Sauvé-Kapandji Procedure: A Masterclass in Distal Radioulnar Joint Reconstruction

Introduction and Pathophysiology of Distal Radioulnar Joint Disorders

Disorders of the distal radioulnar joint (DRUJ) represent a profound source of ulnar-sided wrist pain and functional impairment. The etiology of DRUJ pathology is typically multifactorial, encompassing instability, impingement, ulnocarpal impaction, and inflammatory or degenerative arthritis. Impingement or impaction symptoms referable to this articulation frequently arise from displaced fractures or malunions of the distal radius. These structural deformities alter the kinematics of forearm pronation and supination, leading to accelerated articular wear. Furthermore, traumatic avulsions or degenerative tears of the foveal attachment of the triangular fibrocartilage complex (TFCC) critically destabilize the DRUJ, producing mechanical symptoms, subluxation, and severe pain.

Congenital anomalies, such as Madelung deformity, and systemic autoimmune conditions, particularly rheumatoid arthritis (RA), frequently display secondary incongruity of the DRUJ. In the rheumatoid wrist, progressive synovial hypertrophy and ligamentous attenuation result in predictable patterns of carpal supination and volar subluxation, leading to profound loss of forearm rotation. Similarly, proximal radioulnar joint pathology, such as a radial head fracture treated by primary resection without prosthetic replacement, can induce proximal migration of the radius (Essex-Lopresti lesion), culminating in painful incongruity and longitudinal instability of the DRUJ.

The management of isolated DRUJ pain, incongruity, or instability remains a formidable surgical challenge. The Sauvé-Kapandji procedure—comprising an arthrodesis of the DRUJ combined with a proximal pseudoarthrosis of the distal ulna—serves as a highly effective, comprehensive solution addressing all three pathological components simultaneously.

Figure 1: Radiographs from a patient with rheumatoid arthritis before (A) and after (B,C) a Sauvé-Kapandji procedure. The ulnar osteotomy allows for precise shortening to establish neutral ulnar variance while preserving functional forearm rotation.

Surgical Anatomy and Biomechanics

Osteoarticular Morphology

The DRUJ is the distal articulation in the biarticulate rotational arrangement of the forearm, permitting one primary degree of freedom: pronation and supination. The articular geometry is inherently incongruous. The sigmoid notch of the distal radius is concave, possessing a 15-mm radius of curvature. In contrast, the ulnar head is semicylindrical with a smaller radius of curvature of 10 mm and an articulate convexity spanning 220 degrees.

Because the radius of curvature of the ulnar head does not match that of the sigmoid notch, joint contact area varies significantly throughout the arc of motion. At the extremes of pronation and supination, less than 10% of the ulnar head may be in direct contact with the sigmoid notch. Kinematically, during pronation, the ulnar head translates 2.8 mm dorsally from a neutral position; during supination, it translates 5.4 mm volarly.

Ligamentous and Soft Tissue Stabilizers

The stability of the DRUJ is governed by the osseous morphology, the joint capsule, the radioulnar ligaments, the interosseous membrane, and dynamic musculotendinous forces.
* Triangular Fibrocartilage Complex (TFCC): The TFC is a fibrocartilaginous disc originating at the junction of the lunate fossa and the sigmoid notch, inserting at the base of the ulnar styloid (the fovea). The central portion is avascular cartilage designed for axial load-bearing, whereas the thick, lamellar peripheral margins (dorsal and palmar radioulnar ligaments) are highly vascularized and designed to resist tensile loads. Blood supply to the periphery is derived from the palmar and dorsal branches of the anterior interosseous and ulnar arteries.
* Dynamic Stabilizers: The pronator quadratus acts as a critical dynamic stabilizer by coapting the ulnar head into the sigmoid notch during active pronation and providing passive viscoelastic stabilization during supination. The extensor carpi ulnaris (ECU) is retained over the dorsal distal ulna within a distinct fibro-osseous tunnel, deep to the extensor retinaculum, ensuring unrestricted radioulnar rotation while stabilizing the ulnar aspect of the carpus.

Pathogenesis and Natural History

Traumatic disruption of the DRUJ initiates a cascade of instability leading to painful degenerative joint disease. Distal radial malunions featuring dorsal or volar angulation produce secondary elongation, rupture, or functional shortening of the radioulnar ligaments. Radial shortening secondary to fracture malunion frequently precipitates ulnar impaction syndrome, leading to abutment against the lunate and secondary DRUJ incongruity. Post-traumatic DRUJ osteoarthritis is a particularly common sequela of Colles fractures involving intra-articular extension into the sigmoid notch.

In the rheumatoid wrist, the progression of distal radioulnar synovitis classically results in the "caput ulnae syndrome," originally described by Backdahl. This syndrome is characterized by:
* Weakness and pain during forearm rotation.
* Dorsal prominence and instability of the ulnar head.
* Severe limitation of pronation and supination.
* Swelling and synovial proliferation over the distal radioulnar interval.
* Secondary attritional changes to the extensor tendons (Vaughan-Jackson syndrome) and volar subluxation of the ECU.

