Overview
Definition:
A Boxer's fracture is a fracture of the fifth metacarpal bone, typically resulting from a direct blow to the hand, such as punching an object
In pediatric patients, the mechanism often involves falls or sports-related injuries
The ulnar gutter splint is a common and effective immobilization method for these injuries, providing stability to the affected metacarpal and digits.
Epidemiology:
Metacarpal fractures are common in children and adolescents, accounting for approximately 10-30% of all hand fractures
The fifth metacarpal is the most frequently fractured metacarpal bone due to its prominent position and susceptibility to direct impact
While direct fist-fighting is less common in younger children, falls onto an outstretched hand or impact during play are significant etiologies.
Clinical Significance:
Accurate diagnosis and appropriate management of pediatric Boxer's fractures are crucial to ensure proper healing, prevent long-term functional impairment of the hand, and avoid complications such as malunion, nonunion, or stiffness
Ulnar gutter splinting is a cornerstone of conservative management, offering pain relief and promoting optimal bone alignment
Understanding this topic is vital for pediatric residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Pain at the base of the fifth finger
Swelling of the affected hand and finger
Bruising (ecchymosis) over the dorsal aspect of the hand
Difficulty moving the affected finger
A palpable deformity or step-off at the metacarpophalangeal (MCP) joint
Tenderness to palpation over the fifth metacarpal.
Signs:
Visible swelling and ecchymosis of the dorsal aspect of the hand and little finger
Tenderness and pain on palpation along the fifth metacarpal
Loss of the normal knuckle contour of the fifth metacarpal
Possible dorsal angulation or displacement of the distal fragment
Assessment of neurovascular status is critical, checking for sensation in the ulnar nerve distribution and capillary refill in the fingertip.
Diagnostic Criteria:
Diagnosis is primarily based on a thorough clinical examination and radiographic evidence
Radiographic findings typically include a fracture line within the shaft or neck of the fifth metacarpal, often with dorsal angulation
Displacement and shortening are also assessed
The degree of angulation, usually measured on the anteroposterior (AP) and lateral views, guides management decisions, with specific acceptable ranges for children before surgical intervention is considered.
Diagnostic Approach
History Taking:
Mechanism of injury: Direct blow, fall, sports injury
Time of injury
Presence of any associated injuries
Previous hand injuries or medical conditions
Allergies to medications or materials used in splinting
Pain assessment using a pediatric pain scale.
Physical Examination:
Inspect the hand for swelling, bruising, lacerations, and deformities
Palpate the entire hand, focusing on the metacarpals and phalanges, to identify tenderness and crepitus
Assess range of motion of the MCP, PIP, and DIP joints of all fingers, noting any limitations
Perform a complete neurovascular assessment of the hand and fingers, including sensation and motor function
Evaluate the integrity of tendons and ligaments
Assess for rotational deformities.
Investigations:
Standard radiographic views of the hand are essential, including anteroposterior (AP), lateral, and oblique views
The lateral view is particularly important for assessing dorsal angulation of the metacarpal neck
Comparison views of the uninjured hand may be useful in some cases, especially if there is suspicion of epiphyseal injury
In complex or open fractures, further imaging like CT may be considered
Laboratory investigations are typically not required for uncomplicated Boxer's fractures.
Differential Diagnosis:
Physeal fractures of the fifth metacarpal (Salter-Harris classifications)
Fractures of the proximal phalanx or hamate bone
Soft tissue injuries to the hand
Contusions and sprains
Other metacarpal fractures
Epiphyseolysis of the distal ulnar physis.
Management
Initial Management:
Pain control with appropriate analgesics (e.g., acetaminophen or ibuprofen)
Immobilization with a temporary splint to reduce pain and prevent further injury
Ice application to reduce swelling
Elevation of the hand to minimize edema
Reduction of any significant deformity under local or conscious sedation if indicated and feasible prior to definitive splinting
Thorough assessment and management of any open wounds or neurovascular deficits.
