🩺 Orthopedic Exam Guide (Part 3)

1. Metabolic Bone Disorders

Bone Composition & Remodeling
  • Bone Components:
    1. Mineral (mainly Calcium and Phosphorus).
    2. Matrix (collagen fibers).
    3. Osteoclasts (bone-removing cells).
    4. Osteoblasts (bone-producing cells).
  • Bone Remodeling Cycle:
    • Osteoclasts solubilize bone matrix (resorption).
    • Osteoblasts lay down new bone matrix (osteoid).
    • Osteoblasts become Osteocytes once bone formation is complete.
    • Mineralization with hydroxyapatite takes several months.
  • Categories of Metabolic Bone Disease:
    • Osteoporosis: Quantity of bone (bone mass) is abnormally low.
    • Osteomalacia: Insufficiently mineralized osteoid.
    • Osteitis fibrosa: PTH over-production causing bone replacement by fibrous tissue.
Osteoporosis
  • Definition: Bone is qualitatively normal but quantitatively deficient. Cortex is thinner, trabeculae are sparse. "Silent thief".
  • Primary Osteoporosis:
    • Postmenopausal: Due to estrogen withdrawal. Common in women 55-65 yrs. Presents with vertebral compression (wedge fractures) and distal radius (Colles') fractures.
    • Involutional: Over 70 yrs. Decreased rate of bone formation. Associated with femoral neck or proximal humerus fractures.
    • Risk Factors: Family history, Hysterectomy, Smoking, Diet, Race (White/Asiatic more prone than Negroid).
  • Secondary Osteoporosis: Due to nutritional (Scurvy, Malabsorption), Endocrine (Cushing's, Thyrotoxicosis, Hyperparathyroidism), Malignant (Multiple Myeloma, Leukemia), or Drug-induced (Corticosteroids, Heparin) causes.
  • Diagnosis & Treatment:
    • Measurement of Bone Mineral Density (BMD) using DEXA Scan is the most accurate method. X-rays are late signs.
    • Treatment: Fix fractures early. Diet/Calcium/Vit D supplements. Medical therapy: Bisphosphonates (Alendronate) or Hormonal Replacement Therapy (HRT).
Rickets & Osteomalacia
  • Definition: Incomplete mineralization of bone. Rickets (children - defective growth). Osteomalacia (adults - bone softening).
  • Vitamin D Deficiency Rickets:
    • Clinical: Craniotabes (skull deformity), thickening of knees/wrists, Rickety rosary (costochondral enlargement), Harrison's sulcus, severe bowing of legs.
    • X-Ray: Thickening/widening of physis, distortion of metaphysis.
    • Lab: Decreased Ca & PO4, Increased Alkaline Phosphatase.
    • Treatment: Vitamin D (Calciferol 400-1000 IU/day).
  • Familial Hypophosphataemic Rickets: X-linked dominant. Impaired renal tubular reabsorption of phosphate. Normal Calcium, but reduced Phosphate. Needs large doses of Vit D + Inorganic phosphate.
  • Osteomalacia in Adults:
    • Vague bone pain, muscle weakness. Suspected after stress fractures.
    • X-Ray: Pathognomonic sign is the Looser zone (thin transverse band of rarefaction due to poorly healing stress fracture).
    • Lab: Increased Alkaline Phosphatase, reduced 25-HCC.
💡 Golden Hints

1. The "Silent Thief": Osteoporosis has no symptoms until a fracture occurs. Diagnosis relies on DEXA scan, as X-rays only show signs late.

2. Postmenopausal vs Involutional: Postmenopausal (55-65 yrs) mostly causes vertebral and Colles' fractures. Involutional (>70 yrs) causes femoral neck and proximal humerus fractures.

3. Pathognomonic Sign: The presence of a Looser zone (thin transverse band of rarefaction) on X-ray is highly specific for Osteomalacia.

