Although finger joint dislocations are generally thought of as benign by many athletes and assumed to be a sprain, these injuries represent a spectrum that includes disabling fracture-dislocations. Failure to recognize certain dislocations or fracture-dislocations may result in permanent deformity and loss of motion. Simple dislocations are frequently amenable to early return to play with protection; however, more complex injuries may require specialized splinting or surgery. Delay in diagnosis of unstable proximal interphalangeal fracture-dislocations may require reconstruction or fusion. Early diagnosis and appropriate treatment are essential to ensure optimal functional results.
Finger joint dislocations encompass a range of injury severities from benign to permanently disabling if improperly treated; therefore, appropriate diagnosis in athletes is key to ensure maximal function is retained.
Simple dislocations should be reduced with the appropriate maneuver and most athletes can return to play with protective buddy taping in days.
Volar proximal interphalangeal (PIP) joint dislocations are important to diagnose and treat with immediate extension splinting to prevent subsequent boutonnière deformity secondary to central slip injury.
PIP joint fracture-dislocations all require treatment by a hand surgeon to determine whether extension block splinting or open reduction with internal fixation is indicated.
Untreated PIP joint fracture-dislocations require reconstruction of the joint and may include hemihamate grafting to replace the articular surface and restore joint congruity and stability.
Finger injuries are a known risk in athletes, especially in ball-related sports and high-impact sports such as gymnastics. Specifically, a 2008 review of professional football injuries found that 24% of hand injuries were to the fingers, and 49% of those were joint subluxations or dislocations. Both amateur and professional competitors are at risk for these injuries, especially in early season when conditioning may not be optimal. Often, finger injuries are perceived as minor and athletes encouraged to play through the injury, which is where the role of coaches and team physicians is especially critical in early recognition of more complicated dislocations and fracture-dislocations, to ensure that proper treatment is initiated early. Timely treatment of complex fracture-dislocations ensures optimal outcome, both in range of motion and overall hand function. This article reviews these injuries with a focus on fracture-dislocations; other fractures and finger injuries are covered elsewhere in this issue.
Interphalangeal joint anatomy
A brief review of interphalangeal (IP) joint anatomy is needed to set the stage for examining the mechanism and treatment of finger joint injuries. The proximal IP (PIP) and distal IP (DIP) joints are both bicondylar hinge joints with motion in 1 plane. The middle phalanx (P2) base has a midline ridge that articulates with the trough between the proximal phalanx (P1) condyles to limit rotation. because IP joints are constrained to flexion and extension, they are more susceptible to injury than joints with greater degrees of freedom.
The DIP joint has an arc of motion from 0° to 80°, whereas the PIP joint has a slightly greater range, from 0° to 110°. The PIP joint plays the largest role in functional grasp, contributing 85% of the motion required. In addition to the constraint of bony interface, stabilization is provided by stout ligamentous structures. Radial and ulnar stability is provided by the proper collateral ligaments and dorsal capsule in flexion, and the volar plate and accessory collateral ligaments in extension. The volar plate provides resistance to any hyperextension force and subsequent dislocation. Dorsally, the joint is less protected, because the central slip is the primary support of the PIP joint and is significantly less robust than the volar plate. The DIP joint dorsally is supported by the terminal tendon ( Fig. 1 ).
This anatomy leads to specific vulnerabilities in the IP joints; during end-on loading in hyperextension, the weaker dorsal support leads most commonly to dorsal dislocation. The longer lengths of P1 and P2 compared with P3 creates a longer lever arm, which likely explains the increased incidence of PIP joint dislocations compared with the DIP joint. , In fracture-dislocations, the insertion of the proper collateral ligaments onto the volar lip of P2 dictates the relative stability of the joint: fractures volar to the insertion leave the collateral ligaments intact and are more likely to be stable because the ligaments remain on the base, as opposed to fractures that are more dorsal (involving a greater percentage of the joint surface), which disassociate the ligaments from the phalanx (discussed in more detail later).
