Irritation of the exiting nerve root causes approach-related new root pain [40]. When noted, the surgeons should promptly try to adjust the entry point and trajectory and try to land more caudally in the foramen. The traditional teaching is to walk down the facet with the needle [41]. Reduced height of the foramen/disc is a risk factor. The use of sequential dilators is another requisite in these cases instead of directly applying the tapered dilator. Surgeons should never directly target the upper half of the disc to avoid an exiting root injury. Remain in the lower part of the foramen, and the guide wire should always be followed by the dilator and working cannula as closely as possible to the facet joint [42]. Patient may also have pain if the instrument manipulates or the radiofrequency (RF)/laser/bipolar comes in contact with the traversing nerve root. Either conversion to general anestheia or abandoning the procedure could be the options if the pain persists [43]. TELD may be converted to open surgery or alternatives for sensitive patients in spite of counselling or approach related exiting nerve root pain. In addition, low tolerance to pain and anxiety can make the procedure nonexecutable. Counselling the patient preoperatively, including demo videos or self-help groups, would reduce the anxiety. As patient is conscious, explanation step by step may be needed. The obturator guiding method is another method to have precise control and reduce attempts [44].

Bleeding due to injury to vascular structures is a big hinderance in TELD, especially when profuse. The potential sources of bleeding during TELD are epidural vessels, foraminal artery, segmental lumbar artery or rarely, the great vessels [45,46]. Judicious use of bipolar or RF ablation solves most of the issue. It is more in epidural techniques and when bone sculpting is done [47]. Laser can be helpful along with RF. Pressure saline is an adjunct. Reinsertion of the trocar and waiting for a while does help with tamponading. Cold saline and adrenaline in saline irrigation can be used [41].

The abdominal and the retroperitoneal structures may be injured during TELD. The needle can perforate the peritoneal sac or the colon before landing at the foraminal target, if the skin entry point is chosen too far laterally in tangential entry to disc or the trajectory is kept vertical [48]. Inadvertent advancement of a needle or other instruments beyond the anterior or anterolateral disc margin after reaching the disc can also occur, especially when TELD is being done to treat primary early spondylodiscitis or postoperative spondylodiscitis with soft annulus [18,49]. Ureter or bowel injury has been reported in the literature [50]. To avoid these inadvertent complications, the needle or instrument position should be repeatedly confirmed on fluoroscopic views especially during early learning. Remember, the anteroposterior image view is our directional guide, and the lateral image is our depth guide. The needle tip should never have crossed ventral to the intertransverse plane or facet joint complex plane till it has touched the facet.

Although fluoroscopic guidance is used while approaching the target level, the markings and entry are done on the surface/skin [51]. The needle may land up on an adjacent level due to the lordotic nature of the lumbar spine leading to surgery at the wrong level [52]. Confirmation of the correct level is therefore essential after every step of approach, so to prevent this misfortune. In addition, presence of transitional vertebra or a variation in number of vertebrae may cause a discrepancy between the level reported on the magnetic resonance imaging (MRI), which may not correspond to the x-ray/fluoroscopic localization [53].

The one of the most common complications of TELD is an intraoperative dural breach or traversing root sleeve injury. The prevalence of inadvertent dural sac tears during open LDH surgery is variable, ranging from 1.8% to 17.4% [54]. Because of the surgery with irrigation solution, it is difficult to detect a dura sac tear during TELD. Most cases may go unnoticed and asymptomatic. A mechanical tear caused by the needle, guidewire or the instruments, or a direct/indirect thermal injury caused by bipolar/laser/RF is the reason for dural injury. If dural injury is unrecognized or untreated, in some cases serious neurological deficits may develop. Most dural tears are usually self-sealing due to tamponade effect [55]. However, a neural tissue injury is not pardonable. If rootlets herniate through small rents, it can create deficits or new pain. If a dural tear is noticed and if the surgical objective is already achieved, then observing the patient should be the protocol [56]. The redundant position of the rootlets getting sedimented in supine position may also be a reason what author believes for nonsymptomatic or under reported dural tears. Repeat transforaminal approach through scope and packing of the area with SurgiSeal (Nitcho Kogyo, Tokyo, Japan) or gelatine sponge bits have been successfully tried in liquor leaking wound with additional external stitch where there were no neurological problems. Otherwise, if in the postoperative period, any leak or symptom is noted with an MRI justification, it should be explored. If any nerve rootlets herniate from the split and get strangulated, severe radicular pain starts [55]. If the surgical objective is pending preoperatively, TELD should be abandoned and converted to open surgery. Open surgical protocols for dural injury management have to be followed in such cases [57]. For preventing intraoperative dural breach, surgeons should be vigilant while working near the blind spots where the endoscope does not provide adequate visualization [58].

