The adductor magnus "mini-hamstring": MRI appearance and potential pitfalls

Sonographic Appearance of the Ischiocondylar Origin of the Adductor Magnus

The adductor magnus ischiocondylar origin (AM-IO) tendon has often been described as a third proximal hamstring tendon due to its common origin on the ischial tuberosity as well as similar function. Prior studies have described the magnetic resonance imaging characteristics of the AM-IO; however, its appearance on ultrasound has not been well-detailed. The purpose of our study is to describe the sonographic appearance of the AM-IO and provide a structured scanning protocol for complete evaluation of the tendon.

Anatomical Relationships of the Proximal Attachment of the Hamstring Muscles with Neighboring Structures: From Ultrasound, Anatomical and Histological Findings to Clinical Implications

BACKGROUND

Injuries of the proximal attachment of the hamstring muscles are common. The present study aimed to investigate the relationship of the proximal attachment of the hamstring muscles with neighboring structures comprehensively.

METHODS

A total of 97 hemipelvis from 66 cryopreserved specimens were evaluated via ultrasound, anatomical and histological samples.

RESULTS

The proximal attachment of the hamstring muscles presents a hyperechogenic line surrounding the origin of the semimembranosus and the long head of the biceps femoris muscles, as well as another hyperechogenic line covering the sciatic nerve. The anatomical and histological study confirms the ultrasound results and shows different layers forming the sacrotuberous ligament. Furthermore, it shows that the proximal attachment of the semimembranosus muscle has a more proximal origin than the rest of the hamstring muscles. Moreover, this muscle shares fibers with the long head of the biceps femoris muscle and expands to the adductor magnus muscle. The histological analysis also shows the dense connective tissue of the retinaculum covering the long head of the biceps femoris and semimembranosus muscles, as well as the expansion covering the sciatic nerve.

CONCLUSIONS

These anatomical relationships could explain injuries at the origin of the hamstring muscles.

High-resolution ultrasound in the evaluation of the adult hip

This paper reviews ultrasound of the hip, which is a commonly requested examination for symptomatic hip issues. This includes both intra-articular and extra-articular causes of hip pain. Ultrasound is easily accessible, lacks radiation exposure, and allows for evaluation of the contralateral hip as well as assessment of dynamic maneuvers. Ultrasound can be used to guide interventional procedures. Ultrasound of the hip can be challenging due to the deep location of structures and complex anatomy. Typically, high-frequency transducers are used to examine the hip, however the choice of ultrasound transducer depends on the patient's body habitus, with lower frequency transducers required to penetrate deep structures in obese patients. It is important to have an approach to ultrasound of the hip which includes assessment of the anterior, lateral, posterior, and medial aspects of the hip. The technique and relevant anatomy of each of these compartments are discussed as well as the use of Doppler examination of the hip. Several dynamic maneuvers can be performed to help determine the cause of hip pathology in various locations, and these are described and illustrated. Ultrasound is useful for guided procedures about the hip, and these indications will be reviewed.

Isolated Adductor Magnus Injuries in Athletes: A Case Series

Background

Little is known about injuries to the adductor magnus (AM) muscle and how to manage them.

Purpose

To describe the injury mechanisms of the AM and its histoarchitecture, clinical characteristics, and imaging features in elite athletes.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 11 competitive athletes with an AM injury were included in the study. Each case was clinically assessed, and the diagnosis and classification were made by magnetic resonance imaging (MRI) according to the British Athletics Muscle Injury Classification (BAMIC) and mechanism, location, grade, and reinjury (MLG-R) classification. A 1-year follow-up was performed, and return-to-play (RTP) time was recorded.

