11. Musculoskeletal Injuries: Sprains, Strains & Fractures –

Instructional Objectives

  • Recall components of musculoskeletal (MSK) history for joint pain
  • Detail a systematic physical examination of any joint
  • Explain appropriate use of diagnostic imaging modalities
  • Recognize signs, symptoms, management, complications of conditions in this lecture
  • Compare & contrast sprain vs. strain vs. fracture
  • Identify orthopedic disorders needing referral & appropriate timing

Study & Exam-Prep Tips

  • Review each day’s MSK lecture nightly; revisit material 2−32-3 times before next class
  • Compare/contrast disorders at same joint or with similar presentation → devise differentiation cues
  • Organize studying around frequent “Chief complaints”
  • Use active methods: quiz peers, draw structures, stand/move
  • Seek advisor help for time-management issues
  • Epidemiology worth noting:
    • MSK concerns = 10-20%10\text{-}20\% of outpatient primary-care visits
    • 53%53\% of patients > 6565 yrs complain of multi-site joint pain monthly

Joint Structure & Function

  • Synovial (diarthrodial) joints
    • Components: joint capsule, articular cartilage (collagenous, shape-adaptable cushion), synovium + synovial fluid (nutrition + friction reduction)
    • Examples: knee, shoulder
  • Extra-articular structures
    • Ligaments (bone→bone), tendons (muscle→bone), bursae, muscle, fascia, bone, nerve, skin
  • Bursae
    • Synovial-fluid sacs; permit tendon–muscle glide; bursitis = inflammation

Synovial Joint Sub-types

  • Spheroidal (ball & socket): rotary—hip, shoulder
  • Hinge: planar; flex/ext in one plane—elbow, interphalangeal
  • Pivot (uniaxial rotation): C1–C2, radial head–ulna
  • Condylar (biaxial): convex/concave—MCP, radiocarpal
  • Saddle (biaxial): rider-saddle fit—first CMC

Other Joint Classes

  • Cartilaginous (amphiarthroses): slightly mobile—intervertebral discs (nucleus pulposus)
  • Fibrous (synarthroses): immobile—skull sutures, syndesmoses (tibia–fibula, radius–ulna), gomphosis (tooth root)

History: Assessing Joint Pain

  • Mechanism of injury (MOI): traumatic vs. atraumatic/overuse; high vs. low velocity; acute vs. chronic
  • Location pattern: mono- vs. poly-articular; migratory; symmetric/asymmetric
  • Inflammatory (tender, red, warm) vs. non-inflammatory (stiff, ↓ROM, swelling)
  • Functional limitation: ADLs, gait, grip etc.
  • Systemic S/S: fever, weight loss, rash, myalgias, swelling w/o injury
  • Timing: rapid vs. insidious; diurnal pattern; fluctuations
  • Aggravating/alleviating factors; reproducibility
  • Prior episodes & treatments (“Have you had this before?”)
  • BLUE-SHEET mantra: standardized, repeated ROS/HPI every time

Physical Examination Framework

  • Exposure: full visualization above & below joint
  • INSPECTION
    • During normal activity attempt; compare bilaterally
    • Look for deformity, malalignment, limb shortening, scars, atrophy, skin lesions, hair pattern changes
  • PALPATION
    • Temperature, crepitus, step-offs, point tenderness, effusion; include joints above & below
  • RANGE OF MOTION (ROM)
    • Active first; if limited/painful → passive
    • Compare proximal & distal joints; note restrictions or laxity
    • Watch for crepitus (possible fracture/OA), locking/clicking (meniscal/internal derangement), gross instability (ligament rupture/dislocation)
  • NEUROVASCULAR EXAM distal to injury
    • Sensation (LT, sharp/dull, 2-point), motor, reflexes, rectal tone prn, pulses, cap refill
  • STRESS TESTS (after fracture/dislocation excluded)
    • Apply perpendicular load to evaluate ligament integrity; painless laxity often = complete tear
  • RED FLAGS: obvious/open Fx, unreduced dislocation, pain out of proportion (consider compartment syndrome), neurovascular compromise

Imaging & Diagnostic Modalities

  • Plain Radiographs: at least AP+Lateral\text{AP} + \text{Lateral}; best for bone—Fx, tumor, OA, congenital deformity; not soft-tissue
  • DEXA: bone mineral density (osteopenia/porosis)
  • CT: occult Fx, complex pelvic Fx, foreign body, nec fasc, abscess, myositis, osteomyelitis; faster & cheaper than MRI but ionizing radiation
  • MRI: gold standard for soft tissue (muscles, tendons, ligaments); picks up occult/stress Fx, bone bruise; use after failed conservative care
  • Ultrasound: fluid, effusions, tendon tears, soft-tissue FB, nerve studies; guides injections/aspirations
  • Bone Scan (Technetium 99m99m): detects healing bone—Fx, infection, tumor
  • Arthroscopy: fiber-optic intra-articular; diagnostic + therapeutic (biopsy, repair, debridement)
  • Fluoroscopy: real-time X-ray for reductions, FB removal
  • Open-joint injury work-up: 50-90%50\text{-}90\% knee; CT for intra-articular air → ortho + IV cefazolin 1 g1\,g q88h, tetanus update

