The teres minor muscle in rotator cuff tendon tears

Rotator cuff tear patterns: MRI appearance and its surgical relevance

A new perspective on rotator cuff anatomy has allowed a better understanding of the patterns of the different rotator cuff tears. It is essential for radiologists to be aware of these different patterns of tears and to understand how they might influence treatment and surgical approach. Our objective is to review the arthroscopy correlated magnetic resonance imaging appearance of the different types of rotator cuff tears based on current anatomical concepts.Critical relevance statement Knowledge of the characteristics of rotator cuff tears improves our communication with the surgeon and can also make it easier for the radiologist to prepare a report that guides therapeutic conduct and serves as a prognosis for the patient.Key points• There is no universally accepted classification for RC tears.• New patterns such as delamination or myotendinous junction tears have been defined.• The most difficult feature to assess in full thickness tears on MRI is the pattern.• Fatty infiltration of the RC tendons is crucial in the prognosis and outcome.• The radiological report is an effective way of communication with the surgeon.

Teres minor denervation and pathologies resulting in shoulder joint instability and rotator cuff tears: A retrospective cross-sectional MRI study

Teres minor denervation (TMD) has gained increasing attention in recent years, particularly with the advent of magnetic resonance imaging (MRI). The potential association between TMD and shoulder instability or rotator cuff tear remains a subject of interest in the orthopedic community. In this retrospective and cross-sectional study, authors aim to investigate the potential association between TMD and shoulder instability or rotator cuff tears. Authors retrospectively analyzed MRI findings from 105 patients with TMD, focusing on rotator cuff pathologies, posterior labrocapsular complex (PLCC) tears, and posteroinferior glenohumeral joint capsule alterations. Authors assessed the association between TMD and rotator cuff and PLCC tears. For the multivariate analysis, partial proportional odds models were constructed for subscapularis (SSC) and SSP tears. Rotator cuff tears were present in 82.9% of subjects, with subscapularis (SSC) tears being the most frequent (77.1%). A significant association was observed between TMD and rotator cuff pathology (P = .002). PLCC tears were found in 82.3% of patients, and humeral position relative to the osseous glenoid was noted in 60% of patients with TMD. A significant association was identified between TMD and shoulder instability or labral/capsular abnormalities (P < .001). More than half of the cases exhibited a long tethering appearance toward the axillary neurovascular bundle on T1-weighted sagittal images. Our findings suggest that TMD is significantly associated with rotator cuff tears and shoulder instability. This study highlights the importance of identifying and treating PLCC tears in patients with TMD to address shoulder instability. Further research is needed to elucidate the role of TMD in the pathogenesis of shoulder instability and rotator cuff pathology.

Revision rotator cuff repair: can a Sugaya III tendon considered to be healed or not

BACKGROUND

Sugaya et al described a classification system to assess postoperative rotator cuff tendon healing. Although Sugaya I and II tendons can be considered as healed and Sugaya type IV and V can be considered as retorn, the exact status of Sugaya III tendons remains unclear. The objective of this study was to evaluate the impact of Sugaya III tendons on postoperative functional scores in a population of patients undergoing revision rotator cuff repair.

METHODS

We retrospectively studied the records of all patients who underwent revision rotator cuff repair in one of 12 different institutions between July 2001 and December 2020. A total of 203 shoulders were included (59% males, mean age: 51 ± 8 years old, mean follow-up 11.5 years [range: 2-28.8 yr]). Fifty-four patients (61% males, mean age 52 ± 6 years old, mean follow-up 14.1 years [range: 10.4-28.8 yr]) had a follow-up ≥10 years (mean 14.1 years [range: 10.4-28.8 yr]) and were included in a long-term follow-up subgroup analysis. Structural integrity of the repaired tendon was evaluated on magnetic resonance imaging at last follow-up. Functional scores, acromiohumeral index (AHI), and progression of fatty infiltration and of osteoarthritis were compared according to Sugaya type.

RESULTS

Mean Constant score and mean strength were significantly higher in Sugaya I and II tendons than in Sugaya III (P = .021 and .003) and Sugaya IV and V tendons (P = .07 and .038), but did not differ between Sugaya III and Sugaya IV and V tendons. Mean Subjective Shoulder Value, pain, AHI were significantly higher and fatty infiltration and progression in the Hamada classification were significantly lower in Sugaya I and II tendons and in Sugaya III than in Sugaya IV and V tendons (P < .05), but did not differ between Sugaya I and II and Sugaya III tendons. Similar characteristics could also be observed in the long-term follow-up subgroup.

CONCLUSION

Sugaya III tendons after revision rotator cuff repair do not allow restoration of strength thereby impacting the Constant score. However, there seems to be a protective effect of Sugaya III tendons with regard to pain, progression of proximal migration of the humeral head, osteoarthritis, and fatty infiltration, which seems to last at long-term follow-up.

Long-term results of revision rotator cuff repair for failed cuff repair: a minimum 10-year follow-up study

HYPOTHESIS

Rotator cuff repair remains associated with high retear rates, which range from 13% to 79%. The objective of this study was to evaluate the long-term clinical and structural results after revision rotator cuff repair at a minimum 10-year follow-up.

METHODS

We retrospectively studied the records of all patients who underwent revision rotator cuff repair in 3 different institutions between July 2001 and December 2007 with a minimum 10-year follow-up. A total of 54 patients (61% males, mean age 52 ± 6 years old) met the inclusion criteria. Outcome measures included pain (visual analog scale [VAS]), range of motion (ROM), Subjective Shoulder Value (SSV), and the Constant score. Superior migration, osteoarthritis, and acromiohumeral interval (AHI) were assessed on standard radiographs. Fatty infiltration and structural integrity of the repaired tendon were evaluated on magnetic resonance imaging or computed tomographic arthrogram.

RESULTS

At a mean 14.1 years (10.4-20.5), range of motion did not progress significantly in elevation and internal rotation between pre- and postoperation (158° [range, 100°-180°] to 164° [range, 60°-180°], P = .33, and L3 [range, sacrum-T12] to T12 [range, buttocks-T7], P = .34, respectively) and decreased in active external rotation from 45° (range, 10°-80°) to 39° (range, 10°-80°) (P = .02). However, VAS, SSV, and Constant score were all significantly improved at last follow-up (P < .001). AHI decreased significantly (P = .002) from 10 mm (7-14 mm) to 8 mm (0-12 mm). Two percent of the supraspinatus/infraspinatus tendons were Sugaya 1, 24% were Sugaya 2, 35% were Sugaya 3, 12% were Sugaya 4, and 27% were Sugaya 5. Goutallier score progressed for all muscles, but this did not reach significance and mean Goutallier remained <2 for all 4 muscles at last follow-up. Hamada score progressed from 0% >grade 2 preoperatively to 6% >grade 2 at last follow-up.

CONCLUSION

Revision rotator cuff repair provides significant pain relief and improvement in functional scores at long-term follow-up. The mild progression of fatty infiltration, AHI, and Hamada score suggests that despite high retear rates (39% of stage 4 and 5 in the Sugaya classification), revision repair could possibly have a protective role on the evolution toward cuff tear arthropathy.

[Lesions of the rotator cuff and biceps tendon]

CLINICAL/METHODOLOGICAL PROBLEM

The rotator cuff is a complex anatomical structure and the integrity is pivotal for the shoulder functionality. The pathologies are often multifactorial, resulting from degenerative, vascular, traumatic and mechanical factors.

RADIOLOGICAL STANDARD PROCEDURES

Radiography, ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) form the pillars of radiological diagnostics. Each modality has specific advantages and limitations in the visualization and assessment of pathologies of the rotator cuff and biceps tendon.

METHODOLOGICAL INNOVATIONS

The MR arthrography offers additional insights in unclear cases by enhancing the differentiation between complete and partial tears.

PERFORMANCE

The MRI provides detailed information on tendon quality and associated damages, such as muscle atrophy and fat infiltration, making it the preferred method. The use of MR arthrography can identify defects through increased intra-articular pressure or contrast medium leakage.

EVALUATION

Muscle damage, as induced by edema in acute injuries or fatty degeneration in chronic conditions, can be evaluated using imaging techniques. Special attention is warranted for the infraspinatus, subscapularis and teres minor muscles due to their unique injury patterns and prevalences.

