Subscapularis Repair in Reverse Total Shoulder Arthroplasty: Differences in Outcomes Based on Preoperative Quality of Subscapularis Tendon.

Purpose: This study examines the influence of preoperative fatty infiltration (FI) of the subscapularis tendon (SBS) on outcomes following reverse total shoulder arthroplasty (rTSA) with SBS repair. Methods: A cohort of 161 rTSA patients with SBS repair, followed for a mean of 45.3 months, was divided into three groups based on FI: Group A (intact upper and lower portions, n = 85), Group B (intact lower portions, n = 44), and Group C (fatty infiltrated in both portions, n = 32). The mean age was 74.5 years (range: 65-95). Results: Preoperative FI displayed significant disparity among the groups: Group A (1.18 ± 0.60), Group B (2.95 ± 0.56), and Group C (4.0 ± 0.00) (p < .001). Group A exhibited a more positive trend in activities of daily living, particularly in toileting ability (81% in Group A, 68% in Group B, and 72% in Group C), although without statistical significance (p = 0.220). Complication rates varied: Group A had seven acromial fractures (8%), three cases of instability (3%), and six instances of scapular notching (7%). Group B experienced four acromial fractures (9%) and four cases of scapular notching (9%), while Group C had only one case of scapular notching (3%) (p = 0.733). Conclusion: In cases characterized by favorable preoperative SBS quality, there was an elevation in functional internal rotation (IR) post-surgery, accompanied by an increased incidence of postoperative complications. Hence, careful consideration is advised when determining the necessity for SBS repair. Level of Evidence: Level III, retrospective comparative study.

Characteristics of subscapularis muscle strain in professional baseball players: a case series.

BACKGROUND: Subscapularis muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the postinjury course of subscapularis muscle strain in professional baseball players. METHODS: Of 191 players (83 fielders and 108 pitchers) who were members of a single Japanese professional baseball team between January 2013 and December 2022, 8 players (4.2%) had subscapularis muscle strain and were enrolled in this study. The diagnosis of muscle strain was made on the basis of shoulder pain and magnetic resonance imaging findings. The incidence of subscapularis muscle strain, the details of the site of the injury, and the time to return to play were examined. RESULTS: Subscapularis muscle strain occurred in 3 (3.6%) of 83 fielders and 5 (4.6%) of 108 pitchers, with no significant difference between fielders and pitchers. All players had injuries on the dominant side. Most injuries were located at the myotendinous junction and in the inferior half of the subscapularis muscle. The mean time to return to play was 55.3 ± 40.0 (range, 7-120) days. At a mean 22.7 months after the injury, there were no reinjured players. CONCLUSION: A subscapularis muscle strain is a rare injury among baseball players, but in players whose shoulder pain cannot be given a definite diagnosis, subscapularis muscle strain should be considered as a possible etiology.

Reproducibility of subscapularis muscle thickness measurement using ultrasound imaging. -Relationship between subscapularis muscle thickness and internal rotation torque of the shoulder joint.

BACKGROUND: Few studies have reported on the morphometry of the subscapularis muscle using ultrasound imaging (USI); and their reproducibility has not been verified. OBJECTIVES: This study aimed to clarify the relative and absolute reproducibility of USI measurements of subscapularis muscle thickness at rest and during isometric contraction as well as the degree of change in muscle thickness caused by the amount of internal rotational torque in the shoulder joint. DESIGN: Two-group repeated-measures study. METHODS: The subjects were the inferior fibers of the subscapularis muscle of 40 healthy adult males. Muscle thickness was measured at rest and at 10%-30% of the maximum isometric internal rotation torque. Intraclass correlation coefficients (ICC) and Brand Altman analysis were used for reproducibility measurement. The degree of change in muscle thickness at each torque was also calculated. RESULTS: Intra- and inter-rater ICCs (ranged from 0.69 to 0.91) were good. A proportional error was observed in intra-rater measurements. Both minimal detectable change 95 (ranged from 2.33 to 6.47) were high. The subscapularis muscle thickness was significantly increased at 10% torque (25.49 ± 3.80 mm), 20% torque (26.07 ± 3.90 mm), and 30% torque (25.96 ± 3.82 mm) as compared to that in resting conditions (24.53 ± 4.46 mm) (p < 0.05). CONCLUSION: The reproducibility and error of the subscapularis muscle thickness measurement using USI used in this study were clarified when repeated measurements were made in the same limb position and under the same probe installation conditions, suggesting that the contraction of the subscapularis muscle can be estimated by muscle thickness measurement.

