Both Bone Forearm Fractures

Both bone forearm fractures (BBFF) — simultaneous fractures of the radius and ulna — occur in two distinct clinical settings: in children (where they are the most common paediatric fracture pattern requiring surgical treatment in the upper limb) and in adults (where ORIF with plating is the standard of care). The forearm functions as a joint — the two bones articulate at the proximal radioulnar joint (PRUJ) and distal radioulnar joint (DRUJ), with the interosseous membrane providing the critical fibrous link between them. Restoration of anatomical alignment is essential for forearm rotation — any malunion that changes the interosseous space or the radial bow will restrict pronation and supination. This is the guiding principle of forearm fracture management.

• The radial bow: the radius is not straight — it has a characteristic lateral bow (maximum radial bow of approximately 15 mm at the junction of the proximal and middle thirds); this bow is essential for normal forearm rotation (it allows the radius to rotate around the ulna during pronation and supination); loss of the radial bow (straight radius from malunion) significantly restricts forearm rotation; restoration of the radial bow during ORIF is one of the most critical technical points of forearm plating
• The interosseous membrane (IOM): runs obliquely from the radius (distally) to the ulna (proximally) — the central band transmits longitudinal force from the radius to the ulna; the IOM maintains the interosseous space and is critical for forearm stability; disruption of the IOM occurs in Essex-Lopresti injuries (radial head fracture + IOM rupture + DRUJ disruption)
• Epidemiology in adults: account for approximately 1.5% of all fractures; bimodal — young adults (road traffic accidents, sports, falls from height) and elderly (osteoporotic low-energy falls); in adults, closed reduction and casting are inadequate for both-bone forearm fractures (high malunion rate and functional loss of rotation); ORIF with compression plating is the standard

• Bado classification of Monteggia fractures: Type I (anterior dislocation of radial head — most common, ~70%; ulna fracture with apex anterior angulation); Type II (posterior/posterolateral radial head dislocation — ~15%; associated with elbow fractures in adults); Type III (lateral radial head dislocation — ~10%; more common in children); Type IV (anterior radial head dislocation + fracture of both radius and ulna in the proximal third — rare)
• The line of the radius through the capitellum rule: on any radiographic view of the elbow, a line drawn through the long axis of the radial shaft should bisect the capitellum; this is the most reliable method to identify radial head dislocation; every elbow X-ray after forearm trauma must be checked for this relationship

• ORIF is the standard of care for adult BBFF: closed management in adults results in unacceptable malunion rates and loss of forearm rotation; both bones are plated; standard technique — 3.5 mm dynamic compression plates (DCP) or locking compression plates (LCP); minimum 6 cortices (3 screws) above and below each fracture; the ulna is approached through the subcutaneous border (a direct approach along the palpable ulnar border — the internervous plane between flexor carpi ulnaris and extensor carpi ulnaris); the radius is approached through the volar (Henry) approach (between FCR and the radial artery — or between brachioradialis and FCR in the proximal forearm; the radial nerve branches — PIN — must be protected)
• The Henry approach to the radius: the most widely used approach; the patient is supine with the arm on a hand table; the skin incision runs from the bicipital tuberosity (proximally) to the radial styloid (distally) along the volar radial border; the interval is between the FCR (median nerve) and the brachioradialis (radial nerve — the radial artery runs with brachioradialis and must be identified and protected); in the proximal forearm, the PIN must be decompressed by supinating the forearm (moves the PIN away from the incision field); the flexor pollicis longus and pronator quadratus are elevated off the volar radius to expose the fracture
• Thompson (dorsal) approach to the radius: an alternative to Henry`s; used for fractures in the proximal or middle thirds of the radius; the interval is between the extensor carpi radialis brevis (radial nerve) and extensor digitorum communis (posterior interosseous nerve); the PIN must be identified and protected (it crosses the surgical field in the proximal forearm — supination moves it distally and laterally away from the approach)
• Restoration of radial bow: the radial bow must be restored during plate application; contoured plates matching the natural bow of the radius are available; intraoperative fluoroscopic assessment in the true lateral projection confirms bow restoration; a `bow index` (ratio of maximum bow height to length of the radius) of >0.15 predicts satisfactory forearm rotation
• Order of fixation: the less comminuted bone is fixed first to provide a reference for length and alignment; then the second bone is fixed; alternatively, both bones are provisionally fixed then definitively secured

• Remodelling potential in children: in children, significant angulation and translational malunion can remodel with growth; however, rotational malunion does NOT remodel; therefore, rotational malalignment must be corrected; acceptable angulation for conservative management depends on age — children under 9 years can accept up to 15–20° of angulation in the proximal and middle thirds; older children (>10 years) have less remodelling potential and stricter reduction criteria apply; malunion of both bone forearm fractures in children causes loss of forearm rotation that may be functionally limiting
• Closed manipulation under anaesthesia + above-elbow cast: the standard initial management for paediatric BBFF; the forearm position in the cast affects rotational alignment — fractures of the proximal third are immobilised in supination (to align the proximal radius fragment which is supinated by the biceps and supinator); fractures of the middle and distal third are immobilised in neutral rotation
• Flexible intramedullary nailing (elastic stable intramedullary nailing — ESIN/Nancy nails): the preferred surgical technique in children for BBFF requiring fixation; flexible titanium nails are inserted percutaneously — the radius nail enters through the distal radius metaphysis (retrograde) and the ulna nail through the olecranon or the distal ulna; the nails maintain reduction and allow early mobilisation; indications — failed closed reduction, open fractures, irreducible fractures, pathological fractures; removed at 3–6 months after fracture union; ESIN does not achieve rigid fixation — some movement at the fracture site promotes callus formation (secondary bone healing)

• Forearm as a joint: radius + ulna + IOM form a functional unit; any malunion altering interosseous space or radial bow = loss of pronation/supination; anatomical restoration is mandatory in adults
• Radial bow: ~15 mm at proximal-middle third junction; must be restored during plating; loss of bow → restricted forearm rotation; bow index >0.15 predicts good rotation
• Adult BBFF: ORIF standard (closed management = unacceptable malunion); 3.5 mm DCP/LCP; minimum 6 cortices each side of fracture; ulna — subcutaneous border approach; radius — Henry`s volar approach or Thompson`s dorsal approach
• Henry`s approach: between FCR (median nerve) and brachioradialis (radial nerve/artery); PIN protected by supinating forearm proximally; most common approach to radius
• Monteggia: ulna fracture + radial head dislocation; MISSED radial head dislocation is the classic error; radial shaft line should bisect capitellum on ALL views; Bado Type I (anterior, most common); PIN injury in Type I
• Galeazzi: `fracture of necessity` — always requires surgery; distal radius fracture + DRUJ disruption; ORIF radius → assess DRUJ under fluoroscopy; unstable DRUJ → K-wire transfixion in supination 6 weeks
• Paediatric BBFF: remodelling corrects angulation (NOT rotation); proximal third cast in supination; middle/distal in neutral; ESIN/Nancy nails for failed closed reduction
• Proximal forearm fracture: forearm in SUPINATION for cast (biceps + supinator supinate the proximal radius fragment; casting in supination aligns the distal fragment with the supinated proximal fragment)
• ESIN in children: flexible intramedullary nails; percutaneous; radius — retrograde from distal metaphysis; ulna — from olecranon or distal ulna; removed at 3–6 months; allows some motion (secondary bone healing)
• Radial nerve/PIN: must be protected in Thompson`s approach; supinating the forearm moves PIN distally away from the proximal wound; identified and protected before proximal radius dissection