Continuing Education Activity

Lumbar disc herniation is a common pathology and leads to a significant healthcare burden. Patients with low back pain and related conditions may seek care with a diverse variety of interprofessional team members. Thus, a widespread awareness of the signs and symptoms, diagnostic workup, and treatment options is critical to providing appropriate care for patients who suffer from this pathology. For patients who have failed to respond to non-operative treatment, a lumbar discectomy is an option that interprofessional team members should be aware of. Improving health professional knowledge on the prompt evaluation and treatment of lumbar herniation, including for cases refractory to non-operative management, will improve patient outcomes. This activity reviews the evaluation and surgical management of lumbar disc herniation and highlights the interprofessional team's role in improving care for patients with this condition.

Objectives:

• Identify the indications for a discectomy.
• Describe the equipment and personnel required for performing a discectomy.
• Outline the potential complications of a discectomy.
• Review the importance of improving care coordination amongst interprofessional team members in assessing the need for a discectomy and performing and post-operative follow-up will enhance the delivery of care for patients undergoing discectomy.

Introduction

Lumbar disc herniations (LDH) are a relatively common and early manifestation of degeneration of the lumbar spine. The reported incidence of LDH is 2% ~3% and the prevalence is around 12%.[1][2] Prevalence of 4.8% among men and 2.5% among women above 35 years of age.[2]

The most common site of LDH is at L4–L5 and/or L5–S1.[3]

Surgery for LDH accounts for the most common indication for performing spinal surgery.[4][5]

Relevant pathophysiology involves extrusion of the central nucleus pulposus through the compromised outer annulus fibrosus. Symptoms are thought to result from a multifactorial mechanism with components of noxious stimuli to the disc material itself, an inflammatory cascade impacting local nerve roots, and direct compression of nerve roots by extruded disc material. Treatment options include conservative treatment, the mainstays of which are oral medication and physical therapy. The potential efficacy of these modalities is well established.[6][7][8][9][10] Rigorous adherence to the objective association between the patient’s symptoms, physical exam findings, and diagnostic imaging is essential to predict the effectiveness of any planned surgery.

Different surgical strategies for LDH:

• Open.[5]
• Minimally Invasive Open Lumbar Discectomy (MIOLD).[11]
• Microlumbar discectomy (MLD).
• Micro-endoscopic discectomy (MED).
• Fully endoscopic (FE).

The core principle of the surgery in eliminating the nerve impingement remains the same, the dictum of the newer surgical strategies only focuses on reducing assess trauma to the multifidus and improving surgical vision.[4]

History of discectomy

Mixter and Barr first described laminectomy for LDH in 1934 through L3 to sacrum approach. Hemi-laminectomy came into practice in the 1970s.[12]

Caspar and Williams described microdiscectomy via a 3 cm incision in 1977.

Wiltse and Spencer described the paraspinal approach for managing extra-foraminal discs in 1988.[12]  In the same year, Kambin and Sampson described a fully endoscopic approach [FE]) for an extra-foraminal approach

In 1993, Mayer and Brock reported the use of tubular retractors. Foley and Smith performed a video-assisted technique using a tubular work canal (Micro-endoscopic discectomy: MED) via a 2-cm incision adopting a trans-muscular approach without multifidus release from its insertion in 1997.[12][13]

Indications

Urgent lumbar discectomy is necessary in cases of cauda equina syndrome and progressive or new motor deficit. Elective lumbar discectomy is indicated in cases of unremitting radicular symptoms that correspond to radiographic evidence of nerve root compression by a herniated disc in patients that have failed conservative treatment methods. A thorough understanding of the expected outcomes is necessary on the patient's part before proceeding with surgery. Specifically, the relatively higher reliability of improvement in radicular leg pain as compared to back pain must be stressed. Recurrence risk is an important topic, as well. Revision discectomy remains a viable option should recurrent herniation occur, though with the removal of more disc material and especially in the setting of large or repeated annular injury, the option to proceed with spinal fusion at the injured level may be a consideration. Before surgery, a high level of correspondence between a patient’s symptoms and pathology on magnetic resonance imaging must be confirmed to improve the reasonable likelihood of a positive outcome.

Prerequisites prior to surgery:

Detailed history taking and thorough neurological examination:

L5 disc cause step page with pelvic glissading while walking in L5 radiculopathy.S1 causes dragging of the foot along the ground while walking. Detailed dermatomal mapping must be obtained.

