Interosseous Membrane Research Articles

Isolated Distal Tibiofibular Syndesmotic Injury: A Case Series and Proposed Mechanism

Objective: To review imaging findings of isolated tibiofibular interosseous membrane (IOM) injury and propose an injury mechanism. Case Report: A retrospective review was conducted on five patients who presented with lower leg pain following a traumatic athletic injury. MRI examinations revealed isolated tibiofibular IOM injury without associated fractures or distal syndesmotic disruption. The observed injury patterns, along with the blunt, non-rotational trauma reported in each case, suggest that the mechanism behind this unique presentation may involve sudden traction or direct impact to the lower leg. Conclusion: Isolated tibiofibular IOM injury should be considered in patients with lower leg pain after blunt trauma. MRI of the entire tibia and fibula can be instrumental in characterizing and confirming the injury and should be considered when clinical and injury mechanism indicators are present.

Pathophysiology of longitudinal forearm instability (Essex-Lopresti syndrome) and implications for treatment.

Longitudinal forearm instability, or Essex-Lopresti syndrome, associates radial head fracture and rupture of the structures uniting the 2 bones, mainly the interosseous membrane and triangular fibrocartilage complex adjacent to the distal radioulnar joint. It is often overlooked at first, and should be screened for in case of comminuted radial head fracture without elbow dislocation or instability. Treatment should be prompt, within 4 weeks of trauma, to avoid soft-tissue retraction and hopefully allow healing. This interval is anecdotal, without firm evidence, but matches observations regularly reported in the literature [1]. In the acute phase, treatment consists in rigid, usually unipolar, radial head replacement, protected healing of the interosseous membrane by a TightRope suture button between the bones, radioulnar pinning and triangular fibrocartilage complex suture, followed by 6 weeks' immobilization. Progression is usually favorable. Chronic forms, beyond 4 weeks, when soft-tissue healing is impossible, require interosseous membrane reconstruction. In case of radiocarpal impingement due to ascension of the radius, ulnar shortening osteotomy must be associated. Medium-term results in such cases are much less certain. As a last resort, the "one-bone forearm" is a solution.

Lower limb interosseous membrane in foetuses

Lower limb interosseous membrane in foetuses

Creation of a replicable anatomic model of terrible triad of the elbow.

Terrible triad of the elbow (TTE) is a complex dislocation associating radial head (RH) and coronoid process (CP) fractures. There is at present no reproducible anatomic model for TTE, and pathophysiology is unclear. The main aim of the present study was to create and validate an anatomic model of TTE. Secondary objectives were to assess breaking forces and relative forearm rotation with respect to the humerus before dislocation. An experimental comparative study was conducted on 5 fresh human specimens aged 87.4 ± 8.6 years, testing 10 upper limbs. After dissection conserving the medial and lateral ligaments, interosseous membrane and joint capsule, elbows were reproducibly positioned in maximal pronation and 15° flexion, for axial compression on a rapid (100mm/min) or slow (10mm/min) protocol, applied by randomization between the two elbows of a given cadaver, measuring breaking forces and relative forearm rotation with respect to the humerus before dislocation. The rapid protocol reproduced 4 posterolateral and 1 divergent anteroposterior TTE, and the slow protocol 5 posterolateral TTE. Mean breaking forces were 3,126 ± 1,066N for the lateral collateral ligament (LCL), 3,026 ± 1,308N for the RH and 2,613 ± 1,120N for the CP. Comparing mean breaking forces for all injured structures in a given elbow on the rapid protocol found a p-value of 0.033. Comparison of difference in breaking forces in the three structures (LCL, RH and CP) between the slow and rapid protocols found a mean difference of -4%. Mean relative forearm rotation with respect to the humerus before dislocation was 1.6 ± 1.2° in external rotation. We create and validate an anatomic model of TTE by exerting axial compression on an elbow in 15° flexion and maximal pronation at speeds of 100 and 10mm/min.

