Tuesday, January 16, 2018

Vertebral Body Tethering for Scoliosis (Part 3)

In Medicine, and in particular the area of spine deformity, the development of new treatments and technologies which can demonstrate improved outcomes, lower frequencies of complications, and/or faster recovery can create a “buzz” and enthusiasm depending on its potential of improvement.  Physicians typically see these innovations earlier than the general public at medical meetings and read about them in peer-reviewed medical journals.  Slightly later the medical media, followed by mainstream media, begin to report on the new medical technologies, especially if these treatments have developed some traction amongst physicians.  One such technology is Vertebral Body Tethering (VBT) for scoliosis in the growing spine. 

As detailed in previous postings on this blog there is significant potential for this technology, but little scientific evidence of its efficacy in humans.  At present there are no approved implant systems in the U.S. which are FDA-approved for scoliosis. Spine implants used for VBT are being used in an off-label or unlabeled manner in the U.S.  It is important to understand that innovations, especially in area of surgical spine deformity treatment, advances typically occur faster than does FDA approval.  So innovations without FDA approval does not categorically mean they are unsafe or do not work, rather there is an absence of sufficient high-level of medical evidence to prove these devices are safe and efficacious to the FDA, who demands very high level of scientific proof.  Prior to FDA approval implant systems, such as VBT, exist in a “grey” area.  This can be frustrating to patients and caregivers who are anxious for advances in medicine, yet there is scant medical literature to help them navigate treatment options. 

In the next blog post the complications of VBT will be presented.