2. Neuromuscular Disorders

Poliomyelitis
  • Pathology: Viral infection attacking the anterior horn cells of the spinal cord/brain stem, leading to Lower Motor Neuron (LMN) flaccid paralysis.
  • Clinical Phases:
    1. Acute: Fever, headache, sore throat. Complete rest + artificial breathing if respiratory paralysis.
    2. Paralysis: Unbalanced muscle weakness.
    3. Recovery: Prolonged up to 2 years.
    4. Residual: Permanent asymmetrical flaccid paralysis with intact sensation. Unbalanced pull leads to joint deformity and shortening.
  • Late Management:
    • Isolated weakness: Splint (caliper) or tendon transfer.
    • Fixed deformity: Corrective osteotomy.
    • Flail joint: Arthrodesis.
    • Shortening: Build up shoe (up to 3cm) or operative limb lengthening/shortening.
Cerebral Palsy (CP)
  • Definition: Non-progressive brain damage during early development (maternal ischemia, prematurity, kernicterus).
  • Classifications:
    • Spastic: Most common (>60%). Increased tone, hyperreflexia (UMN lesion).
    • Athetosis: Continuous involuntary writhing movement.
    • Ataxia: Incoordination, wide-based gait.
    • Rigid: Constant contraction, no yield on passive movement.
    • Mixed: Spasticity + Athetosis.
  • Clinical Picture: Delayed milestones (normally: head up at 3m, sit at 6m, walk at 1yr). Spastic Posture: Hip flexed & adducted, knee bent, equinus feet. Positive Babinski reflex. Normal skin sensation.
  • Management:
    • Physiotherapy: Early start, prevent contractures.
    • Splintage: Prevent fixed deformity.
    • Operation (4-8 yrs): Tight muscle release/lengthening (may weaken power), Tendon transfer, Osteotomy.
💡 Golden Hints

1. Motor Neuron Differences: Polio affects anterior horn cells leading to Lower Motor Neuron (Flaccid) paralysis. CP causes brain damage leading to Upper Motor Neuron (Spastic) paralysis.

2. CP Presentation: The most common type of Cerebral Palsy is Spastic (>60%). The classic spastic posture is: Hip flexed & adducted, knee bent, and equinus feet.

3. Sensation: In both Polio and Cerebral Palsy, despite the severe motor deficits, skin sensation remains completely normal.

3. Bone & Joint Infection (Osteomyelitis)

Pathogenesis & Classification
  • Definition: Inflammation of bone and marrow (Osteo = bone, Myelo = marrow).
  • Routes of Infection:
    • Direct: Open fractures, surgery, puncture.
    • Indirect (Hematogenous): Most common in children.
  • Pathogenesis: Organisms settle in the Metaphysis because of rich blood supply, slow circulation, end-arteries, and "hairpin" arrangement.
    • Pus increases intraosseous pressure -> Ischemic necrosis -> Sequestrum (dead bone).
    • Pus breaks through cortex to form a Subperiosteal Abscess, which may rupture causing a draining sinus.
  • Cierny-Mader Classification: Stage I: Medullary. Stage II: Superficial. Stage III: Localized. Stage IV: Diffuse.
  • Bacteriology: Staphylococcus aureus is the most common overall. (Infants: Group B Strep, E. coli. Children: S. aureus, H. influenzae).
Diagnosis & Treatment
  • Clinical: Sudden onset, high fever, restricted movement, calor (heat), rubor (redness), tumor (swelling), dolor (pain), functio laesa (loss of function).
  • Diagnostic Tests:
    • X-Ray: Seldom positive in first 2-4 weeks! Needs 30-50% bone mineral loss to show signs (lytic changes, sclerosis).
    • Bone Scan (Tc99): Positive within 2-3 days.
    • MRI: Early diagnosis, shows soft tissue/marrow changes.
    • Biopsy/Culture: Essential for targeted antibiotic therapy (Blood culture, needle/open biopsy).
  • Treatment (4S): 1. Supportive, 2. Splintage, 3. Systemic Antibiotics, 4. Surgical drainage.
    • Antibiotics: IV until clinical improvement (1-2w), then oral (3-6w).
    • Surgery: indicated for subperiosteal abscess or chronic stage (debridement, removing sequestrum).
  • Chronic Osteomyelitis: Active phase (fistulas, pain) vs Inactive phase. Treated with surgery to remove devitalized bone + local antibiotics (Gentamicin beads).
💡 Golden Hints

1. Diagnostic Trap: Plain X-rays are NOT diagnostic in acute osteomyelitis during the first 2-4 weeks. Bone scan (Tc99) or MRI should be used for early diagnosis.

2. Metaphysis Localization: Infection primarily settles in the metaphysis of children due to the unique hairpin arrangement of end-arteries and slow circulation.

3. Sequestrum: Represents a piece of dead, devascularized bone resulting from ischemic necrosis caused by increased intraosseous pressure from pus.

