Musculoskeletal

Osteoarthritis: outpatient management and joint replacement referral

Clinical Overview and When to Suspect Osteoarthritis

— Leading cause of chronic disability in US adults; affects >32 million Americans

— Knee OA prevalence rises sharply after age 45; hip OA somewhat later

— Women > men after age 55, especially hand and knee OA

— Age (strongest non-modifiable factor)

— Obesity (BMI ≥30 increases knee OA risk ~4×; modifiable — central to outpatient counseling)

— Prior joint injury (ACL tear, meniscectomy → post-traumatic OA)

— Occupational repetitive loading (squatting, kneeling, heavy lifting)

— Female sex, family history (especially nodal hand OA)

— Malalignment (varus/valgus knee), quadriceps weakness

— Adult ≥45 with activity-related joint pain that improves with rest

— Morning stiffness <30 minutes (vs. >1 hour in inflammatory arthritis)

— Insidious onset over months to years

— Functional complaints: difficulty with stairs, rising from chair, opening jars, walking distance

Board pearl: ACR clinical criteria allow diagnosis of knee OA without imaging in a patient ≥45 with activity-related joint pain and ≤30 minutes of morning stiffness. Step 3 stems often punish reflexive ordering of MRI or labs in straightforward OA — start with history, exam, and a weight-bearing plain film only if needed.

Definition: Osteoarthritis (OA) is a chronic, progressive joint disorder characterized by cartilage loss, subchondral bone remodeling, osteophyte formation, and low-grade synovitis — not a "wear and tear" passive process but an active failure of joint homeostasis.

Epidemiology (high-yield for Step 3):

Major risk factors:

When to suspect OA in clinic:

Most commonly affected joints: Knees, hips, hands (DIPs > PIPs > 1st CMC), cervical and lumbar spine, 1st MTP — MCPs, wrists, elbows, ankles, and shoulders are spared (their involvement should prompt search for alternate diagnosis).

Presentation Patterns and Key History

— Pain worsened by activity/weight-bearing, relieved by rest (later: pain at rest and at night signals advanced disease)

— Stiffness that is brief (<30 min), worst in the morning and after inactivity ("gelling phenomenon")

— Functional limitation disproportionate to inflammation

— Knee OA: medial compartment most common (genu varum); pain on stairs (especially descending), buckling, catching, effusions after activity

— Hip OA: groin pain referred to anterior thigh or knee (lateral hip pain → think trochanteric bursitis or gluteal tendinopathy instead); difficulty putting on socks/shoes, decreased internal rotation early

— Hand OA: Heberden nodes (DIP) and Bouchard nodes (PIP); thumb base (1st CMC) pain with pinching, opening jars; "squaring" of the thumb base

— Spine OA (spondylosis): axial pain, stiffness, may cause radiculopathy or neurogenic claudication if facet hypertrophy contributes to spinal stenosis

— 1st MTP (hallux rigidus): pain on toe-off

— Systemic symptoms (fever, weight loss, fatigue) → infectious or inflammatory etiology

— Prolonged morning stiffness >1 hour, symmetric small-joint involvement → rheumatoid arthritis

— Nocturnal rest pain, monoarticular hot swollen joint → septic arthritis, crystal disease, malignancy

— History of psoriasis, IBD, uveitis, urethritis → spondyloarthropathy

— Pain scale, distance walked, stairs, ADLs, work impact, sleep disruption

— WOMAC or KOOS scores quantify hip/knee function and track response

Step 3 management: A focused functional history (what the patient can no longer do) drives shared decision-making about escalation — including the eventual referral for joint replacement when conservative therapy fails and quality of life is impaired. Document baseline function at every visit.

Cardinal symptom triad:

Joint-specific presentation patterns:

Red-flag history items to screen for alternatives:

Functional assessment (Step 3 priority):

Physical Exam Findings

— Bony enlargement, deformity, varus (bow-legged) or valgus knee alignment

— Heberden (DIP) and Bouchard (PIP) nodes; squaring at 1st CMC

— Quadriceps atrophy in chronic knee OA (key driver of functional decline — targets rehab)

— Antalgic gait, Trendelenburg gait (hip OA with abductor weakness)

— Bony tenderness along joint line (medial > lateral in knee OA)

— Crepitus with passive ROM — coarse, palpable, often audible

— Cool, non-inflammatory effusions when present (vs. warm, tense effusion of septic/crystal arthritis)

— Absence of warmth and erythema (presence should prompt arthrocentesis)

— Decreased and often painful at extremes

— Hip OA: earliest loss is internal rotation in flexion — a high-yield exam finding

— Knee OA: loss of full extension (flexion contracture) and terminal flexion

— Patellofemoral grind test for patellofemoral OA

— FABER/FADIR for hip pathology (nonspecific but useful)

— CMC grind test for thumb-base OA

— BP, BMI, gait speed, chair-stand test, single-leg stance — function metrics that predict surgical outcomes and fall risk

— Skin integrity over the affected joint (planning for surgery, intra-articular injection)

— Neurovascular exam to exclude radiculopathy or peripheral arterial disease mimicking joint pain

Key distinction: Bony enlargement + crepitus + cool joint + ≤30 min stiffness = OA, while warm, boggy synovitis + MCP/wrist involvement + >1 hour stiffness = RA. Mistaking inflammatory arthritis for OA delays DMARD therapy and erosive damage — a classic Step 3 trap when the stem buries an "MCP squeeze tenderness" detail in a "knee pain" vignette.