[Modified Latarjet splitting subscapularis muscle under arthroscopy: an anatomical study based on axillary nerve, glenoid, and subscapularis muscle].

Objective: To testify the spatial relationship between the subscapularis muscle splitting window and the axillary nerve in modified arthroscopic Latarjet procedure, which could provide anatomical basis for the modification of the subscapularis muscle splitting. Methods: A total of 29 adult cadaveric shoulder specimens were dissected layer by layer, and the axillary nerve was finally confirmed to walk on the front surface of the subscapularis muscle. Keeping the shoulder joint in a neutral position, the Kirschner wire was passed through the subscapularis muscle from back to front at the 4 : 00 position of the right glenoid circle (7 : 00 position of the left glenoid circle), and the anterior exit point (point A, the point of splitting subscapularis muscle during Latarjet procedure) was recorded. The vertical and horizontal distances between point A and the axillary nerve were measured respectively. Results: In the neutral position of the shoulder joint, the distance between the point A and the axillary nerve was 27.37 (19.80, 34.55) mm in the horizontal plane and 16.67 (12.85, 20.35) mm in the vertical plane. Conclusion: In the neutral position of the shoulder joint, the possibility of axillary nerve injury will be relatively reduced when radiofrequency is taken from the 4 : 00 position of the right glenoid (7 : 00 position of the left glenoid circle), passing through the subscapularis muscle posteriorly and anteriorly and splitting outward.

The subscapularis muscle: A meta-analysis of its variations, prevalence, and anatomy.

BACKGROUND: The subscapularis (SSC) is the largest rotator cuff muscle and is involved in the medial rotation, abduction, adduction, and anterior stabilization of the shoulder. It is anatomically variable, as is the morphology and prevalence of the accessory SSC (aSSC), a rare muscle slip attached to the SSC. There is no current review investigating the prevalence and morphometrics of the SSC and aSSC. PURPOSE: To investigate the prevalence of the morphological variants of the SSC and aSSC via meta-analysis and review the relevant literature involving cadaveric, magnetic resonance imaging, and ultrasonographic studies. STUDY DESIGN: Meta-analysis. MATERIALS AND METHODS: Literature data reporting the prevalence rates and morphometrics of the SSC and aSSC and their variants were pooled. Literature searches and data analyses were performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Anatomical Quality Assurance guidelines. RESULTS: Forty-six studies, totaling 2166 shoulders, were assessed. The SSC showed an overall length, thickness, cross-sectional area, and volume of 152.2 mm (95% confidence interval, CI, 103.8-200.5 mm), 5.6 mm (95% CI, 4.6-6.6 mm), 18.1 cm2 (95% CI, 14.2-22.0 cm2 ), and 126.9 cm3 (95% CI, 87.2-166.5 cm3 ), respectively. The SSC displayed substantial variations in its origin and insertion points and in the composition of its tendon. The aSSC had an overall pooled prevalence of 24.6% (95% CI, 0.0%-76.9%). CONCLUSIONS: The SSC and aSSC have been implicated in multiple shoulder pathologies, including muscle and tendon ruptures and neurovascular compromise. A better understanding of SSC and aSSC variants when diagnosing and treating their related pathologies will reduce patient morbidity and improve treatment regimens.

Subscapularis minor-does it exist?

