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Stress fractures of the upper limb affect athletes from a wide range of sports. Athletes involved in throwing sports are particularly susceptible along with athletes from sports involving high repetitive and compressive loads such as gymnastics. Diagnosis can be made from clinical history, examination and radiography in some cases however MRI imaging is often required for definitive diagnosis. The mainstay of management is rest and activity modification however advanced pathology often requires surgical management for successful resolution and return to play. In the elbow, the bones susceptible to excessive stress in sport are the distal humerus, the olecranon process of the ulna, the coronoid process of the ulna, the sublime tubercle and the radial head. In immature patients, medial epicondyle apophysis is the most common location. The article presents a narrative review of the literature.

This study aimed to describe the involvement of the lesser sigmoid notch in fractures to the coronoid process. We hypothesized that injuries to the lateral aspect of the coronoid process regularly involve the annular ligament insertion at the anterior lesser sigmoid notch.Patients treated for a coronoid process fracture at our institution between 06/2011 and 07/2018 were included. We excluded patients 18 years, patients with arthritic changes or previous operative treatment to the elbow, and patients with concomitant injuries to the proximal ulna. In patients with involvement of the lesser sigmoid notch, the coronoid height and fragment size (anteroposterior, mediolateral, and craniocaudal) were measured.Seventy-two patients (mean age: 47 years ± 17.6) could be included in the study. Twenty-one patients (29.2%) had a fracture involving the lateral sigmoid notch. The mean anteroposterior fragment length was 7 ± 1.6 mm. The fragment affected a mean of 43 ± 10.8% of the coronoid height. The mean mediolateral size of the fragment was 10 ± 5.0 mm, and the mean cranio-caudal size was 7 ± 2.7 mm.Coronoid fractures regularly include the lesser sigmoid notch. These injuries possibly affect the anterior annular ligament insertion which is important for the stability of the proximal radioulnar joint and varus stability of the elbow.ZIEL: Ziel dieser Untersuchung war es, die Beteiligung der Incisura radialis ulnae bei Frakturen des Proc. coronoideus ulnae zu untersuchen. Hypothese der Studie war es, dass bei Verletzungen des lateralen Proc. coronoideus ulnae regelmäßig die Bandinsertion des Lig. anulare der Incisura radialis ulnae beteiligt ist.Patienten, die mit einer Fraktur des Proc. coronoideus ulnae zwischen 06/2011 und 07/2018 in unserer Institution behandelt wurden, wurden in diese Untersuchung eingeschlossen. Ausgeschlossen wurden alle Patienten 18 Jahren, mit arthrotischen Veränderungen oder vorangegangenen Operationen am Ellenbogen sowie bei begleitenden Verletzungen der proximalen Ulna. Bei Beteiligung der Incisura radialis ulnae wurden die Frakturfragmente (anterio–posterior, medio-lateral und kraniokaudal) sowie die Koronoidhöhe standardisiert in der CT vermessen.Insgesamt konnten 72 Patienten mit einem Alter von 47 ± 17,6 Jahren eingeschlossen werden. Hiervon zeigten 21 Patienten (29,2%) eine Beteiligung der Incisura radialis ulnae. Die mittlere anterio–posteriore Fragmentgröße war 7 ± 1,6 mm, im Mittel waren 43 ± 10,8% der Koronoidhöhe beteiligt. Die mittlere medio-laterale Fragmentgröße war 10 ± 5,0 mm, die kraniokaudalen Ausmaße 7 ± 2,7 mm.Frakturen des Proc. coronoideus ulnae involvieren regelmäßig die Incisura radialis ulnae. Diese Verletzungen können die Insertion des Lig. anulare umfassen, welches für die Stabilität des proximalen Radioulnargelenks sowie für eine Varusstabilität des Ellenbogens entscheidend ist.

Background: The aim of the study was to investigate the anatomy of the anterior nerve and artery of the elbow joint to provide reference on the relevant surgical approach to the elbow joint, and determine a simple better surgical approach for the treatment of part of the fractures of the elbow joint. Materials and methods: The upper extremities of 10 adult cadavers fixed by formaldehyde and perfused with red latex in the artery were observed to investigate the anatomic structure of the anterior approach to the elbow joint. From the clearance of the brachioradialis and pronator teres muscle to the approach of the neurovascular interval, we observed the states of the median nerve, the brachial, radial and ulnar arteries, and its branches through anatomical layers and measurement methods. Results: Through the anterior neurovascular interval approach to the elbow, nerve and artery can be protected, and the anterior structures of the elbow, such as the ulna coronoid process, humeroulnar joint and trochlea of the humerus, can be exposed. Conclusions: This study demonstrates that the anterior anatomical structure of the elbow joint including the trochlea of the humerus, coronoid process of the ulna and the front capsule of the elbow can be exposed through the anterior neurovascular approach to the elbow.

Considered to be a rare and very disabling condition, bilateral terrible triad of the elbow is a fracture-dislocation, which consists in a fracture of the radial head and also of the coronoid process of the ulna, all of this associated with a posterior displacement of the elbow and high instability. It was named "terrible triad" because of the poor outcome of bone healing and range of motion, both medium and long term. What we present is a special case, first because it was not a unilateral terrible triad injury but bilateral, and because the treatment was different for each elbow, which was interesting for comparing the outcome. Although both radial head fractures were comminuted, with different treatment options, for one of them open reduction and internal fixation was performed, while for the other one our option was replacement of radial head with a prosthesis. For both elbows we obtained good functional outcome at 1-year follow up.

