Extra-Articular Distal Phalanx Fractures

Extra-articular crush injuries to the distal phalangeal tuft are often highly comminuted and demonstrate very small fragments. Associated nailbed injuries often require operative management because they represent true open fractures, and inadequate reapproximation of the sterile matrix may result in delayed nail plate “lift off” and subsequent deformity.

Open fractures with fragments penetrating the nailbed may require only irrigation, debridement, reduction, and splinting. A well-reduced comminuted tuft or midshaft fracture is often adequately controlled by repair of the soft tissue envelope and immobilization. If the fracture pattern will permit fixation, longitudinal K-wires may be used to stabilize some of the fragments while providing a secure foundation for the sterile matrix repair. Care must be exercised to extract all soft tissue/nail bed elements from the fractured phalanx. For the first few days of immobilization, using a short arm splint minimizes discomfort and swelling. This is later replaced with a digital splint which supports the DIP joint extended and keeps the proximal interphalangeal (PIP) joint free to prevent unnecessary loss of motion of an unaffected joint.

Mallet Fractures

Mallet finger avulsion fractures are most often treated in a closed fashion with an extended splinting regimen. Relative indications for operative management of mallet fractures have been described according to the percentage of the articular surface involved, subluxation of the DIP joint, or overall influence of the loss of extensor continuity on the digital posture (i.e., development of swan-neck deformity).1–3

The more important determinant of mallet fracture management is the stability of the joint relationship. If the distal phalanx demonstrates any volar subluxation, even when placed in an extension splint, fixation of the fragment to which the terminal tendon is attached may be required. If subluxation is absent, the mallet finger may be treated with 6 to 8 weeks of DIP extension splinting followed by gradually resuming active flexion over the following 2 weeks. Some also advocate a transition to nighttime DIP extension splinting for an additional 4 to 6 weeks following full-time use.

Flexor Digitorum Profundus Avulsion Injuries

Avulsion injuries of the FDP tendon, with or without associated fractures, are always considered to be surgical problems because of the predictably poor finger function that results from nonoperative management. There is no accepted role for the nonoperative management of these injuries, except in patients who are unable to comply with postoperative rehabilitation, those who have low demands for hand use, or when the medical risks of surgery outweigh the advantages.

Extra-Articular Distal Phalanx Fractures

The extensor mechanism insertion is at the dorsal lip of the distal phalangeal epiphysis. The germinal nail matrix lies just distal to this insertion. The volar plate inserts onto the epiphysis and proximal metaphysis of the distal phalanx, whereas the FDP insertion flares outward at the metaphyseal region. The volar cortical margin demonstrates a much more significant metaphyseal flare than the dorsal cortex, making the medullary canal significantly dorsal to the mid-axis of the finger.

All distal phalanx fractures require an assessment of the nailbed. If a nailbed laceration is suspected, the nail plate should be removed and the nail matrix repaired. In the absence of a substantial nailbed injury or when only a minor subungual hematoma is present, the nail plate can be maintained as an assistant or substitute for fixation because it stabilizes some of the more minor distal phalangeal fractures.

Use of fixation in distal tuft fractures is indicated for injuries demonstrating displaced fragments large enough to provide purchase for a Kirschner wire (K-wire). Although outcomes of nonoperative management are generally good for simple distal phalanx fractures, fixation of these more complicated injuries may reduce the risk of symptomatic nonunion, nail deformity, and unstable digital pulp pads.4 Fixation is usually performed percutaneously by retrograde insertion of a 0.045- or 0.062-inch smooth K-wire under fluoroscopic guidance. Single pin fixation is often adequate, although two caveats are warranted. First, a single longitudinal pin may keep the fracture fragment aligned but not coapted with the phalangeal base; efforts should be made to compress the fragments together to improve the bony contact and stability. Second, even well-reduced fractures may easily distract or rotate along the shaft of the pin postoperatively. For this reason a second antiparallel pin should be utilized whenever the fracture and the patient′s anatomy will accommodate it.

