Effects of axial forearm instability on force transmission across the elbow.

BACKGROUND: The interosseous membrane (IOM) and distal radioulnar joint (DRUJ) provide axial stability to the forearm. Our hypothesis was that injury to these structures alters force transmission through the elbow. METHODS: A custom-designed apparatus that applies axial loads from the wrist to the elbow was used to test 10 cadaveric upper limbs under the following simulated conditions (1) intact, (2) DRUJ injury, (3) IOM injury, or (4) IOM + DRUJ injury. IOM injury was simulated by osteotomies of the IOM attachment to the radius, and DRUJ injury was simulated by distal ulnar oblique osteotomy. We applied 160 N of axial force during cyclic and functional range of forearm rotation (40o pronation/40o supination), and force, contact pressure, and contact area through the elbow joint were measured simultaneously. RESULTS: The force across the radiocapitellar joint was significantly higher in the IOM + DRUJ injury and the IOM injury groups than in the intact and DRUJ injury groups. The mean force across the radiocapitellar joint was not significantly different between the intact and DRUJ injury groups or between the IOM + DRUJ injury and the IOM injury groups. Forces across the ulnohumeral joint showed an inverse pattern to those in the radiocapitellar joint. CONCLUSIONS: These findings suggest that injury to the IOM contributes more to the disruption of the normal distribution of axial loads across the elbow than injury to the DRUJ.

The impact of harvest length and detachment of the interosseous membrane on donor-site morbidity following free fibula flap surgery-a biomechanical experimental study.

PURPOSE: The fibula flap has been established for orofacial reconstruction following ablative surgery. Donor-site morbidity of the lower leg may be explained by the harvest technique and particularly by detachment of the M. extensor halluces longus (EHL) and M. extensor digitorum longus (EDL). MATERIAL AND METHODS: On cadaveric lower leg specimens, the tendons of the EHL and EDL were dissected at the proximal phalanges and loaded with corresponding weights. The average displacement of the muscle was evaluated during the harvesting procedure. RESULTS: Cumulative detachment of the interosseous membrane caused considerable displacement of the EHL but less impairment of the EDL. Segmental and cumulative osteotomy of the fibula implicated significant displacement of both EHL and EDL. CONCLUSION: A recommendation can be given for cautious selection of osteotomy site of the fibula and for limited sacrifice of the fibula and adjacent attachments of the extensors to keep local-site morbidity at a minimum.

A Novel Algorithmic Approach to Chronic Forearm Longitudinal Instability.

Essex-Lopresti Lesions are rare injuries that are often missed in the acute setting. Delayed intervention may lead to chronic wrist and elbow pain and overall poor outcomes. The literature currently supports treatments that involve shortening of the ulna to reduce the relative degree of ulnar impaction, followed by attempted reduction of the distal radioulnar joint. Although such techniques may help to temporarily reduce wrist pain secondary to ulnar impaction, they do not address the proximal migration of the radius and ipsilateral radial head dislocation at the elbow. Subsequent procedures are often needed to replace or resect the radial head. We present a novel approach to chronic Essex-Lopresti lesions resulting in anatomic restoration of forearm length with return of elbow and wrist flexion/extension as well as improved forearm pronation/supination.

Ligamentous reconstruction of the interosseous membrane of the forearm in the treatment of instability of the distal radioulnar joint / Reconstrução da membrana interóssea do antebraço no tratamento da instabilidade da articulação da radioulnar distal

