Hand fractures and joint injuries

7 Hand fractures and joint injuries






Introduction


Fractures of the phalanges and metacarpals are the most common fractures in the upper extremity and have been reported to account for 10% of all fractures.1 Appropriate diagnosis and treatment can minimize deformity and maximize function. Although many of these fractures can be managed nonoperatively, appropriate follow-up is crucial for a good outcome. These injuries can result in time away from work and activities and can be complicated by stiffness and weakness. The goal of the treating physician should be to minimize deformity and maximize function. Operative indications depend on multiple factors, including stability, location, geometry, configuration, and associated injuries, but ultimately, is chosen when the anticipated outcome is better than nonoperative management.2


The goal of treatment of fractures in the hand is to reduce and stabilize the fracture, maintain the reduction and begin rehabilitation to restore function. The treating physician must take into account the vocation and avocation of the injured patient, as this may affect the treatment.



Anatomy


The metacarpals and proximal and middle phalanges are anatomically divided into the head, neck, shaft, and base. The distal phalanx is divided into the tuft, shaft, and base. The carpometacarpal (CMC) joints of the index and middle fingers have little mobility, while the ring and small fingers have some motion to allow for grasp and power grip. The metacarpophalangeal (MCP) joints are stabilized by the volar plate and the collateral ligaments: the proper collateral ligaments are thicker and run between the head of the metacarpal and the base of the middle phalanx, while the accessory collateral ligaments are thinner and have a more vertical direction, running from the metacarpal head to the volar plate. The cam shape of the metacarpal head contributes to the tightening of the collateral ligaments when the joint is flexed, stabilizing the joint and decreasing abduction and adduction. The thick intermetacarpal ligaments stabilize the second through fifth metacarpals distally, often providing stability with fractures of the metacarpal shaft.


The proximal phalanx acts as an intercalated segment, with tendons running on all sides, but nothing inserting on this bone. The collateral ligaments of the proximal interphalangeal (PIP) joint contain a proper and accessory component, with insertions into the base of the middle phalanx and the volar plate, respectively. They function to provide lateral stability. The head is bicondylar in shape (as opposed to the cam shape of the metacarpal head) and the collateral ligaments of the PIP joint are tightest with the joint in extension. The middle phalanx has insertions of the extensor mechanism (central slip) and flexor (flexor digitorum superficialis – FDS). The distal interphalangeal (DIP) joint is similar anatomically similar to the PIP joint and the distal phalanx contains the insertion of the terminal portion of the extensor mechanism and the flexor digitorum profundus (FDP).


The volar plates of the MCP joints differ from the IP joints in that the MCP joints have more of an accordion like structure, allowing for the volar plate to be compressed with flexion and expanded with extension. The volar plates of the IP joints have stout proximal extensions known as checkrein ligaments. When contracted, these can contribute to PIP flexion contractures.


The thumb has a greater degree of motion at the CMC joint, allowing for opposition to the fingers. The shape of the metacarpal head (greater diameter on ulnar aspect), allows for pronation of the thumb to assist with opposition.



Classification of fractures and dislocations


Fractures of the phalanges and metacarpals may occur through the joints (articular) or along the shaft (extra-articular). Articular fractures are more common in the PIP and DIP joints than the MCP joints. They may occur through the head or the base. Fractures through the head of the phalanges are classified as unicondylar or bicondylar and can occur in the sagittal or coronal plane. Fractures through the shaft can occur as transverse, oblique, or spiral planes. In addition, fractures can be classified as comminuted when there are multiple fragments.


The angular deformity of the fracture is dependent upon the forces acting on the distal bones. Metacarpal fractures most commonly have an apex dorsal configuration secondary to the pull of the interosseous muscles, while fractures of the proximal phalanx tend to have apex volar configuration due to the interosseous muscles. Fractures of the middle phalanx have a variable deformity, depending of the location of the fracture. Those proximal to the insertion of the FDS have dorsal angulation due to flexion of the distal portion of the bone from the FDS, while fractures distal to the FDS insertion have apex volar angulation due to flexion of the proximal fragment (Fig. 7.1).



For a dislocation to occur, the stabilizing structures (collateral ligaments, volar plate, dorsal capsule) must be disrupted. Dislocations are described by the location of the distal bone and are classified as dorsal, volar, radial, or ulnar.


Fracture dislocations commonly occur at the PIP joints of the fingers, and the base of the thumb and ring/small metacarpals. PIP joint and ulnar sided CMC joint fracture dislocations are most commonly dorsal. Thumb CMC joint fracture dislocations are referred as Bennett or Rolando, depending on the configuration and size of the fractured segments.




