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Internet Book of Musculoskeletal Ultrasound » Hip: Normal And Pathology​

Hip: Normal And Pathology​

Authors

Craig Rudy, MD

Attending Emergency Physician

Samaritan Health Services – Albany General Hospital

Jordan Wackett, MD, MPH

Chief Resident, Emergency Medicine Residency

Oregon Health and Science University

Summary

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Introduction

  • Hip pain is a common experience for both pediatric and adult patients.  While there are many chronic causes of hip pain there are acute causes of pain that can be diagnostically challenging for the ED clinician.  
  • X-ray is a frequently used imaging modality that infrequently provides diagnostic help when fracture or dislocation is absent. MRI is an expensive and time consuming test that will occasionally require radiologist assistance to inject intra-articular contrast.  
  • Point-of-care ultrasound is readily available, can visualize soft tissue, and has the potential to help speed diagnostic evaluation. [1]Thom C, Ahmed A, Kongkatong M, Moak J. Point-of-care hip ultrasound leads to expedited results in emergency department patients with suspected septic arthritis. J Am Coll Emerg Physicians Open. … Continue reading[2]Vieira RL, Levy JA. Bedside ultrasonography to identify hip effusions in pediatric patients. Ann Emerg Med. 2010;55(3):284-289.[3]Cruz CI, Vieira RL, Mannix RC, Monuteaux MC, Levy JA. Point-of-care hip ultrasound in a pediatric emergency department. Am J Emerg Med. 2018;36(7):1174-1177.
  • Pediatric patients with an acute limp or “irritable hip” are a common presentation to the ED and present a diagnostic challenge for the ED clinician.  ED physician point-of-care ultrasound is a radiation-sparing imaging modality that can be reliably performed by ED clinicians.1
  • This chapter will review the basics of musculoskeletal ultrasound of the hip broken down by anatomic region.  Relevant anatomy and pathology will be described along with pictorial demonstrations.

Ultrasound Transducer and Settings

Patient seated with optimal physician positioning
Patient in neutral position.
  • Ultrasonography of the hip can be completed using either the high frequency (10 Mhz or greater) linear probe or the curvilinear probe (typically lower frequency on most standard ultrasound machines).  The choice of the probe is dependent on the body habitus of the patient and the depth of structure being interrogated.4  However, most pediatric patients with a normal BMI may be evaluated with a high frequency linear probe.  If there is uncertainty as to the most appropriate probe, it is reasonable to use a higher frequency probe initially.  If the image quality is insufficient then it is reasonable to change probes at that time.  
  • When evaluating the anterior hip the patient should be lying supine with the hip in a neutral position with the toes facing towards the ceiling.4
  • The lateral hip should be evaluated with the patient in the lateral decubitus position with the unaffected hip lying on the bed.4  
  • The medial hip should be evaluated with the patient in a “frog-leg” position.  This is a position where the hip is maximally externally rotated and in 45 degrees of abduction.  Evaluation of the medial hip is typically performed with a high-frequency linear probe due to the superficial location of the structures of interest.4  
  • The posterior hip is evaluated with the patient in the prone position, typically with the foot dangling from the bed.  Due to the prominence of the gluteus maximus, the posterior hip is typically evaluated with the lower frequency curvilinear probe.4  
  • While performing the ultrasound study, care should be taken to maintain patient privacy. Given the sensitive nature of the anatomic regions involved, use a sheet or blanket to drape the genitals and contralateral leg.