ABSTRACT Objectives: To measure the quality of life and clinical outcomes of patients treated with interosseous membrane (IOM) ligament reconstruction of the forearm, using the brachioradialis (BR), and describe a new surgical technique for the treatment of joint instability of the distal radioulnar joint (DRUJ). Methods: From January 2013 to September 2016, 24 patients with longitudinal injury of the distal radioulnar joint DRUJ were submitted to surgical treatment with a reconstruction procedure of the distal portion of the interosseous membrane or distal oblique band (DOB). The clinical-functional and radiographic parameters were analyzed and complications and time of return to work were described. Results: The follow-up time was 20 months (6-36). The ROM averaged 167.92° (93.29% of the normal side). VAS was 2/10 (1-6). DASH was 5.63/100 (1-18). The time to return to work was 7.37 months (3-12). As to complications, one patient had an unstable DRUJ, and was submitted to a new reconstruction by the Brian-Adams technique months. Currently, he has evolved with improved function, and has returned to his professional activities. Three other patients developed problems around the transverse K-wire and were treated with its removal, all of whom are doing well. Conclusion: The new approach presented in this study is safe and effective in the treatment of longitudinal instability of the DRUJ, since it has low rate of complications, as well as satisfactory radiographic, clinical, and functional results. It allows return to social and professional activities, and increases the quality of life of these patients.

RESUMO Objetivos: Mensurar a qualidade de vida e os resultados clínico-funcionais dos pacientes submetidos à reconstrução ligamentar de membrana interóssea (MIO) do antebraço com o uso do braquioestilorradial (BR) e descrever uma nova técnica cirúrgica. Método: De janeiro de 2013 a setembro de 2016, 24 pacientes com lesão longitudinal da articulação radioulnar distal (ARUD) foram submetidos ao tratamento cirúrgico de reconstrução da porção distal da membrana interóssea ou distal oblique band (DOB). Foram analisados os parâmetros clínico-funcionais e radiográficos e descritos as complicações e o tempo de retorno ao trabalho. Resultados: O tempo de seguimento foi de 20 meses [6-36]. A ADM foi em média 167,92° (93,29% do lado normal). A VAS foi 2/10 [1-6]. O DASH foi de 5,63/100 [1-18]. O tempo de retorno ao trabalho foi de 7,37 meses [3-12]. Quanto às complicações, um paciente evoluiu com instabilidade da ARUD e foi submetido a nova reconstrução pela técnica de Brian-Adams. Evoluiu com melhoria funcional e retornou às atividades profissionais. Outros três pacientes evoluíram com problemas ao redor do fio de Kirschner transverso à ARUD e foram tratados com a remoção desse, todos evoluíram bem. Conclusão: A nova abordagem apresentada neste estudo demonstrou-se segura e eficaz no tratamento da instabilidade longitudinal da ARUD, já que apresentou baixa taxa de complicações, bem como resultados radiográficos, clínicos e funcionais satisfatórios, o que melhorou a qualidade de vida desses pacientes.

Single- versus double-bundle suture button reconstruction of the forearm interosseous membrane for the chronic Essex-Lopresti lesion.

PURPOSE: Reconstruction of the ruptured interosseous membrane (IOM) is critical to restore forearm stability for the chronic Essex-Lopresti injury. Positive outcomes have been reported following IOM reconstruction with a single-bundle suture button (Mini-Tightrope) construct, although recent work suggests that double-bundle Mini-TightRope® IOM reconstruction is biomechanically superior. The purpose of this study was to determine whether double-bundle Mini-TightRope® reconstruction of the forearm IOM results in superior clinical outcomes to the single-bundle technique. METHODS: Five patients with chronic Essex-Lopresti injuries treated with double-bundle Mini-TightRope® IOM reconstruction were matched to five patients treated with single-bundle Mini-TightRope® reconstruction. Improvement in clinical examination measures and patient-reported outcomes was compared between the groups. RESULTS: Results were good to excellent in all 10 patients. At final follow-up, forearm rotation was significantly better in the single-bundle group, while maintenance of ulnar variance was better in the double-bundle group. No significant differences were noted between the two groups for any other numerical outcomes, and no complications occurred. CONCLUSION: These findings suggest that while IOM reconstruction with a double-bundle Mini-TightRope® construct results in greater resistance to proximal migration of the radius in the intermediate term, there is a modest concomitant loss of forearm rotation when compared to single-bundle reconstruction. LEVEL OF EVIDENCE: Therapeutic Level IV.

Interosseous membrane reconstruction with a suture-button construct for treatment of chronic forearm instability.

