Fracture - Bennet's fracture dislocation & Rolando fracture and other thumb fractures

Bennett's fracture

This is an oblique fracture of the base of the first metacarpal (the thumb) with associated subluxation and fracture of the carpometacarpal articular surfaces. It is the most common fracture to affect the thumb and is a serious injury.[2]

It is an intra-articular fracture subluxation and failure to treat it quickly and appropriately can lead to much disability through disruption of the pinching and opposition functions of the thumb.[3]

Mechanism of injury

• • Bennett's fracture usually occurs due to an axial blow on a partially-flexed first metacarpal, such as would occur during delivery of a punch with a clenched fist.[2]

  • The volar fracture fragment on the ulnar aspect of the metacarpal base is held firmly in place by the volar anterior oblique ligament, whilst the traction of the abductor pollicis longus muscle tendon pulls the distal metacarpal fragment (containing most of the articular surface) proximally, radially and dorsally.[2]

Presentation[3]

• • Acute, severe pain and swelling at the base of the thumb, with grossly reduced movement at the first carpometacarpal joint.

  • Instability at the carpometacarpal joint may be noted with gentle stressing of the thumb metacarpal.

Radiology

• • Posteroanterior, lateral and oblique views should be taken in the assessment of thumb fractures and injuries.[3]

  • There is a classical oblique fracture line at the base of the first metacarpal with a triangular fragment at the ulnar base of the metacarpal. This fragment remains attached to the trapezium and there is proximal displacement of the metacarpal.[2]

Management[2][3]

• • Small avulsion fractures with minimal articular disruption and minimal instability may be treated by closed reduction and, if the reduction is maintained, placement in a thumb spica cast for six weeks or so.[3] Reduction is achieved through longitudinal traction on the thumb with metacarpal extension, pronation and abduction.

  • However, most cases will require surgical intervention, either through closed reduction and percutaneous placement of K-wires, or open reduction and internal fixation using K-wires and/or screws.

  • After operative intervention, splinting in a thumb spica cast for 2-6 weeks is necessary, depending on the degree of stability obtained during surgery.

  • Subsequent immobilisation in a thermoplastic splint is used to allow gradual mobilisation until healing is complete.

Complications[3]

• • Osteoarthritis of the thumb carpometacarpal joint as a result of osteocartilaginous injury, even if joint congruity and fragment reduction are achieved.

  • Reduced movement at the carpometacarpal joint due to prolonged immobilisation.

  • Recurrent joint subluxation/instability.

  • Postoperative infection of skin/carpometacarpal joint/osteomyelitis.

  • Dorsal sensory branches of radial nerve injury causing anaesthesia.

Other thumb injuries and fractures

Rolando's fracture

• • This is a 3-part fracture at the base of the thumb metacarpal.

  • There is the same fracture of the metacarpal as in Bennett's fracture but, as well as this, there is a large dorsal fragment, resulting in a comminuted Y- or T-shaped intra-articular fracture at the base of the thumb metacarpal.[4] Essentially the three fragments of the fracture are: metacarpal shaft, dorsal metacarpal base, and volar metacarpal base.[1] However, Rolando's fracture has come to be used to describe all comminuted thumb metacarpal base fractures.[1]

  • It is a relatively uncommon fracture but carries a worse prognosis than Bennett's fracture.[4]

  • The mechanism of injury is a significant axial load that splits and crushes the metacarpal articular surface.[1]

  • Presentation can be with a swollen, tender, visibly deformed thumb base.[1]

  • Anteroposterior and lateral X-rays may not show the full extent of comminution and so a Robert view (a hyperpronated view of the thumb base) or CT scanning may be needed.[1]

  • Highly comminuted fractures are sometimes treated conservatively in a thumb spica cast for 3-4 weeks with gradual mobilisation after that time but external fixation and bone grafting may also be used.[1][4]

  • Reduction of large volar and dorsal fragments and reconstruction of the articular surface may be carried out using open reduction and internal fixation with K-wires/screws.[4]

  • Complications can include infection, nerve damage and joint stiffness.[1]

Metacarpal head/shaft fractures

• • These are relatively rare and caused by direct impact to the mid-thumb.