Anatomy

  • The hip joint is a ball and socket joint composed of the bony articulation of the femoral head with the acetabulum and the surrounding supportive structures.  The femoral head tapers to become the femoral neck which runs perpendicular to the anatomic plane of the femoral shaft.  At the junction of the femoral neck and femoral shaft is the intertrochanteric crest.  This is a raised line that spans the distance between the greater and lesser trochanter that appears at the junction of the femoral neck and shaft.  The intertrochanteric crest serves as the insertion site for the joint capsule.4,5
  • The acetabulum occupies greater than one hemisphere of the femoral head creating some bony limits to range of motion.  However this creates an inherently more stable joint when compared to the glenohumeral joint, the other major ball and socket joint.5  These bony structures along with surrounding ligaments provide much of the stability of the hip joint with little contribution from the surrounding musculature. 
  • The surrounding muscles for the hip, by quadrant include: (anterior) quadriceps femoris and iliopsoas, (lateral) sartorius and tensor fasciae latae, (posterior) gluteal and hamstrings group, (medial) adductor muscle group, pectineus, and the deep external rotator muscle group.  [NEED IMAGE – ANATOMY]
  • The medial aspect of the anterior hip contains the femoral neurovascular bundle.  The femoral vein is the most medial of the structures with the femoral artery laterally adjacent.  The femoral nerve is the most lateral structure and lies superior to the iliopsoas muscle.5  
  • In the posterior hip lies the sciatic nerve which exits via the sciatic foramen.  The most typical course is for the nerve to move superficially just below the inferior edge of the piriformis muscle however there are multiple anatomic variants in this region.5  
  •  
Biceps Brachii anatomy including the long and short tendons.
Illustration of the bicipital groove with the long head of the biceps tendon. The subscapularis is also visualized.[4]van Deurzen, Derek FP, et al. “Clinical relevance of the anatomy of the long head bicipital groove, an evidence‐based review.” Clinical Anatomy 34.2 (2021): 199-208.

Normal Ultrasound Anatomy

The sonographic evaluation of the hip can be divided into four sections, the anterior, posterior, lateral, and medial regions of the hip.  Each region is composed of distinct anatomic structures and pathology.  The complete diagnostic sonographic evaluation of the hip would include assessment of all four regions.  However, this frequently is unnecessary therefore it is recommended to proceed with a targeted ultrasonographic assessment of the region of interest based on the initial history and physical exam.  As a general rule, all structures should be scanned in both longitudinal and short axes to evaluate for pathology.

Anterior Hip

The major structures evaluated in the anterior hip are:

  • Anterior joint recess
  • Iliopsoas tendon
  • Rectus femoris
  • Sartorius
  • Tensor fascia lata
  • Femoral neurovascular bundle

[IMAGE NEEDED, ANATOMY, ANTERIOR HIP]

[IMAGE NEEDED, DRAWING, PATIENT POSITION, PROBE]

Technique

The patient is scanned supine with the leg in the neutral position.  Scanning is done using a high-frequency linear probe however patients with a larger body habitus may require a lower frequency probe (typically the curvilinear).6 Begin by placing the probe in the long-axis of the femoral neck near the inguinal crease. The probe should initially be aimed with the indicator towards the umbilicus in order to match the anatomic plane of the femoral neck.  Subsequent subtle adjustments may be necessary to ensure proper alignment in the long-axis. If there is uncertainty on whether you are correctly viewing the joint, slight internal and external rotation of the hip will help clarify the location of the moving femoral head within the static acetabulum. The first structures identified are the acetabulum and femoral neck and this should serve as the “home base”. In this view, the anterior joint capsule is identified and it can be seen extending caudad towards the intertrochanteric crest [NEED IMAGE].  This is the location where a joint effusion would be visualized and an arthrocentesis performed. Using a short-axis slide in the medial and lateral directions the remainder of the region should be evaluated. Superficial to the joint capsule is the iliopsoas muscle. [NEED IMAGE]

Moving the probe into the true short axis, the neurovascular bundle containing the femoral vein, artery, and the nerve is visualized medial and superficial to the joint space. Just lateral and superficial to the neurovascular bundle is the sartorius muscle. Moving laterally is the tensor fascia lata (TFL), which originates from the anterior superior iliac spine with the sartorius. Just deep to sartorius and TFL muscles is the rectus femoris which originates from the anterior inferior iliac spine. [NEED IMAGE].

