The elbow is a complex joint that is designed to withstand a variety of dynamic forces. Its main role in the upper limb is to help position the hand in the appropriate location, in order for the hand to perform its function. Elbow pain may be due to disorders involving the joint itself or the surrounding structures. In addition, referred pain may arise from regions above or below the joint. As is key with other musculoskeletal diagnoses, history is a crucial tool that should be utilized to find out about the mechanism of injury in order to diagnose elbow pain. Also, a focused physical exam in conjunction with imaging studies, when necessary, will provide valuable information needed to arrive at the correct diagnosis.
The elbow is formed by the articulation of the distal end of the humerus with the proximal ends of the bones of the forearm; the radius on the side of the thumb and the ulna on that of the little finger.1 (Figure 1.1)
The distal end of the humerus expands laterally and medially, and at that same time becomes flattened anteroposteriorly. The medial and lateral borders made up of the supracondylar ridges, give origin to the muscles of the forearm and elbow region to make up the prominent medial and lateral epicondyles. On the posteroinferior surface of the medial epicondyle is the groove for the ulnar nerve to course through. The distal end of the humerus has two articular surfaces, a lateral capitulum for articulation with the head of the radius and a medial trochlea for articulation with the ulna. Above the rounded trochlea, anteriorly, is the coronoid fossa which receives the coronoid process of the ulna when the forearm is flexed.1,2
Posteriorly, the olecranon fossa receives the olecranon, which allows for the hinged joint formed in the elbow for flexion and extension motions. The concavity on the anterior surface of the humerus above the capitulum is the radial fossa, which receives the head of the radius when the forearm is flexed.1,2
The proximal end of the ulna, the olecranon, is subcutaneous. On the anterior surface of the ulna is the deep trochlear notch for articulation with the trochlea of the humerus. The articular surface of the notch is shared by the projecting coronoid process. On the lateral side of the coronoid process, there is a second articular surface, the radial notch, which receives the head of the radius. The proximal end of the radius is an expanded disc-like head, with a slight concavity allowing for capitulum to rotate on the humerus.1,2
As one can see from the anatomy described above, there are three joints present at what is referred to as “the elbow joint,” and these are, the humeroulnar, humeroradial, and proximal radioulnar joints. The humeroulnar and humeroradial joints are associated with the movements of flexion and extension of the forearm at the elbow, whereas the proximal radioulnar joint works in conjunction with the distal radioulnar joint to permit pronation and supination. A single articular capsule surrounds the three joints at the elbow, and a single joint cavity is present.3
The joint capsule at the elbow is thin and lax, allowing free movement. Anteriorly and posteriorly, muscles rather than ligaments protect the capsule, but medially and laterally, special ligaments are present. The ulnar collateral ligament arises from the medical epicondyle and fans out to insert on the coronoid process and olecranon. The ulnar collateral ligament has two parts, which along with the flexor carpi ulnaris muscle form the cubital tunnel through which passes the ulnar nerve. The radial collateral ligament arises from the lateral epicondyle. It fans out less than the ulnar collateral ligament does.2,3
Sensory innervation to the joints can be provided by any of the nerves passing across the elbow (musculocutaneous, radia, median, and ulnar) but the majority of the branches are supplied by the musculocutaneous and radial nerves.2
BIOMECHANICS OF THE ELBOW
The humeroulnar joint, also known as trochlear joint, is formed by the articulation of the trochlea of the humerus and the trochlear notch of the ulna. It is classified as a uniaxial hinge joint. The resting position of this joint is with the elbow flexed to 70 degrees and the forearm supinated to 10 degrees. The neutral position (0 degrees) is midway between supination and pronation in the “thumb-up” position.2
The humeroradial joint is the articulation between the capitulum of the humerus and the concave depression on the head of the radius. It too is a uniaxial hinge joint. The resting position is with the elbow fully extended and the forearm fully supinated. At least 30 degrees from full extension and 130 degrees of flexion are necessary for the activities of daily living.2,3
The proximal radioulnar joint is the articulation of the outer surface of the head of the radius with the radial notch of the ulna, to produce the movements of pronation and supination.
