DiagnosticTree/MedialEpicondyle
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{
"model": "bayesian_lr_scoring",
"version": "1.0",
"region_label": "Medial Epicondyle Pain",
"description": "Probabilistic scoring model for medial epicondyle / medial elbow pain. Muscles from T&S Vol.1: Triceps Brachii deep medial head (TrP5, refers directly to the medial epicondyle), and four chest-wall / posterior thorax muscles whose referred pain reaches the medial epicondyle as spillover - Pectoralis Major (sternal section), Pectoralis Minor, Serratus Anterior, and Serratus Posterior Superior. Structural differential from Reece et al. StatPearls 2024 and Chung et al. 2025.",
"thresholds": {
"early_exit_posterior": 0.8,
"early_exit_gap": 0.22,
"pairwise_trigger": 0.15
},
"muscles": {
"triceps_TrP5": {
"label": "Triceps Brachii (deep medial head, TrP5)",
"prior": 0.25,
"page": "Muscle:Triceps_Brachii",
"key_trp_note": "TrP5 lies deep in the medial border of the medial head, just above the medial epicondyle - palpated from an anterior approach with the patient supine and the arm laterally rotated. Medial epicondyle pain extending to the volar 4th/5th digits points to TrP5 rather than the more commonly examined forearm flexors. Resisted wrist flexion is NEGATIVE in TrP5 referral - this distinguishes it from medial epicondylitis.",
"subtitle": "Deep medial-head TrP refers directly to the medial epicondyle; may extend to the volar 4th/5th digits and inner forearm; worse on resisted elbow extension, NOT resisted wrist flexion"
},
"pec_major_sternal": {
"label": "Pectoralis Major (intermediate sternal section)",
"prior": 0.25,
"page": "Muscle:Pectoralis_Major",
"key_trp_note": "The intermediate sternal section refers to the anterior chest and medial arm accenting the medial epicondyle, spilling to the volar forearm and ulnar hand (last 2-2.5 digits). Almost always co-active with pectoralis minor. Left-sided pain mimics angina in exact detail - cardiac status must be established in every patient relieved by TrP treatment. Round-shouldered forward-head posture is the principal perpetuating factor.",
"subtitle": "Anterior chest pain accenting the medial epicondyle, volar forearm, ulnar hand; round-shouldered posture; LEFT-SIDED MIMICS ANGINA - exclude cardiac disease first"
},
"pec_minor": {
"label": "Pectoralis Minor",
"prior": 0.166667,
"page": "Muscle:Pectoralis_Minor",
"key_trp_note": "Almost never active in isolation - one rarely finds active pec minor TrPs without active pec major TrPs. Examine and treat pec major first; pec minor often resolves. Spillover runs along the ulnar arm, elbow, forearm, and palmar hand to the last three fingers. Positive Wright manoeuvre (arm abducted + laterally rotated worsens symptoms) and restricted behind-back reach point to pec minor. Also a cardiac mimic.",
"subtitle": "Anterior deltoid + ulnar arm/elbow/forearm/palmar hand to last 3 fingers; positive Wright manoeuvre; restricts reaching behind back; rarely active without pec major"
},
"serratus_anterior": {
"label": "Serratus Anterior",
"prior": 0.166667,
"page": "Muscle:Serratus_Anterior",
"key_trp_note": "Essential zones are the anterolateral mid-chest and a separate interscapular area medial to the inferior scapular angle; spillover runs down the medial arm to the palm and ring finger. The respiratory symptom complex (air hunger, inability to finish a sentence) and torsional activation (forceful steering-wheel turning) are characteristic. Left-sided pain must never be attributed to myofascial origin until cardiac disease is excluded.",
"subtitle": "Anterolateral mid-chest + interscapular pain, spillover down the medial arm to palm and ring finger; respiratory symptoms (dyspnea, 'can't finish a sentence'); torsional / steering-wheel activation"
},