Extensor Tendon Avulsion Fractures

The vast majority of mallet fractures do not require operative fixation. These fractures may be treated like their non-bony mallet counterparts with extension splinting. Even if these small fragments are not well reduced radiographically, the DIP articular surface remodels well, and adequate DIP extension usually results.

Rarely, a combination of injury to the extensor apparatus, oblique retinacular ligaments, collateral ligaments, and the dorsal fracture may cause or permit volar subluxation of the distal phalanx. In these most severe of mallet finger deformities, operative intervention is recommended.

There are two options for treatment of the subluxated mallet finger: combination closed pinning or open reduction and internal fixation (ORIF).

Because tenuous skin coverage, potential nail deformity, and terminal sensory nerve branch division are the real challenges of any open procedure about the distal phalanx, we have preferred to attempt closed treatment initially. The surgeon should not lose sight of the basic goal of DIP joint congruity by fully focusing on the relationship between the dorsal epiphyseal fragment and the remainder of the phalanx; however, it is logical and attractive to attempt both joint and fracture reduction.

An innovative method to accomplish both goals is a dual pinning technique that relies on indirect pinning or “levering” to reduce the displaced dorsal rim while the relationship is stabilized by a longitudinal joint-traversing pin (Fig. 21.2).5 The levering pin is inserted through the skin at an acute angle to the dorsum of the middle phalanx. The wire tip pierces the terminal tendon and comes to rest on the juxta-articular margin of the dorsal middle phalanx condyles, thus volar to the displaced distal phalanx fragment. The pin is then manipulated to lever the distal phalanx fragment into a nearly anatomic position and driven into the head of the middle phalanx. With the dorsal rim fracture and its attached terminal tendon now in a better position, the DIP joint is aligned and secured with a longitudinal pin.

As with any complex fracture, closed methods or percutaneous techniques may fail to deliver the desired outcome. In the very small subset of mallet injuries in which all closed methods have failed, and those manifesting considerable volar distal phalanx subluxation, an open approach may be employed. A zigzag incision is centered over a transverse limb along the DIP extension crease. Great care is taken to remove all soft tissue and callus blocking perfect manual reduction of both the joint and the fracture line. Multiple attempts at fixation of this fracture will inevitably lead to comminution or deformity of the fracture fragment and make a good result unobtainable.

Several steps are carefully executed to maximize results. A 0.045-inch K-wire is driven from the distal phalanx articular surface volar to the fracture line to the fingertip and withdrawn to the articular surface for passage across the DIP joint after fracture reduction. Care is taken not to place this wire within the fracture site to avoid creating an obstacle for complete reduction. With the DIP joint openly flexed, the PIP joint in extension, and the metacarpophalangeal (MCP) joint in hyperextension, the fracture fragment is reduced.

A second wire is then driven through the extensor tendon proximal to the bone fragment through the head of the middle phalanx at a 45-degree angle to the coronal plane. This wire acts as a blocking pin to proximal migration of the fragment. The pin should also be oriented from the midline to lateral on the sagittal plane. This provides ample mid-line space for passage of the longitudinal pin across the DIP joint after the joint is returned to the extended position and the fracture is reduced. A third pin may then be introduced perpendicular to the fracture plane through the fragment if it is large enough to accommodate additional fixation.

Other methods may be employed for fixation of these fractures, including K-wire fixation without blocking pins, tension-band wiring, and pullout suture/button or anchor fixation. Attempts to stabilize mallet fractures with mini-fragment screws are technically challenging, rarely satisfying, and have the potential to destroy the small fragment. In all cases, however, the goal is to avoid further compromise of the terminal tendon while reducing the DIP joint. A final caution is added against pinning the DIP joint in extreme (greater than 20 degrees) hyperextension. Although the DIP joint that is splinted in hyperextension tends to regain excellent flexion, those pinned in this position have a proclivity to remain stiff and less functional.