The neural structures at risk of injury during TELD are traversing nerve root, exiting root/dorsal root ganglion (DRG) and furcal nerves. A deviation of the needle, dilator and cannula to the upper part of neural foramen should be avoided as it can injure the exiting root/DRG [59]. It is better to keep the beveled open face of the working sheath towards the cranial side till it has entered the disc while rail-roading on the obturator-dilator. After entering of the sheath into the annulus, it can be rotated to face the bevel dorsally. This can again prevent trapping of exiting nerve root by the leading edge. The target should always be the lower half of the foramen [29]. A detailed preoperative MRI evaluation is needed to understand the low exiting (horizontal) nerve root anatomy. Preoperative distance measurement of exiting nerve root to facet at the lower disc level in axial MRI helps to avoid exiting nerve root injury. Similarly, parasagittal and axial magnetic resonance images can detect a horizontal root or low exiting root/conjoined roots, which is a strict contraindication to the inside-out technique [60]. A longer duration of surgery with the scope at an angle close to the horizontal plane can cause a constant strain on the exiting root and add to the woes, leading to postoperative dysesthesia or paresis. The traversing root and the thecal sac are at a risk of injury with blind or excessive intraoperative manipulation by instruments. Initial landing should be as close to the target as possible. The target point and approach angle can be adjusted according to the zone of herniation, type, migration, basic technique used and LDH level. Visualized controlled work under endoscopic view is to be done. Outside-in technique with the use of rotatory instruments and nonvisualized blind reamed foraminoplasty increase the chances of injuries to the traversing root and the thecal sac if not judiciously done. Likewise, steerable instruments also can cause injury when working away from nonvisualized areas.

As the instruments used in full-endoscopic spine surgery are thin, low profile, they are not as sturdy as the ones used in open or minimally invasive spine surgeries. To add to this, TELD instruments have a long lever arm and may also be articulating, so the chances of breaking are more [61]. Gentle and careful handling of the instruments is recommended. The surgeon should use the working cannula or the scope as a joystick to change the direction of work, instead of applying undue force on the instruments.

Nonionic contrast materials such as iohexol (Omnipaque, GE Healthcare, Princeton, NJ, USA) is often used to confirm proper needle position in the Kambin triangle before proceeding further. This is more so in the early phase of the learning curve. Although the safety of nonionic contrast media have been widely reported in the literature, they are notorious in causing sporadic episodes of adverse reactions, urticaria, nausea, flushing, headache, hemodynamic abnormalities, arrhythmia, and seizures [62,63]. The use of contrast agents can be minimized once sufficient experience is gained, and omitting the routine practice of discography [64]. Indigo Carmine is a blue-colored dye which is used to help identify degenerated disc tissue during endoscopic discectomy. It differentially stains the disintegrated disc material, guiding the surgeon as to what is to be removed during the procedure. There have been reports of hemodynamic alterations after injecting indigo carmine into the disc space, such as hypotension, tachycardia, cardiac dysrhythmias and, in the worst-case scenario, anaphylaxis [65]. The anesthetists should be informed during the step of dye injection into the disc so that they can be more vigilant to the hemodynamic parameters of the patient and respond quickly if any reaction occurs. With experience, surgeons could skip this step altogether to avoid potential hazards.

With the extended indications, TELD often involves bony work. The surgeon, at times, has to drill the facet, pedicle or the posterior vertebral wall. This is more so when dealing with cases of high migrated discs, axillary LDH, and stenosis [66]. A coronal facet orientation, especially at the L5–S1 level requires the drilling of the facet for access. In cases of low iliac crest, a shallow transforaminal approach is still possible. However, in cases of high iliac crest, a modified technique with a more medial placement of the skin entry and endoscopic visualized resection of the superior facet tip is be done [67]. Inadvertent excess bony work may lead to injury to the facet or fracture of the pars, causing intraoperative bony instability.