It is a uniaxial pivot joint. The head of the radius is held in proper relation to the ulna and humerus by the annular ligament, which makes up four-fifths of the joint. The resting position of this joint is supination of 35 degrees and elbow flexion of 70 degrees. The elbow can rotate from 0 to 180 degrees. At least 50 degrees of pronation and supination are necessary for the activities of daily living.3 (Figure 1.2)
HISTORY, SIGNS, AND SYMPTOMS
The crucial elements of the history may vary depending on whether the complaints are acute or chronic. Acute complaints begin with a discrete event; chronic complaints have an insidious onset and a longer duration of symptoms. The history should include the following questions:4
What is the patient’s usual activity or pastime? What is the patient’s occupation?
How long have the symptoms been present? Was there a traumatic event that caused the symptoms?
What are the details of the present pain and other symptoms? What are the sites and boundaries of the pain? What makes the symptoms worse, better, motions that worsen and improve the pain?
How old is the patient? If the patient is a child who complains of pain in the elbow and lacks supination on examination, the examiner should suspect a dislocation of the head of the radius. Tennis elbow problems usually occur in persons 35 years of age or older and in those who use a great deal of wrist flexion and extension in their occupations.
Does the patient complain of any abnormal nerve distribution pain? The examiner should notes whether there is any tingling or numbness.
Are any movements impaired? Which movements does the patient feel are restricted?
Past medical history, family history, and review of systems must be included to rule out other causes of joint pain and swelling (e.g. arthritis, gout, infection, or neoplasm).4,5
Physical Exam. The Key components of the physical exam of the elbow should include the following:
Observation: the patient must be suitably undressed so that both arms are exposed to allow comparison of the two sides. Look for ecchymosis, swelling, muscular atrophy, and breaks in the skin that may indicate an open fracture or entry point of infection. The examiner first places the patient’s arms in the anatomic position to determine whether there is a normal carrying angle. It is the angle formed by the long axis of the humerus and the long axis of the ulna and is most evident when the elbow is straight and the forearm is fully supinated. In the adult, this would be a slight valgus deviation between the humerus and the ulna when the forearm is supinated and the elbow is extended. In males, the normal carrying angle is 5 to 10 degrees and in females it is 10 to 15 degrees.1,5
Palpation: with the patient’s arm flexed, the examiner begins palpation on the anterior aspect and moves to the medial aspect, the lateral aspect, and finally the posterior aspect. The examiner is looking for tenderness, abnormality, change in temperature or in texture of the tissue, or abnormal “bumps.” Palpation along the normal bony landmarks, grooves, and joints should also be done.1,4,5
Range of motion: as always, active movements are done first, and it is important to remember that the most painful movements are done last. The active movements include:
Flexion of the elbow (140 to 150 degrees).
Extension of the elbow (0 to 10 degrees).
Supination of the forearm (90 degrees).
Pronation of the forearm (80 to 90 degrees).
If the range of motion is full on active movements, over-pressure may be gently applied to test the end feel in each direction. If the movement is not full, passive movements should be carried out to test the end feel.1,4
Neurovascular examination: the reflexes around the elbow that are often checked include the biceps (C5-C6), brachioradialis (C5-C6), and triceps (C7-C8). The examiner should also check the dermatomes around the elbow and the cutaneous distribution of the various nerves, noting any difference. Pain may be referred to the elbow from the neck, the shoulder, or the wrist.5
Resisted Isometric movements: for proper testing of the muscles of the elbow complex, the movement must be resisted and isometric. The manual muscle testing should also be done with the patient not having mechanical advantage.1,5
Provocative testing: specific testing can be done to generate pain that the patient may be experiencing. These are tests done to diagnose and produce concordant pain that the patient may be experiencing.1
When appropriate, the joint above and below the elbow joint should be examined. In many cases referred pain can be perceived in the elbow, however, with origin of the pain coming from the wrist, hand, shoulder, neck, etc.1
DIFFERENTIAL DIAGNOSIS OF ELBOW PAIN