Inspection:

Palpation:

Range of motion:

Provocative and special tests:

Hemodynamic/systemic check (Step 3 angle for preop and chronic care):

Diagnostic Workup — Initial Labs and Imaging

— ACR criteria allow clinical diagnosis in adults ≥45 with activity-related joint pain and ≤30 min stiffness

— Order CBC, ESR, CRP, RF, anti-CCP, ANA, uric acid only if features suggest inflammatory or crystal arthritis (symmetric small joint involvement, prolonged stiffness, systemic symptoms, atypical joints)

— Expect labs to be normal or only mildly elevated CRP in pure OA

— OA: non-inflammatory — clear/yellow, viscous, WBC <2,000/µL (mostly mononuclear)

— Inflammatory: WBC 2,000–50,000

— Septic: WBC >50,000, positive Gram stain/culture

— Crystals: monosodium urate (gout) or CPPD (pseudogout)

— Obtain weight-bearing views of knees (PA flexed/Rosenberg view best for joint space) and hips; standing AP for alignment

— Hands: PA and oblique

— Four classic findings ("LOSS"):

— Loss of joint space (asymmetric — distinguishes from RA's symmetric loss)

— Osteophytes

— Subchondral sclerosis

— Subchondral cysts

— Kellgren–Lawrence grading 0–4 standardizes severity; grade ≥3 with symptoms supports surgical referral consideration

— Classic clinical picture in a patient ≥45 — imaging does not change initial management

— Radiographic severity often correlates poorly with symptoms

Board pearl: If a Step 3 stem orders an MRI for routine OA, that is almost always the wrong answer — MRI is reserved for suspected internal derangement (meniscal/ligament tear in a younger patient, mechanical locking, suspected AVN, occult fracture, or persistent unexplained symptoms despite normal radiographs).

Labs — usually NOT needed for typical OA:

Synovial fluid analysis (if effusion or diagnostic uncertainty):

Plain radiographs — the workhorse imaging:

When imaging is NOT required:

Diagnostic Workup — Advanced or Confirmatory Studies

— Suspected meniscal tear with mechanical symptoms (locking, true giving way) in a younger or active patient where surgical decision-making depends on the finding

— Suspected avascular necrosis (AVN) — risk factors include chronic glucocorticoids, alcohol use, sickle cell, SLE, prior trauma; plain films may be normal early

— Suspected occult fracture, stress fracture, or subchondral insufficiency fracture in older osteoporotic patient with acute knee pain

— Suspected inflammatory or septic process when radiographs are unrevealing

— Caveat: Incidental meniscal tears and cartilage defects are extraordinarily common on MRI in middle-aged adults with OA — finding one does not mandate arthroscopy

— Bedside detection of effusion, synovitis, and guidance of intra-articular injections

— Useful when joint anatomy is distorted or landmark-based injection has failed

— Preoperative planning for complex deformity or revision arthroplasty

— Better than MRI for cortical bone and osteophyte architecture

— Targeted history and exam; ECG only if indicated by age/comorbidity (per ACC/AHA perioperative guidelines)

— CBC, BMP, type & screen; coagulation only if clinically indicated

— Dental clearance and screening for occult infection (UTI, skin) before elective arthroplasty

— Optimize HbA1c (<7.5–8%), nutrition (albumin >3.5), tobacco cessation ≥4 weeks pre-op

Key distinction: Arthroscopy with lavage or debridement for routine knee OA is NOT recommended — multiple RCTs (and AAOS guidance) show no benefit over sham. Reserve arthroscopy for true mechanical symptoms with a confirmed correctable lesion, not as a substitute for delayed arthroplasty.

MRI — selective use only:

Ultrasound:

CT:

DEXA: Consider in postmenopausal women and older men with OA — comorbid osteoporosis affects fracture risk and surgical planning

Pre-op workup (when arthroplasty is on the table):

Risk Stratification and First-Line Management Logic

— Reduce pain, improve function, slow progression, delay/avoid surgery, maintain independence

— No therapy reliably regenerates cartilage — set realistic expectations

— Step 1 — Core nonpharmacologic therapy for ALL patients:

— Patient education + self-management programs

— Exercise — strongly recommended (aerobic, resistance, neuromuscular, aquatic for those with severe pain or obesity)

— Weight loss — every 1 lb lost ≈ 4 lb of knee load reduced; ≥5–10% body weight loss meaningfully reduces symptoms

— Physical therapy referral for tailored program

— Assistive devices (cane in contralateral hand for hip/knee OA), bracing for medial knee OA, proper footwear

— Thermal modalities, TENS as adjuncts

— Step 2 — Topical agents (preferred first pharmacologic step, especially in knee/hand OA): topical NSAIDs (diclofenac gel), topical capsaicin

