386

CASE REPORT
Partial thickness tear of the supraspinatus at themusculotendinous junction in a softball catcher
Shoji Fukuta1, Shinji Kawaguchi2, and Koichi Sairyo2
Department of Orthopaedic Surgery, National Hospital Organization Kochi National Hospital, Kochi, Japan, 2Department of Orthopedics,
Tokushima University, Tokushima, Japan

1

Abstract : We report a rare case of a partial thickness tear of the supraspinatus at the musculotendinous junction in a softball catcher. Preoperative magnetic resonance images of the shoulder showed high signal intensity
areas at the musculotendinous junction, along with discontinuity of the articular side of the supraspinatus.
Arthroscopic examination revealed articular-side partial tear at the musculotendinous junction. The patient
was able to return to playing softball 20 weeks after arthroscopic side-to-side repair. J. Med. Invest. 68 : 386-388,
August, 2021
Keywords : rotator cuff tear, supraspinatus, musculotendinous junction

INTRODUCTION
With the technological advances in imaging modalities andarthroscopic devices, partial-thickness articular-side rotator
cuff tear has recently been recognized as a clinical entity. Thereare multiple factors in the etiology of articular-side tears although they are often caused by intrinsic tendon degeneration
with aging (1). Partial-thickness articular side tear is also common in young overhead athletes, due to repetitive microtrauma
or internal impingement (2).
Partial articular supraspinatus tendon avulsion is a partial
tear that occurs primarily at the insertion of the tendon on thegreater tuberosity (3). Musculotendinous rupture of rotator cuff
muscles is very rare, and only three reports have been publishedon complete tear at the musculotendinous junction (4-6). Here,
we present a case of partial tear at the musculotendinous junction of the supraspinatus associated with overhead throwing by asoftball catcher. This is the first report of successful arthroscopic
repair for this injury.

CASE PRESENTATION
A 43-year-old right-handed man presented with a 10-month
history of right shoulder pain. The patient reported that he had
regularly played recreational softball for 30 years. He had firstexperienced pain in his right shoulder when throwing the ballfrom the catcher’s position behind home plate to second base. Thepain was felt at the late, accelerated phase of throwing. Nevertheless, he continued playing softball without seeking treatment.
The pain gradually worsened until the patient had difficulty
sleeping because of night pain. He visited a local clinic and underwent magnetic resonance (MR) imaging of the right shoulder,which showed abnormalities. He was then referred to our clinic
for further treatment. He did not have nonsteroidal anti-inflammatory drugs nor intra-articular corticosteroid injection before
Received for publication June 16, 2021 ; accepted June 30, 2021.

arrival to our clinic.
Palpation around the shoulder joint did not elicit pain. On
physical examination, his active and passive range of motion(ROM) on the affected side was the same as that on the contralateral side : flexion, 175° ; abduction, 175° ; external rotation,
60° ; and internal rotation, 2nd lumbar vertebra with the arm atthe side. O’Brien test and crank test were positive, while Neer’s
impingement sign and Hawkin’s sign were negative. No signsof shoulder instability or neurological deficit were evident. The
University of California at Los Angeles (UCLA) shoulder ratingscore (7) was 20 points.
Plain radiograph of the right shoulder showed no obvious
abnormalities. MR images showed high signal intensity areas at
the musculotendinous junction, along with discontinuity of thearticular side of the supraspinatus (Figure 1). Arthroscopic repair was performed under general anesthesia after a diagnosis ofpartial supraspinatus rupture at the musculotendinous junction.
During diagnostic arthroscopy, a 15-mm articular-side partial
tear was identified at the musculotendinous junction (Figure2A). Tear of the superior glenoid labrum was not detected androtator interval looked normal. Subacromial bursoscopy showedno tear on the bursal side. The tear at the musculotendinous
junction was repaired with one side-to-side suture placed anteriorly and securing the posterior aspect of the torn tendon to thesuperior glenoid labrum without a suture anchor (Figure 2B).
After surgery, the patient’s arm was placed in a simple slingfor 2 weeks. Passive ROM exercise was encouraged immediately
after surgery. Active ROM exercise was commenced 6 weeks
postoperatively. Twelve weeks after surgery, gentle throwing
was allowed from a short distance. He was able to return toplaying softball 20 weeks after surgery. MR images acquired at
his final follow-up 12 months postoperatively showed no abnormal signal change and restored continuity of the supraspinatus(Figure 3). The patient experienced no limitations in activities
of daily living, but pain during throwing persisted. He wasable to engage in sports activities at up to 80% of his pre-injury
level. The UCLA shoulder score improved to 31 points at the lastfollow-up.

Address correspondence and reprint requests to Shoji Fukuta, Department of Orthopaedic Surgery, National Hospital Organization
Kochi National Hospital, 1-2-25 Asakuranisimachi, Kochi city, Kochi,780-8507, Japan and Fax : +81-88-843-6385.

The Journal of Medical Investigation Vol. 68 2021

The Journal of Medical Investigation Vol. 68 August 2021
AB

Figure 1. Pre-operative magnetic resonance images : (A) T1-weighted (B) T2-weighted obliquecoronal view of the right shoulder. High signal intensity at the musculotendinous junction of thesupraspinatus suggested musculotendinous rupture (arrow).

