Middle phalanx fractures

INTRODUCTION — Finger fractures are among the most common injuries managed by primary care and emergency clinicians. An understanding of basic finger anatomy and common injury patterns provides the basis for diagnosing and treating these injuries.

Fractures of the middle phalanx are discussed here. Finger anatomy, other common finger injuries, and thumb injuries are reviewed separately. (See "Distal phalanx fractures" and "Proximal phalanx fractures" and "Extensor tendon injury of the distal interphalangeal joint (mallet finger)" and "Flexor tendon injury of the distal interphalangeal joint (jersey finger)" and "Digit dislocation reduction" and "Evaluation of the patient with thumb pain" and "Finger and thumb anatomy".)

CLINICAL ANATOMY — Anatomy of special importance to middle phalanx fractures is described below; a more detailed discussion of finger anatomy is found elsewhere. (See "Finger and thumb anatomy".)

The proximal interphalangeal (PIP) joint and the distal interphalangeal (DIP) joint form the articulations of the middle phalanx (figure 1 and figure 2). At the PIP joint, the biconcave base of the middle phalanx articulates with the convex head of the proximal phalanx. These joints are stabilized by a volar plate, extensor apparatus, capsule, and collateral ligaments. Just proximal to the PIP joint, the flexor digitorum superficialis tendon splits to allow for the flexor digitorum profundus (FDP) to travel through its center (figure 3). The FDP then passes along the palmar surface of the middle phalanx and attaches to the distal phalanx. The FDP enables DIP joint flexion.

The flexor digitorum superficialis (FDS) attaches to the palmar surface of the middle phalanx and is the primary flexor of the PIP joint. The deforming forces that act on the middle phalanx fractures are the FDS and the intrinsic tendons. Middle phalangeal fractures proximal to the FDS insertion have an apex dorsal angulation, whereas fractures distal to the FDS insertion have an apex volar angulation as shown in the figure (figure 4). Deep to the flexor tendons the volar plate provides stability against hyperextension.

On the dorsal surface, the extensor tendon central slip passes over the PIP joint and inserts on the base of the middle phalanx, while the lateral bands proceed distally, attaching to the base of the distal phalanx. Fractures at the proximal base of the middle phalanx can cause an avulsion of the insertion of the extensor tendon central slip. If unrecognized, a boutonniere deformity usually develops (figure 5 and figure 6).

The volar plate is a thickened reinforcement of the capsule of the PIP joint that provides stability in the antero-posterior plane of the PIP joint and prevents hyperextension. It attaches to the periosteum of the middle phalanx distally and to the capsule proximally near the proximal phalanx. Bony avulsion fractures associated with volar plate injuries typically occur at its stronger distal attachment at the middle phalanx [1,2].

MECHANISM OF INJURY — Fractures of the shaft of the middle phalanx are commonly caused by a direct blow to the dorsum of the hand [3]. Less commonly, injuries occur from an axial load or twisting mechanism.

Fractures at the base of the middle phalanx most commonly involve the volar lip. Less common are dorsal lip fractures and central comminution (pilon) fractures. These fractures occur most commonly from an axial load placed on the finger by a ball or other moving object, resulting in hyperextension of the proximal interphalangeal (PIP) joint, possibly involving dorsal subluxation, excessive rotary force, or dislocation of the middle phalanx [1,4,5]. Such injuries are sometimes mistaken for a sprain (or "jamming" of the finger).

PRESENTATION AND PHYSICAL EXAMINATION — Fractures of the shaft of the middle phalanx present with pain and swelling, generally following trauma to the dorsum of the finger. Ecchymosis may be present. The phalanx is typically tender.

Fractures at the base of the middle phalanx typically present with pain and swelling at the proximal interphalangeal (PIP) joint. Volar (ie, palmar) lip fractures are the most common of the base fractures. They result from a combination of PIP joint hyperextension and axial loading. Patients present with swelling, pain, limited motion at the PIP joint, and a flexed finger posture.

