In this study, a modified intrafocal pinning technique with 3D planning was used to facilitate the reduction and fixation of dorsally comminuted intra-articular distal radius fractures following volar plating. Postoperative radiographic and clinical assessment showed a satisfactory reduction and good to excellent outcomes in most of the patients.
The original intrafocal pinning technique described by Kapandji was used with the pins maintained throughout the fracture healing period[16]. This technique was proven to provide sufficient buttress against dorsal extra-articular fractures of distal radius[16]. On the other hand, the limitations of this pinning technique did exist. Some studies found that elderly patients with osteoporosis did not achieve good functional outcome using the original intrafocal pinning technique[8, 17]. Besides, this technique was not recommended for intra-articular distal radius fracture with dorsal or volar comminution[16]. The integrity of the dorsal and volar metaphyseal cortex was considered crucial. Compared with the original Kapandji technique, we used intrafocal pins through the fractured dorsal cortex to reduce the collapsed intra-articular fragment. The prepositioned volar locking plate served as a buttress during this procedure, which eliminated the need for a relatively intact volar metaphyseal cortex. Besides, in our technique, multiple percutaneous subchondral pins from the dorsal aspect were applied to lever the articular surface and hence to restore the volar tilt. An extra dorsal approach or dorsal plating was not required in this case series.
Different modifications to the original Kapandji technique were reported in recent studies[3, 9, 10]. Huang et al. reported a modified sandwich method, in which the intrafocal K-wires were inserted from the dorsal and radial site to reduce the dorsal and radial fracture displacement. The anatomic palmar plate was then applied to build a sandwich structure for fracture fixation. The results showed that the sandwich method could achieve similar radial height, radial inclination, volar tilt, and ulnar variance comparing with the contralateral non-injured side[9]. Compared with our study, either the reduction of intra-articular depression or the situation of dorsal comminution was not specified in Huang’s report. Jirangkul et al. also reported the application of the additional volar locking plate following Kapandji intrafocal K-wire pinning[3]. A total of 57 cases of intra-articular fractures of the distal radius were treated, and most of cases achieved good to excellent clinical outcomes[3]. Compared with our study, the intra-articular fracture fragment was not reduced using intrafocal pinning technique in Jirangkul’s study. Besides, the situation of dorsal comminution was not addressed in this study.
In our study, 3D digital models of the distal radius fractures were reconstructed preoperatively to analyze the collapsed articular surface. The feasibility of CT-based virtual preoperative planning has been investigated in previous studies[18–21]. Compared with the traditional preoperative planning techniques using handwriting hardcopy radiographs along with tracing paper or simple measurements in the PACS, the CT-based 3D preoperative planning was proven to provide better understanding of fracture shape and displacement, especially in intra-articular fractures[22, 23]. In our case series, the collapsed intra-articular fragment as well as the characteristics of the comminuted dorsal cortex were carefully analyzed preoperatively in the 3D digital model, which provided guidance for the entry point and orientation of intrafocal pinning.
Most of the patients (94.3%) achieved excellent or good functional recovery in our study, probably due to the adequate fracture reduction including the recovery of radial inclination, volar tilt, and radial height, which were proven crucial for a satisfactory outcome [24, 25]. Considering different fracture types, all of the AO type C2 fractures resulted in good or excellent functional outcome. Compared with Chou’s study, in which an excellent or good outcome was achieved in 86.4% (19/22) of the patients with C3 dorsally-comminuted distal radial fractures treated with dorsal plating, our study showed similar results in C3 fractures with 85.7% (12/14) of the patients resulted in good or excellent functional recovery[26]. This indicated that our modified intrafocal pinning technique could facilitate volar plating and lead to similar clinical outcome as dorsal plating, even in dorsally comminuted C3 distal radius fractures.
This study had several limitations. First, the study included limited numbers of patients, partly because it was a single-surgeon study. Besides, some patients were excluded due to inadequate follow-up period of less than 12 months. Nevertheless, only the patients operated by one senior attending surgeon were includes, which prevented bias owing to the difference of surgeons’ experience and preference. Another limitation was the lack of comparison with other reduction techniques. Future studies with a larger sample size or with other technique as control group are needed to evaluate the clinical results.