Optimising safe margins in shoulder surgeries: a cadaveric study on brachial plexus nerves with anthropometric and movement correlation.

PURPOSE: Shoulder surgeries, vital for diverse pathologies, pose a risk of iatrogenic nerve damage. Existing literature lacks diverse bone landmark-specific nerve position data. The purpose of this study is to address this gap by investigating such relationships. METHOD: This cadaveric study examines axillary, radial and suprascapular nerves' relation with acromion, coracoid and greater tuberosity of the humerus (GT). It also correlates this data with humeral lengths and explores nerve dynamics in relation to arm positions. RESULTS: The mean distance from the axillary nerve to (i) GT was 4.38 cm (range 3.32-5.44, SD 0.53), (ii) acromion was 6.42 cm (range 5.03-7.8, SD 0.694) and (iii) coracoid process was 4.3 cm (range 2.76-5.84, SD 0.769). Abduction brought the nerve closer by 0.36 cm, 0.35 cm and 0.53 cm, respectively. The mean distance from radial nerve to (i) GT was 5.46 cm (range 3.78-7.14, SD 0.839), (ii) acromion was 7.82 cm (range 5.4-10.24, SD 1.21) and (iii) tip of the coracoid process was 6.09 cm (range 4.07-8.11 cm, SD 1.01). The mean distance from the suprascapular nerve to the acromion was 4.2 cm (range 3.1-5.4, SD 0.575). The mean humeral length was noted to be 27.83 cm (range 25.3-30.7, SD 1.13). There was no significant correlation between these distances and humeral lengths. CONCLUSION: It is essential to exercise caution to avoid axillary nerve damage during the abduction manoeuvre, as its distance from the greater tuberosity and tip of the coracoid process has shown a significant reduction. The safe margins, in relation to the length of the humerus and consequently the patient's stature, exhibit no significant variation. In situations where the greater tuberosity (GT) and the border of the acromion are inaccessible due to reasons such as trauma, the tip of the coracoid process can serve as a dependable bone landmark for establishing a secure surgical margin.

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.

Risk of suprascapular nerve injury in open Trillat procedure: an anatomical study.

PURPOSE: The open Trillat Procedure described to treat recurrent shoulder instability, has a renewed interest with the advent of arthroscopy. The suprascapular nerve (SSN) is theoretically at risk during the drilling of the scapula near the spinoglenoid notch. The purpose of this study was to assess the relationship between the screw securing the coracoid transfer and the SSN during open Trillat Procedure and define a safe zone for the SSN. METHODS: In this anatomical study, an open Trillat Procedure was performed on ten shoulders specimens. The coracoid was fixed by a screw after partial osteotomy and antero-posterior drilling of the scapular neck. The SSN was dissected with identification of the screw. We measured the distances SSN-screw (distance 1) and SSN-glenoid rim (distance 2). In axial plane, we measured the angles between the glenoid plane and the screw (α angle) and between the glenoid plane and the SSN (ß angle). RESULTS: The mean distance SSN-screw was 8.8 mm +/-5.4 (0-15). Mean α angle was 11°+/-2.4 (8-15). Mean ß angle was 22°+/-6.7 (12-30). No macroscopic lesion of the SSN was recorded but in 20% (2 cases), the screw was in contact with the nerve. In both cases, the ß angle was measured at 12°. CONCLUSION: During the open Trillat Procedure, the SSN can be injured due to its anatomical location. Placement of the screw should be within 10° of the glenoid plane to minimize the risk of SSN injury and could require the use of a specific guide or arthroscopic-assisted surgery.

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.

Three-dimensional analysis of baseplate screw penetration in reverse total shoulder arthroplasty: risk of iatrogenic suprascapular neuropathy by screw violation.