Correlation with pertinent radio-imagings:

Radio-imagings include plain and dynamic X-ray; CT, CT myelography or CT discography, MRI, and a spinal teleradiograph. This help to ascertain the presence of LDH, and confirm the level, position, and pattern of the herniated disc (posterolateral/ foraminal/extra-foraminal and extruded vs. sequestrated).[4]

A protrusion is when the height of the hernia is less than the length of the base. Extrusion is when the length of the base is less than the height of the hernia. Sequestration is when there is no continuity between the herniated material and the intervertebral disc.[2]

Patient counseling should encompass:

• Natural history of the disease process-There is a rapid relief of symptoms over a mean period of four to six weeks, with a recurrence of 5 to 10%, regardless of the type of management strategies.[2] Spontaneous resorptions occur in up to 66.66% of cases.[14]
• Different management strategies.
• Different surgical strategies.
• Risk and benefits of surgical management.[4]

The cornerstone of the surgical management of LDH includes:

• Detailed history and neurological examination.
• Good patient selection.
• Proper surgical techniques.[4]

Indication for surgery for LDH includes:

• Cauda equina syndrome
• Refractory and disabling pain despite 6-8 weeks of analgesics
• Progressive or new onset neurological deficits.[4] 

Contraindications

It is imperative to rule out:

• Lumbar canal stenosis.
• Concurrent segmental instability.

Preparation

Anesthesia:

Spinal or general anesthesia both had comparable outcomes.[15]

Patients undergoing general anesthesia (GA) demonstrated significant improvement in VAS leg and back pain compared to LA in MED. LA minimizes costs and risks.[16]

Surgical aspects:

1. OT Safety checklist.
2. Sterile theatre environment.
3. Antibiotic prophylaxis 30 minutes prior to incision.
4. Proper positioning: Genupectoral ensuring free abdomen, chest support, eyes protection, shoulders in 90° abduction, elbows in 90° flexion, and placing the spine in kyphosis to open up the inter-laminar space.
5. Localization and exposure- Through surface landmarks and fluoroscopic guidance.

Technique or Treatment

Open/ Standard Discectomy (SD)

After administering general anesthesia, the patient gets positioned prone on a spine frame (Wilson or Allen Bow) or a dedicated table. Transverse pads at the iliac crest and chest allow for flexion of the hips to increase interlaminar distance while avoiding pressure on the abdomen to reduce central venous pressure.  Palpation of bony landmarks, including the sacrum and iliac crests corresponding to the L4-L5 disc level, may guide the start point and trajectory of the surgical approach. After appropriate sterile skin prep, localization using a spinal needle and fluoroscopic control confirms the target level. A 3 to 4-cm longitudinal incision is marked at the midline centered about the radiographic marker.

The skin incision is made with a sharp scalpel, and subcutaneous dissection with electrocautery reveals the lumbar fascia; this is incised just off of midline, as identified by palpating the spinous processes, ipsilateral to the disc pathology addressed. This fascia should span the interspinous distance at the target level. A radiographic marker may be used to confirm the spinal level and cranially directed trajectory in line with the interspinous space on a lateral fluoroscopic image. Using electrocautery, a subperiosteal elevation of paraspinal musculature from the superior and inferior spinous processes is completed down to the laminar junction. Lateral dissection continues bluntly with a Cobb elevator as far laterally as the facet joint taking care not to violate its capsule. Visualization of the interlaminar space is essential; removing dissected muscle tissue in the surgical field, proper retraction, and diligent hemostasis using electrocautery is crucial. At this point, the surgeon releases the ligamentum flavum from its attachment on the anterior aspect of the lamina of the superior vertebra using a curette. An angled Woodson elevator may then be inserted anterior to the ligamentum, directed caudally, to protect the dura beneath. The ligamentum is then incised sharply to allow for its retraction with a Penfield elevator and visualization of the exiting nerve root and associated epidural fat. The medial aspect of the inferior facet of the superior vertebra may require resection to allow for adequate exposure. A Penfield or blunt probe is then passed into the neuroforamen to mobilize the root, enabling its medial retraction. With adequate visualization of the intervertebral disc space, removal of fragmented or herniated tissue may then be carried out using pituitary rongeurs. If a portion of the herniation remains beneath the posterior longitudinal ligament, a scalpel may be necessary to incise the annulus for access. Care must be taken to probe the epidural space using a Woodson elevator in all directions for any additional disc or ligamentous tissue.