— Step 3 — Oral pharmacotherapy: oral NSAIDs (lowest dose, shortest duration), duloxetine for chronic pain or polyarticular OA

— Step 4 — Intra-articular options: glucocorticoid injection for flares; hyaluronic acid conditionally for knee (modest, controversial benefit)

— Step 5 — Surgical referral when refractory

— Glucosamine/chondroitin — ACR strongly recommends against

— Hydroxychloroquine, methotrexate, TNF inhibitors — for OA, no

— Opioids — strongly conditionally against; tramadol only conditionally and only if no alternatives

— Arthroscopic lavage/debridement for OA without mechanical lock

— Stem cell, PRP injections — insufficient evidence

Step 3 management: The first answer choice for newly diagnosed knee OA should almost always be exercise + weight loss + patient education, with topical NSAID as the first pharmacologic step. Jumping to opioids, MRI, or arthroscopy is a distractor.

Treatment goals (frame for shared decision-making):

Stepwise outpatient model (OARSI/ACR 2019 framework):

Therapies NOT recommended (high-yield "wrong answer" choices):

Pharmacotherapy — First-Line Drug Regimen

— Diclofenac 1% gel — apply to affected joint 4× daily (knee 4 g; hand 2 g per application)

— Comparable efficacy to oral NSAIDs for superficial joints with far less systemic toxicity — preferred in elderly, CKD, CV disease, GI risk

— Skin irritation is the main side effect

— Naproxen 250–500 mg BID (preferred CV profile), ibuprofen 400–600 mg TID, or celecoxib 100–200 mg daily

— Lowest effective dose, shortest duration

— Add PPI if age >65, prior PUD, concurrent antiplatelet/anticoagulant, or chronic glucocorticoids

— Avoid if CKD stage ≥4, decompensated HF, active PUD, on anticoagulation without risk mitigation

— Monitor BP, renal function, hemoglobin

— Modest efficacy in OA; useful adjunct when NSAIDs contraindicated

— Cap at ≤3 g/day chronically (≤2 g if hepatic disease or significant alcohol use)

— Not first-line monotherapy per ACR 2019 (small effect size)

— Particularly useful for polyarticular OA, comorbid chronic pain, depression, or when NSAIDs contraindicated

— Monitor BP, watch for serotonergic interactions, taper to discontinue

— Conditionally against by ACR; only when all other options exhausted and surgery not feasible

— Document risks, screen for misuse, use PDMP

Board pearl: In an 80-year-old with knee OA and CKD stage 3b, the right first-line drug is topical diclofenac, not oral ibuprofen. Step 3 frequently tests NSAID safety in the elderly and renal-impaired.

Topical NSAIDs (first-line pharmacotherapy, especially knee and hand OA):

Oral NSAIDs (second-line when topical inadequate or polyarticular):

Acetaminophen:

Duloxetine 30–60 mg daily:

Capsaicin cream: adjunct for hand/knee OA; burning sensation limits adherence

Tramadol / opioids:

Agents NOT recommended: glucosamine, chondroitin, fish oil, colchicine, hydroxychloroquine, bisphosphonates for OA

Intra-articular Injections and Surgical Management

— Triamcinolone 40 mg or methylprednisolone 40 mg, often with lidocaine

— Best for flares with effusion; meaningful relief lasts 4–8 weeks

— Limit to ≤3–4 injections per joint per year — concern for cartilage loss with frequent repeat injections (recent data) and infection risk

— Transient glucose elevation in diabetics — counsel

— Defer elective arthroplasty ≥3 months after intra-articular steroid injection to reduce prosthetic joint infection risk

— Conditional recommendation against in knee OA by ACR; AAOS does not strongly recommend

— Reasonable trial if other options fail and surgery is deferred

— Indications:

— Persistent moderate–severe pain and functional disability despite ≥3–6 months of optimized conservative therapy

— Pain limiting ADLs, sleep, or quality of life

— Radiographic advanced OA (Kellgren–Lawrence 3–4) generally present but not absolutely required

— Procedures:

— Total knee arthroplasty (TKA) and total hip arthroplasty (THA) — durable (~90% survival at 15–20 years)

— Unicompartmental knee arthroplasty in selected isolated medial-compartment disease

— Hip resurfacing — niche, younger active males

— Osteotomy (high tibial) for younger active patients with unicompartmental disease and malalignment

CCS pearl: In a CCS-style scenario, after failed conservative management, the correct sequence is orthopedic surgery consult → pre-op risk stratification → optimize modifiable factors → schedule TKA/THA → DVT prophylaxis post-op.

