DiagnosticTree/Olecranon

{

 "schema_version": "2.1",
 "region_id": "Olecranon",
 "region_label": "Olecranon / Posterior Elbow Pain",
 "red_flags": [
   "Fluctuant swelling directly over the olecranon tip \u2014 olecranon bursitis; if with fever/erythema, septic bursitis is an emergency",
   "Loss of active elbow extension or palpable gap in the triceps tendon \u2014 distal triceps rupture; urgent orthopaedic evaluation; look for flake sign on plain film",
   "Pain only at terminal extension with hard end-feel, comfortable mid-range \u2014 elbow osteoarthritis with bony impingement; radiograph indicated",
   "Young throwing athlete with focal olecranon tenderness \u2014 stress fracture; plain film then MRI if negative",
   "Fever, warmth, erythema at the posterior elbow \u2014 septic bursitis or septic arthritis; emergency evaluation"
 ],
 "broad_differential": [
   {
     "diagnosis": "Olecranon bursitis (aseptic or septic)",
     "key_features": "Visible fluctuant swelling at olecranon tip; may be painless (aseptic) or painful with fever/erythema (septic); elbow ROM usually preserved; distinguish from TrP4 by presence of bursal fluid \u2014 TrP4 tenderness is deep to the aponeurosis with no fluctuance",
     "reference": "Chung et al. 2025 (PMC12093526); Muscle:Triceps_Brachii differential"
   },
   {
     "diagnosis": "Distal triceps tendon rupture / triceps tendinopathy",
     "key_features": "Weakness or loss of active elbow extension; palpable gap at tendon; positive modified Campbell Thompson test for complete tear; flake sign on X-ray; TrP4 preserves full active extension strength",
     "reference": "Chung et al. 2025 (PMC12093526)"
   },
   {
     "diagnosis": "Elbow osteoarthritis (posterior compartment)",
     "key_features": "Pain at terminal extension and/or maximum flexion only; comfortable mid-range; osteophytes on X-ray; stiffness; may cause ulnar neuropathy",
     "reference": "Chung et al. 2025 (PMC12093526)"
   },
   {
     "diagnosis": "C8\u2013T1 radiculopathy",
     "key_features": "Objective neurological deficit (motor weakness, reflex change, dermatomal sensory loss, positive Spurling's) \u2014 must be present to diagnose; serratus posterior superior refers numbness into C8\u2013T1 distribution WITHOUT neurological deficit",
     "reference": "Muscle:Serratus_Posterior differential"
   }
 ],
 "muscles": [
   {
     "id": "triceps_TrP4",
     "label": "Triceps Brachii (distal attachment, near olecranon)",
     "page": "Muscle:Triceps_Brachii",
     "prior": 0.6,
     "bold": true
   },
   {
     "id": "serratus_posterior_superior",
     "label": "Serratus Posterior Superior",
     "page": "Muscle:Serratus_Posterior",
     "prior": 0.4,
     "bold": false
   }
 ],
 "questions": [
   {
     "id": "q1",
     "text": "What is the full extent of your pain \u2014 beyond just the elbow tip?",
     "type": "single",
     "answers": [
       {
         "id": "q1a1",
         "text": "Pain right at the elbow tip (olecranon) only \u2014 nothing above the elbow or down the forearm",
         "likelihood_ratios": {
           "triceps_TrP4": 7.5,
           "serratus_posterior_superior": 0.3
         }
       },
       {
         "id": "q1a2",
         "text": "Elbow tip pain plus aching in the back of the upper arm or shoulder",
         "likelihood_ratios": {
           "triceps_TrP4": 2.0,
           "serratus_posterior_superior": 1.5
         }
       },
       {
         "id": "q1a3",
         "text": "Elbow tip pain plus a deep ache under the shoulder blade that you can't quite reach, running down toward the little finger",
         "likelihood_ratios": {
           "triceps_TrP4": 0.3,
           "serratus_posterior_superior": 7.5
         }
       },
       {
         "id": "q1a4",
         "text": "Elbow tip pain plus numbness or tingling down the inner forearm or into the little (5th) finger",
         "likelihood_ratios": {
           "triceps_TrP4": 0.3,
           "serratus_posterior_superior": 6.0
         }
       }
     ]
   },
   {
     "id": "q2",
     "text": "What activity or situation most reliably provokes or worsens the elbow tip pain?",
     "type": "single",
     "answers": [
       {
         "id": "q2a1",
         "text": "Pushing things away, press-ups, dips, or straightening the elbow against resistance",
         "likelihood_ratios": {
           "triceps_TrP4": 6.5,
           "serratus_posterior_superior": 0.35
         }
       },
       {
         "id": "q2a2",