Additionally, it is advisable to irrigate the disc space with saline via a bulb syringe to express any loose disc fragments that may have gone unvisualized.   Meticulous hemostasis via bipolar electrocautery is achieved, and the wound is liberally irrigated with saline. The fascial and subcutaneous layers are closed with absorbable sutures, and the skin closure is by surgeon preference.

Minimally Invasive Surgery (MIS) Tubular Discectomy

The patient is positioned and prepped as described above. A 1.5 to 2.0 cm surgical incision is marked longitudinally, 1.5 cm off midline on the affected side.  A stab incision with a #15 scalpel allows the introduction of a guide pin or K-wire, which is advanced under lateral fluoroscopy to ensure appropriate depth as well as docking to the lamina cranial to the affected level. Once the start point and trajectory are confirmed, the full skin incision is made, and a fascial incision is centered over the wire. Sequential dilator retractors are placed to create a working channel that may be anchored to the operating table.  Magnifying surgical loupes or intra-operative microscopic are useful adjuncts to aid in visualization. Utilizing instruments appropriately designed for a tubular approach, the remainder of the procedure takes place as described above. Meticulous hemostasis is achieved, the tubular retractor system is removed, and the closure of subcutaneous tissue and skin completes the case.

Micro-endoscopic Discectomy (MED)

The patient is positioned and prepped as described above. Beginning at a start point 1 to 2 cm off of midline ipsilateral to pathology, the anatomical space bound by traversing nerve root, exiting nerve root, and superior aspect of the caudal vertebra known as a Kambin triangle is approached at the target level using a spinal needle. A 5 to 10mm skin incision is made, and successive cannulated dilators under fluoroscopic guidance allow for the introduction of an 18 mm operating canal through which the endoscope for visualization of the disc space, traversing and exiting nerve roots, and the passing of instruments are made. A laminotomy of the cranial vertebra may be made, and targeted nerve roots may be decompressed using endoscopic curettes, rongeurs, drills, and bipolar electrocautery. Herniated disc material may thus be removed. A single small endoscopic incision is closed with a subcuticular suture.[4]

Full endoscopic discectomy (FE)

• The approach is lateral and trans-foraminal.
• The entry point is 12 to 14 cm off the midline, at an angle of 20° to 30°.[4] 
• This approach is not recommended for sequestrated intra-canal fragments.[4] 

Post-Operative Care

Typically, patients may be discharged on the first postoperative day after an uncomplicated discectomy. An additional postoperative stay may be necessary for physical therapy rehabilitation or oral pain control.  Discectomy on an outpatient basis has been described and practiced at some centers.[17] No external bracing is necessary for spinal stability. Most surgeons advise limiting significant bending, lifting, and twisting motions for 3 to 6 weeks after surgery due to concerns for re-herniation, though more expedient or immediate unrestricted activity may yield equivalent outcomes without increased re-herniation rates.[18][19]

Postoperative advice:

• Light activities can be resumed at 2 weeks.
• Routine activities can be resumed at 6 weeks.
• Strenuous labor or contact sports can be resumed after 12 weeks.

Rehabilitation plays an integral part.[4] Rehabilitation preoperatively was performed in only 35% of centers, postoperatively as an inpatient in all centers, and postoperatively as an outpatient in 82% of centers.[20] Enhanced Recovery Rehabilitation Surgery Concepts favor the best clinical results.[1]

Complications

A wound or deep infection occurs at a rate of 2 to 3%, with dehiscence or other wound infections occurring at a rate of 1 to 2%. Direct intra-operative nerve root injury has been described to affect 1 to 2% of cases. The rate of incidental durotomy ranges from 0 to 4% in the literature. Durotomy can lead to leakage of cerebrospinal fluid with a subsequent risk of developing meningitis. Instability following discectomy by the techniques described here is understood to be exceedingly rare, though the difficulty in its definition and metric makes objective quantification difficult.

The LDH recurrence rate following discectomy ranges from 1 to 25%, and the rate of intragenic dural tear approaches 9%.[8][21][22] Male gender, smoking status, and heavy labor are risk factors.[23] Those with concomitant retrolisthesis at L5-S1 appear to have the same long-term clinical outcomes as those without retrolisthesis according to an 8-year follow-up from the SPORT database.[24] As recurrence has been investigated at widely varying follow-up times and by several outcome measures, including recurrent symptoms and reoperation, patient-specific factors should inform a candid discussion preoperatively regarding the risk of recurrent disease.