"serratus_posterior_superior": {
"label": "Serratus Posterior Superior",
"prior": 0.166667,
"page": "Muscle:Serratus_Posterior",
"key_trp_note": "Refers a wide arc from deep under the scapula (inaccessible at rest - the scapula must be fully abducted to palpate) through the posterior arm, with an olecranon accent, continuing to the ulnar forearm and 5th digit. Reaches the medial elbow region via this ulnar spillover. Respiratory overload (chronic cough, paradoxical breathing) is the primary activator. Scalene TrPs are the key driver - always examine the neck.",
"subtitle": "Deep unreachable ache under the scapula -> posterior arm -> olecranon -> ulnar forearm -> 5th digit; respiratory overload history; scapula must be abducted to palpate"
}
},
"questions": [
{
"id": "q_location",
"text": "Where is the pain most concentrated, beyond the medial elbow itself?",
"sublabel": "Choose the dominant location of the overall pain pattern",
"type": "choice",
"answers": [
{
"id": "elbow_and_posterior_arm",
"label": "Medial elbow and the BACK of the upper arm; little or no chest component",
"sublabel": "Pain centres on the posterior arm and medial epicondyle",
"lr": {
"triceps_TrP5": 7.0,
"pec_major_sternal": 0.4,
"pec_minor": 0.4,
"serratus_anterior": 0.4,
"serratus_posterior_superior": 1.5
}
},
{
"id": "anterior_chest",
"label": "Anterior CHEST and front of the shoulder, with the medial elbow as an extension",
"sublabel": "Chest pain is prominent; medial elbow accents the pattern",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 6.5,
"pec_minor": 4.0,
"serratus_anterior": 1.0,
"serratus_posterior_superior": 0.4
}
},
{
"id": "lateral_chest_interscapular",
"label": "Side of the chest AND between the shoulder blades, spreading to the medial arm",
"sublabel": "Anterolateral chest plus interscapular ache",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 0.6,
"pec_minor": 0.6,
"serratus_anterior": 7.5,
"serratus_posterior_superior": 2.0
}
},
{
"id": "deep_scapular",
"label": "Deep UNDER the shoulder blade, running down to the elbow and little finger",
"sublabel": "A deep ache you cannot reach, arcing down the arm",
"lr": {
"triceps_TrP5": 0.5,
"pec_major_sternal": 0.4,
"pec_minor": 0.6,
"serratus_anterior": 1.2,
"serratus_posterior_superior": 7.5
}
}
]
},
{
"id": "q_provocation",
"text": "What most reliably provokes or worsens the pain?",
"sublabel": "Choose the single strongest aggravator",
"type": "choice",
"answers": [
{
"id": "resisted_extension",
"label": "Pushing, press-ups, or straightening the elbow against resistance",
"sublabel": "Forceful elbow EXTENSION (not wrist movement)",
"lr": {
"triceps_TrP5": 7.0,
"pec_major_sternal": 0.4,
"pec_minor": 0.4,
"serratus_anterior": 0.4,
"serratus_posterior_superior": 1.2
}
},
{
"id": "posture_lifting",
"label": "Round-shouldered sitting, reaching forward, or lifting/adduction across the body",
"sublabel": "Sustained pectoral shortening or forward lifting",
"lr": {
"triceps_TrP5": 0.5,
"pec_major_sternal": 6.0,
"pec_minor": 4.5,
"serratus_anterior": 0.7,
"serratus_posterior_superior": 0.6
}
},
{
"id": "respiratory",
"label": "Coughing, deep breathing, running ('stitch'), or after a respiratory illness",
"sublabel": "Respiratory overload",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 0.6,
"pec_minor": 1.0,
"serratus_anterior": 5.5,
"serratus_posterior_superior": 4.0
}
},
{
"id": "torsion",
"label": "Forceful trunk twisting - e.g. wrenching a steering wheel, sudden rotation",
"sublabel": "Torsional load with a fixed arm",
"lr": {
"triceps_TrP5": 0.5,
"pec_major_sternal": 0.6,
"pec_minor": 0.6,
"serratus_anterior": 7.0,
"serratus_posterior_superior": 0.8
}
}
]
},
{
"id": "q_chest_pain_cardiac",
"text": "Is there anterior chest pain, tightness, or constriction - especially on the LEFT?",