BACKGROUND: The purpose of this study was to report outcomes of interosseous membrane (IOM) reconstruction with a suture-button construct for treatment of chronic longitudinal forearm instability. METHODS: We performed a retrospective review with prospective follow-up of patients who underwent ulnar shortening osteotomy and IOM reconstruction with the Mini TightRope device from 2011 through 2014. Bivariate statistical analysis was used for comparison of preoperative and postoperative Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) scores, range of motion, grip strength, and ulnar variance. Complications and patient satisfaction were also recorded. RESULTS: Ten patients (mean age, 45.3 years) satisfied inclusion criteria: 8 treated for post-traumatic sequelae of Essex-Lopresti-type injuries, 1 for forearm instability secondary to previous elbow surgery, and 1 for instability secondary to trauma and multiple elbow surgeries. Surgeries were performed an average of 28.6 months from initial injury. At mean follow-up of 34.6 months after surgery, significant improvement was observed in elbow flexion-extension arc (+23° vs. preoperatively; P = .007), wrist flexion-extension arc (+22°; P = .016), QuickDASH score (-48; P = .000), and ulnar variance (-3.3 mm; P = .006). Three patients required additional surgery: 1 revision ulnar shortening osteotomy for persistent impingement, 1 revision ulnar osteotomy and Mini TightRope removal for lost forearm supination, and 1 fixation of a radial shaft fracture after a fall. CONCLUSION: IOM reconstruction using a suture-button construct is an effective treatment option for chronic forearm instability.

[Value of MRI in the diagnosis of radial head fracture with forearm interosseous membrane injury].

OBJECTIVE: To investigate the diagnostic value of MRI in radial head fracture with forearm interosseous membrane injuries. METHODS: From December 2011 to December 2012,26 patients with fractures of capitulum radial in our hospital were collected. There were 15 males and 11 females, ranging in age from 21 to 53 years old,with an average of 37.6 years old. All the patients visited hospital within 72 hours after injuries. X-ray radiography of full ulnar radial length in injured side, CT in injured side (three-dimensional reconstruction if necessary) and MRI (including the elbow and wrist joints) were performed within a week after the injury. The MRI manifestations of the forearm interosseous membrane (with or without damage, the injured location and the injury degree ) and the fractures degree of radial head were observed and compared for the relativity. RESULTS: Radial head fracture from Mason type I to III was associated with the forearm interosseous membrane injury. Radial head fracture degree was positive correlated with forearm interosseous membrane injury degree (P < 0.05). CONCLUSION: Radial head fracture with suspicious forearm interosseous membrane injury is necessary to take MRI for checking for any interosseous membrane injury and injury degree, then choose the right treatment for radial capitulum fracture, only in this way can be helpful for the functional recovery of elbow and forearm.

Comparative morphometry of the antebrachial and crural interosseous membranes: preliminary study for the use of the crural interosseous membrane in the surgical repair of the antebrachial interosseous membrane tears.

INTRODUCTION: Traumatic tears of the antebrachial interosseous membrane (AIOM) on its whole length are difficult to treat, particularly in the Essex-Lopresti syndrome. The number of ligamentoplasty techniques described in the literature witnesses the difficulty of its reconstruction and the absence of reliable and satisfying procedure. The aim of this study was to explore a new way of treatment, which consists in replacing the AIOM by the crural interosseous membrane (CIOM), harvested from the same patient. MATERIALS AND METHODS: A morphometric study of the AIOM and CIOM has been conducted on both sides of 15 formalin preserved corpses (i.e. 30 AIOM and 30 CIOM). Studied data were: length of forearms and legs, length and width (at different locations) of the membranes, in situ and after harvesting, and orientation of their fibers. The thickness of membrane was also measured but only after harvesting. RESULTS: Concerning the AIOM, the mean length was 13.3 cm in situ and 12.8 cm after harvesting. Its width was maximal at the union of middle and distal thirds with an average value of 1.7 cm in situ and 1.45 cm after harvesting. Mean thickness was 1 mm. Anterior fibers were oblique distally and medially (20.5° ± 0.95°), and posterior fibers were oblique distally and laterally (40° ± 3.4°). Concerning the CIOM, the mean length was 24.75 cm in situ and 23.9 cm after harvesting. Its width was maximal at the union of proximal and middle thirds with an average value of 2.3 cm in situ and 1.85 cm after harvesting. Mean thickness was 0.5 mm. Obliquity of its fibers was reverse of that of the AIOM: the anterior fibers were quite oblique distally and laterally (13° ± 2.6°), and the posterior fibers oblique were oblique distally and medially (24.2° ± 2.48°). DISCUSSION: From these results, one may conclude that the largest length and width of the CIOM allow its use as substitute for the injured AIOM. The orientation of its fibers should necessitate either its reversal while using the same side or the use of the CIOM of the opposite side; its relative sharpness could signify that its biomechanical properties could be worse. A biomechanical study is necessary to evaluate how this new way of replacing the AIOM could resist to the strains imposed on the forearm.