When evaluating the patient with elbow pain, the prudent practitioner must consider various diagnoses that can produce similar symptoms. Conditions that the physician should consider include lateral epicondylitis, medial epicondylitis, radial tunnel syndrome, intra-articular pathology including radiocapitellar chondral lesions, cervical radiculopathy, ulnar neuropathy, elbow overuse as a compensatory mechanism, inflammation/edema of the anconeus, and inflammatory or degenerative arthritis.6
Radial tunnel syndrome is the name given to the constellation of symptoms that accompany compression of the posterior interosseous nerve (terminal motor branch of the radial nerve). Radial tunnel syndrome is a condition that can be difficult to differentiate from lateral epicondylitis. In the former, maximal tenderness in typically noted 3-4cm distal and anterior to the epicondyle. One useful pearl to differentiate the two pathologies is that resisted wrist extension is usually painful in lateral epicondylitis, but is often not painful in radial tunnel syndrome. Further, resisted thumb and index finger extension may be painful in radial tunnel syndrome but is usually not painful with lateral epicondylitis. Additionally, forearm supination may cause compression of the radial nerve within the supinator muscle and may elicit pain if radial tunnel syndrome is present.6
Medial epicondylitis is characterized by pain along the medial elbow. Plain radiographs are usually negative with the caveat that throwing athletes may have medial traction spurs and medial collateral ligament calcification visible on plain x-ray. The pain of medial epicondylitis is exacerbated by resisted forearm pronation or wrist flexion. Ranges of motion at the elbow and wrist are usually complete. Should decreased sensitivity in the 4th and 5th fingers be found, a diagnosis of ulnar neuropathy may be present. This may be confirmed by nerve conduction study and/or electromyography. Additionally, the elbow flexion test (maximum elbow flexion with wrist extension for three minutes) may produce pain and numbness if ulnar neuropathy is present, but will likely be negative in medial epicondylitis.7
Intra-articular pathology must be suspected when a painful clicking is palpated and/or heard at the end of forearm supination. Additionally, tenderness of the posterior radiocapitellar joint demands consideration of intra-articular pathology.6,7
When considering cervical radiculopathy, one must rule out peripheral nociceptive causes for pain as in the other etiologies mentioned above. With classical cervical radiculopathy, one expects to find pain, sensory loss, and motor weakness, all concordant with the suspected affected nerve root. Specifically, peripheral motions of the elbow while keeping the neck and shoulder neutral should not ordinarily elicit pain.8 Here, pain is typically dysesthetic with abnormal sensation, whereas the other conditions listed above typically produce “dull,” “aching,” and “cramping” pain.6,7
If elbow pain is the result of overuse as a compensatory mechanism, the provider may find an ipsilateral frozen shoulder, or alternatively a shoulder whose range of motion is significantly decreased in one or more planes. In these cases elbow pain is likely to continue regardless of treatment directed at the elbow until the shoulder pathology is identified and addressed.9
The anconeus muscle is found just lateral of the olecranon process and assists with extension of the elbow. Occasionally inflammation of this muscle can contribute to and confound the diagnosis of elbow pain. One study identified that many patients diagnosed with lateral epicondylitis also had high signal intensity on MRI suggestive of edema and granulation tissue in the anconeus muscle.10,9
Lastly, infection and inflammatory or degenerative arthritis must also be considered before making a diagnosis of lateral or medial epicondylitis. Historical clues such as fever, malaise, history of skin breakdown or environmental exposure, and/or serological studies (ex: Erythrocyte Sedimentation Rate, Lyme, Rheumatoid Factor, etc.) may all be appropriate where clinically indicated.9
ELBOW PAIN DIAGNOSIS
Lateral Epicondylitis (AKA: tennis elbow): has an annual prevalence of one to two percent in the general public, and accounts for seven percent of all sports injuries, being the most common sports-related problem at the elbow. Predisposing factors include high tension on the racket strings, improper-sized grip, and leading the backhand with the elbow. It is also seen in computer users from repetitive wrist extension for keyboard use.11
The lateral humeral epicondyle serves as the bony common origin of the wrist extensors. Injury to the extensor carpi radialis brevis muscle (ECRB, which can be felt at the tip of lateral epicondyle) and occasionally, the extensor digitorum communis muscle (EDC, which can be felt just posterior and distal to tip of lateral epicondyle) institutes lateral epicondylitis.11