INTRODUCTION: It has been well established that the subscapularis is divided in two different parts with a tendinous insertion at its superior two-thirds and a muscular attachment on its inferior third. The objective of this cadaveric study was to follow the muscular insertion of the subscapularis medially in order to determine the origin of this inferior muscle insertion and whether a subscapularis minor can be individualized MATERIALS AND METHODS: Twenty-six shoulders from thirteen fresh-frozen cadaveric specimens (5 males and 8 females; mean age, 74.4 years) were dissected in our anatomy lab. The humeral insertion of the subscapularis was then analyzed, and the inferior muscular part of the insertion was identified. The muscle fibers were followed medially until their scapular origin which was recorded as line drawings and photographs. We measured the dimensions of both the humeral insertion and of the scapular origin of the fibers going to the muscular portion. RESULTS: In all cases, the fibres going to the tendinous portion and those going to the muscular portion of the insertion had a different orientation. The fibres going to the muscular portion of the humeral insertion did not originate from the subscapularis fossa but on the glenoid neck and in a depression at the infero-lateral part of the scapular pillar. The mean length of the superior tendinous portion of the humeral insertion was 3.42 cm (± 0.43 cm); the mean length of the inferior muscular portion of the humeral insertion was 1.88 cm (± 0.80 cm). The mean length of the scapular origin in the depression at the infero-lateral part of the scapular pillar of the fibres going to the muscular portion of the humeral insertion was 3.7 cm (± 0.17 cm). CONCLUSION: The fibres of the subscapularis do not all originate from the subscapularis fossa. An additional origin exists at the inferior part of the glenoid neck and in a depression at the infero-lateral part of the scapular pillar. The fibers which originate at this location all insert on the humerus at the muscular portion of the subscapularis humeral insertion. This portion however does not seem to correspond to the so-called subscapularis minor which has been previously described.

Unknown variant of the accessory subscapularis muscle?

Acting in medial rotation of the arm, the subscapularis (SM) is the most powerful and largest muscle of the rotator cuff. It is morphologically variable, especially in the number of tendons, place of insertion, and number of bellies, and it is sometimes fused with another muscle. An accessory subscapularis muscle (ASM) is among the morphological variations of the SM, but it is a really rare variant. The present case describes a very rare ASM that is divided into proximal tendinous attachment, intermediate fleshy muscular belly and distal tendinous attachment. Its origin is located on the lateral border of the scapula, but some fibers are connected with the muscular part of the SM. Its distal attachment is fused with the capsule of shoulder joint, above the tendinous insertion of the SM. Such an arrangement allows for greater stabilization of the joint. Moreover, there is a possibility that it could be used during treatment of ruptured SM tendons.

The subscapularis tendon: A proposed classification system.

BACKGROUND: The subscapularis muscle originates from the medial two-thirds and from the lower two-thirds of the groove on the subscapular fossa of the scapula and inserts into the lesser tubercle of the humerus. Our initial hypothesis is that it shows little morphological variation. The aim of this study is to demonstrate and classify the morphological variability of the subscapularis muscle. METHODS: Classical anatomical dissection was performed on 64 upper limbs (44 females, 20 males, 30 left and 34 right, fixed in 10% formalin). The mean age "at death" of the cadavers was 75.6 years (range 48-95), and the group comprised equal numbers of female and male adults (Central European population). Upon dissection, the following morphological features were assessed: the number of tendons of the SM, the type of insertion of each tendon of the SM, morphometric measurements of the SM. RESULTS: Four types of morphology (based on number of tendons) were observed in the cadavers. Type I was characterized by a single band. This was the most common type, occurring in 43.7% of all cases. Type II was characterized by a double tendon (superior and inferior); it occurred in 9.4%. Type III had three tendons (superior, middle, and inferior). It was the rarest type (7.8% of cases). Type IV, called "multiband", was the second most common (39.1%) and was divided into five subtypes. CONCLUSIONS: The subscapularis muscle is highly morphologically variable. Knowledge of particular types of insertion is essential for both clinicians (for example orthopedists, physiotherapists) and anatomists.

A very rare case of an accessory subscapularis muscle and its potential clinical significance.

