J Orthop Surg Res 14, 6 (2019). Furthermore, to our knowledge, for the first time we used extraction torque during screw removal surgery to analyze risk factors for screw loosening, our findings demonstrated that screws in non-fusion spine and fractured vertebrae had significantly lower extraction torque, while BMD and age showed low, but significant linear correlation with extraction torque. The titanium alloy pedicle screws (Johnson&Johnson, USA; Medtronic, USA; Stryker, USA; Kanghui Med, China; FULE, China) with diameter of 4.0 to 6.5mm and length of 30 to 55mm were used in the primary surgeries. 2023 BioMed Central Ltd unless otherwise stated. 3b. Or it can cause back and leg (or arm) pain, depending on whether the fusion is at the cervical (neck) or lumbar (low back) level. Eur Spine J. For more information about revision procedures to correct broken spinal hardware, or to talk to a spine specialist about any discomfort youre experiencing with your hardware, reach out to Dr. Changs office today. p=0.437, Mann-Whitney Test. Article While methods for spine surgery have significantly improved over the years, a patients recovery still depends on their own diligence and dedication, so following the Dos and Donts of spinal fusion recovery is a must. This is done through a bone graft typically. Nerve damage: It's conceivable that nerves or blood vessels will be damaged as a result of these procedures. Pedicle screw loosening is a common complication after spine surgeries. Dakhil-Jerew F, Jadeja H, Cohen A, Shepperd JA. Return of symptoms. *p<0.001, Kruskal-Wallis test. By clicking Accept All, you consent to the use of ALL the cookies. Common symptoms of failed back . Meanwhile, by using extraction torque data, we analyzed the risk factors of screw loosening. Neurosurg Focus. In general, we found a 33% pedicle screw showed an extraction torque less than 1.02Nm, which might be considered to be loosening according to our data distribution. Informed consent was obtained from all individual participants included in the study. References If the patient has symptoms that seem to be coming out of the loose screw or if there is movement of the spine because of loosening of plate or fracture, the . Damaged hardware may be replaced or additional hardware may be inserted to ensure healing takes place as expected and so your spine can handle any future stress your body may put on it. b Lateral X-ray showed that the same screw was pulled out (white arrow). Why is a screw not good for MDF? Eur Spine J. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. All rights reserved | Website designed & developed by Samskriti Business Solutions Pvt Ltd, symptoms of loose screws after cervical spinal fusion, How to Choose the Right Spine Surgeon? Methods: Theater records from a single spinal surgeon's practice were reviewed to identify patients that had undergone lumbar fusion for discogenic back pain with subsequent pedicle screw instrumentation removal (Expedium, DePuy Synthes) in the preceding 3 years with a minimum of 18 months follow-up. 2000;25(7):85864. X-ray criteria for screw loosening were a radiolucent zone surrounding the screw thicker than 1mm and/or the double halo sign. There is a dramatic decline in screw numbers between 0.90 and 1.20Nm. In a small percentage of men who have an anterior fusion, an infrequent complication results in difficulties with ejaculation following spine fusion surgery. If, however, the broken screw was pressing on a nerve or obstructing the spinal canal, surgery to remove the instrumentation would be considered. f No significant difference of extraction torque was found among different screw diameter. Your problem with nerve pain after a broken screw will require a shotgun blast of medications used aggressively in these early, critical stages. Pedicle screw loosening: the value of radiological imagings and the identification of risk factors assessed by extraction torque during screw removal surgery. A possible explanation could be that surgeries performed in lumbosacral spine were mainly for degenerative disc diseases, which often required spinal fusion, while in the thoracolumbar spine, where operations were more likely for vertebral fracture, fusion were not always necessary. Once theyve established whats going on in your spine, the spine surgeon will walk you through your options. Loosening of instrumentation frequently occurs when the bones of the spine dont heal or fuse correctly; this poor healing my also cause hardware to shift or break. 3a. Wu JC, Huang WC, Tsai HW, Ko CC, Wu CL, Tu TH, Cheng H. Pedicle screw loosening in dynamic stabilization: incidence, risk, and outcome in 126 patients. Manage cookies/Do not sell my data we use in the preference centre. The results showed a low but significant linear correlation between extraction torque and patients age p=0.045, R2=0.123, F=4.345, Linear regression analysis. The mean torque of screws was 1.551.00Nm. Surgery in L5 S1 Fusion is denoted by its level. