Finger joint dislocation is a common hand injury. Finger dislocation can occur at the proximal interphalangeal (PIP), distal interphalangeal (DIP), or metacarpophalangeal (MCP) joints. This paper discusses the epidemiology, anatomy, examination, imaging, treatment, and complications of finger dislocation.
Fingers have three joints: the metacarpophalangeal (MCP) joint, the proximal interphalangeal (PIP) joint, and the distal interphalangeal (DIP) joint. The MCP joint is between the metacarpals and proximal phalanges. The PIP joint is a hinge joint between proximal and middle phalanges. The DIP is also a hinge joint and is between the middle and distal phalanges. The range of motion of these joints allows for flexion and extension, which provides grasping, pinching, and clawing or reaching functions of the fingers. The middle phalanx range of motion at the PIP joint is 105 +/- 5-degrees and accounts for the majority of the flexion of the fingertip during grasping. Flexion and extension of the digit are also possible at the metacarpophalangeal joint; however, the MCP joint can also perform adduction, abduction, and circumduction.
The phalangeal joints have important stabilizers that provide necessary support during motion. Joint stabilizers are both static and dynamic. Static stabilizers consist of non-contractile tissue, including the collateral ligaments, volar plate, dorsal capsule, sagittal bands, and ulnar and radial collateral ligaments. The volar plate is an essential stabilizer as it reinforces the volar side of the joint capsule and maintains stability by preventing hyperextension of the finger joints. The collateral ligaments provide the stabilization against radial and ulnar deviation of the interphalangeal joints. Sagittal bands encircle the MCP joint to keep the extensor tendon centralized and to prevent bowstringing. Dynamic stabilizers include extrinsic and intrinsic tendons and muscles, and two important dynamic stabilizers are the central slip and lateral bands. The central slip tendon is found dorsally and provides for PIP joint extension, and the lateral bands provide DIP joint extension. Finally, digital arteries and nerves are found volarly and appear on both ulnar and radial sides of the digit.
Finger dislocations can involve the MCP, PIP or DIP joints and may occur in the dorsal, volar, or lateral planes. Dislocations categorize, according to the position of the distal bone relative to the more proximal bone.
Hyperextension or high-energy axial loads at the MCP joint can result in dislocation. MCP joint dislocation infrequently occurs because of the protection against hyperextension by the volar plate and radial and ulnar deviation by the collateral ligaments. The most common MCP joint dislocation is the index finger. MCP joint dislocation of the middle finger occurs more frequently when it is subjected to ulnar stress while in hyperextension. Most common MCP joints dislocate dorsally. The typical presentation of MCP joint dislocation is with the IP joint in flexion and the MCP joint in extension. A nonreducible dislocation with dimpling on the volar surface indicates volar plate interposition.
PIP joint dislocations are the most common dislocation due to sports and are also known as “coach’s finger.” The typical presentation of PIP joint dislocation is deformity, decreased range of motion, and pain. PIP joint dislocations can classify into dorsal, volar, and lateral dislocations. PIP joint dislocation is most commonly dorsal; however, volar dislocation correlates with a higher rate of complications and more difficult reductions. Dorsal dislocation results result from longitudinal compression and hyperextension commonly by a ball hitting the fingertip.
Dorsal PIP joint dislocation most commonly occurs at the middle finger and is associated with volar plate, collateral ligament, and dorsal joint capsule injury. Swan neck deformity most often occurs in dorsal dislocations and results from volar plate injury. Trapping of the volar plate inside the joint may occur, causing malalignment and oblique rotation resulting under challenging reductions. Volar dislocation of the PIP joint can occur with and without rotation of the intermediate phalanx. Volar dislocation is infrequent and can be associated with injury to the central slip of the extensor tendon. Untreated rupture of the central slip after PIP joint dislocation is associated with pseudo-boutonniere (PIP flexion contracture). Pseudo-boutonniere is a chronic PIP joint flexion with the absence of DIP extension.
