INJURY TO FINGERS
The hand has both mechanical and sensory functions. Therefore, injuries to the hand not only disrupt mechanical ability but also compromise the sensory function of the upper limb. Most hand injuries cause pain, swelling, and often discoloration. Because the flexor and extensor tendons and the bones lie close to the skin, each major anatomic structure can be examined easily and its functional status determined. Radiographs of the whole hand itself are not needed if only the wrist or finger is injured, but anteroposterior, lateral, and oblique views of the specific site of injury are essential for a complete evaluation.
Fracture Of Proximal And Middle Phalanges
Diagnosis of fractures of the phalanges requires anteroposterior, lateral, and oblique radiographs and careful clinical examination of the soft tissues specifically the flexor and extensor tendons to verify the extent of the injury. Because finger injuries are often caused by crushing forces, open fractures of the fingers are common.
Several muscle forces contribute to deformity in fractures of the proximal or middle phalanx. The insertion of the flexor digitorum superficialis (sublimis) tendon along the middle phalanx affects the angulation of a fracture, depending on the location of the break. If the fracture of the middle phalanx is distal to the insertion of the flexor digitorum superficialis tendon, the fractured bone angulates volarly. Fractures proximal to the insertion of the flexor digitorum superficialis tendon angulate dorsally. In fractures of the proximal phalanx, the insertions of the interosseous muscle at the base of the proximal phalanx tend to flex the proximal fragment and the flexor and extensor tendons angulate the fracture volarly.
For reduction of a fracture of the phalanx, correct rotational alignment is just as essential as alignment in the anteroposterior and lateral planes. In the normal hand, the tips of all the flexed fingers point toward the tuberosity of the scaphoid. Inadequate reduction and persistent rotational malalignment adversely affect the patient’s ability to grasp. Often, the rotational malalignment is not noticeable when the fingers are extended, but it is always obvious when the fingers are flexed. Although judging the reduction of any phalanx fracture in both flexion and extension may be difficult, this step is most important.
The high-energy forces that cause transverse and comminuted fractures of the phalanx often produce significant injury to the soft tissues of the finger as well. Successful treatment of phalanx fractures demands careful attention to the potential consequences of the soft tissue injuries. Even though the fracture may heal in adequate alignment, injuries to the flexor and extensor mechanisms can lead to significant long-term dysfunction.
Management Of Fracture
Correction of deformity, preservation of motion, and care of the soft tissues are all important in the treatment of hand injuries. Adherence to the basic principles of fracture care is essential for good functional results. These principles are (1) alignment of the distal fragment with the proximal fragment, (2) adequate immobilization to allow healing, and (3) preservation of motion and soft tissue function. The primary goal in treating any hand injury is to maintain function, particularly full active motion of all joints. Persistent stiff-ness in the interphalangeal and metacarpophalangeal joints and adduction contracture of the thumb produce a functional loss that can be debilitating.
Immobilization should maintain the hand in a “position of function”: 45 degrees of extension of wrist, 70 degrees of flexion of the metacarpophalangeal joint, 20 degrees flexion of the proximal interphalangeal joints, and maximal abduction of the thumb. If scarring occurs, this position will preserve as much soft tissue length and joint flexibility as possible. In any significant hand injury, only fingers requiring immobilization should be placed in a cast or splinted; the other fingers should remain free to move.
Some fractures of the phalanges are considered stable; these include most nondisplaced fractures, long spiral fractures, and minimally displaced intra-articular fractures that do not displace with gentle early motion. Stable fractures can be treated by taping the injured finger to the normal adjacent finger (buddy taping) and initiating early active motion. Frequent and careful follow-up during the healing phase ensures that early motion does not displace the fracture fragment.
