Participants with lumbar spondylosis, degenerative disc disease, spondylolisthesis, scoliosis, or trauma undergoing elective Transforaminal lumbar interbody fusion (TLIF) were recruited. The follow-up period was 24 months for each participant. The eligible patients for this study should be above 18 years old with confirmed indication to TLIF through a posterior approach. Patients with an active infection, symptomatic osteoporosis, immature bone, pregnancy, active malignancy, and previous radiotherapy at the planned surgical site were excluded. Informed consent was signed by each participant before recruitment. We strictly followed the protocols of patient confidentiality and human subjects in the clinical trial implementation. The patients were blinded to the allocated surgical technique before the operation and during the follow-up period of two years. On the one hand, the doctor will assess the patient's physiological function recovery and imaging examinations (such as CT, MRI or X-ray) before and after the operation to understand the changes in the patient's pain index and the effect of intervertebral disc fusion after the operation; on the other hand, It also evaluates the quality of life and the degree of improvement of psychological emotions through the questionnaires of patients before and after surgery.

After receiving prophylactic antibiotics according to the local hospital protocol, the patients were generally anesthetized in a prone position. Paramedian or midline posterior sections were conducted, exposing the lumber vertebras encompassing the facet joints. The facet joints were removed, and decompression was performed. The diseased disc nucleus was then excised before filling in the bone substitutes. For the control group, the bone substitutes were filled in the disc space manually using a bone grafting funnel. In the case of device group, a novel filler tube with integrated threaded rod, which can be connected to a surgical drill, was used for rapid and continuous graft filling (Figure 1). A polyethyletherketone (PEEK) interbody fusion cage was then placed into the disc space followed by fixation with pedicle screws. The treatment efficacy was assessed by clinical analysis based on the visual analogue scale (VAS) for radicular pain and the Oswestry Disability Index (ODI) questionnaire for low back pain. The VAS back and leg pain scores were measured preoperatively and postoperatively at 1, 3, 6, 12, and 24 months. The ODI questionnaires were taken preoperatively and postoperatively at 3, 6, 12, and 24 months. The bone graft delivery volume and the filling time during the surgery were measured to compare the efficiency of the two approaches.

The X-ray and computed tomography were performed prior to surgery and at 3-, 6-, 12-, and 24-monthspost-surgery for bone fusion assessment. The degree of bone fusion was classified into three grades. Grade I was defined as a complete fusion, union case, and grade II and III was defined as a partial union and a non-union case, respectively. Bone fusion volume was further determined by three-dimensional reconstruction images using ITK-SNAP software

Inclusion Criteria:

spinal fusion procedures in skeletally mature patients with Degenerative Disc Disease (DDD) at one or two contiguous levels from L2 to S1. DDD is defined as discogenic back pain with degeneration of the disc confirmed by history and radiographic studies. These DDD patients may also have up to Grade I spondylolisthesis or retrolisthesis at the involved levels. Patients should have had six months of non-operative treatment prior to treatment with an intervertebral body fusion device.

Exclusion Criteria:

• Patients unsuitable for anesthesia
• Active systemic infection, infection or suspected latent infection localized to the site of the proposed implantation
• Excessive local inflammation
• Rapid joint disease, bone absorption, osteopenia
• Severe osteoporosis or osteopenia
• Morbid obesity
• Pregnancy
• Open wounds
• Patients have demonstrated allergy or foreign body sensitivity to any of the implant materials
• Any medical or surgical condition which would preclude the potential benefit of spinal implant surgery, surgery, such as the presence of tumors, congenital abnormalities, elevation of sedimentation rate unexplained by other diseases, elevation of white blood cell count (WBC), or marked left shift in the WBC differential count
• Patients whose activity, mental capacity, mental illness, alcoholism, drug abuse, occupation, or lifestyle may interfere with their ability to follow postoperative restrictions and who may place undue stresses on the implant during bony healing and may be at a higher risk of implant failure
• Any patient in which implant utilization would interfere with anatomical structures or expected physiological performance
• Any condition not described in the indications for use