Approach to the TFCC and Ulnar Side of the Wrist

What it exposes. The open ulnar approach gives direct access to the triangular fibrocartilage complex (TFCC), its foveal attachment at the base of the ulnar styloid, and the distal radioulnar joint (DRUJ), through the interval between the extensor carpi ulnaris (dorsal) and the flexor carpi ulnaris (volar). Why open (and not arthroscopic). Arthroscopy now treats most TFCC tears, but the open ulnar approach gives direct, unconstrained visualisation of the fovea and the deep (proximal) lamina of the TFCC. The fovea sits at the base of the ulnar styloid and is the strongest stabilising attachment of the DRUJ. When a peripheral tear is retracted, chronic, large, or associated with frank DRUJ instability, open foveal reinsertion through this interval is the most reliable way to achieve anatomic, tension-free reattachment. It is also the same internervous interval used to expose the distal ulnar shaft for an ulnar shortening osteotomy. ### Primary indications - Palmer 1B tears (ulnar or peripheral avulsion from the fovea or ulnar styloid) requiring open repair

• Foveal reinsertion for a foveal TFCC avulsion with DRUJ instability, including chronic or retracted tears not amenable to arthroscopic all-inside repair
• Chronic DRUJ instability in which arthroscopic repair has failed or is not feasible
• Ulnar shortening osteotomy for ulnocarpal impaction syndrome with positive ulnar variance
• Combined pathology where foveal repair is performed together with an ulnar shortening or a wafer procedure
• Ulnar styloid nonunion with a base fragment carrying the foveal attachment, requiring fixation or excision ### Contraindications - Active infection or compromised ulnar skin (abrasions or previous scars that cannot be incorporated)
• Advanced degenerative TFCC disease with established DRUJ arthritis (Palmer 2E) - salvage such as Darrach, Sauve-Kapandji, or a DRUJ arthroplasty is preferred over repair
• An isolated central Palmer 1A tear without peripheral detachment - this is avascular and is debrided, usually arthroscopically
• Significant medical comorbidity making elective wrist surgery inappropriate ### Alternative and complementary approaches - Wrist arthroscopy - the default for diagnostic assessment and most repairs (all-inside, inside-out, outside-in)
• Dorsal (sigmoid notch) approach to the DRUJ - opens the dorsal capsule between the fifth and sixth extensor compartments for DRUJ arthritis or reconstruction
• Volar approach to Guyon's canal - for ulnar nerve decompression rather than TFCC work
• Direct ulnar shortening approach - the proximal extension of the same ECU to FCU interval

Why 1B matters. 1B is a peripheral tear, and the peripheral TFCC is vascularised, so it heals when repaired. It often involves the foveal attachment, producing DRUJ instability, and it is the principal indication for the open ulnar approach when arthroscopic repair is not suitable. A foveal avulsion can exist with an intact superficial disc, so the TFCC can look normal on standard arthroscopic viewing from the radiocarpal joint; probing from a DRUJ portal and assessing the fovea sign (loss of the normal trampoline and hook tension) reveals the deep detachment, and the European Wrist Arthroscopy Society (EWAS) framework grades foveal tears by tissue quality, retraction, and reparability to guide arthroscopic all-inside repair versus open foveal reinsertion.

Position and landmarks Position. Supine on a radiolucent hand table with the shoulder abducted and flat so the forearm can be pronated or supinated as required; the surgeon typically sits on the cephalad or axillary side. Apply a padded pneumatic tourniquet high on the upper arm, exsanguinate with an Esmarch bandage and inflate it, and have an image intensifier available if an ulnar shortening osteotomy or implants are planned. Keep the forearm free to rotate, because pronation and supination change the relationship of the TFCC to the fovea and are used to reduce the repair. Landmarks. Bony landmarks are the ulnar styloid (marking the distal ulna and the fovea at its base), the ulnar head (defining the DRUJ), the pisiform (marking the proximal extent of Guyon's canal), and the DRUJ line between the ulnar head and the sigmoid notch. Soft-tissue landmarks are the ECU tendon (dorsal boundary), the FCU tendon (volar boundary), and the ulnar snuffbox (the soft depression between them, directly over the TFCC and DRUJ). Plan a longitudinal or gently zig-zag incision 4 to 6 cm long centred on the DRUJ between ECU dorsally and FCU volarly; for an ulnar shortening osteotomy shift it proximally along the distal ulnar shaft, and plan it to allow extension both proximally (ulnar shaft) and distally (ulnocarpal joint).

