Neuropathy of the suprascapular and axillary nerves in rotator cuff arthropathy: a prospective electrodiagnostic study.

PURPOSE: Prevalence of axillary (AN) and/or suprascapular (SSN) neuropathy in rotator cuff tear arthropathy (RCTA) is unknown. We aimed to prospectively evaluate for preoperative neurodiagnostic abnormalities in order to determine their prevalence, location, and influence on reverse shoulder arthroplasty (RSA) outcomes. METHODS: Patients who underwent RSA for RCTA were prospectively included. An electromyography and nerve conduction study were performed pre and post-surgery. Clinical situation: VAS, Relative Constant-Murley Score (rCMS) and ROM over a minimum of two years follow-up. RESULTS: Forty patients met the inclusion criteria; mean follow-up was 28.4 months (SD 4.4). Injuries in RCTA were present in 83.9% (77.4% in AN and 45.2% in SSN). There were no differences on preoperative VAS, ROM, and rCMS between patients with and without preoperative nerve injuries. Four acute postoperative neurological injuries were registered under chronic preoperative injuries. Six months after RSA, 69% of preoperative neuropathies had improved (82.14% chronic injuries and 77.7% disuse injuries). No differences in improvement between disuse and chronic injuries were found, but patients with preoperative neuropathy that had not improved at the postoperative electromyographic study at six months, scored worse on the VAS (1.44 vs 2.66; p .14) and rCMS (91.6 vs 89.04; p .27). CONCLUSIONS: The frequency of axillary and suprascapular neuropathies in RCTA is much higher than expected. Most of these injuries improve after surgery, with almost complete neurophysiological recovery and little functional impact on RSA. However, those patients with preoperative neuropathies and absence of neurophysiological improvement six months after surgery have lower functional results.

Suprascapular nerve injury after reverse total shoulder arthroplasty: correlation with screw out of vault penetration and functional situation: prospective study.

BACKGROUND: Baseplate screws have been suggested as a possible cause of suprascapular neuropathy after reverse total shoulder arthroplasty. This study aims to investigate the association between screw penetration out of the vault, electromyographic study, and the clinical outcomes. METHODS: A total of 31 patients who underwent reverse total shoulder arthroplasty for cuff tear arthropathy were prospectively enrolled. They were followed up for a minimum of 24 months. All patients underwent computed tomography 6 months postoperatively to determine the extraosseous position of the screws (perforation of the second bone cortex and protrusion into the supra- or infraspinatus fossa). Electrodiagnostic evaluation was performed preoperatively and postoperatively to stablish any relation between cortex perforation of the screw and suprascapular nerve (SSN) injury. Clinical outcomes pre- and postoperatively (Constant score, ranges of motion, and visual analog scale) of patients with and without documented injury were recorded. RESULTS: A total of 14 patients (45.2%) had an abnormal preoperative SSN electrodiagnostic study (chronic or disuse injuries), and 6 patients (19.4%) had an abnormal postoperative study (acute injury). Of the 6 patients, 2 cases appeared over the pre-existing lesion and 4 appeared over an intact preoperative nerve, all of them affecting the infraspinatus branch of the SSN. Perforation of the second cortex was detected for 60% of superior screws and 40% of posterior screws. The mean lengths of the superior and posterior screws were 30 and 18.2 mm, respectively. Patients with screw perforation of the second cortex were assessed as having a high risk of nerve injury (40% vs. 9.5%). CONCLUSIONS: Preoperative SSN injuries do not have a significant clinical impact and do not predispose to an acute postoperative SSN lesion. The Constant score and visual analog scale score for patients with acute SSN injuries were not statistically different from those without SSN injury. The extraosseous position of the screw increases the probability of an SSN injury to 31%. This risk is higher with the posterior screw, which leads us to question whether it is really necessary to use it.

Complications after open Latarjet procedure: influence of arm positioning on musculocutaneous and axillary nerve function.

BACKGROUND: Alterations in the anatomical relationships of the musculocutaneous (MCN) and axillary nerves and the influence of arm positioning on these relationships after a Latarjet procedure have been demonstrated in the cadaver, but there are no studies in the literature that establish if there is any neurophysiological repercussion. METHODS: We retrospectively identified 24 patients with a primary or revision open Latarjet procedure. A prospective clinical (Constant-Murley, Rowe and Walch-Duplay and active range of motion), radiographic (with CT), and electrodiagnostic evaluation was made at the most recent follow-up. RESULTS: Nonunion occurred in four patients (22%); there were, as well, one case of partial coracoid reabsorption (5%) and two (11%) with mild glenohumeral osteoarthritis. In the anatomical position, we found no alterations in the musculocutaneous nerve and two cases (11%) in the axillary nerve slight motor unit loss. In the risk position, 11 cases (61%) had neurophysiological involvement (36% had neurophysiological changes in the musculocutaneous nerve and 64% in the axillary nerve). No differences between patients with or without neurophysiologic changes were found: Constant 87/83; Rowe 89/90; Walch-Duplay 84/78; Forward elevation 175º/170º, abduction 165°/175°; external rotation 48°/45°. CONCLUSION: The rate of clinical electromyographic changes in the axillary and MCN in the abducted and externally rotated arm position (risk dislocation position) is higher than in neutral position. Nonunion of the coracoid process must play a role in these neurophysiological changes. Although in the medium-term they don't have clinical impact, further randomized prospective studies with a larger sample size are necessary to determine their true repercussion. LEVEL OF EVIDENCE: Level IV.

Injury to the axillary and suprascapular nerves in rotator cuff arthropathy and after reverse shoulder arthroplasty: a prospective electromyographic analysis.

BACKGROUND: Neurologic pre- and postoperative injuries to the axillary and/or suprascapular nerve (SSN) have a higher incidence than expected and may lead to significantly decreased functional outcomes and increased risk of reverse shoulder arthroplasty (RSA) failure. METHODS: Patients who underwent a RSA for rotator cuff tear arthropathy (RCTA) were included from December 2014 to December 2015. This study focused on the clinical (Constant score), radiographic, and pre- and postoperative electromyographic evaluations at 3 and 6 months. RESULTS: Twenty patients met the inclusion criteria. One was lost to follow-up. Preoperatively, 15 patients showed changes on electromyography (9 SSN and 15 axillary nerve lesions); all of them were chronic and disuse injuries. The mean preoperative relative Constant score (rCS) of all included patients was 39 ± 9 (range, 19-64). At 3 months postsurgery, the prevalence of acute injuries for both nerves was 31.5%. At 6 months postsurgery, 2 axillary nerve injuries and 6 SSN injuries remain unchanged, and the rest improved or normalized. The mean postsurgery rCS of the entire cohort at 6-month follow-up was 78 ± 6.5. Mean postoperative rCS for acute postoperative nerve injury was 71 ± 3 for the axillary nerve and 64 ± 5 for SSN. CONCLUSIONS: Axillary and SSN injuries in RCTA have a much higher incidence than expected. Most of these axillary lesions are transient, with an almost complete recovery seen on electromyography at 6 months and with scarce functional impact. However, SSN lesions appear to behave differently, with poor functional results and having a lower potential for a complete recovery.