Metacarpal and Phalangeal Fractures

Arches of the Hand

The hand is composed of two arches: one of these is transverse and corresponds with the metacarpophalangeal (MCP) joints; the other is longitudinal and is aligned along the third digital ray. These two arches of the palm give the hand its cupped shape, which facilitates prehension. The second and third metacarpals are fixed to the second carpal row, whereas the first, fourth and fifth metacarpals are mobile and contribute to cupping of the hand and improved prehension.

The fixed second and third metacarpals do not tolerate angulation well, and all therapeutic options must be considered to restore their anatomy. The fourth and fifth metacarpals, however, tolerate angulation better owing to both their carpometacarpal (CMC) mobility and the possibility of hyperextension of the MCPs.

Hand grip strength is retained if the metacarpal arch is restored. It is hence desirable to reduce oblique and spiral fractures so as to reestablish the length and axis of the metacarpals. Meunier has shown that a metacarpal shortening of just 2 mm results in an 8% loss in the intrinsic functional strength. He determined the loss to be 55% when the shortening was of the order of 10 mm. Low noted a decrease in extrinsic function starting with 3 mm of shortening and a variation of 30 degrees in the angle.

The digits are articulated around the MCPs, which have an active flexion of 90 degrees. The proximal interphalangeal (PIP) joint and distal interphalangeal (DIP) joint flex to 100 degrees and 70 degrees, respectively.

Each digital chain can achieve this function only if its metacarpal and phalangeal lengths match with Fibonacci's numerical series (0, 1, 1, 2, 3, 5, 8, 13, 21 …). Thus the length of the first phalanx is the sum of that of the middle and distal phalanxes. This highlights the need for a treatment that accurately restores the length of each component of the skeleton. In this context Strauch noted a loss of 7 degrees of extension for every 2 mm of skeletal shortening.

Although they appear parallel in extension, the long digital chains converge toward the scaphoid tubercle upon flexion. The occurrence of a rotational malalignment by more than 5 degrees has an adverse impact on function, particularly if there is scissoring. The thumb retains its key functions as long as the trapeziometacarpal (TMC) joint is free and the first commissure has not been compromised by any contracture. Furthermore, it can tolerate a certain degree of stiffness of the MCP and IP joints.

Mechanisms of Deformity

These have been well described and analyzed by McNealy and Lichtenstein.

Metacarpal Fractures

The action of the flexor tendons and interosseous muscles results in palmar flexion of the distal bone fragment and dorsal opening of the fracture site. This deformation is even more pronounced with regard to metacarpal neck fractures ( Fig. 7.1 ).

The interosseous muscles also induce an axial rotation of the distal fragment. The second and third metacarpals have a tendency to pronate (ulnar rotation), whereas the fourth and fifth metacarpals have a tendency to supinate (radial rotation). These deformities may go unnoticed when the fingers are in extension. Only placing the digits in flexion will reveal the deformity, which manifests itself as an overlap of the fractured finger with its neighbor ( Fig. 7.2 ).

All attempts to reduce a fracture must ensure that they restore the convergence of the fingers toward the scaphoid tubercle.

Through their contractile power the interosseous muscles shorten metacarpals that have long oblique or spiral fractures.

With a Bennett fracture the first metacarpal is displaced upward and outward through the action of the abductor pollicis longus and thenar muscles ( Fig. 7.3 ).

A fracture at the base of the fifth metacarpal triggers the same phenomena through the action of the extensor carpi ulnaris (see Fig. 7.3 ).

Direct and axial traumas to the metacarpals of the digits generate fractures and dislocations at their base. The palmar bone fragment remains associated with the carpal bone. Through the action of the radial wrist extensors, the second and third metacarpals become dislocated in an upward and proximal direction, thereby generating a dorsal bulge like the “back of a dinner fork,” although this is often masked by edema and a hematoma.

Phalangeal Fractures

Proximal Diaphyseal Fractures

Through the action of the interosseous muscles the proximal fragment flexes, whereas the distal fragment is placed in extension by the action of the lateral bands of the extensor apparatus. This results in a recurvatum with palmar opening of the fracture site ( Fig. 7.4 ).

Lateral tilting of the distal fragment is more clinically obvious; it depends on the nature of the injury and pattern of the fracture. On the other hand, axial rotation is common but can only be diagnosed clinically or by radiography with the finger in a flexed position.

Middle Diaphyseal Fractures

When the fracture is proximal to the superficial flexor tendon insertion, the proximal fragment is pulled into extension by the central slip of the extensor tendon and the distal fragment is flexed by the action of the superficial flexor. The deforming forces create an open dorsal angulation ( Fig. 7.5 ). When the fracture is distal to the superficial flexor tendon insertion, the proximal fragment moves with flexion and the distal fragment in extension. This creates an open palmar angulation ( Fig. 7.6 ).

