In the elderly population, low back pain is a very common healthissue. Degenerative lumbar stenosis is one of the most commoncauses of these conditions.Randomized trials indicate that for symptomatic LSS patients, decompression offers greater efficacy than nonsurgical treatments. However, the effect of ageas an independent risk factor is well understood, it has beenrelated to an increased risk of morbidity after open spine surgery.Other studies havefound morbidity andcomplication rates were higher in elders comparedwith younger patients after spine surgery, and this finding might be due to the highprevalence of multiple medical comorbidities in this aged group[9, 10].Therefore, it is very important to make a choice which surgical procedure is appropriate, especially in geriatric patients ,for whom the surgical challenge is their physical, psychologic, and social frailty. For this reason,simple Minimally invasive surgical (MIS) decompression surgery methods were preferred to decreasemorbidity and mortality rates.
MIS approaches involvemuscle-splitting techniques to access the spine, leavingintact the midline structures that support muscles andligamentsand decreasing intraoperative blood loss andpostoperative pain. One such recently described MIStechnique is unilateral laminotomy for bilateral decompression (ULBD). This technique uses the microendoscopictubular-retractor system to preserve the facet joints and neural arch ofthe contralateral side, limits postoperative destabilization, andprotects the neural structures from extensive trauma.Ang et al, retrospectively reviewed the outcomes of 113 patients, measured by VAS for back and leg pain, the North American Spine Society score on neurogenic symptoms, found they were comparable between the ULBD and the open lumbar laminotomy groups,but ULBD was associated with the lower blood loss, the shorter hospital stay, the lower percentage of complications and the need for revisions.Although other studies have confirmed similar results, however, for elderly LSS patients over 75 years old, studies on the complications, clinical and radiographic outcomes of ULBD surgeries have seldom been reported.
In this study, the mean age of patients was 75.83 years, and nearly half of these patients had two or more levels of stenosis. We found that ULBDwas associated withsignificant improvement in low back and leg pain as well asODI and SF-36 at 6 months in most patients, thisimprovement persisted at 12 months follow-up. Moreover, patients in the current series toleratedthe surgical procedure well, even though many had comorbiditiessuch as hypertension, congestive heart failure, diabetes mellitus,chronic obstructive pulmonary disease. Katz et al.found that after decompressive laminectomy, elderly patients with greater medical comorbidity andfunctional disability were significantly less satisfied with theresults of surgery. Transfeldtetal. reported that patients undergoing open surgical decompression,with anaverage age of 76.4 years, the complication rate was 21%-40%.In our study the total complication rate were 10.2% and these results demonstated that satisfactory outcomes in elderly patients.We speculate that these good outcomes and low complications of theULBD resultfrom several inherent advantages of the MIS technique. MIS technique can reduce theinflammatory and stress response after surgery. Postsurgical stressresponse was found to contribute to imbalance in autonomic,endocrine, and immune systems. It was also found to promotehypertension, cardiac dysrhythmias, and myocardial infarctions inthe immediate perioperative period.Elderly frail patientssuffering from multiple medical comorbidities and limited physiologicreserve are vulnerable to stress and may therefore especiallybenefit from MIS procedures that minimize these risks.
Another advantage of ULBD is the decreased wound infection. Aging and a comorbid condition, such as vasculopathy, can leadto delayed wound healing that may jeopardize patient outcomeseither by direct influence on spinal muscle rehabilitation. ULBD surgery results insmaller skin incisions that facilitate wound healing and decreasethe risk of wound complications in old population, maybe for this reason ,no wound infections in our study. And this MIS procedure also can reduce blood loss.The cardiovascular and pulmonary compensatory mechanisms areof limited capacity in older patients because age decreases thecontractility and increases the stiffness of the left ventricle.These alterations may impair the patient from tolerating largevolume shifts, which can lead to life-threating complications ingeriatric patients.
Dural tears were the most common complication in UBLD. Itwas thought that with the unilateral approach, especially in severe elderly LSS patients, accessto the opposite lateral spinal canal may require significant duralsac retraction, with a possibly higher risk of tears of the spinaldura mater. Accidental dural tears occurred in 2 patients (4.4%) inour study. However, the rate of dural tears in our serieswas similar to the previously documented average results formicrosurgical ULBD of LSS (0%-18%).This rate was comparableor lower than the rates reported in most series ofdecompressive surgery for LSS with a published overall incidenceof dural tears approaching 14%. To our experiences, in cases withbilateral radiculopathy or severe stenosis, do not rush this stage of the procedure. Allowing contralateralmicroscopic visualization and using angled curets slowly create more room to perform the decompression could reduce the incident of dural tears. If an iatrogenic injury to the dura is encountered, it is best to close it immediately. This mayrequire some special long shaft suture instruments to achievewatertight closure.
For ULBD, another main goal of surgery was adequate decompression of the neural elements. We utilized CT to measurements of the cross-sectional area of the spinal canal and lateral recess heights and postoperative CT demonstrated decompression was enough. In contrast to our results, Thomé et al.found that the ULBD was associated with less sufficient decompression than the bilateral laminotomy, even if the difference was not significant. This finding may suggest that the ULBD approach provides a worse view of the contralateral recess due to the limited exposure via a unilateral approach. However, Moisi et al. concluded in their technical note that the ULBD approach could provide better visualization of the contralateral recess. Our selection of the decompression strategy using the ULBD technique was based on patients’ symptoms and severity of LSS. For elderly patients with facet hyperplasia, ipsilateral facetectomy was routinely performed to obtain an adequate decompression for foraminal and lateral recess stenosis,it provided enough space and abduction angle to allow undermining of the ventral aspect of the spinous process and contralateral lamina, and the posterior midline osteoligamentous structures and contralateral ligamentum flavum could be resected to expose the contralateral side, which allow contralaterally facetectomy and provide complete decompression of the dural sac and contralateral nerve root.
During lumbar decompression surgery, the extent of preservationof the bilateral facet joint is an important factor for maintianing spinal stability. Traditional standard decompressioninvolves widely facetectomy andsome removal of the posterior spinal structures. As aresult, the approach can lead to postoperative destabilization, which canlead to the need for spinal fusionand in turn is associatedwith increased comorbidities in elderly patients. Maricondaet al. indicated that high rates of reoperation in opendecompression, ranged 11–30%. In our study, we performed adequate decompression of the spinal stenosis and no secondary instability was found in this ULBD procedure. Miyazakiet al.reported the average percent facet joint preservation on ULBD was significantly smaller in conventional decompression surgery, ULBDpreserved 60–83% of the facet joint on the approach side and > 90% of the facet joint on the contralateralside. By contrast, traditional approach only retain ≤ 40% percent of the facet. Therefore, we thought this MIS method can reduce the risk of postoperative spinal instability at the surgical site due to satisfactory preservation of the facet joint.