Tennis Elbow

Lateral epicondylalgia (tennis elbow) is a degenerative tendinopathy affecting the common extensor tendon origin at the lateral epicondyle, primarily involving the extensor carpi radialis brevis (ECRB) tendon. Despite the name, fewer than 10% of cases occur in tennis players. The condition is characterized by a failed healing response resulting in angiofibroblastic degeneration rather than acute inflammation.

The pathophysiology begins with repetitive mechanical overload of the wrist extensors exceeding the tendon's adaptive capacity. This leads to microtears, disorganized collagen structure, increased ground substance, neovascularization, and neurogenic inflammation. Histologically, the tissue shows angiofibroblastic hyperplasia with absence of inflammatory cells, confirming this is tendinosis rather than tendinitis.

The ECRB is particularly vulnerable due to its anatomical position and biomechanical demands. It originates from a small area on the lateral epicondyle and must generate force across both the elbow and wrist joints. During gripping and wrist extension activities, the ECRB experiences high tensile loads, especially with the elbow extended and forearm pronated - the exact position used during computer work and manual labor.

Neurogenic sensitization occurs in chronic cases, with elevated substance P and calcitonin gene-related peptide in the affected tendons. This contributes to pain amplification and may explain why some cases become recalcitrant to treatment. The condition often coexists with cervical radiculopathy and shoulder dysfunction, as neural and biomechanical factors from proximal regions can perpetuate or exacerbate symptoms.

Risk factors include age 40-50 years (peak incidence), occupations requiring repetitive gripping and wrist extension (construction, manual labor, computer work), poor wrist posture, inadequate forearm strength, and sudden increases in hand-intensive activities. Similar to golfers elbow (medial epicondylalgia), this represents failed tendon healing, though it affects the lateral rather than medial elbow and involves different muscle groups.

The biomechanical drivers of tennis elbow center on repetitive eccentric loading of the wrist extensors during gripping and wrist stabilization tasks. When you grip an object, your wrist extensors must contract to prevent wrist flexion and maintain functional hand position. This creates tensile stress at the lateral epicondyle, particularly when gripping with the elbow extended and forearm pronated.

Computer work represents a major biomechanical stressor. During mouse use, the wrist extensors maintain wrist position against the weight of the hand while performing fine motor control. Hours of repetitive clicking with the wrist extended and deviated places cumulative microtrauma on the ECRB tendon. Keyboard use with wrists resting on pads forces wrist extension, requiring continuous extensor activation. Sustained, high-volume computer use is recognised in the occupational literature as a risk factor for lateral epicondylalgia.

Manual labor and tool use create even higher loads. Using a screwdriver requires forceful gripping combined with wrist stabilization against rotational torque. Hammering involves rapid eccentric loading as the tool decelerates after impact. Painting with a brush or roller demands sustained isometric contraction of wrist extensors to control the implement. Carrying shopping bags with handles or lifting objects with a pronated grip (palm down) maximizes stress on the lateral extensors compared to supinated (palm up) grips.

Sports biomechanics reveal why tennis players get this injury despite representing a minority of cases. During the backhand stroke, especially with poor technique using excessive wrist extension and late contact point, massive eccentric forces load the wrist extensors at ball impact. One-handed backhands create even higher demands than two-handed technique. However, any racquet sport, weightlifting with poor wrist position, or golf can create similar loading patterns.

Poor proximal mechanics amplify distal loading. Weak scapular stabilizers cause compensatory wrist extension during reaching tasks. Limited thoracic rotation forces the wrist and forearm to generate movement that should come from the trunk. Cervical spine dysfunction can alter motor control of the forearm muscles through neural mechanisms. Even something as simple as lifting with your elbow locked out rather than slightly bent dramatically increases the moment arm and stress on the lateral epicondyle.

Grip technique and tool design matter enormously. Larger diameter grips distribute pressure over more surface area, reducing tendon stress compared to thin handles. Powered tools reduce sustained muscle contraction compared to manual tools. Ergonomic modifications like vertical computer mice minimize forearm pronation, while proper desk height prevents excessive wrist extension during typing.