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IFT vs TENS — Choosing in Physiotherapy

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1. Basic Principles

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2. Mechanism of Analgesia

• Gate control theory — high-frequency TENS (>80 Hz) activates large-diameter Aβ fibres, inhibiting nociceptive transmission in the dorsal horn via interneurons in the substantia gelatinosa
• Endorphin release — low-frequency TENS (<10 Hz) stimulates Aδ fibres and promotes endogenous opioid (enkephalin/β-endorphin) release
• Possible direct local vasodilation reducing ischaemic pain

• The same gate control and endorphin mechanisms, but the interference beat frequency is generated within deep tissue, so it reaches structures that TENS cannot penetrate effectively
• Less skin irritation because the carrier frequency (4000 Hz) has low impedance through skin; the therapeutic low-frequency effect is produced internally
• Additionally has a muscle pumping effect at certain frequencies (~10–50 Hz), promoting blood flow and oedema reduction

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3. Parameter Comparison

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4. Indications — When to Choose Which

Choose TENS when:

• Superficial/localised pain — skin wounds, superficial soft tissue injuries, post-herpetic neuralgia
• Chronic musculoskeletal pain — back pain, osteoarthritis (mild), myalgia
• Neuropathic pain — phantom limb, peripheral neuropathy
• Postoperative pain — early mobilisation, incision site pain
• Obstetric pain (after first trimester) — especially low back pain in labour
• Home use — TENS is portable, inexpensive, self-administered; ideal for ongoing chronic pain management
• Neuralgias — herpes zoster, trigeminal neuralgia (electrode placement around but not over the area)

Choose IFT when:

• Deep tissue pain — hip joint, knee joint, shoulder joint pathology; deep muscle spasm
• Acute oedema & post-traumatic swelling — IFT's muscle pumping at 10–50 Hz helps lymphatic drainage
• Periarticular conditions — bursitis, capsulitis, periarthritis
• Deep nerve pain — sciatic nerve involvement, deep lumbar pain
• Muscle re-education / stimulation of deep muscles where surface TENS cannot reach
• Circulatory insufficiency — IFT promotes vasodilation of deep vessels
• Chronic pelvic pain, stress urinary incontinence — IFT reaches pelvic floor muscles effectively

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5. Contraindications

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6. Practical Decision Guide

Is the target tissue deep (joint, deep muscle, sciatic nerve)?
    YES → IFT preferred
    NO (superficial / skin / subcutaneous)?
        → TENS preferred

Is oedema / swelling the primary concern?
    YES → IFT (muscle pump frequency 10–50 Hz)

Is the patient managing pain at home long-term?
    YES → TENS (portable, affordable, self-use)

Is it a neuropathic / post-herpetic pain?
    YES → TENS (especially high-frequency conventional)

Is it acute joint pain / peri-articular inflammation?
    YES → IFT

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7. Quick Summary

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Nocturnal Leg Cramps (Charley Horse)

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What Actually Happens (Mechanism)

"Any local irritating factor or metabolic abnormality of a muscle — such as severe cold, lack of blood flow, or overexercise — can elicit pain or other sensory signals transmitted from the muscle to the spinal cord, which in turn cause reflex feedback muscle contraction. The contraction stimulates the same sensory receptors even more, which causes the spinal cord to increase the intensity of contraction. Thus, positive feedback develops, so a small amount of initial irritation causes more and more contraction until a full-blown muscle cramp ensues." — Guyton and Hall Textbook of Medical Physiology

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Common Causes & Triggers

Physiological (Most Common)

Medical Conditions to Rule Out

Drug-Induced Cramps

• Diuretics (furosemide, thiazides) — potassium/magnesium loss
• Statins — myopathy-related
• Beta-agonists (salbutamol)
• Raloxifene, clonazepam, lithium
• Alcohol (chronic use)

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Red Flags — When to Seek Medical Evaluation

• Unilateral calf cramp that persists and worsens over days → suspect DVT
• Associated with leg swelling, redness, or warmth
• Occurring with leg pain on walking (cramping that relieves with rest) → suspect peripheral arterial disease / claudication
• In a pregnant woman — may indicate electrolyte emergency
• Accompanied by muscle weakness, wasting, or fasciculations → possible neurological cause (ALS, radiculopathy)
• Not responding to any conservative measures

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Immediate Relief (During a Cramp)

1. Stretch the muscle — straighten the knee and dorsiflex the foot (pull toes toward the shin). This breaks the positive feedback loop by activating the Golgi tendon organ, triggering autogenic inhibition.
2. Stand up and bear weight on the affected leg — immediate reflex inhibition of the cramp.
3. Massage the muscle belly firmly in the direction of the fibres.
4. Apply warmth (warm towel/heat pack) — reduces muscle spindle sensitivity.
5. For hamstring cramps: lie flat, extend the knee, and flex the hip with the leg straight.