Lateral Hip

The lateral hip structures of interest include:

  • Gluteal muscles and tendons
  • Greater trochanter and trochanteric bursa

[IMAGE NEEDED, ANATOMY LATERAL HIP] 

[IMAGE NEEDED, DRAWING, PATIENT POSITION, PROBE]

Technique

Start with the patient in the lateral decubitus position lying on the unaffected hip. Begin using the high-frequency linear probe and switch to the lower frequency curvilinear probe when needed for patients with a larger habitus or deeper structures. [IMAGE NEEDED, POSITIONING OF PROBE AND PATIENT]

Identify the greater trochanter of the femur and its anterior and lateral facets by placing the probe in a longitudinal axis over the greater trochanter. This is your major landmark. The gluteal muscle group is formed by the minimus, medius, and maximus muscles. Minimus lies deepest of the muscles and the tendon inserts onto the anterior facet of the greater trochanter. Medius lies superficial to minimus and its thin portion inserts onto the lateral facet.  The lateral facet appears posterior to the anterior facet in the short axis view [NEED IMAGE]. Maximus lies most superficial and overlies the posterior portion of medius. The subgluteus maximus bursa (also known as the trochanteric bursa) lies between the maximus and medius muscle bellies.4,6 [NEED IMAGE]

Video of trochanteric bursae: https://www.youtube.com/watch?v=q7GNTxx4qN0

Medial Hip

[IMAGE NEEDED, ANATOMY OF MEDIAL HIP]

[IMAGE NEEDED, PATIENT POSITIONING AND PROBE]

The medial thigh contains the insertion of the adductor muscle group onto the pubic tubercle.  While this is a site of chronic pain and injury, this is rarely a location of emergent complaints and therefore the focus of this chapter will not be on the medial thigh.  If the tendon structures of the medial thigh are going to be evaluated it is recommended that the patient be placed in the frog-leg position4.  Using a linear high frequency probe the probe will be placed on the pubic tubercle oriented along the course of the adductor muscle group.  In patients with minimal adiposity in this region extra ultrasound gel may be useful due to the prominence of the adductor tendons rising above the surrounding tissue making for an uneven surface for the probe.  The tendons can initially be evaluated in the long-axis. [Image here]  The adductor tendons have a short tendon length along with a grouped tendon insertion.  From superior to inferior the tendons will be arranged as follows: adductor longus, adductor brevis, and adductor magnus.4,7  Once the tendons have been evaluated in the long-axis they should be evaluated in the short-axis. [NEED IMAGE]

Posterior Hip

The structures of interest are:

  • Hamstring tendons
  • Sciatic nerve

[IMAGE NEEDED, ANATOMY OF POSTERIOR HIP]

[IMAGE NEEDED, DRAWING, PATIENT POSITION, PROBE]

Move the patient into a prone position with their feet hanging off the end of the exam table to evaluate the posterior hip. Place the probe in the short axis over the ischial tuberosity. The hamstring muscle group originates from the ischium.  The gluteus maximus can obscure visualization therefore the probe can be placed just inferior to the gluteal fold overlying the ischial tuberosity.  Due to the prominence of the gluteal tissue, it can be helpful to use pressure to compress some of the tissue to improve visualization.  This will give the overlying gluteus maximus muscle tissue a relatively hyperechoic appearance.  The hamstrings are formed by the semimembranosus, semitendinosus, and long head of the biceps femoris muscles. They’re best evaluated initially by visualizing the ischium in the short axis.[IMAGE NEEDED, US ISCHIUM SHORT AXIS] Immediately lateral to the ischium, a pair of closely associated tendons making up the proximal hamstring tendon bundle are the semimembranosus tendon (inferolateral) and conjoint tendon (superomedial).4,7 [Image here] Continuing distally, the conjoint tendon divides into the semitendinosus tendon and the more superolateral tendon of the long head of biceps femoris.  Meanwhile, moving distally the semimembranosus tendon dives underneath the conjoint tendon and medial to the conjoint tendon traveling in an oblique direction.  Turning the probe 90 degrees on the ischial tuberosity, both tendons may be visualized in a stacked fashion extending distally away from the ischial tuberosity with the conjoint tendon superior and the semimembranosus tendon inferior. [NEED IMAGE] It can be challenging to view both tendons simultaneously due to the oblique travel of the semimembranosus tendon and therefore each may need to be evaluated separately.  Each tendon can be evaluated distally to their respective muscle bellies. Care should be taken to evaluate all structures here in longitudinal and short axes.

