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Wrist and HandFurther Opinion

Two extension block Kirschner wire technique for mallet finger fractures

YH Lee, JY Kim, MS Chung, GH Baek, HS Gong, SK Lee

J Bone Joint Surg [Br] 2009;91-B:1478-81.

 

Mallet fingers are common injuries, regularly seen in everyday general trauma practice. Internal fixation of these injuries is rarely performed outside a specialist hand surgery setting. The reasons for this reluctance to manage a displaced articular fracture differently from the recognised principles of managing such injuries, include:
1. Technical difficulty with such small fragments
2. Frequent comminution
3. Unfamiliar surgical approach with risk of nail damage
4. Understanding that many of these injuries ‘do well’ when treated non-operatively

It is true to say that most mallet fingers will functionally ‘do well’ after non-operative treatment, even though we have no evidence to support this other than our own clinical experience. However, it is also true to say that most, if not all, mallet fingers treated non-operatively will produce a permanent extensor lag at the distal interphalangeal joint. This may be troublesome depending on individual needs. So should we strive to improve this by more invasive treatment?

What is less well recognised is the critical need to identify and treat subluxation of the distal phalanx. Attention is often focussed on ‘the fracture’ and whether or not it constitutes (a somewhat arbitrary) 30% of the joint surface or more. Subluxation is the feature which will determine outcome more than any other.

This report elegantly describes a simple technique for stabilising reduction in displaced articular fractures without the need for surgical approach, reduction of small or comminuted fragments, and with little or no risk of injury to the germinal matrix of the fingernail. In fact, it brings a specialist approach into the realm of the generalist, and should allow surgeons to treat these injuries with technical confidence and adherence to the principles of management we learn in our training but often neglect in our practices.

The use of two parallel Kirschner wires dramatically increases the dorsal buttressing effect on the fracture fragment(s), and stabilises them to rotation as well as to flexion/extension forces.

The authors stress the importance of the reduction technique as being the key to successful stabilisation. Failure to reduce the fragments adequately will not only lead to malunion, but also to significant technical difficulty in inserting the Kirschner wires in the narrow distal phalanx (and subsequent discredit to the technique).

Further technical tips not noted in this paper would include its performance without tourniquet (digital or upper arm). Unrestricted blood flow in the finger will help to cool the rapidly revolving Kirschner wire and reduce the risk of thermal osteonecrosis, infection, pin loosening and loss of reduction. A second piece of technical advice would be to use a new sharp Kirschner wire for every attempted pass. The tips of Kirschner wires blunt very easily (particularly in these small sizes), and a blunt wire will be more difficult to insert, leading to failure of reduction and possible thermal injury to the small bone and its thin overlying skin.

Overall, this simple and logical extension of a widely used and successful percutaneous technique will allow such injuries to be treated by a wider group of surgeons, so improving access to a ‘specialist’ level of care for everyone.

 

Campbell DA

Leeds General Infirmary, Leeds, UK

E-mail: dougcampbell1@hotmail.com