Approach to the Distal Radioulnar Joint and Ulnar Head

What it exposes. The dorsal (and dorsoulnar) approach gives direct, extensile access to the ulnar head, the sigmoid (ulnar) notch of the radius, the DRUJ capsule, and the foveal insertion of the triangular fibrocartilage complex (TFCC). It is the workhorse exposure for almost every DRUJ reconstruction and salvage procedure, and it can be extended proximally along the ulna or distally onto the carpus. Indications. - DRUJ arthritis — osteoarthritis, inflammatory (rheumatoid), or post-traumatic

• DRUJ instability — chronic, from TFCC foveal avulsion that has failed non-operative management
• Distal ulna impaction syndrome — ulnar positive variance abutting the triangular fibrocartilage
• Distal ulna resection or arthroplasty — Darrach, Sauve-Kapandji, Bowers hemiresection, or ulnar head prosthetic replacement
• DRUJ arthrodesis — salvage for failed arthroplasty or gross instability in a low-demand patient
• TFCC foveal repair — open or arthroscopic-assisted reinsertion of the deep TFCC to the ulnar fovea
• Malunion of the distal ulna — corrective osteotomy of the ulnar head or shaft Contraindications. Active infection of the dorsoulnar wrist skin or deeper tissues; severe soft-tissue compromise (previous scars, thin atrophic skin common in rheumatoid patients, or a previous flap that alters flap viability); poor vascular supply to the limb; and a ruptured or grossly unstable ECU tendon that must be addressed first, because the approach depends on a functional sixth compartment. Alternative and adjunct approaches. Arthroscopic TFCC repair for an isolated foveal or peripheral tear without arthritis; a direct ulnar (mini-open) approach over the sixth compartment for a foveal repair or ulnar shortening; the Henry volar approach if combined volar distal radius work is needed (but it gives poor DRUJ access); and the ulnar approach to the ulnar shaft when an ulnar shortening osteotomy is also required.

Clinical assessment that drives the decision. The ulnar-sided painful wrist is a differential trap, so combine clinical tests with imaging before committing to an approach. DRUJ-specific signs include the piano-key sign (the ulnar head ballots dorsally relative to the radius in pronation — dorsal instability), the DRUJ stress or ballottement test (anteroposterior translation of the radius on the ulna, compared with the contralateral side), the fovea sign (focal tenderness at the palmar-ulnar wrist suggesting foveal TFCC disruption), the press test (pushing up from a chair reproduces ulnar-sided pain — sensitive for TFCC/DRUJ pathology), and the ECU synergy test (resisted wrist ulnar deviation with extension reproduces ECU pain or subluxation). Always record baseline DSBUN distribution sensation, forearm pronation-supination, and grip strength, because the nerve is at risk and these are your baselines for later. Exclude mimics — TFCC tears, lunotriquetral ligament injury, ECU tendinopathy or subluxation, ulnocarpal impaction, pisotriquetral arthritis, and ulnar nerve or DSBUN neuritis. Imaging. PA and lateral radiographs of the wrist in true neutral rotation assess DRUJ congruity, ulnar variance, and arthritis; a grip PA view exaggerates ulnar positive variance and unmasks ulnocarpal impaction; and contralateral comparison views help with variance and congruity. Bilateral CT in pronation, neutral, and supination is the gold standard for DRUJ subluxation or dislocation and is essential for planning arthrodesis or prosthetic seating. MRI or MR arthrography best shows the TFCC (central degenerative versus peripheral versus foveal avulsion) and assesses the LT ligament, ECU tendon, and subchondral oedema. Diagnostic wrist arthroscopy is the most accurate assessment of the TFC disc, the foveal insertion (the "hook test"), the LT ligament, and chondral surfaces, and allows concurrent arthroscopic foveal repair. An ultrasound-guided DRUJ or ulnocarpal injection of local anaesthetic and steroid that abolishes the pain confirms the pain generator. Position and landmarks. Supine with the affected arm abducted onto a radiolucent hand table, shoulder flat, arm in neutral rotation, and a well-padded upper arm tourniquet. The limb is free to be pronated and supinated throughout the case — essential to bring the ulnar head dorsally into view. The surgeon sits at the head of the hand table for a stable, magnified, two-handed technique; loupe magnification is routine. Palpate and mark the ulnar head, the ulnar styloid, the ECU tendon (sixth compartment, just dorsal to the styloid, made obvious with wrist extension and ulnar deviation against resistance), the slender EDM tendon (fifth compartment, just radial to the ECU), and Lister's tubercle. Plan a longitudinal dorsoulnar incision, 6 to 10 cm, centred over the DRUJ between the EDM and ECU, or slightly ulnar to the ECU for more direct foveal access; a gently curved or zig-zag incision respects the wrist creases and reduces contracture.

Work down through the layers in the intercompartmental interval between the fifth (EDM) and sixth (ECU) extensor compartments, protecting the dorsal sensory branch of the ulnar nerve in the flap, preserving the ECU subsheath, and opening the dorsal DRUJ capsule to reach the ulnar head and the fovea.