Volar plate avulsion fractures present with swelling of the PIP joint, often with bruising along the volar surface. Often there is loss of motion at the PIP joint due to swelling or pain. Tenderness is generally greatest at the volar surface of the PIP joint. The physical examination may be limited by swelling or pain, but the clinician should attempt to assess the stability of the PIP joint.

During the initial examination, the clinician should focus on identifying any complicating factors that require urgent treatment, including: open injury, neurovascular deficits, malalignment or dislocation, and tendon dysfunction.

The neurovascular status of fingers is evaluated using two-point discrimination and capillary refill time. Although values for both these tests increase with age and certain disease states (eg, diabetes), normal two-point discrimination is approximately 4 to 5 mm, while normal capillary refill is generally less than two seconds [6]. (See "Finger and thumb anatomy".)

Middle phalanx fractures are commonly associated with tendon or other soft tissue injuries, which often manifest as angulation. The complex tendon anatomy in the region of the middle phalanx can lead to variations in fracture patterns, joint immobility, and fracture instability. Middle phalangeal fractures proximal to the flexor digitorum superficialis (FDS) insertion have an apex dorsal angulation, whereas fractures distal to the FDS insertion have an apex volar angulation as shown in the figure (figure 4 and figure 7) [7].

Evaluation for deformity or rotation of the phalanx should be performed with the fingers in extension and flexion (picture 1A-B and picture 2). Careful examination of the PIP and distal interphalangeal (DIP) joints is mandatory. The flexor and extensor mechanisms of the PIP and DIP joints should be evaluated to rule out associated tendon injuries (picture 3A-B and picture 4A-B). Careful evaluation of the extensor tendon is necessary to rule out central slip injuries, which can lead to a boutonniere deformity caused by unopposed action of the flexor tendons (figure 5 and figure 6). The palmar surface of the finger should be examined for damage to the flexor tendon or volar plate. Collateral ligaments are evaluated by placing a varus and valgus stress on the DIP and PIP joints (picture 5).

DIAGNOSTIC IMAGING — Posterior-anterior (PA), lateral, and oblique radiographs are obtained to evaluate the middle phalanx (image 1). Transverse fractures can occur proximally or distally and require evaluation for displacement and angulation. Proximal transverse shaft fractures may present in an apex dorsal position, if the flexor digitorum profundus pulls the distal fragment volarly [3,7,8]. Distal transverse fractures may present in an apex volar position if the flexor digitorum superficialis pulls the proximal fragment volarly (figure 4 and figure 7). (See 'Clinical anatomy' above.)

Oblique and spiral fractures are evaluated for shortening or rotation and are often unstable due to the forces exerted by the various tendon and ligament insertions (image 2 and image 3 and image 4 and image 5).

Intraarticular fractures are commonly associated with soft tissue trauma, such as volar plate injuries, extensor central slip or terminal slip injuries, and collateral ligament tears (image 6 and image 7 and image 8 and image 9 and image 10). Avulsion fractures of the proximal portion of the middle phalanx are best seen on the lateral radiograph. Subluxation of the PIP joint may be noted.

INDICATIONS FOR SURGICAL REFERRAL

General indications — A hand or orthopedic surgeon should be consulted immediately for any open fracture and any fracture associated with a tendon or nerve injury.

Comminuted fractures, pilon fractures, rotational fractures (image 4), intraarticular fractures (image 9), and displaced or angulated fractures (image 11) that cannot maintain their reduction should all be referred to a hand or orthopedic surgeon. Most spiral and oblique fractures involve rotation or shortening and are unstable [3,7,8]. They should also be referred.

Avulsion fractures involving 30 percent or more of the articular surface are considered unstable and require surgical referral, as do volar plate injuries associated with subluxation [1,2,4]. Minor avulsion fractures that are clinically stable may be managed by primary care clinicians who are knowledgeable about fracture management.

