Osseous Structures

The elbow joint complex includes the humerus, radius, and ulna articulating together in concert to form four joints: the humeroulnar joint, the humeroradial joint, the proximal radioulnar joint, and the distal radioulnar joint ( Fig. 13-1 ).

Osseous structures of the elbow.

The humeroulnar joint is generally considered a uniaxial, diarthrodial joint with 1° of freedom. It allows flexion and extension in the sagittal plane around a coronal axis. Morrey described the humeroulnar joint as a modified hinge joint because of the small amounts of internal and external rotation that occur in the extreme end ranges of both flexion and extension. The anterior aspect of the distal end of the humerus is composed of the convex trochlea. It is an hourglass-shaped surface covered with articular cartilage. The trochlear groove is located centrally within the trochlea and runs obliquely in an anterior to posterior direction. The distal end of the humerus is typically rotated 30° anteriorly with respect to the long axis of the humerus. Correspondingly, the proximal end of the ulna is normally rotated 30° posteriorly with respect to the shaft of the ulna. This paired anatomic rotation of the humerus and ulna ensures the availability of end-range elbow flexion to approximately 145° to 150°. It also serves to enhance the static stability of the elbow complex in full extension.

The proximal end of the ulna contains a central ridge that runs between two bony prominences, the coronoid process anteriorly and the olecranon posteriorly. Two fossas are located on each side of the corresponding articular surfaces of the humerus. Anteriorly, the coronoid fossa articulates with the coronoid process of the ulna during flexion. Posteriorly, the olecranon fossa receives the olecranon process of the ulna, which serves to limit extension. The congruency achieved via these articulations makes the humeroulnar joint one of the most stable joints in the human body.

The medial epicondyle of the humerus also contributes significantly to the humeroulnar joint. Located proximal and medial to the trochlea, it serves as the site of origin for the flexor-pronator muscle group and the ulnar collateral ligament (UCL). Hoppenfeld noted that both the size and prominence of the medial epicondyle provide an important mechanical advantage for the medial stabilizing structures of the elbow joint. The cubital tunnel is located posterior to the medial epicondyle and functions to protect the ulnar nerve as it traverses distally across the elbow joint complex.

Similarly, the humeroradial joint is a diarthrodial, uniaxial joint that allows elbow flexion and extension along with the humeroulnar joint. The humeroradial joint also pivots around a longitudinal axis to allow rotational movements in association with the proximal radioulnar joint, thus making the joint a combination hinge and pivot joint.

The articular surfaces of the humeroradial joint include the concave radial head and the spherical convex capitellum at the distal end of the humerus. The capitellum and trochlea are separated by a groove within the humerus, the capitulotrochlear groove. This groove guides the radial head as the elbow flexes and extends.

Immediately proximal to the capitellum on the anterior aspect of the humerus is the radial fossa. It receives the anterior aspect of the radial head when the elbow is in a maximally flexed position. The lateral epicondyle of the humerus lies just lateral to the radial fossa. It serves as the site of origin for the wrist extensor muscle group. The radial tuberosity is located on the radius just distal to the radial head. It is the attachment site for the distal biceps brachii tendon.

The proximal and distal radioulnar joints are intimately related from a functional standpoint. Together they allow 1° of freedom in the transverse plane around a longitudinal axis, which facilitates forearm supination and pronation. During these motions the head of the radius rotates within a ring formed by the annular ligament and the radial notch of the ulna. Little motion actually occurs in the ulna. The radius and ulna lie parallel to each other when the forearm is in a pronated position. As the forearm rotates into supination, the radius crosses over the ulna. The radius and ulna are connected midway between the two bony shafts by an interosseous membrane, which serves as an additional attachment site for the forearm musculature.

Functionally, the bony articulation of the elbow joint forms the carrying angle of the elbow. This is defined as the angle formed by the long axis of the humerus and the ulna. It normally results in an abducted position of the forearm in relation to the humerus. The carrying angle is measured in the frontal plane with the elbow extended and averages 11° to 14° in males and 13° to 16° in females. The carrying angle changes linearly as the elbow joint is flexed and extended, diminishing in flexion and increasing with extension.