With all finger injuries, early motion is key to final function. Both PIP and DIP joint injuries develop rapid stiffness when immobilized, which may lead to irreversible contracture of the previously discussed ligamentous supports of the joint. Although hand surgeons often delay motion or select treatment courses because of concerns of patient noncompliance, athletes are typically motivated to achieve the best possible result and are dedicated to their therapy. Thus, in athletes, the authors advocate selection of the treatment option that allows earliest return to motion given their overall adherence to a structured, supervised hand therapy program.
The common clinical complaint for dislocations and fracture-dislocations may be nonspecific: the athlete reports jamming the finger. Many athletes instinctually pull on a dislocated finger after injury and reduce the joint in the field, presenting for follow-up days later with edema and stiffness. Unless evaluated shortly after injury, swelling may preclude easy visualization of an ongoing dislocation.
History should proceed per routine evaluation of the patient with a hand injury. Additional evaluation of the athlete should include sport, position, training/competition schedule, and previous injuries to the finger. The physician must also elicit the patient’s expectations in timing of return to play and final range of motion. The injured finger should be assessed and compared with the contralateral normal side. A digital block may be used to facilitate full examination.
Key examination points include:
Gross deformity of the finger
Resting posture (flexion vs extension)
Stability of PIP and DIP joints to radial and ulnar stress
Range of motion at both IP joints
Significant bruising under the nail may indicate a concurrent soft tissue mallet. Posture of the finger gives clues to the type of dislocation: a PIP joint fixed in extension is typically seen with a dorsal dislocation, whereas a flexed PIP joint with limited motion indicates a fracture-dislocation. In reduced dislocations, radial and ulnar stress enables assessment of the integrity of the ligaments. This portion of the examination should be performed with the PIP extended to assess the accessory collateral ligaments and volar plate as well as in 30° of flexion to assess the proper collateral ligaments and dorsal capsule. Gentle pressure applied dorsally on the PIP while supporting the DIP volarly can elicit hyperextensibility, indicating volar plate injury from a recent dislocation. Range of motion should be smooth; any catch or clunk alerts the examiner to the diagnosis of a fracture-dislocation. Joint subluxation may only be seen as a slight limitation in range of motion or subtle scissoring. If fluoroscopy is available, it is a useful adjunct to evaluate whether the joint is stable throughout the full range of motion.
Differential diagnoses of these injuries can include:
Collateral ligament sprain
Volar plate avulsion
Central slip disruption
Before any reduction, imaging should be obtained to guide the appropriate maneuver. Especially in delayed presentation of an injury, imaging may help confirm reduction because swelling may obscure any ongoing deformity. Dedicated views of the finger are essential, and hand films do not suffice. The lateral view must show alignment of the condyles to support joint assessment. Reduction is confirmed with presence of a true concentric joint. The dorsal V sign ( Fig. 2 ) indicates ongoing subluxation of the phalangeal base. Fractures should be assessed for the percentage of articular surface involved. Advanced imaging such as a computed tomography scan may be used to delineate complex injuries such as middle phalanx base fracture-dislocations.
In the fingers, any immobilization beyond 3 weeks is undesirable because stiffness will occur. Dislocations without any associated fractures should be mobilized early unless grossly unstable: in a retrospective study of PIP joint dislocations comparing splinting for 4 weeks with early motion, 92% of the early motion group regained full range compared with 36% of immobilized patients. Motion should be initiated 2 to 3 days after injury (allowing 24–48 hours of soft tissue rest) with buddy taping to an adjacent finger. Buddy taping should avoid including the border digits (index and small fingers) unless they are the injured digits. Athletic tape may be used, or specialized Velcro loops may be fabricated by a therapist or purchased online ( Fig. 3 ). Additional sport-specific orthoses may be available.