Provocative testing is done by performing the Cozen’s test. During this test, the patient’s elbow is stabilized by the examiner’s thumb, which rests on the patient’s lateral epicondyle. The patient is then asked to make a fist, pronate the forearm, and radially deviate and extend the wrist while the examiner resists the motion. A positive sign is indicated by a sudden severe pain in the area of the lateral epicondyle of the humerus. Tenderness is present over the lateral epicondyle approximately 5mm distal and anterior to the midpoint of the condyle.1,11
Medial Epicondylitis (AKA: golfer’s elbow): can be found in athletes and in workers performing occupations that demand repetitive wrist flexion activities. It is a tendinopathy of the common flexor tendon, usually the flexor carpi radialis and the pronator teres.12
Medial epicondylitis is less common than lateral epicondylitis, with a reported prevalence less than one percent in the general population, but as high as six percent in some professions. In throwing athletes, particularly baseball players, the elbow’s medial structures endure the most stress and account for up to 97 percent of all elbow injuries.4,12,3
Provocative testing is performed by having the examiner supinate the forearm and extend the elbow and wrist, while palpating the patient’s medial epicondyle. A positive test is indicated by pain over the medial epicondyle of the humerus. The point of maximal tenderness is usually at the insertion of the flexor-pronator mass, 5 to 10mm distal and anterior to the medial epicondyle.3
Elbow Bursitis: A bursa is a fluid-filled, saclike structure lined by synovial membrane that forms in clefts between mobile structures in the musculoskeletal system. The olecranon bursa, located posteriorly over the olecranon process of the ulna, may become swollen in relation to trauma, hemorrhage, sepsis, or any inflammatory arthritis. It is also a common site for the development of rheumatoid nodules or gouty tophi. Due to its superficial location, swelling of the olecranon bursa is easy to detect by both the patient and the examiner. It may be readily distinguishable from an effusion of the elbow joint if the patient is able to fully extend the elbow joint without accentuating the pain.13,5
Ulnar Collateral ligament (UCL) sprain: Injuries to the UCL of the elbow are a result of valgus stress to the elbow. This can be caused by a single traumatic episode, but is frequently seen with repetitive micro-trauma associated with throwing. The late cocking phase of overhead throwing is characterized by a valgus torque of approximately 64 N-m across the elbow. During the acceleration phase of overhead throwing, the valgus forces across the elbow are increased, leading to further stress on the UCL.5
Patients usually complain of medial elbow pain exacerbated by the later cocking and acceleration phases of throwing. If the injury was acute, an audible pop might have been heard. Physical examination shows a 5-degree elbow flexion contracture, UCL tenderness, and pain with or without laxity during UCL instability testing.5,2
Provocative testing is done by having the patient’s arm stabilized with one of the examiner’s hands at the elbow and the other hand placed above the patient’s wrist. With the patient’s elbow slightly flexed (20-30 degrees) and stabilized by the examiner’s hand, an abduction or valgus force at the distal forearm is applied by the examiner to test the medial collateral ligament. The examiner should note any laxity, decreased mobility, or altered pain that may be present compared with the uninvolved elbow.5,2,3
Little League Elbow Sprain: this term is used to describe a group of elbow problems related to the stress of throwing in young athletes. Throwing can cause medial symptoms as well as lateral and posterior symptoms. The medial symptoms are related to the repetitive valgus distraction forces on the medial elbow. Micro-trauma from overuse or improper throwing mechanics (opening up too soon so the throwing arm trails behind the trunk rotation) can cause injury. The skeletal maturity of the athlete affects the type of injury.12
Cubital Tunnel Syndrome: Ulnar neuropathy at the elbow is a common focal neuropathy affecting the upper extremity. The ulnar nerve travels within the retrocondylar groove of the elbow, posteromedial to the medial epicondyle. As the nerve exits the groove it passes under that aponeurotic arch of the flexor carpi ulnaris muscles, also called the humeroulnar arcade, which is formed by attachments of this muscle to the medial epicondyle and olecranon. The proximal edge of the arcade lies about 1-2cm distal to a line join joining the medial epicondyle and olecranon. This is an important structure clinically because it is often implicated as the cause of compressive ulnar neuropathy at the elbow.1