Gluteus maximus muscle lies superior to the origin of the hamstrings. Lateral to the proximal hamstring tendon bundle is the large sciatic nerve with its typical fibrillar appearance in the short axis. The sciatic nerve in the short-axis view, containing the ischial tuberosity and hamstring tendon bundle, will be overlying the quadratus femoris muscle. [NEED IMAGE] The sciatic nerve typically lies superior to the deep external rotator muscles of the hip except for the piriformis (it runs deep to this muscle most commonly).  The anatomy of the deep external rotators will not be covered in this chapter due to lack of common emergent complaints among this group of muscles. 

Illustration of the supraspinatus and infraspinatus.[5]Image courtesy of https://www.sportsinjuryclinic.net/, “Supraspinatus Tear”
Modified-Crass Position (A). Corresponding ultrasound image (B) and schematic drawing (C) show the supraspinatus tendon (SSP) in the long axis with focal thickening of the subacromial bursa (asterisk). Neutral Position (D). Corresponding ultrasound image (E) and schematic drawing (F) show the swollen SSP in the long axis. HH, humeral head; Acr: acromion[6]Ricci, Vincenzo, and Levent Özçakar. “The Dodo Bird Is Not Extinct: Ultrasound Imaging for Supraspinatus Tendinosis.” American Journal of Physical Medicine & Rehabilitation 98.1 … Continue reading
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  •  
Overview of the glenoid fossa and related structures. Lateral view of a right glenoid fossa of the scapula showing the articular cartilage in the middle of the glenoid fossa surrounded by the glenoid labrum on its rim. The subscapular bursa is located anterior to the tendon of the long head of biceps brachii (LHB), in close proximity to the superior glenohumeral ligament (SGHL) and middle glenohumeral ligament (MGHL). The inferior glenohumeral ligament can be found inferiorly, highlighting its different segments: the anterior band (A-IGHL), axillary pouch, and the posterior band (P-IGHL).[7]Dekker, T.J., Aman, Z.S., Peebles, L.A., Storaci, H.W., Chahla, J., Millett, P.J. et al. (2020) Quantitative and qualitative analyses of the glenohumeral ligaments: an anatomic study. American … Continue reading
    • Sliding the transducer medially is necessary to identify the spinoglenoid notch, which is a potential site for a paralabral cyst. The transducer is then moved inferiorly to visualize the teres minor, and then rotated 90 degrees to visualize the tendons in short-axis.

Pathology

Tenosynovitis long head of biceps tendon in short axis.[8]Image courtesy of ultrasoundcases.info, “Long head of the biceps tenosynovitis”
Posterior view of the glenohumeral joint showing both normal and a joint effusion.[9]Image courtesy of acepnow.com, “Ultrasound-Guided Glenohumeral Joint Evaluation and Aspiration”

Point-of-care ultrasound of the hip joint has the ability to help the emergency physician narrow their differential diagnosis.  Complete diagnostic ultrasound of the hip is frequently unnecessary in the ED. Instead using the history and physical exam can help the emergency physician hone in on a specific area of interest. 

