Abstract
Study Design
Single center, retrospective cohort study.
Objectives
Little is known about the surgical outcomes and quality of life in patients with C2-sacrum posterior spinal fusion (PSF). Though it is thought to be a “final” construct, it remains unknown how patients fare postoperatively. We sought to evaluate the surgical outcomes and quality of life of patients after C2-sacrum PSF.
Methods
Consecutive patients undergoing C2-Sacrum PSF from 2015-2020 by 4 surgeons at a single institution were included. The study time period for each patient began after their index operation that led to the C2-sacrum fusion. Dates of surgery, complications, reoperations, patient reported outcomes (PROs) including EuroQol 5 Dimensions (EQ-5D), Oswestry Disability Index (ODI), Scoliosis Research Society (SRS) questionnaires, and activities of daily living (ADL) questions were collected and analyzed. Descriptive statistics, paired t-tests, student t-tests, and linear regression were used.
Results
Of the 23 patients who underwent C2-sacrum PSF, 6 patients (26%) required a total of 10 reoperations after a mean of 1.5 years (range 0-4 years) after C2-sacrum PSF. Five reoperations were for mechanical failure; 3 for wound complications/infection; and 2 for instrumentation and spinous process prominence. PROs were collected on 18 patients with mean follow-up of 2.4 years (range .5-4.5) after their C2-sacrum PSF. At 6-months, both SRS-22 and ODI scores improved significantly after C2-sacrum PSF (SRS: 57.5 to 76.3, P = .0014; ODI: 47.0 to 31.7, P = .013). Similarly, at a mean 2.4 years postoperatively, mean ODI improved significantly (47.0 to 30.4, P = .0032). Six patients (33%) had minimal symptoms (ODI <20). The median postoperative EQ-5D score was .74 (range .19 to 1.0), which compares favorably to patients with hip/knee osteoarthritis (EQ-5D .63) and diabetes mellitus (DM) (EQ-5D .69) and hypertension (HTN). In terms of activities of daily living (ADL), 10 patients (56%) exercised regularly—a mean 4.5 days/week. 11 (61%) could do light aerobic activity (e.g. stationary bike). 10 (55%) were able to play with children/grandchildren as desired. Eight patients (44%) hiked, and 2 (11%) drove independently. 11 (61%) could tolerate short air-travel comfortably. Of the 17 patients who could toilet and perform basic hygiene preoperatively, 16 (94%) were able to do so postoperatively.
Conclusion
Though C2-sacrum PSF is thought to be a “final” construct, approximately 1 in 4 patients require subsequent operations. However, C2-sacrum PSF patients had a significant improvement in SRS and ODI scores by 6 months postop. Over 60% of patients were regularly performing light aerobic activity 2 years after their C2-sacrum PSF. EQ-5D suggests that this population fares better than those with degenerative hip/knee arthritis and similarly to those with common chronic conditions like DM and HTN.
Keywords
Introduction
Patients with adult spinal deformity (ASD) may require extensive instrumented fusions from C2 to sacrum in cases of cervical degenerative disorders and postoperative junctional failures.1,2 With all but 2 spinal motion segments fused, patients with a C2-sacrum posterior spinal fusion (PSF) experience drastic changes in function. Few studies have examined the postoperative courses of patients who required cervical-pelvic fusions, and patient reported outcomes (PROs) have been largely unreported in this population.3-5 One particular study assessing upper-cervical fusions to the sacrum reported reoperation in over half of patients; however, significant improvement was seen in Scoliosis Research Society-22r questionnaire (SRS-22r). 2
In comparison to robust quality of life data in patients undergoing spinal degenerative surgery, upper thoracic to sacrum deformity correction, and even three-column osteotomies, long term outcomes and quality of life metrics in patients with C2-sacrum PSF are sparse. Understanding quality of life measured through PROs, such as ODI, SRS, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), EuroQol-5 Dimensions questionnaire (EQ-5D), and visual analog scale (VAS) scores, helps surgeons and patients better understand postoperative functioning.6-12 One prior study has even directly compared the health impact of adult cervical spine deformity to that of chronic disease states such as blindness and emphysema, using EQ-5D scores. 13
An in-depth understanding of the quality of life of patients living with C2-sacrum PSF – what activities they can and cannot do – is currently lacking. Following this extensive fusion, it is unknown if patients require future surgery, can partake in hobbies, or have the capacity for common activities of daily living (ADLs). Seeking to address this deficiency, we sought to evaluate the surgical outcomes and quality of life in patients after C2-sacrum PSF.
Methods
Study Design and Patient Population
A single-center, multi-surgeon, retrospective cohort study of patients undergoing C2-sacrum fusion was performed. The study period was 6 years from 2015-2020. Institutional Review Board (IRB) approval was obtained to examine these data using a validated, standardized database. All patients, both pediatric and adult, who had undergone C2-sacrum PSF during the study period and who had full-body radiographs pre and postoperatively were included. Patients who had incomplete preoperative and postoperative SRS, ODI, and EQ-5D scores, or incomplete preoperative and postoperative x-rays, were excluded in the analysis of those metrics. Informed consent was obtained from patients in collecting the data for this research.
