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Comprehensive Notes: Musculoskeletal Disorders (MSD) - Complete Module Guide

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MS-CM-001 | Low Back Pain (LBP)

Causes of Low Back Pain

A. Mechanical / Structural Causes (most common, ~85%)

B. Non-Mechanical Causes (Red Flags - Require Urgent Investigation)

• Neoplastic: primary or metastatic spinal tumors (pain worse at night/recumbent, not relieved by rest)
• Inflammatory: ankylosing spondylitis, reactive arthritis (morning stiffness >1 hour, improves with activity)
• Infectious: vertebral osteomyelitis, discitis, epidural abscess (fever, tenderness, history of IV drug use)
• Traumatic: vertebral fractures (post-trauma, or low-energy in osteoporotic patients)
• Vascular: aortic aneurysm (pulsatile mass, severe sudden onset, vascular risk factors)

C. Referred / Visceral Causes

• Kidney stones, pyelonephritis
• Pancreatic disease, retroperitoneal hematoma
• Gynecological causes (endometriosis, ovarian cysts)
• Prostate disorders

D. Psychosocial Factors (Yellow Flags)

• Depression, anxiety, catastrophization, fear-avoidance behavior
• Chronic LBP has co-prevalence of depression in 33-67%, anxiety in 10-30%
• Substance misuse disorders in 13-40%
• Biopsychosocial model: psychological and social factors significantly modulate pain perception

Red Flag Symptoms Warranting Imaging

• Progressive neurologic deficit (weakness, sensory loss, sphincter dysfunction)
• Pain aggravated by Valsalva/recumbency
• Post-trauma
• Fever + tenderness
• History of malignancy
• Night pain unrelieved by rest (Harrison's Principles of Internal Medicine 22E)

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Prevention of Low Back Pain

Primary Prevention

1. Exercise and core strengthening - Regular aerobic activity (walking, swimming); specific lumbar stabilization exercises strengthen paraspinal and abdominal muscles
2. Weight management - Obesity increases lumbar loading; BMI >30 is an independent risk factor
3. Ergonomic workplace design - Adjustable seating, lumbar support, avoiding prolonged static postures
4. Proper lifting technique - Squat-lift (spine neutral, power from legs); avoid twisting while lifting
5. Posture education - Neutral spine during sitting, standing, and sleeping; avoid prolonged forward flexion
6. Smoking cessation - Smoking impairs disc nutrition through reduced capillary flow

Secondary Prevention (Preventing Chronicity)

1. Early mobilization - Bed rest is NOT recommended; early return to normal activities improves outcomes
2. Physical therapy - Targeted physiotherapy, core stabilization, McKenzie exercises
3. Education and reassurance - Pain neuroscience education reduces fear-avoidance
4. Address psychosocial factors - Screen for depression/anxiety; cognitive behavioral therapy (CBT) has strong evidence for chronic LBP
5. Avoid over-medicalization - Avoid routine imaging for acute non-specific LBP (does not improve outcomes, increases nocebo effect)

Pharmacological Prevention of Progression

• NSAIDs as first-line for acute flares (not acetaminophen alone - no longer recommended as first-line)
• Muscle relaxants for acute spasm
• Duloxetine (SNRI) for chronic LBP with co-existing depression
• Opioids: last resort, short duration, lowest effective dose (Harrison's Principles of Internal Medicine 22E; Bradley and Daroff's Neurology)

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MS-CM-002 | Work-Related Musculoskeletal Disorders (WMSDs)

Definition

Burden / Epidemiology

• WMSDs comprise at least 50% of all nonfatal workplace injury cases resulting in days away from work
• The cost of work-related disability from MSDs in the United States was estimated at approximately 1% of gross national product
• Worldwide ergonomic/occupational disability from LBP in 2010 affected up to 26% of the global population
• Low back pain is the most common work-related musculoskeletal complaint globally
• Globally, approximately 1.71 billion people live with musculoskeletal conditions (Global Burden of Disease 2019)
• WMSDs are the leading contributor to disability worldwide
• Industries with highest rates: meatpacking, knit-underwear manufacturing, motor vehicle manufacturing, poultry processing, mail/message distribution, healthcare, construction, food processing, nursing assistance, agriculture
• Distribution of WMSDs by body region: neck (56%), shoulder (47%), lower back (46%) - from office worker studies 2024

