Deformity correction

transcript

Correction of Lower Limb Deformity

Dr. J. Rawat

Source

DiagnosticDiagnostic

Radiographs of the lower limbs:Long filmsFrontal plane (AP view)(Patella Forward) Sagittal plane (Lateral view)

In case of Severe Rotational DeformityHip Forward view(AP Femur)

Patient with LLD

Square the pelvis

DiagnosticDiagnosticAP view standing radiographs

Long LAT view radiograph

Deformity of the lower limb (Frontal Plane)

MMechanical AAxis DDeviation (MAD)

Malalignment

AXIS (mechanical + anatomical)

• Mechanical Axis of the Lower Limb.

• Mechanical Axis of Femur.• Anatomical Axis of Femur.

(7degrees to AA)• Mechanical Axis =

Anatomical Axis of Tibia.• If 1 limb is normal used as

guide for correction.

MAT (Malalignment Test)MAT (Malalignment Test)

Analyzing of

the cause or

the locationof

the malalignment !

Step:1Measurement of the MAD

Mechanical Axis Deviation

>15 mm medial< 1 mm lateral

Mechanical Axis

Source of MAD (Varus)

• Varus: Bony Malalignment Tibia vara (MPTA<85) Femoral Valgus Deformity(LTFA >90) Combination• Joint Surface Malalignment Depressed or deficient Lateral Tibial Plateau Depressed or deficient Lateral Femoral Condyl• Ligamentocapsular (interosseous) Malalignment Lateral Joint Laxity Medial Tibial Subluxation

Source of MAD (Valgus)

• Varus: Bony Malalignment Tibia valga (MPTA>90) Femoral Varus Deformity(LTFA <85) Combination• Joint Surface Malalignment Depressed or deficient medial Tibial Plateau Depressed or deficient medial Femoral Condyl• Ligamentocapsular (interosseous) Malalignment Medial Joint Laxity Lateral Tibial Subluxation

Source of MAD (Valgus)

Step: 2. Measurement of the LDFALDFA= llateral ddistal ffemur aangleusing the mechanical and anatomical axises.

MAT (Malalignment Test)MAT (Malalignment Test)(Step 2 Contd.)

Measurement of the LDFALDFA= llateral ddistal ffemur aangle

< 85° LDFA = Valgus deviation> 90° LDFA = Varus deviation

of the femur

Step: 3. Measurement of the MPTAMPTA

= mmedial pproximal ttibia aangle

Step 3 contd.Measurement of the MPTAMPTA

= mmedial pproximal ttibia aangle

> 90°MPTA = Valgus deviation< 90°MPTA = Varus deviation

of the tibia

Step: 4. Measurement of the JLCAJLCA

= jjoint lline ccovergence aangleNormal= 0-2 degrees

Medial JLCA >2°: - lateral ligament hyperlaxity - medial loss of cartilageLateral JLCA >2°: - medial ligament hyperlaxity - lateral loss of cartilage

MAT ( Malalignment Test)MAT ( Malalignment Test)

•Malorientation of / around knee will change the MADand MAT will be abnormal.

•MalorientationMalorientation in the hiphip and ankle will cause no/minimalankle will cause no/minimalchange in the MADand MAT may be normal.change in the MADand MAT may be normal.

Malorientation-Test (MOT)Malorientation-Test (MOT)for ankle and hipfor ankle and hip

Malorientation-Test Malorientation-Test (MOT)(MOT)

for for a) ankle and b) hipa) ankle and b) hip

Malorientation-Test = MOTMalorientation-Test = MOT

1. Step:Measurement of the LPFA

= lateral proximal femur angle(mechanical)

2. Step:Measurement of the MPFA

= medial proximal femur angle(anatomical)

3. Step:Measurement of the LDTA= lateral distal tibia angle

Sagittal Plane

ANSA = 165 -175AMA= 7degreesMDA(mid diaphysial angle)=10 (Femur)

•Angulation Correction Axis

•Bisector Line

• Femur

Osteotomy rule IOsteotomy rule I

When the Osteotomy line, and ACA pass through the CORArealignment occurs without translation and only angulation is required to correct the deformity.

Osteotomy rule IIOsteotomy rule II

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.

Corollary to Rule IICorollary to Rule II

If osteotomy passes through a different level than the CORA and the axis of correction(ACA) is on the osteotomy line then Translation Deformity will result.

Osteotomy rule IIIOsteotomy rule III

If there is more than one CORA, complete realignment of Mechanical axis and Anatomical axis requires a separate osteotomies for each CORA with seperate Axis of Correction(ACA) for each CORA.

The level and magnitude of one apex determining the level and magniture of the other apex

Corollary to Rule III

If the Osteotomy is done through the Resolution point CORA rather than true multiple apices, then the mechanical axis and joint orientation will correct with a residual alteration in the Anatomical axis of the bone.(This may be a cosmetic problem.)

Conditions when Osteotomy not done at CORA

• If CORA is at Joint Level

• If CORA is at the Epiphysis in Children.

