What are Patient-Specific Spine Implants?
Patient-specific spine implants are devices surgeons utilize during spine surgery to treat spinal deformity, stabilize and strengthen the spine, and facilitate spinal fusion. These are customized implants, tailored to the precise anatomical and surgical requirements of each patient, with the objectives of minimizing anatomical remodeling and improving bone-implant interface mechanics, osseointegration, and surgical outcomes, as well as improving patient outcomes.
Most patient-specific spine implants are made of metals such as titanium, titanium-alloy, or stainless steel, while some are made of non-metallic compounds. The implant materials are biocompatible or body-friendly and able to provide optimal spinal strength and stabilization. They come in many different sizes and shapes to accommodate different patients of all ages.
Anatomy of the Spine
The spine is made up of small bony segments called vertebrae. These vertebrae are categorized into cervical or neck vertebrae, thoracic (upper back), and lumbar (lower back). Cushioning discs present between each vertebra act as shock absorbers. A cylindrical bundle of nerve fibers called the spinal cord passes through the entire vertebral column and branches out to the various parts of our body. Any damage or deformity to the bones of the vertebral column or to the discs present between the vertebrae can damage these nerves, leading to pain in the body part that the nerve supplies.
Indications for Patient-Specific Spine Implants
Patient-specific spine implants may be indicated to treat spinal instability caused by spinal disorders such as:
- Degenerative disc disease (DDD): DDD refers to the gradual deterioration or degeneration of the intervertebral discs between the vertebrae due to aging.
- Scoliosis: Scoliosis is a condition where the spine or back bone is curved sideways instead of appearing in a straight line.
- Kyphosis: Kyphosis is characterized by an abnormal spinal curvature, which causes a physical deformity of the upper back, commonly known as hunchback.
- Spondylolisthesis: Spondylolisthesis is the displacement of a vertebral disc from the spinal column.
- Traumatic spine fracture: Traumatic spine fracture refers to fracture or dislocation of the vertebrae (backbone) and can occur anywhere along the spine.
Preparation for Patient-Specific Spine Implants
Preoperative preparation for patient-specific spinal implant surgery may involve the following steps:
- A review of your medical history and a physical examination are performed by your doctor to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging such as a CT scan to create the patient-specific spine implant required for the procedure.
- You will be asked if you have allergies to medications, anesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking or any conditions you have such as heart or lung disease.
- You may be asked to avoid medications such as blood thinners, aspirin, or anti-inflammatories for a specific period.
- You will be placed on a special diet prior to surgery and laxatives may be used to clean out your bowel.
- You should refrain from alcohol or tobacco at least a few days prior to surgery and several weeks after as it can hinder the healing process.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- You are advised to arrange for someone to drive you home after surgery.
- A signed informed consent form will be obtained from you after the pros and cons of the surgery have been explained.
Procedure for Patient-Specific Spine Implants
Patient-specific spine implants are most often utilized during spinal fusion surgery to stabilize an unstable spine as a result of conditions such as a traumatic fracture or slipped vertebrae (spondylolisthesis) originating from degenerative intervertebral discs. The procedure may involve the following steps:
- You will lie face down on the operating table under the influence of general anesthesia.
- A surgical cut is made over the affected vertebrae (cervical, thoracic or lumbar area).
- Muscles surrounding the affected vertebrae are retracted to gain access to the damaged vertebrae.
- The damaged vertebral bone or intervertebral disc is removed from the affected area of the spinal column.
- Your surgeon then performs spinal fusion. Spinal fusion can be performed through different angles depending upon the specific advantages of each and the choice of your surgeon. It may involve interbody fusion where a bone graft is placed in the space present between the two vertebrae. Other techniques may also be employed for spinal fusion that involves the entire removal of the disc between the affected vertebrae. A patient-specific spine implant made of titanium is then placed between the vertebrae. This implant fabricated individually from CT data enables your surgeon to restore natural spine alignment and height of the disc, as well as assist fusion.
- The fusion process is followed by spinal instrumentation, which involves fitting titanium screws, rods, cages, or plates to stabilize the vertebrae and further accelerate bone fusion.
- Following this, care is taken to reposition the soft tissues carefully and the incision is closed.
Postoperative Care and Recovery
Postoperative care instructions and recovery involved with patient-specific spine implants may involve the following steps:
- You will be transferred to the recovery area where your nurse will closely observe you for any allergic/anesthetic reactions and monitor your vital signs as you recover.
- You may experience pain, inflammation, and discomfort in the operated area. Pain and anti-inflammatory medications are provided as needed to address these.
- Application of cold and warm compresses to the treatment area is also recommended to reduce inflammation and pain.
- Antibiotics are also prescribed as needed to address the risk of surgery-related infection.
- You are encouraged to walk and move around in bed with support as frequently as possible to prevent the risk of blood clots.
- Instructions on surgical site care and bathing will be provided to keep the wound clean and dry.
- Avoid lifting, bending, or twisting your back for the first 6 weeks. Do not lift anything heavier than 5 pounds for the first 2 weeks. Refrain from any strenuous activities such as housework, yard work, or sex for at least a month.
- A corset or brace is recommended to limit bending and assist with the healing of the fused region.
- A physical therapy protocol is recommended to help strengthen the spinal area and optimize its function. Walking is a good exercise and is strongly recommended to improve your endurance.
- Refrain from driving until you are fully fit and receive your doctor’s consent.
- You should be able to resume your normal activities in a couple of weeks but may have certain activity restrictions.
- Complete recovery and return to work vary from patient to patient as it is related to a patient’s overall health status and the type of work one does.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Risks and Complications
Spinal surgery involving patient-specific spine implants is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as:
- Infection
- Bleeding
- Blood clots
- Allergic/anesthetic reactions
- Hardware failure
- Bone graft migration
- Persistent pain
- Failure of vertebral fusion
- Injury to adjacent organs, nerves, or blood vessels