Classification and determining stability of base fractures — Intraarticular fractures at the base of the middle phalanx can be classified using the Keifhaber-Stern classification as stable, tenuous, or overtly unstable depending upon the amount of articular surface involved and the presence of associated ligamentous injury [9]. They are considered stable if less than 30 percent of the articular surface is involved, the collateral ligaments are intact, and the joint remains congruent through a full range of motion. They are considered tenuous if 30 to 50 percent of the articular surface is involved. Any fracture of the base of the middle phalanx that involves greater than 50 percent of the joint surface is considered unstable [9]. If more than 30 degrees of flexion is needed to maintain fracture reduction, these injuries too are considered unstable. Unstable fractures can sublux dorsally, in which case a V-sign may be appreciated on lateral plain radiograph (image 10). Base fractures may be associated with complete dislocation, depending upon the degree of associated ligamentous injury.

Volar plate hyperextension injuries can be classified using the Eaton classification system [10]:

●Type 1: Avulsion of the volar plate without a fracture or dislocation

●Type 2: Complete dorsal dislocation without fracture and avulsion of the volar plate

●Type 3a: Fracture-dislocation with <40 percent proximal interphalangeal (PIP) joint surface with dorsal portion of the collateral ligaments remaining attached to the middle phalanx (stable)

●Type 3b: Fracture-dislocation with >40 percent PIP joint surface with little or no ligament remaining attached to the middle phalanx (unstable)

MANAGEMENT

Nondisplaced fractures — Nondisplaced stable fractures of the middle phalanx without angulation are treated by buddy taping them to an adjacent finger (picture 6) [3,11]. If the ring finger is involved, it should be buddy taped to the little finger. Short-term immobilization with a dorsal (picture 7) or volar finger splint (picture 8) or a toad splint (picture 9) can be used for added protection or pain control [12].

Nondisplaced fractures should be reevaluated by physical examination and radiographs within one week injury to check for displacement, angulation, or rotational deformity [3,11]. If no malalignment is detected, buddy taping is continued for a total of approximately four to six weeks, until clinical healing has occurred. Range of motion exercises to restore normal mobility at the distal interphalangeal (DIP), proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints should be encouraged while buddy taping is continued [13].

The finger should be examined every one to two weeks until range of motion and finger function is normal. Radiographs can be obtained three to four weeks after the first follow-up appointment to ensure healing, but are not necessary unless malalignment or inadequate clinical healing occurs (eg, pain persists or function is compromised). Frequently, radiographic healing lags behind clinical healing.

Displaced or angulated fractures — Closed reduction often produces satisfactory results for angulated or minimally displaced fractures of the middle phalanx. A digital block is used for local anesthesia. Proximal shaft fractures often present in an apex dorsal position, while distal fractures present in an apex volar position. Reduction is performed by applying longitudinal traction, and then using three-point pressure to bring the distal fragment into alignment with the proximal fragment (picture 10 and picture 11) [3,11]. If the fracture is displaced in an apex volar position, flexion of the DIP joint can help realign the distal fragment.

Following reduction, the injured finger should be immobilized in an ulnar or radial gutter splint with buddy taping to an adjacent finger (figure 8) [3,11]. Proper positioning in the splint is as follows:

●Wrist in 20 to 30 degrees of extension

●MCP joints in 70 to 90 degrees of flexion

●PIP and DIP joints flexed 5 to 10 degrees

Increased flexion of the PIP joint may be helpful for maintaining reduction in more proximal fractures of the middle phalanx with significant apex dorsal angulation. Flexed positioning decreases the force exerted by the flexor digitorum superficialis [14].

Although it is not as protective, a dorsal finger splint with buddy taping may be used instead of a gutter splint using the same joint positioning. This approach should not be used if patient compliance is in doubt or if the patient is required to perform any lifting or strenuous work with their hands.

