Involvement of the Subscapular Bursa as a Cause
of Throwing Pain
Hiroaki Inui*, Katsuya Nobuhara
Nobuhara Hospital & Institute of Biomechanics, Japan
Hiroaki Inui, Nobuhara Hospital & Institute of Biomechanics, 720 Haze, Issaicho, Tatsunoshi, Hyogo 679-4017, Japan, Tel:
81-0791-66-0981; Fax: 81-0791-66-2687; E-mail:
Received: June 29, 2015; Accepted: August 22, 2015; Published: September 29, 2015
Little attention has been paid to a role of the subscapular bursa
keeping smooth movement of the shoulder. We hypothesized
that irritation in the subscapular bursa causes throwing pain
and investigated in which position pain would occur in a clinical
scenario and effectiveness of distension arthrography for pain relief
in baseball players. One hundred and ten baseball players with
shoulder pain were enrolled in this study. All underwent examination
of whether pain was provoked with arm rotation at different angles
of abduction before and after arthrography. Factors including skill
level, playing position, symptom duration, and concurrent injury of
the rotator cuff tendon were investigated to affect the results. All
patients experienced pain with external rotation at 135° of abduction
before arthrography, and the pain was reduced after arthrography in
92 players (84%). Thirty-three patients could continue their playing
level 6 months after treatment, while 59 players experienced pain
recurrence. Eighteen patients (16%) could not return to their playing
level without treatment efficacy. Symptom duration was the only
additional factor that affected the results. Irritation in the subscapular
bursa plays a role in the development of disabled throwing shoulders.
Distension arthrography is an effective procedure for pain relief.
Keywords: Subscapular bursa; Throwing injury; Baseball
Bursae exist in many parts of the body where a considerable
degree of motion between parts of the anatomy occurs but
where no cartilaginous joint is required . Particularly in areas
of the shoulder joint where the muscles or tendons and bones
cross each other, bursae between them play important roles in
maintenance of joint function . Many previous studies have
clarified both anatomically and clinically that the subacromial
bursa helps the greater tuberosity of the humerus to smoothly
glide under the coracoacromial arch [2-6]. However, only a
few studies have investigated the subscapular bursa [7,8] and
the clinical importance of this bursa remains incompletely
understood [9,10]. Colas et al.  studied the course of the
subscapularis muscle and the anatomy of the subscapular and
subcoracoid bursae. Their cadaveric study indicated that the
superior distal band of the subscapularis muscle coils along the
coracoid process during external rotation in elevation and that the bursae play an important role in the suppression of friction
associated with those movements. We hypothesized that friction
of the subscapularis tendon coiling along the coracoid process
often causes pain during throwing motion and investigated in
which position pain would occur in a clinical scenario.
This study involved 110 baseball players who visited our
hospital for consultation regarding their symptoms and who
were followed up for at least 6 months. All were men with an
average age of 27 years (range, 16–36 years). The dominant
arm was affected in all players. The subjects comprised 52 high
schooling, 11 collegiate, 9 professional, and 38 recreational level
players. Their baseball playing positions were 50 pitchers, 9
catchers, 19 infielders, and 32 outfielders.
All players complained of shoulder pain during throwing,
especially in the acceleration phase, and stated that their
performance level was decreased owing to throwing pain. The
passive glenohumeral range of motion was assessed using a
large goniometer. Angles of internal and external rotations in
the coronal plane at 90° of abduction were measured in bilateral
sides. Measurements were recorded with each subject lying
supine to stabilize the scapula. The dominant extremity showed
more external rotation at 90° of abduction and less internal
rotation at 90° of abduction than did the contralateral extremity.
The mean external rotation and internal rotation with the
dominant extremity were 105° ± 13° and 50° ± 12°, respectively,
and those with the contralateral extremity were 101° ± 14° and
59° ± 11°, respectively.
