Incidence of Proximal junctional kyphosis with Magnetic Expansion

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Incidence of Proximal junctional kyphosis with Magnetic Expansion Control Rods in early onset scoliosis

Incidence of Proximal junctional kyphosis with Magnetic Expansion Control Rods in early onset scoliosis P Inaparthy, JC Queruz, C Thakar, D Rolton, C Nnadi Oxford University Hospitals

Introduction • High rates of complications reported with traditional growing rod techniques for Early

Introduction • High rates of complications reported with traditional growing rod techniques for Early Onset Scoliosis (EOS) – Bess et al (JBJS Am 2010) – Akbarnia et al (spine 2008) • Proximal junctional kyphosis (PJK) – a well recognised complication in deformity correction • But very little literature available on PJK with growing rods for EOS – Shah et al (2014), Watanabe et al (2014) • No literature on PJK with magnetic growing rods (MCGR)

Aim • To report on the incidence of PJK following treatment with magnetic growing

Aim • To report on the incidence of PJK following treatment with magnetic growing rods in EOS • Evaluate whether Tail Gating results in reduced incidence of PJK compared to previous reports

Material and Methods • Prospective cohort observational study • Over 3 years – 2011

Material and Methods • Prospective cohort observational study • Over 3 years – 2011 to 2014 • Inclusion criteria – Pts whom the surgeon felt would benefit from the use of the magnetic rods – Had a minimum of 2 lengthening procedures

METHODS TAIL GATING TECHNIQUE USING ANNUAL GROWTH VELOCITY T 1 - L 5 (Dimeglio)

METHODS TAIL GATING TECHNIQUE USING ANNUAL GROWTH VELOCITY T 1 - L 5 (Dimeglio) Curves of growth velocity • ‘Maximum’ distraction with conventional GR 2 • ‘Law of diminishing returns’ Skaggs et al Spine 2011 1 • ‘Tail-gating’ concept to shadow growth • Spine in EOS does have growth potential • Magec rods allow for controlled distraction • Apply knowledge of expected growth • Less force on construct = less risk of failure • ‘Scientific approach’ 5 Birth – 5 yrs 2. 2 cm 5 – 10 yrs 1. 1 cm 10 15 20 kg 30 kg 10 yrs – Puberty 1. 8 cm >30 kg

METHODS • 3 lateral-view standing radiographs – Pre-op – After index MCGR rod surgery

METHODS • 3 lateral-view standing radiographs – Pre-op – After index MCGR rod surgery (prior to the first formal lengthening) – The latest follow-up • Evaluation by 2 authors

Results Diagnosis • 21 pts – 12 males : 9 females • Idiopathic scoliosis

Results Diagnosis • 21 pts – 12 males : 9 females • Idiopathic scoliosis 3 • Average follow up 23. 4 mnths • Visceral associations 3 (range 6 -38 mths) • Average no. of distractions 7. 5 (range 2 -12) • Proximal fixation (Screws (20 pts) and hooks (1 pt)) • No returns to theatre for PJK • Central core myopathy 2 • Neuromuscular(1), Hemivertebra(1), Arthrogryposis(1) • Syndromic 10

Proximal junctional kyphosis • > 10 degree difference • Average PJK angle 6 pts

Proximal junctional kyphosis • > 10 degree difference • Average PJK angle 6 pts (28. 6%) 25. 5 degrees (range 10. 6 to 35. 1) • Proximal screw fixation in all cases

PJK Cases Levels of instrumentat ion Pre-op kyphosis 1 T 3, 4 and L

PJK Cases Levels of instrumentat ion Pre-op kyphosis 1 T 3, 4 and L 4, 5 19. 1 14. 8 43. 3 24. 2 2 T 3, 4 and L 4, 5 17. 4 23. 6 44 26. 6 3 T 3, 4 and L 4, 5 8. 6 21. 3 43. 7 35. 1 4 T 3, 4, 5 and L 4, 5 20. 2 17. 1 48. 6 28. 4 5 T 3, 4 and L 4, 5 S 1 3. 4 24. 5 31. 8 28. 4 6 T 3, 4 and T 11, 12, S 1 7. 8 18. 5 18. 4 10. 6 Immediate Last followpost-op up PJK

PJK Demographics Non-PJK pts PJK Pts No. of pts 15 6 Avg. age 8.

PJK Demographics Non-PJK pts PJK Pts No. of pts 15 6 Avg. age 8. 4 yrs 5. 3 yrs Avg. follow up 21. 1 mths 32. 5 mths Male: female 4: 3 2: 1 Syndromic 10 out of 21 All 6 Pre-op thoracic kyphosis 47. 3 deg 52. 5 deg No. of distractions 6. 3 10. 5

Conclusion • Associations identified: – Syndromes – Higher incidence in males (4/6) – Younger

Conclusion • Associations identified: – Syndromes – Higher incidence in males (4/6) – Younger age group (5. 3 years) – Higher number of distractions in the PJK group – Pre-operative hyper kyphosis (average 52. 5 degrees)

Conclusion • Lesser incidence of PJK in our group compared to other studies using

Conclusion • Lesser incidence of PJK in our group compared to other studies using traditional growing rods – Shah et al (spine 2014) = 45% (all screw construct) – Watanabe et al (spine 2014) = 26% (but baseline of 20 deg compared to 10 deg in our group) § Incremental distraction using the Tail gating technique appears to reduce incidence of PJK