Ziel der operativen Versorgung ist die Rekonstruktion des Processus coronoideus ulnae. Grosere Abscherfrakturen des Koronoids (Regan-Morrey Typ II–III, O’Driscoll „tip“ Subtyp 2 und „basal“ Subtyp 1–2) und Frakturen der medialen Facette (O’Driscoll „anteromedial“ Subtyp 1–3) konnen isoliert oder im Rahmen von „Terrible-triad-Verletzungen“ des Ellenbogens auftreten. Aufgrund der aus diesen Verletzungen resultierenden Instabilitat des Ellenbogens ist eine osteosynthetische Versorgung dieser Frakturen regelhaft erforderlich. Kontraindikationen fur eine primare Versorgung mit anatomischen Plattenosteosynthesen bestehen bei ausgedehnten Weichteilverletzungen sowie im Falle eines Infekts am Ellenbogen. Die Versorgung mittels winkelstabiler Plattenosteosynthese erfolgt uber einen medialen Zugang (Hotchkiss oder Spaltung des M. flexor carpi ulnaris). Nach Reposition der Frakturfragmente wird die winkelstabile Platte an die proximale Ulna verschraubt. Ruhigstellung im Oberarmgips bis zur Wundbehandlung. Anschliesend moglichst fruhfunktionelle Nachbehandlung unter Vermeidung von Varus- bzw. Valgusstress. In den behandelnden Zentren wurden im Zeitraum zwischen Januar 2015 und Juli 2018 insgesamt 11 Patienten mit praformierten anatomischen Plattensystemen versorgt. Nach einem mittleren Nachverfolgungszeitraum von 10,7 Monaten zeigte sich ein Mayo Elbow Performance Score von im Mittel 78,89 Punkten. Der Quick Disabilities of the Arm, Shoulder and Hand (Q-DASH) Score lag im Median bei 18,64 Punkten bei einem mittleren funktionellen Bogen von 118°.

Osteoid osteoma is a rare benign osteoblastic tumor that mainly occurs in the extra-articular segments of lower limb long bones. The elbow is an exceptional location for osteoid osteoma. The diagnosis is usually delayed since the elbow is a rare site for this tumor and unspecific clinical signs, such monoarthritis, may mimic other more common conditions. We report the case of a 16-year-old girl who presented with chronic monoarthritis of the elbow which was treated falsely as tuberculous arthritis and monoarticular rheumatoid involvement. The laboratory tests were negative. Computed tomography scan and magnetic resonance imaging showed the focal nidus at the coronoid process of the ulna with mild synovitis. The diagnosis of osteoid osteoma was not made until the disease had been progressing for eighteen months and the elbow had already become stiff. Arthroscopic excision of the lesion was performed, and histopathology of the nidus was consistent with osteoid osteoma. Since then, the patient has been pain-free with an improved elbow range of motion.

As a pivotal part of the elbow joint structure, the coronoid process of the ulna plays a vital role in maintaining elbow joint stability. Loss of coronoid process height causes instability of the elbow joint depending on the fracture characteristics and size. The diagnosis and treatment of coronoid process fractures has gained widespread attention from orthopedic surgeons. Nevertheless, few reports have described reconstruction of coronoid process fractures and defects that affect elbow joint stability. Treatment of elbow joint instability induced by coronoid process defects is challenging because most cases are complicated by other elbow joint injuries. Moreover, the clinical efficacy remains unclear. The present narrative review was performed to examine the research progress on reconstruction of the coronoid process. The findings of this review provide evidence for clinical repair and reconstruction of coronoid process defects and contribute to the published literature on this topic.

Summary An important accessory anatomical variation, exclusively human, and related to the muscular ventres of the flexor pollicis longus and flexor digitorum profundus is frequently denominated Gantzer. These variations have close relations with the anterior interosseous nerve (AIN), which provides, for many authors, by direct compression, one of the rare neuropathic syndromes. In this work, thirty-four forearms were dissected from the collections of the Medical School of the Federal University of Minas Gerais and the Department of Basic Sciences of the Federal University of Juiz de Fora, with a prevalence of 50% of the 34 forearms studied for the Gantzer muscle. The muscle relationship was mainly with the flexor pollicis longus muscle and only one occurrence related to the flexor digitorum profundus muscle, described as a rare occurrence of unilateral double formation of Gantzer muscle. Bilaterality was observed in 88.23% of the findings and the dominant innervation for this muscle variation occurred in 82.35% by the anterior interosseous nerve (AIN). The type morphological in all forms found was the fusiform, with 10.5 cm of total length and an average of 0.3 cm in diameter and all related, as origin, in the medial aspect of the coronoid process of the ulna, next to the origin of the flexor digitorum superficialis muscle. Our work largely reflected the findings of most publications and, considering the controversy of the occurrence of a compressive neuropathy, the data were not sufficient, from a strictly anatomical point of view, to confirm or refute the hypothesis.

Background The coracoid process plays an important role in maintaining the stability of the elbow joint. A fracture of the coronoid process is often treated via surgical approaches, including open reduction and internal fixation, which aim to regain a stable, flexible, and loadable joint. In this study, we compared the anterior, medial, and posterior approaches of internal fixation in the repair of fractures of the coronoid process of the ulna. Methods In this retrospective study, 147 patients with fractures in the coronoid process of the ulna were recruited and classified into the anterior group (n = 73), the medial group (n = 32), and the posterior group (n = 42) according to the surgical approach used for internal fixation. These patients were assessed with respect to incision, operative time, estimated blood loss, fracture healing, and postoperative complications. The Mayo Elbow Performance Score was used to evaluate any form of disability associated with elbow injuries. Multivariate logistic regression analysis was performed to investigate the factors influencing the efficacy of fractures of the coronoid process of the ulna. Results In the medial approach group, the operative time was longer, and perioperative blood loss and postoperative drainage volume were obviously increased compared with the anterior and posterior groups. The anterior group exhibited a better postoperative recovery compared with the medial, and posterior groups. Compared with the anterior group, fracture-healing time in the posterior group was further reduced, whereas elbow joint flexion extension and forearm rotation degree improved. Complications were significantly reduced in the posterior approach group compared with the anterior and medial groups. The factors influencing the efficacy of fractures of the coronoid process of the ulna included the Regan–Morrey classification, perioperative blood loss, and the internal fixation approach. Conclusion In summary, the approach used influences fracture healing or the outcome after osteosynthesis. The posterior internal fixation method produced satisfactory functional outcomes in patients with fractures of the coronoid process of the ulna.

The anconeus muscle is a small and minor functioning muscle located at the posterolateral elbow region. It helps forearm extension and tightening of the joint capsule. Despite its limited functions, pathologies of the anconeus muscle can mimic other abnormalities of the elbow joint. Here, we report a rare case of a traumatic anconeus muscle contusion in a 15-year-old boy due to falling during dance. MRI showed contusion in the anconeus muscle, as well as strain in the ulnar collateral ligament and edema in the coronoid process of the ulna. To our knowledge, this is the first described case of traumatic anconeus muscle contusion in the literature. The presence of long-lasting lateral elbow pain in trauma cases without fracture should alert clinicians to consider anconeus muscle abnormalities. MRI is the best modality for diagnosis in these cases.

