High-resolution ultrasonography can help clinicians visualize key anatomic structures of the elbow and guide periarticular and intra-articular injections. Historically, most procedures done around the elbow have been done using landmark guidance, and few studies have reported the accuracy of ultrasonography-guided injections in the elbow region. This article reviews common musculoskeletal disorders about the elbow that can be evaluated with ultrasonography, reviews the literature on ultrasonography-guided injections of the elbow region, and describes the senior author’s preferred approach for the most commonly performed elbow region injections.
Key points
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Ultrasound is a useful modality for the evaluation of musculoskeletal elbow disorders and for the guidance of procedures in the elbow region.
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Current evidence shows that ultrasound-guided injections in the elbow region have superior accuracy to anatomic landmark–guided injections in the elbow region, although larger, higher-quality evidence is needed.
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Lateral epicondylosis is a common cause of elbow disorder, and ultrasound guidance is increasingly useful for the effective and precise delivery of novel treatments into this tendon.
Introduction
The elbow is a synovial joint with 3 articulations between the humerus, radius, and ulna (ulnohumeral, radiocapitellar, and proximal radioulnar joints) and 2 planes of motion (flexion/extension and pronation/supination). Functioning as a modified hinge joint, the elbow assists in positioning the hand in space, providing a powerful grasp and serving as a fulcrum for the forearm. The joint must be flexible enough to accommodate these complex movements and stable enough to transmit forces from the hand through the shoulder. The interlocking bony anatomy of the elbow makes it inherently stable, but the capsuloligamentous restraints and elbow musculature also play a role. Although high-resolution ultrasound (US) can help clinicians easily visualize key anatomic structures, understanding the complex anatomy and biomechanics of the elbow is essential to the successful diagnosis and treatment of common disorders.
Musculoskeletal clinicians frequently perform periarticular and intra-articular injections to manage elbow disorders. Historically, most procedures done around the elbow have been done using anatomic landmark guidance without live imaging; however, a recent review and position statement by the American Medical Society for Sports Medicine found that US-guided injections (USGI) had improved accuracy, efficacy, and cost-effectiveness compared with landmark-guided injections (LMGI) for large joints (eg, knees and shoulders). Few studies have assessed the accuracy of USGI for the elbow, and a review of the current literature found only 3 head-to-head studies comparing LMGI with USGI around the elbow, and all 3 examined only intra-articular injections.
Given that the success of an injection often depends on placing the needle within the intended target, US is a safe, accessible, and inexpensive tool to ensure accurate needle placement. This article reviews common musculoskeletal disorders of the elbow ( Table 1 ) that can be evaluated with US, reviews the literature on USGI of the elbow, and describes the senior author’s preferred approach to the most common injections.
| Anterior | Joint space, anterior coronoid recess | Effusion, synovial hypertrophy, loose bodies |
| Humeroradial/humeroulnar joint, coronoid and radial fossae | Integrity of the articular cartilage and cortical bone, fracture | |
| Annular recess and neck of the radius | Effusion, synovial hypertrophy, loose bodies, dynamic assessment of radial head in supination and pronation for radial head subluxation | |
| Distal biceps tendon | Full-thickness or partial-thickness tears, tendinosis, bicipitoradial bursitis | |
| Brachialis muscle | — | |
| Median nerve | Entrapment at level of distal humerus (ligament of Struthers), antecubital region (pronator teres), atrophy of distal muscles | |
| Radial nerve | Supinator syndrome or radial tunnel syndrome (hypoechoic swelling of nerve at entry of Arcade of Fröhse) | |
| Radial and brachial vessels | — | |
| Lateral | Lateral epicondyle, common extensor tendon, proximal attachments of the extensor carpi radialis longus and brachioradialis | Epicondylosis, adjacent bone irregularity, full-thickness or partial-thickness tear (former is uncommon) |
| Radial collateral ligament | Ligament tear | |
| Medial | Medial epicondyle/common flexor tendon | Epicondylosis, adjacent bone irregularity |
| Ulnar collateral ligament | Full-thickness or partial-thickness tear, laxity on dynamic examination | |
| Ulnar nerve in cubital tunnel | Nerve entrapment (hypoechoic swelling of ulnar nerve), dynamic examination with elbow flexion and extension to assess for subluxation, snapping triceps syndrome, anconeus epitrochlearis muscle | |
| Posterior | Posterior joint space (olecranon recess) and olecranon process | Effusion with elevation of the hyperechoic fat pad, synovial hypertrophy, loose bodies, fracture |
| Distal triceps tendon | Full-thickness or partial-thickness tears, distal avulsion, tendinosis | |
| Olecranon bursa | Bursitis, synovial hypertrophy/proliferation | |
| Distal biceps tendon insertion | Dynamic evaluation of insertion at radial tuberosity with pronation and supination |
a Anatomic structures as outlined in the American Institute of Ultrasound in Medicine practice parameters for the US examination of the elbow.