Pediatric fractures


Pediatric fractures, or fractures in patients with open growth plates require special attention. The physes are located in the metacarpal neck regions in the index, long, ring, and small fingers and at the metacarpal base in the thumb. The physes of the phalanges are located at the base. Growth plate fractures are described by the Salter–Harris classification (Fig. 7.2) and (Table 7.1), with type II being the most common.



Table 7.1 Classification of Salter–Harris fractures


















Type 1 Fracture is confined to the physis, often with normal radiographs
Type 2 Fracture starts in the physis and extends through the shaft (away from the joint)
Type 3 Fracture starts in the physis and extends into the joint
Type 4 Fracture starts in the shaft and extends through the physis and into the joint
Type 5 The physis is crushed, and there may be sheering through the physis

General principles include early reduction and stabilization. An initial reduction attempt should be completed for displaced fractures, but remanipulating a fracture involving the growth plate should be minimized as this can lead to physeal arrest and premature closure of the growth plate. Generally, the use of plates and screws is avoided and hardware is removed when the fracture is healed. Stabilization of fractures occurs with smooth K-wires and if necessary to cross the physis, effort should be made to minimize the number of passes and thus further injury to the growth plate.




Diagnosis


The diagnosis of hand injuries begins with a history, including hand dominance and occupation as well as the mechanism of injury. The appearance of the hand should be evaluated with the fingers extended as well as flexed. The alignment of the digits may appear normal with the fingers in extension, only to notice a rotational deformity when the digits are flexed (Fig. 7.3).



Specific areas of edema, ecchymosis or tenderness are noted as well as any wounds that may be present. While general screening radiographs of the hand may be beneficial for initial evaluation, specific X-rays provide better detail and should be used once the diagnosis is made (radiographs of the injured finger are preferred over radiographs of the hand for phalangeal fractures). Three views of the injured part are required to adequately evaluate a fracture in the hand.


Occasionally, additional studies will be necessary for diagnosis or to further define the injury. For example, a collateral ligament injury at the metacarpophalangeal (MCP) of the thumb may not be apparent with plain radiographs, but will become apparent with stress views when the joint space is increased. Magnetic resonance imaging (MRI) can also be used to evaluate collateral ligament injuries and determine if a Stener lesion is present, guiding treatment. Computerized tomography (CT) scans can be used to determine bony alignment/fracture configuration and may be helpful in some joint injuries.



Treatment: fingers


Once the diagnosis of a fracture has been made, a decision must be made regarding the best treatment. Options include protection with early motion, immobilization alone or following reduction by closed or open techniques. The goal should be to reduce the fracture, maintain the reduction and return the patient to function with early motion, while minimizing stiffness.



Phalangeal fractures and dislocations


Fractures of the distal phalanx are one of the most common fractures encountered.3 They can involve the tuft, shaft, or base, often extending into the articular surface of the DIP joint. Tuft fractures are often associated with nail bed injuries and repair of the nail bed often reduces and stabilizes the fracture. Shaft fractures are often stable and patients may function well after healing with a fibrous union. For those cases where the fibrous union is symptomatic, correction of the nonunion/fibrous union can be performed.



DIP joint


Bony mallet fractures involve the dorsal aspect of the base of the distal phalanx. The dorsal aspect contains the terminal extensor tendon and the goal of treatment should be to allow healing of a congruent joint without an extension lag. Most of these can be treated with a splint, maintaining the alignment of the joint.4,5 These fractures tend to have palpable and sometimes visible prominence along the dorsal aspect of the finger following healing, even when the radiographic alignment is anatomical, but this typically does not adversely affect their function. Fractures with volar subluxation of the distal phalanx should be reduced and often require pinning of the joint to maintain the reduction.6 Several techniques have been described, but all involve reduction of the joint surface.79 Attempted screw placement into the fragment is difficult, even when the fragment appears large on radiograph, and often results in fragmentation of the dorsal bone. Surgical treatment of stable fractures without subluxation is generally reserved for patients who cannot wear the splint continuously during the healing process, as complications such as pin breakage, pin tract infections and subsequent osteomyelitis can occur and the risks must be carefully considered.


