This is a multicenter, prospective cohort study. The osteoporotic patients requiring posterior lumbar interbody fusion(LIF) with cages are prospectively enrolled and followed up. The patients undergoing LIF with the biomechanical-matched 3D-printed titanium cages (Osteo Match) are compared with those using routine PEEK cages. The hypothesis is that the use of Osteo Match cages can reduce the rate of cage subsidence and increase the rate of lumbar fusion in osteoporotic patients.

Interbody fusion cages are widely used for the surgical treatment of degenerative lumbar diseases, which can stabilize the spine and promote solid fusion. However, because of population aging and the high rate of osteoporosis in the elderly with lumbar degenerative diseases, the cage subsidence and failure of fusion have been frequently reported. The biomechanical strength (such as elasticity modulus) of routine PEEK cages is mismatched with osteoporotic bone, leading to cage subsidence and nonunion.

The 3D-printed porous titanium alloy cages have been proved to have advantages in speeding up and enhancing the lumbar fusion over conventional PEEK cages. However, most of the titanium cages still have much higher biomechanical strength than the osteoporotic bone. The new titanium cages named Osteo Match has been first clinically used in Peking University Third Hospital in China. The elastic modulus of Osteo Match cage is matched with that of lumbar spine with different degrees of osteoporosis. Therefore, we hypothesize that patients undergoing LIF with Osteo Match cages can achieve lower rate of cage subsidence and higher rate of lumbar fusion than those using PEEK cages.

The osteoporotic patients requiring posterior lumbar interbody fusion with cages are prospectively enrolled and followed up. The researchers will invite appropriate patients to participate in the study after their surgical plans are determined. General patients data are collected after informed consent, such as age, gender, weight, height, bone mineral density (measured by DXA, CT Hounsfield units, or QCT), detailed surgical plans, and etc. They are followed up at 3, 6, 12, and 24 months according to our clinical routine, including lumbar x-ray, CTand certain questions about the clinical outcomes.

The patients used Osteo Match cages are compared with those using conventional PEEK cages. The primary endpoints are the subsidence rate and fusion rate at 6 months follow-up. The secondary endpoints are the subsidence rate and fusion rate at other time point of follow-up , and the clinical outcomes(ODI/JOA/VAS) at every follow-up.

Inclusion Criteria:

• aged≥ 50 years old
• lumbar degenerative diseases requiring lumbar fusion with pedicle screw fixation, such as degenerative lumbar spinal stenosis, degenerative lumbar spondylolisthesis.
• no response to nonoperative treatment of at least 3 months
• osteoporosis diagnosed by any method for bone mineral density evaluation, such as DXA, QCTor CT Hounsfield units
• requiring lumbar interbody fusion with cages within L3-S1
• the type of fusion cage has been chosen by the patients
• informed consent

Exclusion Criteria:

• the surgical plan includes any unconventional techniques used to strengthen the fixation, such as augmentation of the pedicle screw with bone cement
• lumbar spondylolisthesis of ≥II degree
• lumbar scoliosis of >20° or imbalance of spinal alignment
• history of lumbar fusion surgery
• cervical myelopathy, thoracic spinal stenosis, motor neuron disease,tuberculosis of spine,spinal tumor
• vertebral fracture within interbody fusion segement
• ASA of ≥IV

The osteoporotic patients requiring lumbar interbody fusion with cages for lumbar degenerative diseases are invited to participate in the study.