Fractures of the neck of the fifth metacarpal bone, treated by percutaneous intramedullary nailing: surgical technique, radiological and clinical results study (28 cases)

This study report the results in 28 patients affected by closed fractures of the neck of the fifth metacarpal bone (boxer's fracture), treated with percutaneous elastic intramedullary nailing using a single wire, to verify the effectiveness of this surgical treatment. We reviewed the results of 28 patients treated with A single Kirschner wire (K-wire) pre-bent in a lazy-S fashion with a mild bend at approximately 5 millimeters, The K-wire is inserted blunt end first in an antegrade manner and the fracture reduced as the wire is passed across the fracture site The wire is usually removed with pliers post-operatively at four weeks in the fracture clinic. The follow-up period averaged of 20,75 months. The parameters evaluated included angulation, rotational alignment, postoperative metacarpophalangeal (MCP) range of motion, and time to union. We opted for this treatment in all cases, regardless volar angulation of the metacarpal head, malrotation of the fifth finger and associated or/no with a severe swelling of the hand. All the patients were reviewed clinically and radiologically at an average of 20,75 months after surgery. At the final follow-up, no patient reported residual pain and All fractures proceeded to bony union but we have one fracture had to be revised for failed fixation and three superficial wound infections needed antibiotic treatment. We recommend that this minimally invasive: percutaneous intramedullary nailing using a single k-wire in all metacarpal neck fracture( boxers’ fractures), especially when severe swelling of the hand is present, with good functional results and low morbidity.


Introduction
Fractures of the metacarpal bones are very common injuries of the skeletal system and, in approximately 50% of the cases, involve the neck of the fifth metacarpal bone [1]. The Metacarpal neck fractures are among the most common of hand fractures with those involving the fifth metacarpal (boxer's fractures) being the most common [2].These fractures result from a longitudinal compression force acting on a flexed metacarpophalangeal joint (MCP) -usually when a clenched fist strikes a solid object, The resultant fracture is usually unstable with volar angulation due to comminution of the volar cortex and the deforming action of the interossei [3].These fractures are frequently observed in active young men, occur in the dominant hand and are typical injuries of aggression (boxer's fractures) [4,5].their treatment can be problematic [ 3],many treatments are numerous: functional treatment by a simple syndactylisation with risk of secondary displacement [6,7];the Conservative treatment consists of a cast immobilization, but sometimes source of skin complications [8,9], and there are Various fixation techniques in use are : a direct osteosynthesis [ 10]; percutaneous pinning [ 11]; plating [12] and percutaneous transverse pinning [1].
The purpose of this study was to report the medium-term results in 28 patients affected by closed fractures of the neck of the fifth metacarpal bone (boxer's fracture), treated with percutaneous elastic intramedullary nailing using a single wire, to verify the effectiveness of this surgical treatment.

Methods
Our series include 28 Cases of fractures of the neck of the fifth metacarpal bone (boxer's fracture), surgically treated. Complex injuries or unreliable patients were not included for this treatment and we excluded from this study: the fracture of the child, articular fracture and open fracture. The rotational deformity of the fifth finger and/or a palmar angulation of the fracture was never an exclusion criterion. The Patient demographics including age, sex, occupation, handedness and other associated medical problems were collected, and the mechanism of injury was noted and the side involved was clinically examined for rotational deformity.
Radiographs measured the angulation at the fracture side; we use a goniometer to calculate the angulation. Operative data was collected regarding time to surgical intervention, Anaesthetic mode, tourniquet . Length of stay in the hospital was documented, and Post operatively patients were assessed clinically and radiologicallly.
Ranges of movements at the métacarpophalangeal (MCP) joint and inter phalangeal (IP) joint, were assessed using TAM(total active motion) and TPM ( total passive motion) as well as the presence of any rotational deformity. From the radiographic point of view, antero-posterior (AP) and latero-oblique X-rays were taken to assess the possible presence of a residual deformity of the fifth finger. All the patients were reviewed clinically and radiographically from 5 to Anatomical results (Figure 4, Figure 5): All fractures proceeded to radiological bony union without rotational or severe angulation deformities (Figure 4, Figure 5). The wire was extracted in all patients at a mean period of 4 weeks (range four to six weeks). All

