Sigmoid notch osteotomy for posttraumatic dorsal dislocation of the distal radioulnar joint: A case report

Instability of the distal radioulnar joint (DRUJ) is associated most commonly with injury to the soft-tissue restraints of that joint, particularly the triangular fibrocartilage complex. The dorsal rim of the sigmoid notch, however, also plays an important role as a bony restraint to dorsal subluxation. We report a case of posttraumatic dorsal dislocation of the DRUJ associated with a depressed fracture of the dorsal rim of the sigmoid notch. This was treated with soft-tissue release and corrective osteotomy of the dorsal rim of the sigmoid notch to restore DRUJ stability and congruency.     

Ulnar styloid fixation in the treatment of posttraumatic instability of the radioulnar joint: a biomechanical study with clinical correlation

Biomechanical displacement testing was done on nine fresh human upper extremities to define the stabilizing influence of the triangular fibrocartilage on the radioulnar joint and the efficacy of triangular fibrocartilage-ulnar styloid avulsion fracture repair in restoring lost stability. Test data confirmed that the triangular fibrocartilage is a major stabilizer of the radioulnar joint and internal fixation of triangular fibrocartilage-ulnar styloid avulsion fractures can restore preavulsion stability in all positions of forearm rotation. On the basis of this data and a successful clinical experience, primary repair of displaced ulnar styloid avulsion fractures is advised as a means of stabilizing the radioulnar joint and preventing the disability associated with chronic radioulnar joint instability.     

Irreducible fracture-dislocation of the distal radioulnar joint secondary to entrapment of the extensor carpi ulnaris tendon

Entrapment of the extensor carpi ulnaris (ECU) tendon between the ulnar head and the sigmoid notch of the radius occurred in a 12-year-old boy. This led to an irreducible dorsal dislocation of the distal radioulnar joint (DRUJ). Irreducible DRUJ dislocations are uncommon, and the entrapped ECU has not been previously described in a skeletally immature patient. The physical and roentgenographic findings of a dorsally displaced ulna, a widened DRUJ, and the inability to obtain a closed reduction should alert the examiner to the need for exploration. A dorsal exposure is required to free the ECU and reconstruct the triangular fibrocartilage complex.     

Biomechanics of the distal radioulnar joint.

The distal radioulnar joint (DRUJ) is a complex joint involved in pronosupination and ulnocarpal motion and support. The ulnar head, in a rolling, sliding motion, moves from the dorsal to the volar rim of the sigmoid notch as the joint moves from pronation to supination. The triangular fibrocartilage (TFC) is taut first dorsally and then volarly in the same sequence. The ulnar carpus is supported variably, as a function of ulnar length relative to the radial articular surface, by the pole of the distal ulna through the TFC. The TFC does not resist the pistonlike movement of the DRUJ, which occurs under dynamic loading. The coronal alignment of the DRUJ minimizes shear stress on the articular surfaces because of its alignment with the rotational axis of the forearm. Ulnar variance is a factor in the development of several clinical conditions.     

Extensor tendon rupture associated with osteoarthritis of the distal radioulnar joint

Non-rheumatoid osteoarthritis of the distal radioulnar joint can cause extensor tendon rupture. We analysed the radiographic morphology of the distal radioulnar joint to identify the risk factors for this complication. Forty-one wrist X-rays of 37 patients with extensor tendon rupture caused by distal radioulnar joint osteoarthritis were evaluated retrospectively for the severity of osteoarthritis by the Kellgren/Lawrence scoring system. Measurements were obtained from posteroanterior views. All but one wrist had severe osteoarthritic changes exceeding grade 3. The radiographic features that were different from those of the contralateral wrists included deepening and widening of the sigmoid notch, radial shift of the ulnar head and dorsal inclination of the sigmoid notch. There was no significant association between tendon rupture and the morphology of the ulnar head or ulnar variance. The scallop sign, dorsal inclination of the sigmoid notch and radial shift of the ulnar head are radiological risk factors for extensor tendon ruptures.     

Reconstruction of the ulnar head with a vascularized second metatarsal head: case report

A case of a young patient with avascular necrosis of the ulnar head following a severely displaced ulnar head fracture is presented. Treatment included debridement of the entire ulnar head, leaving the ulnar styloid, sigmoid notch, triangular fibrocartilage, and both distal radioulnar ligaments intact. The head of the ulna was reconstructed by transferring a vascularized second metatarsal head. At 4-year follow-up, the patient had a pain-free wrist with 45° active pronation and 65° supination. He resumed working without limitations as a manual laborer. We conclude that ulnar head reconstruction with a vascularized second metatarsal head is worthwhile in the setting of an unreconstructable traumatic defect, particularly when the sigmoid notch and distal radioulnar ligaments are preserved.     