The Prevalence of Chronic Interosseous Membrane Lesions Following Mason II and III Radial Head Fractures in Complex Elbow Instability-A Retrospective Observational Cohort Study.

The primary aim of the present study was to assess the prevalence of chronic lesions of the central band of the interosseous membrane (cbIOM) in complex elbow instability (CEI) in a consecutive series of patients who had previously undergone surgical treatment for Mason II and III radial head (RH) fractures. The secondary aim was to define its clinical significance. We performed a retrospective study on a prospective database. Our study population comprised 93 patients affected by CEI with type II or III RH fractures according to Mason's classification who were analyzed in the chronic setting. All patients were treated according to the current therapeutic algorithms. At the last follow-up, the "muscular hernia sign" was investigated by means of a bilateral ultrasonographic examination to assess any chronic cbIOM lesions; the Mayo Elbow Performance Score (MEPS) was used to evaluate the clinical significance of these lesions. All 93 patients were assessed after a mean time of 7.3 years (range: 2-12). No positive "hernia signs" were found, while five patients (5.4%) displayed an increased laxity of the cbIOM when compared with the contralateral side despite a negative "hernia sign". The clinical outcome in all five patients was excellent with a mean MEPS of 96 (range, 90-100). Chronic cbIOM lesions are very rare in CEI with RH fractures. No patients in this large sample displayed a cbIOM complete lesion; in cases with increased laxity, satisfactory mid-term clinical results were observed. Considering that previous studies reported (1) a high prevalence of cbIOM lesions in patients with Mason II and III RH fractures and (2) the current expert opinion about the scarce healing potential of the cbIOM, this study also suggests that the IOM may heal better than previously believed when RH fractures are treated appropriately in the acute setting.

Fluorosis Masquerading as Compressive Myelopathy

A 60-year-old woman from Cuddalore presented with restricted neck movements, progressive difficulty in walking, and lower limb weakness, leading to bed confinement. Clinical examination revealed spastic paraparesis, brisk reflexes, and sensory deficits below the hips. Laboratory investigations indicated renal insufficiency and elevated urine fluoride levels. Imaging demonstrated calcifications of sacroiliac, sacrospinous ligaments, interosseous membrane, and posterior longitudinal ligament, with osteosclerosis and osteoporosis. Differential diagnoses included Ankylosing Spondylitis and Diffuse Idiopathic Skeletal Hyperostosis. However, the unique pattern of ligament calcification and elevated fluoride levels supported a diagnosis of fluorosis. This case underscores the importance of considering fluorosis in patients from endemic areas with spastic paraparesis and characteristic radiological findings. Posterior decompression via laminectomy was performed, emphasizing the need for awareness of fluorosis as a potential cause of cervical compressive myelopathy.

Decompression corrective osteotomy of the distal radius for treatment of the DRUJ-incongruency and impingement syndrome with focus on posttraumatic cases

IntroductionPosttraumatic or congenital ulna-minus variance with altered shape of the sigmoid notch and increased tension of the distal oblique band of the interosseous membrane (DIOM) can lead to painful impingement in the distal radioulnar joint (DRUJ) during rotation and loading of the forearm. As an operative treatment concept, a new method was described in 2016. Its goal is to restore the osseous congruency, which is required for normal painless function. The hypothesis is based on remodelling of the joint surface and the decompression of the DRUJ by releasing the DIOM. The purpose of this study is to analyze the results of performed operations with detailed focus on posttraumatic cases. Materials and Methods: The indication for the operation is the impingement and incongruency in the DRUJ with ulna-minus variance. The surgical procedure is based on shortening and closed-wedge osteotomy of the distal radius with an ulnar translation of the radial shaft. Fifty-nine operations were performed between 2011 – 2022 on 52 patients (13 men, 39 women). Twenty-four patients were operated on the right side, 21 on the left side and 7 bilaterally. In 45 cases the operation was indicated because of congenital, in 12 cases due to posttraumatic incongruency and in 2 cases because of iatrogenic impingement after previously performed excessive ulnar shortening osteotomy. Modified Mayo-Wrist-Score, patient questioning, VAS and ROM were used to evaluate the results. ResultsSignificant reduction of pain on VAS from 7.22 to 1.98 (p < .001) was achieved. The pre- and postoperative range of motion did not show any significant changes (mean total arc of motion 301,94° vs. 295,20°, p = .300). Specific complications we observed included a too distally performed osteotomy, DRUJ instability, de Quervain´s tenosynovitis, persistent pain and conversion into an ulna-plus variance. ConclusionUnder consideration of the indication criteria and correct execution of the osteotomy, in about 90 % of the cases this operation leads to good-to-excellent results with pain reduction and improvement of weight-bearing and power. The preoperative examination, verification of the DRUJ stability and the radiological diagnostics are crucial for a good outcome.