4. Tuberculosis of Bone & Joint

Pathology & Clinical Features
  • Overview: 10-15% of TB is extrapulmonary; 10% of that is skeletal. Almost 50% of skeletal TB affects the Spine, followed by hip and knee. Caused by Mycobacterium tuberculosis via hematogenous spread.
  • Pathology:
    • Vertebral TB: Begins in anterior vertebral body. Progressive destruction causes forward collapse leading to sharp angulation (Gibbus).
    • Joint TB: Starts in synovium/metaphysis -> chronic monoarticular arthritis -> articular erosion -> Fibrous ankylosis.
    • Caseating granuloma spreads to soft tissue causing a Cold Abscess, which may discharge through the skin as a chronic sinus.
  • Clinical Features: Low grade fever, night sweats, muscle wasting, chronic joint pain.
    Spinal TB complication: Pott's Paraplegia (weakness/paralysis of lower limbs due to cord compression).
Diagnosis & Treatment
  • X-Ray (Phemister Triad): Pathognomonic for joint TB:
    1. Periarticular osteopenia
    2. Decreased joint space
    3. Destruction of the corners of the joint
  • Investigation: Increased ESR/CRP, Mantoux test. Definitive diagnosis requires synovial biopsy / culture for AFB.
  • Treatment:
    • Anti-TB Chemotherapy: Rifampicin + INH (9 months) + Pyrazinamide/Ethambutol (first 2 months).
    • Surgical: Drainage of abscess, Partial Synovectomy, Arthrodesis for late/destructive joint damage.
    • Splintage in functional position.
💡 Golden Hints

1. Phemister Triad: The classic radiological finding in joint TB includes: Periarticular osteopenia, decreased joint space, and destruction of joint corners.

2. Spine Predilection: About 50% of skeletal TB cases involve the spine. Destruction of the anterior vertebral body leads to forward collapse and a sharp deformity called Gibbus.

3. Definitive Diagnosis: While Mantoux test and ESR are helpful, the definitive diagnosis of skeletal TB requires a synovial biopsy and culture for Acid Fast Bacilli (AFB).

5. Osteoarthritis (OA)

Pathoanatomy & Cell Biology
  • Definition: Degenerative joint disease with progressive softening and disintegration of articular cartilage.
  • Risk Factors: Age, Obesity, Increased mechanical load, Occupation, Female gender, Previous trauma/infection.
  • Classification: Primary (wear and tear, elderly) vs Secondary (due to trauma, infection, inflammatory).
  • Pathoanatomy (Structures Affected):
    • Cartilage: Erosion, fibrillation, splitting (Increased water, Decreased proteoglycan).
    • Bone: Cystic changes, sclerosis (hardening), osteophytes.
    • Synovial membrane: Hypertrophy, edema.
    • Capsule: Inflamed and contracted (Most common cause of pain).
  • Cell Biology: Increase in MMP (matrix metalloproteinase), Decrease in TIMP. Increase in inflammatory markers (TNF-alpha, IL-1, IL-6).
Clinical Features & Management
  • Clinical Features: Pain (Starts at weight bearing -> then at rest -> late stages at night), Stiffness, Swelling, Crepitus, Deformity (e.g., Varus angulation of knee).
  • Radiological Stages:
    • Stage 1: Bony spur only.
    • Stage 2: Narrowing of joint space < 50%.
    • Stage 3: Narrowing > 50% with osteophyte formation.
    • Stage 4: Complete obliteration of joint space, large osteophytes, subchondral sclerosis/cysts.
  • Treatment:
    • Non-operative: Weight loss, walking aids, Physiotherapy (Quadriceps strengthening), NSAIDs, intra-articular corticosteroids or hyaluronic acid.
    • Operative: Arthroscopy, Osteotomy (in young patients to correct alignment), Arthrodesis, Joint Arthroplasty (Joint Replacement - most commonly used for end-stage).
💡 Golden Hints

1. Source of Pain: Because cartilage has no nerve supply, the pain in OA primarily comes from the inflamed and contracted capsule and subchondral bone.

2. Cartilage Composition Changes: In OA, the cartilage shows decreased proteoglycans and increased water content, reducing its elasticity and shock absorption.

3. End-Stage Treatment: For Stage 4 OA (complete obliteration of joint space), the most commonly used and effective operative treatment is Joint Arthroplasty (Replacement).

