Metacarpal Fractures

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Introduction

Hand fractures are common in the general population with relative propensity seen in contact-sport athletes (For example, boxers, football players) and manual laborers

A metacarpal fracture

• Is a break in one of the five metacarpal bones of either hand.
• Are categorized as being fractures of the head, neck, shaft, and base (from distal at the metacarpal phalangeal joint to proximal
• at the wrist). 
• Boxer fracture is another name for a fracture of the fourth or fifth metacarpal, one of the most common metacarpal fractures.
• The mechanisms of these injuries vary from axial loading forces to direct blows to the dorsal hand
  

Clinically Relevant Anatomy

The metacarpals are long, thin bones that are located between the carpal bones in the wrist and the phalanges in the digits.

• Each is comprised of a base, shaft, and head.
• The proximal bases of the metacarpals articulate with the carpal bones,
• Distal heads of the metacarpals articulate with the proximal phalanges and form the knuckles.
• The 1st metacarpal is the thickest and shortest of these bones.
• The 3rd metacarpal is distinguished by a styloid process on the lateral side of its base.
• Soft tissues generally involved with fractures include cartilage, joint capsule, ligaments, fascia, and the dorsal hood fibers.
• With severe polytrauma cases, the tendons and nerves adjacent to the fracture can also be injured. 

Etiology

Metacarpal fractures typically occur secondary to a direct blow or fall directly onto the hand. 

• These fractures commonly occur during athletic activities, particularly in contact sports. Almost one-fourth of cases occur during athletic events.
• Sporting injury is frequently the cause among younger patients
• Work-related injuries are often the cause in middle-aged patients
• Falls are typically the cause of the elderly.
• Fifth metacarpal fractures often occur secondary to punching a wall or other solid object (hence the eponym, "boxer's fracture")

Hand Fractures

• Makeup about 40% of all acute hand injuries
• Constitute about 20% of all fractures occurring below the elbow

Metacarpal Fractures

• Typically occur in patients aged 10-40 years
• Men are more likely to be affected than women. 
• Young men sustain metacarpal fractures secondary to a punching mechanism or a direct blow to the hand
• Geriatric females sustain these injuries secondary to a low energy fall. 
• The incidence rate of fracture seen in association with each digit's metacarpal bone increases from the radial to the ulnar side.
• The incidence rate of 2nd metacarpal fractures is lower than the incidence rate of 5th metacarpal fractures.
• Bennett fracture is the most common fracture involving the base of the thumb. This fracture refers to an intra-articular fracture that separates the palmar ulnar aspect of the first metacarpal base from the remaining first metacarpal.

The fractures of the metacarpals can be divided into three parts.

1. The first, neck fractures, occurs often when a person punches another person or object. In the majority of cases, surgical intervention is not essential to treat this condition.
2. The metacarpal shaft fractures are often produced by longitudinal compression, torsion, or direct impact. They are described by the appearance of their respective fracture patterns and can be divided by transverse, oblique, spiral, and comminuted.
3. Metacarpal base fractures are rare and have a minimal consequence because the motion of the joint is small. More common are the fractures of the base of the fifth digit and are the result of a longitudinally directed force 

Characteristics/Clinical Presentation

Patients with metacarpal fractures generally present with

• Pain
• Swelling
• Ecchymosis (bruise)
• Limitation of movement
• Deformity - Knuckle asymmetry may be observed, and the knuckle may appear to be missing.
• Finger misalignment may also be noted.
• A metacarpal head fracture is associated with axial compression of the extended digit which causes severe discomfort.
• In a metacarpal base fracture, movement of the wrist or longitudinal compression exacerbates the pain.
• Any metacarpal fracture angulation can produce a pseudo-claw deformity.

Differential Diagnosis

Injuries to neighboring bones (carpal bones, phalanges) and associated soft tissues (ligaments, tendons) need to be excluded.

Evaluation

The evaluation includes:

• Standard radiographs of the hand (antero-posterior, lateral, and oblique). In the vast majority of cases, this will be enough to confirm the diagnosis and form a management plan. Confirmation of more subtle injuries can be obtained using special views such as Brewerton (metacarpal heads), Roberts, and Betts (thumb) views.
• CT is sometimes necessary for the base of metacarpal fractures to check for any intra-articular displacement and determine if there is a need for surgery

Outcome Measures

• Grip Strength: measured with a dynamometer
• Range of motion
• Patient Specific Functional Scale
• DASH
• Michigan Hand Outcome Questionnaire (MHO): In this questionnaire, they assess 6 criteria for people with a hand disorder: overall hand function, activities of daily living (ADL), pain, work performance, aesthetics, and patient satisfaction with hand function.