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Faraj AA, Webb JK. The limitation of radiological approaches led to a great variety of screw loosening rate in literatures. In my practice, I often order a CT scan around 3 months to verify the instrumentation is not loose and there are early signs of bone growth (fusion). Depending on the patient, the bones can fuse quickly, or they can take some time. Injury in the nerves: Naturally, when dealing with the spine, there is always a risk of suffering through nerve damage. If you have had a lumbar fusion, then there is always the risk of a hardware malfunction, failure or breakage. 1994;19(15):17528. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Linear regression analysis was used to estimate the relevance between the extraction torque of pedicle screw and other clinical findings. Normal movement places small stresses on normal bones, which can actually flex a tiny bit; but motion also stresses the hardware, which is rigid - that's the point of putting it in; and since the metal won. It can occur without symptoms so the patient doesn't even know he or she has it. The thing about surgery is there is 'inherent risks'. You might experience the following side effects: Loose or broken screws. c Screw placed in fractured vertebrae showed significantly lower extraction torque than those in non-fractured vertebrae. Spinal fusion is a time-tested surgical approach to many types of chronic spine-related pain, especially in the neck and lower back. The distribution of screws in three clusters based on extraction torque by Twostep Cluster. Our results showed a low but significant linear correlation between extraction torque and BMD (p=0.010, R2=0.304, F=8.296) as well as age (p=0.045, R2=0.123, F=4.345), indicating pedicle screw in aged patients or those with low bone density may be less stable according to mechanical measurement, as shown in Figs. During the follow-up period, 97 patients had presented with CT signs of pedicle screws loosening (1-mm radiolucent zone around at least 1 screw and double halo sign); however, out of those only 39 complained of axial pain with ODI values over 40; those patients underwent revision surgery. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. As shown in Tables3 and4, the X-ray criteria of loosening had a sensitivity of 24% and a specificity of 98%, while the CT scan criterion of loosening had a sensitivity of 22% and a specificity of 96%. My question isShould I contact the surgeon who performed my surgery back in N.Y.? I have three surgeries and the last one they put rods in;The screws have pulled loose from the top of the rods. In June of 2005, I underwent anterior cervical spine fusion surgery. Those with significant pedicle malplacement or destructive spine disorders, such as bone metabolic disease, were excluded from our study. p=0.746, Kruskal-Wallis test. The mean torque of screws placed in the lumbosacral junction (L4, L5, and S1, n=54) was 2.141.12Nm, which was significantly higher than those placed in other segments. Is surgery required for my unstable spondylolisthesis? A nurse will take you through the hospital admissions and discharge procedures. Thirty-three patients who underwent pedicle screw removal surgery after at least 2years from primary surgery were evaluated preoperatively for fixation stability by X-ray and CT scan. 2000;9(2):97103. Rods, screws and plates are all common forms or hardware that are inserted, and while they are quite durable, they arent a perfect solution. A postoperative complication of a surgery for a back injury is to sustain a broken screw. Pseudarthrosis: The result of when spinal fusion surgery fails. Hi everyone i'm back from seeing the surgeon. These include excessive bleeding, reactions to drugs or anesthesia or formation of blood clots in vessels that might break free and damage organs, including the lungs. Original question: What are the symptoms of a spinal fusion screw coming loose? However, in 24 patients who underwent multilevel (more than two segments) instrumentation, there was no significant difference regarding extraction torque (p=0.437) between screws placed in the end segments (n=88) and those in the mid segments (n=103), as shown in Fig. Therefore, spinal hardware (e.g. There were 26 screws placed in 13 fractured vertebrae. Nevertheless, the specific details regarding X-ray criteria of loosening were not described in most papers, suggesting that the subjective viewpoints of surgeon and radiologist played an important role. What happens to atoms during chemical reaction? Spinal muscle injury. 