Role of Ultrasound and Magnetic Resonance Imaging in Evaluation of ‎Elbow Pain

The elbow is a complex joint designed to withstand a wide range of dynamic exertional forces. There are multiple lesions causing pain at the elbow. The location and quality of elbow pain can generally localize the injury to one of the four anatomic regions: anterior, medial, lateral, or posterior elbow. The purpose of this study is to evaluate the role of ultrasound and ‎magnetic resonance imaging in identifying elbow pain causes. Sixty patients (36male and 24 female) were enrolled in this study who are complaining from elbow pain and or any discomfort at elbow region. ‎Tendinous elbow lesions (flexor and extensor tendon injury) were the most detectable lesions (50/172) (29.0%), followed by ligamentous lesions (medial and lateral collateral ligament injuries) (42/172) (24.41%), bony lesions (38/172) (22.09%), muscle lesions (24/172) (13.95%) and nerve lesions come last with (20/172) (11.76%). Ultrasound is a rapid cheap modality of choice regarding screening of elbow tendionous and ligamentous injury to lesser degree bony and neural lesions, MRI should be considered to assess precisely the extent of any ‎injury in addition to the value of bone visualization & nerve evaluation. Magnetic resonance neurography is a potentially useful diagnostic tool in the evaluation of ulnar neuropathy at the elbow especially ulnar nerve.


Introduction
The musculoskeletal system can be subjected to acute injuries including contusions, strains, sprains, tearing of soft tissues, dislocations, fractures or any combination of these. Systemic diseases including rheumatologic, endocrine, and vascular can lead also to alteration of musculoskeletal biomechanics, which ultimately can change one's function. Infection, tumors are other conditions that can lead to the musculo-skeletal morbidity of varied severity [1].
The elbow is a complex joint designed to withstand a wide range of dynamic exertional forces. The location and quality of elbow pain can generally localize the injury to one of the four anatomic regions: anterior, medial, lateral, or posterior [2].
Ultrasonography has several advantages over other imaging techniques, importantly because of dynamic examination in addition to its rapid, cheap and focused criteria [3].
US may be successfully used to show joint effusion, analyze the features of synovtis in inflammatory diseases, assess tendon, bursae, ligaments nerves and entheseal involvement in patients with pain and swelling of elbow. [4] With its high spatial resolution, excellent soft tissue contrast, and multiplanar imaging capabilities, MRI is often the imaging modality of choice for the evaluation of the painful elbow. The introduction of high-field scanners have reduced scan times and cost with improved image resolution. [5] MRI has become the procedure of choice for evaluating elbow abnormalities, providing images of injuries to ligaments and tendons, compressive or entrapment neuropathy, bone injuries, inflammatory and synovial conditions, as well as soft-tissue masses. [6] Magnetic resonance neurography (MRN) is an imaging study designed to examine peripheral nerves, MRN allows both direct assessment of the nerve lesion, as well as indirect signs of nerve injury such as associated regional muscle denervation. MRN provides better anatomic localization of the entrapment site than is possible with EMG studies, as well as information on the nature of the underlying causative lesion (e.g., benign or malignant mass, fibrosis). [7] 2. Patients Methods 60 patients complaining from elbow pain enrolled in this study. They were referred to Radio-diagnosis & Medical Imaging Department from clinics of Orthopedic and Physical Medicine Departments for Ultrasound & MRI evaluation & assessment. Informed written consent were obtained from all participants in the study after full explanation of the benefits and risks of the procedure. Privacy & confidentiality of all patient data were guaranteed. All data provision were monitored and used for scientific purpose only.

Inclusion Criteria
Patients with elbow pain and /or any discomfort and swelling at elbow region, they were clinically fit to participate in the study and they have no contraindication to MRI.

Exclusion Criteria
Patients with recent trauma with fracture or recent opened wound.

Full History Taking
Present history of Elbow pain, time of occurrence and relation to efforts. Other symptoms as tingling, numbness, swelling and limitation of movement.

Clinical Examination
Including general examination and local elbow examination. The local elbow examinations were done by single independent orthopaedic surgeon and rheumatologist.
Ultrasound is done followed by MRI examination.

