Junya Imatani

Anatomic and histologic studies of lateral collateral ligament complex of the elbow joint.

We studied the gross and histologic anatomic characteristics of the lateral collateral ligament complex of the elbow joint from 15 cadavers to demonstrate its cross-sectional anatomy. The lateral ulnar collateral ligament adheres closely to the supinator, the extensor muscles, its intermuscular fascia, and the anconeus muscle and lies posterior to the radial collateral ligament. The lateral ulnar collateral ligament itself was identified with microscopy as a slender, poor structure consisting of the thick area of the posterolateral capsuloligamentous layer and a poorer structure than the anterior bundle of the medial collateral ligament as the primary stabilizer of the elbow joint. We believe that the lateral ulnar collateral ligament contributes to rather than is a major constraint to the posterolateral rotatory instability as part of the lateral collateral ligament complex with the surrounding tissues.

Fractures of the Base of the Middle Phalanx of the Finger

We classified fractures of the base of the middle phalanx into five types: 1) single palmar fragment; 2) single dorsal fragment; 3) two main fragments; 4) not involving the articular surface, including epiphyseal separation in children; and 5) all others. Types 1 and 2 were subclassified into avulsion, split and split-depression. Surgery is recommended for unstable type-1 avulsion fractures, type-2 avulsions which may develop buttonhole deformities, and all fractures which displace articular cartilage surfaces. Long-term follow-up showed that surgical treatment which produced good stability and congruity gave good results. These should be the primary aims of treatment.

An anatomical study of the watershed line on the volar, distal aspect of the radius: implications for plate placement and avoidance of tendon ruptures.

PURPOSE The watershed line is a useful surgical landmark for positioning a volar locking plate. Implants placed on or distal to it can impinge on flexor tendons and cause injury. However, the details of the anatomy of this line are unclear. We studied macroscopically and histologically the structures of the volar aspect of the distal radius. METHODS We studied 20 distal forearm regions of 10 cadavers (5 males and 5 females; mean age, 79 y [range, 56-88 y]) to clarify the details of the watershed line. In 16 specimens, we investigated the macroscopic appearance of the volar aspect of the radius and the relationships among the bone, the volarradiocarpal ligaments, and the pronator quadratus. Histological analyses were performed in 4 specimens of 2 cadavers to examine the morphology of the margin of the bony structures. RESULTS In the medial half of the distal volar radius, 2 lines were identified by direct macroscopic visualization; one was the proximal line that corresponded to the distal ridge of the pronator fossa, and the other was the distal line, which was more prominent. A medial bony prominence was situated on the distal line. In the lateral half, the distal and proximal lines of the medial half merged to form a single line. A lateral prominence was situated on this line. CONCLUSIONS The watershed line might not be a distinct line, and it corresponds to the distal margin of the pronator fossa in the lateral half of the volar radius and to a hypothetical line between the distal and proximal lines in the medial half. The medial and lateral bony prominences on the volar radius should be key structures for accurate plate placement to avoid flexor tendon injury. CLINICAL RELEVANCE The present study suggests bony landmarks for positioning a volar locking plate.

Joint Capsule Attachment to the Extensor Carpi Radialis Brevis Origin: An Anatomical Study With Possible Implications Regarding the Etiology of Lateral Epicondylitis

PURPOSE 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. CLINICAL RELEVANCE The results of the current study may enhance magnetic resonance imaging understanding and may help clarify the etiology of the lateral epicondylitis.

The Galeazzi-Equivalent Lesion in Children Revisited

A fracture at the medial end of the distal third of the radius with an epiphyseal separation of the distal ulna in a 16-year-old boy is described. This injury, known as the Galeazzi-equivalent lesion in children, is characterized by complete distal ulnar epiphyseal separation without rupture of the distal ligamentous stabilizing system between the radius and ulna, which includes the triangular fibrocartilage complex, interosseous ligaments and periosteal tube of the ulnar. The Galeazzi fracture-dislocation and the Galeazzi-equivalent lesion appear to be completely dissimilar in their pathological anatomy. We suggest calling the latter a “pseudo-Galeazzi injury”.

FRACTURES OF THE BASE OF THE MIDDLE PHALANX OF THE FINGER

We classified fractures of the base of the middle phalanx into five types: 1) single palmar fragment; 2) single dorsal fragment; 3) two main fragments; 4) not involving the articular surface, including epiphyseal separation in children; and 5) all others. Types 1 and 2 were subclassified into avulsion, split and split-depression. Surgery is recommended for unstable type-1 avulsion fractures, type-2 avulsions which may develop buttonhole deformities, and all fractures which displace articular cartilage surfaces. Long-term follow-up showed that surgical treatment which produced good stability and congruity gave good results. These should be the primary aims of treatment.

Acute posterolateral rotatory subluxation of the elbow joint. A case report.

The elbow joint has become increasingly recognized as a very important joint for all sports activities. Players in some sports cannot compete at all with an unstable elbow due to ligament injuries. Thus, professional sports players and heavy laborers, as in our case, should find the excellent results of primary ligament repair preferable. This technique is less invasive than secondary ligament reconstruction and can result primarily in an accurate, stable elbow with full range of motion for mobilizing the joint and muscles at an early stage.

Volar Distal Radius Anatomy Applied to the Treatment of Distal Radius Fracture

Volar locking plate (VLP) fixation has become the standard surgical treatment for distal radius fractures. However, flexor tendon rupture is one of the major complications following volar plating. This detailed review on the anatomy and morphology of the volar distal radius might facilitate appropriate placement of the volar plate and thereby avoid flexor tendon rupture. We introduce safe and secure VLP fixation along standard surgical procedures to avoid complications based on anatomy of the volar surface of the distal radius.