Consolidation Time Frames

These are typically from 3–5 weeks for metacarpal and epiphyseal fractures, 5–7 weeks for diaphyseal fractures of the proximal phalanx, 7–10 weeks for the middle phalanx, and 3–4 weeks for fractures of the distal phalanx. Open fixation doubles these times. Finally, additional factors come into play, such as the extent, the mechanism, the energy of the injury-causing trauma and the presence of associated injuries (eg, joint involvement, soft tissue contusion, comminution of the site, neurovascular pedicle injuries). Just like the quality of the reduction and fixation, the patient's age, their metabolic state and possible tobacco use also affect the prognosis.

Clinical Examination

Hand deformities resulting from one or more skeletal fractures are not always readily apparent because they may remain hidden by edema or hematomas. Although a recurvatum deformity of the phalanges can be readily diagnosed, oblique or spiral fractures are often not apparent on a finger in extension. It is through careful flexing of the finger that a rotatory malalignment can be seen. Flexion of the MCP joints reveals the metacarpal arch. In the case of a fracture of the metacarpal neck, the knuckle becomes less prominent, and if there is much angulation, the head can be felt in the palm of the hand at the distal palmar crease. This can be a hindrance with physical labor, especially when gripping. The clinical examination must always be completed by an assessment of the tendon apparatus and neurovascular pedicles.

Radiologic Examination

The radiologic examination of a fracture must be performed carefully and should not be limited to a single posteroanterior (PA) and lateral view of the hand.

For the metacarpals, angled exposures at 45 and 60 degrees allow for resolution of the bone overlaps that occur with a lateral view ( Fig. 7.7 ). Anomalies of the metacarpal rays are searched for on the PA exposures, with any shortening arousing suspicion if there is no obvious injury. Despite the overlap, an entirely side-on view is very useful to assess interfragment separation in the case of a long oblique fracture to rule out an associated CMC dislocation. The latter are often difficult to see on PA and oblique exposures (see Chapter 6 ).

For the thumb we use the Kapandji views :

• Static PA views ( Fig. 7.8 ): the forearm and hand rest on their ulnar side, with the hand in semipronation, the wrist at 15 degrees of extension, the coronal plane of the thumb parallel with the table. The adjacent digit is inclined obliquely in a vertical position at a proximal angle of 30 degrees and centered on the MCP joint.

  

• Static lateral views ( Fig. 7.9 ): the wrist is in ulnar inclination and in 20 degrees of extension, the thumb aligned with the radial side of the forearm, the hand in pronation. The thumb and forearm rest on their radial side, the fingers flexed so as to lift the metacarpal off the surface of the table by 30 degrees. The beam is vertical and centered on the MCP joint.

  

• Dynamic exposures assume the same positions as for static ones, with the thumb in hyperabduction, then in hyperadduction for the PA exposure, then in hyperflexion and hyperextension for the lateral view.

The Brewerton scale, originally for assessment of erosive injuries encountered at the head of the metacarpals with rheumatoid arthritis, is equally of great relevance for assessing traumatic MCP joint injuries. The hand is placed with its dorsum on the radiographic cassette, with the MCP joints bent to 65 degrees and the digit at an inclination of 15 degrees toward the ulnar side of the hand ( Fig. 7.10 ).

Functional Treatment

Functional treatment relies on immediate and careful mobilization. Weeks, de La Caffinière and Mansat observed that one-quarter of cases of finger stiffness are due to a hand fracture. Early, if not immediate, mobilization is the best way to combat edema and joint stiffness and to preserve tendon gliding. The best dynamic orthosis to promote mobilization while also protecting against excessive movement is achieved by buddying the injured finger with its neighbor with Elastoplast or Velcro bands that hold them together ( Fig. 7.11 ).

Splinting

Splinting with or without prior reduction requires immobilization in a position that minimizes hand stiffness. Immobilization with a splint is a necessity for fractures that are deemed to be unstable, although this results in stiffness in numerous joints. Too many fingers are assigned to tongue depressors, which should never have left the otorhinolaryngology setting.

Attention must therefore always be given to the immobilized position, also referred to as the safe position, because it prevents joint stiffness by keeping the collateral ligaments stretched. This is the intrinsic-plus position, with the wrist in extension at 20 degrees, the MCP joints flexed between 40 and 60 degrees and the IPs in extension or very slight flexion (15 degrees at the most). The various positions of immobilization are derived from this basic position.

Immobilization follows the principle of stabilization of the injured segment and the adjacent joints.