1). However, nearly all cases resolve spontaneously within 2 years, thus identifying patients who require more detailed or invasive work-up is a challenging task for clinicians. Esses SI, Sachs BL, Dreyzin V. Complications associated with the technique of pedicle screw fixation. Right Posture to Escape & Avoid Neck Pain. Early complications of spinal pedicle screw. Ozawa T, Takahashi K, Yamagata M, Ohtori S, Aoki Y, Saito T, Inoue G, Ito T, Moriya H. Insertional torque of the lumbar pedicle screw during surgery. After the fusion is completely healed, the screws . As expected, extraction torques of pedicle screw after fusion surgery (n=142) were significantly higher than those in non-fusion surgery (n=84) (p=0.001), as shown in Fig. Because of metal artifact, no signal zone was usually seen around screw tail, which could not be interpreted as screw loosening (Fig. 2012;132(4):4716. (L3-5) stabilization system and in whom the left L-5 pedicle screw broke (B, arrow) 24.5 months after surgery without clinical symptoms. Previous ACDF involving C6, C7, and T1. The mean torque of screws placed in fractured vertebrae was 1.030.63Nm, which was significantly lower (p=0.009) than those in non-fractured vertebrae, as shown in Fig. Roellinghoff reported that in 64 patients treated with multilevel pedicle screw fixation, 35(54.69%) patients showed radiographic signs of screw loosening [16]. We also tested the average torque of newly implanted screws and found that 1.02Nm was lower than the low limit of 95% confidence interval of newly implanted screws. It may take 1-3 hours depending on your own condition. The cutoff values were 1.02 and 2.22Nm. This type of pain is called neurogenic or neuropathic pain. Steps to Take. Yes, you absolutely can. 3d. pain and redness in your lower legs that might extend above your knee chest pain a cough shortness of breath Symptoms of an infection include: severe pain fever chills redness and swelling and. If after 6-12 months a patient continues to have or experience new pain, more imaging may be pursued. Are there some people who "reject" the hardware that is in their body or does it definitely mean the fusion surgery has to be redone. Extraction torque, as an objective mechanical indicator, has been used to evaluate the mechanical fixation of pedicle screws in animal model [19]. Eur Spine J. The main role of the screw in lumbar fusion is to reduce the motion of the spine and to conduct the stabilization, whereas screw loosening is observed in quite a few literature works (7)(8)(9). For many people working from home, neck pain becomes a big problem. No vertebral body fractures or facet joint dislocations. Orthop Rev. I always tell my patients that fusion is a two-part process. Sanden B, Olerud C, Petren-Mallmin M, Johansson C, Larsson S. The significance of radiolucent zones surrounding pedicle screws. When this separation occurs, then the screw is held by these loose, torn fibers which do not have a lot of strength, as you might imagine. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. The average value should be $1.5 Million - $5.5 Million on a broken screw back surgery case. You can tell if the screws attached are loose when a sudden pain is experienced or when you feel bulges in your spine. An in vivo study of pedicle screw fixation augmenting posterior lumbar interbody fusion. e Extraction torques of pedicle screw after fusion surgery (n=142) were significantly higher than those in non-fusion surgery. The minimal time interval between primary surgery to screw removal was 18months. In total, 236 screws were taken out, and the extraction torque data was recorded and analyzed to identify the sensitivity and specificity of both imaging studies for screw loosening. Four breaking screws were detected. Symptoms of FBSS. 4 What are the symptoms of a failed laminectomy? Privacy No funding was received for the current study. Powered by, Minimally Invasive Surgery Lumbar Spine, Anterior Cervical Discectomy and Fusion (ACDF), Minimally Invasive Surgery Cervical Spine, Vagal Nerve Stimulation and Seizure Epilepsy Surgery. A spinal fusion procedure involves the fusion of one or more vertebrae (vertebrae) with screws, bolts, and plates. This cookie is set by GDPR Cookie Consent plugin. I had a screw come loose after a spinal fusion and all I felt was more pain as time went on. Ohtori S, Inoue G, Orita S, Yamauchi K, Eguchi Y, Ochiai N, Kishida S, Kuniyoshi K, Aoki Y, Nakamura J, et al. It is a treatment for a variety of diseases and conditions of your spine. Some of the long-term side effects of spinal fusion and common problems after spinal fusion are mentioned below. Infection: Some patients experience catching infections after surgery. He said the CT scan, the MRI and the bone scan showed nothing except the loose screws at the L5 level. PubMed Why do screws come loose after spinal fusion? Now I know why! CAS Now they are going to extend the rods up further, does that sound right. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. If you think its happening you need to have an x-ray done to check. Terms and Conditions, If you know or suspect that something has gone wrong with your spinal hardware, youll want to contact the surgeon that performed your initial operation. Surgeons needed to be more cautious when assessing screw loosening merely according to radiological examination, and aware of that screws in fractured vertebrae or non-fusion surgery were vulnerable to loosening. How you prepare The screw, especially a larger diameter screw, is acting like a wedge so the board can actually be split apart around the screw. To do so . Correspondence to Normal spinal alignment preserved. Really need to get off these meds and try to have some sort of quality of life. https://doi.org/10.1186/s13018-018-1046-0, DOI: https://doi.org/10.1186/s13018-018-1046-0. J Bone Joint Surg Br. A recent article has potentially identified a novel hypothesis bacteria. Ensure stabilization at the surgical site. Getting an MRI Monday, then will find out what we can do. The doctor could actually trigger the pain by touching where the lower screws are in my back. *p=0.001, Mann-Whitney Test. This is done because the spine is unstable because of an injury, or because the spine needs to be fixed in place because of pain. Spinal hardware is used in a number of different procedures to help increase stability or facilitate healing after an injury. In the fractured vertebrae, the continuity of cortical and structure of trabecula were damaged, which might affect the stability of screw placed in it. These cookies track visitors across websites and collect information to provide customized ads. With a failed fusion, the patient's initial symptoms may return, or they may experience new problems. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. The indications for screw removal included the following: (1) pedicle screw fixation for thoracolumbar fracture without fusion and imaging confirmed solid fracture union, (2) patients required screw removal that presented persistent axial para-midline back pain to palpation or abnormal foreign body sensation due to pedicle fixation with imaging All values are given as the meanSD. To the best of our knowledge, no study has evaluated such risk factors according to the extraction torque in vivo. However, the actual fusion does not occur for at least the next 6-12 months, which is the second part. Excessive strain between the screw and bone interface is considered to be the primary cause for screw loosening [12, 22], which could be deteriorated when fusion is failure or the anterior support is inadequate. Spine. Rates vary in the literature as there is no . This cookie is set by GDPR Cookie Consent plugin. Heres what you should know about spine deformities that can develop during the adult years. Spine. This union can take up to a couple years to complete, and spinal hardware . Created for people with ongoing healthcare needs but benefits everyone. Okuyama K, Abe E, Suzuki T, Tamura Y, Chiba M, Sato K. Posterior lumbar interbody fusion: a retrospective study of complications after facet joint excision and pedicle screw fixation in 148 cases. Rollinghoff M, Schluter-Brust K, Groos D, Sobottke R, Michael JW, Eysel P, Delank KS. Glaser J, Stanley M, Sayre H, Woody J, Found E, Spratt K. A 10-year follow-up evaluation of lumbar spine fusion with pedicle screw fixation. The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. Later on, the screw was visible on xray pictures and my pain was just confirmation. Spinal fusion is generally safe. This website uses cookies to improve your experience while you navigate through the website. This is associated with pneumothorax, mediastinitis, sepsis, shock, and respiratory failure with an overall mortality of 16%. Spine deformities are a surprisingly common cause of adult back pain, and even a subtle change in your spine curvature can cause problems. Conventional lateral and anteroposterior radiographs were taken before and at 3 to 6months after primary surgery. Spinal fusion is a time-tested surgical approach to many types of chronic spine-related pain, especially in the neck and lower back. Google Scholar. Provided by the Springer Nature SharedIt content-sharing initiative. Never stopped smoking but was coming along good. Numbness and tingling sensation exacerbating on your back, legs, and neck It is kind of hard to know if the pain in your back is due to hardware failure or some other complications from your surgery. Like, the doctor has to pretty much blatantly screw up. Regardless, the nerve root can take a long time to heal from a fusion surgery, making the outcome difficult to predict. Both X-ray and CT had high specificity