Intra-articular glucocorticoid injection:

Hyaluronic acid (viscosupplementation):

Genicular nerve radiofrequency ablation: option for advanced knee OA poor surgical candidates

Surgical referral — orthopedics for joint replacement:

Arthroscopy: not indicated for OA alone; reserved for true mechanical symptoms with correctable lesion

Pre-op optimization: BMI ideally <40 (some centers <35), HbA1c <7.5–8%, smoking cessation, dental clearance, MRSA screening per center, nutrition, anemia correction

Special Populations — Elderly and Renal/Hepatic Impairment

— Avoid chronic oral NSAIDs when possible (Beers Criteria) — risk of GI bleed, AKI, HF exacerbation, hypertension, drug interactions

— Prefer topical NSAIDs, acetaminophen ≤3 g/day, duloxetine, intra-articular injections, PT

— Screen for falls, frailty, sarcopenia — quadriceps strengthening reduces fall risk

— Polypharmacy review at every visit

— Cognitive screening before opioid prescribing

— eGFR 30–59: use oral NSAIDs cautiously and short-term only; topical NSAIDs preferred; monitor BP, creatinine, K+

— eGFR <30: avoid systemic NSAIDs entirely; topical NSAIDs are an option (minimal systemic absorption)

— Acetaminophen safe at standard doses

— Duloxetine: avoid if CrCl <30

— Tramadol: dose-adjust; serotonergic and seizure risk

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

— NSAIDs: avoid in cirrhosis (risk of variceal bleed, hepatorenal syndrome, ascites worsening)

— Duloxetine: avoid in significant hepatic disease

— NSAIDs raise BP, blunt diuretics/ACE inhibitors, increase MI and HF risk

— Naproxen has the most favorable CV profile among oral NSAIDs; avoid diclofenac and high-dose ibuprofen in established CVD

— Prefer topical NSAIDs, acetaminophen, duloxetine

— Avoid oral NSAIDs if possible; if needed, add PPI and minimize duration

— Intra-articular injection generally safe with therapeutic INR; do not routinely interrupt anticoagulation for joint injection

Step 3 management: In an elderly patient on warfarin with knee OA, the safest analgesic choice is topical diclofenac plus acetaminophen ≤3 g/day, with an intra-articular steroid injection if a flare occurs — not oral ibuprofen, which would risk bleeding and AKI.

Elderly (≥65–75):

Chronic kidney disease:

Hepatic impairment:

Cardiovascular disease / heart failure:

Anticoagulated patients:

Special Populations — Pregnancy, Younger Adults, and Post-Traumatic OA

— Primary OA is uncommon in reproductive-age women, but secondary or post-traumatic OA may flare

— Acetaminophen is first-line analgesic in pregnancy

— NSAIDs: avoid after 20 weeks (oligohydramnios/fetal renal risk) and absolutely after 30 weeks (premature ductus arteriosus closure) — FDA warning

— Topical NSAIDs: limited data, generally avoided after 20 weeks

— Opioids: only if essential and short-term; neonatal abstinence risk

— Lactation: ibuprofen preferred among NSAIDs; acetaminophen safe

— Post-traumatic OA — prior ACL tear, meniscectomy, intra-articular fracture

— Developmental — hip dysplasia, femoroacetabular impingement (FAI), slipped capital femoral epiphysis sequelae, Perthes disease

— Metabolic — hemochromatosis (2nd and 3rd MCP involvement, "hook" osteophytes), ochronosis (alkaptonuria), Wilson disease, acromegaly

— Crystal — CPPD/chondrocalcinosis accelerating OA

— Avascular necrosis sequelae

— Workup if atypical: ferritin/transferrin saturation, calcium, TSH, consider hand x-rays for chondrocalcinosis

— Cross-training, neuromuscular rehab, gradual loading

— Counsel that running does not cause knee OA in the absence of prior injury

— Joint-preserving surgery (osteotomy, cartilage restoration) may delay arthroplasty

— Weight loss ≥10% delivers symptom benefit comparable to many drugs

— GLP-1 agonists/bariatric surgery referral when BMI ≥35–40 with OA-driven disability — emerging Step 3 management consideration

Board pearl: OA in a young patient with 2nd–3rd MCP involvement and hook-shaped osteophytes → check iron studies for hemochromatosis — a classic Step 3 zebra worth recognizing.

Pregnancy and lactation:

Younger adults (<45) with OA — always investigate why:

Athletes and active adults:

Obesity-specific:

Pediatrics: Primary OA does not occur; juvenile idiopathic arthritis, hemophilic arthropathy, or post-traumatic causes should be considered

Complications and Adverse Outcomes

— Progressive functional decline — loss of independence, falls, deconditioning

— Chronic pain with sleep disruption, depression, anxiety

— Sarcopenia and weight gain from reduced activity → cardiometabolic disease

— Joint deformity — varus knee, fixed flexion contractures, ulnar drift mimics in advanced hand OA

— Baker (popliteal) cyst — may rupture, mimic DVT

— Secondary meniscal degeneration, loose bodies, mechanical symptoms

— Post-traumatic OA risk doubles after meniscectomy

— NSAID-induced: GI bleed, peptic ulcer, AKI, hypertension, HF exacerbation, MI/stroke (esp. diclofenac, high-dose ibuprofen)

— Acetaminophen: hepatotoxicity at high doses or with alcohol use

— Intra-articular steroids: transient hyperglycemia, infection (rare), skin atrophy, potential accelerated cartilage loss with frequent use, post-injection flare

