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.     

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 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.     

The role of the distal radioulnar ligaments, interosseous membrane, and joint capsule in distal radioulnar joint stability

The individual contribution of the distal radioulnar ligaments to dorsal and palmar translational stability during forearm rotation remains controversial. Furthermore, the role of the distal radioulnar joint capsule as a restraint and contributor to stability has not been investigated. A biomechanical study was performed in 11 fresh cadaver specimens to simultaneously measure dorsal and palmar radioulnar ligament tension. Joint rotation and radial translation were measured after sequential excision of the disk, interosseous membrane, joint capsule, and radioulnar ligaments. Results confirmed that the dorsal ligament tightens during pronation while the palmar ligament becomes progressively lax; the converse occurred during supination. Translational stability remained intact at all positions throughout the sectioning sequence until one of the radioulnar ligaments was sectioned. The most significant increases in translation occurred after sectioning the dorsal radioulnar ligament in pronation and after sectioning the palmar radioulnar ligament in supination. Forearm rotation increased significantly after excising either hemicapsule.     

Anatomic reconstruction of the distal radioulnar ligaments: long-term results

Chronic post-traumatic dynamic distal radioulnar joint instability following rupture of the distal radioulnar ligaments may cause disabling and progressive ulnar-sided wrist symptoms. We use a free tendon graft to anatomically reconstruct both dorsal and palmar distal radioulnar ligaments simultaneously. Nine patients who underwent this procedure between 1990 and 1997 were assessed using a modified Mayo Wrist Score. Following surgery, average wrist scores improved from 66 (95% CI, +/-3.0) to 92 (95% CI, 92+/-6.9) and were maintained in the long term (average score, 87 at 9 years). Joint stability was restored and maintained in seven of the nine patients, but two developed recurrent instability. Pain, grip strength and function were better following surgery in the short and long term. Range of supination and pronation decreased slightly from an average of 169 degrees pre-operatively to 155 degrees (90% of normal) in the long term. Long-term radiographs show no distal radioulnar or ulnocarpal joint osteoarthritis.     

Simultaneous dislocations of the radiocapitellar and distal radioulnar joints

Posttraumatic instability of the distal radioulnar joint (DRUJ), occurring in isolation or in association with fractures of the radius, is well-documented. Few reports have identified simultaneous ipsilateral DRUJ instability and elbow dislocation. The authors of the present study describe a case of persistent radiocapitellar subluxation after closed reduction of an elbow dislocation, secondary to irreducible volar subluxation of the DRUJ.     

韧带解剖重建术治疗慢性远尺桡关节不稳定

 目的介绍自体掌长肌腱移植、远尺桡韧带解剖重建的适应证、手术方法 及治疗慢性远尺 桡关节(distal radioulnar joint, DRUJ)不稳定的初期随访结果 。方法 2008年 10月至 2009年 6月, 应用 自体掌长肌腱移植、远尺桡韧带解剖重建术治疗 6例慢性 DRUJ不稳定患者。平均年龄 22岁。男 4例, 女 2例。术中取腕背第四、五伸肌鞘管间纵行切口。切开鞘管, 显露 DRUJ背侧部分。横野L冶形切开远尺 桡背侧关节囊, 显露 DRUJ和三角纤维软骨盘。于桡骨远端尺背侧, 距离月骨窝和乙状切迹各约 5 mm 处钻孔。在尺侧腕屈肌腱桡侧做掌侧纵行切口, 切取全长掌长肌腱, 将其一端通过桡骨隧道穿至掌侧, 再用止血钳经三角纤维软骨盘下方透过掌侧关节囊, 将其引至背侧。在尺骨颈和茎突隐窝之间钻孔。将 肌腱两个断端经尺骨隧道引至尺骨颈处, 再把其中一端绕过尺骨颈。将前臂置于中立位, 抽紧缝合肌腱。 术后长臂石膏固定前臂于中立位。 4周后更换为前臂石膏, 继续制动 4周。结果 所有患者术后均获得 9~24个月随访, 平均 14个月。术后没有感染及感觉神经支损伤等并发症。疼痛减轻, 握力增加。采用改 良 Mayo评分评估腕关节功能: 术前平均 69分, 术后平均 95分。 5例患者对手术结果 满意。结论 韧 带解剖重建术适用于无骨性关节炎的慢性 DRUJ不稳定, 术后腕关节功能改善明显。     