Historical Occupation-Specific Syndromes (Table)

Risk Factors for WMSDs at the Workplace

Physical / Biomechanical Risk Factors

Organizational / Psychosocial Risk Factors

• Short work cycle times with little task variety
• Frequent tight deadlines, high cognitive demands
• Inadequate rest/recovery periods
• Little control over work pace or methods
• Cold work environment
• Localized mechanical stresses (e.g., pressing forearm against hard edge)
• Poor spinal support in seating

Prevention of Exposure to Workplace Risk Factors

Engineering Controls (Eliminate/Reduce the Hazard)

1. Workstation redesign - adjustable height desks, chairs with lumbar support
2. Mechanical assists - hoists, dollies, conveyor belts to reduce manual lifting loads
3. Anti-vibration tool handles and anti-fatigue mats
4. Tool/handle redesign to allow neutral wrist posture

Administrative Controls (Change Work Practices)

1. Job rotation - rotate workers between high-exposure and low-exposure tasks
2. Rest breaks - mandatory micro-breaks every 30-45 minutes for repetitive tasks
3. Pacing - avoid machine-paced work; allow worker control over speed
4. Limit cumulative lift weight per shift

Personal Protective Equipment and Training

1. Back support belts (limited evidence; do not replace engineering controls)
2. Training in proper lifting technique (squat-lift; load close to body; no twisting)
3. Ergonomics education programs
4. Early reporting of symptoms culture

Rehabilitation for Affected Workers

• Protection from aggravating tasks during recovery
• Restoration of strength and dynamic stability (physiotherapy)
• Graduated return-to-work programs with modified duties (Firestein & Kelley's Textbook of Rheumatology)

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MS-CM-003 | MSD Related to Mobile Usage

Burden / Epidemiology

• Prevalence of musculoskeletal complaints among mobile device users: 1.0% to 67.8% (wide range due to study design differences)
• Studies consistently show significant association between smartphone use time and neck/shoulder pain intensity
• Among students with text neck syndrome: 31.7% have mild neck disabilities, with higher prevalence in females (40%)
• Significant correlation between smartphone addiction scale scores and neck disability index (NDI)
• Repetitive thumb use on touchscreens is increasingly linked to de Quervain tenosynovitis and trigger thumb

Disorders Related to Mobile Usage

1. Text Neck Syndrome

• Definition: Overuse injury of the cervical spine caused by sustained forward-flexed head posture while looking at a mobile device
• Mechanism: For every inch the head moves forward, the effective weight on the cervical spine increases. At 0° (neutral), head weighs ~12 lbs; at 60° flexion (typical texting posture), effective load is ~60 lbs
• Symptoms: Neck pain, stiffness, headaches, radiating pain to shoulders/arms, reduced cervical range of motion, early degenerative changes
• Structures affected: Cervical muscles (trapezius, levator scapulae, sternocleidomastoid), cervical discs, facet joints, ligaments
• Epidemiology: Prevalence rising particularly among youth; females more affected; correlates directly with daily screen time

2. Trigger Thumb (Stenosing Flexor Tenosynovitis)

• Definition: Inflammation of the flexor pollicis longus tendon sheath causing a size mismatch between the tendon and its sheath at the A1 pulley
• Mechanism: Repetitive thumb flexion (typing, scrolling, gaming) causes microtrauma and inflammation at the first annular (A1) pulley
• Symptoms: Pain and clicking/locking of the thumb in flexion; may progress to fixed flexion deformity
• In adults: Associated with repetitive smartphone use; middle-aged women particularly affected
• Treatment: Rest, splinting, corticosteroid injection; surgical A1 pulley release for refractory cases (Campbell's Operative Orthopaedics 15th Ed; Sabiston Textbook of Surgery)

3. De Quervain Tenosynovitis

• Definition: Stenosing tenosynovitis of the first extensor compartment of the wrist (abductor pollicis longus + extensor pollicis brevis tendons)
• Mechanism: Repetitive pinching, gripping, and lateral deviation of the wrist - common with texting, scrolling, gaming
• Typical patient: Middle-aged women, new mothers, golfers, and increasingly smartphone users
• Symptoms: Pain and swelling at the radial styloid/base of thumb; positive Finkelstein test (thumb in palm, ulnar deviation = pain)
• Treatment: Thumb spica splint, NSAIDs, corticosteroid injection into first extensor compartment; surgical release of first compartment if conservative treatment fails (Miller's Review of Orthopaedics; Sabiston Textbook of Surgery)

