PRINCIPLES OF DEFORMITY CORRECTION

Prepared by: Supervised by:Dr. Abdullah K. Ghafour Dr. Hamid Ahmed Jaff3rd year IBFMS trainee

Reminders

frontal plane-mechanical frontal plane-anatomical sagittal plane-anatomical

Introduction Deformity: It’s the position of a limb/Joint, from

which it cannot be brought back to its normal anatomical position.

Described as abnormalities of : Length Angulation Rotation Translation Combination

Introduction Evaluation of Deformity:

History Clinical examination Radiological Examination

X-rays o Long films (51 Inches)o Frontal plane (AP view)o Sagittal plane (Lateral view)

CT Scanso CT Scanogram

Malalignment refers to the loss of collinearity of the hip, knee, and ankle in the frontal plane.

Therefore, if the MAD exceeds the normal range, there is malalignment

Frontal plane MAD may arise from four anatomic sources:1. femoral frontal plane deformity2. tibial frontal plane deformity3. frontal plane knee joint laxity4. femoral or tibial condylar

deficiency.

Malalignment and Malorientation

Malalignment and Malorientation

Paley and Tetsworth (1992) designed a malalignment test (MAT) to identify the source(s) of the MAD. MAT identifies only which bone or joint source contributes to the MAD that is measured. It does not identify the level of deformity in the femur or tibia

Steps of MAT: Step 0: Measure the MAD

normal range is 1-15 mm medial Varus > 15mm – 1mm< valgus

Step 1: Measure the mLDFA normal range is 85°-90° outside the normal range femur

is contributing to the MAD. Varus > 85° - 90° < valgus

Malalignment and Malorientation

Step 2: Measure the MPTA normal range is 85°-90° outside the normal range tibia

is contributing to the MAD. Valgus > 85° - 90° < varus

Step 3: Measure the JLCA normal range is 0°_2° medial Medial JLCA > 2° means varus lateral JLCA > 2° means valgus outside the normal range loss

of cartilage height and ligamentous laxity is contributing to the MAD.

Malalignment and Malorientation Addendum 1: Rule Out

Knee Joint Subluxation

Compare the midpoints of the femoral and tibial knee joint orientation lines.Normally, they should be within 3 mm of each other.

Malalignment and Malorientation Addendum 2: Rule Out Condylar

Malalignment

Compare the joint lines of the medial and lateral plateaus with each other. They should be collinear.Comparethe lines tangential to the medial and lateral femoral condyles. They should be collinear.

Malalignment and Malorientation Malorientation of the ankle

or hip joints usually leads to minimal or no MAD because the deformity apex is at or near the ends of the mechanical axis of the lower limb.

Ankle joint orientation assessed by measuring mLDTA and aLDTA.

Hip joint orientation assessed by measuring mLPFA, aMPFA and aMNSA.

center of rotation of angulation When a bone is divided and

angulated, the mechanical and anatomic axes of the bone are also divided into proximal and distal segments.

The pairs of proximal and distal axis lines intersect to form an angle, this point is called the center of rotation of angulation (CORA).

center of rotation of angulation CORA Method:

Step 0: malalignment test (MAT)Step 1: draw PAA and PMAStep 2: draw DAA and DMAStep 3: Decide whether this is uniapical or multiapical angulation:mark the CORA(s), and measure the magnitude(s)

Sagittal Plane Deformities the sagittal plane alignment of the hip,

knee, and ankle changes with normal knee motion and gait.

The line from the center of rotation of the hip to the center of rotation of the ankle is the mechanical axis of the lower limb in the sagittal plane.

With the knee in full extension, it passes anterior to the center of rotation of the knee joint while it become collinear at approximately 5°_10° of knee flexion

Sagittal Plane Deformities Knee malalignment in the sagittal

plane is better tolerated than in the frontal plane because all three joints move in the sagittal plane and can therefore compensate for sagittal malalignment.

Flexion malalignment is present when the mechanical axis of the lower limb does not pass anterior to the center of rotation of the knee in maximum extension.

Extension malalignment is present when the knee can be hyperextended passively more than 5°

Sagittal Plane Deformities Knee Joint Malorientation: The joint

orientation of the distal femur and of the proximal tibia is measured to the adjacent anatomic axis line by using PDFA (83±4°) and PPTA (81 ±4°).

PDFA < 79°, there is overall procurvatum deformity of the distal femoral joint line

PDFA > 87°, there is overall recurvatum deformity of the distal femoral joint line

Knee Joint Malorientation:

PPTA < 77°, there is overall procurvatum deformity of the proximal tibial joint line.

PPTA > 85°, there is overall recurvatum deformity of the proximal tibial joint line.