• Skin and Soft tissue Consideration

Isolated Tibial Diaphysial Deformity

• Step 0-Measure MAD • Step1 Draw Mechanical axis of Femur after

conducting MAT,MOT.• Step2 Draw a line from Center of Ankle

Plafond along Anatomical axis ofDistal Tibia.• Step 3 Find CORA and Angle of Deformity

where this line meets the Extended Mechanical Axis of Femur.

Juxta Articular

Tibial Deformity

with a Normal Femur

Diaphiseal Femoral

Deformity

with Normal Tibia

Juxta Articular Femoral deformity with Normal Tibia

Anatomical Axis Method of Preop Planning for Femur

Conditions where Anatomical Axis used for Femur

• Femoral Head deformed so mechanical axis cant be made.

• Severe Rotational deformity of Femur.

• CORA not corresponding to the apparent deformity

Combined Femoral

And Tibial Deformity

in the Absence of Normal Opposite

Level of Osteotomy

CORA not at Apex of

Apparent Deformity

Order of Deformity Correction

• 1st correct the Angular Deformity

• 2nd correct the Length

• 3rd correct the Rotation after the Angulation is Corrected.

• Finally correct Translation

Effect of Rotation on Pre op Planning.

• Tibia Rotation can be corrected through the CORA determined by Previous Method .

• Can Alter Level of CORA in Femur.

• Ext Rot leads to app shortening and Int Rot to app Lengthening of Femoral Neck

Compensating the Rotation

• Clinically determine the Rotation deformity• Xray with the Hip forward position (Knee

rotated)• Measure Distance from Mid Diaphysial line to

Center of head of Femur.• Compare with same distance in Knee forward

film.• Center of Femur head for mechanical axis

line are shifted Medially or Laterally by the same distance

Sagittal Plane

Correction

Sagittal Plane Deformity

• Malalignment Better tolerated.• Compensated for by Hip,Knee,Ankle Subtalar

and Midfoot.• Associated with late degenerative changes. • Malalignment Test• Malorientation Teat• Correction using Anatomical Axis• Soft tissue component of deformity should be

corrected before osteotomy.

Methods to Correct the Deformity

• Osteotomy and Plating

Single Deformity

Metaphysial Correction• Osteotomy and Nailing

Multi level osteotomy

Diaphysial Correction• Fitbone Lengthening also required• Fixators Ring, Taylor Spatial Frame,Monorail

Example for reverse planningExample for reverse planningas described by Reiner Boungartas described by Reiner Boungart

• 15 yo girl originally from Afghanistan.• Known case of Vit. D resistant rickets

Clinical

• Short stature: Ht = 141.2 cmShort stature: Ht = 141.2 cm Wt 42.5 kg

• Has splayed wrists• Pain in the legs off and on.• No knee pain or instability at present.

Mechanical Axis Deviation (MAD)

Lt = 40mm Medial Rt = 33mm Medial Normal = 8+/- 7 mm medial

Mechanical Axis

Femur: Lt = 20°

Rt = 25°

Tibia: Lt = 20°

Rt = 14°

X-ray MeasurementsX-ray Measurements

mLDFA [85 – 90] Lt = 95 Rt = 97

MPTA [85 – 90]

Lt = 78

Rt = 80

JLCA [0 – 2]

Lt = 2

Rt = 1

Measurements ContdMeasurements Contd

mLPFA [85 – 95] Lt = 102 Rt = 105aMPFA [79-89] Lt = 82 Rt = 70aMNSA [125-135] Lt = 128 Rt = 123

Measurements ContdMeasurements Contd

Rt = 90 Lt = 90

[86-92]

Sagittal planeSagittal plane

• ANSAANSA Lt = 165

Rt = 165

Normal = 165-175

• Mid diaphysial Angle (MDA)Mid diaphysial Angle (MDA)

Lt = 15

Rt = 15

Normal = 10

PDFA Lt = 80

Rt = 80

Normal = 79-87

Mid diaphysial Angle (MDA)

Lt = 8

Rt = 10

Normal = 0

ADTAADTA

Rt = 83 Lt = 84

Normal = 78-82

2. Exact planning of the 2. Exact planning of the deformity correctiondeformity correction- operative planning- operative planning

Lengthening of 4cm at the femur

Translation of 4 mm

„Reverse planning“ – technique described by PD Dr. Baumgart in Bangkok November / 2003

Different planning!

Preoperative Planning-BasicsPreoperative Planning-Basics

• At the end of the preoperative planning for leg lengthening, the mechanical axis pass the center of hip, ankle and knee

• Analyze the bone which has to be corrected and mark the center of angulation (CORA)

• Use the mechanical (= anatomical) axis of the tibia as orientation line for the correction, if there is no Tibia deformity (in the follow exmple-both Tibia and Femur-are deformed)

• Be certain, that the mechanical lateral distal femur angle (mLDFA) is within the physiological range (85°-90°) before you start

Draw a target, vertical linetarget, vertical line on tracing paper representing the new mechanical axis and another line crossing at 87°.

Evaluate the knee joint angle line very precisely and place this line on the crossing line, what this means, that knee joint is now orientated under 87° to the mechanical axis

Reverse Planning- Step1Reverse Planning- Step1

Take over the target line representing the new mechanical axis, place the center of the knee joint on this line and continue the line distally.

