With social and economic development, societal aging has become an irreversible global trend in the 21st century. In 2016, the average life expectancy reached 76 in China(11). As a result, the prevalence of degenerative LSS is increasing. However, chronic pain and discomfort from LSS may significantly impair psychosocial function and induce sleep disorders, depressive symptoms, and increased utilization of health care(12). In recent years, PE has become the most minimally invasive treatment for lumbar degenerative disease, its indications are constantly being expanded, and it has proven efficacy for LSS(10, 13). For elderly patients with LSS, while traditional surgical treatment can achieve extensive decompression and pain relief, it is associated with high risk and long recovery before resuming normal activities, and it takes longer to improve the quality of life. Elderly patients often have severe and complex underlying diseases, which exacerbate surgical risks and problems such as reduced spinal stability, prolonged bed rest, high complication rate, and high costs(14).
In this study, analysis of early efficacy showed that PE had the following advantages in elderly patients with LSS: (1) more extensive anesthesia indications and low risk from general or local anesthesia, low intraoperative blood loss, short operation time, and minimal intraoperative fluctuations in blood circulation; (2) minimal damage to the bone structure (only part of the thickened ligamentum flavum, protruding intervertebral disc tissue, and osteophytes on the medial side of the facet were removed during operation) and minimal impact on the stability of the posterior spine; (3) short postoperative bed rest and low complication rate (no postoperative infection or deep venous thrombosis was observed in this study); (4) effective relief of back/lower-extremity pain, with significant improvement in VAS and JOA scores on postoperative day 1 and at the last follow-up visit; (5) a short hospital stay, satisfactory improvement in symptoms after the operation, emonstrated efficacy, and low cost; and (6) age is not a contraindication for decompressive lumbar spine surgery.
3.1 Physiological characteristics and surgical options for elderly patients with LSS
Elderly patients with LSS often have the following physiological and clinical characteristics: (1) LSS is characterized by degenerative changes such as facet joint hyperplasia and cohesion and ligamentum flavum hypertrophy due to long-term back pain–associated adverse lumbar stress and compensatory lumbar hyperplasia, as well as slow onset and prolonged disease course. Multiple segments are involved in most cases, and lumbar spondylolisthesis and scoliosis are observed in some cases. However, the symptoms of nerve injury are often inconsistent with imaging findings, and the location of affected segments is not clear. (2) Elderly patients have varying degrees of severe and complex underlying disease, which limits treatment options and significantly increase s the surgical risk and postoperative complication rate. (3) Elderly patients often have general organ insufficiency, requiring more complex perioperative management. Moreover, they are prone to incision infection or delayed healing, pulmonary infection, urinary infection, and gastrointestinal disorders after anesthesia and operation due to poor nutrition status and low immunity, which severely affect the postoperative efficacy. Therefore, for elderly patients with LSS, the goal of surgical treatment is to decompress completely while maintaining spinal stability. Moreover, depending on the patient’s physical condition, it is important to reduce anesthesia and operation time and minimize surgical trauma. While traditional surgical treatment can achieve extensive decompression and pain relief, it takes a long time for patients to resume normal activities and to improve the quality of life. Elderly patients often have severe and complex underlying diseases and are thus at increased risk for open surgery, reduced spinal stability, prolonged bed rest, high complication rate, and high costs(5, 6). With the continuous advancement and development of PE, many researchers in China and abroad believe that PE is a safe and minimally invasive spinal technology with low blood loss, minimal postoperative scars, minimal nerve adhesions, minimal impact on the stability of the posterior spine, fast postoperative recovery, and the option of local anesthesia(8, 9, 15). Therefore, PE can achieve the goal of "targeted and precise" decompression, while maintaining spine stability and minimizing surgical trauma. This study showed that PE achieved satisfactory outcomes with fast postoperative recovery and low complication rate in elderly patients.
