Musculoskeletal System Lecture Notes

Overview of Spinal Curvature

• Normal Spinal Curvature (Sagittal View): When viewed from the side, a healthy spine exhibits an S-shaped curve. This configuration is essential for core balance, stability, flexibility, and ensuring an even distribution of weight during movement.

• Regional Curvatures:

  • Cervical Spine: Exhibits an inward curve, described as a backward C-shape or a lordotic curve.

  • Thoracic Spine: Exhibits an outward curve, described as a C-shape or a kyphotic curve.

  • Lumbar Spine: Exhibits an inward curve, identical to the cervical spine (backward C-shape or lordotic curve).

• Anatomical Landmarks for Neck Alignment:

  • A: Atlas

  • B: Axis

  • C: Intervertebral Foramen

  • D: Seventh Cervical ($C7$)

  • E: First Thoracic ($T1$)

  • F: Shoulder

  • G: Spinous Process

  • H: Jaw

  • I: Occiput

  • J: Skull

• Neutral Lateral Cervical Alignment Characteristics:

  • Equal disc spacing.

  • Well-defined edges.

  • Presence of a graceful forward curve.

  • Optimum range of motion ($ROM$).

Cervical Kyphosis (Military Neck)

• Definition: A condition where the cervical spine is straight or reversed (kyphotic) rather than possessing the normal lordotic curve.

• Primary Causes:

  • Poor Posture: Prolonged periods of improper neck and upper back alignment, such as slouching over computer screens or smartphones.

  • Degenerative Disc Disease (DDD): Age-related wear and tear where intervertebral discs wear down.

  • Ankylosing Spondylitis: An autoimmune disease causing arthritis that often affects the sacroiliac ($SI$) joints and the spine.

  • Spinal Injuries: Trauma resulting from accidents, such as Motor Vehicle Accidents ($MVA$).

  • Osteoporosis: Weakening of the skeletal structure impacting the spine.

  • Congenital Factors: Genetic predisposition toward spinal abnormalities.

  • Spinal Tumors: Most commonly secondary to cancer metastasis.

• Symptoms:

  • Pain in the neck, back, shoulders, or arms.

  • Decreased range of motion.

  • Headaches, specifically tension-type headaches.

  • Muscle weakness in the neck and upper back.

  • Radiculopathy: Numbness and tingling radiating into the arms and hands due to nerve compression.

  • Instability during walking and poor posture.

  • Dysphagia: Difficulty swallowing caused by improper neck alignment.

  • Poor urinary or fecal control.

• Treatment Modalities:

  • Physical Therapy: Focuses on traction, posture correction, strengthening, and $ROM$ exercises.

  • Osteopathy and Acupuncture.

  • Cervical Decompression: Gentle stretching to create negative pressure, reducing load on nerves and discs.

  • Surgery: Reserved for severe cases.

• Prevention Strategies:

  • Maintain proper posture while sitting.

  • Perform regular neck/upper back stretching and strengthening.

  • Utilize ergonomic workspaces.

  • Avoid excessively large pillows to prevent neck flexion while sleeping.

Major Spinal Deformities: Kyphosis, Lordosis, and Scoliosis

• Kyphosis:

  • Definition: Excessive forward rounding of the upper spine, often resulting in a "humpback" or "hunchback."

  • Synonyms: Dowager’s hump, neck hump, text hump, round back, or military neck.

  • Differential Diagnosis: Must be distinguished from a "buffalo hump," which is a symptom of Cushing’s disease (excess fat due to surplus cortisol).

  • Demographics: In older adults, it often results from osteoporotic compression fractures. In children/teens, it may result from malformation or conditions like Ehlers-Danlos syndrome.

  • Age-related Postural Hyperkyphosis Consequences:

    • Increases with the number of vertebral fractures.

    • Impairs mobility and increases the risk of falls and further fractures.

    • Hyperkyphosis due to osteoporosis can significantly impair lung function.

• Lordosis:

  • Definition: Excessive inward curvature of the spine.

  • Demographics: Common in adults over age $50$, children during growth spurts, and during pregnancy.

  • Anatomic Impact: Typically affects the lumbar spine (lumbar lordosis), pushing the hips and pelvis forward and making the buttocks appear more prominent. It creates extra space beneath the lower back when the patient is lying supine.

  • Causes: Idiopathic, Spondylolisthesis (vertebra slips out of place), osteoporosis, osteosarcoma, and muscular dystrophy.

• Scoliosis:

  • Definition: Abnormal sideways curvature of the spine into a C or S shape.

  • Prevalence: Affects approximately $2\%$ of the global population.

  • Symptoms: Most cases are mild; severe cases present with uneven posture, back/leg pain, and numbness.

