SPINAL CONCEPTS, INC., BACFIX TI SPINAL FIXATION SYSTEM

K973687 · Spinal Concepts, Inc. · MNH · Mar 18, 1998 · Orthopedic

Device Facts

• Record ID: K973687
• Device Name: SPINAL CONCEPTS, INC., BACFIX TI SPINAL FIXATION SYSTEM
• Applicant: Spinal Concepts, Inc.
• Product Code: MNH · Orthopedic
• Decision Date: Mar 18, 1998
• Decision: SN
• Submission Type: Traditional
• Regulation: 21 CFR 888.3070
• Device Class: Class 2
• Attributes: Therapeutic

Intended Use

The Spinal Concepts, Inc. BacFix™ ti Spinal Fixation System consists of a combination of components which include rods, hooks, locking wedges, screws and transverse connectors which are indicated to provide temporary stability of the thoracic, thoracolumbar or lumbar spine (T1-S1). When intended for pedicle screw fixation, the implants are intended for use in Grade 3 and 4 sponylolisthesis at L5-S1, utilizing autologous bone graft, having the device fixed or attached to the lumbar and sacral spine and intended to be removed after solid fusion is attained. Levels of pedicle screw attachment for this indication range from L3 to the sacrum. When intended for non-pedicle, posterior screw fixation, the system is intended for hook and/or sacral/iliac screw fixation from the thoracic spine to the ileum/sacrum. The indications are: 1. Idiopathic scoliosis. 2. Neuromuscular scoliosis/kyphoscoliosis with associated paralysis or spacticity. 3. Scoliosis with deficient posterior elements such as that resulting from laminectomy or myelomeningocele. 4. Spinal fractures (acute reduction or late deformity). 5. Degenerative disc disease (back pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies). 6. Neoplastic disease. 7. Spondylolisthesis. 8. Spinal stenosis. 9. Revision surgery.

Device Story

BacFix™ ti Spinal Fixation System provides temporary spinal stability; consists of titanium rods, hooks, locking wedges, screws, and transverse connectors. Components preassembled outside wound; instrument applies three-point shear clamp for fixation. Used by surgeons in clinical settings to treat spinal deformities and degenerative conditions. Output is rigid construct stabilizing thoracic, thoracolumbar, or lumbar spine. Benefits patient by maintaining alignment during fusion; pedicle screw use restricted to specific spondylolisthesis cases requiring subsequent hardware removal.

Clinical Evidence

Bench testing only. Static and fatigue mechanical testing performed on BacFix™ ti and existing BacFix™ systems. Results compared to published data for other spinal fixation systems, demonstrating mechanical integrity and substantial equivalence.

Technological Characteristics

Materials: Ti-6AL-4V ELI (ASTM F-136), Ti-6AL-7Nb (ASTM F-1295), unalloyed titanium (ASTM F-67). Components: rods (5.5/6.0mm), hooks, mono-axial/multi-axial screws (5.0-8.0mm), locking wedges, transverse connectors. Fixation: three-point shear clamp instrument. Sterilization: sterile or non-sterile (requires user sterilization to 10-6 SAL).

Indications for Use

Indicated for patients requiring temporary spinal stabilization (T1-S1). Pedicle screw use limited to Grade 3-4 spondylolisthesis at L5-S1 (L3-sacrum attachment) with autologous bone graft; removal required after fusion. Non-pedicle/posterior screw fixation indicated for idiopathic/neuromuscular scoliosis, kyphoscoliosis, deficient posterior elements, spinal fractures, degenerative disc disease, neoplastic disease, spondylolisthesis, spinal stenosis, and revision surgery.

Regulatory Classification

Identification

(1) Rigid pedicle screw systems are comprised of multiple components, made from a variety of materials that allow the surgeon to build an implant system to fit the patient's anatomical and physiological requirements. Such a spinal implant assembly consists of a combination of screws, longitudinal members (e.g., plates, rods including dual diameter rods, plate/rod combinations), transverse or cross connectors, and interconnection mechanisms (e.g., rod-to-rod connectors, offset connectors).(2) Semi-rigid systems are defined as systems that contain one or more of the following features (including but not limited to): Non-uniform longitudinal elements, or features that allow more motion or flexibility compared to rigid systems.