腕尺桡偏运动时腕韧带长度变化的活体研究

目的 研究腕关节在尺桡偏运动过程中,腕关节韧带长度的变化.方法 对6名志愿者腕关节进行CT扫描,获得腕关节在桡偏20°至尺偏40°内每隔20°的运动范围内各腕骨及尺桡骨远段三维重建图像.男3名,女3名,仅研究单侧右侧腕关节.年龄20～32岁,平均24岁.在腕关节尺桡偏运动过程中,在重建各腕骨及尺桡骨结构图像上以软件测量掌、背侧腕韧带的长度.结果 腕关节尺偏时桡舟头韧带、长桡月韧带、背侧腕间韧带止于舟骨、大多角骨和小多角骨部分的长度较中立位显著伸长,分别伸长(2.4±0.3)mm、(2.3±0.8)mm、(1.2±0.6)mm、(1.2±1.2)mm与(2.6±1.0)mm,差异均有统计学意义(P＜0.05);腕关节桡偏时尺头韧带与背侧桡腕韧带长度显著伸长(P＜0.05),分别为(0.8±0.6)mm和(1.0±0.5)mm.结论 在腕关节尺桡偏运动时,桡舟头韧带、长桡月韧带、背侧腕间韧带于桡偏位缩短,尺头韧带、背侧桡腕韧带长度于尺偏位缩短.这些位置可能使不同腕韧带张力降低,有利于损伤韧带的修复.     

Detailed anatomy of the articular disc of the distal radioulnar joint

The articular disc of the distal radioulnar joint anatomy was studied in 109 wrist joints from 64 fresh adult cadavers. The disc is a strong fibrocartilaginous semicircular biconcave structure well adapted to its various functional roles. The length of the disc at its radial attachment varied between 12 and 20 mm (in most cases, 14-16 mm), and the width, measured between the apex and the radial base, varied from 7 to 14 mm, (in most cases, 9-11 mm). The thickness of the dorsal and palmar margins and the ulnar apex varied from 3 to 6 mm (in most cases, 4-5 mm), whereas the thickness of the central part varied from 0.5 to 3 mm (in most cases, 1 mm) and in a number of cases was perforated. Because the incidence of perforations increases progressively with the age of the subjects, the perforations were assumed to be degenerative in nature. Although the articular disc is a definable anatomic entity, it is intimately attached to surrounding elements to form a complex anatomic and functional structure.     

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function.

The purpose of this study was to examine the anatomy and mechanical properties of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist and to better understand the functional design of the dorsal ligaments. The DRC ligament was consistently found to originate from the dorsal margin of the distal radius and extended ulnar obliquely and distally. Its radial fibers attached to the lunate and lunotriquetral interosseous ligament. The DRC ligament then inserted onto the dorsal tubercle of the triquetrum. The DIC ligament originated from the triquetrum and extended radially and attached onto the lunate, inserted into the dorsal groove of the scaphoid, and then extended to the trapezium. The DRC and DIC ligaments together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length by changing the angle between the 2 arms of the V. The DRC-DIC ligaments' lateral V configuration allows normal carpal kinematics while maintaining its indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist.     

The ligaments of the wrist.

The ligaments of the wrist were studied by dissecting ten fixed and seven fresh frozen wrists. In three other specimens multiple cross-sections were prepared. These studies show that the wrist ligaments can be classified into two groups: extrinsic and intrinsic. In the extrinsic group, the deep volar radiocarpal ligaments are three strong and very important structures connecting the radius to the capitate, the radius to the lunate, and, in a deeper layer, the radius to both the scaphoid and the lunate. A ligamentous deficiency was noted frequently between the capitate and the lunate. There also are very strong volar connections between the radius and the medial or ulnar carpus. These studies suggest that certain patients with a generalized ligamentous laxity and weakness will develop a pathological disruption of the volar ligaments with trauma. These torn volar ligaments should be repaired or reconstructed, for repair of only the dorsal ligaments seldom will provide good stability to such wrists.     

The distal radioulnar joint

Reconstructive surgery of the distal radioulnar joint should be considered for those in the age range of 20 to 50 years, particularly in those patients having sustained a high-energy injury and in cases where there is a great demand on the wrist joint for heavy work and sports activities. Meticulous preoperative planning in terms of correct clinical and radiologic evaluation and strict adherence to restoration of the joint congruency and restoration of ligament function are most important in obtaining reliable, long-term results in the vast majority of patients.     

The dorsal ligaments of the wrist

The anatomy and function of the dorsal ligaments of the wrist have received increased attention over the past decade. The anatomy, variability, osseous attachments, and function of the dorsal radiocarpal (DRC) and the dorsal intercarpal (DIC) ligaments have been studied. More detailed anatomic and mechanical studies of the subregions of the intercarpal ligaments have also been recently reported. The DRC and the DIC form a lateral V configuration that allows normal carpal kinematics while maintaining an indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist. The DRC and the DIC together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length three-fold by changing the angle between two arms of the V.     

