Table 6.
Prospective cohort studies
| Study | Main inclusion criteria, main exclusion criteria | Number of participants type/level LDH | Interventions/technique/instrumentation | Follow-up: duration and outcome | Comment |
|---|---|---|---|---|---|
| Hoogland et al. [17] | Inclusion criteria | n = 262 ♀76 ♂186, mean 46 years, range 18–80 | Endoscopic transforaminal discectomy (ETD) | Follow-up: 24 months, 9% lost to follow-up | Authors included only patients with recurrent LDH, more than 6 months after open microdiscectomy or endoscopic surgery |
| Previous surgery (same level) | Type: all LDH | Intradiscal and intracanal technique | Pain leg (VAS): pre-op. 8.5, follow-up 2.6, differences 5.9 = 69% | ||
| Recurrent disc herniation | Level: single level, L2–S1 | Thessys instrumentation | Pain back (VAS): pre-op. 8.6, follow-up 2.9, difference 5.7 = 66% | ||
| Radiculopathy | GPE (MacNab): 31% excellent, 50% good, 2.5% poor | ||||
| Post-tension sign | Patient satisfaction: 51% excellent, 35% good, 5% poor | ||||
| Neurological deficit | Recurrence: 6.3% | ||||
| Exclusion criteria | Complications: 1.1% | ||||
| Not specified | Re-operations: 7% | ||||
|
Hoogland and Schenkenbach [15] Schenkenbach and Hoogland [51] |
Inclusion criteria | n = 130 ♀43 ♂87, mean 39 years | Endoscopic transforaminal discectomy (ETD) | Follow-up: 12 months, 5.1% lost to follow-up | |
| Radiculopathy | Type: all LDH | Intradiscal and intracanal technique | Pain leg (VAS): difference 5.9 | ||
| Post-tension sign | Level: single level, L2–S1 | Thessys instrumentation | Pain back (VAS): difference 5.4 | ||
| Neurological deficit | GPE (MacNab): 56% excellent, 27% good, 6% poor | ||||
| Exclusion criteria | Return to work (6 weeks): 70% | ||||
| Not specified | Complications: 1.5% | ||||
| Re-operations: 4.6% | |||||
| Kafadar et al. [20] | Inclusion criteria | n = 42 ♀2 ♂40, range 18–74 years | Percutaneous endoscopic transforaminal discectomy (PETD) | Follow-up: mean 15 months (range 6–24) (SD 4), 0% lost to follow-up | Authors excluded n = 8 from analyses due to stopped procedures. These were taken into account in this review |
| Radiculopathy | Type: all LDH | Pure intradiscal technique | GPE (S/S-score): 14% excellent, 36% good 36% poor | ||
| Post-tension sign | Level: single level, L4–L5 | Karl Storz instrumentation | Recurrence: 0% | ||
| Neurological deficit | Complications: 45% | ||||
| Exclusion criteria | Re-operations: 17% | ||||
| Previous surgery(same level) | |||||
| Spinal stenosis | |||||
| Segmental instability | |||||
| Calcified LDH | |||||
| Kambin [23]; Kambin | Inclusion criteria | n = 175 ♀76 ♂99 | Arthroscopic microdiscectomy and selective fragmentectomy | Follow-up: mean 48 months (range 24–78), 3.4% lost to follow-up | |
| Radiculopathy | Type: all LDH | Pure intradiscal technique | GPE (Modified Presby, St Luke score): 77% excellent, 11% good, 12% failed | ||
| Post-tension sign | Level: single level, L2−S1 | Kambin technique | Return to work (3 weeks): 95% | ||
| Neurological deficit | Biportal n = 59 | Complications: 5.3% | |||
| Exclusion criteria | Re-operations: 7.7% | ||||
| Large extraligamental LDH | |||||
| Previous surgery (same level) | |||||
| Cauda syndrome | |||||
| Degenerative disc | |||||
| Knight et al. [27]; Knight et al. [29] | Inclusion criteria | n = 250 ♀? ♂?, mean 48 years, range 21–86 | Endoscopic laser foraminoplasty (ELF) | Follow-up: mean 30 months (range 24–48) (SD 5.87), 3.2% lost to follow-up | Authors included also degenerative and lateral stenosis in this study |
| Prior disc surgery n = 75 | Type: All LDH | Intradiscal and intracanal technique | Pain (VAS > 50% improvement): 56% | ||
| Back pain | Level: single and multiple level, L2–S1 | Richard Wolf instrumentation | Functional status (ODI): 60% improved ≥ 50% | ||
| Leg pain | Complications: 0.8% | ||||
| Radiculopathy | Re-operations: 5.2% | ||||
| Exclusion criteria | |||||
| Cauda syndrome | |||||
| Painless motor deficit | |||||
| Lee et al. [33] | Inclusion criteria | n = 116 ♀43 ♂73, mean 36 years, range 18–65 | Percutaneous endoscopic lumbar discectomy (PELD) | Follow-up: mean 14.5 months (range 9–20), 0% lost to follow-up | |
| Radiculopathy | Type: not specified | Intradiscal and intracanal technique | Pain leg (VAS): pre-op. 7.5, follow-up 2.6, difference 4.9 = 65% | ||
| Neurological deficit | Level: single level, L2–S1 | YESS, Richard Wolf instrumentation | GPE (Modified MacNab): 45% excellent, 47% good, 6.0% poor | ||
| Non-contained or sequestered LDH | Return to work: average 14 days, range 1–48 days | ||||
| Exclusion criteria | Recurrence: 0% | ||||
| Previous surgery (same level) | Complications: 0% | ||||