Most displaced fractures of the proximal and middle phalanges can be treated with closed reduction and cast immobilization using an ulnar or radial gutter splint. The plaster must be applied with great care to avoid excessive pressure on the soft tissues, which can cause ulceration of the skin. The fracture is checked at weekly intervals for 4 to 6 weeks. In fractures of the phalanges, radiographic evidence of healing appears slowly, and radiographs do not show union for many weeks. However, most uncomplicated fractures are clinically stable in 4 to 6 weeks. If examination at that time detects minimal swelling, no tenderness, and no instability, the patient can begin gentle protected motion, but the fracture should be protected for an additional few weeks with intermittent splinting or buddy taping. Fractures that require open reduction and internal fixation or closed reduction and pin fixation include unstable fractures, fractures that cannot be adequately reduced and maintained with closed means, displaced intra-articular fractures, multiple fractures with soft tissue injuries, and fractures in patients who repeatedly remove their casts.
Oblique fractures are often unstable and tend to shorten the finger. Closed reduction under radiographic control followed by percutaneous pinning restores stability, maintains the reduction, and allows early motion. Transverse fractures of the proximal or middle phalanx are very unstable, often requiring internal fixation. Inserted through a dorsal or midaxial incision, crossed Kirschner wires stabilize the fracture with only minimal disruption of the soft tissues; the wires are removed under local anesthesia without significant soft tissue dissection. Small compression plates may be used.
When a fracture is stabilized with either closed reduction and pin fixation or open reduction and internal fixation, the finger is left undisturbed for 8 to 10 days for the initial phase of soft tissue healing; then active supervised motion is begun to preserve soft tissue function.
Massive crushing injuries with multiple fractures of the phalanges and significant destruction of soft tissue require open reduction and stabilization. Fortunately, the incidence of postoperative infection in open hand fractures is quite low.
Special Problems In Fracture Of Phalanges
Management of fractures of the phalanges is complicated by numerous problems. Because of the intricate relationship between the flexor and extensor tendons, the joints, and the architecture of the phalanges, neglect or inadequate treatment can lead to significant disability.
Treatment of Oblique Fractures
The pull of the flexor muscles tends to shorten oblique fractures of the proximal and middle phalanges. Resulting soft tissue adhesions contribute to stiffness of the proximal interphalangeal joint. In addition, a bone spike protrudes volarly, creating a mechanical block to full flexion of the proximal interphalangeal joint. Such problems can be managed in a number of ways. If the alignment of the proximal phalanx is adequate but joint motion is limited, the volar spike can be removed surgically and the tendon adhesions freed. These procedures increase flexion and extension of the proximal interphalangeal joint. Inadequate bone alignment necessitates osteotomy of the proximal phalanx and internal fixation with Kirschner wires.
Treatment of Stable Intra-articular Fractures
Most intra-articular fractures of the metacarpophalangeal joint that have large nondisplaced fragments can be treated with buddy taping. However, close follow-up is essential to ensure that the fragment does not subsequently displace.
Treatment of Fracture of Condyles
Intra-articular fractures of the interphalangeal joints that involve the condyles of the proximal or middle phalanx are usually unstable. To avoid missing the fractured condyle and to assess the degree of displacement, radiographic examination must include anteroposterior, lateral, and oblique views. However, even after adequate open reduction, stable internal fixation, and fracture healing, stiffness usually persists in the distal or proximal interphalangeal joint.
Treatment of Malunion and Nonunion
Even with proper treatment and adequate follow-up, fracture malunion may occur. In most cases, a malunion does not require any further care, but if it causes pain, limits hand function, or is cosmetically displeasing, surgical intervention should be considered. Osteotomy at the fracture site or at an adjacent area of metaphyseal bone is the usual procedure for realigning the phalanx. The osteotomy is stabilized with an internal fixation device.
Nonunion is rare in phalanx fractures and often remains asymptomatic. For symptomatic nonunion, treatment with open reduction and internal fixation combined with bone grafting usually results in healing.
Treatment of Tendon Adhesions
Because injuries to the phalanges damage soft tissue as well as bone, adhesions may develop between the flexor and extensor tendons and the fracture site. The primary clinical sign of this complication is a limitation of active flexion. The need for assistance to achieve full flexion usually indicates the presence of adhesions within the sheath of the flexor tendon. Vigorous physical therapy can help restore motion, but surgical tenolysis of the flexor sheath at the level of the healed fracture is occasionally required. Extensor tendon adhesions also limit active finger flexion and require the same treatment.