Musculoskeletal

Sports medicine: stress fracture and overuse injuries

Clinical Overview and When to Suspect Stress Fracture and Overuse Injuries

— Bone: repetitive microtrauma → osteoclastic resorption outpaces osteoblastic formation → microfractures coalesce

— Tendon: failed healing response, collagen disarray (tendinosis, not tendinitis)

— Trigger is almost always a "too much, too soon" training error — abrupt increase in volume, intensity, frequency, or surface change (>10%/week rule)

— Insidious, activity-related pain in a runner, military recruit, dancer, or adolescent athlete

— Pain that progresses earlier into the activity over weeks (early sign: pain after; late: pain during and at rest)

— Focal bony tenderness, especially tibia, metatarsal, navicular, femoral neck, pars interarticularis

— New shoe, new mileage, new surface, return after deconditioning

— Female athletes with menstrual dysfunction (Female Athlete Triad / RED-S)

— Military trainees in first 6–8 weeks of basic training

— Cross-country and track runners, ballet dancers, gymnasts, basketball players

— Older adults with low BMD doing new exercise programs

Definition: Stress injuries are a continuum from stress reaction (periosteal edema, marrow edema on MRI without cortical break) to overt stress fracture (cortical disruption). Overuse injuries broadly include tendinopathy, apophysitis, medial tibial stress syndrome (MTSS), and bursitis from repetitive submaximal load exceeding bone/tendon remodeling capacity.

Pathophysiology:

When to suspect on Step 3:

High-risk demographics:

Step 3 management: In the ambulatory clinic, the first decision is risk stratification by location, not imaging. High-risk sites (femoral neck tension side, anterior tibial cortex "dreaded black line," navicular, 5th metatarsal base, medial malleolus, pars, sesamoids) demand urgent imaging and non-weight-bearing; low-risk sites (posteromedial tibia, 2nd–4th metatarsal shaft, fibula) tolerate relative rest.

Board pearl: A normal radiograph does not exclude a stress fracture in the first 2–3 weeks; MRI is the gold standard for early detection and grading severity.

Presentation Patterns and Key History

— Week 1–2: vague ache after running, resolves with rest

— Week 3–4: pain during the latter half of the run

— Week 5+: pain at onset of activity, then with walking, then at rest/night — night pain is a red flag

— Acute "pop" or sudden inability to bear weight suggests completion of fracture — urgent referral

— Training log: weekly mileage, recent % increase, terrain (track vs trail vs treadmill), shoe age (>500 mi reduces shock absorption)

— Cross-training, strength training, rest days

— Prior stress fractures (strongest predictor of next one)

— Nutrition: caloric intake vs expenditure, vegan/restrictive eating, calcium and vitamin D intake

— Menstrual history in female athletes: age at menarche, regularity, amenorrhea >3 months, OCP use masking amenorrhea

— Sleep, mood, body image, performance pressure (RED-S screen)

— Medications: glucocorticoids, SSRIs, PPIs, depot medroxyprogesterone, aromatase inhibitors

— Smoking, alcohol, energy drinks

— Groin or anterior thigh pain in a runner → femoral neck until proven otherwise

— Dorsal midfoot pain with limp → navicular (frequently missed, high nonunion risk)

— Lateral foot pain at 5th metatarsal base → Jones fracture risk

— Low back pain with extension in adolescent athlete → spondylolysis (pars)

— Insertional Achilles or plantar fascia pain at rest, morning stiffness → consider seronegative spondyloarthropathy

Classic timeline:

Targeted history checklist (Step 3 ambulatory visit):

Red flag features that change management:

Key distinction: Mechanical/overuse pain improves with rest and worsens predictably with the offending activity. Inflammatory pain is worse in the morning, improves with activity, and lasts >30 min of stiffness — think spondyloarthritis, not overuse, and pursue HLA-B27, sacroiliitis imaging, CRP.

Board pearl: Always ask female athletes the "triad questions" — menses, meals, mass (weight) — because low energy availability is the upstream driver that turns a training error into a stress fracture.

Physical Exam Findings

— Antalgic gait, shortened stance phase on the affected side

— Pes planus or pes cavus (cavus → 5th MT and femoral neck risk; planus → navicular and tibial risk)

— Leg-length discrepancy, Q-angle, foot pronation

— Muscle bulk asymmetry, calf atrophy in chronic Achilles tendinopathy

— Focal, reproducible point tenderness over bone is the hallmark of stress fracture

— Tendinopathy gives tenderness along the tendon, not bone

— MTSS: diffuse tenderness over distal two-thirds of posteromedial tibia >5 cm; stress fracture: focal <5 cm tender point

— Hop test: single-leg hop reproduces pain → suggests tibial or metatarsal stress fracture

— Fulcrum test: examiner's forearm under femur with downward pressure on knee → femoral shaft stress fracture

— Patrick/FABER and log roll: groin pain → femoral neck stress fracture; immediate orthopedic referral

— Stork test (single-leg hyperextension): unilateral low back pain → pars/spondylolysis

— Tuning fork (128 Hz) or therapeutic ultrasound over suspected site: pain elicited supports stress injury — sensitive but not specific

— Squeeze test of metatarsals, navicular "N-spot" tenderness (dorsal proximal navicular)

— Achilles: tender 2–6 cm above insertion (mid-substance) vs at calcaneus (insertional); thickened cord

— Patellar (jumper's knee): inferior pole patella tenderness, pain with single-leg decline squat

— Lateral epicondylosis: pain with resisted wrist extension, Cozen test

— Greater trochanteric pain: tender over gluteus medius insertion, single-leg stance >30 s reproduces pain

Inspection:

Palpation — the single most useful maneuver:

Provocative tests:

Tendinopathy-specific exam:

Hemodynamic / systemic check: Step 3 expects you to also screen for compartment syndrome in exertional leg pain — measure pulses post-exercise, look for paresthesias, tight compartments.