Muscle & Tendon Injuries

Definitions

  • Ligament tear → Sprain (bone–bone)
  • Tendon or muscle tear → Strain (muscle–bone)

Sprains

  • MOI: twist/jam/stretch beyond physiologic limit
  • Presentation: tenderness, swelling, ecchymosis, ±instability, functional loss; able to ambulate >33 steps
  • X-ray: no Fx/hemarthrosis
  • Grading:
    • Grade I: stretched ligament (microscopic)
    • Grade II: partial tear with laxity
    • Grade III: complete tear & instability
  • Treatment
    • Grade I: RICE, NSAIDs, rehab
    • Grade II: above + immobilization (foam splint/air cast)
    • Grade III: cast vs. surgical repair; ortho consult
  • Prognosis: swelling peaks ≈24\approx24 h, subsides 2−42-4 d; full strength up to 66 mo

Strains

  • Partial tears often progress; ROM intact early; can heal conservatively
  • Complete rupture → loss of action, often requires surgery
  • Grading/Healing
    • 1° mild: few fibers; minimal swelling/pain, no strength loss; heal 1−31-3 wk
    • 2° moderate: many fibers; significant pain/swelling, strength loss; heal 2−32-3 mo
    • 3° severe: full rupture; acute severe pain + pop, palpable gap, instability; heal ≥66 mo with likely surgery
  • Management
    • 1°/2°: RICE, NSAIDs
    • 3°: add immobilization, IV analgesia/observation, ortho referral
  • Delayed-onset muscle soreness (DOMS): Type 1 strain; appears 12−4812-48 h post-exercise, lasts 4−124-12 d; treat with ice, stretching, active rest

Tendon Pathology Terminology

  • Tendinopathy: umbrella for tendon pain/swelling
  • Tendinosis: chronic degeneration (↓cells, disorganized fibers, neovessels)
  • Tenosynovitis: tendon + sheath inflammation
  • Entrapment: loss of smooth glide
  • Rupture: complete separation
  • Etiology: overuse, poor ergonomics/equipment, vibration, static posture, inadequate rest, fluoroquinolone Rx
Common Tendinopathies
  • Epicondylitis (lateral “tennis”, medial “golfer’s”)
  • Biceps, Achilles, Quadriceps, Rotator-cuff, Tibialis posterior/anterior
  • S/S: gradual pain with activity, night pain, point tenderness over tendon (NOT joint line), minimal to no effusion
  • Treatment: correct overload, rest/ice/splint, PT, NSAIDs or steroid injections, surgery last resort

Bursitis

  • Bursa inflammation → swelling + tenderness; treat rest, ice, OTC analgesics; aspiration then compression; surgery rarely

Fasciitis

  • Plantar fasciitis = #1 adult heel pain; degenerative origin on calcaneus
  • Pain with first steps & prolonged standing; worse on dorsiflexing toes
  • Tx: heel pad, stretching, ice

Infectious Arthritis (Septic Joint)

  • Onset hours–days; hot, red, swollen, very painful ↓ROM; often monoarticular (>90%90\%)
  • RF: DM/immunosuppression, IVDU, elderly, prosthesis, prior joint disease (RA)
  • Gonococcal variant: migratory tenosynovitis/arthralgia then single joint; ±GU Sx
  • Work-up: X-ray, urgent aspiration → WBC, Gram, culture, crystals
  • DDx: gout/pseudogout, RA, tumor, Lyme, SLE
  • Management: IV ABX, admit, ortho + ID consult

Fractures

  • Definition: cortical discontinuity (= crack = break)
  • Clinical: point tenderness, pain, deformity, crepitus, impaired function, ±neurovascular deficits
  • Confirm w/ radiographs (≥22 views)

Dislocation & Subluxation

  • Dislocation: complete loss of articular contact; obvious deformity
    • Ischemic limb window ≈ <4 h → urgent reduction
  • Subluxation: partial displacement; may still need reduction

Complications of MSK Injuries

  • Acute: bleeding, vascular compromise, nerve injury
    • Nerve lesions: neurapraxia (bruise, recovery 6−86-8 wks), axonotmesis (crush, regenerate wks–yrs), neurotmesis (transection, no spontaneous recovery)
  • Long-term: instability (leads to OA), stiffness ↓ROM, non-union, delayed union, malunion, osteonecrosis, chronic pain

Compartment Syndrome

  • Pathophysiology: elevated intracompartmental pressure → critical ischemia (leg/forearm common)
  • Hallmark: “pain out of proportion” & exquisite pain on passive stretch
  • Classic 5 P’s: pain, pallor, pulselessness, poikilothermia, paralysis (late signs)
  • Causes: Fx, reperfusion, hemorrhage, crush, burns, tight casts, anticoagulation, hemophilia, vascular puncture
  • Exam: swollen, firm compartment; sensory loss; pulses/color often normal early; pressures >30−50 mm Hg30-50\,\text{mm Hg} (normal <1010)
  • Treatment: emergent ortho fasciotomy (≤66 h ideal), reverse anticoagulation/replace factors

Orthopedic Referral Guidelines

  • Immediate (ED): neurovascular injury, septic arthritis, compartment syndrome, unreduced dislocation, open/unstable Fx, severe distal weakness/paresthesia
  • Within ≤7\le7 days: closed stable Fx, post-reduction dislocation, suspected tumors, failed conservative Tx (>33 mo)