Lateral PIP dislocation can also occur and involves disruption of the collateral ligaments. The patient presents with joint instability and the widening of the joint on radiographs. Finally, rotary volar dislocations may occur when the phalanx displaces and rotates around one collateral ligament, allowing the proximal phalanx to wedge itself between the lateral band and extensor tendon. The classic lateral radiographic finding has the description of “Chinese finger-trap.”
DIP joint dislocations typically present with deformity at the fingertip. Dorsal, lateral, and volar DIP joint dislocations are all possible. Dorsal DIP joint dislocations occur most frequently and are associated with fractures and skin injuries. They are not always associated with flexor tendon avulsions but may have an interposed volar plate causing a non-reducible dislocation. Volar DIP joint dislocations are similar to dorsal PIP joint dislocations in that both are associated with extensor tendon injuries. The lateral DIP joint is more likely to have post-reduction instability than volar or dorsal dislocations. Isolated DIP joint dislocation without related injuries such as soft tissue or fractures is rare and is commonly managed with closed reduction and splinting in the emergency departments.
From 2004 to 2008, approximately 166000 finger dislocations received treatment in US Emergency Departments. Most dislocations occur between fifteen and nineteen years of age and affect African Americans more than other racial groups. They occur most commonly in basketball and football players.
Examiners must perform a complete history, which includes risk factors such as Ehlers-Danlos syndrome, mechanism of injury, handedness, previous finger injuries, occupation, and hobbies. Ample lighting should be used to examine the hand for skin integrity, ecchymosis, swelling, or bony deformity. If skin integrity becomes compromised due to laceration or abrasion, the goal of the examiner is to evaluate in a bloodless field if possible. Examiners may use finger tourniquets or, in a patient with adequate circulation, an anesthetic with epinephrine can be used. Finger examination must be through its complete active and passive range of motion.
A thorough neurovascular exam is imperative in the evaluation of the injured hand. The injured digit should be compared to the same digit on the unaffected hand for light-touch, pinprick, and 2-point discrimination to identify any potential digital nerve injury. The digital artery can be evaluated by comparison to an unaffected digit on the opposite hand with the use of a capillary refill. If the examiner identifies a deformity, the examiner must also determine if there is any rotation or angulation. Hyperextension of the finger joint should be performed to asses the competency of the volar plate. Lateral stress of finger joint is performed to test the collateral ligaments. To evaluate the integrity of the central slip, the Elson test is preform. To assess for rotation or angulation, the patient is asked to make a fist if possible, and all the fingertips should point toward the scaphoid. Overlapping or “scissoring” indicates a rotational component to the injury. Rotated or angulated fractures are also identifiable by comparison of the digital pulp and nails with the unaffected hand. Palpation can be used to determine the location of maximal tenderness.
The standard of care for evaluating injuries to the hand is plain film imaging. For each affected digit, true lateral, anterior-posterior, and oblique views are necessary. The films must demonstrate a clear view of the affected digit. Unaffected fingers must not obscure the view of the affected digit. Examiners should keep in mind that rotational deformities are most commonly diagnosed on the physical exam rather than on plain films. In addition to plain films, ultrasound (US) continues to be an area of research regarding the identification of fractures and tendon ruptures.
Treatment of MCP, PIP, and DIP joint dislocation may be operative or nonoperative depending on the ease of reduction, post-reduction stability, or involvement of the volar plate or other stabilizing structures. Before any reduction, a digital nerve block using lidocaine, bupivacaine, or tetracaine injected at the dorsal base of the dislocated finger will provide immediate anesthesia.
Non-operative management of MCP joint dislocations consists of closed reduction and splinting. The clinician can achieve closed reduction by extension and axial compression on the proximal phalanx with relocating pressure over the phalangeal base to glide it into position. This approach is different than the traction technique used in PIP joint dislocation. Multiple reduction attempts should be avoided as the inability to reduce may indicate volar plate interposition requiring open reduction. Multiple attempts at MCP joint dislocation reduction have the potential complication of displacing the volar plate between articular surfaces, lumbricals, or flexor tendons. The finger should have splinting with the wrist extended 30 degrees and MCP joint in 30 to 60 degrees of slight flexion to prevent terminal extension for about 3 to 6 weeks, followed by an additional two weeks of buddy taping.
