lower limb deficiencies

Proximal focal femoral deficiency

Definition

· congenital malformation characterized by failure of normal development of the proximal part of the femur

epidemiology

· rare (1 in 50 000)

· bilateral in 15%

· usually severe form

· associated with fibular hemimelia in 2/3

· may also be associated with

· talipes equinovarus

· cleft palate

· CDH

· spinal deformity

Classification

· Aitken's classification

Class A

· head of femur present

· adequate acetabulum

· short femoral shaft

· may be coxa vara

· bony connection between head and neck present at maturity

· may be pseudarthrosis at point of connection

Class B

· head of femur present

· adequate acetabulum

· short femoral shaft with small bony tuft on proximal end

· no osseus connection between head and neck

Class C

· no femoral head or represented by ossicle

· acetabulum severely dysplastic

· short femoral shaft with bony tuft proximally

Class D

· femoral head and acetabulum comletely absent

· femur consists of condyles only

Clinical

Presentation

· short involved thigh segment

· characteristic posture

· flexed, abducted and externally rotated hip

· ship's funnel sign of thigh segment

· bulky upper sharply tapering to knee

· knee usually flexed but can be extended

Problems

· instability of the hips

· malrotation

· leg length

· inadequate proximal musculature

treatment

General

Class A & B

· have femoral heads present

· often can be treated with

· limb lengthening

· hip stabilization

Class C & D

· effectively have no femoral heads

· usually require

· amputation

· prosthesis

Unilateral

· can sometimes ambulate in prosthesis

· poor cosmesis

· best results with surgery

· conversion to AKA or BKA

· need to predict eventual leg length discrepancy

· if foot will lie proximal to unaffected knee

· ablate foot as Symes

· AKA prosthesis to stump

· if foot will lie distal to unaffected knee

· van Ness rotational osteotomy with resection of bone to bring ankle to level of unaffected knee

· foot functions as knee joint for BKA stump

· usually require knee arthrodesis

· performed when growth potential achieved

Bilateral

· usually class C and D

· can usually walk well without prosthesis

· surgical procedures usually detract from mobility

· should not be treated surgically unless

· such severe foot deformity that cannot ambulate without prosthesis

Specific

Class A

· equalise leg length

· lengthen femur (up to 6”) OR

· shorten and epiphyseodese opposite femur

· realign coxa vara

· subtrochanteric osteotomy

Class B

· realign and form single skeletal lever

· fuse pseudarthrosis and knee with IM nail

· then perform Symes or van Ness amputation

· then apply prosthesis

Class C

· as above but no pelvifemoral stability

Class D

· only in unilateral cases

· fusion of femur to pelvis at 90^o

· uses knee as hip joint

· van Ness rotationplasty to produce knee

Paraxial fibula hemimelia

definition

· deficiency of bony elements on lateral side of lower limb

· may be

· terminal (abnormal foot)

· intercalary (normal foot)

epidemiology

· most common congenital deficiency of long bones

· M:F 2:1

· may be associated with PFFD

pathology

· usually some femoral shortening

· usually some hypoplasia of lateral femoral condyle

· tibia markedly shortened and bowed anteromedially

· lateral tarsal bones fused or absent

· absence of one or more lateral rays

Clinical

Presentation

· leg short

· bowed anteromedially

· skin dimple over apex of bow

· foot in equinus

· varus or valgus

· absence of one or more lateral rays

· if terminal cf. intercalary

Problems

· leg length discrepancy

· usually 5”

· usually worse with intercalary defect (normal foot)

· foot deformity

· tibial bowing

· least important

· usually corrects

treatment

Reconstruction

· soft tissue procedures for foot

· to place foot beneath tibia

· leg length equalisation

· lengthening

· epiphyseodesis of unaffected limb

· usually not indicated

· poor results

Salvage

· early ablation with Symes amputation

· below knee prosthesis

Paraxial tibial hemimelia

definition

· deficiency of skeletal elements on medial aspect of lower limb

epidemiology

· only skeletal deficiency with a documented familial occurrence

· autosomal dominant

· associated with

· lobster hand

· reduplication of toes

· CDH (20%)

· bilateral in 30%

clinical

Presentation

· leg markedly shortened

· anterolateral bowing

· foot fixed in severe varus

· sole facing perineum

· may be flexion contracture of knee

· terminal

· absence of one or more of medial rays of foot

· intercalary

· foot normal or more than five rays present

Problems

· severe shortening

· malrotation of foot

· instability and contracture of knee

treatment

· often best to manage with

· foot ablation

· prosthesis

· can sometimes centralise upper end of fibula beneath femur first