Hip Joint Effusion

  • Emergency physicians can use point-of-care ultrasound to identify a hip effusion in both pediatric and adult patients3.  A retrospective review of pediatric emergency department physicians could perform a hip ultrasound and identify a hip ultrasound with 90% accuracy after a total of 10 ultrasound studies.1  Ultrasound was overall 85% sensitive for effusion and 98% specific.1
  • The diagnosis of a hip effusion is made by placing the ultrasound probe over the anterior hip over the inguinal ligament and with the probe indicator oriented towards the umbilicus.  The inferior reflection of the joint capsule extends beyond the femoral neck to the metaphysis and typically has a small amount of fluid present.  The thickness of the anechoic fluid can be measured in this plane using the shortest path between the femoral neck and the anterior aspect of the joint capsule.  Typical definitions of normal thickness of the joint capsule is 5mm however some studies have allowed up to 7.5mm.8  Physiologic fluid within the joint capsule should be less than 2 mm excluding the thickness of the joint capsule.4  Additionally, using the patient as their own control, a 2 mm or greater side-to-side difference is also diagnostic of an effusion.8  Qualitatively, the shape of the joint capsule in the absence of an effusion can be described as concave.  In patients with an effusion the joint capsule will start to take on a convex appearance with the apex of the joint capsule appearing at the femoral neck or just inferiorly.9 [NEED IMAGE- NORMAL AND EFFUSION]
  • The differential for a patient with a hip effusion includes: Septic arthritis, transient synovitis, osteoarthritis, crystalline arthropathy, seronegative and seropositive arthritis, lyme disease.  Ultrasound alone is insufficient to diagnose the contents of the intra-articular space however some of the ultrasonographic features may be suggestive of one process more than another.  
    • Septic joint – The effusion may have heterogeneous material within the joint.  There is also typically synovial thickening.  Late findings may also demonstrate cartilaginous changes due to local destruction from purulent material.  Unfortunately, these findings may also be found in non-septic hips on rare occasions and therefore should be not taken to be specific to the septic hip.10  In most cases infection is ruled-out when an effusion is not present.8 However, there are case reports in patients with a high pretest probability of having an occult septic hip.11 The authors of this chapter advocate that in patients with a sufficiently low pretest probability a septic hip can be ruled-out if an effusion is not present.  Hopefully future prospective studies will incorporate a pretest probability in addition to hip ultrasound for the complete evaluation of the septic hip.   Point-of-care ultrasound has also been shown to improve time to diagnosis of septic hip when compared with radiology performed ultrasound studies.2  Previous evidence has suggested that purulent material can lead to permanent cartilage damage as soon as six hours.12  [NEED IMAGE] 
    • Transient synovitis – Most commonly seen in pediatric patients between the ages of 3-810.  Given the relative size of the patient a high frequency linear probe may provide better diagnostic visualization.  The effusion of transient synovitis typically remains anechoic and homogenous.  The synovium will be thickened in appearance.10  Bilateral transient synovitis may be present in up to 5% of cases and therefore side-to-side comparisons may show similarly distended joint capsules.9 [NEED IMAGE]
    • Osteoarthritis – The fluid of osteoarthritis is typically homogenous and anechoic.  However there may be heterogeneous material or loose bodies in the fluid from prior degenerative cartilage or labral tears.4,10  The synovium will appear thickened and may have some diverticula.  The shape of the femoral head may also show osteophytic changes and the acetabular rim may appear to extend as osteophytes appear.  The osteophytes, made of bone, will have a similar hyperechoic appearance with posterior shadowing however they will have a much more irregular shape or pattern than the typical linear appearance of long bone cortex.  Osteoarthritis is a diagnosis of exclusion for hip effusion.  [NEED IMAGE]
    • Crystalline arthropathy – A joint effusion may be present and difficult to differentiate from other types of effusion.  In the case of chondrocalcinosis, the anterior reflection of the labrum may multiple contain hyperechoic submillimeter foci.4  In some cases of crystal deposition the articular cartilage may have the appearance of “icing” due to numerous small hyperechoic foci collecting along the cartilage. [NEED IMAGE]
Hypertrophy and thickening of the biceps tendon in the bicipital groove.[10]Image courtesy of https://www.ultrasoundcases.info/, “Biceps tendon tendinopathy / tendinosis”
Sonography of bilateral shoulders. (A and B) Transverse view, (C and D) longitudinal view. Red arrow shows absence of biceps tendon within the right bicipital groove (A and C), white arrow shows normal biceps tendon within the left bicipital groove (B and D).[11]Lim, Chong Hong, Kok An Lee, and Joe Wei Liew. “Popeye’s sign: biceps tendon rupture.” BMJ Case Rep 13.2 (2020): e234205.

