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This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Anatomy & Pathophysiology

Bony Anatomy

• The elbow is a trocho-ginglymoid joint consisting of medial and lateral articulations that provide bony stability [3].
• The medial ulnohumeral articulation is formed by the trochlea articulating with the ulna within the greater sigmoid notch [3].
• The ulnohumeral joint has highly congruent anatomy through almost 180° of articular contact, with the exception of a bare area in the greater sigmoid notch devoid of cartilage [3].
• The coronoid process has medial and lateral facets that buttress the trochlea anteriorly [3].
• The sublime tubercle is located just distal and medial to the coronoid and serves as the attachment site for the anterior bundle of the medial ulnar collateral ligament [3].
• The medial epicondyle is larger and more posteriorly oriented than the lateral epicondyle and serves as the attachment site for the origins of the flexor pronator mass [3].
• The lateral radiocapitellar joint is formed by the capitellum and radial head [3].
• The radius is held in close approximation to the ulna at the proximal radioulnar joint by the annular ligament [3].
• The area of the ulna that articulates with the margin of the radial head at the proximal radioulnar joint is known as the lesser sigmoid notch [3].
• The radial head is a concave elliptical structure covered with articular cartilage along the radiocapitellar joint and approximately 270° of the articular margin [3].
• The radial head articulates with both the capitellum and the lesser sigmoid notch [3].
• The lateral epicondyle is the origin of the lateral extensor musculature [3].
• The origin of the lateral ulnar collateral ligamentous complex is located just distal to the lateral epicondyle at the geometric center of the radiocapitellar articulation [3].
• The distal humeral articulation is angled 30° from the longitudinal axis [3].
• The anterior humeral line should pass through the center of the axis of rotation [3].
• The axis of rotation is 5° to 7° angulated in the coronal plane to the epicondylar axis, with the medial side more distal than the lateral side [3].
• This coronal angulation accounts for the change from a valgus carrying angle to a more varus position as the elbow is flexed [3].
• There is a high correlation between the size of the radial head and capitellum on the left and right sides of the same individual [2, 3].
• The olecranon provides a broad attachment site for the triceps [3].
• The ulna bends approximately 8° medially at 8 cm from the tip of the olecranon [3].
• The articulation to the tip of the coronoid is approximately 30° from the long axis of the ulna in the sagittal plane [3].

Ligaments & Soft Tissue

• Elbow stability is determined by primary stabilizers, which include the ulnohumeral articulation, the medial ulnar collateral ligament, and the lateral ulnar collateral ligament complex [1].
• Secondary stabilizers of the elbow include the radiocapitellar articulation, the common flexor tendon, the common extensor tendon, and the joint capsule [1].
• The medial ulnar collateral ligament is comprised of the anterior bundle, posterior bundle, and transverse ligament [2].
• The anterior bundle of the medial ulnar collateral ligament is the strongest component and the primary restraint to valgus stress [2].
• The anterior bundle of the medial ulnar collateral ligament is subdivided into anterior and posterior bands that provide reciprocal function, with the anterior band tight in extension and the posterior band tight in flexion [2].
• The lateral ulnar collateral ligament origin center is 10.7 mm from the lateral epicondyle [2].
• The lateral ulnar collateral ligament insertion is 3.3 mm from the apex of the supinator crest [2].
• Tensile forces are present at the medial elbow, while compressive forces are present at the lateral elbow [4, 5].
• The joint capsule allows maximum distension at approximately 70 to 80 degrees of flexion [4, 5].
• The anterior capsule attaches at a point approximately 6 mm distal to the tip of the coronoid [4, 5].
• The coronoid tip is an intraarticular structure that is visualized during elbow arthroscopy [4, 5].
• The medial or ulnar collateral ligament is the primary valgus stabilizer [4, 5].
• The anterior bundle of the medial ulnar collateral ligament is the most important component for stability [4, 5].
• The posterior bundle of the medial ulnar collateral ligament has the greatest change in length and becomes taut at flexion beyond 120 degrees [4, 5].
• The lateral ulnar collateral ligament is the posterolateral stabilizer [4, 5].
• Osborne’s ligament stabilizes the ulnar nerve in the cubital tunnel [4, 5].
• The ligament of Struthers is a variant anatomy arising from the supracondylar process to attach to the medial epicondyle and is a potential site of median nerve compression [4, 5].

Muscles & Insertions

• The brachialis is the strongest elbow flexor and attaches to the coronoid 11 mm distal to the tip [4, 5].
• The biceps brachii inserts at the ulnar margin of the radial tuberosity, with the long head inserting proximal and the short head inserting distal [4, 5].
• The biceps brachii is a powerful supinator of the forearm [4, 5].
• The triceps is the primary elbow extensor and inserts on the olecranon process [4, 5].
• The mobile wad consists of the brachioradialis, extensor carpi radialis longus, and extensor carpi radialis brevis [4, 5].
• The flexor-pronator mass consists of the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis [4, 5].
• The triceps has three distinct insertional areas to the olecranon corresponding to the posterior capsular insertion, the deep muscular portion, and the superficial tendinous portion [2].
• The deep muscular head of the triceps corresponds to the medial head, while the tendinous portion corresponds to the long and lateral heads [2].
• The width of the triceps insertion is 2.6 cm and is located 1.1 cm from the tip of the olecranon [2].