Work down through the layers between the ECU and FCU, protecting the dorsal sensory branch of the ulnar nerve in the subcutaneous fat, then develop the true internervous plane onto the dorsoulnar capsule and the fovea. ### The anatomy that governs the dissection The TFCC is composite, not a single disc. Its components are the articular triangular fibrocartilage (the central disc), the dorsal and palmar radioulnar ligaments, the meniscal homologue, the sheath of the extensor carpi ulnaris, the ulnotriquetral and ulnolunate ligaments, and the ulnar collateral ligament. It originates from the ulnar border of the distal radius (the sigmoid notch) and inserts onto the ulnar head and styloid through a dual attachment: a strong proximal (foveal) lamina at the base of the ulnar styloid and a distal (styloid) lamina at the styloid tip. Vascularity dictates treatment. The peripheral third of the TFCC is vascularised from the dorsal and palmar branches of the anterior interosseous artery, the ulnar artery, and the dorsal sensory branch of the ulnar artery, while the central two-thirds is avascular and is nourished by synovial fluid diffusion. This is why peripheral Palmer 1B tears heal when repaired and central Palmer 1A tears do not - the centre is debrided, the periphery is repaired. ### The internervous plane The plane lies between the extensor carpi ulnaris, supplied by the posterior interosseous nerve (a branch of the radial nerve), dorsally, and the flexor carpi ulnaris, supplied by the ulnar nerve, volarly. It is a true internervous plane between radial and ulnar nerve territories, so neither muscle is denervated by developing the interval. ECU is retracted dorsally and FCU volarly to reach the dorsoulnar capsule, the DRUJ, and the fovea.

Structures at risk, by layer

• Open foveal reinsertion (Palmer 1B) - the principal procedure; anatomic reattachment of the vascularised peripheral TFCC to the fovea.
• Peripheral TFCC repair - direct suture repair of a dorsoulnar peripheral tear when arthroscopy is not suitable.
• DRUJ capsulotomy and ligamentous reconstruction - for chronic DRUJ instability.
• Ulnar shortening osteotomy - through the same ECU to FCU interval extended proximally along the distal ulnar shaft; an oblique osteotomy is shortened by 2 to 4 mm (to achieve 1 to 2 mm of negative variance) and fixed with a 3.5 mm plate.
• Wafer procedure - partial resection of the distal ulnar dome for ulnocarpal impaction without DRUJ arthritis.
• Ulnar styloid fixation or excision - for a styloid nonunion that carries the foveal attachment. Relationship to arthroscopy. Most TFCC work is now arthroscopic because it is less invasive and allows direct assessment of the whole wrist. The open ulnar approach complements arthroscopy rather than replacing it: it is chosen when the fovea must be seen directly, when the tear is chronic and retracted, when tissue quality is poor, or when a concomitant ulnar shortening osteotomy is performed.

Guidelines, registries and global practice Management of ulnar-sided wrist pain and TFCC injury is convergent across examination systems. The shared principles are: confirm the diagnosis with neutral-rotation radiographs and MRI; reserve repair for vascularised peripheral and foveal tears; default to arthroscopy for most repairs; and use the open ulnar approach selectively for foveal reinsertion and ulnar shortening.

Population and biomechanical evidence: - The TFCC transmits approximately 20 percent of axial load across the wrist at neutral ulnar variance, and this load rises as ulnar variance becomes more positive, underpinning ulnar shortening for impaction.

• The peripheral third of the TFCC is vascularised while the central two-thirds is avascular, which is the anatomic basis for repairing the periphery and debriding the centre.
• The foveal (proximal lamina) attachment is the strongest stabiliser of the DRUJ, explaining why foveal detachment produces clinically significant instability even when the superficial disc appears intact. Global practice variation. In well-resourced settings, wrist arthroscopy is routine and suture anchors or arthroscopic all-inside devices are standard. In resource-limited settings, open peripheral repair and trans-osseous suture techniques achieve the same biological goal without arthroscopic equipment, and ulnar shortening is performed with conventional small-fragment plates. Consent (globally applicable): discuss dorsal sensory branch of the ulnar nerve injury and possible neuroma, persistent or recurrent DRUJ instability, stiffness, and (with ulnar shortening) nonunion and hardware irritation.