Radioulnar Ligaments Research Articles

The anatomy of the ulnocarpal complex

The ulnocarpal complex (triangular fibrocartilage complex; TFCC) represents an intricate system of structures which secures motion guidance, stability and pressure transmission in the ulnocarpal compartment of the wrist joint. Anatomically, this complex consists of the ulnocarpal disc (triangular disc), palmar and dorsal radioulnar ligaments, ulnolunate, ulnotriquetral and ulnocapitate ligaments, ulnocarpal meniscus homologue, ulnar recess (prestyloid recess), ulnocarpal collateral ligament and tendon sheath of the extensor carpi ulnaris. The distal radioulnar joint and the interosseous membrane of the forearm, which lie close together, also belong functionally to the ulnocarpal complex. Together with the proximal radioulnar joint, they permit rotational movements of the hand (pronation and supination). This review highlights all components of the ulnocarpal complex systematically. Distinctive characteristics involving size, as well as variations, are listed, and their functional meaning analyzed. The accumulated knowledge serves as a basis for possible interventions both at the ulnocarpal complex and the distal radioulnar joint.

Soft-tissue stabilizers of the distal radioulnar joint: an in vitro kinematic study

Purpose Distal radioulnar joint (DRUJ) stability is dependent on osseous anatomy, soft-tissue stabilizers, and muscle activity. The relative importance of DRUJ soft-tissue stabilizers remains controversial and has not been examined in the more physiologic setting of simulated muscle loading in the intact specimen. The purpose of this study was to examine the role of static stabilizers on the kinematics of the DRUJ during active simulated motion. Methods Twelve cadaveric upper extremities underwent computer-controlled, simulated, active forearm rotation. Joint kinematics were measured in the intact specimen and after sequential sectioning of soft-tissue stabilizers including the dorsal and palmar radioulnar ligaments (RULs) and the triangular fibrocartilage (TFC), dorsal and palmar capsule, ulnocarpal ligaments (UCL), extensor carpi ulnaris (ECU) subsheath, pronator quadratus (PQ), and the interosseous membrane (IOM). Results After sectioning of soft tissues significant changes in the DRUJ kinematics were observed. With a distal to proximal sectioning sequence significant alterations in kinematics were not identified until sectioning of the IOM; with a proximal to distal sectioning sequence intact DRUJ kinematics were maintained until the final soft-tissue (RULs and TFC) sectioning. Conclusions Sectioning of all soft-tissue stabilizers produced significant DRUJ instability and abnormal joint kinematics. The RULs and TFC play a key role in DRUJ kinematics because they can help to maintain normal joint rotation in the absence of all other soft-tissue stabilizers. With the preservation of other soft-tissue stabilizers, however, the RULs and TFC are not essential for the maintenance of normal kinematics of the DRUJ.

The use of a volar ulnar portal in wrist arthroscopy

Purpose The purpose of this study was to quantitatively describe the neurovascular relationships of a volar ulnar (VU) wrist arthroscopy portal. A second purpose was to evaluate whether the use of a VU portal identified additional pathology of the lunotriquetral ligament and ulnar sling mechanism that was not seen through the dorsal portals. Type of study This study was an anatomic study and retrospective chart review. Methods Cadaver dissections established the neurovascular anatomy of the VU portal. Measurements were taken from the portal to the ulnar nerve and artery, the palmar cutaneous branch of the ulnar nerve, and the pronator quadratus. A dorsal capsulotomy was performed to assess the ligamentous interval. A chart review was performed of 23 patients in whom a volar ulnar portal was used. Intraoperative pathology that was identified through the VU portal but was not visible through a dorsal portal was recorded. Postoperative neurovascular complications were noted. Results The portal was generally > 5 mm radial to the ulnar neurovascular bundle, but no true internervous plane was seen. Tears of the palmar aspect of the lunotriquetral ligament were seen in 7 patients. One patient had a triangular fibrocartilage tear that extended into the dorsal radioulnar ligament. Conclusions This study provides a safe, standardized approach to the volar ulnar aspects of the radiocarpal joint, which is useful for evaluation of the ulnar sling mechanism and the dorsal radioulnar ligament. The VU portal aids in the diagnosis and debridement of tears involving the palmar aspect of the lunotriquetral ligament. The VU portal should be considered for inclusion in the arthroscopic examination of any patient with ulnar sided wrist pain. Level of evidence Level IV.

