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Limb Length Inequalities / Growth Deformities

- Discussion:
    - see: limb development and physeal anatomy;
    - leg length discrepancy leads to awkward gait, & pelvic obliquity.
    - treatment of limb length inequality, requires an ability to predict leg length discrepancy at skeletal maturity;
    - differential diagnosis of limb length inequality
    - definitions:
           - amelia: limbs may fail to develop or may be represented by mere stubs;
           - hemimelia:
                  - translated means "half limb"
                  - distal portion of limb may fail to develop & may taper to stump, while the proximal portion develops normally;
                  - paraxial hemimelia: either the preaxial or postaxial portions of the limb remain;
                          - examples: tibial hemimelia vs fibular defectsfibular hemimelia;
           - phocomelia: proximal portion of limb is deficient, w/ hand or foot appearing to project directly from trunk;
           - terminal deficiency:
                  - transverse: complete transverse terminal amputation;
                  - paraxial deficiency: there is complete deficiency of either the preaxial or the postaxial portion of the limb;
           - intercalary deficiency:
                  - transverse: complete absence of middle segment of limb w/ retention of distal portion of limb;
                  - paraxial: absence of the middle segment of either the preaxial or postaxial limb;
    - specific conditions:
           - congenital causes:
                  - proximal femoral focal deficiency
                  - paraxial tibial hemimelia
                  - tibial bowing
                  - congenital deficiency of tibia:
                  - fibular defects
           - traumatic causes:
                  - bone bridge
                  - pediatric hip and femoral fractures 
                        - distal femoral physeal fractures 
                        - proximal tibial physeal frx 
    - methods to estimate growth potenital:
           - mosely straight line
           - distal femoral physis:
           - proximal tibial epiphysis:
           - multiplier method:

- Exam:
    - be sure to rule out scoliosis, pelvic obliquity, and joint (hip, knee, ankle) contracture;
    - each of these can give the false sense of leg length inequality;
    - have the child stand on pre-measured blocks and reassess any scoliosis or pelvic obliquity; 
    - impairment: (impairment to whole leg)
          - 1/2 inch = 4%
          - 1 inch = 8%
          - 1 1/2 inch = 16%
          - 2 inch = 24%
          - 2 1/2 inch = 32%
          - 3 inch = 40%

- Radiographs:
    - orthoroentgenogram:
           - single exposure long cassette, with a standardized distance between x-ray tube to cassette;
    - scanogram:
           - several exposures are taken over a single cassette;
           - eliminates magnification error but child must be able to sit still; 
           - indicated for knee flexion contracture;
    - ref: Methods for Assessing Leg Length Discrepancy.

- Treatment:
    - aim of treatment is to ensure discrepancy < 1.2 cm at skeletal maturity.
    - descrepancy < 1.2 cm;
          - those projected at 1.2 cm or less do not require intervention.
    - descrepancy between 1.2 - 2.5 cm;
          - this is the grey zone, and treatment is controversial;
          - patients will often compensate for the leg length inequality thru increased flexion and circumduction of the long extremity and
                  thru toe walking of the short limb;
          - as observed by Gross (Orthopedics, 1978), adults w/ leg length descrepancy less than 2 cm were generally asymmptomatic and
                   only 10% required a shoe lift;
          - patients with weakness of hip abductors or lower limb paralysis will not compensate for leg length descrepancy as well as
                   patient with normal motor strength;
    - descrepancy > 2.5 cm;
          - most agree that all discrepancies projected to be > 2.5 need treatment;
          - limb lengthening:
          - procedures to shorten the longer limb
          - surgery on growth plates
                - bone bridge
          - amputation:
                - amputation may be considered for severe lower extremity limb length descrepancies in which there is little or no possibility
                           that the shortened extremity will have acceptable function

Developmental patterns in lower-extremity length discrepancies.

Closed intramedullary osteotomies of the femur.

Straight-line graphs for the prediction of growth of the upper extremities.

Evaluation of Physeal Behavior in Response to Epiphyseodesis with the Use of Serial Magnetic Resonance Imaging.

Opening-Wedge Osteotomy for Angular Deformities of Long Bones in Children.

Normal limits of knee angle in white children--genu varum and genu valgum.

Partial physeal growth arrest: treatment by bridge resection and fat interposition.

Congenital abnormalities of the femur and related lower extremity malformations: classification and treatment.  

Rotational osteotomy for proximal femoral focal deficiency

Does unequal leg length cause back pain? A case-control study.

Congential skeletal deficiencies of the extremities: classification and fundamentals of treatment.   

Leg length discrepancy: how much is too much?   

Longitudinal limb deficiencies and the sclerotomes. An analysis of 378 dysmelic malformations induced by thalidomide

Need for Concomitant Proximal Fibular Epiphysiodesis When Performing a Proximal Tibial Epiphysiodesis.

Leg Length Inequality and Epiphysiodesis: Review of 96 Cases.

The new intramedullary cable bone transport technique.