Experimental study on rotation of the forearm--functional anatomy of the interosseous membrane

In an attempt to elucidate the function of the interosseous membrane of the forearm, the anatomy of the interosseous membrane and the kinematics of the forearm during pro-supine movement were studied. Results and Conclusions; The rotation axis coincides with the line drawn from the ulnar head to the radial head. The motion of the radius is an arc of a circle about it. At one-fourth the length of the forearm from the distal end, the axis coincides with the edge of the interosseous border of the ulna. The most prominent fibers of the interosseous membrane are those being attached to this part. Therefore, tension of these most prominent fibers is constant. The interosseous membrane of the forearm apparently shows a structure meeting the needs for stabilizing two bones, transmitting thrusts and giving the origin to the muscles without interfering with the pro-supine movement of the forearm.     

Ultrasound diagnosis and surgical pathology of the torn interosseous membrane in forearm fractures/dislocations

Ultrasound was used to effectively diagnose and precisely locate a torn interosseous membrane in 2 forearm fracture/dislocations. The ultrasound appearance of the torn interosseous membrane in cadavers and in the fractures/dislocations shows disruption of the anterior and posterior layers in midsubstance or adjacent to the radius or ulna. The surgical pathology in 3 forearm fractures/dislocations (2 Galeazzi injuries and 1 Essex-Lopresti injury) shows a longitudinal oblique tear of the interosseous membrane, parallel to its major palmar fibers, oriented from proximal radial to the distal ulnar. After ultrasound diagnosis, we demonstrated the feasibility of direct primary repair of the torn interosseous membrane associated with the Essex-Lopresti injury in a clinical case.     

MRI在桡骨头骨折合并前臂骨间膜损伤中的诊断价值

目的：探讨MRI在桡骨头骨折合并前臂骨间膜损伤中的诊断价值。方法：收集2011年12月至2012年12月间所有桡骨头骨折患者26例,其中男15例,女11例;年龄21～53岁,平均37.6岁。所有患者于伤后72 h内就诊,伤后1周内行伤侧尺桡骨全长X线片、伤侧CT（必要时加三维重建）及MRI检查（包括肘及腕关节）.观察前臂骨间膜在磁共振上的表现（有无损伤、损伤的部位及损伤的程度）,桡骨头骨折的损伤程度,比较两者的相关性。结果：桡骨头骨折Mason Ⅰ-Ⅲ型均可伴有前臂骨间膜损伤,桡骨头骨折程度与前臂骨间膜损伤程度成正相关（P〈0.05）.结论：桡骨头骨折伴前臂骨间膜可疑损伤时,有必要进行前臂MRI检查,明确骨间膜有无损伤及损伤程度,根据骨间膜损伤的情况对桡骨小头骨折选择正确的治疗方法,只有这样才能有利于肘关节和前臂功能的恢复。     

Interosseous membrane anatomy and functional mechanics

Longitudinal forearm stability is maintained through the interaction of several anatomic structures. One such structure, the interosseous membrane, is a fibrous tissue with an oblique orientation from the radius to the ulna. The membrane maintains the interosseous space between the radius and ulna through forearm rotation and actively transfers forces from the radius to the ulna. The interosseous membrane's unique functional capabilities result from its anatomic and histologic organization, which produces a stiff structure with elastic properties capable of maintaining large loads. The interosseous membrane's load transferring ability reduces the forces placed on the radiocapitellar articulation, thereby protecting this joint. However, large chronic loading results in attenuation of the membrane fibers, thereby reducing longitudinal stability. Large sustained loads occur after radial head resection with concurrent interosseous membrane tears, resulting in the proximal migration of the radius and disruption of the distal radioulnar joint. Ultimately, the treatment option for severe membrane disruption combined with proximal migration of the radius is the creation of a single bone forearm.     