  • Types:

    • Idiopathic: Most common; unknown cause, likely genetic.

    • Congenital: Vertebral malformation during embryonic development.

    • Neuromuscular: Linked to nerve or muscle abnormalities in conditions like cerebral palsy, spina bifida, or muscular dystrophy.

Inflammation: Acute and Chronic

• General Definition: Part of the body’s defense mechanism against injury or foreign invaders (infections, toxins). Suffix suffix "-itis" denotes inflammation (e.g., Pharyngitis, Arthritis).

• Acute Inflammation:

  • Onset/Duration: Rapid onset, lasting only a few days.

  • Major Cells: Neutrophils and mononuclear cells (monocytes, macrophages).

  • Primary Mediators: Vasoactive amines and eicosanoids.

  • Outcomes: Resolution, abscess formation, or transition to chronic inflammation.

• Chronic Inflammation:

  • Onset/Duration: Delayed onset, lasting months to years.

  • Causative Agents: Persistent pathogens, non-degradable foreign bodies, or autoimmune reactions.

  • Major Cells: Monocytes, macrophages, lymphocytes, plasma cells, and fibroblasts.

  • Primary Mediators: $IFN\text{-}\gamma$, cytokines, growth factors, reactive oxygen species, and hydrolytic enzymes.

  • Outcomes: Tissue destruction and fibrosis.

• The 5 Cardinal Signs of Inflammation:

  • Rubor (Redness): Due to increased blood flow.

  • Calor (Heat): Due to increased blood flow.

  • Tumor (Swelling): Due to accumulation of fluid and cells.

  • Dolor (Pain): Due to stimulation of sensory neurons by inflammatory mediators.

  • Functio Laesa (Loss of Function): Due to tissue damage.

• Symptoms of Chronic Inflammation: Body pain, chronic fatigue, depression/anxiety, gastrointestinal complications (constipation/acid reflux), weight fluctuations, and persistent infections.

Acute Traumatic Musculoskeletal Injuries

• Examples: Blunt trauma, fractures, contusions, concussions, sprains, dislocations, and muscle/ligament tears.

• Management Protocol (PRICES):

  • P: Protection

  • R: Rest

  • I: Ice

  • C: Compression

  • E: Elevation

  • S: Stabilization

• Timing: Prices is most effective within $24\text{--}72\,hours$ post-injury.

• Classification: Injuries are categorized as Acute; Chronic (recurring); or Chronic (overuse).

Conditions of the Upper Extremities

• Rotator Cuff Injuries:

  • Muscles involved (SITS): Supraspinatus, Infraspinatus, Teres Minor, Subscapularis.

  • Mechanism: Repetitive overhead motions (painters, carpenters, swimmers, pitchers).

  • S/Sx: Dull shoulder ache, worse at night, worse with abduction/flexion.

  • Diagnosis: Physical Exam (Apley scratch test), MRI, or Arthroscopy.

• Shoulder (Glenoid) Labrum Tears:

  • Anatomy: Fibrocartilaginous ring that deepens the shallow glenoid socket.

  • Mechanism: Throwing sports or falling on an outstretched shoulder.

  • S/Sx: Painful clicking, clunking, or "locking" sensation.

  • Diagnosis: MRA (MR Arthrography) is more accurate than standard MRI.

• Brachial Plexus Injury:

  • Mechanism: Nerves (C5-T1) are stretched or torn. Common in football or birth trauma.

  • Symptoms: "Stingers" or "burners" (electric shock sensations), numbness/weakness.

• Frozen Shoulder (Adhesive Capsulitis):

  • Risk Factors: Diabetes, thyroid conditions, Parkinson’s disease.

  • Stages:

    1. Freezing: ($6\,weeks \text{ to } 9\,months$) Pain and limited $ROM$.

    2. Frozen: ($4\text{--}6\,months$) Pain improves, but shoulder is stiff.

    3. Thawing: ($6\,months \text{ to } 2\,years$) Slow return to normal motion.

• Epicondylitis:

  • Medial (Golfer’s Elbow): Inflammation of flexor-pronator muscles at the medial epicondyle. Pain occurs when flexing the wrist/pronation.

  • Lateral (Tennis Elbow): Inflammation of extensor tendons. Mill’s Test (passive wrist flexion and pronation) is diagnostic.

• Carpal Tunnel Syndrome:

  • Mechanism: Median nerve compression in the wrist.

  • Diagnosis: Tinel’s sign (tapping nerve) and Phalen’s sign.

• Dupuytren’s Contracture:

  • S/Sx: Thickening of palmar fascia forming cords; typically affects the $4th$ and $5th$ digits.

  • Diagnosis: Tabletop test (inability to lay hand flat).

  • Treatment: Collagenase (Xiaflex) injections or fasciectomy.