Step 3 management: If the exam shows groin pain + limited internal rotation + inability to bear weight, order hip MRI same day and make the patient non-weight-bearing on crutches before they leave the clinic — femoral neck stress fracture can displace.

Diagnostic Workup — Initial Labs and Imaging

— AP and lateral of suspected site; for foot include oblique

— Findings appear 2–6 weeks after symptom onset: periosteal reaction, cortical lucency, callus, "gray cortex sign"

— Sensitivity early on is only 15–35% — a normal film does not rule out injury

— Anterior tibial cortex "dreaded black line" (transverse lucency on lateral view) = high-risk, prone to complete fracture and nonunion

— CBC, CMP, TSH

— 25-OH vitamin D — target >30 ng/mL (some sports medicine experts push 40)

— Serum calcium, phosphate, magnesium, PTH

— Ferritin (iron deficiency very common in female runners)

— In females with menstrual dysfunction: FSH, LH, estradiol, prolactin, β-hCG

— In males with multiple stress fractures or low libido: morning total testosterone

— Celiac serology (tTG-IgA + total IgA) if GI symptoms or unexplained low BMD/iron

— ≥1 "high-risk" triad factor: low energy availability/eating disorder, BMI <17.5 or <85% expected weight, menarche >15, amenorrhea/oligomenorrhea, prior stress fracture, prior Z-score <–1

— In athletes, Z-score <–1.0 is considered low (not –2.5 as in general population) because weight-bearing athletes should have higher than average BMD

Imaging — start with plain radiographs:

When to obtain labs (ambulatory work-up of recurrent or high-risk stress fractures, or any athlete with red flags):

DEXA indications in athletes (ISCD/Female Athlete Triad Coalition):

ECG/biomarkers: generally not relevant unless screening for RED-S with bradycardia, orthostatic vitals, or evaluating syncope in a thin athlete with bradycardia → ECG to exclude prolonged QT from electrolyte/eating disorder pathology.

Board pearl: A Z-score of 0 in an elite distance runner is abnormally low — interpret BMD in athletes against the expected adaptive overshoot, not the general population.

CCS pearl: Order "X-ray, affected bone, 2 views" first; if negative and clinical suspicion remains, advance to MRI rather than repeating films.

Diagnostic Workup — Advanced and Confirmatory Studies

— Sensitivity and specificity >90% within days of symptom onset

— Detects marrow edema, periosteal edema, fracture line

— Fredericson grading (tibia) and similar systems guide return-to-play:

— Grade 1: periosteal edema only

— Grade 2: marrow edema on T2

— Grade 3: marrow edema on T1 and T2

— Grade 4: cortical fracture line

— Higher grade → longer rest, more imaging follow-up

— No radiation — preferred in adolescents and pregnant athletes

— Best for navicular, pars interarticularis, sesamoid, and tarsal coalition evaluation — defines cortical break and nonunion

— Useful when MRI shows edema but you need to confirm a fracture line or fragmentation

— Pars defect on CT confirms spondylolysis after suspicious SPECT/MRI

— Very sensitive but nonspecific (lights up with tumor, infection, arthritis)

— Largely replaced by MRI; still useful when MRI unavailable or for screening multifocal injuries

— SPECT improves spatial resolution for spondylolysis

— Excellent for tendinopathy, plantar fasciitis, bursitis: tendon thickening, hypoechoic areas, neovascularization on Doppler

— Can guide injections

— Not for bone

— Compartment pressures (Pedowitz criteria: pre-exercise >15, 1 min post >30, or 5 min post >20 mmHg) for chronic exertional compartment syndrome

— Nerve conduction studies if neurogenic pain suspected

— Vascular studies (ABI, exercise duplex) for popliteal artery entrapment

MRI — gold standard:

CT:

Bone scan (triple-phase Tc-99m):

Ultrasound:

Additional studies based on differential:

Key distinction: MTSS vs tibial stress fracture vs chronic exertional compartment syndrome — all cause shin pain in runners. MTSS = diffuse tenderness, pain at start that improves; stress fracture = focal tenderness, pain that worsens; CECS = tight, crampy pain at predictable distance, paresthesias, resolves within minutes of stopping.

Step 3 management: For suspected femoral neck stress fracture, MRI within 24–48 hours while patient is non-weight-bearing; if tension-side (superior cortex) lesion → urgent orthopedic surgery for percutaneous fixation.

Risk Stratification and First-Line Management Logic

— Femoral neck (superior/tension side)

— Patella (anterior)

— Anterior tibial cortex

— Medial malleolus

— Talus, navicular

— Proximal 5th metatarsal (Jones)

— Sesamoids of great toe

— Pars interarticularis (in adolescents, displacement risk)

— Management: non-weight-bearing, urgent ortho referral, often surgical fixation, prolonged immobilization (6–12+ weeks)

— Posteromedial tibia

— Fibula

— Femoral shaft (medial)

— 2nd–4th metatarsal shafts ("march fracture")

— Calcaneus, pubic rami

— Management: relative rest, protected weight bearing as tolerated, walking boot if needed, cross-train, return to sport in 6–8 weeks

1. Stop the offending activity (do not "run through it")

2. Pain control: acetaminophen preferred over NSAIDs acutely (theoretical concern NSAIDs impair bone healing — limit use in first 2 weeks)

3. Activity modification: pool running, cycling, elliptical, swimming to preserve aerobic fitness

4. Address modifiable risk factors: calcium 1000–1200 mg/day, vitamin D ≥800–1000 IU/day (more if deficient), caloric balance, sleep