Operative intervention is indicated for nonreducible MCP joint dislocation as there is a high likelihood of volar plate involvement in these cases. Open reduction of MCP joint dislocation can be performed using either a dorsal or volar approach; however, the dorsal approach is preferable as it carries a lower risk of neurovascular injury. After surgery, the wrist is splinted in 30-degrees of extension with the MCP joint in slight flexion for two weeks to prevent terminal extension. The recommendation is that the PIP and DIP joints not be immobilized. Recovery to preinjury motion typically occurs between 4 to 6 weeks.
PIP joint dislocations are also manageable with operative and nonoperative options, but unlike MCP joint dislocations, practitioners must determine if the PIP joint dislocation is dorsal, volar, lateral, or rotary as the treatment may differ. For closed reduction of dorsal PIP joint dislocation, the practitioner should apply slight extension and longitudinal traction, and with the other hand, apply pressure to the dorsal aspect of the proximal phalanx to relocate the displaced digit. After reduction, the examiner should evaluate the joint for instability in all planes and obtain radiographs. The normal contour of the dorsal aspect of the PIP joint on lateral plain film is “C” shaped. If, after reduction, this contour takes on a “V” shape, it may indicate persistent dorsal subluxation, which can lead to severe stiffness. PIP joint dislocation is often stable after reduction and is treated by dorsal splinting in 30-degrees of flexion. Volar PIP dislocations are the least common, but the reduction of the volar PIP joint dislocation is generally successful. The reduction takes place by applying mild traction with the PIP and MCP joints held in slight flexion. After the reduction of the volar dislocation, apply extension splint for six weeks. Unlike volar PIP joint dislocation, lateral dislocations are more likely to require operative intervention. Closed reduction requires relaxation of the extensor tendon and lateral bands by wrist extension and MCP flexion, respectively. Then the middle phalanx is gently rotated back into position. If reduction of the lateral PIP joint dislocation provides a full range of motion without subluxation, then the joint is not grossly unstable. In these cases, splinting and reassessment in two or three weeks is recommended. All unstable dislocations require referral for orthopedic evaluation and possible open repair. Indications for operative intervention regarding PIP joint dislocation include joint instability, significant ligament, soft tissue or tendon injury, or dislocations that are not reducible.
Splinting remains the mainstay of emergency treatment post-reduction. A recent randomized control trial compared buddy taping versus aluminum orthosis treatment of Eaton grades I and II hyperextension type injuries and found no difference in strength, pain, or function at three weeks. However, buddy tape did show an earlier range of motion and decreased edema.
DIP joint dislocation management is less complex then PIP joint dislocation. The three types of DIP joint dislocation are dorsal, volar, and lateral. The most common type of DIP joint dislocation is dorsal. Dorsal DIP joint dislocation is reduced with longitudinal traction, relocating dorsal pressure on the distal phalanx with DIP joint in flexion. Often, the reduction occurs easily in the emergency room setting, followed by splinting of DIP in 10 to 20-degree flexion for two to three weeks. If there is persistent DIP joint instability, such as those found more commonly in lateral dislocation, then it is treated with four to six weeks of K-wire fixation after concentric reduction. Irreversible dislocation is typically due to volar plate interposition and requires surgical intervention.
Physical therapy, occupational therapy, and return to play or work training are often necessary. The orthopedic or hand surgeon should give education on how to care for the injury until recovery is complete.
Finger dislocation evaluation, management, and treatment are complex. Orthopedic and hand surgeon consultation and close follow up are critical to decreasing the likelihood of the many complications associated with this injury. Since finger dislocation most commonly occurs in athletes, the discussion for return to play is also complex and requires communication between the orthopedic specialist, hand surgeon, and player. An orthopedic nurse can assist in the care, answer patient questions, assist during any procedural interventions, serve as a bridge between therapists and the clinician, and monitor progress towards healing. Physical and/or occupational therapy may be in order, with the therapist providing and charting updates so the entire team is aware of the current patient status. Specialists and nurses collaborating as an interprofessional team can enhance outcomes in diagnosing and managing finger dislocations. [Level 5]
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