Cervical spine implants

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FACULTY OF MECHANICAL

ENGINEERING

ENGINEERING IN MEDICINE

GROUP M04-31A (THURSDAYS 7:30-10)

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COURSE CREDIT REPORT:

CERVICAL SPINE IMPLANTS

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Author:

Diego Ruperez Esteban

Date of submission: 14/11/2022

Professor: Dr inż. Anna Nikodem

TABLE OF CONTENTS

1. INTRODUCTION        1
2. DEVELOPMENT        5

1. HISTORY        5
2. BRYAN CERVICAL DISC        7

1. Components        7
2. Materials        7
3. characteristics        8
4. Commercial product        8

1. 3D IMPLANTS        10

1. CONCLUSIONS        11
2. SOURCES        12

1. BIBLIOGRAPHY        12
2. FIGURES        13

1.        INTRODUCTION

Cervical spine surgery represents the 20% of all surgeries that take place in the spine. (Rick C. Sasso, Md (spineuniverse) 2019) It is a surgical intervention that is done with the objective of treating neurological compression of the nerves or the spinal canal. This compression can be caused by many different reasons but the two main causes of it are pathologies of the discs and bone formation(osteophytes) problems.

Pathologies of the discs appear when the wear makes that the separation between cervical bones disappear and then a dolorous pressure is generated.

Problems with bone formation appears when some anomaly starts growing due to some illness and generates pressure into the nerves that go through the openings of the vertebrae.

These two problems mentioned here are the main cause of a series of illnesses that lead to a cervical spine surgery. The principal ones are going to be briefly explained here. (Rick C. Sasso, Md (spineuniverse) 2019)[pic 4]

• Cervical disc hernia: It is produced when intervertebral discs suffer an important wear in the neck section, and this leads to compression of nerves close to the medulla. It is the main cause of cervical spine surgery.
• Cervicoartrosis: With the ages the discs, the ligaments and articulations deteriorate. The discs lose their height, are less hydrated

and the cartilage of the articulation losses its properties leading to incorrect alienation of the spine.

• Vertebral infection: There are three levels of infection, the disc one, the vertebrae one and infection of both. This illness takes place when a microorganism invades the zone and causes and infection.

Figure   1-   Hernia   de   disco

cervical        (2019).        spineuniverse. Accessed on 02nd November 2022 from: https://www.spineuniverse.com/espa nol/discos-herniados/hernia-disco- cervical

• Vertebral fracture: This kind of fractures are produced by a serious traumatism. When this happens, it is usually accompanied by a displacement of the vertebra (luxation). This illness is mainly produced in vehicle accidents.[pic 5]

As we have set, this are the main illnesses that lead to a cervical spine surgery, however, there can be also many other reasons as for example deteriorations due to the lifestyle of the patient (extreme sports, incorrect posture, sedentarism…) or having it since the patient was born.

Once we know what is this surgery and the causes that lead to it, we have to explain the different ways of approaching the vertebras and the different techniques that are applied for the surgery.

Figure 2 – Fractura de cuello (2010) Western new york urology associates. Accessed on 02nd November 2022        from:

https://www.wnyurology.com/c ontent.aspx?chunkiid=103568

To approach to the cervical vertebras there are two ways the anterior way and the posterior way. The anterior way is the most used one because it is less aggressive with the muscles of that area, and this makes the recuperation to be less painful for the patient. However, there are some cases in which the posterior way is the only solution so all surgeons must know both ways of approaching. (Medlineplus, 2016)

• Anterior way: As we have already set, this is the most used way to approach to the vertebras and it is used for most of the illnesses previously mentioned. In this way, an incision is made in the anterolateral face of the neck in the middle approximately, then the muscles are split without needing to cut them and a separator is putted to maintain the oesophagus and trachea to the inner part and the carotid to the outer part. In this moment the surgeon is ready to procced with the surgery.[pic 6]

• Posterior way: This is a more aggressive way but sometimes it is the only solution. It is used mainly in vertebral fractures or in hernias that are very lateralized. In this way an incision is made in the middle part of the neck, the cervical muscles are split and then the bone is exposed, and the surgery can go on.

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Figure 5- Comparison of the incision in both ways (2016). Medlineplus. Accessed on 4th November 2022 from:https://medlineplus.gov/spanish/ency/esp_presen tations/100133_3.htm

As we have different ways to approach the affected area, we also

Figure 3- Anterior Way of approaching the vertebras (2016). Awaredoctor. Accessed on        4th        November        2022        from: https://aware.doctor/blog/abordaje- quirurgico-de-la-columna-cervical/

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Figure 4- Posterior way of approaching the vertebras (2016). Awaredoctor. Accessed on        4th        November        2022        from: https://aware.doctor/blog/abordaje- quirurgico-de-la-columna-cervical/

have different kinds of doing the surgery once we have approached the vertebras. Before briefly explaining some of the most used techniques it is important to remind that this surgery is done under general anaesthesia, so the patient is deeply sleepy and does not feel any pain.(Awaredoctor, 2016)

1. Discectomy: It can be done with both ways of approaching. Once the vertebras have been reached, the herniated disc is emptied, and the hernia is taken out. Also, the common posterior vertebral ligament is opened and the bone that is compressing the medulla is taken out. This technique can be accompanied by a cervical fusion or a cervical implant.

1. Cervical fusion: This technique consists of the union of two vertebra to avoid their movement. Apart from a system to fix them, we need to stimulate the bone, so it grows from one vertebra to the other. It can be done with the anterior or the posterior way, a way or another is chosen depending on the illness that has led to the surgery, if it was a hernia, the anterior way is the appropriate one, if it was a fracture, the posterior way is the appropriate one. In this surgery the intervertebral disc is taken out and a metal box and a bone implant are collocated and fixed with a plate with screws to stabilize the vertebra This is the most used technique[pic 9]

Figure 6- Anterior Cervical Discectomy and Fusion (2018). drnesterenko.        Accessed        on        5th        November        2022        from: https://www.drnesterenko.com/2018/04/25/acdf-anterior-cervical- discectomy-fusion/

1. Laminectomy and Laminoplasty: These techniques are both done by the posterior way and their principal objective is to treat compressions that affect various level of the cervical spine. The first technique consists of taking out the posterior part of the vertebra so the medulla can breathe and reduce the compression. The second technique consist of increasing the diameter of the cervical canal by cutting in a special way the vertebra.[pic 10]

Figure 7- Cervicals surgery (2021). drnesterenko. Accessed on 5th November 2022 from: https://www.infoespalda.es/operacion-de-cervicales

1. Corpectomy: This technique consists of taking out a whole vertebra. It is used is cases in which the osteophyte is voluminous and taking out the vertebral disc is not enough to reduce the pressure on the medulla. A metallic box is introduced to substitute the vertebra and we use a plate to fix the box.

1. Cervical disc implant: It is done using the anterior way, the implant has a fixed part that relates to the superior and inferior vertebra and a moving part that is located between both. This technique has the same results as the cervical fusion but with the advantage that the mobility is maintained, and some risks of the cervical fusion are avoided. This technique is used mainly in young people as their pathologies are slighter.

This last technique is the one that we are now going to focus on, as it is the main topic of this report.

1. DEVELOPMENT

The cervical spine implants are mobile devices that are placed between two vertebral bodies of the neck zone, replacing the intervertebral disc that joins them. It is designed to maintain the same mobility and support functions as the natural intervertebral disc.

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