Effect of subscapularis repair on joint contact forces based on degree of posterior-superior rotator cuff tear severity in reverse shoulder arthroplasty

Massive irreparable rotator cuff tears (RCTs) affect the clinical outcomes of reverse shoulder arthroplasty (RSA). However, the effects of subscapularis repair on the outcomes of RSA, based on the degree of posterior-superior RCTs, are unclear. This study aimed to examine the effect of subscapularis repair on three-dimensional joint contact forces (JCFs) based on the degree of posterior-superior RCT severity in RSA. Ten human in vivo experimental data were used as input to the musculoskeletal model. A six-degrees-of-freedom (DOF) anatomical shoulder model was developed and validated against three-dimensional JCFs. The 6-DOF musculoskeletal shoulder model of RSA was then developed by importing the reverse shoulder implant into the validated anatomical shoulder model. Based on the various types of posterior-superior RCT severity, inverse dynamic simulations of subscapularis-torn and subscapularis-repaired models of RSA were performed: from isolated supraspinatus tears to partial or massive tears of the infraspinatus and teres minor. The intact rotator cuff model of RSA was also simulated for comparison with the different types of models. Our results showed that the more posterior-superior RCTs progressed in RSA, the more superior JCFs were observed at 90°, 105°, and 120° abduction in the subscapularis-torn model. However, subscapularis repair decreased the superior JCF at those angles sufficiently. In addition, the teres minor muscle-tendon force increased as infraspinatus bundle tears progressed in both the subscapularis-torn and -repaired models, in order to compensate for the reduced force during abduction. However, the teres minor muscle-tendon force was not as high as that of the infraspinatus muscle-tendon, which could result in muscle force imbalance between repaired subscapularis and teres minor. Therefore, our results suggest that repairing the subscapularis and the repairable infraspinatus during RSA can improve glenohumeral joint stability in the superior-inferior direction by restoring muscle force balance between the anterior cuff (i.e., subscapularis) and posterior cuff (i.e., infraspinatus and teres minor). The findings of this study can help clinician decide whether to repair the rotator cuff during RSA to enhance joint stability.

Allograft-enhanced latissimus dorsi transfer is better than the conventional technique for irreparable posterosuperior rotator cuff tears. A retrospective matched cohort

PURPOSE

Latissimus dorsi tendon (LDT) transfer (LDTT) to the greater tuberosity to treat irreparable posterosuperior rotator cuff tears (RCTs) in young active patients has been shown to have up to 36% of clinical failures, most of them happening because of either deltoid origin disruption or post-operative transfer rupture from the greater tuberosity. In an attempt to simultaneously prevent both complications, a modified technique includes the following adaptations to the original technique: reinforcement and augmentation of the LDT with a tendinous allograft, enabling the use of a single deltopectoral approach. The aim of this study is to compare mid-term outcomes of the traditional LDTT technique with this modified transfer.

METHODS

Retrospective cohort study comparing two groups who underwent either the traditional (group 1; n = 19) or the modified technique (group 2; n = 27). Group homogenization was assured by statistical comparison of 24 baseline independent variables. The outcome variables were the gains to active shoulder range of motions (ROM) and UCLA scores (and all its subscores, independently), at a minimum follow-up of two years. A p value < .05 was considered to be statistically significant.

RESULTS

At a mean follow-up of 25 months, both groups have shown improvements to most variables. However, group two (modified technique) achieved greater improvements to UCLA score (p = .009), active external rotation (p = .006) and internal rotation (p = .008).

CONCLUSION

At mid-term follow-up, improvements to outcomes of the modified (single approach, allograft-enhanced) latissimus dorsi transfer were greater than those of the original technique.

Teres Minor Muscle Atrophy: Anatomy, Patterns, and Clinical Manifestations

➢

Isolated teres minor atrophy has a reported incidence in the literature of 3% to 6.2%.

➢

There are 2 distinct muscular bundles of the teres minor that have varying degrees of atrophy. Fatty degeneration of the medial-dorsal component exceeds that of the lateral-ventral component in most cases.

➢

A healthy and intact teres minor muscle is of functional importance in the setting of a complete infraspinatus tear because it becomes the only external rotator of the shoulder joint.

➢

Clinical and functional outcomes after rotator cuff repair and reverse shoulder arthroplasty for patients with teres minor atrophy in the setting of a rotator cuff tear are still controversial.

Incidence of Teres Minor Muscle Atrophy in Young and Middle-aged Populations

Background

Teres minor atrophy can be seen in shoulders both with and without a rotator cuff tear, even among the young population. The purpose of this study was to retrospectively investigate the incidence of teres minor atrophy in young and middle-aged patients with or without a rotator cuff tear.

Methods

Patient records were reviewed to identify 10-39-year-old patients (Group Y) and 60-69-year-old patients (Group O) who underwent MRI because of shoulder disorders. The exclusion criteria were as follows: (1) prior surgeries, (2) neurological disorders in the cervical spines or shoulder girdle, (3) global atrophy of all four cuff muscles without a rotator cuff tear, (4) acute trauma, and (5) poor image quality due to artifacts. An experienced shoulder surgeon evaluated teres minor atrophy on T1-weighted oblique sagittal images. Statistical analysis was performed using the chi-square test for comparison of Groups Y and O.

Results

Group Y consisted of 528 shoulders in 520 patients, including 406 males and 114 females with a mean age of 26 years. Group O consisted of 884 shoulders in 837 patients, including 394 males and 443 females with a mean age of 65 years. Rotator cuff tears were seen in 33 shoulders (6.3 %) in Group Y, and 411 shoulders (46.5%) in Group O. Teres minor atrophy was more present in Group O (59 shoulders [6.7%]) than Group Y (11 shoulders [2.1%], P < .001). Among shoulders with teres minor atrophy, the incidence of intact cuff tended to be higher in Group Y than O (7 shoulders [64%] and 21 shoulders [36%], P = .08). However, the ratio of the intact cuff to the number of patients in each group was not significantly different (Group Y, 7 of 528 [1.3%]; Group O, 21 of 884 [2.3%]). Teres minor muscle atrophy tended to be more common in athletes than nonathletes in Group Y, although the difference was not significant (P = .057).

Conclusion

The incidence of teres minor atrophy was significantly higher in middle-aged patients than young patients. Middle-aged patients with teres minor atrophy were more associated with rotator cuff tears. The common cause of teres minor atrophy may be rotator cuff tears. Teres minor atrophy in young patients might be associated with sports-related factors such as infraspinatus hypertrophy or axillary nerve injury.

Inter-rater agreement of rotator cuff tendon and muscle magnetic resonance imaging parameters evaluated preoperatively and during the first postoperative year following rotator cuff repair

BACKGROUND

Magnetic resonance imaging (MRI) is standard of care for rotator cuff evaluation, with clinical interpretation usually limited to qualitative judgments. The reliability of MRI-based measurements and scoring systems has been evaluated only preoperatively or ≥6 months following rotator cuff repair, when repairs are in the later stages of healing. This study describes the MRI assessments and inter-rater agreement of various rotator cuff tendon and muscle parameters evaluated preoperatively and 4 times during the first postoperative year.

METHODS

Two musculoskeletal radiologists independently assessed MRI scans of 42 patients preoperatively and 3, 12, 26, and 52 weeks after rotator cuff repair. Using standardized reading rules, readers assessed tendon integrity (5-point Sugaya classification), tear dimensions, muscle fat (5-point Goutallier classification) and atrophy (4-point Warner classification), muscle cross-sectional areas, and myotendinous junction distance. Raw exact agreement proportions, κ statistics, and correlation coefficients were used to quantify inter-rater agreement.

RESULTS

Readers showed moderate to substantial above-chance agreement in scoring rotator cuff tendon integrity and supraspinatus muscle atrophy and good to excellent agreement on tear dimensions and muscle cross-sectional areas but only fair to moderate agreement for fatty infiltration and myotendinous junction distance. Only fatty infiltration grades evidenced observer bias. Inter-rater agreement did not appear time dependent.

CONCLUSION

By use of defined reading rules in a research setting, MRI evaluations of rotator cuff tendon integrity, tear dimensions, muscle atrophy, and cross-sectional areas have reasonable reliability at all time points in the first postoperative year. However, the presence of clinically significant disagreements, even in such favorable circumstances, indicates the need for improved imaging tools for precise rotator cuff evaluation.

Teres minor muscle hypertrophy is a negative predictor of outcomes after reverse total shoulder arthroplasty: an evaluation of preoperative magnetic resonance imaging and postoperative implant position

BACKGROUND

Predictors of outcomes after reverse total shoulder arthroplasty (rTSA) remain unclear. The purpose of this study was to analyze the impact of preoperative muscle quality and postoperative implant positioning on patient-reported outcomes following rTSA.

METHODS

We evaluated 88 shoulders treated with rTSA in which preoperative magnetic resonance imaging was available. Preoperative muscle quality was evaluated, including fatty infiltration, rotator cuff muscle volume, and total tear size. Postoperative implant position was determined radiographically. The correlation between imaging parameters and the 2-year postoperative American Shoulder and Elbow Surgeons (ASES) score was examined. Multivariate analyses were performed to adjust for confounding factors including patient demographic characteristics and implant position.