DIP joint dislocations are typically in a dorsal direction (distal phalanx is dorsal to the middle phalanx) (Fig. 7.4). Acute dislocations can often be managed by closed reduction. Flexing the wrist and MCP joints to take the tension off the flexor tendons, and applying distal pressure to the base of the distal phalanx will often reduce the joint. If this is unsuccessful, it is often due to tissue interposed in the joint – most commonly the volar plate – and an open reduction is necessary.10 This can be completed through a volar zig-zag incision or midlateral incisions. The joint is exposed and any intervening tissue is removed, taking care to avoid damaging the articular cartilage, and the joint is reduced. Late presentation of DIP joint dislocations will usually require open reduction, using the same technique. Following reduction, these injuries are typically stable and early motion can be started using a dorsal blocking splint.



Fractures involving the proximal aspect of the DIP joint can occur as isolated middle phalanx articular fractures, involving one or both condyles and may extend proximally into the shaft (diaphysis). Stable fractures can be managed with protective splinting and followed closely with radiographs. If alignment is maintained, buddy taping and range of motion (ROM) exercises can begin around 3 weeks and continued for an additional 3 weeks or until radiographic healing is present. Unstable or displaced fractures should be reduced and stabilized either with K-wires or screws.



Middle phalanx shaft fractures


Treatment of middle phalanx shaft fractures depends on stability and fracture pattern (transverse versus oblique/spiral). Stable, nondisplaced fractures can be managed with a short period of immobilization (typically 2–3 weeks) followed by protected motion with buddy taping. They should be followed closely, checking for displacement and clinical signs of malrotation. This should be checked with the fingers in flexion. Any evidence of malrotation is an indication for reduction and stabilization.


Oblique fractures tend to be unstable, even following reduction, and often result in shortening, which is poorly tolerated by the extensor mechanism. Spiral fractures shorten and rotate. Therefore, these fractures are usually best treated with stabilization. Stiffness is common following these injuries, making postoperative rehabilitation important to optimize the outcome. Plate and screw fixation can provide good stability and allow early motion, but hardware tends to irritate extensor tendons, often resulting on adhesions, and necessitation removal. Lag screws are better tolerated than plates, but still require soft tissue dissection, which can result in adhesions and limit postoperative motion. K-wire fixation can often be accomplished with minimal soft tissue stripping and can easily be removed following healing, but the fixation is not rigid, so the rehabilitation program cannot be as aggressive. These fractures take a longer to heal due to the higher ratio of cortical to cancellous bone (in comparison to the proximal phalanx and metacarpal), but are usually stable enough to remove the K-wires between 4 and 6 weeks. Radiographic healing may take up to 4 months. A removable splint for protection and protected motion with buddy strapping is instituted to maximize motion.



PIP joint injuries


Injuries around the PIP joint are challenging to treat and good outcomes can be difficult to obtain. Stiffness is common and causes difficulty with gripping and grasping activities, as well as fine dexterity. The small size of the articular fracture fragments can make it difficult to maintain reduction. The goal in treating injuries of the PIP joint is to create a congruent joint and begin a rehabilitation program aimed at restoring motion.


The PIP joint functions as a hinge joint with approximately 100° of motion in the sagittal plane (flexion–extension) and minimal motion in the coronal or axial planes. The base of the middle phalanx is a biconcave surface with a central ridge. The volar lateral aspects of the bone are the sites of insertion of the proper collateral ligaments. The volar plate is a fibrocartilaginous structure, which provides additional stability to the joint. It has thicker fibers that insert laterally and thinner fibers, which insert centrally, to the base of the middle phalanx and proximal extensions, which attach to the periosteum on the proximal phalanx. The volar base of the middle phalanx and its curvature play an important role in stability, preventing dorsal subluxation of the middle phalanx.


The head of the proximal phalanx contains two condyles, separated by a groove or sulcus. There is a slight difference on the size of each condyle, allowing the fingers to converge in flexion. The index and middle have a slightly larger radial condyle while the small finger has a slightly larger ulnar condyle.


Injuries involving the PIP joint can involve the volar base of the middle phalanx, the head of the proximal phalanx, a pure dislocation, or any combination of these. Fractures involving the base of the middle phalanx include dorsal base fractures (involving the insertion of the central slip of the extensor mechanism), the volar base, resulting dorsal subluxation of the middle phalanx, avulsion of the collateral ligaments, or pilon type of fracture involving the dorsal and volar margins, with a depressed central articular fragment (Fig. 7.5). Fractures involving the proximal phalanx head can involve one or both condyles and can occur with or without proximal extension.