Experimental study on penetration of dental implants into the maxillary sinus in different depths

The exposing of dental implant into the maxillary sinus combined with membrane perforation might increase risks of implant failure and sinus complications. Objective: The purpose of this study was to investigate the effects of the dental implant penetration into the maxillary sinus cavity in different depths on osseointegration and sinus health in a dog model. Material and Methods: Sixteen titanium implants were placed in the bilateral maxillary molar areas of eight adult mongrel dogs, which were randomly divided into four groups according to the different penetrating extents of implants into the sinus cavities (group A: 0 mm; group B: 1 mm; group C: 2 mm; group D: 3 mm). The block biopsies were harvested five months after surgery and evaluated by radiographic observation and histological analysis. Results: No signs of inflammatory reactions were observed in any maxillary sinus of the eight dogs. The tips of the implants with penetrating depth of 1 mm and 2 mm were found to be fully covered with newly formed membrane and partially with new bone. The tips of the implants with penetrating depth over 3 mm were exposed in the sinus cavity and showed no membrane or bone coverage. No significant differences were found among groups regarding implant stability, bone-to-implant contact (BIC) and bone area in the implant threads (BA). Conclusions: Despite the protrusion extents, penetration of dental implant into the maxillary sinus with membrane perforation does not compromise the sinus health and the implant osseointegration in canine. .

Experimental study on penetration of dental implants into the maxillary sinus in different depths.

UNLABELLED: The exposing of dental implant into the maxillary sinus combined with membrane perforation might increase risks of implant failure and sinus complications. OBJECTIVE: The purpose of this study was to investigate the effects of the dental implant penetration into the maxillary sinus cavity in different depths on osseointegration and sinus health in a dog model. MATERIAL AND METHODS: Sixteen titanium implants were placed in the bilateral maxillary molar areas of eight adult mongrel dogs, which were randomly divided into four groups according to the different penetrating extents of implants into the sinus cavities (group A: 0 mm; group B: 1 mm; group C: 2 mm; group D: 3 mm). The block biopsies were harvested five months after surgery and evaluated by radiographic observation and histological analysis. RESULTS: No signs of inflammatory reactions were observed in any maxillary sinus of the eight dogs. The tips of the implants with penetrating depth of 1 mm and 2 mm were found to be fully covered with newly formed membrane and partially with new bone. The tips of the implants with penetrating depth over 3 mm were exposed in the sinus cavity and showed no membrane or bone coverage. No significant differences were found among groups regarding implant stability, bone-to-implant contact (BIC) and bone area in the implant threads (BA). CONCLUSIONS: Despite the protrusion extents, penetration of dental implant into the maxillary sinus with membrane perforation does not compromise the sinus health and the implant osseointegration in canine.

Fractal avalanche ruptures in biological membranes.

Bilayer membranes envelope cells as well as organelles, and constitute the most ubiquitous biological material found in all branches of the phylogenetic tree. Cell membrane rupture is an important biological process, and substantial rupture rates are found in skeletal and cardiac muscle cells under a mechanical load. Rupture can also be induced by processes such as cell death, and active cell membrane repair mechanisms are essential to preserve cell integrity. Pore formation in cell membranes is also at the heart of many biomedical applications such as in drug, gene and short interfering RNA delivery. Membrane rupture dynamics has been studied in bilayer vesicles under tensile stress, which consistently produce circular pores. We observed very different rupture mechanics in bilayer membranes spreading on solid supports: in one instance fingering instabilities were seen resulting in floral-like pores and in another, the rupture proceeded in a series of rapid avalanches causing fractal membrane fragmentation. The intermittent character of rupture evolution and the broad distribution in avalanche sizes is consistent with crackling-noise dynamics. Such noisy dynamics appear in fracture of solid disordered materials, in dislocation avalanches in plastic deformations and domain wall magnetization avalanches. We also observed similar fractal rupture mechanics in spreading cell membranes.