4. Carpal Tunnel Syndrome (CTS)

• Definition: Compression of the median nerve within the carpal tunnel at the wrist
• Mechanism: Prolonged wrist flexion/extension while holding devices; sustained grip; repetitive tapping on screens increases pressure in carpal tunnel
• Risk factors: Female sex, age 40-60, repetitive wrist use, vibration, obesity, diabetes, hypothyroidism, pregnancy
• Symptoms: Numbness/tingling in the thumb, index, middle, and radial half of ring finger (median nerve distribution); nocturnal symptoms; thenar wasting in severe cases
• Tests: Tinel's sign (tapping over carpal tunnel), Phalen's test (sustained wrist flexion x 60 sec)
• Treatment: Wrist splint in neutral position (especially nocturnal), corticosteroid injection, surgical carpal tunnel release (Sabiston Textbook of Surgery; Goldman-Cecil Medicine)

Risk Factors for Mobile-Related MSD

1. Duration of use - >2-3 hours/day continuous use is high-risk
2. Posture - Neck forward flexion >30°, wrist flexion/deviation during typing
3. Grip force - Tight grip on device activates forearm flexors excessively
4. Lack of breaks - No rest between sessions
5. Device size - Smaller screens require more neck flexion and finer thumb movements
6. Age - Young adults (students) are highest-risk group by exposure time
7. Sex - Females have higher prevalence (smaller tendon sheaths, hormonal factors)
8. Existing conditions - Diabetes, hypothyroidism, obesity amplify CTS risk
9. Phone addiction/behavioral factors - Nomophobia, compulsive checking behavior

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MS-CM-004 | Ergonomics Applied to MSD Prevention

Definition of Ergonomics

Domains of Ergonomics

Application to Specific Disorders

For Low Back Pain (Office/Industrial Ergonomics)

• Chair height: Feet flat on floor, hips and knees at 90°, lumbar lordosis supported
• Monitor height: Top of screen at or slightly below eye level (prevents neck flexion)
• Desk height: Elbows at 90° when typing; forearms parallel to floor
• Sit-stand workstations: Alternate sitting and standing every 30-60 minutes
• Monitor distance: Arm's length (~50-70 cm) from eyes
• Consequences of poor ergonomics: Repetitive microtrauma, sustained muscle activation, cumulative loading on discs and joints leading to pain and injury

For Text Neck / Mobile Use

• Device position: Hold phone at eye level rather than neck-flexed position
• Neutral cervical posture education: Ear directly over shoulder over hip in sagittal plane
• Screen angle apps/stands: Use phone stands/holders rather than holding device
• Take micro-breaks: 20-20-20 rule modified for neck: every 20 minutes, look up for 20 seconds
• Voice input: Use voice-to-text to reduce thumb and neck loading

For De Quervain / Trigger Thumb

• Pinch vs. whole-hand grip: Use larger buttons/keys; avoid repetitive pinch grip
• Ergonomic phone cases: Finger rings/loops reduce need for tight gripping
• Stylus use: Reduces direct screen-tapping forces
• Break frequency: Thumb stretching every 30 minutes

For Carpal Tunnel Syndrome

• Wrist posture: Maintain neutral wrist (0° flexion/extension) during typing
• Ergonomic keyboards: Split keyboards, negative tilt keyboards reduce wrist deviation
• Wrist rests: Used correctly (between keystrokes, not while typing) reduce sustained loading
• Mouse ergonomics: Vertical mice maintain forearm in neutral pronation/supination
• Voice recognition software: Reduces total keying volume

Ergonomics in Surgical / Clinical Settings

• Surgeons' MSD burden: 68% of surgeons report generalized pain from operating; back (50%), neck (48%), arm/shoulder (43%)
• Healthcare sector: In 2022, had the highest number of nonfatal work-related injuries (665,300 in the US)
• Anti-fatigue mats: Reduce cumulative loading on lower limbs during prolonged standing
• Adjustable OR table height: Maintain surgeon's elbows at ~90° for open procedures
• Laparoscopic ergonomics: Monitor at eye level; instrument handles fit surgeon's grip span (Sabiston Textbook of Surgery)