Use of Orthoses Made From Thermoplastic Materials

Use of orthoses made from thermoplastic materials is preferable because they are customized to fit the injured person's anatomy, thereby leaving the uninjured fingers and joints free so as to limit stiffness. These orthoses can be altered successively to match reduction in edema or resized if progress with the consolidation allows additional digital segments to be freed ( Figs. 7.12 and 7.13 ).

As a general rule, 3 weeks are sufficient to stabilize the fracture site. Beyond this time frame, active rehabilitation with use of a dynamic orthosis will allow for functional restoration. From 3–6 weeks are required to regain mobility in a sector, beyond which manual labor is allowed.

Nonoperative management should not be seen as withholding more advanced therapies, and the choice of a suitable method is paramount if a favorable outcome is to be expected. Indeed, the majority of hand fractures are amenable to nonoperative treatment.

Percutaneous Fixation With Wires and Screws

Percutaneous fixation with wires and screws is recommended when reduction can be achieved by external means. The closed approach avoids devascularization, limits injuries at the surgical site and preserves the hematoma and its valuable growth factors. It is indicated for cases of simple displaced fractures, and the conferred stability often allows early mobilization.

Conversely, this method is also suitable for highly comminuted fractures, for which access to perform a direct fixation has little chance of success. The aim is then to restore the length and proper rotation of the injured segment, even if this arrangement will not always allow for immediate mobilization. Furthermore, it will allow stabilization of a fracture for which the contused or injured adjacent covering does not allow for open fixation ( Fig. 7.14 ).

Axial and Cross-Wiring

Pratt and Von Saal proposed the use of Kirschner wires for hand surgery. They are preferably introduced from the dorsolateral side of the finger, while avoiding damaging or blocking the extensor apparatus ( Fig. 7.15 ). Depending on the size of the bone, the Kirschner wires are 1.0 or 1.2 mm and are introduced with a powerful driver at a slow rotational speed to avoid heating and burning of the cortical bone. The use of wires must avoid fixing uninjured joints, and it is preferable to perform oblique wiring through the lateral surfaces of the metacarpal and phalangeal heads. A single wire is insufficient to stabilize the fracture site and can act as a rotational axis. The second wire must be introduced from the opposite side so as to form a crossed assembly. It is best to manually maintain axial compression of the fracture site at the time of introduction so as to avoid creating a physical separation of the bone at the fracture site.

When wiring of an unstable fracture proves to be difficult, it is prudent to introduce a temporary axial wire that will restore the alignment. Once the two crossed wires are in place the assembly is strong enough to remove the axial wire. This assembly, referred to as an “Eiffel Tower,” was proposed by Tubiana and assists the surgeon with his or her effort while also protecting the injured individual from a malunion ( Fig. 7.16 ). Wires in the vicinity of joints impede capsular-ligament movement, and the risk of neurovascular pedicle injuries is not insignificant. Furthermore, the rate of sepsis, pseudarthrosis and/or malunions remains relatively high (25.3%).

Intramedullary Wiring of Metacarpals and Phalanges

This is based on the principle of elastic fixation promoted by Hackethal and Ender. For extraarticular fractures of the base of the first metacarpal, Kapandji has proposed a crossed ascending double wiring whereby the wires are introduced through the lateral surfaces of the first metacarpal head ( Figs. 7.17 and 7.18 ). A similar technique can be used for the intermediate phalanges by following the three-point support by elastic stable intramedullary nailing (ESIN) of Métaizeau. For the fifth metacarpal, Foucher uses multiple intramedullary wires introduced through a cortical window at the base of the fifth metacarpal ( Fig. 7.19 ).

Transverse Metacarpal Wires ( Fig. 7.20 )

In 1973 Lamb published his experience with transverse wiring of unstable metacarpal fractures. He thereby paid homage to a little known old idea of Berkmann and Myles. The healthy metacarpal constitutes a “biological” external fixator, allowing stabilization at the fractured digit while maintaining its length and its axis. Furlong used this to stabilize unstable fractures of the fifth metacarpal neck (see Fig. 7.20, [2] ). James (see Fig. 7.20, [1] ) also recommended it for the treatment of unstable metacarpal fractures. This method is starting to be developed to treat metacarpal fracture-dislocations and to maintain the length of the metacarpal when there is bone loss ( Fig. 7.21 ; also see Fig. 7.20, [3] ). It is the best way to neutralize the palmar flexion stresses exerted by the interosseous muscles on one or more distal fragments of fractured metacarpals. Johnson proposed single transverse wiring to treat Bennett fractures (see Fig. 7.20, [4] ). In the same way, Iselin uses two divergent wires to better stabilize the first metacarpal and prevent retraction of the first commissure.