Splinting Technique:
The ulnar gutter splint is a common choice for Boxer's fractures
It typically extends from the mid-forearm down to the distal palmar crease, immobilizing the fifth (and sometimes fourth) metacarpal and finger in a functional position
Materials include plaster of Paris or fiberglass rolls, and padding
The splint should support the metacarpal head and neck, and maintain the MCP joint in slight flexion (approximately 70-90 degrees) to prevent stiffness, with the PIP and DIP joints free
Ensure the splint does not restrict the motion of the uninvolved fingers
Proper padding is crucial to prevent pressure sores
For pediatric patients, careful assessment of fit and comfort is paramount.
Indications For Reduction And Surgery:
Significant displacement or angulation (typically >30-40 degrees in pediatric metacarpal fractures, but specific acceptable ranges may vary with age and metacarpal involved)
Intra-articular extension of the fracture
Open fractures
Neurovascular compromise
Irreducible dislocations associated with the fracture
Multiple associated hand fractures
Unstable fractures
Failure of conservative management.
Post Splinting Care:
Educate the child and caregivers on splint care: keeping it dry, avoiding insertion of objects, and reporting any signs of tightness, increased pain, numbness, tingling, or skin breakdown
Regular follow-up appointments are essential to monitor healing and assess for complications
Activity modification to avoid re-injury.
Complications
Early Complications:
Compartment syndrome of the hand
Neurovascular injury
Skin irritation or pressure sores from the splint
Infection, particularly in open fractures
Excessive swelling or pain.
Late Complications:
Malunion or nonunion of the fracture
Joint stiffness, especially at the MCP joint if immobilized improperly
Chronic pain or hypersensitivity
Boutonniere or swan-neck deformities if extensor tendon function is affected
Cold intolerance or sympathetic dystrophy (less common).
Prevention Strategies:
Accurate fracture reduction before splinting
Appropriate splinting technique that maintains functional position and avoids constrictive pressure
Regular monitoring for neurovascular compromise and compartment syndrome
Patient and caregiver education regarding splint care and warning signs
Early mobilization of uninvolved digits
Prompt surgical intervention when indicated.
Prognosis
Factors Affecting Prognosis:
Severity of the initial injury
Degree of displacement and angulation
Promptness and appropriateness of treatment
Presence of associated injuries or complications
Patient compliance with treatment and follow-up instructions
Age of the child and their healing potential.
Outcomes:
With appropriate management, most pediatric Boxer's fractures treated with ulnar gutter splinting have an excellent prognosis, with complete healing and return to normal function
Residual mild angulation may be well-tolerated and remodel over time in younger patients
Significant residual deformities or complications can lead to long-term functional deficits.
Follow Up:
Follow-up typically involves serial radiographic examinations to assess fracture healing and union (e.g., at 1-2 weeks, 4-6 weeks)
Clinical assessment for pain, swelling, and range of motion is performed at each visit
Once radiographic union is evident, the splint is removed, and a physiotherapy program focusing on regaining full range of motion and strength is initiated
Duration of immobilization is typically 4-6 weeks, depending on the individual healing rate.
Key Points
Exam Focus:
Remember that pediatric metacarpal fractures often have higher acceptable angulation for non-operative management compared to adults
The ulnar gutter splint immobilizes the 4th and 5th metacarpals and provides support
Pay close attention to the MCP joint position during splinting (slight flexion)
Always assess neurovascular status before and after splinting
Open fractures require immediate surgical management and antibiotics.
Clinical Pearls:
For young children, a well-padded and smooth splint is crucial for comfort and compliance
Educate parents on recognizing signs of splint complications, as children may not articulate their discomfort well
Consider wrist involvement if pain or swelling extends beyond the metacarpals
Early mobilization of the thumb and uninvolved fingers is key to preventing stiffness.
Common Mistakes:
Improper reduction leading to malunion
Over-tight splint causing neurovascular compromise or skin breakdown
Immobilizing the MCP joint in full extension, which can lead to stiffness
Neglecting to assess for rotational deformities
Inadequate follow-up, leading to missed complications or delayed rehabilitation
Treating closed, non-displaced fractures of the fifth metacarpal neck as simple contusions without adequate imaging.