Mark the center of rotation of angulation (CORA).

Mark the center of the ankle joint CA on this line in correct position according to the opposite length or to the desirable length.

Reverse Planning TibiaReverse Planning TibiaStep 2aStep 2a

This should be the position of the ankle joint at the final result = CA .

Choose an OT level near to the center of CORA in accordance with the locking performance of the nail and draw a transverse line to identify the level.

Reverse Planning TibiaReverse Planning TibiaStep 2bStep 2b

Take an extra sheet and draw the distal part of the tibia ending within the OT-line.

Draw the anatomical axis and the scaled nail borderline according to the diameter of the planned nail. The nail will always center in the diaphysis and simulate by drawing the bone reaming of the curved cortex.

Lengthen the lines proximally out of the fragment.

Reverse Planning TibiaReverse Planning TibiaStep 3Step 3

Take the extra sheet and place the center of the ankle joint exactly on the dedicated center CA which was found in step 2a so that

1. The entry point of the nail has to be near to the middle of the tibia head not damaging any cartilage

2.the lines of the nail coming out of the distal fragment enter the distal frontplane of the proximal tibia fragment at the OT-level

Reverse Planning – TibiaReverse Planning – TibiaStep 4Step 4

Shift the distal fragment upwards along the anatomical axis, because this will be the the reverse actreverse act of lengthening over a nail.

If the frontal planes of both fragments get into contact, mark the new center of the ankle joint CA´ .

The position of the distal tibia fragment now is the postoperative position which is essential to get the exact position after the complete lengthening as planed.

Reverse Planning TibiaReverse Planning TibiaStep 5Step 5

• The exact geometrical position (lat. or med. shift)

• The angle of the frontal planes of the proximal + distal fragment

• The position of the entry point of the nail

Reverse Planning TibiaReverse Planning Tibia

Evaluate

All these landmarks must be exactly achieved intraoperatively visually and controlled on thescreen with the Patella in front.

Take over the vertical target line vertical target line (()) of the tibia representing the mechanical axis, place the center of the knee joint and ankle joint on this line and continue the line proximally as the target line.

Reverse Planning Reverse Planning Step 6Step 6

Mark the center of rotation of angulation (CORA).

Mark the center of the hip joint CH´ on this line in correct position according to the opposite length or to the desirable length.

Reverse Planning FemurReverse Planning FemurStep 7aStep 7a

This should be the position of the hip joint at the final result = CH´ .

Choose an OT level near to the center of CORA in accordance with the locking performance of the nail and draw a transverse line to identify the level.

Reverse Planning Reverse Planning Femur- Step 7bFemur- Step 7b

Take an extra sheet and draw the proximal part of the femur ending with the OT-line.

Draw the anatomical axis and the scaled nail borderline according to the diameter of the planed nail. The nail will always center in the diaphysis. Anatomical variations of the proximal femur such as coxa valga which could be an obstacle for antegrade nailing does not affect your planning for retrograde nailing.

Lengthen the lines distally out of the fragment.

Reverse Planning FemurReverse Planning FemurStep 8Step 8

Take the extra sheet and place the center of the hip joint (CH) exactly on the dedicated center CH´ which was found in step 7b so that

1. The entry point of the nail has to be in the middle of the condyles allowing the entry of a nail without damaging any

cartilage or cruciate ligament

2.the borderlines of the nail coming out of the proximal fragment enter the proximal frontplane of the distal femur fragment at the OT- level

Reverse Planning Femur Reverse Planning Femur Step 9aStep 9a

3. The lateral proimal femur angle (LPFA) should be about 90° preventing an overtention or relaxation of the gluteus muscle –both should be examined clinically

4. After final position of the proximal femur fragment, the exitpoint of the nail at the distal femur fragment is defined and the entry point comes out exactly in the middle of the condyles.

Reverse Planning Femur Reverse Planning Femur Step 9bStep 9b

Shift the proximal fragment downwards along the anatomical axis, because this will be the reverse actthe reverse act of lengthening over a nail.

If the frontal planes of both fragments get into contact, mark the new center of the hip joint CH* .

The position of the proximal femur fragment now is the postoperative position which is essential to get the exact position (=CH´) after the complete lengthening as planed.

Reverse Planning Reverse Planning Femur- Step 10Femur- Step 10

Note: Evaluate...Note: Evaluate...- The exact geometrical position (lat.

or med. shift)

- The angle of the frontal planes of the proximal + distal fragment

- The position of the entry point of the nail

All the landmarks must be exactly achieved intraoperatively visually

and controlled on thescreen with the Patella in front.

Control of the mechanical axis intraoperatively under

Imaging Intensifier with

- grid- radiolucent rulers

on the OT-table!

3. Exact intraoperative control3. Exact intraoperative control

Control of the mechanical axis intraoperatively under

Imaging Intensifier with

on the OT-table!

Control of

mechanical axis

intraoperatively

under Imaging

Intensifier

on the OT-table!

Deformity correction

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