As a result, entrapment under the humeroulnar arcade became known as the cubital tunnel syndrome. Ulnar nerve is derived from the anterior rami of the C8 and T1 spinal nerves. Ulnar neuropathy at the elbow (UNE) typically presents with numbness and tingling in the fourth and fifth digits, elbow pain, nocturnal awakenings, and worsening of symptoms with elbow and repeated wrist flexion. Sensory symptoms from UNE are often brought on by sustained elbow flexion (e.g., when talking on the phone or lying on one’s side with elbow flexed). Motor symptoms in UNE are overall less common than sensory symptoms, but range from mild weakness of intrinsic hand muscles to severe wasting and claw hand deformity.14,5
Provocative testing is done by performing the Tinel test at the elbow. It is performed by firm percussion over the ulnar nerve in the ulnar groove and a bit further distally over the cubital tunnel. This test is considered positive when it results in paresthesia or pain in ulnar-innervated regions of the hand, particularly the fourth and fifth digits.14,5,11
Radial Tunnel Syndrome and posterior interosseous nerve syndrome (PIN): There is some controversy about whether radial tunnel syndrome and posterior interosseous nerve syndrome are two separate entities or a continuum of the same condition.5
The radial tunnel is 5cm in length, from the level of the radiocapitellar joint, extending distally past the proximal edge of the supinator. Laterally it is bounded by brachioradialis, ECRL (extensor carpi radialis longus), and ECRB (extensor carpi radialis brevis). Medially is bounded by biceps tendon and brachialis, with the capsule of the radiocapitellar joint making up the floor of the tunnel. As the radial nerve enters the antecubital fossa laterally, it divides into the posterior interosseous branch and the superficial radial nerve.1
Radial tunnel syndrome occurs because of compression of the superficial radial nerve by structures in or near the radial tunnel, including the ECRB and brachioradialis. It may be caused by repetitive pronation and supination, direct trauma, or bony lesion of the radial head. Complaints include deep, dull ache distal to the lateral epicondyle that may be worse at night. Weakness and sensory changes are uncommon. Physical examination typically reveals a positive Tinel sign at the radial tunnel.15,5
Posterior interosseous nerve syndrome (PINS) occur from irritation of the nerve at it passes between the two supinator heads in the arcade or canal of Frohse, a fibrous arch in the supinator muscle occurring in 30 percent of the population. In PINS, physical exam demonstrates lateral elbow pain, usually distal to the lateral epicondyle, and weakness in the wrist, thumb, and finger extensors. There are usually no sensory deficits. The presence of weakness with resisted supination of the forearm and extension of the middle finger (middle finger test) is common with posterior interosseous nerve syndrome.1,15,5
Anterior interosseous neuropathy: The anterior interosseous nerve branches off from the median nerve in the region of the elbow. It then descends the anterior forearm, innervating several muscles including the flexor pollicis longus, the deep flexor of digits 2 and 3, and pronator quadratus. It does not provide cutaneous sensation; therefore, nerve dysfunction is characterized by weakness of this group of muscles only.1,5
Proactive testing includes the pinch grip test, where the patient is asked to pinch the tips of the index finger and thumb together. Normally there should be a tip-to-tip pinch. If the patient is unable to pinch tip to tip and instead has an abnormal pulp-to-pulp pinch of the index finger and thumb, the test is indicative of a positive sign for pathology to the anterior interosseous nerve. Typically, the nerve gets entrapped as it passes between the two heads of the pronator teres muscle.1,15
Pronator teres syndrome: Entrapment of the median nerve occasionally occurs in the proximal forearm at the site where the nerve passes through the pronator teres muscle. This syndrome generally occurs in physically active people such as professional bicycle riders and is rare. During provocative testing, the patient is asked to flex the elbow to 90 degrees. The examiner strongly resists pronation as the elbow is extended. A positive test is indicated by tingling or paresthesia in the median nerve distribution of the forearm and hand.1,5,15
Cervical Radiculopathy: a radiculopathy is a pathologic process affecting the nerve roots. Signs and symptoms of cervical radiculopathy include myotomal weakness, paresthesias, sensory disturbances, and depressed muscle stretch reflexes. Cervical nerve root injury is most commonly caused by cervical intervertebral disk herniation, with spondylitic spinal changes the next most common cause. Some causes of non-compressive radiculopathy include infection (especially herpes zoster and lyme disease), nerve root infarction infiltration by tumor, and demyelination. Patients typically report history of axial cervical pain that is then followed by explosive onset of upper limb pain.5 Lower cervical roots, particularly C7, are more frequently affected by nerve root compression than higher cervical roots. Provocative maneuvers such as neuroforaminal closure and root tension signs help localize lesion to the cervical spine. Spurling’s maneuver, cervical extension, lateral flexion, and ipsilateral axial rotation reproducing radicular symptoms are highly specific for cervical radiculopathy.5,15