Ultrasound (US) could visualize the pathological anatomy of HO and the enlargement site and compression location of the nerve in the cubital tunnel [1]. We read with great interest the article of Jačisko et al[2]. In addition, we report rare US images of HO in direct contact with the swollen ulnar nerve in the cubital tunnel that was not detected by plain radiography. A 60-year-old female presented with a six-month history of elbow pain. Her pain was located at the medial side of the right elbow joint and accompanied by numbness of the fifth finger. She had a history of excessive manual labor due to her occupation as a gardener over the past few decades. The numbness began with the fifth finger initially and gradually extended toward the medial side of the elbow joint. US images showed hyperechoic masses causing acoustic shadowing, in direct contact with the ulnar nerve in the cubital tunnel. The HO seems to be related to compression of the ulnar nerve. The ulnar nerve was swollen (Figure 1-a, b). The maximal cross-sectional-area was 0.10 cm2. Plain elbow radiographs demonstrated osteophyte formation in the coronoid process of the ulna, the coronoid fossa of the humerus, and in the radial head (Figure 1-c). Radiographic imaging showed no heterotopic bone formation in the soft tissues surrounding the medial side of the right elbow. We performed US-guided perineural injection with a mixture of 1 cc of 10 mg triamcinolone and 3 cc of 0.2 % ropivacaine. Her pain and numbness gradually diminished with no adverse effects. Her pain reduced by 70% after two weeks, with pain improvement sustained for 6 months after the injection. Jačisko et al[2]have presented some diagnostic US imaging on neuropathy caused by HO located close to the ulnar nerve in the cubital tunnel. Especially, this case showed definite heterotopic bone formation in the soft tissue surrounding the medial side of the elbow on plain radiography. The classic sonographic patterns of HO were defined by the presence of central hypoechoic area surrounded by foci of calcification [3, 4]. The distortion of normal soft tissue and the formation of hypoechoic areas, with or without foci of calcification can also be shown as early signs[3, 4]. The use of US for HO is highly sensitive and provides an earlier diagnosis compared with other radiologic modalities [3-5]. It can be an effective treatment strategy and may improve the prognosis of neuropathy. We highlight that US evaluation can provide early diagnostic information about ulnar nerve morphology and various HO formations even if plane radiographs did not show heterotopic bone formation in the soft tissues surrounding the medial side of the elbow.

The median nerve passes through the humeral and ulnar heads of the pronator teres muscle (PT), although variations such as absence of the ulnar head may exist. We observed histological sections of the upper extremity from 24 embryos and fetuses. In the early stage, the PT extended between the radius and the medial epicondyle of the humerus, but no candidate for the ulnar head was found. In mid-term fetuses, the ulnar margin of the PT was attached to the elbow joint capsule. Moreover, in late-stage fetuses, a small deep part of the PT arose from the thick joint capsule of the humero-ulnar joint near the coronoid process of the ulna. This joint capsule also provided the most proximal origin of the flexor digitorum profundus muscle. Therefore, we considered fetal PT origin from the capsule as a likely candidate for the ulnar head. Consequently, the PT seemed to develop from a single anlage through which the median nerve passed, but later - possibly after birth - a small PT origin from the joint capsule appeared to obtain an aponeurosis connecting the muscle fiber to the ulna. This secondary change in PT morphology might explain the muscle variation seen in adults.

Osteochondropathy of the proximal ulnar bone is a rare disease that affects not only the ulnar, but also the venous process. To our knowledge, the existing domestic and foreign medical literature does not provide a description of osteochondropathy of the coronal process, a topic of considerable interest from the point of view of diagnosis and treatment. Here, we describe a clinical case of osteochondropathy of the coronal process and present a clinical picture of the defect of the elbow joint in the patient, with radiographs taken before and after the surgery. In the present clinical case, postoperatively, the patient reported pain; however, the elbow joint function was fully restored, indicating the success of the treatment and that active surgical treatment of this disease is adequate and timely.

Stress fractures occur as a result of force excess to the osseous strength of a bone and most commonly occur as an overuse phenomenon in occupational or recreational physical pursuits. In the elbow, the bones susceptible to excessive stress in sport are the distal humerus, the olecranon process of the ulna, and rarely the coronoid process of the ulna, the sublime tubercle, or the radial head. In immature patients, medial epicondyle apophysis is the most common location.

The coronoid process of the ulna is an important bony stabilizer of the elbow forming an anterior buttress with the radial head to avoid posterior subluxation or dislocation of the elbow (Fig. 38.1). Specific fracture types are associated with distinct patterns of traumatic elbow instability. Coronoid fractures are classified using the O’Driscoll classification based on fragment morphology: type 1 are tip fractures associated with terrible triad elbow fracture-dislocations, type 2 are anteromedial facet fractures associated with posteromedial varus rotational-type injuries (PMVRI), and type 3 are large basal fracture associated with olecranon fracture-dislocations.

Medial compartment erosion is an advanced stage of medial coronoid disease, an important cause of elbow lameness in dogs, with treatment and the expected prognosis depending on the extent of the cartilage lesions. The identification of specific computed tomographic (CT) findings might facilitate the nonsurgical diagnosis and add to treatment decision making. Aims of this retrospective, analytical, method comparison study were to describe CT findings in elbows of dogs arthroscopically diagnosed with medial compartment erosion and to compare CT vs. arthroscopic findings. A total of 56 elbows met inclusion criteria. Elbows with focal (n = 13), diffuse (n = 11), and complete (n = 32) erosion were compared. Prevalence findings for CT lesions were as follows: periarticular osteophytosis (100%), abnormal shape of the medial coronoid process of the ulna (96.4%), and subchondral bone defect of the medial part of the humeral condyle (MHC; 96.4%). The three groups significantly differed for presence of medial coronoid process fragmentation, radial head subchondral bone sclerosis, and widening of the humeroulnar joint space. No significant agreement was found between CT and arthroscopy for presence of a subchondral bone defect of the MHC. A significant agreement was found between CT and arthroscopy for presence of fragmentation of the medial coronoid process. However, some of the calcified body/fragment(s) visualized on CT in the region of the medial coronoid process could not be identified via arthroscopy. Findings indicated that an accurate estimation of the extent of the elbow cartilage lesions still requires arthroscopic joint inspection.

