Articular Injuries in the Athlete

Bone and Cartilage

Elbow anatomy, including the ossification centers and pattern of ossification in the elbow, are discussed in detail in Chapter 2 . Elbow injury patterns in skeletally immature athletes are associated with stages of growth and development, and the skeletal developmental stage defines the weakest link. Childhood terminates with the appearance of all secondary centers of ossification, adolescence terminates with the fusion of all secondary ossification centers, and young adulthood is signified by the completion of skeletal growth. Injuries during childhood are related to the developing epiphyses (see Chapter 25 ). Excessive forces may alter vascularization or ossification. During adolescence, peripheral fragment avulsions, subchondral osteonecrosis, or physeal injury or nonunion may occur. By the time patients reach young adulthood, stress reactions, ligamentous injuries, or capsular injuries become more common. Accessory ossicles are of particular anatomic concern to physicians treating articular injuries. These may occur extraarticularly (medial epicondyle or tip of the olecranon in the triceps tendon) or intraarticularly (olecranon fossa, coronoid fossa, lateral epicondyle ; Figs. 67.1 and 67.2 ). Persistent apophyses at the medial or lateral epicondyle can commonly be confused with loose bodies. Sesamoid fabella cubiti in the biceps tendon, patella cubiti in the triceps tendon, or accessory ossicles such as the supratrochlear posterius in the olecranon fossa or os supratrochlear anterius in the coronoid fossa must also be distinguished from pathologic loose bodies.

Ligaments

Ligamentous anatomy in the elbow region is discussed at length in Chapter 2, Chapter 3, Chapter 68, Chapter 71 . A brief review of their functional anatomy as it relates to articular injuries is presented here. The ulnar collateral ligament (UCL) complex consists of three main portions—anterior band, posterior band, and transverse ligament. The anterior band serves as the primary stabilizer to valgus stress, with the radiocapitellar joint providing secondary stability. Repetitive valgus stresses associated with activities such as throwing generate three well-described forces on the elbow and its articular surfaces ( Fig. 67.3 ) :

• 1

  medial tension

• 2

  lateral compression

• 3

  posterior shear

Microtrauma to the anterior band of the UCL may cause progressive valgus laxity, which causes an alteration of the basic biomechanics of the joint. Shear forces on the olecranon develop, leading to synovitis, osteophytes, and loose bodies in the posterior compartment. Additionally, an increase in compressive forces is transmitted to the radiocapitellar joint. Fragmentation and/or loose bodies may result. These changes in elbow articulation may result in well-described clinical findings, such as increased valgus-carrying angle, flexion contractures, medial epicondyle hypertrophy or fragmentation, and trochlear or olecranon fragmentation.

History

A detailed history helps narrow the extensive differential diagnosis of elbow pain in athletes ( Table 67.1 ). We find it most helpful to classify injuries by mechanism, with further subclassification based on the anatomic compartment involved (medial, lateral, posterior) and onset of pain (acute, chronic). Pertinent information includes age, sport played, level of competition, position, characterization of pain (location, duration, onset), mechanism of injury, and past medical history. As mentioned above, skeletal age can provide the physician with useful information regarding the likely diagnosis.

Different sports predispose athletes to different injuries. Gymnasts must lock out their elbows to support their body weight, which often leads to posterior elbow injuries. Baseball players, especially pitchers, put large-magnitude valgus stresses on the elbow, which can result in myriad injuries. For pitchers, in particular, effectiveness over their previous outings, number of pitches thrown, types of pitches thrown, phase of throwing associated with the pain, and parent's or coach's observations of any changes in mechanics are pertinent. A detailed knowledge of the phases of throwing will help the treating physician narrow the differential diagnosis of elbow pain in throwers. This is discussed at length in Chapter 66 . It is important to note that the number of pitches thrown and innings pitched may not be the greatest risk factors.

Physical Examination

Bilateral upper extremities should be examined, beginning with inspection to note muscle atrophy or hypertrophy, bony deformities, elbow asymmetry, and/or flexion contractures. Range of motion of both shoulders and elbows is assessed, and carrying angles of the elbows should be compared ( Fig. 67.4 ). Palpation should include the medial and lateral epicondyles, medial and lateral collateral ligaments, sublime tubercle, radial head, and olecranon process. Careful examination of the ulnar nerve may reveal subluxation and/or tenderness. Lateral ligaments are tested with varus stress with the arm internally rotated, whereas medial ligament stability is tested with a valgus stress applied to an externally rotated arm. Special maneuvers used to help diagnose elbow medial collateral ligament (MCL) insufficiency include the moving valgus stress test and milking test, both of which are detailed in Chapters 4 and 66 . Pain with forced hyperextension may suggest hyperextension valgus overload syndrome, whereas mechanical locking or catching may indicate loose bodies or osteochondral defects. In throwing athletes, it may help to have them simulate a pitch to reproduce their symptoms. The examination requires a complete neurologic and vascular assessment, with special attention given to the ulnar nerve.

Imaging

Standard anteroposterior, lateral, and reverse axial views of the affected and contralateral elbow are an essential part of the workup. Stress views may help detect subtle ligamentous instability; however, negative stress films do not rule out ligamentous pathology. Magnetic resonance imaging (MRI) can be used in these cases to evaluate the ligament in question further. Additionally, MRI is helpful for diagnosing osteochondritis dissecans (OCD) lesions, stress fractures, and other soft tissue pathology. Computed tomography (CT) scans are also useful to evaluate loose bodies, bone spurs, and articular cartilage lesions.

Arthroscopy

Arthroscopy of the elbow can facilitate or confirm the diagnosis of articular and ligamentous injuries ( Fig. 67.5 ; see Chapter 20, Chapter 22, Chapter 24 ). For example, OCD lesions can be inspected and probed at arthroscopy, which can help dictate the appropriate treatment, and the arthroscopic valgus stress test can be used to confirm disruption to the medial ulnar collateral ligament. Chapter 20, Chapter 21, Chapter 22, Chapter 23, Chapter 24 detail the expanding role of arthroscopy of the elbow to treat cartilage and synovial lesions in the athlete, such as lateral synovial plicae, loose bodies, OCD lesions, and posterior compartment osteophytes (see Part 2).