Treatment by Rigid Open Fixation

Treatment by rigid open fixation requires specific equipment. Following a period of great enthusiasm that was prompted by the emergence of AO devices, many users pointed out that the bulky size of the implants—the screws and plates in particular—injured the extensor apparatus when applied to the dorsum of the metacarpals and phalangeals. In 1974 Heim and Pfeiffer, who were the initial proponents of this method, observed that treatment of the phalangeals with such implants ultimately yielded mostly unsatisfactory outcomes, while the surgery could prove very difficult in and of itself. Biomechanical studies have now established that the stresses placed on the digital chain during extension and flexion motion are minimal. Based on these measurements, Foucher and Merle have developed Osteo, which is a miniaturized apposition device that has now been reproduced by the majority of manufacturers of such biomechanical items. Stryker Leibinger ( Fig. 7.22 ) and DePuy Synthes have developed a wide range of screws and plates. In practice, screws of 1.1, 1.2, 1.5, 1.7, 2.0, and 2.3 mm in diameter and straight “L” and “T”-shaped plates with thicknesses of 0.55 and 1 mm cover the various fixation requirements that are typically encountered. These sectionable plates are sufficiently malleable to be custom designed and applied as close as possible to the bone ( Fig. 7.23 ).

Osteosynthesis of the hand conforms with the biomechanical principles laid out by the AO and with conventional assemblies. Primary stability and contact are key parameters. Direct screw fixation with compression perpendicular to the fracture line is used on long oblique or spiral fractures. Short oblique or spiral fractures call for a compressive interfragment screw fixation with a neutralizing plate in apposition. Complex fractures combine screw fixation, plates and cerclage wiring to align the intermediate fragments on the plate.

The plates are preferably installed on the dorsolateral sides of the phalangeals to avoid tendon adhesions ( Fig. 7.24 ). Full dorsal application of the device leads to exposure to a double risk of adhesion of the extensor to the plate and catching of a flexor tendon by a protruding screw. On the metacarpals, the implantation is lateral on the distal part and more dorsal at the level of the median and proximal diaphysis; this is to counter strong stresses during flexion. In the last few years, bioengi­neering has allowed for the use of locking screws with these miniplates. This simplifies the treatment of highly comminuted injuries and multifragmented epiphyseal plates while offering increased stability that allows early mobilization.

Treatment by External Fixation

Treatment by external fixation is not often used in the hand. It is essentially restricted to multitissue injuries of the thumb column and for PIP joint fractures. In 1974 Crockett suggested the use of an external construct to fix digital arthrodeses with Kirschner wires that are joined together with acrylic resin. Scott and Mulligan and then adherents of Vilain's teachings specified their indication in complex traumas of the hand and in osteoarthritis ( Fig. 7.25 ). In 1973 Allieu adapted Hoffmann's external fixator for the hand, and they recommended assembly in a single section with transfixing wires for the thumb column.

In terms of the digits, to retain full joint movement it is best to use oblique dorsal wires joined together by small tie rods. Hoffmann's minifixator allows such assemblies on the digital chain, and it is compatible with mobilization. Its use remains tenuous, however, when the wires are anchored in small juxtaarticular bone fragments. This necessitates reliance on the adjacent skeleton and on the bridging of intact joints. The use of this must remain restricted to complex traumas of the thumb column when the loss of bone and skin cannot be treated in an emergency ( Fig. 7.26 ). For the first metacarpal the Orthofix Pennig Minifixator allows stabilization by a “minirail” system or ready-for-use articulated device, but its size limits its use almost entirely to the thumb.

More recently, dynamic external fixation processes with varying degrees of complexity have emerged that allow joint distraction mobilization. These devices are suitable mainly for smashed PIP joints, with entities as described by Suzuki or the Ligamentotaxor (Arex) developed by Pélissier ( Fig. 7.27 ; also see Fig. 7.50 ).

Temporary Fixation

Temporary fixation is useful for severe multitissue injuries or with major loss of bone. A minimal fixation is performed in light of the frequent contamination of these injuries. It relies on wires and individual screws to reassemble an epiphyseal plate, along with a wire cerclage that makes a multifragmented diaphysis look like a bundle of wood. The length and axis of the digital chain are maintained in neutral by an external fixator or by interposition of a spacer that may be cemented in and equipped with wires. Once there is no risk of infection and there is adequate soft tissue coverage, the spacer is replaced by a corticocancellous graft or a more stable fixation (see Figs. 7.21 and 7.26 ).

Distal Phalanx Injuries

Fractures of the distal phalanx are the most common and most often affect the thumb and the middle finger. The diagnosis is strictly by PA and lateral x-rays. Schneider distinguishes between fractures of the tuft, the diaphysis and the base.