Kensuke Yamanaka

An anatomic study of the extensor tendons of the human hand

A total of 548 upper limbs (276 right and 272 left hands) from Japanese cadavers were dissected. The arrangements of extensor indicis proprius, extensor digitorum communis (EDC), and extensor digiti minimi tendons and the intertendinous connections were studied. The most common pattern of extensor tendons was as follows: the index finger had a single EDC tendon, the middle finger had a single EDC tendon, the ring finger had a single EDC tendon, and the small finger had a single EDC tendon or a single common EDC tendon distributed to the ring and small finger. A single extensor indicis proprius tendon ran along the ulnar side of the EDC, and the extensor digiti minimi tendon consisted of 2 slips. Intertendinous connections were classified into 3 types: type 1 with a filamentous band, type 2 with a fibrous band, and type 3 with a tendinous band subdivided to r-shaped and y-shaped. The most common patterns were type 1 in the second intermetacarpal space (IMCS), type 3r in the third IMCS, and type 3y in the fourth IMCS.

Locking of the metacarpophalangeal joint of the thumb.

We clinically examined the hands of twenty-three patients and experimented with amputation specimens to clarify the characteristic features and pathomechanism of locking of the metacarpophalangeal joint of the thumb. In all of the patients the locking had resulted from forced hyperextension of the thumb. Every injured thumb showed a mild hyperextension deformity of the metacarpophalangeal joint, with the joint having become fixed. Manual reduction was successful in seven patients, but the other sixteen required open reduction, during which we found that the proximal palmar ligament was ruptured transversely with its distal part riding over the volar prominence of the radial condyle of the metacarpal together with the accessory collateral ligament. These dislocated parts of the ligament formed a constricting bundle on the distal joint surface of the condyle that prevented closed reduction. The locking was released by cutting the constricted ligament bundle. Our description of this mechanism is supported by the experimental evidence that we obtained from examining the amputation specimens.

Successful manual reduction of locked metacarpophalangeal joints in fingers.

Background: Many studies on the etiology and operative treatment of locked metacarpophalangeal joints in fingers have been reported, but there have been few investigations on manual reduction. The rate of success of manual reduction in previous reports has been low, and no consensus has been reached with regard to the best method of manual reduction. On the basis of our experience with operative treatment, we devised a safe method of manual reduction. Methods: Between January 1987 and December 1995, we reduced a locked metacarpophalangeal joint in twelve female patients; every locked finger was successfully reduced, and complications such as fracture did not occur during manual reduction. The average duration of follow-up was five years and nine months (range, three years and two months to nine years and three months). Results: Six patients had no recurrence of the locking. Four of the six remaining patients had one or two incidents of locking, had no alteration in the activities of daily living, and did not want operative treatment. The two remaining patients reported that they had incidents of locking several times a day, and they requested operative treatment as they were afraid of additional recurrences. One patient had an open reduction fifteen months after the initial episode of locking, and the other patient elected not to have an operation for personal reasons. Conclusions: We believe that our method of manual reduction should be used to treat a locked metacarpophalangeal joint in a finger and that operative treatment should be limited to patients in whom manual reduction is unsuccessful or the reduction is unstable.

Progression from calcifying tendinitis to rotator cuff tear

Abstract. This report documents the clinical, radiographic and histologic findings in a 46-year-old man with calcifying tendinitis in his left shoulder which progressed to rotator cuff tear. The patient had a 1-year history of repeated calcifying tendinitis before being referred to our hospital. On the initial visit, radiographs and magnetic resonance imaging (MRI) revealed calcium deposition localized in the supraspinatus tendon without apparent tear. Three months after the first visit, MRI revealed a partial-thickness rotator cuff tear at the site of calcium deposition. Surgical and histologic findings demonstrated that calcium deposition was the cause of cuff rupture. To our knowledge, based on a review of the English literature, this is the first case report in which the progression from calcifying tendinitis to rotator cuff tear has been serially observed.

Cytopathological study of osteosarcoma of bone.

整形外科領域における細胞診に関する報告は少ない. われわれは針生検吸引細胞診による診断を目的とし, 骨肉腫5例の腫瘍捺印細胞像について検討した. Dahlinによる組織学的分類によると骨形成型2例, 骨形成型+軟骨形成型2例, 軟骨形成型1例であった. 細胞は大小不同が強く, 多形成に富み, 細胞型出現頻度は多辺形型35～56%, 紡錘形型12～23%, 円形型9～22%, 奇怪細胞型4～15%, 多核巨細胞型5～15%であった. 核の長径は7～27μ, 類円形～ 長楕円形でクロマチンの増量をみ, ときに核内偽封入体を散見した. 背景には組織型を反映し, 骨形成型にライトグリーン好性の無構造物としての類骨組織をみ, また軟骨形成型に赤紅色のメタクロマジーを呈した軟骨基質を認めた. 光顕的細胞型と電顕像を対比するに多辺形型細胞は悪性の骨芽細胞と軟骨細胞に, 紡錘形型は悪性の筋線維芽細胞と骨芽細胞に, 円形型は悪性の骨芽細胞と軟骨細胞に, 奇怪細胞および多核巨細胞型は, 悪性の骨芽細胞, 筋線維芽細胞と軟骨細胞にそれぞれ相当するものと考えられた.