Hip Anatomy and Abductor Mechanism

Normal Hip Anatomy

• A normal hip X-ray includes the:
  • Sacroiliac joint
  • Acetabulum
  • Superior pubic ramus
  • Ischium
  • Inferior pubic ramus
  • Pubic symphysis
  • Ilium
  • Sacrum
  • Head of femur
  • Greater trochanter
  • Obturator foramen
  • Lesser trochanter
  • Shaft of femur
• Shenton's line is a continuous line from the lower border of the superior pubic ramus, laterally towards the head and neck of the femur.
  • If this line is disturbed, it indicates pathology of the hip.

Special Tests for Hip

• The Trendelenburg Test assesses the abductor mechanism of the hip
• Principle abductors of the hip : Gluteus medius and Gluteus minimus, supplied by the superior gluteal nerve.
• Abductors help maintain gait
  • I/L abductors help swing the C/L limb.
  • Helps move the limb when the other limb is in the stance phase.

Abductor Failure

• Causes of abduction failure:
• Gluteus medius weakness
• Gluteus minimus weakness
• Superior gluteal nerve palsy
• Coxa vara
• Abductor failure leads to a waddling gait
• To perform the Trendelenburg test:
  • Have the patient stand on each limb for 30 seconds.
  • Observe the anterior superior iliac spine (ASIS).
  • A positive test is when the ASIS/PSIS of the other side goes down, or the sound side sinks when the patient stands on the pathological side.

Thomas Test

• Also known as the Hugh Owen Thomas well leg raise test.
• Used to assess flexion contracture/flexion deformity of the hip

Hip Dislocation

• Posterior dislocation (most common):
  • Mechanism: Dashboard injury.
  • Attitude of limb: Flexion, adduction, and internal rotation (F, AD, IR).
• Anterior dislocation:
  • Mechanism: Deceleration injury, fall from height.
  • Attitude of limb: Flexion, abduction, and external rotation (F, AB, ER).
• In a posterior dislocation the limb is shortened.
  • X-ray: Shenton's line is broken; adduction and internal rotation of the limb; lesser trochanter is not visible.
  • Palpation: Head palpable in the gluteal region.
• In an anterior dislocation the limb is lengthened.
  • X-ray: Head lies outside the acetabulum; Shenton's line is broken; abduction and external rotation of the limb.
  • Palpation: Head palpable in the femoral triangle.

Hip Dislocation Management and Complications

• Management: Closed reduction
  • If closed reduction is not possible due to muscle spasm, perform closed reduction under anesthesia
  • If closed reduction under anesthesia doesn't work then open reduction + Apply skeletal traction
• Complications:
  • Avascular necrosis: Most common if not reduced within 6-12 hours post-injury.
  • Sciatic nerve injury: In posterior dislocation, presents with foot drop/high stepping gait due to common peroneal nerve injury.

Proximal Femur Fractures

• Blood Supply to the head of the femur comes from the medial and lateral circumflex femoral artery and the profunda femoris artery.
• Intracapsular neck of femur (NOF) fractures Disrupts blood supply, so has a higher risk of AVN
• Types include:
  • Head of femur
  • Intracapsular neck
  • Extracapsular neck
• Relevant anatomy
  • Acetabulum
  • Medial circumflex artery
  • Capsule
  • Extracapsular NOF/ intertrochanteric fracture

Neck of Femur Fractures

• Classifications include Anatomical, Pauwel’s, and Garden’s.
• Intracapsular Fracture:
  • Age: 50-60 years
  • Sex: Female >>> males
  • Trauma: Trivial fall
  • Pain: Mild Pain
  • Location of pain: Scarpa's Triangle
  • Shortening:
  • Deformity/attitude: External rotation <45° (capsule limits it)
  • Complication: Avascular Necrosis (AVN) (45%) > Non-union (30%) due to disruption of blood supply
    • X-ray: Intracapsular fracture, Shenton's line abnormal, Joint capsule
• Intertrochanteric/Extracapsular Fracture:
  • Age: 70-80 years
  • Sex: Female > males
  • Trauma: Moderate to severe fall
  • Pain: Moderate to severe pain
  • Location of pain: Trochanteric region
  • Shortening: > 1 inch
  • Deformity/attitude: External rotation >45° (Lateral part of foot touches the bed)
  • Complication: Malunion/Coxa vara/↓ in neck-shaft angle (No disruption of blood supply)
    • X-ray: Extracapsular fracture, Joint capsule

Neck of Femur Fracture Treatment

• In patients less than 65 years:
  • If less than 3 weeks, and Non-viable Head Of Femur then do closed reduction IF + cannulated cancellous screws
  • If less than 3 weeks and Viable, do Fix + vascularisation procedures: Meyers, Bakshi, Fibular vascular graft
  • If more than 3 weeks, get an MRI
• In patients 65 years or older, do replacement.
  • If the hip was previously normal, do Hemiarthroplasty like Austin Moore, Thompson, Bipolar (Best)
  • If the hip was previously Abnormal, do Total replacement for example in Osteoarthritis
• If both fail and it is in a young patient, do Fix + osteotomy: McMurray or Pauwels (Better)

Hemiarthroplasty vs Total Arthroplasty

• Hemiarthroplasty: Replacement of only the head and neck of the femur.
• Total arthroplasty: Replacement of the head and neck of the femur + acetabular cup.