Clinical, Radiographic, and Biomechanical Evaluation of the Upper Extremity in Patients with Osteogenesis Imperfecta.

Introduction: Osteogenesis imperfecta (OI) is a hereditary disorder primarily caused by mutations in type I collagen genes, resulting in bone fragility, deformities, and functional limitations. Studies on upper extremity deformities and associated functional impairments in OI are limited. This cross-sectional study aimed to evaluate upper extremity deformities and functional outcomes in OI. Methods: We included patients regardless of their OI subtypes with a minimum age of 7 years. Radiographic analysis of radial head dislocation, ossification of the interosseous membrane, and/or radioulnar synostosis of the forearm were performed, and deformity was categorized as mild, moderate, or severe. Clinical evaluation was performed using the Quick Disabilities of Arm, Shoulder, and Hand (qDASH) questionnaire and shoulder-elbow-wrist range of motion (ROM). Three-dimensional motion analysis of the upper limb was conducted using the Southampton Hand Assessment Procedure (SHAP). The SHAP quantifies execution time through the Linear Index of Function (LIF) and assesses the underlying joint kinematics using the Arm Profile Score (APS). Additionally, the maximum active Range of Motion (aRoM) was measured. Results: Fourteen patients aged 8 to 73 were included. Radiographic findings revealed diverse deformities, including radial head dislocation, interosseous membrane ossification, and radioulnar synostosis. Six patients had mild, six moderate, and two severe deformities of the upper extremity. Severe deformities and radial head dislocation correlated with compromised ROM and worse qDASH scores. The qDASH score ranged from 0 to 37.5 (mean 11.7). APS was increased, and LIF was reduced in OI-affected persons compared with non-affected peers. APS and LIF also varied depending on the severity of bony deformities. aRoM was remarkably reduced for pro-supination. Conclusion: Patients with OI showed variable functional impairment from almost none to severe during daily life activities, mainly depending on the magnitude of deformity in the upper extremity. Larger multicenter studies are needed to confirm the results of this heterogeneous cohort. Level of evidence: Retrospective clinical study; Level IV.

Central band reconstruction in Essex-Lopresti lesions

Restoration of longitudinal forearm stability by reconstruction of the central band (CB) of the interosseous membrane (IOM) of the forearm. Acute and chronic Essex-Lopresti lesions (EL) with longitudinal forearm instability. Absolute: acute/subacute infection. Relative: severe complex regional pain syndrome (CRPS), bony deformity/bone loss, pronounced osteoarthritis of the elbow and wrist. Ulnar approach with exposure of the ulna approximately 6 cm proximal to the ulnar styloid. Creation of a3.5 mm drill hole from ulnar-distal to radial-proximal. AFiberloop (Fa. Arthrex, Naples, FL, USA) is fixed to one end of the LARS (Ligament Advanced Reconstruction System, Fa. Corin Group, Cirencester, UK) in awhipstitch technique, is shuttled through the drill hole from radial to ulnar and fixed over aBicepsButton (Fa. Arthrex, Naples, FL, USA). Exposure of the radius through amodified Henry approach. A3.5 mm drill hole is made from radial-proximal to ulnar-distal approximately 12 cm proximal to the radial styloid. The graft is shuttled from the ulnar to the radial incision directly on the palmar surface of the IOM and shortened to the required length. Another Fiberloop is used to perform awhipstitch on the free end of the LARS. The final fixation of the CB reconstruction is achieved by shuttling the Fiberloop sutures through the radial drill hole with fixation over aBicepsButton. Short-term immobilization in along arm cast with subsequent early functional treatment. Mediocre to poor clinical results are reported in the literature for the treatment of chronic EL. Future research will tell whether the advanced surgical techniques with CB reconstruction will lead to better clinical outcomes.

