CHAPTER 110
Finger Sprain
(PIP Joint)
Presentation
During a sports activity or a fall, the patient’s finger is jammed or hyperextended, resulting in a painful, swollen, possibly ecchymotic proximal interphalangeal (PIP) joint. There may have been an initial dislocation, which was reduced by the patient or a bystander (see Chapter 109).
What To Do:
Get a detailed history of the exact mechanism of injury.
Palpate to locate precise areas of tenderness. Pay particular attention to the collateral ligaments, the volar plate, and the dorsal insertion of the central slip of the extensor tendon at the base of the middle phalanx. Note any associated injuries above and below the PIP joint.
Obtain anteroposterior and lateral radiograph views of the finger. “Chip fractures” may represent tendon or ligament avulsions. Surgical repair and orthopedic consultation are required if there is an avulsion fracture of more than 33% of the articular surface.
If pain precludes active motion testing or passive stressing of the joint ligaments, consider using a 1% lidocaine digital block or, more effectively, direct joint injection. The patient may decide if this anesthesia is used or not. (He may prefer feeling the pain of the examination than the pain of injection.)
Assess collateral ligament stability by stress testing the injured joint both radially and ulnarly—performed with the joint at about 20 degrees of flexion. A partial ligament tear allows no laxity, but there is little or no resistance to stress if the collateral ligament tear is complete.
Test for avulsion of the central anterior tendon slip by having the patient attempt to extend the middle phalanx against resistance (see Chapter 99). If the patient is unable to extend his finger at the PIP joint, a central-slip extensor injury should be suspected.
Test for an avulsion of the volar carpal plate by passively attempting to hyperextend the PIP joint. If hyperextension is greater than that of the same finger on the uninjured hand, a disruption of the volar plate must be considered, because delay in making this diagnosis may lead to chronic pseudoboutonnière deformity (see Chapter 99).
If any of these associated injuries exist, orthopedic consultation should be sought, and prolonged splinting and rehabilitation may be required.
When there is no loss of function and no significant joint instability or fracture, immobilize the joint by buddy taping adjacent digits. Have the patient remove the tape while sleeping or if the hand becomes wet (to prevent maceration of the skin), and have him dry the skin thoroughly prior to re-taping. Prophylactic nighttime PIP extension splinting can be used with the more serious sprains to prevent the mild PIP joint flexion contractures that are common consequences of these injuries. Very minor sprains may not require any special splinting.
When a central extensor tendon slip injury is suspected, splint the PIP joint in full extension without immobilizing the distal interphalangeal or metacarpophalangeal joints (see Chapter 99).
Disruption of the volar plate with abnormal hyperextension at the PIP joint and injuries with minor fractures require splinting with a padded dorsal splint 20 to 30 degrees short of full extension for 3 to 4 weeks with buddy taping to the adjacent finger for another 2 to 4 weeks. Provide follow-up for active range-of-motion exercises to restore normal joint mobility.
When collateral ligament instability is present, splint the affected finger to the finger adjacent to the ruptured ligament.
Instruct the patient to use elevation and acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs) for pain. Ice may be used if it provides comfort.
Inform the patient that swelling, stiffness, and discomfort may persist for several months, and provide follow-up for continued care or physical therapy. Active range-of-motion exercises performed by squeezing a soft foam ball can be helpful.
What Not To Do:
Do not miss joint instability or tendon avulsion—these injuries require special splinting and orthopedic referral.
Do not immobilize the PIP joints when buddy taping by taping over the PIP joints. Early mobilization is an important benefit.
Discussion
Most PIP joint sprains are stable and heal well with minimal splinting and early mobilization.
The major complications of the more severe PIP joint injuries are stiffness, joint enlargement, ligamentous laxity, and boutonnière deformity. Temporary stiffness and joint enlargement are to be expected for most PIP joint sprains. Boutonnière deformity (see Chapter 99) can be prevented by adequate examination and diagnosis of volar-plate disruption and central-slip injuries. Ligamentous laxity is not common, but if there is significant laxity, which usually affects the index or small finger, the ligament may need to be surgically reattached or reconstructed.
Early recognition of instability—either dorsal, volar, or lateral—as well as discovering weakness to extension against resistance, offers the best possibility of closed treatment leading to satisfactory functional healing. The main goals are to enable volar-plate, collateral-ligament, or central-slip healing, and to restore normal joint function.
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