Edema control in the immediate postinjury period can significantly improve range of motion. Coban (3M Science, Maplewood, MN) wrapping is an effective treatment and may be adjusted by the patient serially. Although custom sleeves and gloves are available and may be used in select cases, most patients benefit from the simplicity of digit wrapping. A dislocation may develop a mild flexion contracture; however, these are rarely functionally significant, with the exception of specific pitching grips.
|Dislocation||Reduction Maneuver||Additional Tips||After Reduction|
|Dorsal DIP||Volarly applied pressure on P3 base + axial traction||If irreducible, consider entrapped volar plate||Recommend splinting 2–3 wk in extension|
|Volar DIP||DIP flexion + axial traction||Least likely to need reduction||Needs assessment for bony mallet (fracture-dislocation)|
|Dorsal PIP||PIP extension + axial traction||Use thumb to hook base of P2 longitudinally||Needs assessment for PIP fracture-dislocation|
|Volar PIP||PIP flexion + axial traction||Flex metacarpophalangeal and wrist, may require slight rotation||Presume central slip injury and splint PIP in extension|
|Lateral PIP||Radial or ulnar force in direction of dislocation + axial traction||Easiest dislocation to reduce||Assess collateral ligament stability after reduction|
Dorsal Distal Interphalangeal Joint
Dorsal dislocations of the DIP joint are the most common and result from a hyperextension impact on the finger. They are seen more frequently in sports with forceful ball handling, such as basketball and volleyball. On presentation, the finger is extended with an inability to flex. Reduction of these dislocations is performed by longitudinal traction and direct pressure on the dorsal P3 base. The collateral ligaments are likely to be torn and splinting in slight flexion for 2 to 3 weeks promotes stable healing. A dorsal or a volar splint may be applied with the PIP left free (see Fig. 3 ). These dislocations are more likely to be open than PIP or volar DIP given the paucity of tissue between the joint and skin, and thus may require operative debridement.
If irreducible, a dorsal DIP joint dislocation may have an entrapped volar plate within the joint space. This finding may be subtle on lateral radiographs, with several millimeters of joint space widening, and should thus be evaluated carefully, especially in patients with persistent limitation in motion despite lack of deformity ( Fig. 5 ). An operative approach is required to reduce this injury; the authors use a dorsal approach and use of an elevator to open the joint space and release the entrapped volar plate. Once reduced, these dislocations should also be splinted for 2 to 3 weeks in extension before initiating range of motion. Return to play with a splint is acceptable if the sport allows.
Volar Distal Interphalangeal Joint
Volar dislocations are significantly less common and are most commonly seen in softball. Because the terminal tendon crosses the joint at the DIP immediately before insertion, it is presumed to be involved with either a stretch mechanism or avulsion, with or without a small bony fragment. Extension splinting for 6 weeks is required to prevent chronic mallet deformity, and any flexion of the DIP during this period necessitates restarting the period of immobilization. , Splinting should be in slight hyperextension with the PIP free.
Although splinting is adequate in treatment of mallet fingers during daily activities, it is unlikely to be robust enough for sports. If absolutely necessary for an athlete to return to play, a splint may be transitioned to a finger-based cast during games for additional protection and swapped for a splint during all other times to allow motion of the PIP joint. Five-year outcomes of soft tissue mallets treated with splinting alone showed an average 8° extension lag and 55° of active motion, with 25% showing arthritis. Longer duration of full-time splint wear is also associated with decreased extension lag; however, additional nocturnal splinting has not been found beneficial. For noncompliant patients, oblique pinning across the DIP into extension is an alternative; however, unprotected return to play with a Kirschner wire in place may lead to a bent or broken pin.
Dorsal Proximal Interphalangeal Joint
Dorsal dislocations represent a spectrum of injury. Type I is a hyperextension injury with avulsion of the volar plate but intact accessory and proper collateral ligaments preventing full dislocation ( Fig. 6 ). Type II injuries involve a split in the accessory and proper collateral ligaments leading to a true dorsal dislocation. When hyperextension is accompanied by a significant axial loading force, a type III injury occurs as a dorsal dislocation with a volar fracture of P2. The joint remains stable in flexion in all but the worst type 3 injuries, because of the support of the proper collateral ligaments.