Summaries of studies’ clinical findings related to bone-anchored annular closure.
| Study Citation | Patient Population | Study Design | Sample Size | Follow-Up | Results |
| Klassen et al 201720 a | Radiculopathy + imaging confirmed LDH + failed ≥6 wk of NS care; large annular defect (≥6 mm); mean ages were 43 (22–71) y (AC) and 44 (23–74) y (D) | RCT | D: 278 AC: 272 | 90 d | Significantly lower rate of all-cause SAEs (9.7% vs 16.3 %; P = 0.056) and device- or surgery-related SAEs (4.5% vs 10.2%; P = 0.02) with AC compared with D; reoperation rate at 90 d was 5.4% with D and 1.9% with AC (P = 0.03); device dislocation occurred in 0.7% of AC patients. |
| Van den Brink et al 201929 a | Same study populations and parameters as Klassen et al | 1 y | Significantly lower rates of symptomatic index-level rLDH (8.4% AC vs 17.3% D, P = 0.002); reoperation (6.7% AC vs 12.9% D, P = 0.015); and device- or surgery-related SAEs (7.1% AC vs 13.9% D, P = 0.009). | ||
| Thome et al 201827 a | Same study populations and parameters as Klassen et al | 2 y | Frequency of symptomatic index-level rLDH (12% vs 25%; P < 0.001), composite success index (27% vs 18%; P = 0.02), and device or procedure-related SAEs (7% vs 17%; P = 0.001) significantly improved with AC compared with D; reoperation rate was 13% in D and 5% in the AC groups (P = 0.001); device migration and mesh migration occurred in 1.1% and 1.5% of AC patients, respectively. | ||
| Kienzler et al 201919 a | Same study populations and parameters as Klassen et al | 3 y | Symptomatic index-level rLDH rate (14.8% vs 29.5%; P < 0.001), reoperation rate (11% vs 19.3%; P = 0.007), leg pain (21 vs 30; P < 0.01), back pain (23 vs 30; P = 0.01), ODI (18 vs 23; P = 0.02), physical health component (47 vs 44; P < 0.01), and mental health component (52 vs 49; P < 0.01) scores were significantly improved with AC compared with D; reoperation rate was 19.3% with D and 11% with AC (P = 0.007); all-cause SAE rate was reduced in the AC group (10.7% vs 18.7%; P = 0.008); device-related deficiencies and fracture occurred in 4% and 0.4% of AC patients, respectively. | ||
| Nanda et al 201923 a | Same study populations and parameters as Klassen et al | 4 y | Over 4 years, reoperation rate was significantly lower in AC group (14.4% vs 21.1%; P = 0.03); partial or complete device removal in 23 reoperations; no reoperations were related to endplate changes; magnitude of improvement was greater in AC patients for leg pain (P = 0.04), ODI (P = 0.04), and mental health component scores (P = 0.02). | ||
| Thome et al 202128 a | Same study populations and parameters as Klassen et al | 5 y | AC exhibited statistically significant reductions in symptomatic index-level rLDH (18.8% vs 31.6%; P < 0.001), reoperation (16.0% vs 22.6%; P = 0.03), and device- or surgery-related SAEs (12.0% vs 20.0%, P = 0.008) compared with D; clinically significant improvements in leg pain severity, ODI, and health-related QOL were observed over 5 years with no clinically relevant differences between AC and D; reoperation for device failure was 5.2%; Vertebral endplate changes were more common in AC with no association with clinical outcomes (leg pain, ODI, and health-related QOL). | ||
| Cho et al 201918 | Radiculopathy + radiographically confirmed LDH; mean ages 41 ± 11 y (AC) and 43 ± 12 y (D) | RCT | D: 30 and AC: 30 | 2 y | Significantly greater disc height maintenance (86.3% vs 79.2%; P = 0.04) in AC vs D group; rate of rLDH was 20% in D and 3.3% in AC groups (P = 0.04); no instances of device migration, loosening, or fracture occurred in AC group. |