Failure occurs when the primary objective of the surgery is not fulfilled. Failure to remove the herniated disc or incomplete decompression of the stenotic area is quite common especially in early learning curve [68,69]. It occurs because of a residual or complete fragment remaining as the cause of compression. The patient may have an immediate pain-free period for a day or two under the LA influence or steroid and again get the same pain back. The patients usually have radicular pain without a significant pain-free interval. A typical finding is restricted straight leg raise. This is more likely to occur in cases of migrated LDH, axillary fragment or large central LDH with high canal compromise. At times, a sequestered disc fragment may migrate from its original position and the surgeon may not find it at its corresponding position on MRI. A change in the location of the fragment after the initial presentation can only be confirmed by an immediate preoperative screening MRI or X-MRI [70]. A concomitant lateral recess/central stenosis, dynamic stenosis or instability frequently adds to advanced failed cases [71]. Lateral recess bony stenosis can be addressed with a separate decompression procedure. In cases of unilateral symptoms of long-standing and moderate stenosis, TELD with stenosis decompression is gaining momentum and advances are being reported [72]. Another conceptual change is to understand that the disc prolapse material can have associated end plate cartilage or/and annulus in addition to nucleus fragment. This may have to be removed for complete decompression especially with acute on chronic clinical history. There may be small to big end plate junction failure or posterior rim apophysis fracture [73,74]. This may be healed or avulsed nonunited and may necessitate removal when needed. Incomplete decompression can also occur due to technical difficulties. To prevent this problem, proper training, multiple instrument inventory, variable techniques and tricks are needed with progressive learning. Technically, either you must reach the base of herniation in front of the endoscopic view, or you have to have steerable instruments under vision to be used. Adequate knowledge of anatomical relationships is an essential know-how. Plotting the fragment on plain anteroposterior and lateral projection radiographs helps determine the target point. Moreover, the ability to recognize the endpoint of the decompression is the crux for a successful TELD [75]. The endpoint may vary depending on the situation. Not all signs are always possible and thus, the surgeon should make a judicious call based on experience.

Seizures can be caused by inadvertent administration of the contrast media into the thecal sac during TELD [76]. Otherwise, intraoperative seizures are due to increased epidural pressure, although their occurrence is rare (0.02%) [77]. The duration of the procedure, speed of saline infusion and use of large channel endoscopes are the major risk factors that should be optimized. Prolonged duration of surgery also can precipitate prodromes and seizures. Other factors include hypoxia, a history of epilepsy, anesthetic and sedative agents, etc. [33]. Mechanical irrigator system maintain constant pressure, but can be dangerous if not used judiciously. Instead, manual irrigation (drip stand elevation and cuff pressure) is intermittent and allows washing out excess fluid. Also, a high index of suspicion and early recognition of the prodromal symptoms like neck or upper back pain, headache confusion, visual disturbances, hemodynamic abnormalities and discomfort is the key to avoid seizures [33].

The most common neural injury problem is approach-related irritation of the foraminal/extraforaminal neural structures (exiting nerve root, DRG, or frucal nerve) or lateral recess structure (traversing nerve root) [85]. Irritation injury can be a neuropraxia, axonotmesis or neurotmesis and can be caused by the approach needle, obturator, the working cannula or hand instruments during the approach steps. If neural injury occurs in the conventional posterior open discectomy, it may usually occur to the traversing nerve root, which is already compromised. So, accentuation of any numbness or dysesthesia is explainable and patient can get convinced. However, in TELD afresh DRG can be the injured one, and the patient has new symptom called postoperative dysesthesia (POD) [86]. POD may cause significant sequelae and is common and reported in various series up to 15% patients, especially at the upper lumbar levels [40]. Transient paresis may occur, with estimated incidence rate of up to 4% reported in the literature [18]. The risk factors are foraminal or far-lateral disc herniations, narrow foramen, and more horizontal position of the working tube. This complication is particularly stressful for the surgeon, because the symptoms differ from the patient’s preoperative symptoms. Blind reamed foraminoplasty for “outside-in” approach will have more POD than visualized endoscopic foraminoplasty [42]. Widening of approach triangle without taking adequate care for foraminoplasty and especially for advanced fusion indications with expandable cage also have more incidences of POD. During the procedure, patients are conscious but under LA. Patient feedback gives you the indication to redirect and reconsider the approach direction. But, if excess LA is given then you may get lesser feedback and a GA, if used can be very dangerously compounding, though used at many centers. Neuromonitoring can be used in GA [87]. A continuous palpation of leg muscles throughout the procedure by a physiotherapist or physician is also a naive method to detect abnormal neural contractions while manipulating. Although common and disabling, POD recovers in most patients after several weeks or months without additional therapeutic measures [18].