Background The attachment of the anterior joint capsule on the ulnar coronoid process is not yet completely understood. The purpose of this study was to clarify the anatomic relationship between the anterior capsule of the elbow joint and the tip of the coronoid process. Methods Seventeen embalmed elbows were used for this anatomic study. The anterior capsule of the elbow joint was reflected, and the attachment of the capsule on the coronoid process was exposed. The attachment of the joint capsule on the coronoid process was macroscopically and histologically observed, its relationship to the coronoid tip was assessed, and the length of the attachment of the joint capsule was measured. Results The length of the capsule attachment at the radial side of the coronoid (11.9 mm) was greater than that at the ulnar side (6.1 mm). The bone thickness on the coronoid tip from the proximal edge of the joint capsule attachment was 1.9 mm; together, the cartilage and bone thickness was 4.7 mm. At the radial side of the coronoid, the thickness of the joint capsule at the proximal aspect of the attachment of 2 samples was 0.6 mm and 0.3 mm, and that at the tip of the coronoid was 2.6 mm and 1.7 mm, respectively. Conclusions The anterior capsule of the elbow joint had a substantial attachment on the radial side of the coronoid process. The subtype 2 tip fractures of the O'Driscoll classification included the joint capsule attachment, joint cartilage, and subchondral bone.

Terrible triad injury of the elbow is a complex injury that is classically defined as elbow dislocation along with fractures of the coronoid process of the ulna and the radial head. The injury is usually associated with typical soft-tissue disruptions (with common involvement of the lateral collateral ligament complex, elbow joint capsule, as well as the common extensor and flexor-pronator tendons) that are best understood in the context of injury mechanism as well as the role and relevance of the various elbow stabilizers. The goals of this article are to review the pertinent anatomy, mechanism of injury, classification and imaging of terrible triad injuries of the elbow with brief descriptions of treatment, and complications of this complex injury.

Coronoid process fractures of the ulna are difficult to treat, and are associated with stiffness, recurrent instability, and pain. Hence, treatment of coronoid process fractures are challenging for surgeons. The purpose of this study was to report the clinical outcomes of an anterior surgical approach associated with plate fixation for Regan and Morrey type II or type III fractures of the coronoid process.We evaluated 16 consecutive patients who underwent surgical treatment for fracture of the coronoid process of the ulna from March 2012 to July 2016. Ten patients had a type II fracture, and 6 patients had a type III fracture. All patients underwent surgical treatment for coronoid process fracture through an anterior approach. While preserving the neurovascular structure, all fractures were treated with buttress plate fixation, maintaining the gap between brachial artery and median nerve. Each patient was treated with concentric reduction of both the ulnotrochlear and the radiocapitellar articulations, without any evidence of elbow instability, except 1 case, who showed some medial instability.At the final follow-up, solid osseous union was confirmed for all coronoid fractures. The average time to radiologic union was 16.3 weeks. The mean flexion-extension arc was 124.25 ± 12.12 degree, with a mean flexion contracture of 8.25 ± 4.36 degree, and further flexion of 132.5 ± 9.31 degree. The mean forearm rotation arc was 167.81 ± 10.49 degree. Fifteen patients achieved a functional arc of motion. The mean Mayo elbow performance score was 92.1 points, with 12 excellent cases and 4 good cases.Coronoid process fractures of the ulna can be treated successfully with plate fixation through an anterior surgical approach, which allows for accurate reduction and rigid internal fixation and early functional exercise, resulting in a reasonable outcome.

Incidence of auxiliary head of the flexor pollicis longus muscle has been described repeatedly. Accessory head has been noted arising from the lateral or more rarely from the medial border of the coronoid process of the ulna. During routine dissection, we found a rare case of an additional slip of tendinous origin of flexor pollicis longus muscle from the medial epicondyle of the humerus. However, such anomaly was not found on the left side. The embryological source and clinical impact of the current incident are discussed.

Objective To document the progression of disease after an unloading procedure when combined with arthroscopic debridement to treat osteochondrosis (OC) lesions affecting the medial humeral condyle in juvenile dogs without medial compartment disease. Study Design Retrospective case series. Animals Dogs with medial humeral condyle OC (n = 6). Methods Dogs with medial humeral condyle OC (9 elbows) were treated by arthroscopic debridement of the OC lesion and sliding humeral osteotomy (SHO). Outcomes were assessed by radiography (n = 9), 2nd-look arthroscopy (9) and clinical examination including lameness assessment (9) at 18–28 months after surgery. Results Seven elbows had marked progression of pathology affecting the medial compartment, 5 elbows developed subsequent fragmentation of the medial coronoid process of the ulna [FMCP], 2 elbows had fibrocartilaginous infill of the humeral defect without development of coronoid pathology. Conclusion This limited case series suggests that medial compartment disease develops despite unloading of the medial compartment using a distal diaphyseal SHO in juvenile dogs with OC.

Osteogenesis imperfecta (OI) type V is a specific OI phenotype with interosseous membrane calcification of the forearm and hyperplastic callus formation as typical features. The causative gene mutation for OI type V has been recently discovered. The purpose of this report is to review the clinical and radiographic characteristics of mutation confirmed OI type V in detail. Sixteen (nine familial and seven sporadic) patients were enrolled in the study. Blue sclera and dentinogenesis imperfecta were not evident in any patient. However, hypodontia in the permanent teeth, ectopic eruption, and short roots in molars were additionally observed in 11 patients. Of the radiographic abnormalities, cortical thickening and bony excrescence of interosseous margin of the ulna was the most common finding, followed by overgrowth of the olecranon and/or coronoid process of the ulna. Slender ribs and sloping of the posterior ribs with or without fractures were also a consistent finding. Hyperplastic callus was detected in 75% of patients and was commonly encountered at the femur. Heterotopic ossification in the muscles and tendon insertion sites were noted in four patients, which resulted in bony ankylosis or contracture of joints. The current study confirms common clinical and radiographic findings of OI type V and reports additional phenotypic information. These observations provide clues to recognize OI type V more promptly and guide to direct targeted molecular study. © 2013 Wiley Periodicals, Inc.