The distal radioulnar joint as a load-bearing mechanism—a biomechanical study

Purpose A biomechanical study was performed to define the normal profiles of force transmission across the distal radioulnar joint (DRUJ) and their alteration as the result of surgical modification of the joint and its ligaments. Methods Twelve cadaver arms were used in this investigation. A custom-made jig was designed to hold the arm and allow axial loading of the hand. Force transmitted across the DRUJ was measured with sensor film. The axial force transmitted through the ulna and radius was measured with strain gauges mounted to the surface of each bone and the strain in the dorsal and volar distal radioulnar ligaments (DRUL) was measured with differential variable reluctance transducers. Measurements of force and strain with the DRUJ in the surgically unmodified condition were performed in various positions of forearm rotation and with sequential loads. Subsequently, the same series of measurements was performed after DRUL division and after reconstruction of the ligament. The effect of excision of the ulna head (Darrach’s procedure) was also studied. Results Force varied significantly (p < .05) with the applied load and with forearm position, being greater in supination than pronation (sensor film data). Force transmitted through the ulna varied in an approximately reciprocal pattern with that of the radius. The greatest forces through the ulna occurred in supination and therefore mirrored the change in force transmission across the DRUJ. Between 32% and 34%, respectively, of the applied load (5–10 kg) was transmitted through the ulna and the remainder was transmitted through the radius (strain gauge data). Division of either the volar or the dorsal DRUL tended to increase the force transmitted across the DRUJ (p = .09), and reconstruction of the disrupted DRUL restored the force pattern toward the previous values (not significant) (differential variable reluctance transducer data). Excision of the ulna head disrupted the force transmission profiles, producing the biomechanical equivalent of a 1-bone forearm. Only 1.8% and 2.7% of the applied force (10 kg and 5 kg), respectively, was transmitted through the ulna (strain gauge data only). Conclusions The data show consistent and characteristic force transmission profiles across the DRUJ and through both ulna and radius. The joint is important in the transmission of load and its anatomic integrity should be respected in surgical procedures if normal biomechanics are to be preserved.

Biomechanical function of the distal radioulnar and ulnocarpal wrist ligaments

Purpose: This study was designed to provide quantitative information concerning the functions of the ligaments that stabilize the distal radioulnar joint (DRUJ). This joint permits the radius to rotate around a nearly fixed ulna allowing supination and pronation of the hand. Understanding their function is important in developing procedures for reconstruction. Methods: Using a ligament tension transducer that hooked under the center of the ligament and deflected it laterally while measuring the force required, we determined the tensions in 6 ligaments in 9 cadaver arms in pronation and supination of the hand. These ligaments included those of the DRUJ: palmar distal radioulnar ligament (PDRUL) and dorsal distal radioulnar ligament (DDRUL); and the ulnocarpal joint ligaments: ulnolunate ligament (ULL), ulnotriquetral ligament (UTL), and the ulnocarpal collateral ligament (UCCL), which includes the subsheath of the extensor carpi ulnaris, and the dorsal ulnocarpal ligament (DUCL). Results: For the ligaments of the DRUJ in supination, the mean tension in the PDRUL (2.6 N) was greater than that of the DDRUL (0.8 N), whereas in pronation the mean tension in the PDRUL (1.1 N) was less than that of the DDRUL (1.7 N). For the ulnocarpal ligaments in supination, the ligament tensions in the ULL, UTL, and the UCCL were significantly greater than the same ligaments with the forearm pronated. The DUCL tension remained unchanged throughout supination and pronation. Conclusions: In supination of the forearm all ligaments except for the DDRUL had equivalent tensions, indicating their role in stabilizing the joint to this motion. In pronation ligament tensions generally were lower but were distributed over all 6 ligaments tested. DUCL tension was equivalent in both supination and pronation, unlike the other ligaments that had greater tensions in supination.