Ten milliliters of dye compounded with 10 ml of local
anesthetic was injected into the joint. In 29 patients (26%),
leakage or pooling of the dye in the supraspinatus or infraspinatus
tendons occurred (Figure 1). After evaluation, the shoulder was
forced to internally rotate to distend the dye to the subscapularis
bursa. This direction of dye distension was confirmed with plain
radiographs after arthrography (Figure 2). In 14 patients, the dye
also leaked from the bicipital groove.
Figure 1: The antero-posterior x-ray image with the arm internally rotated
shows the leakage of the dye into the ISP tendon (the white arrow),
indicating its tendon injury.
Figure 2: a. The anterior-posterior x-ray image shows the dye bursting
to the medial side below the coracoid process. b. The scapular Y view of
the same patient shows the dye bursting anterior to the bone. The images
indicated the dye distended to the subscapular bursa.
Evaluation and statistical analysis
The patients were examined to determine in which position
their pain was provoked. The treatment was considered effective
when pain was not provoked with arm rotation 1 or 2 weeks
after arthrography. The patients were divided into three groups
according to whether they could return to their premorbid
playing level: Group A could play at their preinjury level 6 months
after the treatment; in Group B, the treatment was effective,
but pain was either not adequately reduced to return to their
premorbid playing level or recurred in 6 months; and in Group C,
the treatment was not effective and patients could not return to
their playing level. Factors including skill level, playing position,
symptom duration, and concomitant injury of the rotator cuff
tendon were investigated with respect to their ability to affect
the arthrography outcome.
Fisher's exact probability test was used to detect statistical
differences between two groups regarding the results, and a
statistically significant difference was considered to exist at p <
0.05. The chi-square test was used for statistical analysis across
Pain tended to be provoked with greater arm raising and
extension (Table 1), and pain was provoked in all patients by
external rotation at 135° of abduction (Figure 3). Pain with
external rotation at 135° degrees of abduction decreased after arthrography in 92 players (84%). Thirty-three patients could
continue at their playing level 6 months after treatment (Group
A), while 59 patients either did not have adequate pain relief to
return to their premorbid playing level or the pain recurred in
6 months (Group B). Eighteen patients (16%) were not relieved
from pain and could not return to their playing level (Group C).
We divided the subjects into four subgroups according to
playing level. These four subgroups comprised 48 high schooling,
9 collegiate, 8 professional, and 27 recreational level players.
Group A included 14 high school, 4 collegiate, 2 professional, and
13 recreational players; Group B, 34 high school, 5 collegiate, 6
professional, and 14 recreational players; and Group C, 4 high
school, 2 collegiate, 1 professional, and 11 recreational players.
Skill level did not affect the arthrography outcome (Table 2).
Baseball playing position
The patients comprised 46 pitchers, 5 catchers, 14 infielders,
and 27outfielders. Group A included 15 pitchers, 3 catchers, 7
infielders, and 8 outfielders; Group B, 31 pitchers, 2 catchers, 7
infielders, and 19 outfielders; and Group C, 4 pitchers, 4 catchers,
5 infielders, and 5 outfielders. Playing position did not affect the
arthrography outcome (Table 3).
Fifty-one patients were treated for less than 3 months after
symptom onset, and their symptom duration was considered to
be short. Fifteen patients with short-duration and 18 patients
Table 1: Percentage of players with provoked rotational pain at different
Figure 3: Pain was provoked with the arm externally rotated in 135
degrees of abduction.
with long-duration symptoms belonged to Group A, 33 with
short-duration and 26 with long-duration symptoms belonged to
Group B, and 3 with short-duration and 15 with long-duration
symptoms belonged to Group C. There were more patients with
short-duration symptoms in Groups A and B than in Group C
(Fisher's exact probability test, P = 0.009) (Table 4).
Concomitant injury in rotator cuff tendon
Twenty-nine patients demonstrated pooling of dye in the
rotator cuff, indicating injury to this structure. Nine patients
with cuff tears and 24 without cuff tears belonged to Group A,
16 with cuff tears and 43 without cuff tears belonged to Group
B, and 4 with cuff tears and 14 without cuff tears belonged to
Group C. Tendon injury did not affect the result. In fact, a higher
proportion of rotator cuff injury was noted in patients in Groups
A and B, in whom the treatment proved effective (Table 5).