RESULTS

Univariate analysis showed that the ASES score was significantly lower in patients with teres minor muscle hypertrophy relative to those with normal muscle (73.3 ± 22.8 vs. 84.2 ± 16.9, P = .02). The functional subscore was significantly lower in patients with grade 2 fatty infiltration of the deltoid muscle relative to those with grade 0 fatty infiltration (26.1 ± 14.6 vs. 34.8 ± 11.6, P = .03). Older age was associated with a higher pain subscore (ρ = 0.32, P = .002). Multivariate analysis demonstrated that teres minor muscle hypertrophy remained a significant independent predictor of the ASES score (β coefficient = 91.3, P = .03).

CONCLUSION

Teres minor muscle hypertrophy is an independent negative predictor of patient-reported outcomes after rTSA.

A low teres minor index of trophicity negatively impacts the functional outcomes of reverse shoulder arthroplasty

INTRODUCTION

The teres minor (TM) participates in active external rotation (ER) after reverse shoulder arthroplasty (RSA). The TM index of trophicity (T2/G) measured on CT scan is a predictor of poor results in patients who have irreparable rotator cuff tears. The aim of this study was to evaluate how T2/G impacts the functional outcomes of RSA in the context of massive rotator cuff tears. We hypothesized that a T2/G less than 0.75 is a predictor of worse functional outcomes.

MATERIALS AND METHODS

This study involved 32 shoulders in 26 patients (mean age 71 years) who underwent RSA for cuff tear arthropathy and had a minimum follow-up of 1 year (mean 3 years). T2/G is the ratio between T2 (TM thickness) and G (maximum glenoid cavity thickness) on preoperative axial CT slices. Clinical examination at the final assessment involved determining the Constant score, the shoulder joint's range of motion and the Subjective Shoulder Value (SSV).

RESULTS

Eight shoulders had a T2/G of less than 0.75 (group 1) while 24 shoulders had an index above 0.75 (group 2). These two groups were similar preoperatively. The Constant-Murley score in group 1 was significantly lower than in group 2 (50.2 points versus 59.7 points, p<0.05). Group 1 had a postoperative improvement of 1̊ in their ER with elbow at side while group 2 had a 16.5̊ improvement (p=0.002). Group 1 had a postoperative loss of 6.3̊ in their ER in 90̊ abduction while group 2 had a 21.7̊ improvement (p=0.001). The SSV at the final assessment was 69% in group 1 versus 79% in group 2 (p=0.094).

CONCLUSION

Having a TM index of trophicity below 0.75 is a negative predictor of clinical outcomes due to lack of ER after RSA.

LEVEL OF EVIDENCE

IV.

Three-dimensional kinematic features in large and massive rotator cuff tears with pseudoparesis

BACKGROUND

Although massive rotator cuff tears occasionally lead to severe impairment of shoulder function, the criteria for losing the ability to elevate the arm are unclear. This study aimed to analyze the features of both tear size and 3-dimensional (3D) shoulder kinematics that correspond to the loss of the ability to elevate the arm in patients with large and massive rotator cuff tears.

METHODS

We prospectively enrolled patients with rotator cuff tears, including the supraspinatus and more than half of the subscapularis or more than two-thirds of the infraspinatus, without severe pain. A total of 13 patients (15 shoulders) were divided into 2 groups: 9 shoulders in the pseudoparesis (P) group and 6 shoulders in the non-pseudoparesis (NP) group. Fluoroscopic images were collected during active scapular-plane elevation, and 3D shoulder kinematics was analyzed using 2-dimensional-3D registration techniques. The radiographic findings and 3D kinematic results were compared between the groups. The correlation between tear size and 3D kinematics was also investigated.

RESULTS

The most superior position of the humeral head center was significantly higher in the P group (6.7 ± 3.0 mm in P group vs. 3.6 ± 1.3 mm in NP group, P = .0321). Superior migration, which was defined as the most superior position > 5 mm, was significantly more frequent in the P group (7 shoulders and 1 shoulder in the P and NP groups, respectively; P = .0201). Thoracohumeral external rotation was significantly smaller in the P group (16° ± 31° in P group vs. 91° ± 21° in NP group, P < .0001). The total tear size and the tear sizes of the anterior and posterior rotator cuffs were significantly correlated with the superior (r = 0.68, P = .0056), anterior (r = 0.68, P = .0058), and posterior (r = -0.80, P = .0004) positions of the humeral head center. The tear size of the posterior rotator cuff also tended to be correlated with glenohumeral external rotation (r = -0.48, P = .0719).

CONCLUSION

Anterior and posterior rotator cuff tears cause significant superior and anteroposterior translations of the humeral head, and posterior cuff tears may lead to loss of glenohumeral external rotation. With these abnormal kinematics, superior migration and loss of thoracohumeral external rotation were identified as features of pseudoparesis.

Electromyography activity of the teres minor muscle with varying positions of horizontal abduction in the quadruped position

Background

The teres minor (TMi) muscle exposed relatively high activity during the acceleration and deceleration phases of the throwing motion, compared with the infraspinatus muscle. However, few studies have identified TMi muscle activity in intervention exercises. The purpose of this study was to investigate TMi muscle activities in different horizontal adduction positions in the quadruped horizontal abduction exercise. This study hypothesized that TMi muscle activity would differ in response to resistance application across different horizontal adduction positions.

Materials and methods

Nineteen collegiate baseball players volunteered their participation. Raw electromyography activity of the TMi muscle along with 7 different muscles attached to the scapula on the dominant-side were collected, and normalized by each of the corresponding maximum voluntary isometric contractions. All subjects performed manual isometric resistance horizontal abduction exercises at 90° and 135° of abduction with 3 horizontal adduction angles in the quadruped position: 1) coronal, 2) scapular, and 3) sagittal plane. Electromyography data were also collected from rhythmical concentric contraction of horizontal abduction at 90° of abduction in the quadruped position.

Results

TMi muscle activity was significantly greater with the arm positioned in the coronal plane than that of the scapular and sagittal planes (41, 26, and 17% maximum voluntary isometric contraction, respectively) (P < .05).

Conclusion

The present study demonstrated that TMi muscle activity varied depending on horizontal adduction positions.

How common is fatty infiltration of the teres minor in patients with shoulder pain? A review of 7,367 consecutive MRI scans

Purpose

The teres minor is particularly important for activities that require external rotation in abduction in the settings of both rotator cuff tears and reverse shoulder arthroplasty. This study sought to assess the incidence of teres minor fatty infiltration in a large cohort of consecutive patients evaluated with shoulder MRI for shoulder pain and to identify all associated pathologies in an effort to determine the various potential etiologies of teres minor involvement.

Methods

A retrospective review of 7,376 non-contrast shoulder MRI studies performed between 2010 and 2015 were specifically evaluated for teres minor fatty infiltration. Studies were reviewed by two fellowship trained musculoskeletal radiologists. Muscle atrophy was graded on a 3-point scale according to Fuchs and Gerber. The remaining rotator cuff tendons and muscles, biceps tendon, labrum, and joint surfaces were assessed on MRI as well.

Results

In this series, 209 (2.8%) shoulders were noted to have fatty infiltration of the teres minor. The rate of isolated fatty infiltration of the teres minor was 0.4%. Concomitant deltoid muscle atrophy was common, and occurred in 68% of the shoulders with fatty infiltration of the teres minor. Tearing of the teres minor tendon was extremely rare.

Conclusion

Fatty infiltration of the teres minor can occur in isolation, be associated with deltoid muscle atrophy only, or occur in the setting of rotator cuff full tears. Thus, fatty infiltration of the teres minor may be related to a neurologic process or disuse. Further long term longitudinal studies are necessary to be elucidate the etiologies.

Level of Evidence

Level IV.

SECEC Grammont Award 2017: the prejudicial effect of greater tuberosity osteotomy or excision in reverse shoulder arthroplasty for fracture sequelae

HYPOTHESIS

The aim was to evaluate risk factors for complications, revision, and mid- to long-term outcomes after reverse shoulder arthroplasty (RSA) implanted for proximal humeral fracture sequelae (PHFS).

METHODS

The radiographs of 98 patients (mean age, 68 years) who underwent RSA for the treatment of PHFS were reviewed at a minimum 5-year follow-up. PHFS were divided into 4 types according to the Boileau classification: type 1 (46 cases), type 2 (6 cases), type 3 (12 cases), and type 4 (34 cases). The tuberosities underwent osteotomy in 28 cases and excision in 12 (all type 3 or 4 PHFS). The mean follow-up period was 8.4 years (range, 5-14 years).