Without surgical intervention, the natural history of DRUJ derangement dictates progressive, painful limitation of forearm rotation. In cases of significant positive ulnar variance, secondary limitations in wrist flexion-extension and radioulnar deviation inevitably develop, accompanied by progressive carpal translation.

Clinical Evaluation

Patient History and Physical Findings

A meticulous clinical history is paramount. A prior history of wrist or forearm fracture, particularly those involving high-torque axial loads, should be documented. In the absence of trauma, congenital anomalies or inflammatory arthropathies must be considered. Occupational demands and specific functional deficits provide critical insight into the degree of impairment.

Physical examination typically reveals ulnar-sided wrist pain, diminished grip strength, and restricted forearm rotation. Pain is classically exacerbated by resisted pronation or supination. The examiner must systematically differentiate isolated DRUJ pathology from proximal radioulnar joint disease, interosseous membrane contracture, or ulnocarpal abutment.

Key provocative maneuvers include:
* Piano Key Test: Evaluates DRUJ instability; considered positive if ballottement of the distal ulna elicits pain, gross instability, or crepitus.
* Ulnocarpal Compression Test: Axial loading with ulnar deviation and rotation. A positive test reproduces ulnar-sided pain and grinding, indicative of TFCC pathology or ulnocarpal impaction.
* Lunotriquetral (Regan) Shuck Test: Assesses the integrity of the lunotriquetral interosseous ligament; positive if pain or excessive translation is noted.
* Selective Anesthetic Injections: Highly accurate for isolating intra-articular DRUJ pathology from extra-articular or ulnocarpal sources of pain.

Imaging and Diagnostic Studies

Standard radiographic evaluation includes neutral rotation posteroanterior (PA), lateral, and specialized ulnar variance views. If ulnocarpal abutment is suspected, a pronated grip-view PA radiograph maximizes dynamic positive ulnar variance.

Computed tomography (CT) is the gold standard for evaluating DRUJ subluxation, sigmoid notch morphology, and articular congruity. Axial cuts should be obtained simultaneously on both upper extremities in neutral, full pronation, and full supination. Magnetic resonance imaging (MRI), particularly with single-injection gadolinium arthrography, provides superior resolution for diagnosing TFCC tears and intrinsic intercarpal ligamentous disruptions.

Differential Diagnosis

• ECU tendinitis or subluxation
• Flexor carpi ulnaris (FCU) tendinitis
• Pisotriquetral osteoarthritis
• Lunotriquetral ligament tear
• TFCC peripheral or central tear
• Acute DRUJ dislocation
• Split ulnotriquetral ligament tear

Indications and Nonoperative Management

Nonoperative management is the initial step for mild to moderate DRUJ sprains and capsulitis. This includes rigid splinting, activity modification, NSAIDs, and targeted corticosteroid injections. Easily reducible, acute DRUJ dislocations may be managed with 6 weeks of cast immobilization in a position of stability.

Surgical intervention via the Sauvé-Kapandji procedure is indicated for patients with refractory pain, chronic instability, and established DRUJ arthritis who have failed conservative measures. It is imperative to distinguish ulnocarpal pain from DRUJ pain; the Sauvé-Kapandji procedure is contraindicated for a pain-free, stable DRUJ, even in the presence of radiographic abnormalities. Alternative surgical options include Darrach resection, hemiresection interposition arthroplasty, matched distal ulnar resection, and constrained or unconstrained prosthetic arthroplasty.

Preoperative Planning and Patient Positioning

Preoperative templating requires careful analysis of ulnar variance. In cases of marked positive ulnar variance, the surgeon must determine whether to perform the ulnar osteotomy prior to DRUJ fixation to allow proximal recession of the ulnar head, thereby restoring neutral variance and optimizing radioulnar congruity.

The patient is positioned supine with the operative extremity extended on a radiolucent hand table. A pneumatic tourniquet is applied to the proximal arm. Intraoperative fluoroscopy must be sterilely draped and readily available throughout the procedure.

Detailed Surgical Approach and Technique

Incision and Dissection

A 6 to 8 cm longitudinal incision is made along the ulnar border of the distal forearm. In patients with rheumatoid arthritis requiring concomitant dorsal tenosynovectomy or tendon transfers, a more dorsal incision may be utilized and extended obliquely.

The dorsal cutaneous branch of the ulnar nerve must be meticulously identified and protected throughout the procedure to prevent debilitating neuromas. The distal 4 to 6 cm of the ulna is exposed extraperiosteally through the internervous interval between the ECU and FCU. Extraperiosteal dissection is critical to minimize the risk of postoperative heterotopic ossification at the pseudoarthrosis site.

Identification and mobilization of the dorsal sensory branch of the ulnar nerve, tagged with a rubber vessel loop. Protection of this structure is paramount.

