Open reduction and internal fixation has become the predominant mode of fracture fixation of the distal radius 18–20. Plating has reduced the rate of infections and provided patients the ability to bear weight on the extremity, but comes with the risk of tendon compartment entrapment or tendon lag 11,16. Recently, Lauder et al conducted a retrospective study that analyzed the functional outcomes of dorsal-spanning bridge plating. They found that grip strength was 86% and extension torque was 78% when compared to the uninjured contralateral wrist. Dominant and nondominant wrist injuries were identified with nearly complete recovery of dominant-sided grip (95%) and extension (96%), and non-dominant-sided grip (79%) and extension (65%) strength. There were only 2 cases of postoperative surgical site pain with no cases of infection, tendonitis, or tendon rupture 21. However, this is not to say that dorsal-spanning bridge plating lacks complications. Such complications can be separated into minor (wound healing and hardware failure without loss of reduction) and major complications (malunion, nonunion requiring surgery, wound complications/unplanned surgery, deep infection, extensor tendon adhesions/tenolysis, EPL rupture requiring and EIP transfer) 22. Several studies have demonstrated clinical complications with the use of the conventional distraction plate as well. Hanel et al. reported one extensor carpi radialis longus rupture with hardware failure in their study of 52 patients 22. Ruch et al. had 3 patients with extensor lags of 10° from their 22 patients with reported mean Disabilities of the Arm, Shoulder and Hand (DASH) score of 11.5 points at final follow-up 11. Richard et al. reviewed distraction plating of comminuted distal radius fractures in 33 elderly patients and reported complications including digital stiffness, required tenolysis at the time of plate removal, superficial radial neuritis, and chronic regional pain syndrome 23. Another study on the dorsal-bridge plating technique identified complications including: tendon rupture, tenosynovitis, reoperation, and 25% collapse 24.
There has also been controversy in the specific technical approaches between volar or dorsal plating. Some authors prefer a volar plate to avoid the risk of extensor tendon damage, while other authors believe that a volar approach provides better biomechanical outcomes 25–35. Rein et al. described 2 of 14 patients with dorsal plating who experienced extensor tendon irritation, 2 patients with fragment displacement and 3 cases of nerve irritation. This is in comparison to 12 of 14 patients that had no complications with the volar approach. However, they also point out that novel dorsal plates and modified techniques could overcome these issues 34. Similarly, Henry et al. described the advantages of volar plating as having a socially less visible scar and the ability to support immediate functional loading of the hand, wrist, and forearm in both rehabilitation and daily activities. It was also noted that with increasing fracture complexity that restoration of volar tilt becomes increasingly difficult without the use of a device to achieve the lift maneuver 29.
Radiologic, clinical, and biomechanical studies have been performed advocating the superiority of dorsal plating over volar plating. Letsch et al. provided radiologic evidence that palmar plates (1.7 points) had a significantly lower result than patients with a dorsal plate (1.0 points, p < 0.05). In such studies, locked or non-locked dorsal constructs were more than 2 times stiffer than volar constructs. With regards to functional outcome, there was a strong tendency for better outcomes with dorsal plating (3.0 points) compared with palmar plating (4.1 points); however, these findings were not significant 36. A biomechanical study by Trease et al. proved that while not statistically significant, the failure strength of dorsal constructs was 53% higher than that of volar constructs 37. While volar versus dorsal plating remains an ongoing issue, the novel subcutaneous plate provides stiffness as good as the conventional dorsal-spanning bridge plate, therefore handling stiffness similar to volar plates.
The modified subcutaneous construct aims to overcome common complications of badly comminuted distal radius fractures via multiple modifications to current techniques. Lewis et al. first provided evidence that plating to the second metacarpal did not result in tendon entrapment, but plating to the third metacarpal resulted in six tendon entrapments in six samples 16. With respect to Lewis’ data for the insertion of distal plating sites, the modified construct was placed to the second metacarpal to minimize tendon entrapment. In addition, by staying superficial to the extensor compartment, the above mentioned complications should theoretically be marginal due to minimal soft tissue disruption and violation of the third and fourth extensor compartments, as well as bypassing possible nerve injury. The data from the current study suggests that the subcutaneous internal fixator plate provides adequate structural support similar to the traditional Burke approach after cycling and is both stiffer and stronger than an external fixator.
In the current study, we tested the axial and torsional durability of external fixation, the Burke plate, and subcutaneous plating. The results demonstrate the biomechanical integrity of our modified construct for the fixation of comminuted distal radius fractures. It is stiffer than an external fixator, and has the theoretical advantage of avoiding pin-tract infections. In addition, it is subcutaneous and not as cumbersome as the external construct. While not as stiff as the Burke plate, our construct is minimally invasive, easier to remove, and does not violate the dorsal extensor compartments allowing movement of the fingers while the construct is in place. The results of this study, in addition to the theoretical circumvention of well-known complications, support dorsal subcutaneous plating as an alternative for highly comminuted distal radius fractures.
While the current study portrays biomechanical loading as good as the conventional plate and better stiffness than the external fixator, there are limitations to the current study as well. A primary limitation of this study is the relatively low number of specimens used. However, nonparametric statistical analyses are less sensitive to sample size issues, and statistical significance was still achieved despite the limited number of specimens used. This study was performed in cadaveric specimens, therefore, the effects of osteogenesis on the tested constructs could not be evaluated and cyclic data should be interpreted with caution. Finally, while age-matched specimens allowed for comparison of two biologically similar samples, the clinical significance of these results cannot be determined without further study.
We accept the alternative hypothesis that the modified subcutaneous construct is superior to external fixation in terms of stiffness both pre- and post-axial load cycling. We found that the Burke plate was superior in stiffness before axial cycling, but the difference does not reach significance after axial cycling, suggesting that the modified plate should be as resilient as the Burke plate in actual use. We recognize the small sample size may have affected power to detect a post-cycling difference, but on the basis of marked superiority to external fixation and reduced invasiveness for installation, we have identified an important alternative technique for the fixation of severely comminuted distal radius fractures. Future studies will focus on clinical results of the subcutaneous infix plating technique.