Results

Different mechanisms of injury were found; most of the athletes (10/11) had flexion and internal rotation of the hip with extension or slight flexion of the knee. Symptoms consisted of pain in the posteromedial (7/11) or medial (4/11) thigh during adduction and flexion of the knee. Clinically, there was a suspicion of an injury to the AM in only 3 athletes. According to MRI, 5 lesions were located in the ischiocondylar portion (3 in the proximal and 2 in the distal myoconnective junction) and 6 in the pubofemoral portion (4 in the distal and 2 in the proximal myoconnective junction). Most of the ischiocondylar lesions were myotendinous (3/5), and most of the pubofemoral lesions were myofascial (5/6). The BAMIC and MLG-R classification coincided in distinguishing injuries of moderate and mild severity. The management was nonoperative in all cases. The mean RTP time was 14 days (range, 0-35 days) and was longer in the ischiocondylar cases than in the pubofemoral cases (21 vs 8 days, respectively). Only 1 recurrence, at <10 months, was recorded.

Conclusion

Posteromedial thigh pain after an eccentric contraction during forced adduction of the thigh from hip internal rotation should raise a suspicion of AM lesions. The identification of the affected portion was possible on MRI. An injury in the ischiocondylar portion entailed a longer RTP time than an injury in the pubofemoral portion.

US and MRI of Pelvic Tendon Anatomy and Pathologic Conditions

The bony pelvis serves as the attachment site for a large number of powerful muscles and tendons that drive lower extremity movement. Organizing the pelvic tendons into groups that share a common function and anatomic location helps the radiologist systematically evaluate these structures for injury, which can be caused by repetitive stress, acute trauma, or failure of degenerated tissues. Tears of the anteromedial adductors around the pubic symphysis and anterior flexors traversing anterior to the hip principally affect younger male athletes. Tears of the lateral abductors and posterior extensors are more common in older individuals with senescent tendinosis. The deep external rotators are protected and rarely injured, although they can be impinged. Imaging of the pelvic tendons relies primarily on US and MRI; both provide high spatial and contrast resolution for soft tissues. US offers affordable point-of-care service and dynamic assessment, while MRI allows simultaneous osseous and articular evaluation and is less operator dependent. While the imaging findings of pelvic tendon injury mirror those at appendicular body sites, radiologists may be less familiar with tendon anatomy and pathologic conditions at the pelvis. The authors review pertinent anatomy and imaging considerations and illustrate common injuries affecting the pelvic tendons. Online supplemental material is available for this article. ^©RSNA, 2022.

Effects of a Groin Pain Prevention Program in Male High School Soccer Players: A Cluster-Randomized Controlled Trial

Background

Groin pain is frequently reported by soccer players. A prevention program incorporating the Copenhagen adduction exercise (CAE) has been shown effective in decreasing adductor muscle injury in semi-professional soccer players. However, the effect of such programs on groin pain in high school soccer players is unknown. No reports have examined the effects of combining the CAE with other targeted exercises such as the Nordic hamstrings exercise (NHE).

Purpose

To evaluate the preventative effects of exercise on groin pain in high school soccer players in three groups comprising NHE alone, combined NHE and CAE, and a control group.

Design

Randomized Controlled Clinical Trial.

Methods

A cluster randomized controlled trial spanning 16 weeks was conducted on 202 high school soccer players from seven high schools in a Japanese under 18 Soccer League. Players were allocated to either group A (three schools, 66 players) receiving the CAE alone, or group B (two schools, 73 players) receiving the CAE and NHE, or control group C (two schools, 63 players) who performed their usual training. This study compared the number of injuries, injury rate, and severity of the injury of groin pain in these three groups.

Results

The number of players injured was less in group B (4 players) compared to C (18 players), and time-lost to soccer was less in groups A (6 players) and B (3 players) compared to group C (16 players). Injury rates were significantly lower in groups A and B, with the relative risk of injury compared to group C of 0.42 (95% CI 0.19% to 0.90%) in group A and 0.19 (95% CI 0.07 to 0.54) in group B.

Conclusion

A 16-week program incorporating the CAE in training sessions in high school soccer players reduced the incidence of groin pain and which may be related to injury severity according to time -lost to soccer, however the combination of both the CAE and NHE may be more effective than the CAE alone.

Level of Evidence

2b.