5. Gait/biomechanical assessment, shoe replacement, orthotics if indicated

6. Graded return: pain-free walking → jogging → running, increase volume ≤10% per week

7. Physical therapy for strength, hip/core stability, running form

— Relative rest, load modification (not complete rest — tendons need progressive load)

— Eccentric exercise (Alfredson protocol for Achilles, decline squats for patellar) is first-line

— Adjuncts: shockwave therapy, PT, topical NSAIDs

— Avoid corticosteroid injection in Achilles and patellar tendons (rupture risk)

High-risk vs low-risk site framework drives every decision:

High-risk stress fractures (tensile side, watershed blood supply, high nonunion/displacement risk):

Low-risk stress fractures (compressive side, good blood supply):

General management ladder for low-risk injuries:

Overuse tendinopathy ladder:

CCS pearl: For a recreational runner with focal posteromedial tibial tenderness and normal X-ray, order "MRI tibia without contrast," prescribe walking boot, refer to PT, and schedule follow-up in 4 weeks — that is the canonical Step 3 ambulatory sequence.

Pharmacotherapy — First-Line Regimens

— Acetaminophen 650–1000 mg q6h PRN (max 3 g/day in most adults, 2 g if hepatic risk) — first-line for stress fractures because of bone healing concerns with NSAIDs

— NSAIDs (ibuprofen 400–600 mg q6h, naproxen 500 mg BID) acceptable for tendinopathy and MTSS; avoid prolonged use (>2 weeks) in stress fractures

— Topical diclofenac 1% gel — good for superficial tendinopathy with fewer systemic effects, preferred in elderly

— Opioids essentially never indicated for overuse injury

— Vitamin D: if 25-OH D <20 → 50,000 IU weekly × 8 weeks then 1000–2000 IU/day; if 20–30 → 1000–2000 IU/day; goal >30 ng/mL

— Calcium: dietary preferred, 1000–1200 mg/day total; supplement only if intake inadequate

— Military trial data: calcium 2000 mg + vitamin D 800 IU daily reduced stress fracture incidence by 20% in female recruits — common board fact

— Bisphosphonates not recommended in young female athletes (teratogenic potential, prolonged half-life)

— In postmenopausal women with stress fracture + osteoporosis: alendronate 70 mg weekly or zoledronate 5 mg IV yearly per usual osteoporosis guidelines

— Consider endocrinology referral

— Nonpharmacologic restoration of menses through increased energy availability is first-line (additional 300–500 kcal/day, reduced training load)

— Combined oral contraceptives do NOT restore bone density and may mask the underlying problem — guideline-discouraged for treating triad-related amenorrhea

— Transdermal estradiol + cyclic progesterone has some evidence in selected refractory cases; coordinate with sports endocrinology

— Corticosteroid injections: limited role; useful for short-term pain in lateral epicondylosis and trochanteric bursitis but worse long-term outcomes than PT

— Avoid in Achilles and patellar tendons — rupture risk

— PRP and prolotherapy — mixed evidence; not first-line on boards

Analgesia:

Bone health pharmacology:

Recurrent or high-risk osteoporosis-related stress fractures:

Hormonal management in Female Athlete Triad / RED-S:

Tendinopathy adjuncts:

Board pearl: The Step 3 "wrong answer" trap is prescribing OCPs to a young amenorrheic runner with a stress fracture to "fix her bones." Correct answer: increase caloric intake, decrease training, treat the energy deficit.

Procedural and Surgical Management

— Femoral neck (tension/superior side): urgent percutaneous cannulated screw fixation

— Femoral neck (compression/inferior side) with >50% width of cortex involved or failure of conservative care

— Anterior tibial cortex "dreaded black line" failing 3–6 months conservative care: intramedullary nailing or drilling

— Navicular complete fracture or persistent symptoms: percutaneous screw fixation

— Proximal 5th metatarsal (Jones, zone 2): intramedullary screw fixation, especially in competitive athletes (faster return to play, lower nonunion vs cast)

— Sesamoid nonunion: bone grafting or sesamoidectomy

— Medial malleolus with fracture line: ORIF

— Patella: tension band wiring

— Pars interarticularis with persistent pain and pseudoarthrosis: direct pars repair or fusion

— Walking boot (CAM boot) 4–6 weeks for most low-risk stress fractures

— Short-leg cast for high-risk foot fractures if patient noncompliant

— Pneumatic leg brace (Aircast) for tibial stress fractures — shortens return to running by ~3 weeks vs no brace

— Crutches with non-weight-bearing for femoral neck and navicular pending surgery

— Extracorporeal shockwave therapy (ESWT): evidence in plantar fasciitis, lateral epicondylosis, calcific tendinopathy of the shoulder, recalcitrant Achilles tendinopathy

— Ultrasound-guided percutaneous tenotomy/needle tenotomy for chronic tendinosis

— PRP injection: moderate evidence for lateral epicondylosis, patellar tendinopathy; insurance often won't cover (Step 3 value-based care nuance)

— Fasciotomy for chronic exertional compartment syndrome failing conservative care

— Surgical release for popliteal artery entrapment syndrome or iliotibial band in refractory cases

Indications for surgical intervention in stress fractures:

Conservative immobilization protocols:

Procedures for overuse soft-tissue injury:

CCS pearl: A 19-year-old female collegiate runner with groin pain, positive log roll, MRI showing superior femoral neck edema with fracture line — order non-weight-bearing, orthopedic surgery consult, NPO, type and screen, admit — this is a surgical emergency on the order timeline.

Board pearl: Jones fracture in a competitive athlete = screw fixation; in a sedentary patient, non-weight-bearing cast is acceptable but has 25% nonunion rate.

