Fracture Principles & Complications

A fracture is a break in the structural continuity of bone (or cartilage/physis). This is a foundational orthopaedic-trauma topic for NEET PG that ties together classification systems, the biology of bone healing, the principles of reduction–holding–rehabilitation, and the feared early and late complications (compartment syndrome, fat embolism, avascular necrosis, malunion/non-union).

Definition & Description of a Fracture

A fracture is described systematically so that any examiner can picture it from the words alone. The standard descriptive sequence:

1. Site → diaphyseal / metaphyseal / epiphyseal / intra-articular.
2. Pattern → transverse, oblique, spiral, comminuted (≥3 fragments), segmental, greenstick, buckle/torus, avulsion, impacted.
3. Displacement → translation, angulation, rotation, shortening (overriding) or distraction.
4. Open vs closed → does the fracture communicate with the external environment?
5. Special features → physeal involvement, pathological bone, intra-articular step.

High-yield: A transverse fracture results from a bending/tapping force, an oblique/spiral fracture from a twisting (torsional) force, and a comminuted fracture from high-energy direct trauma. Greenstick and torus (buckle) fractures are incomplete fractures seen almost exclusively in children because of their soft, elastic periosteum.

Mechanism-to-pattern mnemonic

"Twist gives Spiral, Bend gives Transverse, Crush gives Comminuted."

Classification Systems

1. AO/OTA Classification

The AO (Arbeitsgemeinschaft für Osteosynthese) system uses an alphanumeric code: the bone and its segment are numbered, then the fracture type is graded by complexity.

AO Type	Meaning	Complexity
A	Simple (two fragments)	Least complex
B	Wedge (butterfly fragment, but cortices still contact after reduction)	Intermediate
C	Complex/comminuted (no cortical contact after reduction)	Most complex

High-yield: In the AO numbering of long bones, proximal = 1, diaphysis (shaft) = 2, distal = 3. Bones are numbered 1 = humerus, 2 = radius/ulna, 3 = femur, 4 = tibia/fibula. So "32-A" = femoral shaft, simple.

2. Gustilo–Anderson Classification (OPEN fractures)

This is the single most examined classification in trauma. It grades open (compound) fractures by wound size, soft-tissue damage, contamination and vascular status.

Grade	Wound	Soft tissue / contamination	Notes
I	< 1 cm, clean	Minimal	Low energy, inside-out puncture
II	1–10 cm	Moderate, no extensive damage	Moderate energy
IIIA	> 10 cm	Extensive soft tissue, but adequate periosteal cover	High energy; segmental/comminuted
IIIB	> 10 cm	Extensive loss, periosteal stripping, needs flap cover	Bone exposed
IIIC	Any size	Arterial injury requiring repair	Worst prognosis

High-yield: ANY of the following automatically upgrades a wound to Grade III regardless of skin wound size — high-velocity/gunshot injury, segmental fracture, farmyard/grossly contaminated wound, fracture > 8 hours old, or associated neurovascular injury. Grade IIIC = arterial injury needing repair and carries the highest amputation rate.

High-yield: Risk of infection rises with grade: roughly 0–2% (I), 2–5% (II), up to 10–50% (III). Antibiotics must be given within the first hour: first-generation cephalosporin for Grade I–II; add an aminoglycoside (gram-negative cover) for Grade III; add penicillin/metronidazole for farmyard/anaerobic (clostridial) contamination.

3. Salter–Harris Classification (PHYSEAL/growth-plate injuries in children)

Mnemonic "SALTR":

Type	"SALTR"	Description	Prognosis
I	S = Slipped/Separated	Through the physis only	Best
II	A = Above	Physis + metaphysis (Thurston-Holland fragment)	Commonest (~75%), good
III	L = Lower	Physis + epiphysis (intra-articular)	Needs anatomic reduction
IV	T = Through/Together	Metaphysis + physis + epiphysis	Risk of growth arrest
V	R = Ruptured/cRush	Crush of physis	Worst, growth arrest

High-yield: Salter–Harris Type II is the most common; Type V has the worst prognosis (premature physeal closure, limb shortening, angular deformity). Types III & IV are intra-articular and demand anatomical reduction.

