"Floating thumb metacarpal" or complete dislocation of the thumb metacarpal: a case report and review of the literature

We present a case of a patient with a simultaneous dislocation of the metacarpophalangeal (MP) and the carpometacarpal (CMC) joint of the thumb as an isolated injury, and we review the relevant literature. We found only three previous reports in the literature, two reports as an isolated injury and another similar injury combined with a carpometacarpal fracture-dislocation of all four fingers. A closed reduction of both joints followed by an open repair of the torn ulnar collateral ligament of the MP joint and Kirschner-wire (K-wire) stabilization of the CMC joint led to a good result at 1 year. This rare injury has been described as a "complete dislocation of the thumb metacarpal" or as a "simultaneous dislocation of the MP and CMC joints of the thumb". We suggest it is a "floating thumb metacarpal".     

Isolated dislocation of the four ulnar carpometacarpal joints

Dislocation of the multiple carpometacarpal joints without associated fractures of the metacarpal and/or carpal bones is an exceedingly rare injury. An earlier belief that carpometacarpal dislocations are high-energy injuries is questioned due to an unusual case of isolated dislocation of the four ulnar metacarpals that occurred after a relatively minor hand trauma. Early recognition and anatomical reduction are essential to achieving good long-term outcomes. Massive edema, interposed volar ligaments and overlapping metacarpal bases are the usual obstacles to a successful closed reduction.     

Neglected floating fifth metacarpal: a case report

Simultaneous dislocation of the metacarpophalangeal and carpometacarpal joint has been previously reported. Floating metacarpals occur when the metacarpal head displaces volarly and the base displaces towards the dorsal side. A closed dislocation at both ends of the fifth ray is unusual. In this study, we report a neglected case of floating fifth ray and its management along with a review of the literature.     

An isolated ring finger metacarpal shaft fracture?--beware an associated little finger carpometacarpal joint dislocation

Dislocations of the ulnar carpometacarpal joint are easily missed because of a low index of suspicion as well as their subtle clinical and radiological features. Often, the presence of a more obvious adjacent injury also draws attention away from the carpometacarpal joint. Two cases of ring finger metacarpal shaft fractures with associated little finger carpometacarpal joint dislocations are presented. In both cases, the metacarpal fractures were diagnosed but the carpometacarpal joint dislocations were initially overlooked. The presence of an apparently isolated ring finger metacarpal fracture due to an indirect force should raise the possibility of an associated carpometacarpal joint injury.     

Proximale Metakarpalfrakturen mit Gelenkbeteiligung

Intraarticular fractures of the base of the first metacarpal that have healed in displaced position quickly lead to posttraumatic arthritis. After satisfactory closed reduction a percutaneous pin fixation is sufficient, if necessary combined with fixation of the first metacarpal. If closed reduction cannot be obtained, open reduction with pin fixation, or rigid fixation with screws or plates, is advisable. Displaced fractures of the metacarpal base of the fingers also lead to posttraumatic arthritis with a weak grip. Displaced fractures and dislocated fractures require reduction and percutaneous or internal fixation with K-wires and possibly additional pin fixation of the carpometacarpal joints.     

Divergent fracture-dislocation of the hamatometacarpal joint: case report

Hamatometacarpal fracture-dislocation is a rare injury that consists of a fourth metacarpal fracture and a fifth carpometacarpal joint injury. We present the case of a 21-year-old man with a divergent hamatometacarpal fracture-dislocation that consisted of a combination of dorsal intra-articular fracture-dislocation of the fourth carpometacarpal joint, palmar dislocation of the fifth carpometacarpal joint, and fracture of the hook of the hamate. The mechanism of palmar dislocation of the fifth metacarpal base and fracture of the hook of the hamate involved extension of the fifth metacarpal and ulnopalmar load transmission.     

Divergent fracture-dislocation of the second carpometacarpal joint and the three ulnar carpometacarpal joints

A case of divergent dislocation between the second metacarpal and the three ulnar metacarpals is presented. Severe edema, fragments of the trapezoid, and interposed volar ligaments prevented successful closed reduction. Open reduction enabled restoration of the carpometacarpal complex with excellent recovery of hand function.     

Multiple volar dislocations of the carpometacarpal joints with an associated fracture of the first metacarpal base

Multiple pometacarpal （CMC） joints volar dislocations of car- are uncommon and have been reported rarely. A 25 years old male presented with injury to his left hand 6 days following a road traffic accident. Clini- cal examination revealed gross swelling of the hand and diffuse tenderness over the carpometacarpal area. His ra- diographs of the hand showed volar dislocation of the second, third and fourth CMC joints in association with anextra-articular fracture of the base of thumb metacarpal. He was treated by open reduction and percutaneous fixation using Kirschner wires. The functional results were excellent at one year follow-up.     