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Prevention & Long-Term Management

Lifestyle & Physical

Nutritional Supplementation

Pharmacological (Doctor-prescribed)

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Physiotherapy Role

• Stretching programme — daily calf, hamstring, and plantar fascia stretching
• IFT or TENS — for muscle pain relief post-cramp
• Hydrotherapy — warm water exercise reduces muscle excitability
• Gait and posture assessment — flat feet (pes planus) or leg length discrepancy can overload the calf/hamstring chronically
• Dry needling to trigger points in gastrocnemius/soleus if chronic tightness is a contributing factor
• Manual therapy to lumbar spine if L4/L5/S1 radiculopathy is suspected as the underlying driver

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Summary Table

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Unilateral Pain After Haemorrhagic Stroke — Clinical Analysis

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1. Primary Diagnosis: Central Post-Stroke Pain (CPSP)

What It Is

"Lesions at any level of the neuroaxis (generally affecting spinothalamocortical afferent sensory pathways) including the medulla, pons, midbrain, thalamus, subcortical white matter, and the cortex may produce central poststroke pain syndrome. The thalamus and brainstem are common sites; 8–16% of thalamic strokes may lead to chronic pain." — Bradley and Daroff's Neurology in Clinical Practice

"The severe, persistent, unrelenting unilateral pain often is described in dramatic terms... With partial recovery of sensation or with an acute but incomplete lesion, spontaneous pain or discomfort (Dejerine-Roussy syndrome), sometimes of the most distressing type, may appear on the affected side." — Adams and Victor's Principles of Neurology, 12th Ed.

Why It Fits This Patient

Characteristics of CPSP

• Burning, aching, shooting, or squeezing pain — constant or paroxysmal
• Allodynia — normally non-painful stimuli (light touch, clothing) cause pain
• Hyperalgesia — exaggerated pain response to stimuli
• Hyperpathia — delayed, explosive pain after stimulation
• Thermal allodynia — cold especially triggers or worsens pain
• Emotional disturbance, noise, or even music can aggravate it

"Thermal — especially cold — stimuli, emotional disturbance, loud sounds, and even certain types of music may aggravate the painful state." — Adams and Victor's Principles of Neurology

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2. Compounding Causes (RA + Gout on Affected Side)

Rheumatoid Arthritis (RA)

• RA causes synovial inflammation, joint destruction, and peripheral sensitisation
• On the stroke-affected side, reduced activity and immobilisation worsens RA joint involvement (disuse synovitis, contractures)
• The patient may have shoulder, hand, or knee joint pain from RA that blends with CPSP
• RA flares in immobilised joints → adhesive capsulitis (frozen shoulder) is very common post-stroke

Gout

• Gout attacks (acute crystal arthropathy) cause exquisite joint pain — most commonly in foot, ankle, knee
• On the affected side, reduced mobility → poor urate clearance from joints → more frequent gout attacks
• Gout pain is episodic, sudden, nocturnal, severe — may be misinterpreted as worsening CPSP
• Dehydration (common in stroke patients) and diuretic use raise serum urate

Hemiplegic Shoulder Pain (Separate Entity)

"Some 40–60% of patients develop shoulder pain after a stroke. It is postulated that the pain is due to inflammation in the joint secondary to immobilisation and joint contracture (frozen shoulder syndrome)." — Bradley and Daroff's Neurology in Clinical Practice

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3. Full Differential Diagnosis

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4. Assessment Approach

History

• Character of pain: burning/shooting/aching? Constant or paroxysmal?
• Does light touch or cold worsen it? (→ CPSP allodynia)
• Is pain episodic and joint-specific? (→ Gout)
• Morning stiffness >30 min, symmetric joints? (→ RA)
• Shoulder pain with overhead movement? (→ Hemiplegic shoulder)

Examination

• Sensory testing: pinprick, light touch, temperature, vibration on affected vs. unaffected side
• Check for allodynia (cotton wool → pain on affected side = CPSP)
• Joint examination: swelling, tenderness, range of motion
• Shoulder: assess for subluxation (fingerbreadth gap below acromion)
• Look for tophaceous deposits (gout)

Investigations

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5. Management

A. Central Post-Stroke Pain (CPSP)

"Dysesthesias, when severe and persistent, may respond to anticonvulsants (carbamazepine 100–1000 mg/d; gabapentin 300–3600 mg/d; or pregabalin 50–300 mg/d), antidepressants (amitriptyline 25–150 mg/d; nortriptyline 25–150 mg/d; desipramine 100–300 mg/d; or venlafaxine 75–225 mg/d)." — Harrison's Principles of Internal Medicine, 22nd Ed.