Capsuloligamentous Structures

The joint capsule is a relatively thin but strong structure that derives significant strength from its transverse and obliquely oriented fibrous bands. The posterior portion of the capsule is a thin transparent structure that allows visualization of the bony prominences when the elbow is fully extended. The posterior capsule originates just above the olecranon fossa and inserts distally along the medial and lateral margins of the trochlea. The anterior capsule originates proximally above the coronoid and radial fossas and attaches distally at the anterior margin of the coronoid medially and into the annular ligament laterally. The anterior capsule is taut as the elbow is extended and lax in flexion. The greatest capsular laxity occurs at approximately 80° of elbow flexion. A synovial membrane lines the joint capsule and is attached anteriorly above the radial and coronoid fossas to the medial and lateral margins of the articular surface and posteriorly to the superior margin of the olecranon fossa.

The ligaments of the elbow consist of thickened parts of the medial and lateral portions of the capsule. The UCL is located on the medial aspect of the elbow. This ligamentous complex can be divided into three distinct components: the anterior, posterior, and transverse bundles ( Fig. 13-2, A ). The anterior bundle originates from the inferior surface of the medial epicondyle and inserts at the medial aspect of the coronoid process. Because of the posterior orientation of this portion of the ligament in relation to the center of rotation of the elbow joint, the anterior bundle is taut throughout elbow ROM. The anterior bundle can be further divided into two bands: the anterior band, which is taut in extension, and the posterior band, which tightens in flexion. The anterior bundle of the UCL provides the main ligamentous support to resist valgus strain at the elbow.

Medial ( A ) and lateral ( B ) capsuloligamentous structures.

The posterior bundle originates from the posteroinferior medial epicondyle and fans out to attach onto the posteromedial aspect of the olecranon. The transverse bundle of the UCL originates from the medial olecranon and inserts into the coronoid process. Several authors have reported that these two bundles provide minimal amounts of medial elbow stability.

Laterally, the ligamentous complex helps stabilize the elbow against varus stress. It is made up of several components, including the radial collateral ligament, the annular ligament, the accessory lateral collateral ligament, and the lateral ulnar collateral ligament.

The characteristics of the radial collateral ligament are not as well defined as those of the UCL. Originating from the lateral epicondyle, the radial collateral ligament fans out and inserts into the annular ligament ( Fig. 13-2, B ). The origin of the radial collateral ligament is in line with the axis of elbow joint rotation, which allows little change in length as the elbow moves through its full ROM.

The annular ligament is a strong fibroosseous ring that encircles and stabilizes the radial head within the radial notch of the ulna. Its origin and insertion occur along the anterior and posterior radial notch of the ulna. The anterior portion of this ligament becomes taut with supination, whereas the posterior portion becomes taut with pronation.

The accessory lateral collateral ligament originates from the inferior margin of the annular ligament and inserts discretely into the tubercle of the supinator crest of the ulna. The accessory lateral collateral ligament further assists the annular ligament in varus stabilization of the elbow joint complex.

The lateral ulnar collateral ligament originates from the lateral epicondyle and inserts into the tubercle of the crest of the supinator. This ligament provides posterolateral stability for the humeroulnar joint.

The elbow joint is one of the most congruent joints in the human body and therefore is also one of its most stable. Stability is provided by the interaction of soft tissue and articular constraints. The static soft tissue stabilizers include the capsular and ligamentous structures. Table 13-1 summarizes the stabilizing influences of the ligamentous and articular components of the elbow joint. When the elbow is in full extension, the anterior capsule provides approximately 70% of the restraint to joint distraction, whereas the UCL provides approximately 78% of the resistance to distractive forces at 90° of elbow flexion. The restraint to valgus displacement varies significantly, depending on the angle of elbow flexion. When the elbow is in full extension, the capsule provides 38% of the valgus restraint, the UCL provides 31%, and the osseous articulations provide the remaining 31%. Conversely, at 90° of elbow flexion, the primary restraint to valgus force is the UCL, which provides 54% of the restraint, followed by the osseous articulation (33%) and the capsule (13%). Varus stress is controlled in extension by the joint articulation (54%), lateral collateral ligament (14%), and joint capsule (32%). As the elbow flexes, the lateral collateral ligament and capsule contribute 9% and 13%, respectively, and the joint articulation provides 75% of the stabilizing force against varus stress.

Musculotendinous Structures

The elbow joint musculature can be divided into six groups based on their functions: the elbow flexors, extensors, flexor-pronators, extensor-supinators, primary pronators, and primary supinators.