Double-Flap Elevation From the Ipsilateral Lower Extremity: The Anterior Approach to Fibula Osteo-Cutaneous Flap Elevation.

The free fibular flap has been elevated by a "lateral approach" from the posterior edge of the peroneal muscle for more than 40 years. However, in this approach, the surgical view is limited because flap elevation in mandibular reconstruction is performed simultaneously with tumor resection in the supine position, even when using positioning pillows. We herein propose an "anterior approach" as a new surgical method. We retrospectively investigated free fibular flap surgeries performed using the anterior approach, which consists of three anterior approaches, over a seven-year period. First, to avoid the course of the superficial peroneal nerve, the crural fascia was incised 1-2 cm posterior to the anterior edge of the peroneal muscle. The anterior edge of the peroneus muscle is detached from the anterior intermuscular septum. After performing osteotomies distal and proximal to the fibula, the interosseous membrane was incised from the anterior view. Pulling out the fibula to the anterior space between the anterior intermuscular septum and the peroneal muscle made the surgical field shallow. No postoperative superficial or deep peroneal nerve palsies were found in the 55 patients. Only one tourniquet was used in 31 of the 55 cases (56.4%), with an average of 95 min. Twenty-four patients (43.6%) required a second tourniquet 38 min after an interval. Only one tourniquet was used in 25 of the 30 (83.3%) cases in the last 3 years. Moreover, double flaps were used in 21 cases (38.2%), all of which involved ipsilateral ALT flaps. In 18 cases, double-flap elevation and prefabrication were successfully finished before the completion of tumor resection by otorhinolaryngologists.

Treatment of Congenital Ulnar Impingement Syndrome by Corrective Osteotomy of the Distal Radius - Clinical Results

In 2016, a new method was described to treat the painful impingement syndrome of the DRUJ: decompression corrective osteotomy of the distal radius. Clinical symptoms are based on a positive compression test; pain occurs with weight-bearing on the forearm. This phenomenon is seen in conjunction with a deformed sigmoid notch together with ulna minus-variance, which leads to increased tension in the distal oblique bundle of the interosseous membrane. The etiology of the condition can be either congenital, post-traumatic, or iatrogenic. Through the proposed osteotomy, decompression in the DRUJ is achieved. This study summarises the results of these surgical procedures performed in our hand centre exclusively in cases of congenital origin. Remodelling of the DRUJ is achieved through the shortening of the distal radius together with closed wedge osteotomy. Relief of the interosseous membrane is accomplished by ulnar translation of the radial shaft. This study only included patients with congenital incongruency in the DRUJ. The results were evaluated using a visual analogue scale (VAS) and the Krimmer Wrist Score and by measuring the preoperative and postoperative range of motion as well as grip strength. Within 11 years, 45 procedures were performed with our method on 38 patients, of which 17 were treated on the right side, 14 on the left side, and 7 bilaterally. In cases of bilateral incongruency, only the symptomatic side was treated. The statistical evaluation showed a significant reduction of pain on the VAS from 7.2 to 2 (p<0.001). No significant changes were seen in the range of motion (p=0.812). The Krimmer Wrist Score showed good to excellent results in almost 90% of cases. If the indication criteria are met, contraindications are avoided and the osteotomy is correctly performed, this technique leads to an improvement of patients' functionality and quality of life. From a preventive viewpoint, the influence on the progression of the degenerative changes is yet to be demonstrated in further studies. At any rate, this is a safe procedure, which leaves the path open for other possible options.

