Prevention and Treatment of Nerve Injuries in Shoulder Arthroplasty

Muscles variations with topographical relationship to the suprascapular notch and its potential arthroscopic feasibility

PURPOSE

This study provides an insight on the extent of muscular variability at the suprascapular notch and elaborates on its anatomical interference in suprascapular nerve arthroscopic decompression procedures.

METHODS

The suprascapular notch was dissected and its muscular topography was observed in 115 cadaveric specimens. High resolution imaging of the suprascapular notch was captured by a handheld digital microscope (Q-scope). The supraspinatus and subscapularis muscles were traced as they course at the suprascapular notch vicinity. The omohyoid muscle attachment onto the suprascapular ligament was measured. A scoping review and meta-analysis were done to investigate the observed rare muscular variants.

RESULTS

In 3.48%, the suprascapular notch anterior surface was fully covered by the subscapularis muscle. The omohyoid muscle inserted onto the suprascapular ligament in 31.25% and extended up to 3/4th of the suprascapular ligament length in 2.61%. Two rare variant muscles were encountered: subclavius posticus muscle and a newly reported "coracoscapularis muscle".

CONCLUSIONS

Four categories of muscles with topographical relationship to the suprascapular notch and its arthroscopic feasibility have been classified: (1) constant muscles not intervening with the suprascapular notch space - supraspinatus muscle; (2) constant muscles with variable positions that can intervene with the suprascapular notch space - subscapularis muscle; (3) constant muscles with variable positions that can intervene with the surgical approach - omohyoid muscle; (4) variable muscles intervening with the suprascapular notch space and surgical approach - subclavius posticus and coracoscapularis muscles. This study elucidates the necessity to assess/secure the omohyoid muscle attachment onto the suprascapular ligament in suprascapular nerve decompression ligamentectomy.

LEVEL OF EVIDENCE

V Basic Science Research.

Preoperative ultrasound mapping of the suprascapular and spinal accessory nerves: A surgeon's guide to precision

BACKGROUND

The aim of the study was to evaluate the accessibility and localization of spinal accessory and suprascapular nerves in the suprascapular region in healthy volunteers using ultrasonography.

METHODS

One hundred healthy volunteers were included and the location of the spinal accessory nerve (SAN) and suprascapular nerve (SSN) was assessed in the right suprascapular region.

FINDINGS

Seventy men and 30 women, (mean age 40.37 years; mean BMI 23.44 kg/m2) participated in the study. Mean distance of SAN from the vertebral spinous process and medial border of the scapula was 3.80 and 0.7 cm, respectively. Mean depth of SAN from the skin was 2.67 cm. The mean distance of SSN from the spine was 7 cm and mean depth of SSN from the skin was 3.28 cm. In overweight and obese individuals, the distance of SAN from the skin and vertebral spinous process and distance of SSN from the vertebral spine increased significantly. According to gender, there was no statistically significant difference in the location of SSN and SAN; however, the distance of SSN from the vertebral spine was significantly increased with increasing age.

INTERPRETATION

The SSN and SAN in the suprascapular region can be consistently and reliably mapped using ultrasound. These data can also help in surface markings of both the nerves, which reduces the operating time and risk of iatrogenic injury.

Early morbidity and mortality after one-stage bilateral shoulder arthroplasty

PURPOSE

One-stage bilateral shoulder arthroplasty has the advantage of requiring a single hospital stay and a single anaesthesia. The topic has been little reported, unlike one stage bilateral hip and knee arthroplasty, which have demonstrated their interest. The aim of the present study was to determine peri- and early post-operative morbidity and mortality after this procedure. The study hypothesis was that peri- and early post-operative morbidity and mortality in one stage bilateral shoulder arthroplasty is low in selected patients and that satisfaction is high.

METHODS

A single-centre retrospective study assessed peri- and early post-operative morbidity and mortality in one stage bilateral shoulder arthroplasty. Twenty-one patients, aged < 80 years, with ASA score ≤ 3, were consecutively operated on between 1999 and 2020. Indications comprised primary osteoarthritis, aseptic osteonecrosis, inflammatory arthritis, massive rotator cuff tear, and dislocation fracture, involving both shoulders.

RESULTS

There were no early deaths. The complication rate was 10% (4/21 cases). No prosthesis dislocation or sepsis was reported. Mean blood loss was 145 ± 40 cc, mean surgery time 164 ± 63 min, and mean hospital stay five ± four days. Only one patient required postoperative transfusion. Functional results at six months showed significantly improved range of motion and good patient satisfaction.

CONCLUSIONS

One-stage bilateral shoulder arthroplasty was feasible in selected patients. Mortality was zero, and morbidity was low. Surgery time was reasonable and required no repositioning. Postoperative home help is indispensable for patient satisfaction during rehabilitation.

Influence of humeral lengthening on clinical outcomes in reverse shoulder arthroplasty

BACKGROUND

Deltoid tensioning secondary to humeral lengthening after reverse shoulder arthroplasty (RSA) is commonly theorized to be crucial to improving range of motion (ROM) but may predispose patients to acromial/scapular spine fractures and neurologic injury. Clinical evidence linking patient outcomes to humeral lengthening is limited. This study assesses the relationship between humeral lengthening and clinical outcomes after RSA.

