Scheuermann's kyphosis

Definition 

 

Structural kyphosis of thoracic or thoracolumbar spine

- characterised by vertebral wedging & subsequent growth disturbance of vertebral end plate

 

X-ray Diagnostic Criteria Sorensen 1964

 

1.  Kyphosis > 45°

 

2. > 5° wedging 3 or more adjacent apical vertebrae

 

Other features

- Schmorl nodes

- irregularity & flattening of vertebral end-plates

- narrow disc spaces

- increased AP diameter of apical vertebrae

- spondylosis in adults

 

Epidemiology

 

Prevalence 0.5 to 8%

 

M:F 2:1 

 

High familial predilection

- AD with high penetrance and variable expression

 

Aetiology

 

Many theories proposed / true cause unclear

 

1.  AVN of ring apophysis

- but Ring Apophysis doesn't contribute to vertebral growth

 

2.  Schmorl Nodes

- protrusions of cartilage of disc through endplate into body

- ? nodes decrease enchondral ossification with growth arrest of anterior body

- but nodes present in normal patients (40-75% autopsies)

 

3.  Mechanical Factors

- likely that kyphosis occurs first

- increases pressure on vertebral end-plates anteriorly and causes secondary body wedging 

 

4.  Osteochondritis or Epiphysitis

- but no inflammatory features or necrotic bone

 

5.  Abnormality of Cartilage endplate identified 

- Abnormal matrix

 

6.  Tight ALL

 

Symptoms

 

Onset prior to puberty ~ 10 years old

 

Pain

- mechanical and usually in area of deformity

- ceases with maturity

 

Signs

 

Kyphotic Deformity

- fixed / remains with hyperextension

- worsen's on Adam's forward bending

 

Also

- compensatory lumbar hyperlordosis 

- increased cervical kyphosis 

- associated mild - moderate scoliosis common

 

Lateral standing X-ray

 

Cobb angle

- line along superior & inferior end-plates of each body 

- measure angle of intersection

- often difficult to see T1 - T5

 

Individual vertebral wedging

- > 5o

- > 3 adjacent vertebrae

 

Schmorl nodes

 

Irregularity & flattening of vertebral end-plates

 

Hyperextension Lateral X-ray

 

Over bolster

- structural degree of deformity

- degree of correction

 

DDx 

 

1.  Postural kyphosis 

- more flexible,  disappears prone, normal x-ray, disappears with hyperextension lateral

 

2.  Osteoporosis / crush fracture

 

3.  Congenital kyphosis / anterior bar

 

4.  Infection, tumour

 

5.  Ankylosing spondylitis

 

6.  Post laminectomy

 

7.  Congenital / Developmental

- OI / SED / Achondroplasia / Morquio's

 

Natural History

 

Weinstein 1993 Iowa

- 67 patients average kyphosis 71°

- follow up 32 years vs age match controls

 

Findings

1.  More intense back pain but no increased analgesia use

2.  No difficulty with ADL's

3.  Normal recreational activities

4.  No increased numbness

5.  More sedentary jobs 

6.  ROM

- decreased extension

- weaker extension

7.  Normal self esteem

 

Curve <100° 

- normal pulmonary function

 

Curve >100° 

- restrictive lung disease

 

Management

 

Non Operative Management

 

Observe

 

<50°

No progression on serial Xray

No / mild pain

 

Exercise

 

No long-term correction

- useful to maintain flexibility / correct lumbar lordosis

- strengthen extensors of spine i.e. swimming, pilates

 

Brace

 

Indications

- skeletally immature

- curve < 75°

 

Type

- Milwaukee Brace / thoracic kyphosis

- TLSO / TL kyphosis

 

Timing

 

Brace full-time for 18/12

- then part-time until skeletal maturity

 

Issue

- trying to get a 15 year old boy to wear a CTLSO for 3 years

 

Operative Management

 

Indications

 

Adolescent

- pain +++ uncontrolled by brace 

- kyphosis > 75° & progressing

- most surgeons won't operate until 90°

 

Adults

- pain +++ despite non-operative treatment

 

Principles

 

1. Correction of kyphosis

2. Arthrodesis of spine

 

Issues

 

Approach

 

Posterior Approach

- failure rate high with loss of correction & pseudarthrosis if curve large

- fusion on tension side of spine

 

Correction films

- crucial

- posterior instrumentation will only give you 10o correction

- if corrects only to > 50o , need to release ALL

 

One Stage

 

Curve < 75° & corrects to < 50°

- one stage posterior instrumented fusion

 

Two Stage

 

Curve > 75° & corrects to > 50°

- two stage procedure

- anterior thoracotomy / release of ALL

- discectomy & interbody fusion of 5 or 6 apical levels with ribs

- posterior instrumented fusion 2/ 52 later

 

Last Instrumented Vertebra LIV

 

Sagittal line from the posterior edge of the sacrum should intersect the LIV

- supine & standing hyperextension Xrays

- should be distal to first lordotic disc

- usually L1 if apex T6; L2 if apex T8; L3 if apex T10

 

Results

 

Coe et al Spine 2010

- retrospective review of 683 cases

- 50% posterior fusion, 40% anterior and posterior, 10% anterior only

- mean patient age 21

- 4% infection rate

- 2% acute neurological injury

- 4 spinal cord injuries (0.6%)

- 4 deaths (0.6%)