Eponymous fractures worth memorising

• Colles — distal radius, dorsal displacement ("dinner-fork" deformity), fall on outstretched hand.
• Smith — distal radius, volar (reverse Colles), "garden-spade" deformity.
• Galeazzi — radial shaft fracture + distal radio-ulnar joint dislocation ("fracture of MUGR": Monteggia = Ulnar + radial head; Galeazzi = Radial + DRUJ).
• Monteggia — proximal ulnar fracture + radial head dislocation.
• Bennett — intra-articular fracture-dislocation of base of first metacarpal.
• Jones — base of 5th metatarsal (zone 2); high non-union risk.
• Pott — bimalleolar ankle.

Stages of Fracture Healing (Secondary Bone Healing)

Secondary healing occurs with relative stability (cast, intramedullary nail, bridging plate) and proceeds through callus. Primary (direct) healing occurs with absolute stability (rigid compression plate, lag screw) and has no visible callus — it heals by cutting cones / Haversian remodelling.

Inflammation (haematoma) → Soft callus (fibrocartilage) → Hard callus (woven bone) → Remodelling (lamellar bone)

Stage	Timing	Key event
1. Haematoma & inflammation	0–7 days	Cytokines (TNF-α, IL-1/6), BMPs, macrophages
2. Soft callus	2–3 weeks	Chondroblasts lay fibrocartilage; provides initial stability
3. Hard callus	3–12 weeks	Endochondral & intramembranous ossification → woven bone
4. Remodelling	months–years	Wolff's law; woven → lamellar bone, medullary canal reforms

High-yield: Primary (direct) healing = absolute stability, NO callus, Haversian remodelling. Secondary healing = relative stability, abundant callus. A surgeon who sees no callus on a plated fracture is reassured, not alarmed — that is intended primary healing.

High-yield: BMP-2 and BMP-7 (OP-1) are osteoinductive proteins used to augment healing. Wolff's law governs remodelling: bone is laid down where mechanically stressed and resorbed where not.

Factors delaying union

• Local: infection, inadequate immobilisation, gap/distraction, bone loss, poor blood supply, intra-articular fractures (synovial fluid lyses haematoma), soft-tissue interposition.
• Systemic: smoking, diabetes, steroids, NSAIDs (inhibit prostaglandin-driven healing), malnutrition, age, bisphosphonates.

Principles of Fracture Management

The classic teaching is the "4 Rs":

Resuscitate → Reduce → Retain (Hold) → Rehabilitate (Restore function)

1. Resuscitation — ATLS first; a fracture is rarely the immediate threat. Open fractures: tetanus prophylaxis, IV antibiotics within 1 hour, photograph and cover wound, splint.
2. Reduction — restore alignment.
   • Closed reduction — manipulation under anaesthesia; followed by cast/traction.
   • Open reduction — for intra-articular, failed closed reduction, open fractures.
3. Retention/Holding — maintain reduction.
   • Conservative: plaster cast, functional brace, skin/skeletal traction.
   • Operative (internal fixation): plates & screws, intramedullary nail, K-wires, tension band.
   • External fixation: for open fractures, severe soft-tissue injury, damage-control orthopaedics.
4. Rehabilitation — early mobilisation to prevent stiffness, fracture disease and muscle wasting.

High-yield: Intramedullary (IM) nailing is the gold standard for diaphyseal long-bone fractures of the femur and tibia in adults — it is load-sharing and allows early weight-bearing. Reamed, locked IM nail for femoral shaft. Plate fixation is preferred for metaphyseal/articular fractures and forearm shafts (where exact length/rotation matters).

High-yield: AO principles of fracture fixation: (1) anatomical reduction (esp. articular), (2) stable fixation, (3) preservation of blood supply (biological fixation), (4) early active mobilisation. Lag screw + neutralisation plate gives absolute stability and compression.

Damage-control orthopaedics

In a polytrauma/physiologically unstable patient, definitive fixation is deferred. Temporary external fixation (span the joint) is applied early, and conversion to internal fixation is done once the patient is resuscitated ("second hit" theory — avoid amplifying the inflammatory response).

Complications of Fractures

Classification of complications

Timing	Local	Systemic / General
Immediate	Vascular injury, nerve injury, visceral injury, skin loss	Haemorrhage, shock
Early	Compartment syndrome, infection, gangrene	Fat embolism, ARDS, DVT/PE, crush syndrome, tetanus
Late	Malunion, non-union, delayed union, AVN, myositis ossificans, Volkmann's contracture, joint stiffness, OA, growth disturbance, CRPS, implant failure	—

1. Compartment Syndrome (EARLY, surgical emergency)

Raised pressure within an osseofascial compartment compromises perfusion, causing ischaemic muscle/nerve injury.

