Knee & Foot

Principles

 

Foot

 

A little equinus is better than calcaneus

A little valgus is better than varus

A little varus is better than severe valgus

TA lengthening is most over used operation in CP

 

Knee

 

A little knee flexion is better than recurvatum

 

Knees

 

Problems

 

Tight hamstrings 

- prevents knee extension with hip flexion

 

Often have co-spasticity with tightness of quads 

- unmasked when lengthen hamstrings

- limit the amount of knee flexion in gait 

- result in a stiff knee gait which is very energy inefficient

- i.e. must check Ely's / may need release of RF

 

Jump Gait 

 

Issue

 

Knee flexed / equinus ankle

 

Non-operative Management

 

Botox / physio

 

Operative Management

 

Lengthen hamstrings at the musculotendinous junction

- release the Semitendinosis with tenotomy

- intramuscular recession of Semimembranosus 

- usually leave biceps femoris

- aim for Popliteal angle of 70o

 

Stiff - Knee Gait

 

Spastic rectus femoris can cause limited flexion of knee during swing phase of gait 

- particularly after hamstring lengthening

 

Operative

- Transfer of this to sartorius / SemiT

- release of rectus is just as good

- find plane of tissue under vastus intermedius

 

Tibia

 

Problem

 

Externally rotated tibia

 

Management

 

TDRO / tibial derotation osteotomy

- supramalleolar

- anteromedial approach

- DCP

 

Foot and ankle

 

Problems

 

1.  Equinus

2.  Equinovarus

3.  Valgus

4.  Hallux Valgus

 

Equinus

 

T Achilles lengthening may be the most overused operation in CP

- over-lengthening will lead to slumping in the patient with spastic hamstrings and hip flexors

- crouched posture / debilitating calcaneus

 

Operative Options

 

1.  Formal Z lengthening / Zone 3 / tendon

- > 2cm lose up to 80% of power

- soleus important contributer to power

- soleus might not be tight

- Silverskiold test determines gastrocnemius tightness

 

2. Hoke triple percutaneous slide technique

- proximal and distal cuts medial 

- middle cut lateral

- similar problems to above

 

3. Musculotendinous release (Zone 1)

- best procedures

- Baumann - multiple perpendicular divisions of aponeurosis of gastrocnemius +/- soleus

- Strayer - gastrocnemius recession / single transverse division of aponeurosis of gastrocneumius

 

Equinovarus

 

Cause

 

Tibialis posterior and T Achilles both tight

- most common in spastic hemiplegia 

 

Options

 

1. Perform intramuscular recession

- never extramuscular procedure for fear of reverse deformity

 

2. Tibialis posterior split transfer to Peroneus brevis 

- very effective and preserves plantar flexion

 

3.  Hindfoot deformity fixed 

- Dwyer lateral closing wedge osteotomy 

- lateral calcaneal slide

 

Valgus Defomity

 

Preoperative

 

Always standing Xray of the ankle to ensure no ankle valgus as well

- Coby x-ray

 

Operative Options

 

1.  Grice extra-articular subtalar arthrodesis

 

Results of the Grice are not very good 

 

Scott etal JPO 1988

- 62 feet - 30% fail, 60% poor

- best in child 4-12 years 

 

2.  Evans lateral calcaneal lengthening + first MT plantarflexion osteotomy + T Achilles lengthening

- need first MT plantarflexion osteotomy to enable MT to touch ground post lateral calcaneal lengthening

- may need FDL to T Post transfer also

 

3.  STJ Fusion

 

Hallux Valgus

 

Should always fuse

- high failure with anything else