1. ICEOS 2016
Utrecht, November 2016
Proximal Rib-Based Constructs in EOS: Long-Term Follow up and Survivorship
Alexandra Kondratyeva, MD; Nicholas Feinberg, BA; Zachary Bloom, BA; Chun Wai Hung, MEng; Hiroko Matsumoto, MA; John Smith, MD; Josh Pahys, MD; Sumeet Garg, MD; Michael Vitale, MD, MPH; Children’s Spine Study Group

2. Background
Vertical Expandable Prosthetic Titanium Rib (VEPTRTM; Synthes North America, West Chester, PA)
Originally developed for thoracic insufficiency syndrome (TIS)
Expanded for other indications such as early- onset scoliosis (EOS)
Source: DePuy Synthes
For VEPTR, the most superior or proximal attachments are rib circumferential anchors, while the distal or inferior anchors are to rib, spine, or pelvis.
Source: DePuy Synthes

3. Background
One of the more common cause for revisions of VEPTR devices are anchor/mechanical complications.
Acute proximal anchor problems include rib fracture and rib cradle displacements.
Chronic migration of the proximal rib attachments are also a common issue.
Studies have reported mechanical issues, most prominently device migration and rod breakage, to comprise between 18.5% to 83.3% of all complications associated with VEPTR. (Oyoun, Spine 2014; Campbell, Spine 2007; Greggi, 2012; Hasler, Eur Spine 2010; Samdani, Clin Orth Rel Res 2010; Smith, J Neurosurg 2009; Waldhausen, J Ped Surg 2007; White, Clin Orth Rel Res 2011; Yamaguchi, Spine Deformity 2014; Williams, J Ped Ortho 2013; Waldhausen, J Ped Surg 2016).

4. Study Purpose
In light of the high risk of complications, it is clear that further research is necessary to elucidate the risks related to rib- based constructs for the treatment of EOS.
Goal - The purpose of this study is to examine the durability of rib-based constructs used in the treatment of EOS and to identify risk factors associated with revision or failure of the original instrumentation.

5. Methods
Design
Multi-center retrospective cohort study from 5 hospitals in the Children’s Spine Study Group (CSSG)
Children’s Hospital of New York, New York
Primary Children’s Medical Center, Utah
Shriners Hospital for Children, Pennsylvania
Children’s Hospital, Colorado
Seattle Children’s Hospital, Washington
Date range from 2002 – 2011
Analysis: Kaplan-Meir Survivorship

6. Methods Inclusion Criteria Patients with diagnosis of EOS
Treatment with proximal rib-based growing construct (VEPTR)
Index surgery > 5 years
Exclusion Criteria
Unknown cause for implant removal

7. Patient Demographics Patient Characteristics Patients (no.) 206
Mean age at implant (year)
Gender
Male
103 (50%)
Female
EOS Etiology
Congenital
46 (22.3%)
Neuromuscular
88 (42.7%)
Syndromic
35 (17%)
Idiopathic
37 (18%)
Ambulatory Status
Ambulator
98 (47.6%)
Non-ambulator
108 (52.4%)

8. Additional Characteristics
Preoperative Curve Characteristics
VEPTR Implant Characteristics
Major Cobb Classification
< 20
5 (2.4%)
17 (8.3%)
140 (68%)
> 90
41 (19.9%)
Missing
3 (1.5%)
Kyphosis Classification
13 (6.3%)
20-50
105 (51%)
> 50
46 (22.3%)
42 (20.4%)
Number of VEPTRs
Unilateral
72 (35%)
Bilateral
134 (65%)
Location of Inferior Attachment
Pelvis
114 (55.3%)
Spine
87 (42.2%)
Both
5 (2.4%)

9. Revision/Failure Risk
Number (%)
Original Construct Revision/Failure
140 (68%)
Original Construct – Survival to “Safe” Exit
66 (32%)
Year + SD (Range)
Age at revision/failure
(1-8)
Age at "Safe" Exit
(2-13)
Factors Associated with Revision/Failure
Greater preoperative Major Cobb angle (p = 0.006)
Preoperative hyperkyphosis (p = 0.021)
Age < 6 y (p = 0.001)
Inferior anchor to pelvis (p = 0.02)

10. Construct Survivorship
10% of revisions/failures occur 5+ years after index
p <0.001
90% of failures occurred in the first 4 years post-index surgery
Revision risk relatively consistent each year through year 7 postoperatively

11. Conclusions
Majority of revisions/failures (90%) occurred within first 4 years of index surgery
Risk factors for VEPTR revision/failure
Inferior fixation to pelvis as opposed to spine
Age < 6 years
Higher preoperative major Cobb angle
Preoperative hyperkyphosis
Future Goal
Need for elucidating risk factors to improve care for patients with EOS

12. Thank You
Michael G. Vitale, MD, MPH