Efficacy of Sub-laminar and/or Interspinous Tethers to Prevent Proximal Junctional Kyphosis After Surgical Correction of Adult Spinal Deformity

Efficacy of Sub-laminar and/or Interspinous Tethers to Prevent Proximal Junctional Kyphosis After Surgical Correction of Adult Spinal Deformity - Randomized Multicentric Single Blind Controlled Trial

PJK (proximal junctional kyphosis) at the upper end of spinal fusions after surgical correction of adult spinal deformity is not uncommon. Two-thirds of cases are observed within the first 3 months after surgery and 80% within the first 18 months. PJK is consequently a common problem after surgery for adult spinal deformity, representing one of the most frequent complications following this kind of procedure. Although the first-line treatment of this event is conservative, surgery may be necessary in around 30-40% of cases. Revision surgery generally consists of extending the posterior spinal instrumentation.

Prophylactic vertebroplasty has been proposed to reduce the risk of PJK and PJF, with promising results but with the limitation of reinforcing only the bony structures, with no action on the soft tissues. In this context, some authors have reported that the use of tethers, creating a transitional zone at the upper end of the construct between the fused and the non-instrumented spine, could reduce the occurrence of this complication (PJK). One of the hypotheses is that the use of a topping-off system results in a transitional zone reducing stresses at the junctional spine and may reduce the occurrence of both PJK and the need for reoperation.

Compared with other topping-off systems, such as hooks, the surface of contact provided by the bands on the posterior arches is much greater and the primary stability much better. In addition, the risk of malposition is extremely low.

The aim of this study is therefore to compare the occurrence of PJK and PJF in patients for whom tethers were implanted at the upper end of the instrumentation versus patients for whom no tether system was used.

In a retrospective study conducted in the neurosurgery department of the HCL on 38 patients undergoing multilevel spine instrumentation with junctional tethers, PJK occurred in 8 of them (21%) after 24 months of follow-up.

Inclusion Criteria:

• Patient men and women older than 18
• Patient indicated spinal posterior fusion and instrumentation with the upper end (UIV with screws) between T9 and L2 and the lower end between L5 and iliac
• Constructs ≥4 levels (i.e., ≥4 discs included)
• Patient able to signed a consent form
• Patient able to fill a self-administered questionnaire
• Patient affiliated to health care insurance (social security in France

Exclusion Criteria:

• Allergy to metal
• Cimentoplasty at the junctional zone (UIV, UIV+1 and/or UIV+2)
• Bone metabolism disorders that potentially compromise the mechanical support expected from this type of implant.
• Morbid obesity (BMI > 40)
• Patients with infection (in particularly osteomyelitis)
• Cancer of lesss than 5 years or currently treated
• Acute trauma
• Immunodepression
• Parkinson
• Chronic inflammatory disease
• Severe psychological disorders
• Pregnancy or women breastfeeding
• Inadequate tissue coverage of implant site,
• Interference with other critical anatomical structures.
• Patient not being able to understand the objectives of the study or refusing to comply with postoperative instructions
• Patient participating in an ongoing study that may interfere with this study
• Patient under legal protection