Anatomy - Angle-stable palmar plate osteosynthesis of a distal radius fracture on the right

1. A. radialis
2. Tendon of M. flexor carpi radialis
3. N. medianus
4. R. thenaris nervi mediani
5. M. pronator quadratus
6. Tendon of M. flexor digitorum profundus
7. Tendon of M. Flexor digitorum superficialis
8. R. palmaris nervi mediani

Modified Henry Approach

The modified Henry approach is suitable for exposing most fractures of the distal radius. While the classic Henry approach occurs between the A. radialis and the M. brachioradialis, the modified Henry approach involves splitting the tendon fascia of the M. flexor carpi radialis longitudinally and proceeding between it and the A. radialis. The modified approach is comfortable and low in complications, although the A. radialis and the palmar cutaneous branch of the N. medianus are at risk.

Plate Design

The development of angle-stable plate systems has led to a change in the surgical treatment of distal radius fractures. Previously, the predominant technique was dorsal buttressing plate osteosynthesis, but today the palmar angle-stable plate osteosynthesis is considered the gold standard.

Due to the widespread use of this technique, a variety of different plate systems are now available, which show significant differences that must be considered when selecting. These relate to the plate design and the various locking techniques.

The plate used here, VariAx™ by Stryker, is side-specific, takes into account the curved structure of the radius, and features the traditional T-shape. The distal edge of the transverse arm is shaped according to the so-called watershed line of the distal radius, a theoretical line marking the most palmar aspect of the palmar edge of the radius. This line runs distal to the pronator quadratus line and is covered by the palmar capsule.

When a plate is positioned distal to the watershed line, the contact pressure on the flexor tendons significantly increases depending on the extension position of the wrist. The tendon of the M. flexor pollicis longus (FPL) is exposed to the highest pressures, most likely due to its location and course. Studies have shown that plates placed palmar to this line serve as a pivot point for the flexor tendons - especially during wrist extension - making (peri)tendinitis or tendon rupture, particularly of the flexor pollicis longus tendon, highly likely.

Two distal rows of screws allow for high flexibility in screw positioning, which is advantageous in the presence of osteoporosis or multifragment fractures. Both central and dorsal joint surfaces can be optimally captured with this, and the subchondral position of the screws prevents secondary dislocation. The screw holes are designed to allow multidirectional, angle-stable anchoring of the screws with a play of 15°. The screw heads are countersunk in the plate and do not protrude. Together with the low-profile plate design and the watershed shape, they help prevent rupture of the flexor tendons.

The longitudinal arm of the plate allows for dynamic correction of the plate position during repositioning through the sliding hole in the middle. Proximally and distally, the plate can be securely fixed with additional angle-stable screws.