The aim of this study was to clarify the morphological characteristics of the intermuscular aponeurosis between the flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS; IMAS), and that between the FCU and flexor digitorum profundus (FDP; IMAP), and their topographic relationships with the ulnar nerve. Fifty limbs of 38 adult cadavers were studied. The IMAS extended along the deep surface of the FCU adjoining the FDS, having the appearance of a ladder, giving off “steps” that decreased in width from superficial to deep around the middle of the forearm. Its proximal part divided into two bands connected by a thin membrane, and was attached to the medial epicondyle and the tubercle (the most medial prominent part of the coronoid process of the ulna), respectively. The IMAP extended deep between the FCU and FDP from the antebrachial fascia, and its distal end was located on the posterior border of the FCU. The IMAP became broader toward its proximal part, and its proximal end was attached anterior and posterior to the tubercle and the olecranon, respectively. The ulnar nerve passed posterior to the medial epicondyle and then medial to the tubercle, and was crossed by the deep border of the IMAS at 58.3 ± 14.1 mm below the medial epicondyle. The deep border of the IMAS and aberrant tendinous structure passing across the ulnar nerve, or the parts of the IMAS and IMAP passing posterior to the ulnar nerve are potential causes of ulnar nerve compression.

Authors chose anterior approach through the antecubital fossa for better exposure in that case of isolated coronoid process fracture. The objective of the study was to report validity of anterior approach for the Regan and Morrey type III, isolated fracture of the coronoid process of the ulna without residual valgus or varus instability. From January 2007 and January 2010, we evaluated eleven consecutive patients (7 men, 4 women; mean age 44 years; range 25-67 years) who underwent surgical fixation through the anterior approach. The mean follow-up period was 21 months (range 15-34 months). Preoperative and follow-up roentgenograms were evaluated for assessment of the fracture configuration and confirmation of fracture union. Clinical evaluation included an analysis of surgical complication, range of motion, Mayo elbow performance score, and DASH (disability of the arm, shoulder, and hand) score. Fractures were mainly fixed with plate and screws in 8 cases, cannulated screws in 3 cases. There was no residual joint instability after fracture fragment fixation. All fractures were united, and the average union time was 15.2 weeks with a range of 11-20 weeks. Mean flexion contracture of the elbow was 3.6° (range 0°-10°), and further flexion was 130.9° (range 125°-140°) at the last follow-up. Mean Mayo elbow performance score was 92.3 (range 80-100 points), and mean DASH score was 5.9 (range 1.6-8.3 points). In conclusion, Primary fixation of the coronoid process fractures through the anterior approach could be particularly useful in the Regan and Morrey type III isolated coronoid process fractures.

Transverse divergent dislocation of the elbow, in which the radius and ulna dislocate in diverging directions, is an extremely rare injury (19 cases have been reported in the literature). Usually, this type of elbow dislocation occurs in children, and an adult case is extremely rare. In this report, we present a case of a transverse divergent dislocation of elbow in a 20-year-old woman, treated with conservative method and long-arm cast immobilization. At 9 years, she had no pain in the elbow, returned to full activities and had normal function. The X-ray of the elbow was normal, except for a small nonunited bony fragment adjacent to the coronoid process of the ulna.

Objective: To describe in detail the computed tomographic findings in elbows of dogs with fragmentation of the medial coronoid process of the ulna. Methods: Retrospective review of computed tomographic images of 58 elbows that had displaced medial coronoid process fragment(s), non-displaced medial coronoid process fragment or a stable fissure in the articular cartilage of the medial coronoid process at arthroscopy. Results: Bone fragments were observed in 85 per cent elbows with a displaced fragment at arthroscopy, in 18 per cent elbows with a non-displaced fragment and in 29 per cent elbows with a stable fissure. Fissures in the subchondral bone were observed in computed tomographic images of 43 per cent elbows that had a stable fissure at arthroscopy. Abnormal shape, sclerosis and lucency affecting the medial coronoid process, subchondral sclerosis of the ulna and humerus, irregular radial incisure of the ulna and periarticular osteophytes were observed in a similar proportion in dogs regardless of the arthroscopic findings. Kissing lesions affecting the medial aspect of the humeral condyle were mainly associated with displaced fragments. Signs of joint incongruity were observed in dorsal and sagittal reconstructed computed tomographic images in 24 per cent elbows. Clinical Significance: A wide range of abnormalities may be observed in computed tomographic images of dogs with fragmented medial coronoid process. Computed tomographic is moderately sensitive for detection of fragments.

Purpose: The purpose of this study was to evaluate the results of eight cases of coronoid process fractures that were fixed with a plate. Materials and Methods: Eight coronoid process fractures were treated by plating and these cases were reviewed retrospectively. Six patients were men and two were women. The average age was 41 years (range: 22-79) at the time of injury. According to Regan’s classification, there were five type 2 and three type 3. According to O’Driscoll’s classification, there were five anteromedial type and three base type. Open reduction and internal fixation with a plate were performed through a medial approach by splitting of the two heads of the flexor carpi ulnaris. The patients were follow-up for a mean of 15.8 months (range: 6-25). We evaluated the clinical outcomes with using the Mayo Elbow Performance Score. Results: The average active motion of the elbow joint was 120。 . The average Mayo Elbow Performance Score was 86.9. There were 5 excellent results, 1 good result and 2 fair results. Summary: Plating through a medial approach of the elbow provided stable fixation and satisfactory union for treating displaced coronoid process fractures with the unstable elbow.

Fractures of the coronoid process of the ulna generally occur in relatively high-energy injuries and are commonly associated with injuries to other structures around the elbow. Damage to the coronoid process in addition to other elbow structures may complicate treatment. Several approaches have been used in the management of coronoid process fractures. This paper reports a method of coronoid process fracture fixation using suture anchors.

The purpose of this study was to provide a detailed description of the anatomy of the coronoid process of the ulna and to use magnetic resonance (MR) images and anatomic correlation with cadavers to show the macroscopic configuration of this structure. Photography and high-resolution radiography were performed in 26 ulna specimens from the collection of a local museum. MR imaging of the coronoid process of 11 cadaveric elbows was performed. The images were compared with those seen on anatomic sectioning. The anteromedial rim of the coronoid process of the ulna had a regular surface, without osseous irregularities or facets in 69.2% of the specimens. In 30.8% of the specimens, the anteromedial rim was not regular and a small ridge could be identified. The insertion site of the joint capsule was onto the anterior aspect of the coronoid process, at an average distance of 5.9 mm distal to the tip. The attachment of the anterior band of the ulnar collateral ligament at the sublime tubercle was flush with the articular margin in 63.6% of the specimens. In 36.4% of the specimens, a more distal attachment, with a separation between the undersurface of the ligament and the adjacent tubercle, was seen. The brachialis tendon was attached to the coronoid process at a mean distance of 12.1 mm distal to the tip. The coronoid process of the ulna is a small osseous structure with a complex anatomy and presents some anatomical variations.