— Opioids: misuse, constipation, falls in elderly, hyperalgesia

— Prosthetic joint infection (PJI): 1–2% lifetime risk; presents as pain, warmth, drainage, or persistent pain after arthroplasty — refer urgently to ortho

— VTE: DVT/PE — prophylaxis is standard (aspirin, LMWH, DOAC per protocol) for 10–35 days post-op

— Periprosthetic fracture, dislocation (especially THA in first 6–12 weeks)

— Aseptic loosening — late cause of pain, requires revision

— Nerve injury (peroneal in TKA), vascular injury

— Stiffness/arthrofibrosis after TKA — manipulation under anesthesia if ROM <90° at 6–12 weeks

— Persistent pain in 10–20% of TKA patients despite radiographic success — set expectations preoperatively

Key distinction: Acute warm, painful, swollen prosthetic joint = PJI until proven otherwise — obtain ESR, CRP, and joint aspiration before antibiotics, and refer urgently. Do not give empirical oral antibiotics from clinic; that obscures the diagnosis.

Disease-related complications:

Treatment-related complications:

Surgical (TKA/THA) complications:

Mortality: Low operative mortality (<1%), but OA-related immobility contributes to CV disease, the leading cause of death in this population

When to Escalate Care — Consults and Referrals

— Refractory pain and functional disability despite 3–6 months of optimized conservative care (PT, weight loss, topical and oral analgesics, injections)

— Inability to perform ADLs, work, or sleep due to joint pain

— Advanced radiographic OA with concordant symptoms

— Mechanical symptoms (locking, true giving way) with suspected internal derangement

— Suspected septic joint: hot, swollen, exquisitely tender joint with fever — same-day arthrocentesis and inpatient management; do not inject steroid

— Suspected prosthetic joint infection — urgent ortho referral, do not start antibiotics empirically before culture

— Acute hemarthrosis in anticoagulated patient

— Suspected fracture (acute pain after fall, inability to bear weight, deformity)

— Cauda equina syndrome in patient with spinal OA: saddle anesthesia, urinary retention, bilateral leg weakness — emergent MRI and neurosurgery

— Suspected inflammatory arthritis (RA, PsA, spondyloarthritis, gout/CPPD with diagnostic uncertainty)

— Atypical OA in young patient with metabolic suspicion

— Erosive (inflammatory) OA of the hand with rapid progression

CCS pearl: In a CCS case, after 3–6 months of failed conservative therapy with persistent pain and functional decline, the next correct action is referral to orthopedic surgery for arthroplasty evaluation — not escalating to opioids or repeating injections indefinitely.

Orthopedic surgery referral (elective):

Urgent/emergent referrals:

Rheumatology referral:

Physical therapy referral: essentially universal — first-line and post-op

Pain management referral: patients failing standard therapy and not surgical candidates; for radiofrequency ablation, image-guided injections, multimodal pain plans

Bariatric / endocrinology / nutrition: BMI ≥35–40 with OA disability — GLP-1 agonists or bariatric surgery can transform candidacy and outcomes

Behavioral health: comorbid depression/anxiety strongly predict poor surgical outcomes — address pre-op

Geriatrics / care coordination: older patients with frailty need home safety, fall prevention, caregiver support

Key Differentials — Other Joint Disorders

— Symmetric small joint involvement (MCPs, PIPs, wrists), prolonged morning stiffness >1 hour, warm boggy synovitis, systemic symptoms

— RF, anti-CCP positive; elevated ESR/CRP; erosive joint changes

— Symmetric joint space loss vs. OA's asymmetric

— DIPs typically spared (opposite of OA)

— Skin/nail psoriasis, DIP involvement, dactylitis, enthesitis

— Asymmetric oligoarthritis, "pencil-in-cup" radiographic findings

— Can mimic hand OA but with inflammation and systemic features

— Acute monoarthritis, 1st MTP "podagra", knee

— Tophi, hyperuricemia, monosodium urate crystals (negatively birefringent, needle-shaped)

— Often coexists with OA (especially knee)

— Chondrocalcinosis on radiograph, acute attacks in knee, wrist

— Positively birefringent rhomboid crystals

— Accelerates OA-like change in atypical joints (wrist, MCP)

— Acute monoarticular, fever, ESR/CRP markedly elevated

— Synovial WBC >50,000, positive Gram stain/culture

— Emergent drainage + IV antibiotics

— Hand OA variant with inflammation, gull-wing deformity on x-ray

— Ankylosing spondylitis: inflammatory back pain in young adult, improves with activity, sacroiliitis

— IBD-associated, reactive arthritis

Key distinction: Symmetric MCP/wrist involvement + stiffness >1 hour + positive anti-CCP = RA, requiring early DMARD therapy (e.g., methotrexate) — missing this is a Step 3 trap when the stem buries inflammatory features inside a "knee/hip pain" vignette.