Open repair of the ulnar disruption of the triangular fibrocartilage complex with double three-dimensional mattress suturing technique

Open repair technique of the ulnar disruption of the triangular fibrocartilage complex is described. This technique is indicated for a fresh or a relatively fresh (less than 1 year after the initial injury) ulnar foveal detachment tear, horizontal tear, and proximal slit tear of the triangular fibrocartilage complex, all of which are accompanied by severe dorsal, palmar, or multidirectional instability of the distal radioulnar joint. A chronic tear greater than 1 year from initial injury and a fresh triangular fibrocartilage complex tear without distal radioulnar joint instability, such as central slit tear, are excluded from our indications. A dorsal C-shaped skin incision, a longitudinal incision of the radial edge of the extensor carpi ulnaris subsheath and the dorsal distal radioulnar joint capsule, exposes the distal radioulnar joint. A small, 5-mm longitudinal incision at the origin of the radioulnar ligament exposes its fovea detachment and/or the proximal slit tear of the triangular fibrocartilage complex. The disrupted radioulnar ligament is sutured in a pullout fashion to the ulna with a 3-dimensional double mattress technique through 2 bone tunnels that is precisely made at the central portion of the fovea with 1.2-mm K-wire. An additional horizontal mattress suture is used for closure of the small incision made at the radioulnar ligament, then the extensor carpi ulnaris is repaired. This open-repair technique is complex and requires precise technical skills; however, early results have been more rewarding than the conservative treatment.     

Distal radioulnar joint instability in distal radius fractures: the role of sigmoid notch and triangular fibrocartilage complex revisited

The stabilising effects of various structures of the distal radioulnar joint (DRUJ) have been heavily debated. This biomechanical cadaveric study examined the effects of the volar and dorsal lips of the sigmoid notch and the volar and dorsal aspects of the triangular fibrocartilage complex (TFCC) on DRUJ stability. Sequential fractures of the distal radius and sectioning of the TFCC were performed followed by measurements of ulnar translation with the forearm in pronation, neutral and supination. A dorsal lunate facet fracture created instability in pronation. Lunate facet fractures alone did not create instability in other forearm positions. Sectioning of the volar TFCC after loss of the dorsal TFCC by a dorsal lunate facet fracture caused DRUJ instability with the forearm in neutral position. Sectioning of the dorsal TFCC after loss of the volar TFCC due to a volar lunate facet fracture created instability in neutral and pronated positions.     

Origins and insertions of the triangular fibrocartilage complex: a histological study

The origins and insertions of the triangular fibrocartilage complex (TFCC) were examined histologically in serially sectioned fresh-frozen cadaver wrists. The radioulnar ligament arose vertically through Sharpey's fibres from a broad area in the ulnar fovea and more horizontally from a narrow area at the base of the ulnar styloid. The floor of the extensor carpi ulnaris sheath also originated firmly from the dorsal side of the fovea of the ulna, through an arrangement of Sharpey's fibres. Loose ulnocarpally oriented fibres, corresponding to a thickened ulnar joint capsule, arose from the hyaline-like cartilage matrix at the tip of the ulnar styloid and inserted onto the triquetrum without Sharpey's fibres. The ulnolunate and ulnotriquetral ligaments originated not from the ulna, but from the palmar side of the TFCC. The insertion of the TFCC into the sigmoid notch of the radius demonstrated a central transition from the fibrocartilaginous disc into hyaline cartilage and a firmer fibroosseous transition of the dorsal and palmar portions of the radioulnar ligament at the periphery.     

Reconstruction for DRUJ Instability

The skeletal architecture of the DRUJ provides minimal inherent stability, as the sigmoid notch is shallow and its radius of curvature is 50% greater than that of the ulnar head [Af Ekenstam F, Hagert CG. Anatomical studies on the geometry and stability of the distal radio ulnar joint. Scand J Plast Reconstr Surg 1985;19(1):17–25]. Due to its incongruent articulation, the DRUJ relies strongly on the surrounding soft tissues for stability. The triangular fibrocartilage complex (TFCC) is generally accepted as the major soft tissue stabilizer of the DRUJ of which the volar and dorsal radioulnar ligaments are the primary components. Restoration of the radioulnar ligaments offers the best possibility to restore the normal DRUJ primary constraints and kinematics. This article presents an update of the procedure developed by the senior author that anatomically reconstructs the palmar and dorsal radioulnar ligaments at their anatomic origins and insertions.     

The distal radioulnar ligaments: a biomechanical study.