| Central or lateral stenosis | Re-operations: 0% | ||||
| Segmental instability | |||||
| Morgenstern et al. [42] | Inclusion criteria | n = 144 ♀48 ♂96, mean 46 years, range 18–76 | Endoscopic spine surgery | Follow-up: mean 24 months (range 3–48), 0% lost to follow-up | Primary outcome of this study was to compare normal versus intensive physical therapy post operative revalidation |
| Radiculopathy | Type: all LDH | Intradiscal and intracanal technique | GPE (MacNab): 83% excellent and good, 3% poor | ||
| Neurological deficit | Level: multiple level n = 60, L1–S1 | YESS, Richard Wolf instrumentation | Complications: 9% | ||
| Exclusion criteria | Re-operations: 5.6% | ||||
| Sequestration | |||||
| Ramsbacher et al. [45] | Inclusion criteria | n = 39 ♀21 ♂18, mean 50 years | Transforaminal endoscopic sequestrectomy (TES) | Follow-up: 6 weeks, 0% lost to follow-up | |
| Radiculopathy | Type: all LDH | Intracanal technique | Pain leg (VAS): pre-op. 6.7, follow-up 0.8, difference 5.9 = 88% | ||
| Neurological deficit | Level: single level, L3–S1 | Sofamor–Danek endoscope | Pain back (VAS): pre-op. 5.1, follow-up 1.3, difference 3.8 = 74% | ||
| Exclusion criteria | PS: 77% (very satisfied + satisfied) | ||||
| Far migrated sequesters | Complications: 5.1% | ||||
| Central or lateral stenosis | Re-operations: 10% | ||||
| High iliac crest | |||||
| Ruetten et al. [46] | Inclusion criteria | n = 517 ♀277 ♂240, mean 38 years, range 16–78 | Extreme-lateral transforaminal approach | Follow-up: 12 months, 10% lost to follow-up | |
| Radiculopathy | Type: all LDH | Intracanal technique, Richard Wolf instrumentation, n = 27 bilateral | Pain leg (VAS): pre-op. 7.1, follow-up 0.8, difference 6.3 = 89% | ||
| Neurological deficit | Level: multiple level n = 46, L1–L5 | Pain back (VAS): pre-op. 1.8, follow-up 1.6, difference 0.2 = 13% | |||
| Exclusion criteria | Functional status (ODI): pre-op. 78, follow-up 20, difference 58 = 74% | ||||
| Far cranial/caudal migrated sequester | Recurrence: 6.9% | ||||
| Previous surgery (same level) | Complications: 0% | ||||
| Spinal stenosis | Re-operations: 6.9% | ||||
| Sasani et al. [48] | Inclusion criteria | n = 66 ♀36 ♂30, median 52 years, range 35–73 | Percutaneous endoscopic discectomy (PED) | Follow-up: 12 months, 0% lost to follow-up | |
| Radiculopathy | Type: foraminal + extraforaminal LDH | Pure intradiscal technique Karl Storz instrumentation | Pain (VAS): pre-op. 8.2, follow-up 1.2, difference 7.0 = 85% | ||
| Post-tension sign | Level: single level, L2–L5 | Functional status (ODI): pre-op. 78, follow-up 8, difference 70 = 90% | |||
| Neurological deficit | Complications: 6.1% | ||||
| Exclusion criteria | Re-operations: 7.6% | ||||
| Previous surgery (same level) | |||||
| Schubert and Hoogland [54] | Inclusion criteria | n = 558 ♀179 ♂379, mean 44 years, range 18–65 | Transforaminal nucleotomy with foraminoplasty | Follow-up: 12 months, 8.7% lost to follow-up | |
| Radiculopathy | Type: all LDH | Intracanal technique, Thessys instrumentation | Pain leg (VAS): pre-op. 8.4, follow-up 1.0, difference 7.4 = 88% | ||
| Post-tension sign | Level: single level, L2–S1 | Pain back (VAS): pre-op. 8.6, follow-up 1.4, difference 7.2 = 84% | |||
| Neurological deficit | GPE (MacNab): 51% excellent, 43% good, 0.3% poor | ||||
| Sequestration | Recurrence: 3.6% | ||||
| Exclusion criteria | Complications: 0.7% | ||||
| Previous surgery (same level) | Re-operations: 3.6% | ||||
| Suess et al. [57] | Inclusion criteria | n = 25 ♀11 ♂14, mean 48 years, range 26–72 | Percutaneous transforaminal endoscopic sequestrectomy (PTFES) | Follow-up: 6 weeks, 0% lost to follow-up | All patients operated under general anaesthesia and EMG monitoring |
| Radiculopathy | Type: foraminal + extraforaminal LDH | Pure intradiscal technique, instrumentation not specified | Pain leg (VAS): pre-op. 6.7, follow-up 0.8, difference 5.9 = 88% | ||
| Neurological deficit | Level: single level, L2–L5 | Pain back (VAS): pre-op. 5.1, follow-up 1.3, difference 3.8 = 75% | |||
| Exclusion criteria | Complications: 4% | ||||
| Cauda syndrome | Re-operations: 8% | ||||
| Spinal stenosis |
Intervention as quoted in original article. Post-tension signs denotes positive tension signs (straight leg raising test or contralateral straight leg raising test)
Outcomes: S statistically significant, NS not statistically significant, PS patient satisfaction, MacNab MacNab score as described by MacNab [39]. The sum of ‘excellent’ and ‘good’ outcomes are labelled ‘satisfactory’, GPE global perceived effect, S/S-score Suezawa and Schreiber score [40], Presby. St Luke score Rush-Presbyterian-St Luke score [23], ODI Oswestry disability index [38]