Special Controls

*Classification.* (1) Class II (special controls), when intended to provide immobilization and stabilization of spinal segments in skeletally mature patients as an adjunct to fusion in the treatment of the following acute and chronic instabilities or deformities of the thoracic, lumbar, and sacral spine: severe spondylolisthesis (grades 3 and 4) of the L5-S1 vertebra; degenerative spondylolisthesis with objective evidence of neurologic impairment; fracture; dislocation; scoliosis; kyphosis; spinal tumor; and failed previous fusion (pseudarthrosis). These pedicle screw spinal systems must comply with the following special controls:(i) Compliance with material standards; (ii) Compliance with mechanical testing standards; (iii) Compliance with biocompatibility standards; and (iv) Labeling that contains these two statements in addition to other appropriate labeling information: “Warning: The safety and effectiveness of pedicle screw spinal systems have been established only for spinal conditions with significant mechanical instability or deformity requiring fusion with instrumentation. These conditions are significant mechanical instability or deformity of the thoracic, lumbar, and sacral spine secondary to severe spondylolisthesis (grades 3 and 4) of the L5-S1 vertebra, degenerative spondylolisthesis with objective evidence of neurologic impairment, fracture, dislocation, scoliosis, kyphosis, spinal tumor, and failed previous fusion (pseudarthrosis). The safety and effectiveness of these devices for any other conditions are unknown.” “Precaution: The implantation of pedicle screw spinal systems should be performed only by experienced spinal surgeons with specific training in the use of this pedicle screw spinal system because this is a technically demanding procedure presenting a risk of serious injury to the patient.” (2) Class II (special controls), when a rigid pedicle screw system is intended to provide immobilization and stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion in the treatment of degenerative disc disease and spondylolisthesis other than either severe spondylolisthesis (grades 3 and 4) at L5-S1 or degenerative spondylolisthesis with objective evidence of neurologic impairment. These pedicle screw systems must comply with the following special controls: (i) The design characteristics of the device, including engineering schematics, must ensure that the geometry and material composition are consistent with the intended use. (ii) Non-clinical performance testing must demonstrate the mechanical function and durability of the implant. (iii) Device components must be demonstrated to be biocompatible. (iv) Validation testing must demonstrate the cleanliness and sterility of, or the ability to clean and sterilize, the device components and device-specific instruments. (v) Labeling must include the following: (A) A clear description of the technological features of the device including identification of device materials and the principles of device operation; (B) Intended use and indications for use, including levels of fixation; (C) Identification of magnetic resonance (MR) compatibility status; (D) Cleaning and sterilization instructions for devices and instruments that are provided non-sterile to the end user; and (E) Detailed instructions of each surgical step, including device removal. (3) Class II (special controls), when a semi-rigid system is intended to provide immobilization and stabilization of spinal segments in the thoracic, lumbar, and sacral spine as an adjunct to fusion for any indication. In addition to complying with the special controls in paragraphs (b)(2)(i) through (v) of this section, these pedicle screw systems must comply with the following special controls: (i) Demonstration that clinical performance characteristics of the device support the intended use of the product, including assessment of fusion compared to a clinically acceptable fusion rate. (ii) Semi-rigid systems marketed prior to the effective date of this reclassification must submit an amendment to their previously cleared premarket notification (510(k)) demonstrating compliance with the special controls in paragraphs (b)(2)(i) through (v) and paragraph (b)(3)(i) of this section.

Predicate Devices

• BacFix™ Spinal Fixation System (K964404)
• Synthes Universal Spinal System (K921948, K922855, K943725)

Submission Summary (Full Text)

{0}------------------------------------------------

K973687

# SUMMARY OF SAFETY AND EFFECTIVENESS BacFix™ ti Spinal Fixation System

#### General Information I.

| Classification Name: | 87 Orthopedics |
|--------------------------------|---------------------------------------------------------------------------------------------------------|
| Common Name: | Appliance, Fixation, Spinal Interlaminal |
| Device Trade Name: | BacFixTM ti Spinal Fixation System |
| Classification Code: | This device has been placed in Class II by the<br>Orthopedics Panel. |
| Submitter's Name & Address: | Spinal Concepts, Inc.<br>8200 Cameron Road, Suite B-160<br>Austin, Texas 78754 U.S.A.<br>[phone] |
| Establishment Registration No: | 1649384 |

Contact Person: Teena M. Augostino Director, Clinical and Regulatory Affairs

Summary Preparation Date: March 3, 1998

#### II. Predicate Device

The Spinal Concepts, Inc. BacFix™ ti Spinal Fixation System claimed to be substantially equivalent in material, design, and function to the existing BacFix™ Spinal Fixation System and the Synthes Universal Spinal System.