The IFITM5 mutation in osteogenesis imperfecta type V is associated with an ERK/SOX9-dependent osteoprogenitor differentiation defect.

Osteogenesis imperfecta (OI) type V is the second most common form of OI, distinguished by hyperplastic callus formation and calcification of the interosseous membranes, in addition to the bone fragility. It is caused by a recurrent, dominant pathogenic variant (c.-14C>T) in interferon-induced transmembrane protein 5 (IFITM5). Here, we generated a conditional Rosa26-knockin mouse model to study the mechanistic consequences of the recurrent mutation. Expression of the mutant Ifitm5 in osteo-chondroprogenitor or chondrogenic cells resulted in low bone mass and growth retardation. Mutant limbs showed impaired endochondral ossification, cartilage overgrowth, and abnormal growth plate architecture. The cartilage phenotype correlates with the pathology reported in patients with OI type V. Surprisingly, expression of mutant Ifitm5 in mature osteoblasts caused no obvious skeletal abnormalities. In contrast, earlier expression in osteo-chondroprogenitors was associated with an increase in the skeletal progenitor cell population within the periosteum. Lineage tracing showed that chondrogenic cells expressing the mutant Ifitm5 had decreased differentiation into osteoblastic cells in diaphyseal bone. Moreover, mutant IFITM5 disrupted early skeletal homeostasis in part by activating ERK signaling and downstream SOX9 protein, and inhibition of these pathways partially rescued the phenotype in mutant animals. These data identify the contribution of a signaling defect altering osteo-chondroprogenitor differentiation as a driver in the pathogenesis of OI type V.

Posttraumatic proximal radioulnar synostosis: Current concepts on the clinical presentations, classifications, and open surgical approaches

In the forearm, posttraumatic heterotopic ossification usually forms as a proximal radioulnar synostosis. It can occur after soft tissue injury involving the interosseous membrane or after surgery involving the radio and ulna, such as distal biceps tendon repair. It can also be induced by radial head dislocation or fracture. Screening radiography can be used to select the appropriate time for excision. The synostosis can be resected when the ectopic bone margin and trabeculation appear mature on radiographs. An interval of 6–12 months from the injury is generally recommended based on ectopic bone maturity. Selection of the surgical approach depends on site, extension (elbow joint or proximal radioulnar joint), severity of the initial articular surface, and periarticular tissue injury. The posterolateral approach is indicated for synostoses: at or distal to the bicipital tuberosity, at the level of the radial head, and proximal radioulnar joint. The posterior global approach is recommended when the forearm synostosis is associated with complete bony ankylosis of the elbow involving the distal aspect of the humerus. After surgical resection of a proximal radioulnar synostosis, the exposed bone surfaces can be covered with interposition material to minimize recurrence.

Ultrasound guided compressibility of the lower leg anterior tibial muscle compartment: a feasibility study

ABSTRACT Objectives Some young individuals participating in sports activities may encounter lower leg muscle pain and tightness, potentially indicating chronic exertional compartment syndrome (CECS). While muscle pressure measurement is typically recommended for diagnosis, it is invasive and associated with low sensitivity and specificity. Thus, there is a need for novel diagnostic approaches. Methods This feasibility study aims to assess whether an ultrasound-guided technique can effectively measure the compressibility of the anterior tibial muscle compartment, focusing on optimal leg positioning and identifying reliable external and internal anatomical landmarks. The compressibility of the anterior tibial muscle compartment was evaluated using ultrasound images obtained at 10 mmHg and 80 mmHg external pressure, with the drop in compartment thickness used to calculate the compressibility ratio. Measurements were conducted in various leg positions and utilizing different external and internal landmarks. Results Studies in healthy volunteers showed that knee and heel support positioning, measuring at the leg’s widest circumference, and using the interosseous membrane as an internal landmark yielded the lowest measurement variability with an intra class correlation of .977 (.764–1.000; 95%-confidence interval). Conclusion These findings suggest that ultrasound-guided techniques can feasibly determine the compressibility ratio of the anterior tibial muscle compartment, providing valuable insights for standardized protocols in future studies on suspected cases of chronic exertional compartment syndrome.

