➢ The rate of wrong-level spine surgery appears to be low relative to other complications related to spine surgery.
➢ Up to 50% of neurosurgeons may perform wrong-level spine surgery at some point in their career.
➢ Wrong-level lumbar disc surgery typically occurs at a level cephalad to the one intended.
➢ There are multifactorial reasons for wrong-level surgery with which the surgeon should be familiar.
➢ Wrong-level spine surgery may occur despite adhering to the Universal Protocol.
In 1999 the Institute of Medicine published its landmark report, To Err is Human: Building a Safer Health System, in which it was estimated that between 44,000 and 98,000 preventable hospital deaths occur annually in the United States due to human error1. Subsequently, state-based and federal-based initiatives including the National Summit on Medical Errors and Patient Safety, the National Quality Forum, the Agency for Healthcare Research and Quality, and The Joint Commission were tasked with identifying ways to reduce medical errors and improve patient safety. Medical societies such as the American Academy of Orthopaedic Surgeons (AAOS) and the North American Spine Society have similarly made recommendations to improve patient care through the publication of procedural guidelines2,3.
Wrong-patient, wrong-side, or wrong-site surgery falls under The Joint Commission’s designation of a sentinel event, which is defined as “an unexpected occurrence involving death or serious physiological or psychological injury, or the risk thereof” to the patient4. One study found that 84% of wrong-site surgery malpractice claims led to patient indemnity versus 30% for other orthopaedic complications5. The Joint Commission, which collects data on sentinel events, has identified wrong-site, wrong-side, or wrong-patient surgery as one of the most frequently, annually reported sentinel events. In fact, it was the most commonly reported sentinel event6 (928 [13.3%] of the 6994 incidents reviewed) during the nine-year period from 2004 through 2012. Moreover, recent news reports have brought this problem into the public consciousness7-9.
The Centers for Medicare & Medicaid Services (CMS) list wrong-site surgery as a never event. First coined in 2001 at the National Quality Forum, this term refers to adverse events that occur in a hospital and that are ostensibly preventable and should never happen10. Twenty-nine “never events” have been identified by CMS in the following categories: surgical, care management, device or product, patient protection, environmental, radiographic, and criminal10. Since 2009, CMS has refused payment for never events such as surgery on the wrong-side, site, or patient, including wrong-level spine surgery.
In 1997, the AAOS produced a report on wrong-site surgery in which it was estimated that an orthopaedic surgeon has a 25% chance of performing wrong-site or wrong-patient surgery at some time during a thirty-five-year career11. Spine surgeries were at particularly high risk for wrong-site surgery, most commonly at a level cephalad to what was intended. Wrong-level surgery is a problem that is unique to spine surgery as compared with other orthopaedic procedures, because in addition to identifying the laterality of the procedure (i.e., right versus left side of spine), the surgeon must also identify the correct level. The purpose of this review is to discuss the incidence, causation, medicolegal repercussions, and strategies for avoidance of wrong-level spine surgery.
Discovering the true incidence of wrong-level spine surgery is likely not possible, as this would require a prospective study of multiple surgeons, over many years, who would be readily willing to disclose such information12,13. While wrong-level surgery is not an infrequent cause for a lawsuit, the individual spine surgeon appears to infrequently perform wrong-level surgery14-16.
In previously published case series of lumbar discectomies, the rate of wrong-level spine surgery has ranged from 0.14% to 2.12%. Roberts reported that, of 17,058 lumbar discectomies performed by six different surgeons over a period of nine years, twenty-four (0.14%) involved wrong-level spine surgery17. Williams identified three (0.57%) wrong-level spine surgeries in his series of 530 lumbar microdiscectomies18. Ruggieri et al. reported that seven (0.8%) wrong-level spine surgeries occurred among 872 lumbar discectomies over a ten-year period19, whereas Eie et al. described twenty (2.12%) wrong-level lumbar discectomy exposures in 943 patients who were available for follow-up over a thirty-five-year span20.
More recent literature has focused on surveying the personal experience of neurosurgeons with regard to wrong-level spine surgery. Groff et al.14 anonymously queried 1045 members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Section on Disorders of the Spine and Peripheral Nerves (Spine Section) via a web-based survey inquiring about the frequency of wrong-level spine surgery in a single-level lumbar decompression. They received 569 replies (a response rate of 54%), with nearly 47% of respondents admitting to having performed wrong-level surgery at least once in their career and with 18% of those respondents reporting that they had been sued because of it. Interestingly, a far smaller percentage (11%) of respondents admitted to performing wrong-side spine surgery at least once. Of the surgeons who admitted to performing wrong-level or wrong-side surgery, 68% noticed the error and corrected it intraoperatively, 5% noticed the error immediately after the operation, and 27% realized the error more than twenty-four hours after the surgery.