Unstable dorsal fractrue-dislocation of the fifth carpometacarpal jont

Four cases of unstable fracture-dislocation of the fifth carpometacarpal joint are reproted, including 3 isolated dorsal fracture-dislocation and 1 dorsal fracture-dislocation associated with a fracture of the fourth metacarpal bone. All cases required open reduction and Kirschner wire fixation which resulted in good function. Attention is drawn to the frequent delay in diagnosis. The applied anatomy is discussed.     

The safest direction of percutaneous pinning for achieving firm fixing of the fifth carpometacarpal joint

IntroductionTraditional treatment of unstable fifth carpometacarpal joint injuries is closed reduction and pinning. The purpose of this study was to determine the safest corridor for pinning of the fifth carpometacarpal joint to prevent iatrogenic injury to the ulnar nerve and tendons.Materials and methodsIn the first phase of study, three fresh cadavers were dissected and the safest directions of Kirschner wire (k-wire) insertion in the coronal and sagittal planes were determined for k-wire entrance 2 cm distal to the base of the fifth metacarpal. The second phase objective was to evaluate the accuracy of data obtained in the previous phase. Therefore, with five other cadavers, k-wires were inserted in a combination of maximum angles in different planes determined previously. The ulnar nerve branches and tendons were then investigate to detect possible damage. In the third phase, four fresh carpometacarpal joints were fixed with directions outside the range of the defined angles.ResultsThe safe direction determined in the first phase was a 20°–30° coronal plane angle relative to the body of the fifth metacarpal bone and between 10° volar to dorsal to 20° dorsal to volar angle in the sagittal plane. Insertion of k-wires in the second phase could fix the fifth carpometacarpal joint firmly without penetration of the volar and dorsal cortices of the hamate. All inserted k-wires outside the defined range resulted in injuries to nerves or tendons or loose fixing.ConclusionThe safest corridor for pinning unstable fifth carpometacarpal injuries is 2 cm distal to the joint at an angle of 20°–30° to the coronal plane from 10° volar to dorsal to 20° dorsal to volar direction in the sagittal plane.     

Isolated dislocation of the second metacarpal at both ends

A dislocation of the second metacarpal at both ends is reported herein for the first time. Six weeks after injuring her right hand in a fall while climbing stairs, a 34-year-old woman visited our clinic with pain, swelling, and deformity of her hand. The radiographs showed a volar dislocation of the head and a dorsal dislocation of the base of the second metacarpal. The probable mechanism of injury was the hyperextension at the metacarpophalangeal joint; this force dislocated the metacarpal head toward the volar plate. Force then further continued along the second metacarpal shaft in the hyperflexed wrist, thus dislocating the base dorsally. We performed an open reduction and K-wire fixation of the second metacarpophalangeal joint and an arthrodesis of the second carpometacarpal joint. At the six-month follow-up, the patient had restricted flexion (0 to 50 degrees) at the second metacarpophalangeal joint, but full range of motion at the interphalangeal joints. The grip strength on the right side was 70% of that measured in the uninvolved hand. Key Words: Dislocation, Second metacarpal.     

Carpometacarpal dislocation: an aid to diagnosis.

Although the 'true' lateral radiograph of the hand has improved diagnosis of carpometacarpal dislocation, cases can still be missed if only the carpometacarpal joint area is inspected, as overlap of the adjoining joints can make interpretation difficult. Measurement of the angle between the long axis of the second and fifth metacarpal bones on a true lateral radiograph, in cases of fifth carpometacarpal dislocation is advocated, as the carpometacarpal angle is increased compared with controls (38.5 degrees compared with 9.8 degrees). A lesser increase in the carpometacarpal angle is suggestive of subluxation of this joint and this should be examined under anaesthesia.     

Biomechanical investigations on the aetiology of arthrosis of the first carpometacarpal joint (author's transl)

Forty-eight carpometacarpal joints of the thumb (dissecting room material) were investigated roentgenologically and macroscopically. The localization of arthrotic lesions of the articular surfaces of the first metacarpal bone and the greater multangular bone support the view that arthrosis of the first carpometacarpal joint is due primarly to mechanical factors. The opposition movement of the thumb is combined with a pronating rotation of the first metacarpal bone. This rotation leads to an incongruity of the joint and in consequence to an extreme diminuition of the pressure transmitting area. Photoelastic experiments demonstrate that the point-like contact areas are subjected to an extremly high stress. The functional analysis of the tangential fiber layer in the articular cartilage shows that the first carpometacarpal joint is adapted only to movements typical for a saddle-shaped joint.     

鹅型外固定器治疗第一掌骨骨折

介绍一种治疗第一掌骨基底骨折的鹅型外固定器.方法 该固定器由手部部分和肘部托板部分组成.通过牵引鹅嘴使第一掌骨头背伸,鹅颈的压迫使第一掌向骨折块靠拢,达到第一掌骨基底骨折的复位和腕掌关节脱位的复位.肘部托板作为牵引的支点.固定4～6周后去除鹅型外固定器锻练活动.1990～1997年应用鹅型外固定器治疗第一掌骨基底骨折17例.Bennett’s骨折4例.结果 21例全部复位良好.随访3个月以上的16例,关节活动恢复正常.结论 该外固定器的设计符合生物力学原理,使用方便,临床应用效果满意.     