RESULTS

The functional results and rate of RSA survival without revision (85% vs. 100% at 10 years, P = .007) were significantly lower for types 3 and 4 vs. types 1 and 2. Overall, our findings showed that RSA for PHFS is not the panacea that surgeons once believed: At a mean follow-up of 8.5 years (range, 5-14 years), 59% of the patients in our series had fair or poor results. Patients who underwent tuberosity osteotomy or excision had lower functional results (adjusted Constant score, 69% vs. 88%; P < .001), more postoperative complications (32% vs. 9%, P = .003), and a higher revision rate (15% vs. 2%, P = .017). Patients who underwent tuberosity osteotomy or excision at the time of RSA were at risk of postoperative prosthetic instability and humeral stem loosening. The absence of the greater tuberosity at last radiographic follow-up was predictive of higher rates of complications and revisions, as well as a poorer final outcome. Previous fracture fixation was associated with a higher rate of complete tuberosity resorption (56% vs. 33%, P = .026) and with higher rates of postoperative complications (27% vs. 13%, P = .099) and reinterventions (17% vs. 2%, P = .018).

CONCLUSION

The functional results and rates of complications and revision depend on the type of fracture sequelae and tuberosity management. Patients with more severe (type 3 and 4) fracture sequelae who undergo tuberosity osteotomy or excision are at risk of having a poorer functional result and higher rates of complications and revision with lower survival. Previous fracture fixation is also a prejudicial factor.

Modified L'Episcopo tendon transfer for isolated loss of active external rotation

BACKGROUND

Patients with isolated loss of active external rotation (ILER) but preserved active forward elevation have recently been identified as a rare and distinct clinical entity. The modified L'Episcopo procedure attempts to restore horizontal muscle balance and restore active external rotation.

METHODS

A retrospective study was performed for all patients with ILER and preserved forward elevation with Hamada stage ≤2 changes undergoing the modified L'Episcopo tendon transfer. Preoperative rotator cuff fatty infiltration and morphology was reported. Clinical, radiographic, and functional outcomes were recorded preoperatively and compared to postoperative outcomes at a minimum of 24 months' follow-up.

RESULTS

Nine patients (8 male, 1 female) with a mean age of 58.4 years (range, 51-67 years) were evaluated at a mean follow-up of 64.3 months (range, 24-126 months). Significant improvement was demonstrated in active external rotation with the arm at the side (mean increase of 47°; range, 30°-60°, P = .004) and at 90° abduction (mean increase of 41°; range, 20°-70°, P = .004). The mean Constant score and pain score significantly improved at final follow-up (P = .004). All patients were either very satisfied or satisfied, with a mean subjective shoulder value of 74% (range, 60%-99%).

CONCLUSION

In appropriately selected patients with ILER and preserved active forward elevation, the modified L'Episcopo procedure can restore horizontal muscle balance and produce significant improvements in active external rotation, Constant score, and pain.

Comparison of shoulder muscle strength, cross-sectional area, acromiohumeral distance, and thickness of the supraspinatus tendon between symptomatic and asymptomatic patients with rotator cuff tears

BACKGROUND

The purpose of this study was to demonstrate the differences in shoulder muscle strength, cross-sectional area of the rotator cuff muscles, acromiohumeral distance, and supraspinatus tendon thickness between symptomatic and asymptomatic patients with rotator cuff tears.

METHODS

Thirty-two symptomatic patients and 23 asymptomatic patients with rotator cuff tears participated in this study. Data of the patients with any type of tear and supraspinatus tear were analyzed. We evaluated the isometric torque, cross-sectional area of the rotator cuff muscles, supraspinatus tendon thickness, acromiohumeral distance, range of motion, and Western Ontario Rotator Cuff Index.

RESULTS

Asymptomatic patients showed greater isometric torque of shoulder abduction and internal rotation than symptomatic patients with any type of tear (P ≤ .01). Asymptomatic patients also demonstrated greater cross-sectional area of the supraspinatus (P < .01); however, there was no significant difference in the cross-sectional area of the other cuff muscles. There was also no significant difference in the supraspinatus tendon thickness (P = .10). The acromiohumeral distance at 90° of shoulder abduction was larger (P = .04) in asymptomatic patients. Additionally, similar tendencies were observed in the results of patients with supraspinatus tears, except for the isometric torque of shoulder external rotation. This torque was greater (P < .01) in asymptomatic patients.

CONCLUSION

Asymptomatic patients showed greater shoulder range of motion, muscle strength of shoulder abduction and internal rotation, small occupation ratio of supraspinatus tendon thickness as a percentage of acromiohumeral distance, and large cross-sectional area of supraspinatus.

The Application of Double Elastic Band Exercise in the 90/90 Arm Position for Overhead Athletes

BACKGROUND

Traditional exercises performed with the shoulder in the position of 90° abduction and external rotation with elbow flexion (90/90) while using a single elastic band showed moderate activity of both the lower trapezius (LT) and infraspinatus (IS) muscle. The purpose of this study was to investigate activity of the teres minor (TMi) and the LT muscles during standing external rotation exercise with the shoulder in the 90/90 position with 2 elastic bands in both the frontal and the scapular plane.

HYPOTHESIS

TMi, IS, and LT muscle activities will vary depending on whether the shoulder is positioned in the frontal or scapular plane with the application of 2 elastic bands. Also, the serratus anterior (SA) and teres major (TMa) muscles will produce different muscular activity patterns during exercises performed with 2 elastic bands in the frontal plane compared with the TMi and LT muscles.

STUDY DESIGN

Controlled laboratory study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 21 collegiate baseball players volunteered to participate. The electromyography (EMG) activities of the TMi, IS, LT, SA, TMa, middle deltoid (MD), posterior deltoid, and upper trapezius (UT) muscles were measured with the 90/90 arm position during both isometric and oscillation resistance exercises with 2 elastic bands oriented in the frontal and scapular planes.

RESULTS

A significant difference was observed in EMG activity of both the TMi and the LT muscles between single and double elastic band applications in the frontal plane (P < 0.05). In contrast, EMG activity of the IS, SA, and TMa muscles was significantly increased in the scapular plane compared with the frontal plane (P < 0.05).

CONCLUSION

The standing 90/90 position effectively increased both TMi and LT muscle EMG activity with the double elastic band in the frontal plane while minimizing UT and MD muscle activity. EMG activity of the IS, SA, and TMa muscles increased with exercise in the scapular plane as compared with the frontal plane.

CLINICAL RELEVANCE

Oscillation movement under double elastic band application differentiated external rotator muscle and scapular muscle activities between the frontal and scapular plane during the 90/90 exercise in the frontal plane compared with the scapular plane. Clinicians can utilize each of the scapular and frontal positions based on their desired focus for muscular activation.

Effect of preoperative teres minor hypertrophy on reverse total shoulder arthroplasty

BACKGROUND

The preoperative status of the teres minor (Tm) can affect the outcome of reverse total shoulder arthroplasty (RTSA). The effect of preoperative Tm hypertrophy on the outcome of RTSA is unclear.

METHODS

A total of 86 shoulders that underwent RTSA were retrospectively enrolled. Of these, 48 cases with a Tm occupation ratio (OR) of >0.288 in the preoperative magnetic resonance image were assigned to the hypertrophic group, and 38 cases to the control group. The two groups were compared with respect to preoperative rotator cuff tear involvement, fatty infiltration, pre- and postoperative rotator cuff ORs, pain scores, functional scores, range of motion, and muscle strength. Postoperative Tm ORs in 1-year follow-up multidetector computed tomography were compared with preoperative Tm ORs.

RESULTS

Preoperatively, integrities of infraspinatus (ISP) and supraspinatus were significantly different between the 2 groups (P = .001, 0.009, each). Preoperative ISP ORs were significantly related to preoperative Tm ORs (r = -0.534, P < .001). The mean pre- to postoperative change of Tm ORs in the hypertrophic group decreased (-0.029 ± 0.068), whereas that of the control group increased (+0.047 ± 0.092). Postoperative pain scores, functional scores, range of motion, and muscle strength were not different between groups.

CONCLUSIONS

In cases of advanced rotator cuff tear requiring RTSA, Tm hypertrophy is found to be related to tear and atrophy of the ISP, suggesting that Tm hypertrophy is a compensatory change for ISP dysfunction. However, Tm hypertrophy was observed to diminish after RTSA. Preoperative Tm hypertrophy appears to have no beneficial effect on the outcomes of RTSA.