The palmar radiocarpal ligaments: A study of adult and fetal human wrist joints

The palmar radiocarpal ligaments were studied with use of fifty-four dissected adult cadaver wrists and serial sections on twenty-three wrists from fetuses ranging in size from 23 to 230 millimeters crown-rump length. Three palmar radiocarpal ligaments were clearly identified: the radioscaphocapitate, long radiolunate, and short radiolunate ligaments. The radioscaphocapitate ligament originates from the radial styloid process and inserts into the radial aspect of the waist of the scaphoid, hemicircumferentially around the distal pole of the scaphoid and interdigitates with fibers from the palmar aspect of the triangular fibrocartilage complex just palmar to the head of the capitate, with only a minor insertion distally into the body of the capitate. The long radiolunate ligament originates just ulnar to the radioscaphocapitate ligament, being separated from it throughout its course by the interligamentous sulcus. The long radiolunate supports, but is separate from, the palmar aspect of the scapholunate interosseous ligament, and inserts into the radial half of the palmar surface of the lunate. The short radiolunate ligament, previously not described, originates just palmar to the lunate facet of the distal radius articular surface and inserts as a flat sheet of fibers into the proximal margin of the palmar surface of the lunate. Each ligament is intracapsular, enveloped within a continuous superficial fibrous stratum and deep synovial stratum.     

Simultaneous dislocation of the proximal and distal radioulnar joints: A case report

A 34-year-old man was struck on his left arm by a heavy piece of wood. Clinical and radiographic examinations revealed anterior dislocation of the radial head and palmar dislocation of the ulnar head. Under general anesthesia both dislocations were reduced and the arm was immobilized in a plaster cast in supination for 5 weeks. 5 months after the injury, the patient had normal motion in both the wrist and elbow and returned to his previous occupation as a wood-cutter. At reexamination 4 years later, he had no pain and no instability in his wrist or elbow.     

Dislocation of the distal radioulnar joint: anatomy and clues to prompt diagnosis

The articular disk is a strong, complex structure responsible for the stability of the distal radioulnar joint. It is injured by a hyperpronation or hypersupination injury which disrupts the disk or its strong central attachment to the ulna. Prompt diagnosis is essential for a good result as no good late reconstruction is available. Reliance on radiographs for the diagnosis will seldom be rewarding, and they are mainly of value in ruling out associated fractures. A careful clinical examination and a high index of suspicion are the best tools available for diagnosis in this injury.     

An effective method of reconstructing posttraumatic dorsal dislocated distal radioulnar joints

A new method of reconstructing a posttraumatic dorsally dislocated distal radioulnar joint with use of a long, distally attached palmaris longus tendon strip is described. This sling holds the dislocated distal ulna radially and volarward. Long-term results have been excellent.     

Kinematic analysis of the distal radioulnar joint after a simulated progressive ulnar-sided wrist injury

A kinematic analysis of a progressive, ulnar-sided wrist injury was performed using a cadaver model to study the static and dynamic stabilizers of the distal radioulnar joint with a 3-dimensional motion tracking system. Anatomically based loads were applied to achieve pronation and supination and then the specimens were evaluated after serial transection of the triangular fibrocartilage, the extensor carpi ulnaris sheath, and the ulnocarpal ligaments. Statistically significant increases in translation of the radius relative to the ulna occurred with sectioning of both the triangular fibrocartilage proper and the extensor carpi ulnaris tendon sheath. No significant change in position of the forearm could be appreciated with subsequent sectioning of the ulnocarpal ligaments. Our observations support the idea that the ulnocarpal ligaments do not need to be surgically reconstructed when there are serious injuries to the triangular fibrocartilage complex.     

The anatomy of the proximal radioulnar joint

This study is an anatomic investigation to define the architecture of and the stabilizing structures for the proximal radioulnar joint. Ten fresh-frozen cadaver elbows were dissected. Measurements of the radial head, annular ligament, radial fossa of the ulna, and interosseous membrane were made and were correlated to clinical observations of elbow stability. Sequential transection of the soft tissue constraints of the proximal radioulnar joint demonstrated the annular ligament and the central band of the interosseous membrane to be the main stabilizers in pronation and the central band to be the significant stabilizer in supination. Eccentric loading of the joint was noted on anterior-posterior shifting of the radial head during forearm rotation. The clinical relevance of these observations in relation to radial head dislocation, fracture pattern, and elbow stability is discussed.