The three primary flexor muscles of the elbow are the biceps brachii, the brachioradialis, and the brachialis. The biceps brachii typically consists of a long and short head. The long head of the biceps brachii originates on the superior glenoid and glenoid labrum. It passes directly through the glenohumeral joint capsule and the intertubercular groove of the humerus until it joins with the short head of the biceps brachii. The short head of the biceps originates from the coracoid process of the scapula. The two heads join to form a common attachment onto the posterior portion of the radial tuberosity and via the bicipital aponeurosis, which attaches to the anterior capsule of the elbow joint. The biceps is responsible for the vast majority of elbow flexion strength when the forearm is supinated and generates its highest torque values when the elbow is positioned between 80° and 100° of flexion. The biceps also acts secondarily as a supinator of the forearm, principally when the elbow is in a flexed position.

The brachialis muscle originates from the lower half of the anterior surface of the humerus. It extends distally to cross the anterior aspect of the elbow joint and inserts into both the ulnar tuberosity and the coronoid process. The brachialis muscle is active in flexing the elbow in all positions of forearm rotation.

The brachioradialis muscle originates from the proximal two thirds of the lateral supracondylar ridge of the humerus and along the lateral intermuscular septum just distal to the spiral groove. It inserts into the lateral aspect of the base of the styloid process of the radius. The muscular insertion of the brachioradialis is at a significant distance from the joint axis and therefore exhibits a substantial mechanical advantage as an elbow flexor.

The triceps brachii and anconeus muscles serve as the primary extensors of the elbow. The triceps brachii is a large three-headed (long, lateral, and medial) muscle that encompasses almost the entire posterior portion of the brachium. The long head of the triceps originates from the infraglenoid tubercle, whereas the lateral and medial heads originate from the posterior and lateral aspects of the humerus. At the distal end of the humerus, the three heads converge to form a common muscle that inserts into the posterior surface of the olecranon.

The small anconeus muscle originates from a broad area on the posterior aspect of the lateral epicondyle and inserts into the olecranon. The anconeus muscle covers the lateral portion of the annular ligament, the radial head, and the posterior surface of the proximal end of the ulna. Electromyographic (EMG) activity of the anconeus muscle during the early phases of elbow extension has been noted, and this muscle appears to play a stabilizing role during both pronation and supination movements.

The flexor-pronator muscles include the pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis. All these muscles originate completely or in part from the medial epicondyle and serve secondary roles as elbow flexors. Their primary roles are associated with movements of the wrist and hand. This muscle group may provide a limited amount of dynamic stability to the medial aspect of the elbow in resisting valgus stress.

The extensor-supinator muscles include the brachioradialis, extensor carpi radialis brevis and longus, supinator, extensor digitorum, extensor carpi ulnaris, and extensor digiti minimi muscles. Each muscle originates near or directly from the lateral epicondyle of the humerus. Like the flexor-pronators, the primary functions of the extensor-supinator muscles involve the wrist and hand. They also provide dynamic support over the lateral aspect of the elbow. Both this muscle group and the flexor-pronator musculature are susceptible to various overuse conditions and muscular strains.

The pronator quadratus and pronator teres muscles act on the radioulnar joints to produce pronation. The pronator quadratus originates from the anterior surface of the lower part of the ulna and inserts at the distal and lateral border of the radius. The pronator quadratus acts as a significant pronator in all elbow and forearm positions. The pronator teres, which possesses both humeral and ulnar heads, originates from the medial epicondyle and coronoid process of the ulna. The two heads join together and insert along the middle of the lateral surface of the radius. The pronator teres is a strong forearm pronator. It generates its highest contractile force during rapid or resisted pronation. However, the contribution of the pronator teres to pronation strength diminishes when the elbow is positioned in full extension. The flexor carpi radialis and brachioradialis also act as secondary pronators.