BACKGROUND: Baseplate screws have been suggested to be a possible cause of suprascapular neuropathy after reverse total shoulder arthroplasty (RTSA). Three-dimensional analyses of screw penetration and confirmation of its clinical impacts are relevant. The study aims to investigate the association between screw penetration and the clinical outcomes. MATERIALS AND METHODS: Eighty-two patients who underwent RTSA for a massive rotator cuff tear, cuff tear arthropathy, or osteoarthritis with rotator cuff tear were retrospectively enrolled. They were followed up for a minimum of 12 months, and all underwent computed tomography at 1 year postoperatively. The lengths of the superior and posterior baseplate screws were documented. Postoperative computed tomography images were subjected to 3-dimensional analysis to determine whether superior or posterior screws penetrated the glenoid vault and the location to which they penetrated, and screw-to-nerve distances were measured to estimate risks of screw nerve violation and iatrogenic suprascapular neuropathy. Patients with any screw <5 mm from the suprascapular nerve were deemed to have a high risk. Clinical outcomes (functional scores, ranges of motion, and isometric strengths) of patients in the high- and lower-risk groups were compared. RESULTS: The mean lengths of the superior and posterior screws were 28 ± 4 mm and 18 ± 3 mm, respectively. Penetration was detected for 13% of superior screws and 64% of posterior screws. Sixty-three percent of penetrating superior screws and 5% of penetrating posterior screws were <5 mm from the suprascapular nerve, and therefore, 12% of patients who received RTSA were assessed to have a high risk of iatrogenic suprascapular neuropathy. However, no significant difference was detected in clinical outcomes between the high- and lower-risk patients after a mean follow-up period of 20 months. CONCLUSION: Twelve percent of patients who received RTSA were assessed to be at high risk of iatrogenic suprascapular neuropathy by baseplate screw penetration. However, the clinical outcomes of RTSA at a minimum follow-up of 1 year were similar in the high- and lower-risk groups.

What Are Practical Surgical Anatomic Landmarks and Distances from Relevant Neurologic Landmarks in Cadavers for the Posterior Approach in Shoulder Arthroplasty?

BACKGROUND: Traditional total shoulder arthroplasty is performed through the deltopectoral approach and includes subscapularis release and repair. Subscapularis nonhealing or dysfunction may leave patients with persistent pain, impairment, and instability. Alternative approaches that spare the subscapularis include rotator interval and posterior shoulder approaches; however, to our knowledge, a cadaveric study describing pertinent surgical anatomy for a posterior shoulder approach regarding shoulder arthroplasty has not been performed. QUESTIONS/PURPOSES: (1) What are the distances from important neurologic structures of the shoulder for arthroplasty through a posterior approach? (2) What surgical landmarks can help identify the internervous interval between the infraspinatus and teres minor? METHODS: Twelve hemitorso cadaver specimens with intact rotator cuffs were dissected to study posterior shoulder anatomy regarding posterior shoulder arthroplasty. The median (range) age of the specimens was 79 years (55 to 92). Six of the 12 specimens were right-hand dominant, and 10 specimens were male. Cadaver height was a median 171 cm (155 to 191) and weight was a median of 68 kg (59 to 125). A posterior deltoid split and internervous approach between the infraspinatus and teres minor were used. A posterior T capsulotomy was performed. The distances to important neurologic structures were measured with an electronic caliper and provided in median (range) distances in millimeters. Although not as meaningful as distance ratios accounting for a specimen's body size, neurologic distances in millimeters are surgically practical and provide intraoperative usefulness. Surgical landmarks that can help identify the infraspinatus and teres minor plane were noted. Practical visual and tactile cues between the infraspinatus and teres minor were identified. Posterior rotator cuff tendon morphologies and widths were recorded. RESULTS: The closest important neurologic structure was the axillary nerve, measuring a median (range) 17 mm (9 to 19) from the inferior glenoid rim while the infraspinatus branch of the suprascapular nerve measured 21 mm (15 to 36) from the posterior glenoid rim. The axillary nerve measured 84 mm (70 to 97) from the posterior tip of the acromion in the deltoid split. Three surgical landmarks were helpful for identifying the plane between the infraspinatus and teres minor in all 12 specimens: (1) identifying the triangular teres minor tendon insertion, (2) medial palpation identifying the low point between the prominent muscle bellies of the infraspinatus and teres minor, and (3) identifying the distinct and prominent teres minor tubercle, which is well localized and palpable. CONCLUSION: A major benefit of the posterior approach for shoulder arthroplasty is subscapularis preservation. Multiple practical surgical cues are consistently present and can help identify the infraspinatus and teres minor interval. We did not find the presence of fat stripes to be helpful. The suprascapular nerve is in proximity to posterior surgical dissection and differs from the deltopectoral approach. This is an important distinction from an anterior approach and requires care with dissection. Future studies are necessary to assess iatrogenic risk to the posterior rotator cuff and external rotation strength. This may entail intraoperative nerve conduction studies of the posterior rotator cuff and clinical studies assessing external rotation strength. CLINICAL RELEVANCE: Studying posterior shoulder anatomy is an initial first step to assessing the feasibility of the posterior approach for anatomic shoulder arthroplasty. Additional studies assessing the degree of glenohumeral exposure and possible iatrogenic posterior rotator cuff injury are necessary. Because of the proximity of neurologic structures, it is recommended that surgeons not perform this technique until sufficient evidence indicates that it is equivalent or superior to standard anterior approach total shoulder arthroplasty. After such evidence is available, proper training will be necessary to ensure safe use of the posterior shoulder approach.

