principles of deformity correction

Principles of Deformity Correction

Dr Ankit MadhariaJunior ResidentNKPSIMS & RC

Deformity • Definition:

• It’s the position of a limb/Joint, from which it cannot be brought back to its normal anatomical position.

Deformity • Described as abnormalities of

• Length• Angulation• Rotation• Translation

• The location, magnitude, and direction of the deformity complete the characterization of a bony deformity

Evaluation of Deformity• Clinical Examination• Radiological Examination

• Xrays • CT Scans

Evaluation of Deformity : X Rays• Radiographs of the lower limbs:• Long films (51 Inches)• Frontal plane (AP view)(Patella Forward)

Sagittal plane (Lateral view)

Evaluation of Deformity : X Rays• Radiographs of the lower limbs:• Long films (51 Inches)• Frontal plane (AP view)(Patella Forward)

Sagittal plane (Lateral view)

Evaluation of Deformity : X Rays• Radiographs of the lower limbs:• Long films (51 Inches)• Frontal plane (AP view)(Patella Forward)

Sagittal plane (Lateral view)

Evaluation of Deformity : X Rays• Radiographs of the lower limbs:• Long films (51 Inches)• Frontal plane (AP view)(Patella Forward)

Sagittal plane (Lateral view)

Square the Pelvis in case of Limb Length discrepancy

Evaluation of Deformity : CT Scan• CT Scanogram

AXIS

• Each long bone has 2 axis :-Mechanical axisAnatomical axis.

MECHANICAL AXIS• Straight line connecting the joint

center points of the proximal & distal joints.

• Its always a straight line whether in frontal or sagittal plane.

ANATOMICAL AXIS• Is mid diaphyseal line.• In a normal bone, the

anatomic axis is a single straight line.

• In a malunited bone with angulation, each bony segment can be defined by its own anatomic axis

Limb Alignment• It involves assessment of the frontal

plane mechanical axis of the entire limb rather than single bones

Limb Alignment• Mechanical axis deviation (MAD) is measured

as the distance from the knee joint center to the line connecting the joint centers of the hip and ankle.

• Normally, 1 mm to 15 mm medial to the knee joint center.

Joint Orientation Lines• Line representing the orientation of a joint

in a particular plane /projection.• ANKLE Frontal : along the flat subchondral line of

tibial plafond.Sagittal : line from distal tip of posterior lip

to tip of anterior lip.

Joint Orientation Lines• Knee: • FRONTAL : along the subchondral line of

tibial plateau.• Line tangential to most distal point on the

femoral condyle.

• SAGITTAL : along flat subchondral line of plateau.

Line connecting 2 points where the condyles meet the metaphysis.

Joint Orientation Lines• Hip:• FRONTAL : from tip of greater trochanter to

center of femoral head.• Also from the centre of femoral head along

the anatomical axis of the femoral neck

• The relation between anatomical or mechanical axes and the joint orientation lines can be referred to as joint orientation angles

Joint Orientation Angles

Centre of Rotation of Angulation (CORA)

• The intersection of the proximal axis and distal axis of a deformed bone is called the CORA , which is the point about which a deformity may be rotated to achieve correction.• Either Anatomical or Mechanical axis can

be used to identify CORA.

Centre of Rotation of Angulation (CORA)• Correction of angulation by rotating the bone

around a point on the line that bisects the angle of the CORA (the “bisector”) ensures realignment of the anatomic and mechanical axes without introducing an iatrogenic translational deformity.

• All points that lie on the bisector can be considered to be CORAs because angulation about these points will result in realignment of the deformed bone

Evaluation of the Various Deformity Types

• Length• Clinically• Radiologically

Evaluation of the Various Deformity Types

• Angulation• Characterized by Magnitude and direction of apex• Identification of the CORA is key in characterizing

angular deformities and planning their correction• Angulation can be in Frontal plane or in sagittal

plane or in oblique plane

Evaluation of the Various Deformity Types

• Angulation

Evaluation of the Various Deformity Types

• Rotation• Clinically• Radiologically

• Axial CT scans• Characterised by

• Position• Magnitude

Evaluation of the Various Deformity Types• Translation

• Clinically• Radiologically

• Axial CT scans• Characterised by

• Plane• Direction• Magnitude • Level

Treatment• Following evaluation, the deformity is characterized by its

• type (length, angulation, rotational, translational, or combined), • the direction of the apex (anterior, lateral, posterolateral, etc.), • the orientation plane, • It’s magnitude, • and the level of the CORA

Osteotomies• An osteotomy is used to separate the deformed bone

segments to allow realignment of the anatomic and mechanical axes.

• The ability of an osteotomy to restore alignment depends on • location of the CORA• Axis about which correction is performed (the correction axis), • Location of the osteotomy

Results when using osteotomy

A.The CORA, the correction axis, and the osteotomy all lie at the same location; the bone realigns through angulation alone, without translation.

B.The CORA and the correction axis lie in the same location but the osteotomy is proximal or distal to that location; the bone realigns through both angulation and translation.

C.The CORA lies at one location and the correction axis and the osteotomy lie in a different location; correction of angulation results in an iatrogenic translational deformity.

Wedge osteotomy• The type of wedge osteotomy is determined by the

location of the osteotomy relative to the locations of the CORA and the correction axis

Wedge osteotomy

A.Opening wedge osteotomy.

• The CORA and correction axis 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.

Wedge osteotomyB. Neutral wedge osteotomy.

• The CORA and correction axis 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.

Wedge osteotomies

C. Closing wedge osteotomy.

• The CORA and correction axis 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.

Dome Osteotomy• In a dome osteotomy, the osteotomy site

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

Dome Osteotomy

Ideally, the CORA and correction axis are mutually located with the osteotomy proximal or distal to that location such that the angulation and obligatory translation that occurs at the osteotomy site results in realignment of the bone axis.

Dome Osteotomy

When the CORA and correction axis are not mutually located, a dome osteotomy through the CORA location results in a translational deformity.

Dome osteotomy

the CORA and correction axis are mutually located with the osteotomy distal to that location in all of these examples.

A.Opening dome osteotomy.The CORA and correction axis lie on the cortex on the convex side of the deformity.

Opening dome osteotomy increases final bone length.

Dome osteotomy

B. Neutral dome osteotomy.

The CORA and correction axis lie in the middle of the bone.

Neutral dome osteotomy has no effect on final bone length..

Dome osteotomy

C. Closing dome osteotomy.

The CORA and correction axis lie on the concave cortex of the deformity.

A closing dome osteotomy decreases final bone length

It can result in significant overhang of bone that may require resection

Treatment By Deformity type : Length• 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

Treatment By Deformity type : Angulation• Correction of angulation deformities involves making

an osteotomy, obtaining realignment of the bone segments, and securing fixation during healing.

• Alternatively, the correction may be made gradually using external fixation to both restore alignment and provide stabilization during healing

Treatment By Deformity type : Rotation• Correction of a rotational deformity requires an

osteotomy and rotational realignment followed by stabilization.

Treatment By Deformity type : Translation• Translational deformities may be

corrected in one of three ways.

Thank you