| Nunley et al 202324 | Radiculopathy + radiographically confirmed LDH; failed ≥6 wk NS care; large annular defect (≥6 mm); mean age 41 ± 13 y (AC) | Prospective cohort | AC: 55 | 1 y | rLDH and reoperation rates were 3.7% and 5.5%, respectively; no device-related SAEs or device integrity failures observed; 4 SAEs observed (hematoma, reherniation, infection, and neurological function decline); 97.1% of patients returned to work by 1 y (median 2.5 wk). |
| Ardeshiri et al 201917 | Symptomatic, MRI-confirmed LDH at single level; disc height ≥5 mm; annular defect ≥6 mm; mean age 45 (23–82) y | Prospective cohort | AC: 75 | 2 y | rLDH rate was 1.4% (1/75); 3 reoperations (4%) required: rLDH, epidural infection, and device dislocation;1 intraoperative implant-associated dural tear occured but did not result in postoperative complications; improper implantation of 1 device in 1 patient, but no associated AEs noted. |
| Sanginov et al 201826 | Symptomatic LDH confirmed by CT or MRI + failed 6 wk of NS care; mean age of 38 (17–63) y | Prospective cohort | AC: 120 | 5 y | 1 ipsilateral (0.8%) and 1 contralateral (0.8%) rLDH (both reoperated); other reoperations included 3 fusions for segmental instability and treatment of 1 epidural hematoma; Modic endplate changes in 20 patients (16.7%) at baseline and 42 (35%) within 5 y of follow-up; no significant differences in pain or function scores between patients with or without endplate changes |
| Kursumovic et al 201721 | Radiculopathy + radiographically confirmed LDH; 90% with annular defect ≥6 mm; mean age 46 (18–75) y | Real-world registry analysis | AC: 171 | 15 mo | Mean follow-up of 15 (1–72) mo; 74% had 12 mo or later follow-up. Six (3.5%) reherniations, 4 of which required reoperation; 22 reoperations were performed across 12 patients (7%), which included 5 fusions, 5 re-discectomies, 4 wound revisions, 3 decompressions, 2 spinal cord stimulators, and 3 unknown; device-related complications in 15 patients (8.8%), 2 of whom required revision surgery. |
| Vukas et al 201330 | Radiculopathy + failed ≥6 wk of NS care + preoperative MRI; mean ages 38 y (AC) and 41 y (D) (18–70 for all) | Prospective comparative cohorts | D: 72 and AC: 30 | 2 y | Improved leg pain (8.9 vs 21.2; P = 0.005), back pain (10.5 vs 19.1; P = 0.27), and disability (11.6 vs 19.8; P = 0.08) with AC compared to D at 2-y follow-up; symptomatic reherniation rate was 6.9% in D and 0% in AC groups; patients were enrolled nonconcurrently; no instances of device-related AEs |
| Sanginov et al 202425 | Radiculopathy + LDH confirmed by MRI + large annular defect (≥6 mm); median age 38 y (AC) | Consecutive case series | AC: 133 | 8 y | rLDH rate was 1.5%, and reoperation rate was 3.0% at 1 y; after 1 y, symptomatic and asymptomatic rLDH were 2.8% and 1.9%; bone resorption was observed in 64% of patients, primarily around the polymer barrier. By 8 years, all resorption stabilized and/or decreased as evidenced by sclerotic rims; maximum resorbed bone volume was 12%. Presence and size of bone resorption had no clinical impact. |
| Lequin et al 201222 | Sciatica with MRI-confirmed LDH + failed ≥6 wk of NS care; Mean age 42 ± 11 y; mean defect width 7.8 mm | Prospective cohort | AC: 45 | 1 y | Of 41 patients, symptomatic rLDH in 1 (2.4%), who also required a reoperation; 3 total reoperations (6.7%): ipsilateral rLDH, contralateral rLDH, and scar tissue management; no evidence of heterotopic ossification or spontaneous fusion and no device complications observed. |
Abbreviations: AC, annular closure; AE, adverse events;CT, computed tomography; D, discectomy group; LDH, lumbar disc herniation; MRI, magnetic resonance imaging; NS, nonsurgical;ODI, Oswestry Disability Index; QOL, quality of life; RCT, randomized controlled trial; rLDH, recurrent lumbar disc herniation; SAE, serious adverse events.
↵a These studies report 90-d, 1-y, 2-y, 3-y, 4-y, and 5-y follow-up time points and outcomes of the same RCT.