Introduction

Routine radiography, ultrasound, CT, and MR imaging (conventional and arthrography) are the main diagnostic modalities used for diagnosis of abnormalities around the elbow joint.

Conventional Radiography

Radiography ( Fig. 10-1 ) is used for primary evaluation of any osseous elbow pathology by assessment of the bony contours, joints, and fat pads. Limited soft tissue evaluation and ionizing radiation are major limitations. Generally, plain film series for evaluation of the elbow includes anteroposterior, lateral, internal, and external oblique views. Radiocapitellar projection can be useful for fractures of the radial head, capitellum, or coronoid process and the humeroradial and humeroulnar articulation.

FIGURE 10–1, Plain film series. A , Anteroposterior projection. B , Lateral projection. C , Anteroposterior projection in pronation. D , Radiocapitellar projection.

Computed Tomography

Complex osseous anatomy and pathology that is poorly visualized on conventional radiography can be evaluated better with CT ( Fig. 10-2 ; see also ) using multiplanar reconstructions and surface rendering of the osseous anatomy and by rotation of the reconstructed model in infinite projections. Complex fractures, dislocations, degree of healing, and calcifications such as matrix calcification (osteoid, cartilage) in some bone tumors or in soft tissues can be assessed better.

FIGURE 10–2, CT series obtained with 64-slice multidetector CT. A , Axial section through the olecranon and trochlea. B , Axial section through the radioulnar joint. C , Coronal reconstruction through the head of the radius and coronoid process. D , Sagittal reconstruction through the trochlea and ulna.

Computed Tomographic Arthrography

Articular cartilage abnormalities such as chondral and osteochondral fractures and osteochondritis dissecans as well as synovial and capsular abnormalities are well depicted by CT arthrography ( Fig. 10-3 ). The soft tissues are poorly visualized compared to MRI. Ionizing radiation, invasive technique, metal artifacts in postoperative patients, and high costs are other disadvantages.

FIGURE 10–3, CT arthrography. A coronal reconstruction image through radiocapitellar, ulnotrochlear, and proximal radioulnar joint illustrating the cartilage in great detail (arrows) .

Magnetic Resonance Imaging

Soft tissue anatomy and pathology can be better visualized by MRI ( Figs. 10-4 to 10-6 ). MRI does not involve any ionizing radiation, but higher costs, longer examination time, and patient claustrophobia can pose problems.

FIGURE 10–4, Axial T1-weighted MR images depicting normal anatomy from above the elbow joint ( A ) up to the proximal radioulnar joint level ( D ). AM , Anconeus muscle; BM , biceps muscle; BR , brachioradialis muscle; BrM , brachialis muscle; BT , biceps tendon; Co , coronoid; ECRL , extensor carpi radialis longus; EDM , extensor digitorum muscle; FDP , flexor digitorum profundus; FDS , flexor digitorum superficialis; FCU , flexor carpi ulnaris; LE , lateral epicondyle; LF , lacertus fibrosus; ME , Medial epicondyle; MN , median nerve; O , olecranon; PT , pronator teres; RH , radial head; RN & PBV , radial nerve and profunda brachialis vessels; RN s&d , radial nerve superficial and deep branches; SM , supinator muscle; T , trochlea; TT , triceps tendon; UCL , ulnar collateral ligament; UN , ulnar nerve.

FIGURE 10–5, Normal coronal MR anatomy from anterior to posterior. A , Radial collateral ligament (RCL) , ulnar collateral ligament (UCL) . B , RCL and UCL C , Radial head (RH) , processus coronoideus (Co) , RCL, pronator teres muscle (PT) , extensor digitorum muscle (EDM) , and supinator muscle (SM) . D , Lateral ulnar collateral ligament (arrows) . E , Lateral epicondyle (LE) , medial epicondyle (ME) , RH, processus coronoideus ulnae (co) , PT, EDM, SM, RCL. F , Olecranon process (O) , triceps brachii tendon (TT) , anconeus muscle (AM) , flexor digitorum profundus (FDP) .

FIGURE 10–6, Normal sagittal MR anatomy from lateral to medial. A , Lateral epicondyle (LE) , radial head (RH) , triceps brachii muscle (TM) , brachialis muscle (BrM) , biceps brachii muscle (BM) , anconeus muscle (AM) , brachioradialis muscle (BR) , extensor carpi radialis longus (ECRL) , supinator muscle (SM) . B , Trochlea (T) , olecranon (O) , olecranon fossa (FO) , coronoid fossa (FC) , processus coronoideus (co) , BrM, BM, TM. C , O, T, co, flexor digitorum profundus muscle (FDP) , BrM, BM, triceps tendon (TT) . D , Medial epicondyle (ME) , flexor digitorum superficialis muscle (FDS) , pronator teres muscle (PT) .

MR Arthrography

MR arthrography ( Fig. 10-7 ) has an added advantage over plain MR imaging in better evaluation of articular cartilage, intraarticular bodies, and collateral ligaments. Indirect MR arthrography performed by intravenous injection of gadolinium-based contrast is noninvasive and less expensive. Direct MR arthrography involves intraarticular injection of gadolinium-based contrast using a lateral approach over the radial head or a posterolateral approach between the olecranon, humerus, and radial head. It is invasive and expensive, but distention of the joint capsule allows for excellent evaluation of the intracapsular structures.

FIGURE 10–7, Normal MR arthrography. T1-weighted fat-saturated images after intraarticular injection of contrast material. A , Coronal image at the level of the ulnar collateral ligament (UCL) demonstrating its ulnar insertion at the level of the sublime tubercle (ST) . B , Coronal image at the level of the radial collateral ligament (RCL) , illustrating the common flexor tendon (CET) and the synovial fringe or fold (SF) . C , Sagittal image at the level of the radiocapitellar joint demonstrating the synovial fold (SF) and the pseudodefect of the capitellum (PDC) . D , Sagittal image at the level of the medial epicondyle (ME) demonstrating the ulnar nerve (UN) and the common flexor tendon (CFT) . E , Sagittal image demonstrating the distal triceps tendon (TT) . Co , Coronoid process; O , olecranon. F , Sagittal image demonstrating the triceps (TT) , brachialis (BrT) , and biceps (BT) tendons. T , Trochlea.

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