Academic Sharing

Discussion on Large Animal Spinal Implant Surgical Models in Medical Devices

2024-07-25

Preclinical experiments involving implantation in large animals are frequently conducted for medical devices. In particular, the surgical models used for spinal implantation are known to be more complex compared to other experiments. Let’s delve deeper into this topic and continue our discussion here. #### I. Implantation of Pedicle Fixation Products Many spinal orthopedic products involve the implantation at the pedicle site. During the testing process, pedicle operations are also performed in animal models. Large animals that can accommodate spinal fixation implants generally include pigs, dogs, and sheep. Due to anatomical differences, sheep and pigs are the preferred choices for pedicle operations. For example, pedicle screws can be implanted into the lumbar vertebrae of pigs to verify their stability and extraction force. Postoperative CT imaging reveals that due to the choice of screw length, the implant has not fully entered the vertebral body.  *CT image post-implantation* From the CT image post-implantation, we can observe that the implant does not completely enter the vertebral body due to the chosen screw length. In subsequent tests, screws of appropriate length and diameter can be selected for the experiment. As the diameter of the pedicle in animals is generally smaller than that in humans, smaller screws are sometimes utilized for testing.Upon pathological dissection, it can also be observed that the screw avoids the vertebral canal and is primarily implanted along a reasonable pedicle trajectory. #### II. Spine Navigation Products Experiment Currently, the R&D projects of navigation products for spinal operations are increasing on the market, used for intraoperative guidance in spinal surgery.  *In the testing of such products, sheep are generally used as the experimental animals.*  *Based on the data measured during surgery, models are created for calculation to obtain a reasonable needle insertion path and angle.*  *Traditional radiography is also used during the study for real-time fluoroscopy to verify the rationality of puncture guidance.* #### III. Artificial Bone Products Testing New material artificial bones are generally tested in rabbits for spinal fusion studies. In general, autogenous iliac bone is also used as a control in this study. After separation of the ilium, autogenous bone is prepared.  *Bilateral dissection is conducted on the rabbit's lumbar vertebrae to expose the transverse processes for bone graft fusion. After the bone graft fusion, imaging examinations are performed on the animals at appropriate time points to assess the fusion effect.* #### IV. Study on Spinal Nerve-related Products Spinal Nerve-related Product Evaluation Studies on neurostimulation generally aim to verify the long-term safety of the implant and the effectiveness of certain functions.In terms of animal selection, sheep or pigs are generally selected. The main consideration is whether the epidural space inside the vertebral canal can accommodate the size of the implant.  *Taking sheep as an example, procedures are performed on appropriate vertebrae, followed by implantation into suitable segments. Postoperatively, behavioral observations of the animals are conducted, along with imaging evaluations to assess whether the implant is in the predetermined position and its associated neurostimulation functions.* #### V. Conclusion The aforementioned discussion elucidates various large animal models employed in spinal experiments for medical devices, encompassing common test items. As the number of related test products amplifies, novel experiments will be tailored for animal models in alignment with customer testing needs. Through rigorous experimental studies, we endeavor to efficiently complete test projects with precision and accuracy, ensuring the swift market entry of your products and consequently benefiting a greater number of patients. WuXi AppTec Medical Device Testing Center, your trusted partner, is committed to enhancing patient healthcare and quality of life.

Brain implantation test of medical devices

2021-11-23

The international organization for stand...

ISO 10993-23 new method of biocompatibility stimulation test - in vitro stimulation test

2021-08-17

In January 2021, the international organ...

Biological evaluation of medical devices

2021-07-06

In the past decades, with the development of medical technology, medical devices have brought many benefits to clinical patients. At the same time, the potential biological risks caused by their direct or indirect contact with human body have attracted more and more attention. Use of international standard ISO 10993-1, "biological evaluation of medical devices - Part 1: evaluation and testing within a risk management process" issued by FDA in (2016), ISO 10993-1:2018 and GB / T 16886.1: all elaborated the basic principles of biological evaluation of medical devices from the perspective of risk management. At present, the equivalent transformation of GB / T 16886.1:2011 and ISO 10993-1:2018 standards has also entered the stage of soliciting opinions. Although ISO 10993 and GB / T 16886 series standards recommend in vivo and in vitro tests and corresponding test methods for biological evaluation, biological evaluation is neither a set of mandatory test list nor a simple criterion for judging whether it is qualified or unqualified, but a risk assessment process throughout the whole product development stage.

Preclinical animal study of medical devices

2020-08-21

Preclinical animal test of medical devices is to simulate clinical use by applying medical devices to animal models. Because it is closer to the actual clinical use and expected use, it is an important means to evaluate the safety and effectiveness of medical devices for high-risk medical devices and innovative medical devices without clinical application history. Preclinical animal test of medical devices, aiming at different research and development stages and test purposes of medical devices, It is divided into feasibility study (generally carried out in the product design and development stage), safety study and effectiveness study (generally at the stage of product finalization and / or final product). According to the clinical use and characteristics of medical devices, when selecting the animal model that meets the test purpose, priority should be given to the similarity between the structure, function, metabolism and disease characteristics and the human body and its impact on the test results. The higher the similarity between the animal model and the human body, the evidence supported when extrapolating the results to the human level In terms of animal selection, the higher the level, the larger animals, such as beagle dog, Labrador dog, Bama pig, domestic pig, goat, sheep and monkey, and the experimental animals that meet relevant national / industrial standards should be selected as far as possible.

Regulatory requirements for microbial identification

2020-08-19

The establishment of microbiological database of environmental pollution bacteria and tested bacteria through microbiological identification can be used to formulate disinfection and sterilization procedures in clean room / area, correlation analysis of tested bacteria, pollution traceability, and important judgment basis for determining whether to retry, which is of great significance to ensure product quality and the reliability of sterility inspection results. National laws and regulations also put forward clear requirements for microbial identification and identification level, which are summarized below. Microbial identification refers to the process of distinguishing bacteria, yeasts and molds, or determining the level of genera, species and strains by measuring the characteristics of unknown microorganisms with the help of the existing classification system (general rule 9204 of Chinese Pharmacopoeia). According to the Chinese and American Pharmacopoeia, GMP guidelines and PDA tr70, pharmaceutical / device manufacturers need to identify microorganisms under the following circumstances: (1) colonies isolated from the clean room environment (2) positive sterility test results (3) suspicious colonies found in the control bacteria inspection of non sterile drugs (4) microbiological deviation investigation, etc.