Regardless of complete removal of LDH, persistent pain can be there postoperatively. Various possibilities should be kept in mind in such cases:

Although the occurrence of gross neurologic deficit is rare in TELD, it is one of the dreaded complications of this procedure [18]. The traversing nerve root is at a risk of injury with the instruments or the bipolar RF/laser. Even a large, herniated disc can injure the nerve root during its extraction. Unrecognized dural tears may also lead to postoperative neurologic deficit [55]. In case of severe neurological deficits such as foot drop or cauda equina syndrome, open surgery and exploration are recommended.

Since TELD is a fluid medium based surgery, there is a risk that the irrigation fluid may seep into the tissue planes. Extravasation of irrigation fluid has been reported to occur in upto 3.8% patients [71]. Most cases are self-limiting and require only observation. Limiting the surgical time minimizes this complication.

Pneumocephalus is a condition in which air enters into the subdural or subarachnoid space. Although TELD is a closed fluid-medium surgery, there is a rare possibility that in a case of inadvertent dural tear, pneumocephalus may occur. The mechanism is that a sudden gush of CSF out of the dural sac creates a negative intrathecal pressure, and any air trapped in the working channel or working cannula may get sucked into the thecal sac and migrate cranially [91]. Symptoms may range from headache, dizziness, nausea, and vomiting to more severe features including drowsiness, confusion, disorientation, agitation and seizures [92]. A reverse Trendelenburg position (head-low) should be adopted in case a dural rent occurs to prevent air from entering into the thecal sac.

In most cases it occurs because of the use of LA and therefore resolve themselves shortly after surgery which leaves no residuals but adds to the patient and the surgeon’s anxiety.

Zhu et al. [93] reported urinary retention as a result of epidural anesthesia, which is a very rare complication in TELD. It can be managed with catheterization, observation and catheter removal following the reappearance of bladder sensations.

The occurrence of hematoma is relatively rare, but a retroperitoneal hematoma or epidural hematoma can develop. Injury to segmental artery or lumbar radicular artery or their branches during the transforaminal approach or extraforaminal discectomy may cause hematoma formation in the loose retroperitoneal space [46]. Smaller hematoma are subclinical, not recognized and self-limiting. In case of a large hematoma, urgent surgical evacuation is required [94,95].

Uncontrolled bleeding may lead to seepage of blood under the subcutaneous tissue, leading to ecchymosis around the incisional area. This is a rare occurrence (incidence reported to be 0.76%), and is usually inconsequential, not associated with increased pain, and therefore, no further treatment is required [17].

The blind-puncture technique in PTELD puts the retroperitoneal structures at risk of injury. In addition to a retroperitoneal hematoma, inadvertent injury to the lumbar segmental artery may manifest in the postoperative period with flank/inguinal region pain due to pseudoaneurysm [96]. Symptomatic patients often require urgent abdominal computed tomography (CT) scans with CT angiography. Treatment can vary from endovascular coiling to vascular repair.

Superficial infections are rare in PTELD due to smaller incision and continuous irrigation of the surgical field. However, they can occur with skin incisional margin necrosis especially if there is overzealous under sizing than a 7- to 8-mm incision. Prolonged operative time, especially in cases of stenosis, calcified or central disc herniations can also precipitate wound infection [71]. More invasive endoscopic approach, especially a trans-iliac approach for L5–S1, can lead to concealed muscle injuries, infection and scarring. The routine use of broad-spectrum antibiotics in irrigating fluid should be practiced [97].

An unrecognized dural rent may present with persistent postoperative oozing from the wound. Rarely, a pseudomeningocele may form, although the potential space for its formation is limited in the transforaminal approach [98]. Rarely, CSF may leak from the dural puncture area that was repaired or a sealant was applied during the surgery due to straining in the postoperative period. Patients should avoid strenuous activity in the postoperative period, especially when a dural tear has occurred.

Systemic complications are rare in TELD. However, sporadic cases of deep vein thrombosis and pulmonary embolism have been reported in the literature [19]. Pulmonary complications like dyspnea, pulmonary edema and respiratory failure can also occur. Hilbert et al. [99] reported severe dyspnea with severe abdominal pain in a patient after endoscopic discectomy. On CT-guided aspiration and analysis, the fluid proved to be surgical irrigation solution.

