eagerly await the results of this trial, particularly with respect to the effect of pectoralis minor tenotomy on short term clinical pain scores, neuropathic symptoms and functional outcomes. Having said that, given the relatively low incidence of long-term nerve dysfunction in shoulder arthroplasty procedures, achieving statistical significance will certainly be a challenge until registry-based studies are able to examine this question with larger data sets.

Conclusion: A Promising Path Forward

While further studies are certainly imperative, in the absence of any observed short-term complications, pectoralis minor tenotomy appears to be a safe and potentially effective mitigation strategy for addressing distal neuropathy and improving scapulohumeral rhythm in reverse shoulder arthroplasty procedures.

 

 

References:

  1. Olson, J. J., O’Donnell, E. A., Dang, K., Huynh, T. M., Lu, A. Z., Kim, C., Haberli, J., & Warner, J. J. P. (2022). Prevalence, management, and outcomes of nerve injury after shoulder arthroplasty: a case-control study and review of the literature. JSES reviews, reports, and techniques, 2(4), 458–463. https://doi.org/10.1016/j.xrrt.2022.04.009
  2. North, D., Hones, K. M., Jenkins, P., Sipavicius, E., Zermeño Salinas, J. L., Hao, K. A., Schoch, B. S., Wright, T. W., Gulotta, L. V., & King, J. J. (2023). How common is nerve injury after reverse shoulder arthroplasty? A systematic review. Journal of shoulder and elbow surgery, 32(4), 872–884. https://doi.org/10.1016/j.jse.2022.10.022
  3. Lopiz, Y., Rodríguez-González, A., Martín-Albarrán, S., Herzog, R., García-Fernández, C., & Marco, F. (2024). Neuropathy of the suprascapular and axillary nerves in rotator cuff arthropathy: a prospective electrodiagnostic study. International orthopaedics, 48(5), 1285–1294. https://doi.org/10.1007/s00264-024-06130-7
  4. Lädermann, A., Lübbeke, A., Mélis, B., Stern, R., Christofilopoulos, P., Bacle, G., & Walch, G. (2011). Prevalence of neurologic lesions after total shoulder arthroplasty. The Journal of bone and joint surgery. American volume, 93(14), 1288–1293. https://doi.org/10.2106/JBJS.J.00369
  5. Dutton, L. K., Barlow, J. D., Loosbrock, M. F., Spinner, R. J., Bishop, A. T., & Shin, A. Y. (2022). Persistent and profound peripheral nerve injuries following reverse total shoulder arthroplasty. Journal of shoulder and elbow surgery, 31(10), 2128–2133. https://doi.org/10.1016/j.jse.2022.03.018
  6. Kim, H. J., Kwon, T. Y., Jeon, Y. S., Kang, S. G., Rhee, Y. G., & Rhee, S. M. (2020). Neurologic deficit after reverse total shoulder arthroplasty: correlation with distalization. Journal of shoulder and elbow surgery, 29(6), 1096–1103. https://doi.org/10.1016/j.jse.2019.11.014
  7. Linderman, S. E., Hall, J. R. L., Johnson, J. E., Caceres, A. P., Hettrich, C. M., & Anderson, D. D. (2022). Return of Scapulohumeral Rhythm in Patients After Reverse Shoulder Arthroplasty: A Midterm Stereoradiographic Imaging Analysis. The Iowa orthopaedic journal, 42(1), 227–237.
  8. Sulkar, H. J., Aliaj, K., Tashjian, R. Z., Chalmers, P. N., Foreman, K. B., & Henninger, H. B. (2022). Reverse Total Shoulder Arthroplasty Alters Humerothoracic, Scapulothoracic, and Glenohumeral Motion During Weighted Scaption. Clinical orthopaedics and related research, 480(11), 2254–2265. https://doi.org/10.1097/CORR.0000000000002321
  9. Gonzalez, F. F., Fonseca, R., Leporace, G., Pitta, R., Giordano, M. N., Chahla, J., & Metsavaht, L. (2021). Three-dimensional kinematic evaluation of scapulohumeral rhythm after reverse shoulder arthroplasty: a systematic review and meta-analysis. JSES reviews, reports, and techniques, 2(1), 8–16. https://doi.org/10.1016/j.xrrt.2021.10.009
  10. Sharma K, Friedman JM. The Human Disharmony Loop: A Case Series Proposing the Unique Role of the Pectoralis Minor in a Unifying Syndrome of Chronic Pain, Neuropathy, and Weakness. Journal of Clinical Medicine. 2025; 14(5):1769. https://doi.org/10.3390/jcm14051769