A comparative study of a novel absorbable cranial flap fixation system and Aesculap CranioFix

Absorbable cranial flap fixation products, represented by Aesculap^® CranioFix absorbable clamp, are widely used in neurosurgery. However, the product has some shortcomings, as it is not entirely biodegradable, the lower disc's angle cannot be adjusted, and there is a failure to readjust after fixation. To address these issues, MedArt Technology Co., Ltd. from China has come up with a high-purity PLLA combined with an innovative structural design to develop a novel cranial flap fixation system that is more convenient to operate, has a better resetting effect, and can be fully absorbed. This study aims to verify its safety and effectiveness through in vitro experiments and clinical trials.

In this study, the absorbable cranial flap fixation system of MedArt was used as the experimental group, and the CranioFix absorbable clamp constituted the control group. The material properties and the changing trend of mechanical properties of the two groups were compared by accelerated degradation experiments in vitro. A multicenter, randomized, parallel, positive-controlled, non-inferiority clinical study was conducted with a 48-week follow-up. The shortening degree of the bone flap gap, qualified rate of bone flap displacement, changing trend of implant volume, and occurrence of postoperative adverse events were compared between the two groups.

The results of the in vitro accelerated degradation showed that in terms of the decrease in intrinsic viscosity, the control and experimental groups took 7 days and 14 days, respectively, to reach the test endpoint. For mechanical properties, the control group and experimental groups lost clinical safety fixation significance on the 3rd and 4th day after the degradation began, respectively. Regarding the release of degradation products, the control group showed a burst of lactic acid release during the first 3-7 days, while the experimental group released lactic acid slowly and constantly. In the clinical study, 90 patients were randomly enrolled, 87 of whom completed the operation, with an average age of 50. The 3D reconstruction of CT images showed that the bone flap gaps in both groups were less than 2 mm after surgery. The qualified rate of bone flap displacement in the experimental group was 100% after surgery. In contrast, in the control group, there was one unqualified case at 1 week after surgery and two unqualified cases at 6 weeks, 12 weeks, 24 weeks, and 48 weeks. The residual volume of the implant in the experimental group was closer to 50% (about 48.8%) 48 weeks after surgery, than in the control group (about 43.9%) 12 weeks after surgery. Regarding safety, only one possible device-related adverse event occurred in the control group, with an incidence rate of 2.22%, manifested as poor healing at the incision site.

The study has verified that the experimental group had better stability, longer biodegradation time, and better mechanical properties than the control group. Moreover, the experimental group could significantly narrow the cranial flap gap, reduce the flap displacement, and promote skull healing after craniotomy. It shows a fairly reliable fixation effect and safety. TRIAL REGISTRATION INFORMATION: Registry: Chinese Clinical Trial Registry, registration number: ChiCTR2500099674, and date of registration: 27 March 2025 ( https://www.chictr.org.cn/showproj.html?proj=261082 ).