#### III. Device Description

The Spinal Concepts, Inc. BacFix™ ti Spinal Fixation System consists of a combination of titanium components which include rods, hooks, locking wedges, screws and transverse connectors which are indicated to provide temporary stability of the thoracic. thoracolumbar or lumbar spine (T1-S1). The BacFix™ Spinal Fixation System consists of longitudinal members (spinal rods), in diameters of 5.5 and 6.0mm, in two hardnesses, and a variety of lengths; spinal anchor components, hooks and screws (mono-axial and multi-axial) of various diameters (5.0. 6.0. 7.0 and 8.0mm) and lengths; locking connectors (threaded wedge and nut or non-threaded wedge and locking clip) sized to fit the spinal rods; and a transverse connector assembly (link), also in various lengths. Hooks and screws may be placed at any position along the spinal rods. Wedges are used to connect the spinal rods to screws (hooks and links). These components are preassembled outside the wound, eliminating the need to pre-plan the position of each eyebolt on the spinal rod. A spinal rod is positioned within the open face of the wedge. Fixation of the construct is accomplished using an instrument that applies a three point shear clamp. Addition of the hex nut (when using threaded wedge) and optional use of the

{1}------------------------------------------------

locking clip (when using the non-threaded wedge) complete the implant. Anchor components may be added to (or removed from) the construct at any time during the procedure.

#### IV. Sterilization

The BacFix™ ti Spinal Fixation System implants and instrumentation may be provided sterile or non-sterile. Both implants and instruments must be sterilized prior to use in accordance with the recommended sterilization parameters described in the package insert in order to achieve a sterility assurance level of 10-6.

#### V. Indications for Use

When intended for pedicle screw fixation, the implants are intended for use in Grade 3 and 4 sponylolisthesis at L5-S1, utilizing autologous bone graft, having the device fixed or attached to the lumbar and sacral spine and intended to be removed after solid fusion is attained. Levels of pedicle screw attachment for this indication range from L3 to the sacrum.

When intended for non-pedicle, posterior screw fixation, the system is intended for hook and/or sacral/iliac screw fixation from the thoracic spine to the ileum/sacrum. The indications are:

- 1. Idiopathic scoliosis.
- Neuromuscular scoliosis/kyphoscoliosis with associated paralysis or spacticity. 2.
- Scoliosis with deficient posterior elements such as that resulting from laminectomy 3. or myelomeningocele.
- 4. Spinal fractures (acute reduction or late deformity).
- Degenerative disc disease (back pain of discogenic origin with degeneration of the 5. disc confirmed by history and radiographic studies).
- Neoplastic disease. 6.
- 7. Spondylolisthesis.
- 8. Spinal stenosis.
- 9. Revision surgery.

#### VI. Substantial Equivalence

| Product | Material | System Components | Function/<br>Design | Indications |
|---------------------------------------------------|------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| SCI<br>BacFix™ ti<br>Spinal<br>Fixation<br>System | Ti-6AL-4V ELI<br>(ASTM F-136)<br>or Ti-6AL-7Nb<br>(ASTM F-1295)<br>& unalloyed<br>titanuium<br>(ASTM F-67) | Rods (hard and soft<br>- various lengths)<br>Hooks (laminar,<br>pedicle, lumbar –<br>right and left),<br>Rod links/wedges<br>(various sizes and<br>lengths)<br>Screws (angled,<br>straight, various<br>sizes and | Bilateral, dual<br>spinal rods<br>connected with<br>transverse rod<br>linkages.<br>Spinal rods are<br>attached to<br>thoracic &<br>lumbar spine<br>with hooks &<br>to sacral spine | When intended for pedicle screw fixation, the<br>implants are intended for use in Grade 3 and 4<br>spondylolisthesis at L5-S1, utilizing autologous<br>bone graft, having the device fixed or attached<br>to the lumbar and sacral spine and intended to<br>be removed after solid fusion is attained.<br>Levels of pedicle screw attachment for this<br>indication range from L3 to the sacrum.<br>When intended for non-pedicle, posterior screw<br>fixation, the system is intended for hook and/or<br>sacral/iliac screw fixation from the thoracic spine<br>to the ileum/sacrum. The indications are: 1.<br>Idiopathic scoliosis, 2. Neuromuscular |