METHODS

A single institution review of 284 RSAs performed in 265 patients was performed. Humeral lengthening was defined as the difference in the subacromial height preoperatively to postoperatively as measured on Grashey radiographs. The subacromial height was measured as the vertical difference between the most inferolateral aspect of the acromion and the most superior aspect of the greater tuberosity. The relationship between humeral lengthening and clinical outcomes was assessed on a continuous basis. Secondarily, clinical outcomes were assessed using a dichotomous definition of humeral lengthening (≤25 vs. >25mm) based on prior clinical and biomechanical work purporting a correlation with clinical outcomes. Improvement exceeding the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) for ROM and outcome scores after RSA were also compared.

RESULTS

Humeral lengthening demonstrated a nonlinear relationship with postoperative ROM, clinical outcome scores, and shoulder strength and their improvement preoperatively to postoperatively. Furthermore, there were minimal differences in ROM measures, outcome scores, and shoulder strength when stratified using the dichotomous definition of humeral lengthening. No difference in the proportion of patients exceeding the MCID or SCB when stratified by humeral lengthening ≤25 vs. >25mm was found. There was no difference in humeral lengthening in patients with versus without complications.

CONCLUSION

No clear relationship between humeral lengthening and clinical outcomes was identified. The previously purported 25mm threshold for humeral lengthening did not predict improved patient outcomes. Outcomes after RSA are multifactorial; the relationship between humeral lengthening and outcomes is likely confounded by other patient and surgical factors.

LEVEL OF EVIDENCE

IV; Case Series.

Prevalence, management, and outcomes of nerve injury after shoulder arthroplasty: a case-control study and review of the literature

Background

Neurologic injury is a rare and potentially devastating complication of shoulder arthroplasty. Patients typically present with a mixed plexopathy or mononeuropathy, most commonly affecting the axillary and radial nerves. Given the paucity of studies available on the topic, our goal was to elucidate the prevalence of nerve injury after shoulder arthroplasty and to describe the treatment course and outcomes of neurologic injuries.

Methods

This is a retrospective case-control study performed at a single, urban, academic institution. Consecutive patients who underwent anatomic total shoulder arthroplasty (TSA) or reverse shoulder arthroplasty (RSA) by a single surgeon from 2014 to 2020 were reviewed, and patients with a documented nerve injury were identified. A control group of patients without nerve injury were selected in a 2:1 ratio controlling for age and procedure type (TSA vs. RSA; primary vs. revision). Data collected included demographics, comorbidities as per the Charlson Comorbidity Index, radiographic evaluations, surgical and implant details, patient-reported outcome measures, and perioperative complications.

Results

Of 923 patients, 33 (3.6%) sustained an iatrogenic nerve injury: 10 (2.1%) after TSA, 23 (5.0%) after RSA, and 3 (7.8%) after revision arthroplasty. Axillary mononeuropathy was most common (42%), followed by brachial plexopathies (18%). There was no significant difference in age, sex, race, body mass index, and preoperative diagnoses between groups. Patients with nerve injury had fewer comorbidities (Charlson Comorbidity Index <3, 33 vs. 65%, P<.001). Patients with nerve injury had higher rates of cervical spine pathology (15 vs. 6%; P = .15) and increased postoperative lateralization (8.9 mm [7.2] vs. 5.5 mm [7.3]; P<.06). The majority (91%) were managed with observation alone. Three (9%) underwent an additional procedure: carpal tunnel release (1, 3%), ulnar nerve decompression (1, 3%), and ulnar nerve transposition (1, 3%) for peripheral compressive neuropathies. At the final follow-up, 19 (57%) nerves fully recovered, and 14 (43%) showed mild residual sensorimotor dysfunction. The mean time to first sign of recovery and ultimate recovery were 11 (7.2) and 36 (23.5) weeks, respectively. At the final follow-up, patients with nerve injury performed worse on patient-reported outcomes, including visual analog score pain (2.2 vs. 1.0, P<.001), American Shoulder and Elbow Surgeons score (67.8 vs. 84.8, P<.001), and Single Assessment Numeric Evaluation scores (62 vs. 77, P = .009).

Discussion

Nerve injury after shoulder arthroplasty is rare, occurring in 3.6% of our patient population. Axillary mononeuropathy and brachial plexopathies are the most common. Most patients can be managed expectantly with observation and will recover at least partial nerve function, although clinical outcomes remain inferior to those without nerve complication.

Incidence, Risk Factors, Prevention, and Management of Peripheral Nerve Injuries Following Shoulder Arthroplasty

In this article, the authors review the incidence and causes of iatrogenic peripheral nerve injuries following shoulder arthroplasty and provide preventative measures to decrease nerve injury rate and management options. They describe common direct and indirect causes of injury such as laceration and retractor use versus arm positioning and lengthening, respectively. Preventative measures include an understanding of anatomy and high-risk locations in the shoulder, minimizing extreme ranges of arm motion and utilization of intraoperative nerve monitoring. Lastly, the authors review diagnosis and management of neurologic symptoms including how and when to use electrodiagnostic studies, nerve grafts, transfers, or muscle/tendon transfers.

When should reverse total shoulder arthroplasty be considered in glenohumeral joint arthritis?

Anatomical total shoulder arthroplasty (TSA) has been used widely in treatment of glenohumeral osteoarthritis and provides excellent pain relief and functional results. Reverse total shoulder arthroplasty (RSA) was created to treat the complex problem of rotator cuff tear arthropathy. RSA also has been performed for glenohumeral osteoarthritis even in cases where the rotator cuff is preserved and has shown good results comparable with TSA. The indications for RSA are expanding to include tumors of the proximal humerus, revision of hemiarthroplasty to RSA, and revision of failed TSA to RSA. The purposes of this article were to describe comprehensively the conditions under which RSA should be considered in glenohumeral osteoarthritis, to explain its theoretical background, and to review the literature.