Osteomyelitis

  • Ultrasound is limited as a diagnostic tool for osteomyelitis and is optimally made through alternative imaging modalities.13,14  If osteomyelitis is able to be seen by ultrasound the probe should be localized over the bony area of interest. Probe selection should be driven by the age and body habitus of the patient with higher frequency probes used when there is minimal soft tissue between the probe and the bone.  Ultrasonographic findings including periosteal edema and thickening.  Superficial to the periosteum there may also be small regions of edema.  Although a joint effusion may be present concurrently with osteomyelitis the absence of effusion is insufficient to rule-out osteomyelitis. In cases of direct inoculation the tract may be visualized with signs of infection tracking parallel to the tract.  [NEED IMAGE]

Bursitis

  • The most commonly diagnosed bursitis in the hip is greater trochanteric bursitis, now commonly referred to as greater trochanteric pain syndrome due to its more common chronic presentation.  A few pathologic tissue changes are grouped together into the broader clinical entity of greater trochanteric bursitis.  Visualization of the region of interest is most easily accomplished by placing the probe over the lateral hip with the patient in the lateral decubitus position.  With the probe oriented in the axial plane the ridge combining the anterior and lateral facet of the greater trochanter will act as the central point of focus.4  The choice between a high frequency linear probe and a lower frequency curvilinear probe is dependent on the patient’s body habitus.  The most common pathologic change is tendinopathy of the gluteus medius and minimus tendons.  Tendinopathy will show thickened hypoechoic tendons with a much more heterogeneous appearing structure than the typical fibrillar structure of healthy tendon.  Occasionally, calcific changes of the tendon may be present [Jacobsen].  This will appear as a hyperechoic structure (usually round) with posterior acoustic shadowing within the tendon unit.  If bursitis is present, it will most commonly be present in the bursa immediately superior to the insertion of the gluteus medius tendon.  This will appear as a layer of anechoic fluid.  The surrounding synovium of the bursa may have some concurrent thickening.  It is important to avoid excess compression as this may displace fluid within the space.  Assessing the anechoic fluid to ensure that it is within the synovium is important.  Fluid that contains heterogeneous components or appears to extend beyond the synovium would suggest an alternative diagnosis such as a tendon tear, hematoma, or infectious process.10  [NEED IMAGE]

Slipped Capital Femoral Epiphysis

    • Slipped capital femoral epiphysis (SCFE) is an important diagnostic consideration in the child with hip or knee pain.  Classically, the first line imaging modality is x-ray.  However, in the course of work-up a point-of-care ultrasound may be concurrently performed. The sonographic evaluation typically starts with anterior hip ultrasound and in cases of high concern further images may be obtained from the lateral or posterior views. In the acute phase of SCFE will show a physeal “step” where the femoral head will appear to have slipped posteriorly off of the physis.15  A concurrent effusion may also be present.  Chronic slips can be challenging due to remodeling at the physis and progressive closure of the physis.10  In diagnostically uncertain cases it is reasonable to compare to the contralateral side.  There is insufficient evidence to recommend ultrasound as a diagnostic modality to replace x-ray at this time.  [NEED IMAGE]
    •  
Medial dislocation of long head biceps tendon is seen from bicipital groove. Biceps tendon is intact.[12]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 10973
Short axis view of the supraspinatus tendon demonstrating cortical changes and hypoechoic articular surface defect.[13]https://theultrasoundsite.co.uk/, “Partial thickness rotator cuff tear: A summary”
Supraspinatus tendon in short axis. There is a fluid filled defect replacing the entire full thickness and entire width of the right supraspinatus suggesting a tear. The defect length or retraction is 30 mm.[14]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 17937

Tendon Pathology

Calcific deposits are seen in both supraspinatus and infraspinatus tendons. [15]Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 7501
Acute subacromial-subdeltoid bursitis: fluid distending the bursa more than 1.5 mm. The tendon fibers are poorly characterized due to anisotropy.[16]Case courtesy of Bruno Di Muzio, Radiopaedia.org, rID: 22396