Similarly, Mody et al.15 surveyed 3505 members of the AANS regarding wrong-level spine surgery and received a response from 415 (12%). Fifty percent of respondents admitted to performing wrong-level spine surgery at least once in their career, whereas 15% acknowledged exposing the wrong level but performing surgery on the correct level after intraoperative radiographic confirmation. Approximately half of the wrong-level spine surgeries were detected intraoperatively and were subsequently corrected, 19% were discovered immediately after the operation, and 31% were discovered in the follow-up period. There were 418 total wrong-level spine surgeries performed, of which seventy-three (17%) led to legal action or remuneration to the patient. The authors calculated the prevalence of wrong-level spine surgery to be 0.03% (418 of 1,300,000). Seventy one percent of the wrong-level surgeries were lumbar, 21% were cervical, and 8% were thoracic.
Jhawar et al.16 surveyed 138 members of the Canadian Neurosurgical Society and the Royal College of Physicians, 68% of whom completed a questionnaire that asked members whether they had performed wrong-level lumbar or cervical discectomies or wrong-sided craniotomies within the previous year. The authors calculated a rate of wrong-level lumbar discectomies as 12.8 occurrences per 10,000 operations and a rate of wrong-level cervical discectomies as 7.6 occurrences per 10,000 operations. Thirty-two percent of responding surgeons admitted to removal of a disc at the wrong level in the lumbar spine and 16% admitted to wrong level removal of a disc in the cervical spine at some time in their career. A lawsuit was either pending or expected in 10% of the wrong-level surgeries. The authors did not comment as to whether the mistakes were noticed intraoperatively and corrected.
Wrong-level spine procedures accounted for twenty-six (43%) of sixty-one classifiable wrong-site surgeries reported to the American Board of Orthopaedic Surgery (ABOS) by 9255 ABOS Part-II candidates for certification, recertification, or maintenance of certification over a twelve-year period with a total case load of 1,291,396 procedures21. A single-level lumbar laminotomy was the most commonly reported wrong-site procedure, accounting for fourteen of sixty-one (23%) of all wrong-site spine surgeries. Thirty-one (3%) of the 897 candidate member spine surgeons performed wrong-level surgery, at a rate of 0.041%, while only 0.66% of hand surgeons and 0.55% of sports and general orthopaedic surgeons performed wrong-site surgery, at a rate of 0.004% and 0.005%, respectively.
Causes/Factors of Wrong-Level Spine Surgery
Why wrong-level spine surgery occurs is multifactorial and complex, with few data to quantify rates of specific causes (Table I). The Joint Commission has cited leadership and poor or improper communication in their root cause analysis (between patient and surgeon, and surgeon and team) as the primary reasons for wrong-site surgery between 2004 and 201222. Other authors have identified unusual anatomy, emergent surgery, fatigue, failure to obtain proper imaging, surgical levels above L5-S1, and lack of surgeon experience as risk factors12,13,21,23-25. In a study of 100 consecutive patients undergoing lumbar discectomy, Ammerman et al. found a significant (p = 0.004) correlation to wrong-level exposure if the surgery was performed cephalad to L5-S1 and if the patient age was older than fifty-five years (p = 0.04)24.
Given the relatively uniform appearance of the vertebrae in their respective region and the multiple levels over which they span, localization of a particular vertebra or intervertebral disc space can be confusing and thus problematic. Other important issues that make intraoperative localization radiographs difficult to interpret include patient factors such as obesity, osteoporosis, scoliosis, and previous surgery. Non-patient factors include the experience of the surgeon and radiology technician, status of the radiographic equipment, and image quality.
In the paper by Hsiang23, the most common causes of wrong-level spine surgery were: (1) failure to obtain or difficulty obtaining intraoperative radiographic images, (2) anatomic abnormalities, (3) large or obese body habitus, and (4) challenging areas of the spine to image. In their series of 11,173 spine procedures (rate of 0.13% wrong-level spine surgery), Vachhani and Klopfenstein26 reported that eight (57%) of fourteen wrong-level spine surgeries occurred despite obtaining intraoperative radiographs, and they cited obesity, transitional anatomy, and poor imaging as the causes.