Ultrasound Examination
Ultrasound examination of the elbow was done using highfrequency linear transducers with frequencies ranging from 10 to 18 MHz with the use of Color and power Doppler imaging.
A complete assessment of the elbow was in transverse and longitudinal images of all four aspects of the joint: Anterior, lateral, medial, and posterior lateral (figure 1).

MRI Examination
MRI studies were obtained using a closed MRI machine 1.5-T MRI system Patients were in supine position with the arm at the side and palm up.

Image Analysis
The findings obtained for each patient were analyzed and compared with serology, operative data & histopathology which were considered the gold standard for our study.

Results
This prospective study included 60 (36 male, 24 female). Their age ranged from 20 to 60 years & mean age 40.03±6.84. (Table 1), Representing the demographic data of the patients.
The findings were divided according to tissue involved into tendinous lesions followed by ligamentous lesions, bony lesions, muscle lesions and lastly nerve lesions.
N. B. More than one MR. finding was detected in the same patient (Overlapping).

Case 1 Male Patient Aged 30 Years Old Presented by Severe Elbow Pain After Lifting of Heavy Object
A case of intra-muscular hematoma proved by operative intervention

Case 2 A Female Patient Aged 50 Years old Presented by Right Elbow Pain, Swelling and Inability to Move the Elbow Figure 3. (A) Axial T2WI (B) sagittal PDFATSAT & (c) Axial STIR (D) axial 3D FIESTA reveled marked edema affecting all muscles of elbow biceps, triceps and brachialis, subcutaneous tissue overlying the elbow (A), areas of increased bone marrow signal are seen denoting bone marrow edema (B) (green arrow) as an early sign of bony affection ulnar nerve is seen thickened with altered signal at both STIR & FIESTA sequences (red arrow) (C&D).On
Real time ultrasound images of the same patient; transverse view at elbow region showed diffuse subcutaneous edema (E), on color Doppler study seen at (F) showed inflamed and swollen muscle with detected color flow inside muscles.
Over all picture is of elbow joint septic arthritis with ulnar nerve affection by inflammatory response.
A case of capitulum osteochondritis dissecans (OCD) grade V.

Case 4
A female patient aged 60 years presented with right elbow pain associated with limitation of movement of elbow especially extension, with history of intra-muscular (triceps) injection one month ago.
A case of triceps intramuscular collection.

Figure 5. (A) Axial T1WI (B) sagittal T2WI STIR,(C) axial T1WI at the same level &(D) axial T2 STIR with contrast, well defined fluid collection seen inside the muscle fibers of triceps displaying low signal at T1W I(A)&(C), the lesion become more evident after contrast enhancement, as it showed marginal enhancement, high signal seen in bone marrow of distal humerus and olecranon process of ulna as well increased triceps muscle fibers signal at STIR sequence due to nearby inflammatory process (B) &(D).
On ultrasound image (E&F), showed well defined anechoic lesion measured about 5x4mm (red arrow) seen inside the muscle fiber of triceps.

