Obviously displaced RW-C thumb metacarpal base fractures are rare in children and still challenging for paediatric orthopaedic clinicians to manage. Closed reduction is difficult to perform for severely angulated and displaced RW-C fractures. According to some authors, RW-C fractures with fewer than 30 degrees of angulation disbalance can be treated by closed reduction and splinting. Ruptures of the medial periosteum make the fracture unstable, and immobilization with the first ray yields unreliable results . Some researchers have recommended that aggressive procedures are performed in children when the maximum angle of fracture is > 30 degrees, the magnitude of displacement of the fracture is > 2/3 of the diameter of growth plate, or a rotational deformity is present [6,8,9]. All 17 cases exhibited these operative indications. Thus, the indications of acceptability of imperfect reduction exist for two reasons. First, the first ray is constituted by a series of joints that can compensate for small extra-articular displacements without causing severe disability. Second, such displacements can be corrected by remodelling the growth plate [14,15]. However, this spontaneous correction requires two years . We must remember that the growth plate closes at an average age of 14.5 years in girls and 16.5 years in boys when considering the indications for the treatment of these fractures [6,15].
Some studies have reported that severely displaced RW-C fractures might require open reduction to remove any portions of interposed periosteum that prevent reduction. Open reduction is indicated for irreducible RW-C fractures [4,12]. However, Jehanno et al reported that open reduction is not difficult due to interposition of tendons or of the periosteum . The mobility of the metacarpal base and swelling make closed reduction difficult. Comminution, soft tissue interposition, or transperiosteal “buttonholing” may further complicate reduction [4,10]. Manual closed reduction of RW-C fractures requires axial traction on the thumb, and pressure is placed on the base of the distal fragment . Both the second metacarpal and thenar impact manual closed reduction. In theory, these are the true reasons that closed reduction fails. When closed reduction is performed unsuccessfully, open reduction is also required . The leverage technique that we described in this study showed a minimally invasive and reliable choice to avoid open reduction.
In general, manual reduction and leverage treatment for paediatric fractures, including S-H type II fractures of the distal radius, radial neck fractures, supracondylar fractures, and Bennett fractures, are successful and yield good results, and satisfactory results have been reported [18-21]. We performed leverage reduction to anatomically reduce these fractures. The number of leverage manual reduction attempts can be reduced to fewer than 3, while injury to the physis caused by the tip of the leverage k-wire can be avoided. For at least 2 years follow-up, there were no cases of premature physis closure, bone bridge formation or epiphyseal ischemic necrosis in our study.
There are many pin configuration options, including pinning across the reduced carpometacarpal (CMC) joint, the Iselin technique, the modified Iselin technique, and direct fixation across the fracture [6,12,22,23,24]. Some authors have shown that intraarticular k-wires may aggravate articular surface lesions and cause posttraumatic arthritis. Thus, the Iselin method was proposed . Some researchers have determined the incidence of secondary displacement because of the faulty Iselin technical approach and a decrease in the quality of reduction . Wiggins preferred the technique of transfixing a k-wire across the epiphyseal growth plate, which has never been reported to cause epiphysiodesis . Hastings also demonstrated that thumb base fracture fixation with longitudinal K-wire fixation yields good results . We prefer DACK wire fixation, which has been proven to be a good technique in previous studies. Bone union was achieved in all 16 patients within a mean time of 4.2 (range 4~6 weeks). A total of 15 patients had an excellent outcome, and one had a good outcome, without secondary displacement of the fracture or tendinous adhesion. In our experience, the advantages of DACK wire fixation include the easy selection of the needle puncturing point and stable transfixion of K-wires across the epiphyseal growth plate, which is yields higher stability than does the Iselin technique.
In our research, most of the leverage procedures were performed within 0.30 min with 1-3 leverage attempts. A longer duration of the leverage procedure is associated with more radiation exposure (RE). The risk of RE needs to be understood and minimized in paediatric trauma theatres, as RE is associated with malignant diseases . Ultrasonography (US) has also been used for intraoperative monitoring for the treatment of radial neck fractures in children to reduce the dose of RE . US could be a useful alternative to X-ray in the future for this kind of fracture during intraoperative intensification.
Our results show that the following key points should be understood when performing the procedures: (1) According to the preoperative imaging and C-arm image intensifier data, the plane with the largest displacement and angulation of fractures should be chosen as the leverage plane to achieve anatomical reduction and reduce the number of leverage attempts. (2) The abductor pollicis longus tendon and the first metacarpal epiphysis should be considered the puncturing points for the wires to reduce tendinous adhesion. (3) DACK wire fixation is more reliable. (4) When leveraging, the tip of the K-wire should be moved towards the metaphysis to prevent injury to the physis. (5) In contrast to other metacarpals, the thumb metacarpal is visible on both AP and lateral X-rays, and the angulation and displacement can more reliably be assessed.
The main limitation of this study is that it is a retrospective cohort study with a small sample size and without a control group. We cannot confirm that our technique is superior to others. However, our technique yielded satisfactory outcomes with few complaints. Additional studies with large sample sizes are needed.