C (8B) Musculoskeletal Injuries and Disorders

Basic Anatomy

Tendon = muscle → bone

Ligament = bone → bone

Bursa = fluid-filled sac providing lubrication/cushioning

Cartilage = protective padding between bones.

 Types of musculoskeletal problems

1. Muscle Pain / Inflammation

2. Delayed-onset muscle soreness (DOMS)

3. Myalgia

4. Tendinitis / Bursitis / Sprain / Strain

5. Osteoarthritis

6. Acute Low Back Pain

Muscle Pain / Inflammation

Pain receptors in skeletal muscle can be stimulated by:

• overuse

• injury

Inflammation:

• erythema = redness

• edema = swelling

• hyperalgesia = exaggerated pain response.

Delayed-onset muscle soreness

• caused by overexertion

• begins 8+ hours after activity

• professor said commonly peaks around 24–48 hours.

Myalgia

• Myalgia = muscle pain

• Causes

  • systemic infections

  • chronic disorders

  • medications → especially statins.

Tendinitis

• Inflammation of tendon

• Causes:

  • repetitive motion

  • fluoroquinolones

    • Fluoroquinolones can be associated with tendinitis/tendon rupture.

Bursitis

• repetitive joint action

• acute injury

• leads to pain/tenderness/swelling

Sprain

• Ligament injury

• Can involve:

  • overextension

  • partial tear

  • tear

Strain

Muscle or tendon injury.

Osteoarthritis

• OA = gradual softening/destruction of cartilage between bones

• Refer for:

  • undiagnosed OA

  • topical NSAID needed for ≥21 days

  • OA pain not improved after 7 days topical NSAID.

Acute Low Back Pain

Recognize contributing factors:

• sedentary lifestyle/obesity

• poor posture/improper shoes/ improper lifting technique.

Pain Classification

Acute <4 weeks

Subacute = 4 weeks–3 months

Chronic >3 months.

Musculoskeletal Self-Care Exclusions

1. 6 – 10 – 7 – 21

• Pain >6/10 → refer

• Pain >10 days → refer

• No improvement after 7 days topical analgesic → refer

• Need topical NSAID for ≥21 days → refer

2. Special patients

• pregnancy

• age <2 years

3. Worse or sick

• undiagnosed OA

• pelvic/abdominal pain except dysmenorrhea

• systemic illness (N/V/fever)

Memory: “Worse or sick = refer.”

4. Injury / nerve red flags

• deformed joint

• suspected fracture

• abnormal movement

• limb weakness/numbness

• back pain + loss of bowel/bladder control

Memory: “Broken, weak, numb, or bowel/bladder + back pain = REFER.”

Treatment Goals - skip

• reduce pain severity and duration

• restore function

• prevent re-injury/disability

• prevent acute → chronic pain

Treatment Approach

1. Nonpharmacologic

2. Oral

   1. systemic medications

   2. supplements

3. Topical products

⭐ Professor emphasized:

If the patient can safely use an oral agent → oral therapy is preferred/first-line.

Topicals:

• adjunct to oral treatment OR

• alternative when oral therapy cannot be used.

Nonpharmacologic

treatment overview

• RICE (Inflammation

• heat (Non-inflammatory)

• treatment for muscle cramps

• Alternating heat + ice:

Nonpharmacologic

RICE

R = Rest

I = Ice

C = Compression

E = Elevation

• Ice

• Compression → support

• Elevation → above heart when appropriate.

Nonpharmacologic

Muscle cramps

• stretch

• massage

• if electrolyte depletion → sports drinks/enhanced waters may help.

Nonpharmacologic

Heat

• Use for non-inflammatory pain

• 15–20 min, 3–4×/day

• Do NOT:

  • use on inflamed areas

  • combine heat with topical analgesics

  • use over broken skin.

Nonpharmacologic

Alternating heat + ice:

• anecdotal support

• professor said no strong scientific evidence discussed supporting it.