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.

Repair of a perforated sinus membrane with a palatal fibromucosal graft: a case report.

The sinus lift procedure in association with dental implant placement and autologous bone grafting enables clinicians to achieve the prosthetic rehabilitation of the posterior edentulous maxilla, when the vertical height of the atrophic crest is reduced. The most commonly reported intraoperative complication of sinus augmentation is membrane perforation, which may lead to infection, with the risk of graft loss or resorption, and acute or chronic sinusitis. We present a technique for repairing a perforated Schnei-derian membrane with a de-epithelialized fibromucosal graft harvested from the palate of a 50-year-old man. In the postoperative period, no wound infections, sinusitis, or bleeding were observed. This technique allowed good prosthetic rehabilitation 3 months postoperatively. This technical procedure is a quick and easy way to treat this surgical complication, allowing repair of the Schneiderian membrane perforation with autologous tissue, without other surgical accesses or need to modify the existing surgical access. In addition, our procedure causes no patient discomfort or adds significant morbidity, with only a moderate increase in surgical time compared to the planned procedure.

Mason type-I radial head fractures and interosseous membrane lesions--a prospective study.

BACKGROUND: The role of the forearm interosseous membrane (IOM) in trauma remains not fully understood. Information from experimental models simulating sudden axial loading of the IOM is limited. The results from several cadaver studies are controversially discussed in literature. Pronation and supination of the forearm as well as varus and valgus position of the elbow joint have been suspected to have influence on the injury pattern. The purpose of the current study, therefore, was to further investigate the role of the IOM in trauma mechanism. METHODS: We prospectively screened the forearms of 14 patients with Mason type-I radial head fractures for additional occult IOM lesions. The fractures were classified according to the Mason classification using plain radiographs. All patients were subjected to forearm magnetic resonance imaging visualizing the entire IOM within a week. Treatment consisted of nearly total immobilization of the elbow joint using a special elastic and gauze bandage for 7 days followed by an early motion recovery program. RESULTS: Partial disruptions of the distal part of the IOM were found in nine cases. The biomechanically essential interosseous ligament was not attained by these ruptures in any of the cases. None of the patient had the classical findings of the Essex Lopresti lesion. All patients had regular roentgenograms of both wrists. Patients were asymptomatic at the time of a 4-week follow-up. CONCLUSION: Our results suggest that injuries of the IOM are more frequent than generally expected. The findings support the conclusions of some of the previous cadaver studies. If IOM lesions are suspected, magnetic resonance imaging tomography should be performed.

Leg anterior compartment syndrome following ankle arthroscopy after Maisonneuve fracture.

We report a case of leg anterior compartment syndrome following ankle arthroscopy after Maisonneuve fracture. A 21-year-old football player sprained his left ankle. Plain radiography of his left ankle showed a lateral dislocation of the talus without obvious fractures. Plain radiography of his left lower extremity showed a spiral fracture of the proximal fibula approximately one third distal to the fibular head. According to these findings, we diagnosed this fracture as a Maisonneuve fracture and treated it by ankle arthroscopy and drilling of the talar osteochondral injury followed by arthroscopic ankle visualization during syndesmosis screw fixation. Six hours after surgery, the patient complained of pain in the lower extremity. We diagnosed acute compartment syndrome and performed emergent fasciotomy. One year after surgery, he was able to fully participate in athletic activities. We consider ankle arthroscopy to be available for the treatment of ankle fracture with the suspected complication of an intra-articular disorder such as a Maisonneuve fracture. However, with this type of ankle fracture, there is a higher potential risk of acute compartment syndrome developing than with other types of ankle fractures. Therefore we suggest that surgeons guard against this complication.