MR Imaging of the Rotator Cuff

The cause of rotator cuff tears is multifactorial with both intrinsic and extrinsic contributing factors. Understanding the normal MR anatomy of the rotator cuff and using an appropriate search pattern can help readers identify common pathologic conditions. Accurate designation using classification systems for tear thickness, size, and degree of retraction and muscle fatty infiltration and atrophy are important in guiding surgical management. Knowledge of common disease locations for the rotator cuff tendons can help focus reader searches and increase sensitivity.

Mid-term results of reverse shoulder arthroplasty for glenohumeral osteoarthritis with posterior glenoid deficiency and humeral subluxation

BACKGROUND

Results of anatomic shoulder arthroplasty for glenohumeral osteoarthritis with severe glenoid retroversion are unpredictable with a high rate of glenoid loosening. Reverse shoulder arthroplasty (RSA) has been suggested as an alternative, with good early results. We sought to confirm this at longer follow-up (minimum 5 years). The study hypothesis was that early results would endure over time.

METHODS

We retrospectively reviewed all RSAs performed in 7 centers from 1998 to 2010. The inclusion criteria were primary glenohumeral osteoarthritis with B1, B2, B3, or C glenoid. Forty-nine shoulders in 45 patients fulfilled the criteria. Bone grafting was performed in 16 cases. Clinical outcomes were evaluated with the Constant score (CS) and shoulder range of motion.

RESULTS

The mean total CS increased from 30 preoperatively to 68 points (P < .001) with significant improvements in all the subsections of the CS and range of motion. Scapular notching was observed in 20 shoulders (43%), grade 1 in 5 (11%), grade 2 in 7 (15%), grade 3 in 5 (11%), and grade 4 in 3 (6%). The glenoid bone graft healed in all the shoulders. Partial inferior lysis of the bone graft was present in 8 cases (50%). Scapular notching and glenoid bone graft resorption had no influence on the CS (P = .147 and P = .798).

CONCLUSION

RSA for the treatment of primary glenohumeral osteoarthritis in patients with posterior glenoid deficiency and humeral subluxation without rotator cuff insufficiency resulted in excellent clinical outcomes at a minimum of 5 years of follow-up.

Traumatic Isolated Myotendinous Rupture of the Teres Minor in a Young Athlete - A Unique Case Report

Introduction:

Functional role of teres minor (TM) is well known. To date, an isolated myotendinous rupture of the TM, without any lesion of the other cuff tendons, has never been reported in literature.

Case Report:

The patient was a 22-year-old soccer player who has presented with a direct shoulder traumatism that is causing persistent pain and impairment. Early appropriate imaging was done (magnetic resonance imaging [MRI] and arthro-computed tomography scan); it revealed an isolated tear of the TM at the myotendinous junction. Open surgical repair was performed through a posterior approach, within the 1st month after the injury. The patient was immobilized for 1 month in neutral rotation and then was allowed to begin the rehabilitation process. At the 2-year follow-up point, the patient had a pain-free and functional shoulder, allowing a return to full activities, including sport at the pre-injury level. MRI confirmed that the muscle had healed, without atrophy or fatty infiltration.

Conclusion:

A TM myotendinous tear is very rare but might be under diagnosed. Early appropriate imaging is necessary. Surgical repair may be the preferable option in young and active patients and should be performed at the acute phase before muscular atrophy and fatty infiltration occur.

Optimizing methods to quantify intramuscular fat in rotator cuff tears with normalization

OBJECTIVE

To determine which normalization method may best account for confounding individual factors, such as age or BMI, when quantifying fat infiltration on MRI in patients with rotator cuff tears, the effects of normalization using three different muscles (teres major; triceps brachii; teres minor) were compared.

METHODS

Thirty-seven consecutive patients diagnosed with rotator cuff pathology were included. MRI fat-water sequences were used to quantify rotator cuff intramuscular fat (%fat). Three reference muscles (teres major, triceps, teres minor) were used to derive normalized %fat. Relationships between intramuscular %fat and tear size, age, and BMI in each rotator cuff muscle, before and after normalization, were compared with Fisher transformations (α = 0.05).

RESULTS

Normalization with teres major ameliorated confounding relationships of age and BMI on rotator cuff %fat. In contrast, normalization with triceps maintained the confounding relationships between %fat and age in supraspinatus (p = 0.03) and infraspinatus/teres minor (p = 0.028). Normalization with teres minor maintained the confounding relationship between %fat and BMI in subscapularis (p = 0.039). Normalization with teres major best-maintained relationships between tear size and infraspinatus/teres minor %fat (p = 0.021). In contrast, normalization with triceps or teres minor eliminated all significant relationships with tear size.

CONCLUSIONS

Results of this pilot study suggest normalization to teres major using MRI-based %fat quantification methods can effectively control for individual factors, such as BMI or age, and may have utility in evaluating and monitoring rotator cuff fat infiltration attributed specifically to a tendon tear.

Diagnostic and therapeutic musculoskeletal ultrasound applications of the shoulder

High frequency ultrasound is a valuable tool for assessing soft tissue injuries about the shoulder. It has advantages over other imaging modalities including relatively low cost, portability, and dynamic real-time visualization. It has a high sensitivity for identifying tendon degeneration, bursitis, and rotator cuff tears. Ultrasound is also an excellent modality for diagnostic and therapeutic needle-guided procedures. A detailed knowledge of shoulder anatomy and transducer positioning is required for obtaining adequate diagnostic value from ultrasound. This Monograph is designed to help develop scanning protocols for optimizing image acquisition for musculoskeletal assessment of the shoulder. Muscle Nerve, 2019.

Long-term results of reverse total shoulder arthroplasty for rotator cuff dysfunction: a systematic review of longitudinal outcomes

BACKGROUND

The aim of this systematic review was to evaluate the longitudinal evolution of midterm to long-term results of reverse total shoulder arthroplasty (RTSA) for patients with massive irreparable rotator cuff tears (miRCT).

METHODS

Databases were scanned for studies of RTSA for miRCT. Studies with a minimum Level IV of evidence were considered eligible. Studies were included if they reported a minimum of 5 years of follow-up and excluded if they reported RTSA combined with tendon transfers or as revision arthroplasty. Data were grouped based on results after 5 to 7 years, 7 to 10 years, and 10 to 20 years of follow-up.

RESULTS

Eight studies with a total of 365 shoulders were included. After a mean follow-up of 9.5 years (range, 5-20 years), the preoperative absolute and relative Constant scores were significantly improved from 24 to 59 points (P = .004) and from 33% to 74% (P = .009). The preoperative Subjective Shoulder Value improved from 23% to 72% (P = .049). Active anterior elevation and abduction also improved significantly (P = .004 and P = .014, respectively), but active external rotation remained unchanged (P = .855). None of the clinical scores or active ranges of motion significantly deteriorated up to 20 years after the operation (P > .05). After 10 years, 42% of the RTSAs showed grade III or IV inferior scapular notching.

CONCLUSION

Pooled long-term results of RTSA for miRCT show significant improvement of overhead function and of objective and subjective outcome scores up to 20 years after surgery. Shoulder function and outcome scores also showed no significant deterioration between 5 and 20 years of follow-up. Longer follow-up will be needed to determine ultimate longevity.

The pattern of idiopathic isolated teres minor atrophy with regard to its two-bundle anatomy

OBJECTIVE

We aimed to analyze the pattern of teres minor atrophy with regard to its two-bundle anatomy and to assess its association with clinical factors.

MATERIALS AND METHODS

Shoulder MRIs performed between January and December 2016 were retrospectively reviewed. Images were evaluated for the presence and pattern of isolated teres minor atrophy. Isolated teres minor atrophy was categorized into complete or partial pattern, and partial pattern was further classified according to the portion of the muscle that was predominantly affected. The medical records were reviewed to identify clinical factors associated with teres minor atrophy.

RESULTS

Seventy-eight shoulders out of 1,264 (6.2%) showed isolated teres minor atrophy; complete pattern in 41.0%, and partial pattern in 59.0%. Most cases of partial pattern had predominant involvement of the medial-dorsal component (82.6%). There was no significant association between teres minor atrophy and previous trauma, shoulder instability, osteoarthritis, and previous operation. The history of shoulder instability was more frequently found in patients with isolated teres minor atrophy (6.4%), compared with the control group (2.6%), although the difference was not statistically significant.

CONCLUSION

Isolated teres minor atrophy may be either complete or partial, and the partial pattern may involve either the medial-dorsal or the lateral-ventral component of the muscle. The imaging findings of partial pattern teres minor atrophy indicate that the two muscle components may have separate innervation.