Data Collection
Demographic and comorbidity data included age, sex, comorbidities, connective tissue disease, neurologic pathology. Smoking status was also determined at time of C2-sacrum PSF. Operative data included total operative time (minutes), time to reoperation, indications for reoperation, and any subsequent complications following reoperation. All demographic and perioperative data was collected through retrospective review of the electronic medical record (EMR).
Outcome Measures
Outcomes included surgical outcomes and PRO measures. Surgical outcomes included reoperation and indication for any reoperation. A reoperation was defined as any unplanned return to OR for spine surgery after the C2-sacrum PSF. Reasons for reoperation were surgical site infection or mechanical failure, which included pseudarthrosis, rod fracture, proximal/distal junctional pathology, or implant failure, as defined by previous studies. 14 The number of reoperations and details of management during each were noted.
Patient reported outcome measures collected preoperatively and postoperatively included SRS and ODI scores at 6-months, and in select patients longer follow-up was utilized. EQ-5D, as well as targeted questions regarding ADLs, hobbies, and toileting, were only collected at a mean 2.4 years postoperatively to understand the current quality of life in patients living with C2-sacrum PSF.
Statistical Analysis
Descriptive statistics were performed to summarize patient demographics, comorbidities, presenting signs/symptoms, and operative data. Categorical data were presented as frequencies and percentages, whereas continuous data were presented with mean and standard deviations (SD). Paired t-tests were used to compare PROs at different times in a patient’s perioperative course. Student t-tests were used to compare differences in scores between different groups of patients. Additionally, linear regression was utilized to assess relationships between variables such as EQ-5D and time since C2-sacrum PSF.
Results
Patient Sample
A total of 23 patients who had undergone C2-sacrum PSF were reviewed. At the time of C2-sacrum PSF, mean age was 53. Thirteen patients (57%) were male. Of those requiring C2-S PSF as a revision (21 patients), 17 patients required it to address kyphosis. Two patients underwent C2-sacrum PSF as their index procedure (Figure 1). One patient was revised to C2-sacrum PSF for myelopathy (Table 1). Case: Anteroposterior and lateral radiographs of a 67-year-old man who required C2-sacrum PSF as his index procedure for pathologic compression fractures. (a) Preoperative radiographs at presentation with 124° of thoracic kyphosis (TK). (b) Preoperative CT scan. (c) Radiographs after halo traction (d) Radiographs after C2-sacrum PSF, with 67° of TK. Patient Demographics Patient Demographics and Indications for C2-sacrum PSF. MS, Marfan syndrome; BS, brown sequard syndrome; LD, Loeys Deitz, LE, Ehlers Danlos; KF, Klippel Feil; CP, Cerebral Palsy; PD, Parkinson’s disease; Opr, osteoporosis; Opn, osteopenia. aPreviously smoked but quit prior to first spine surgery.
Reoperations Following C2-sacrum PSF
Complications and Corresponding Management Data for Patients Requiring Reoperation After C2-Sacrum PSF.
Four patients experienced 5 mechanical failures of instrumentation. One patient, a 72-year-old male, experienced pullout of screws bilaterally at C2-C4 after a series of falls 10 months postoperatively. Of note, he had suffered an upper thoracic fracture and proximal junctional kyphosis (PJK), which had required C2-sacrum PSF. Two reoperations were required to manage this: an ACDF was performed initially, followed by revision posterior instrumentation and fusion with extension to C1. Two patients dealt with rod fractures at the thoracolumbar spine: a 68-year-old female experienced bilateral iliac screw connector and T12 rod fractures 11 months postoperatively and was found to have pseudarthrosis and kyphotic posturing with +10 cm SVA, requiring revision T4-sacrum PSF. The other patient, a 64-year-old female had bilateral T12-L2 rod fracture with progressive coronal/sagittal malalignment 4 years postoperatively, requiring revision T9-sacrum PSF (Figure 2). The remaining patient, a 72-year-old male, experienced right-sided L2/3 and S1 screw fractures with pseudarthrosis at 1.6 years postoperatively, requiring revision T12-sacrum PSF and a TLIF at L4/5. Importantly, 75% of these patients with a mechanical failure after C2-sacrum PSF had either osteoporosis or osteopenia. Case: A 64-year-old woman presented after prior instrumentation and fusion at an outside institution, which was complicated by PJK (a). She required C2-sacrum PSF (b) and did well until 4 years postoperatively when she presented with pain and forward-pitched posture. Her radiographs revealed broken rods (c). She required revision instrumentation and fusion from T9 to sacrum (d).
Outside of mechanical complications, prominent instrumentation and wound infections were seen. One patient, a 50-year-old female, complained of prominent instrumentation postoperatively, requiring reoperation 1 year after C2-sacrum PSF. Instrumentation (both rods and pedicle screws) from C2-T1 were removed during the first reoperation and replaced, minimizing prominence. Six months later, though the hardware was not prominent, this patient experienced prominence of her C6 and C7 spinous processes, which required a second reoperation for spinous process resection. Notably, this patient had Loeys-Dietz, a connective tissue disorder associated with cutaneous anomalies. Additionally, this patient was 1 of 2 smokers in our cohort.