The mechanical roles of the triangular fibrocartilage have been examined in three experiments. Kinematic analysis by a stereophotogrammetric method revealed that the palmar radioulnar ligament was taut in supination and that the dorsal radioulnar ligament was taut in pronation. In full pronation, the palmar radioulnar ligament decreased to an average of 71% of its length in tension. In full supination, the dorsal radioulnar ligament decreased to an average of 90% of its length. Mechanical testing of the triangular fibrocartilage under axial load disclosed a significant laxity (mean: 10.4 mm), which was decreased in pronation. Transverse loading tests demonstrated that the triangular fibrocartilage is less stiff in neutral forearm rotation. Study of the material properties of the palmar and dorsal parts of the triangular fibrocartilage showed these structures to be strong ligaments with material properties similar to those of the radiocarpal ligaments.     

Distal ulnar recession for disorders of the distal radioulnar joint

Thirty-six wrists of 35 patients were treated with distal ulnar recession for pain and limitation of motion associated with chondromalacia of the ulnar head, triangular fibrocartilage complex tears, ulnocarpal impingement, and instability of the distal radioulnar joint. Contributing factors were positive ulnar variance in 31 wrists, fracture of the distal radius in five, sprains in 14, premature closure of the distal radial epiphysis in five, and lax ligamentous habitus in five. The ages of the patients averaged 33 years. Clinical findings were local tenderness, crepitus, and instability evident by a positive "piano key" effect. Roentgenographic findings were positive ulnar variance (29 of 36), zero ulnar variance (four), negative ulnar variance (three), positive arthrogram (11 of 19), and "forme fruste" Madelung's deformity (two). The surgical procedure is a modification of the Milch cuff resection with the use of a dynamic compression plate. Recession ranged from 2 to 13 mm (average of 4 mm). Findings at surgery included chondromalacia of the ulnar head (19), tears of the triangular fibrocartilage complex (11), and excessive mobility of the ulnar head (10). At an average follow-up of 24.5 months, results were excellent in 7 wrists, good in 21, fair in four, and poor in four. Poor results in two wrists were upgraded to good after osteosynthesis of a nonunion in one and recessional osteotomy of the radial sigmoid notch in the other. Ulnar recession offers a less destructive alternative to disorders of the distal radioulnar joint than the Darrach resection.     

An anatomic reconstruction of the distal radioulnar ligaments for posttraumatic distal radioulnar joint instability

Fourteen patients with posttraumatic distal radioulnar joint instability were treated with a reconstruction of the distal radioulnar ligaments. The technique is anatomically accurate, is reproducible, and requires less dissection than previously described techniques. Candidates for the procedure had joint instability and an irreparable triangular fibrocartilage complex. Ten patients had bidirectional instability. Two patients had a concurrent corrective osteotomy of the distal radius for a malunion. The procedure restored stability and relieved symptoms in 12 of 14 patients at 1 to 4 years' follow-up evaluation. One patient with a deficient sigmoid notch and one with ulnocarpal ligament injury did not achieve full stability. All patients attained near full pronation and supination. The procedure is an effective treatment for an unstable distal radioulnar joint when its articular surfaces are intact and the other wrist ligaments are functional, and it can be used in combination with a distal radius corrective osteotomy.     

The value of plain X-rays in predicting TFCC injury after distal radial fractures

In this prospective study, the plain X-rays and MRI scans of 60 patients with intraarticular distal radius fractures were examined in random order. MRI evaluation revealed that 27 of the 60 patients (45%) had triangular fibrocartilage lesions. No correlation was found between triangular fibrocartilage injury and the Melone classification system, the presence of an ulnar styloid fracture, comminution of the articular surface of the distal radius, >20 degrees dorsal angulation of the distal radius or subluxation/dislocation of the distal radioulnar joint on the plain X-rays. When Frykman Type VI and VIII fractures were compared with all the other Frykman subtypes, a significant difference in the incidence of triangular fibrocartilage complex tears was observed. We conclude that triangular fibrocartilage injury should be considered with all distal radial fractures, especially the Frykman Types VI and VIII.     

The congruence of the distal radioulnar joint

The functional anatomy of the distal radioulnar joint was studied in 10 healthy volunteers. The joint surfaces of both the ulnar head and the sigmoid notch of the radius form arcs of circles with small areas of contact because the diameters of the circles are different. The distal radioulnar joint is congruent throughout its range of motion, but the area of contact shifts from dorsal in the sigmoid notch in pronation to volar in supination. The insertion of the distal radioulnar ligaments on the ulnar head explains the congruence of the joint.     

