Epicondylitis

Populations and Risk Factors

• Age: Peak incidence between 35–55 years; tendon vascularity and collagen quality decline with age, reducing repair capacity
• Sex prevalence: Lateral epicondylitis affects men and women equally in the general population; medial epicondylitis shows slight male predominance due to occupational exposure
• Occupational factors: Repetitive gripping, twisting, and wrist motion — mechanics, plumbers, carpenters, computer workers (lateral); heavy manual labor with gripping and forearm pronation (medial); occupational exposure increases risk 2–7 times compared to sedentary workers
• Athletic exposure: Racquet sports (lateral — improper backhand technique), golf (medial — lead arm during downswing), baseball pitching (medial — valgus stress during acceleration phase), rock climbing, rowing
• Biomechanical factors: Grip strength imbalance, forearm pronator/supinator strength asymmetry, poor proximal kinetic chain mechanics (shoulder and scapular weakness forcing distal compensation)
• Dominant limb: Lateral epicondylitis most commonly affects the dominant arm; dominant limb hypertrophy may be observed on inspection

Causes and Pathophysiology

• Repetitive microtrauma to the common tendon origin: The ECRB (lateral) and pronator teres/flexor carpi radialis (medial) attach at small bony surfaces that concentrate enormous tensile forces during gripping and wrist motion. Each contraction cycle produces microscopic collagen fiber disruption at the teno-osseous junction. When the cumulative rate of microtrauma exceeds the tendon's repair capacity, the condition progresses from acute inflammation to failed healing.
• Acute tendinitis phase (first 2–6 weeks): True inflammatory response with neutrophil and macrophage infiltration, increased vascular permeability, and prostaglandin-mediated pain. The tendon is edematous and irritable. Histologically, inflammatory cells are present. This is the only phase where anti-inflammatory interventions (ice, NSAIDs) address the actual pathology. Clinically, the tendon is warm, swollen, and painful at rest.
• Chronic tendinosis phase (beyond 6–8 weeks): The tendon transitions to a degenerative state. Histological examination reveals: (1) disorganized, immature Type III collagen replacing organized Type I collagen — the tendon loses tensile strength; (2) angiofibroblastic hyperplasia — excessive fibroblast proliferation with disordered matrix production; (3) neovascularization — new blood vessels grow into the degenerative tendon, accompanied by neonerves (new pain-sensing nerve fibers) that explain the persistent pain; (4) absence of traditional inflammatory cells — neutrophils and macrophages are no longer present, which is why anti-inflammatory treatments fail in chronic cases. This is the critical clinical distinction: chronic epicondylitis is a failed healing response, not ongoing inflammation.
• The neovascularization-pain connection: The new blood vessels that grow into degenerative tendon tissue are accompanied by unmyelinated sensory nerve fibers (neonerves). These neonerves contain substance P and calcitonin gene-related peptide (CGRP) — nociceptive neurotransmitters that produce pain without any inflammatory stimulus. This mechanism explains why patients with chronic tendinosis experience significant pain despite no measurable inflammation, and why eccentric loading protocols (which may disrupt neovascular ingrowth) are more effective than anti-inflammatory approaches.
• ECRB vulnerability (lateral): The ECRB is the primary tissue involved because of its anatomical position — its deep surface contacts the lateral edge of the capitellum during forearm pronation and wrist extension, creating a mechanical abrasion zone. Additionally, the ECRB origin is relatively hypovascular compared to adjacent extensors, reducing its repair capacity. This explains why lateral epicondylitis preferentially involves the ECRB rather than the extensor digitorum or extensor carpi ulnaris.
• Common flexor origin vulnerability (medial): The pronator teres and flexor carpi radialis bear the greatest tensile load during power gripping and pronation. The ulnar nerve passes through the cubital tunnel immediately posterior to the medial epicondyle — medial epicondylitis may produce secondary ulnar nerve irritation (cubital tunnel syndrome) through local inflammation and swelling, which is why neurological screening of the ring and little fingers is required in all medial epicondylitis assessments.
• Eccentric loading mechanism: Both lateral and medial epicondylitis are most commonly produced by eccentric loading — the tendon lengthens under tension (e.g., the wrist extensors eccentrically controlling wrist flexion during a backhand stroke, or the wrist flexors eccentrically controlling wrist extension during a golf downswing). Eccentric loads generate 20–40% greater force within the tendon than concentric contractions, which is why eccentric rehabilitation (progressively loading the tendon eccentrically) is the most evidence-supported intervention for chronic tendinosis.