High-yield: The earliest and most reliable clinical sign is pain out of proportion and pain on passive stretch of the muscles in that compartment. The classic "6 P's" — Pain, Pallor, Paraesthesia, Paralysis, Pulselessness, Poikilothermia — appear LATE; pulses are usually present even in established compartment syndrome (do NOT wait for pulselessness).

High-yield: Closed tibial shaft fracture is the commonest cause. Diagnosis is clinical; if measured, compartment pressure > 30 mmHg absolute or a delta pressure (diastolic BP − compartment pressure) < 30 mmHg mandates intervention. Treatment = emergency fasciotomy (release all four compartments of the leg). Remove all encircling casts/dressings first.

Volkmann's ischaemic contracture is the late sequela of an untreated forearm compartment syndrome (classically after supracondylar fracture of humerus in children) → fixed flexion claw-hand deformity.

2. Fat Embolism Syndrome (EARLY)

Marrow fat enters the circulation after long-bone (especially femoral shaft) or pelvic fractures, typically 24–72 hours after injury, in young adults.

High-yield: Gurd's criteria — major: respiratory insufficiency (hypoxaemia/ARDS), cerebral signs (confusion), petechial rash (axilla, conjunctiva, chest — pathognomonic); minor: tachycardia, fever, retinal fat/emboli, fat in urine/sputum, thrombocytopenia, dropping haematocrit. The classic triad = hypoxaemia + neurological changes + petechial rash.

High-yield: Management is largely supportive — oxygen and respiratory support. The single most important preventive step is early fracture stabilisation. Heparin and steroids are NOT routinely recommended.

3. Avascular (Avascular/Aseptic) Necrosis — AVN (LATE)

Death of bone due to interruption of blood supply. Certain sites have retrograde/precarious blood supply and are notorious for AVN.

High-yield: Classic AVN-prone sites and their fractures:

• Femoral head — after intracapsular (subcapital) neck of femur fracture (medial circumflex femoral artery torn).
• Scaphoid — proximal pole, after waist fracture (retrograde supply from distal pole).
• Talus body — after talar neck fracture (Hawkins classification).
• Lunate — Kienböck's disease.

High-yield: MRI is the investigation of choice for early AVN (detects marrow oedema before X-ray changes). On X-ray, the "crescent sign" (subchondral lucency) is characteristic. Hip AVN is staged by the Ficat–Arlet classification.

4. Delayed Union, Non-union & Malunion (LATE)

• Delayed union — healing slower than expected for that bone but still progressing.
• Non-union — union has failed; no progress over 3 consecutive months (often defined ~6–9 months). Types: hypertrophic ("elephant-foot", good vascularity, inadequate stability → needs rigid fixation) vs atrophic (poor vascularity → needs bone grafting + fixation).
• Malunion — healed in unacceptable alignment (angulation, rotation, shortening) → functional/cosmetic deformity, secondary OA.

High-yield: Hypertrophic non-union = mechanical problem (stability) → treat with rigid fixation. Atrophic non-union = biological problem (blood supply) → treat with bone grafting ± BMP. Sites prone to non-union: scaphoid, neck of femur, tibial shaft (lower 1/3), lateral condyle humerus, Jones fracture.

5. Implant Failure (LATE)

Metal fatigue: cyclical loading on an implant bridging an ununited fracture eventually causes the implant to bend or break. An implant is in a "race against time" — the fracture must unite before the implant fails. Signs: progressive pain, breakage/back-out of screws, loss of position on serial X-rays. Other implant problems: peri-implant fracture, infection (biofilm), loosening, metal hypersensitivity.

High-yield: Implant failure usually signals an underlying non-union — the implant did not fail in isolation; it broke because the bone never shared the load.