Intertrochanteric Fracture Management

• Surgical: Maintain neck shaft angle (125°-130°) with devices to prevent coxa vara.
• Proximal femoral nail with locking and stabilization screws is the best modality.
• Dynamic Hip Screw: Sliding compression mechanism.

Shaft of Femur Fracture Management

• Derotation boot allows healing in a malunited position and prevents external rotation.
• Conservative Management is used in inoperable cases (age, comorbidities)
• Patellar tendon bearing cast (conservative)
• Closed Reduction and Internal Fixation (CRIF) with intramedullary rod/nail with interlocking screws is the definitive treatment

Fat Embolism Syndrome (FES)

• Pathogenesis: Leakage of intramedullary fat into circulation.
• Clinical features: Not seen in children.
  • Cutaneous: Petechial rash.
  • Cardiorespiratory: Dyspnea/tachypnea -24-48 hours after polytrauma.
  • CNS: Depression, coma, anxiety.
• Diagnosis: GURDS criteria.
  • Major criteria (4):
    • Axillary/Subconjunctival petechiae.
    • PaO2 below 60 mmHg.
    • CNS depression.
    • Pulmonary edema.
  • Minor criteria (8):
    • Tachycardia.
    • Fever.
    • Anemia.
    • Thrombocytopenia.
    • Fat globules in sputum.
    • Fat globules in urine (Lipuria): Gurd test.
    • ↑ ESR
    • Retinal emboli.
• Presence of 1 major and 4 minor criteria = Fat embolism.
• Management:
  • Prevention: Immobilization + Early fixation of fracture.
  • Treatment: Supportive O2+ IPPV.

Treatment of Femur Shaft Fracture

• Age <6 months: Pavlik harness
• Age 6 months-5 years: Hip spica cast (If <2 years/ 12 kg: Gallows traction)
• Age 5-10 years: Flexible nails (Ender's nail, TENS)/Plates if unstable
• Age >10 years: Intramedullary interlocking nails

Leg Injuries

• Patella Fracture:
  • Due to direct trauma to the knee.
  • Treat with tension band wiring with K wires.
• Bipartite Patella:
  • Congenital anomaly: Accessory ossification center.
  • A small separated fragment due to incompletely fused patella at the superolateral pole.
  • Incidental finding on x-ray.
  • Rarely painful.
  • Conservative management.

Tibial Shaft Fracture

• Management:
  • Conservative: Patellar tendon-bearing cast.
  • Definitive: CRIF with intramedullary rod/nail with interlocking screws.
• Runner's Fracture:
  • Stress fracture of the fibula seen in marathon runners.

Ankle Joint Anatomy

• Bones and features:
  • Lateral malleolus
  • Medial malleolus
  • Posterior malleolus
  • Talus
  • Calcaneus

Ankle Fractures

• Types include:
  • Isolated lateral malleolus
  • Bimalleolar/Pott's
  • Trimalleolar/Cotton's

Foot Fractures

• Initial management: Closed reduction, Neurovascular assessment before and after reduction, then slab application,
• After swelling goes down perform definitive surgery
• Calcaneal Fracture:
  • Mechanism: Fall from height landing on feet.
  • Angles to assess reduction:
    • ↓ Bohler's angle
    • ↑ Gissane's angle.
• Aviator's Fracture:
  • Fracture of the talar neck.
  • ↑ Risk of avascular necrosis of the body of the talus.
  • Hawkins classification of talar neck fracture.
  • Blood supply of the talus: Dorsalis pedis → Sinus tarsi A.
• Chopart's Fracture:
  • Fracture of the intertarsal joint.
  • Amputation at the intertarsal joint is known as Chopart's amputation.
• Lisfranc's Fracture:
  • Fracture of the tarso-metatarsal joint.
  • Amputation at the tarsometatarsal joint is known as Lisfranc's amputation.

Robert Jones Fracture

• Fracture of base of the 5th metatarsal with Articulation of 4th and 5th metatarsals
• Zone 3 (Stress fracture)
• Zone 2 (True Jones fracture) In watershed area (vascularity) Non-union
• Zone 1 (Pseudo Jones fracture) Due to avulsion of peroneus brevis tendon
• Non-weight bearing short leg cast for 6-8 weeks
• Intramedullary screw fixation if displacement

Nerve Injuries

• Anterior or inferior shoulder dislocation: Axillary (Circumflex humeral) nerve.
• Fracture of the surgical neck of the humerus: Axillary nerve.
• Fracture of the shaft of the humerus: Radial nerve.
• Fracture of the supracondylar humerus: Anterior interosseous nerve (AIN) > median > Radial > ulnar (AMRU).
• Medial condyle humerus: Ulnar nerve.
• Cubitus valgus: Tardy ulnar nerve palsy.
• Monteggia fracture dislocation: Posterior interosseous nerve
• Lunate dislocation: Median nerve.
• Hip dislocation: Sciatic nerve.
• Neck of fibula fracture: Common peroneal nerve.

Summary of Femur Fractures

• Intracapsular Neck of Femur Fracture:
  • If >65 years, then Hemiarthroplasty/Total hip replacement.
  • If <65 years, MRI, then Osteotomy if it fails.
• Intertrochanteric Fracture: Treat with DHS/PFN (All age groups).
• Femur Shaft Fracture: Treat with Nailing (All age groups).