The subscapularis muscle is the largest muscle of the rotator cuff and its main function is internal rotation. It is morphologically variable in both point of origin and insertion. The presence of an accessory subscapularis muscle can lead to brachial plexus neuropathy. This report presents a very rare accessory subscapularis muscle originating from two distinct bands on the subscapularis and teres major muscles. The insertion was divided among four tendons. The fourth tendon is bifurcated. One of these was connected to the tendon of the subscapularis muscle and the other three inserted into the base of the coracoid process of the scapula. This anomalous muscle has the potential to entrap the nerves of the posterior cord such as the axillary, lower subscapular, and thoracodorsal nerves.

Does a subscapularis tear combined with a posterosuperior rotator cuff tear affect postoperative functional outcomes?

BACKGROUND: The subscapularis is biomechanically important for the shoulder. However, few studies have clinically assessed its importance using a comparative design. Our objective was to compare the functional outcomes in patients who underwent isolated repair of posterosuperior rotator cuff tears and those with repair of combined tears involving the subscapularis. METHODS: We performed a retrospective cohort study evaluating patients who underwent arthroscopic full-thickness rotator cuff repair between January 2013 and May 2017. The patients were divided into 2 groups: isolated repair of posterosuperior tears and repair of combined tears involving the subscapularis. The primary outcome was to evaluate the American Shoulder and Elbow Surgeons (ASES) and University of California, Los Angeles (UCLA) scales at 24 months' follow-up. RESULT: A total of 326 patients were evaluated: 194 with isolated posterosuperior repairs and 132 with combined subscapularis repairs. Both groups showed significant improvement with the procedure (P < .001). The ASES score at 24 months showed no significant difference (P = .426) between the group without subscapularis repair (median, 90.0; interquartile range [IQR], 24.8) and the group with subscapularis repair (median, 86.3; IQR, 33.2). Similarly, the UCLA score showed no difference between the groups (median, 33.0 [IQR, 6.0] and 32.5 [IQR, 8.8], respectively; P = .190). The preoperative functional evaluation also showed no significant differences between the groups. CONCLUSION: The functional results did not differ between patients who underwent isolated repair of posterosuperior tears and those with repair of combined tears involving the subscapularis, according to the ASES and UCLA scales at 24 months.

Isokinetic evaluation of the shoulder and elbow after Latarjet procedure.

BACKGROUND/HYPOTHESIS: The Latarjet procedure changes the anatomy of the shoulder, moving the coracoid process distally through an incision in the subscapularis muscle. Some authors have studied the effect of this surgery on shoulder rotator strength. Our hypothesis is that the Latarjet procedure decreases elbow supination and flexion strength. METHODS: A retrospective case series, evaluating patients submitted to the Latarjet procedure between May 2013 and June 2017. Movements of the elbow (supination, pronation, flexion and extension) and shoulder (internal and external rotation) were evaluated bilaterally using a Biodex System 3 isokinetic dynamometer (Biodex Medical Systems, New York) in concentric/concentric mode. RESULTS: We evaluated 20 patients with an average follow-up of 36 months. In the elbow, we observed a 9.1% decrease in supination strength at a speed of 60°/s (p=0.044), without statistical difference at 120°/s (p=0.570). In the shoulder, there was a 13.5% decrease in external rotation strength at 60°/s and 4.5% at 180°/s (p=0.009 and p=0.040, respectively). The other movements did not demonstrate any statistically significant differences. CONCLUSION: After the Latarjet procedure, the supination strength at 60°/s was decreased, as was the external rotation strength of the shoulder at 60°/s and 180°/s. We did not observe any reduction in strength for shoulder flexion or internal shoulder rotation. LEVEL OF EVIDENCE: IV, case series.

Comparison of Functional and Radiological Outcomes of Tears Involving the Subscapularis: Isolated Subscapularis Versus Combined Anterosuperior Rotator Cuff Tears.