to detect screw loosening, but their sensitivities could be overestimated. OK so I overdid it and after months of pain and test had to undergo another fusion of the level above. If there is loosening around the screws, it could imply different things. Indications for L5 S1 fusion are debilitating pain and dysfunction arising from degenerative disc disease, slipped disc, fractures, recurrent herniation, sciatica, scoliosis, and spinal canal narrowing. We could not detect such a clear gap in our data. No pain meds. But I really can't stand the narcotics they give. But as with any surgery, spinal fusion carries some risks. Your doctor may also use screws, rods or plates to hold your vertebrae in . Your vertebrae are the bones that make up your spine (backbone). Okuyama K, Abe E, Suzuki T, Tamura Y, Chiba M, Sato K. Can insertional torque predict screw loosening and related failures? Skipping steps, not following normal protocol, ignoring you when you told them something that is a classic sign they did something wrong in your post op visit. Surgery for removal of hardware is scheduled for August 26, wish it were sooner, but at least at this point there appears to be hope. Bleeding or blood clots: Some patients might experience blood clots and even bleeding. Postsurgical Complications Surgeries always carry a risk for infection, which can vary by institution. In both cases, bilateral S1 pedicle screws were inserted outwardly using a free-hand technique, and on one side, screws induced severe pain by impinging on an L5 root. Spine. XW, JS, YC, KP, and JC performed the surgeries; XW, JS, and JW collected the data; JS, JW, JC, and HJ performed the data analysis; XW and JS wrote the paper; all authors read and approved the final submitted manuscript. Your surgeon will normally re-open your original incision. Pedicle screw loosening is a common complication after spine surgeries. However, symptom and pain reduction is common. When hardware is loose, it usually doesn't make a noise. The possible signs of a failed fusion include chronic back pain, reduced mobility, neuropathic pain, and radicular pain. Computed tomography after the selective rootgraphy of the injured nerve . 2001;1(6):4027. Sometimes a small ligament will snag as one moves, and then it pops back into place. I had a plate and 8 screws on c4,c5,c6,c7 13 months ago. If the screws are loose I will not remove them as it will give her back pain. The screws were carefully studied, using a process called sonication, which assessed if small amounts of subtle non-aggressive bacteria were present. Arch Orthop Trauma Surg. What Happens If My New Spinal Hardware Breaks Or Shifts? Anterior plate well applied. An apple a day may not keep the doctor away, but good nutrition just might help you heal and recover more quickly after spine surgery. a No significant difference was found between polyaxial and monoaxial screws. hardware removed after a spinal fusion - shared with permission. In our study, there was no significant difference between X-ray and CT scan regarding both sensitivity (p=0.863) and specificity (p=1.00). The cookie is used to store the user consent for the cookies in the category "Performance". Personal Stories. Cervical spine fusion can be performed routinely from the front of the neck or the back of the neck. A selected survey of ABS members. There was no linear correlation between extraction torque and patients height (p=0.848), weight (p=0.196), BMI (p=0.125), and time interval between the primary surgery and screw removal surgery (p=0.965). The standard history and physical examination have only limited utility for assessing the postoperative anatomy, and radiologists can play an important role in diagnosing complications and guiding postoperative care. 2013;22(Suppl 6):S8538. Loosening of the screws does not necessarily mean fusion will not eventually occur, or those symptoms are due to the loose screws. Meanwhile for the past years all was okaytill Just recently where I started seeing a sports medicine doctor, orthopaedic, physical therapy, and massage, but nothing has helped. By using Twostep Cluster, the distribution of extraction torque of pedicle screws showed two prominent peaks and one valley. Pain and swelling after spinal fusion surgery. statement and 3 Can you sue for failed back surgery syndrome? A typical case showing CT scan might be insensitive to detect screw loosening. 1998;23(12):13749. In a spinal fusion procedure, hardware is typically used to stabilize the spine while the bone graft fuses the vertebrae together. Herniated discs are a common cause of back and neck pain, with symptoms limiting activities and even interfering with getting a good nights sleep. I do not expect complete fusion at this point, but the scan gives a good idea if the fusion process is progressing. Answer (1 of 13): Yes, it can happen, especially in an area which is being constantly used. Thanks. If after 6-12 months a patient continues to have or experience new pain, more imaging may be pursued. senior resident) with sufficient practice made all the extraction torque recordings. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. Most spinal fusions use a bone graft to fuse or join two vertebrae. There were no clear symptoms pointing towards any loose screws. Department of Spinal Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China, Xiaoliang Wu,Jiawei Shi,Yongquan Cheng,Kaiwen Peng,Jianting Chen&Hui Jiang, Respiratory Department, Nanfang Hospital, Southern Medical University, Guangzhou, China, You can also search for this author in Typical CT image of metal artifact around screw tail. Christensen FB, Dalstra M, Sejling F, Overgaard S, Bunger C. Titanium-alloy enhances bone-pedicle screw fixation: mechanical and histomorphometrical results of titanium-alloy versus stainless steel. Do you know whythe screws keep coming loose. I am looking forward to getting rid of the hardware and hopefully getting off these meds and begin to have a little quality of life again. | Mehta Spine. This may include facet joint or sacroiliac joint rhizotomy, spinal fusion, or sacroiliac joint fusion. I just had another MRI today and I now have more problems. I had two back surgeries and left to travel for two yrs only to come back to Fla. to see my neurosurgeon. This picture shows metal artifact around screw tail in CT scan, which may confuse the interpretation of screw loosening. Surgical screws, rods or metal plates are used. a Anteroposterior X-ray showed radiolucent zone and double halo around the screw (black arrow) which indicate screw loosening. New mri and ct show nothing according to dr. 2. Spine. Comparison of teriparatide and bisphosphonate treatment to reduce pedicle screw loosening after lumbar spinal fusion surgery in postmenopausal women with osteoporosis from a bone quality perspective. New symptoms like pain in another place or new numbness and tingling or referred pain down the leg New weakness in the leg New loss of function like an inability to exercise without pain The Categories of Spinal Fusion Complications Years Later The problems fall into two main categories: ASD and muscular stabilization failure. The presence of wear debris [23] was reported to induce osteolysis leading to screw loosening. But when hardware breaks, it cant mend itself like a bone. Therefore, a broken screw won't move very much in your spine, so if it's not causing you issues now (you don't have any pain, so it sounds like it isn't), the screw isn't likely to be a problem later on. What can't you do after spinal fusion? A and B: Radiographs . If it comes out far enough it can be felt, and sometimes it comes through the skin. Possible complications include: Infection. Is it easy to get an internship at Microsoft? Our findings showed that X-ray had a sensitivity of 24% and a specificity of 98%, while CT scan had a sensitivity of 22% and a specificity of 95% regarding extraction torque as criterion of screw loosening. In this process, two or more vertebrae are fused together and healed into one solid bone. A number of complications can occur as a result of . This consequence is extremely uncommon. How to tell if a screw is coming loose? Patients might feel like they got better for a little while, but then started to get worse again. X-ray had a sensitivity of 24% and a specificity of 98%, while CT scan had a sensitivity of 22% and a specificity of 96%. 3c. 2023 MehtaSpine. Symptoms The main symptom is pain following back surgery. 2019, 2023 Rocky Mountain Brain & Spine Institute. Xiaoliang Wu and Jiawei Shi contributed equally to this work. L lumbar vertebrae, S sacrum, T thoracic vertebrae. Wu et al. Like any surgery, this procedure can also have long-term side effects. They have to show doctor error or malice in order to make a law suit. But opting out of some of these cookies may affect your browsing experience. Traditionally, it was assessed by radiological approaches, both X-ray and CT (computed tomography) scan, while reports using mechanical method to study screw loosening after spine surgery are rare. Thank you. Once they have a diagnosis, they can begin developing a treatment plan. Apparently this is common as the bones fuse either the screw goes deeper in or out - my case it is on the move outwards but he said 4 months is too early to have it removed. Anecdotally, I have wondered if some loose screws occurred due to persistent wobbling of the screw in the bone. Pedicle screws are used sometimes in a spinal fusion to add extra support and strength to the fusion while it heals. However, like any other metal it can fatigue and break (sort of like when one bends a paper clip repeatedly).