Relation between Hypertrophy of Teres Minor Muscle and External Rotation Lag Sign in Patients with Rotator Cuff Pathology

BACKGROUND

The purpose of this study was to determine the compensatory hypertrophy of the teres minor (TM) muscle in rotator cuff tears (RCTs) and also the relation between hypertrophy of TM muscle and external rotation lag sign (ERLS).

METHODS

In the period between June 2017 and April 2018, forty patients with RCTs of the shoulder joint came to our institution. We determined the ERLS of all the RCT patients along with the TM occupation ratio in the magnetic resonance imaging (MRI) scan and correlated them together. The normal mean of TM occupational ratio was calculated from ten patients who have undergone MRI scan for other causes but with normal rotator cuff muscles.

RESULTS

In our study, the mean TM occupational ratio of 10 normal rotator cuff patients was 0.277. Of 40 rotator cuff pathology patients, the mean occupational ratio of the TM in RCTs is 0.359. Sixteen of the 40 patients had ER lag positive and the remaining 24 patients had ER lag negative. Those who were ER lag negative have an TM occupational ratio >0.401. A positive correlation was found between hypertrophy of TM and ERLS.

CONCLUSION

ERLS will be negative in patients with hypertrophy of TM in the setting of posterosuperior cuff tears. There is a strong correlation between cuff tears and hypertrophy of TM muscle, which helps in better prognosis and functional outcome of the patients treated with surgical intervention.

Biceps Detachment Preserves Joint Function in a Chronic Massive Rotator Cuff Tear Rat Model

BACKGROUND

Lesions of the long head of the biceps tendon are often associated with massive rotator cuff tears (MRCTs), and biceps tenotomy is frequently performed for pain relief and functional reservation. However, the efficacy and safety of biceps tenotomy regarding the effects on the surrounding tissues in chronic MRCT are unclear.

HYPOTHESIS

Biceps tenotomy would result in improved mechanical and histological properties of the intact subscapularis tendon and improved in vivo shoulder function while not compromising glenoid cartilage properties.

STUDY DESIGN

Controlled laboratory study.

METHODS

Right supraspinatus and infraspinatus tendons were detached in 25 male Sprague-Dawley rats, followed by 4 weeks of cage activity to create a chronic MRCT condition. Animals were randomly divided into 2 groups and received either biceps tenotomy (n = 11) or sham surgery (n = 14) and were sacrificed 4 weeks thereafter. Forelimb gait and ground-reaction forces were recorded 1 day before the tendon detachment (baseline), 1 day before the surgical intervention (biceps tenotomy or sham), and 3, 7, 10, 14, 21, and 28 days after the intervention to assess in vivo shoulder joint function. The subscapularis tendon and glenoid cartilage were randomly allocated for mechanical testing or histologic assessment after the sacrifice.

RESULTS

Compared with sham surgery, biceps tenotomy partially restored the in vivo shoulder joint function, with several gait and ground-reaction force parameters returning closer to preinjury baseline values at 4 weeks. With biceps tenotomy, mechanical properties of the subscapularis tendons were improved, while mechanical properties and histological Mankin scores of the glenoid cartilage were not diminished when compared with the sham group.

CONCLUSION

Biceps tenotomy in the presence of chronic MRCT partially preserves overall shoulder function and potentially restores subscapularis tendon health without causing detrimental effects to joint cartilage. This laboratory study adds to the growing literature regarding the protective effects of biceps tenotomy on the shoulder joint in a chronic MRCT model.

CLINICAL RELEVANCE

This study provides important basic science evidence supporting the use of biceps tenotomy in patients with massive rotator cuff tears.

The presence of a rotator cuff tear interferes with age-dependent muscle atrophy of intact shoulder muscles. An MRI study with 3 years' follow-up

Rotator cuff muscle atrophy is frequently studied, but it is unknown whether redistribution of mechanical load in the presence of a rotator cuff tear influence muscle atrophy that is observed in patients. We hypothesized that in the presence of a supraspinatus tear, redistribution of mechanical load towards teres minor and deltoid slows down atrophy of these muscles over time. In this retrospective observational study of 129 patients, we measured the cross-sectional surface-areas on MRI of shoulder muscles in an intact rotator cuff (n = 92) and in a supraspinatus-tear group (n = 37) with a mean follow-up of 3 ± 1.8 years. Mixed models were applied to evaluate changes in surface-area of the rotator cuff and deltoid with adjustments for age, sex and follow-up time. In patients with an intact rotator cuff, the mean surface-area of the teres minor decreased 6 mm²/year (95% CI 0.7-11.1, P = 0.026) and the mean deltoid surface-area decreased 75 mm²/year (95% CI 24.5-124.8, P = 0.004). The presence of a rotator cuff tear was associated with less reduction of teres minor and deltoid surface-area in patients <50 years, with an effect of a tear of 22 mm²/year (95% CI 1.7-41.7, P = 0.034) and 250 mm²/year (95% CI 75.8-424.3, P = 0.006), respectively. Whereas the surface-area of teres minor and deltoid decrease over time in patient with an intact rotator cuff, the decline in surface-area of these muscles was substantially less in the presence of a rotator cuff tear. Our findings indicate that atrophy may be reduced if an increase in mechanical load is exerted onto the muscle.

Understanding the Importance of the Teres Minor for Shoulder Function: Functional Anatomy and Pathology

Although the teres minor is often overlooked in a normal shoulder, it becomes a key component in maintaining shoulder function when other rotator cuff tendons fail. The teres minor maintains a balanced glenohumeral joint and changes from an insignificant to the most significant external rotator in the presence of major rotator cuff pathology. The presence or absence of the teres minor provides prognostic information on the outcomes of reverse total shoulder arthroplasty and tendon transfers. Clinical tests include the Patte test, the Neer dropping sign, the external rotation lag sign, and the Hertel drop sign. Advanced imaging of the teres minor can be used for classification using the Walch system. Understanding the function and pathology surrounding the teres minor is paramount in comprehensive management of the patient with shoulder pathology. Appropriate clinical examination and imaging of the teres minor are important for preoperative stratification and postoperative expectations.

Isolated loss of active external rotation: a distinct entity and results of L'Episcopo tendon transfer

BACKGROUND

The purpose of this study was to characterize a subgroup of cuff-deficient patients with isolated loss of active external rotation (ILER) but preserved active elevation and to evaluate the outcomes of the L'Episcopo procedure to restore horizontal muscle balance.

METHODS

During a 10-year period, 26 patients (14 men, 12 women) were identified with ILER in the setting of massive irreparable posterosuperior cuff tears. A modified L'Episcopo tendon transfer was performed to restore active external rotation and to improve shoulder function. The mean age at surgery was 64.5 years (29-83 years). Patients were evaluated with a mean follow-up of 52 months (range, 24-104 months).

RESULTS

Preoperatively, despite maintained active elevation (average of 161°), ILER patients complained about loss of spatial control of the arm and difficulties with activities of daily living. On computed tomography scan or magnetic resonance imaging, there was severe fatty infiltration of infraspinatus and absent or atrophic teres minor. After L'Episcopo transfer, 84% of patients were satisfied. The gain in active external rotation was +26° in arm at the side and +18.5° in 90° abduction. Adjusted Constant score and Simple Shoulder Value increased from 63.6% to 86.9% and from 36.9% to 70.8%, respectively (P < .001). The ADLER score increased from 10 to 24.5 points (P < .002). Two patients with advanced cuff tear arthropathy (Hamada stage 3 and 4) required conversion to a reverse shoulder arthroplasty (RSA) 7 and 9 years after the index surgery.

CONCLUSIONS

ILER is a distinct entity that is a cause of severe handicap because of loss of spatial control of the upper limb. This symptom is related to absent or atrophied infraspinatus and teres minor. In properly selected cases (Hamada stage 1 or 2), the modified L'Episcopo transfer is effective at restoring anterior-posterior rotator cuff force balance. In more advanced cuff tear arthropathy (Hamada stage ≥3), the tendon transfer should be performed with an RSA because of possible secondary degeneration of the glenohumeral joint.

Reverse Total Shoulder Arthroplasty for Massive, Irreparable Rotator Cuff Tears Before the Age of 60 Years: Long-Term Results

BACKGROUND

There has been serious concern regarding the longevity and durability of outcomes of reverse total shoulder arthroplasty (RTSA) in younger patients. It was the purpose of this study to analyze long-term outcomes and complications of RTSA for irreparable rotator cuff tears in patients younger than 60 years.

METHODS

Twenty patients (23 shoulders) with a mean age of 57 years (range, 47 to 59 years) were evaluated at a mean of 11.7 years (range, 8 to 19 years) after RTSA. Fifteen shoulders (65%) had undergone previous non-arthroplasty surgery. Longitudinal clinical and radiographic outcomes were assessed.

