Orthopedics: Bone Anatomy

• The study notes cover basics of General Concepts of Trauma, Upper and Lower Limb Trauma, Cumulative Trauma Disorders, Orthopedic Oncology, Nerve Injuries, Metabolic Diseases of the Bone, Orthopaedic Infections, Spine Injuries and Disorders, Joint Disorders, Paediatric Orthopedics, and Sports Injuries.

Anatomy of Bone

• Bone consists of organic and inorganic components.
• Cells make up 5-10% of bone.
• Organic component or osteoid constitutes water, which occupies a higher percentage in children.
• Inorganic component comprises calcium hydroxyapatite, which is the principal mineral.
• Proteins make up 90-95% of bone, and Collagen Type I. Is the principal protein.
• Osteoblasts, osteoclasts, and osteocytes are bone cell types.
• Osteoblasts are mononuclear cells that lay down osteoid matrix, facilitating mineral deposition, and are rich in alkaline phosphatase.
• Osteoclasts are monocyte aggregates/multinucleated giant cells which are phagocytic, facilitate bone resorption and remodelling, rich in Tartrate Resistant Acid Phosphatase (TRAP) and carbonic anhydrase, are least in number.
• Osteocytes are resting, mature osteoblasts, most abundant in bone and have the longest lifespan.
• Meniscus of the knee joint comprises Collagen type I.
• Articular hyaline cartilage contains collagen type II.
• Bone formation markers increase in bone resorption.
• TRAP elevates in osteoporosis due to increased osteoclast activity.

Parts of Bone

• Medullary cavity holds marrow in children and fat in adults.
• Yellow bone marrow, compact bone, periosteum, Sharpey's fibers, and nutritient arteries are parts of the bone
• Sharpey’s fibers anchor the periosteum to bone.
• The growth plate facilitates longitudinal or interstitial growth.
• The epiphyseal/physeal plate, visible only in children, comprises germinal, proliferative, hypertrophic, and calcification layers and an ossification layer.
• The germinal Layer is most important, while hypertrophic layer is the weakest.

Physeal Injuries

• Hypertrophic layer sustains injury in most traumatic injuries
• Germinal layer injuries affect overall growth.
• Salter-Harris classification mnemonic: SALTER.
• SALTER Classification:
  • Type I (Split): Fracture splits the growth plate, but the germinal layer is intact; Normal Growth, Good Prognosis.
  • Type II (Away): Fracture splits the growth plate, extending into the metaphysis, no injury to geminal matrix; Metaphyseal fragment: Thurston Holland; Good Prognosis.
  • Type III (Lower): Fracture splits the growth plate, extending into the epiphysis, injuring the germinal layer; Bad Prognosis.
  • Type IV (Through Everything): Fracture extends through all layers and germinal layer; Bad prognosis.
  • Type V (Rammed/Crushed): Worst outcome, Impaction injury crushes growth plate, missed on x-ray.

Fractures

• Diagnosis: Clinical assessment of abnormal mobility or through X-ray.
• Causes divided into significant and insignificant trauma scenarios.
• Significant trauma leads to stress fractures in normal bone with abnormal loading, causing point tenderness.
• Insignificant trauma leads to pathological fractures in abnormal or weak bone, causing pain before the fracture due to pre-existing lesion.
• Localized causes include infection, ischemia, lesions, cysts, and radiation.
• Generalized causes include osteoporosis, metastasis, osteogenesis imperfecta, osteopetrosis, scurvy, rickets/osteomalacia and Paget's Disease.

Bone Fractures, Stress Fractures, Healing, and Non-healing

• Vertebral compression fractures have wedge formations and are usually in pathological fractures.
• Subtrochanteric fractures of the proximal femur exhibit banana fractures
• To plan for prophylactic fixation of pathological fractures, Mirel's criteria is used and scores are above 8.
• In Stress fractures, pain follows activity, particularly intense activity and frequency, and affects lower limb bones more than upper limb bones.
• Stress Fractures- initial x-ray results are often negative in the first 2-3 weeks
• For Stress Fractures, MRI scans will should soft tissue edema and IOC will detect the fractures.
• Frequent sites of stress fractures include the Tibia, as wells as metatarsals, and they require a bone scan.
• Metatarsal stress fractures are more likely in the neck of the bone vs the shaft.
• Fractures require primary and secondary healing to close
• Primary Healing has direct, intramembranous healing with absolute stability via compression plates and lag screws to result in Callus- Free closure
• Secondary Healing has indirect, endochondral healing with relative stability through Pop/braces, external fixation, bridge plating, and intramedullary nailing as it results in movement.
• Non Union is associated with Hematoma formation (2-3 days)., Granulation tissue formation & Inflammation with fibroblasts (2-3 weeks)., Callus formation-Fibroblasts to Osteoblasts (2-3 months)., Consolidation (2-3 years)., Bone remodelling-Woven bone transitions to Lamellar Bone (3 years).
• Factors affecting fracture healing include patient age, nutrition, and tobacco/alcohol Use, as wells as improper immobilization type and the type of fracture.