Special Populations — Elderly and Renal/Hepatic Impairment

— Stress fractures occur with lower training loads because of decreased BMD, sarcopenia, slower bone remodeling

— Pelvic and sacral insufficiency fractures are uniquely common — present as low back/buttock/groin pain after new walking program, often missed

— Pubic ramus, femoral neck, vertebral compression — order MRI pelvis if X-ray negative

— All elderly patients with insufficiency fractures need DEXA and osteoporosis evaluation (Step 3 owns this — secondary fracture prevention is a core ambulatory measure)

— Screen for secondary causes: hyperparathyroidism, multiple myeloma (SPEP/UPEP, free light chains), vitamin D deficiency, hypogonadism, glucocorticoid use, malabsorption

— Avoid prolonged NSAIDs: GI bleed, AKI, hypertension worsening, heart failure exacerbation, drug interactions (anticoagulants, ACEi/ARB + diuretic "triple whammy")

— Acetaminophen max 3 g/day in elderly, 2 g in hepatic impairment

— Topical diclofenac preferred for localized pain

— Falls risk assessment before prescribing anything sedating

— NSAIDs contraindicated when eGFR <30, use caution at eGFR 30–60

— Calcium and phosphate management is more complex in CKD — coordinate with nephrology; avoid empiric high-dose calcium in CKD 4–5 (vascular calcification risk)

— Bisphosphonates: alendronate avoid if eGFR <35; denosumab acceptable in CKD but watch for hypocalcemia

— Vitamin D: in advanced CKD, use activated forms (calcitriol, paricalcitol) under nephrology

— Acetaminophen max 2 g/day; avoid in active alcohol use disorder

— Avoid NSAIDs in cirrhosis (variceal bleed risk, hepatorenal physiology)

— Adjust opioid dosing if used (rarely indicated here)

Elderly athletes (masters athletes, "weekend warriors"):

Pharmacology adjustments in elderly:

Renal impairment:

Hepatic impairment:

Key distinction: Insufficiency fractures (normal stress on abnormal bone, e.g., osteoporotic elderly) vs fatigue fractures (abnormal stress on normal bone, e.g., recruits and runners). Both are "stress fractures" but the workup priorities differ — insufficiency triggers metabolic bone work-up; fatigue triggers training/nutrition work-up.

Step 3 management: In a 72-year-old woman with sacral insufficiency fracture, start vitamin D + calcium, order DEXA, evaluate for osteoporosis pharmacotherapy, and schedule a falls assessment before discharge — these are all measured quality metrics.

Special Populations — Pregnancy, Pediatrics, and Other Subgroups

— Open physes change the pathology: instead of stress fractures, kids get apophysitis at traction sites

— Osgood-Schlatter (tibial tubercle)

— Sinding-Larsen-Johansson (inferior patella)

— Sever disease (calcaneal apophysis)

— Little Leaguer's elbow (medial epicondyle) and shoulder (proximal humeral physis)

— Iselin (5th MT base apophysis)

— Management: relative rest, ice, stretching, activity modification — almost always self-limited at skeletal maturity

— Salter-Harris stress injuries of the physis can cause growth arrest — get imaging if symptoms persist

— Spondylolysis is the most common cause of low back pain in adolescent athletes — order MRI or limited CT/SPECT; brace + activity modification for 3 months

— Always screen for Female Athlete Triad/RED-S in adolescent female athletes; nutrition and menstrual history are mandatory

— Pubic ramus and sacral stress fractures can occur in pregnancy/postpartum, especially with breastfeeding (transient lactational bone loss)

— Imaging: MRI without gadolinium preferred; avoid CT and bone scan

— Avoid NSAIDs especially after 20 weeks (oligohydramnios) and at ≥30 weeks (premature ductus closure) — ACOG/FDA guidance

— Acetaminophen is safe; bisphosphonates contraindicated

— Continue exercise per ACOG — encourage modified low-impact activity

— Stress fractures peak in first 6–8 weeks of basic training

— Tibia and metatarsals most common; femoral neck most morbid

— Evidence-based prevention: calcium 2000 mg + vitamin D 800 IU daily, graduated training, shock-absorbing insoles

— Unique sites: 2nd metatarsal base (Lisfranc area), pars, sesamoids, posterior ankle os trigonum

— High prevalence of RED-S

Pediatric and adolescent athletes:

Pregnant athletes:

Military recruits:

Dancers, gymnasts:

Board pearl: A 14-year-old gymnast with low back pain worse with extension, positive stork test → MRI lumbar spine (preferred over CT in adolescents to limit radiation) looking for pars stress injury — treat with activity cessation and TLSO brace for 3 months.

Key distinction: Bone pain in adolescents at traction apophyses = apophysitis (benign); bone pain at midshaft or articular sites with night pain, B symptoms = think osteoid osteoma, osteosarcoma, Ewing — image and refer.

Complications and Adverse Outcomes

— Fracture completion and displacement: most feared in femoral neck (avascular necrosis of femoral head, lifelong disability), navicular, anterior tibia

— Avascular necrosis: femoral head, talus, scaphoid (analogous principle in upper extremity)

— Nonunion: navicular, anterior tibial cortex, 5th MT Jones, sesamoids — sites with watershed blood supply

— Malunion with chronic pain and altered biomechanics

— Chronic regional pain syndrome (CRPS) — disproportionate pain, allodynia, autonomic changes after immobilization

— DVT from prolonged immobilization, especially in lower extremity casting — consider prophylaxis in patients with additional VTE risk factors (OCPs, smoking, prior VTE, malignancy)

— Disuse osteopenia of the affected limb

— Muscle atrophy and proprioceptive deficits

— Recurrence: prior stress fracture is the strongest predictor — up to 60% in untreated triad

— Progression to early osteoarthritis at adjacent joints (especially navicular, talar, sesamoid injuries)

— Persistent BMD deficit in athletes who never address energy availability

— Career-ending injury in elite athletes — psychological morbidity

— Tendon rupture (Achilles, patellar) especially after steroid injection or fluoroquinolone use