  • They may require closed reduction and fixation with K-wires if significant displacement/angulation, but are often managed conservatively with thumb spica splinting.

Fractures of thumb phalanges[5]

• • Proximal phalanx fractures are fractures of the phalangeal head and shaft.

  • Distal phalanx fractures may occur as:

• • Usually treated conservatively, depending on the degree of injury/displacement; the nail may need trephination if there is significant subungual haematoma. Tendon avulsion injuries may require reconstructive surgery.

Thumb dislocations[6]

• • These may affect the interphalangeal joint (the thumb has only two phalanges) or the metacarpophalangeal (MCP) joint.

  • MCP dislocation:

• • Interphalangeal dislocation:

Mallet thumb[5]

• • There is avulsion of the extensor tendon causing the thumb to be stuck in moderate flexion. Bony fragments may be present.

  • It usually occurs due to forceful flexion of the interphalangeal joint.

  • An open mallet thumb can be caused by laceration causing tendon disruption.

  • Closed mallet thumb can be treated by conservative splinting but may require open tendon repair or fixation of avulsed bone.

Gamekeeper's thumb (skier's/ski-pole thumb)

• • This is injury to the ulnar collateral ligament (UCL) of the MCP joint (on the medial side of the thumb) due to forced abduction of the MCP.[7]

  • The ligament can be torn partially or fully and there can be an associated avulsion fracture of the volar base of the proximal phalanx.[7][8]

  • Gamekeepers suffered chronic injury due to wringing the necks of game between their thumb and index finger.[8]

  • Nowadays this is a much more common injury in skiers who fall against the ski-pole/strap or ground while the thumb is abducted, and so it is seen as an acute injury. It is the most common upper limb injury in skiers.[8] It may also be seen in sportspeople who play with balls (eg basketball, netball) and in those who hold sticks (eg hockey, lacrosse).[8]

  • The thumb is hyperextended and laterally deviated with swelling and bruising over the joint. Pain is experienced over the ulnar side of the MCP joint.[8] Grasp and pinching ability may be reduced.[8]

  • Adequate treatment is important so that pinch grip can be maintained.[7]

  • Splint and apply ice for first aid whilst transferring to receive medical attention. X-ray should be performed to exclude associated fracture if there is tenderness over the UCL.[7]

  • If a fracture has been excluded, evaluate the stability of the ligament by applying abducting pressure to one side of the UCL while applying counterpressure to the other side. Compare to the uninjured hand.[7]

  • Referral to a hand specialist may be necessary for a decision on the need for surgery, depending on the degree of disruption of ligament and associated damage.

  • If there is joint instability and a tender mass palpable, there may be a Stener lesion present. This is when the proximal end of the UCL is trapped outside the adductor aponeurosis of the thumb. Surgery by a hand surgeon is required.[7]

• If there is just incomplete ligamental injury and the joint is stable, treatment can be immobilisation in a thumb spica splint for 4-6 weeks.[7][8] Otherwise, surgical repair is usually indicated.

  • Complications include osteoarthritis of the MCP joint. However, correct and prompt treatment carries a good prognosis with regards to return to normal function.[8]

Complications of traumatic thumb injuries

• • Post-traumatic arthritis.

  • Bony malunion.

  • Chronic ligamentous damage and instability.

  • Vascular injury.

  • Neurological injury.

Bennett fractures

Closed reduction and thumb spica cast immobilization are effective in the treatment of Bennett fractures if the reduction can be maintained. The closed reduction technique consists of thumb traction combined with metacarpal extension, pronation, and abduction. Direct downward pressure is applied to the dorsal radial metacarpal base. The strong pull of the APL frequently leads to displacement, necessitating open reduction and internal fixation or closed reduction with percutaneous pinning. More than 1 mm of articular incongruity or persistent CMC joint subluxation after closed reduction indicates the need for surgical treatment.^{[2, 3, 5, 9, 10, 11]}