RESULTS

At the time of final follow-up, the mean absolute and relative preoperative Constant score (CS) (and standard deviation) had improved from 24 ± 9 to 59 ± 19 points (p < 0.001) and from 29% ± 11% to 69% ± 21% (p < 0.001), respectively. The mean Subjective Shoulder Value (SSV) had increased from 20% ± 13% to 71% ± 27% (p < 0.001). There were also significant improvements in the mean active anterior elevation (from 64° to 117°), active abduction (from 58° to 111°), pain scores, and strength (all p ≤ 0.001). Clinical outcomes did not significantly deteriorate beyond 10 years and the functional results of patients with previous surgical procedures were not significantly inferior to the results of those with primary RTSA. The grade of, and number of patients with, radiographically apparent notching increased over time; the mean relative CS was lower in patients in whom the notching was grade 2 or higher (57%) than it was in those with no or grade-1 notching (81%; p = 0.006). Nine (39%) had ≥1 complication, with 2 failed RTSAs (9%).

CONCLUSIONS

RTSA in patients younger than 60 years leads to substantial subjective and functional improvement without clinical deterioration beyond 10 years. It is associated with a substantial complication rate, and complications compromise ultimate subjective and objective outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Anatomic study and electromyographic analysis of the teres minor muscle

BACKGROUND

The teres minor muscle is a focused topic on the treatment of massive rotator cuff tears and reverse total shoulder arthroplasty. Its precise anatomy and function have not been completely investigated. The purposes of this study were to anatomically investigate the muscle and analyze electromyographic (EMG) activities during shoulder motion.

METHODS

This anatomic study used 20 shoulders from deceased donors (mean age, 75.0 years). EMG data were recorded from 10 healthy volunteers (mean age, 21.7 years) during flexion, abduction, and external rotations at 0° of abduction, at 90° of abduction, and at 90° of flexion in their dominant arms synchronized with a computerized 3-dimensional motion analysis system.

RESULTS

The muscle in all specimens consisted of 2 distinct muscular bundles: the upper and lower portions. The upper portion attached to the round area of the greater tuberosity, and the lower portion inserted into the linear shaped area. Both portions were independent in their origins, insertions, and innervation. The muscle engaged force during each shoulder motion. EMG activities of abduction and the 3 forms of external rotation were similar. Maximal voluntary contraction in the 3 forms of external rotation was 32% in maximum external rotation in the neutral position, 25% in flexion, and 40% in abduction.

CONCLUSIONS

The teres minor consists of independent upper and lower portions. The muscle engages force in all ranges of 5 shoulder motions, and maximum external rotation in abduction is a reliable method to evaluate potential activity of the muscle.

An anatomical investigation of clock face landmarks around the glenoid for shoulder arthroscopy orientation

BACKGROUND

For shoulder arthroscopy, few anatomical landmarks are available and inexperienced surgeons tend to be adrift due to the limited visual field of the scope. The purpose of this study was to demonstrate the useful landmarks around the glenoid for accurate orientation, and also the safe distance to avoid suprascapular nerve injury during surgical procedures around the glenoid.

METHODS

In 15 human solution-fixed cadavers, a cross-section of the shoulder joint on the labrum surface was created. The positions of the principal anatomical structures surrounding the glenoid were marked on the labrum and measured using our clock face indication system. In 9 shoulders the distances from the labral surface to the spinoglenoid notch were recorded. As an indicator of the scapula size, the distances between the superior and inferior angles of the scapula were also measured.

RESULTS

The average landmark positions in the right shoulder were as follows: center of the attachment of the long tendon 11:59, anterior edge of the supraspinatus 11:59, posterior edge of the base of the coracoid process 12:13, superior edge of the subscapularis 1:03, anterior edge of the base of the coracoid process 1:25, inferior edge of the subscapularis 5:27, inferior edge of the teres minor 6:21, border of the infraspinatus and teres minor 7:43, center of the scapula spine 10:06, border of the supra and infraspinatus 10:27. The average distance from the labral surface to the spinoglenoid notch was 23.17 mm, and that from the superior to inferior angle was 144.93 mm. The Pearson correlation coefficient for these distances was 0.007.

CONCLUSIONS

The locations of anatomical landmarks surrounding the glenoid were reliably demonstrated using our clock face indication system. The expected distance from the labral surface to the suprascapular nerve was approximately 23 mm, irrespective of the size of the scapula.

Editorial Commentary: Teres Minor Fatty Infiltration on Magnetic Resonance Imaging--Have You Considered It, and Does It Matter When Performing Rotator Cuff Repairs?

Rotator cuff repair can be performed without a great deal of concern in the presence of fatty infiltration in the teres minor.

Effect of Teres Minor Fatty Infiltration on Rotator Cuff Repair Outcomes

PURPOSE

To observe changes in fatty infiltration (FI) of the teres minor without tear of the teres minor in a postoperative magnetic resonance imaging and to evaluate the influence of FI of the teres minor in the clinical outcomes of rotator cuff repair.

METHODS

Of 816 patients who underwent rotator cuff repair, 51 (6.3%) had FI of the teres minor without tear involvement and 30 cases were available for postoperative magnetic resonance imaging. FI and functional outcome scores were assessed and compared with the control group that had no FI of the teres minor selected by a propensity score matching.

RESULTS

FI of the teres minor was observed in various degrees (grade 1 in 9, grade 2 in 9, grade 3 in 6, and grade 4 in 6). The degree of FI was not related to the amount of tendon involvement of a rotator cuff tear (P = .240). All postoperative functional outcome scores (12.6 ± 1.2 months; range, 11-17), including pain visual analog scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons Score, significantly improved (all P < .001), and there were no significant differences compared with that of the control group. In most of the cases, FI of the teres minor was unchanged (P = .317).

CONCLUSIONS

FI of the teres minor without tear involvement can be observed in a rotator cuff tear as a possibly incidental finding of unknown clinical significance. Its cause has not been determined, and it appears that FI of the teres minor does not appear to improve, at least at the 1-year follow-up. Nevertheless, the functional outcomes of the repair were successful in our study; therefore, rotator cuff repair can be performed without a great deal of concern in the presence of FI in the teres minor.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Arthroscopic Repair of an Isolated Teres Minor Tear: A Case Report

CASE

Isolated avulsion of the teres minor tendon is exceedingly uncommon and, to our knowledge, the presentation and arthroscopic repair of this type of injury have not been described. Known musculotendinous avulsions about the shoulder frequently involve the supraspinatus, long head of the biceps, and pectoralis major.

CONCLUSION

We present the case of a patient with an isolated teres minor avulsion and an otherwise intact rotator cuff. The patient underwent successful arthroscopic repair and rehabilitation, allowing for a return to the pre-injury level of function.

Patterns of Age-Associated Degeneration Differ in Shoulder Muscles

Shoulder complaints are common in the elderly and hamper daily functioning. These complaints are often caused by tears in the muscle-tendon units of the rotator cuff (RC). The four RC muscles stabilize the shoulder joint. While some RC muscles are frequently torn in shoulder complaints others remain intact. The pathological changes in RC muscles are poorly understood. We investigated changes in RC muscle pathology combining radiological and histological procedures. We measured cross sectional area (CSA) and fatty infiltration from Magnetic Resonance Imaging with Arthrography (MRA) in subjects without (N = 294) and with (N = 109) RC-tears. Normalized muscle CSA of the four RC muscles and the deltoid shoulder muscle were compared and age-associated patterns of muscle atrophy and fatty infiltration were constructed. We identified two distinct age-associated patterns: in the supraspinatus and subscapularis RC muscles CSAs continuously declined throughout adulthood, whereas in the infraspinatus and deltoid reduced CSA was prominent from midlife onwards. In the teres minor, CSA was unchanged with age. Most importantly, age-associated patterns were highly similar between subjects without RC tear and those with RC-tears. This suggests that extensive RC muscle atrophy during aging could contribute to RC pathology. We compared muscle pathology between torn infraspinatus and non-torn teres minor and the deltoid in two patients with a massive RC-tear. In the torn infraspinatus we found pronounced fatty droplets, an increase in extracellular collagen-1, a loss of myosin heavy chain-1 expression in myofibers and an increase in Pax7-positive cells. However, the adjacent intact teres minor and deltoid exhibited healthy muscle features. This suggests that satellite cells and the extracellular matrix may contribute to extensive muscle fibrosis in torn RC. We suggest that torn RC muscles display hallmarks of muscle aging whereas the teres minor could represent an aging-resilient muscle.

What is the Best Clinical Test for Assessment of the Teres Minor in Massive Rotator Cuff Tears?

