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B-Twin Sliding Implant for Spinal Fixation

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A sliding B-Twin implant is placed in the intervertebral space when performing spondylodesis with bone allo- or autografts in patients with degenerative changes in the intervertebral discs (including in combination with grade I spondylolisthesis) at one or two levels from L2 to S1. The operation is performed openly through a posterior or anterior approach, or percutaneously through a posterolateral approach.

The B-Twin implant operation is placed in the intervertebral space.

 

Description of the implant

The disclosed B-Twin implant has a lordosis configuration, that is, a trapezoidal cross-sectional shape. The implant length is standard - 25 mm, and the diameter can be different. The diameter is chosen depending on the height of the intervertebral space at the level of the lesion. For this, before the operation, an X-ray of the spine in frontal and lateral projections, CT, or MRI is performed. The diameter of the implant should be 10–20% greater than the height of the intervertebral space, and the length should be at least 3 mm less than the anteroposterior size of the vertebral bodies.

After the discectomy and the destruction of the endplates, it is necessary to re-confirm whether the implant size is correct. To do this, use the measuring instruments that are supplied with the implant. The rectangular curette allows you to assess whether the diameter is correctly selected (it is used during open surgery). Correspondence of the implant length to the anteroposterior size of the vertebral bodies is checked using a measuring template, which has the same length as the implant itself.

The implant is placed in the intervertebral space in a folded state (in the form of a rod with a diameter of 5 mm) using a special device. It also allows, after installation, to push metal segments out of the rod - teeth. Two implants are placed in one intervertebral space.

 

Indications

Indications for the use of the B-Twin sliding implant surgery are determined by the attending physician in the following cases:

  • degenerative changes in the intervertebral discs at one or two levels from L2 to S1
  • age over 18 years, cessation of growth (end of skeletal maturation)
  • the X-ray data on the level of the lesion corresponding to the data of the physical examination
  • the neurologic findings are consistent with CT or MRI findings and physical findings; in the absence of neurological disorders, a test is performed with the introduction of a contrast agent into the intervertebral disc (discography)
  • debilitating back pain, significantly limiting physical activity
  • ineffectiveness of conservative treatment (physiotherapy exercises, drug treatment, ultrasound therapy, treatment in a specialized clinic) during the previous 6 months.

In addition, the implant can be installed in the following cases:

  • surgical treatment of severe damage to the intervertebral disc, surgical decompression (laminectomy, resection of the articular process, foraminotomy)
  • repeated surgery on the intervertebral discs (if the previous operation was unsuccessful), surgery for recurrent disc herniation and instability of the intervertebral joint; the implant is not installed if fusion has already been performed at the level of the lesion
  • lumbar spinal stenosis
  • spondylolytic or degenerative spondylolisthesis of the 1st degree (including after correction of spondylolysis of a higher degree)

 

Counterindications

  • metabolic bone damage
  • neurofibromatosis type II or tumors of the spinal cord and spine in the patient himself or his relatives
  • acute spinal cord injury
  • congenital or acquired osteodystrophies (Paget's disease, renal osteodystrophy), thyrotoxicosis, hypothyroidism, Ehlers-Danlos syndrome, osteogenesis imperfecta, achondroplasia, a history of tuberculosis
  • severe osteomalacia and osteoporosis, in which interventions on the spine are contraindicated
  • pregnancy
  • immunodeficiency
  • infection in the operation area, discitis, osteomyelitis, fever, leukocytosis, increased erythrocyte sedimentation rate (ESR)
  • malignant neoplasms
  • treatment with drugs that affect bone metabolism:
    • the use of prednisone in a total dose of 150 mg or other glucocorticoids in an equivalent dose during the last 6 months.
    • Calcitonin use within the last 6 months
    • use of diphosphonates for 30 days or longer in the past 12 months.
    • the use of fluoride preparations in therapeutic doses for 30 days. or longer in the past 12 months.
    • the use of vitamin D preparations in therapeutic doses for 30 days. or longer in the last 6 months.
  • chemotherapy in the last 12 months
  • alcoholism, drug addiction
  • severe obesity
  • scoliosis
  • allergy to metals