Joint capsule attachment to the extensor carpi radialis brevis origin: an anatomical study with possible implications regarding the etiology of lateral epicondylitis.
OBJECTIVE
To identify the unique anatomical characteristic of the extensor carpi radialis brevis (ECRB) origin and points of differentiation from other extensors and to clarify the specific relationship of the ECRB to the underlying structures.


METHODS
We studied the origin of each extensor macroscopically for its muscular and tendinous parts; to identify the relationship between the ECRB origin and the deeper structures, we also examined the attachment of the joint capsule under the ECRB origin.


RESULTS
The ECRB simply originated as a tendon without any muscle, whereas other extensors originated as a mixture of tendon and muscle. At the anterior part of the ECRB origin, the thin attachment of the joint capsule (average width, 3.3 mm) lay deep to the ECRB and was distinct. However, at the posterodistal portion, the joint capsule, annular ligament, and supinator were intermingled and originated as a single wide sheet from the humerus (average width, 10.7 mm).


CONCLUSIONS
The anterior part of the ECRB origin was delicate, because the ECRB origin was purely tendinous, and the attachment of the articular capsule was thin compared with that of the posterodistal attachment. This thin attachment could be an initial factor leading to the development of lateral epicondylitis.


CONCLUSIONS
The results of the current study may enhance magnetic resonance imaging understanding and may help clarify the etiology of the lateral epicondylitis.
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan.
Akimoto
A
Nimura
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan.
Hitomi
H
Fujishiro
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan.
Yoshiaki
Y
Wakabayashi
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan.
Junya
J
Imatani
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan.
Hiroyuki
H
Sugaya
Unit of Clinical Anatomy, and the Department of Orthopaedic Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo; the Department of Orthopaedic Surgery, Okayama Saiseikai General Hospital, Okayama; and the Shoulder and Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Japan. Electronic address: akita.fana@tmd.ac.jp.
Keiichi
K
Akita
D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006811:Humerus / Q000473:pathology; D017746:Joint Capsule / Q000473:pathology*; D008023:Ligaments, Articular / Q000473:pathology; D008297:Male; D012016:Reference Values; D012307:Risk Factors; D013484:Supination / Q000502:physiology; D013710:Tendons / Q000473:pathology*; D013716:Tennis Elbow / Q000473:pathology*
Lateral epicondylitis; articular capsule; extensor carpi redialis brevis; supinator; tennis elbow