Friday, December 8, 2017

Top Eleven Podium Presentations at the 2017 ICEOS Meeting Which Will Impact the Care of EOS Patients in My Practice
1.       Paper #1
a.       Bouton D, Karol L, Poppino K, Johnson C.  Continued deterioration in pulmonary function at a minimum 18-year follow-up from early thoracic fusion in non-neuromuscular patients.
b.      Conclusion: Patients with thoracic spinal fusion at a very young age (mean 2.7 years) have a continued decline in pulmonary function (38% of normal) as they enter adulthood, which can be life-threatening.  Additionally, their functional capacity (6-minute walk test) is severely limited to 62% vs. age-matched controls.
c.       Take-away message: Avoid thoracic spine fusions in children less than 5 years of age.
2.       Paper #3
a.       Celebiolglu E, Yataganbaba A, Asli O, Degirmenci C, Kocyigit IA, Tekin R, Demirkiran HG, Yalcin EE, Demir AU, Yazici M.  Can TGR change the natural history of pulmonary function in EOS?  Is radiological straightness correlated with normal lung development?
b.      Conclusion: Traditional Growing Rods can help Early Onset Scoliosis patients who would otherwise have serious pulmonary insufficiency and help achieve pulmonary capacities compatible with a healthy life.  Despite significant decreases in Traditional Growing Rod graduates in oxygen consumption capacity and pulmonary test compared to healthy controls, results were not statistically different than Adolescent Idiopathic Scoliosis.
c.       Take-away message: Traditional Growing Rods are effective and successful in achieving good results in pulmonary functions as well as radiological parameters.
3.       Paper #5
a.       Kawakami N, Matsumoto H, Saito T, Tauchi R, Ohara T, Redding G.  Pre-operative Six Minute Walk Performance in Children with Congenital Scoliosis.
b.      Conclusion: The 6 minute walk test is a feasible measure of function and is substantially reduced prior to surgery in most children with congenital scoliosis.  The 6 minute walk  test correlates with age and inversely with Cobb angle, but not FVC%. 
c.       Take-away message: The 6 minute walk test measured serially in meters and not as a % of normal is a useful measure of functional status in children with congenital scoliosis.
4.       Paper #25
a.       Ahmad A, Subramanian T, Panteliadis P, Wilson-Macdonald J, Rothenfluh D, Nnadi C.  Quantifying the “Law of Diminishing Returns” in Magnetically Controlled Growing Rods.
b.      Conclusion: The “Law of Diminishing Returns” can also be observed following serial distraction in Magnetically Controlled Growing Rods.  In comparison to previously published data for Traditional Growing Rods, there is a gradual linear decline as opposed to a rapid initial decline in lengthening.
c.       Take-away message: Magnetically Controlled Growing Rods gradually appear to stiffen the spine in a similar way as Traditional Growing Rods.
5.       Paper #26
a.       Poon S, Spencer HT, Sever R, Cho R.  Maximal Force Generated by Magnetically Controlled Growing Rods Decreases with Rod Lengthening.
b.      Conclusion:  There is a small (3.6 lb.) statistically significant decrease in the maximal force generated by MCGR as the rods are lengthened.  This decrease may contribute to diminished spine length gained with each subsequent MCGR lengthening.
c.       Take-away message: Magnetically Controlled Growing Rods are able to maintain >92% of distraction force near the end (83%) of the actuator length.
6.       Paper #29
a.       ElBromboly Y, Johnston C, McClung A, Samdani A, Glotzbecker M, St. Hilaire T, Hurry J, Kedar P, Flynn T, El-Hawary R.  Does the Type of Proximal Anchor Used During Distraction-Based Surgeries for Patients with Non-Idiopathic EOS Affect Spine Length?
b.      Conclusion:  At a minimum 5 year follow-up, distraction-based surgeries increased spine length for patients for non-idiopathic EOS; regardless of proximal anchor choice.  Rib-based anchors may protect against potential law of diminishing returns.
c.       Take-away message: Rib-based proximal anchors in growing rods appear to achieve equivalent correction as spine-based anchors in non-idiopathic patients.
7.       Paper #38
a.       Luhmann SJ, McAughey E, Ackerman S, Bumpass D, McCarthy R.  Cost analysis of growth guidance system compared with magnetically controlled and traditional growing rods for early-onset scoliosis in the US: an integrated health care delivery system perspective.
b.      Conclusion: Growth Guidance Systems resulted in fewer invasive surgeries (3.4 vs. 14.4) and deep Surgical Site Infections than Traditional Growing Rods with lower cumulative costs per patient than both Magnetically Controlled Growing Rods ($29,916 less) and Traditional Growing Rods ($25,226 less) over a 6-year episode of care. 
c.       Take-away message: Growth Guidance Systems result in fewer infections, less surgery and are 16-18% cheaper than Magnetically Controlled Growing Rods or Traditional Growing Rods of the entire episode of care.
8.       Paper #40
a.       Bauer J, Yogova P, Neiss G, Rogers KJ, Sturm PF, Sponseller P, Luhmann SJ, Pawelek J, Shah SA.  Is There an Improvement in Quality of Life with Early Onset Scoliosis Managed with Traditional Growing Rods Converted to Magnetically Controlled Growing Rods.
b.      Conclusion: Although patient families and their surgeons may subjectively report improved Quality of Life after conversion from frequent surgical Traditional Growing Rods lengthenings to in-office Magnetically Controlled Growing Rod lengthenings, these improvement were not evident in Quality of Life surveys.
c.       Take-away message: In patients converted to Magnetically Controlled Growing Rods the benefits are obvious to caregivers and surgeons, but the outcome measures are not sensitive enough to pick up a difference.
9.       Paper #41
a.       Skaggs D, Akbarnia B, Pawelek J, Matsumoto H, St. Hilaire T, Sturm PF, Perez-Grueso FJS, Luhmann SJ, Sponseller P, Smith J, White K, Vitale M.  Two Year HRQOL Measures are Similar Between Magnetically-Controlled Growing Rod (MCGR) Patients and Traditional Growing Rod Patients.
b.      Conclusion: Prior to surgery MCGR patients has lower HRQOL in 3 out of 10 domains (Daily Living, Physical Function, Transfers), however at 24 months both groups were similar across all domains.  Subgrouping of neuromuscular patients revealed differences in financial and parental impact domains which suggest etiology plays a role in the Health-Related Quality of Life in these patients.
c.       Take-away message: There may be a benefit to Magnetically Controlled Growing Rods in Daily Living and Physical Function when compared to Traditional Growing Rods.  More study is needed.
10.   Paper #42
a.       Gomez JA, Kubat O, Hurry J, Soroceanu A, Flynn T, Tovar M, Hanstein R, Lafage V, Schwab F, Smith J, Skaggs, El-Hawary R.  Spinopelvic alignment affect Health-related Quality of Life (HRQoL) for Patients with Early Onset Scoliosis.
b.      Conclusion: For children with early onset scoliosis, preop Pelvic Incidence >60 degrees (poor Pain outcomes), pre and post-op Lumbar Lordosis>60 degrees (poor Satisfaction outcomes), postop Pelvic Incidence-Lumbar Lordosis mismatch >20 degrees (poor Fatigue outcomes) and post-op Proximal Junctional Kyphosis (poor Fatigue outcomes) all decrease Health-Related Quality of Life.
c.       Take-away message: Achieving good spinopelvic alignment is important in Early-Onset Scoliosis treated surgically.
11.   Paper #45
a.       Matsumoto H, Campbell M, Minkara A, Roye DP, Garg S, Johnston C, Samdani A, Smith J, Sponseller P, Sturm PF, Vitale M.  Development of a Risk Severity Score (RSS) Predicting Surgica Site Infection in Early Onset Scoliosis: Identifying High-Risk Patients.
b.      Conclusion: The Risk Severity Score (neuromuscular diagnosis and endocrine, gastrointestinal, pulmonary comorbidities, etc…) provides empirically-derived patient-specific Surgical Site Infection risks.  It can be used to prepare for high-risk patients for surgery, as a factor in clinical decision-making, and to facilitate comparison between hospital outcomes. 

