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Similar to Measurements around knee
Measurements around knee
- 1. Lower Limb Alignment andmeasurements around the Knee Dr Namith Rangaswamy AIIMS New Delhi
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- 3. Position Patella forwards Blocksto correct LLD
- 5. If Patella isdisplaced due to gross deformity The limb can be oriented into a true AP view based on the flexion-extension axis of the knee and without consideration of the position of the patella
- 6. Joint orientation lines Ankle: 1)Frontal plane: drawn across the flat subchondral line of the tibial plafond in either the distal tibial subchondral line or for the subchondral line of the dome of the talus. 2) Sagittal plane: drawn from the distal tip of the posterior lip to the distal tip of the anterior lip of the tibia
- 7. Knee 1) Proximal tibialknee joint orientation line, frontal plane: Connect two points on the concave aspect of the tibial plateau subchondral line. 2) Distal femoral knee joint orientation line, frontal plane: Draw a line tangent to the two most convex points on the femoral condyles. 3) Proximal tibial knee joint orientation line, sagittal plane: Draw a line along the fiat portion of the subchondral bone. 4) Distal femoral joint orientation line, sagittal plane: Connect the two anterior and posterior points where the condyle meets the metaphysis. For children, this is drawn where the growth plate exits anteriorly and posteriorly
- 8. Hip 1) Neck offemur line, frontal plane: Draw a line from the center of the femoral head through the mid-diaphyseal point ofthe narrowest part of the femoral neck. 2)Hip joint orientation line, frontal plane: Draw a line from the proximal tip of the greater trochanter to the center of the femoral head.
- 9. Joint Center Points Hip:center of the circular femoral head, best be identified using Mose circles (Goniometer). Knee Joint: Top of the femoral notch, the midpoint of the femoral condyles, the center of the tibial spines, the midpoint of the soft tissue around the knee, or the midpoint of the tibial plateaus(top of the femoral notch or tibial spines is the quickest) Ankle joint: Measured at the mid-width of the talus, the mid-width of the tibia and fibula at the level of the plafond, or the mid- width of the soft tissue outline (The mid- width of the talus or the plafond is the easiest to use)
- 10. Anatomic axis: Mid- diaphysealline Mechanical axis: Line connecting the joint center points of the proximal and distal joints Parallel to each other
- 11. Joint Orientation Angle •Angle formed between the joint line and either the mechanical or anatomic axis • The angle may be measured medial (M),lateral (L), anterior (A), or posterior (P) to the axis line. The angle may refer to the proximal (P) or distal (D) • The angle formed between joint orientation lines on opposite sides of the same joint is called the joint line convergence angle
- 12. • In thefrontal plane, the distance on the joint line between the intersection with the anatomic axis line and the joint center point is called the anatomic axis to joint center distance (aJCD). • In the sagittal plane, the distance between the point of intersection of the anatomic axis line with the joint line and the anterior edge of the joint is called the anatomic axis to joint edge distance (aJED)
- 13. • Mechanical axisof the lower limb is the line from the center of the femoral head to the center of the ankle plafond. • MAD is the perpendicular distance from the mechanical axis line to the center of the knee joint line. The frontal plane Mechanical Axis Deviation The normal mechanical axis line(MIKULICZ LINE) passes 8 ± 7 mm medial to the center of the knee joint line.
- 14. Intraoperative – Cabletechnique
- 15. Anatomic tibiofemoral angle:Relation between the anatomic axes of the femur and tibia.
- 16. Age wise knee alignment 1-2 years2-7 years 7 and up Varus Valgus Normal alignment (Valgus) Varus orientation of the distal femur Combination of decreasing varus orientation of the distal femur and a mild increase in valgus orientation of the proximal tibia Within the range of reference values that are available for the adult population Sabharwal, Sanjeev & Zhao, Caixia & Edgar, Michele. (2007). Lower Limb Alignment in Children Reference Values Based on a Full- Length Standing Radiograph. Journal of pediatric orthopedics. 28. 740-6. 10.1097/BPO.0b013e318186eb79.
