A comparison of long-term efficacy of K-rod-assisted non-fusion operation and posterior lumbar interbody fusion for single-segmental lumbar disc herniation
Authors: Cheng Xueliang , Qu Yang , Dong Rongpeng , Kang Mingyang , Zhao Jianwu 
Published: March 2021

Abstract
BACKGROUND Since the development of internal fixation, posterior lumbar interbody fusion (PLIF) surgery has become the gold standard for the treatment of lumbar disc herniation. Although it has good short-term clinical efficacy, it can result in problems such as postoperative intractable lower back pain and degeneration of adjacent segments. K-rod-assisted non-fusion surgery for the treatment of lumbar disc herniation has also been proven to have clinical efficacy; however, its long-term effects have not been examined.AIMTo compare the long-term clinical efficacy of K-rod-assisted non-fusion operation to the clinical efficacy of PLIF in the management of single-segment lumbar disc herniation.METHODSThis study retrospectively analyzed 22 patients with lumbar disc (L4/5) herniation who underwent K-rod-assisted non-fusion operation (n=13) or PLIF (n=9) between December 2010 and December 2013 and were followed-up for more than 5 years. Clinical outcomes were evaluated by the Oswestry Disability Index (ODI), pain Visual Analogue Score (VAS), and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). Imaging evaluations included adjacent segmental intervertebral height, range of motion (ROM) of the vertebrae, incidence of lumbar instability, spino-pelvic parameters, Pfirrmann grading, Modic changes, and University of California Los Angeles (UCLA) grading.RESULTS Clinical outcomes, namely operation times (110.5±11.15 min vs. 134.44±12.36 min, P <0.05) and blood loss (59.2±7.03 ml vs. 80.0±8.66 ml, P <0.05), were significantly reduced in the K-rod group compared to the PLIF group. At the last follow-up, the clinical outcomes of the K-rod group were improved compared to those of the PLIF group as observed by the VAS score (2.1±0.9 vs. 3.0±0.7, P <0.05), JOABPEQ (26.7±1.1 vs. 25.2±1.5, P <0.05), and ODI (21.0±3.7 vs. 28.4±6.9, P <0.05). Imaging outcomes at the last follow-up indicated that the loss of height in the L3/4 intervertebral space (0.4±0.9 mm vs. 1.5±0.7 mm, P <0.05) and L5/S1 intervertebral space (0.2±0.5 mm vs. 1.8±1.7 mm, P <0.05), the ROM of L3/4 (4.9±2.0 vs. 8.8±2.4, P <0.05), the ROM of L5/S1 (5.7±1.7 vs. 8.6±1.2, P <0.05), and the incidence of adjacent segment degeneration (7.7% vs. 38.9%, P <0.05) in the PLIF group were significantly higher than those in the K-rod group. According to Pfirrmann grading, Modic changes, and UCLA grading, the incidence of adjacent segment degeneration was 55.6% in the PLIF group and 15.4% in the K-rod group. Changes in spino-pelvic parameters between the two groups were as follows: pelvic index remained unchanged, pelvic tilt angle increased, and lumbar lordosis and sacral slope decreased.CONCLUSIONCompared to PLIF, single-segment lumbar disc herniation using K-rod-assisted non-fusion surgery resulted in better long-term clinical efficacy. Our results demonstrate that this procedure can delay adjacent segment degeneration after lumbar surgery.