The original PLIF procedure was performed after posterior decompression or/and nucleus pulposus removal, and bone grafting was performed in the fused intervertebral space to achieve interbody fusion. In order to overcome the disadvantages of bone graft resorption, narrowing of the vertebral space and long postoperative bed rest, various types of interbody fusion devices that are more suitable for the anatomical or pathological structure of the vertebral space have been improved. Indications: (1) severe lower back pain caused by degenerative changes in the lumbar spine that has failed after more than one year of conservative treatment; (2) discogenic back pain with or without neurogenic pain; (3) spondylolisthesis within the range of Ⅰ to Ⅱ degrees; (4) the height of the pre-fused intervertebral space must be less than 12 mm; (5) failure after disc removal; no loss of intervertebral space, infection, or degenerative changes in the adjacent intervertebral space. Surgical procedure (L5-S1 segment surgery as an example) A posterior median lumbar incision is made to reveal the L5-S1 vertebral plates and small joints bilaterally. About 1/2 of each of the upper and lower laminae of the L5 to S1 vertebral body is excised, and the medial 1/2 of the small joint is excised on both sides, and the interlaminar ligament is excised to reveal the dural sac and nerve roots. The dural sac and nerve roots are gently retracted with a nerve puller to reveal the intervertebral disc, the annulus fibrosus is cut and the disc is removed, and the cartilage plate above and below the disc is scraped with an annular scraper to reveal the end plate of the vertebral body. A suitable type of intervertebral fusion device is determined with the intervertebral fusion trial body, and the resected plate is crushed and filled into the anterior part of the vertebral space, and the fusion device filled with crushed bone is implanted into the vertebral space, or a suitable height of autologous bone is taken and implanted into the vertebral space. Pedicle screws are screwed into the L5-S1 vertebral body, and compression fixation is applied between the pedicle screws. Our clinical approach is often combined with TLIF practice, which often occludes the articular eminence on one side so that complete neurological decompression can be achieved, reducing the strain on the nerve roots and dural sac when placing the fusion, and placing one fusion is sufficient, preserving the contralateral articular eminence for posterior bone graft fusion. Therefore, our surgical approach should be called PTLIF or modified TLIF surgery, Case presentation: Male. 64 years old, low back pain with right lower extremity soreness and numbness for one year, aggravated for one week, admitted to the hospital with significant L5 nerve root damage on examination, significant spinal stenosis and lumbar disc herniation (L4/5) on imaging; posterior lumbar decompression interbody fusion was performed.