Sagittal Plane Deformities

Sagittal Plane Deformities Hip Joint Malorientation:• The aPPFA is normally 90°.• The anterior NSA (ANSA) is

normally 170±5°. • The proximal and distal mid-

diaphyseal lines of the femur intersect in the mid-femur. The normal (MDA) is approximately 10°.

Sagittal Plane Deformities Ankle Joint Malorientation: Draw the distal mid-

diaphyseal line of the tibia, and measure the ADTA. If the ADTA is less than 78° or greater than 85°, there is malorientation of the ankle joint line relative to the DAA line.

CORA in sagittal plane Step 1:Draw the mid-diaphyseal line(s) to

represent the diaphysis of the bone. Step 2:Decide whether the joint orientation angles

are normal (PPTA,ADTA) foe tibia and PDFA for femur.

Step 3:Decide whether this is uniapical or multiapical angulation. Mark the CORA(s) and measure the magnitude(s)

Oblique Plane Deformities The apical direction of an oblique plane

angulation is either anterolateral, anteromedial, posterolateral, or posteromedial.

If a radiograph could be obtained exactly perpendicular to the oblique plane, the magnitude could be measured directly.

Oblique Plane Deformities Knowing the magnitudes of

angulation measured off the AP and LAT radiographs, the magnitude of the true angulation in the oblique plane can be calculated by:

=

Translation Deformity Translation deformity refers to displacement

deformity. It occurs secondary to fractures and osteotomies.

Translation deformity parameters: (a) plane, (b) direction, (c) magnitude, and (d) level.

Osteotomy Concepts There are two basic osteotomy types for angular

deformity correction: 1. angulation-only osteotomies

opening wedge closing wedge

2. angulation with translation osteotomies. circular cut (dome) Oblique cut

The axis line around which the correction is performed is the Angulation Correction Axis (ACA)

Osteotomy Concepts A line passing through the CORA dividing the

transverse angle into two equal parts is called the transverse bisector line (tBL)

Each point on tBL line can be considered a CORA When the ACA passes through CORA the point is called an ACA-CORA

Osteotomy Concepts Osteotomy Rules: Osteotomy rule 1: When the osteotomy

and ACA pass through any of the CORAs, realignment occurs without translation.

Osteotomy Concepts Osteotomy Rules: Osteotomy rule 2: When the ACA is

through the CORA but the osteotomy is at a different level, the axis will realign by angulation and translation at the osteotomy site.

Osteotomy Concepts Osteotomy Rules: Osteotomy rule 3: When the

osteotomy and ACA are at a level above or below the CORAs the proximal and distal axes of the bone will be parallel but translational deformity will result.

Osteotomy types Opening Wedge Osteotomy: The CORA and ACA lie on the

cortex on the convex side of the deformity.

The cortex on the concave side of the deformity is distracted to restore alignment, opening an empty wedge that traverses the diameter of the bone.

Opening wedge osteotomy increases final bone length.

Osteotomy types Closing Wedge Osteotomy: The CORA and ACA lie on the

concave cortex of the deformity. The cortex on the convex side

of the deformity is compressed to restore alignment, requiring removal of a bone wedge across the entire bone diameter.

A closing wedge osteotomy decreases final bone length.

Osteotomy types Neutral wedge osteotomy: The CORA and ACA lie in the middle of the bone. The concave side cortex is distracted and the

convex side cortex is compressed. A bone wedge is removed from the convex side. Neutral wedge osteotomy has no effect on final

bone length.

Osteotomy types Focal Dome Osteotomy: The osteotomy is a cylindrical

shaped cut in three dimensions .

the osteotomy site cannot pass through both the CORA and the correction axis. Thus, translation will always occur when using a dome osteotomy.

Translation deformity correction Translational deformities may be

corrected in one of three ways. Transverse cut osteotomy:

Oblique cut osteotomy:

Multiple osteotomies:

a b

Length discrepancy correction Acute distraction or

compression methods obtain immediate correction of limb length by acute lengthening with bone grafting or acute shortening, respectively

Gradual correction techniques for length deformities typically use Ilizarov external fixation/ LRS

PRINCIPLES OF DEFORMITY CORRECTION

For more information please read this genius book for (Dr. DROR PALEY).

References • Paley D., Herzenberg J. E. (editorial assistance), [2005] Principles

Of Deformity Correction, 1st ed. 2002. Corr. 3rd printing 2005. by Springer-Verlag Berlin Heidelberg, New York, USA

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• Solomon L., Warwick D. , Nayagam S.,[2010] Apley’s System of Orthopaedics and Fractures, 9th ed. Hodderarnold comp.,London, UK.

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?THANK

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