c.       Take-away message: The risk of a postoperative surgical wound infection can be tabulated for preoperative optimization and in discussions with caregivers preoperatively.

The Growing Spine Study Group 

Monday, November 13, 2017

Vertebral Body Tethering Part 2

Vertebral Body Tethering for Scoliosis

As mentioned in the last blog there is a paucity of information/evidence on the use of VBT in skeletally-immature patients with scoliosis.  Animal studies have demonstrated VBTs can modulate spinal growth with few changes to the intervertebral disc or growth plates.  Early, short-term, single institution series have been encouraging with few reported serious complications.  More research is necessary on VBT safety, timing of VBT placement, VBT tensioning, intervertebral disc health, long-term patient reported and radiographic outcomes of VBT.

Current indications for VBT
1     1. Skeletally immature patient (Risser 0-3, Sander digital hand score <5).  Optimal timing of VBT surgery is necessary to produce a satisfactory spinal alignment at the completion of spinal growth.  At present there is insufficient information available to accurately predict when to place a VBT.
2     2.  Deformity location: main thoracic
3     3. Idiopathic diagnosis
4     4. Coronal deformity: main thoracic (30-70 degrees), thoracolumbar/lumbar (30-60 degrees)
5     5. Flexibility on side-bending radiographs to less than 30 degrees.
6     6. Less than 20 degrees of axial rotation. 
7     7. Less than 40 degrees of kyphosis

Surgical Technique: VBT for Scoliosis
VBT is a thoracoscopic, minimally-invasive technique in which screws are placed into the vertebral bodies on the convex side of the coronal deformity.  The screws are placed into the middle of the vertebral body with bicortical purchase under fluoroscopic guidance.  A high-strength, braided polypropylene tether is then placed into the screw heads and then sequentially secured to each screw after segmental compression.  The technique achieves modest correction of the spinal deformity immediately postoperative.  

Technical challenges for this technique do exist.  Placement of anterior body screws above T5 and below L4 is not typically possible patient anatomy.  There are questions about the number of vertebra which should be included into the VBT construct, how much to tension to place across each vertebral motion segment within the VBT construct, optimal screw trajectory and screw size, placement of VBT across the diaphragm for thoracolumbar curves, and implant prominence.