Relationship between interlaminar angle and the superior articular process removal range in patients with lumbar disc herniation during Percutaneous Endoscopic Interlaminar Discectomy: a cross-sectional study

Abstract Objective: Explore the relationship between the superior articular process removal range (SAPR) during Percutaneous Endoscopic Interlaminar Discectomy （PEID）and the interlaminar angle (ILA). In addition, we assessed the relationship between other imaging parameters and surgical difficulty. Methods: Collect the data of 237 patients who underwent PEID at Qilu Hospital of Shandong University. Measure the imaging data, such as ILA, facet angle (FA), facet joint medial distance (FMD), and the SAPR, and compare their statistical difference. Results: SAPR is negatively related to ILA(P<0.05). For patients with the L4/L5 segment operation, the average SAPR is 6.15±3.02mm. The SAPR of the patients with surgical segment ILA of 47.50-72.52° was 9.06±1.70mm. That of the patients with surgical segment ILA of 72.71-86.06° was 7.30±1.22mm. That of the patients with surgical segment ILA of 86.31-96.37° was 6.50±1.48mm. That of the patients with surgical segment ILA of 97.10-118.68° was 1.86±1.17mm. For patients with the L5/S1 segment operation, the average SAPR is 4.81±2.17mm. The SAPR of the patients with surgical segment ILA of 54.48-86.22° was 7.22±0.79mm. That of the patients with surgical segment ILA of 87.30-98.60° was 5.72±1.06mm. That of the patients with surgical segment ILA of 98.80-107.06° was 4.43±0.90mm. That of the patients with surgical segment ILA of 108.53-141.00° was 1.98±1.26mm. Interestingly, the ILA is also closely related to the operation time and operation difficulty score(P<0.05). Conclusions : Smaller ILA tends to be associated with more SAPR during the PEID. In addition, The smaller the ILA, the more difficult it is to expose the key anatomical structures, which leads to an increase in operation difficulty and longer operation time.