Diabetic Muscle Infarction

Ultrasonographic evaluation should be targeted to the area of maximal pain.  This disease is most common in the thigh and lower leg.4,21  An extensive field examination of the area should be performed with orthogonal views obtained.  The characteristic changes will include loss of typical striations within the muscle tissue.  This will appear as hypoechoic muscle tissue relative to surrounding muscle.  In some cases, some muscle fiber architecture may still be intact.4  There will frequently be secondary hypo or anechoic edema near the affected area.4,21 Comparison may be made to unaffected muscles, particularly focusing on the unaffected extremity. The cause is unknown however it may be a signal of end-stage organ disease secondary to diabetes.4,21  [NEED IMAGE]

Fracture

Ultrasound findings of fractures are further discussed in Chapter [LINK TO FRACTURE CHAPTER].

DVT

  • Ultrasound findings of DVT are further discussed in chapter [Link to DVT chapter]

Morel-Lavallée

Ultrasound findings of Morel-Lavallée are further discussed in chapter [Link to Morel-Lavallée chapter]

Soft Tissue Hematoma

Ultrasound findings of soft tissue hematoma are further discussed in chapter [Link to hematoma chapter]

Axial section of the normally concave rotator interval showing conspicuous coracohumeral ligament thickening (red double arrow) with a rounded and convex profile (yellow dotted arrows). LHBT long head of the biceps tendon[17]Stella, Salvatore Massimo, et al. “Ultrasound features of adhesive capsulitis.” Rheumatology and therapy 9.2 (2022): 481-495.
Lesions of the posterior glenoid labrum: A. an irregular, decreased in size labrum (arrows); B. a labrum avulsed and displaced onto the glenoid (arrows); H – head of the humerus, moved backwards in relation to the glenoid (B), ISP – the infraspinatus muscle; joint fluid (*)[18]Krzyżanowski, Wojciech, and Marta Tarczyńska. “The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part II: examples of labral pathologies.” Journal … Continue reading
A well-defined cyst is noted deep to infraspinatus. It abuts the posterior aspect of glenohumeral joint.[19]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 12963
  • Posterior Glenoid Labrum and Paralabral Cyst
    • The posterior glenoid labrum can be visualized as a hyperechoic triangular structure lateral to glenoid. A well-defined hypoechoic or anechoic cleft may indicate a labral tear.
    • It is important to scan medially along the scapular spine to evaluate for parameniscal cysts, particularly at the spinoglenoid notch and suprascapular notch. Parameniscal cysts can compress the suprascapular nerve cause denervation and atrophy of the infraspinatus muscle when located in the spinoglenoid notch, or of both the infraspinatus and supraspinatus when located in the suprascapular notch. This may demonstrate denervation changes such as muscle atrophy and hyperechogenicity.
Video of an anterior shoulder dislocation. The probe is on the posterior shoulder and you can see the humeral head is not articulating with the glenoid cavity. Hemearthrosis is present with a distended capsule.
Confirmation of reduction with the probe on the posterior shoulder. Internal and external rotation of the joint demonstrate appropriate glenohumeral articulation.
  • Shoulder Dislocation
    • Evaluation of the posterior glenohumeral joint can provide rapid assessment for shoulder location. This simple evaluation has high sensitivity and specificity and may allow for rapid confirmation of suspected anterior shoulder dislocations.[20]Boswell B, Farrow R, Rosselli M, et al. Emergency Medicine Resident-Driven Point of Care Ultrasound for Suspected Shoulder Dislocation. South Med J. 2019;112(12):605-609. … Continue reading[21]Pescatore R, Nyce A. Managing Shoulder Injuries in the Emergency Department: Fracture, Dislocation, and Overuse. Emerg Med Pract. 2018;20(6):1-28.
    • Glenohumeral separation distance measures the anterior-posterior displacement of the most posterior aspects of the glenoid fossa and head of humerus, when image obtained from posterior glenohumeral approach. A glenohumeral separation distance >0cm (glenoid measured posterior to humeral head) has a high sensitivity for anterior dislocations.[22]Lahham S, Becker B, Chiem A, et al. Pilot study to determine accuracy of posterior approach ultrasound for shoulder dislocation by novice sonographers. West J Emerg Med. 2016;17(3):377-382. … Continue reading
    • Point-of-care ultrasound can also be useful in suspected posterior dislocations. This injury is easily missed on anterior-posterior radiographs, and axillary views can be difficult to obtain due to pain and difficulty with abduction. Thus, ultrasound is a useful tool in further evaluation when clinical suspicion is high.[23]Henneberry R, Dahn T, Atkinson P. Just the Facts: Point-of-care ultrasound in the management of shoulder dislocations. Can J Emerg Med. 2020;22(3):287-290. doi:10.1017/cem.2020.14
  • Clavicle Fracture
    • To assess for clavicle fracture with ultrasound, one scans along the length of the clavicle to evaluate for a cortical step-off. This is particularly useful in pediatric evaluations to decrease radiation exposure in diagnostic evaluation.
Long axis ultrasound of the distal 1/3 of the clavicle shows a cortical irregularity with surrounding swelling and fluid (blood).
Abrupt discontinuity of the right bony cortex between the greater tubercle and the rest of the right humerus. Subtle fluid adjacent to the fracture, compared with the left side.[24]Case courtesy of Maulik S Patel, Radiopaedia.org, rID: 10603

