Hip Dislocation

Synovial ball/socket; head = 2/3 sphere; capsule strong anteriorlyLigaments: supported by iliofemoral, pubofemoral, ischifemoral ligament, ligament of head of femur and transverse ligament of acetabulumBlood supply: ascending branches of medial and lateral circumflex femoral arteries (from profunda femoris); prone to disruption from fractures acetabular branches of obturator and medial circumflex branches of inferior and superior gluteal Femoral head supplied by reticular anastomosis from medial and lateral circumflex, and artery of head of femur (runs with ligament of head and enters at fovea; more important in children)Epiphyses: Body: appears 7/40 all disappear at 18-20yrs Lower end: appears birth Head: appears 6-12/12 Greater trochanter: appears 4yrs Lesser trochanter: appears 8yrs

In prosthesis: 70% in 1st month; due to XS flexion, adduction and internal rotationNative: trauma (associated with sciatic nerve injury in 10-15%, fracture of femoral head in 5%); sciatic nerve injury may be due to acetabular rim fracture

Anatomy

Posterior Dislocation

80-90%

Epidemiology

Forced applied to flexed knee posteriorlyMOI

Short, adducted, internally rotated Likely irreducible fracture/dislocation if knee slightly flexed and hip in neutral position

Examination

10% avascular necrosis (more if longer time dislocated)50% acetabular / femoral fracture10% sciatic nerve injury

Complications

Urgent if native (within 6hrs); bed rest after for few days if 1st, otherwise early mobilisation if recurrentAllis manouevre: stand on bed; hold down pelvis; hip and knee flex 90°; correct adduction and internal rotation; grasp ankle between knees to provide fulcrum; axial traction with rocking motion; can add lateral traction to proximal femurStimson: lie prone; leg hang over side of bed; 90° flexion as above; push down on calf and bum; better if femoral fractureBigelow: flex (with your forearm under knee as fulcrum to provide upward traction) abduct externally rotate extend internally rotate to neutralReverse Bigelow: quick jerk to slightly flexed thighWhister: elbow beneath affected knee, hand on unaffected knee; hold affected ankle; push up with arm

Management

Anterior Dislocation

10%

Usually MVA (forced abducation)Epidemiology

Type I: superior/pelvic, hip extended at time of injuryType II: inferior/obturator, hip flexed at time of injuryHip abducted and externally rotated at time of injury in both

Classification

Abducted, externally rotated, flexedCan palpate femoral head anteriorlyExamination

Femoral artery and femoral nerve injuryComplications

Orthopaedic emergency; do within 6hrs to avoid avascular necrosis; reduced under GA; in-line traction with hip and knee flexion to 90° and internal rotationManagement

Central

fracture / dislocation

Through acetabulum; needs reduction under GA

Obturator Dislocation

Head over obturator foramenShort, abducted and externally rotatedNeeds reduction under GA