— Chronic pain with central sensitization

— Compensatory injuries on the contralateral limb

— Cardiovascular: bradycardia, hypotension, prolonged QT, sudden cardiac death

— Endocrine: hypothalamic amenorrhea, hypothyroidism (low T3 syndrome), low cortisol pattern

— Hematologic: anemia (iron deficiency)

— GI: gastroparesis, constipation

— Psychiatric: depression, anxiety, eating disorders

— Bone: stress fractures, premature osteoporosis

— Immune: increased infections, impaired wound healing

Acute complications:

Subacute complications:

Long-term complications:

Tendinopathy complications:

RED-S systemic complications (board favorite):

Step 3 management: In a young female athlete with second stress fracture in 12 months, do not just treat the bone — screen for eating disorder (SCOFF, EAT-26), order DEXA, check ferritin and vitamin D, refer to sports nutritionist, multidisciplinary triad clinic. Recurrence after isolated bone-focused care is the trap.

Board pearl: Femoral neck stress fracture missed in clinic that displaces is a classic malpractice and exam scenario — the lesson is to make any runner with groin pain non-weight-bearing pending MRI.

When to Escalate — Referral, Consult, and Inpatient Triage

— Femoral neck stress fracture, especially tension side or any cortical break

— Displaced or complete stress fracture at any site

— Navicular stress fracture with cortical break

— Pars interarticularis with neurologic findings

— Acute Achilles or patellar tendon rupture

— Suspected septic joint or osteomyelitis mimicking overuse pain

— Any high-risk stress fracture

— Stress fracture not improving after 4–6 weeks of appropriate conservative care

— Recurrent stress fractures at the same site

— Refractory tendinopathy after 3 months of PT and load management

— Sports nutritionist/dietitian: all athletes with RED-S risk, recurrent fractures, low BMD

— Endocrinology: low BMD with secondary causes, hypogonadism, refractory amenorrhea, men with multiple stress fractures

— Mental health/eating disorder specialist: positive SCOFF/EAT-26 screen, suspected anorexia or bulimia

— Physical therapy: essentially all overuse injuries

— Gait/biomechanics lab or podiatry: recurrent foot/lower limb injuries, structural foot abnormalities

— Rheumatology: if inflammatory features suggest spondyloarthritis or seronegative disease

— Hemodynamic instability or syncope in suspected RED-S/eating disorder with bradycardia <40, electrolyte derangement, refeeding risk

— Acute femoral neck or pelvic fracture requiring surgical fixation

— Suspected pathologic fracture (concern for malignancy, multiple myeloma)

— Septic arthritis or osteomyelitis in differential — admit for IV antibiotics after blood cultures

Same-day orthopedic surgery referral (urgent, often inpatient):

Routine orthopedic/sports medicine referral within 1–2 weeks:

Multidisciplinary referrals (Step 3 ambulatory framework):

Inpatient triage criteria:

CCS pearl: A teenage runner with BMI 15.5, HR 38, K 2.9, three stress fractures in a year — order "admit to medicine, telemetry, nutrition consult, psychiatry consult, slow refeeding protocol, monitor phosphate." This is not orthopedics-first; it is medical stabilization first.

Key distinction: Sports medicine specialist vs orthopedic surgeon — refer to sports medicine for diagnosis, conservative management, rehab planning; refer to orthopedic surgery when you anticipate operative intervention or need urgent fixation.

Key Differentials — Same Category (Musculoskeletal Overuse)

— Stress reaction (no cortical break) vs stress fracture (cortical break) — both on the same MRI continuum

— Bone bruise/contusion — acute traumatic, not insidious

— Osteitis pubis (pubic symphysis stress reaction in soccer players, runners) — bilateral pubic tenderness, X-ray with symphyseal sclerosis

— Achilles tendinopathy: mid-substance (2–6 cm above insertion) vs insertional (with Haglund deformity, calcaneal spur)

— Patellar tendinopathy (jumper's knee): inferior pole patella

— Quadriceps tendinopathy: superior pole patella

— Iliotibial band syndrome: lateral knee pain, positive Ober and Noble compression tests — friction syndrome, not tendinopathy

— Lateral epicondylosis (tennis elbow), medial epicondylosis (golfer's elbow)

— Rotator cuff tendinopathy/impingement, biceps tendinopathy

— De Quervain tenosynovitis — positive Finkelstein test

— Trigger finger (stenosing tenosynovitis)

— Plantar fasciitis — heel pain worst with first steps in morning, improves with activity then worsens late day

— Medial tibial stress syndrome (MTSS, "shin splints") — periostitis along distal posteromedial tibia

— Greater trochanteric pain syndrome, pes anserine bursitis, retrocalcaneal bursitis, olecranon bursitis, prepatellar bursitis ("housemaid's knee")

— Chronic exertional compartment syndrome (anterior compartment of leg most common)

— Popliteal artery entrapment syndrome — calf claudication in young athlete with diminished pulse on plantarflexion

— Tarsal tunnel syndrome, Morton neuroma (3rd web space, click on Mulder), meralgia paresthetica (lateral cutaneous nerve of thigh in cyclists, tight clothing)

— Cervical/lumbar radiculopathy mimicking shoulder or hip overuse

Within-MSK differentials must distinguish bone, tendon, fascia, muscle, and nerve:

Bone overuse:

Tendon overuse:

Fascia/enthesis:

Bursitis:

Compartment and vascular:

Nerve:

Key distinction: MTSS vs tibial stress fracture vs CECS — the classic Step 3 triad of shin pain. Tenderness pattern (diffuse vs focal), pain timing (start, predictable distance, persistent), and provocative testing differentiate them; MRI for stress fracture, compartment pressures for CECS, clinical diagnosis for MTSS.

