Fracture, Metacarpal Neck: I-V

By admin Last updated Dec 14, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Quynh Hoang

Chris Koutures

Basics

Description

The metacarpal neck (distal metaphysis) is the aspect of the metacarpal shaft immediately underneath the metacarpal head.
The weakest point of the metacarpal is located at the distal metaphysis, so metacarpal fractures frequently involve the neck (1)[C].
The mechanism of injury is usually an axial load on the metacarpal phalangeal (MCP) joint while in a flexed position, such as when throwing a punch.
Fractures about the metacarpal neck must be scrutinized for malrotation and angulation.
As 2nd and 3rd metacarpals are necessary for handgrip power, much less angulation is tolerated in these injuries.
Synonym(s): Boxer's fracture; 5th metacarpal neck fracture

Epidemiology

5th metacarpal neck fractures (boxer's fractures) are the most common hand fracture, accounting for 20% of all hand fractures (1)[C],(2)[B].
Fractures of the 1st metacarpal neck are uncommon.

Risk Factors

Out-of-control tempers: Boxer's fractures usually are due to striking an opponent or a wall with a clenched fist.

Etiology

Due to the action of the interosseus muscles, the distal fracture fragment (metacarpal head) displaces volarly, resulting in an apex dorsal angulation.
The index and long fingers cannot tolerate angulation deformities given their relatively fixed articulations with the distal carpal bones.
The ring and small fingers, however, have limited flexion and extension, so angular deformities are better tolerated and they heal with minimal loss of function.

Diagnosis

History

Axial load or direct trauma, often to clenched fist or dorsum of the hand
Immediate pain and swelling noted

Physical Exam

Swelling and tenderness on the dorsum of the hand, often accompanied by metacarpophalangeal (MCP) joint depression
Extreme angulation may lead to pseudoclawing, ie, hyperextension of the MCP joint along with proximal interphalangeal (PIP) joint flexion as the patient attempts to extend the finger.
Tenderness and swelling about the dorsal aspect of the distal metacarpals. Examine skin closely for teeth marks or other injuries.
Evaluate the digits for malrotation, which occurs more in 4th and 5th metacarpal neck fractures. Have the patient bring all the fingernails into the palm and compare with the noninjured hand. All the nails should point toward the base of the 1st metacarpal. If the injured finger is out of this alignment, strongly suspect significant fracture malrotation.

Diagnostic Tests & Interpretation

Imaging

Anteroposterior, oblique, and true lateral views of the hand usually are sufficient.
Normally, the metacarpal neck is situated with a baseline of 15 degrees of volar angulation. Ensure adequate visualization on the lateral view to evaluate the degree of fracture angulation.
A conservative rule for limits of acceptable angulation of the 2nd through 5th digits is 10–30. Thus, the 2nd digit can only tolerate 10 degrees of angulation (in addition to the baseline 15 degrees); the 5th metacarpal can accept 30 degrees above the baseline. Many other experts will tolerate a greater degree of angulation of the 5th metacarpal; this decision often is influenced by the particular activity or sport of the patient.
Degrees of acceptable angulation vary in current literature. For the index or long finger, some authors report that angulations of >15 degrees above baseline are not tolerated due to the lack of carpal metacarpal motion (1)[C]. Others report that for the ring finger up to 30 degrees of excessive angulation (above baseline) at the metacarpal neck is acceptable, and for the small finger, up to 40 degrees of excessive angulation (above baseline) at the 5th metacarpal neck is acceptable (3)[C],(2)[B].

Differential Diagnosis

Metacarpal head fracture
Metacarpal shaft fracture
Open fracture
MCP joint dislocation
MCP joint sprain

Treatment

NSAIDs can be used along with ice for immediate analgesia.
Narcotic analgesics may be necessary for sleep during the first few nights after the injury.
Closed reduction is considered in cases of significant angulation of 4th (>20 degrees above baseline) and 5th (>30 degrees above baseline) metacarpal neck fractures.
Anesthesia can be obtained by hematoma block or ulnar nerve block.
Flex the MCP, PIP, and distal interphalangeal joints all to 90 degrees. Apply dorsally directed pressure along the proximal phalanx shaft through the flexed PIP joint while simultaneously applying volarly directed pressure over the proximal fracture fragment (3)[C].
Obtain a postreduction lateral view of the hand to ensure adequate reduction and immobilization.
Nondisplaced and nonangulated fractures of the 2nd or 3rd metacarpal necks can be immobilized in a radial gutter splint with the wrist in 30 degrees extension, MCP joint in 70–90 degrees of flexion, and PIP/DIP joints near full extension.
Mildly angulated 4th (<20 degrees above baseline) and 5th (<30 degrees) metacarpal neck fractures can be immobilized in ulnar gutter splints with the same positions.
Alternatively, some literature recommends functional treatment by casting (glove cast) or by taping with pressure bandage (3)[C],(2)[B]. For functional casting, the cast is applied circularly around the metacarpals, and it starts distal to the palmar crease of the wrist and ends just proximal to the MCP joint. This allows maximal range of motion of the finger and wrist while providing immobilization and protection of the fracture fragment.
Elevate the hand and apply ice for 20-min intervals on a regular basis over the first 24–48 hr after injury.

