Summary of literature review for amniotic membrane–derived biologic agents on postoperative outcomes following spinal surgery.
| Study | Design | Tissue Type | Objective | Methods | Results |
| Animal Studies | |||||
| Bolat et al33 (2013) | Retrospective animal (rat) study | HAF | Evaluate effects of mitomycin-C, sodium hyaluronate, and amniotic fluid on prevention of spinal epidural fibrosis | A total of 4 groups (10 each): control, mitomycin-C, sodium hyaluronate, and amniotic fluid. L5 total laminectomy performed and assessed for epidural fibrosis 4-wk postoperative | Significant difference in amount of scar tissue (none) in experimental groups compared with control group |
| Choi et al34 (2011) | Experimental animal (rat) study | FAM | Evaluate effects of amniotic membrane on epidural adhesions after laminectomy | A total of 20 rats, 2 groups. Laminectomy with or without amniotic membrane. Assessment at 1-, 3-, and 8-wk postoperative | Significant decrease in amount and tenacity of scar tissue in amniotic membrane group |
| Cunningham et al35 (2019) | Experimental animal (sheep) study | Dual-layer, chorion-free amnion patch from HAM | Evaluate effect of dual-layer, chorion-free amnion path following lumbar laminectomy | A total of 12 sheep, 2 groups: control and amnion. Laminectomy performed with or without amnion, and half were evaluated at 4 wk, half at 10 wk | Significant decrease in amount of fibroblast infiltration and tissue tenacity with the use of amnion |
| Goldschlager et al36 (2011) | Experimental animal (sheep) study | AECs | Comparison of allogeneic mesenchymal precursor cells to AECs in promoting osteogenesis | A total of 29 sheep divided into 5 groups: (1) C3-C4 ACDF with autograft IC and IBC, (2) HA/TCP Mastergraft granules alone, (3) HA/TCP with 5 million MPCs, (4) HA/TCP with 5 million AECs, and (5) nonoperative | MPCs lead to significantly more fusion than any other group, and all AECs failed to have any fusion at all |
| Kara et al38 (2015) | Experimental animal (rat) study | HAF and HAM | Evaluate effectiveness of amniotic fluid and membrane on prevention of postlaminectomy spinal epidural fibrosis | A total of 27 rats underwent 2 nonconsecutive lumbar laminectomies were divided into either: (1) laminectomy alone, (2) laminectomy + AM, (3) laminectomy + AF. Sacrificed at 6 wk | No significant differences between groups in regard to epidural scar formation and mean fibroblast count |
| Luo et al39 (2019) | Experimental animal (rabbit) study | Amniotic suspension allograft containing particulated HAM and HAF | Evaluate whether amniotic suspension allograft increases intervertebral disc height and morphology after disc degeneration | A total of 12 rabbits underwent disc puncture and then 4 wk later were injected with either amniotic suspension allograft, sham control, or were left untreated. Assessed over 12 wk | At 12 wk, experimental group had significantly greater disc height, magnetic resonance imaging T2 relaxation times, and improved morphology compared with control and untreated groups |
| Oner et al40 (2015) | Experimental animal (rat) study | HAF | Assessment of 2 different bone grafts and amniotic fluid on vertebral fusion in rat model | A total of 48 rats were randomized into 1 of 4 groups: allograft group, allograft plus AF, DBM group, or DBM plus AF. Fusion of spine was assessed at 8 wk | Amniotic fluid significantly enhanced posterior spinal fusion when combined with allograft |
| Tao and Fan42 (2009) | Experimental animal (dog) study | FAM, CAM, and AFF | Evaluate whether AM can reduce epidural scar adhesion after laminectomy in canine model | A total of 24 dogs underwent laminectomy at L1, L3, L5, and L7 with FAM, CAM, AFF, and no treatment assigned randomly to each of the 4 sites. Animals were sacrificed at 1, 6, and 12 wk postoperative | CAM group had significantly lower amounts of epidural fibrosis compared with controls |
| Human Studies | |||||
| Anderson et al32 (2017) | Prospective, RCT | Cryopreserved amniotic membrane (cAM) | Compare pain, functional outcomes and recurrent herniation follow lumbar microdiscectomy w/ or w/o amniotic tissue graft | A total of 80 patients randomized to either amniotic tissue or no tissue following elective lumbar microdiscectomy | AM group had greater functional outcomes and no recurrent herniations at 2 years |
| Kamson and Smith37 (2020) | Prospective, RCT | Cryopreserved amniotic-derived products | Comparison of PROM after use of orthobiologic supplementation during endoscopic-assisted lumbar decompression surgery | A total of 269 patients randomized to receive either amniotic membrane, bone marrow aspiration, both, or none during lumbar decompression | Patients receiving either bone marrow aspirate or amniotic membrane had significantly decreased pain at all timepoints compared with control |
| Subach and Copay41 (2015) | Retrospective case series | Dehydrated human amnion/chorion membrane | Evaluation of AM on epidural scar formation after transforaminal lumbar interbody fusion | A total of 5 patients who had transforaminal lumbar interbody fusion with AM who subsequently underwent epidural re-exploration | Four of 5 cases had easily detachable tissue during epidural re-exploration |
| Walker et al43 (2018) | Retrospective case series | HAM | Evaluate HAM in the prevention of spinal retethering after detethering | A total of 14 patients received HAM after detethering. Followed for minimum of 6 mo | Only 1 patient required subsequent detethering |
Abbreviations: ACDF, anterior cervical discectomy and fusion; AECs, amnion-derived epithelial cells; AF, amniotic fluid; AFF, autologous-free fat; AM, amniotic membrane; CAM, cross-linked amniotic membrane; DBM, demineralized bone matrix; FAM, freeze-dried human amniotic membrane; HAF, human amniotic fluid; HA/TCP, hydroxyapatite-tricalcium phosphate; IBC, interbody cage; IC, iliac crest autograft; MPCs, mesenchymal precursor cells; RCT, randomized controlled trial.
Note: Boldface indicates the primary variables being measured or outcomes of interest in each selected study.