The biceps brachii and the supinator muscles are the primary supinators of the forearm, whereas the brachioradialis acts as an accessory supinator. The supinator muscle originates from three separate locations: (1) the lateral epicondyle, (2) the proximal anterior crest and depression of the ulna distal to the radial notch, and (3) the radial collateral and annular ligaments. The supinator muscle then winds around the radius and insert into the dorsal and lateral surfaces of the proximal end of the radius. The supinator, though a significant supinator of the forearm, generally appears to be weaker than the biceps. The supinator acts alone during unresisted slow supination in all elbow and forearm positions and during unresisted fast supination with the elbow extended. The effectiveness of the supinator is not altered by elbow position; however, elbow position does significantly affect the biceps. Because the supinator originates at the radial collateral and annular ligaments, it may also act as a supportive or stabilizing muscle for the lateral aspect of the elbow.

Neurologic Structures

The four nerves that play significant roles in normal elbow function are the median, ulnar, radial, and musculocutaneous nerves. Table 13-2 shows the effect of injury to each of these peripheral nerves.

The median nerve arises from branches of the lateral and medial cords of the brachial plexus. Nerve root levels include C5 to C8 and T1. This nerve proceeds distally over the anterior brachium and continues to the medial aspect of the antecubital fossa. From the fossa, the nerve continues its course under the bicipital aponeurosis and passes most often between the two heads of the pronator teres. The median nerve can be compressed between these two heads or by the bicipital aponeurosis, which results in either pronator or anterior interosseous syndrome. Although relatively uncommon, highly repetitive and strenuous pronation movements of the forearm can also lead to entrapment of the median nerve.

The ulnar nerve emanates from the C8 and T1 nerve root levels and descends into the proximal aspect of the upper extremity from the medial cord of the brachial plexus. The ulnar nerve passes from the anterior to the posterior compartments of the brachium through the arcade of Struthers. This arcade represents a fascial bridging between the medial head of the triceps and the medial intermuscular septum. The nerve continues distally, passing behind the medial epicondyle and through the cubital tunnel. At the cubital tunnel, the bony anatomy provides little protection for the nerve ( Fig. 13-3 ). Ulnar nerve injury, which can be caused by compression or stretching, takes place most often in the cubital tunnel. The cubital tunnel retinaculum flattens with elbow flexion, thus decreasing the overall capacity within the cubital tunnel. This can be noted clinically when nerve symptoms are reproduced during elbow flexion, which typically occurs when osteophytes are present on the ulna or medial epicondyle. Injury to the medial capsular ligaments can result in increased traction forces on the medial portion of the elbow and cause a change in length of the ulnar nerve. This change in length may result in neuropathy or ulnar nerve subluxation. The nerve enters the forearm by passing between the two heads of the flexor carpi ulnaris and continues distally between the flexor digitorum profundus and flexor carpi ulnaris.

Ulnar nerve.

The radial nerve originates from the posterior cord of the brachial plexus and derives its nerve supply from the C6, C7, and C8 nerve root levels, with variable contributions from the C5 and T11 nerve root levels. At the midpoint of the brachium, the radial nerve descends laterally through the radial groove of the humerus and continues its course in a lateral and distal direction. The nerve descends anteriorly behind the brachioradialis and brachialis muscles to the level of the elbow, where it divides into its posterior interosseous and superficial radial branches.

The musculocutaneous nerve originates from the lateral cord of the brachial plexus at nerve root levels C5 to C7. The nerve passes between the biceps and brachialis muscles and pierces the brachial fascia lateral to the biceps tendon. The nerve continues distally and terminates as the lateral antebrachial cutaneous nerve, which provides sensation over the anterolateral aspect of the forearm. Compression between the biceps tendon and the brachialis fascia can cause entrapment of the musculocutaneous nerve.

Sensory nerves innervate the elbow cutaneously and are derived from specific nerve root levels. The lateral aspect of the arm is innervated by branches of the axillary nerve of the C5 nerve root level, whereas the lateral aspect of the forearm is innervated by the musculocutaneous nerve of the C6 nerve root level. The medial aspect of the arm is innervated by the brachial cutaneous nerve from the T1 nerve root level, and the medial aspect of the forearm is innervated by branches of the antebrachial cutaneous nerve from the C8 nerve root level. The T2 dermatome extends from the axilla to the posteromedial portion of the elbow. The extent of innervation provided by each nerve root is variable, and overlap between dermatome distributions does occur.

Biomechanics of Baseball Pitching

The biomechanics of the elbow during overhead baseball pitching can be broken down into six phases: windup, stride, arm cocking, arm acceleration, arm deceleration, and follow-through. During the windup and stride phases, minimal elbow kinetics and muscle activity are present. As the foot contacts the ground, the elbow is flexed to approximately 85°.