Diagnosis and treatment of longitudinal instability of the forearm

Radio-ulnar dissociation can result from high-injury trauma that the compressive forces traverse the wrist forearm and elbow. This injury can be thought of as an "unhappy triad" of radial head fracture, triangular fibrocartilage complex failure, and a tear of the interosseous membrane. The radius is the primary stabilizer of the forearm with the forearm interosseous membrane enabling load sharing between the radius and the ulna. The central one-third of the interosseous membrane is 3 times stronger than the membranous portion and approaches the strength of the anterior cruciate ligament for determining interosseous membrane injury. Imaging studies with proven diagnostic efficacy include magnetic resonance imaging and ultrasound. Surgical treatment should be considered when circumstances imply longitudinal instability of the forearm. Surgical treatment includes open reduction/internal fixation or prosthetic replacement of the radial head as well as repair of the disrupted triangular fibrocartilage complex. Successful treatment of radioulnar dissociation is predicated on early diagnosis of the condition.     

Magnetic resonance imaging of the interosseous membrane of the forearm

BACKGROUND: Diagnosis of damage to the interosseous membrane of the forearm after trauma is difficult. Patients with a proximal radial fracture and associated damage to the interosseous membrane may have wrist pain in association with subluxation or dislocation of the distal radioulnar joint. Accurate identification of injury to the interosseous membrane may allow better planning of surgical treatment. METHODS: T1 and T2-weighted magnetic resonance images that were made in the axial, sagittal, and coronal planes were used to evaluate the interosseous membrane in the forearms of cadavera, volunteers, and patients. The images were evaluated subjectively by two orthopaedic surgeons and a musculoskeletal radiologist. RESULTS: The interosseous membrane was most consistently visualized on the axial images. Axial T2-weighted images showed the interosseous membrane clearly. The addition of fat-suppression techniques allowed abnormalities to be identified more accurately. Fast-spin-echo techniques were used to obtain data quickly and accurately. CONCLUSIONS: The intact and disrupted interosseous membrane can be evaluated with use of magnetic resonance imaging. Axial T2-weighted fast-spin-echo images with fat suppression in the middle one-third of the forearm provide the most accurate information.     

In vivo MR studies of dynamic changes in the interosseous membrane of the forearm during rotation.

In vivo dynamic changes in the interosseous membrane (IOM) during forearm rotation were studied using magnetic resonance imaging (MRI). The right forearms of 20 healthy volunteers were examined in five different rotational positions. Axial slices were obtained at the proximal quarter, the middle and the distal quarter of the forearm. The changes in shape of the IOM during rotation were observed in an axial MR plane. For each image, we measured the interosseous distance and the length of the interosseous membrane. Images of the tendinous and membranous parts of the IOM could be differentiated by thickness. There were minimal dynamic changes in the tendinous part on the MRI while the membranous part showed numerous changes during rotation. The interosseous distance and the length of the interosseous membrane were maximum from a neutral to a slightly supinated position. The tendinous part is considered to be taut during rotation to provide stability between the radius and the ulna, but the membranous part which is soft, thin and elastic, allows smooth rotation.     

Interosseous membrane reconstruction for forearm longitudinal instability

Forearm longitudinal instability results from an axial load to the forearm with fracture or dislocation of the radial head and disruption of the interosseous membrane and that of the distal radioulnar joint. Patients may present in the acute or chronic setting with radioulnar instability as manifested by persistent or new forearm discomfort and wrist and elbow pain. Reconstruction of the interosseous membrane has been described to restore longitudinal forearm stability. We describe reconstruction of the central band of the interosseous membrane with a bone-patellar tendon-bone graft. This procedure may be carried out in conjunction with radial head fixation or replacement and TFCC repair in the acute setting or ulnar shortening osteotomy in late presenting cases.     

The intra-operative radius joystick test to diagnose complete disruption of the interosseous membrane

