Hand Dislocation Clinical Presentation

As with any hand injury, the history of a patient with a suspected hand dislocation should begin with determining the patient’s age; handedness; sex; and type of participation in sports, hobbies, or occupation, because these affect both the presentation of the injury and the goals of treatment.

The patient most likely presents with a history of trauma leading to finger deformity. The clinician should inquire about whether other injuries took place to rule out the presence of any life-threatening injury. The time at which the event occurred should be determined, as should the conditions surrounding it (these are particularly important if there is a question about whether an associated wound is contaminated or clean).

Because the dislocation is often reduced by the patient or others involved at the scene, it is important to elicit the mechanism of injury (eg, hyperextension, axial loading, torsion, radial or ulnar stress, or a direct blow) and assess the resultant deformity.

Although in many cases, the patient is unable to clearly describe the mechanism of injury, description of the deformity as either volar or dorsal is still valuable because the associated injuries and the appropriate treatment of these 2 types of deformity differ significantly. The exact location of pain can be helpful in localizing the injury, but this is more precisely defined by tenderness on physical examination.

Most carpal trauma occurs as a result of fall-on-outstretched-hand (FOOSH) injury, such as might occur in any sport or accident. When the resultant vector is primarily one of ulnar deviation and intercarpal supination, ligamentous disruption and carpal dislocations tend to result. This mechanism can be observed in glove-side injuries in baseball fielders or hockey goalies.

Once the mechanism of injury has been translated into forces, loads, rotations, extensions, reductions, joint deformities, and related forces that caused the dislocation, the clinician can use this knowledge to manage the local or obvious deformity as well as any distal or occult injuries. For example, the metacarpophalangeal (MCP) joint may appear dislocated, but fractures are typically associated with MCP dislocations because rotational and compressive forces are involved. Hence, radiographs are required before any reduction attempt. ^[14]

The past medical and surgical history should focus on previous injuries to the hand, presence of fixation devices, and underlying conditions that may affect healing (eg, ligamentous laxity).

With significant injury to the digits, a comprehensive examination may be hindered by pain. A thorough visual inspection of the hand and fingers is the first required step. Inspect for deformity, skin color, skin temperature, skin integrity, and swelling. Distal digital sensation should be checked early and often.

Inspection for deformity

The following deformities may be observed:

• Hyperextension - This is typical of dorsal proximal interphalangeal (PIP) joint dislocations, indicating damage to the volar plate

• Angulation - This may be radial or ulnar, indicating damage to one or both of the collateral ligaments

• Rotation - This is common in rotatory subluxation, which is a subtype of volar dislocation rather than a separate class of injury; it is best noted by looking at the nails, which should all lie in the same plane (the nail of an injured digit will be rotated out of the plane occupied by the others)

• Displacement of the more distal phalanx - This is volar in volar dislocations and dorsal or dorsolateral in dorsal dislocations; it may be obscured by swelling or may be subtle in partially reduced dislocations with entrapped soft tissue

Assessment of skin

The skin of the fingers is tightly stretched over the underlying structures and adherent to them, especially on the volar aspect and toward the fingertip. This makes the interphalangeal joints more prone to open dislocations than many other joints in the body. Accordingly, it is important to check for any breaks in the skin.

Any skin defect in the area of a joint must be presumed to represent an open dislocation with direct communication to the joint and potential contamination by bacterial flora. This flora can be destructive to articular cartilage and, therefore, may necessitate intravenous (IV) antibiotics and consultation with a hand surgeon for irrigation and debridement. One should be suspicious of an open injury in a patient presenting with a laceration over a joint even without deformity, because the patient may have reduced the jammed finger before the examination.

Sensation examination

Sensation examination includes testing for the following:

• Ability to distinguish light touch from deep pressure

• Ability to distinguish sharp from dull

• Ability to detect 2 points separated by 5 mm

• Ability to detect temperature variation

Because the presence of pain can limit the examination, rapid pain relief should be considered. The patient can be made pain-free or the pain made tolerable before manipulation of the hand or digit. Benefits of examination with anesthesia include improved assessment of range of motion (ROM) and digit stability. Digital block with a local anesthetic is quick and efficacious intervention. However, the clinician must have a working protocol with the hand specialist. In some cases, the hand specialist may want to examine the digit before giving the anesthetic.

Reducing the patient’s pain is a priority, but this priority must not be allowed to outweigh the need to perform a very thorough and well-documented neurovascular examination. The emergency physician and the hand specialist must establish some guidelines for eliminating the patient’s pain without compromising the examination and documentation for the provider who will have to provide ultimate follow-up, rehabilitation, and occupational guidelines.