Risk Factors for Groin Pain in Male High School Soccer Players Undergoing an Injury Prevention Program: A Cluster Randomized Controlled Trial

Little is known about the risk factors for developing groin pain in high school soccer players. Therefore, the purpose of the study is to investigate the risk factors for developing inguinal pain in high school soccer players who are undergoing an injury prevention program. A cluster randomized controlled trial was conducted on 202 high school soccer players. Players were allocated to either group A (3 schools, 66 players) receiving the Copenhagen adduction exercise (CAE) alone, or group B (2 schools, 73 players) receiving the CAE and Nordic hamstrings exercise, or group C, the control group without any intervention (2 schools, 63 players). Hip range of motion (ROM) and strength measures were assessed prior to a groin injury prevention program and used in univariate and multivariate analysis to predict development of groin pain. Logistic regression analysis identified that hip abduction ROM and eccentric adductor strength of the dominant leg were factors in the development of groin pain. Increased abduction ROM and decreased eccentric adductor muscle strength of the dominant leg were risk factors for the development of groin pain.

The Hamstrings: Anatomic and Physiologic Variations and Their Potential Relationships With Injury Risk

The incidence and recurrence of hamstrings injuries are very high in sports, posing elevated performance and financial-related costs. Attempts to identify the risk factors involved in predicting vulnerability to hamstrings injury is important for designing exercise-based programs that aim to mitigate the rate and severity of hamstrings injuries and improve rehabilitation strategies. However, research has shown that non-modifiable risk factors may play a greater role than modifiable risk factors. Recognizing non-modifiable risk factors and understanding their implications will afford the prescription of better suited exercise programs, i.e., that are more respectful of the individual characteristics. In a nutshell, non-modifiable risk factors can still be acted upon, even if indirectly. In this context, an underexplored topic is how intra and inter- individual anatomic and physiologic variations in hamstrings (e.g., muscle bellies, fiber types, tendon length, aponeurosis width, attachment sites, sex- and age-related differences) concur to alter hamstrings injuries risk. Some anatomic and physiologic variations may be modifiable through exercise interventions (e.g., cross-sectional area), while others may not (e.g., supernumerary muscle bellies). This apparent dichotomy may hide a greater complexity, i.e., there may be risk factors that are partially modifiable. Therefore, we explored the available information on the anatomic variations of the hamstrings, providing a deeper insight into the individual risk factors for hamstrings injuries and contributing with better knowledge and potential applications toward a more individualized exercise prescription.

Classifying Ischial Tuberosity Avulsion Fractures by Ossification Stage and Tendon Attachment

BACKGROUND

We propose a new classification system for ischial tuberosity fractures in adolescents that is based on the ossification pattern of the apophysis.

METHODS

We performed a retrospective review of patients who were diagnosed with ischial tuberosity avulsion fractures at a single institution from 2008 to 2018. Skeletal maturity and fracture location, size, and displacement were recorded based on initial injury radiographs. The fractures were classified by location as being lateral (type 1) or complete (type 2). Pelvic computed tomography (CT) review demonstrated 5 stages of ossification. We then reviewed pelvic CT and magnetic resonance imaging scans to assess the tendinous insertions at the ischial tuberosity apophysis. Reliability analysis was performed.

RESULTS

We identified 45 ischial tuberosity fractures. The mean patient age was 14.4 years (range, 10.3 to 18.0 years). Boys accounted for 82% of the cohort. Forty-seven percent of the fractures were classified as type 1, and 53% were classified as type 2. Type-1 fractures were associated with younger age (p = 0.001), lower Risser score (p = 0.002), lower modified Oxford score (p = 0.002), less displacement (p = 0.001), and smaller size (p < 0.001) when compared with type-2 fractures. Of the 45 patients, 18 had follow-up of >6 months, with 56% going on to nonunion. Nonunion was associated with greater displacement (p = 0.016) and size (p = 0.027). When comparing union rates by fracture type, 33% of type-1 fractures progressed to nonunion, while 78% percent of type-2 fractures progressed to nonunion; however, this difference was not significant (p = 0.153). A review of the advanced imaging indicated that type-1 fractures involved the semimembranosus and conjoined tendons, whereas type-2 fractures also involved the adductor magnus tendon.