Introduction
The elbow is a synovial joint with 3 articulations between the humerus, radius, and ulna (ulnohumeral, radiocapitellar, and proximal radioulnar joints) and 2 planes of motion (flexion/extension and pronation/supination). Functioning as a modified hinge joint, the elbow assists in positioning the hand in space, providing a powerful grasp and serving as a fulcrum for the forearm. The joint must be flexible enough to accommodate these complex movements and stable enough to transmit forces from the hand through the shoulder. The interlocking bony anatomy of the elbow makes it inherently stable, but the capsuloligamentous restraints and elbow musculature also play a role. Although high-resolution ultrasound (US) can help clinicians easily visualize key anatomic structures, understanding the complex anatomy and biomechanics of the elbow is essential to the successful diagnosis and treatment of common disorders.
Musculoskeletal clinicians frequently perform periarticular and intra-articular injections to manage elbow disorders. Historically, most procedures done around the elbow have been done using anatomic landmark guidance without live imaging; however, a recent review and position statement by the American Medical Society for Sports Medicine found that US-guided injections (USGI) had improved accuracy, efficacy, and cost-effectiveness compared with landmark-guided injections (LMGI) for large joints (eg, knees and shoulders). Few studies have assessed the accuracy of USGI for the elbow, and a review of the current literature found only 3 head-to-head studies comparing LMGI with USGI around the elbow, and all 3 examined only intra-articular injections.
Given that the success of an injection often depends on placing the needle within the intended target, US is a safe, accessible, and inexpensive tool to ensure accurate needle placement. This article reviews common musculoskeletal disorders of the elbow ( Table 1 ) that can be evaluated with US, reviews the literature on USGI of the elbow, and describes the senior author’s preferred approach to the most common injections.
| Anterior | Joint space, anterior coronoid recess | Effusion, synovial hypertrophy, loose bodies |
| Humeroradial/humeroulnar joint, coronoid and radial fossae | Integrity of the articular cartilage and cortical bone, fracture | |
| Annular recess and neck of the radius | Effusion, synovial hypertrophy, loose bodies, dynamic assessment of radial head in supination and pronation for radial head subluxation | |
| Distal biceps tendon | Full-thickness or partial-thickness tears, tendinosis, bicipitoradial bursitis | |
| Brachialis muscle | — | |
| Median nerve | Entrapment at level of distal humerus (ligament of Struthers), antecubital region (pronator teres), atrophy of distal muscles | |
| Radial nerve | Supinator syndrome or radial tunnel syndrome (hypoechoic swelling of nerve at entry of Arcade of Fröhse) | |
| Radial and brachial vessels | — | |
| Lateral | Lateral epicondyle, common extensor tendon, proximal attachments of the extensor carpi radialis longus and brachioradialis | Epicondylosis, adjacent bone irregularity, full-thickness or partial-thickness tear (former is uncommon) |
| Radial collateral ligament | Ligament tear | |
| Medial | Medial epicondyle/common flexor tendon | Epicondylosis, adjacent bone irregularity |
| Ulnar collateral ligament | Full-thickness or partial-thickness tear, laxity on dynamic examination | |
| Ulnar nerve in cubital tunnel | Nerve entrapment (hypoechoic swelling of ulnar nerve), dynamic examination with elbow flexion and extension to assess for subluxation, snapping triceps syndrome, anconeus epitrochlearis muscle | |
| Posterior | Posterior joint space (olecranon recess) and olecranon process | Effusion with elevation of the hyperechoic fat pad, synovial hypertrophy, loose bodies, fracture |
| Distal triceps tendon | Full-thickness or partial-thickness tears, distal avulsion, tendinosis | |
| Olecranon bursa | Bursitis, synovial hypertrophy/proliferation | |
| Distal biceps tendon insertion | Dynamic evaluation of insertion at radial tuberosity with pronation and supination |
a Anatomic structures as outlined in the American Institute of Ultrasound in Medicine practice parameters for the US examination of the elbow.
Lateral evaluation
On US, the common extensor tendon normally has a hyperechoic fibrillar appearance. Changes in tendon echogenicity (generally increased hypoechogenicity), thickening of the tendon, cortical irregularity, intratendinous calcification, and/or tendon hyperemia signify degenerative changes and are seen with lateral epicondylosis. Deep to the common extensor tendon lies the radial (lateral) collateral ligament, which typically occupies approximately 50% of footprint at the lateral epicondyle, and should also be assessed with the lateral evaluation.
