Article: Microendoscopic discectomy versus open discectomy for lumbar disc herniation: a meta-analysis 

Meta-analysis published in the European Spine journal in 2016

Authors: JuLiang He et. al, 2016.

Introduction: Surgical discectomy is indicated for pts who are non-responsive to conservative management for at least 6 weeks or have progressive neurological impairment. There are different types of discectomies – open (standard), micro, microendsocopic and percutaneous endoscopic discectomy 

Purpose: To compare the outcomes of microendoscopic discectomy and open discectomy of patients with lumbar disc herniation.

Methods: An extensive search of studies was done using PubMed, Medline, Embase, Cochrane library and Google Scholar. Studies included in the final analysis were 5 RCTs conducted in various countries involving 501 patients, who were 18 and older, were diagnosed with symptomatic lumbar disc herniation, and were followed for 1 year after surgery. Of the 501 pts, 253 were treated by microendoscopic discectomy and 248 were by open discectomy. The studies had a low risk of bias based on quality scoring.

Outcomes measured: 

1. Visual analogue scale (VAS) – measures pain (subjective)
2. Oswestry disability index (ODI) – measures functional disability in a patients with lower back pain (subjective)
3. Complications
4. Operation time
5. Blood loss
6. Length of hospital stay.

Data analysis: conducted with RevMan 5.0.

Results: 

– The pooled analysis showed that there was no significant difference in the VAS, ODI or complication between the two groups. 

– Compared with the open discectomy, the micro endoscopic discectomy was associated with:

1. less blood loss [WMD = -151.01 (-288.22, -13.80), P = 0.03],
2. shorter length of hospital stay [WMD = -69.33 (-110.39, -28.28), P = 0.0009
3. longer operation time [WMD = 18.80 (7.83, 29.76), P = 0.0008]

Findings:

1. 3 RCT reported VAS score and the pooled analysis showed no significant difference between both groups.
2. 4 RCT reported compared ODI score at final follow ups, pooled analysis also showed no significant difference between both groups.
3. This indicates similar improvement of clinical symptoms (decompression of nerve root) based off the VAS and ODI assessments which help determine the clinical effectiveness of the procedures. 
4. ALL studies reported operation time and microendoscopic discectomy was shown to take a much longer time compared to the open approach.
5. ALL the studies assessed the length of hospital stay and thy found that micrendoscopic discectomy was associated with significant shorter length of hospital stay compared to open discectomy.
6. Four RCT explored intraoperative blood loss and showed that in the microendoscopic group the was significantly less blood lost compared to the open group resulting in less surgical trauma. 

Limitations of the analysis include:

1. Inability to determine complication rate, which was due to inconsistent definitions of complications across the included studies. Major adverse events such as Dural tear, root injury, recurrence, reoperation and infection were considered and analyzed in this study. Qualitative analysis showed no significant difference in Dural tear, nerve root injury reoperation or would infection between both groups.
2. The sample size used for the analysis was quite small. 
3. Microendoscopic discectomy is a difficult procedure and may require dexterity and good hand eye co-ordination. Improvement in proficiency over time may reduce the time spent during the surgery never these this approach has its risk such as difficulty suturing a Dural tear with limited root or risk for root injury.

Conclusions: Micro endoscopic discectomy, which requires a demanding learning curve, may be a safe and effective alternative to conventional open discectomy for patients with lumbar disc herniation. However, open discectomy carries risk of surgical trauma of paravertebral muscles, and surgical scarring and adhesions. Microendoscopic discectomy is less invasive and may be performed using a transmuscular approach. It has also been associated with reduced post-operative pain, may reduce surgical trauma, length pf hospital stay and time to return to work/activity.