• Trigger Finger:

  • Pathology: Inflammation/thickening of the A1 pulley, preventing the flexor tendon from gliding.

Conditions of the Lower Extremities

• Hamstring Strain:

  • Grades: Grade $1$ (pull); Grade $2$ (partial tear); Grade $3$ (complete tear/avulsion).

  • Prevention: Strengthen the gluteal muscles (as glutes/hamstrings work together) and stretch quadriceps.

• Knee Bursitis: Inflammation of the bursa (fluid-filled sac). Requires aspiration if infection/gout is suspected.

• Meniscal Tears:

  • Mechanism: Valgus force (force pushing toward the center of the body) or twisting.

  • Diagnosis: McMurray test (pain/clicking during rotation).

  • Healing: Outer $1/3$ has blood supply and may heal; inner $2/3$ lacks supply.

• Platelet-Rich Plasma (PRP): Concentrating platelets ($3\text{--}5\,times$ normal concentration) and injecting them into the injury site to utilize growth factors for regeneration.

• Patellar Tendinitis (Jumper’s Knee): Overuse injury from jumping; pain is usually felt under the kneecap.

• Chondromalacia Patella (Runner’s Knee): Softening and degeneration of the patellar cartilage.

• Shin Splints (Medial Tibial Stress Syndrome): Diffuse pain along the tibia, worse with activity.

• Stress Fractures: Tiny bone cracks from repeated micro-injuries (marching/running). Healing takes $6\text{--}8\,weeks$.

Clinical Workup for Neck and Back Pain

• History of Present Illness (HPI): Quality, onset, duration, location, radiation, and whether relief is found with rest or activity.

• Red Flags (Review of Systems):

  • Fever/chills (infection).

  • Unexplained weight loss/anorexia (cancer).

  • Urinary/fecal incontinence (Cauda Equina - medical emergency).

  • Pain worse with inspiration (pulmonary).

• Physical Exam Tests:

  • Straight Leg Raise (SLR) Test:

    • $0\text{--}30^{\circ}:$ Slack taken up in sciatic nerve.

    • $30\text{--}70^{\circ}:$ Tension and movement of sciatic nerve.

    • > 70^{\circ}: Tension of other structures.

Degenerative and Traumatic Spinal Disorders

• Sciatica: Pain radiating from the buttocks down the leg, often due to lumbar nerve root compression.

• Degenerative Disc Disease (DDD):

  • Stage 1 (Dysfunction): Minor discomfort and stiffness.

  • Stage 2 (Dehydration): Discs lose moisture and shock absorption.

  • Stage 3 (Stabilization): Development of osteophytes (bone spurs) and spinal stenosis.

  • Stage 4 (Collapsing): Vertebrae collapse, loss of height, severe pain.

• Disc Herniation: Nucleus pulposus (NP) herniates through the annulus fibrosus (AF).

• Babinski Reflex: Positive sign (big toe extension/fanning) in adults indicates a CNS disorder (stroke, MS, ALS, tumor).

• Cauda Equina Syndrome:

  • Definition: Compression of nerve roots at the caudal end of the spinal cord ($L1\text{--}L5$).

  • Surgical Emergency: Requires immediate Lumbar Laminectomy to prevent permanent paralysis or incontinence.

Case Study Observations

• Case 1: $53\text{-year-old}$ female with low back pain radiating to both legs, $20\,lb$ weight loss in $6\,months$, and recent urinary leakage/incontinence.

• Diagnosis Consideration: The presence of weight loss and incontinence suggests possible cancer metastasis or Cauda Equina Syndrome.

• Case 2 (C3-4 Herniation): $43\text{-year-old}$ male with awkward gait and bilateral Babinski responses, indicating serious spinal cord compression.

• Breast Cancer Metastasis Case: $76\text{-year-old}$ woman with buttock pain initially suspected as schwannoma; CT revealed occult breast cancer with metastasis to the cauda equina.

Study Questions

• What does the normal spinal curvature look like?

• What is cervical kyphosis? Discuss causes, symptoms, and treatment.

• List the 3 major kinds of spinal deformities (Kyphosis, Lordosis, Scoliosis) and identify clinical features of each.

• What are clinical implications of age-related postural hyperkyphosis?

• Describe the main differences between acute vs chronic inflammation.

• What are the 5 cardinal signs of acute inflammation?

• Understand the mechanism of injury, signs, symptoms, diagnosis, and treatment for upper and lower extremity conditions.

• Identify red flag Review of Systems (ROS) when working up neck and back pain.

• What is the straight leg raise test, and what does it test for?

• Discuss pathophysiology, symptoms, and diagnosis for sciatica, DDD, Disc Herniation, and Cauda Equina Syndrome.