CONCLUSIONS

We propose a new classification system based on the ossification pattern of the ischial tuberosity apophysis that reflects the skeletal maturity of the patient, the size and location of the fracture, and the amount of displacement, and likely predicts the probability of subsequent nonunion. The ischial tuberosity ossifies in a pattern similar to the iliac crest as described by Risser, and this pattern of ossification dictates the size of the ischial tuberosity avulsion fracture fragments and the involved tendons.

Ultrasound Features of the Proximal Hamstring Muscle-Tendon-Bone Unit

The hamstring muscle complex is made by a group of posterior biarticular thigh muscles, originating at the ischial tuberosity, which extend the hip and flex the knee joint. Proximal hamstring injuries are frequent among athletes, commonly involving their long myotendinous junction during an eccentric contraction. In this pictorial essay, we describe the ultrasound technique to visualize the normal anatomy of the proximal hamstring muscle-tendon-bone complex and present ultrasound findings in patients with traumatic injuries and tendinopathies.

Open Repair of Acute Proximal Adductor Magnus Avulsion

Hip adduction is accomplished through coordinated effort of the adductor magnus, brevis, and longus and the obturator externus and pectineus muscles. Each of these muscles may be injured at its proximal or distal insertion or in its midsubstance. The incidence of injuries to the adductor complex is difficult to determine in sport because of players' underreporting and playing through minor strains. The most commonly injured adductor muscle is the adductor longus muscle. The injury most frequently occurs at the proximal or distal musculotendinous junction, but several case reports of origin and insertional ruptures of the adductor longus exist in the literature. Successful outcomes have been obtained with both operative and nonoperative approaches in these cases. Reports of isolated proximal avulsion of the adductor magnus are less common. This article describes our surgical technique for management of a rare acute proximal adductor magnus avulsion.

Hip position and sex differences in motor unit firing patterns of the vastus medialis and vastus medialis oblique in healthy individuals

Weakness of the vastus medialis oblique (VMO) has been proposed to explain the high prevalence of knee pain in female subjects. Clinicians commonly use exercises in an attempt to preferentially activate the VMO. Recently, our group found evidence to support clinical theory that the VMO is neurologically distinct from the vastus medialis (VM). However, the ability to voluntarily activate these muscle subsections is still disputed. The aim of this study was to determine if VM and VMO activation varies between sexes and if control of the two muscles is different between rehabilitation exercises. Thirteen men and 13 women performed isometric straight leg raises in two hip positions, neutral hip rotation and 30 degrees lateral hip rotation. Bipolar intramuscular fine-wire electrodes were inserted into the VM and VMO to obtain motor unit recruitment thresholds and initial firing rates at recruitment. Linear mixed models and Tukey post hoc tests were used to assess significant differences in 654 motor units. Women demonstrated faster motor unit firing rate at recruitment, 1.18 ± 0.56 Hz higher than men. Motor units fired 0.47 ± 0.19 Hz faster during neutral hip rotation compared with lateral hip rotation. The VMO motor units were recruited 2.92 ± 1.28% earlier than the VM. All motor units were recruited 3.74 ± 1.27% earlier during neutral hip rotation than lateral hip rotation. Thus the VM and the VMO can be activated differentially, and their motor unit recruitment properties are affected by sex and hip position.

NEW & NOTEWORTHY This is the first study to reveal differential activation of the vastus medialis oblique from the vastus medialis in clinical exercise protocols. Our research group used fine-wire electrodes to examine EMG signals of the vastus medialis oblique and vastus medialis to avoid possible cross talk. We also consider the effect of sex on motor unit firing patterns because of higher prevalence of knee pain in women, and yet few studies evaluating the sex differences in neuromuscular control.