BACKGROUND: Few studies have compared the clinical and radiological characteristics and outcomes in isolated subscapularis (SSC) and combined anterosuperior (AS) rotator cuff tears (RCTs). Furthermore, risk factors for retear after SSC repair and the effect of preoperative fatty degeneration require further evaluation. PURPOSE: To compare the functional and radiological outcomes of isolated SSC with combined AS RCTs after arthroscopic repair and to determine the risk factors for SSC retear in these 2 groups. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Data from 30 patients in the isolated SSC group were compared with data from 110 patients in the combined AS group. All patients underwent primary arthroscopic rotator cuff repair between 2010 and 2016. Clinical outcomes were assessed through use of the visual analog scale for pain, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test at a mean follow-up of 26.7 months (range, 24-96 months). SSC tendon integrity was examined via magnetic resonance imaging, computed tomography arthrogram, or ultrasonography at least 1 year after surgery. RESULTS: The isolated SSC group had a greater proportion of males and the patients were younger compared with the combined AS group (both P < .050). The incidence of trauma was high but not significantly different between groups (56.7% vs 40.9%; P = .180). Clinical outcome measures and radiological outcomes in terms of retear were not statistically different between both groups (16.7% vs 8/5%; P = .337). The optimal cutoff values for the risk of SSC tendon retear in both groups were 19-mm retraction and 16-mm superoinferior dimension (P = .048). Unfavorable preoperative fatty degeneration of the SSC muscle (grades 3 and 4) was a significant risk factor for retear (odds ratio, 9.8; P < .001). CONCLUSION: Isolated SSC and combined AS RCTs were comparable except for patient age and sex; both had a high incidence of traumatic history. The current data suggest that the risk factors for retear after SSC repair in RCTs involving the SSC were tear size greater than 19 mm of retraction and unfavorable fatty degeneration (grade 3 or higher) of the SSC muscle.

The grade of preoperative subscapularis muscle atrophy as a prognostic factor for postoperative retears: A double-center retrospective series.

The aim of the study was to investigate whether subscapularis muscle atrophy is a negative prognostic factor leading to increased risk of retears in patients treated with an arthroscopic subscapularis tendon repair. We hypothesized that fatty infiltration of the subscapularis muscle deteriorates the clinical and sonographic outcome of the arthroscopic repair and inhibits reparability of the ruptured tendons. A double- center, multinational, retrospective, blind (in the follow-up) clinical study regarding 32 patients who underwent an arthroscopic subscapularis repair was conducted. Patients were divided into two groups according to the preoparative fatty infiltration grade of subscapularis muscle (group A: grade

All-arthroscopic glenoid reconstruction by iliac crest bone graft transfer does not affect structural integrity and 3-dimensional volume of the subscapularis muscle.

AIM: The subscapularis muscle is an important active stabilizer of the glenohumeral joint. For this radiological study, we investigated if its radiological integrity is affected after arthroscopic glenoid reconstruction. In the technique used, an autologous iliac crest graft is transported through the rotator interval, and the graft is fixed via an antero-inferior portal with compression screws. METHODS: 3 women and 6 men (mean age 31 ± 9 years, min 21, max 46 years) who had a preoperative glenoid deficit of 23% ± 6% (min 13%, max 29%) were included. In a follow-up after an interval of 34 months (min 19, max 50), MRI scans were performed on both shoulders. With ITK-SNAP, a 3D reconstruction software, the volume of the subscapularis muscle in the injured and contralateral shoulder was measured. In addition, signal intensity ratios (PSI) (infraspinatus muscle / cranial subscapularis muscle and infraspinatus muscle / caudal subscapularis muscle) were analyzed and the width of the cranial and caudal portions as well as the length of the subscapularis muscle in the parasagittal plane were determined. RESULTS: The 3D volume showed no difference between operated and healthy shoulders (p = 0.07), neither did PSI ratios (infraspinatus muscle / cranial subscapularis muscle: p = 1.00, infraspinatus muscle / caudal subscapularis muscle: p = 1.00). In the parasagittal plane, length (p = 0.09) and cranial width (p = 0.23) did not differ. However, the width of the lower muscle was increased in injured shoulders (p = 0.02). CONCLUSION: In this cohort, no relevant volume loss could be found after arthroscopic glenoid reconstruction. However, a greater width of the lower muscle portion could be identified in the parasagittal plane as a possible indication of scarring.

A Detailed Analysis of the Blood Supply to the Subscapularis Muscle.