A Rare Case of Osteogenesis Imperfecta Type V

Osteogenesis imperfecta (OI) is a hereditary bone condition characterised by fragile bones to be more susceptible to fracture. We reported a rare case of a 6-year-old girl with OI Type V and hyperplastic callus formation. She presented with recurrent fractures since birth with no family history of a similar condition. Clinically, her height and weight were lower than the 5th percentile for her age. She had deformities with limitation of movement of elbows, kyphoscoliosis, a more extensive right thigh, and anterior bowing of both legs. Radiographic examination revealed interosseous membrane of forearm ossification, dislocation of the right radial head and hyper-callosity of both femurs during fracture healing. She was treated with intravenous pamidronate and had posterior instrumentation and fusion for scoliosis and intramedullary rodding for her femur fracture. On a recent follow-up at the age of 16 years, she was ambulating well with no progression of the spinal deformity.

Treating Erythromelalgia with Interosseous Membrane Stimulation: An Autonomic Basis for the Condition and Its Treatment.

Erythromelalgia, which has primary and secondary presentations, causes heat, pain, and redness in the skin. The condition seems to have an autonomic basis, with vasomotor dysfunction causing dilatation of some blood vessels and constriction of others. No consistently effective treatments have been reported. Anticonvulsant, antidepressant, antihistamine, anti-inflammatory, antihypertensive, analgesic, nutritional, and topical approaches have been tried as were lidocaine infusions, nerve blocks, and thoracic and lumbar sympathectomies. Interosseous membrane stimulation appears to affect the local autonomic milieu in the extremity being treated. This approach was used on a patient with erythromelalgia. A 36-year-old woman with erythromelalgia was treated with interosseous membrane stimulation. Eight treatments were given over a 1-year timeframe at 1-3-month intervals. This patient repeatedly experienced much relief from her burning paresthesias, swelling, diaphoresis, and ruddy discoloration of her extremities for 6-8 hours following each treatment. The intensity of her discomfort subsided gradually over time. Interosseous membrane stimulation is a safe, simple, and effective treatment for erythromelalgia, which is notoriously refractory to treatment. This patient's response to treatment might have been a result of localized derangement of her autonomic nervous system. It is possible that manipulation of the autonomic milieu of an extremity is a significant factor in the mechanism of action of interosseous membrane stimulation.

The pronator contracture syndrome: A new entity in supination restriction

Forearm rotation is essential for daily activities and functional dexterity, involving both pronation and supination. Forearm rotation limitations can result from various pathologies, often linked to trauma, structural changes in radio-ulnar joints, and interosseous membrane alterations. Soft tissue contracture, such as post-burn scarring or specific neurological conditions, can also restrict forearm rotation. We present two cases of painless restricted passive and active supination, devoid of bony, neurovascular, soft tissue, or congenital abnormalities. We describe a surgical technique to improve forearm rotation in these patients.

Invasion Patterns and Long-Term Clinical Outcomes of Diffuse Tenosynovial Giant Cell Tumor of the Ankle Joint.