The patient may have persistent pain following lumbar disc surgery, which may be a part of failed back surgery syndrome.[25]

Complications pertaining to lumbar discectomy can be enumerated as:

Dural tear:

Place a Patti neurosurgical sponge, and extend the laminectomy edges to expose the tear and primary repair with 5/0 non-absorbable suture. Use of biological glue.[26]

A history of epidural steroid injections within 3 months of the surgery has a risk for intraoperative dural injury.[1]

Excessive traction on the nerve while exposing the disc increases the risk of epidural bleeding and CSF leak.[4][27]

Iatrogenic Neuropraxia.[28]

Epidural bleeding:

Compresses with Patti sponge for venous “lakes”.

Use of hemostatic agents such as surgical and surgiflow.

Vascular injury:

The reported incidence is less than 1%.

Aorta and inferior venacava are at risk in L1-L4, the iliac vessels are at risk at L4-L5 and L5-S1.[29]

Large vessel injury- may require embolization or laparotomy.

Disc not identified:

Confirm imaging dates (which should be less than 2 months old).

Confirm the correct surgical level.

Extend the surgical corridor.

Failed-back surgery syndrome. A recurrence rate of 3-15% and instability rate of 20% during ten years of follow-up have been observed.[30]

Recurrence.

The reported incidence of 3% to 15%.[4]

Most recurrences at the same level of herniation and on the same side.[31]

In one study Recurrence rate at 5-year follow-up was 6.27% .63% of them occurred within 6 months.

Modic changes, disc height index (DHI), and facet orientation (FO) showed a significant co-relationship.[32]

Modic type-II and contained disks had higher odds of recurrence.[33]

Smoking, disc protrusion, and diabetes are significant predictors of recurrence.[34]

Obesity is a risk for the occurrence as well as recurrence of LDH.

Reoperation:

In one study comprising 1850 patients, 130 patients underwent re-operation and were successful in 62%of them. Herniation at different levels, recurrences at the same level, and scar formation showed excellent results in 98%, 54%), and 38% cases respectively.[35]

Postoperative discal pseudo-cyst.[36]

Iliac arteriovenous fistula.[37]

Epidural hematoma.[38]

Retained Non-absorbable Haemostatic Material (RNHM) such as gossypibomas and muslinomas.[39]

Clinical Significance

The gold standard of surgical intervention for lumbar disc herniation is discectomy or removal of disc material contributing to symptoms. Historically completed through an open approach, several more MIS options are presently available, giving the surgeon multiple options.  A recent Cochrane Database systematic review comparing open versus minimally invasive discectomy presented low-quality data suggestive of lower infection rates and shorter hospital stays for minimally invasive techniques, though with possibly inferior improvements in the low back and leg pain.[40]

Since the relatively recent adoption of endoscopic techniques, research available thus far appears to indicate a general reduction in immediate post-operative disability and hospital stay with equivalent outcomes compared to MIS and open techniques. Additional long-term, high-quality studies are warranted before superiority among these methods may be assessed, though each offers unique advantages.[41] The long-term implications of the relatively minimal surgical exposure necessitated by MIS or endoscopic approaches have been topics of debate.[42][43][44]

Lumbar discectomy has a success rate between 60 and 90%.[5]

Preoperative weight reduction and abstinence from smoking have beneficial effects on outcomes.[5] The strongest MRI predictors of meeting minimal clinically important differences (MCID) for health-related quality of life (HRQoL) included gray disc, herniated nucleus pulpous (HNP) area (>116.6 mm), and Hemi-Area Ratio (>51.8%).[45] Modic type 1 changes are associated with worse functional outcomes after discectomy.[46]

Comparative studies have demonstrated similar clinical results following MIS and SD/MLD.[13] The clinical efficacy and safety of MLD, MED, and SD for managing lumbar disc herniation are comparable.[12] Percutaneous techniques though encompass rapid recovery after surgery; there are high odds of recurrence and revision rates compared to MED and SD.[12] They also have also a higher cost. [12]Central high-canal compromised and migrated discs have a high failure rate with percutaneous inter-laminar endoscopic discectomy (PIED).[12] Though endoscopy confers the advantage of reduced muscle damage, creatine phosphokinase (CPK) and multifidus muscle atrophy were not significantly different in endoscopic Vs conventional microdiscectomy.[5][47] Minimally invasive techniques have a high risk of recurrence and iatrogenic complications.[31] Meta-analysis showed increased odds of intraoperative nerve root injury following percutaneous procedures while comparing to MED. MIS has a significant learning curve of 25 to 100 MEDs.[4][13], Grade C evidence is present for endoscopic percutaneous discectomy in managing LDH.[5]