6. Bone Tumors

Classification & General Evaluation
  • Classification by Origin:
    • Bone-forming: Osteoid osteoma, Osteosarcoma.
    • Cartilage-forming: Osteochondroma, Enchondroma, Chondrosarcoma.
    • Fibrogenic: Fibroma, Fibrosarcoma.
    • Hematopoietic: Multiple Myeloma.
    • Unknown origin: Giant cell tumor, Ewing sarcoma.
  • Radiological Differentiating Features:
    • Benign: Well-circumscribed, narrow zone of transition, sclerotic border, no periosteal reaction.
    • Malignant: Permeative (moth-eaten), wide zone of transition, Codman's triangle (periosteal elevation), Sunburst pattern.
  • Biopsy Principles: Essential for accurate diagnosis. Open biopsy is preferable to closed (except in spine). Incision must be longitudinal so it can be excised entirely during definitive surgery. Do not use a tourniquet to avoid seeding malignant cells.
Benign Bone Tumors
  • Fibrous Cortical Defect (Non-ossifying fibroma): Commonest in children. Metaphysis. Asymptomatic, heals spontaneously.
  • Fibrous Dysplasia: Bone replaced by fibrous tissue. Ground-glass appearance on X-ray. Can cause Shepherd crook deformity in proximal femur.
  • Osteoid Osteoma: Small (< 2cm) nidus in long bones. Males 10-20 yrs. Severe night pain relieved dramatically by Aspirin (due to high PGE2).
  • Osteochondroma (Exostosis): Mushroom-shaped overgrowth of physeal plate. Cartilage cap + bony stalk. Most common benign tumor. 1-5% risk of malignant transformation if it grows after maturity.
  • Simple Bone Cyst: Children, metaphyseal (proximal humerus). Fluid-filled, heals spontaneously even if fractured.
  • Aneurysmal Bone Cyst (ABC): Aggressive, blood-filled, eccentric ballooning of cortex (soap bubble). High recurrence rate. Needs curettage + bone graft.
  • Enchondroma: Cartilage tumor in medullary cavity. Most common in hand phalanges. O-ring sign calcifications. Multiple = Ollier disease.
  • Giant Cell Tumor (Osteoclastoma): Epiphysis/Metaphysis in young adults (20-40 yrs). Multi-nucleated osteoclast-like giant cells. Soap-bubble appearance. Locally aggressive with risk of malignant transformation (5-10%).
Malignant Bone Tumors
  • Chondrosarcoma: Older adults (mean 43 yrs). Matrix-producing cartilage tumor. Pelvis, femur, ribs. Slow growing, resistant to chemo/radiotherapy. Treated with wide excision. Graded I to III based on cellular atypia.
  • Osteosarcoma: Highly malignant bone-forming tumor. Peaks in < 20 yrs (around the knee) and elderly (secondary to Paget's). X-Ray shows Sunburst appearance & Codman's triangle. Spreads hematogenously to Lungs (90%). Treated with Neo-adjuvant Chemotherapy + Wide Resection.
  • Ewing Sarcoma: Children 10-15 yrs. Arises in Diaphysis of long bones. Mimics osteomyelitis (warm, tender, fever). X-Ray shows Onion-skin pattern (periosteal reaction). Histology shows small round blue cells + Homer-Wright Rosettes. Treated with Chemo + Radio + Surgery.
  • Multiple Myeloma: Malignant plasma cells. Age > 45 yrs. Backache, punched-out lytic lesions in skull/pelvis, hypercalcemia. Urine shows Bence-Jones proteins. Treated with Chemo (Melphalan) + Radiotherapy.
  • Metastatic Bone Tumor (Secondary): More common than primary bone cancer. Originates from Prostate, Breast, Kidney, Lung, Thyroid. Usually Osteolytic (except prostate/breast which can be osteoblastic). Treated palliatively (pain control, prophylactic fixation, radiotherapy).
💡 Golden Hints

1. Tumor by Age: Ewing Sarcoma & Osteosarcoma typically affect patients < 20 years old. Chondrosarcoma, Multiple Myeloma, and Metastatic tumors affect patients > 40 years old.

2. X-Ray Signatures: Onion-skin pattern = Ewing Sarcoma. Sunburst & Codman's triangle = Osteosarcoma. Soap bubble = Giant Cell Tumor / Aneurysmal Bone Cyst.

3. Biopsy Rule: Use a longitudinal incision (not transverse) for an open biopsy, so the entire biopsy tract can be safely excised during definitive surgery.