Surgical Therapy

Generally, closed reduction utilizing the technique described above followed by percutaneous K-wire fixation is successful. Two 0.045-inch K-wires are drilled through the dorsal radial thumb metacarpal base into the reduced volar ulnar fragment. If the fragment is very small, reduction may be maintained by placing the K-wire from the thumb metacarpal into the trapezium or the index metacarpal. Maintaining thumb abduction is essential to preserving the first web space.^[12]

If adequate reduction cannot be achieved utilizing this percutaneous technique, open reduction and internal fixation is performed. An L-shaped incision is made over the subcutaneous border of the thumb metacarpal. The incision is carried down radially to allow for subperiosteal reflection of the thenar musculature and direct visualization of the joint. Towel-clip forceps are extremely valuable in obtaining and temporarily maintaining reduction. Fixation is achieved using either K-wires or mini screws (2.0 mm).^{[2, 3, 5, 9, 10, 13, 14]}

Zhang et al reported success with open tension band wiring as a fixation option for the treatment of Bennett fractures.^[15] Mahmoud et al reported good results from performing open reduction and internal fixation (ORIF) of Bennett fractures in young, active manual laborers, using a K-wire and wire loop construct to achieve anatomic reduction.^[16]

Postoperative Details

Fluoroscopy was found to often provide erroneous results, compared with plain radiographs and direct examination, in cases of Bennett fracture after closed reduction and percutaneous pinning, according to Capo et al in a study of simulated Bennett fracture in cadavers. This is an important issue, the authors stated, because fluoroscopic examination is often used to determine the adequacy of closed reduction after pinning of Bennett fracture. The assessment of the articular gap, stepoff, and displacement as detected by fluoroscopy is often in error, according to the authors, compared to that detected by plain radiographs and direct examination. The authors noted that restoration of joint congruity is an important factor in the prevention of arthritis in patients with Bennett fracture and that therefore surgical management is generally recommended for displaced intra-articular fractures of the base of the thumb metacarpal.^[11]

Follow-up

A well-molded thumb spica cast is utilized for 2-6 weeks depending on the stability obtained at surgery. Once the cast is discontinued, a thermoplastic splint is fabricated and a protected mobilization program is initiated until fracture healing is complete.

Complications

Displaced intra-articular fractures predispose the patient to arthritis and loss of motion within the affected joints. Unfortunately, even after restoration of articular congruity, some patients develop posttraumatic arthritis secondary to the osteocartilaginous injury sustained as a result of the initial trauma.

Loss of motion also occurs following prolonged immobilization. Rigid fixation enables patients to initiate movement sooner postoperatively, minimizing this problem.

Other potential postoperative complications include loss of reduction with recurrent joint subluxation and instability, infection, and sensory nerve injury.

Outcome and Prognosis

The prognosis for Bennett fractures is most closely related to the amount of energy associated with the original injury. High-energy injuries produce comminution, articular surface damage, and extensive soft-tissue injury, leading to a poor outcome. With anatomic restoration of the joint surface and reestablishment of stability, the outcome is routinely good, especially in low-energy injuries with simple fracture patterns and limited soft-tissue involvement.

http://emedicine.medscape.com/article/1238036-treatment#showall

Further reading & references

• 1. Walsh JJ, Rolando Fracture, Medscape, Feb 2009

  2. Bennett's Fracture Dislocation; Bennett's Fracture Dislocation, Wheeless' Textbook of Orthopaedics

  3. Priano SV et al, Bennett Fracture, Medscape, Apr 2010

  4. Rolando's Fracture; Rolando's Fracture, Wheeless' Textbook of Orthopaedics

  5. Laub Jr DR et al, Thumb Fractures and Dislocations, Medscape, Sep 2010

  6. Dislocations of the Thumb MP Joint, Wheeless' Textbook of Orthopaedics

  7. Leggit JC, Meko CJ; Acute finger injuries: part II. Fractures, dislocations, and thumb injuries. Am Fam Physician. 2006 Mar 1;73(5):827-34.

  8. Foye PM et al, Skier's Thumb, Medscape, Aug 2010