Osteotomy of the Ulnar Diaphysis

The osteotomy site is selected just proximal to the metaphyseal flare of the ulnar head, ensuring adequate distal bone stock to accommodate two fixation screws. Fluoroscopy confirms the appropriate level.

Measurement of the osteotomy resection. Preoperative ulnar variance dictates the exact length of the resection required to achieve neutral variance.

Two parallel osteotomy cuts are made using an oscillating microsaw to remove a 10- to 14-mm segment of the ulnar diaphysis. If positive ulnar variance is present, a correspondingly larger segment is resected to permit proximal translation of the ulnar head.

Execution of the proximal and distal osteotomies using an oscillating microsaw under continuous saline irrigation.

Removal of the resected ulnar segment. The underlying pronator quadratus muscle is carefully preserved for subsequent interposition.

The resected diaphyseal segment is retained and decorticated to harvest autologous cancellous bone graft, which will be utilized to augment the DRUJ arthrodesis.

Harvesting of cancellous bone from the resected ulnar diaphyseal segment.

Distal Radioulnar Joint Exposure and Preparation

The extensor retinaculum over the fifth dorsal compartment is incised, and the extensor digiti minimi is retracted radially. A dorsoulnar capsulotomy exposes the DRUJ articular surfaces. Using a sharp curette or high-speed burr, the articular cartilage of both the ulnar head and the sigmoid notch is completely denuded down to bleeding subchondral bone. The harvested cancellous autograft is then densely packed into the joint space.

Thorough curettage of the sigmoid notch to remove all residual cartilage, followed by packing of the autologous bone graft.

Fixation of the Arthrodesis

The ulnar head is manually compressed into the sigmoid notch in neutral rotation and neutral variance. Two parallel Kirschner wires are driven from the ulnar head into the distal radius to provisionally secure the arthrodesis.

A. Provisional stabilization of the ulnar head using two K-wires. B. Over-drilling with a cannulated bit for definitive screw fixation.

Cannulated screws are inserted over the K-wires. To prevent levering the ulnar head out of alignment, the distal screw is tightened first. Lag technique should be avoided on the proximal screw to prevent angular deformity; the ulnar head must remain strictly parallel to the longitudinal axis of the ulnar shaft.

Proximal Ulnar Stump Stabilization Techniques

To mitigate the risk of symptomatic proximal ulnar stump instability, soft tissue tenodesis is highly recommended.

ECU Tenodesis (Minami Technique):
A 3.5-mm drill hole is created in the dorsal aspect of the proximal ulnar stump. The ECU tendon is split longitudinally; the radial half is released distally, passed through the medullary canal of the proximal ulna, and sutured back upon itself.

Modification of the Sauvé-Kapandji procedure utilizing ECU tenodesis to stabilize the proximal ulnar stump.

FCU Tenodesis (Lamey and Fernandez Technique):
Alternatively, a distally based slip of the FCU tendon can be utilized to tether the proximal ulnar segment, preventing dorsal instability during forearm rotation.

Stabilization of the proximal ulnar segment using a distally based slip of the FCU tendon.

Wound Closure and Interposition

The pronator quadratus muscle is meticulously mobilized and sutured into the osteotomy gap. This interposition serves a dual purpose: it stabilizes the ulnar stump and provides a biologic barrier against heterotopic ossification across the pseudoarthrosis. The extensor retinaculum is subsequently repaired.

Suturing the pronator quadratus into the ulnar osteotomy gap.

Anatomical closure of the extensor retinaculum.

Technique for Severe Osteopenia (Fujita Modification)

In patients with advanced rheumatoid arthritis and severe osteopenia, standard screw fixation may fail. The Fujita modification utilizes the resected ulnar head as an autologous bone peg.

A. Longitudinal incision centered over the distal ulna.

B. Oblique osteotomy performed 30 mm proximal to the distal end of the ulna.

C. A 10-mm diameter hole is drilled into the sigmoid notch of the radius.

D. The resected ulnar segment is rotated 90 degrees, impacted into the radial drill hole, and secured with a single cancellous screw.

Complications and Management

The most prevalent complication following the Sauvé-Kapandji procedure relates to the proximal ulnar stump. Transient pain, radioulnar impingement, and a subjective sensation of instability are common but typically resolve within 3 months. If chronic symptomatic instability persists, salvage procedures utilizing dynamic ECU or FCU tenodesis are required. To minimize this risk, the osteotomy should be performed as distally as possible, excessive bone resection (>14 mm) must be avoided, and the interosseous membrane should be preserved.

Heterotopic ossification of the pseudoarthrosis site can lead to recurrent loss of rotation. Extraperiosteal resection of the ulnar diaphysis and robust interposition of the pronator quadratus are critical prophylactic measures. If mature ossification occurs, surgical excision followed by immediate postoperative mobilization is indicated.

Iatrogenic injury to the dorsal sensory