Many lesions are reportedly associated with throwing
injuries, including articular sided tears of the supraspinatus or
infraspinatus muscle, labral lesions, Bennett lesions, humeral
head lesions or cysts, and glenoid bony lesions [11-19]. However,
most disabled throwing shoulders improve without surgical
intervention, and the findings of such lesions are not always
related to the patient's symptoms [15,20,21], suggesting other
causes of the shoulder disability.
The subscapularis bursa lies between the subscapularis
muscle and scapula under the coracoid process. The bursa
helps the subscapularis muscle to coil around the coracoid
process, especially during external rotation in elevation [8,22].
Table 2: Skill level.
Effective (A & B)
Not effective (C)
Table 3: Baseball playing position.
Effective (A & B)
Not effective (C)
Table 4: Symptom duration.
less than3 months
3 months or more
Effective ( A & B)
Not effective (C)
Table 5: Combined injury.
Cuff tear +
Cuff tear -
Effective (A & B)
Not effective (C)
Irritation in this bursa may disturb throwing motion, and the
arm is forced to rotate in such situations. In fact, pain tends to
be provoked during external rotation with greater arm elevation
and horizontal abduction in the clinical setting. The current study
also showed that filling the joint and its bursa with liquid dye
after arthrography reduced rotational pain in 84% of the players.
The arm position relative to the trunk during throwing is
approximately 90° to 100° of abduction . In the present
study, there was a discrepancy in comparison of the angle of
abduction at which pain was provoked. We surmised that the
reason for this discrepancy was that the arm was examined
passively. During actual throwing activity, the scapulohumeral
relationship approaches that with the arm passively elevated at
135° of abduction to generate rotational torque.
More patients in Groups A and B had short-duration symptoms
(< 3 months) than in Group C, indicating that treatment efficacy
is affected by symptom duration. If athletes with symptomatic
shoulders continue playing baseball without treatment, their
condition will worsen to more advanced stages until no treatment
is effective. Friction of the subscapularis tendon might cause
inflammation in the subscapular bursa. When inflammation
is localized, it may resolve spontaneously. However, in more
advanced stages, irritation in the bursa becomes extensive, and
adhesion may develop, disturbing the gliding motion of the
tendon. Restriction in the glenohumeral joint movement might
affect coordination of the glenohumeral, scapulothoracic, and
trunk movements, decreasing throwing performance or causing
other injuries. Thus, we should educate athletes and their coaches
to address throwing disability as quickly as possible.
Group B included patients whose symptoms recurred in less
than 6 months despite the fact that distension arthrography
temporarily relieved their pain. Some shoulder joint
characteristics, including subtle instability, might predispose a
player to developing symptom recurrence; however, the current
study could not elucidate why their throwing pain recurred.
Further shoulder examination for subtle instability or throwing
motion analysis to investigate abnormal biomechanics is needed.
If the cause of throwing pain is known, training for proper
throwing motion could prevent recurrence.
To our knowledge, no author has ever pointed out the
importance of the subscaplar bursa causing throwing pain.
Hopefully, function of the subscapular bursa should be highlighted
and more attention should be paid to its anatomy. We think
physical therapies can alleviate further inflammation or damage
with continued throwing by approaching scapular position or
orientation. Myers et al.  demonstrated the scapula tipped
posteriorly until maximum glenohumeral external rotation
during throwing motion. Stretching the pectoralis minor muscle
 might help this posterior tipping of the scapula and decrease
glenohumeral contribution at maximum shoulder external
rotation in throwing.
This retrospective study had some limitations. We could
not determine in which cases distension arthrography would
be effective. Additionally, we could not determine how involvement of the subscapular bursa relates to previously
reported pathological conditions such as internal impingement
[16,19], glenohumeral internal rotation deficit , or SICK
scapula syndrome . Further prospective studies with larger
population are needed.
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