- 17. • normal mLDFAto be 87.5±2SD • MPTA to be 87±2S(Paley et al) • Malalignment Test (MAT) Varus Valgus mLDFA >90* <85* MPTA <85* >90* JLCA(0-2/3*) Lateral laxity, JLCA >2* Medial joint line laxity, JLCA >2* Varus JLCA >2* with lateral subluxation Valgus JCLA > 2° plus lateral subluxation.
- 18. Compare the jointlines of the medial and lateral plateaus with each other. Compare the lines tangential to the medial and lateral femoral condyles. Condylar malalignment Varus Valgus Lateral Femoral con Depressed/Hyp oplastic/angled Med Femoral Condyle Depressed/Hyp oplastic/angled Lateral Tibial Con Depressed/Hyp oplastic/angled Medial Tibial con Depressed/Hyp oplastic/angled
- 19. Center Of RotationOf Angulation (CORA). The point at which the proximal and distal axis lines intersect
- 20. Tibial deformities • Ifthe ipsilateral femur has a normal mLDFA, extend its mechanical axis distally to become the mechanical axis of the proximal tibia • If the ipsilateral mLDFA is not normal but the contralateral MPTA is normal, use the contralateral MPTA to draw the mechanical axis of the proximal tibia. • If the ipsilateral mLDFA and the contralateral MPTA are not normal, use a normal value (87°) for the MPTA.
- 21. Step 2: DrawThe Mechanical Axis Of The Distal Tibia • Draw a line from the midpoint of the tibial plafond parallel to the shaft of the tibia (parallel to the anatomic axis mid-diaphyseal line). Measure the LDTA of the ankle plafond line to this line. • If the shaft of the tibia distal to the deformity is very short and an accurate parallel line cannot be drawn and the opposite LDTA is within normal limits, use it to orient the mechanical axis of the distal tibia. • If the deformity level is very distal and the contralateral LDTA is not within normal limits, use the normal value of 90° to orient the DMA line.
- 22. Step 3 Uni-apical: CORA isat the level of obvious angulation Obtained by extending PMA and DMA Mag: Magnitude of Angulation
- 23. Step 3 • Multiapicalangulation: If the CORA is not at the obvious apex, there is more than one apex of angulation • Draw a third line corresponding to the mechanical axis of the mid-tibia • Mark the two CORAs, and measure the • magnitude of angulation of the two deformities
- 24. Femoral deformities Draw DMA ExtrapolateTibial MA Replicate contralateral mLDFA Draw DMA with supposed normal mLDFA
- 25. Draw PMA 1. Drawa line dropped from center of femoral head parallel to Proximal anatomical axis, measure contralateral AMA and replicate a corresponding line. 2. Create AMA with supposed normal value of 7* 3. Line forming contralateral LPFA or LPFA of 90*
- 26. Mark the CORAat the intersection point of the PMA and DMA lines
- 27. Fujisawa scale F. Point:62.5% of tibial plateau
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- 42. metaphyseal-diaphyseal angle isthe angle created by the intersection of a line through the transverse plane of the proximal tibial metaphysis with a line perpendicular to the long axis of the tibial diaphysis Blounts EMA > 20* MDA > 11*
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- 46. Anterior to theposterior cruciate ligament insertion just at the tip of BL and slightly medial to center of the intercondylar DFN entry
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Editor's Notes
- #10 knee joint is approximately the same using a point at the top of the femoral notch, the midpoint of the femoral condyles, the center of the tibial spines, the midpoint of the soft tissue around the knee, or the midpoint of the tibial plateaus (~Fig.l-Sb). Using the top of the femoral notch or tibial spines is the quickest way to mark the knee joint center point without measuring the width of the bones or soft tissues. the ankle joint center point is the same whether measured at the mid-width of the talus, the mid-width of the tibia and fibula at the level of the plafond, or the mid-width of the soft tissue outline (~ Fig. l-Sc). The mid-width of the talus or the plafond is the easiest to use.