Ki Hyuk Sung, MD

Amount of correction after calcaneal lengthening for planovalgus foot

deformity in patients with cerebral palsy

Seoul National University Bundang Hospital

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Introduction

• Planovalgus foot deformity is common in patients with cerebral palsy

• A complex 3-D malalignment– hindfoot valgus, plantar flexed talus– midfoot planus and pronation– relatively short lateral column– forefoot abduction and supination

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Introduction

• Medial callosities

• Hallux valgus

• Shoe wear

• Pain

• Gait disturbance due to lever arm dysfunction

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Introduction

• Surgical options

– medial displacement osteotomy of calcaneus

– subtalar extra-articular arthrodesis

– lengthening of the lateral column

– triple arthrodesis

• Calcaneal lengthening osteotomy

– most commonly used to correct the deformity

and not sacrifice joint motion in patients with CP

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Introduction

• Additional procedures, such as, medial soft tissue

procedure, medial bony procedure, or triple

arthrodesis could be performed concomitantly with

calcaneal lengthening depending on severity of

deformity.

• However, there has been no guideline to determine

the necessity of these procedures

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Purpose of the study

• To investigate the amount of correction

after calcaneal lengthening for the

treatment of planovalgus foot deformity in

patients with CP

• To guide a surgical indication in terms of

the severity of the foot deformity

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Materials and Methods

• Retrospective design

• Inclusion

– patients with cerebral palsy who underwent

calcaneal lengthening for planovalgus deformity

between 2003 and 2011

– patients who had preop and postop weight bearing

AP and lateral foot radiographs

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Materials and Methods

• Exclusion

– patients who had concomitant medial column

procedures with calcaneal lengthening

– patients with a history of previous foot surgery

– patients with inadequate foot radiographs for

measurement

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Radiographic measurement

• Lateral foot weight bearing radiograph

– Calcaneal pitch angle

– Lateral talocalcaneal angle

– Lateral talus-first metatarsal angle

– Naviculocuboid overlap

– Relative calcaneal length

– Calcaneocuboid subluxation

• Anteroposterior foot weight bearing radiograph

– Anteroposterior talus-first metatarsal angle

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Calcaneal pitch angle

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Lateral talocalcaneal angle

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Lateral talus-first metatarsal angle

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Naviculocuboid overlap (B/A)

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Relative calcaneal length (a/b)

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Calcaneocuboid subluxation

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AP talus-first metatarsal angle

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Operative procedure

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`

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• Corrected group

– a group of patients whose radiographic indices

improved beyond the value of normal alignment

after calcaneal lengthening

• Under-corrected group

– a group of patients whose radiographic indices

did not reach the value of normal alignment

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Reliability of radiographic measurement

• Inter-observer reliability (3 observer)

• 36 radiographs

• ICC (intraclass correlation coefficient) &

95% confidence interval

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Statistical analysis

• Comparison between preop radiographic

measurement and postoperative measurement

– Paired t-test

• Define the cut-off values of the preop radiographic

measurements between the corrected and the

under-corrected group

– ROC curve

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Results

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Table 1. Patients demographics and surgical procedures

Gender (M / F) 51 / 24

Age (year) 11.0±5.2 (range 5.4 to 30.1)

Geographic type (hemiplegia/diplegia/triplegia/quadriplegia)

5 / 48 / 3/ 19

Follow-up duration (year) 3.1±2.2 (range 0.3 to 8.4)

Calcaneal lengthening (bilateral/ unilateral) 54 / 21

Number of surgical procedures per patient 6.7 ± 3.0 (range 2 to 14)

Data are presented as mean ± SD

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Table 2. Inter-observer reliability of radiographic parameters

Radiographic parameters ICC 95% CI

AP talus-1st metatarsal angle 0.736 0.595 to 0.844

calcaneal pitch angle 0.918 0.864 to 0.954

Lateral talocalacneal angle 0.722 0.521 to 0.848

Lateral talus-1st metatarsal angle 0.793 0.641 to 0.887

Naviculocuboid overlap 0.915 0.859 to 0.953

Relative calcaneal length 0.817 0.709 to 0.895

Calcaneaocoboid subluxation 0.794 0.673 to 0.881

ICC, intraclass correlation coefficient

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Table 3. Change in radiographic measurements after calcaneal lengthening in patients with cerebral palsy

Parameters Preoperative PostoperativeMean

differencep-

valueNormal

alignment

AP talo-1MT (˚) 22.3±11.3 2.4±13.6 19.9±14.4 <0.001 10±7.0

CP (˚) 2.9±8.8 7.3±8.1 -4.4±7.2 <0.001 17±6.0

Lat TC (˚) 47.0±9.5 37.9.±9.2 9.1±8.5 <0.001 49±6.9

Lat talo-1MT (˚) 30.2±15.6 11.6±13.1 18.5±13.8 <0.001 13±7.5

NC overlap (%) 69.0±17.2 37.8±22.1 31.2±22.9 <0.001 47±13.8

Relative calcaneal length 1.9±0.2 2.0±0.3 -0.1±0.3 0.016 -

CC subluxation (˚) 0.2±1.5 1.4±1.9 -1.2±1.8 <0.001 -

AP talo-1MT, anteroposterior talus-first metatarsal angle; CP, calcaneal pitch angle; Lat TC, lateral talocalcaneal angle; Lat talo-1MT, lateral talus-first metatarsal angle; NC overlap, naviculocuboid overlap; CC subluxation, calcaneocuboid joint subluxation.

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Table 4. Cut-off values of the preoperative radiographic measurements between the corrected and the under-corrected group after calcaneal lengthening in patients with cerebral palsy

ParametersNo. of subject

(corrected group)

No. of subject (under-corrected

group)

Area under the ROC curve

95% CI p- valueCut-off value

AP talo-1MT (˚) 54 21 0.729 0.614 to 0.825 0.0001 >23˚

Lat talo-1MT (˚) 45 30 0.754 0.641 to 0.847 <0.0001 >36˚

NC overlap (%) 47 28 0.645 0.526 to 0.752 0.0319 >72%

AP talo-1MT, anteroposterior talus-first metatarsal angle; Lat talo-1MT, lateral talus-first metatarsal angle; NC overlap, naviculocuboid overlap; ROC curve, Receiver Operating Characteristic curve.

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Conclusions

• Calcaneal lengthening with concomitant

peroneus brevis lengthening is the effective

procedure for correcting planovalgus foot

deformity while preserving subtalar joint

motion in patients with cerebral palsy.

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Conclusions

• For the patients with more than 23˚of AP

talus-first MT angle, more than 36˚of Lat.

talus-first MT angle, and more than 72% of NC

overlap, the additional procedures should be

considered due to the possibilities of

insufficient correction with calcaneal

lengthening alone.

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Thank you !