Pressures in the distal radioulnar joint: effect of surgical procedures used for Kienbock's disease

Radial shortening and ulnar lengthening are two accepted surgical methods for treating Kienbock's disease. The effect of these procedures on the pressure within the distal radioulnar joint between the ulnar head and the sigmoid notch of the radius was experimentally evaluated in six fresh cadaver forearms. Radical shortening and ulnar lengthening led to increased pressure at the distal radioulnar articulation and caused shifting of the location of the center of pressure distally within the sigmoid notch. Radial displacement of the distal radial fragment at the time of radial shortening, however, decreased the peak pressures. Based on these experimental data, ulnar lengthening and radial shortening can be expected to alter the normal biomechanics of the distal radioulnar joint.     

Ulnar lengthening and shortening

Alteration in length of the distal ulna may provide an attractive alternative to more destructive procedures commonly used for the treatment of mechanical and degenerative problems at the distal radioulnar joint. Ulnar recession has shown effectiveness in ulnolunate impingement, triangular fibrocartilage tears, and symptomatic ulnar plus variance. It has also been effective in chondromalacia of the ulnar head in the sigmoid notch and in unstable distal radioulnar joints where recession alters the bearing surface and tightens the ulnocarpal ligamentous complex. Ulnar lengthening has been efficacious in relieving the symptoms of Kienb?ck's disease by decompressing the involved portion of the lunate and distributing joint compressive force on the triquetrum and medial lunate articular surfaces. It may also be of value in some instances of NDCI associated with an ulnar minus variant.     

Distal radioulnar joint arthroscopy and the volar ulnar portal

Pain on the ulnar side of the wrist remains poorly understood. As attention has shifted toward the myriad causes of ulnar-sided wrist pain, the utility of viewing the wrist from a volar ulnar (VU) perspective has emerged. Lunotriquetral ligament tears have been implicated in the pathogenesis of volar intercalated segmental instabilities. They often originate in the palmar subregion, which is most important for maintaining stability. These tears are difficult to visualize through the 4, 5, or 6R portals. They are well seen through a VU portal, and the direct line of sight facilitates debridement. The VU portal has potential use in the arthroscopic diagnosis and treatment of patients with injuries to the ulnar sling mechanism. It aids in triangular fibrocartilage repairs especially those involving the dorsal aspect between the ulnar styloid and the radial insertion, because the proximity of the 4, 5, and 6R portals makes triangulation of the instruments difficult. Although arthroscopy of the dorsal aspect of the distal radioulnar joint has been well described, it has largely remained a curiosity, with few clinical indications. Recent biomechanical studies have highlighted the importance of the deep attachment of the triangular fibrocartilage complex in maintaining distal radioulnar joint stability. The volar distal radioulnar portal is useful for assessing the foveal attachment. It may be used where there is the suspicion of a peripheral triangular fibrocartilage detachment due to a loss of its normal tension despite the lack of a visible tear during radiocarpal arthroscopy. The judicious use of these portals deserves consideration for inclusion as part of a thorough arthroscopic examination of selected patients with ulnar-sided wrist pain.     

The congruence of the distal radioulnar joint. A magnetic resonance imaging study

The functional anatomy of the distal radioulnar joint was studied in 10 healthy volunteers. The joint surface of both the ulnar head and the sigmoid notch of the radius form arcs of circles with small areas of contact because the diameters of the circles are different. The distal radioulnar joint is congruent throughout its range of motion, but the area of contact shifts from dorsal in the sigmoid notch in pronation to volar in supination. The insertion of the distal radioulnar ligaments on the ulnar head explains the congruence of the joint.     

三角纤维软骨复合体解剖及生物力学研究

目的从解剖完整的腕关节入手,阐明三角纤维软骨复合体各组成部分的解剖特点,评估三角纤维软骨复合体(TFCC)对于维持远侧桡尺关节稳定的重要性。方法对8个新鲜解冻的腕关节和6个经甲醛浸泡的腕关节进行显微解剖。同时对影响远侧桡尺关节稳定性的因素作了初步的评估。前臂中旋位,垂直于尺骨予20N拉力下测量尺骨相对于桡骨的位移,然后先后切断掌背侧桡尺韧带,测量尺骨相对于桡骨的位移变化。结果发现掌背桡尺韧带由三角纤维软骨盘外周增厚而成,止于尺骨茎突基底部,是维持远侧桡尺关节稳定性的主要因素之一,切断掌背侧桡尺韧带会导致远侧桡尺关节明显不稳。结论TFCC由三角纤维软骨盘、掌背侧桡尺韧带、尺骨月骨韧带、尺骨三角骨韧带、尺侧腕伸肌下腱鞘、半月板同源物、尺侧囊组成。掌背桡尺韧带是维持远侧桡尺关节稳定性的主要因素之一,掌背侧桡尺韧带损伤会导致远侧桡尺关节明显不稳。