12-phase flow (12)

1. 1FRAME
   Adult subacute/chronic plantar heel pain — a DIFFERENTIAL DISCIPLINE first (plantar fasciopathy vs calcaneal stress fracture vs nerve entrapment vs systemic enthesitis; fat-pad atrophy / fibromatosis / Sever-paediatric explicitly excluded) then a natural-history-anchored conservative ladder (~80–90% resolve <12 mo — Crawford Cochrane 2003 PMID 12917892; DiGiovanni 2006 PMID 16882901; JOSPT CPG 2023 PMID 38037331)
   inputs: age, symptom_duration
   advance: Scope confirmed adult; paediatric (Sever) routed out; differential framed
2. 2ENTRY
   Recognise the classic triad — post-static (first-step) morning heel pain easing then worsening with load + medial calcaneal tubercle tenderness + positive windlass — vs an entry that is bilateral/inflammatory or load-acute (runner) demanding mimic screening (JOSPT CPG 2023; 2014). BAYESIAN PRIORS (set the differential, not just PHP): in an undifferentiated inferior-heel-pain adult presenting to primary/MSK care plantar fasciopathy pre-test ≈0.80, calcaneal stress fracture ≈0.05 (rising to ≈0.20–0.30 in a runner/recruit/RED-S/osteoporotic — De Garceau 2003 PMID 12793489 mimic-enriched cohort framing), tarsal-tunnel/Baxter nerve entrapment ≈0.05–0.10, systemic SpA enthesitis ≈0.04 (rising if bilateral+inflammatory — Kim 2018 PMID 30187686; Yang 2015 PMID 26359027), fat-pad atrophy ≈0.04, S1 radiculopathy ≈0.02 (route msk.low-back-pain.core.v1). Wired LR+ for the WINDLASS test (weight-bearing): sensitivity 31.8% (7/22) but specificity 100% (0/53 non-PF, i.e. other-foot-pain + controls, positive) → LR+ → ∞ (rule-IN; reference standard = clinical PF dx vs other foot pain — De Garceau 2003 PMID 12793489); non-weight-bearing windlass sens 13.6%/spec 100% (LR+ → ∞ but LR− 0.86, poor rule-out)
   inputs: first_step_morning_heel_pain, medial_calcaneal_tubercle_tenderness
   actions: workup.plantar_heel_pain
   advance: Entry trigger characterised (classic vs atypical/inflammatory/load-acute) and pre-test priors per ddx assigned
3. 3CONTEXT
   Capture risk/driver profile: BMI (obese OR 2.9, Irving 2007 PMID 17506905), foot posture (pronated FPI≥4 OR 3.7), activity (runner/recruit/load-spike → stress-fracture prior), symptom duration (chronic >6 mo), gastroc tightness, diabetes (injection caution + neuropathic mimic), osteoporosis/RED-S (stress-fracture prior), prior steroid injection (rupture risk — Acevedo 1998 PMID 9498581), and laterality + inflammatory features (spondyloarthritis pivot)
   inputs: bmi, activity_level, symptom_duration, laterality_and_inflammatory_features, diabetes_status, prior_corticosteroid_injection
   advance: Pre-test priors + comorbidity/driver profile captured
4. 4RED_FLAGS
   Calcaneal stress fracture — positive calcaneal SQUEEZE test (medial-lateral compression of the calcaneal body) in a runner / military recruit / RED-S / osteoporotic / training-load-spike patient → route msk.fracture-triage.core.v1 + MRI/bone-stress imaging + relative offloading, NOT injection and NOT continued loading. Squeeze-test probability shift is conditioned on the bone-stress-risk prior (Conditional Dependency 5): in the at-risk subgroup a positive squeeze is a strong rule-IN for bone stress and overrides the conservative fasciopathy ladder; in a low-risk sedentary adult it is weakly discriminating (commonly fat-pad/fascial) and does NOT by itself mandate MRI (Nweke 2025 PMID 40717873 retains heel-squeeze in the core exam triad for stress-fracture exclusion). Infection/tumour: fever, rest/night pain unrelieved by rest, weight loss, focal bony destruction, malignancy history → escalate/image. Profound sensory loss / rapidly progressive neuro deficit, or referred heel pain with dermatomal/SLR signs → urgent nerve/spine evaluation, route msk.low-back-pain.core.v1 if S1 radicular (JOSPT CPG 2023; 2014)
   inputs: calcaneal_squeeze_test, activity_level
   actions: workup.plantar_heel_pain
   advance: Stress fracture & infection/tumour & severe neuro screened — escalated if present, else mechanical PHP pathway
5. 5INITIAL_WORKUP