Board pearl: When you can localize tenderness to a single fingertip-sized spot on bone in a runner, the answer on Step 3 is stress fracture until imaging proves otherwise — even when MTSS feels likely.

Key Differentials — Other Categories

— Osteoid osteoma: young patient, night pain dramatically relieved by NSAIDs/aspirin, classic nidus on CT with surrounding sclerosis — mimics stress fracture

— Osteosarcoma: adolescents, distal femur/proximal tibia, sunburst periosteal reaction, elevated ALP

— Ewing sarcoma: diaphysis, onion-skin periosteal reaction, B symptoms

— Metastatic disease: older adults with breast/prostate/lung/kidney/thyroid primary — order skeletal survey, SPEP, PSA

— Multiple myeloma: elderly with bone pain, anemia, renal failure, hypercalcemia — punched-out lytic lesions

— Osteomyelitis: indolent in adults, may mimic stress reaction; fever, elevated ESR/CRP, MRI with bone marrow edema and abscess

— Septic arthritis: acutely red, hot, painful joint — arthrocentesis

— Tuberculosis or fungal osteomyelitis in immigrants/immunocompromised

— Ankylosing spondylitis and other spondyloarthropathies: young patient with insidious low back pain, morning stiffness >30 min, improves with activity, alternating buttock pain, HLA-B27, enthesitis at Achilles or plantar fascia mimicking overuse tendinopathy

— Reactive arthritis after GU/GI infection

— Psoriatic arthritis: dactylitis, nail changes

— Rheumatoid arthritis: symmetric small joint, MCP/PIP, morning stiffness

— Osteomalacia (vitamin D deficiency, Looser zones on X-ray) — diffuse bone pain in patients with malabsorption, bariatric surgery, dark skin, veiled clothing

— Hyperparathyroidism: hypercalcemia, subperiosteal resorption

— Paget disease: older adults, elevated ALP, bowing tibia, mixed lytic-sclerotic

— Hypophosphatemic rickets, fibrous dysplasia — rare but classic exam answers

— Lumbar radiculopathy presenting as hip/thigh pain

— Hip OA referring to knee

— Visceral pain (renal stones, AAA, ectopic pregnancy) referred to back/groin

— Peripheral arterial disease in older patients with exertional calf pain — ABI <0.9

— Deep vein thrombosis — calf pain with swelling, Wells score

Tumor (always on the Step 3 differential for bone pain):

Infection:

Inflammatory/rheumatologic:

Metabolic/endocrine:

Neuropathic and referred:

Vascular:

Key distinction: Night pain awakening the patient from sleep, B symptoms, weight loss, or pain unrelieved by rest should redirect from overuse to tumor/infection — order ESR, CRP, CBC, and advanced imaging before assuming overuse.

Step 3 management: Adolescent with night pain dramatically relieved by ibuprofen — order CT, not just MRI, because osteoid osteoma is the diagnosis and CT shows the nidus.

Secondary Prevention and Long-Term Plan

— Re-introduce activity gradually with ≤10% increase in weekly volume

— At least one rest day per week

— Rotate surfaces (avoid concrete-only), replace running shoes every 300–500 miles

— Cross-train: cycling, swimming, elliptical to offload impact while maintaining fitness

— Strength training 2×/week: hip abductors, gluteals, core (the #1 modifiable factor for runners)

— Calcium 1000–1200 mg/day, dietary first

— Vitamin D ≥800–1000 IU/day, dose to achieve 25-OH D >30 ng/mL

— Adequate total energy intake — minimum 45 kcal/kg fat-free mass/day in athletes

— Adequate protein 1.2–1.6 g/kg/day

— Treat iron deficiency (ferritin goal >30–50 in athletes)

— Smoking cessation, alcohol moderation (both impair bone)

— Multidisciplinary team: primary care/sports medicine, sports dietitian, mental health, coach/athletic trainer

— Goal: restore menses through energy availability ≥45 kcal/kg FFM/day

— Monitor BMD every 1–2 years

— Avoid OCPs as monotherapy for bone health

— Coach education to remove "leanness as performance" messaging

— Continue eccentric loading program for at least 12 weeks even after symptom resolution

— Progressive return to sport-specific loading

— Identify and correct biomechanical contributors

— Custom orthotics for pes cavus/planus with recurrent injuries

— Stability shoes for overpronators; neutral cushioned for high-arched

— Avoid minimalist shoes during return to sport phase

— Start anti-resorptive therapy if T-score ≤–2.5 or FRAX above threshold (major osteoporotic ≥20% or hip ≥3%)

— Fall prevention: vision check, home safety, balance training

— Reassess BMD in 2 years

— Influenza, COVID, Tdap, shingles, pneumococcal per age

Address the underlying training error (universal):

Bone health optimization (long-term):

Female Athlete Triad / RED-S long-term plan:

Tendinopathy long-term:

Footwear and orthotics:

In postmenopausal women with insufficiency stress fracture:

Vaccination/general prevention reminders at follow-up visits (Step 3 owns longitudinal care):

Board pearl: The single highest-yield prevention intervention for a runner with a first low-risk stress fracture is structured graded return-to-running with PT supervision and ≤10%/week progression, not just rest and time.

Step 3 management: Document all of these elements in the discharge plan — Step 3 vignettes reward the answer that addresses bone, biomechanics, and behavior, not just immobilization.