The arm-cocking phase begins as the foot comes into contact with the ground and continues until the point of maximum shoulder external rotation. As the arm moves into external rotation, a varus torque is produced at the elbow to prevent valgus stress. Shortly before maximum external rotation, the elbow is flexed to 95° and a varus torque of approximately 85 Nm is produced. At this critical instant, excessive valgus strain may cause injury to the medial stabilizing structures of the elbow, particularly the UCL. As discussed previously, Morrey and An reported that at this instant the UCL is contributing approximately 54% of the resistance to this valgus strain moment. Assuming that the UCL absorbs 54% of the 85 Nm of valgus strain observed during the arm-cocking phase, 45 Nm of strain would be applied to the UCL in this position, which approaches the maximum load capacity before failure of the UCL ensues.

In addition, as the elbow joint sustains this valgus strain, lateral compression is applied. This may lead to compressive injuries involving the lateral compartment of the elbow as the radial head and humeral capitellum are approximated. Such compression may lead to avascular necrosis, osteochondritis dissecans, osteochondral chip fractures, or any combination of these injuries.

As the arm accelerates from maximal external rotation to ball release, elbow extension velocity peaks at approximately 2500°/sec. As the elbow extends and resists valgus strain simultaneously, the olecranon can impinge against the medial aspect of the trochlear groove and olecranon fossa, which may lead to the formation of a posteromedial osteophyte and loose bodies. This type of compression under valgus stress was described by Wilson et al as valgus extension overload.

As the arm decelerates and continues into the follow-through phase, eccentric contraction of the elbow flexors must control the distractive forces at the elbow joint. Moderate activity of the biceps brachii and brachioradialis has been reported at this time. Muscular activity of the elbow flexors may assist in preventing impingement of the olecranon as the elbow is rapidly extended. The elbow remains in a flexed position of approximately 20° as the arm continues into follow-through. Minimal kinetic and muscular activity at the elbow occurs during this final phase of throwing.

Biomechanics of the Elbow During Tennis

The kinematic and kinetic data during tennis vary depending on the type of stroke; therefore, the biomechanics of the serve and groundstroke will be discussed separately. The overhead serve has been compared with the mechanics of overhead throwing. The elbow has been reported to extend at 1500°/sec and pronate at 347°/sec during the acceleration and deceleration phases of the tennis serve. Morris et al reported that the activity of the triceps and pronator teres during the tennis serve must be high to produce significant racket velocity. Because of this excessive angular velocity, eccentric contraction of the elbow flexors and supinators is critical for prevention of injuries to the elbow during an overhead tennis serve.

During a groundstroke, both the forehand and the backhand—the wrist extensors—are predominantly active as the athlete prepares the racquet for impact. The extensor carpi radialis longus and brevis and the extensor communis muscles are active during both strokes, with the forehand showing additional muscular activity of the biceps brachii and brachioradialis. As the racquet comes into contact with the ball and begins the follow-through, continued activity of the extensor carpi radialis brevis occurs. The backhand produces additional activity of the biceps brachii as the elbow decelerates into extension.

Kelley and Weiland compared the muscular activity of the elbow during the backhand stroke in subjects with and without lateral epicondylitis. The results indicated that the group of subjects exhibiting lateral epicondylitis had a significant increase in EMG activity in the extensor carpi radialis longus and brevis, pronator teres, and flexor carpi radialis. These retrospective findings may have an impact on the explanation of the etiology of lateral epicondylitis.

Biomechanics of the Golf Swing

The biomechanics of the golf swing that pertain to elbow and wrist injuries can be broken down into five phases: backswing, transition, downswing, impact, and follow-through. As the athlete swings the club, both the lead arm and the back arm are susceptible to injuries at various moments during the swing.

The backswing phase produces few injuries in the elbow. As the backswing progresses, the lead wrist pronates, flexes, and deviates radially. The back arm flexes at the elbow and the wrist supinates, extends, and deviates radially. The wrist flexors exhibit minimal EMG activity, whereas the wrist extensors exhibit 33% of the maximum voluntary isometric contraction (MVIC). As the clubhead approaches the top of the backswing, the musculature of the elbow must contract eccentrically to control the clubhead and transition from the backswing to the downswing. This motion places a great deal of stress on the stretched flexor-pronator mass of the back arm.