   Clinical diagnosis — history of post-static dyskinesia (cardinal), exam: medial calcaneal tubercle / proximal fascia tenderness, WINDLASS test (passive 1st-MTP dorsiflexion ± weight-bearing), gastroc-soleus tightness, foot posture, gait/footwear. WIRED LR (windlass, weight-bearing): LR+ → ∞ (spec 100%, De Garceau 2003 PMID 12793489) but LR− ≈0.68 (sens 31.8%) — a NEGATIVE windlass does NOT exclude PHP. CONDITIONAL DEPENDENCY 1 (windlass-LR | chronicity & nerve co-load): the windlass test is NOT structure-specific — in cadaveric strain testing 1st-MTP extension also significantly loads the tibial / lateral-plantar / medial-plantar nerves (Alshami 2007 PMID 17475147), so when nerve-entrapment features co-exist (positive Tinel, burning, sensory signs) the windlass LR+ is degraded toward non-discriminatory and must NOT be combined naively with post-static history as if conditionally independent; in long-standing chronic PHP fascial contracture may also blunt windlass provocation, lowering observed sensitivity below the acute estimate. CONDITIONAL DEPENDENCY 2 (post-static history | windlass): post-static dyskinesia and a positive windlass share the same fascial-load mechanism — they are positively correlated given disease, so multiply their individual LRs only with a correlation discount, not as independent tests. Imaging is NOT required for the classic windlass-positive phenotype; reserve for atypical/red-flag/refractory (JOSPT CPG 2023; corroborated by the 2025 evidence framework Nweke 2025 PMID 40717873 which retains the exam triad + heel-squeeze + selective imaging). Education on favourable natural history is itself a Strong first-line intervention
   inputs: post_static_dyskinesia_pattern, medial_calcaneal_tubercle_tenderness, ankle_dorsiflexion_gastroc_tightness
   actions: workup.plantar_heel_pain, workup.tendinopathy
   advance: Clinical diagnosis supported, windlass LR interpreted conditional on nerve-co-load/chronicity, natural-history education delivered; advance if atypical features require branching
6. 6BRANCHING_WORKUP
   Atypical features drive cascading diagnostics. HEEL ULTRASOUND — wired binned LRs (reference standard = APTA/JOSPT clinical PF dx; convert published sens/spec → LR): plantar-fascia thickness >4 mm — in a low-pretest screening cohort sens 96%/spec 100% → LR+ ≈ very large (point estimate → ∞ at spec 100%; conservative bounded ≈48 using continuity correction), LR− 0.04 (Aggarwal 2020 PMID 32817771; n=44 PF vs 50 healthy controls); BUT in a HIGH-pretest, mimic-enriched cohort the SAME >4 mm cutoff degrades to sens 70%/spec 66.7% → LR+ 2.1, LR− 0.45 (Ramu 2022 PMID 35947294) — see Conditional Dependency 3. STRONGEST WIRED RULE-IN findings: abnormal fascial echopattern sens 90%/spec 96.7% → LR+ 27.3, LR− 0.10; hypoechoic intrafascial areas sens 80%/spec 96.7% → LR+ 24.2, LR− 0.21; perifascial oedema sens 26.7%/spec 100% → LR+ → ∞ (Ramu 2022 PMID 35947294). Combined B-mode thickness + shear-wave elastography composite sens 93.3%/spec 93.8% → LR+ 15.0, LR− 0.071 (Wang 2023 PMID 37904905, AUC 0.973; thickness-alone AUC 0.925, cutoff 3.15 mm sens 100%/spec 81.3% → LR+ 5.35). Sonoelastography raises B-mode accuracy 90% → 95.4% (Sconfienza 2013 PMID 23297327; n=80 PF vs 50). CONDITIONAL DEPENDENCY 3 (US-thickness threshold | symptom & pretest prevalence): the >4 mm thickness LR is NOT fixed — it is conditional on the source-population pretest probability (rule-IN power collapses from ~∞ in a healthy-control comparison to LR+ 2.1 in a heel-pain-vs-heel-pain comparison) AND on the diagnostic question (a thick fascia is far less specific when the competing diagnosis is enthesitis, which ALSO thickens the fascia); therefore in a high-pretest or mimic-rich patient prefer the qualitative signs (echopattern/hypoechoic) over the single thickness cutoff. CONDITIONAL DEPENDENCY 4 (enthesitis prior | bilaterality + inflammatory features): positive Tinel/burning/night-sensory → tarsal tunnel / Baxter first-branch lateral plantar nerve (nerve conduction/MRI); bilateral + inflammatory rhythm + age <45 + psoriasis/IBP/uveitis raises SpA-enthesitis prior — only THEN do CRP/ESR and US-enthesis composite (tendon thickening + bursal synovitis + bone erosion) discriminate (sens 70.7%/spec 65.5%, AUC 0.740 → LR+ 2.05, LR− 0.45 — Yang 2015 PMID 26359027; plain-film posterior calcaneal erosion / retrocalcaneal-recess obliteration tracks symptomatic SpA enthesis — Kim 2018 PMID 30187686); a unilateral mechanical presentation with normal CRP keeps the SpA posterior so low that an isolated thick fascia should NOT trigger the rheum route. Suspected stress fracture / mass → heel MRI (marrow oedema); back/dermatomal signs → S1 radiculopathy → route msk.low-back-pain.core.v1 (JOSPT CPG 2023)