Rheumatoid arthritis (RA):

Psoriatic arthritis:

Gout:

CPPD / pseudogout:

Septic arthritis:

Inflammatory ("erosive") OA:

Hemochromatosis arthropathy: 2nd/3rd MCP involvement, hook osteophytes, chondrocalcinosis

Spondyloarthropathies:

Fibromyalgia: widespread pain, tender points, no joint inflammation, often coexists

Key Differentials — Non-Articular Causes of Joint Pain

— Lumbar radiculopathy (L2–L4) — pain radiating from back to thigh, positive straight-leg or femoral stretch test, neurologic signs

— Trochanteric (greater trochanteric pain syndrome / gluteal tendinopathy): lateral hip tenderness, pain lying on side

— Meralgia paresthetica: lateral femoral cutaneous nerve, anterolateral thigh dysesthesia

— Avascular necrosis of femoral head: groin pain, MRI required when radiographs normal; risk factors steroids, alcohol, SCD

— Inguinal hernia, iliopsoas bursitis, femoral hernia

— Vascular claudication (PAD): exertional buttock/thigh pain relieved by rest

— Pes anserine bursitis: medial knee pain just below joint line, focal tenderness

— Iliotibial band syndrome: lateral knee pain, runners

— Patellofemoral pain syndrome: anterior knee pain with stairs, prolonged sitting; younger patients

— Meniscal tear: mechanical locking, McMurray, joint line tenderness

— Referred from hip — hip OA can present as knee pain (especially anterior thigh/knee)

— DVT with calf pain mimicking knee pathology (esp. ruptured Baker cyst)

— De Quervain tenosynovitis: radial wrist pain, positive Finkelstein

— Trigger finger: flexor tenosynovitis with locking

— Carpal tunnel syndrome: nocturnal paresthesias, median distribution

— RA, psoriatic arthritis (above)

Board pearl: When the stem says "groin pain with loss of internal rotation," that's hip OA. "Lateral hip pain that hurts when lying on that side" is trochanteric/gluteal tendinopathy — a high-yield distinction that changes management entirely (physical therapy and possibly local injection, not arthroplasty).

Hip OA mimics — when "hip pain" is not the hip:

Knee OA mimics:

Hand OA mimics:

Shoulder pseudo-OA: rotator cuff disease, adhesive capsulitis, calcific tendinopathy — true GH OA is uncommon

Polymyalgia rheumatica: age >50, proximal shoulder/hip girdle pain, marked ESR elevation, dramatic response to low-dose prednisone — can mimic OA stiffness

Secondary Prevention, Long-Term Plan, and Discharge Medications

— Weight loss — sustained ≥5–10% reduction; refer to structured programs, dietitian, GLP-1 agonist or bariatric surgery if BMI threshold met

— Regular exercise — combine aerobic (walking, cycling, swimming), resistance (quadriceps, hip abductors), and neuromuscular (balance, proprioception); aim ≥150 min/week moderate activity

— Injury prevention: ACL injury prevention programs in athletes, ergonomic workplace modifications, fall prevention in elderly

— Footwear: supportive shoes, avoid high heels, consider lateral wedge insoles only if symptomatic relief (evidence mixed)

— Smoking cessation (improves surgical outcomes, bone healing)

— Treat comorbid depression and sleep disorders — both amplify pain perception

— VTE prophylaxis for 10–14 days (TKA, sometimes up to 35) and up to 35 days (THA) — options include aspirin 81 mg BID, rivaroxaban, apixaban, enoxaparin, or warfarin per protocol; choice depends on patient risk

— Multimodal analgesia: scheduled acetaminophen, NSAID (if no contraindication), short-course opioid with taper

— Bowel regimen with opioids

— Antiemetic PRN

— Resume home medications (antihypertensives, statins, etc.)

— Continue or restart antiplatelets/anticoagulants per surgeon

— Dental prophylaxis: routine antibiotic prophylaxis before dental procedures is NOT recommended for most patients with prosthetic joints (per ADA/AAOS 2016); individualize for immunocompromised or high-risk patients in first 2 years

— Lifelong awareness of PJI symptoms — counsel to seek care for new joint pain, fever, drainage

— Activity restrictions are minimal long-term; encourage low-impact exercise (walking, cycling, swimming, golf)

— Driving usually resumes 4–6 weeks post-op

— Sexual activity, return to work counseling

Step 3 management: A patient with a hip prosthesis getting routine dental cleaning does not need prophylactic antibiotics per current guidance — a frequently tested update from older practice.

Modifiable risk factor optimization (lifelong):

Post-arthroplasty discharge medications:

Long-term post-arthroplasty considerations:

Vaccinations: ensure influenza, pneumococcal, COVID, shingles, and Tdap are up to date — especially before elective arthroplasty

Follow-Up, Monitoring, and Rehabilitation

— 2–4 weeks after initiating new therapy (NSAID, duloxetine) to assess response, BP, side effects

— 3 months to reassess function and progress with PT/exercise/weight loss

— 6–12 months stable patients on chronic therapy — annual labs (CBC, BMP) if on chronic NSAIDs