Disruption of the interosseous membrane is easily missed in patients with Essex-Lopresti syndrome. None of the imaging techniques available for diagnosing disruption of the interosseous membrane are completely dependable. We undertook an investigation to identify whether a simple intra-operative test could be used to diagnose disruption of the interosseous membrane during surgery for fracture of the radial head and to see if the test was reproducible. We studied 20 cadaveric forearms after excision of the radial head, ten with and ten without disruption of the interosseous membrane. On each forearm, we performed the radius joystick test: moderate lateral traction was applied to the radial neck with the forearm in maximal pronation, to look for lateral displacement of the proximal radius indicating that the interosseous membrane had been disrupted. Each of six surgeons (three junior and three senior) performed the test on two consecutive days. Intra-observer agreement was 77% (95% confidence interval (CI) 67 to 85) and interobserver agreement was 97% (95% CI 92 to 100). Sensitivity was 100% (95% CI 97 to 100), specificity 88% (95% CI 81 to 93), positive predictive value 90% (95% CI 83 to 94), and negative predictive value 100%). This cadaveric study suggests that the radius joystick test may be useful for detecting disruption of the interosseous membrane in patients undergoing open surgery for fracture of the radial head and is reproducible. A confirmatory study in vivo is now required.     

Cadaveric modeling of the pronator teres rerouting tendon transfer.

The purpose of this study is to report the biomechanics of the supination effect of the pronator teres rerouting procedure and to determine the optimum insertion point for the transfer using a cadaveric model. Pronator teres rerouting procedures were performed on 5 fresh-frozen above-elbow cadaver specimens mounted in a forearm rotation mounting frame. The pronator teres was detached from its native insertion and tested at 6 insertions on the radius. The amount of rotation of the forearm was measured after loading of the pronator teres muscle for each insertion site. The experiments were repeated by placing the pronator teres 1 cm proximal to the 6 experimental insertion sites for a total testing of 12 insertions. The results of this study show that placement of the pronator teres through the interosseous membrane, around the radius, with reinsertion onto the volar surface produced the greatest amount of forearm supination. Rerouting of the pronator teres tendon produces supination through a windlass effect when the tendon is rerouted through an interosseous window and reinserted onto its original insertion or onto the volar surface of the radius. Placement of the insertion 1 cm proximal on the radius did not affect the amount of forearm supination compared with 6 original insertion sites.     

Posterior interosseous island forearm flap

The skin of the dorsal aspect of the forearm is supplied by several cutaneous branches of the posterior interosseous artery. This vascular anatomy permits the surgeon to obtain an island flap of the dorsal forearm based on the distal anastomosis between the two interosseous arteries at the distal part of the interosseous space. This flap can reliably be transferred to different skin defects of the hand such as those created by correction of an adduction contracture of the first web space, or on the back or front of the wrist level. Its principal advantages are that it is a thin flap with excellent circulation and that it is possible to close the donor area primarily provided the island flap is not wider than 3 to 4 cm. The procedure has been employed in 25 patients with satisfactory results.     

Ultrasonography for the interosseous membrane of the forearm.

The ability to improve the technique for an accurate clinical diagnosis of the injury of interosseous membrane of the forearm (IOM) associated with forearm fractures and dislocations is important for its treatment and prognosis. Ultrasound examination of the IOM in 46 forearms from 18 normal volunteers, five patients with restricted forearm pronation and supination, and two preoperative cases was performed to determine the usefulness and reproductivity of this examination. The intact IOM was observed as a continuous, slightly convex anteriorly and hyperechoic structure between the radius and ulna with both transverse and longitudinal views. IOMs with histories of forearm injuries were distinguished by the findings, which demonstrated a loss of continuity and were seen as hypoechoic traces from the others. This study confirmed that it is possible to trace the entire IOM and to detect differences between intact and disrupted IOMs with transverse and longitudinal views.     

Pronation contracture of the forearm due to iatrogenic scar formation of the distal membranous part of the forearm interosseous membrane

A case of successful treatment of pronation contracture of the forearm due to iatrogenic scar formation in the distal membranous part of the interosseous membrane of the forearm is presented and the management of this problem is discussed.     