The invasion patterns and long-term outcomes ofdiffuse tenosynovial giant cell tumor (D-TSGCT) of the ankle joint remain unclear. Seven patients who visited our department between 2011 and 2023 and were diagnosed withD-TSGCT of the ankle joint by contrast-enhanced MRI and a pathological diagnosis were included. The invasion patterns of ankle D-TSGCT on MRI were investigated. The recurrence rate and clinical symptoms were examined in five patients followed up for more than seven years after total resection. In seven patients (1 male/6 females, mean age 37.0±16.6 years, range 15-57 years) with D-TSGCT of the ankle joint, contrast-enhanced MRI at the initial presentation showed invasion within the ankle joint, extending along the tendon sheath, within the talocalcaneal joint, and in the tarsal sinus in 100% of cases, around the deltoid ligament in 86%, within the plantar surface in 43%, invasion of the interosseous membrane in 57%, around the Achilles tendon in 29%, and scalloping on the talocrural joint in 43%. The mean time from mass awareness to the first visit was 51.9±80.0 months (range 1-240 months). Gross total resection, defined as the removal of all tumors as gauged by MRI, was initially performed on 6/7 patients. One patient underwent partial resection of only the anterior part of the tumor. Of the six cases in which gross total resection was performed, 5 had long-term follow-up of more than seven years post-operatively, and one case is still only one year post-operatively. The long-term results offive patients followed for more than seven years after total resection were as follows: a mean follow-up period of 125 months (range 89-171 months), a 100% recurrence rate, a mean time to recurrence of 27.5±19.2 months (range 7-60 months), and a 16% reoperation rate. In the last follow-up, osteoarthritic changes were observed radiographically in 2/5 patients (40%), both of whom had scalloping of the talocrural joint on MRI at the time of the initial diagnosis. Four of the five patients (80%) had no clinical symptoms in the last follow-up. Ankle D-TSGCT presents with a strong local infiltrative pattern inside and outside the ankle joint along the tendon sheath, radical resection may be difficult, and the recurrence rate may be higher than previously reported. On the other hand, there are many cases that remain free of clinical symptoms in the long term after recurrence, and surgical indications for ankle D-TSGCT need to consider function preservation as well as recurrence rates.

Reproduction of forearm rotation dynamic using intensity-based biplane 2D–3D registration matching method

This study aimed to reproduce and analyse the in vivo dynamic rotational motion of the forearm and to clarify forearm motion involvement and the anatomical function of the interosseous membrane (IOM). The dynamic forearm rotational motion of the radius and ulna was analysed in vivo using a novel image-matching method based on fluoroscopic and computed tomography images for intensity-based biplane two-dimensional–three-dimensional registration. Twenty upper limbs from 10 healthy volunteers were included in this study. The mean range of forearm rotation was 150 ± 26° for dominant hands and 151 ± 18° for non-dominant hands, with no significant difference observed between the two. The radius was most proximal to the maximum pronation relative to the ulna, moved distally toward 60% of the rotation range from maximum pronation, and again proximally toward supination. The mean axial translation of the radius relative to the ulna during forearm rotation was 1.8 ± 0.8 and 1.8 ± 0.9 mm for dominant and non-dominant hands, respectively. The lengths of the IOM components, excluding the central band (CB), changed rotation. The transverse CB length was maximal at approximately 50% of the rotation range from maximum pronation. Summarily, this study describes a detailed method for evaluating in vivo dynamic forearm motion and provides valuable insights into forearm kinematics and IOM function.

Morphological changes in the interosseous membrane of the forearm during forearm rotation.

[Purpose] Changes in forearm interosseous membrane dynamics during forearm rotation relative to the shoulder joint position remain poorly understood. The purpose of this study was to clarify interosseous membrane dynamics during forearm rotation in shoulder abduction and external rotation positions. [Participants and Methods] We conducted open magnetic resonance imaging on 17 healthy forearms in the prone position. Three limb positions were set for measuring the forearm rotation angle: intermediate, maximum pronation, and maximum supination. Images were obtained with the shoulder joint abducted at 90°and externally rotated at 90°. The forearm interosseous membrane angle was measured at three points: the apex of the forearm interosseous membrane, the radius, and the ulna. The measurement of the interosseous angle was repeated thrice. [Results] Sufficient intra-rater reliability was confirmed for the forearm interosseous membrane angle measurement. The interosseous membrane of the forearm showed a mean dorsal convex shape during forearm pronation (141.7° ± 0.83°), and the mean palmar convex shape during forearm supination (-141.6° ± 0.64°). [Conclusion] This study provides useful information for future research by quantifying the dynamics of the interosseous membrane of the forearm, which is an important soft tissue for forearm rotation. The establishment of a quantitative evaluation method for forearm interosseous morphological changes will help further elucidate forearm rotation movements during sports activities.