As the downswing progresses, the wrists must uncoil to produce clubhead speed. The wrists and elbows uncoil and return to the neutral position initially observed at setup to prepare for impact. The downswing is characterized by increased muscular activity of both the wrist extensors and flexors. The wrist extensors exhibit 45% MVIC and the wrist flexors 35% MVIC during the downswing. During impact, the wrist and hands decelerate because of the force of impact. McCarroll and Gioe reported that more than twice as many injuries occur during downswing as during backswing because the elbows and wrists move approximately three times faster during downswing. This deceleration of force places a great deal of strain on the forearm muscles as they attempt to maintain control of the club. The majority of elbow injuries take place during impact as the lateral epicondyle of the lead arm and the medial epicondyle of the back arm are placed under significant strain. The lead elbow extensor mass has been reported to be under even greater stress at impact because of the compressive force of ball impact and divots. At ball contact, wrist flexor activity increases significantly to 91% MVIC. Additionally, the wrist extensors exhibit EMG activity of approximately 58% MVIC.

After impact, the arm continues into follow-through. Minimal injuries occur during this phase. The wrists and hands follow a reverse pattern as that seen during the backswing. The lead arm flexes at the elbow, supinates, extends, and deviates radially at the wrist, whereas the back arm pronates, flexes, and deviates radially at the wrist. During follow-through, the EMG activity of the wrist extensors is approximately 60% to 70% MVIC. The repetitive nature of elbow and wrist motion observed may be responsible for the golfing overuse injuries commonly seen in the forearm musculature.

When the muscular activity patterns of golfers with medial epicondylitis and golfers without injuries are compared, golfers with medial epicondylitis exhibit significantly greater wrist flexor muscle activity during the backswing, transition, and downswing.

History

Before the examination begins, a complete history is imperative. The location, intensity, and duration of pain should be clearly identified. The date and mechanism of injury should be explained thoroughly because this will assist in determining the structures involved. Other subjective information, such as aggravating factors, previous injuries, and primary complaints, should also be recorded to assist in assessment and development of patient-specific treatment and goals.

Observation

The trunk and arms should be completely exposed to provide a full view of the neck, shoulder, and elbow for a comprehensive evaluation. The skin should be evaluated for areas of contusion, ecchymosis, swelling, burns, surgical scars, redness, blanching, petechiae, and venous congestion. The carrying angle of the elbow should also be assessed during this portion of the examination.

Palpation

Palpation of the elbow begins with the identification of specific bony landmarks. The clinician should palpate each to determine whether tenderness or deformity is present.

The medial epicondyle may exhibit tenderness for various reasons, including epicondylitis, muscle strain, and UCL injury. The medial supracondylar ridge should be examined for osteophytes, which may be entrapping the median nerve. The olecranon is easily palpated and is covered by the insertion of the triceps and the olecranon bursa, both of which may be tender in athletes with a pathologic condition. Osseous changes in the posteromedial olecranon may be associated with valgus extension overload in overhead athletes. The ulnar border should also be palpated for stress fractures, which are sometimes present in throwing athletes. The lateral epicondyle is often irritable when palpated if epicondylitis is present. Finally, the radial head lies approximately 2 cm distally from the lateral epicondyle and should be palpated during passive supination and pronation.

When one palpates the soft tissues of the elbow, it is helpful to divide the elbow into four distinct regions: the medial, posterior, lateral, and anterior aspects.

The major structures of the medial aspect of the elbow include the ulnar nerve, the flexor-pronator muscle group, the UCL, and the supracondylar lymph nodes. The clinician should manually determine whether the ulnar nerve is capable of being dislocated from within its bony sulcus. This is done by abducting and externally rotating the shoulder with the athlete in a supine position and the elbow flexed between 20° and 70°. The medial epicondyle should also be palpated to determine tenderness in the flexor-pronator muscle mass or the UCL.

The posterior aspect of the elbow contains the olecranon, which should be palpated for the presence of an inflamed, swollen bursa. The triceps insertion points should also be palpated for tenderness.

Laterally, the wrist extensor group is palpated. The brachioradialis is made prominent by having the patient close the fist, place the forearm in a neutral position, and resist elbow flexion. Resisted wrist flexion allows easy palpation of the extensor carpi radialis longus and brevis.