Once splinted, post-reduction radiographs are obtained to ensure the reduction is adequate. No more than 1 or 2 mm of displacement or shortening is acceptable. Up to 10 degrees of angulation is acceptable but no amount of rotation is permitted. The patient should be referred to a hand or orthopedic surgeon if adequate reduction cannot be maintained. (See 'Indications for surgical referral' above.)

Displaced or angulated middle phalanx fractures are treated with four weeks of splinting. Repeat examinations and radiographs should be performed with the splint in place one week following the injury, and every one to two weeks thereafter. Total time in the gutter splint should not exceed four weeks to prevent stiffness and loss of motion [3]. After four weeks, buddy taping is used to provide stability.

Once the fracture has maintained a stable position for a minimum of three weeks, the splint is removed. Buddy taping is applied for four to six weeks for further protection, but range of motion exercises are begun. If there is significant swelling or loss of motion, formal physical therapy under expert supervision should be performed [13]. Thereafter, range of motion and function are evaluated every two weeks until normal function is achieved. Radiographs can be obtained every four to eight weeks until complete fracture healing is evident; full radiographic healing can take up to 12 weeks [8].

Volar plate avulsion fractures — Volar plate avulsion fractures of the proximal middle phalanx that involve over 30 percent of the joint surface are often unstable and should be referred to a hand surgeon for treatment. Smaller fractures may be managed conservatively but the best approach remains unclear. Given that studies to date show that early immobilization is associated with acceptable outcomes and has not been shown to cause harm, we suggest the following approach:

●Buddy tape the finger or place the injured finger in an extension block splint or aluminum splint in slight flexion for 5 to 10 days if needed for pain control or swelling.

●Once the splint is no longer needed for pain, allow range of motion of the finger while using buddy taping until range of motion and function have returned (generally three to four weeks).

●Reevaluate the finger one week after the initial injury looking closely for any sign of joint instability or any deformity or malrotation. If the examination reveals no problems, subsequent reevaluations can be performed every one to two weeks until motion and overall function have returned to baseline.

●Repeat radiographs can be obtained at one and four weeks. Referral to a hand therapist may be necessary if motion is regained too slowly.

Treatment recommendations for small, stable volar plate avulsion fractures vary in the type of immobilization and the duration of treatment. Some recommend early range of motion while others suggest complete immobilization initially in a range of flexions [4,15-17]. Generally, an extension block or aluminum splint is used, with the finger held in slight flexion.

According to a systematic review, there is insufficient evidence to determine whether early active mobilization or splinting leads to better outcomes [18]. A retrospective study compared 20 patients immobilized in an extension block splint in neutral with 105 patients immobilized at 30 degrees of flexion and reported fewer flexion deformities without resultant hyperextensibility in the patients splinted at neutral [19]. Another retrospective study of Eaton type 1 and 2 fractures compared 23 patients immobilized in an extension block splint at 10 degrees of flexion with 21 patients managed with buddy taping [20]. All patients wore a night splint in 10 degrees of flexion, were followed for an average of nine weeks, and received hand therapy. Neither treatment was found to be superior, but buddy taping was thought to be easier.

Dorsal lip fractures — Dorsal lip fractures are often associated with extensor tendon central slip injuries. These are treated with the PIP joint in full extension for up to six weeks if a tendon tear is associated. Failure to recognize this injury may result in a boutonniere deformity (figure 6).

RETURN TO SPORT OR WORK — Patients with nondisplaced fractures can return to play or work once pain is controlled. Buddy taping is needed for a minimum of four to six weeks thereafter, and a protective splint should be used for any higher risk activities during this period.

Displaced fractures should remain in a gutter splint for three to four weeks, until radiographs demonstrate that the fracture has maintained a stable position and evidence of early healing is present [3,21]. After the gutter splint has been removed, the patient may return to noncontact activities, with buddy taping for protection, for an additional four to six weeks. If the patient's work or athletic activities involve heavy lifting or the risk of forceful trauma to the finger, then return should be delayed until plain radiographs demonstrate significant healing (ie, substantial callus present at fracture site). This will likely require six to twelve weeks in a healthy adult.