In a survey study among spine surgeons for surgical management of symptomatic discs:

• 63% preferred MLD
• 53% percent preferred early mobilization (first postoperative day).
• 59% preferred to follow up with patients clinically.[5]

Comparative study between OD, MLD, MED, and FE:  

A comparison between SD and MLD-A meta-analysis found no benefit.[4]

Comparison between SD and MED-Mean hospital stay, bleeding, and time to return to work were lower in MED, but long-term pain results were equivalent.[4]

Comparison between MLD and FE-No significant difference in clinical results in terms of pain, complications, or recurrence. Endoscopy and MED only reduced hospital stay and intraoperative bleeding.[4]

In a meta-analysis from 1997 to 2020, OD, MLD, MED, and FE were associated with:

• Recurrence in 4.1%, 5.1%, 3.9% and 3.5%;
• Re-operations in 5.2%, 7.5%, 4.9% and 4%;
• Wound complications in 3.5%, 3.5%, 1.2% and 2%;
• Durotomy in 6.6%, 2.3%, 4.4% and 1.1% ;
• Neurological complications in 1.8%, 2.8%, 4.5% and 4.9% respectively; and
• Nerve root injury in 0.3% for MLD, 0.8% for MED, and 1.2% for FE.[13]

Enhancing Healthcare Team Outcomes

A high degree of interprofessional coordination and teamwork is necessary for achieving optimal outcomes when performing a discectomy. Beginning with the preoperative diagnostic workup, primary care practitioners must be well versed in the signs and symptoms of a painful herniated disc so that they may start the appropriate workup process and initiate the proper referrals, all while effectively managing the patient's pain. Imaging technicians and radiologists contribute critical information to the diagnostic process through advanced imaging studies, most commonly MRI. Initial management employs pharmacists' expertise in determining the safest and most effective anti-inflammatory medication for each patient. Physical therapists administer the gold-standard first-line treatment; their understanding of human mechanics and therapeutic modalities allows for successful treatment of many disc herniations without surgery.[10] [Level 1]

If conservative treatment fails, a discectomy is an option. Primary care practitioners again play an essential role in providing recommendations for pre-operative medical optimization and clearance. On the day of surgery, peri-operative and operating room nursing staff ensure the patient remains comfortable and safe. They also facilitate providing that necessary medications, equipment, and supplies allow for completion of the procedure. An anesthesiology team with an attending physician and assistant maintain safe and effective analgesia during the surgical procedure. Operating room techs assist in the positioning of the patient and placement of necessary equipment. An electrophysiologist carries out neurologic monitoring for the duration of the procedure. An orthopedic or neurosurgical spine surgeon carries out the procedure with an assistant. Postoperative care is agreed upon and executed by the interprofessional team as described. Effective analgesia in the immediate postoperative period is critical. The physical therapy staff carries out activity recommendations from the surgical team. Social workers ensure that the patient's hospital stay and discharge, once medically clear, are as seamless as possible. The surgeon's office staff coordinates follow-up care so that all steps towards a maximal recovery are in place. 

Recurrence rates of lumbar disc herniation after discectomy are broadly reported and range from 1 to 25%.[8][21][22] [Level 3] A multitude of factors, including medical comorbidities and specific disc herniation patterns, have been shown to play a role in this risk.[34] [Level 2] All involved interprofessional team-members must execute their roles properly and communicate their findings and expertise to the rest of their colleagues to maximize outcomes. Through properly administered conservative treatment modalities, medical optimization accurately indicated surgical intervention, and precise and efficient operations and postoperative care. The interprofessional team caring for patients undergoing discectomy could collectively strive for improved outcomes.

Assessing the need for and performing a discectomy requires an interprofessional team approach, including physicians, specialists, specialty-trained nurses, therapists, and pharmacists, all collaborating across disciplines to achieve optimal patient results. [Level 5]

Proper surgical indication is the mainstay of surgical management of LDH. The nuisances in the pertinent surgical technique must be mastered.[4]