Treatment of a first metacarpal basal fracture is relatively difficult, and the treatment of such fractures involving dislocation is particularly challenging . However, closed reduction and percutaneous K-wire fixation can obtain a satisfactory curative effect for both the Bennett fracture and Rolando fracture [17,18,19,20].
Numerous techniques have been reported for closed reduction and percutaneous K-wire fixation of first metacarpal basal fractures [4, 8,9,10,11, 21, 22]. Although the result of parallel K-wires fixation between the first and second metacarpals reported by Van Niekerk and Ouwens in 1989 seemed unsatisfactory , the concept of minimally invasive and reliable fixation was worthy of further investigation. This influenced the development of modified techniques that have subsequently achieved a good curative effect . Our technique is a further modification of the technique involving parallel K-wire fixation between the first and second metacarpals for the treatment of first metacarpal basal fracture. The highlights of our technique are that the ends of the K-wires were bent at 90° toward each other, and the wires were then sheathed with a section of infusion tube and strapped with silk thread. This simple operation enables the parallel K-wires to form a stable frame structure similar to an external fixator; coupled with the support of the second metacarpal, a stable rectangular frame is formed.
Previous studies have reported conflicting outcomes of closed reduction and parallel K-wire fixation for first metacarpal base fracture. In Van Niekerk and Ouwens’ report , only 14 of the 19 intra-articular fractures were successfully treated by closed reduction and parallel K-wire fixation, and three of the 23 patients had poor recovery that affected their daily life and hobbies. In contrast, Greeven et al.  reported that they achieved good results with the application of this technique; only one patient with an extra-articular fracture experienced functional limitations and could not engage in their previous hobby, but was able to return to work. The follow-up results obtained by Greeven et al.  were obviously better than those obtained by Van Niekerk and Ouwens , who performed this surgical technique earlier. This difference may be related to the maturity of the surgical techniques.
In our study, all 20 patients who underwent the modified surgery were able to return to their original work or previous activity or hobby, and although their thumb movement declined after 1 year, they were satisfied with the strength, range of motion, and symptoms of their hand. By comparison, two of the 10 patients who underwent traditional surgery developed joint stiffness that prevented them from pursuing their previous hobbies. The good clinical results in the modified technique group may be related to our modification of the surgical technique, the bending of the K-wires, and the interlocking fixation, which enhanced the stability; thus, postoperative plaster fixation could be largely avoided (the rate of plaster use in our modified technique group was 2/20 (10%), compared with 12/25 (48%) in the report by Greeven et al. ). Therefore, the functional exercises performed immediately postoperatively promoted rehabilitation of our patients’ hand function (Fig. 3).
In the traditional technique, Wagner’s method  requires the K-wire across the first carpometacarpal joint, which is also unavoidable in the cross K-wire fixation technique. However, this transarticular K-wire fixation may damage the joint surface, which occurred in almost all of the traditional surgeries included in our study. A high incidence of traumatic arthritis has been reported for transarticular K-wire fixation (16 of 21patients) . Moreover, it is difficult to drive the K-wire diagonally into the first metacarpal base or the fracture blocks, and repeated drilling may damage the joint and cause a new fracture. Therefore, repeat manipulation and fluoroscopy are needed to determine the correct position during traditional surgery; thus, the operation time in the group that received the traditional technique was longer than that of the group that underwent modified technique. In addition, only performing fixation of the bases of the first and second metacarpals and/or fixation of the first carpometacarpal joint is still unstable, and so postoperative plaster-assisted fixation is necessary . In contrast, our modified technique of drilling parallel K-wires through the first and second metacarpals is easy to perform; we only need to fix the proximal and distal ends of the first and second metacarpal with K-wires, which does not have strict requirements as to the position of the K-wires. By strapping the bending ends of the two K-wires, this forms a stable rectangular frame so that the length of the first metacarpal is maintained and the axial rotation is resisted; thus, it is more stable than longitudinal K-wire fixation . Furthermore, our technique of parallel K-wire fixation avoids direct damage to the joint, and does not interfere with the blood supply to the fracture; thus, our technique may achieve a higher rate of fracture healing than other K-wire fixation techniques or plate fixation, although this has not yet been investigated. Greeven et al.  reported that three of 25 cases developed needle infection and were cured by oral antibiotics. However, none of the 30 patients in our study developed an infection. This difference may be related to the health education of the patients and the strict bandaging and care of the exposed K-wires after the surgery. Potenza et al.  also achieved satisfactory results when they applied this parallel K-wire fixation technique in the treatment of fifth metacarpal neck fractures.
Duan et al.  recently introduced a frame structure to treat comminuted fractures of the first metacarpal base. The structure was made of multiple K-wires and bone cement and also served as a type of external fixator. However, the operation was complex, it was difficult to avoid damaging the metacarpals, and it was difficult to maintain the fracture reduction while the cement set; moreover, the appearance was cumbersome, and the application of bone cement increased the medical costs (extra expenses 110 USD). Adi et al.  reported the use of trapezoidal K-wire fixation between the first and second metacarpals in the treatment of first metacarpal base fractures. The K-wires were also bent and fixed, but the fixation was achieved using a special locking device. However, it was difficult to avoid K-wire deviation and slippage when they were drilled into the metacarpal shaft at an acute angle, so the operation time is longer (mean tourniquet time 30 min). Additionally, the use of special locking devices increased the medical cost (nearly 100 USD), and the removal was inconvenient. Similarly, Shafific  used a self-made external fixator (parallel K-wires) for metacarpal and phalanx fractures and performed the locking fixation of the K-wires using a commercial device (locking ball/Jurgan ball), but the medical costs were substantial, and the fixation and subsequent removal operations were not easy. In contrast, our method is easy to perform, achieves good stability, is very cheap (owing to the use of infusion tube and silk thread), and only requires stitch cutting to remove the K-wires.
The only problem with our technique is that movement of the first metacarpal can be restricted by the fixation, and the thumb motion may therefore decline after the surgery . This phenomenon was observed in our study, and the solution is to open the thumb and maximise the space between the first and second metacarpals during the operation .
Our study had several limitations. First, this was a retrospective, observational trial with a relatively small sample size, and the follow-up was short. Second, although we evaluated the efficacy of the modified technique by comparing it with the traditional K-wire fixation technique, a randomized control group could not be created. Due to the poor stability of the traditional technique, plaster fixation is still indispensable, so it is not the most ideal control model (with more different parameters). In addition, we mainly obtained data regarding the surgical effect in the modified technique group through comparison of the injured and uninjured hands, and although we adjusted for the dominant hand in the data analysis, we still cannot exclude the influence of the dominant hand. Third, traumatic osteoarthritis was not evaluated because 1-year postoperative radiographs were unavailable for some patients, and evaluation of this complication requires long-term follow-up to be meaningful . This is worthy of discussion in future studies.