Flexor Digitorum Profundus Avulsion Fractures

The FDP tendon may rupture at its insertion, with or without an associated bony fracture fragment. These most commonly occur in the ring finger, although such injuries have been reported in all digits. Leddy and Packer6 described a well-accepted classification system, with four types of injuries. Type 1 injuries are nonbony FDP avulsions that retract into the palm. Type 2 avulsions contain a small fragment that retracts to the PIP joint level, with the A3 pulley preventing the fragment from further passage proximally in the tendon sheath. Type 3 avulsions are less common large fragment avulsions that are able to retract only to the A4 pulley level just proximal to the DIP joint. All of these injuries have been considered surgical problems due to the predictable loss of active DIP flexion. Particular attention is paid to the timing of surgical reconstruction due to the tendon biology and the risk of extensive musculotendinous shortening over time.

Type 1 avulsions are best treated as acutely as possible. Retracted tendons have complete disruption of the normal dorsal vincula and their blood supply. Repair should be pursued within 7 to 10 days of the injury to avoid degeneration and contraction of the tendon stump.

Type 2 and type 3 avulsions may be repaired at a remote time, although repair remains easiest within 7 to 10 days after injury. Several considerations warrant early intervention. Although the position of the bony fragment may be determined radiographically, a tendon detachment may also have occurred at the fragment–tendon interface, leaving the fragment in the finger while the tendon has retracted to the palm (type 4 injury). Although unusual, this condition warrants the urgency of the type 1 nonbony avulsion in the setting of a fracture/avulsion. Furthermore, the benefits of delayed repair (decreased swelling, joint mobilization) are difficult to obtain with the continuous presence of a fracture fragment within the flexor tendon sheath. There is no specific time limit on the viability of primary repair in these injuries; therefore, it may be generally feasible for a matter of weeks to months.

The surgical approach is via a midaxial or volar zigzag incision. Care is taken to minimize trauma to the sheath and its contents. In a type 1 or 4 avulsion, a counterincision is made in the palm over the A1 pulley, and a pediatric feeding tube is passed from distal to proximal through the tendon sheath. The retracted tendon should be readily located in the palm because more proximal migration is prevented by the muscular origin of the lumbricals. The feeding tube is used to escort the tendon through the intact sheath. A distally based periosteal flap is raised at the site of the avulsion, and the cortex is roughened to create an inflammatory nidus for adherence of the reattached stump. Using a stout, double-armed monofilament suture, the tendon may be reattached though predrilled holes from the reattachment site to the dorsum of the nail at the level of the lunula and secured over a bolster and a button. The periosteal flap is sutured volarly over the inset tendon for additional security. The monofilament suture is cut and removed with the button 4 weeks later after adequate strength of the repair is established. Gapping at the repair site is a known concern with this technique. Alternatively, a buried anchor may be used under the same periosteal window to provide fixation to the insertion site without the need for an external button. This provides the security of long-term support of the repair during healing. These anchors must be placed obliquely and with care to obtain good purchase while not violating the dorsal cortex/nailbed. Bone pullout is a potential complication with this technique.7

Type 2 fracture fragments are often very small and can be treated similarly to type 1 avulsions after either resection of the small fragment or simultaneous fixation of the fragment and tendon reinsertion achieved by sutures woven through the tendon–fragment interface. The anchor or button repair may securely maintain excellent reduction of these smaller fragments.

Type 3 fractures are large enough to require fixation of the bony fragment with K-wires. Attention should be paid to accurate alignment of the articular surface. These fragments may contain the majority of the joint surface, and instability may exist without anatomic reduction. Fixation with multiple K-wires, including at least a single wire holding the DIP joint in extension, is usually necessary.