   inputs: tinel_tarsal_tunnel, crp_esr, heel_ultrasound, heel_mri
   actions: panel.inflammation, workup.tendinopathy
   advance: Mimic-specific branching complete; US LR interpreted conditional on pretest+competing-dx; terminal entity assignable or routed by engine_id
7. 7DIFFERENTIAL
   MECE 6-way pivot with engine_id routing: (1) plantar FASCIOPATHY — medial, post-static, windlass LR+→∞ (De Garceau 2003 PMID 12793489), US echopattern LR+ 27.3 (Ramu 2022 PMID 35947294); (2) calcaneal STRESS FRACTURE — diffuse, calcaneal-SQUEEZE+, athlete/recruit/osteoporosis/RED-S, MRI marrow oedema → route msk.fracture-triage.core.v1 (carry over load-history + bone-stress-risk + squeeze result); (3) NERVE ENTRAPMENT — tarsal tunnel/Baxter, Tinel+, burning/sensory, no clean post-static; (4) systemic ENTHESITIS of spondyloarthritis — bilateral, inflammatory rhythm, CRP↑, US-enthesis composite LR+ 2.05 (Yang 2015 PMID 26359027) → route rheum.axial-spondyloarthritis.core.v1 (carry over laterality + inflammatory-feature + CRP); (5) S1 RADICULOPATHY — referred heel pain, dermatomal/SLR/reflex signs, no post-static rhythm → route msk.low-back-pain.core.v1 (carry over neuro exam); (6) CENTRAL-SENSITISATION / chronic-widespread-pain OVERLAY — catastrophising explains ~39% of foot-function variance (Cotchett 2017 PMID 28605621) → co-manage msk.fibromyalgia.core.v1 if ACR-2016 positive (overlay, not exclusion). CONDITIONAL DEPENDENCY 5 (stress-fracture prior | athlete/osteoporosis/RED-S): the calcaneal-squeeze test only meaningfully shifts probability when the PRIOR is elevated — in a sedentary non-osteoporotic adult a positive squeeze is far more often fat-pad/fascial than a true stress fracture, whereas in a runner/recruit/RED-S/osteoporotic patient the same finding mandates MRI and offloading; squeeze interpretation is therefore explicitly conditioned on the bone-stress-risk profile (corroborated as a core triad element — Nweke 2025 PMID 40717873). Co-existence/look-alikes: heel fat-pad atrophy (central tenderness, may co-exist post-injection), plantar fibromatosis (palpable nodule), infection/tumour; Sever apophysitis = paediatric, excluded (JOSPT CPG 2023; 2014; 2008 PMID 18434670)
   inputs: post_static_dyskinesia_pattern, calcaneal_squeeze_test
   advance: Terminal entity assigned; mimics excluded or routed by engine_id with carryover state
8. 8RISK_STRATIFICATION
   Stratify by chronicity (subacute vs chronic >6 mo — drives night-splint/ESWT eligibility), prior-treatment failures (refractory tier → injection/ESWT/PRP/surgery), modifiable-driver burden (BMI obese OR 2.9 95% CI 1.4–6.1; pronated foot FPI≥4 OR 3.7 95% CI 1.6–8.7 — Irving 2007 PMID 17506905; occupational standing), psychosocial burden (high pain-catastrophising ~39% / kinesiophobia ~21% of foot-function variance — Cotchett 2017 PMID 28605621; predicts poor conservative response → central-sensitisation overlay), and harm risk (prior steroid injection → cumulative rupture/fat-pad-atrophy risk Acevedo 1998 PMID 9498581; diabetes → injection glycaemic caution; CKD → NSAID avoidance; pregnancy → procedure deferral). T_TEST / T_TREAT thresholds: with windlass+ (LR+→∞) and classic post-static history the post-test probability of PHP is high enough to cross T_treat (initiate conservative ladder) WITHOUT imaging (JOSPT CPG 2023 — imaging not required for classic phenotype); imaging is only ordered when an atypical/red-flag feature drops post-test probability below T_treat or raises a competing-diagnosis prior above its own T_test (stress fracture in an at-risk athlete; enthesitis if bilateral+inflammatory). No PHP-specific validated severity calculator exists — stratification is clinical (JOSPT CPG 2023)
