Central Slip Avulsion and Pseudoboutonniere Deformities

By admin Last updated Nov 23, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Jeffrey Feden

Razib Khaund

Basics

Description

Boutonniere deformity describes a characteristic flexion deformity of the proximal interphalangeal (PIP) joint and hyperextension deformity of the distal interphalangeal (DIP) joint; it results from disruption of the central slip at or near its insertion onto the dorsal aspect of the base of the middle phalanx.
Mechanism of injury is often forced flexion of an extended PIP joint or volar dislocation of the middle phalanx, causing avulsion of the central slip.
Deformity of the finger may develop several weeks after an untreated injury.
Pseudoboutonniere deformity results from hyperextension of the PIP joint; the volar plate is ruptured, whereas the central slip remains intact.

Epidemiology

Unknown incidence but relatively uncommon

Risk Factors

Ball-handling sports

Etiology

Boutonniere deformity:
- Following avulsion of the central slip, the intact lateral bands slowly migrate in a volar direction as the central slip retracts.
- The head of the proximal phalanx “buttonholes” through the injured extensor mechanism.
- The lateral bands become flexors of the PIP joint and extenders of the DIP joint.
Pseudoboutonniere deformity: Contracture and fibrosis of the volar plate following injury leads to a flexion deformity of the PIP joint.

Diagnosis

History

Always consider injury to the central slip when an athlete “jams” a finger or has a PIP joint dislocation reduced.
Knowledge of the mechanism of injury and/or direction of a PIP joint dislocation also may localize the injury and guide treatment.
- Forced flexion of an extended PIP joint or volar dislocation of the middle phalanx may cause central slip injury.
- Hyperextension of the PIP joint or dorsal dislocation of the middle phalanx may cause volar plate injury.

Physical Exam

Early: Swollen PIP joint with dorsal tenderness, weak active extension, full passive extension; classic deformity is rarely seen in the acute setting.
Late: Flexion deformity of the PIP joint with hyperextension of the DIP joint
Unlike a true boutonniere deformity, pseudoboutonniere deformity is characterized by a fixed flexion contracture of the PIP joint, inability to achieve passive extension, and mild or absent DIP joint hyperextension.

Diagnostic Tests & Interpretation

Imaging

Plain radiographs (especially a true lateral view) to evaluate for fracture, dislocation, and volar plate injury

Differential Diagnosis

Fracture
PIP joint dislocation
Volar plate disruption
Collateral ligament tears

Treatment

Boutonniere deformity:
- Strict immobilization of the PIP joint in continuous extension for 4–6 wks; nighttime splinting for another 2–3 wks (1,2,3)[C]
- Allow active and passive flexion of the DIP joint without immobilization (1,2,3)[C].
- Gentle active and passive range of motion after splinting is completed (1,2,3)[C]
- Splinting is appropriate initial treatment even for chronic deformity (3)[C].
- Safety-pin splints are most practical for flexion contractures of >40 degrees; dynamic spring splints may be used for greater contractures (4)[C].

P.69

Pseudoboutonniere deformity:
- May be treated with progressive extension splinting if the flexion contracture is <45 degrees; otherwise, surgical release should be considered (5)[C].
- Acute volar plate injuries should be treated initially with an extension block splint and active flexion for 3 wks, followed by gradual extension (5)[C].

Additional Treatment

Referral

Referral is recommended for:

Inability to reduce a PIP joint dislocation or a large, displaced intra-articular PIP joint fracture
Failure of nonoperative treatment with splinting
Chronic flexion contractures of >45 degrees

Surgery/Other Procedures

Consider surgical management for:

Interposed soft tissue preventing congruent reduction of a volar PIP dislocation
Large, displaced intra-articular PIP fracture at the base of the middle phalanx
Flexion contractures of >45 degrees
Symptomatic, chronic deformities

Ongoing Care

The athlete's sport and position will dictate his or her ability to participate with the injured finger immobilized.

References

1. Hong E. Hand injuries in sports medicine. Prim Care. 2005;32:91–103.

2. Peterson JJ, Bancroft LW. Injuries of the fingers and thumb in the athlete. Clin Sports Med. 2006;25:527–542, vii–viii.

3. Lee SJ, Montgomery K. Athletic hand injuries. Orthop Clin North Am. 2002;33:547–554.

4. Aronowitz ER, Leddy JP. Closed tendon injuries of the hand and wrist in athletes. Clin Sports Med. 1998;17:449–467.

5. Rettig AC. Athletic injuries of the wrist and hand: part II: overuse injuries of the wrist and traumatic injuries to the hand. Am J Sports Med. 2004;32:262–273.

Additional Reading

Coons MS, Green SM. Boutonniere deformity. Hand Clin. 1995;11:387–402.

Hogan CJ, Nunley JA. Posttraumatic proximal interphalangeal joint flexion contractures. J Am Acad Orthop Surg. 2006;14:524–533.

Codes

ICD9

736.21 Boutonniere deformity

Clinical Pearls

An acutely injured PIP joint with dorsal tenderness and weak active extension should be treated empirically even in the absence of a classic boutonniere deformity.
Accidental flexion of the PIP joint during the treatment period must be avoided to prevent disruption of the healing process.
The majority of central slip injuries can be treated nonoperatively with satisfactory results.
The mechanism and direction of injury at the PIP joint may help to differentiate boutonniere from pseudoboutonniere deformities.