• Motor cortex stimulation (MCS) — neurosurgical; evidence for refractory CPSP
• Deep brain stimulation (DBS)
• Ketamine infusion — short-term pain relief
• TENS / IFT — adjunct; modest benefit for peripheral component

B. Hemiplegic Shoulder Pain

• Proper positioning and arm support (sling when mobilising)
• Range-of-motion physiotherapy — passive then active-assisted
• Suprascapular nerve block — for refractory shoulder pain
• Intra-articular corticosteroid — if adhesive capsulitis
• Avoid aggressive passive stretch (can worsen subluxation)

C. Gout (on Affected Side)

• Colchicine (0.5 mg BD) or NSAIDs for acute attacks (caution: renal function post-stroke)
• Allopurinol for prophylaxis (start once acute attack settles; target uric acid <360 µmol/L)
• Adequate hydration
• Dietary: reduce purines (red meat, organ meat, alcohol — especially beer)
• Note: NSAIDs should be used cautiously in post-stroke patients (cardiovascular and renal risk)

D. RA Management

• Continue/optimise DMARDs (methotrexate, hydroxychloroquine, leflunomide)
• Physiotherapy — joint protection, splinting, range of motion
• Short-course corticosteroids for acute flares on affected side
• Avoid long-term NSAIDs post-haemorrhagic stroke

E. Physiotherapy (Overall)

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Summary

Post-haemorrhagic stroke unilateral pain at 9 months
+ Good motor power
+ Allodynia / burning quality
→ PRIMARY = Central Post-Stroke Pain (CPSP / Dejerine-Roussy)

Co-existing RA → adds joint inflammation and immobility pain
Co-existing Gout → adds episodic crystal arthropathy attacks
Immobility → adds hemiplegic shoulder pain (40–60% of stroke patients)

Management is MULTIMODAL:
  Amitriptyline or Gabapentin/Pregabalin (CPSP)
  + Physiotherapy (desensitisation, ROM, positioning)
  + Optimised RA DMARD therapy
  + Allopurinol + Colchicine (Gout)
  + Shoulder protection and nerve block if needed

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Haemorrhoids & the Role of Physiotherapy

1. What Are Haemorrhoids?

"Hemorrhoids are normal vascular structures in the submucosal layer of the anal canal, arising from a channel of arteriovenous connective tissues that drains into the superior and inferior hemorrhoidal veins." — Roberts and Hedges' Clinical Procedures in Emergency Medicine

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2. Classification

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3. Symptoms

• Bright red rectal bleeding (on tissue or in bowl — not mixed with stool)
• Prolapse felt as a lump at the anus
• Perianal itching / discomfort (mucus discharge)
• Aching or heaviness after defecation
• Acute severe pain — thrombosed external haemorrhoid
• Anaemia in chronic bleeders

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4. Causes & Contributing Factors

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5. Medical & Surgical Management (Context for Physiotherapy)

Conservative (First-line)

• High-fibre diet (25–35 g/day) + increased water (8–10 glasses/day) — most important intervention
• Bulk-forming laxatives (psyllium/ispaghula husk)
• Sitz baths — warm water soaks 15–20 min, 2–3×/day; reduces spasm, oedema, pain
• Topical agents — corticosteroid/anaesthetic creams (short term only)
• Stool softeners (docusate sodium)

Office Procedures

• Rubber band ligation — best evidence for Grade II–III internal haemorrhoids
• Infrared photocoagulation (IRC)
• Sclerotherapy

Surgical

• Haemorrhoidectomy — Grade III–IV, mixed, failed office procedures
• Stapled haemorrhoidopexy

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6. Role of Physiotherapy

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A. Pelvic Floor Rehabilitation

Pelvic Floor Strengthening (Kegel Exercises)

• Strengthens the levator ani, pubococcygeus, and external anal sphincter
• Improves venous return from the anorectal vasculature
• Reduces passive engorgement of haemorrhoidal cushions
• Reduces faecal incontinence associated with prolapsed haemorrhoids
• Technique: Contract pelvic floor as if stopping urine midstream → hold 5–10 seconds → relax fully → repeat 10–15 times, 3 sets/day

