MRI of pectoralis major tears: association between ancillary findings and tear severity

Muscle Injury Around the Shoulder

Acute shoulder tendon and intra-articular injuries are common and their imaging well described. However, a subset of patients present with more unusual acute shoulder muscle injury. Of these, pectoralis major muscle injuries are encountered the most often and are increasingly prevalent due to a focus on personal fitness, particularly bench-press exercises. Other muscle injuries around the shoulder are rare. This article reviews the anatomy, mechanism of injury, and the imaging findings in relation to injuries of these muscles around the shoulder. We focus on pectoralis major injury but also review proximal triceps, latissimus dorsi, teres major, and deltoid muscle injuries, providing imaging examples.

Bilateral pectoralis major MRI in weightlifters: findings of the non-injured side versus age-matched asymptomatic athletes

OBJECTIVE

To evaluate magnetic resonance imaging (MRI) features of the contralateral side in weightlifting athletes with pectoralis major (PM) tears. We hypothesized that MRI of the non-injured side may present increased pectoralis major tendon (PMT) length and thickness and greater pectoralis major muscle (PMM) volume and cross-sectional area when compared with the control group.

METHODS

We retrospectively identified MRI cases with unilateral PM injury and reviewed imaging findings of the contralateral side. Also, we evaluated MRI from ten asymptomatic control weightlifting athletes, with PM imaging from both sides. Two musculoskeletal radiologists independently reviewed MRI and measured PMT length, PMT thickness, PMM volume (PMM-vol) and PMM cross-sectional area (PMM-CSA), as well as humeral shaft cross-sectional area (Hum-CSA) and the ratio between PMM-CSA and Hum-CSA (PMM-CSA/Hum-CSA). Data were compared between the non-injured side and controls. The MRI protocol from both groups was the same and included T1 FSE and T2 FATSAT axial, coronal, and sagittal images, one side at a time.

RESULTS

We identified 36 male subjects with unilateral PM injury with mean age 35.7 ± 8 years and 10 age- and gender-matched controls (p = 0.45). A total of 36 PM MRI with non-injured PM and 20 PM MRI studies were included in this study. PMT length and PMT thickness were significantly higher in contralateral PM injury versus control subjects (both P < 0.001). Also, PM-CSA and Hum-CSA were greater in the contralateral PM injury group (P = 0.032 and P < 0.001, respectively). PMT thickness > 2.95 mm had 80.6% sensitivity and 90.0% specificity to differentiate the non-injured PM group from controls.

CONCLUSION

Non-injured side MR imaging of patients with previous contralateral PM lesion demonstrates greater PMT thickness and length as well as PM-CSA and Hum-CSA than controls.

Pectoralis Major Rupture: Evaluation and Management

Pectoralis major tendon ruptures are being reported with increasing frequency and primarily occur in young, high demand, male patients. The injury results from an eccentric contracture of the muscle most commonly while performing the bench press maneuver during weight training. In the setting of both acute and chronic injury, physical examination is critical for a timely and accurate diagnosis. During physical examination, comparison with the opposite side is imperative, and findings may include swelling, ecchymosis, loss of the anterior axillary fold, and a decreased pectoralis major index. Surgical treatment of acute ruptures is superior to nonsurgical treatment and results in improved functional outcomes and high levels of return to work and sport. Repair of chronic tears is more challenging and may require reconstruction with autograft or allograft tissue. Despite advances in surgical technique, tendon rerupture, persistent pain, and wound infection remain a concern.

Automatic MRI segmentation of pectoralis major muscle using deep learning

To develop and validate a deep convolutional neural network (CNN) method capable of selecting the greatest Pectoralis Major Cross-Sectional Area (PMM-CSA) and automatically segmenting PMM on an axial Magnetic Resonance Imaging (MRI). We hypothesized a CNN technique can accurately perform both tasks compared with manual reference standards. Our method is based on two steps: (A) segmentation model, (B) PMM-CSA selection. In step A, we manually segmented the PMM on 134 axial T1-weighted PM MRIs. The segmentation model was trained from scratch (MONAI/Pytorch SegResNet, 4 mini-batch, 1000 epochs, dropout 0.20, Adam, learning rate 0.0005, cosine annealing, softmax). Mean-dice score determined the segmentation score on 8 internal axial T1-weighted PM MRIs. In step B, we used the OpenCV2 (version 4.5.1, https://opencv.org) framework to calculate the PMM-CSA of the model predictions and ground truth. Then, we selected the top-3 slices with the largest cross-sectional area and compared them with the ground truth. If one of the selected was in the top-3 from the ground truth, then we considered it to be a success. A top-3 accuracy evaluated this method on 8 axial T1-weighted PM MRIs internal test cases. The segmentation model (Step A) produced an accurate pectoralis muscle segmentation with a Mean Dice score of 0.94 ± 0.01. The results of Step B showed top-3 accuracy > 98% to select an appropriate axial image with the greatest PMM-CSA. Our results show an overall accurate selection of PMM-CSA and automated PM muscle segmentation using a combination of deep CNN algorithms.