Treatment of distal radioulnar (RU) joint instability by reconstructing both palmar and dorsal RU ligaments with a tendon graft (adams technique)

Treatment of distal radioulnar (RU) joint instability by reconstructing both palmar and dorsal RU ligaments with a tendon graft (adams technique)

In Reply:

Dr. Strackee makes an accurate observation that the center of rotation was at the center of the osteotomy, a fact that was stated in the text of the article (page 40, line 1). His comments, however, are overreaching, unsupported, and not realistic. Wedge osteotomies were developed to minimize alteration of ulnar variation for the small group of patients with Kienböck's disease who are ulnar neutral or positive. No one claims that these osteotomies eliminate changes in ulnar variation. Certainly alterations can be minimized by placing the center of rotation as close as possible to the distal ulnar corner of the radius. Unfortunately in the clinical situation this places the osteotomy into the distal radioulnar joint. It also makes the distal radial fragment in the area of the lunate facet excessively thin, risking intra-articular fracture and nonunion. The degree of precision alluded to by Dr. Strackee is further hampered by the fact that the center of rotation is not the only variable that effects the postosteotomy geometry of the radius. The kerf of the saw blade removes 1 to 2 mm of bone. The distal radioulnar ligaments are another point of rotation in addition to the ulnar margin of the radius. The adjacent distal radioulnar joint is another constraint that may introduce translation of the distal radial fragment into the equation. Furthermore the distal radius is a 3-dimensional structure so the coronal angle of the osteotomy could induce changes in radiopalmar tilt. Finally, it is important to remember that biomechanics is only a theoretical part of the picture. I draw Dr. Strackee's attention to the physiologic issues such as joint denervation and surgically stimulated fibrovascular response recently reported on by Illarramendi et al. 1 Illarramendi AA Schulz C De Carli P The surgical treatment of Kienböck's disease by radius and ulna metaphyseal core decompression. J Hand Surg. 2001; 26A: 252-260 Google Scholar

Comprehensive management of soft-tissue injuries associated with distal radius fractures

Distal radius fractures can no longer be thought of in isolation. Increasing recognition is being given to the associated soft-tissue injuries that include: median nerve compression, radioulnar ligament injury, fibrocartilage disc substance tear, volar extrinsic ligament injury, dorsal extrinsic ligament injury, and intrinsic ligament injuries. Diagnosis, classification, and management of the associated soft-tissue injuries can be accomplished with a combination of endoscopic and arthroscopic techniques that balance well with current methods of distal radius fixation. The use of these less invasive but stable techniques facilitates an early rehabilitation program with the long-term goal of improved function. Copyright © 2002 by the American Society for Surgery of the Hand

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.

An analysis of the constraint properties of the distal radioulnar ligament attachments to the ulna.

Nine cadaver upper extremities were tested to evaluate the constraint properties of the dorsal and palmar radioulnar ligaments at their foveal and styloid attachments to the ulna. The specimens were tested by anterior and posterior displacement of the radius relative to the ulna with the forearm in pronation, supination, and neutral rotation. There were no statistically significant differences in the relative percent of constraint contribution of the styloid and foveal ligament insertions. In neutral forearm rotation total displacement after sectioning both ligament insertions tended to be larger in palmar than in dorsal displacement. A similar trend was observed with 60 degrees forearm supination. In the pronated position, however, the trend was reversed with larger total displacement in dorsal displacement.

In vitro experimental study of the effect of radial shortening and ulnar ostectomy on contact patterns in the elbow joint of dogs.

To determine effects of incremental radial shortening and subsequent ulnar ostectomies on joint surface contact patterns in a canine elbow joint model. Paired forelimbs from 9 adult dogs. Joint casting was performed by placement of colored polymethylmethacrylate in the elbow joint cavity and loading in a materials testing system at physiologic angle and load. Joint casting was performed in unaltered specimens, after radial shortening, and after subsequent distal ulnar ostectomy, proximal ulnar ostectomy, and proximal ulnar ostectomy with intramedullary pinning. Computer-aided analysis of photographs of proximal radial and ulnar articular surfaces without joint casts was performed before and after each casting procedure. All increments of radial shortening changed the size and location of radial and ulnar contact areas. The radial contact area became smaller, the anconeal contact area disappeared, the medial coronoid contact area migrated craniolaterally, and the lateral projection of the coronoid process became a contact area. A proximal ulnar ostectomy stabilized with an intramedullary pin restored normal contact area size and location and restored continuity of the radial and coronoid contact areas across the radioulnar articulation in 6 of 10 specimens. A midshaft ulnar ostectomy, distal to the level of the radioulnar ligament, had no effect on contact patterns. A proximal ulnar ostectomy without stabilization resulted in varus deformity during loading. Proximal radial shortening, which creates articular step incongruity, changes the location and size of the radioulnar contact areas. Dynamically stabilized ulnar ostectomies proximal to the radioulnar ligament restore contact patterns in vitro.