Extensile options. Extend proximally along the subcutaneous border of the ulna in the interval between the ECU (dorsal) and the flexor carpi ulnaris (volar) — the same interval as the standard approach to the ulnar shaft — to reach the ulnar shaft for an ulnar shortening osteotomy, malunion correction, or shaft fixation. Extend distally onto the dorsoulnar wrist and carpus to reach the dorsal triquetrum, the ECU sheath at the carpus, and the ulnocarpal joint. Useful combined approaches include staging distal radius volar plating (Henry) through a separate incision for a distal radius fracture with DRUJ/TFCC injury; supplementing wrist arthroscopy (arthroscopic TFCC assessment and repair) with a mini-open dorsal approach for foveal reinsertion or arthroplasty; and adding an ulnar shortening osteotomy via the proximal extension for ulnar impaction needing both variance correction and DRUJ/TFCC management. Closure. Repair the DRUJ capsule meticulously with absorbable sutures using the preserved capsular cuffs — a watertight capsular closure is especially important after prosthetic replacement and resection to contain the joint and stabilise the construct. Repair the ECU subsheath and extensor retinaculum to restore both ECU tendon stability and dorsal DRUJ stability; failing to repair it invites ECU subluxation and DRUJ instability. Release the tourniquet, achieve meticulous haemostasis, irrigate, consider a drain only for a large resection or arthroplasty, and close subcutaneous tissue and skin. Apply a sterile bulky dressing and a sugar-tong or long arm splint in a position that protects the repair (typically neutral to slight supination for a foveal repair, or as dictated by the procedure).

Post-operative care varies by procedure. A TFCC foveal repair is splinted in a long arm or sugar-tong splint in neutral to slight supination for about 6 weeks, then progressive rotation and strengthening. An ulnar head replacement is splinted for 2 to 4 weeks with protected motion and no loading for 6 weeks. Darrach, Sauve-Kapandji and Bowers procedures have a short period of splintage (about 2 weeks) then early forearm rotation to prevent stiffness and adhesions. A DRUJ arthrodesis is immobilised until radiographic union, then the pseudoarthrosis and forearm are mobilised. Elevate the limb, monitor neurovascular status (especially the DSBUN distribution), and use hand therapy for oedema control, scar management, and staged range of motion. Review at 2 weeks (wound check, suture removal, splint check, begin early motion), 6 weeks (radiographs, progress mobilisation and loading), 3 months (functional and radiographic assessment, grip strength), and 6 to 12 months (final outcome assessment).

A single dorsal exposure serves the whole family of DRUJ procedures — what changes is the soft-tissue handling and the demands of closure, not the approach itself. - TFCC foveal repair — reinsert the deep TFCC to the fovea with transosseous tunnels or suture anchors, restoring the deep radioulnar ligaments and DRUJ stability (young, high-demand patient with an isolated foveal avulsion and an intact joint).

• Ulnar head replacement (prosthetic arthroplasty) — resect the arthritic head to the defined cut, prepare the shaft, and seat a modular or monoblock prosthesis; stability depends on a competent, repaired capsule and ECU subsheath (active patient, painful arthritis, intact soft tissues).
• Sauve-Kapandji — debride the sigmoid notch and ulnar head cartilage, fuse the DRUJ with a compression screw across the ulnar head into the sigmoid notch, then resect a segment of ulna proximal to the fusion to create a pseudoarthrosis that preserves rotation and the ulnar carpal buttress.
• Darrach — resect the distal ulna at the level of the ulnar neck with minimal resection to avoid stump impingement and instability (low-demand, often rheumatoid, patient).
• Bowers hemiresection interposition — resect only the distal articular portion of the ulnar head, preserving the ulnar styloid and TFCC attachment, and interpose soft tissue (capsule or a rolled ECU slip) to prevent radioulnar impingement.
• DRUJ arthrodesis — decorticate the sigmoid notch and ulnar head and fuse them (often as the Sauve-Kapandji construct, or as a salvage with proximal resection), fixed with a screw or plate.

The unifying principle. Resection procedures (Darrach) remove the load-bearing ulnar head and can destabilise the ulnar stump and the carpus, while reconstructive procedures (repair, prosthesis) aim to preserve or restore load transfer and the soft-tissue stabilisers. The dorsal approach serves both families, but resection cases tolerate a looser capsule whereas prosthetic and repair cases depend on a competent, repaired ECU subsheath and capsule.

Guidelines, Registries & Global Practice The dorsal approach to the DRUJ and ulnar head is a standard hand and upper limb exposure taught and practised worldwide. The surgical anatomy and the family of DRUJ procedures performed through this exposure are convergent across examination systems and textbooks. | Body | Position on DRUJ disorders |

|------|----------------------------| | AAOS / ASSH | Match the procedure to patient demand and joint status; preserve or restore anatomy (repair or prosthesis) in active patients; reserve resection for low-demand or salvage situations | | BOA / BSSH (UK) | Confirm the diagnosis with appropriate imaging before surgery; protect the dorsal sensory branch of the ulnar nerve; repair the capsule and ECU subsheath to maintain stability | | EFORT / FESSH (Europe) | Arthroscopy has a growing role in diagnosis and foveal repair; prosthetic ulnar head replacement is an established option for the painful arthritic DRUJ with intact soft tissues | Registry and population evidence. Distal radius fractures are among the most common fractures in adults, and DRUJ and TFCC injury accompanies a substantial proportion, underlining the frequency with which this anatomy and exposure are encountered. Ulnar head prosthetic arthroplasty series report reliable pain relief and improved grip and satisfaction at short to medium term, with implant-related complications (loosening, instability) as the principal long-term concern. Global practice variation. In high-resource settings, modular ulnar head prostheses, suture anchors, and routine arthroscopy are standard. In resource-limited settings, the same dorsal approach is used for resection procedures (Darrach, Sauve-Kapandji) and open foveal repair with transosseous sutures, achieving durable results without implants where prosthetic options are unavailable. Consent (globally applicable). Discuss dorsal sensory branch of the ulnar nerve injury and possible neuroma, DRUJ or ECU instability if the capsule or subsheath is not restored, implant-related risks if a prosthesis is used, stiffness and loss of rotation, and the possibility of revision surgery or a salvage procedure.