Traumatic pathology of antibrachial interosseous membrane of forearm

The antibrachial interosseous membrane (IOM) is taught over an average length of 10.6cm between the diaphyses of the radius and ulna bone. It looks like a stitch with fibers running from the ulna to the radius and from proximal to distal and fibers running from distal to proximal. The central band, which is the middle part of the fibers directed from distal to proximal has mechanical properties similar to those of a ligament and act as a ligamentous structure embedded in the larger membranous complex of the IOM. The interosseous membrane has a double function: it stabilizes transversally the forearm's two bones and stabilizes longitudinally the two bones by transferring loads from the radius to the ulna. Load transmission varies according to the prono-supination position, the varus-valgus constraints on the elbow and the inclination of the wrist, making interpretation of the experimental data difficult. One should consider the forearm as a whole and the interosseous membrane with the two diaphyses should be regarded as a middle radio-ulnar joint, intercalated between the proximal and distal radio-ulnar joint. Those three articulations or links between radius and ulna act synergistically to stabilize and optimize repartition of loads. Functional loss of one of these links, and of course of more than one, will severely modify the forearm function. Essex-Lopresti lesion, which represents the functional loss of all three links, is the most destabilizing forearm lesion. Imaging of the interosseous membrane is difficult. MRI allows for static imaging of the interosseous membrane but there are often artifacts due to previous trauma or surgical procedures. Dynamic sonography helps to visualize all the lesions and will probably be part of the evaluation of every severe forearm injury. Surgical treatment depends on the gravity of the lesions of the different links. Interosseous membrane reconstruction is still the most difficult technique and most of the previously reported ligamentoplasties cannot answer all the biomechanical constraints. We describe a ligamentoplasty based on the biomechanics whose technique has been validated by cadaveric experiments. First surgical cases are promising.     

The efficacy of magnetic resonance imaging and ultrasound in detecting disruptions of the forearm interosseous membrane: a cadaver study

The purpose of this study was to examine the efficacy of magnetic resonance imaging (MRI) and ultrasound (US) in determining complete disruptions of the central portion of the forearm interosseous membrane. The midportion of the forearm interosseous ligament was longitudinally incised in 19 fresh-frozen cadaver arms. The specimens were imaged with MRI and US. The MRIs were examined by a hand surgeon, a musculoskeletal radiologist, and a general radiologist, all blinded to the state of the interosseous membrane. The musculoskeletal radiologist and general radiologists read the real-time US images in a consensus fashion. Magnetic resonance imaging showed a 96% accuracy rate, a 100% positive predictive value, a 93% negative predictive value, 93% sensitivity, and 100% specificity. Kappa analysis showed substantial interobserver agreement for MRI. Ultrasound showed a 94% accuracy rate, a 94% positive predictive value, a 100% negative predictive value, 100% sensitivity, and 89% specificity. There was no statistical significance between the accuracy of MRI and US. We conclude that MRI and US imaging should both be considered when forearm interosseous membrane integrity is in question.     

Management of injuries to the interosseous membrane

Injury to the interosseous membrane of the forearm typically occurs in conjunction with disruption of the radial head and the distal radioulnar joint. Frequently, the true extent of injury is not initially appreciated, and patients may develop longitudinal instability of the forearm, with wrist pain, forearm discomfort, and instability. This article outlines various treatment strategies, which include considerations at the wrist, forearm, and elbow.     

The radioulnar joints and forearm axis: surgeons' perspective.

Forearm injuries are common and can vary in complexity. The fractures are easily diagnosed, but the associated soft tissue injuries may not be as obvious. Treatment results are dependent not only on the fracture healing but on the return of normal relationships about the distal radioulnar joint, the interosseous membrane, and the proximal radioulnar joint. Alteration in any of these elements can result in permanent loss of forearm rotation and stability. Recent anatomic and biomechanical studies have increased our knowledge of these structures and their role in forearm function. The findings from these studies may lead to earlier repair of soft tissue injuries about the radioulnar joints and the interosseous membrane. Further follow-up of these procedures will be needed to validate their indications.     

Analysis of flow changes in forearm arteries after raising the radial forearm flap: a prospective study using colour duplex imaging.