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 of the posttraumatic unstable distal radioulnar joint

Although not a common problem, the posttraumatic unstable distal radioulnar joint can be difficult to treat. This article focuses on the various methods for reconstruction of the unstable distal radioulnar joint. Attention focuses specifically on anatomic reconstruction of distal radioulnar ligaments. The authors' technique is presented in detail.

The Anatomy of the Ligaments of the Wrist and Distal Radioulnar Joints

The ligaments of the wrist are responsible for guiding and constraining the complex motion of the carpal bones relative to the forearm bones, the metacarpals, and contiguous carpal bones. The majority of wrist ligaments are found within the joint capsule as organized thickenings composed of parallel collagen fascicles, small caliber nerves and blood vessels, and lined on their deep surfaces by synoviocytes. The palmar radiocarpal ligament complex is composed of the radioscaphocapitate, long radiolunate, radioscapholunate and short radiolunate ligaments. The ulnocarpal ligaments include the ulnolunate, ulnotriquetral and ulnocapitate ligaments. Dorsally, the radiocarpal joint is spanned by the dorsal radiocarpal ligament. Palmar ligaments connecting the proximal and distal carpal rows include the scaphotrapeziotrapezoid, scaphocapitate, triquetrocapitate and triquetrohamate ligaments. Within each row are interosseous ligaments connecting adjacent carpal bones, each divisible into dorsal and palmar components. There are unique regions within some of the ligaments, such as a zone of fibrocartilage in the proximal regions of the scapholunate and lunotriquetral interosseous ligaments, and strong deep regions connecting the trapezoid, capitate, and hamate. The distal radioulnar joint is connected by the triangular fibrocartilage complex, composed of a fibrocartilaginous disc and the palmar and dorsal radioulnar ligaments. The ulnocarpal ligaments attach to the palmar radioulnar ligament rather than directly to the ulna, allowing increased independence between wrist and forearm motion.

Histological anatomy of the triangular fibrocartilage complex of the human wrist

The triangular fibrocartilage complex (TFCC) was studied in serial histological sections of the human wrist to reveal its three-dimensional fine structure. The TFCC consisted of a fibrocartilaginous disc proper and other fibrous components. Three-dimensionally, the distal portion of the TFCC had a hammock-like contour that partially surrounded the carpus; while the proximal ligamentous portion corresponding to the radioulnar ligament connected the radius to the ulna. The radioulnar ligament originated at the ulna from both the fovea and the basistyloid. The fibres first gathered and then bifurcated palmarly and dorsally, enclosing and partially coalescing with the proximal side of the disc before inserting around the distal rim of the sigmoid notch of the radius. The meniscus homologue, which corresponded to the ulnar internal wall of the wrist joint, was derived from a loose synovial fold adapting to the stresses from radioulnar deviation. The distal side of the disc consisted of a dense population of chondrocytes in a collagen matrix, while the proximal side was rather rich in fibres directed radioulnarly. Inside the TFCC were loose connective tissues. The histological arrangement of the TFCC is compatible with its function of supporting the carpus, stabilizing the joints and allowing smooth motion of the wrist.

The proximal ligamentous component of the triangular fibrocartilage complex: Functional anatomy and three-dimensional changes in length of the radioulnar ligament during pronation and supination

The proximal ligamentous component of the triangular fibrocartilage complex (TFCC) was studied anatomically using 15 fresh-frozen cadaver hand forearm specimens. Changes in the length of either side of this component were analysed during forearm rotation with the complete three-dimensional structure of the TFCC preserved. The proximal ligamentous component consists of three portions: dorsal, central and palmar. The dorsal and palmar portions connect the radius and ulna directly. These were recognized in all specimens whereas the central portion was not constant. The morphology of the proximal component was categorized into three types: fan-shaped, V-shaped, and funnel-shaped in five wrists each. Changes in ligament length during forearm rotation were measured using fine wires under slight tension that paralleled the ligaments from origin to insertion. The dorsal and palmar portions demonstrated three trends: the dorsal portion increased in length from supination to pronation whereas the palmar portion increased in length from pronation to supination; the length of the dorsal portion remained almost constant as the palmar portion increased in length from pronation to supination; the length of the palmar portion remained almost constant while the dorsal portion lengthened from supination to pronation. These variations appear to be related to which portion of the ligament was attached nearest to the centre of the ulnar fovea, where the rotational axis of the forearm passes. The portion attaching nearest to the fovea demonstrated a nearly isometric length pattern, whereas the portion which attached at a distance showed greater extensibility. These findings suggest that the proximal component of the TFCC corresponds to a true radioulnar ligament, and the isometric and eccentric fibres act mutually during forearm rotation.