"sublabel": "Cardiac mimic screen - pectoral and serratus anterior TrPs reproduce anginal pain in exact detail",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - chest pain / tightness present (CARDIAC DISEASE MUST BE EXCLUDED FIRST)",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 5.0,
"pec_minor": 3.5,
"serratus_anterior": 3.0,
"serratus_posterior_superior": 0.6
}
},
{
"id": "no",
"label": "No - no anterior chest pain or constriction",
"lr": {
"triceps_TrP5": 1.8,
"pec_major_sternal": 0.4,
"pec_minor": 0.7,
"serratus_anterior": 0.7,
"serratus_posterior_superior": 1.5
}
}
]
},
{
"id": "q_referral_hand",
"text": "Does the pain travel into the hand or fingers, and where?",
"sublabel": "Distribution of distal spillover",
"type": "choice",
"answers": [
{
"id": "volar_45",
"label": "Volar (palm) side of the ring and little fingers, with inner forearm",
"sublabel": "Volar 4th/5th digit pattern",
"lr": {
"triceps_TrP5": 5.0,
"pec_major_sternal": 1.5,
"pec_minor": 1.2,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 1.5
}
},
{
"id": "ulnar_last3",
"label": "Ulnar forearm and palm to the last THREE fingers",
"sublabel": "Broader ulnar hand spillover",
"lr": {
"triceps_TrP5": 0.8,
"pec_major_sternal": 4.0,
"pec_minor": 5.0,
"serratus_anterior": 1.0,
"serratus_posterior_superior": 1.5
}
},
{
"id": "palm_ring",
"label": "Down the medial arm to the palm and the ring finger",
"sublabel": "Medial arm to palm / ring finger",
"lr": {
"triceps_TrP5": 0.8,
"pec_major_sternal": 1.0,
"pec_minor": 1.0,
"serratus_anterior": 5.0,
"serratus_posterior_superior": 1.5
}
},
{
"id": "fifth_only",
"label": "Ulnar forearm to the little (5th) finger only",
"sublabel": "5th-digit predominant",
"lr": {
"triceps_TrP5": 1.2,
"pec_major_sternal": 1.0,
"pec_minor": 1.0,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 5.0
}
},
{
"id": "no_hand",
"label": "No hand or finger involvement",
"sublabel": "Pain stops at or above the elbow",
"lr": {
"triceps_TrP5": 1.5,
"pec_major_sternal": 1.0,
"pec_minor": 0.6,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 0.6
}
}
]
},
{
"id": "q_posture",
"text": "What posture or scapular finding is present on examination?",
"sublabel": "Observe from the front and behind",
"type": "choice",
"answers": [
{
"id": "round_shoulder",
"label": "Round-shouldered, forward-head posture (often bilateral)",
"sublabel": "Classic pectoral shortening posture",
"lr": {
"triceps_TrP5": 0.7,
"pec_major_sternal": 5.0,
"pec_minor": 4.0,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 1.0
}
},
{
"id": "scapular_winging",
"label": "Scapular prominence or winging, often unilateral round shoulder",
"sublabel": "Scapula stands out / wings",
"lr": {
"triceps_TrP5": 0.6,
"pec_major_sternal": 0.8,
"pec_minor": 1.0,
"serratus_anterior": 5.5,
"serratus_posterior_superior": 1.5
}
},
{
"id": "upper_thoracic_extension",
"label": "Upper-thoracic stiffness, tender T1 spinous process, difficulty flexing forward",
"sublabel": "Upper thoracic articular pattern",
"lr": {
"triceps_TrP5": 0.7,
"pec_major_sternal": 0.7,
"pec_minor": 0.8,
"serratus_anterior": 1.0,
"serratus_posterior_superior": 4.5
}
},
{
"id": "no_postural",
"label": "No specific postural or scapular abnormality",
"sublabel": "Posture unremarkable",
"lr": {
"triceps_TrP5": 2.0,
"pec_major_sternal": 0.7,
"pec_minor": 0.8,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 0.8
}
}
]
},
{
"id": "q_respiratory_complex",
"text": "Are there respiratory symptoms - breathlessness, air hunger, or inability to finish a sentence without pausing to breathe?",
"sublabel": "The serratus anterior respiratory symptom complex",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - dyspnea / air hunger / 'can't take a deep breath'",
"lr": {
"triceps_TrP5": 0.5,