Objectives: To compare ulnar trochlear notch bone radiopacity in Labrador retrievers with and without fragmented medial coronoid process using quantitative analysis of film density on digitised radiographs. Methods: Mediolateral view elbow radiographs from Labrador retrievers (n=34) aged between six and 18 months were obtained and digitised. Images from dogs with an arthroscopic diagnosis of fragmentation of the medial coronoid process (n=17) were compared with that of a control population (n=17), and this data subject to statistical analysis. Results: A statistically significant relationship between the presence of increased trochlear notch radiopacity and a fragmented medial coronoid process was identified. Fractional analysis of this area shows the region of greatest difference in radiopacity between normal and fragmented medial coronoid process cohorts to be in the trochlear region of the medial coronoid process of the ulna. A decrease in radiopacity values in the dysplastic group versus the normal cohort was observed for the region of the proximo-caudal ulnar trochlear notch. Clinical Significance: An increase in ulnar trochlear notch radiopacity is a finding associated with fragmentation of the medial coronoid process in Labrador retrievers.

Congruity of the ulnohumeral joint, especially its anterior portion, is an important stabilizer of the elbow joint. We report on 3 patients in whom the insufficiency of the coronoid process, such as nonunion or a flattened trochlear notch, was associated with posterolateral rotatory instability of the elbow. In our opinion, addressing the anterior bony integrity of the ulnohumeral joint, in addition to the ligamentous stabilizer and mechanical axis, is essential to achieve stability in these circumstances. This issue is discussed with a review of the literature.

The terrible triad is an uncommon injury, which includes an elbow posterior dislocation with fractures of the radial head and coronoid process of the ulna. In addition there is rupture of the lateral and medial collateral ligaments. The short-term and long term results are historically poor, with a high rate of complications. The main objective of this study is to report the results of a multicentre study of patients who sustained the terrible triad injury focusing on surgical treatment in order to offer a standardized surgical protocol. We retrospectively review the results of surgical treatment of eighteen terrible triads from a multicentre study of 226 elbow dislocations. At an average follow up of 31.5 months postoperatively, all eighteen patients returned for clinical examination, functional evaluation, and radiographs. The mean MEPS score value was 78 (25-100), which correspond to three excellent results, ten good results, three fair results, and two poor results. Five early and three late complications were reported. This particular case of elbow dislocation is very unstable and leads to many complications. The surgeon should attempt to restore stability by preserving the radial head whenever possible or replacing it with prosthesis otherwise, by repairing the lateral collateral ligament and performing fixation of the coronoid fracture. If after anatomical restoration of stability elements, the elbow remains unstable, options include repair of the medial collateral ligament or stabilization assumed by hinged external fixator.

The coronoid process is critical to elbow stability and is vulnerable during injury. Traumatic elbow injures are relatively uncommon, so it is important for surgeons to be mindful of the importance of specialized treatment of the coronoid for optimal elbow function. Optimal coronoid fracture fixation is determined by fracture morphology, which can usually be predicted based on the overall pattern of injury. There is evidence that improved understanding of coronoid fractures and their management is improving the results of treatment.

This article has been withdrawn because it is an inadvertent duplication of an article that has already been published in J. Shoulder Elbow Surg., 14 (2005) 60–64, doi:10.1016/j.jse.2004.04.012 . The journal wishes to point out that there was an inadvertent duplicate publication of same article with slightly different titles. There was no intent in any way on the part of the authors to publish the article in duplicate, and the journal regrets the error. The second of the two articles has therefore been withdrawn from J. Shoulder Elbow Surg., 15 (2006) e5–e8.

Purpose The coronoid fractures that occur in the terrible-triad pattern of traumatic elbow instability (posterior dislocation with fractures of the radial head and coronoid) usually are small transverse fragments. Attempts to classify these fragments according to height as suggested by Regan and Morrey have been inconsistent and contentious. The purpose of this study was to quantify coronoid fracture height in terrible-triad injuries. Methods The height of the coronoid process of the ulna and the coronoid fracture fragment were measured on computed tomography scans of 13 patients with terrible-triad–pattern elbow injuries. Two observers performed the measurements with excellent intraobserver and interobserver reliability. Results The total height of the coronoid process of the ulna averaged 19 mm. The average height of the coronoid fracture fragment was 7 mm. This corresponds to an average of 35% of the total height of the coronoid process. Conclusions The transverse coronoid fractures associated with terrible-triad elbow injuries have a variable height that may not be easy to classify according to the system of Regan and Morrey. Classification of coronoid fractures according to fracture morphology and injury pattern may be preferable.

It has been suggested that specific types of coronoid fractures are associated strongly with specific patterns of traumatic elbow instability. This hypothesis was tested in a review of a large consecutive series of patients with a fracture of the coronoid as part of a fracture-dislocation of the elbow.One surgeon repaired 67 coronoid fractures as part of a fracture-dislocation of the elbow over a 7-year period. Each coronoid fracture was characterized on the basis of surgical exposure. Pearson chi-square analysis was used to evaluate the association of the coronoid fracture type with 1 of 4 common patterns of elbow fracture-dislocation.The coronoid fracture was associated with an anterior (6 patients) or posterior (18 patients) olecranon fracture-dislocation in 24 patients, an elbow dislocation and radial head fracture in 32 patients, and a varus posteromedial rotational instability pattern injury in 11 patients. Among the 24 patients with olecranon fracture-dislocations 22 had large coronoid fractures and 2 had small (50%) coronoid fractures. All 32 patients with terrible-triad injuries had small (50%) coronoid fractures with 1 of these being a fracture of the anteromedial facet of the coronoid. Among patients with varus posteromedial rotational pattern injuries 9 had small fractures of the anteromedial facet and 2 had larger fractures. The association of coronoid fracture type with injury pattern was strongly statistically significant for both classification systems.The following strong associations were confirmed by this study: large fractures of the coronoid process with anterior and posterior olecranon fracture-dislocations, small transverse fractures with terrible-triad injuries, and anteromedial facet fractures with varus posteromedial rotational instability pattern injuries. An awareness of these associations and their exceptions may help guide the optimal management of these injuries.Therapeutic, Level IV.

Posterior dislocation of the elbow with associated fractures of the radial head and the coronoid process of the ulna is referred to as terrible triad injury (TTI). We report three cases of TTI. The three patients were a 59-year-old female, a 43-year-old male, and 52-year-old male. All cases were treated by ostheosynthesis.We recognized posterolateral rotatory instability (PLRI) of the elbow in one case after operation. PLRI consists of the inadequate operation of a front bone factor (radial head and coronoid process) and the lateral collateral ligament. We think that PLRI is a poor prognosis factor of TTI and repair of the lateral collateral ligament is of great significance.