Pelvic Floor Relaxation / Downtraining

• Many patients with haemorrhoids have a paradoxically contracting or hypertonic pelvic floor — they strain against a tight sphincter, massively increasing rectal pressure
• Biofeedback-assisted relaxation teaches the patient to relax the puborectalis and external anal sphincter during defecation
• Evidence supports biofeedback for dyssynergic defecation (outlet obstruction constipation) — a major cause of haemorrhoid worsening

Biofeedback Therapy

• Surface EMG or manometry probes provide real-time feedback of sphincter and pelvic floor activity
• Teaches proper coordination — relax floor while bearing down gently
• Reduces straining force and time spent on the toilet
• Also used post-haemorrhoidectomy to restore continence

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B. Posture and Defecation Mechanics

• Physiotherapists educate on optimal defecation posture
• The squatting position (knees higher than hips — use a footstool/squatty potty) straightens the anorectal angle, reduces straining effort by ~30%, and reduces time to defecation
• Correcting breath-holding and Valsalva straining — teach diaphragmatic breathing with gentle exhale during defecation instead of breath-holding

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C. Electrotherapy Modalities

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D. Manual Therapy / Soft Tissue Techniques

• Myofascial release of hypertonic pelvic floor muscles (internal and external techniques)
• Trigger point therapy to levator ani, obturator internus, piriformis — reduces referred perineal pain
• Scar tissue mobilisation post-haemorrhoidectomy — prevents fibrotic stricture and painful scarring
• Perineal massage — improves tissue extensibility and reduces postoperative discomfort

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E. Post-Haemorrhoidectomy Rehabilitation

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F. Lifestyle and Exercise Prescription

• Aerobic exercise (walking, swimming, cycling) improves bowel motility, reduces constipation, and promotes venous return from the lower body
• Avoid prolonged sitting — advise regular standing/walking breaks
• Core strengthening — reduces intra-abdominal pressure fluctuations during daily activities
• Avoid heavy straining exercise (heavy deadlifts, intense Valsalva exercises) during acute flares
• Weight management — obesity directly increases haemorrhoidal pressure

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G. Patient Education (Key Physiotherapy Role)

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7. Summary Table

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Disc Bulge, Prolapse, Protrusion & the McKenzie / Extension Exercise Approach

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Part 1: Disc Pathology — Classification & Terminology

Anatomy of the Intervertebral Disc

• Nucleus pulposus — central gel-like core, high water content, absorbs axial load
• Annulus fibrosus — concentric collagen rings encasing the nucleus; resists radial and tensile forces
• Cartilaginous end plates — anchor the disc to vertebral bodies

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Disc Pathology Classification (Combined Task Forces / Radiological Standard)

"A 'disc protrusion' is used when the base of the disc is broader than any other diameter of the displaced disc material. It is called an 'extruded disc' when the base against the disc is smaller than the diameter of the displaced disc material." — Grainger & Allison's Diagnostic Radiology

"An extrusion is seldom seen in asymptomatic patients... Disc material exposed to the epidural space appears to resolve more quickly than subligamentous disc herniations." — Grainger & Allison's Diagnostic Radiology

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Location Classification (Axial/Transverse Plane)

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Common Levels & Nerve Root Signs

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Natural History

"Disc herniation occurs when the annulus fibrosis thins and tears, and the nucleus pulposus prolapses, usually laterally, compressing and inflaming a nerve root. Clinical symptoms are typically self-limited, with a high rate of spontaneous improvement... The size of the disc protrusion may naturally decrease over time." — Rosen's Emergency Medicine

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Part 2: McKenzie Method (MDT — Mechanical Diagnosis and Therapy)

Who Developed It?

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Three McKenzie Syndromes

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The Centralisation Phenomenon — Core Concept

The most important clinical sign in McKenzie assessment.

• Centralisation = good prognostic sign → continue that movement direction
• Peripheralisation = bad sign → stop that direction, try the opposite
• Centralisation predicts success of conservative management

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McKenzie Assessment Process

1. Repeated movement testing — perform 10 repetitions in each direction (flexion, extension, lateral glide, combined) in standing and lying
2. Observe effect on symptoms — centralisation, peripheralisation, no change
3. Identify directional preference — the movement that centralises/abolishes pain
4. Classify syndrome — Derangement, Dysfunction, or Postural
5. Prescribe direction-specific exercises

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Part 3: Extension Exercises — The McKenzie Lumbar Programme

Extension Exercise Progression (Lumbar)

