Both-Bone Forearm Fracture

Both bone forearm fracture is a fracture of the radius and ulna shafts. In children the forearm is the most common site of fracture, with shaft fractures a minority (about 6 to 10%) of paediatric forearm fractures. In adults it follows high energy injury (road traffic collision, fall from height, sport), and open fractures are more frequent.

Paediatric patterns are plastic deformation, greenstick and complete fractures. Complications are refracture after greenstick injury, malunion with loss of rotation, compartment syndrome (uncommon but under recognised), nonunion (more common in adults), radioulnar synostosis, nerve injury and infection after plating.

Acceptable alignment depends on age and remodelling potential. Under 8 years: up to 15 degrees of angulation, up to 45 degrees of malrotation, and bayonet apposition. From 9 years: up to 10 degrees of angulation, up to 30 degrees of malrotation, and at least 50% apposition. Any bayonet apposition and a pronounced rotational block are unacceptable in adults, who need anatomical reduction.

Pathophysiology.

The radius and ulna act as a ring with the proximal and distal radioulnar joints, so a shaft fracture of both bones shortens or rotates the forearm. The radial bow is essential for rotation, and loss of the bow or malunion limits pronation and supination.

Children's thick periosteum helps hold reduction, but high energy fractures with loss of the periosteal sleeve are unstable.

Pain, swelling and deformity of the forearm, with loss of rotation, and sometimes an open wound or skin tenting. Examine the elbow and wrist. Test the median, anterior interosseous, ulnar and radial nerves, check pulses, and examine the forearm compartments (tense swelling, pain on passive finger stretch, escalating analgesic need).

Ask about mechanism and the possibility of non-accidental injury in young children.

• Radiographs of the full forearm, anteroposterior and lateral, including the elbow and wrist. Check the radiocapitellar line and the distal radioulnar joint to exclude Monteggia and Galeazzi injuries.
• Look at the bicipital tuberosity and the radial styloid for rotation. Measure the angulation of each bone.
• CT for complex or intra-articular extension, and the cast index (sagittal over coronal width at the fracture) when casting a child. A cast index of 0.8 or under predicts maintained reduction.
• Wound inspection and Gustilo grading when open.

Differential diagnosis.

• Monteggia fracture dislocation and Galeazzi fracture dislocation.
• Plastic deformation of one bone with a fracture of the other.
• Isolated radial or ulnar shaft fracture.
• Essex-Lopresti injury and pathological fracture.

Children.

• Closed reduction under sedation or anaesthesia with an long arm cast moulded to keep the interosseous space, for 6 to 8 weeks. Radiographs at 1 and 2 weeks to catch redisplacement.
• Unstable, failed or irreducible fractures, and older children: intramedullary elastic nailing of both bones (2.0 to 2.5 mm titanium nails), or plating in adolescents near maturity. Nails are removed at 6 to 12 months.
• Open fractures: urgent debridement and stabilisation with the antibiotic regimen given under open injury.

Adults. Open reduction and internal fixation of both bones with 3.5 mm compression plates, restoring length, alignment and radial bow. Bone graft for comminution or bone loss. Closed treatment fails in adults. Start movement at once when fixation is stable.

Open injury. Intravenous co-amoxiclav 1.2 g every 8 hours (or cefazolin 2 g every 8 hours) within 1 hour of injury, continued until 24 hours after wound closure for types I and II and until 72 hours or 24 hours after soft tissue cover (whichever is earlier) for type III (maximum 3.6 g co-amoxiclav daily; every 12 hours at creatinine clearance 10 to 30 mL/min; check liver tests in courses over 7 days).

For heavy contamination or soft tissue loss add gentamicin 5 mg/kg intravenously once daily for up to 72 hours (creatinine daily, level before the second dose, avoid or extend the interval at eGFR under 60 mL/min/1.73 m2).

With severe penicillin allergy use clindamycin 600 mg intravenously every 8 hours (maximum 2.7 g daily) with gentamicin.

Children: co-amoxiclav 30 mg/kg intravenously every 8 hours (maximum 1.2 g a dose) and gentamicin 7 mg/kg once daily (5 mg/kg from 12 years).

Tetanus booster 0.5 mL intramuscularly if the last dose was over 10 years ago, with tetanus immunoglobulin 250 units intramuscularly (500 units if over 24 hours since injury or heavily contaminated) when immunisation is incomplete or unknown.

Debride and stabilise within 24 hours (within 12 hours for gross contamination).

Compartment syndrome. Fasciotomy of the volar and dorsal compartments without delay.

Analgesia.

• Adults:
  • Paracetamol 1 g orally every 6 hours for up to 5 to 7 days (maximum 4 g daily; 3 g daily when weight is under 50 kg or in hepatic impairment).
  • Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily; avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer or anticoagulant use).
  • Oral morphine 5 to 10 mg every 4 hours as needed for up to 3 days (start 2.5 to 5 mg with age over 75 or eGFR under 30; avoid exceeding 60 mg in 24 hours without senior review), with monitoring of sedation and respiration and a laxative.
• Children: paracetamol 15 mg/kg orally every 4 to 6 hours (maximum 75 mg/kg daily and not exceeding 4 g daily) and ibuprofen 10 mg/kg orally every 6 to 8 hours with food (maximum 40 mg/kg daily and not exceeding 2400 mg daily), for up to 5 days.
• Children: ketamine 1 to 2 mg/kg intravenously for reduction under sedation with airway skilled staff and continuous oximetry and capnography.

Monitoring. Radiographs at 1 week, 2 weeks and 6 weeks, and at union (8 to 12 weeks in adults). Forearm compartments every hour in the first 24 hours after injury or surgery when risk is high. Rotation at 6 weeks and 3 months. Union, and refracture risk after plate or nail removal.

Referral and escalation. All adult fractures and all unstable, open or unreduced paediatric fractures need orthopaedic referral the same day. Emergency for compartment syndrome, open fracture, or neurovascular compromise.

Special groups.

• Children under 3 years: assess for non-accidental injury.
• Adolescents near maturity: manage with adult plate fixation.
• Older adults: osteoporotic fractures need locking plates and bone health assessment.
• Kidney impairment: avoid ibuprofen, reduce morphine doses and extend gentamicin intervals.
• Region specific: tight traditional splints (bamboo or wooden) can cause compartment syndrome and ischaemia, so remove them and examine.