MIS-TLIF technology has less blood loss during operation, and no drainage tube can be placed after operation. Xu et al(8). study the necessity of indwelling tube after MIS-TLIF, in the drainage group, 28 patients had an average drainage volume of < 50 ml in the first 24 h after surgery. The complications such as postoperative incision infection and hematoma compression did not increase in the non-drainage group, and their postoperative bedridden period and hospital stay were significantly reduced, postoperative low back pain significantly relieved. It is proved that not placing a drainage tube routinely does not have great risks, and its clinical benefits far exceed the conventional placement of drainage tubes.
The drug used in this study was a mixture of dexamethasone, and vitamin B12. Dexamethasone can inhibit the excitability of nerve endings, improve local blood circulation, make local metabolites easy to be removed from the blood circulation, alleviate local acidosis, and help reduce inflammation. Dexamethasone can significantly expand the pharmacological effects of Vitamin B12. Its molecular mechanism is that dexamethasone has a large molecular size and a complex spatial structure, which affects the release and absorption of Vitamin B12 (9). Vitamin B12 can provide nutrition for nerve tissue, reduce abnormal discharge of damaged nerves, and relieve pain indirectly(10). The combination of two drugs accords with pharmacokinetics and drug individualization principles; the safety, feasibility, and practical value were proved by our previous study(11).
However, concentration of the combination of these drugs is difficult to maintain during surgery. Absorptive gelatin sponge is a semi-synthetic material. Its unique sponge-like structure has protective effects on nerve roots(12), and its collagen properties have a good effect on preventing adhesions around the dura mater and nerve roots after decompression(13). At the same time because of its good hemostatic effect is often used in spinal surgery. Previous researchers have impregnated gelatin sponges with hemostatic drugs and found that gelatin sponges have strong water absorption and slow release of tranexamic acid, which can significantly reduce postoperative wound bleeding in posterior lumbar spine surgery, and do not increase the risk of wound infection and epidural hematoma(14, 15). Gelatin sponges are indeed a good carrier for impregnating drugs.
After research, we found that this method has a good effect on reducing postoperative root pain, and the effect of promoting early recovery. There was no significant difference in the results of the satisfaction survey. Considering that patients who were informed by the surgeon before surgery has a certain psychological expectation, moreover the neurological symptoms of patients after sufficient decompression are significantly relieved than before surgery.
In this study, we found that VAS scores of back pain and leg pain in the two groups began to increase on the second day after surgery (Fig. 2), indicating that radicular nerve root edema pain began to appear at this time, while the VAS score of the control group reached the peak on the 3rd to 4th days after surgery. It may be considered that the early rehabilitation exercise stimulated the radicular nerve root edema to worsen. The appearance of the peak VAS score in the intervention group means that early rehabilitation exercises will indeed stimulate further edema of the nerve root to a certain extent, but its peak value is significantly lower than that in the control group, indicating that the anti-inflammatory effect of the mixed drug is obvious, and the duration more than 72 hours.
In addition, this new method has another obvious advantage. Compared with conventional postoperative routine intravenous or oral administration of various hormones and non-steroidal anti-inflammatory drugs, this study illustrates a cheap and low-cost method, which can greatly reduce the economic burden of patients.
With regard to the use of this new technology, the following points need special attention. First, there is a risk of the local drugs penetration into the dura mater(16). According to our previous clinical experience, it is recommended to use artificial dura to attach to the surface of dura, and then place a gelatin sponge impregnated with mixed drugs. Artificial dura mater can not only prevent nerve root adhesion, but also slow down the spread of mixed drugs to the subdural space.
Although there are obvious differences in the relief of pain between the intervention group and the control group, some patients still have recurrent pain after surgery. Elderly patients may experience more drug dependence relative to younger patients(17), and individual differences in pain sensitivity must also be considered. In addition, it is not clear how long the effectiveness of mixed drugs lasts, or whether the mixing ratio is able to achieve the best results, therefore further research is still needed. All in all, there are inevitably all kinds of biases, but the data of this study is reliable in general, and there is no possibility of false-positive results caused by obvious biases.