Stage 1 — Lying Prone (Passive Position)

• Lie face down, arms by sides, rest for 3–5 min
• Allows lumbar spine to naturally extend
• Used for acute, very painful patients

Stage 2 — Prone on Elbows

• Prop up on forearms (sphinx position)
• Partial extension loading
• Hold 2–3 min; repeat several times

Stage 3 — Prone Press-Up (Most Important)

• Lie prone; place hands under shoulders
• Push upper body up keeping hips/pelvis on the floor
• Elbows straighten fully → maximises lumbar extension
• 10–15 repetitions, multiple times/day
• Key: maintain passive lower body; do not activate glutes

Stage 4 — Standing Extension

• Stand with feet apart, hands on lower back
• Arch backward as far as possible, hold 2–3 seconds
• Useful when going from sitting to standing (office breaks)
• Repeat 10×, used as a prophylactic break

Stage 5 — Side Glide (Lateral Shift Correction)

• If patient has visible lateral shift (lean to one side)
• Stand sideways to wall; hip against wall
• Push hips toward wall while shoulders go away
• Corrects lateral shift before extension becomes effective
• Must be corrected first or extension will peripheralise

Stage 6 — Therapist-Assisted Techniques

• Passive extension mobilisations in prone
• Posterior-anterior (PA) pressures over spinous processes
• Combined with patient's own press-up movement
• Maitland grades I–IV can be layered onto McKenzie postures

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When to Use Flexion Instead (McKenzie)

• Single or double knee-to-chest in supine
• Sitting forward bend
• Flexion in standing
• Used when extension peripheralises symptoms

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Dosage & Frequency

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Part 4: Full Physiotherapy Programme for Disc Patients

Adjunct Physiotherapy Modalities

Red Flags — Immediate Surgical Referral

• Cauda equina syndrome — bilateral leg pain, bladder/bowel dysfunction, saddle anaesthesia → surgical emergency
• Progressive neurological deficit (worsening foot drop)
• Severe pain not relieved at all with any position
• Cancer, infection, fracture suspected

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Summary

DISC PATHOLOGY SPECTRUM:
Bulge → Protrusion → Extrusion/Prolapse → Sequestration
(contained)                              (free fragment)
Increasing severity ↑ | Better spontaneous resorption of extruded material ↑

McKENZIE PRINCIPLE:
Most posterior disc herniations → Extension is the directional preference
Extension loading shifts nucleus anteriorly → centralises pain → decompresses root
Test first: if extension centralises symptoms → continue extension programme
If extension peripheralises → check for lateral shift first, or try flexion

KEY EXERCISES:
Prone lying → Prone on elbows → Prone press-up (10× every 2 hrs)
→ Standing extension → Lateral shift correction → Stabilisation

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Post-Op Knee: Half Squat, Full Squat, Lunges & Hops — Biomechanics, Muscle Work, Form & Safety

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Key Anatomical Context — Forces Acting on the Post-Op Knee

• Post ACL reconstruction: avoid deep knee flexion early; more risk in 0–30° open chain extension (OKC) than in closed chain
• Post TKR (total knee replacement): patellofemoral stress is the limiting factor; avoid >90° loading early
• Post patellofemoral surgery / chondroplasty: minimise PFJRF — avoid full squats, stairs, lunges early
• Post PCL reconstruction: avoid deep flexion >70° early (PCL under maximum tension)
• Post meniscectomy / meniscal repair: deep squat increases compressive and shear stress on meniscal remnant — progress cautiously

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1. HALF SQUAT (0–60° Knee Flexion)

Biomechanics

• A closed kinetic chain (CKC) exercise — foot fixed to ground, force transmitted through the entire chain
• At 0–60°: moderate quadriceps demand, low PFJRF, low ACL stress (compared to open chain extension in same range)
• Tibiofemoral compression moderate; meniscal load manageable
• Hip extensors (gluteus maximus) share significant load — co-contraction of hamstrings stabilises the knee
• Centre of mass stays over base of support

Primary Muscles Working

Proper Form ✅

• Feet shoulder-width apart, toes slightly out (10–15°)
• Descend slowly and controlled (3 seconds down, 2 up)
• Knees track over 2nd–3rd toe — do not cave inward (valgus)
• Weight evenly distributed across entire foot — not on toes
• Trunk slight forward lean (normal hip hinge) — but spine neutral, no rounding
• Lower to 60° only — hip crease does NOT pass below knees in a half squat
• Eyes forward, chin neutral