The anterior structures of the elbow pass through the cubital fossa. From medial to lateral, these structures are the median nerve, brachial artery, and biceps tendon. The biceps can be made prominent by resisted elbow flexion.

Range of Motion

The normal ROM of the elbow is 0° of extension, 140° to 150° of flexion, 80° of pronation, and 80° of supination. Passive ROM is assessed in each direction and is always compared with that on the contralateral side. In addition, the end-feel of movement should be assessed. Normal end-feel of the elbow is different for each movement: elbow extension exhibits a bony end-feel, flexion has a soft tissue approximation, and forearm pronation and supination both have a capsular end-feel.

Muscle Testing

Muscle testing of the elbow musculature begins with the patient seated. The brachialis is tested with the elbow flexed and the forearm pronated. The biceps is tested with the forearm supinated and the shoulder flexed to 45° to 50°. The brachioradialis is tested with the elbow flexed and the wrist in neutral rotation. Triceps extension is performed with the shoulder flexed 90° and the elbow flexed 45° to 90°. Pronation and supination of the elbow are performed with the arm by the side, the elbow flexed 90°, and the wrist in neutral rotation. Resistance is applied at the distal end of the forearm as the patient attempts to rotate in either direction. Wrist extension and flexion are performed with the elbow flexed 30° and the elbow fully extended. Isokinetic testing may also be performed to determine specific objective data on muscular strength, power, and endurance.

Special Tests

Special tests for the elbow joint are used in an attempt to elicit specific pathologic signs or symptoms. Laxity is assessed to evaluate the integrity of the medial and lateral stabilizing structures. Varus and valgus testing may be performed by stabilizing the arm with one hand and applying a fulcrum at the elbow joint with the other. The clinician imparts a varus or valgus stress and notes the amount of gapping and the end-feel of motion. The tests are conducted bilaterally and may be performed at 0° of extension and 30° of flexion. Pain, excessive gapping, or a soft end-feel may all indicate a pathologic condition of the stabilizing structures.

Several clinical tests are used to test the integrity of the UCL. The two most common techniques are the supine and prone valgus stress tests. In the first, the athlete is positioned supine while the clinician holds the elbow, externally rotates the shoulder, and blocks the upper extremity from further rotation ( Fig. 13-4 ). The UCL is easily palpated in this position. The elbow is tested at 5° and at 25° to 30° of flexion by applying a valgus stress to determine the integrity of the ligament. The amount of opening, or gapping, is assessed, as well as the end-feel of motion. Excessive gapping, a soft end-feel, or localized medial pain may all indicate a UCL injury.

Clinical test for instability of the ulnar collateral ligament in the supine position.

Next, the athlete is placed in the prone position with the involved arm hanging over the edge of the table. The clinician internally rotates the shoulder and stabilizes the elbow and forearm in pronation before placing a valgus stress on the elbow at 5° and at 25° to 30° of flexion ( Fig. 13-5 ). Again, the amount of opening and end-feel are evaluated during the examination. The prone test is preferred by the authors because of its greater capacity for isolating the UCL and minimizing humeral rotation.

Clinical test for instability of the ulnar collateral ligament in the prone position.

The clinical test for valgus extension overload is performed by the clinician grasping the elbow in a flexed position. As the clinician forces the elbow into extension, a valgus stress is simultaneously applied to the elbow. The clinician palpates the posteromedial aspect of the joint for tenderness and crepitation. Pain over the posteromedial portion of the olecranon process signifies a positive test result.

A lateral pivot shift test is used to assess posterolateral rotatory instability of the elbow. Patients who have sustained an elbow dislocation often report a posterolateral rotatory mechanism of injury that is replicated during this test. With the patient supine, the clinician holds the arm over the head with the shoulder in 90° of flexion and maximal external rotation.

The clinician applies a valgus and supination moment while flexing the elbow, which results in the semilunar notch of the ulna being displaced from the trochlea of the humerus. During this maneuver maximal displacement occurs at approximately 40°. This test is often not tolerated by the patient without general anesthesia; however, signs of apprehension during testing indicate a positive clinical test result in an awake athlete.

