Novel Mini-Invasive Surgical Technique for Treating Fifth Metacarpal Neck Fractures: A Case Report

Background

Metacarpal fractures alone account for about 40% of all hand fractures, generally in young, healthy men, leading to absences from work [1]. Fifth metacarpal neck fractures are common, usually resulting from a direct, axial trauma (eg, from punching with a closed fist); this fracture is sometimes called a boxer’s fracture [2]. Transverse metacarpal neck fractures often result in an apex dorsal angulation. Biomechanically significant functional decrease in flexor tendon efficiency occurs in the fifth metacarpal neck with angulations over 30°, due to slack in the flexor digiti minimi and third volar interosseous [3]. Metacarpal neck fractures with serious rotation or shortening cannot be effectively controlled through entirely non-operative means. Only if there is no shortening, angulation, or rotational malalignment, will the fracture be eligible for closed methods [1–3]. First, fracture reduction should be achieved by the Jahss maneuver, as recently proposed [4]. Correcting rotational alignment is the most important factor in reduction. The common techniques for fixation of unstable metacarpal neck fractures that cannot be treated by casting alone are closed reduction and internal fixation and open reduction and internal fixation using plates and screws [3]. Closed reduction and internal fixation is the treatment of choice for isolated meta-carpal neck fractures not meeting the criteria for non-operative treatment; intramedullary pinning, percutaneous pinning, bouquet pinning, and minimally invasive pinning can be valid alternatives [5–9]. All these techniques can however lead to complications and drawbacks [10–15].

This report is of a 25-year-old male Italian pianist with a displaced fifth metacarpal neck fracture successfully treated by reduction using the Jahss maneuver and K-wire attachment of subchondral bone to the metacarpal.

Case Report

A 25 year-old, right-handed, male professional pianist presented to the hand clinic with a trauma (punch against wall) to his right hand, sustained 2 days earlier. Physical examination demonstrated swelling, pain, functional limitation, and mal-rotation of the fifth finger. Radiographic images confirmed an angulated, displaced right fifth metacarpal neck fracture that did not involve the articular surface (Figure 1). The patient’s pathological anamnesis, surgical history, and family medical history were not relevant for the case. The patient’s functional ambition and aspirations were a complete return to pre-lesion range of motion and bone stability, especially the achievement of abduction and extension. The surgical procedure was performed under locoregional anesthesia with a pneumatic tourniquet. An intraoperative image intensifier was used. We reduced the fracture by the Jahss maneuver, through a 90° flexion of the metacarpophalangeal joint and proximal inter-phalangeal joint and pressing upward on the flexed finger to correct angulation. After confirmation by the image intensifier of the correct achievement of fracture reduction, a 1.6-mm K-wire, mounted in a wire-driver drill, was inserted into the metacarpal head in a retrograde direction from the ulnar side of the metacarpal head, while manually maintaining the reduction. Similarly, another 1.4-mm K-wire was inserted in a cross-retrograde direction from the radial side of the metacarpal head and drawn back gently from the base of the meta-carpal bone until its distal tip was situated at the subchondral level of the metacarpal head. The image intensifier confirmed good fracture alignment and stability on passive mobilization (Figure 2). Final intensifier pictures were obtained (Figure 3). A customized ulnar gutter splint, including the forearm and hand, was applied with the wrist extended 20°, the metacarpophalangeal joint flexed 60°, and the interphalangeal joints in complete extension. At 1 week after surgery, the splint was changed to a thermoplastic one, and physical therapy at the piano was started. At 1 month after radiographic confirmation of bone healing, the first K-wire was removed; the second was removed 45 days after surgery. At 3 months after surgery, full range of motion was achieved and, in 4 months, complete recovery of strength (Figure 4). The patient agreed to participate in this case and gave informed consent.

Discussion

Several surgical techniques [5,6] have been described for these kinds of fractures, and there is currently no consensus regarding the optimal fixation technique. We believe minimally invasive fixation could be promising and, in this report, describe a new minimally invasive surgical technique of a fifth metacarpal neck fracture in a high-demand young pianist.

Bouquet pinning is performed by placing 3 K-wires with a dorsal bend [7]. This minimally invasive technique provides good postoperative range of motion if prolonged immobilization is prevented from tendon adhesion and joint contracture. However, bouquet pinning also represents a complex procedure with long learning curves. It is performed through a minimally open access, producing a dorsoulnar scar [8].

Intramedullary fixation is performed with antegrade placement or retrograde fixation improving range of motion, compared with pinning, and a lower incidence of shortening, but at a greater economic cost, higher risk of limited rotational stability and nonunion/malunion [8,10,11]. Moreover, intramedullary fixation can jeopardize the terminal divisions of the dorsal ulnar nerve branch, causing neuritis [12].

Percutaneous pinning includes the anterograde and retrograde intramedullary technique, percutaneous transverse, and retrograde cross-pinning fixation [9,10]. A cadaveric anatomical study demonstrated that this closed percutaneous approach can damage the surrounding tendons and neurovascular structures. In particular, retrograde pinning has been shown to produce injury both to the extensor digitorum communis and the extensor digitorum minimi tendons, the anterograde technique to the extensor carpi ulnaris, transverse pinning to the dorsal branch of the ulnar nerve, and retrograde cross-pinning to the digital branches of the dorsal cutaneous ulnar nerve [12].

Plate and screw fixation can be accomplished with retraction of the extensor tendons and subperiosteal exposure of the metacarpal neck. Volar cartilage can also make distal fracture fragment fixation difficult [13]. This technique offers stable fixation and can be conducted when comminution precludes closed reduction and percutaneous pinning. Complications include higher rate of stiffness, metacarpal head avascular necrosis, extensor tendon injury, and adhesion [13–15].

In a recent report, the importance of minimally invasive pinning techniques was pointed out and a single-K-wire retrograde pinning technique was described [9]. However, the authors describe surgical access at the base of the fifth metacarpal together with protection of the branches of ulnar nerve. We believe our approach may be better, as no surgical incision is needed, and this will produce no scar on the dorsum of the hand. Moreover, our technique does not need bending of K-wires, making their insertion technically easier. Also, the use of 2 wires that are removed at different times makes early mobilization easier, with a faster return to work (in our case, playing music).

Our technique prevents traumatizing the extensor tendon cuff by piercing the metacarpophalangeal joint capsule, which can cause extensor tendon dislocation and instability and pain and retraction of the extensor cuff. For patients who need high-demand functionality of the metacarpophalangeal joint, such as pianists, these surgical complications can lead to loss of extension and abduction, movements whose minimal loss is a great harm to a pianist.

This report has limitations. As it is a single case, further investigation and clinical studies should be conducted to evaluate whether this new technique could be a standard approach.

Conclusions

We describe a novel minimally invasive surgical technique of a displaced fifth metacarpal neck fracture in a young pianist with high-demand functionality. Unlike other techniques, our operative approach had the advantage of preventing extensor tendon dislocation and instability and nerve injury, and it allowed early joint motion, joint stability, and complete recovery of movements in all planes.

Further studies should be conducted to evaluate whether this new technique could be a standard approach.