Transverse Shaft Fractures

The realistic choices for treatment of a transverse diaphy-seal fracture are pins or plates; simple interfragmentary screws are not useful because of the horizontal fracture orientation. The decision on whether to pin or plate is based on the behavior of the fracture and the potential for optimizing outcome by striking the optimal balance between surgical morbidity (favoring closed pinning) and potential for an accelerated rehabilitation program (favoring plating).

One of the most effective, yet technically challenging, methods of closed treatment is collateral recess pinning. Using this technique, one or two pins are introduced from the phalangeal head region in a retrograde direction, crossing the fracture plane and penetrating the subchondral bone or opposite endosteum of the proximal fragment. When two pins can be accommodated in the canal, this crossing construct provides rotational control. Pins are kept extra-articular in the distal aspect of the phalanx in an effort to minimize joint stiffness. The collateral ligaments of the IP joints originate dorsal to the axis of rotation of the phalangeal head. Here the collateral recess provides a bony landmark for palpation. This surface irregularity in the phalangeal shaft offers purchase for the introduction of the very obliquely oriented pins, preventing extracortical deflection (Fig. 21.4).

Tips and Tricks

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  When utilizing the collateral recess pinning technique, two technical tricks should be employed. The two pins should initially be placed only up to the fracture plane. One pin may then be used as a joystick to aid in reduction under fluoroscopic control while the second pin achieves initial fixation. The rotation is then assessed prior to passage of the second pin. The most difficult part of this technique is the oblique introduction of the pins. This should be achieved first so that the required manipulation does not disrupt an initial reduction or single pin fixation. The second technical consideration is soft tissue management. Introduction of the pins should be attempted with the finger in the intrinsic plus position (IP extended). This prevents the percutaneous pins from both tethering the soft tissue and mechanically blocking IP joint extension.

  
  
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  For selected extra-articular transverse fractures of the proximal phalangeal base that are unstable and may not be amenable to the use of a condylar blade plate, a specific transarticular pinning method provides both fracture stability and internal splinting of the MCP joint in flexion, the lengthened position for the collateral ligaments. As described by Belsky et al,8 this technique is simpler than collateral recess pinning and avoids manipulation of the soft tissue envelope of the PIP joint (Fig. 21.5). The fractures are reduced with distraction and MCP flexion. A K-wire is introduced through the head of the metacarpal and into the base fragment of the flexed proximal phalanx. The wire is driven to the level of the fracture line. This first maneuver stabilizes the small proximal fragment and makes an accurate reduction under image intensifier more easily obtainable. Distraction and flexion across the fracture plane provide reduction that can be secured by driving the wire across the fracture line and into the medullary canal. After the first wire is in place, meticulous assessment of digital rotation provides an opportunity to adjust the final reduction prior to passage of a second antiparallel wire to hold rotation (Fig. 21.6). This second wire may be driven through the metacarpal head or may alternatively be introduced via the lateral cortical margin of the phalangeal base—a technique that is particularly well suited for the radial border of the index digit and the ulnar border of the small digit.

Spiral Oblique Fractures

In our experience, these fractures are best treated with interfragmentary screw fixation (Fig. 21.7), which provides the rigidity and early motion benefits of internal fixation without the prominence and excessive tendon contact of plating. Most often seen in the proximal phalanx, these fractures can be approached via a gentle curvilinear incision over the proximal phalanx. This incision should sweep volar to the finger′s mid-axis at the PIP joint level to maximize exposure. Although longitudinal splitting of the extensor tendon is commonly employed, we prefer one of several other extensor handling options to provide exposure with minimal postoperative adhesions.

Wide exposure may be achieved by excision of one of the oblique bands of the extensor hood distal to the MCP joint sagittal bands and lateral to the central extensor tendon (Fig. 21.8). Excising this triangle of extensor on the radial aspect of the digit also minimizes the chance of postoperative intrinsic adhesions.9

An alternative deep exposure that is used when a fracture line extends over the entire diaphysis, or even enters the PIP joint, is the Chamay exposure.10 In this seldom-needed but rather useful technique, the extensor apparatus is incised as a distally based V, with the central slip insertion on the middle phalanx as the base of this tendon flap (Fig. 21.9).

