The Tether™ - Vertebral Body Tethering System is manufactured from:

• Anchors: Ti 6Al-4V ELI titanium alloy per ASTM F136
• Set Screws: Ti 6Al-4V ELI titanium alloy per ASTM F136
• Bone Screws: Ti 6Al-7Nb titanium alloy per ISO 5832-11 with an hydroxyapatite coating per ISO 13779-2
• Cord: Sulene® PET (polyethylene-terephthalate)
• Instruments and Cases: Generally comprised of aluminum, stainless steel, titanium alloy, and/or polymeric materials

Indications

The Tether™ - Vertebral Body Tethering System is indicated for skeletally immature patients that require surgical treatment to obtain and maintain correction of progressive idiopathic scoliosis, with a major Cobb angle of 30 to 65 degrees whose osseous structure is dimensionally adequate to accommodate screw fixation, as determined by radiographic imaging. Patients should have failed bracing and/or be intolerant to brace wear.

Contraindications

The Tether™ - Vertebral Body Tethering System should not be implanted in patients with the following conditions:

• Presence of any systemic infection, local infection, or skin compromise at the surgical site;
• Prior spinal surgery at the level(s) to be treated;
• Known poor bone quality defined as a T-score -1.5 or less;
• Skeletal maturity;
• Any other medical or surgical condition which would preclude the potential benefit of spinal surgery, such as coagulation disorders, allergies to the implant materials, and patients unwillingness or inability to cooperate with post-operative care instructions.

Preoperative Procedure

The surgeon is responsible for being familiar with the indications, contraindications, system/procedure risks, and surgical technique to ensure proper treatment, patient selection, and postoperative care when using The Tether™ - Vertebral Body Tethering System. The patient must be an acceptable surgical risk, and appropriate for vertebral body tethering based on consideration of various factors such as preoperative Cobb angle, curve flexibility, curve type(s), curve location(s), skeletal maturity, and anticipated growth, among others. Examination and evaluation of the individual patient anatomy is necessary to plan the appropriate surgical procedure and technique. Due to smaller vertebral body size and variable venous anatomy, caution should be observed if extending instrumentation proximal to T5. 

Zimmer Biomet Spine does not specify the maximum number of times a re-usable instrument may be re-used. The useful life of these instruments is highly dependent on a number of factors including the frequency and manner in which they are used and the handling they experience in between uses. Inspection and, where appropriate, functional testing prior to instrument use is the best way to determine whether or not an individual device should be used. Review and inspect all instrumentation and implants prior to use. Replace or add any needed components for the planned surgery.

Use of automated cleaning processes without supplemental manual cleaning may not result in adequate cleaning of instruments. Proper handling, decontamination (including 

pre-rinsing, washing, rinsing and sterilization), storage and utilization are important for the long and useful life of all surgical instruments. Even with correct use, care and maintenance, instruments should not be expected to last indefinitely. This is especially true for cutting instruments (e.g., bone awls/drills) and driving instruments (e.g., drivers). These items are often subjected to high loads and/or impact forces. Under such conditions, breakage can occur, particularly when the item is corroded, damaged, nicked or scratched.

Operative Procedure

For surgical placement of The Tether™ - Vertebral Body Tethering System, patients are positioned in the lateral decubitus position with the convex side of the curve to be instrumented facing upwards. As most idiopathic thoracic curves are convex towards the right side, a left lateral decubitus position will be the most common position utilized for instrumentation of thoracic curves. For recommended surgical site preparation, positioning, and technique details, please see the Surgical Technique Guide. For thoracoscopic surgery, standard anesthesia protocol should be observed. However, it is recommended to use a single lung ventilation technique such as a double-lumen endotracheal tube to aid surgical exposure if necessary. Anchor use is recommended at all levels. Consideration should be given to the osseous structure at each level to determine if both a bone screw and anchor are needed to adequately support the construct and anticipated loads. Please refer to the Surgical Technique Guide if implant removal is required (including revision). Close wound(s) and apply wound dressing using standard techniques.

It is critical that patients follow all postoperative instructions provided by care providers including recommendations regarding medications, home care, surgical wound dressings and activity limitations. The patient must be warned to avoid falls or sudden jolts. Failure to follow postoperative instructions could lead to impaired wound healing, injury to neurologic structures or failure to achieve desired curve correction.

Optional protective bracing may be used for up to six months after surgery depending on patient factors such as bone quality and activity levels. Bracing may provide additional support for patients who are overcorrecting or have a suspected or confirmed cord break. Use of The Tether does not preclude the need to brace compensatory curves.