3.2 Is postdecompression fusion always required during the surgical treatment of lumbar spinal stenosis?
Researchers still debate the need for spinal fusion after decompression in LSS patients. In some cases, LSS is accompanied by degenerative spondylolisthesis. Many spine surgeons regard this as an absolute indication of fusion. Spinal surgery may impose a high risk of degenerative spondylolisthesis, and many surgeons therefore believe that performing fusion after decompression is the best course of action(16-18), However, no evidence is available to support any benefits of fusion in LSS patients without spondylolisthesis(19, 20). Several prospective studies with ≥ 5-year follow-ups(20, 21) have demonstrated better clinical results in cases without spinal fusion because spinal fusion may promote degeneration of adjacent segments and lead to a higher revision rate. Forsth et al(22) conducted a large retrospective analysis of 8,785 eligible patients. Patients who were lost to follow-up and who were followed up for less than 2 years were excluded from the analysis. A total of 5,390 patients were included in the analysis. The analysis included patients with or without lumbar spondylolisthesis before operation. Various measures were evaluated during postoperative follow-up. The 2-year follow-up showed no significant difference in various clinical measures between the decompression group and the fusion group, regardless of the presence of lumbar spondylolisthesis before operation. Moreover, the incidence of reoperation due to recurrent spinal stenosis or spinal instability was similar in the two groups (decompression group: 7%, fusion group: 8.1%). Lad et al(23) conducted a retrospective cohort analysis and found that the 90-day complication rate after initial admission was significantly higher in the decompression-plus-fusion group than in the decompression-alone group, with no significant between-group difference in the revision rate during the ≥ 5-year follow-up. In addition, decompression plus fusion prolonged hospital stay and was associated with higher blood loss and costs. Other studies reached different conclusions regarding the reoperation rate. Ghogawala et al(24) conducted a randomized clinical trial to investigate the efficacy of lumbar decompression plus fusion versus lumbar decompression alone for the treatment of grade Ⅰ lumbar degenerative spondylolisthesis with spinal stenosis and found no significant difference in the Oswestry Disability Index (ODI) at 2 years after the operation between the groups. However, blood loss, hospital stay, and hospitalization costs were significantly higher or longer in the decompression-plus-fusion group than in the decompression-alone group. The reoperation rate was 14% and 34%, respectively. Some researchers believe that the high reoperation rate in the decompression-alone group was due to the clinical decision about revision, as surgeons are more inclined to perform spinal fixation in the case of unsatisfactory decompression alone but are less likely to perform revision in the case of unsatisfactory decompression plus fusion. These data indicate that fusion is probably no longer the best treatment for LSS. Further research is needed to investigate whether internal fixation is appropriate or necessary for LSS.
3.3 Surgical strategies for PE in elderly patients with LSS
PE has become the most minimally invasive treatment of lumbar degenerative diseases. However, precise decompression is critical due to its limited operating field. It is important to perform a comprehensive assessment of imaging studies and physical examination before operation in order to develop an individualized treatment plan. We believe that for elderly patients, the lumbar spinal canal is often associated with hypertrophic ligamentum flavum, facet joint hyperplasia, and lateral recess stenosis. Moreover, the degree of spinal canal stenosis on imaging findings is often discordant with the severity of clinical conditions. Therefore, in this study, the transforaminal approach was used in elderly patients whose primary symptom was lower-extremity radiating pain due to disc herniation and lateral recess stenosis, and the interlaminar approach was used in patients with long-term intermittent limping with central LSS on imaging studies for thorough decompression. For patients with long-term mild to moderate intermittent limping and recent severe lower-extremity radiating pain due to lateral disc herniation, the transforaminal approach was used under local anesthesia with good clinical efficacy. The selection of the specific approach is also related to the location of the affected segment. L5/S1 is usually blocked by the high crest, which hinders the placement and adjustment of a transforaminal channel. Therefore, for patients with L5/S1 spinal canal and high crest, the interlaminar approach was used under general anesthesia. During decompression, some of the thickened ligamentum flavum and protruding intervertebral disc tissue should be removed, and the osteophytes and calcified tissues at the edge of the lamina and the medial side of the facet should be polished to achieve thorough decompression of the spinal canal and/or neural tube. Percutaneous endoscopic lumbar spinal decompression is a minimally invasive surgical technique that is continuously developing, and it has a steep learning curve. The requirements for endoscopic skills are higher for the treatment of elderly patients with LSS than for lumbar disc herniation.
This study has some limitations due to its design and follow-up time. This is a retrospective analysis of data collected from a database to evaluate the safety and effectiveness of PELD for the treatment of LSS in elderly patients aged 65 or over. Due to the special characteristics and the high threshold for surgical treatment of elderly patients, we only included patients with single-segment LSS and excluded patients with apparent lumbar instability or multisegment stenosis. In addition, the present study lacked a control group of patients who received either conservative management or open surgery. Moreover, the sample size was small, so it may not have covered all possible complications, such as perioperative cardiac events and death. In addition, the follow-up time was short, and the long-term efficacy of minimally invasive surgery for LSS was confirmed only in some patients with a longer follow-up time.
In summary, with the rapid development of minimally invasive technology, spinal endoscopic techniques enable individualized treatment plans for LSS. For elderly LSS patients with severe and complex underlying diseases, PELD is undoubtedly a better option, with recognized advantages such as a short operation time, a low surgical risk, minimal impact on spinal stability, a fast postoperative recovery, and proven efficacy. Patients who were previously considered ineligible for lumbar spinal surgery may be qualified for this treatment. Thus, more elderly patients will have an opportunity to undergo minimally invasive treatment for LSS and experience improved quality of life. Our results may help surgeons better understand and perform minimally invasive lumbar decompression in elderly patients.