Follow-Up, Monitoring, and Rehab Counseling

— 2 weeks: confirm pain decreasing, symptom diary review, training cessation adherence, walking boot fit

— 4 weeks: clinical exam — point tenderness resolving? hop test painless? Begin pool running and stationary biking if pain-free

— 6–8 weeks: repeat imaging only if symptoms persist (MRI for grading, not routine plain films — callus may take longer than symptoms)

— 8–12 weeks: graded return to running protocol begins once pain-free walking ≥30 min and no point tenderness on bone

— 3 months: full sport participation possible for most low-risk injuries; high-risk often 4–6 months

— 6–12 months: re-screen for triad factors, repeat DEXA if abnormal at baseline

— Walk-jog intervals 1:4 (1 min jog, 4 min walk) × 20 min, alternate days

— Progress to 2:3, 3:2, 4:1, then continuous jogging

— Add distance before adding speed

— No two consecutive running days initially

— Stop and reassess if pain returns

— Symptom log: pain location, intensity, timing relative to activity

— Weekly training volume and intensity

— Menstrual calendar in female athletes

— Daily weight in eating disorder recovery (per program)

— Sleep duration, mood, energy

— Repeat 25-OH vitamin D in 3 months after replacement

— Repeat DEXA in 1–2 years if low at baseline

— Pain that returns during graded return = step back two levels, not stop completely

— Cross-training preserves cardiovascular fitness — VO2max drops ~7% after 2 weeks of detraining

— Address the psychological burden of forced rest — refer to sport psychologist if needed

— Reinforce that bone remodeling continues for 3–6 months after symptoms resolve — early return causes recurrence

— BMD evaluation in patients with fragility/insufficiency fracture

— Vitamin D and calcium counseling documented

— Falls assessment in elderly

— Tobacco cessation counseling

— Smoking, depression screening

Follow-up cadence (ambulatory Step 3 timeline):

Return-to-running protocol (board-favored structure):

Monitoring parameters:

Counseling points:

Quality measures Step 3 likes:

CCS pearl: Schedule the next follow-up before the patient leaves the visit — Step 3 cases reward you for scheduling appropriate intervals (2-week boot check, 6-week reimaging if symptomatic, 3-month return-to-play clearance).

Ethical, Legal, and Patient Safety Considerations

— The physician's primary duty is to the patient, not the team, coach, or parent

— Returning an athlete to play before bone healing risks completion of fracture and permanent disability — clear documented refusal of clearance is appropriate even under pressure

— "Sideline pressure" from coaches/agents/families is a classic Step 3 ethics scenario — the answer is always patient safety first

— Adolescent athletes' menstrual history, eating habits, and body image concerns are confidential in most states; parents may not need to be informed of all details, but suspected eating disorders with medical instability often require disclosure for safety

— Know your state's adolescent confidentiality laws

— Encourage but don't force family involvement when possible

— Suspected abuse (physical, sexual, emotional) in young athletes — mandatory reporter in all states

— High-profile examples (USA Gymnastics) emphasize that physicians must report rather than defer to institutions

— Hazing injuries or coercive training practices may rise to reportable abuse

— Surgical fixation in a minor: parental consent + adolescent assent

— Off-label PRP or shockwave therapy: discuss limited evidence, cost (often not covered — Step 3 health systems point), and reasonable alternatives

— Corticosteroid injection in tendinopathy: discuss rupture risk explicitly

— Severe anorexia with medical instability may impair decision-making capacity — involuntary admission criteria vary by state

— Refeeding syndrome risk: monitor phosphate, magnesium, potassium; advance calories slowly

— Coordinate with psychiatry

— Athletes seen in urgent care, ER, or while traveling for competitions are at risk of lost follow-up — explicitly arrange follow-up with their home sports medicine clinician

— Discharge summary should specify weight-bearing status, follow-up date, red-flag return precautions

— Imaging results returning after the visit (e.g., MRI showing femoral neck fracture in a patient sent home walking) require direct provider-to-patient contact within 24 hours and updated weight-bearing instructions — failure here is a documented safety event

— Counsel athletes on WADA-banned substances in over-the-counter supplements; recommend NSF Certified for Sport products

Pre-participation clearance and "fitness to play":

Confidentiality and the minor athlete:

Mandatory reporting:

Informed consent edge cases:

Eating disorder care and capacity:

Transition-of-care risk (Step 3 favorite):

Doping and supplements:

Board pearl: When a coach pressures you to clear a player with an unhealed femoral neck stress fracture for the championship game, the answer is decline to clear, document the conversation, and notify the athletic trainer in writing — never split the difference on a fracture that can displace.

High-Yield Associations and Rapid-Fire Facts

— Tibia (posteromedial) → distance runner

— Anterior tibial "dreaded black line" → jumping athletes, ballet

— Navicular → sprinters, hurdlers, basketball

— 5th MT (Jones) → cutting sports, basketball, football

— 2nd MT (march fracture) → military recruits, dancers

— Sesamoid → runners, dancers en pointe

— Femoral neck → distance runners, military

— Pubic ramus → female distance runners, postpartum

— Pars interarticularis → gymnasts, divers, football linemen, dancers

— Rib (1st) → rowers, baseball pitchers

— Ulnar shaft → softball pitchers, tennis

— Olecranon → throwers

— Coracoid → trap shooters

— Low energy availability → hypothalamic amenorrhea → low estrogen → low BMD → stress fracture

— OCPs do NOT restore BMD in hypothalamic amenorrhea

— Z-score, not T-score, in premenopausal athletes

— Calcium 1000–1200 + vitamin D 800–1000 daily reduces military stress fracture risk

— Glucocorticoids, PPIs (long-term), SSRIs, depot medroxyprogesterone, anticonvulsants (phenytoin, carbamazepine), aromatase inhibitors, GnRH agonists, heparin (long-term), thiazolidinediones, excessive thyroid replacement

— Eccentric exercise = first-line

— Steroids: NO in Achilles and patellar, OK short-term in lateral epicondyle

— Fluoroquinolones → Achilles tendinopathy/rupture, especially with concurrent steroids and age >60