Form Errors to Avoid ❌

• Knee valgus (knees diving inward) — overloads medial compartment and patellofemoral joint
• Heels lifting — ankle stiffness shifts load anteriorly; fix with heel wedge or ankle mobility work
• Forward trunk collapse — overloads lumbar spine, reduces quadriceps engagement
• Rapid uncontrolled descent — eccentric control is critical for joint protection
• Knee shooting past toes excessively — increases patellofemoral stress (some forward travel is normal)
• Holding breath / Valsalva — raises intra-abdominal pressure; exhale on ascent

Post-Op Application

• ✅ First closed-chain exercise introduced in most protocols (TKR, ACL, meniscal, patellofemoral)
• Typically introduced at 2–6 weeks depending on surgery
• Start with wall squat (wall behind back for guidance) or chair squat (sit-to-stand)
• Add resistance band above knees for VMO activation cue
• Progress: bodyweight → resistance band → goblet squat with load

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2. FULL SQUAT (>90° to Full Flexion)

Biomechanics

• At >90° flexion: PFJRF rises steeply to 6–8× body weight
• Tibiofemoral compressive forces at maximum — greatest load on menisci and articular cartilage
• PCL under high tension (posterior drawer force on tibia)
• Hamstrings near full shortening — reduce active co-contraction capacity
• Calf-thigh contact at full flexion creates a "wrap-around" compressive force on posterior capsule
• Ankle dorsiflexion requirement: >35° — limited mobility → heel rise → increased anterior shear

Primary Muscles Working

Proper Form ✅

• Wide stance (slightly wider than shoulder width) aids depth without heel rise
• Deep squat requires full ankle dorsiflexion — address mobility first
• Maintain lumbar lordosis throughout — do NOT allow posterior pelvic tilt ("butt wink") at depth
• Knees remain over toes throughout
• Chest up, thoracic extension maintained
• Controlled tempo throughout — no bouncing at the bottom

Form Errors to Avoid ❌

• "Butt wink" (posterior pelvic tilt) at the bottom — collapses lumbar spine; increases disc and SI joint stress
• Heel rise — forced by ankle restriction; shifts knees forward, increases PFJRF dramatically
• Knee hyperextension on ascent — locks out joint, impaction injury to posterior structures
• Medial knee collapse throughout the movement
• Rapid "bounce" at the bottom — extreme compressive spike on menisci and cartilage

Post-Op Application

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3. LUNGES

Biomechanics

• A unilateral, single-leg-dominant CKC exercise
• Greater demand on hip extensors and frontal plane stability compared to squats
• Introduces lateral and rotational forces on the knee — tests dynamic stabilisers
• Front knee: quadriceps-dominant, 70–90° flexion → moderate-high PFJRF
• Rear knee: hip flexor stretch (iliopsoas, rectus femoris) + minor weight bearing
• Step length determines force distribution: short step → more knee-dominant (quad); long step → more hip-dominant (glute)
• Trunk position modulates load: upright = more quad; lean forward = more hip/glute

Primary Muscles Working

Lunge Variations & Post-Op Relevance

Proper Form ✅

• Step forward so front shin remains roughly vertical (knee behind or at toes)
• Front knee tracks over 2nd–3rd toe
• 90° at front knee AND rear knee at bottom
• Trunk erect and vertical — avoid leaning over front knee
• Lower rear knee to ~2 cm above floor, then drive back up
• Push through front heel, not toes, to ascend
• Hips level throughout — no hip hike or drop

Form Errors to Avoid ❌

• Front knee diving past toes excessively → increases PFJRF
• Knee valgus (medial cave) — most common and most dangerous post-op
• Trunk lean forward — reduces quad engagement, increases knee stress
• Hip drop/Trendelenburg — gluteus medius weakness; increases ITB and lateral knee stress
• Pushing from rear leg rather than front — doesn't achieve intended strengthening
• Inadequate step length — makes it a knee-dominant mini-squat instead

Post-Op Application

• Start with split squat (static) — both feet stay fixed
• Progress to reverse lunge before forward lunge
• Add side step-up as an alternative if lunge loading is too great
• Walking lunge introduced at 3–4 months (ACL), 4–6 months (meniscal repair)

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4. HOPS — Biomechanics & Return-to-Sport Role

• Rapid force generation (concentric)
• Shock absorption (eccentric deceleration)
• Dynamic joint stability under impact
• Neuromuscular control and reactive stiffness