"pec_major_sternal": 0.7,
"pec_minor": 1.2,
"serratus_anterior": 6.0,
"serratus_posterior_superior": 2.5
}
},
{
"id": "no",
"label": "No - no respiratory symptom component",
"lr": {
"triceps_TrP5": 1.5,
"pec_major_sternal": 1.2,
"pec_minor": 1.0,
"serratus_anterior": 0.3,
"serratus_posterior_superior": 0.8
}
}
]
},
{
"id": "q_wright_behindback",
"text": "Does raising and outwardly rotating the arm (Wright position) worsen symptoms, or is reaching behind the back restricted?",
"sublabel": "Pectoralis minor signs - neurovascular tensioning and scapular restriction",
"type": "binary",
"answers": [
{
"id": "yes",
"label": "Yes - Wright position worsens symptoms and/or behind-back reach is limited",
"lr": {
"triceps_TrP5": 0.6,
"pec_major_sternal": 1.5,
"pec_minor": 6.0,
"serratus_anterior": 1.0,
"serratus_posterior_superior": 0.8
}
},
{
"id": "no",
"label": "No - arm elevation/rotation and behind-back reach do not provoke it",
"lr": {
"triceps_TrP5": 1.3,
"pec_major_sternal": 1.0,
"pec_minor": 0.3,
"serratus_anterior": 1.0,
"serratus_posterior_superior": 1.1
}
}
]
},
{
"id": "q_palpation",
"text": "Where does firm palpation most precisely reproduce the patient's familiar pain?",
"sublabel": "The reproducing tender point - the most specific localiser",
"type": "choice",
"answers": [
{
"id": "deep_medial_arm",
"label": "Deep in the medial head of the triceps just above the medial epicondyle (anterior approach)",
"sublabel": "TrP5 location",
"lr": {
"triceps_TrP5": 7.0,
"pec_major_sternal": 0.4,
"pec_minor": 0.4,
"serratus_anterior": 0.4,
"serratus_posterior_superior": 0.5
}
},
{
"id": "sternal_chest",
"label": "In the sternal chest fibres / anterior axillary fold (pincer grasp of pec major)",
"sublabel": "Pec major sternal section",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 6.5,
"pec_minor": 1.5,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 0.5
}
},
{
"id": "deep_to_pecmajor",
"label": "Deep beneath pec major near the coracoid (pec minor, found after pec major slackened)",
"sublabel": "Pec minor location",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 1.2,
"pec_minor": 6.5,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 0.5
}
},
{
"id": "midaxillary_ribs",
"label": "Midaxillary line over the 5th/6th rib (serratus anterior against the ribs)",
"sublabel": "Serratus anterior location",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 0.6,
"pec_minor": 0.7,
"serratus_anterior": 7.0,
"serratus_posterior_superior": 0.8
}
},
{
"id": "under_scapula_ribs",
"label": "Deep against a rib under the abducted scapula (serratus posterior superior)",
"sublabel": "SPS location - only accessible with scapula abducted",
"lr": {
"triceps_TrP5": 0.4,
"pec_major_sternal": 0.5,
"pec_minor": 0.6,
"serratus_anterior": 0.8,
"serratus_posterior_superior": 7.0
}
}
]
}
],
"pairwise": [
{
"id": "pw_pecmaj_pecmin",
"pair": [
"pec_major_sternal",
"pec_minor"
],
"text": "Tiebreaker - Pectoralis Major vs Pectoralis Minor",
"question": "Does raising and outwardly rotating the arm (Wright position) reproduce the symptoms, or is the pain mainly reproduced by direct pressure on the sternal chest fibres?",
"sublabel": "Pec minor is a neurovascular tensioner; pec major is the superficial chest source",
"answers": [
{
"id": "wright",
"label": "Wright position / behind-back restriction dominates - pectoralis minor",
"lr": {
"pec_major_sternal": 0.3,
"pec_minor": 6.0
}
},
{
"id": "sternal",
"label": "Direct sternal-fibre tenderness reproduces it - pectoralis major",
"lr": {
"pec_major_sternal": 6.0,
"pec_minor": 0.3
}
}
]
},
{
"id": "pw_sa_sps",
"pair": [
"serratus_anterior",
"serratus_posterior_superior"
],
"text": "Tiebreaker - Serratus Anterior vs Serratus Posterior Superior",