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MS-CM-005 | Non-Communicable Musculoskeletal Disorders (NCDs)

Concept

Key Characteristics

• Chronic course: Persistent or recurrent symptoms lasting months to years
• Multifactorial etiology: No single cause; risk factors are cumulative
• Major disability burden: MSDs are the highest contributor to the global rehabilitation need
• Prevention-oriented: Most risk factors are modifiable

Major Non-Communicable MSDs

Common Risk Factor Framework for Non-Communicable MSDs

• Non-modifiable: Age, sex, genetics, race/ethnicity
• Modifiable lifestyle: Physical inactivity, obesity, smoking, poor nutrition, excessive alcohol
• Biomechanical: Repetitive loading, poor posture, occupational exposure
• Metabolic: Diabetes, vitamin D deficiency, calcium deficiency

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MS-CM-006 | Risk Factors for Osteoporosis in the Community

Risk Factors

Non-Modifiable Risk Factors

Modifiable Lifestyle Risk Factors

Medical / Pharmacological Risk Factors

Community-Level Prevention of Osteoporosis

• Physical activity: Weight-bearing and resistance exercise (walking, jogging, resistance training) at all ages; particularly in adolescence to maximize peak bone mass
• Calcium intake: 1200-1500 mg/day for adults over 50 (dairy, leafy greens, fortified foods)
• Vitamin D supplementation: 800-1000 IU/day for adults over 50; sun exposure (15-30 min/day)
• Fall prevention programs: In the elderly (home hazard removal, balance training, vision correction)
• Smoking cessation and alcohol reduction
• Screening: DXA scan for women >65 years and postmenopausal women <65 with risk factors (FRAX score)
• Pharmacological: Bisphosphonates (alendronate, zoledronic acid) for confirmed osteoporosis or fragility fracture - inhibit osteoclastic bone resorption

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Quick Reference Summary

• WHO Musculoskeletal Fact Sheet - 1.71 billion people globally affected
• Harrison's Principles of Internal Medicine 22E
• Firestein & Kelley's Textbook of Rheumatology
• Miller's Review of Orthopaedics 9th Edition
• Sabiston Textbook of Surgery (Ergonomics chapter)
• Campbell's Operative Orthopaedics 15th Ed 2026

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MSK Community Medicine Notes

1st Year MBBS | UHS Level

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MS-CM-001 | LOW BACK PAIN (LBP)

What is Low Back Pain?

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CAUSES of Low Back Pain

1. Mechanical Causes (Most Common - 85%)

2. Non-Mechanical Causes (Red Flag Causes - Serious!)

• Cancer - pain worse at night, doesn't go away with rest
• Infection - (e.g., TB spine / discitis) - fever + back pain + tenderness
• Fracture - especially in osteoporotic elderly patients
• Ankylosing spondylitis - morning stiffness >1 hour, young male, improves with activity
• Aortic aneurysm - severe sudden back pain, pulsating abdominal mass

3. Referred Pain (Pain Coming from Another Organ)

• Kidney stones / infection
• Ovarian cysts / endometriosis
• Prostate problems
• Pancreatitis

4. Psychosocial Causes

• Depression, anxiety, stress
• Fear-avoidance behavior (afraid to move)
• Poor coping skills
• Work dissatisfaction

Mnemonic for Red Flags: "TUNA FISH" Tumor, Unrelenting pain at night, Neurological deficit, Age >50 or <20, Fever, Infection history, Steroid/Osteoporosis, History of trauma

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PREVENTION of Low Back Pain

Primary Prevention (Stop it Before it Happens)

1. Exercise - Regular walking, swimming; core-strengthening exercises
2. Correct posture - Sit upright, ear over shoulder over hip
3. Proper lifting - Bend the knees, keep back straight, lift with legs (squat-lift method)
4. Healthy weight - Obesity adds load on lumbar spine
5. Ergonomics at work - Proper chair height, lumbar support, monitor at eye level
6. Stop smoking - Reduces blood supply to spinal discs

Secondary Prevention (Stop it Getting Worse / Chronic)

1. Early movement - Do NOT rest in bed; stay active (bed rest makes it worse!)
2. Physiotherapy - Core exercises, McKenzie method
3. Pain education - Understand that pain doesn't always mean damage
4. Treat depression/anxiety - CBT (cognitive behavioral therapy)
5. Avoid unnecessary imaging - Does not improve outcomes for non-specific LBP