Pure dislocations result from hyperextension and an axial load. They are often dorsal dislocations and are managed similar to the DIP joint, with an initial trial of closed reduction (with the wrist and fingers flexed and distal pressure on the base of the middle phalanx). When successful, a dorsal blocking splint and early active flexion can produce good results. When reduction cannot be completed by closed means, open reduction is indicated, either through a volar or mid-lateral approach.11


Volar dislocations are less common, but can lead to late deformities if not recognized and treated.12 The central slip is often injured and can result in late boutonniere deformities. Following reduction, splinting the PIP joint in extension and active flexion of the DIP joint will allow gliding of the lateral bands. Active flexion can be started following three weeks, as further immobilization of the PIP joint may result in permanent stiffness. Irreducible dislocations are due to an interposed central slip or collateral ligament and require open reduction through a dorsal approach, allowing direct inspection of the central slip.



Middle phalanx base articular fractures


Fracture dislocations of the PIP joint result from an axial load in a dorsal direction or longitudinal direction when the finger is slightly flexed. These injuries are classified according to the amount of the articular surface involved. Fractures involving <30% of the articular surface of the base of the middle phalanx are typically stable and can be managed nonoperatively. Fractures involving 30–50% of the articular surface are tenuous and often are unstable. Fractures involving >50% are unstable and result in dorsal subluxation of the middle phalanx (Fig. 7.6).13



Lateral radiographs should be carefully evaluated for the “V sign”, indicative of dorsal subluxation (Fig. 7.7). The two condyles of the proximal phalanx should be superimposed and the base of the middle phalanx should be collinear with the head of the proximal phalanx. There should be a smooth curvature of the joint surface, with a consistent space between the proximal and middle phalanx. If there is convergence of the joint space creating a dorsal “V”, the patient may be able to flex the digit at the PIP joint, but this occurs through a hinge process rather than rotation, and the joint surface will degenerate.



Treatment is directed at recreating a congruent joint surface and restoring motion. Stable fractures and those which are classified as tenuous but maintain reduction and a congruent joint with <30° of flexion, can be managed nonoperatively with a dorsal extension block splint. Active flexion is initiated and extension is allowed short of the point of subluxation. These patients should be followed closely to ensure that subluxation of the joint does not develop. Unstable fractures, or those which a congruent joint cannot be established with <30° of flexion, require operative treatment.


A variety of techniques have been described, including extension block pinning,14,15 open reduction and internal fixation,16 volar plate arthroplasty,17,18 replacement arthroplasty,19,20 and external fixation.2123 All of these techniques have case reports or small series illustrating good outcomes, but there are no prospective studies indicating one technique is better than others for a particular injury.




External fixation


A variety of devices have been described for management of PIP joint fracture dislocations.2124 The common principle is to produce distraction across the joint, allowing alignment to be maintained through ligamentotaxis. In addition, some devices provide a volar directed force on the middle phalanx to assist in maintaining alignment. They all allow immediate PIP joint motion. Careful attention should be paid to the fragments along the volar base of the middle phalanx as dorsal subluxation can recur if these do not heal in proper position (the volar lip of the base of the middle phalanx is a restraint to dorsal subluxation, so healing of the fracture fragments must recreate the normal curvature).


External fixation systems can be fabricated from K-wires with or without the use of rubber bands or commercially available devices can be used. Figure 7.10 illustrates and example of a PIP joint fracture dislocation in the small finger managed with an external fixator fabricated from K-wires.



Technique of external fixation


A 0.045-inch K-wire is inserted through the head of the proximal phalanx, perpendicular to the joint surface (Fig. 7.8). A second 0.045-inch K-wire is inserted through the distal shaft of the middle phalanx, parallel to the DIP joint surface. The proximal wire is bent distally along the radial and ulnar aspects, paralleling the digit. Distal to the second wire, a dorsal proximal bend is created, followed by a dorsal distal bend. The bends should be at the same level on both the radial and ulnar sides. This creates a groove in the proximal wire for the distal wire to be positioned, allowing slight distraction across the joint, which will aid the reduction via ligamentotaxis. Increasing or decreasing the first bend on the proximal wire can adjust the distraction across the joint. This can be performed under local anesthesia and immediate motion is initiated. The fixator is left in place for approximately six weeks and rehabilitation focuses on motion of the PIP and DIP joints. The joint surface will remodel over time.




Internal fixation


Internal fixation of middle phalanx base fractures can be demanding, but good results can be obtained. Postoperative rehabilitation is critical to a good outcome, so the patient must be compliant or the result can be a good radiograph with a stiff nonfunctional finger. Larger fragments can often be stabilized with small screws, reconstructing the volar base of the middle phalanx (Fig. 7.9). Dorsal fragments can be stabilized with screws or K-wires to reinsert the central slip. Comminution at the base of the middle phalanx creates a greater challenge and the surgeon should be prepared for this as often what appears as a large piece on X-ray is found to be multiple smaller pieces. If the articular surface can be reduced, a cerclage wire may be used to hold the bone fragments in place (Fig. 7.10).25 This may provide adequate stability to allow early motion.