— Document WOMAC or functional scores longitudinally to justify escalation

— BP each visit; creatinine and CBC at 1–3 months then annually

— Reassess CV/GI risk yearly; reconsider PPI need

— Re-evaluate ongoing need — many patients can use intermittently

— Day 0–1: mobilize same day; PT begins immediately; DVT prophylaxis started

— Week 1–2: wound check, suture/staple removal, continue PT

— Week 6: ortho follow-up with radiograph; most patients ambulate with cane or unassisted

— 3 months: return to most activities; final ROM goals (≥110° flexion TKA, full extension)

— 1 year: routine ortho check; then periodic radiographs every 2–5 years to monitor for loosening, polyethylene wear

— Quadriceps strengthening is the single most evidence-based intervention for knee OA

— Hip abductor strengthening for hip OA

— Aquatic therapy for patients with severe pain or obesity

— Neuromuscular training, balance, proprioception

— Set expectations: OA is chronic and progressive but manageable

— Emphasize active self-management — exercise adherence is the strongest predictor of long-term function

— Weight loss messaging at every visit (motivational interviewing)

— Sleep, mood, social support — all modulate pain

Board pearl: Quadriceps strengthening + weight loss delivers the largest evidence-based functional benefit in knee OA — more durable than any oral medication. Reinforce at every visit.

Routine outpatient follow-up cadence:

NSAID monitoring (if chronic):

Post-arthroplasty rehab milestones:

Physical therapy emphasis:

Patient counseling pillars:

Quality measures (value-based care): Patient-reported outcome measures (PROMs) pre/post-arthroplasty are increasingly mandated by CMS

Ethical, Legal, and Patient Safety Considerations

— Discuss alternatives (continued conservative care, injection, doing nothing), realistic outcomes (10–20% with persistent pain despite "successful" TKA), risks (infection 1–2%, VTE, periprosthetic fracture, revision surgery), and recovery time

— Document shared decision-making — Step 3 examiners reward this language

— Use of decision aids improves consent quality and reduces surgical regret

— Elderly patients with mild cognitive impairment can often retain capacity for elective decisions; formally assess if in doubt

— Engage healthcare proxy / advance directive review before elective major surgery

— Check state PDMP before prescribing; co-prescribe naloxone for higher-risk patients

— Limit post-op opioids to 3–7 days for most arthroplasties; taper expectation set preoperatively

— Avoid opioids for chronic OA whenever possible — Step 3 frequently tests this

— Clear written discharge instructions: medications, VTE prophylaxis duration, wound care, weight-bearing status, red flags (fever, calf swelling, increasing pain, drainage)

— Medication reconciliation at discharge — most common cause of post-op error

— Schedule PT and ortho follow-up before discharge

— Communicate with PCP within 7–14 days; close the loop on chronic disease (DM, HTN) post-op

— TKA/THA underutilized in women, Black, Hispanic, and low-income patients despite equal disease burden — actively address access barriers

— Language-concordant care, interpreter use, culturally tailored education improve outcomes

— Document falls assessment — under-recognition is a patient safety issue

— Report device failures (implant recalls) to FDA MedWatch

— Driving safety counseling in patients with significant ROM limitations or on opioids

Step 3 management: When discharging a post-TKA patient, the safest plan includes VTE prophylaxis prescription, scheduled PT, ortho follow-up at 2–6 weeks, written red-flag instructions, and a PCP visit within 2 weeks — missing any of these is a known transition-of-care failure point.

Informed consent for joint replacement:

Capacity and surrogate decision-making:

Opioid stewardship and patient safety:

Transitions of care after arthroplasty (high-yield Step 3):

Health equity and access:

Mandatory reporting and safety:

Workers' compensation / disability: Be objective in functional documentation; avoid conflict of interest

High-Yield Associations and Rapid-Fire Facts

Key distinction: OA = mechanical, asymmetric, large weight-bearing joints + DIPs, no systemic symptoms, normal labs. Inflammatory arthritis = symmetric small joints, prolonged stiffness, elevated inflammatory markers, systemic features. Most Step 3 OA traps hinge on missing this line.

Heberden nodes = DIP; Bouchard nodes = PIP — both OA, hand

Earliest exam finding in hip OA = loss of internal rotation in flexion

Hip OA pain = groin/anterior thigh, sometimes referred to knee

OA radiographic mnemonic "LOSS": Loss of joint space (asymmetric), Osteophytes, Subchondral sclerosis, Subchondral cysts

Synovial WBC in OA = <2,000; inflammatory 2,000–50,000; septic >50,000

Use cane in CONTRALATERAL hand for hip/knee OA

Every 1 lb lost = ~4 lb less knee load

Glucosamine/chondroitin: ACR strongly recommends AGAINST

First-line drug for knee/hand OA = topical NSAID (esp. elderly, CKD)

Naproxen has the most favorable CV profile among oral NSAIDs

Diclofenac and high-dose ibuprofen have highest CV risk

Limit intra-articular steroid to 3–4 injections/year/joint

Defer arthroplasty ≥3 months after intra-articular steroid (PJI risk)

TKA VTE prophylaxis ≥10–14 days; THA up to 35 days

Dental antibiotic prophylaxis for prosthetic joints: NOT routinely needed

Hemochromatosis = 2nd/3rd MCP arthropathy with hook osteophytes

OA in MCPs/wrists/elbows/ankles = think alternate diagnosis (RA, CPPD, hemochromatosis)