Background The results of elbow dislocations with associated radial head and coronoid fractures are often poor because of recurrent instability and stiffness from prolonged immobilization. We managed these injuries with a standard surgical protocol, postulating that early intervention, stable fixation, and repair would provide sufficient stability to allow motion at seven to ten days postoperatively and enhance functional outcome. Methods We retrospectively reviewed the results of this treatment performed, at two university-affiliated teaching hospitals, in thirty-six consecutive patients (thirty-six elbows) with an elbow dislocation and an associated fracture of both the radial head and the coronoid process. Our surgical protocol included fixation or replacement of the radial head, fixation of the coronoid fracture if possible, repair of associated capsular and lateral ligamentous injuries, and in selected cases repair of the medial collateral ligament and/or adjuvant-hinged external fixation. Patients were evaluated both radiographically and with a clinical examination at the time of the latest follow-up. Results At a mean of thirty-four months postoperatively, the flexion-extension arc of the elbow averaged 112 degrees +/- 11 degrees and forearm rotation averaged 136 degrees +/- 16 degrees . The mean Mayo Elbow Performance Score was 88 points (range, 45 to 100 points), which corresponded to fifteen excellent results, thirteen good results, seven fair results, and one poor result. Concentric stability was restored to thirty-four elbows. Eight patients had complications requiring a reoperation: two had a synostosis; one, recurrent instability; four, hardware removal and elbow release; and one, a wound infection. Conclusions Use of our surgical protocol for elbow dislocations with associated radial head and coronoid fractures restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. We recommend early operative repair with a standard protocol for these injuries.

SummaryIn a retrospective trial over eight years 518 joints from 421 dogs with fragmented medial coronoid process of the ulna (FCP) were included. Seventy-five joints had an additional osteochondrosis dissecans of the medial aspect of the humeral condyle. Forty-six point eight percent of the dogs (197/421) were younger than one year. Two hundred and forty-seven joints were treated by conventional arthrotomy and 271 joints were treated by arthroscopy. Two hundred and thirty-eight cases (103 treated by arthrotomy and 135 by arthroscopy) were re-evaluated clinically and radiographically and 191 cases (88 treated by arthrotomy and 103 by arthroscopy) by means of a questionnaire at an average of 23 and 21 months after the operations, respectively. Forty-two point four percent (81/191) of the cases treated by arthrotomy did not show any lameness, 29.3% (56/191) showed temporary lameness after rest or heavy exercise, and 28.3% (54/191) showed constant lameness. The signs of which had, however, been reduced by surgery in 14 of these cases. Sixty point one percent (143/238) of the cases treated by arthroscopy did not show any lameness, 29.4% (70/238) showed temporary lameness after rest or heavy exercise and 10.5% (25/238) showed constant lameness, out of which four cases had improved after surgery. In the cases treated by arthroscopy, the period of convalescence was shorter. Differences between these methods were not observed with respect to the development of subsequent arthrosis. The results of the study show that arthroscopy, with its minimal invasive character, gives better functional results than conventional arthrotomy. However, the development of secondary arthrosis cannot be avoided by either method.

SummaryIn a retrospective and prospective trial over six years, 17 joints from 13 dogs presented with incomplete ossification of the humeral condyle (IOHC) were included. All dogs showed lameness of the forelimb but no humeral condylar fractures. One dog showed a fracture of the olecranon. Four of the bilaterally affected dogs showed only unilateral lameness. 53.8% of the dogs (7/13) were younger than one year. With regard to breed distribution, the German Wachtel was most frequently represented with three dogs. In 12 dogs the diagnosis was made by radiography in a craniocaudal view, and seven dogs could be further investigated by computed tomography. In one dog the diagnosis was only made during arthroscopy. Two joints showed an additional fragmented medial coronoid process of the ulna and another two an osteochondrosis dissecans of the medial humeral condyle. During arthroscopy, all joints showed a clearly visible fissure line in the joint cartilage between the humeral condyles. In ten joints the I0HC was treated with a transcondylar lag screw under arthroscopic control. Three of the four bilaterally affected dogs were treated only unilaterally because of a lack of lameness on the other side. In the dog with the olecranon fracture, only the fracture was treated. The patients were rechecked clinically and radiologically (n = 10) or by means of a questionnaire (n = 1) at an average of 26 months post operation. Seven cases, six of them treated by lag screw fixation, did not show any lameness. Three joints (one dog with olecranon fracture, two unilaterally affected dogs with lag screw fixation) showed some degree of lameness after heavy strain and one dog showed a continuous slight lameness. The four bilaterally affected and only unilaterally treated dogs showed no lameness on the untreated joint. With regard to development of arthrosis, six radiographically examined joints showed no increase in arthroses. In five joints the increase was mild and in two joints moderate. In six joints with lag screw fixation, the IOHC was radiographically unified and was confirmed by computed tomography in three cases.

Background There is no universally accepted approach to the elbow for the fixation of coronoid process fractures. This study aims to introduce a novel anterior surgical approach for the fixation of the ulnar coronoid fracture, with minimal surgical dissection damage and excellent visualization for reduction and internal fixation. Hypothesis The anterior approach can facilitate satisfactory outcomes for coronoid process fractures. Material and methods From February 2010 to July 2014, 12 patients (8 males and 4 females; range: 14–62 years; mean age: 31 years) with a closed fracture of the coronoid process of the ulna were included in this study. According to Adams classification, we included 5 type II, 3 type III, 3 type IVAM, and 1 type IVAL. The fractures were treated operatively via an anterior approach between nerves and blood vessels. The anatomical reduction and fixation with cannulated screws or a mini plate was easily performed. One elbow showed significant joint instability, necessitating, another incision to repair the lateral collateral ligament, and a subsequent operation with a hinged external fixator was required. The remaining patients received a splint for 2 weeks followed by functional exercises. Results Mean follow-up was 21 months (13–36). Fracture union was achieved in each patient. The arc of elbow flexion and extension were (135 ± 15)°, and forearm pronation/supination were restored to (165 ± 15)°. When compared with the normal side, there was no significant difference in the functional outcome ( P > 0.05). According to Morrey's scale, the functional recovery of the injured arms was assessed as excellent in eleven patients and good in one. Mild heterotopic ossification was found in one case, which had not impaired the elbow function. No other complications were noted. Conclusions The anterior approach has the benefits of simplicity, safety, minimal invasion, excellent exposure, and satisfactory prognosis for coronoid process fractures. Level of evidence Prospective study, level IV.

