Clean FRCS notes with inline figures
Summary of PE:
•1. Describe LLD
•2. Look for site of LLD (supra or infrapelvic, below or above knee)
•3. Pick up signs that may point to the underlying cause
•4. Any compensatory mechanism / complication of long leg
•5. Assess for skeletal maturity
What are the problems associated with LLD?
•Deformity→ increase energy in gait walking, require shoe raise and cosmetic problem, knee pain
•Compensation mechanism→ compensatory scoliosis, pelvic tilting, contralateral hip adduction, knee flexion and ipsilateral equinus deformity, OA hip
What kinds of imaging available for LLD measurement?
| Type / group | Definition / note |
|---|---|
| X | rays |
•Tele-radiograph (single film, single exposure): single exposure but inaccurate measurement due to parallax of XR beam
•Ortho-radiograph (single film, 3 exposure): 3 exposure over hip, knee and ankle to give more accurate measurement but require co-operative patient (hold still)
•Scanogram (separate film, 3 exposure) with ruler fixed on XR, avoid magnification
•CT scanogram: Especially used for angular deformity → accurate measurement
•For LLD, can ask for either standing or supine film. For standing film, you need to assess the joint line and rotational alignment which can mask LLD.
•Details of LLD prediction
•Overall assumption: Shapiro 1 pattern
•SINGLE VISIT
•Paley multiplier
•Prediction based on multiplying current discrepancy by a sex and age specific factor
•Adv: applicable in first visit, most accurate in type I growth patter
•Disadv: Use chronological age
•Simplistic
•MULTIPLE VISITS
•Menelaus Arithmetic method→ assume that.....
•Physis closure for boy at 16 and girls at 14
•Proximal femur 3mm/year, Distal femur 9mm/year and Proximal tibia 6mm/year (rule of thumb) distal tibia 5mm/year → growing spurt (3965)
•Inhibition is calculated by discrepancy of LLD between 2 visit.
•→ Future Discrepancy = current discrepancy + (Growth remaining in the long leg x inhibition)
•Adv: more applicable in clinical setting, most accurate towards end of growth
•Disadv: uses chronological age, not accurate for early projection
Green and Anderson growth remaining:
•Data is from American children in 1950s with reference to skeletal age (Greulich Pyle)
•Based on skeletal age and uses growth percentiles of the child to predict the future growth
2 graphs:
•Leg length graph: Skeletal maturity with growth percentile
•Growth remaining graph: Differential growth for tibial and femur, predict effect of epiphysiodesis
Adv:
•Uses skeletal age
•Takes into account growth percentile
Disadv:
•2 set of graphs
•Complex
•Heavy reliance on skeletal age
•Not for lengthening, for epiphysiodesis only
•Data from single population
•Moseley graph
Adv:
•Uses skeletal age
•Accounts for the Difference between skeletal and chronological age
•Prediction for both epiphysiodesis and lengthening
Disadv:
•Complex
•Assumption of linear growth pattern