Visual Observation of Apparent Infraspinatus Muscle Atrophy in Male Professional Tennis Players.
Orthop J Sports Med 2020;
8:2325967120958834. [PMID:
33195711 PMCID:
PMC7605003 DOI:
10.1177/2325967120958834]
[Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 04/22/2020] [Indexed: 12/04/2022] Open
Abstract
Background:
Previous studies have reported visually observed apparent muscle atrophy in
the infraspinous fossa of the dominant arm of overhead athletes. Several
mechanisms have been proposed as etiological factors, including eccentric
overload, compressive spinoglenoid notch paralabral cysts, and cumulative
tensile suprascapular neurapraxia.
Purpose:
To report the prevalence of apparent infraspinatus atrophy in male
professional tennis players and to determine whether the suspected atrophy
correlates with objectively measured weakness of external rotation.
Study Design:
Cross-sectional study; Level of evidence, 3.
Methods:
A total of 153 male professional tennis players underwent a musculoskeletal
screening examination that included visual inspection of the infraspinous
fossa. Infraspinatus atrophy was defined as hollowing or loss of soft tissue
bulk inferior to the scapular spine in the infraspinous fossa of one
extremity that was visibly different from the contralateral extremity. This
finding was observed and independently agreed upon by both an orthopaedic
surgeon and a physical therapist during the examination. Also assessed were
rotator cuff instrument-assisted manual muscle testing, visual observation
of scapular kinesis (or motion), and glenohumeral joint range of motion for
internal and external rotation and horizontal adduction.
Results:
In the 153 players, dominant-arm infraspinatus atrophy was observed in 92
players (60.1%), and only 1 player (0.7%) was identified with nondominant
infraspinatus atrophy. A Pearson correlation showed a significant
relationship between the presence of dominant-arm infraspinatus atrophy and
dominant-arm external rotation strength measured in neutral
abduction/adduction (at the side) (P = .001) as well as
between the presence of dominant-arm infraspinatus atrophy and bilateral
external rotation strength measured at 90° of glenohumeral joint abduction
(P = .009 for dominant arm and .002 for nondominant
arm). No significant correlation was found with scapular dyskinesis,
glenohumeral range of motion, or instrument-assisted manual muscle testing
of the supraspinatus (empty-can test).
Conclusion:
Visually observed infraspinatus muscle atrophy is a common finding in the
dominant shoulder of asymptomatic male professional tennis players and is
significantly correlated with external rotation weakness. This condition is
present in uninjured players without known shoulder pathology and is not
related to glenohumeral joint internal rotation, total rotation range of
motion, or scapular dysfunction. Players with visually observed
infraspinatus atrophy should be evaluated for external rotation strength and
may require preventive strengthening.
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