The diagnostic performance of MRI signs to distinguish Pectoralis major tendon avulsions from Myotendinous injuries

BACKGROUND

Management of pectoralis major (PM) injuries is largely determined by the anatomic location of the injury, with tendon avulsions from the humerus requiring surgery while myotendinous (MT) injuries are typically managed non-operatively. Because physical examination cannot reliably make this distinction, MRI is often used for staging. However, correct classification can also be difficult with MRI where there is extensive soft tissue edema and distorted anatomy.

OBJECTIVE

To determine the diagnostic performance of primary and secondary MRI signs of PM injury for distinguishing tendon avulsions from MT injuries in a selected sample of patients that underwent surgical repair using a practical interpretation algorithm.

METHODS

In this retrospective study, 3 blinded observers independently assessed the MRI findings of 17 patients with PM injury (including 12 acute injuries, 4 chronic, and 1 of uncertain age) where subsequent surgery documented tendon avulsion (11) and MT injuries (6) by applying the primary MRI criteria of absent tendon at the humerus, retracted tendon stump, epicenter of edema, and the secondary finding of soft tissue edema contacting the anterior humeral cortex. Operative findings were used as the reference standard. Sensitivity, specificity, and positive and negative predictive value were recorded for each finding.

RESULTS

The primary MRI finding of lack of a visible tendon at the insertion (sensitivity 82-100%, specificity 100%) and the secondary finding of edema contacting the anterior humeral cortex (sensitivity 64-91%, specificity 67-100%) were both useful for the distinction of tendon avulsion from MT injury, particularly in acute injuries. The presence of a retracted tendon stump and the epicenter of edema were not reliable findings. The use of a decision tree including the secondary finding of humeral edema increased the sensitivity and specificity for 2 of the 3 observers.

CONCLUSION

MRI assessment of PM injury focused on the humeral insertion of the PM tendon allows accurate distinction of tendon avulsion from MT injury.

CLINICAL IMPACT

This study describes a practical approach to classifying PM injuries with MRI to distinguish injuries that require surgery from those that can potentially be managed conservatively.

The smoke sign: a secondary sign of unsuspected acute pectoralis major tendon injury on routine shoulder MRI

OBJECTIVE

To study the diagnostic utility of the "smoke sign" to detect unsuspected acute pectoralis major tendon injury on routine shoulder MRI.

MATERIALS AND METHODS

Retrospective study of 52 shoulder MRI in patients with (38) and without (14) acute pectoralis major injury confirmed on imaging. Two readers independently reviewed shoulder MRI for the presence of the "smoke sign"-feathery soft tissue edema lateral or anterior to short head biceps/coracobrachialis on fluid-sensitive coronal-oblique and sagittal-oblique images, respectively.

RESULTS

The smoke sign was present on shoulder MRI in 24/24 (100%) humeral avulsions, 4/4 (100%) tendon tears, 4/8 (50%) of myotendinous junction injuries, and 0/2 (0%) intramuscular injuries. The smoke sign was present in 0/14 examinations without acute pectoralis major injury.

CONCLUSION

While dedicated pectoralis MRI remains the preferred method for imaging pectoralis injury, the "smoke sign" can serve as an easy to recognize finding on routine shoulder MRI that can raise the suspicion of an acute pectoralis major tendon injury. Its detection should prompt evaluation of the pectoralis major tendon and recommendation for dedicated imaging to confirm and evaluate the full extent of injury.

Pectoralis Major Tendon Tear: A Critical Analysis Review

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Pectoralis major (PM) tendon tears are predominantly seen in young men, and the majority of tears occur as tendon avulsions involving the sternal head. Weightlifting, specifically bench-pressing, and sporting activities with eccentric overloading of the PM tendon are the 2 most common activities that result in PM injury.

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Early surgical repair or reconstruction should be offered to younger, active patients with a complete PM tear; the majority of the patients undergoing surgical repair achieve good-to-excellent outcomes.