Topography of sensory receptors within the human glenohumeral joint capsule.

BACKGROUND AND HYPOTHESES: Sensory receptors in the joint capsule are critical for maintaining joint stability. However, the distribution of sensory receptors in the glenohumeral joint of the shoulder, including mechanoreceptors and free nerve endings, has not been described yet. This study aimed to describe the distributions of different sensory receptor subtypes in the glenohumeral joint capsule. Our hypotheses were as follows: (1) Sensory receptor subtypes would differ in density but follow a similar distribution pattern, and (2) the anterior capsule would have the highest density of sensory receptors. METHODS: Six glenohumeral joint capsules were harvested from the glenoid to the humeral attachment. The capsule was divided into 4 regions of interest (anterior, posterior, superior, and inferior) and analyzed using modified gold chloride stain. Sensory receptors as well as free nerve endings were identified and counted under a light microscope from sections of each region of interest. The density of each sensory receptor subtype was calculated relative to capsule volume. RESULTS: Sensory receptors were distributed in the glenohumeral joint capsule with free nerve endings. The anterior capsule exhibited the highest median density of all 4 sensory receptors examined, followed by the superior, inferior, and posterior capsules. The median densities of these sensory receptor subtypes also significantly differed (P = .007), with type I (Ruffini corpuscles) receptors having the highest density (2.97 U/cm3), followed by type IV (free nerve endings, 2.25 U/cm3), type II (Pacinian corpuscles, 1.40 U/cm3), and type III (Golgi corpuscles, 0.24 U/cm3) receptors. CONCLUSION: Sensory receptor subtypes are differentially expressed in the glenohumeral joint capsule, primarily type I and IV sensory receptors. The expression of sensory receptors was dominant in the anterior capsule, stressing the important role of proprioception feedback for joint stability. The surgical procedure for shoulder instability should consider the topography of sensory receptors to preserve or restore the proprioception of the shoulder joint.

Sensory innervation of the human shoulder joint: the three bridges to break.

BACKGROUND: Painful shoulders create a substantial socioeconomic burden and significant diagnostic challenge for shoulder surgeons. Consensus with respect to the anatomic location of sensory nerve branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches (ABs) (1) innervating the shoulder joint and (2) the distribution of sensory receptors about its capsule and bursae. MATERIALS AND METHODS: Four electronic databases were queried, between January 1945 and June 2019. Thirty original articles providing a detailed description of the distribution of sensory receptors about the shoulder joint capsule (13) and its ABs (22) were reviewed. RESULTS: The suprascapular, lateral pectoral, axillary, and lower subscapular nerves were found to provide ABs to the shoulder joint. The highest density of nociceptors was found in the subacromial bursa. The highest density of mechanoreceptors was identified within the insertion of the glenohumeral ligaments. The most frequently identified innervation pattern comprised 3 nerve bridges (consisting of ABs from suprascapular, axillary, and lateral pectoral nerves) connecting the trigger and the identified pain generator areas rich in nociceptors. CONCLUSION: Current literature supports the presence of a common sensory innervation pattern for the human shoulder joint. Anatomic studies have demonstrated that the most common parent nerves supplying ABs to the shoulder joint are the suprascapular, lateral pectoral, and axillary nerves. Further studies are needed to assess both the safety and efficacy of selective denervation of the painful shoulders, while limiting the loss of proprioceptive function.

Suprascapular nerve decompression in addition to rotator cuff repair: a prospective, randomized observational trial.