Signs and Symptoms

Acute Tendinitis Presentation (First 2–6 Weeks)

• Pain at the epicondyle during and immediately after aggravating activity
• Local swelling and warmth directly over the epicondyle (may be subtle)
• Pain eases significantly with rest; returns quickly with activity resumption
• Grip strength reduced during painful episodes but recovers between flares
• Morning stiffness that resolves within 30 minutes of gentle use

Chronic Tendinosis Presentation (Beyond 6–8 Weeks)

• Pain that initially "warms up" and decreases during the first few minutes of activity, then returns with greater intensity as activity continues — this warm-up pattern reflects the tendinosis mechanism (neovascular pain decreases temporarily with increased blood flow, then the mechanical loading overwhelms the degenerative tissue)
• Deep, aching, "toothache-like" quality at the epicondyle; may become constant with severe degeneration
• Pain radiating down the forearm toward the wrist along the extensor mass (lateral) or flexor mass (medial)
• Progressive grip weakness — difficulty holding a coffee cup, turning a doorknob, or shaking hands
• Night pain in advanced stages, particularly when the forearm is positioned in a way that stretches the involved tendon
• Crepitus — a gritty, grinding sensation as the degenerative tendon moves, representing disorganized collagen and roughened tendon surface
• No visible swelling or warmth (inflammation is absent in true tendinosis)

Assessment Profile

Subjective Presentation

• Chief complaint: Pain at the outside (lateral) or inside (medial) of the elbow that worsens with gripping, twisting, and lifting activities; patients frequently report difficulty with everyday tasks — opening jars, carrying grocery bags, shaking hands, using a screwdriver
• Pain quality: Sharp with provocative movements (gripping, lifting); dull, aching, and deep at rest in chronic cases; may radiate down the forearm; night pain in advanced tendinosis
• Onset: Insidious in most cases — gradual increase over weeks to months linked to repetitive occupational or recreational activity; acute onset possible with sudden forceful gripping or eccentric overload (e.g., catching a heavy object)
• Aggravating factors: Gripping, wringing, lifting with palm down (lateral), palm up (medial); shaking hands; turning doorknobs; carrying bags; racquet sports, golf; any sustained grip activity
• Easing factors: Rest from aggravating activities; counterforce bracing (reduces tensile load at the origin); warmth during activity in chronic cases (temporarily improves blood flow to the degenerative tendon)
• Red flags: Sudden loss of grip strength without pain → suspect tendon rupture or posterior interosseous nerve (PIN) compression; numbness in the ring and little fingers with medial epicondylitis → suspect concurrent ulnar nerve involvement at the cubital tunnel

Observation

• Local inspection: Usually normal appearance; dominant limb hypertrophy may be visible; no visible swelling in chronic tendinosis; mild swelling may be present in acute tendinitis; check for forearm muscle wasting in chronic severe cases
• Posture: Protective forearm positioning — the client may hold the forearm in pronation with the elbow slightly flexed to reduce tension on the extensor origin (lateral) or in supination to reduce tension on the flexor origin (medial); shoulder and scapular posture should be assessed as proximal kinetic chain dysfunction may contribute
• Gait: Not applicable

Palpation

• Tone: Hypertonic extensor mass (lateral) or flexor-pronator mass (medial) — the entire muscle belly is in protective hypertonicity. Taut bands and trigger points are commonly palpable in the ECRB (lateral) and pronator teres/FCR (medial). Proximal forearm guarding may extend into the brachioradialis and supinator.
• Tenderness: Exquisite point tenderness directly over the lateral epicondyle at the ECRB origin (lateral) or over the medial epicondyle at the common flexor origin (medial). Tenderness extends distally along the muscle-tendon junction for 1-2 cm. In medial epicondylitis, palpate posterior to the medial epicondyle for ulnar nerve tenderness — positive Tinel's sign at this location indicates concurrent cubital tunnel involvement.
• Temperature: Warmth over the epicondyle in acute tendinitis (true inflammatory phase); normal temperature in chronic tendinosis (no active inflammation); this is a clinically useful differentiation — warmth suggests the condition is still in the inflammatory phase where ice and anti-inflammatory approaches are appropriate
• Tissue quality: Acute — tendon feels thickened and edematous at the origin. Chronic — tendon may feel thickened, ropy, and nodular at the teno-osseous junction from the degenerative changes described in Pathophysiology. Crepitus may be palpable with passive wrist motion while palpating the tendon. Reduced fascial mobility in the proximal forearm.

Motion Assessment

• AROM: Pain at the epicondyle during active wrist extension (lateral) or active wrist flexion (medial); full ROM is usually preserved but painful at end-range; grip strength testing (dynamometry) reveals measurable weakness — typically 20–50% reduction compared to the uninvolved side
• PROM / end-feel: Pain at the epicondyle with passive wrist flexion and pronation (lateral — stretches the extensor origin) or passive wrist extension and supination (medial — stretches the flexor origin); end-feel is tissue stretch (elastic) with pain; passive motion is less painful than active because the contractile tissue is not under tension — but stretch on the degenerative origin still reproduces symptoms
• Resisted testing: This is the definitive finding — pain at the epicondyle with resisted wrist extension (lateral) or resisted wrist flexion (medial) with the elbow extended; "strong and painful" = tendinopathy; "weak and painful" = more severe tear or possible neurological involvement; "weak and pain-free" = complete rupture or neurological deficit (PIN compression mimics lateral epicondylitis but produces weakness without epicondylar pain)

Special Test Cluster

If grip weakness is disproportionate to pain: Consider PIN compression (radial tunnel syndrome) as a differential — PIN palsy produces wrist drop and finger extension weakness without epicondylar tenderness. Add ULTT3 and resisted supination testing.

Differential Assessment