Fracture, Metacarpal Base/Shaft: I-V

By admin On Nov 17, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Tara Robbins

Basics

Description

Metacarpal shaft and base fractures are defined by their location, pattern, and displacement:
- 3 types of metacarpal shaft fractures: Transverse, oblique or spiral, and comminuted
- 2 types of metacarpal base fractures: Intra-articular and extra-articular
Metacarpal fractures involving the 1st metacarpal (thumb) are considered separately from those involving the 2nd to 5th metacarpals.
Two intra-articular fractures of the thumb deserve special mention:
- Bennett's fracture: Fracture combined with a subluxation or dislocation of the metacarpal joint
- Rolando fracture: T- or Y-shaped fracture involving the joint surface

Epidemiology

Metacarpal fractures account for 1/3 of all hand fractures.
Small finger is the most commonly injured (50%), followed by the thumb, index, long finger, and ring finger (1)
Fractures of metacarpal base occur most commonly in the 4th and 5th metacarpals.
Metacarpal fractures account for 10–39% of pediatric hand injuries.

Incidence

Lifetime incidence of metacarpal fracture is 2.5%.

Risk Factors

Gymnastics, contact sports, racquet sports, boxing, karate

Etiology

Transverse and comminuted metacarpal shaft fractures usually result from a direct blow:
- Dorsal angulation is common.
Spiral metacarpal fractures result from indirect trauma or rotational torque applied to a digit:
- Fracture fragments tend to shorten and rotate, especially in the index and small fingers.
Intra-articular metacarpal base fractures are high-energy injuries and usually result from a direct blow over the base of the metacarpal or a significant axial force or torque applied to the digit:
- Associated with carpometacarpal (CMC) dislocations
- Most frequently occur in ring and small fingers
- Uncommon in index and middle fingers
- Avulsion fractures usually occur due to tractional forces from tendons that insert into the base of the metacarpals.
Extra-articular metacarpal base fractures occur from same forces as intra-articular metacarpal base fractures:
- Most are stabilized by intermetacarpal ligament resulting in only minimal displacement
- Can be associated with CMC dislocation of adjacent digit

Diagnosis

History

Direct blow vs indirect blow with rotational torque: Rotational torque often leads to spiral fractures.
Nerve injury or damage to the extensor tendon frequently is associated with crush injuries.

Physical Exam

Tenderness and swelling over the dorsal hand
Pain with motion
Inability to make a fist
All patients require a thorough neurovascular examination distal to the fracture site. 4th and 5th metacarpal base fractures may cause injury to the motor branch of the ulnar nerve, resulting in paralysis of the intrinsic hand muscles.
Evaluate for rotational malalignment:
- All the fingers of a closed fist should point to the scaphoid tubercle.
- No crowding or digital overlap should be present when the digits are fully flexed.
- The plane of the fingernails should be parallel on the injured and normal hand.
Function of the flexor and extensor tendons must be documented.

Diagnostic Tests & Interpretation

Imaging

Radiographic evaluation with 3 views is mandatory because many fractures are overlooked or misinterpreted.
Standard anteroposterior and lateral views: Pronation of 10–30° in lateral view facilitates view of the second and third metacarpals; supination of 10–30° aids in viewing the ring and small fingers.
Oblique views allow better visualization of intra-articular fractures, spiral fractures, and epiphyseal plate injuries.
Robert view with the hand in maximal pronation is helpful for differentiating between intra-articular and extra-articular fractures, as it allows for visualizing intra-articular extension of an epibasilar fracture.
Tomograms or computed axial tomographic scans help define CMC relationships, and are of benefit for defining comminuted intra-articular fractures (1).
Malrotation should be suspected if there is metacarpal shortening or a discrepancy in the shaft diameter.

Differential Diagnosis

Metacarpal head and neck fractures
Metacarpophalangeal collateral ligament injuries
Carpometacarpal fracture dislocation

Treatment

Once thorough neurovascular examination is complete, wrist or hematoma block may facilitate reduction.
Fractures amenable to closed manipulative reduction are transverse fractures, isolated spiral/oblique fractures with <3 mm of shortening, and extra-articular fractures of the thumb.
Closed reduction of metacarpal shaft fractures is performed with longitudinal traction, dorsal pressure at the fracture site, and rotation as needed.
Closed reduction of extra-articular base fractures typically require only longitudinal traction.
Postreduction films are mandatory. Limits of angular deformity depend on mobility of different metacarpals at base: <10° for 2nd and 3rd metacarpals; <20° for 4th and 5th metacarpals; <25° of both angulation and rotation are acceptable for the thumb.
Orthopedic referral is required if satisfactory reduction cannot be performed or maintained.
Radiographs should be repeated 1 wk after injury to reevaluate for angulation, rotation, and shortening.
Dorsal and volar splints must include all metacarpal shafts and wrist while avoiding immobilization of the metacarpophalangeal joint. Splint should be left in place for 3–4 wks (1)[B].
Ulnar gutter splint for 3–4 wks for extra-articular metacarpal base fractures if ring and/or little finger(s) are involved.
Volar or radial gutter for 3–4 wks for extra-articular metacarpal base fractures of index and long finger

