A Comparative Study Between Mechanical and a Viscoelastic Disc Prosthesis in the Lumbar Spine

A Randomized Controlled Study Between Mechanical and a Viscoelastic Disc Prosthesis in the Lumbar Spine. A Comparison on Clinical Outcome and Facet-joint Load Between Two Different TDR Designs.

TDR implants for the lumbar spine are currently most 2- or 3-piece devices with a purely mechanical function that provide/restore mobility. Lately interest is growing on non-mechanical implants that could possibly provide/restore mobility, but also produce counterforces on mobility as in healthy discs. No previous comparison between these two concepts has been performed, neither on clinical outcome, neither on specific differences on facet-joint load and wear.

A total of 250 patients are to be enrolled and treated. Inclusion criteria is unbearable pain and dysfunction from degenerative disc disease (DDD) that at one or two segments in the lover lumbar spine, that has not responded positively from at least one year of conservative treatment (that is combination of intense physical training and drugs). Patients with DDD below L3 vertebra are divided I three groups: One segment DDD appropriate for treatment with TDR. Two segments DDD appropriate for treatment with TDR. One segment DDD appropriate for treatment with TDR and one segment DDD not appropriate for treatment with TDR, that will be treated with anterior fusion (ALIF) at the same surgical procedure, called "hybrids". Within all three groups there will be an equal randomization between the two prosthesis types. Clinical outcome will be evaluated from questionnaires sent out to patients after 12- and 24 months and 5- and 10 years after surgery. The questionnaire are the currently used ones from the Swedish Spine Registry (SweSpine) including VAS leg/back, EuroQol ,GA and ODI. Complications will be registered continuously and facet-joint load/health will be examined from flex-ext x-rays at 1 and 2 years. At the 2-year check up a 3D-CT will be performed to further evaluate the facet joints and their load under flex-ext.

Surgical procedure with total disc replacement using mechanical disc prosthesis device, "ORBIT, Globus Medical"

Surgical procedure with total disc replacement using viscoelastic disc prosthesis device, "ZACK, FH Orthopaedics"

Surgical procedure with total disc replacement (TDR) using ORBIT disc prostheses device combined with adjacent level anterior intracorporal fusion (ALIF) with intracorporal device SASCA.

Surgical procedure with total disc replacement (TDR) using ZACK disc prostheses device combined with adjacent level anterior intracorporal fusion (ALIF) with intracorporal device SASCA.

Surgical procedure with anterior intracorporal fusion (ALIF) combined with adjacent level total disc replacement (TDR) (using either ORBIT mechanical disc prosthesis or ZACK viscoelastic disc prosthesis)

GA (Global Assessment of back pain, patient-based evaluation of leg and back pain as compared to preoperatively,1-5, 1 disappeared and 5 worsened) ,collected from questionnaires

VAS (Visual Analogue Scale, 0 no pain, 100 worst possible pain) of back and leg,collected from questionnaires

ODI (Oswestry disability index, self-completed questionnaire contains ten topics concerning intensity of pain, lifting, ability to care for oneself, ability to walk, ability to sit, sexual function, ability to stand, social life, sleep quality, and ability to travel, 0-5 zero indicating the least amount of disability and 5 indicating most severe disability)

EuroQol EQ-5D-5L, Self-completed questionnaire regarding mobility, self-care, usual activities, pain/discomfort and anxiety/depression. EQ VAS records the patient's self-rated health on a vertical visual analogue scale, where the endpoints are labelled 'The best health you can imagine' and 'The worst health you can imagine'. The VAS can be used as a quantitative measure of health outcome that reflect the patient's own judgement.

Medical records, questionnaires and further registrations in SweSpine reporting repeat surgery, with a differentiation of the medical reason for that intervention.

Medical records will be evaluated for surgically related complications, death, infection, bleeding, implant loosening, re-operation/revision, neurological complication, thrombosis, implant failure, implant malpositioning/displacement, non-union, incisional hernia, retrograde ejaculation

Inclusion Criteria: Incapacitating pain from DDD (both clinical and radiological) in one or two segments below the L3 vertebra, were at least one segment is suitable for TDR treatment. Patient with more than one year of pain, that has during this period made a prolonged and adequate conservative program. -Patient between 20 and 55 years of age. - -Patient able to understand written and spoken Swedish. Exclusion Criteria: Patient does not accept to be part of the study. Three or more segments suspected to be symptomatic. Earlier vertebral fracture, tumour, infection or fusion in the lumbar spine. -Substantial scoliosis/deformity. Need for posterior decompression. Pregnancy, psychiatric illness or drug abuse. -Patient does not understand written and spoken Swedish and can thus not take part in information and answer questionnaires. -Patient residing outside Sweden and thus is not covered with SweSpine. -