Discussion
The elbow is commonly affected by overuse disorders and inflammatory conditions. Various imaging techniques may be used to assess the elbow, including CT, MRI, and Ultrasound . Imaging plays a crucial role in the evaluation of elbow tendons, ligaments as well as bony lesions. [9] Magnetic resonance imaging has been proven to provide excellent evaluation of ligaments and tendons around the elbow joint, with the ability to show various types of soft tissue and bony abnormalities. [10] This study included sixty patients;(36 Male & 24 Female) with elbow joint lesions of variable causes, In the study males represented (60%) of all patients while female represented (40%), with their age ranged from 20-60 years with mean age about 40±6.84, the right side was more affected than the left side, as right sided affection was 66.7 % of the total cases, while left side represented 33.3%., this agreed with Hasan et al.
[11] whose study was performed on 36 patients, with male representing 52.7% and females representing 47.2% ranging in age from 20 to 64 years (mean age, 31 years), right side was affected by (61%), and the left side (39%).
In this study common extensor origin injury (lateral epicondylitis) was more common than common flexor tendon (medial epicondylitis) with 66.6% to 32 % of total tendinosis lesions, this agreed with Shiri, R, et al [12] which was a random study on 4.783 population in which lateral epicondylitis represented 61% and medial epicondylitis represented 39% of these population.
In this study, lateral tendinopathy included three grades regarding degree of tendon injury, we detected 16 cases (47.0%) with grade1 (Tendinosis) being the most common type of tendinous injury, 10 cases (29.2%) grade II injury (Partial tear) & 8 cases (23.5%) grade III complete tear, this agreed with Zhang et al. [13] who stated that grades of lateral tendinopathy are also 3 grades & grade I is the most common type of injury with 38 cases (39.6%), 31 cases (32.3%) with grade 2, and 27 cases (28.1%) grade 3.
Regarding to ligamentous injury, medial collateral ligament injury was more affected (28/42) 66.6% than lateral collateral ligament injury (14/42) (33.3%), this agreed with Sarath Bethapudi et al. [14], in which medial collateral ligament injury was the most common ligament to be injured in the study group.
In this study there was a great association between lateral epicondylitis and lateral collateral ligament injury which agreed with Liang Qi et al. [15] in which lateral epicondylitis was mostly associated with other abnormalities, mostly RUCL injury.
Regarding to grades of injury of medial collateral ligament, grade I injury was the most common type of medial collateral ligament injury with 18 cases (64.2%) of total ligamentous injury, grade II injury come second with 6 cases (21.4%).& at last grade III injury with 4 cases (14.2%) of total ligamentous injury, this disagreed with Gregory M. Ford, et al. [16] in which grade II was the most common type of elbow injury with 40%, followed by grade III & Last grade I Ultrasound examination revealed 18 cases out of 28 cases (64.2%) regarding medial collateral injury cases, while it revealed 12 out of 14 cases (85%) of lateral collateral ligament injury this mismatched with Torquato Brandão, et al [17 ] who stated that ultrasonography and magnetic resonance imaging can be considered to some extend equivalent modalities for elbow ligament assessment in the hands of experienced examiners In this study two cases of capitular osteochondritis desiccant is seen as a cause of elbow pain, OCD is a disorder of articular cartilage and subchondral bone which is classified into five grades, this case was grade V in which there was a displaced bone fragment and fluid signal seen interposed between it and the parent bone (Capitulum) as well as secondary degenerative changes, its location is in capitulum of humerus agreed with Christiaan J A van Bergen., et al [18] which stated that OCD of the elbow typically affects the humeral capitellum and leads to pain on the lateral aspect of the joint.
Regarding elbow joint bony neoplasm, this study included 10 neoplastic cases which represented 16% of total cases, four patients were diagnosed with giant cell tumor seen at lower humus, the other four patients were diagnosed with osteochondroma and seen at upper radius, this agreed with Halai, et al [19] which reported that primary bony tumors of the elbow are uncommon and account for approximately 1% of all osseous tumors encountered in study group.
[20] who stated that out of 21 patients with ulnar neuropathy, nineteen of patients qualitatively increased ulnar nerve size. Seventeen of them had qualitatively increased signal intensity of the ulnar nerve.
In this study using (MRN) in tracing ulnar nerve at elbow region we had the ability to detect 20 cases of ulnar nerve affection with different nerve lesions, on the other hand usual MRI had the ability to verify only 15 cases out of these 20 cases, with MRI sensitivity of 75% to 100% MRN sensitivity, this matched with Daniel Schwarz, et al [21] who stated that MRI sensitivity to nerve affection at cervical radiculopathy was 69% to 96% regarding MRN.

Conclusion
Us is a rapid cheap modality of choice regarding the elbow examination with precise examination of ligamentous injury & effusion, to less extend the rest of elbow lesions but can be used as a screening tool.
MRI revealed higher sensitivity relative to ultrasound results regarding the tendon lesions & ligamentous injury.
Cases of bony lesions could be assessed accurately by MRI examination however; ultrasonography was much less sensitive than MRI in assessing these lesions.
Regarding intra-articular lesions (joint effusion & synovial thickening) both MRI &Ultrasound revealed nearly the same results with higher sensitivity of MRI over ultrasound.
Ulnar nerve lesions was better assessed by MRI especially MRN neurography sequences (FEISTA & STIR) detecting its abnormal signal or fibers enlargement.