Dorsal Approach to Distal Radius

Osseous Anatomy

The distal radius is the most commonly fractured long bone in adults. Distal radius fractures show a characteristic bimodal age distribution worldwide: young patients (predominantly male, high-energy trauma such as sport and road traffic injury) and older patients (predominantly female, low-energy falls on osteoporotic bone). They are among the most frequent injuries presenting to emergency departments globally and account for a substantial share of upper-limb fractures requiring operative intervention.

The distal radius has THREE articular surfaces: (1) Scaphoid fossa (radial, lateral facet, 50% of load), (2) Lunate fossa (ulnar, medial facet, 50% of load), and (3) Sigmoid notch (articulates with distal ulna in DRUJ). The radial styloid projects roughly 10-12mm distal to the ulnar articular surface (radial length/height). On the lateral view the articular surface has an average volar (palmar) tilt of about 11° (commonly quoted range 10-12°), and on the PA view it has a radial inclination of about 22-23° (ulnar slope).

Lister tubercle is a CRITICAL LANDMARK - a palpable dorsal prominence on the distal radius between the 2nd compartment (ECRL, ECRB) and 3rd compartment (EPL). The tubercle serves as a pulley for EPL tendon and is the key surface landmark for incision planning. The dorsal rim of the distal radius (watershed line) is located 15-20mm proximal to Lister tubercle - dorsal plates MUST be placed proximal to this line to avoid extensor tendon irritation.

Extensor Compartments (6 Compartments at Wrist)

The extensor retinaculum creates SIX dorsal compartments at the wrist, each containing tendons that are at risk during dorsal approach:

1st Compartment (most radial): Abductor Pollicis Longus (APL) and Extensor Pollicis Brevis (EPB) - located at radial styloid, superficial radial nerve crosses over this compartment (injury causes numbness dorsal thumb/1st web)

2nd Compartment: Extensor Carpi Radialis Longus (ECRL) and Brevis (ECRB) - radial to Lister tubercle, inserts on 2nd/3rd metacarpal bases (wrist extension/radial deviation)

3rd Compartment: Extensor Pollicis Longus (EPL) - runs around the ULNAR side of Lister tubercle (uses the tubercle as a pulley), the tendon most at risk of closed/attrition rupture after distal radius fracture, and should be transposed during surgery

4th Compartment: Extensor Digitorum Communis (EDC) to all fingers and Extensor Indicis Proprius (EIP) - ulnar to Lister, used as interval with 3rd compartment for dorsal approach

5th Compartment: Extensor Digiti Minimi (EDM) - over DRUJ

6th Compartment: Extensor Carpi Ulnaris (ECU) - most ulnar, in groove on ulnar styloid

The dorsal approach uses the 3rd-4th compartment interval (EPL vs EDC/EIP). Both compartments are innervated by posterior interosseous nerve (PIN), so this is NOT a true internervous plane, but it is a safe TENDON interval that does not violate muscle bellies.

Nerve Anatomy

Posterior Interosseous Nerve (PIN): Terminal motor branch of radial nerve that innervates all extensor compartments (1st through 6th). PIN is NOT at risk during dorsal wrist approach because it terminates 4-5cm proximal to wrist joint in floor of 4th compartment (under EDC/EIP). No motor branches are encountered during distal radius surgery.

Superficial Radial Nerve (SRN): Pure sensory branch of radial nerve that provides sensation to dorsoradial hand (dorsum of thumb, first web space, radial side of index/middle fingers). SRN emerges between brachioradialis and ECRL in distal forearm (8-10cm proximal to radial styloid) and divides into 3-6 dorsal digital branches. These branches cross the operative field superficially over the 1st/2nd compartments. Injury causes a painful neuroma or numbness over the dorsal thumb and first web space. Protection: keep the incision between the 2nd/3rd compartments (NOT too radial), use blunt dissection in subcutaneous tissue, and identify and retract branches with vessel loops.

Vascular Anatomy

The distal radius has rich blood supply from radial and ulnar arteries via dorsal and volar carpal arches. The dorsal radiocarpal branch of radial artery runs deep to extensor tendons at wrist level and supplies dorsal capsule/ligaments. This vessel is typically cauterized during capsulotomy. The anterior interosseous artery terminates on volar distal radius and is at risk during volar plating (Soong classification) but NOT during dorsal approach.

