Phalangeal Fractures Clinical Presentation

Distal phalangeal fractures

Most distal phalangeal fractures are crush injuries from a perpendicular force, as in injuries from a car door or hammer or in sports when a player has a digit stepped on or crushed between the helmets of opposing players. Tuft fractures are often comminuted and are generally stable fractures because of intrinsic splinting of bony fragments by fibrous septae in the fingertips.

Physical examination in a person suspected of having a phalangeal fracture starts with inspection, attitude of the injured finger, and localization of any swelling. Neurovascular status should be examined as well as color, capillary refill, and digital temperature.

• Palpation of the joint over 4 planes (ie, dorsal, volar, medial, lateral) allows assessment of point tenderness over ligamentous origins and insertions, which is suggestive of soft-tissue disruption.

• Passive range of motion and joint stability should be assessed through dorsal, volar, and lateral stressing. It should not be assumed that lack of full active flexion or extension is merely secondary to joint pain.

Fractures at the base of the distal phalanx are usually mallet avulsion fractures and are caused by rupture of the extensor tendon at the DIP joint. These are common injuries in basketball or baseball players. ^[10] The mechanism of injury usually results from a direct blow to the tip of the finger that causes forced flexion of the DIP joint.

Jersey finger

Avulsion of the flexor digitorum profundus from its insertion on the volar base of the distal phalanx results in the jersey finger. The mechanism of injury most commonly occurs in football when a player grabs the opponent's jersey. There is forced hyperextension of the DIP joint against an actively contracting flexor tendon. The ring finger is most commonly involved. Pain and swelling of the affected finger occurs, with loss of active flexion of the DIP joint.

This injury is often overlooked because on physical examination there is no obvious deformity present and the loss of DIP flexion is either not appreciated or dismissed secondary to pain or soft-tissue swelling. If one suspects flexor tendon avulsion, then gentle active flexion of the DIP joint should be tested specifically. Radiographic findings are often normal but may reveal a small avulsion fracture.

Middle phalangeal fractures

The mechanism of injury of middle phalangeal fractures is usually the result of a blunt or crush force perpendicular to the long axis of the bone. Angulation and rotation are 2 features of instability that must be examined.

Visual inspection usually detects dislocations and subluxations but is most valuable in the angulatory or rotary deformities that can accompany subluxation/dislocations. These deformities suggest complications ranging from asymmetric ligament tears to interposed tissues between joint surfaces. Rotational deformities are serious injuries and are detected clinically. Patients should be asked to fully flex the phalanges, and the long axis of the fingers should point to the scaphoid tubercle or the distal radius with the fingers parallel to each other.

Dorsal or volar angulation is evaluated radiographically in relation to the insertion of the flexor digitorum superficialis. Fractures distal to the tendon result in volar angulation, and proximal fractures result in dorsal angulation from the resulting muscle pull.

Proximal phalangeal fractures

Proximal phalangeal fractures are relatively common and may result in a great deal of disability. The mechanism of action usually results from a direct perpendicular force, a rotary force, or hyperextension of the finger.

The physical examination is the same as that for distal phalangeal fractures (see above).

Dorsal PIP joint dislocations

Dorsal dislocation of the PIP joint is a common injury that occurs secondary to joint hyperextension. The volar plate must be ruptured for dorsal dislocation to occur. This rupture usually occurs at the distal insertion site at the base of the middle phalanx and may involve a tiny avulsion fracture of the base of the middle phalanx.

When disruption of the collateral ligaments has also occurred, rotary deformity and lateral stress instability will be apparent. Joint dislocation should be assessed for collateral ligament injury, because any associated collateral ligament problems require orthopedic referral.

Volar PIP joint dislocations

Volar dislocations of the PIP joint are less common than dorsal dislocations and are more difficult to manage than other injuries. A volar dislocation ruptures the extensor mechanism, possibly involving injury of the central slip.

Evaluation of the PIP joint injury starts with the history to understand the mechanism and direction of injury, the presence of an initial deformity, and whether a reduction was performed. The physical examination includes thorough inspection and palpation of the area and localization of the tenderness. The examination should also include testing active and passive range of motion, with and without resistance. Tenderness dorsally indicates a central slip injury. This is confirmed if there is pain and inability to extend the PIP joint against resistance. Lateral stressing of the joint assesses integrity of the collateral ligaments and the degree of instability.

Grading and treatment

Instability of the PIP joint is classified as 3 grades, and treatment is based on the grading of the injury. Grading is based on active range of motion and stress testing. When pain interferes with evaluating for these, a local anesthetic block at the metacarpal level should be performed. The grades are as follows:

• Grade I injuries are stable through an active range of motion and do not angulate more than 20° greater than the contralateral side on stress testing.

• Grade II injuries will not deform with active range of motion, but stress testing will show instability, defined as greater than 20° of angulation when compared with the contralateral side. These injuries are due to a complete disruption of one of the major retaining ligaments, which include the radial or ulnar collateral ligaments, the volar plate, or the central extensor slip.

• Grade III injuries show deformity with active range of motion or the injured fingers are unable to be moved through more than 75% of the range of motion under anesthetic block. This implies complete disruption of greater than 50% of the entire capsule or 2 or more of the major retaining ligaments.

Collateral ligament injuries may be the result of a pure angulatory stress or a joint dislocation with the radial collateral ligament as the ligament most frequently injured.

The most common complication of a volar plate injury or dorsal dislocation is the development of pseudo-boutonniere deformity, which is a persistent PIP joint flexion contracture. Another common problem is detachment of the volar plate, resulting in hyperextension laxity at the PIP joint and a swan-neck deformity. Associated with the swan-neck deformity is the painful snapping of the lateral bands with attempted flexion. Both of these complications can be prevented with appropriate treatment.

DIP joint dislocations: Dislocations of the DIP joint are uncommon. Such injuries are usually the result of a hyperextension force, and they are frequently open because the skin in this area is both thin and well anchored.

Boutonniere deformity

Disruption of the central slip of the extensor digitorum communis tendon over the PIP joint produces the classic boutonniere deformity. This can be caused by blunt trauma over the dorsal aspect of the finger, with a deep laceration over the PIP joint, or with forced flexion of the joint.

Avulsion of the central slip results in a flexion deformity of approximately 15-30° due to unopposed pull of the flexor digitorum superficialis tendon. As a result of loss of extensor tendon function, in addition to localized pain and swelling, the PIP joint cannot be actively extended. One can think of this as the PIP "buttonholing" through the central slip.

Prevention of a boutonniere deformity requires a high index of suspicion during the acute stage of the injury. A central slip injury should be suspected in patients who present with pain mainly over the dorsal aspect of the PIP joint.

Radiographic findings are rare for the small avulsion fracture at the dorsal base of the middle phalanx. The best indication of central slip damage is inability to extend the PIP joint fully against active resistance. A central slip disruption is present unless proven otherwise when full extension cannot be performed.

Immediately after injury, examination will reveal a diffusely swollen PIP joint held in mild flexion. Active extension may be possible with the lateral bands. The diagnosis is made by palpating all 4 quadrants of the joint. This is confirmed if there is pain and inability to extend the PIP joint against resistance. Tenderness dorsally indicates a central slip injury.

Boutonniere deformities are graded I through IV, as follows:

• A grade I injury is correctable passively.

• A grade II injury is the case in which there is a PIP joint flexion contracture of less than 30° that is not passively correctable.

• Grade III boutonnieres demonstrate a PIP joint flexion contracture greater than 30° and loss of flexion of the distal joint.