P.221

Splints should be applied to injuries requiring orthopedic referral (see below), unless that consultant is immediately available.
Controversy still exists regarding the optimal management for metacarpal neck fractures, particularly for fracture of the 5th metacarpal neck.
There is no consensus on:
- How much angulation is acceptable (recommendations in literature vary from 20–70 degrees for the 5th metacarpal)
- Which splinting method is most optimal
- What length of immobilization is optimal (literature varies anywhere from no immobilization to 1 wk of immobilization followed by functional treatment, to pure immobilization ranging from 2–4 wks)
In a randomized controlled trial by Muller et al., no differences in functional outcome were found between boxer's fractures treated with immobilization in an ulnar gutter cast for 3 wks and those treated with functional taping for 1 wk. Furthermore, range of motion of the 5th CP joint was not affected in fractures with angulation <70 degrees that were not reduced (2)[B].
In a 2005 Cochrane Review, the authors concluded that there is no single nonsurgical treatment method that can be recommended as superior to another (4)[B].

Additional Treatment

Referral

Open reduction and internal fixation is indicated for:

Significant angulation of 2nd (>10 degrees above baseline) and 3rd (>10 degrees above baseline) metacarpal neck fractures, or those with any displacement
Failure to achieve acceptable angles after reduction of the 4th and 5th metacarpals
Any metacarpal neck fracture with rotational malalignment or comminution
Any potential open fracture
Degree of residual angulation that is unacceptable to the patient
Inability to hold reduction position
Athlete who desires immediate return to play in cast orthosis

Ongoing Care

Fractures should remain splinted for a minimum of 3–4 wks.
Clinical healing is defined as no tenderness with palpation of the fracture site.
Once the splints are removed, begin range of motion work with emphasis on handgrip and manipulation strength. Key to prevent stiffness of the MCP joint.

Follow-Up Recommendations

For 2nd and 3rd metacarpal neck fractures, follow-up radiographs should be obtained in 5–7 days to monitor fracture alignment.
For 4th and 5th metacarpal neck fractures, follow-up radiographs should be taken at 7–10 days.
Perform follow-up visits at 2-wk intervals to monitor for malalignment, rotational deformity, angulation, and progress of healing.

Patient Monitoring

Return to sports participation recommended when there is pain-free range of motion and when strength approaches that of the contralateral hand.
In general, conservative guideline for return to contact sports with splint/orthotic protection is after 2–4 wks of immobilization. Some experts may allow immediate return to play with a protective cast or splint.
Use of orthotic protection during contact sports should continue for 8–10 wks after the initial injury.

Patient Education

Patients should be warned that despite reduction and splinting, loss of knuckle prominence may result.
After splint removal, educate patient on range of motion exercises to prevent MCP joint stiffness.

Complications

MCP joint stiffness due to prolonged immobilization, interosseus muscle contractures, or tendon adhesions
Cosmetic deformity without functional loss still may ensue.
Although uncommon, delayed union or nonunion of the fracture site may occur.
Pseudoclawing

References

1. Capo J, Hastings H. Metacarpal and phalangeal fractures in athletes. Clin Sports Med. 1998;17: 491–511.

2. Muller M, Poolman R, et al. Immediate mobilization gives good results in boxer's fractures with volar angulation up to 70 degrees: a prospective randomized trial comparing immediate mobilization with cast immobilization. Arch Orthop Trauma Surg. 2003;123:534–537.

3. Leggit J, Meko C. Acute finger injuries: part II. Fractures, dislocations, and thumb injuries. Am Fam Physician. 2006;73:827–834.

4. Poolman RW, Goslings JC, et al. Conservative treatment for closed fifth (small finger) metacarpal neck fractures. Cochrane Database Syst Rev. 2005;3:CD003210.

Codes

ICD9

815.04 Closed fracture of neck of metacarpal bone(s)
815.14 Open fracture of neck of metacarpal bone(s)