BACKGROUND: Tear and retraction of the supraspinatus (SS) and infraspinatus (IS) musculotendinous units and/or their repair may be associated with traction damage to the suprascapular nerve, potentially responsible for pain or weakness of the rotator cuff (RC). Arthroscopic release of the transverse scapular ligament at the suprascapular notch has been advocated to prevent or treat suprascapular nerve impairment associated with RC retraction and/or repair. The effect of this procedure on preoperative normal nerve function is, however, not well studied.We hypothesize that (1) decompression of the suprascapular nerve without preoperative pathologic neurophysiological findings will not improve clinical or imaging outcome and (2) suprascapular decompression will not measurably change suprascapular nerve function. METHODS: Nineteen consecutive patients with a magnetic resonance arthrography documented RC tear involving SS and IS but normal preoperative electromyography (EMG)/nerve conduction studies of the SS and IS were enrolled in a prospective, controlled trial involving RC repair with or without suprascapular nerve decompression at the suprascapular notch. Nine patients were randomized to undergo, and 10 not to undergo, a decompression of the suprascapular nerve. Patients were assessed clinically (Constant score, mobility, pain, strength, subjective shoulder value), with magnetic resonance imaging and neurophysiology preoperatively and at 3- and 12-month follow-up. RESULTS: There was no clinically relevant difference between the release and the non-release group in any clinical parameter at any time point. At magnetic resonance imaging, there was a slightly greater increase of fatty infiltration of the IS in the release group without any other differences between the 2 groups. Electromyographically, there were no pathologic findings in the non-release group at any time point. Conversely, 3 of the 9 patients of the release group showed pathologic EMG findings at 3 months, of whom 2 had recovered fully and 1 only partially at 12 months. CONCLUSION: In the presence of normal EMG findings, suprascapular nerve release added to arthroscopic RC repair is not associated with any clinical benefit, but with electromyographically documented, postoperative impairment of nerve function in 1 of 3 cases. Suprascapular nerve release does not therefore seem to be justified as an adjunct to RC repair if preoperative EMG findings document normal suprascapular nerve function. Based on these findings, the ongoing prospective randomized trial was terminated.

Ultrasonography-guided anterior approach for axillary nerve blockade: An anatomical study.

Combined ultrasound (US)-guided blockade of the suprascapular and axillary nerves (ANs) has been proposed as an alternative to interscalene blockade for pain control in shoulder joint pathology or postsurgical care. This technique could help avoid respiratory complications and/or almost total upper limb palsy. Nowadays, the AN blockade is mostly performed using an in-plane caudal-to-cephalic approach from the posterior surface of the shoulder, reaching the nerve immediately after it exits the neurovascular quadrangular space (part of the spatium axillare). Despite precluding most respiratory complications, this approach has not made postsurgical pain relief any better than an interscalene blockade, probably because articular branches of the AN are not blocked.Cephalic-to-caudal methylene blue injections were placed in the first segment of the AN of six Thiel-embalmed cadavers using an US-guided anterior approach in order to compare the distribution with that produced by a posterior approach to the contralateral AN in the same cadaver. Another 21 formalin-fixed cadavers were bilaterally dissected to identify the articular branches of the AN.We found a good spread of the dye on the AN and a constant relationship of this nerve with the subscapularis muscle. The dye reached the musculocutaneous nerve, which also contributes to shoulder joint innervation. We describe the anatomical landmarks for an ultrasonography-guided anterior AN blockade and hypothesize that this anterior approach will provide better pain control than the posterior approach owing to complete blocking of the joint nerve. Clin. Anat. 33:488-499, 2020. © 2019 Wiley Periodicals, Inc.

Arthroscopic transosseous rotator cuff repair: how to avoid damaging the axillary nerve-a cadaveric study.