Systemic Analgesics

overview

• NSAIDs

• Acetaminophen

Systemic Analgesics

NSAIDs

• analgesic

• anti-inflammatory

Systemic Analgesics

Acetaminophen

mainly analgesic

Systemic Analgesics

Potential concerns with long-term NSAIDs

• nephropathy

• GI ulcers/bleeding

• cardiac events

Systemic Analgesics

Duration

Maximum musculoskeletal self-care with systemic analgesic: 10 days.

Chronic-joint supplement

Glucosamine + Chondroitin

Chronic-joint supplement

Glucosamine + Chondroitin

• treat OA joints (cartilage production)

• slow onset

• shellfish

• stomach upset.

And for the numbers:

6–8 weeks → starts working
4–6 months → full benefit

Topical Products can have: - skip

• analgesic effect

• antipruritic effect

• anti-inflammatory effect

• anesthetic effect

• counterirritant effect

Topical Products used for:

• minor–moderate muscle/joint pain → often add-on therapy

Topical Products

name them all…

→ Voltaren = topical NSAID for OA

→ Lidocaine = anesthetic for neuropathy

→ Counterirritants = methyl salicylate, camphor, menthol, capsaicin

→ Trolamine salicylate = NOT counterirritant

1. V L C T = “Vardhan Loves Chandler Too”

2. M C M C = “My Cute Mom Cooks”

Topical Products

Voltaren

• diclofenac gel 1% - arthritis pain only

• 2 – 4 – 7 – 21

  • 2 g upper

  • 4 g lower

  • 7 days to effect

  • 21 days max self-care

  • And 4×/day + max 2 areas.

Topical Products

Lidocaine

• neuropathic pain

• (anesthetic) blocks nerve impulses / Na⁺ channels

• OTC: 0.5–4%

• Rx Lidoderm patch: 5%

Topical Products

Counterirritants - skip

• Concept: DISTRACT from deeper pain

• Mechanisms discussed:

  • Vasodilation leads Rubefaction → Methyl salicylate

  • Cooling → Camphor + Menthol

  • Irritation without rubefaction → Capsaicin

Topical Products

Counterirritants - table

• Concept: DISTRACT from deeper pain

• Methyl salicylate → vasodilation → rubefaction/HEAT

  • Heat/exercise ↑ absorption → ↑ toxicity

  • Avoid ≤19 years

• Camphor → cooling

  • Toxicity → CNS effects/seizures → avoid in children

• Menthol → cooling

  • cold → warm

• Capsaicin → irritation/burning

  • 3–4×/day

  • Burning/stinging decreases with repeated use

  • TAKES TIME: May start helping around 14 days; can take 4–6 weeks

  • Avoid mucous membranes / wash hands

Topical Products

Trolamine Salicylate

• NOT a counterirritant

• Mechanism discussed:

→ salicylate collects in synovial fluid.

General Topical Counseling

• no heat, no tight wrap, no broken skin, no eyes/mouth/genitals;

• pain/swelling/blisters = STOP.

General Topical Counseling

Combination products

• Do NOT combine two products from the same topical category

• Do NOT combine counterirritant + skin protectant

• Low priority: an ingredient can be listed as “inactive” if the amount is too low to be therapeutic

• Check the ingredient list, not just the brand name

Topical populations we talk about?

1. Minimum age varies by product:

• OTC monograph: ≥2 yr

• many products: ≥13 yr

• some: ≥18 yr

→ Always check individual label.

2. Pregnancy:

→ avoid musculoskeletal self-care / refer.

Main Musculoskeletal Case:

70-year-old:

• lower-back soreness after yard work

• pain 4/10

• uncontrolled HTN

• CAD

• taking levofloxacin

Self-care?

✅ YES

Pain is not severe and there is a clear muscular overexertion cause.

Medication choice

His:

• uncontrolled HTN

• CAD

do not automatically exclude self-care, but they affect drug selection.

→ avoid NSAID
→ acetaminophen appropriate.

Levofloxacin

🟡 Remember fluoroquinolones can cause tendon injury.

But in this case:

• pain is lower-back muscular soreness

• clear trigger = yard work

• tendon rupture would present differently/more severely.

⭐ Final professor emphasis

If oral therapy can safely be used:

oral systemic therapy first

Topical:

→ adjunct OR alternative when oral therapy cannot be used.