P.219

Functional brace (Galveston) if fracture requires significant reduction
Thumb spica cast for extra-articular fractures of the thumb for 4–6 wks
Bulky compressive dressing for unstable fractures
Closed reduction with local block or conscious sedation and immobilization is generally effective for children (1)[B].
Referral is needed for unstable or unsatisfactory reductions in children.
Long oblique and spiral fractures typically require closed reduction and percutaneous pinning in children (1)[B].
Fractures involving the physis and epiphysis are uncommon in children:
- Usually Salter type II, which almost always are treatable with closed reduction and immobilization
- Salter type III fractures are rare. These require open reduction, since osteonecrosis of the metacarpal head can result if inadequately reduced.
Children can be immobilized longer due to additional flexibility.

Additional Treatment

Referral

Any rotational deformity
>3 mm of shortening
>10° angulation for 2nd and 3rd metacarpals; >20° angulation for 4th and 5th metacarpals; >25° angulation of the thumb
Intra-articular base fractures
Inability to perform or maintain satisfactory closed reduction
All surgical cases, including special situations such as multiple fractures, nerve or tendon injury, and open fractures

Additional Therapies

Field management: Splint immobilization provides comfort and minimizes soft tissue injury.
Ice packs should be used proximal to the metacarpals to prevent digital injuries.
Active motion as soon as 3–4 wks for fractures treated with immobilization and closed reduction
Buddy taping may provide stability when mobilization begins.
Clinical union is manifest by absence of tenderness at the fracture site with palpation and range of motion. Radiographic union will lag behind clinical union by several weeks.

Surgery/Other Procedures

Open reduction internal fixation or closed reduction with percutaneous pinning is advocated for patients with malunion or unstable fractures (Bennett, Rolando, comminuted, intra-articular, spiral/oblique with shortening and rotation).

Ongoing Care

Follow-Up Recommendations

Follow up 1 wk after injury with radiographs to evaluate for angulation, rotation, and shortening.
Splint should remain in place for 3–4 wks.
Rehabilitation should be delayed until 3–4 wks post injury for distal metacarpal shaft fractures (2).
Both active and passive range of motion (ROM) at interphalangeal joints can be started immediately for metacarpal base and proximal shaft fractures (2).
Gentle active ROM at the MCP joint is allowed in most proximal stable shaft fractures 3–4 wks after injury (2).
Passive ROM at MCP joint can be added when there are signs of clinical union, usually 5–6 wks after the injury (2).
Strengthening exercises should be added at 8 wks (2).

Complications

Stiffness can develop after prolonged immobilization or delayed rehabilitation.
Chronic CMC joint stiffness is associated with intra-articular fractures.
Malunion usually manifests as malrotation or dorsal angulation, so confirm that the patient's fingertips point toward the scaphoid tuberosity in flexion at each visit:
- 5 degrees of malrotation can result in 1.5 cm of digital overlap and cause a decrease in grip strength.
Nonunion is uncommon in metacarpal fractures.

References

1. Chin SH, Vedder NB. MOC-PSSM CME article: metacarpal fractures. Plast Reconstr Surg. 2008;121:1–13.

2. Weinstein L, Hanel D. Metacarpal fractures. J Am Soc Surg Hand. 2002;2(4):168–180.

Additional Reading

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

Harrison BP, Hilliard MW. Emergency department evaluation and treatment of hand injuries. Emerg Med Clin North Am. 1999;17:793–822.

Lyn E, Antosia R. Chapter 47: Hand. Marx: Rosen's emergency medicine: concepts and clinical practice, 6th ed. Philadelphia: Mosby, 2006.

Mastey RD, Weiss AP, Akelman E. Primary care of hand and wrist athletic injuries. Clin Sports Med. 1997;16:705–724.

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

Simon RR, Koenigsknecht SJ, eds. Emergency orthopedics. Stamford, CT: Appleton Lange, 1996.

Codes

ICD9

815.00 Closed fracture of metacarpal bone(s), site unspecified
815.01 Closed fracture of base of thumb (first) metacarpal
815.02 Closed fracture of base of other metacarpal bone(s)