INTRODUCTION: Arthroscopic transosseous rotator cuff repair can be performed with an external guide, although the proximity to the axillary nerve raises safety concerns. The aim of this study is to determine the safety of different drilling angles regarding the axillary nerve. MATERIALS AND METHODS: We performed a bone tunnel in the greater tuberosity in 17 fresh frozen shoulders, using an external guide at four different angles: 40°, 50°, 60°, and 70°. At each angle, we measured the distance between the drill and the axillary nerve, the distance from the acromion to the skin incision point, and the perimeter of the arm at the axilla. RESULTS: The distance to the axillary nerve was safe with the guide at an angle of 40°, 50° and 60°, but not at 70° (p = 0.001). We found significant differences between all four angles (p < 0.05). Regression analysis demonstrated the influence of the guide angle in all measurements assessed (p < 0.001). There was no association between the measurements taken and the axillary perimeter (p > 0.5). CONCLUSIONS: Arthroscopic transosseous rotator cuff repair with an external guide does not pose a risk for the axillary nerve using angles of 60° or less.

Coexistence of a rare case of a suprascapular artery with other vascular abnormalities: case report and potential surgical relevance.

PURPOSE: The suprascapular artery originates in the thyrocervical trunk; however, several variations regarding both the origin and the path have already been described. This article aims to describe a complex and rare variation of the suprascapular artery originating as a branch of the subscapular artery. We described, reviewed the literature, and highlighted the clinical relevance of such variations to the medical practice. METHODS: A routine dissection was performed on a male adult cadaver approximately 60-70 years old, embalmed in formalin 10%. In addition, the diameter of the axillary, subscapular and suprascapular arteries was measured. RESULTS: During the dissection, we identified the suprascapular artery emerging from the medial side of the subscapular artery with a long and tortuous pathway to the supraspinatus fossa, under the superior transverse scapular ligament. Associated with this, three other anatomical variations stand out: the posterior circumflex humeral artery emerging from the subscapular artery, the absence of the anterior circumflex humeral artery, and two pectoral branches emerging from the third part of the axillary artery and from the subscapular artery, respectively. CONCLUSION: Such variations are of great clinical relevance to orthopedists, mastologists, vascular surgeons and other specialties for both surgical approaches and suprascapular neuropathy.

Proximity of the Coracoid Process to the Neurovascular Structures in Various Patient and Shoulder Positions: A Cadaveric Study.

PURPOSE: To examine and compare the distances from the anteromedial aspects of the coracoid base and the coracoid tip to the neurovascular structures in various patient positions. METHODS: The experiment was conducted in 15 fresh-frozen cadavers. We dissected 15 right and 15 left shoulders to measure the distances from the anteromedial aspects of the coracoid base and the coracoid tip to the lateral border of the neurovascular structures in the horizontal, vertical, and closest planes. The measurements were performed with the cadavers in the supine, lateral decubitus, and beach-chair positions. With cadavers in the beach-chair position, we evaluated 5 arm postures (arm at side, 45° of abduction, 90° of abduction, 45° of forward flexion, and 90° of forward flexion). RESULTS: The shortest distance from the coracoid base to the neurovascular structures was found in the beach-chair position with arm at side in the horizontal plane (27.4 ± 4.9 mm) and 90° of abduction in the vertical (21.8 ± 4.2 mm) and closest (19.5 ± 4.2 mm) planes. The distances in each plane were statistically significant compared with the supine and lateral decubitus positions (P < .005). Between the coracoid tip and the neurovascular structures, the shortest distance was found in the beach-chair position with 90° of abduction, with 29.3 ± 7.7 mm, 20.8 ± 4.9 mm, and 18.5 ± 5.1 mm in the horizontal, vertical, and closest planes, respectively. The distances were statistically significant in all planes compared with the supine and lateral decubitus positions (P < .005). CONCLUSIONS: Shoulder surgery in the area of the coracoid process is safe, especially with the patient in the supine position. The distance from the coracoid process to the neurovascular structures was closest in the beach-chair position with 90° of arm abduction. CLINICAL RELEVANCE: This study determined the distances between the coracoid process and the neurovascular structures during surgery around the coracoid process.

Sensory innervation of the subacromial bursa by the distal suprascapular nerve: a new description of its anatomic distribution.