{2}------------------------------------------------

| | diameters) | with screws | scoliosis/kyphoscoliosis with associated<br>paralysis or spasticity, 3. Scoliosis with<br>deficient posterior elements such as that<br>resulting from laminectomy or myelo-<br>meningocele, 4. Spinal fractures (acute<br>reduction or late deformity), 5.Degenerative<br>disc disease(back pain of discogenic origin with<br>dgeneration of the disc confirmed by history<br>and radiographic studies). 6.Neoplastic disease,<br>7. Spondylolisthesis, 8. Spinal stenosis,<br>9. Revision surgery. |
|-----------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| SCI BacFix<br>Spinal<br>Fixation<br>System<br>(K964404) | Rods (hard and soft<br>- various sizes and<br>lengths)<br>Hooks (laminar,<br>pedicle, lumbar -<br>right and left),<br>Rod links/wedges<br>(various sizes and<br>lengths)<br>Screws (angled,<br>straight, various<br>sizes and<br>diameters) | Bilateral, dual<br>spinal rods<br>connected with<br>transverse rod<br>linkages.<br>Spinal rods are<br>attached to<br>thoracic &<br>lumbar spine<br>with hooks &<br>to sacral spine<br>with screws | Same as above |
| Synthes<br>Universal<br>Spine<br>System<br>(K921948)<br>(K922855),<br>(K943725)<br>may all<br>apply in<br>part. | Rods (hard and<br>soft-various sizes<br>and lengths),<br>Hooks (laminar,<br>pedicle, lumbar,<br>transverse process),<br>rod collar,<br>transverse bars,<br>Screws (various<br>sizes and<br>diameters) | Bilateral, dual<br>spinal rods<br>connected with<br>transverse rod<br>linkages.<br>Spinal rods are<br>attached to<br>thoracic &<br>lumbar spine<br>with hooks &<br>to sacral spine<br>with screws | Intended for correction of anterolateral lordotic<br>deformities of the spine, scoliosis,<br>pseudarthrosis and fracture or dislocation of the<br>thoracolumbar spine (T8-L5). |
| | 316L Stainless<br>Steel & 22-13-5<br>Stainless Steel | | |
| | Ti-6AL-7NB &<br>CP (chemically<br>Pure) titanium | | |

#### VII. Mechanical Testing

Static and fatigue testing was performed on the BacFix™ ti and the existing, BacFix™ Systems. These data were compared with published data of various other hook, rod and screw spinal fixation systems. The results of this testing demonstrated the BacFix™ ti to be substantially equivalent to the BacFix™ and the Synthes Universal Spine System and able to withstand clinical loading and maintain mechanical integrity.

#### VIII. Conclusion

The BacFix™ ti Spinal Fixation System is considered to be substantially equivalent in design, material and function to the existing BacFix™ System and the Synthes Universal Spine System.

{3}------------------------------------------------

Image /page/3/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a circular seal with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES • USA" around the perimeter. Inside the circle is an abstract symbol featuring three stylized human profiles facing to the right, representing health and human services.

Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

MAR 1 8 1998

Ms. Teena M. Auqostino Director Regulatory and Clinical Affairs Spinal Concepts, Inc. 8200 Cameron Road, Suite B-160 Austin, Texas 78754

Re : K973687 BacFix™ ti Spinal Fixation System Requlatory Class: II Product Codes: MNH and KWP Dated: January 7, 1998 January 8, 1998 Received:

Dear Ms. Augostino:

We have reviewed your Section 510(k) notification of intent to market the device system referenced above and we have determined the device system is substantially equivalent (for the indications for use stated in the enclosure) to device systems marketed in interstate commerce prior to May 28, 1976 or to devices that have been reclassified in accordance with the provisions of the Federal, Food, Drug, and Cosmetic Act This decision is based on your device system being (Act). found equivalent only to similar device systems labeled and intended for patients: (a) having severe spondylolisthesis (Grades 3 and 4) of the fifth lumbar - first sacral (L5-S1) vertebral joint; (b) who are receiving fusions using autogenous bone graft only; (c) who are having the device fixed or attached to the lumbar and sacral spine; and (d) who are having the device removed after the development of a solid fusion mass. You may, therefore, market your device system subject to the general controls provisions of the Act and the limitations identified below.

The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Note that labeling or otherwise promoting this device system for pedicular screw fixation/attachment for indications other than severe spondylolisthesis, as described above, would cause the device system to be adulterated under 501(f)(1) of the Act.

{4}------------------------------------------------

Page 2 - Ms. Teena M. Augostino

This device system, when intended for pedicular screw fixation/attachment to the spine for indications other than severe spondylolisthesis, as described above, is a class III device under Section 513(f) of the Act. Class III devices are required to have an approved premarket approval (PMA) application prior to marketing. Accordingly:

- All labeling for this device, including the package 1. label, must state that there are labeling limitations. The package insert must prominently state that the device system using pedicle screws is intended only for patients: (a) having severe spondylolisthesis (Grades 3 and 4) of the fifth lumbar - first sacral (L5-S1) vertebral joint; (b) who are receiving fusions using autogenous bone graft only; (c) who are having the device aussychous bone grain the lumbar and sacral spine; and (d) who are having the device removed after the development of a solid fusion mass.
- You may not label or in anyway promote this device system 2. for pedicular, screw fixation/attachment to the cervical, thoracic or lumbar vertebral column for intended uses other than severe spondylolisthesis, as described above. The package insert must include the following statements:

### WARNINGS :

- When used as a pedicle screw system, this device . system is intended only for grade 3 or 4 spondylolisthesis at the fifth lumbar - first sacral (L5-S1) vertebral joint.
- . The screws of this device system are not intended for insertion into the pedicles to facilitate spinal fusions above the L5-S1 vertebral joint.
- . Benefit of spinal fusions utilizing any pedicle screw fixation system has not been adequately established in patients with stable spines.
- . Potential risks identified with the use of this device system, which may require additional surgery, include:

. . . . . . . . . . . . . . . . .

device component fracture, loss of fixation, non-union, fracture of the vertebra, neurological injury, and vascular or visceral injury.

{5}------------------------------------------------

See Warnings, Precautions, and Potential Adverse Events sections of the package insert for a complete list of potential risks.

- Any pedicular screw fixation/attachment for intended uses 3. other than severe spondylolisthesis, as described by item 1, for this device is considered investigational and may only be investigated as a significant risk device in accordance with the investigational device exemption (IDE) regulations under 21 CFR, Part 812. All users of ('D') for pedicular screw fixation/attachment for intended uses other than severe spondylolisthesis, as described above, must receive approval from their respective institutional review boards (IRBs) and the Food and Drug Administration (FDA) prior to conducting an investigation.
- Any previous warning statements identified as part of 4 . previous 510(k) clearances or required by OC/Labeling and Promotion which stated that a component/system was not approved for screw fixation into the pedicles of the spine must be replaced by the warnings of items 1 and 2 above.

If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the current Good Manufacturing Practice requirement, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic (QS) inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory In addition, FDA may publish further announcements action. concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections -531 ---through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal Laws or Regulations.

FDA advises that the use of your device system with any other device components but those identified in this 510(k) would require submission of a new 510(k) providing documentation of design, material, and labeling compatibility between the device components. Mechanical testing of a spinal system consisting of the subject device components and other device components, whether yours or those of other manufacturers, may also be required.

{6}------------------------------------------------

Page 4 - Ms. Teena M. Augostino

This letter will allow you to begin marketing your device as described in your 510(k) premarket notification immediately. An FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and permits your device to proceed to the market.

If you desire specific advice for your device on our labeling requlation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at [phone]. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at [phone]. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number [phone] or [phone] or at its Internet address "http://www.fda.gov/cdrh/dsmamain.html".

Sincerely yours,

Russell T. Legume

Celia M. Witten, Ph.D., M.D. Director Division of General and Restorative Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

{7}------------------------------------------------

## INDICATION FOR USE STATEMENT

Page 1 of 2

510(k) Number (if known):

K973687

Device Name:

Spinal Concepts, Inc. BacFix™ ti Spinal Fixation System

Indications for Use: The Spinal Concepts, Inc. BacFix™ ti Spinal Fixation System consists of a combination of components which include rods, hooks, locking wedges, screws and transverse connectors which are indicated to provide temporary stability of the thoracic, thoracolumbar or lumbar spine (T1-SI).

> When intended for pedicle screw fixation, the implants are intended for use in Grade 3 and 4 sponylolisthesis at L5-S1, utilizing autologous bone graft, having the device fixed or attached to the lumbar and sacral spine and intended to be removed after solid fusion is attained. Levels of pedicle screw attachment for this indication range from L3 to the sacrum.

> > (Continued on next page)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)

Prescription Use: (Per 21 CFR 801.109) Or

Over-The-Counter (Optional Format 1-2-96)

Mark M. Melkerson

(Division Sign-Off)
bomw Com Division of General Restorative Devices
510(k) Number. K97

{8}------------------------------------------------

When intended for non-pedicle, posterior screw fixation, the system is intended for hook and/or sacral/iliac screw fixation from the thoracic spine to the ileum/sacrum. The indications are:

- Idiopathic scoliosis. 1.
- Neuromuscular with associated 2. paralysis or spacticity.
- Scoliosis with deficient posterior elements such as that resulting 3. from laminectomy or myelomeningocele.
- Spinal fractures (acute reduction or late deformity). 4.
- Degenerative disc disease (back pain of discogenic origin with ર. degeneration of the disc confirmed by history and radiographic studies).
- Neoplastic disease. 6.
- 7. Spondylolisthesis.
- Spinal stenosis. 8.
- Revision surgery. 9.