Radiation safety is an important issue in TELD. The use of fluoroscopy is especially more during the early phase of the learning curve. This not only poses the surgeon, but also the patients at a risk of various adverse effects of ionizing radiation [100]. Ahn et al. [101] reported an average fluoroscopic time of 2.5 minutes per TELD case in their institute. They suggested that surgeons could safely perform approximately 5000 TELD cases using radiation shielding clothes and 291 TELD cases without shielding clothes per year. This is a pretty big adequate number for any surgeon. Ultrasound (US) guided percutaneous needle placement is emerging as an effective alternative to fluoroscopy [102]. The application of enabling technologies like navigation, robotics and US-MRI fusion are also evolving in the field of endoscopic discectomy [103-105].

Discal pseudocyst formation is a rare complication of endoscopic discectomy. It was first reported by Young et al. [106]. A discal pseudocyst differs from the juxta-facet, perineural and ganglion cysts as it communicates with the disc space and develops over a relatively short time following discectomy. It can compress the nerve root, resulting in a recurrence or exacerbation of patient’s pre-existing symptoms [107]. Although morphologically and imaging-wise they appear to be like true discal cysts, they lack a true capsule. Advances in imaging techniques have improved the diagnosis of pseudocysts [108]. A repeat TELD with drainage of the cyst is required in symptomatic patients [109].

The not-so-uncommon but one of the most problematic infections is spondylodiscitis, though it is rarer after TELD than with open surgeries. An inadvertent puncture of the intestine during initial needle insertion and redirection correctly will contaminate the disc space, leading to secondary spondylodiscitis [110]. If an intestinal injury is suspected, the needle should be changed. Re-entry should be taken under the cover with broad-spectrum antibiotics. Watch for any abdominal complaints. The typical presentation is severe back pain, toxic systemic features at times combined with leg pain and disability. Elevated erythrocyte sedimentation rate and C-reactive protein appear to be more reliable for diagnosis along with radiological findings, especially in the early postoperative phase [111]. For definitive bacteriological diagnosis, disc biopsy under fluoroscopy is needed. The first-line treatment with appropriate antibiotic therapy with limited ambulation and bracing is needed, along with biopsy for evidence-based practice. Re-endoscopic debridement and wash is getting remarkable response in the hands of endoscopic surgeons and is recommended. There are reports of broad-spectrum antibiotics such as vancomycin 1 g being injected into the disc in concentrated paste form. Antibiotic-instilled saline irrigation is used by many surgeons in the primary TELD as a prophylactic measure. The author personally uses Cefazolin and gentamicin. In case of unresponsiveness, open debridement with interbody fusion may be needed [112].

An inadvertent puncture of the intestine during needle insertion may also lead to psoas abscess if the intestinal flora gets inoculated in the psoas muscle [113]. Similar strategies as in prevention of spondylodiskitis, including change of the needle and re-entry under the cover with broad-spectrum antibiotics, are to be followed. Treatment is appropriate antibiotic therapy guided by culture and sensitivity reports. Coexisting spondylodiskitis should be ruled out or managed as per protocols [110].

Radiographic evidence of reherniation of disc fragments at the same level, after a pain-free interval, despite postoperative documentation of removal of all fragments is recurrence in the true sense. After surgery, a hidden intradiscal herniated fragment may extrude from the same side or the contralateral side at the index level. The cutoff timeline for the symptom-free period has always been a matter of debate, and the literature is divided on this. Some authors have given a cutoff of as early as 2 weeks of symptom-free period before calling it a recurrence [114]. Others have given a cutoff ranging from 3 to 6 months [115,116]. To avoid confusion, an arbitrary time of 6 months could be used to define an early recurrence if it occurs within 6 months, and late recurrence if it occurs after 6 months of the index surgery [117]. Variable data claim lesser, more, or similar recurrence rate to that of traditional open or microlumbar discectomy [118-120]. There are reports of recurrence rates of TELD ranging from 0.8% to 15% in the literature [27,116,121]. Yin et al. [122] have reported the highest data, to date, on the prevalence of recurrence after TELD. In their meta-analysis involving 23,930 patients, they reported a recurrence rate of 3.4%.

Recurrence is predisposed by certain risk factors such as insufficient decompression, greater disc height, early and strenuous postoperative activity, presence of Modic changes, among many others [31,114]. Kim et al. [32] have proposed a scoring system to predict the risk for early recurrence in patients undergoing TELD. To reduce the recurrence rate, complete removal of the herniated mass, including the subannular and extruded parts, is very important. However, it does not mean a radical removal of the entire nucleus pulposus, but only the fragmented disc pieces, as aggressive subtotal discectomy can predispose to iatrogenic instability and lower patient satisfaction [123]. Recurrences are mostly managed by reoperations and usually refractory to conservative therapy. The utility of TELD in operating recurrent herniations have been excellent. This is true not only for recurrences due to previous TELD, but also due to traditional microlumbar discectomy. This is because TELD avoids the previous operative scar tissue of the posterior approach and thus provides a better access to the recurrent disc. This minimizes the chances of dural tear or neurologic injury due to fibrotic adhesions at the previously operated area, which is traditionally feared in revision microlumbar discectomy [28,89,124].