BACKGROUND: Sensory innervation to the shoulder provided by the distal suprascapular nerve (dSSN) remains the subject of debate. The purpose of this study was to establish consensus with respect to the anatomic features of the sensory branches of the dSSN. The relevant hypothesis was that the dSSN would give off 3 sensory branches providing innervation to the posterior glenohumeral (PGH) capsule, the subacromial bursa, in addition to the coracoclavicular and acromioclavicular ligaments. METHODS: The division, course, and distribution of the sensory branches that originated from the dSSN and innervated structures around the shoulder joint were examined macroscopically by dissecting 37 shoulders of 19 fresh-frozen cadavers aged of 83.0 years (range, 74-98 years). RESULTS: The 37 dSSN provided 1 medial subacromial branch (MSAb), 1 lateral subacromial branch (LSAb), and 1 PGH branch (PGHb) to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular (MSAb and LSAb) and coracoclavicular (MSAb) ligaments, as well as the PGH capsule (PGHb). CONCLUSIONS: The dSSN provided 2 subacromial branches and 1 PGHb to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular and coracoclavicular ligaments, as well as the PGH capsule.

Arthroscopic rotator cuff repair with or without suprascapular nerve decompression in posterosuperior massive rotator cuff tears.

PURPOSE: The purpose of this study was to compare clinical outcomes of the arthroscopic rotator cuff repair (ARCR) in posterosuperior massive rotator cuff tears with or without arthroscopic suprascapular nerve (SSN) decompression in terms of arthroscopic release of the transverse scapular ligament. METHODS: Patients with a minimum follow-up of 24 months who underwent complete repair of torn rotator cuff involving a complete full-thickness tear of the supraspinatus and the infraspinatus were retrospectively evaluated. A total of 31 patients were treated with SSN decompression (group 1), and 36 patients were treated without SSN decompression (group 2). The clinical and functional outcomes were evaluated using the University of California, Los Angeles (UCLA) score, active range of motion (flexion and external rotation), and a visual analog scale (VAS) for pain. Repair integrity and fatty infiltration of the repaired cuff were examined by MRI. RESULTS: There was no significant difference between both groups across all measured at final follow-up: UCLA scores were 30.8 in group 1 and 30.8 in group 2 (p = 0.58); VAS scores were 14 mm and 13 mm, respectively (p = 0.35); active flexion angle were 149° and 153°, respectively (p = 0.35); and external rotation angles were 41° and 42°, respectively (p = 0.85). There were no significant differences in the re-tear rate (42% in group 1 and 33% in group 2, P = 0.75) and post-operative fatty infiltration scores of supraspinatus (P = 0.28) and infraspinatus (P = 0.37) in both groups. CONCLUSIONS: The functional outcomes and healing rate did not differ significantly between the groups with or without SSN decompression treated with arthroscopic cuff repair for massive RCT. At the short-term follow-up, SSN decompression was not found to have significantly affected the outcome of ARCR for posterosuperior massive RCT.

An anatomical study of the superior transverse scapular ligament of Jining population.

PURPOSE: The aim of this study was to determine the anatomical variations of the superior transverse scapular ligament (STSL) for better understanding the possible predisposing factors for suprascapular nerve entrapment. METHODS: The study was using fifty 10% formalin solution-fixed human cadaveric shoulders. After dissection of the suprascapular region, the length, medial width, lateral width and middle width of the suprascapular opening were measured for each STSL. RESULTS: The STSL displayed six types as: (1) band-shaped in 11 cases; (2) fan-shaped in 27 cases; (3) triangular-shaped in 5 cases; (4) linear type in 2 cases; (5) bifid in 1 case; (6) absent in 1 case. The ossified type of STSL was found in 3 cases. There were statistically significant differences in the length (P = 0.009), medial width (P = 0.001), lateral width (P = 0.029) of the three types of fan-shaped, band-shaped and triangular-shaped. However, there was no statistical difference in the middle width of the suprascapular opening of the three types (P = 0.340). CONCLUSION: Knowing the morphological features and variations of the STSL is important for better understanding the anatomical conditions, which could be taken into consideration during open suprascapular operations or arthroscopic decompressions.

Clinical outcomes of suprascapular nerve decompression: a systematic review.