EPL tendon blood supply is relatively tenuous, with a watershed zone as the tendon turns around Lister tubercle within the 3rd compartment. Fracture haematoma and oedema can raise pressure within the intact 3rd compartment, and sharp dorsal/Lister fragments cause friction, producing ischaemia and delayed attrition rupture. This combination explains why closed EPL rupture is classically described after non- or minimally displaced fractures (sealed compartment) and is the rationale for transposing the EPL out of the compartment during surgery.

Articular Surface and Stability

Distal radius stability depends on restoration of THREE parameters: (1) Radial height (normal 10-12mm, measure from radial styloid tip to ulnar corner of radius on AP X-ray), (2) Volar tilt (normal 11° volar inclination on lateral X-ray, 0° acceptable but dorsal tilt unacceptable), and (3) Radial inclination (normal 23° ulnar slope on AP X-ray).

Biomechanical studies show that EACH 1mm loss of radial height increases distal radioulnar joint (DRUJ) contact pressure by 20-40% and shifts 10% more load to ulnocarpal joint. Radial shortening greater than 2-3mm causes ulnar-sided wrist pain (ulnar impaction syndrome). Dorsal tilt greater than 10° increases radiocarpal contact pressure by 40-50% and predisposes to post-traumatic arthritis.

The dorsal radiocarpal ligament and volar radiocarpal ligament provide extrinsic carpal stability. Dorsally displaced fractures (Colles pattern) disrupt volar ligaments, while volar Barton fractures (shear injury) disrupt dorsal ligaments. Ligament injuries are NOT routinely repaired during fracture ORIF, but severely displaced intra-articular fragments may require arthroscopic or open reduction.

Primary Indications

Dorsally Displaced/Comminuted Distal Radius Fractures: The dorsal approach is indicated when fracture configuration has significant dorsal comminution, metaphyseal impaction, or articular step-off that requires direct visualization and reduction from dorsal side. AO/OTA 23-A3 (extra-articular complete metaphyseal comminution) and 23-C3 (complete articular with metaphyseal comminution) fracture patterns often require dorsal plating because volar plate cannot buttress dorsal cortex effectively.

Absolute indications for ORIF (volar OR dorsal approach): (1) Dorsal angulation greater than 10° (unacceptable biomechanics), (2) Radial shortening greater than 3mm (causes ulnocarpal impaction), (3) Intra-articular step-off greater than 2mm (causes post-traumatic arthritis), (4) Loss of reduction after closed reduction and casting (inherently unstable fracture).

Dorsal Barton Fracture: Shear fracture of dorsal rim with radiocarpal subluxation/dislocation (carpus follows dorsal fragment dorsally). This is an ABSOLUTE indication for ORIF because closed reduction cannot maintain reduction - dorsal buttress plate is REQUIRED to prevent redislocation. Dorsal Barton represents 5-10% of distal radius fractures and has high-energy mechanism (fall on flexed wrist or axial load).

Scaphoid Nonunion (Dorsal Approach ORIF): Proximal pole scaphoid nonunions or waist nonunions with DISI deformity (dorsal intercalated segment instability) can be approached dorsally for screw fixation and bone grafting. The dorsal approach provides direct access to proximal pole and allows dorsal-to-volar screw trajectory. Scaphoid blood supply enters dorsally at waist level (dorsal carpal branch of radial artery), so dorsal approach respects vascular anatomy.

Chronic Scapholunate Ligament Reconstruction: Chronic scapholunate (SL) dissociation with static instability (scapholunate gap greater than 3mm on AP X-ray, DISI deformity on lateral X-ray) requires ligament reconstruction or tenodesis procedures (Brunelli, modified Brunelli, bone-ligament-bone graft). Dorsal approach provides access to dorsal SL ligament (strongest component of SL complex) and allows intercarpal reduction and pinning.

Wrist Arthroscopy Portal Placement: The 3-4 portal (between 3rd and 4th compartments) is the PRIMARY portal for wrist arthroscopy - located 1cm distal to Lister tubercle in line with radial border of 3rd metacarpal. This portal enters radiocarpal joint between scapholunate and lunotriquetral ligaments (center of proximal carpal row). Understanding dorsal anatomy is essential for safe portal placement.