Lateral Epicondylosis
First described in 1882, lateral epicondylosis is the most common cause of lateral elbow pain. Pathologic changes typically occur within the deep-anterior fibers of the common extensor tendon at its origin on the lateral epicondyle. Therapeutic injections have long been a cornerstone of management for lateral epicondylosis. Once thought to be an inflammatory process, glucocorticoid injections were used as early as the 1950s to help treat local inflammation in this condition. Lateral epicondylosis is now recognized as a degenerative process, but despite this shift in understanding, corticosteroids remain the most common injectate studied and the most common substance injected. Numerous randomized controlled trials have compared LMGI with corticosteroids versus local anesthetics, saline injections, prolotherapy, physical therapy, and observation (the wait-and-see approach). Many of these studies showed short-term symptomatic relief; however, these benefits are often not sustained. Long-term studies have shown that corticosteroid injections are no more beneficial than observation alone, and may even have an inferior outcome with higher recurrence rates at 1 year.
Studies of USGI of corticosteroid for lateral epicondylosis are limited. McShane and colleagues presented 2 case series of patients with chronic lateral epicondylosis treated with US-guided percutaneous needle tenotomy. In the 2006 study, subjects underwent fenestration of the common extensor tendon followed by an injection of corticosteroid and bupivacaine. In a subsequent 2008 study, McShane and colleagues repeated the same protocol, but without the corticosteroid and found superior results. The investigators concluded that corticosteroid injections are not a necessary component of the procedure. In a 2013 randomized controlled trial, Krogh and colleagues compared USGI with corticosteroids, platelet-rich plasma (PRP) and saline injections. Sixty patients were enrolled, with 20 in each treatment arm, and there was no significant difference in pain reduction between the 3 groups at 3 months. One significant limitation of this study was that, despite a predetermined 12-month study interval, the 6-month and 12-month outcomes were not reported because of a significant number of patients being lost to follow-up, and the maximum benefits from a PRP injection may not be realized until 6 months after the injection.
Once the gold standard for the treatment of lateral epicondylosis, glucocorticoid injections are now considered to have a deleterious effect on this condition, and a growing number of novel injection therapies for lateral epicondylosis have been reported in the literature. Randomized studies have examined the role of botulinum toxin, prolotherapy, and sclerosing solutions. Despite botulinum toxin being the second most studied injectate in randomized controlled trials, no studies have examined USGI with botulinum toxin for lateral epicondylosis. A growing body of literature has also examined autologous whole-blood injections, PRP, autologous stem cell therapy, and percutaneous needle tenotomy to augment the natural healing process. These procedures are discussed in more detail elsewhere in this issue.
US guidance has been used in a few of these studies using novel injectate ( Table 2 ). In 2013, Rabago and colleagues presented a prospective randomized controlled trial of USGI of prolotherapy with 3 treatment arms: (1) 20% dextrose solution (PrT-D), (2) dextrose-morrhuate sodium (PrT-DM) solution, and (3) observation. The 2 prolotherapy groups showed improvement in Patient-rated Tennis Elbow Evaluation composite scores at both 16 and 32 weeks’ follow-up compared with the observation group. The PrT-D group had less pain and improved grip strength compared with the other groups. In 2006, Zeisig and colleagues presented a pilot study of USGI of polidocanol, a local anesthetic and sclerosant. Although the pilot study showed a significant improvement in pain and grip strength at 8 months, a larger prospective randomized controlled study failed to reproduce these results at 3-month, 12-month, or 24-month follow-up, and a network meta-analysis found no significant difference between polidocanol and placebo.
| Procedure | Number of Subjects | Duration of Follow-up (wk) | Study Design | Level of Evidence a | |
|---|---|---|---|---|---|
| Lateral Epicondylosis | |||||
| Corticosteroids | |||||
| McShane et al, 2006 | PNT + CSI | 58 | 121 (range 73–191) | Cohort | III |
| McShane et al, 2008 | PNT | 52 | 88 (range 28–152) | Cohort | III |
| Prolotherapy | |||||
| Rabago et al, 2013 | PRT-D vs PRT-DM vs observation | 26 (32 elbows) | 32 | RCT | II |
| Sclerosing Therapy | |||||
| Zeisig et al, 2006 | Polidocanol | 11 (13 elbows) | 35 | Cohort | III |
| Zeisig et al, 2008 | Polidocanol | 32 (36 elbows) | 52 | Cohort | III |
| Zeisig et al, 2010 | Polidocanol | 25 (28 elbows) | 104 | Cohort | III |
| Orthobiologics | |||||
| Connell et al, 2006 | Autologous blood + PNT | 35 | 26 | Cohort | III |
| Connell et al, 2009 | Autologous dermal fibroblast | 12 | 26 | Cohort | III |
| Stenhouse et al, 2013 | Autologous conditioned plasma + PNT vs PNT | 28 | 26 | RCT | II |
| Krogh et al, 2013 | PRP vs CSI vs saline (PNT) | 60 | 13 | RCT | II b |
| Medial Epicondylosis | |||||
| Suresh et al, 2006 | Autologous blood + PNT | 20 | 44 | Cohort | III |
| Ulnar Collateral Ligament Disorders | |||||
| Podesta et al, 2013 | PRP | 34 | 70 (range 11–117) | Cohort | III |
| Distal Biceps Disorders | |||||
| Sanli et al, 2014 | Intratendon PRP | 12 | 47 (range 36–52) | Cohort | III |
| Barker et al, 2015 | Intratendon PRP | 6 | 16.3 (range 12–30) | Cohort | III |
| Mautner et al, 2015 | Intratendon PRP | 1 | 18 | Case report | IV |
a Level of evidence was assigned through collaboration between 2 of the authors according to guidelines set forth by Wright.