6. Other notable complications

• Myositis ossificans — heterotopic ossification in muscle, classically after elbow dislocation/supracondylar fracture and aggressive passive physiotherapy. Avoid forced passive movement.
• Complex Regional Pain Syndrome (CRPS / Sudeck's atrophy) — disproportionate pain, swelling, vasomotor changes, patchy ("spotty") osteopenia on X-ray; commonest after distal radius fracture.
• Crush syndrome — rhabdomyolysis → myoglobinuria → acute kidney injury + hyperkalaemia.
• Deep vein thrombosis / pulmonary embolism — especially pelvic/lower-limb fractures; needs thromboprophylaxis.

Investigation of Choice

Scenario	Investigation of choice
Suspected fracture (first line)	Plain X-ray — 2 views (AP + lateral), include joint above & below
Occult scaphoid / hip fracture, early AVN, stress fracture	MRI
Complex intra-articular / pelvic / spinal fracture (preop planning)	CT
Pathological/metastatic bone, stress fracture follow-up	Bone scan

High-yield: The "rule of 2s" for X-rays — 2 views, 2 joints (above and below), 2 limbs (compare in children), 2 occasions (repeat in 10–14 days for occult scaphoid fracture).

Key Differentials & Look-alikes

• Fracture vs accessory ossicle / sesamoid — smooth, corticated margins favour ossicle; sharp irregular edge favours fracture.
• Pathological fracture — fracture through abnormal bone (metastasis, myeloma, simple bone cyst, osteoporosis); minimal trauma + lytic/blastic lesion. Always think malignancy in an elderly patient with a low-energy fracture and a lucent lesion.
• Stress fracture — repetitive loading in normal bone (athletes, military recruits); X-ray often normal early, MRI/bone scan diagnostic.
• Greenstick vs complete fracture — only in children; incomplete cortical break.
• Septic arthritis / osteomyelitis — when an "open fracture" patient deteriorates, exclude deep infection.

Recently asked / exam angle

• Gustilo–Anderson grading of open fractures is a perennial favourite — especially that Grade IIIC = arterial injury and that segmental/grossly contaminated/farmyard wounds are Grade III irrespective of size. Antibiotic choice by grade is frequently tested.
• Salter–Harris with the SALTR mnemonic — "Type II commonest, Type V worst prognosis" is a near-guaranteed one-liner.
• Compartment syndrome — "earliest sign = pain on passive stretch," "pulses present," "delta pressure < 30 mmHg," and "emergency fasciotomy" are classic single-best-answer stems. Commonest cause = closed tibial fracture.
• Fat embolism — petechial rash + hypoxaemia 24–72 h after femoral fracture; Gurd's criteria; management supportive; prevention by early fixation.
• AVN-prone sites (femoral head, scaphoid proximal pole, talus, lunate) and MRI as investigation of choice are repeatedly asked.
• Primary vs secondary bone healing — "no callus = primary healing under absolute stability" trips up many candidates.
• Hypertrophic vs atrophic non-union management (stability vs grafting) is a high-yield differentiator.
• AO basics — A/B/C complexity grading and segment numbering occasionally appear.

Rapid revision

1. Gustilo IIIC = arterial injury needing repair → highest amputation risk; give cephalosporin + aminoglycoside ± penicillin within 1 hour.
2. Salter–Harris II is commonest; Type V worst (physeal crush → growth arrest).
3. Compartment syndrome: earliest = pain on passive stretch; pulses present; delta pressure < 30 mmHg → emergency fasciotomy; commonest after closed tibial fracture.
4. Fat embolism = hypoxaemia + cerebral signs + petechiae at 24–72 h; Gurd's criteria; treat supportively; prevent by early fixation.
5. AVN sites: femoral head (intracapsular #NOF), scaphoid proximal pole, talus, lunate (Kienböck); MRI is investigation of choice; X-ray crescent sign.
6. Primary healing = absolute stability, NO callus (Haversian remodelling); secondary healing = relative stability, callus.
7. Hypertrophic non-union → rigid fixation; atrophic non-union → bone graft.
8. IM nailing = gold standard for femoral/tibial shaft; plating for articular/forearm fractures.
9. Volkmann's contracture = late forearm compartment syndrome, classically after paediatric supracondylar humerus fracture.
10. X-ray rule of 2s: 2 views, 2 joints, 2 limbs (kids), 2 occasions (occult scaphoid).
11. Colles = dorsal, Smith = volar; Galeazzi = radius+DRUJ, Monteggia = ulna+radial head.
12. Implant failure usually means an underlying non-union — the implant lost the race against time.