AB

Figure 2. Arthroscopic views. (A) Musculotendinous junction disruption with exposed supraspinatus
muscle (arrows). (B) After repair of musculotendinous junction.

AB

Figure 3. Postoperative magnetic resonance images : (A) T1-weighted and (B) T2-weighted obliquecoronal view of the right shoulder. Continuity of the supraspinatus was observed and the high signal
intensity at the musculotendinous junction disappeared.

387

388

S. Fukuta, et al. Musculotendinous junction tear

DISCUSSION
Musculotendinous injuries of the upper and lower extremities
are well-described clinical entities (8), though these injuries
rarely occur in the rotator cuff. Several case series have beenreported, along with the pathology and natural history of musculotendinous rupture of the infraspinatus (9, 10). However,
only 7 cases of complete rupture of the supraspinatus at themusculotendinous junction have been reported in the literature(4-6). Lädermann et al. (4) presented a series of supraspinatus injuries at the musculotendinous junction in which 5 patients had
a definitive history of acute trauma, while 2 had no history oftrauma. Characteristic MR imaging findings in the acute phaseof the injury are muscular edema at the musculotendinous junction, similar to that observed in the musculotendinous rupture of
the infraspinatus (9, 10). Although the mechanism of this injury
remains unclear, inlet impingent secondary to acromioclavicularosteoarthritis might lead to a predisposition to rupture at themusculotendinous junction.
In our case, the MR imaging of the right shoulder was acquired 10 months after the onset of symptoms, so muscle edema
could not be detected. An area of high signal intensity at themusculotendinous junction with discontinuity of the articularside of the supraspinatus was the only significant finding. In contrast to a report by Lädermann et al. (4), our patient had no abnormality in the acromioclavicular joint and the partial rupture
was located on the articular side. Hence, the musculotendinous
rupture may have occurred as a result of eccentric contraction
during throwing or repeated overhead activity.
There is no consensus regarding the ideal treatment protocol
for rupture at the musculotendinous junction. Of the 7 reported
cases of supraspinatus musculotendinous rupture, 6 cases weremanaged conservatively and the remaining case was managed
by surgery for open side-to-side repair of the musculotendinous
junction. At the latest follow-up, 2 of the conservatively managed
cases showed a complete recovery, 1 showed improvement, and 3
complained of loss of function. In a case series of musculotendinous rupture of the infraspinatus presented by Walch et al. (10),the authors noted that early tendon repair to restore muscle
tension in the infraspinatus might prevent the progression ofmuscle function loss. Lädermann et al. (4) proposed non-surgicalmanagement of incomplete injuries. The natural history of acomplete rupture at the musculotendinous junction of supraspinatus entails rapid fatty infiltration and functional deterioration. Recent developments in arthroscopic techniques offersome advantages for managing the chronic symptoms of partial

rupture in patients who participate in overhead sports.
We reported an uncommon case of partial tear of the supraspinatus at the musculotendinous junction in a throwing
athlete. High signal intensity areas at the musculotendinous
junction on MR images are useful for the diagnosis. This type ofinjury should be taken into consideration for a painful throwingshoulder.

REFERENCES
1.

Fukuda H, Hamada K, Nakajima T, Yamada N, Tomonaga
A, Goto M : Partial-thickness tears of the rotator cuff : aclinicopathological review based on 66 surgically verified
cases. Int Orthop 20 : 257-65, 1996
2. Connor PM, Banks DM, Tyson AB, Coumas JS, D’Alessandro
DF : Magnetic resonance imaging of the asymptomatic
shoulder of overhead athletes : a 5-year follow-up study. AmJ Sports Med 31 : 724-7, 2003
3. Snyder SJ, Pachelli AF, Del Pizzo W, Friedman MJ, Ferkel
RD, Patte G : Partial thickness rotator cuff tears : results ofarthroscopic treatment. Arthroscopy 7 : 1-7, 1991
4. Lädermann A, Christophe FK, Denard PJ, Walch G : Supraspinatus rupture at the musclotendinous junction : anuncommonly recognized phenomenon. J Should Elb Surg
21 : 72-76, 2012
5. Benazzo F, Marullo M, Pietrobono L : Supraspinatus rupture at themusculotendinousjunctionin a young woman. JOrthop Traumatol 15 : 231-234, 2014
6. Hertel R, Lambert SM : Supraspinatus rupture at the musculotendinous junction. J Shoulder Elbow Surg 7 : 432-435,
1998
7. Bosch U, Skutek M, Fremerey RW, Tscherne H : Outcome
after primary and secondary hemiarthroplasty in elderly
patients with fractures of the proximal humerus. J ShoulderElbow Surg 7 : 479-84, 1988
8. Zarins B, Ciullo JV : Acute muscle and tendon injuries inatheletes. Clin Sports Med 2 : 167-182, 1983
9. Lunn JV, Castellanos-Rosas J, Tavernier T, Barthélémy R,
Walch G : A novel lesion of the infraspinatus characterizedby musculotendinous disruption, edema, and late fatty infiltration. J Shoulder Elbow Surg 17 : 546-553, 2008
10. Walch G, Nové-Josserand L, Liotard JP, Noël E : Musculotendinousinfraspinatusruptures : an overview. OrthopTraumatol Surg Res 95 : 463-470, 2009