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Nonsurgical treatment of a complete PM tear is an option but will result in cosmetic deformity and a deficit in adduction strength of the arm. Outcomes after nonsurgical treatment of complete PM tears are less satisfactory than those obtained after surgical treatment.

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Currently, there is no consensus on the chronological definition of PM tears (acute versus chronic), the critical time limit for performing surgical repair, the ideal fixation device (cortical button, bone tunnel, or suture anchors), the indications for allograft use, and the ideal rehabilitation protocol after treatment of PM tears.

Injuries in Muscle-Tendon-Bone Units: A Systematic Review Considering the Role of Passive Tissue Fatigue

Background:

Low-cycle fatigue damage accumulating to the point of structural failure has been recently reported at the origin of the human anterior cruciate ligament under strenuous repetitive loading. If this can occur in a ligament, low-cycle fatigue damage may also occur in the connective tissue of muscle-tendon units. To this end, we reviewed what is known about how, when, and where injuries of muscle-tendon units occur throughout the body.

Purpose:

To systematically review injuries in the muscle-tendon-bone complex; assess the site of injury (muscle belly, musculotendinous junction [MTJ], tendon/aponeurosis, tendon/aponeurosis–bone junction, and tendon/aponeurosis avulsion), incidence, muscles and tendons involved, mechanism of injury, and main symptoms; and consider the hypothesis that injury may often be consistent with the accumulation of multiscale material fatigue damage during repetitive submaximal loading regimens.

Methods:

PubMed, Web of Science, Scopus, and ProQuest were searched on July 24, 2019. Quality assessment was undertaken using ARRIVE, STROBE, and CARE (Animal Research: Reporting In Vivo Experiments, Strengthening the Reporting of Observational Studies in Epidemiology, and the Case Report Statement and Checklist, respectively).

Results:

Overall, 131 studies met the inclusion criteria, including 799 specimens and 2,823 patients who sustained 3,246 injuries. Laboratory studies showed a preponderance of failures at the MTJ, a viscoelastic behavior of muscle-tendon units, and damage accumulation at the MTJ with repetitive loading. Observational studies showed that 35% of injuries occurred in the tendon midsubstance; 28%, at the MTJ; 18%, at the tendon-bone junction; 13%, within the muscle belly and that 6% were tendon avulsions including a bone fragment. The biceps femoris was the most injured muscle (25%), followed by the supraspinatus (12%) and the Achilles tendon (9%). The most common symptoms were hematoma and/or swelling, tenderness, edema and muscle/tendon retraction. The onset of injury was consistent with tissue fatigue at all injury sites except for tendon avulsions, where 63% of the injuries were caused by an evident trauma.

Conclusion:

Excluding traumatic tendon avulsions, most injuries were consistent with the hypothesis that material fatigue damage accumulated during repetitive submaximal loading regimens. If supported by data from better imaging modalities, this has implications for improving injury detection, prevention, and training regimens.

Sports Medicine-Related Breast and Chest Conditions-Update of Current Literature

ABSTRACT

This article reviews the most up-to-date evidence-based recommendations pertaining to breast and upper chest conditions, specifically for the sports medicine physician. Because of the unique circumstances of the team physician, they can see a wide breadth of pathology. Athletes may not have a primary care physician and may prefer to present to their team physician for breast and upper chest conditions. It is often more comfortable and convenient for athletes to seek treatment in the team setting. Therefore, it is important that the medical professional be aware of not only common pathology but also of that which is rarer. Any delay in evaluation can result in unnecessary morbidity and lead to complications or extended time lost from sport. Consequently, it also is important to facilitate an atmosphere encouraging early presentation and workup.

Pectoralis major tear in a 23-year-old woman while performing high-intensity interval training: a rare presentation

Pectoralis major (PM) tears are a rare injury, that commonly occurs at the sternocostal head and has a greater incidence in men, with only two previously reported cases in young and middle-aged women. The authors report a complete PM tear that occurred in a 23-year-old woman, that presented after performing a 'muscle-up'. MRI revealed PM rupture at the humeral insertion. Surgical management was performed, and patient returned to high-intensity interval training at 11 months postoperatively and reported great satisfaction. This is the first case in literature that reports a complete tear of the PM in a young woman through an atraumatic mechanism of injury with no previous alteration to the PM. With a cultural increase in wellness, atraumatic PM tear in young women should be expected and remain on the differential for any athlete that participates in high-intensity interval training.