   inputs: symptom_duration, prior_corticosteroid_injection
   actions: calc.ckd_epi_2021
   advance: Chronicity + refractory tier + harm-risk profile documented; treatment tier set
9. 9TREATMENT
   Conservative ladder anchored to natural history (Strong: education on favourable course + manual therapy/stretching + foot orthoses + taping — JOSPT CPG 2023 PMID 38037331). Rung 1 education/load-modification/relative-rest; Rung 2 plantar-fascia-SPECIFIC stretch (toe-dorsiflexion, DiGiovanni JBJS 2006 PMID 16882901 — 2-y 92% satisfied, 94% reduced pain) ± gastroc-soleus stretch; Rung 3 footwear + prefabricated/custom orthoses + low-Dye taping (short-term); Rung 4 night splint for chronic >6 mo (modest/adjunctive — Batt 1996 PMID 8792046 positive small RCT, Wheeler 2017 PMID 29259809 null between-group); Rung 5 short-course NSAID (eGFR/GI/CV-gated) or acetaminophen for analgesia only; Rung 6 fascia-loading/calf-strengthening progression. REFRACTORY (≥3–6 mo failed): Rung 7 corticosteroid injection — ideally US-guided; ~4-week-only pain benefit (McMillan BMJ 2012 PMID 22619193: +10.9 FHSQ pts at 4 wk, NNT 2.93, NO benefit 8/12 wk) with explicit rupture/fat-pad-atrophy harm (Acevedo 1998 PMID 9498581: 86% of ruptures injection-associated), diabetic glycaemic caution; Rung 8 ESWT for refractory (high-quality large pain+function effect — Charles 2023 PMID 37662911; medium-intensity, Zhao NMA 2025 PMID 40709373 OR 2.29–5.50 vs placebo); Rung 9 last-line/debated PRP (mid-term > steroid — Ye 2025 PMID 40200209 6-mo VAS OR −1.41) then surgery: gastrocnemius recession PREFERRED (76% pain reduction, low complications — Pickin 2022 PMID 34838458) over plantar fasciotomy (lateral-column overload risk — Gamba 2022 PMID 35692721). Bilateral inflammatory enthesitis → do NOT inject; route to rheum.axial-spondyloarthritis.core.v1
   inputs: symptom_duration, creatinine_egfr, prior_corticosteroid_injection
   actions: calc.ckd_epi_2021
   advance: Appropriate ladder rung initiated with shared decision-making on natural history & injection harm
10. 10DISPOSITION
    Outpatient management for essentially all plantar fasciopathy. Specialty referral: rheumatology if systemic enthesitis suspected (route to rheum.axial-spondyloarthritis.core.v1); foot-and-ankle surgery / sports medicine for refractory after structured conservative ladder ± ESWT failure; urgent imaging/escalation if stress fracture, infection, tumour, or progressive neuro deficit. No admission pathway for uncomplicated PHP (JOSPT CPG 2023)
    advance: Level of care + referral pathway set
11. 11MONITORING
    Reassess pain (first-step VAS / FFI / FHSQ) and function at ~6–12 weeks of conservative care; expect gradual improvement on the natural-history trajectory. Re-screen mimics if NOT improving as expected (re-consider stress fracture, nerve entrapment, systemic enthesitis). Post-injection: monitor for sudden tearing/arch collapse (rupture — Acevedo 1998 PMID 9498581) and glycaemia in diabetes. On NSAID: renal function/eGFR (CKD-EPI 2021) + GI tolerance. Track modifiable drivers (weight, footwear, load) (JOSPT CPG 2023)
    inputs: symptom_duration, creatinine_egfr
    actions: calc.ckd_epi_2021
    advance: Trajectory reviewed; mimic re-screen if off-trajectory; harm surveillance documented
12. 12FOLLOWUP
    Counsel that ~80–90% resolve within ~12 months on first-line care (Crawford Cochrane 2003 PMID 12917892; DiGiovanni 2006 PMID 16882901); maintain plantar-fascia/gastroc stretching, weight management, supportive footwear, graded load return. Escalate stepwise only for the refractory minority. Return precautions: sudden heel "pop"/arch collapse (rupture), new burning/numbness (nerve), bilateral/inflammatory features (systemic enthesitis), fever/night-rest pain/weight loss (infection/tumour) (JOSPT CPG 2023)
    advance: Self-management + escalation thresholds + return precautions communicated