Relative Indications

Volar Lunate Dislocation Reduction: Volar lunate dislocations (lunate displaces volarly and remains attached to volar radiocarpal ligament while carpus dislocates dorsally) can be reduced via dorsal approach if closed reduction fails. Dorsal capsulotomy allows direct reduction of lunate back into lunate fossa and carpal realignment. However, median nerve decompression via VOLAR approach is often performed simultaneously because acute carpal tunnel syndrome occurs in 30-40% of lunate dislocations.

Failed Volar Plating with Dorsal Comminution: Revision surgery for failed volar plate fixation (loss of reduction due to inadequate dorsal buttress) may require dorsal plate supplementation to prevent dorsal collapse. This typically occurs in elderly osteoporotic patients with severe metaphyseal comminution (AO/OTA 23-A3 fractures).

Radiocarpal Fracture-Dislocation: High-energy injuries with complete disruption of radiocarpal joint (both dorsal and volar ligaments torn) may require combined dorsal/volar approach for open reduction, ligament repair, and temporary radiocarpal pinning.

Absolute Contraindications

Active Infection: Cellulitis, abscess, or osteomyelitis overlying dorsal wrist is an absolute contraindication to surgery. Soft tissue infection must be treated with antibiotics and incision/drainage before proceeding with ORIF. Chronic osteomyelitis requires debridement and staged reconstruction.

Inadequate Soft Tissue Coverage: Severe soft tissue injury with skin loss, compartment syndrome, or vascular compromise requires soft tissue reconstruction (skin graft, flap coverage) before attempting ORIF. Open fractures with significant contamination should undergo external fixation and staged ORIF after soft tissue healing (7-14 days).

Relative Contraindications

Low-Demand Elderly with Minimal Displacement: Older, lower-demand patients with minimally displaced extra-articular fractures (AO/OTA 23-A2) often do well with closed reduction and casting, avoiding surgical risks. Multiple randomised trials in patients over 65 (including the widely cited Arora volar-locking-plate-versus-cast trial) have shown that, despite better radiographic alignment with fixation, patient-reported functional outcomes (DASH/PRWE) are similar between operative and non-operative treatment by one year, supporting shared decision-making rather than routine ORIF in this group.

Medical Comorbidities: Uncontrolled diabetes (HbA1c greater than 8%), severe peripheral vascular disease, or active smoking (greater than 10 cigarettes/day) significantly increase wound complications (infection 10-15%, wound dehiscence 5-8%) and nonunion risk (smoking triples nonunion rate). Consider volar approach instead (less soft tissue stripping) or external fixation in high-risk patients.

Complex Regional Pain Syndrome (CRPS) History: Prior CRPS in ipsilateral upper extremity is NOT an absolute contraindication, but patients should be counseled on 10-15% recurrence risk after wrist surgery. Aggressive hand therapy and vitamin C supplementation (500mg daily for 50 days) reduce CRPS incidence.

Extensor Tendon Irritation Risk: Very thin soft tissue envelope (BMI less than 18) or rheumatoid arthritis patients have higher risk of extensor tendon irritation/rupture from dorsal hardware (15-20% vs 2-5% general population). Volar plating is preferred in these patients. If dorsal plating is necessary, use ultra-low-profile plates and bury hardware deep to extensor retinaculum.

Positioning

The patient is positioned supine on the operating table with the affected upper extremity on a radiolucent hand table. General anesthesia or regional anesthesia (axillary block, supraclavicular block) can be used. Regional blocks provide 12-18 hours of postoperative analgesia and reduce opioid requirements.

The arm is positioned in 90° shoulder abduction and 90° elbow flexion with forearm in neutral rotation (thumb pointing up). A nonsterile tourniquet is placed on upper arm and inflated to 250mmHg (or 100mmHg above systolic BP) after exsanguination with Esmarch bandage. Tourniquet time should be limited to less than 90 minutes (ischemia time) with deflation every 90 minutes if longer case.

Fluoroscopy Setup: The C-arm is positioned on the opposite side of the table (foot of bed) and brought in perpendicular to hand table for AP/lateral views. The surgeon stands on the radial side of the arm (if right-handed operating on right wrist, stand on thumb side). The scrub nurse/tech stands opposite (ulnar side).

Preoperative radiographs (AP, lateral, oblique) and CT scan (if intra-articular comminution) are displayed on monitors in OR for reference. Bilateral wrist radiographs of contralateral uninjured wrist can be used as template for radial height/inclination restoration.