Types of Hop Tests / Exercises

Biomechanics of Hopping

• Take-off phase: Rapid concentric triple extension (hip, knee, ankle) — demands full strength of quadriceps, hamstrings, glutes, and calf
• Flight phase: Prepares for landing — pre-activation of stabilisers
• Landing phase (MOST CRITICAL post-op): Eccentric deceleration; GRF 3–5× body weight in <200ms; dynamic valgus at landing = most common ACL re-injury mechanism

Proper Landing Mechanics ✅ (Soft Landing Technique)

• Land with soft knees — do not land stiff-legged
• Simultaneous triple flexion at ankle, knee, and hip on contact
• Knee aligned over 2nd toe — no dynamic valgus
• Quiet landing — loud landing = poor eccentric control
• Hold landing for 3 seconds without hopping or staggering
• Trunk slightly forward over landing foot

Form Errors to Avoid ❌

• Stiff-legged landing — massive impact force through articular cartilage
• Knee valgus at landing — primary mechanism of ACL re-rupture
• Asymmetric landing (favouring the non-operated leg) — detected by Limb Symmetry Index (LSI)
• Trunk rotation or lateral lean on landing
• Looking down — impairs balance and dynamic alignment

Limb Symmetry Index (LSI) — Return-to-Sport Criterion

LSI = (Operated limb performance ÷ Non-operated limb) × 100

• LSI ≥90% across all four hop tests is the standard return-to-sport threshold (ACL)
• LSI <90% = not cleared for unrestricted sport return

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5. When to AVOID or STOP — Red Flags & Clinical Criteria

Stop the Exercise Immediately If:

Contraindications by Surgery Stage

The "2-Hour Pain Rule" (Clinical Standard)

• If pain after exercise persists >2 hours or is worse next morning than before: load was too high
• Regress the exercise, reduce repetitions/sets, or reduce depth
• This rule applies to post-op knee rehabilitation universally

Effusion Grading — Exercise Modification Guide

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6. Progressive Post-Op Knee Exercise Roadmap

WEEK 0–2:    Isometrics (quad sets, SLR, VMO activation)
             Heel slides, ankle pumps, CPM

WEEK 2–6:    Mini squat (0–45°), wall slides
             Terminal knee extension (TKE) with band
             Step-up (low step, 5–10 cm)
             Stationary bike (low resistance)

WEEK 6–12:   Half squat (0–60°), sit-to-stand
             Split squat / static lunge
             Reverse lunge
             Step-up (higher step, 15–20 cm)
             Swimming, deep water running

MONTH 3–4:   Half squat with load
             Forward lunge
             Lateral lunge
             Leg press (full range, controlled)
             Introduce jogging on flat

MONTH 4–6:   Full squat (if ROM allows and cleared)
             Walking lunge
             Single-leg squat
             Box step-down (eccentric control)
             Begin hop training: bilateral → single-leg

MONTH 6+:    Hop tests (LSI assessment)
             Plyometrics, agility drills
             Sport-specific return criteria
             (LSI ≥90%, psychological readiness, strength ≥90%)

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Summary Table

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Rabies & Post-Exposure Prophylaxis (PEP)

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1. The Virus

"Rabies virus is a lyssavirus that infects a broad range of mammals and causes serious neurologic disease when transmitted to humans." — Harrison's Principles of Internal Medicine, 22nd Ed.

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2. Epidemiology

• ~59,000 human deaths annually worldwide; >99% occur in Asia and Africa from dog bites
• More than 15 million people receive PEP annually (WHO)
• In the USA: endemic canine rabies eliminated; wildlife (bats, raccoons, skunks, foxes) are the primary reservoir; bats are the most common source of indigenously acquired human rabies
• Rabies-free zones: Hawaii, UK, Australia/New Zealand, Antarctica, Japan, most Pacific islands

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3. Pathophysiology — How Rabies Kills

"After a bite, saliva containing infectious rabies virus is deposited in muscle and subcutaneous tissues. The virus remains close to the site of exposure for the majority of the long incubation period (typically 20–90 days). Rabies virus binds to the nicotinic acetylcholine receptor in muscle... Subsequently, the virus spreads across the motor end plate and ascends and replicates along the peripheral nervous axoplasm to the dorsal root ganglia, the spinal cord, and the CNS." — Tintinalli's Emergency Medicine

1. Inoculation → virus in muscle/subcutaneous tissue at bite site
2. Binding → nicotinic acetylcholine receptor at neuromuscular junction
3. Retrograde axonal transport → ascent along peripheral nerves → spinal cord → brain
4. CNS replication → limbic system, brainstem, cerebellum
5. Centrifugal spread → outward to salivary glands, skin, cornea, heart, adrenals

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4. Clinical Stages

Recovery is rare. — Harrison's Principles of Internal Medicine, 22nd Ed.