Essex-lopresti injuries.

The Essex-Lopresti injury results from a high energy trauma to the upper extremity causing significant instability to the forearm joint. The radial head is fractured, the interosseous membrane is torn, and the distal radioulnar joint is disrupted. Frequently, the greatest challenge with this specific injury pattern is the diagnosis, because it is often missed in the emergency room. Once the diagnosis has been established, surgical treatment focuses on the elbow (radial head fracture) and the wrist (distal radioulnar joint disruption) to restore forearm length and stability. Chronic or untreated Essex-Lopresti lesions continue to challenge treating physicians and often require salvage or reconstructive procedures to minimize pain and return function.

[Traumatic pathology of antibrachial interosseous membrane of forearm]. / Pathologie traumatique de la membrane interosseuse de l'avant-bras.

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.

Active range of motion as an indicator for ligament and membrane lesions in the upper cervical spine after a whiplash trauma.

In the present study, we examined whether active range of neck motion (AROM) differed between persons with and without a diagnosis of whiplash-associated disorder type 2 (WAD2) and explored whether magnetic resonance (MR)-verified lesions of specific ligaments or membranes at the craniovertebral junction was associated with increased or decreased motion in any particular direction among the WAD2 patients. A CROM goniometer was used for registration of flexion, extension, side bending (left and right) and rotation (left and right), respectively. The neck structures considered were the alar and the transverse ligaments, and the tectorial and the posterior atlanto-occipital membranes. Our study comprised 87 WAD2 patients and 29 control persons without any known neck injury. For comparing mean values of AROM between the groups, t-test and analysis of variance (ANOVA) were used. WAD patients had on average a shorter range of active motion for all movements compared with the control group. The difference was statistically significant for all measures considered, except side bending to the left. Among the WAD patients, increasing severity of lesions to the alar ligaments was associated with a decrease in maximal flexion and rotation. A similar pattern was seen for lesions to the transverse ligament, but the trend test was not significant. An abnormal posterior atlanto-occipital membrane was associated with shorter range of left rotation, with a significant trend test both in analyses with and without adjustment for lesions to other structures. No significant association was found in relation to lesions to the tectorial membrane, but very few persons had such lesions. These findings indicate that soft tissue lesions may affect neck motion as reflected by AROM. However, since lesions to different structures seem to affect the same movement, AROM alone is not a sufficient indicator for soft-tissue lesions to specific structure in the upper cervical spine.

Forearm interosseous membrane trauma: MRI diagnostic criteria and injury patterns.

OBJECTIVE: Define criteria for interosseous membrane (IOM) injury diagnosis using MRI, and characterize patterns of IOM disruption following forearm trauma. Our hypothesis is that most IOM injuries occur along the ulnar insertion, and MRI should be obtained following forearm trauma to assess IOM competency. DESIGN: Sixteen cadaver forearms were subjected to longitudinal impact trauma. Prior to and following injury, MR images were examined by a board-certified musculoskeletal radiologist using pre-defined criteria for determining IOM integrity. Each specimen was dissected and the viability/pattern of injury examined. The MRI and dissection results were compared using a double-blinded methodology. RESULTS: Eight of the 16 specimens demonstrated IOM trauma. Seven specimens demonstrated complete IOM disruption from the ulnar insertion, and one revealed a mid-substance tear with intact origin and insertion. The dorsal oblique bundle was disrupted in four specimens. MRI analysis identified IOM injury in seven of the eight forearms. The injury location was correctly identified in six specimens when compared to dissection observations. MRI determination of IOM injury demonstrated a positive predictive value of 100%, a negative predictive value of 89%, a sensitivity of 87.5% and a specificity of 100%. CONCLUSION: Our findings demonstrate the accuracy of MRI in identifying IOM disruption, and its ability to localize specific injuries in a clinically relevant model of forearm trauma. The injury patterns demonstrated most lesions occurred along the IOM's ulnar insertion, and in half of the injured specimens there was concomitant dorsal oblique bundle disruption.