7. High-Yield Comparisons (المقارنات الامتحانية)

هذه أهم المقارنات المستخلصة من ملازم الجزء الثالث والتي تتكرر باستمرار في الامتحانات:

1. Osteoporosis vs. Osteomalacia
Feature Osteoporosis Osteomalacia
Defect Decreased quantity of bone mass. Decreased mineralization of osteoid.
Bone Quality Qualitatively Normal (matrix/mineral ratio is normal). Qualitatively Abnormal (soft bone, uncalcified osteoid).
Radiology sign Wedge fractures, general osteopenia. Looser zone (transverse band of rarefaction).
Blood chemistry Usually Normal. Decreased Ca/PO4, Increased Alk. Phosphatase.
2. Poliomyelitis vs. Cerebral Palsy (CP)
Feature Poliomyelitis Cerebral Palsy
Etiology Viral infection of Anterior Horn Cells. Non-progressive brain damage (hypoxia, kernicterus).
Type of Lesion Lower Motor Neuron (LMN). Upper Motor Neuron (UMN).
Muscle Tone Flaccid paralysis (decreased tone). Spastic paralysis (>60% of cases).
Sensation Intact (Normal). Intact (Normal).
3. Benign vs. Malignant Bone Tumors (Radiology)
Feature Benign Tumors Malignant Tumors
Borders/Transition Well-circumscribed, Narrow zone of transition. Poorly defined, Wide zone of transition.
Cortical involvement Sclerotic border, intact cortex (usually). Permeative (moth-eaten), cortical destruction.
Periosteal Reaction Usually Absent. Present (Codman's triangle, Sunburst, Onion-skin).
4. Osteosarcoma vs. Ewing Sarcoma
Feature Osteosarcoma Ewing Sarcoma
Age Group Peaks at < 20 years and elderly (Paget's). 10 - 15 years old.
Cell Origin Bone-forming (Mesenchymal cells). Marrow endothelial cells (Small round blue cells).
Typical Location Metaphysis of long bones (around knee). Diaphysis of long bones.
X-Ray Pattern Sunburst pattern & Codman's triangle. Onion-skin pattern.
5. Osteochondroma vs. Osteoid Osteoma
Feature Osteochondroma Osteoid Osteoma
Presentation Painless, hard, slow-growing mass. Severe night pain, no obvious large mass.
Aspirin Response No effect. Dramatic relief of pain.
Radiology Mushroom-shaped outgrowth with cartilage cap. Small radiolucent nidus (<2cm) surrounded by sclerosis.
Malignant Risk 1-5% risk (Chondrosarcoma) if grows after maturity. Benign, does not turn malignant.
6. Primary vs. Secondary (Metastatic) Bone Tumors
Feature Primary Bone Tumors Secondary (Metastatic) Tumors
Frequency Rare. Most common malignant bone tumors.
Age Group Frequently affects children/young adults. Usually older adults (> 50 years).
Lesion Number Usually solitary. Usually multifocal.
Common Origins Osteoblasts, Chondrocytes, etc. Prostate, Breast, Kidney, Lung, Thyroid.
7. Comprehensive Summary of Major Bone Tumors (أهم أورام العظام)

هذا الجدول يجمع أهم الأورام (الحميدة والخبيثة) المذكورة في المحاضرة السادسة مع إبراز وتظليل مفاتيح الحل لكل ورم.

Tumor Age Group Typical Location Key Clinical & X-Ray Features Nature
Osteoid Osteoma 10 - 20 years Diaphysis / Metaphysis Severe night pain relieved by Aspirin. Small radiolucent nidus (<2cm). Benign (Bone-forming)
Osteochondroma Teenagers Metaphysis / Epiphysis Mushroom-shaped outgrowth with cartilage cap & bony stalk. Benign (1-5% malignant risk)
Giant Cell Tumor 20 - 40 years Epiphysis / Metaphysis Soap-bubble appearance. Multi-nucleated osteoclast-like cells. Locally Aggressive (5-10% malignant risk)
Osteosarcoma < 20 years (and elderly) Metaphysis (around knee) Highly malignant. X-Ray: Sunburst pattern & Codman's triangle. Malignant (Bone-forming)
Ewing Sarcoma 10 - 15 years Diaphysis Mimics osteomyelitis. X-Ray: Onion-skin pattern. Histology: Homer-Wright Rosettes. Malignant (Marrow/Round cell)
Chondrosarcoma Older adults (> 40 yrs) Pelvis, femur, ribs, sternum Cartilage matrix, central flecks of calcification. Resistant to chemo/radio. Malignant (Cartilage-forming)
Multiple Myeloma Older adults (> 45 yrs) Skull, spine, pelvis Malignant plasma cells. Punched-out lytic lesions. Urine: Bence-Jones protein. Malignant (Hematopoietic)