Findings associated with specific dislocations

Dislocations of the thumb MCP joint may be simple or complex. In simple dislocations, the phalanx sits perpendicular to the metacarpal, and the volar plate is not trapped. In complex dislocations, the phalanx is positioned parallel to the metacarpal, with the volar plate trapped in the joint. Gamekeeper’s (skier’s) thumb presents with pain and tenderness on the ulnar aspect of the thumb around the MCP joint. ^[15]  The extent of associated laxity depends on the amount of disruption and the ability of the examiner to stress the joint.

Dislocations of the finger MCP joints also may be simple or complex. Simple dislocations can be identified as the base of the phalanx sits on the dorsum of the head of the metacarpal at a right angle. A complex dislocation (see the images below) may reveal a dimple on the palmar surface, and the digit may appear shortened and deviated to the ulnar side.

Simple dorsal dislocations of the PIP joints of the fingers may include volar plate disruption. The middle phalanx is often perpendicular to the distal aspect of the proximal phalanx. With lateral dislocation, the digit often is deviated to the ulnar side. Open dislocations of the distal interphalangeal (DIP) joints of the fingers are common because of the strong support of the skin and periarticular structures.

Evaluation after reduction

After reduction, the point of maximum tenderness, active ROM, stability to gentle passive stress should be checked. If the injury is to the thumb, testing specific to the thumb may be warranted.

Point of maximum tenderness

The point of maximum tenderness may not be easy to determine but helps to define damaged structures. The following locations are associated with specific injuries:

• Lateral – Injury to collateral ligaments (radial, ulnar, or both)

• Volar – Injury to volar plate

• Dorsal (base of middle phalanx) – Injury to central slip

Active range of motion

Active ROM (AROM) may be difficult to test if the patient is experiencing significant pain. Digital block (after neurologic examination) may be necessary for an accurate determination of ROM (see the image below).

The examiner must test full active extension of the PIP joint against resistance. In a PIP joint injury, inability to perform this motion with preservation of passive ROM (PROM) is diagnostic of a rupture of the central slip of the extensor tendon. This injury must be splinted in extension to avoid development of a boutonniere deformity (see the images below).

The joint should stay reduced throughout the ROM examination. Instability or redislocation, usually in extension, necessitates extension block splinting at an angle that preserves the reduction.

If both AROM and PROM are reduced, this is consistent with entrapment of a soft-tissue structure (eg, volar plate, collateral ligament, flexor or extensor tendon) in the joint and persistent subluxation. This requires a further attempt at closed reduction. If this is unsuccessful, open reduction is urgently indicated.

Stability to gentle passive stress

Different forms of passive stress are employed to evaluate stability. Hyperextension tests the volar plate. Ulnar deviation tests the radial collateral ligament. Radial deviation tests the ulnar collateral ligament. If the joint opens up 20° or more with minimal resistance, this is consistent with a complete collateral ligament tear.

Forceful passive testing for stability must be avoided, because it can convert a partial tear to a complete one; furthermore, instability of any of these structures to passive stress is unlikely to change the management of an injury that is stable with AROM. The one potential exception to this general rule is complete rupture of the radial collateral ligament of the index finger PIP joint in a young, active patient. This injury is often surgically repaired, primarily because stability at this joint (required for a normal pinch grip) is more important than ROM.

Dorsal deformities can be observed in both MCP-joint and CMC-joint dislocations. Because of swelling, clinical identification of these dislocations is sometimes hard. Bony prominences at the joints of maximum tenderness may be the most common physical findings.

After reduction, the stability of the MCP joint should be checked by means of radial and ulnar deviation with the joint in flexion to determine the functional stability of the radial and ulnar collateral ligaments. The MCP joint should be put through an ROM examination to assess its stability.

After reduction of carpometacarpal (CMC) dislocations, evaluation of hand ROM in dorsal and palmar flexion should be carried out to determine the intrinsic stability of the CMC joint.

Assessment specific to thumb

Physical examination testing specific to the thumb is indicated in some cases. In addition to AROM, testing of the thumb includes flexion of the MCP joint with radial and ulnar stress testing in extension and flexion and contralateral side-to-side comparison. Increased laxity with pain to palpation suggests an ulnar collateral ligament injury, such as gamekeeper’s (skier’s) thumb (see the images below).

Entrapment of the ulnar collateral ligament in the aponeurosis (Stener lesion) prevents healing and may necessitate surgical intervention (see the images below).

Joint stiffness, flexion deformity, hyperextension and instability may develop from the dislocation or damaged periarticular structures or from immobilization during treatment. Boutonniere deformity may result from an undiagnosed or untreated central slip injury associated with volar PIP dislocation. Overly forceful attempts at reduction may result in phalangeal fractures. ^[16] Associated intra-articular fractures may predispose to degenerative joint disease (DJD).