· osteoarthritis caused by load exceeding tolerance of cartilage
· anatomical deformity causing increased loads per unit area
· inflammatory or metabolic disease leading to abnormal cartilage
· most often from anatomical deformity
· dysplasia (45%)
·
Perthes disease (20%)
SUFE (10%)
· osteoarthritis by age 50 occurs in
· 50% of patients with dysplasia or Perthes disease
· 20% of patients with SUFE
· failure of cartilage can be halted by decrease in load
· aim of osteotomy is to correct deformity
· before osteoarthritis begins (reconstructive)
· before end-stage osteoarthritis occurs (salvage)
· pain relief achieved by
· relief of localized increases in intra-articular pressure
· relief of increased intra-osseous pressure
Reconstructive
· age < 25 yrs
· some biological plasticity remains
· x-ray shows at-risk hip
· must be likely that osteotomy will restore normal prognosis
Salvage
· age < 50 yrs
· x-ray shows mechanical pathogenesis of hip disease
· localised changes of sclerosis, joint space narrowing and cysts
· must be likely that congruence improved by osteotomy
· nature of pain
· disability
· requirements
· contractures
· flexion adduction contractures common
· may be eliminated with valgus-extension osteotomy
· flexion-extension arc
· should be at least 80o
· abduction-adduction arc
· correction should not exceed arc
· AP pelvis
· true lateral (faux profil)
· to assess anterior uncovering
· simulating radiographs
· in various positions simulating correction
· maximum abduction and adduction
· examination under image intensifier
· positions to simulate correction
· assessment of anteversion
· 3D CT
· for complex dysplasias
· femoral osteotomy for femoral disorders
· AVN, Perthes, SUFE
· pelvic osteotomy for acetabular disorders
· hip dysplasia
· varus intertrochanteric osteotomy
· shaft should be displaced medially
· so that mechanical axis continues to pass through knee
· valgus intertrochanteric osteotomy
· shaft should be displaced laterally
· avoid true lengthening
· to prevent increasing muscle forces across joint
Indications
· coxa valga
· abduction contracture
· range of abduction at least equal to degree of desired correction
· lateral overloading
· improved congruity with hip in maximum abduction
Technique
· lateral opening or medial closing or combination
· medial displacement of shaft
· internal fixation with 90o blade-plate
Effect
· relaxation of abductors, adductors and psoas
· unloading of hip joint
· increase in weight-bearing surface
· mechanical axis maintained
· medial closing may cause
· Trendelenburg gait
· shortening of limb
· prominence of greater trochanter
Indications
· adduction contracture
· range of adduction at least equal to degree of desired correction
· severe OA with medial osteophytes
· improved congruity with hip in maximum adduction
Effect
· inferomedial osteophyte brought into weight-bearing position
· inferior cervical osteophytes contact acetabular floor osteophytes
· superolateral joint space widens because of fulcrum effect
· lever arm of body weigh decreases
· improvement of congruity of hip joint
Indications
· anterior uncovering of femoral head
· excessive femoral anteversion
· fixed flexion contracture
Effect
· improved anterior covering of femoral head
· elimination of fixed flexion contracture
Indications
· severe SUFE
Technique
· flexion and derotation
Effects
· extension deformity corrected
· femoral shaft perpendicular to physis
Indications
· localised involvement
· sum of arcs of involvement on AP and lateral < 200o
· significant improvement with osteotomy
· normal bone on weight-bearing area > 50o
Technique
· varus or valgus depending on location of disease
· varus for superior disease
· valgus for central disease
· redirect pelvis into more appropriate position
· include
· single, double and triple innominate osteotomies
· spherical osteotomy
· for severely incongruous hips
· include
· shelf
· Chiari