Incision

A longitudinal skin incision is made over the dorsum of wrist centered on Lister tubercle (palpable bony prominence). The incision begins 4-5cm proximal to Lister tubercle (in distal forearm) and extends 2-3cm distal to tubercle (over proximal metacarpals). Total incision length is approximately 6-8cm.

The incision is placed between the 2nd compartment (ECRL/ECRB, radial to Lister) and 4th compartment (EDC/EIP, ulnar to Lister), directly OVER the 3rd compartment (EPL). This placement allows EPL identification and transposition while minimizing injury to superficial radial nerve branches (located radially over 1st/2nd compartments).

Superficial Dissection: Incise skin and subcutaneous tissue sharply with scalpel. Identify and protect dorsal venous plexus (ligate or cauterize small veins crossing incision). Use blunt dissection with Metzenbaum scissors to spread subcutaneous tissue and identify superficial radial nerve (SRN) branches. SRN branches appear as white nerve fibers 1-2mm in diameter running obliquely from radial to ulnar across operative field. GENTLY retract nerve branches with vessel loops or small retractors - do NOT excessively stretch or transect.

Deep Dissection - Extensor Retinaculum

The extensor retinaculum (thick fibrous band overlying extensor tendons at wrist) is now visible. The retinaculum has six compartments, each containing specific tendons. Identify the 3rd compartment (EPL tendon) running around ulnar side of Lister tubercle and the 4th compartment (EDC/EIP tendons) ulnar to EPL.

Retinaculum Incision: Make a longitudinal incision in extensor retinaculum over the 3rd compartment (directly over EPL tendon). Extend this incision proximally and distally the full length of the wound. Elevate the radial leaf of retinaculum (2nd compartment side) off underlying EPL tendon using small periosteal elevator.

EPL Transposition (CRITICAL STEP): Identify the EPL tendon (solitary tendon in 3rd compartment, courses around Lister tubercle from ulnar to radial). Use small right-angle clamp or tenotomy scissors to release EPL from its compartment proximally and distally. Gently lift EPL tendon out of 3rd compartment and transpose it RADIALLY (place it superficial to 2nd compartment). EPL will now lie free on radial side and will NOT be replaced back into 3rd compartment at closure (prevents adhesions and rupture).

After EPL transposition, the floor of 3rd compartment (distal radius periosteum) is exposed. This provides a clean window to the fracture site.

Capsulotomy and Fracture Exposure

Incise the dorsal wrist capsule longitudinally over distal radius fracture site. The capsule is 2-3mm thick and appears as white fibrous tissue adherent to bone. Use scalpel or electrocautery to make a longitudinal capsulotomy parallel to radius shaft (4-5cm long).

Elevate capsular flaps radially and ulnarly using periosteal elevator (Cobb or Key elevator) to expose fracture fragments. The pronator quadratus muscle may be partially elevated off volar cortex if volar cortex visualization is needed (elevate from radial to ulnar). However, extensive pronator stripping should be avoided as it devascularizes fracture fragments.

Fracture Visualization: The fracture site is now exposed. Dorsal comminution (multiple small fragments) and metaphyseal impaction (crushed cancellous bone) are typically seen in Colles-pattern fractures. Use small periosteal elevator or Freer elevator to gently disimpact fracture fragments and restore radial length/volar tilt.

Fracture Reduction

Reduction Maneuvers: (1) Apply longitudinal traction to distal fragment (thumb and fingers) to restore radial length - compare to preoperative radiograph or contralateral side for target length. (2) Apply volar translation force to distal fragment to restore volar tilt (11° normal). (3) Reduce any articular step-off by direct pressure on displaced fragments using small elevator or probe.

For intra-articular fractures, use fluoroscopy (AP, lateral, oblique views) and direct visualization to confirm articular surface congruity (step-off less than 2mm). If articular reduction cannot be achieved with closed maneuvers, use small pointed reduction forceps or 0.062-inch K-wires as joysticks in metaphyseal fragments to manipulate pieces into anatomic position.

Provisional Fixation: Once reduction is achieved, hold position with 0.062-inch K-wires placed from radial styloid into ulnar cortex (2-3 wires) or from dorsal cortex into volar cortex (interfragmentary lag technique). K-wires stabilize reduction temporarily during plate application.