Anatomic factors play a critical role in the causation of wrong-level spine surgery. Lumbosacral transitional anatomy (i.e., segmentation anomalies) can be described as sacralization of the L5 segment or lumbarization of the S1 segment, with an estimated prevalence as high as 35.6%27. Depending on convention, the interpreting radiologist (of the preoperative magnetic resonance image [MRI]) may label a so-called unfused lower lumbar segment as L5-S1 or S1-S2, which may be in disagreement with the surgeon’s interpretation and thereby inject confusion into identification of the proper level (Fig. 1). If there are four or six lumbar segments, the nomenclature of the vertebral bodies will vary depending on whether they were counted beginning from the most cephalad or most caudal vertebra (Fig. 2). The first attempt at intraoperative identification of disc spaces during lumbar microdiscectomy was successful in only two (50%) of four patients with transitional anatomy versus thirty-nine (87%) of forty-five patients with normal anatomy24. Moreover, nonuniform terms used to describe segmentation anomalies such as vestigial, transitional, partially fused, lumbralized, and sacralized add to the perplexity.
The thoracic spine can be a particularly vexing anatomic area to image intraoperatively for several reasons, including the uniform appearance of the vertebrae or intervertebral disc spaces, especially in the midthoracic spine; the presence of osteoporosis or scoliosis; the variable number of rib-bearing vertebrae; the presence of anomalous ribs; the presence of scapulohumeral shadows at the cervicothoracic junction; and the distance from identifiable landmarks. Commonly, in order to identify the surgical level, the surgeon will count in a caudal direction from the C2 vertebra under fluoroscopy if the target level is the middle to upper thoracic spine or he or she will count in a cephalad direction from the sacrum if the desired level is in the middle to lower thoracic spine. Noncontiguous imaging provided by this patulous technique can make localization difficult and may be further confounded by the aforementioned anatomic anomalies.
In the cervical spine, a Klippel-Feil (congenital fusion) anomaly may be present. In the particular instance of a C2-C3 congenital fusion, the C3 body may be mistaken for an elongated C2 body; thus, the surgeon may intend to perform surgery on C3-C4 but may end up operating on C4-C5 (Fig. 3). This example highlights the importance of making clinical radiographs and comparing them with intraoperative radiographs so that the appropriate level may be identified.
Quality intraoperative radiographs or fluoroscopic images are critical in identifying the desired surgical level. The reasons that obtaining quality images may be difficult can be divided into two categories: intrinsic patient factors, and image acquisition problems. Factors that are intrinsic to the patient include obesity, osteoporosis, scoliosis, and previous surgery. These intrinsic factors have the potential to obscure the anatomy and lead to radiographic misinterpretation of the intended surgical level21. Problems related to image acquisition may include an inexperienced or poorly trained radiographic technologist who may simply be unable to adequately image the desired level. In addition, older or improperly functioning equipment may also hinder the ability of the surgeon to identify the surgical target.
Physician experience has been shown to make a difference in the complication rate associated with lumbar discectomy. Wiese et al. reported a significant difference in the rates of wrong-level exposure between surgeons who had performed between fifty and 100 lumbar microscopic discectomies before the beginning of the study and surgeons who had performed more than 500 lumbar microscopic discectomies before the beginning of the study (rate of wrong-level exposure, 3.3% compared with 1.3%, respectively; p = 0.05)25. These issues highlight not only the importance of making good-quality preoperative radiographs in the office for comparison with those made in the operating room, but also the need for the surgeon to anticipate and have a strategy to deal with these at-risk situations.
Of all orthopaedic procedures, lumbar spine surgeries are the most commonly litigated cases in medical malpractice while generating the highest indemnity payments and defense costs28. Neurosurgeons and orthopaedic surgeons are at a 20% and 14% annual risk, respectively, for being named in a malpractice claim, and they are at a 3% to 4% annual risk of making an indemnity payment. Furthermore, practitioners of these subspecialties are at an 80% risk for being named in a malpractice claim by the time they are forty-five years of age, and they are at a 98% risk by the time they are sixty-five years of age29.
Between 10% and 18% of wrong-level spine surgery cases wind up in litigation14-16, the repercussions of which can be psychologically and physically daunting for both patient and surgeon, particularly in cases with protracted legal proceedings30-32. It is unfortunate that, during physician training, little time is devoted to learning techniques of avoiding malpractice litigation, and even less time is devoted to the learning of physician-patient communication skills that may be protective from lawsuits33.