Characteristics of acute groin injuries in the adductor muscles: A detailed MRI study in athletes

Acute adductor injuries account for the majority of acute groin injuries; however, little is known about specific injury characteristics, which could be important for the understanding of etiology and management of these injuries. The study aim was to describe acute adductor injuries in athletes using magnetic resonance imaging (MRI). Male athletes with acute groin pain and an MRI confirmed acute adductor muscle injury were prospectively included. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. 156 athletes presented with acute groin pain of which 71 athletes were included, median age 27 years (range 18-37). There were 46 isolated muscle injuries and 25 athletes with multiple adductor injuries. In total, 111 acute adductor muscle injuries were recorded; 62 adductor longus, 18 adductor brevis, 17 pectineus, 9 obturator externus, 4 gracilis, and 1 adductor magnus injury. Adductor longus injuries occurred at three main injury locations; proximal insertion (26%), intramuscular musculo-tendinous junction (MTJ) of the proximal tendon (26%) and the MTJ of the distal tendon (37%). Intramuscular tendon injury was seen in one case. At the proximal insertion, 12 of 16 injuries were complete avulsions. This study shows that acute adductor injuries generally occur in isolation from other muscle groups. Adductor longus is the most frequently injured muscle in isolation and in combination with other adductor muscle injuries. Three characteristic adductor longus injury locations were observed on MRI, with avulsion injuries accounting for three-quarters of injuries at the proximal insertion, and intramuscular tendon injury was uncommon.

[Chronic sports injuries of the knee joint]

Chronic sports injuries of the knee joint are common and mainly caused by repetitive (micro) trauma and exertion. Chronic insertion tendinopathies and avulsion fractures and symptoms related to entrapment, friction and impingement can be pathophysiologically distinguished in athletes. In this review, we depict the characteristic magnetic resonance imaging (MRI) findings of the most commonly occurring pathologies.

Anatomy of the Adductor Magnus Origin: Implications for Proximal Hamstring Injuries

Background:

The adductor magnus (AM) has historically been a potential source of confusion in patients with suspected proximal hamstring avulsion injuries.

Purpose:

To investigate the anatomic characteristics of the AM, including its osseous origin, anatomic dimensions, and relationship to the proximal hamstring tendons.

Study Design:

Descriptive laboratory study.

Methods:

Dissection of the AM origin was performed in 11 (8 cadavers) fresh-frozen hip-to-foot cadaveric hemipelvis specimens. The gross anatomy and architecture of the proximal hamstring and AM tendons were studied. After dissecting the hamstring tendons away from their origin, the dimension, shape, and orientation of the tendon footprints on the ischial tuberosity were determined.

Results:

The AM was identified in all cadaveric specimens. The mean tendon thickness (anterior to posterior [AP]) was 5.7 ± 2.9 mm. The mean tendon width (medial to lateral [ML]) was 7.1 ± 2.2 mm. The mean tendon length was 13.1 ± 8.7 cm. The mean footprint height (AP dimension) was 12.1 ± 2.9 mm, and mean footprint width (ML dimension) was 17.3 ± 7.1 mm. The mean distance between the AM footprint and the most medial aspect of the conjoint tendon footprint was 8.5 ± 4.2 mm. Tendon measurements demonstrated a considerable degree of both intra- and interspecimen variability.

Conclusion:

The AM tendon is consistently present just medial to the conjoint tendon at the ischial tuberosity, representing the lateral-most portion of the AM muscle. This study found wide variation in the dimensional characteristics of the AM tendon between specimens. Its shape and location can mimic the appearance of an intact hamstring (conjoint or semimembranosus) tendon intraoperatively or on diagnostic imaging, potentially misleading surgeons and radiologists. Therefore, detailed knowledge of the AM tendon anatomy, footprint anatomy, and its relationship to the hamstring muscle complex is paramount when planning surgical approach and technique.

Clinical Relevance:

The reported data may aid surgeons in more accurate recognition, diagnosis, and repair of proximal hamstring avulsion injuries.

Society of Skeletal Radiology 2015 annual meeting summary

Peer-reviewed abstracts presented at the 2015 Society of Skeletal Radiology (SSR) 38th Annual Meeting were reviewed following oral presentation. Topics felt to be of potential interest to musculoskeletal (MSK) investigators and practicing clinicians are highlighted in this compilation and analysis of the meeting. New concepts regarding MSK imaging and intervention, MSK protocols and techniques, and quality improvement are included. ePoster highlights are also presented.