Thorough clearance of debris in the fracture plane, meticulous reduction, provisional wire fixation, and attention to proper technique are the ingredients of a successful result with these fractures. As with all applications of interfragmentary screw fixation, care should be taken to introduce the screws out of plane in relation to one another and sufficiently distant from one another and the fracture line to prevent iatrogenic fragmentation.

Comminuted Phalangeal Shaft Fractures

These fractures usually result from higher energy mechanisms, so that the soft tissue envelope is often compromised; in addition to assessment of skin integrity and fracture pattern, determination of neurovascular status is particularly important. The outcome of these injuries is predictably poorer than the outcome of noncomminuted phalangeal shaft fractures, and fixation can be more challenging.

If comminution is minimal, percutaneous pinning may provide adequate control of the major fragments and maintain alignment during the healing phase. Moderately or severely comminuted phalanx fractures often display an intact base and head with primarily central diaphyseal destruction. These fractures may best be addressed with mini-condylar blade plating (Fig. 21.10). This technique provides a rigid construct to prevent shortening and malrotation. A 1.5-mm mini-fragmentary system should be used on the proximal or middle phalanx. The blade may be placed proximally or distally and should be used on the end with less length of intact bone (i.e., where the greatest need for the stability of the blade construct exists).

The ideal position for plate placement is subject to several key factors: purchase of the blade and juxta-articular screw, maximization of cortical contact when the fracture is reduced, and purchase of the screws into diaphyseal fragments. These factors can usually be addressed while also placing the plate along one of the lateral margins of the phalanx, thus minimizing its contact with the extensor mechanism.

After one of the appropriate extensor-side exposures is obtained, the blade is introduced first. We have typically employed a smooth 0.045-inch K-wire for provisional reduction; the wire can later be exchanged for the screw that accompanies the blade, so that it is placed in a slightly eccentric position. The location of the blade is then determined by direct visualization using the selected implant.

The hole for the blade is predrilled parallel to the articular surface with the 1.5-mm drill bit. The plate′s blade is cut to match the measured depth. Although most commercially available systems have precontoured their plates to accommodate the metaphyseal flare, additional plate bending may be desired. The advantage of leaving in the provisional K-wire is now apparent because the screw hole aperture in the plate adjacent to the blade can be slipped over the pin to guide the plate into position.

Often, we have found it useful to employ a reduction clamp or other compression device to firmly seat the blade in position. After confirming reduction and length/position of hardware, the parallel screw is applied at the base of the plate locking the plate into position. The rest of the screws are then applied along the available cortical bone across the fracture site.

In some of the most severely comminuted phalangeal fractures, there is insufficient purchase for plate or wire fixation. In this setting external fixation is an option to consider. It may be constructed with K-wires and elastics, or commercially available fixators may be used. The specifics of the use and applications of external fixation devices on the phalanges are discussed in greater detail in the next section. The fixators can be either joint spanning or non-spanning (Fig. 21.11), as well as either fixed or dynamic.

Regardless of the selected method of fixation of these comminuted fractures, always consider the need for bone graft. These fractures are often impacted and demonstrate poor bony contact of fragments. Small portions of cancellous bone can readily be harvested from the dorsal distal radius through a corticotomy created on the floor of the second extensor compartment immediately proximal to Lister′s tubercle. Alternatively, some surgeons prefer harvesting graft from the volar approach under the pronator teres; this site can yield excellent corticocancellous graft for spanning large intercalary defects. Exposure is provided through a minimal incision between the long digital flexors and the radial artery (volar approach of Henry). A third option in the setting of multiple digital trauma is bone graft from other amputated digits (spare parts) if applicable and available.