Neurologic Testing

The deep tendon reflexes that are significant during examination of the elbow are the biceps reflex, brachioradialis reflex, and triceps reflex, which are controlled by the spinal levels C5, C6, and C7, respectively. A slight response is normal, whereas an increased response could signify an upper motor neuron lesion and a decreased response may indicate the presence of a lower motor neuron lesion.

The biceps tendon reflex can be elicited with the elbow relaxed and in a flexed position; the clinician places the thumb over the biceps tendon in the cubital fossa and gently taps the thumb with a reflex hammer. The brachioradialis reflex is elicited by tapping the tendon at the lateral distal end of the radius with the flat edge of a reflex hammer. The triceps tendon reflex is elicited by tapping over the triceps tendon with a reflex hammer.

Sensory perception is assessed by pinprick and light touch of the skin. The contralateral extremity is always used for comparison. The lateral aspect of the arm is innervated by the axillary nerve (C5), and the lateral aspect of the forearm is innervated by branches of the musculocutaneous nerve (C6). The medial aspect of the arm is innervated by the brachial cutaneous nerve (C8), and the medial aspect of the forearm is innervated by the antebrachial cutaneous (T1) nerve.

Plain View Radiographs

Plain view radiographs may be a useful adjunct to the clinical examination. The views routinely taken of an elbow include both an anteroposterior and a lateral view. These views allow the clinician to identify the presence of fractures or loose bodies. Internal and external oblique views may also provide further diagnostic information and are the best views to detect the presence of posterior olecranon osteophytes.

Computed Tomographic Arthrography

A diagnostic arthrogram is extremely useful when a UCL tear is suspected. Contrast dye is injected into the elbow, and radiographs are obtained to determine whether the dye has escaped the capsule through a tear. Complete tears of the UCL will result in a positive arthrogram. A computed tomographic scan, performed immediately after the arthrogram, can enhance visualization of a capsuloligamentous injury.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) may prove to be beneficial in the differential diagnosis of various pathologic elbow conditions. MRI of the elbow is helpful in diagnosing complete UCL tears, particularly when the elbow is injected with saline before testing. A UCL tear is indicated by leakage of dye along the medial side of the elbow both proximally and distally along the medial olecranon. Timmerman and Andrews referred to this finding as a T-sign.

Phase I: Immediate-Motion Phase

The first phase of elbow rehabilitation is the immediate-motion phase. The goals of this phase are to minimize the effects of immobilization, reestablish nonpainful ROM, decrease pain and inflammation, and retard muscular atrophy. The rehabilitation specialist must not overstress healing tissues during this phase.

Early ROM activities are performed to nourish articular cartilage and assist in the synthesis, alignment, and organization of collagen tissue. ROM activities are performed in all planes of elbow and wrist motion to prevent the formation of scar tissue and adhesions. Reestablishing full elbow extension is the primary goal of early ROM activities. These interventions are designed to minimize the development of elbow flexion contractures. The elbow is predisposed to flexion contractures because of the intimate congruency of the joint articulations, the tightness of the joint capsule, and the tendency of adhesions to develop in the anterior capsule after injury. The brachialis muscle also attaches to the capsule and crosses the elbow joint before becoming a tendinous structure. Injury to the elbow may cause excessive scar tissue formation in the brachialis muscle, as well as functional splinting of the elbow.

Grades I and II joint mobilizations may be performed as tolerated during this early phase of rehabilitation. These grades I and II mobilization techniques are used to neuromodulate pain by stimulating type I and type II articular receptors. Posterior glides with oscillations are performed in the midrange of elbow motion to assist in regaining full extension. Aggressive mobilization techniques are not used until the later stages of rehabilitation when the pain has subsided.

If the patient continues to have difficulty achieving full extension during ROM and mobilization techniques, a low-load, long-duration stretch may be performed to produce creep of collagen tissue, which will result in tissue elongation. The authors find this intervention to be extremely beneficial in regaining full elbow extension. The athlete lies supine with a towel roll placed under the brachium to act as a cushion and fulcrum. Light-resistance exercise tubing is applied to the wrist of the patient and secured to the table or to a dumbbell on the ground ( Fig. 13-6 ). The patient is instructed to relax as much as possible for 10 to 12 minutes. The amount of resistance applied should be of low magnitude to enable the athlete to tolerate the stretch for the entire duration without pain or muscle spasm.

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