Brachial Plexopathy: the brachial plexus is a network of nerve fusions and divisions that originate from cervical and upper thoracic nerve roots and terminate as named nerves that innervate muscles and skin of the shoulder and arm. Most brachial plexus disorders show a regional involvement rather than involving the entire plexus. The pathologic changes seen with brachial plexus lesions vary with the underlying cause, which include compression, transection, ischemia, inflammation, metabolic abnormalities, and radiation therapy.16 The onset of symptoms may vary from acute to insidious. Acute onset is characterized by pain in the shoulder or upper arm, while insidious onset can manifest as progressive pain, evolving numbness, or weakness of selected muscles. Clinical signs of brachial plexopathy include muscle weakness, atrophy, and sensory loss. Traumatic injuries are the most common cause of brachial plexus lesions in children and adults. Non-traumatic brachial plexopathies include neoplastic and radiation induced plexopathy, brachial plexopathy related to diabetes, inflammatory process (Parsnage Turner’s Sydrome), and thoracic outlet syndrome.16,5
Thoracic outlet syndrome (TOS): The thoracic outlet is bounded by bony structures of the spinal column, first ribs, and sternum. Compromise of the neurovascular structures that traverse the thoracic outlet occurs in three distinct spaces: the scalene triangle, the costoclavicular space, and the pectoralis minor space.17
The scalene triangle is formed by the anterior scalene muscle, the middle scalene, and the superior border of the first rib. Cervical ribs and anomalous first ribs may compress the scalene triangle. It is the space most commonly involved in TOS and is the most common site of brachial plexus compression.17 The Costoclavicular space comprises the area between the first rib and the clavicle. The subclavian vein is most likely to be compressed at this site.17 Pectoralis minor space is bounded by the pectoralis minor muscle anteriorly and the chest wall posteriorly.17
Distinct terms are used to describe the predominantly affected structure, including neurogenic (nTOS) from brachial plexus compression, venous (vTOS) from subclavian vein compression, and arterial (aTOS) from subclavian artery compression. nTOS accounts for more than 95 percent of cases of TOS.17,5,8
A thorough physical examination that includes a complete neurologic and vascular examination should be performed. The clinical manifestations, diagnosis, and approach to management of each type of TOS are unique, reflecting compression of a specific structure. Since we are concerned mainly in this discussion with diagnoses that mimic pain due to elbow joint pathology, will mainly focus on neurogenic TOS symptoms. nTOS include progressive unilateral atrophic weakness of intrinsic hand muscles and numbness in the distribution of the ulnar nerve, with occasional numbness of the ulnar aspect of the forearm. The motor involvement is much greater than the sensory involvement.
Weakness and atrophy involve the thenar eminence more than the ulnar-innervated hand intrinsic muscles, while medial forearm muscles are less involved.16,17
Part 2 of this article, to appear in the October edition, reviews diagnostic tets and treatment options.
Madouna Hanna, DO is in the Department of Physical Medicine and Rehabilitation at Hofstra North Shore - LIJ School of Medicine
Kevin Trinh, MD is in the Department of Physical Medicine and Rehabilitation at Hofstra North Shore - LIJ School of Medicine
Gerard DeGregoris III, MD is the Director of Education and Research at Manhattan Spine and Pain Medicine, New York, New York and is an Attending Physician in the Department of Anesthesia at North Shore- LIJ, Lenox Hill Hospital, New York, New York
Pierce J. Ferriter, MD is an Attending Physician in the Department of Orthopedic Surgery at Hofstra North Shore- LIJ School of Medicine, Lenox Hill Hospital, New York
Steven Mandel, MD is Clinical Professor of Neurology at Hofstra North Shore- LIJ School of Medicine, Lenox Hill Hospital, New York, New York and an Adjunct Clinical Professor of Medicine in the Division of Neurology at New York Medical College, New York
Steven Mandel, MD is Clinical Professor of Neurology at Hofstra North Shore- LIJ School of Medicine, Lenox Hill Hospital, New York, New York and an Adjunct Clinical Professor of Medicine in the Division of Neurology at New York Medical College, New York, NY
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