Minimal invasive plating of distal radius fractures. A safe procedure?

Minimal invasive plate osteosynthesis (MIPO) with preservation of the pronator quadratus (PQ) muscle represents a new technique for stabilization of distal radius fractures. However, the complex anatomy of the distal radius metaphysis requires implants with features that address all morphologic specifics of this area to avoid complications, which are still reported with this technique. It was the aim of our anatomic investigation to evaluate the feasibility of plate insertion via a minimal transverse approach as well as the risk of soft- tissues compromise with the use of an implant, which is only partially adapted to the characteristics of distal radius metaphysis.

Twenty forearm specimens, conservated with Thiels method, have been used for this study. The majority (n = 19/20) of implants (2.4 mm small fragment juxta-articular locking compression/ LCP T-plate -5-hole; Depuy - Synthes^®, Solothurn, Switzerland) could be inserted easily and all were seated proximal to the so called "watershed line" (n = 20/20).

In a total of 8/20 specimens close contacts or potential compromise to neighboring soft- tissues was seen: perforation of the PQ muscle by the plate occurred in 2/20 specimens and was related to an extreme muscle morphology. In 7/20 specimens close contacts between the T-plate and other soft tissues were observed, which were exclusively located at the radial edge of the distal transverse bar. They affected the brachio-radialis tendon (elevation: 2/20, side-to-side contact: 3/20, overriding: 1/20) and the radial artery (elevation: 4/20, side-to-side contact: 2/20, overriding: 1/20). No significant differences of morphologic types of PQ muscle and the difficulty of plate insertion, adjustment on the bone, PQ muscle damage and contact to neighboring soft-tissues could be evaluated.

Insertion of volar radius plates through a MIPO approach can be easily accomplished without detachment and damage to the PQ muscle even with grossly adapted implants. However, perfectly pre-shaped plates which are adapted to all anatomic aspects of the distal radius metaphysis are required to achieve optimal contact with the metaphyseal bone and to avoid potential complications.