If the remaining fragments are too small to stabilize, they can be excised and the joint surface is reconstructed. The two most common methods to accomplish this are by advancing the volar plate (volar plate arthroplasty) or replacement of the volar base of the middle phalanx. This can be accomplished by using a portion of the hamate (hemi-hamate replacement arthroplasty, HHRA).


The volar plate arthroplasty was described by Eaton and Malerich in 198018 and involves removing the comminuted portion of bone along the volar aspect of the base of the middle phalanx, creating a trough parallel to the dorsal surface of the middle phalanx, and advancing the volar plate to resurface the joint. The volar plate is attached to the bone, either through drill holes or with a permanent suture at the lateral aspect. The joint is temporarily pinned in slight flexion. At 3 weeks, the pin is removed and motion is begun.17 The volar plate serves to prevent dorsal subluxation of the middle phalanx. The results with this technique can be unpredictable as stiffness and recurrent dorsal subluxation can occur. Long-term follow-up of Dr Eaton’s patients have been published with good results,26 but there are few recent reports of this procedure.


More recently, the hemi-hamate replacement arthroplasty has been described (Hastings et al. ASSH annual meeting, 1999) and subsequently published. The dorsal distal portion of the hamate has similar anatomy to the volar base of the middle phalanx. Osseous cuts must be precise and the curvature of the volar base of the middle phalanx must be reproduced or persistent dorsal subluxation will occur. This can be rigidly fixed and early motion can be instituted. Published series have shown promising results.20,27



Technique of HHRA


The procedure can be performed under regional or general anesthesia. The finger is approached from the volar aspect with a Bruner incision from the palmodigital crease to the DIP flexion crease (Fig. 7.11). Skin flaps are elevated and retracted. The digital neurovascular bundles are freed so they are not under tension when the joint is exposed. A radial or ulnar based flap of the flexor sheath is created between the A-2 and A-4 pulleys. The collateral ligaments are released from the middle phalanx, leaving a small stump for later repair, and the volar plate is released from fragments at the base of the middle phalanx. The neurovascular bundles are inspected to make sure they will not tether as the joint is exposed. The flexor tendons are retracted and the joint is shot gunned open exposing the joint. If resistance is encountered, it is usually due to the collateral ligaments; these are inspected, ensuring complete release from the middle phalanx.



Once the joint is exposed, the loose fragments are removed and a smooth surface is created along the joint surface and along the volar margin of the middle phalanx. This will be the site of insertion of the hemi-hamate graft. Care must be taken to preserve as much of the dorsal cortex as possible as this becomes prone to fracture if insufficient bone remains. The defect for the graft should be large enough to allow fixation of the graft with at least two, and preferably three screws. The dimensions of the defect are measured so an appropriate size graft can be obtained.


Next, a dorsal transverse incision is outlined proximal to the base of the ring and small metacarpals to expose the distal aspect of the hamate. Fluoroscopy can be used to confirm the correct location of the incision. Care is taken to preserve the dorsal sensory branch of the ulnar nerve and a transverse capsulotomy is performed exposing the joint. The dimensions of the graft are outlined and the graft is harvested slightly larger than necessary, so it can be trimmed to the appropriate dimensions. The axial and sagittal cuts are made using a small saw. A portion of the dorsal hamate can be removed proximal to the axial cut to facilitate the coronal cut. This can be completed with a curved osteotome. The graft is removed and the donor site is closed. The graft is placed along the base of the middle phalanx and provisionally fixed with small K-wires. This step is crucial as proper positioning is necessary for a good outcome. The graft must be placed so the normal curvature of the middle phalanx base is recreated. If the graft is positioned too vertically, dorsal subluxation of the middle phalanx will occur. The joint is reduced and visualized with fluoroscopy. The joint should now appear congruent, with appropriate curvature of the middle phalanx base and without evidence of the dorsal “V.” The cartilage on the graft is typically thicker than the middle phalanx, so images may appear as if the graft is not in proper position. This can be ignored since direct visualization will ensure alignment of the joint surface. The joint is opened and the K-wires are replaced with small screws (1.0–1.5 mm), rigidly securing the graft to the middle phalanx. The joint is reduced and fluoroscopy is used to confirm appropriate length of the screws and position of the graft.

Feb 21, 2016 | Posted by in General Surgery | Comments Off on Hand fractures and joint injuries
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