Longitudinal view of a normal appearing acromio-clavicular joint space. The hypoechoic space between the hyperechoic lateral clavicle and the medial edge of the acromion is the acromio-clavicular joint space.[25]Selame, Lauren Ann J., et al. “A Stepwise Guide to Performing Shoulder Ultrasound: The Acromio-Clavicular Joint, Biceps, Subscapularis, Impingement, Supraspinatus Protocol.” Cureus 13.9 … Continue reading

  • Greater Tuberosity Fracture
    • Greater tuberosity fractures appear as a cortical step-off and discontinuity at the junction between the greater tuberosity and humeral articular surface. This is not to be mistaken with cortical irregularities associated with rotator cuff tears which are located focally at the rotator cuff footprint on the greater tuberosity.[26]Vosti KL, Jacobs CD. Outcome measurement in postgraduate year one of graduates from a medical school with a pass/fail grading system. Acad Med. 1999;74(5):547-549. … Continue reading
  • Acromioclavicular Joint Disorders
    • Sonographic findings for pain attributed to acromioclavicular joint arthritis include joint effusion, narrowing of joint space, and osteophytic changes. AC joint dislocation can be visualized as well, with displacement of the distal clavicle from the edge of the acromion.

Pearls and Pitfalls

  • Anisotropy is a common artifact that depends on the direction of the ultrasound beam that leads to artificial hypoechoic or anechoic appearance of the tendon when not perpendicular to the tendon. This can be minimized by constantly tilting the angle of the transducer to remain perpendicular to the tendon fibers.19

  • The subscapularis is multipennate, which can be mistaken for tendinopathy or tear. It is important to visualize the rotator cuff tendon in two axes to avoid misdiagnosis.19

Transducer Location

Patient Position

Structures of Interest

Pathology

Anterior

Neutral

External rotation

Long head of biceps tendon

Subscapularis

Biceps tendinopathy

Biceps tendon rupture

Biceps tendon subluxation/dislocation

Joint effusion

Subscapularis tendinopathy

Superior

Neutral

Dynamic abduction

Acromioclavicular joint

Subacromial space

Supraspinatus

Clavicle

Acromioclavicular arthropathy

Subacromial impingement

Subacromial-subdeltoid bursitis

Supraspinatus tendinopathy

Calcific tendinosis

Clavicle fracture

Anterior

Modified Crass

Supraspinatus

Supraspinatus/infraspinatus tendinopathy

Rotator cuff interval

Posterior

Neutral

Infraspinatus

Teres minor

Glenohumeral joint

Posterior labrum

Infraspinatus/teres minor tendinopathy

Glenohumeral joint dislocation

Paralabral cyst



References

References[+]