BACKGROUND: Suprascapular neuropathy is an uncommon clinical diagnosis. Although there have been a number of case series reporting on this pathologic process, to date there has been no systematic review of these studies. This study aimed to synthesize the literature on suprascapular neuropathy with regard to clinical outcomes. The secondary objective was to detail the diagnosis and treatment of suprascapular neuropathy and any associated complications. METHODS: A systematic review was performed to identify studies that reported the results or clinical outcomes of suprascapular nerve decompression. The searches were performed using MEDLINE through PubMed and Cochrane Database of Systematic Reviews. RESULTS: Twenty-one studies comprising 275 patients and 276 shoulders met inclusion criteria. The mean age was 41.9 years, and mean follow-up was 32.5 months. The most common symptom was deep, posterior shoulder pain (97.8%), with a mean duration of symptoms before decompression of 19.0 months; 94% of patients underwent electrodiagnostic testing before decompression, and 85% of patients had results consistent with suprascapular neuropathy. The most common outcome reported was the visual analog scale score, followed by the Constant-Murley score. The mean postoperative Constant-Murley score obtained was 89% of ideal maximum. Ninety-two percent of athletes were able to return to sport. Only 2 (0.74%) complications were reported in the included studies. CONCLUSIONS: Surgical decompression in the setting of suprascapular neuropathy leads to satisfactory outcomes as evidenced by the patient-reported outcomes and return to sport rate. Furthermore, the rate of complications appears to be low.

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.

Preventing brachial plexus injury during shoulder surgery: a real-time cadaveric study.

BACKGROUND: Brachial plexopathy is not uncommon after shoulder surgery. Although thought to be due to stretch neuropathy, its etiology is poorly understood. This study aimed to identify arm positions and maneuvers that may risk causing brachial plexopathy during shoulder arthroplasty. METHODS: Tensions in the cords of the brachial plexuses of 6 human cadaveric upper limbs were measured using load cells while each limb was placed in different arm positions and while they underwent shoulder hemiarthroplasty and revision reverse arthroplasty. Arthroplasty procedures in 4 specimens were performed with standard limb positioning (unsupported), and 2 specimens were supported from under the elbow (supported). Each cord then underwent biomechanical testing to identify tension corresponding to 10% strain (the stretch neuropathy threshold in animal models). RESULTS: Tensions exceeding 15 N, 11 N, and 9 N in the lateral, medial, and posterior cords, respectively, produced 10% strain. Shoulder abduction >70° and combined external rotation >60° with extension >50° increased medial cord tension above the 10% strain threshold. Medial cord tensions (mean ± standard error of the mean) in unsupported specimens increased over baseline during hemiarthroplasty (sounder insertion [4.7 ± 0.6 N, P = .04], prosthesis impaction [6.1 ± 0.8 N, P = .04], and arthroplasty reduction [5.0 ± 0.7 N, P = .04]) and revision reverse arthroplasty (retractor positioning [7.2 ± 0.8 N, P = .02]). Supported specimens experienced lower tensions than unsupported specimens. CONCLUSIONS: Shoulder abduction >70°, combined external rotation >60° with extension >50°, and downward forces on the humeral shaft may risk causing brachial plexopathy. Retractor placement, sounder insertion, humeral prosthesis impaction, and arthroplasty reduction increase medial cord tensions during shoulder arthroplasty. Supporting the arm from under the elbow protected the brachial plexus in this cadaveric model.

Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control.

Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interaction torques produced during single-joint elbow movements from different elbow initial orientations and over a range of movement speeds. We found that shoulder muscle activity reliably preceded movement onset and elbow agonist activity, and was scaled to compensate for the magnitude of interaction torques arising because of forearm rotation. Our second experiment tested whether elbow muscles compensate for interaction torques introduced by single-joint wrist movements. We found that elbow muscle activity preceded movement onset and wrist agonist muscle activity, and thus the nervous system predicted interaction torques arising because of hand rotation. Our third and fourth experiments tested whether shoulder muscles compensate for interaction torques introduced by different hand orientations during self-initiated elbow movements and to counter mechanical perturbations that caused pure elbow motion. We found that the nervous system predicted the amplitude and direction of interaction torques, appropriately scaling the amplitude of shoulder muscle activity during self-initiated elbow movements and rapid feedback control. Taken together, our results demonstrate that the nervous system robustly accounts for intersegmental dynamics and that the process is similar across the proximal to distal musculature of the arm as well as between feedforward (i.e., self-initiated) and feedback (i.e., reflexive) control.NEW & NOTEWORTHY Intersegmental dynamics complicate the mapping between applied joint torques and the resulting joint motions. We provide evidence that the nervous system robustly predicts these intersegmental limb dynamics across the shoulder, elbow, and wrist joints during reaching and when countering external perturbations.