Deposition of calcium pyrophosphate dihydrate crystals in the hand

A rare case with deposition of calcium pyrophosphate dihydrate crystals around the proximal portion of the first and second metacarpal bones is reported. The second metacarpal had a cystic lesion, and the cortex of the first metacarpal had irregular osteolytic change. There were degenerative changes in the first carpometacarpal joint, trapeziotrapezoid articulation, and second carpometacarpal joint. The patient had recurrent acute inflammatory attacks at the affected site. Initially the patient was thought to have tumoral calcinosis, or a calcifying soft-tissue tumor, with the possibility of a malignant tumor because of angiographic evidence of tumor stain and hypervascularity. Surgical biopsy with partial curettage of the calcified mass resulted in early recurrence of deposition of the crystals. Total excision would seem to be necessary to avoid recurrence.     

Percutaneous intramedullary fixation of metacarpal shaft fractures

Twenty-two displaced metacarpal shaft fractures in 19 patients were stabilized with multiple intramedullary K-wires. These were inserted percutaneously through a small window in the base of the metacarpal and were buried in the bone. No external splintage was routinely used postoperatively and all patients were encouraged to mobilize their fingers immediately: formal physiotherapy was not usually required. All the fractures that we were able to follow-up united, but the K-wires bent at the fracture site in two instances, producing 20 degrees angular deformities. The buried K-wires had to be removed in one instance as a result of protrusion into the carpometacarpal joint.     

Luxation carpo-métacarpienne palmaire du cinquième doigt : à propos d’un cas

Pure carpo-metacarpal dislocations without any fracture are rare, their volar component is exceptional. Untreated injuries can result in instability and early articular degeneration. We report a 72-year-old female patient who underwent an isolated closed volar dislocation of her fifth finger carpo-metacarpal joint after a fall. The clinical examination showed a 10°-defect in rotation with limited adduction (radial deviation). The X-rays showed a gap between the base of the fourth and the fifth metacarpal bones with volar dislocation of the base of the fifth carpometacarpal joint. The dislocation was successfully treated by closed reduction maintained with two K-wires. Immobilisation of the joint was applied for 6 weeks. At 2 years follow-up evaluation, the patient was pain free with no clinico-radiological evidence of instability and had returned to her previous level of activity.     

Simulated extension osteotomy of the thumb metacarpal reduces carpometacarpal joint laxity in lateral pinch

PURPOSE: To assess the effect of an extension osteotomy of the thumb metacarpal on thumb carpometacarpal (CMC) joint laxity with respect to the lateral pinch position. METHODS: Seven fresh-frozen specimens were dissected. The metacarpal, trapezium, and trapezoid were removed en bloc and rigidly fixed proximally and distally. The laxity of each specimen was measured by cyclically loading the CMC joint in a custom-built laxity testing device designed to allow relative movement of the trapezium and first metacarpal in 4 directions. The position of the CMC joint in lateral pinch was used as the baseline joint position. An extension osteotomy then was simulated by flexing the metacarpal base 30 degrees, thus placing the joint in the relationship it would assume if an extension osteotomy was performed and the specimen was positioned in lateral pinch. Laxity measurements then were repeated. RESULTS: The simulated extension osteotomy reduced laxity in all directions tested: dorsal-volar (40% reduction), radial-ulnar (23% reduction), distraction (15% reduction), and pronation-supination (29% reduction). CONCLUSIONS: The beneficial clinical effects of a thumb metacarpal extension osteotomy may be partially due to reduced joint laxity in the position of lateral pinch.     

Clinical results of intraarticular fractures of the base of the fifth metacarpal treated by closed reduction and cast immobilization

This retrospective study evaluated the results of closed reduction and cast immobilization for isolated intraarticular fractures of the base of the fifth metacarpal. Twenty-two of 37 such fractures were available for follow-up at an average of 43 months, and these had all healed at an average of 5 weeks without any cast complications. Twenty patients reported excellent or good results, and two reported fair or poor results. At follow-up, 13 had no arthrosis and nine had mild arthrosis of the carpometacarpal joint. However, outcome was not influenced by fracture type, the degree of subluxation or articular step off, or the presence of arthrosis. We conclude that isolated fractures of the base of the fifth metacarpal can be reliably treated with closed reduction and cast immobilization.     

Metacarpal descent,definition and normal range

Metacarpal descent, an indication of carpometacarpal (CMC) joint mobility, was measured in 90 normal subjects by assessing the alignment of the metacarpal heads with the hand in a relaxed posture and when making a tight fist. Metacarpal descent was greater in women. Hand dominance was associated with an increase in positional angles but not metacarpal descent.