This study aimed to provide a comprehensive description of the arterial supply to the subscapularis (SSC) muscle. This will provide critical information for various surgical procedures. Ten specimens of embalmed Korean cadavers were dissected and subjected to modified Sihler's method to reveal the branching pattern of the arteries surrounding the subscapularis, and its intramuscular blood supply. The SSC muscle was generally supplied by branches from the subclavian artery (suprascapular artery, supraSA; circumflex scapular artery, CxSA; and dorsal scapular artery, dSA) and the axillary artery (subscapular artery, subSA; lateral thoracic artery, LTA; posterior circumflex humeral artery, PCxHA; and a branch of the axillary artery, AAbr). The anterior aspect of the muscle was supplied by the subSA, LTA, CxSA, supraSA, and AAbr. The posterior aspect of the muscle was supplied by the supraSA, PCxHA, and subSA. The dSA was more scarcely distributed than the other arteries. In two cases, the dSA supplied the portion of the muscle near the medial border of the scapular. The anterior side of the muscle tendon was supplied by the CxSA, and its posterior side was supplied by the PCxHA. The subSA can be considered to be the main branch supplying the SSA based on its distribution area of arteries. It was mostly situated within the lower region of the SSC. After distributing to the anterior surface of the SSC, some branches of the subSA reached the posterior surface as perforating branches. Clin. Anat. 32:642-647, 2019. © 2019 Wiley Periodicals, Inc.

Is the subscapularis normal after the open Latarjet procedure? An isokinetic and magnetic resonance imaging evaluation.

BACKGROUND: The Latarjet procedure is considered to be a violation of the subscapularis muscle. This study evaluated the postoperative status of the subscapularis through isokinetic and magnetic resonance imaging analysis after splitting. We hypothesized that compared with a healthy contralateral shoulder, there would be satisfactory recovery of subscapularis strength at the cost of some fatigability and some mild fatty infiltration. MATERIALS AND METHODS: This was a case-control retrospective study of patients who underwent a Latarjet procedure between January 2013 and January 2015. A total of 20 patients were reviewed at 1 year postoperatively. With the patient seated, strength testing of both shoulders was done (concentric, eccentric, and fatigability) with a dynamometer. Trophicity and fatty infiltration were analyzed by magnetic resonance imaging. RESULTS: Strength of the internal rotators (IRs) and external rotators (ERs) of the injured shoulder was significantly lower compared with the healthy shoulder in concentric testing at 180°/s and 60°/s (13% for IR and 20% for E, P < .05) and in eccentric testing at 60°/s (19% for IR and 16% for ER, P < .05). A peak torque ratio (ER/IR) of the operated-on shoulder was maintained. The difference in muscular endurance was significant (P < .001). There was no muscle atrophy and minimal or no fatty infiltration of the subscapularis in any patient. CONCLUSION: At 1 year after the open Latarjet procedure, isokinetic testing showed a combined strength deficit in both internal and external rotation with a conserved muscle balance. Although no significant subscapularis fatty infiltration or atrophy was noted, there was a significant deficit in endurance compared with the healthy shoulder.

Accessory subscapularis muscle - A forgotten variation?

The quadrangular space is a space in the axilla bounded by the inferior margin of the teres minor muscle, the superior margin of the teres major muscle, the lateral margin of the long head of the triceps brachii muscle and the surgical neck of the humerus, medially. The axillary nerve (C5-C6) and the posterior circumflex humeral artery and veins pass through this space in order to supply their territories. The subscapularis muscle is situated into the scapular fossa and inserts itself into the lesser tubercle of the humerus, thus helping stabilize the shoulder joint. A supernumerary muscle known as accessory subscapularis muscle originates from the anterior surface of the muscle and usually inserts itself into the shoulder joint. It is a rare variation with few reports of its existence and incidence. We present a case of the accessory subscapularis muscle in a male cadaver fixated with a 10% formalin solution. The muscle passed anteriorly to the axillary nerve, thus, predisposing an individual to quadrangular space compression syndrome. We perform a review of the literature and address its clinical, anthropological and anatomical significance.