Biomechanics & Motion

• The normal elbow has a range of motion from 0° to 140° from extension to flexion [1].
• The normal elbow has a range of motion of 75° in pronation and 85° in supination [1].
• A functional arc for the elbow is 100° for flexion and extension and forearm rotation [1].

Investigations

Physical Examination

• The physical examination of the elbow is directed by the history and the location of the patient's pain in the anterior, posterior, medial, or lateral aspect [1].
• Active and passive flexion, extension, supination, and pronation should be evaluated using a goniometer for accurate measurement [9].
• The contralateral elbow should be examined for comparison during range of motion assessment [9].
• Pain should be assessed during the mid-arc or at the terminal ends of motion [9].
• Mid-arc range of motion pain is more common with intrinsic disease and may not improve with contracture release alone [9].
• The ulnar nerve is of utmost importance in the physical examination due to its anatomic proximity to the elbow [9].
• An assessment for ulnar nerve subluxation should be performed [9].
• Subluxation of the ulnar nerve is a relative contraindication for an arthroscopic procedure secondary to possible iatrogenic nerve injury [9].
• Electromyography and nerve conduction velocity studies should be performed if there is any question about neurologic dysfunction [9].

Imaging

• Plain radiographs remain the hallmark and the best screening test for elbow evaluation [1].
• Standard radiographic views include AP, lateral, and oblique views [9].
• Serial radiography is used as follow-up when heterotopic ossification is present [9].
• Primary bony landmarks identified on radiographs include the ulnohumeral joint, coronoid process, radial head, capitellum, radiocapitellar joint, olecranon tip, coronoid/olecranon fossae, and trochlear ridge [9].
• CT is helpful when assessing for malunion architecture and the location and pattern of osteophytes and/or loose bodies [9].
• Three-dimensional CT is used to check for heterotopic ossification [9].
• CT is not necessary when the stiffness is entirely soft-tissue related [9].
• CT is beneficial if any joint incongruity or abnormal bony anatomy is present [9].
• MRI can be used to evaluate ligaments and tendons, but it is rarely indicated for elbow stiffness [9].
• MRI may be most helpful in evaluating associated injuries including partial or complete tears of the medial collateral ligament in the context of valgus extension overload syndrome [11].
• CT with two-dimensional reconstruction and three-dimensional surface rendering best visualizes the pathology of valgus extension overload syndrome [11].
• AP, lateral, oblique, and axillary views of the elbow may reveal posteromedial olecranon osteophytes and/or loose bodies in valgus extension overload syndrome [11].
• Radiographic evaluations are essential when diagnosing an osteochondritis dissecans lesion of the elbow [12].
• Important aspects of osteochondritis dissecans lesions may be better seen with MRI [12].
• Standard AP and lateral radiographs should be obtained for the evaluation of elbow osteoarthritis [13].
• Radiographs typically show osteophyte formation at the coronoid process, coronoid fossa, radial fossa, radial head, olecranon tip, and olecranon fossa in elbow osteoarthritis [13].
• Joint spaces at the ulnohumeral joint are usually preserved in elbow osteoarthritis [13].
• Joint spaces at the radiocapitellar joint are mildly narrowed in elbow osteoarthritis [13].
• Loose bodies may be evident on radiographs, which typically underestimate the number present [13].
• CT may be useful for surgical planning in elbow osteoarthritis, allowing a detailed assessment of osteophytes and the presence of loose bodies [13].

References

[1] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Biomechanics, Physical Examination, and Imaging of the Elbow > Summary and Conclusions.

[2] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Biomechanics, Physical Examination, and Imaging of the Elbow > Annotated References.

[3] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Anatomy, Biomechanics, Physical Examination, and Imaging of the Elbow > Anatomy > Bony Anatomy.

[4] Miller S Review Of Orthopaedics. SECTION 16 PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY > TABLE 2.3 Shoulder Spaces.

[5] Miller S Review Of Orthopaedics. Genetics of musculoskeletal conditions and abnormalities are summarized in Table 1.27 > TABLE 2.3 Shoulder Spaces.

[9] Aaos Comprehensive Orthopaedic Review 3. Elbow Stiffness* > IV. Evaluation.

[11] Aaos Comprehensive Orthopaedic Review 3. Elbow Injuries in the Athlete* > III. Valgus Extension Overload Syndrome and Posterior Impingement.

[12] Orthopaedic Knowledge Update. Osteochondritis Dissecans of the Knee and Elbow* > Summary.

[13] Aaos Comprehensive Orthopaedic Review 3. Arthritis and Arthroplasty of the Elbow > I. Osteoarthritis.