Intended for healthcare professionals

Endgames Case Review

A patient with a painful and swollen hand

BMJ 2017; 358 doi: https://doi.org/10.1136/bmj.j3127 (Published 20 July 2017) Cite this as: BMJ 2017;358:j3127
  1. Alexander EJ Trevatt, core surgical trainee, year 2,
  2. William Maynard, foundation year 2,
  3. Roger Adlard, consultant plastic and reconstructive surgeon
  1. Plastic and reconstructive surgery department, St George’s University Hospitals NHS Foundation Trust, London, UK
  1. Correspondence to A Trevatt alextrevatt{at}gmail.com

A 26 year old man presented to the emergency department with a painful and swollen right hand. The previous night he had punched a wall. He was previously fit and well with no substantial medical history.

On examination his hand was swollen and bruised, but there was no open wound. He had tenderness over the dorsum of the hand, particularly over the fifth metacarpal. There was no obvious deformity, scissoring, or malrotation of the fingers, but he was unable to make a full fist due to the pain. On extension there was an extensor lag of the little finger.

Radiographs were taken (fig 1) and his hand was put in a volar backslab.

Fig 1
Fig 1

Radiographs of the patient’s right hand: anterior-posterior (left), oblique (middle), and lateral (right)

Questions

  • 1. What injury has the patient sustained?

  • 2. How should a patient with this diagnosis be managed?

  • 3. What are the potential complications of this injury?

Answers

1. What injury has the patient sustained?

Short answer

The patient has sustained a closed fracture to the neck of the fifth metacarpal of his right hand, also known colloquially as a “boxer’s fracture.” The radiographs show a simple extra-articular fracture with approximately 50° of volar angulation.

Discussion

Fractures of the fifth metacarpal are common injuries, accounting for 10% of all hand fractures.1 The five metacarpals make up the body of each hand, articulating proximally with the trapezium, trapezoid, capitates, and hamate, respectively, and distally with the proximal phalanges. The fifth metacarpal articulates proximally with the hamate, laterally with the fourth metacarpal, and distally with the fifth proximal phalanx.

Fractures of the fifth metacarpal most commonly occur after sudden axial loading, when the fingers are flexed at the metacarpophalangeal joint, for example, by punching a hard object, or after a fall. For this reason, these fractures were traditionally referred to as “brawler’s fractures,” since trained boxers with correct technique were more likely to fracture their first or second metacarpals. However, more recently they have become known colloquially as “boxer’s fractures.” Volar angulation of these fractures is common due to the displacing forces of the collateral ligaments of the metacarpophalangeal joint and the interosseous muscles. Angulation is generally more severe in fractures of the fifth metacarpal compared with other metacarpal fractures. This is because of the relative mobility of the fifth metacarpal (required for little finger opposition) and its lack of supporting structures at its ulnar border.

Presentation is generally characterised by pain and oedema over the fracture site, reduced range of movement at the metacarpophalangeal joint, and depression of the contour of the knuckle. Lacerations over the knuckles might also be present, particularly if impact has occurred with sharp objects, including teeth. These are known as “fight bites” and are a surgical emergency that requires urgent exploration and washout in theatre because of the risk of infection from flora in the oral cavity. If there are lacerations, antibiotics with anaerobic cover should be commenced. Lacerations can also cause extensor tendon injuries that can complicate fractures of the fifth metacarpal.

2. How should a patient with this diagnosis be managed?

Short answer

As long as there is no deformity, scissoring, or malrotation, patients can be managed conservatively. A referral should be made to a hand therapist to address any inability to make a full fist.

Discussion

Important points to elicit in the history are the mechanism of injury and force of impact, whether there has been any loss of function or sensation since the injury, and whether an open wound was sustained. When examining the hand it is useful to compare both hands. Look for oedema, bruising, and skin lacerations over the point of contact and observe whether any rotational deformity to the digits is present. Ensure that the other digits and forearm are also inspected for other injuries, and document the neurovascular status of the hand.

Where there is no scissoring or malrotation of the digits on flexion, the patient can be managed conservatively. Where there is severe displacement, angulation on radiography, scissoring, or malrotation, manipulation of the fracture might be required. This can generally be performed under local anaesthetic in adults; however children might require a general anaesthetic. A small degree of “extensor lag” (inability to fully extend the affected digit) is common in these fractures and can generally be managed conservatively with hand therapy.

The maximum acceptable volar angulation of closed fifth metacarpal neck fractures is unspecified. Volar angulation of up to 40° is generally accepted because of the compensatory movements of the basal joints, and some surgeons have reported good functional outcomes with up to 70° angulation.2 Unacceptable volar angulation that is not corrected can lead to reduced flexion and pseudo clawing. Correction can generally be achieved using the Jahss manoeuvre, whereby the metacarpophalangeal and proximal interphalangeal joints are flexed to 90° and the proximal phalanx is used as a lever to reduce the distal displaced fragment. The reduction can then be maintained using a splint or backslab.

In cases that require intervention, closed reduction can be sufficient. However, frequently the fracture configuration cannot be sufficiently improved with closed reduction because of displacement or because the fracture is unstable, in which case surgical fixation might be required. Other reasons for surgery are polytrauma, severe soft tissue injury requiring reconstruction, and open fractures.

3. What are the potential complications of this injury?

Short answer

Delayed fracture union, extensor tendon lag, and malunion are the commonest complications in fifth metacarpal fractures. Functionally, patients with residual digital rotation have poor functional outcomes. Septic arthritis of the fifth metacarpophalangeal joint is a serious complication of open injuries.

Discussion

Complications following metacarpal fractures are relatively common, and can be surgical or non-surgical. Non-surgical complications include malrotation of the little finger caused by fracture malunion. The digit commonly rotates radially and is most pronounced on flexion. This can cause severe functional deficit, particularly on power grip and opposition. The treatment for rotation is primarily surgical correction. Excessive volar angulation can also cause extensor lag and an inability to achieve full active extension at the fifth metacarpophalangeal joint. This can lead to poor functional outcomes if pronounced.

Non-union (failure of the fracture to heal clinically or radiographically after four months) can also occur. This might be because of poor immobilisation in unstable fractures and is most common in transverse fractures, which are inherently unstable. Non-union can also occur due to poor blood supply, associated soft tissue injuries, infection, or when there is interposition of soft tissues into the fracture. The options for treating non-union include stable plate fixation, debridement, or bone grafting. Mal or non-union can occur in up to 15% of patients treated surgically.3

Stiffness is a common postoperative complaint that is more common after open fractures and in some studies4 has a higher association with plate fixation. It usually resolves with early mobilisation of the injured hand but might require procedures such as tenolysis or capsulotomy.

Infection is rare in closed fractures, occurring in less than 1% of cases. However, in open injuries infection can occur in up to 11% of cases.5 To reduce the risk of infection, these patients should be started on antibiotics early, and should undergo urgent washout of the fracture. Infected fractures are more likely to develop mal or non-union, and can progress to septic arthritis of the metacarpophalangeal joint. If septic arthritis is suspected, urgent debridement of the infected area is recommended, antibiotics commenced, and early referral to hand therapy initiated. Patients with septic arthritis of the metacarpophalangeal joint are likely to develop joint stiffness and pain if not treated promptly.

Patient outcome

The patient was referred to the hand therapy team because of his inability to make a full fist. He attended two appointments where he was given a hand exercise regime to follow. He was discharged on his second appointment when he had regained full function in his hand.

Footnotes

  • We have read and understood BMJ policy on declaration of interests and declare that we have no competing interests.

  • Patient consent obtained.

  • Provenance and peer review: not commissioned; externally peer reviewed.

References

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