Medical Management

The goal of treatment is a restoration of anatomy and function.

• Antibiotics and tetanus prophylaxis are options for open fractures as per standardized guidelines.
• The modality of treatment will vary depending on skin integrity (open versus closed fracture), the number of digits/metacarpals fractured, the stability of the specific, degree of comminution, displacement, and/or rotational malalignment
• In general, increasing degrees of displacement, comminution, and rotational malalignment are critical factors in assessing the fracture patterns potential for stability and reduction maintenance with non-operative management.
• The GP/Specialist after assessing the fracture will perform gentle tests and imaging to work out if surgery is needed.
• If surgery is not needed a physiotherapist will make a custom splint, which will support the healing fracture.

Physical Therapy Management

Full strength and range of motion is the goal of rehabilitation.

Under the physiotherapist’s instructions

• Hand exercises with light resistance such as rubber bands or squeeze ball can help if there is scarring or extensor lag develops.
• Soft tissue recovery may be more of a problem than the bony one.
• Rest and elevation are important, and so is the quality of splinting - poor splinting can cause stiffness, pressure sores, or even compartment syndrome

Physiotherapists use a number of techniques to regain movement in the hand, wrist, and fingers, including:

• Swelling management with massage and compression garments
• Soft tissue massage to help with muscle tension and pain
• Providing clients with a home exercise program of specific movements and strengthening exercises.

Most hand fractures can be treated non-operatively   This very informative 4 minute video gives a basic run done on Physio treatment

More specific Advice.

These are the steps to be followed in a stable fracture:

One or other of the below stabilizing techniques could be used :-

• Buddy strapping the injured digit to another digit is used as a non-operative technique. This is used with or without the application of varying degrees of splint. The ‘buddy’ reduces the risk of rotational deformity.
• The splinting of the fracture should be: 20 degrees wrist extension; MCP joint 60-70 degree flexion and IP joint extension

• Early motion is generally considered appropriate when there are stable fractures or rigid fractures.
• Generally, AROM (active ROM) exercises without resistance can begin 2 to 3 weeks after operative treatment in uninvolved or bordering/adjacent joints.  
• Active Motion: If the fracture is internally fixed, the active range of motion can start early. Most fractures are treated by immobilization, but the active motion can begin after three weeks of therapy, starting with the joints not splintered during the initial immobilization. This phase usually lasts 3-6 weeks.  
• Specific tendon gliding should be included in the active motion.
• Tendon gliding is important to prevent adhesions, increased circulation about the fracture site, decreased edema and compression at the fracture site.
  

Exercises For Tendon Gliding 

• Claw posture to achieve extensor digitorum communis tendon glide over the metacarpal bone
• Intrinsic plus posture to achieve central slip. Lateral bands glide over proximal phalanx 1
• Flexor Digitorum Profundus (FDP) blocking exercises to glide FDP tendon over the phalanx
• Hook fist posture to promote selective FDP tendon glide
• Flexor Digitorum Superficialis (Sublimis) blocking exercise to glide FDS tendon over middle phalanx
• Sublimis fist posture to promote selective FDS tendon glide
  

Passive Motion

• Passive motion can be initiated after sufficient clinical healing at approximately 5-6 weeks of therapy.   
• The timing of initiation of joint mobilization depends on the structures involved in the injury. If the structures resisting the force are not involved in the injury, joint mobilization can be initiated at the same time as active motion. Compression on the fracture can result in shortening, angulation or rotational mal-alignment of the bone.
• Traditional PROM aims to assist in articular cartilage healing, reduce swelling, and stiffness.  
• Resistive Motion: Four weeks after the injury light resistance can be performed in most metacarpal fractures which are treated by immobilization. Active motion should only be continued if healing has not started.
• Resistive exercise should also be delayed when a fracture is fixed by pinning until these pins are removed, to ensure the stability of the fracture. Light resistive exercise helps with scar remodeling and improved motion. There are several types of resistive exercises such as the weight-well exercises. This kind of exercise strengthens the finger flexors (FDP and FDS muscles).
• Functional activities and work simulation should be included in the resistive exercises as soon as possible.

Conclusion

Main points on metacarpal fractures:

• Common hand injury
• Require thorough assessment consisting of the history, examination, and radiological investigations
• They mostly divide into open or closed, based on the digit they affect, intra-articular or extra-articular status, and based on the location on the bone itself (head, neck, shaft, base)
• May have conservative or operative treatment
• Can have long-term sequelae requiring further management
• Rehabilitation goals are return of full strength and range of motion.
• Rest and elevation are important, and so is the quality of splinting - poor splinting can cause stiffness, pressure sores, or even compartment syndrome.
• Physiotherapy is an critical element in the restoration of good hand function