Distal Radius Fractures

Introduction
Distal radius fractures are one of the most common fractures encountered in any trauma practice. Ever since Abraham Colles described the classical dinner fork deformity before the days of X-rays there has been a lot of interest and controversy over their management. The general principles in the management of these fractures are:

1. Anatomical reduction especially of any intra articular fragments
2. As rigid fixation as possible
3. Early mobilisation to prevent problems with stiffness

Classification
Although the term distal radial fractures includes a huge range of fracture patterns, they can be broadly classified into:

1. Extra articular
2. Intra articular

Within these broad sub divisions the fractures are usually described according to the direction of displacement, being either volar or dorsal. The most common cause of injury, i.e. fall on an outstretched hand, means dorsally displaced fractures were much more common then volar displaced fracture.

Treatment Options
The traditional methods of treatment have been broadly along the following lines:

1. Manipulation alone
2. Manipulation with K wire fixation
3. Open reduction and internal fixation (ORIF)
4. External fixation

Locking Plates
In this article I will be focusing on the option of ORIF, with special emphasis on the role of locking plates, and the approach to applying the plates.

Before the age of locking plates internal fixation was used mainly as a buttressing device, depending on the direction of displacement, i.e. dorsal buttressing for the dorsally displaced fracture and vice versa. The plate which was usually a T plate was fixed to the proximal shaft and the distal T segment was used to buttress the distal fragment.

The advent of the locking plates changed the concept of plates from functioning, just as a buttress. These implants functioned as neutralisation devices where the distal locking screws provided direct stability by supporting the sub chondral bone. They did not rely on the purchase of the distal screws which was usually poor on osteoporotic comminuted bone.

Dorsal Plates
Because most of the distal radius fractures were dorsally displaced and dorsal radius was more easily accessible due to the relative subcutaneous nature of the bone, this became the preferred approach of most surgeons. However there were problems associated with this:

1. There is little space available between the skin and the dorsal surface of the radius and this is occupied by the extensor tendons
2. The dorsal surface of the radius is convex thus which induces forced rubbing of the extensor tendons against the implants.
3. Blood supply to the dorsal fragments is principally from the dorsal side and these can be damaged during the dissection.
4. The dorsal surface is usually comminuted which increases the difficulty of reduction
5. Dorsal scars are generally less well tolerated.

All of the above, especially the problems associated with extensor tendon attrition, dampened the enthusiasm for the application of the dorsal locking plates and an alternative was being sought.

Volar plating of the distal radius with double row of distal locking screws

Volar approach to the distal radius
The volar aspect of the distal radius is better suited for implant positioning because:

1. More space is available from the skin to bone
2. The flexor tendons are separated from the implant by pronator quadratus
3. The concave surface of the distal radius facilitates better implant position
4. Blood supply is less likely to be disturbed
5. Volar cortex is usually less comminuted
6. Volar scars are better tolerated.

Watershed Line
Careful examination of the volar aspect of the distal radius reveals the presence of what is called the watershed line. Distal to this line the radius slopes in a dorso-distal direction. This ridge is close, 2mm, to the joint line on the ulnar aspect and well proximal, 10-15mm, on the styloid side. It is important to place the implant distal to the watershed line to prevent impinging on the flexor tendons and causing injury.

Extended Volar approach and reduction of fracture
The traditional volar approach through the bed of flexor carpi radialis (FCR) is sufficient for simple fractures and when the fractures are recent. But for complex dorsally displaced fractures, especially fractures which are a few days old where the fracture haematoma has organised, it does not give access to the fracture fragments and reduction is difficult. In these instances an extended FCR approach is used by releasing the radial septum and pronating the proximal fragment to gain access to the comminuted fracture fragments.

Biomechanical aspects
By approaching distal radius fractures through the volar aspect we are converting a dorsally unstable fracture into one which is now unstable in both directions. Some fractures are inherently unstable in both directions. So the loads placed across the implant can be as high as 50lb for even activities of daily living. Because of the special geometry of the distal radius volar plates a volar plate is in a more favourable bio mechanical position than a corresponding distal radius plate. This is due to the fact that the whole articular surface is offset a few millimetres in a volar direction with respect to the shaft. The stability can also be increased by a second row of distal screws in an opposite inclination. Together both rows form a scaffold that cradles the articular surface, maintaining reduction in spite of extreme instability.

Complications
Complications encountered with volar locking plates are few and are usually related to poor surgical technique. These include inadequate reduction, insufficient exposure and improper implant positioning relating to flexor tendon problems. The other problems are implant failure, infection, non union and reflex sympathetic dystrophy.

Conclusion
In conclusion locking volar plates have provided a new approach to the management of distal radius fractures regardless of the direction of displacement of the fracture. The obvious benefits are an early return to function, improved final motion, no extensor tendon problems and the abolition of routine plate removal. It is an easy to learn, simple procedure which has improved the outcome of this common injury.

References

1. J.Orbay. Volar Plate Fixation of Distal Radius Fractures Hand Clinic 21(2005)347-354
2. Ring et al, Prospective multi centre trial of a plate for dorsal fixation of distal radius fractures. J hand Surg Am 1997;22;777-84
3. Peine et al, Comparison of three different plating techniques for dorsum of the distal radius:a biomechanical study J Hand Surg Am 2000:25:29-33
4. Fernandez, Jupiter Fractures of the distal radius: a practical approach to management. New York :Spriinger-Verlag;1996
5. Putnam et al, Advances in fracture management in the hand and distal radius. Hand Clin 1989:5(3):455-70
6. Orbay, Fernandez, Volar fixed angle plate fixation for unstable distal radius fractures in the elderly patient. J Hand Surg 2004;29(1):96-102
7. Baratz et al Displaced intra articular fractures of the distal radius:effect of fracture displacement on contact stresses in a cadaver model. J hand Surg Am 1996:21:183-8

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