The purpose of this study is to assess the changes in flow patterns of forearm arteries produced by excision of the radial artery when harvesting the radial forearm flap, in order to clarify its vascular morbidity rationally. Eleven patients with elective surgery using the radial flap were included in this investigation. A prospective study was designed using colour duplex imaging for quantitative flow measurement in two stages: a few days before the operation, a first colour duplex scanning examination was done recording flow velocity and vessel section area from the radial, ulnar, posterior interosseous and anterior interosseous arteries around the wrist. Volumetric parameters and relative blood flow percentages were calculated and compared to those obtained from a second similar vascular investigation accomplished in the same limb 4-5 months after the operation. Statistical analysis was done using the Wilcoxon matched pairs test. After raising the radial forearm flap there was a trend for increased overall forearm flow (from 162 to 215 ml/min, P = 0.09 N.S.), the ulnar (P = 0.04), the posterior interosseous (P = 0.004) and the anterior interosseous (P = 0.003) arteries being responsible for this tendency. The anterior interosseous artery showed the greatest increase in blood (from 8.2 to 67.7 ml/min), reaching a relative flow percentage (33%) close to that of the radial artery before its excision (39%). Results of this study indicate that another 'major vascular axis' based on the anterior interosseous artery develops after sacrificing the radial artery and that global arterial inflow to the hand is not impaired.     

Effects of radial head excision and distal radial shortening on load-sharing in cadaver forearms

BACKGROUND: The present study was performed to measure changes in radioulnar load-sharing in the cadaveric forearm following two orthopaedic surgical procedures that often have varying results: radial head excision and distal radial shortening. A better understanding of the biomechanical consequences of those procedures could aid surgeons in obtaining a more satisfactory clinical outcome. METHODS: Miniature load-cells were inserted into the proximal part of the radius and the distal part of the ulna in twenty fresh-frozen cadaveric forearms. Load-cell forces, radial head displacement relative to the capitellum, and local tension within the central band of the interosseous membrane were measured simultaneously as the wrist was loaded to 133.5 N in neutral pronation-supination and neutral radioulnar deviation. Testing was repeated after incremental distal radial shortening and after removal of the radial head. RESULTS: With the elbow flexed to 90 degrees and in valgus alignment (the radial head in contact with the capitellum), the mean force in the distal part of the ulna was 7.1% of the applied wrist force and the mean force in the interosseous membrane was 4.0%. With the elbow in varus alignment (a mean initial gap of 1.97 mm between the radial head and the capitellum), the respective mean values were 27.9% and 51.2%. After excision of the radial head, the mean force in the distal part of the ulna increased to 42.4% of the applied wrist force and the mean force in the interosseous membrane increased to 58.8%, in both varus and valgus elbow alignment. The mean distal ulnar force increased with progressive distal radial shortening in both varus and valgus elbow alignment; after 6 mm of radial shortening, the distal ulnar force averaged 92.4% (in varus alignment) and 60.9% (in valgus alignment). Equal distal load-sharing between the radius and ulna occurred after approximately 5 mm of radial shortening with the elbow in valgus alignment and after approximately 2 mm of radial shortening with the elbow in varus alignment. In valgus alignment, the force in the interosseous membrane was negligible after all degrees of radial shortening; in varus alignment, the mean force in the interosseous membrane decreased from 51.2% (0 mm of distal radial shortening) to 0% (6 mm of distal radial shortening) because of progressive slackening of the interosseous membrane. CONCLUSIONS: Radial head excision shifted the applied wrist force that normally would be transmitted to the elbow, through radial head-capitellar contact, to the interosseous membrane. The resulting proximal radial displacement created an ulnar-positive wrist and increased distal ulnar loading. Radial shortening and ulnar lengthening procedures have been designed to shift the applied wrist force from the distal part of the radius to the distal part of the ulna; it is commonly assumed that these procedures have equivalent biomechanical effects. We found that radial shortening resulted in slackening of the interosseous membrane, thereby negating its ability to transmit load through the forearm. Slackening of the interosseous membrane would not be expected with distal ulnar lengthening procedures. CLINICAL RELEVANCE: When the radial head has been fractured or excised, the mechanical status of the interosseous membrane is critical to the load-sharing process. If the interosseous membrane remains intact, distal ulnar loads will be limited to less than half of the applied wrist force; if the interosseous membrane has been damaged, nearly the entire applied wrist force will be shifted to the ulna. The amount of radial shortening or ulnar lengthening performed at the time of surgery during joint-leveling procedures has been largely empirical. We found that distal ulnar load increased by approximately 10% for each millimeter of radial shortening.