— Plain films: 2–6 weeks delay, low sensitivity early

— MRI: gold standard for stress injury

— CT: best for pars, navicular, sesamoid, nonunion

— Bone scan: sensitive, nonspecific, replaced by MRI

— Female Athlete Triad / RED-S: energy, menses, bone

— Osgood-Schlatter: tibial tubercle apophysitis in adolescents

— Sever: calcaneal apophysitis 8–14 yo

— Little League shoulder: proximal humeral physis

— Jersey finger: FDP avulsion, ring finger

— Mallet finger: extensor tendon disruption

— 10% rule for weekly mileage

— Shoe replacement at 300–500 miles

— Vitamin D goal >30 ng/mL

— Z-score <–1 = low BMD in athletes

Site → classic athlete:

Triad/RED-S core associations:

Drug-induced bone risk:

Tendinopathy quick hits:

Imaging quick reference:

Special syndromes:

Prevention numbers to memorize:

Board pearl: "Female runner, missed periods, stress fracture" is the single most repeated Step 3 sports medicine stem — and the correct intervention is increase calories, decrease training, not OCPs.

Board Question Stem Patterns

— 22-year-old female marathoner, 3 weeks of insidious groin pain worse with running, normal hip X-ray, point tenderness on log roll. Next step?

— Answer: MRI of the hip, non-weight-bearing with crutches — not "trial of NSAIDs" or "return in 4 weeks"

— 19-year-old cross-country runner, BMI 17.5, last menses 8 months ago, second tibial stress fracture in 18 months. Most appropriate management?

— Answer: increase caloric intake and reduce training; refer to dietitian and consider eating disorder evaluation — NOT "start oral contraceptives" or "start alendronate"

— Runner with diffuse posteromedial tibial tenderness over a 6 cm region, pain at start of run that improves, normal X-ray. Diagnosis?

— Answer: medial tibial stress syndrome (focal <5 cm tenderness with pain worsening through run = stress fracture; tight crampy pain with paresthesias at predictable distance = CECS)

— Ballet dancer with anterior shin pain, lateral X-ray shows transverse anterior cortical lucency. Management?

— Answer: orthopedic referral for likely surgical management (IM nail or drilling); prolonged conservative care has high failure

— 16-year-old with night pain in proximal femur, dramatically relieved by ibuprofen, no training history. Best test?

— Answer: CT (shows nidus); NOT a stress fracture

— 14-year-old gymnast, unilateral low back pain with extension, positive stork test. Best imaging?

— Answer: MRI lumbar spine (or limited CT) for pars; treat with activity cessation ± bracing

— 74-year-old with new buttock pain after starting walking program, sacral edema on MRI. Next steps?

— Answer: DEXA, vitamin D, calcium, start osteoporosis pharmacotherapy if T ≤–2.5, falls assessment

— 50-year-old with 3 months of mid-Achilles pain, thickened tendon. Best initial treatment?

— Answer: eccentric heel-drop exercise program (Alfredson protocol) — NOT corticosteroid injection (rupture risk)

— Collegiate basketball player with lateral foot pain, X-ray shows transverse fracture at proximal 5th metatarsal metaphyseal-diaphyseal junction. Best management?

— Answer: intramedullary screw fixation (in competitive athlete) vs non-weight-bearing cast (sedentary, with informed nonunion risk)

— Coach asks you to clear an athlete with an unhealed high-risk stress fracture. Best response?

— Answer: decline clearance, document reasoning, communicate with athletic trainer and family

Stem type 1: "The femoral neck trap"

Stem type 2: "The female athlete triad"

Stem type 3: "Distinguishing shin pain"

Stem type 4: "The dreaded black line"

Stem type 5: "Osteoid osteoma masquerader"

Stem type 6: "Adolescent low back pain"

Stem type 7: "Insufficiency fracture in the elderly"

Stem type 8: "Tendinopathy management"

Stem type 9: "Jones fracture"

Stem type 10: "Coach pressure ethics"

Board pearl: When the stem mentions groin pain + runner + normal X-ray, the only correct next step is MRI + non-weight-bearing — every other answer is a distractor.

One-Line Recap

Stress fractures and overuse injuries arise when bone or tendon repair cannot keep up with cumulative load, and Step 3 management hinges on locating the injury (high-risk sites need urgent MRI, non-weight-bearing, and surgical consult; low-risk sites need relative rest, graded return, and biomechanical correction), addressing the upstream driver (training error, energy deficit, Female Athlete Triad/RED-S, vitamin D and calcium deficiency, biomechanical contributors), and arranging structured follow-up rather than just immobilizing the limb.

High-risk sites you must memorize: femoral neck (tension side), anterior tibial cortex, medial malleolus, navicular, talus, sesamoids, proximal 5th metatarsal (Jones), patella, pars interarticularis — all need MRI, non-weight-bearing, and orthopedic referral, often surgical fixation.

Low-risk sites (posteromedial tibia, fibula, 2nd–4th MT shafts, femoral shaft, calcaneus, pubic rami): relative rest, walking boot, PT, return to running with the 10% rule, full recovery in 6–12 weeks.

Female Athlete Triad / RED-S = energy + menses + bone; treat the energy deficit first, never use OCPs as the bone fix, screen with DEXA (Z-score <–1 is low in athletes), and assemble a multidisciplinary team (dietitian, mental health, coach).

Tendinopathy = failed healing, not inflammation: first-line is eccentric loading, not steroids; avoid corticosteroid injection in Achilles and patellar tendons (rupture risk); fluoroquinolones potentiate Achilles rupture, especially in elderly on steroids.

Step 3 management pearl: Every ambulatory visit for overuse injury should document the training error, the biomechanical contributor, the bone-health work-up (vitamin D, calcium, triad screen), the return-to-activity timeline, and the follow-up date — that complete package is the consistent right answer pattern across vignettes.