"question": "Is the chest/arm pain provoked by deep breathing, coughing, or trunk torsion (anterolateral chest source), or is it a deep unreachable ache under the shoulder blade arcing to the little finger?",
"sublabel": "Anterior lateral-chest source vs deep posterior scapular source",
"answers": [
{
"id": "anterolateral",
"label": "Anterolateral chest, respiratory/torsional provocation - serratus anterior",
"lr": {
"serratus_anterior": 6.0,
"serratus_posterior_superior": 0.3
}
},
{
"id": "deep_posterior",
"label": "Deep unreachable scapular ache to the 5th finger - serratus posterior superior",
"lr": {
"serratus_anterior": 0.3,
"serratus_posterior_superior": 6.0
}
}
]
},
{
"id": "pw_triceps_pecmaj",
"pair": [
"triceps_TrP5",
"pec_major_sternal"
],
"text": "Tiebreaker - Triceps TrP5 vs Pectoralis Major",
"question": "Is the medial elbow pain reproduced by resisted elbow extension (pushing) with no chest component, or is there prominent anterior chest pain?",
"sublabel": "Local elbow extensor source vs chest-wall referred source",
"answers": [
{
"id": "elbow_extension",
"label": "Resisted elbow extension reproduces it; no chest pain - triceps TrP5",
"lr": {
"triceps_TrP5": 6.0,
"pec_major_sternal": 0.3
}
},
{
"id": "chest",
"label": "Prominent anterior chest pain present - pectoralis major",
"lr": {
"triceps_TrP5": 0.3,
"pec_major_sternal": 6.0
}
}
]
}
],
"treatment_dag": {
"edges": [
{
"from": "pec_major_sternal",
"to": "pec_minor",
"type": "functional_unit",
"label": "Pec major and minor almost always co-active - inactivate pec major first; pec minor often resolves"
},
{
"from": "serratus_anterior",
"to": "serratus_posterior_superior",
"type": "functional_unit",
"label": "Both accessory inspiratory muscles - serratus anterior can drive SPS; treat the dominant source first"
},
{
"from": "pec_major_sternal",
"to": "serratus_anterior",
"type": "antagonist_risk",
"label": "Serratus anterior is a pectoral antagonist - may develop stretch weakness; release before strengthening"
}
],
"edge_type_labels": {
"key_satellite": "Treat first - key TrP driving satellite",
"functional_unit": "Treat concurrently in same session",
"secondary_load": "Treat after primary resolves",
"antagonist_risk": "Treat in alternating cycles - reactive activation risk"
}
},
"emergency": [
{
"id": "rf-e1",
"label": "Acute coronary syndrome / myocardial ischaemia",
"question": "Left-sided chest, medial arm, or medial elbow pain with pressure, tightness, or constriction? Exertional onset, breathlessness, diaphoresis, nausea, or jaw pain? Cardiac risk factors (age, hypertension, diabetes, smoking, known CAD)? NOTE: pectoral and serratus anterior TrPs reproduce anginal pain in exact detail - relief by TrP treatment does NOT exclude cardiac disease. Cardiac status must be established independently.",
"source": "T&S Vol.1 Ch.42 (pec major cardiac mimicry); Reece et al. StatPearls 2024"
},
{
"id": "rf-e2",
"label": "Acute compartment syndrome of the forearm",
"question": "Severe, disproportionate, worsening forearm pain unrelieved by rest? Pain sharply increased by passive finger or wrist extension? Tense or woody forearm? Paraesthesia or pallor of the hand? Recent fracture, crush, or tight cast?",
"source": "Standard limb emergency screen"
},
{
"id": "rf-e3",
"label": "Septic arthritis of the elbow",
"question": "Acutely hot, swollen, exquisitely tender elbow with severe restriction of all movement? Fever or systemically unwell? Recent bacteraemia, penetrating injury, IV drug use, or immunosuppression?",
"source": "Standard joint-sepsis screen"
}
],
"urgent": [
{
"id": "rf-u1",
"label": "Ulnar collateral ligament (UCL) tear",
"question": "Throwing athlete or valgus-load history? Acute 'pop' or gradual medial pain worst in late cocking / early acceleration of throwing? Valgus laxity on stress testing or positive milking manoeuvre? Tenderness at the anteroinferior medial epicondyle (UCL origin) rather than the flexor mass?",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