Healing Complications and Non-union

• Factors affecting fracture healing include patient age/nutrition/tobacco/alcohol use, as wells as improper immobilization and inadequate treatment.
• Healing complications include hypertrophic and atrophic types.
• hypertrophic fractures have smooth and sclerosed ends, are visible via X-ray, have exuberant and proper bone biology, associated with improper treatment and require re-treatment via immobilization.
• atrophic fractures have absent bone biology and callous formation, are also typically a result of poor treatment.
• Bone grafts are most effective from the iliac crest due creeping substitution helps bone grow.
• Healing in an anatomically abnormal position can cause malunion. Treatment includes osteotomy with cutting, realigning & bone fixation).
• Fractures that result in a malunion very rarely/never revert to non-union and vice versa.
• Bones with a malunion: clavicle, supracondylar humerus, Colle's, intertrochanteric femur.
• Bones with a non-union: lower 1/3rd of the tibia, scaphoid, lateral condyle of the humerus, neck of the femur, talus.

Fractures: Management & Open

_ Fracture Management_

• Intra-articular fracture requires ORIF w/I&S plates & screws.
• Extra-articular fractures can be managed via conservative (POP cast, slab, traction) & Surgical (Definitive) methods.

A. Upper limb: plating with screws. B. Lower limb- Intramedullary rods/nails with interlocking screws.

Fractures of Necessity

• Intra-condylar #
• Lateral condylar humerus #
• Monteggia/Galeazzi #.
• Neck of femur #

Open Fractures (OF) Fractures with skin and soft tissue disruption

• Common pathogen = S. aureus, hematoma can also escape.

A. Management a. Wound Management: - Antibiotics: Broad spectrum - Wound wash: Sterile normal saline, Povidone-iodine (Betadine), H2O2 2. Surgical Management:

• IF: >6 hr old injury, a new neurovascular injury is present, if edges can’t be approximated.

3. External fixation: wound cleaning and early definitive surgery. 4: Gustilo Anderson Classification: guides definitive treatment.

• External 1st
• Intra EF with surgery once it's closed

External Fixators

• Illizarov ring: multi planar

• rings and pins, distraction osteogenesis (callotaxis) at 1mm/mm day, used in fractures of bones with bone loss .

• Rail fixators: Combination of compression/external fixation.

• Spanning plate: pins, connects bones, stabilizes and spans periarticular fractures

• Ring sequestrum is a common complication that heats the bone during fixes.

• The stability improves if number of pins, rods, and planes are biplanar.

Amputation

Trauma Scores and Types: -Mangled Extremity Severity Score: Score ≥ 7 = Amputation

• Limb Salvage Score -Ganga Score -Amputation: Cutting Limb trough the bone . - Disarticulation: Cutting Limb through a joint..

• SACH (prefered for Indians)

• Trauma Lower extremity.

ATLS

Advanced Life Support (ATLS): 1: Airway: Chin lift/jaw thrust with neck stability - 2: Breating - 3: Circulation - 4: Disability: Glasgow Coma Scale (GCS) 5: Environment: keep Temperature stable..

Pelvic Fractives

• Pelvis has a lot of space which can hide a mass amount of bleeding
• Fracture requires high level of suspicion- high bleeding from fracture requires Tamponade: pelvis binder or handbedsheets ..

AVN/Osseoncrosis

• A vascular necleous: neck of femur, scaphoid.
• Non traumatic is idiopathic, steroid use, sickle cell disease and cancer Traumatic and non-Traumatic reasons.

Bones

• Bones include Head of femur, prox scaphoid prox talus, femoral condyle, humeral head, capitilam.
• X ray- white is from dead bone IOC-Mri and fix total hip replacement.