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MS-CM-002 | WORK-RELATED MUSCULOSKELETAL DISORDERS (WMSDs)

Definition

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Burden / Epidemiology

• WMSDs = at least 50% of all workplace injuries causing days off work
• Cost in USA = about 1% of Gross National Product
• 26% of the world's population suffers occupational disability from low back pain
• 1.71 billion people globally live with MSDs (WHO/GBD 2019)
• MSDs are the leading cause of disability worldwide
• Most affected body regions: Neck > Shoulder > Lower Back
• Low back pain is the single most common work-related MSD

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RISK FACTORS for WMSDs at the Workplace

Physical Risk Factors (Remember "RAMPS F")

• R - Repetition (same movement over and over)
• A - Awkward posture (bending, twisting, reaching)
• M - Manual handling / heavy lifting
• P - Prolonged static posture (standing/sitting without moving)
• S - Sustained force (gripping tools hard)
• F - Force and vibration (power tools, hand-arm vibration)

By Body Region

Organizational / Psychosocial Risk Factors

• No rest breaks
• High work demands, tight deadlines
• No control over work pace
• Monotonous tasks, poor job satisfaction
• Cold work environment

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Prevention of Exposure to WMSD Risk Factors

1. Engineering Controls (Best - Eliminate the Hazard)

• Adjustable desks and chairs
• Mechanical hoists/cranes for heavy lifting
• Anti-vibration tool handles
• Conveyor belts (avoid manual carrying)
• Anti-fatigue mats for standing workers

2. Administrative Controls (Change How Work is Done)

• Job rotation (alternate between high and low-risk tasks)
• Regular rest breaks (every 30-45 minutes)
• Limit daily lift weight
• Reduce shift duration for high-risk tasks
• Training programs on proper lifting technique

3. Personal Protective Measures

• Proper lifting technique education (squat-lift)
• Back support belts (limited evidence but used in practice)
• Ergonomics training
• Early symptom reporting culture in workplace

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MS-CM-003 | MSD RELATED TO MOBILE USAGE

Burden / Epidemiology

• Prevalence of MSDs among mobile users: 1% to 68% (wide range - varies by study)
• Neck complaints are the most common
• 31.7% of students with text neck have neck disability; females more affected (40%)
• Significant correlation between smartphone addiction scores and neck disability index
• Rising rapidly among young adults and students worldwide

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DISORDERS Related to Mobile Use

1. Text Neck Syndrome

• What it is: Neck and shoulder pain caused by looking down at a phone for long periods
• Mechanism: The more the neck bends forward, the heavier the head feels on the spine:
  • 0° (upright) = ~5-6 kg (normal head weight)
  • 30° forward = ~18 kg
  • 60° forward (texting position) = ~27 kg
• Symptoms: Neck pain, stiffness, headaches, shoulder pain, reduced neck movement
• Who gets it: Students, young adults, heavy phone users

2. Trigger Thumb

• What it is: The thumb gets "stuck" or clicks when bent/straightened
• Cause: Inflammation of the flexor tendon sheath at the base of the thumb (A1 pulley)
• How phones cause it: Repetitive thumb scrolling and tapping = microtrauma + inflammation
• Symptoms: Pain + clicking/locking of thumb; worse in the morning
• Treatment: Rest, splint, steroid injection; surgery in severe cases

3. De Quervain Tenosynovitis

• What it is: Pain at the thumb-side of the wrist
• Cause: Inflammation of two tendons (APL + EPB) in the first extensor compartment of the wrist
• How phones cause it: Repetitive pinching and lateral wrist movement while texting
• Classic patient: Middle-aged women, new mothers, heavy phone/gamers
• Key Test: Finkelstein test - Fold thumb in palm, make fist, bend wrist towards little finger side → pain = positive
• Treatment: Thumb spica splint, NSAIDs, steroid injection, surgery if needed

4. Carpal Tunnel Syndrome (CTS)

• What it is: Pressure on the median nerve inside the carpal tunnel at the wrist
• Cause: Prolonged wrist bending while holding phone; repetitive tapping raises tunnel pressure
• Symptoms: Numbness/tingling in thumb, index, middle, and half of ring finger; worse at night; thenar muscle wasting (late)
• Key Tests:
  • Tinel's sign - Tap over wrist = tingling/electric shock in fingers
  • Phalen's test - Hold wrists bent for 60 seconds = symptoms appear
• Treatment: Wrist splint (neutral), steroid injection, carpal tunnel release surgery