Goodkin and Laska34 reviewed sixty-nine cases of wrong-level disc surgery collected from legal journals over a fifteen-year period, sixty-eight of which were settled or had a jury verdict rendered (only 42% of the time in favor of the defense). Fifty-two of the cases involved the lumbar spine, twenty-five of which were intended to be at L4-L5; instead, nineteen were performed at one or two levels cephalad to L4-L5 and only five at a level caudad to L4-L5. The inclination of mistakenly performing surgery at a level cephalad to the intended level remained consistent for discectomies intended for L3-L4 and L2-L3. As the reason for this common error, the authors cite McCullough’s laminar trap, which refers to the inferior edge of the superior lamina progressively overlying more of the disc space with each ascending level of the lumbar spine (Fig. 4)35. If, during the operation, the surgeon localizes the intended disc slightly cephalad, then he or she may be directed to the lamina just cephalad of the one intended, inadvertently exposing the adjacent disc space just cephalad of the one intended to be exposed. Of the seventeen cases that did not involve the lumbar spine, three of four wrong-level cervical cases occurred below the intended level, whereas no clear trend was noted in the thoracic spine cases. Many plaintiffs claimed persistent or worsening back and/or leg pain postoperatively as reason for litigation. Remuneration ranging from $62,000 to $1,500,000 was awarded to the plaintiff in fifty-five (81%) of sixty-eight of the cases.
Fager reviewed 275 malpractice cases against neurosurgeons, of which 118 (43%) were spine-related cases. Seventy-three (62%) of the spine-related cases involved the lumbar spine36. Wrong-level surgery was the third most common reason for litigation involving the lumbar spine, despite the surgeon obtaining localizing preoperative radiographs in all of the cases. Furthermore, if a postoperative neurologic deficit occurred, it tended to lead to settlement, citing Studdert et al.37, that the magnitude of compensation is related to the severity of the plaintiff’s disability rather than the physician’s negligence. Fager compared the results of his study to the results of a similar one that he did twenty years prior, and concluded that the two studies had strikingly similar findings, with skewed, plaintiff-favoring outcomes despite a twenty-year interval for potential tort reform38.
There is no consensus on the definition of wrong-level spine surgery. Some authors12,15 define it merely as the act of wrong-level exposure, while others define it as performing the procedure on a level other than the one intended. In their paper, Goodkin and Laska opined, as have others17,21, that wrong-level disc-space surgery or exposure, if recognized and corrected at the time of surgery, is an intraoperative complication that is not below the standard of care34. Two retrospective lumbar discectomy case series failed to discover any new adverse findings during follow-up of patients who inadvertently had the wrong disc space explored before the intended disc was removed during the same surgery18,39. It may be advisable in the informed consent to mention the possibility for wrong-level spine surgery, specifically with regard to those patients who have potential risk factors (i.e., obesity or transitional anatomy)34,40.
The AAOS, the North American Spine Society, and The Joint Commission, through their respective “Sign Your Site”; Sign, Mark, & X-ray (SMaX); and Universal Protocol programs2,3,41, have each made recommendations in an effort to eliminate wrong-site surgery. These protocols suggest involving the patient and surgical team in the identification of the surgical site and procedure. Since 2004, hospitals accredited by The Joint Commission, ambulatory surgery centers, and office-based surgery centers are required to preoperatively verify the patient and procedure, and to mark the surgical site in the preoperative holding area. This is followed by a so-called time-out in the operating room prior to the beginning of every surgery, with the timeout consisting of the participants agreeing upon (at the minimum) correct patient identity, procedure, and site. However, many institutions include additional elements, such as consent confirmation, appropriate imaging, or implant availability.
Despite the implementation of such practices, the reported number of wrong-site, wrong-side, or wrong-patient sentinel events continues to increase. In 2004, the year the Universal Protocol was introduced, there were fifty wrong-side, wrong-site, or wrong-patient events reported to The Joint Commission. By 2011, that number tripled to 15242. The reason for this increase is unclear, but the increase could reflect (1) decreased anxiety about reporting such events since they are anonymous, (2) state-enforced mandatory reporting, or (3) possibly an actual increase in the number of wrong-site surgeries. Because most of these events are voluntarily reported, their numbers are likely underrepresented, making an accurate assessment of the incidence of wrong-level spine surgery from these data impossible.