The elbow joint is one of the feline appendicular joints most commonly and severely affected by degenerative joint disease. The macroscopic and histopathological lesions of the elbow joints of 30 adult cats were evaluated immediately after euthanasia. Macroscopic evidence of degenerative joint disease was found in 22 of 30 cats (39 elbow joints) (73.33% cats; 65% elbow joints), and macroscopic cartilage erosion ranged from mild fibrillation to complete ulceration of the hyaline cartilage with exposure of the subchondral bone. Distribution of the lesions in the cartilage indicated the presence of medial compartment joint disease (most severe lesions located in the medial coronoid process of the ulna and medial humeral epicondyle). Synovitis scores were mild overall and correlated only weakly with macroscopic cartilage damage. Intra-articular osteochondral fragments either free or attached to the synovium were found in 10 joints. Macroscopic or histologic evidence of a fragmented coronoid process was not found even in those cases with intra-articular osteochondral fragments. Lesions observed in these animals are most consistent with synovial osteochondromatosis secondary to degenerative joint disease. The pathogenesis for the medial compartmentalization of these lesions has not been established, but a fragmented medial coronoid process or osteochondritis dissecans does not appear to play a role.

Median nerve neuropathy following an elbow injury is uncommon. When it occurs, understanding the median nerve distribution and anatomy is crucial for identifying the cause and for distinguishing cases that can be managed with observation as opposed to intervention. The consequences of misdiagnosis can result in permanent disability. Understanding the mechanisms of nerve injury will help the clinician anticipate prognosis and guide treatment. Stretch, transection, and compression of nerves may present similarly, but isolating the mechanism and the extent of injury can guide the treatment modalities and help predict the overall recovery. The case is a report of median nerve compression in a woman after a nondisplaced fracture of the coronoid process of the ulna. Despite the unique nature of the patient’s symptoms, the neuropathy resolved with “watchful waiting.” The location of the injury was a key component in identifying the cause of the neuropathy. It highlights the importance of identifying a cause; some cases will resolve without intervention. Clinicians should consider median nerve compression when presented with a patient experiencing neurologic symptoms following such a fracture.

Background: The current treatment of coronoid process fractures of the ulna is based on the classification system of Regan and Morrey. We found no biomechanical studies that specifically addressed the role of the coronoid process in elbow stability. In the present investigation, the elbows of cadavera were tested before and after fracture of the coronoid process to assess the stabilizing contribution of the coronoid process under axial loading. Methods: Six fresh-frozen cadaveric elbows were tested mechanically. All soft tissue surrounding the elbow, including the skin, was left intact. An axial load compressing the elbow joint was applied along the shaft of the forearm in the sagittal plane. A displacement of fifteen millimeters per minute was applied until a load of 100 newtons was attained. Each elbow was tested in 15, 30, 45, 60, 75, 90, 105, and 120 degrees of flexion. Next, less than 25 percent, 25 to 50 percent, or more than 50 percent of the coronoid process was fractured with an osteotome under radiographic guidance, and the testing was repeated. Each elbow served as its own control, and one elbow was used for two tests; therefore, a total of seven situations were investigated. The difference in displacements between the intact and osteotomized elbows was measured. Results: There was no significant difference, at any flexion position, in posterior axial displacement between the intact elbows and the elbows in which 50 percent or less of the coronoid process was fractured (type I and type II) (p = 0.43). There were significant differences, across all flexion positions, in posterior axial displacement between the intact elbows and the elbows in which more than 50 percent of the coronoid process was fractured (type III) (p = 0.006). Specimens with a type-III fracture also showed a significant increase in displacement compared with specimens with a type-I or type-II fracture (p = 0.012). Specifically, from 60 to 105 degrees of flexion, a significant increase in posterior translation of up to 2.4 millimeters was found (p < 0.05). Conclusions: In response to axial load, elbows with a fracture involving more than 50 percent of the coronoid process displace more readily than elbows with a fracture involving 50 percent or less of the coronoid process, especially when the elbow is flexed 60 degrees and beyond. Clinical Relevance: These data provide biomechanical support for the current treatment of coronoid process fractures and may help to explain why type-III coronoid process fractures often have a poor prognosis.

The purpose of this study was to identify the incidence of abnormal computed tomography (CT) findings in dogs with lameness of one or both elbows. CT examinations of 102 elbows in 51 dogs were reviewed individually and by group consensus by 3 examiners and graded for various abnormalities. Frequently encountered abnormalities included abnormal shape and sclerosis of the medial coronoid process of the ulna, irregularity of the radial incisure of the ulna, and ulnar trochlear notch sclerosis. Other abnormalities included distinct/separate or fissure/in situ fragmentation of the medial coronoid; lucency of the radial incisure; ununited anconeal process; sclerosis, lucency, or flattening of the medial aspect of the humeral condyle; osteophyte formation; and joint incongruity. In conclusion, CT of the canine cubital joint is useful in identification of various lesions beyond simple fragmentation of the medial coronoid process of the ulna.

The authors dissected 72 paired arm to study the anatomy of Gantzer's muscle. The dissection explored course of the median nerve from the elbow to the distal end of the forearm. The following anatomical structures and variations were noted;(1) The presence of a Gantzer's muscle, as well as its relationship to the median and anteriorinterosseous nerves.(2) The origin and insertion of Gantzer's muscle.Results: Gantzer's muscle arose from the medial epicondyle of the humerus in 45 arms (90%), from the coronoid process of the ulna in 3 arms (6%), from the intermuscular fascia in 1 arm (2%), and from a double origin- the medial epicondyle and the coronoid presess-in 1 arm (2%). Insertion was to the proximal part of the tendon of the flexor pollicis longus muscle in all arms.Gantzer's muscle always lies posterior to the median nerve. In 12 out of 50 arms, the muscle passed posterior to the anterior interosseous nerve, and in the remaining 38 arms, the anterior interosseous nerve ran proximal to the muscle along its proximal border and never cross Gantzer's muscle and its tendon.Based on these findings, the authors concluded that Gentzer's muscle rarely contributes to anterior interosseous nerve compression in the proximal forearm.