         "text": "Sustained postures \u2014 elbow held forward or unsupported for long periods (driving, writing, desk work)",
         "likelihood_ratios": {
           "triceps_TrP4": 3.0,
           "serratus_posterior_superior": 2.0
         }
       },
       {
         "id": "q2a3",
         "text": "History of prolonged coughing, respiratory illness, or breathing difficulties \u2014 pain started or worsened during or after",
         "likelihood_ratios": {
           "triceps_TrP4": 0.3,
           "serratus_posterior_superior": 7.0
         }
       },
       {
         "id": "q2a4",
         "text": "Reaching behind yourself, carrying loads with arms extended, or sitting with shoulders elevated",
         "likelihood_ratios": {
           "triceps_TrP4": 0.5,
           "serratus_posterior_superior": 5.5
         }
       }
     ]
   },
   {
     "id": "q3",
     "text": "Do you have any associated sensations \u2014 aching, numbness, or tingling \u2014 away from the elbow itself?",
     "type": "single",
     "answers": [
       {
         "id": "q3a1",
         "text": "No radiation \u2014 the pain stays localised to the back of the elbow tip",
         "likelihood_ratios": {
           "triceps_TrP4": 4.5,
           "serratus_posterior_superior": 0.4
         }
       },
       {
         "id": "q3a2",
         "text": "Aching into the back of the upper arm, sometimes toward the back of the shoulder",
         "likelihood_ratios": {
           "triceps_TrP4": 2.5,
           "serratus_posterior_superior": 3.0
         }
       },
       {
         "id": "q3a3",
         "text": "Numbness or tingling down the inner (little-finger) side of the forearm or into the 5th digit",
         "likelihood_ratios": {
           "triceps_TrP4": 0.4,
           "serratus_posterior_superior": 6.5
         }
       },
       {
         "id": "q3a4",
         "text": "A sense of deep tenderness or fullness under the shoulder blade on the same side",
         "likelihood_ratios": {
           "triceps_TrP4": 0.35,
           "serratus_posterior_superior": 7.0
         }
       }
     ]
   },
   {
     "id": "q4",
     "text": "Does pushing things away from you, or straightening the elbow against resistance, specifically reproduce the elbow tip pain?",
     "type": "single",
     "answers": [
       {
         "id": "q4a1",
         "text": "Yes \u2014 the elbow tip specifically hurts when pushing, pressing, or extending against resistance",
         "likelihood_ratios": {
           "triceps_TrP4": 6.0,
           "serratus_posterior_superior": 0.35
         }
       },
       {
         "id": "q4a2",
         "text": "No \u2014 straightening the elbow under load does not change the pain; posture or breathing matters more",
         "likelihood_ratios": {
           "triceps_TrP4": 0.4,
           "serratus_posterior_superior": 5.5
         }
       },
       {
         "id": "q4a3",
         "text": "Unsure / pain is present with most activities regardless of elbow loading",
         "likelihood_ratios": {
           "triceps_TrP4": 1.0,
           "serratus_posterior_superior": 1.0
         }
       }
     ]
   },
   {
     "id": "q5",
     "text": "Where is the most tender spot when you or a clinician press firmly in the area?",
     "type": "single",
     "answers": [
       {
         "id": "q5a1",
         "text": "Right at the olecranon tip \u2014 deep, spot tenderness through the tendon; no swelling or fluctuance",
         "likelihood_ratios": {
           "triceps_TrP4": 5.5,
           "serratus_posterior_superior": 0.4
         }
       },
       {
         "id": "q5a2",
         "text": "Deep under the shoulder blade \u2014 tenderness only accessible when the arm is swung well forward",
         "likelihood_ratios": {
           "triceps_TrP4": 0.3,
           "serratus_posterior_superior": 7.0
         }
       },
       {
         "id": "q5a3",
         "text": "In the back of the upper arm muscle belly, somewhere above the elbow",
         "likelihood_ratios": {
           "triceps_TrP4": 3.5,
           "serratus_posterior_superior": 2.0
         }
       },
       {
         "id": "q5a4",
         "text": "Not well localised \u2014 pain felt but hard to pinpoint on palpation",
         "likelihood_ratios": {
           "triceps_TrP4": 1.2,
           "serratus_posterior_superior": 1.2
         }
       }
     ]
   }
 ],
 "treatment_dag": {
   "triceps_TrP4": [],
   "serratus_posterior_superior": [
     "triceps_TrP4"
   ]
 }

}