Sonographic Needle Placement
US findings of lateral epicondylosis have been well documented, but no studies have compared USGI versus LMGI for the treatment of this condition. Depending on the injectate, the precise needle target around the common extensor tendon may vary. For example, corticosteroid injections have traditionally targeted the peritendinous region superficial to the common extensor tendon. However, with the novel treatments described earlier (eg, percutaneous needle fenestration, orthobiologics) the needle should be directed into areas of abnormality within the tendon.
The patient is positioned in a seated or supine position with the elbow flexed to approximately 90°, forearm prone, and the lateral aspect of the elbow facing the clinician. The US transducer is positioned in long axis to the common extensor tendon, the needle oriented in plane to the transducer, and the needle is advanced in a distal to proximal direction ( Fig. 1 ). The length of the needle is typically 25 to 38 mm given the superficial nature of the common extensor tendon; the needle may vary from 18 to 25 gauge depending on the indication and goals of the procedure. Injectate volume likewise may vary but is typically 2 to 3 mL.
Medial evaluation
The common flexor tendon originates from the medial epicondyle, and is shorter and broader than the common extensor tendon. The normal tendon appears as a hyperechoic fibrillary structure and pathologic changes are characterized by degenerative changes, similar to those with lateral epicondylosis described earlier. The medial evaluation should also include examination of the anterior band of the ulnar (medial) collateral ligament (UCL), which is the major stabilizer of valgus stress at the elbow. Normally, the anterior band of the UCL appears as a fibrillar, hyperechoic, fanlike structure traversing from the medial epicondyle to its insertion on the sublime tubercle of the coronoid process on the ulna. Dynamic assessment of the UCL can be performed by placing the elbow under valgus stress with the elbow in slight flexion to disengage the olecranon. Complete tears result in discontinuity of the ligament and widening of the ulnohumeral joint with greater than a 0.5-mm difference between rest and stress, whereas partial tears can result in thickening of the ligament with internal disruption. The ulnar nerve can also be assessed at the elbow, and should be dynamically examined for signs of entrapment or subluxation.
Medial Epicondylosis
Medial epicondylosis is not as common as its lateral counterpart, which is diagnosed 7 to 10 times more often. Although a growing body of literature has explored different types of therapeutic injections for chronic lateral epicondylosis, the literature is limited for medial epicondylosis. Corticosteroids are the only injectate that has been studied in prospective randomized controlled trials, and neither of these 2 studies used US guidance. Similar to lateral epicondylosis, subjects showed a short-term benefit, but had no sustained benefit at 3 months or 1 year.
US guidance has only been used in 1 prospective cohort study for chronic medial epicondylosis. In 2006, Suresh and colleagues presented 20 subjects with US-guided needle fenestration followed by an injection of autologous blood (2 mL) into the site of maximum tendon injury. A second autologous blood injection, also 2 mL, was performed at 4 weeks’ follow-up. Three of the 20 patients failed to improve following the procedure, but at the 10-month follow-up interval the remaining 17 patients had improvement in Visual Analog Scale pain scores and Nirschl elbow scores.
Sonographic Needle Placement
There is limited literature on USGI for medial epicondylosis. Given the proximity of the ulnar nerve to the common flexor tendon there is the potential to accidentally injure the nerve, and case reports have described this complication with LMGI of corticosteroids in this region.
The senior author prefers positioning the patient in a supine position for comfort, although the procedure can be done with the patient seated. The elbow should be flexed and abducted approximately 90°, forearm supine, and the medial aspect of the elbow facing the clinician. The US transducer should be positioned in long axis to the common flexor tendon origin, the needle oriented in plane to the transducer, and the needle advanced in a distal to proximal direction ( Fig. 2 ). Similar to injection of the common extensor tendon, the length of the needle is typically 25 to 38 mm, needle may vary from 18 to 25 gauge depending on the indication and goals of the procedure, and injectate volume is typically 2 to 3 mL.