Several authors have reported a lack of faith on the part of surgeons with regard to the ability of the Universal Protocol or other programs to eliminate wrong-level spine surgery, intimating that there are influences that lead to wrong-level spine surgery that are out of the control of the surgical team14,15. Kwaan et al., in their review of nearly 3,000,000 procedures, found a rate of 1:113,000 wrong-site non-spine-related surgeries, and they further reported that only two-thirds of cases could have been prevented by application of the Universal Protocol43. In their literature review, Devine et al. concluded that insufficient evidence exists to show that wrong-site protocols, such as the Universal Protocol, prevent wrong-site surgery12. Similarly, Longo et al. concluded that insufficient evidence exists to show that such protocols mitigate wrong-level spine surgery13. Furthermore, James et al., using information collected by the ABOS from its candidate members over several years, showed no difference in the frequency of wrong-site surgery before and after the implementation of the Universal Protocol. However, they did note that when spine procedures were excluded from the data, the rate of wrong-site surgery dropped 35% (p = 0.303) after the implementation of the Universal Protocol. This suggests that the Universal Protocol may decrease the occurrence of wrong-site surgery in non-spine procedures but may not prevent wrong-level spine surgery21. A report from the Quality and Patient Safety Division of the Massachusetts Board of Registration in Medicine discussed five wrong-level spine surgeries that occurred in a single hospital in that state over a two-year period despite the fact that the Universal Protocol was followed in each case44. More recently, however, Vachhani and Klopfenstein found a significant reduction (p < 0.001) in the number of wrong-level surgeries at their institution after implementation of the Universal Protocol26.
Perioperative Techniques to Prevent WLSS
Several intraoperative techniques (Table II) to prevent wrong-level spine surgery have been advocated by various authors, although all of the studies provided either Level-IV or Level-V evidence. In thoracic spine surgery, the use of computed tomography (CT) or fluoroscopy to aid in the preoperative percutaneous placement of radiopaque markers in the pedicle of interest or to insert polymethylmethacrylate cement into a vertebral body with use of a standard vertebroplasty technique by a radiologist may be beneficial in assisting accurate intraoperative identification of the proper disc space23,45-47. Upadhyaya et al. reported that there were no wrong-level spine surgeries with use of preoperative percutaneous fiducial screw placement for level localization in thoracic spine surgery in twenty-six patients, concluding that this practice was both safe and associated with reduced fluoroscopy time46. Irace and Corona advocated a technique of using a wire placed intraoperatively into the cranial spinous process to help prevent wrong-level spine surgery48. In their series of 818 lumbar discectomies, only one unintended disc space was explored with use of this technique. The use of intraoperative CT or fluoroscopic navigation has been proposed as a means to accurately target the intended surgical level49,50.
Once an intraoperative confirmatory radiograph is performed, a permanent marker should be placed into a fixed anatomic point (e.g., a suture or a needle placed into the spinous process) or a mark should be made on the skin at the level of the radiopaque marker, since wrong-level spine surgery can occur once the radiopaque marker has been removed. Furthermore, if a discectomy is being performed, obtaining another radiographic image showing the radiopaque marker within the disc space may be prudent51,52. Asopa et al. reported no wrong-level spine surgeries in their series of sixty-four lumbar microdiscectomies with use of localization, confirmatory, and intradiscal radiographs (Fig. 5)52. The surgeon should also recognize that if the expected pathology that has been noted on the MRI or CT myelogram is not demonstrated at the level that has been exposed for operation, then he or she should reevaluate and/or reimage the surgical level in question34,51.
Often, anatomic spinal landmarks such as acute or chronic fractures, osteophytes, vertebral end plate anomalies, varying intervertebral disc heights, or spondylolisthesis can be used by the surgeon to localize the correct surgical level. These landmarks, along with the findings from the clinical examination and preoperative imaging, may be more reliable than counting vertebrae alone in challenging settings, such as when operating on obese patients or patients who have transitional anatomy51,53. If there is uncertainty as to the proper level, intraoperative consultation with a radiologist may be warranted23,51.
Despite the ubiquitous implementation of the Universal Protocol and use of the North American Spine Society and AAOS surgical site guidelines, wrong-level spine surgery still occurs, while mixed evidence exists that specifically shows that implementation of the Universal Protocol diminishes the frequency of wrong-level spine surgery26,36,43,44,54. This implies that surgeons should not be held to a standard of infallibility if wrong-level spine surgery occurs in a setting in which reasonable, appropriate actions were taken to identify the intended surgical level of the spine. Wrong-level spine surgery is a recognized problem that is associated with multifactorial and often very challenging issues. While wrong-level spine surgery may never be completely eradicated, an awareness of the potential for wrong-level spine surgery, associated risk factors, and strategies for prevention is critical to reducing the likelihood of its occurrence. Three-dimensional intraoperative imaging may help surgeons avoid performing wrong-level spine surgery in challenging patients. We recommend close adherence to the Universal Protocol when taking patients to surgery and urge surgeons to make their best reasonable efforts to accurately identify the operative level with the aid of the previously described techniques.
Source of Funding: No external source of funding was used for this study.
Investigation performed at OrthoCarolina, Charlotte, North Carolina
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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