Floating fifth metacarpal: give conservative management a try!

Abstract

We describe a case of double dislocation of fifth metacarpal (floating metacarpal) in a young adult presenting immediately after injury. He was treated conservatively by closed reduction and immobilization with a wrist brace for 3 weeks. Following above mentioned conservative management, he was pain free and he regained full range of motion and power comparable to contralateral side. Reports on floating metacarpal are rare till date and all of them have been managed surgically. We report a case of such dislocation which was managed successfully with conservative treatment. We advocate conservative management for floating metacarpal if it presents early and if reduction is stable.

INTRODUCTION

Floating fifth metacarpal (MC) refers to double dislocation of the fifth metacarpal. It denotes dislocation at both metacarpophalangeal (MCP) and carpometacarpal (CMC) joints. Though isolated dislocations of CMC and MCP joints have been reported several times in literature [1], only few case reports mention about the simultaneous dislocation of both joints [2].

Reviewed literature revealed that close floating metacarpal is rare and mostly occurs because of direct/indirect trauma to the involved MC [2, 3]. Only a few cases have been reported in the literature on floating metacarpal; thumb and little finger have been reported more commonly [3]. These dislocations have been considered inherently unstable often requiring fixation; either open or close [4]. However, in our case, we noticed that the dislocations were stable after reduction and hence managed it conservatively with splint. Conservative management has not been a popular method of management for floating MC, and no cases have been reported to date. This prompted us to report our case, where conservative management was successful.

CASE REPORT

A 28-year-old gentleman presented to us with complaints of pain and swelling of the right hand for 2 hr. He sustained an injury to his hand when his motorbike skid and he landed on the ulnar aspect of his hand and little finger. On examination, there was swelling, tenderness and deformity on the ulnar aspect of his hand. There was restriction of movement of the fifth finger. His wrist movements were normal, and there were no open wounds in hand. Radiological evaluation revealed dorsal dislocation of fifth CMC joint and volar dislocation of distal MCP joint (Fig. 1). Based on clinico-radiological examination, diagnosis of close, fifth floating finger was made. Closed reduction of the dislocations was done under sedation in emergency room, and wrist splint supporting the head of MCs was applied. Immediate post-reduction stability of the joints was assessed and the joints were found to be stable. Post-reduction radiographs (antero-posterior and oblique views) confirmed the reduction of both CMC and MCP joints (Fig. 2). The splint was removed after 3 weeks, and finger and wrist range of motion (ROM) exercises were started. At 6 months follow-up, his finger and wrist ROM were full. Grip strength was comparable on both sides and his movements were pain free (Fig. 3). No abnormalities were detected on the radiographs at 6 months follow-up (Fig. 4).

DISCUSSION

Fracture-dislocations of metacarpal bones are rare and isolated double dislocations are even rarer. Isolated floating metacarpals have been reported in thumb [3] and on a few instances in little finger [5–8]. As reported [1], floating MCs are commonly associated with fractures of carpal bones and require surgical fixation. Floating fifth metacarpal is even rarer, and on extensive search of literature we could only find seven reported cases [2]. All the cases needed surgical management for floating finger. To the best of our knowledge, ours is the first case, which was managed conservatively without surgery.

Fifth metacarpal CMC joint is a saddle joint which is supported by multiple ligaments, and usually, high energy trauma is needed to cause dislocation of these joints [4]. The injury often occurs due to direct blow to the ulnar aspect or palmar aspect of the hand or may be due to axial force along the shaft of the fifth metacarpal leading to disruption of the ligaments [2]. In our case too, the patient sustained hyperextension injury to little finger when he fell from bike leading to double dislocation.

Close reduction of these dislocations is easy if patients present early. It can be achieved with gentle traction to the little finger and manipulation [1]. In chronic, neglected or irreducible cases, open reduction is required for reduction of dislocation [2]. The reduction cannot be achieved in acute cases at times because of interposition of the ligaments, and in chronic cases as a result of fibrosis [2]. Our patient presented within hours of injury and the reduction could be easily achieved by traction and manipulation.

Review of literature suggests that dislocations of metacarpal are inherently unstable after reduction because of the capsular damage and fixation with K-wire for about 4–6 weeks is suggested to be appropriate [4]. We, in contrast, believe that if the reduction is stable and does not cause immediate dislocation after reduction, immobilization with a splint for more than 3 weeks would be sufficient to heal the capsular damage and ligamentous tear. This prompted us to immobilize the finger for 3 weeks as the reduction was stable immediately. We did not use any K-wires to fix the joint. With our method too, the patient could achieve full range of pain-free movement, and there was no loss of grip strength. So, we would suggest to try conservative management for floating metacarpals, if close methods can achieve the reduction, and if no subluxation or re-dislocation occurs immediately.

ACKNOWLEDGEMENTS

We acknowledge Mr. Sunit Kumar Singh for helping us with preparing manuscript and proof reading it for English language.

CONFLICT OF INTEREST STATEMENT

None declared.

REFERENCES