Patients with small volar plate avulsion fractures may return to work or sport once they have regained a functional range of motion. We suggest protection with buddy taping or splinting for an additional four to six weeks to prevent reinjury during high-risk activities.

COMPLICATIONS — Middle phalanx fractures complicated by shortening, angulation, or rotation can lead to malrotation of the finger and abnormal mechanics. Failure to recognize intraarticular involvement or prolonged use of splinting can lead to stiffness and loss of motion at the proximal interphalangeal (PIP) or distal interphalangeal (DIP) joint. Nonunion is a rare complication [8].

In addition, soft tissue injuries may accompany the fracture and lead to deformity [4,21]. Improperly treated volar dislocations or injury to the central extensor slip may result in a Boutonniere deformity [5].

Delayed treatment of intraarticular fractures often leads to poor outcomes, including contractures, instability, joint destruction, and chronic pain [5]. The most common complications following a volar plate avulsion fracture are pain, stiffness, and swelling [1,4,22]. Undiagnosed instability can lead to recurrent subluxation, traumatic arthritis, or a swan neck deformity [1,4,22,23]. A flexion contracture can develop due to poor healing and capsular fibrosis [23].

ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:

●(See "General principles of fracture management: Bone healing and fracture description".)

●(See "General principles of fracture management: Fracture patterns and description in children".)

●(See "General principles of definitive fracture management".)

●(See "General principles of acute fracture management".)

●(See "General principles of fracture management: Early and late complications".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Fractures of the skull, face, and upper extremity in adults" and "Society guideline links: Acute pain management".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Finger fracture (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Mechanism and presentation – Middle phalanx fractures occur most commonly from a blow to the dorsum of the hand but may occur from an axial load or twisting injury. They present with tenderness and swelling around the middle phalanx; ecchymosis may be present. (See 'Clinical anatomy' above and 'Mechanism of injury' above.)

●Physical examination – The initial physical examination should focus on identifying any complicating factors that require urgent treatment, including: open injury, neurovascular deficits, malalignment or dislocation, and tendon dysfunction. A neurovascular examination including two-point discrimination and capillary refill should be performed. (See 'Presentation and physical examination' above.)

Middle phalanx fractures are commonly associated with tendon injuries and the flexor and extensor mechanisms of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints should be examined carefully (picture 3A-B and picture 4A-B).

All middle phalanx fractures should be assessed carefully for evidence of rotation (picture 1A-B and picture 2), shortening, or angulation. Transverse fractures may present in an apex volar or apex dorsal position. Spiral or oblique fractures are often unstable.

●Diagnostic imaging – Anterior-posterior (AP), lateral, and oblique radiographs are obtained to evaluate the middle phalanx. Oblique and spiral fractures are often unstable (image 2 and image 3 and image 4 and image 5). Intra-articular fractures are commonly associated with soft tissue trauma, such as volar plate injuries, extensor central slip or terminal slip injuries, and collateral ligament tears (image 6 and image 7 and image 8 and image 9 and image 10). Avulsion fractures of the proximal phalanx are best seen on the lateral radiograph. (See 'Diagnostic imaging' above.)

●Surgical referral – Immediate consultation with a hand surgeon should be obtained for any open fracture and any fracture associated with a tendon or nerve injury. Comminuted fractures, rotational fractures, intraarticular fractures, and displaced or angulated fractures that cannot maintain their reduction require referral. (See 'Indications for surgical referral' above.)

●Management of uncomplicated injuries – Uncomplicated, nondisplaced middle phalanx fractures are treated with finger splinting or buddy taping. Minimally displaced fractures are reduced and initially treated in a gutter splint. Proper splinting, positioning of the finger, and follow-up are described in the text. Minor volar plate avulsion fractures are treated with early mobilization, with initial splinting provided as needed for comfort. Spiral or oblique fractures are often unstable and should be reassessed regularly looking for rotation and shortening. (See 'Management' above.)