Hydrophobia — The Hallmark

• Attempts to swallow water trigger violent spasms of the throat and inspiratory muscles
• Caused by viral involvement of the brainstem (nucleus ambiguus, respiratory centres)
• Also aerophobia (spasms triggered by a puff of air on face)
• Hypersalivation + inability to swallow = classic "foaming at the mouth"

Incubation Determinants

• Short (days–weeks): bites to head, face, neck; deep wounds; multiple bites; high viral inoculum
• Long (months–years): bites to distal extremities; minor wounds; low viral inoculum

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5. WHO Exposure Classification

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6. Post-Exposure Prophylaxis (PEP) — Step by Step

STEP 1: Immediate Wound Washing (Most Critical First Step)

"Elimination of rabies virus at the site of the infection by chemical or physical means is an effective mechanism of protection." — WHO

• Wash vigorously with soap and water for at least 15 minutes
• Then apply: povidone-iodine (10%), 70% ethyl alcohol, or aqueous iodine solution
• This single measure can markedly reduce the viral load and significantly decrease the risk of infection
• Do NOT suture the wound immediately — allows virus escape; if suturing needed, do so after local RIG infiltration

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STEP 2: Rabies Immunoglobulin (RIG) — Passive Immunisation

• Give on Day 0 (same day as first vaccine dose) — provides immediate passive protection while vaccine-induced immunity develops (takes 7–14 days)
• Do NOT give in the same syringe or site as the vaccine
• Do NOT give more than the calculated dose — excess RIG suppresses the active vaccine immune response
• If Day 0 has passed but vaccine series has begun, RIG can still be given up to Day 7 if not yet administered
• Not needed if previously vaccinated (immune memory provides rapid anamnestic response)

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STEP 3: Rabies Vaccine — Active Immunisation

Modern Cell-Culture Vaccines (WHO-recommended — replacing nerve tissue vaccines)

WHO strongly recommends the discontinuation of production and use of nerve tissue vaccines (Semple vaccine, suckling mouse brain vaccine) and their replacement by modern cell culture vaccines. — WHO

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PEP Vaccine Schedules

A. Never Previously Vaccinated (Standard)

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B. Previously Vaccinated (Booster / Re-exposure)

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STEP 4: Is PEP Still Effective If Delayed?

• PEP should be started as soon as possible
• However, it can still be initiated even weeks after exposure — as long as the patient shows NO symptoms of rabies (once symptoms appear, no treatment is effective)
• The sooner started, the better; delay is never a reason to withhold PEP

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7. Risk Assessment — When Is PEP Needed?

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8. Pre-Exposure Prophylaxis (PrEP)

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9. Diagnosis (Clinical)

"A diagnosis of rabies often is not considered until relatively late in the clinical course... This diagnosis should be considered in patients presenting with acute atypical encephalitis or acute flaccid paralysis." — Harrison's Principles of Internal Medicine, 22nd Ed.

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10. Treatment of Clinical Rabies

• Supportive ICU care: sedation, analgesia, mechanical ventilation
• Milwaukee Protocol (experimental): induced coma + antiviral therapy — very rare survivors reported; not widely adopted
• Palliative care is the mainstay

"No specific treatment is available. Vaccination immediately after animal bites prevents rabies disease." — Sherris & Ryan's Medical Microbiology

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11. PEP Summary Card

ANIMAL BITE / EXPOSURE
        ↓
1. WASH WOUND — soap & water 15 min + povidone-iodine
        ↓
2. ASSESS EXPOSURE CATEGORY (WHO I / II / III)
        ↓
Category I → No PEP
Category II → Vaccine only (Days 0, 3, 7, 14)
Category III → RIG (20 IU/kg infiltrated into wound) 
               + Vaccine (Days 0, 3, 7, 14)
        ↓
3. ASSESS PREVIOUS VACCINATION STATUS
   Previously vaccinated → 2 vaccine doses only (Day 0 + 3), NO RIG
   Never vaccinated → Full PEP as above
        ↓
4. ASSESS ANIMAL
   Dog/cat/ferret — healthy → observe 10 days
   Wild animal / bat → treat as rabid until proven otherwise
   Rodents/rabbits → PEP rarely needed
        ↓
5. NEVER inject vaccine in GLUTEAL region
   NEVER give RIG in same syringe as vaccine
   NEVER withhold PEP because of delay — start even weeks later
        ↓
REMEMBER: Once symptoms appear → NO PEP is effective