},
{
"id": "rf-u2",
"label": "Cubital tunnel syndrome / ulnar neuropathy",
"question": "Numbness or tingling in the ring and little fingers? Positive Tinel sign at the cubital tunnel? Ulnar nerve subluxation out of the groove on elbow flexion? Intrinsic hand weakness or clumsiness? NOTE: ulnar neuritis coexists with medial epicondylitis in up to 50% and worsens prognosis - examine the nerve in every case.",
"source": "Reece et al. StatPearls 2024; Gabel & Morrey 1995"
},
{
"id": "rf-u3",
"label": "Valgus extension overload / posteromedial impingement",
"question": "Throwing athlete with pain at terminal extension and a hard end-feel? Posteromedial olecranon osteophyte on X-ray? Often coexists with UCL insufficiency.",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
},
{
"id": "rf-u4",
"label": "Cervical radiculopathy (C8-T1)",
"question": "Neck pain with medial arm/forearm pain in a dermatomal pattern? Positive Spurling's test? Objective sensory deficit, reflex change, or myotomal weakness? Radicular pain not reproduced by local muscle palpation?",
"source": "Reece et al. StatPearls 2024 (differential)"
},
{
"id": "rf-u5",
"label": "Occult fracture / osteochondritis dissecans",
"question": "Significant trauma or acute onset? Bony point tenderness, swelling, or effusion? In an adolescent or skeletally immature athlete (growth plate more vulnerable than tendon)? Mechanical symptoms (locking, catching) suggesting a loose body?",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
}
],
"broad_differential": [
{
"id": "bd-1",
"condition": "Medial epicondylitis (golfer's / thrower's elbow)",
"confidence": "common",
"mimics": "Medial epicondyle pain worse with gripping, wrist flexion, and pronation - overlaps the medial-elbow TrP referral zone",
"distinguishing_feature": "Tenderness 5-10 mm DISTAL to the medial epicondyle at the flexor-pronator insertion; pain reproduced by RESISTED WRIST FLEXION and PRONATION (pronation most sensitive, elbow flexed 90 degrees). Triceps TrP5 referral is NEGATIVE on resisted wrist flexion - this is the key separator. A degenerative tendinosis, not inflammation.",
"action": "Clinical diagnosis; MRI (gold standard) or ultrasound (95% sensitivity) if ambiguous. Conservative: activity cessation, ice, NSAIDs, counterforce strap 2 cm below epicondyle, physiotherapy with eccentric loading. Examine the ulnar nerve in every case. Surgery only after 6-12 months of failed conservative care.",
"source": "Reece et al. StatPearls 2024"
},
{
"id": "bd-2",
"condition": "Ulnar neuropathy / cubital tunnel syndrome",
"confidence": "common",
"mimics": "Medial elbow pain with ulnar-sided forearm and 4th/5th finger symptoms - overlaps both triceps TrP5 and the chest-wall ulnar spillover patterns",
"distinguishing_feature": "Objective sensory loss in the ulnar distribution, positive Tinel at the cubital tunnel, ulnar nerve subluxation on flexion, and intrinsic hand weakness/wasting. TrP referral produces ulnar-pattern PAIN without objective neurological deficit or nerve-conduction slowing. Coexists with medial epicondylitis in up to 50%.",
"action": "Tinel sign, elbow flexion test, nerve subluxation check. EMG/NCS confirms and grades. Activity modification, night splinting in extension; surgical decompression or transposition if progressive motor involvement.",
"source": "Reece et al. StatPearls 2024; Gabel & Morrey 1995"
},
{
"id": "bd-3",
"condition": "Ulnar (medial) collateral ligament sprain or tear",
"confidence": "uncommon",
"mimics": "Medial elbow pain in throwing athletes - same population and medial location as the muscular sources",