Discussion
The aim of this retrospective study was to assess the clinical and radiographic results of percutaneous intramedullary nailing fixation with single K-wires in fractures of the neck of the fifth metacarpal bone .the Boxer's fractures are very common injuries [13,14].Which can cause impairment of hand function [15][16][17], When they heal in malrotation and/or in volar angulation of the metacarpal head and the result may be a loss of the grip strength and an extension deficit of the little finger.
The epidemiological study of our series is in agreement existing with other studies [18,19]. The punch is by far the most common etiology but this concerns only rarely fracture the real boxer [20], but rather a young population impulsive and hence the preponderance of male [2].The frequency of this etiology is certainly Page number not for citation purposes 4 underestimated in our study, where the patients attach their fracture at accident the work.
The management of boxer's fracture is still Controversial [1],Various operative techniques have been proposed for the surgical treatment of these fractures [4,21,22 ].the principles of treatment include restoration of articular anatomy, stable fixation of fractures, elimination of angular or rotational deformity and rapid restoration of mobility and function [23]. Although Flexible intramedullary nailing is indicated for any displaced or unstable fracture of the metacarpal neck [24].first described by Foucher In 1975, introduced the ″bouquet″ technique of closed anterograde nailing of metacarpal fractures using multiple small pre-bent K-wires, is currently one of the surgical procedures of choice [11].
We report the results obtained in 28 patients with a fracture of the neck of the fifth metacarpal, treated surgically using single Kirschner wire (K-wire) and followed-up at least 20, 75 months after surgery.
The majority of our patients, at surgery, presented a severe swelling of the surrounding soft tissues of the hand. We believe that the presence of a severe swelling of the soft tissues of the hand is one more reason to choose this type of treatment which minimizes the surgical trauma.
Intramedullary pinning and internal fixation with locking plates are the other two common methods of treatment for boxer's fracture.
Recently, in a comparative study on fifth metacarpal neck fracture fixation , Facca et Al [22] reported better results in the series stabilized with intramedullary K-wire in comparison to a second series treated with locking plates and immediate mobilization, In this second series treated with locking plates, the authors reported a deficit, despite immediate mobilization, of the MP joint due to the adherences of the extensor. Winter et al [25] In their short-term retrospective study, with a mean follow-up of 2.7 months, reported that in the boxer's fracture intramedullary pinning gave better functional outcomes than transverse pinning, although they concluded that intramedullary pinning is technically more demanding than transverse pinning and the surgeon has a more definite learning curve [25].
To the best of our knowledge a rare documents were published on percutaneous intramedullary nailing technique -by single k-wire-for treatment of fractures of the neck of the fifth the metacarpals [21,23]. Mohammed  We describe a surgical technique that contains of variety of technical of Foucher using a single wire of adequate diameter which is pre-bent to act as an elastic support With the elastic pre-bent wire with syndactylisation ,adequate stability is achieved to commence early mobilization. With minimal soft tissue dissection, avoidance of periosteal stripping and flexible fixation as opposed to rigid fixation, abundant periosteal callus is generated encouraging fracture healing [11]. In addition this procedure is relatively simple, with reduced operating times, minimal radiation exposure and can be performed as day case surgery thereby reducing hospital costs [26].The disadvantages of this technique are lack of absolute stability, wire migration, impalement of soft tissues, pin site problems, infection and the necessity for implant removal [11,27]. We had five patients had buried wires and the wire removed in the operatory block . It is worth mentioning that the metacarpal must be perforated laterally so that the extensor mechanism is not impaled by the wire. The diameter of the wire chosen depends on the bone and should be strong enough to resist minimal forces during early mobilization . Foucher's bouquet osteosynthesis method was described using three 0.8 mm wires. We aim to leave the wire protruding from the skin for ease of removal in the outpatient clinic, the wire is cut flush with the bone and is buried to allow wound closure. Wire migration has been reported to be common with this method and Foucher recommends leaving sufficient length of the wire to allow easy secondary removal. We had to revise one fracture as the wire had backed out loosing the reduction at the fracture site ( Figure 7); in these cases it is imperative to get ‗hockey stick' bend in the K wire at the correct length to be able to adequately hold the smaller distal fragment. All patients in our study except the one requiring revision were generally satisfied about the surgical experience.
Page number not for citation purposes 5 Our study has demerits in that few patient numbers are involved and that it is a retrospective analysis, however we have highlighted the merits of a very simple technique that saves operative time, adequately stabilizes the metacarpal neck fracture, promotes early mobilization, fewer complication rates and in general obtains a satisfactory outcome in the majority of patients. Larger, prospective studies may be required to validate the technique.

Conclusion
In conclusion, we recommend that this minimally invasive: percutaneous intramedullary nailing using a single in all boxers' fractures, especially when severe swelling of the hand is present, with good functional results and low morbidity.

Competing interests
The authors declare no competing interest.

Authors' contributions
All the authors have contributed to this study in ways that comply to ICMJE authorship criteria. All the authors have read and approved the final version of the manuscript. Table 1: characteristics of patients managed by K-wire Table 2: Angulation before and after surgery treatment