Plate Fixation

Select an appropriate dorsal locking plate (low-profile design, titanium or stainless steel). The plate should be sized to fit distal radius contour (small, medium, large based on AP width). Position the plate longitudinally on dorsal radius PROXIMAL to watershed line (15-20mm proximal to Lister tubercle) to prevent extensor tendon irritation.

Plate Placement: The distal end of plate should be 2-3mm proximal to dorsal articular rim (if placed directly on rim, extensor tendons will rub on plate). Contour plate to match dorsal radius curvature (slight convexity). Fix plate proximally first with 3.5mm cortical screws in shaft (two screws in oblong holes to allow distal adjustment). Check reduction and plate position with fluoroscopy (AP/lateral).

Distal Locking Screws: Once plate position is confirmed, place distal locking screws (2.4mm or 2.7mm diameter) into subchondral bone of distal radius. Locking screws provide fixed-angle stability and prevent volar tilt collapse. Use fluoroscopy to ensure screws do NOT penetrate articular surface (stop 2-3mm short of subchondral bone on lateral view). Place 4-6 distal locking screws in divergent trajectories (radial-ulnar-volar directions) to maximize fragment fixation.

Plate Countersinking: After all screws are placed, verify that plate is flush with bone (no prominent edges). If plate is slightly prominent, use bone rongeur to remove small amount of dorsal cortex around plate edges (create slight depression so plate sits below bone surface). This reduces tendon irritation.

Augmentation for Metaphyseal Voids

If significant metaphyseal comminution or bone loss is present, the subchondral void can be filled with bone graft substitute (calcium phosphate cement, calcium sulfate, or allograft cancellous chips) to prevent articular subsidence. Inject bone graft substitute through small cortical window before applying plate, or pack around screws after plate placement.

Autogenous iliac crest bone graft is rarely needed for distal radius fractures (reserved for nonunions or severely osteoporotic bone with high-risk comminution). Bone graft substitutes provide equivalent structural support with lower morbidity (no donor site pain).

Closure

Fluoroscopy Check: Obtain final AP, lateral, and oblique wrist radiographs to confirm: (1) Radial height restored (10-12mm), (2) Volar tilt restored (11° or neutral acceptable), (3) Radial inclination restored (23°), (4) Articular step-off less than 2mm, (5) No intra-articular screw penetration, (6) Plate position acceptable (proximal to watershed line).

Capsule Closure: Repair dorsal capsule with 2-0 absorbable suture (Vicryl) in interrupted or running fashion. Capsule repair reinforces dorsal stability and covers hardware.

EPL Management: EPL tendon remains transposed RADIALLY outside 3rd compartment (do NOT replace into compartment). Ensure EPL glides freely without kinking or catching on hardware.

Retinaculum Repair: Repair extensor retinaculum over 4th compartment (EDC/EIP side) with 2-0 Vicryl, but leave radial leaf open or loosely closed to accommodate transposed EPL without constriction.

Subcutaneous and Skin: Close subcutaneous layer with 3-0 Vicryl in buried interrupted fashion. Close skin with 4-0 nylon vertical mattress or running subcuticular 4-0 Monocryl. Apply sterile dressing and volar resting splint (wrist in 20° extension, forearm neutral rotation).

Postoperative Protocol

Immobilization: Volar splint for 10-14 days until suture removal, then transition to removable wrist brace. Early finger/thumb ROM exercises begin immediately (day 1-2) to prevent stiffness. Wrist ROM begins at 2-3 weeks (gentle flexion/extension, pronation/supination).

Radiographic Follow-up: X-rays at 2 weeks, 6 weeks, 12 weeks to monitor fracture union and hardware position. Union expected by 6-8 weeks for extra-articular fractures, 8-12 weeks for intra-articular fractures.

Strengthening: Progressive grip strengthening at 6 weeks, full activity (unrestricted lifting) at 12 weeks. Return to heavy manual labor/contact sports at 3-4 months once radiographic union and full ROM/strength achieved.

Hardware Removal: Dorsal plating is associated with a higher rate of extensor tenosynovitis than volar plating (approximately 7.5% vs 4.5%; Azzi 2017). If symptomatic tendon irritation occurs (pain with finger extension, palpable clicking over the plate), plate removal once the fracture has united is reasonable and usually resolves symptoms. Asymptomatic patients do NOT require routine removal.