The Proximal Ligamentous Component of the Triangular Fibrocartilage Complex

The proximal ligamentous component of the triangular fibrocartilage complex (TFCC) was studied anatomically using 15 fresh-frozen cadaver hand forearm specimens. Changes in the length of either side of this component were analysed during forearm rotation with the complete three-dimensional structure of the TFCC preserved. The proximal ligamentous component consists of three portions: dorsal, central and palmar. The dorsal and palmar portions connect the radius and ulna directly. These were recognized in all specimens whereas the central portion was not constant. The morphology of the proximal component was categorized into three types: fan-shaped, V-shaped, and funnel-shaped in five wrists each. Changes in ligament length during forearm rotation were measured using fine wires under slight tension that paralleled the ligaments from origin to insertion. The dorsal and palmar portions demonstrated three trends: the dorsal portion increased in length from supination to pronation whereas the palmar portion increased in length from pronation to supination; the length of the dorsal portion remained almost constant as the palmar portion increased in length from pronation to supination; the length of the palmar portion remained almost constant while the dorsal portion lengthened from supination to pronation. These variations appear to be related to which portion of the ligament was attached nearest to the centre of the ulnar fovea, where the rotational axis of the forearm passes. The portion attaching nearest to the fovea demonstrated a nearly isometric length pattern, whereas the portion which attached at a distance showed greater extensibility. These findings suggest that the proximal component of the TFCC corresponds to a true radioulnar ligament, and the isometric and eccentric fibres act mutually during forearm rotation.

The dorsopalmar stability of the distal radioulnar joint

Sixteen fresh-frozen adult human cadaveric upper extremities were used in a biomechanical analysis of distal radioulnar joint (DRUJ) stability. The relative contribution to stability of the DRUJ by the surrounding anatomic structures presumed to stabilize the joint was analyzed with respect to forearm rotation and wrist flexion and extension using a purpose-built 4-axis materials testing machine. The dominant structures stabilizing the DRUJ were the ligamentous components of the triangular fibrocartilage complex proper. The major constraint to dorsal translation of the distal ulna relative to the radius is the palmar radioulnar ligament. Palmar translation of the distal ulna relative to the radius is constrained primarily by the dorsal radioulnar ligament, with secondary constraint provided by the palmar radioulnar ligament and interosseous membrane. The ulnocarpal ligaments and extensor carpi ulnaris subsheath did not contribute significantly to DRUJ stability; however, approximately 20% of DRUJ constraint is provided by the articular contact of the radius and ulna. These relationships were consistent regardless of wrist position or degree of forearm rotation.

DYNAMIC RADIAL TRANSLATION INSTABILITY OF THE CARPUS

We report a case of a dynamic radial translation instability of the carpus, secondary to avulsion of the ulnocarpal ligaments and attenuation of the short radiolunate ligament. In addition, there was a peripheral detachment of the distal radioulnar ligaments causing distal radioulnar instability. Reattachment of the avulsed ligaments combined with a Sauvé-Kapandji procedure resulted in an excellent function, which was maintained 10 years after surgery.

Biomechanical aspects of malunited distal radius fracture. A review of the literature

One of the most common injuries in orthopaedics is the distal radius fracture. Malunion may lead to pain, limited motion, and loss of grip strength. Presently there is no consensus concerning the indications for corrective surgery after malunion. Studies concerning the biomechanics of the wrist in cases of malunited radius fracture can be helpful. Analysis of the literature of the last ten years. In laboratory studies, malalignment of the radius caused alterations of the distal radioulnar joint (anatomically: reduction of the radioulnar contact area, disruption of the deep portion of the dorsal radioulnar ligament, tightness of the triangular fibrocartilage complex; functionally: limited forearm pronation and supination). Further alterations have been found concerning the carpal kinematics, the force transmission through the wrist, the pressure distribution on the articular surface of the radius and the median nerve. Attempts should be made to obtain an anatomic reduction of all acute distal radius fractures. Posttraumatic disability of the wrist following malunion in radius fractures should accordingly be treated by a corrective osteotomy of the radius at the original fracture site.