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Risk Factors for Mobile-Related MSD

1. More than 2-3 hours/day continuous phone use
2. Neck bent forward >30° while using phone
3. Tight grip on device
4. No rest breaks between sessions
5. Small screen requiring more precise movements
6. Female sex (smaller tendons, hormonal factors)
7. Existing diabetes or thyroid disease (amplifies CTS)
8. Phone addiction / compulsive checking (nomophobia)

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Preventive Strategies for Mobile-Related MSD

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MS-CM-004 | ERGONOMICS

Definition

"The science of designing work, products, and environments to fit the human body - to prevent injury and improve efficiency."

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Three Domains of Ergonomics

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Application in Specific Disorders

Office Ergonomics (LBP / Neck Pain)

• Chair: Back supported, feet flat on floor, hips + knees at 90°
• Monitor: Top of screen at eye level, arm's length away
• Keyboard: Wrists neutral (flat), elbows at 90°
• Take standing breaks every 30-60 minutes
• Use sit-stand desks if possible

Mobile Ergonomics (Text Neck / Thumb Conditions)

• Hold phone at eye level (not in lap)
• Use stylus instead of finger for precision work
• Finger loops/handles on phone
• Ergonomic phone stands

For CTS / De Quervain

• Keep wrist neutral while typing (do not bend up or down)
• Split ergonomic keyboards
• Vertical mouse (neutral forearm position)
• Voice recognition software to reduce typing

Principles Hierarchy ("Most Effective to Least"):

1. Eliminate the hazard (automation, redesign)
2. Substitute (replace heavy tool with lighter one)
3. Engineering controls (adjustable workstations)
4. Administrative controls (breaks, rotation)
5. PPE / Personal controls (back belts, wrist braces)

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MS-CM-005 | NON-COMMUNICABLE MUSCULOSKELETAL DISORDERS (NCDs)

Concept

• Are NOT caused by infections (no germ/microbe)
• Cannot spread from person to person
• Develop slowly over years
• Are caused by lifestyle, aging, genetics, and mechanical factors

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Key Examples of Non-Communicable MSDs

Common Risk Factors for NCDs (Same Pattern Across Diseases)

• Non-modifiable: Age, sex, family history, ethnicity
• Modifiable: Physical inactivity, obesity, poor diet, smoking, alcohol
• Biomechanical: Repetitive loading, poor posture, occupation
• Metabolic: Vitamin D deficiency, calcium deficiency, diabetes

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MS-CM-006 | OSTEOPOROSIS - RISK FACTORS IN THE COMMUNITY

What is Osteoporosis?

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Risk Factors - Complete List

Non-Modifiable (Cannot Change)

Modifiable Lifestyle (Can Change)

Drugs / Medical Causes

Mnemonic for Osteoporosis Risk: "SHATTERED" Steroid use, Hyperthyroidism, Alcohol, Thin body/low BMI, Tobacco, Estrogen low (menopause/premature), Race (white/Asian), Elderly, Diet (low Ca/VitD)

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Prevention of Osteoporosis in the Community

1. Calcium intake - 1200-1500 mg/day (milk, yogurt, cheese, leafy greens)
2. Vitamin D - 800-1000 IU/day + 15-30 minutes of sunlight daily
3. Weight-bearing exercise - Walking, jogging, dancing, resistance training
4. Stop smoking and limit alcohol
5. Fall prevention in elderly - Remove home hazards, improve lighting, use walking aids
6. Balance training - Reduces fall risk in osteoporotic patients
7. DXA bone scan screening - Women >65 years, or younger with risk factors
8. Bisphosphonates (alendronate, zoledronic acid) - For confirmed osteoporosis

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SUMMARY TABLE FOR QUICK REVISION

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Note for UHS exams: Focus on definitions, risk factors (non-modifiable vs. modifiable), epidemiology figures, clinical features of mobile-related MSDs, and the Finkelstein, Tinel, and Phalen tests. Short-answer questions frequently ask you to "classify" and "describe" - use the tables above directly.