Subscapularis muscle flap for reconstruction of posterior chest wall skeletal defect.

INTRODUCTION: Chest wall skeletal defects are usually closed using muscle flaps or prosthetic materials. Postoperative prosthetic infections are critical complications and often require plastic surgery support. We report a new surgical technique, involving a subscapular muscle flap, for covering posterior chest wall defect. PRESENTATION OF CASE: A 75-year-old man was admitted to our hospital. We performed a right upper lobectomy with posterior chest wall resection between the third and sixth ribs. The resulting chest wall defect was covered with a polytetrafluoroethylene mesh that became infected postoperatively. We removed the infected mesh and used the subscapularis muscle, the nearest muscle to the defect, to cover the chest wall defect. The scapular tip was lifted and the lower half of the muscle was dissected. The free end of the flap was sutured to the stumps of the anterior serratus and rhomboid major muscles. Computed tomography, 1 month later, revealed that the flap was engrafted to the chest wall. DISCUSSION: No previous study has reported the use of a subscapularis muscle flap for chest wall reconstruction. The lower third of the scapula was excised since blood supply to the scapula tip may be reduced after dissection of the subscapularis muscle, and to prevent the scapula tip from falling into the thoracic cavity. CONCLUSION: The use of a subscapularis muscle flap to repair chest wall defect is a simple and safe technique that can be conducted in the same surgical field as the initial reconstruction surgery and does not require plastic surgery support.

Shoulder arthroplasty and its effect on strain in the subscapularis muscle.

BACKGROUND: Increasing the thickness of the prosthetic humeral head on subscapularis strain in patients undergoing total shoulder arthroplasty has not been elucidated. The optimal postoperative rehabilitation for total shoulder arthroplasty that does not place excessive strain on the subscapularis is not known. We hypothesize that the use of expanded non-anatomic humeral heads during shoulder replacement will cause increased tension in the repaired subscapularis. We identified a recommended passive range of motion program without invoking an increase in tension in the repaired subscapularis, and determined the impact of the thickness of the humeral head on subscapularis strain. METHODS: Eight fresh-frozen, forequarter cadaver specimens were obtained. An extended deltopectoral incision was performed and passive range-of-motion exercises with the following motions were evaluated: external rotation, abduction, flexion, and scaption. An optical motion analysis system measured strain in the subscapularis. The same protocol was repeated after performing a subscapularis osteotomy and after placement of an anatomic hemiarthroplasty of three different thicknesses. FINDINGS: For abduction and forward flexion, we observed a trend of decreasing strain of the subscapularis, as the laxity is removed with increasing humeral head component thickness. With the short humeral head, strain was similar to native joint with passive scaption and flexion but not with external rotation or abduction. INTERPRETATION: The passive range of motion that minimizes tension on the subscapularis is forward flexion and scaption. Therefore, passive forward flexion or scaption does not need to be limited, but external rotation should have passive limits and abduction should be avoided.

The role of subscapularis muscle denervation in the pathogenesis of shoulder internal rotation contracture after neonatal brachial plexus palsy: a study in a rat model.

We assessed the role of subscapularis muscle denervation in the development of shoulder internal rotation contracture in neonatal brachial plexus injury. Seventeen newborn rats underwent selective denervation of the subscapular muscle. The rats were evaluated at weekly intervals to measure passive shoulder external rotation. After 4 weeks, the animals were euthanized. The subscapularis thickness was measured using 7.2T MRI axial images. The subscapularis muscle was then studied grossly, and its mass was registered. The fiber area and the area of fibrosis were measured using collagen-I inmunostained muscle sections. Significant progressive decrease in passive shoulder external rotation was noted with a mean loss of 58° at four weeks. A significant decrease in thickness and mass of the subscapularis muscles in the involved shoulders was also found with a mean loss of 69%. Subscapularis muscle fiber size decreased significantly, while the area of fibrosis remained unchanged. Our study shows that subscapularis denervation, per se, could explain shoulder contracture after neonatal brachial plexus injury, though its relevance compared to other pathogenic factors needs further investigation.