"distinguishing_feature": "Tenderness at the anteroinferior medial epicondyle (UCL origin), valgus laxity on stress testing, positive milking manoeuvre. Pain worst in late cocking / early acceleration of throwing. Calcification or traction osteophyte on X-ray; MRI arthrogram is most sensitive.",
"action": "Valgus stress and milking tests; MRI arthrogram. Conservative rehab with pronator-flexor strengthening for partial tears; UCL reconstruction for throwing athletes wishing to return to sport.",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
},
{
"id": "bd-4",
"condition": "Valgus extension overload / posteromedial impingement",
"confidence": "uncommon",
"mimics": "Medial and posteromedial elbow pain in throwers - overlaps triceps and UCL territory",
"distinguishing_feature": "Pain at terminal extension with a hard end-feel; posteromedial olecranon osteophyte on X-ray; often with UCL insufficiency and increased carrying angle. TrP pain has a soft end-feel and is reproduced by palpation.",
"action": "X-ray and CT for osteophyte/loose body; assess MCL integrity. Arthroscopic debridement of the posteromedial osteophyte; address concurrent instability.",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
},
{
"id": "bd-5",
"condition": "Cervical radiculopathy (C8-T1)",
"confidence": "uncommon",
"mimics": "Medial arm and forearm pain - overlaps the ulnar spillover of all the chest-wall and triceps sources",
"distinguishing_feature": "Dermatomal sensory deficit, reflex change, myotomal weakness, positive Spurling's. TrP referral produces no reflex change or true dermatomal deficit and IS reproduced by muscle palpation. TrPs commonly develop secondarily to radiculopathy and may coexist.",
"action": "Spurling's test, neurological examination. MRI cervical spine and EMG/NCS if neurological signs. Treat coexisting TrPs concurrently - they may be the dominant pain source.",
"source": "Reece et al. StatPearls 2024 (differential)"
},
{
"id": "bd-6",
"condition": "Synovial plica / synovitis of the elbow",
"confidence": "rare",
"mimics": "Medial or posteromedial elbow pain with mechanical symptoms",
"distinguishing_feature": "Painful snapping or catching with flexion-extension; localised joint-line tenderness; effusion in synovitis. TrP pain has no mechanical catching and no effusion.",
"action": "MRI or arthroscopy. Conservative management; arthroscopic excision of symptomatic plica if refractory.",
"source": "Reece et al. StatPearls 2024 (differential)"
},
{
"id": "bd-7",
"condition": "Elbow osteoarthritis / rheumatoid arthritis",
"confidence": "uncommon",
"mimics": "Medial elbow aching, particularly in older or inflammatory-arthropathy patients",
"distinguishing_feature": "Joint-line tenderness, crepitus, loss of both flexion and extension, radiological joint changes; morning stiffness and systemic features in RA. TrP pain spares the joint line and produces no radiological change.",
"action": "X-ray; inflammatory screen if RA suspected. Manage the arthropathy; TrPs are independently treatable and frequently coexist.",
"source": "Reece et al. StatPearls 2024 (differential)"
},
{
"id": "bd-8",
"condition": "Herpes zoster (shingles)",
"confidence": "uncommon",
"mimics": "Unilateral burning medial arm or chest-wall pain before the rash appears - indistinguishable from a chest-wall or arm TrP pattern at onset",
"distinguishing_feature": "Dermatomal distribution; allodynia (light touch painful in a band); vesicles appear 1-4 days after pain onset. Age over 50 or immunocompromise raises suspicion.",
"action": "Examine the skin carefully at every visit for unilateral burning pain. If vesicles appear, refer urgently - the antiviral window is 72 hours from rash onset.",
"source": "Reece et al. StatPearls 2024 (differential); Chung et al. 2025"
}
]
}