BACKGROUND

Few studies define the clinical signs to evaluate the integrity of teres minor in patients with massive rotator cuff tears. CT and MRI, with or without an arthrogram, can be limited by image quality, soft tissue density, motion artifact, and interobserver reliability. Additionally, the ill-defined junction between the infraspinatus and teres minor and the larger muscle-to-tendon ratio of the teres minor can contribute to error. Therefore, we wished to determine the validity of clinical testing for teres minor tears.

QUESTION/PURPOSES

The aim of this study was to determine the accuracy of commonly used clinical signs (external rotation lag sign, drop sign, and the Patte test) for diagnosing the teres minor's integrity.

METHODS

We performed a prospective evaluation of patients referred to our shoulder clinic for massive rotator cuff tears determined by CT arthrograms. The posterosuperior rotator cuff was examined clinically and correlated with CT arthrograms. We assessed interobserver reliability for CT assessment and used three different clinical tests of teres minor function (the external rotation lag sign, drop sign, and the Patte test). One hundred patients with a mean age of 68 years were available for the analysis.

RESULTS

The most accurate test for teres minor dysfunction was an external rotation lag sign greater than 40°, which had a sensitivity of 100% (95% CI, 80%-100%) and a specificity of 92% (95% CI, 84%-96%). External rotation lag signs greater than 10° had a sensitivity of 100% (95% CI, 80%-100%) and a specificity of 51% (95% CI, 40%-61%). The Patte sign had a sensitivity of 93% (95% CI, 70%-99%) and a specificity of 72% (95% CI, 61%-80%). The drop sign had a sensitivity of 87% (95% CI, 62%-96%) and a specificity of 88% (95% CI, 80%-93%). An external rotation lag sign greater than 40° was more specific than an external rotation lag sign greater than 10° (p < 0.001), and a Patte sign (p < 0.001), but was not more specific than the drop sign (p < 0.47). There was poor correlation between involvement of the teres minor and loss of active external rotation.

CONCLUSIONS

Clinical signs can predict anatomic patterns of teres minor dysfunction with good accuracy in patients with massive rotator cuff tears. This study showed that the most accurate test for teres minor dysfunction is an external rotation lag sign and that most patients' posterior rotator cuff tears do not lose active external rotation. Because imaging is not always accurate, examination for integrity of the teres minor is important because it may be one of the most important variables affecting the outcome of reverse shoulder arthroplasty for massive rotator cuff tears, and the functional effects of tears in this muscle on day to day activities can be significant. Additionally, teres minor integrity affects the outcomes of tendon transfers, therefore knowledge of its condition is important in planning repairs.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Clinical performance of lateralized versus non-lateralized reverse shoulder arthroplasty: a prospective randomized study

BACKGROUND

Reverse shoulder arthroplasty (RSA) is an established therapeutic option in the treatment of cuff tear arthropathy (CTA). Recent studies have described a positive effect of lateralization of the center of rotation, especially on postoperative rotational function. The goal of this study is to compare the outcome of non-lateralized versus lateralized RSA with particular regard to rotational function in patients with CTA.

METHODS

Thirty-four patients underwent implantation of RSA either with lateralization (n = 17) or without lateralization (n = 17) by use of a 1-cm autologous bone graft ("bony increased offset") of the humeral head for CTA. Clinical outcomes were measured with the Constant score; the Disabilities of the Arm, Shoulder and Hand score; and the Activities of Daily Living Requiring External Rotation score, as well as measurement of external rotation and determination of the external rotation lag sign with the arm at the side and at 90° of abduction, at 1 year postoperatively and at final follow-up. Computed tomography scan evaluation was performed in all patients preoperatively and at 1 year postoperatively to assess preoperative fatty infiltration of the rotator cuff and bony integration of the graft postoperatively.

RESULTS

At final follow-up, all patients showed significantly increased functional results. There were no significant differences in the evaluated parameters. If patients with degenerative changes of the teres minor were excluded, the lateralized group showed significantly increased external rotation. Bony integration of the graft could be verified on postoperative computed tomography scans in all patients.

CONCLUSION

RSA with bony lateralization shows a trend toward improved external rotation in lateralized RSA, with a statistically significant improvement in external rotation in patients with an intact teres minor.

Arthroscopic Partial Repair of Irreparable Rotator Cuff Tears: Preoperative Factors Associated With Outcome Deterioration Over 2 Years

BACKGROUND

Arthroscopic partial repair is a treatment option in irreparable large-to-massive rotator cuff tears without arthritic changes. However, there are indications that arthroscopic partial repair does not yield satisfactory outcomes.

PURPOSE

To report the clinical and radiographic results of arthroscopic partial repairs in patients with irreparable large-to-massive cuff tears. In addition, an analysis was performed regarding preoperative factors that may influence patient outcomes and patient-rated satisfaction over time.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From 2005 to 2011, a total of 31 patients who underwent arthroscopic partial repair for irreparable large-to-massive cuff tears were retrospectively evaluated. Partial repair was defined as posterior cuff tissue repair with or without subscapularis tendon repair to restore the transverse force couple of the cuff. Pain visual analog scale (PVAS), questionnaire results (American Shoulder and Elbow Surgeons [ASES] and Simple Shoulder Test [SST]), and radiographic changes (acromiohumeral distance and degenerative change) were assessed preoperatively, at first follow-up (roughly 1 year postoperatively), and at final follow-up (>2 years postoperatively). Patients rated their satisfaction level at each postoperative follow-up as well. Preoperative factors that might influence outcomes, such as patient demographics, tear size, and fatty infiltration, were investigated.

RESULTS

The preoperative, first follow-up, and final follow-up results for mean PVAS (5.13, 2.13, and 3.16, respectively) and questionnaires (ASES: 41.97, 76.37, and 73.78; SST: 3.61, 6.33, and 6.07, respectively) improved significantly (all P < .05). Radiographic evaluation showed no difference compared with preoperative status. Nevertheless, patient-rated satisfaction at final evaluation was inferior: 16 good responses ("very satisfied" and "satisfied") and 15 poor responses ("rather the same" and "dissatisfied"). Despite initial improvements in both groups (P < .05), patients with poor satisfaction demonstrated statistically significant deterioration in mean PVAS (from 2.07 to 4.67), questionnaire scores (ASES: from 74.56 to 59.80; SST: from 5.11 to 3.81), and acromiohumeral distance (from 7.19 to 5.06 mm) between the first and final follow-up (all P < .05). Patients with good satisfaction showed no significant difference or they improved (P > .05) from the first to the final follow-up. Among preoperative factors, fatty infiltration of the teres minor was identified as the only statistically significant factor affecting patient-rated satisfaction (P = .007).

CONCLUSION

This study showed that arthroscopic partial repair may produce initial improvement in selected outcomes at 2-year follow-up. However, about half of the patients in the study were not satisfied with their outcomes, which had deteriorated over time. Preoperative fatty infiltration of the teres minor was the only factor that correlated with worse final outcomes and poor satisfaction after arthroscopic partial repair.

Hypertrophic changes of the teres minor muscle in rotator cuff tears: quantitative evaluation by magnetic resonance imaging

BACKGROUND

Few reports have assessed the teres minor (TM) muscle in rotator cuff tears. This study aimed to quantitatively analyze the morphologic changes of the TM muscle in patients with or without rotator cuff tears by magnetic resonance imaging (MRI).

METHODS

This retrospective study consisted of 279 subjects classified on the basis of interpretations of conventional MRI observations into 6 groups: no cuff tear; partial-thickness supraspinatus (SSP) tear; full-thickness SSP tear; SSP and subscapularis tears; SSP and infraspinatus (ISP) tears; and SSP, ISP, and subscapularis tears. With use of ImageJ software (National Institutes of Health, Bethesda, MD, USA) for oblique sagittal MRI, we measured the areas of ISP, TM, and anatomic external rotation (ISP + TM) muscles on the most lateral side in which the scapular spine was in contact with the scapular body. The occupational ratios of the TM muscle area to the anatomic external rotation muscle area were calculated. Ratios above the maximum of the 95% confidence intervals of the occupational ratio in the no-tear group were defined as hypertrophy of the TM muscle.

RESULTS

Occupational ratios of the TM muscle in the no-tear group followed a normal distribution, and ratios >0.288 were defined as hypertrophic. Hypertrophic changes of the TM muscle were confirmed in rotator cuff tears involving the ISP tendon. A negative correlation was found between the occupational ratios of TM and ISP (P < .001).

CONCLUSION

The TM muscle appeared hypertrophic in rotator cuff tears involving the ISP, and the progression of ISP muscle atrophy seemed to induce the development of this compensatory hypertrophy.