Erosive OA = inflammatory hand variant, gull-wing deformity

Acetaminophen cap = 3 g/day chronically, 2 g if liver disease

Arthroscopic debridement for OA: NOT indicated (no benefit over sham)

Quadriceps weakness predicts and accompanies knee OA — strengthening is core therapy

TKA flexion goal ≥110°; manipulation under anesthesia if <90° at 6–12 weeks

Persistent pain after "successful" TKA: 10–20% — counsel preoperatively

PJI workup: ESR + CRP + joint aspiration BEFORE antibiotics

Avoid NSAIDs in CKD stage ≥4, decompensated HF, active PUD, cirrhosis with ascites

Avoid NSAIDs in pregnancy after 20 weeks (FDA, 2020)

Cane reduces hip joint load by ~20–30%

Board Question Stem Patterns

— 62-year-old obese woman with 6 months of knee pain worse with stairs, brief AM stiffness, bony enlargement on exam → Answer: Exercise + weight loss + topical diclofenac (NOT MRI, NOT glucosamine, NOT opioid)

— 78-year-old with knee OA, eGFR 35, on warfarin → Answer: Topical NSAID ± acetaminophen ≤3 g/day (NOT oral ibuprofen)

— Groin pain with limited internal rotation → hip OA, get plain film

— Lateral hip pain when lying on that side → trochanteric/gluteal tendinopathy, PT and possibly injection

— Elderly patient with anterior knee pain, normal knee exam, decreased hip internal rotation → examine and image the HIP

— Persistent disabling symptoms despite 3–6 months of PT, weight loss, NSAIDs, injection → orthopedic referral, NOT another injection or opioid

— Fever, increased pain, wound drainage 3 weeks post-TKA → PJI workup (ESR, CRP, aspiration), ortho referral, NO empiric antibiotics from clinic

— Patient with "OA" of MCPs, wrists, or ankles, or with chondrocalcinosis → look for RA, CPPD, hemochromatosis (check ferritin)

— Patient with intra-articular steroid injection 6 weeks ago, scheduled for TKA → postpone TKA until ≥3 months from injection (PJI risk)

— Patient with TKA 3 years ago going for cleaning → no routine antibiotic prophylaxis

— "Knee pain" + symmetric MCP swelling + 90-min AM stiffness + elevated CRP → RA, not OA — get RF/anti-CCP, refer to rheumatology, start DMARD

— Knee OA + BMI 38 → structured weight loss program (and consider GLP-1 or bariatric surgery) is the highest-value intervention

Board pearl: Step 3 OA stems reward the least invasive, most evidence-based, longest-impact intervention first — exercise, weight loss, and topical NSAID — and punish reflexive ordering of MRI, opioids, glucosamine, or arthroscopy.

Pattern 1 — The "obvious" OA case testing first-line therapy:

Pattern 2 — Choosing analgesic in an elderly/CKD patient:

Pattern 3 — Hip pain localization:

Pattern 4 — Referred knee pain:

Pattern 5 — When to refer for arthroplasty:

Pattern 6 — Post-TKA red flag:

Pattern 7 — The atypical-joint trap:

Pattern 8 — Pre-op timing:

Pattern 9 — Dental prophylaxis:

Pattern 10 — Inflammatory mimic buried in stem:

Pattern 11 — Weight loss as drug:

One-Line Recap

Osteoarthritis is a chronic mechanical joint disease best managed in the outpatient setting with a stepwise plan of exercise, weight loss, and topical NSAIDs first — escalating to oral NSAIDs, duloxetine, or intra-articular steroid injections as needed — and referring for total joint arthroplasty only when 3–6 months of optimized conservative therapy fail to control pain or restore function.

Board pearl: When in doubt on a Step 3 OA stem, choose the least invasive, most function-restoring, evidence-based step that the patient has not yet tried — and remember that exercise and weight loss are always part of the right answer.

Diagnosis is clinical in adults ≥45 with activity-related pain, ≤30-min stiffness, and characteristic exam (bony enlargement, crepitus, asymmetric joint involvement of knees/hips/hands); imaging and labs are reserved for atypical features.

Cornerstones of therapy are nonpharmacologic — patient education, structured exercise (especially quadriceps strengthening), and ≥5–10% weight loss deliver durable benefit unmatched by any single drug.

Pharmacotherapy is stepwise and individualized — topical NSAIDs first, oral NSAIDs (with PPI in high-risk GI patients) or duloxetine next, intra-articular steroid for flares; avoid glucosamine/chondroitin, opioids, and arthroscopic debridement for OA.

Surgical referral is the right answer when symptoms are refractory despite optimized conservative care; pre-op optimization (BMI, HbA1c <7.5–8%, tobacco cessation, dental clearance) and ≥3-month delay after any intra-articular steroid reduce PJI risk, and post-op care emphasizes VTE prophylaxis (10–35 days), early mobilization, structured PT, and clear transition-of-care communication with the PCP.