Although this complication is more often reported in open discectomy, excessive removal of outer layer of the annulus/posterior longitudinal ligament (PLL)/ligamentum flavum may cause epidural fibrosis and scarring in TELD patients as well [125]. A careful dissection, limited removal of PLL and ligamentum flavum and annuloplasty using bipolar RF are some of the methods to minimize soft tissue damage at the operative site, causing less postoperative scarring and epidural fibrosis [126]. In symptomatic patients refractory to conservative management, re-exploration and adhesiolysis could be done. There have been reports of endoscopic lumbar adesiolysis as well, with the use of RF or hyaluronic acid [127,128].

Disc degeneration is only an initial event in the cascade of spinal degeneration. TELD does not guarantee a halt in the natural history of progression of this degeneration. Moreover, aggressive removal of nucleus pulposus and other supporting structures such as the PLL, ligamentum flavum and facet contributes to acceleration of the process [66,123]. Higher grades of facetectomy can even precipitate an adjacent segment degeneration and co-existence of osteoporosis adds to the woes [129,130]. However, foraminoplasty has been found play a role in delaying, if not preventing late postoperative foraminal stenosis in some studies [131].

These complications can also be further subclassified as firstly as problem (which did not leave any after effects), secondly as obstacle that left a minor after effect or which could be corrected by a medication, and thirdly as a true complication that left a permanent after effect or needed reintervention.

A major concern or limitation for adaptation of TELD has always been a fear of the learning curve associated with it. There is abundant literature reporting a ‘steep’ learning curve for TELD [132,133]. A learning curve for any procedure is a graphical representation of proficiency in its execution as a function of time. It is the number of repetitions that need to be performed before one master the technique, and thus could either be steep or shallow. A steep learning curve is where one becomes proficient in the technique with a small number of repetitions, in contrast to a shallow learning curve, where one needs many repetitions of the task over a long time period to master it. Therefore, a shallow learning curve may reflect that the procedure is more technically demanding and difficult to master, contrary to the common belief that a steep learning curve is more challenging to overcome [134]. Nevertheless, a steeper learning curve phase and initial longer operation times may increase the incidence of complications for novice surgeons. In addition, by expanding the indications, experienced surgeons can add to unknown unreported complications as well. The strategy for dealing with these types of complications best is preventive, and we should be focused on such strategies considered here. Usually, the surgeons who overcome the learning curve end up mastering this technique and these surgeons and patients themselves start to prefer it over traditional techniques because of the lower morbidity and increased efficacy of the procedure. However, open procedures must be mastered by surgeons and are equally necessary in spinal surgery to overcome problems and complications encountered when performing TELD.

As with any technique in modern medicine, a successful TELD is affected by technique and experience. The surgeon should develop capabilities of autonomously using the endoscope and hand instruments and develop hand-eye coordination with tactile feedback. No assistant or accessory holder for the working channel should be practiced. Fluoroscopy should be used to ensure safety at any step of the procedure and for any manipulation confirmation. The legacy of these procedures is that they cause fewer complications due to lesser operative trauma to the musculo-ligamentous complex and spine stability. Different kinds of problems can arise with some frequency as with any surgical procedure. Surgeons should take adequate technical considerations and increase the understanding of the patient's pathoanatomy to reduce complications. The potential complications associated with TELD should be noted, especially those that are surprising and unexpected and undocumented. This is to give safe guidelines to the future generations. Documentation, rating, and follow-up of complications are necessary to gauge treatment decisions and improve informed consent and patient outcomes. Furthermore, with an ageing population and a worldwide struggle with rising healthcare costs, complications are an important socioeconomic factor. Understanding the frequency, type and consequences of complications are the first steps to take to reduce them. Modified ranking scale, Karnofsky Performance Status, modified McCormick scale, Clavien-Dindo Grading System, etc., are the various grading systems of complication in lumbar spine surgery. Future studies could focus on developing a combination scaling system in TELD to make for a better reporting of the complications.