The sixth patient required reoperation after C2-sacrum PSF for postoperative hematoma and surgical site infection. The 66-year-old female had 5 prior procedures before C2-sacrum PSF; most recently she had undergone a T3-pelvis PSF to address PJK from a prior procedure, which was subsequently complicated by myelopathy, necessitating a decompression and extension to C2. This procedure was complicated by hematoma formation, which required 3 additional procedures. Initially she underwent irrigation and debridement (I&D) 2 weeks after C2-sacrum PSF, followed by repeat I&D, antibiotic bead placement, and application of a wound vac 3 weeks later. A third return to the OR 1 week later concluded her management with a repeat I&D, wound closure with plastic surgery, and application of an incisional wound vac.
Patient Reported Outcomes
PROs Among Patients with at Least 2 Years Follow-Up.
SRS and ODI scores over time among patients with C2-sacrum PSF.
Distribution of EQ-5D scores after C2-sacrum PSF.
Postoperative EQ-5D Scores in C2-sacrum PSF vs Chronic Health Conditions.
Activities of Daily Living
Patient Ability to Participate in Hobbies and ADLs Following C2-Sacrum PSF.
Discussion
After a C2-sacrum PSF, 26% of patients required reoperation, most commonly for mechanical failure. Despite the need for reoperation in a quarter of the sample, the quality of life was not significantly different from those who did not require reoperation after C2-sacrum PSF. Moreover, over half of the patients in this sample report being able to regularly exercise and many of the patients remain able to participate in outdoor activities and travel. Quality of life in patients with C2-sacrum PSF were better or similar to other commonly seen chronic medical conditions such as diabetes and hypertension, indicating that patients can maintain a high quality of life with a C2-sacrum PSF.
Surgical Outcomes
Mechanical failures after long-construct fusions are well-known and common complications, including rod fractures, pseudarthrosis, and implant failure. Akazawa et al. reviewed patients with an average of 10 levels fused and found that 5% of patients experienced rod fracture, 17 which was comparable to the 2 patients (8.7%) in our sample who experienced rod fractures. The authors also suggested that this complication may occur more often in patients with iliac screws and in patients with small-diameter rods. Pseudarthrosis is another common mechanical complication and is often seen at approximately 1 year postoperatively most commonly at the thoracolumbar and lumbosacral junctions, with sagittal rod contours >60°. 18 Indeed, 1 patient in our sample had pseudarthrosis and rod fracture at the thoracolumbar junction at approximately 4 years after C2-sacrum PSF; the other, at the lumbosacral junction at 1 year after C2-sacrum PSF. Thus, attention to the thoracolumbar and lumbosacral transitional zones is crucial to promote bony fusion. It is routine at our center to use BMP and reinforce these areas with multiple rods. Iyer et al note a higher rate of complications in their cohort of patients undergoing fusion from the cervical spine to the pelvis. Their population did differ from ours in that the mean age of our cohort was nearly 15 years younger and we focused exclusively on those whose constructs extended up to C2, whereas their cohort encompassed other cervical spine levels as the UIV, potentially allowing for more complications like PJK.
While only 2 patients of the 23 in this sample were smokers, smoking may have contributed to postoperative complications. One of these patients had prominent spinal instrumentation and spinous processes requiring 2 reoperations. Nicotine disrupts the epidermal barrier and reduces collagen synthesis, 19 thereby weaking the epidermis, which likely contributed to the wound complications in this patient. 20 In addition to smoking, this patient had Loeys Dietz syndrome, which presents with translucent skin and easy bruising, 21 heightening the risk for symptomatic instrumentation prominence. Smoking cessation, even as late as 4 weeks prior to surgery, 22 can reduce the risk of complications associated with surgery. Similarly, osteoporosis likely contributed to postoperative complications seen in our patient sample. Three of 4 patients (75%) with mechanical complications had either osteoporosis or osteopenia. Biomechanical studies have assessed pull-out strength of screws and have found correlations with insertion depth and bone density: osteoporotic bone has significantly less pedicle screw pull out strength compared to normal bone, likely contributing in part to the mechanical failures, as in this sample’s patient who had multilevel cervical spine screw pullout after a fall. 23 The perioperative management of patients with decreased bone mineral density is critical: consultation with an endocrinologist or primary care physician comfortable managing it may be beneficial to patients as many patients with osteoporosis are undermanaged prior to their surgeries. Surgical techniques may also be modified in the osteoporotic patient. PMMA cement may be used to prefill a trajectory prior to placing a solid pedicle screw, which can increase pullout strength substantially. 24 Additional instrumentation including sublaminar wires or laminar hooks may be used to increase the strength of instrumentation during a posterior approach to the spine. 25 Therefore, a multidisciplinary approach involving both primary care physicians as well as spine surgeons is critical in the management of osteoporotic patients who require long-construct PSF.
Patient-Reported Outcomes
Patients living with C2-Sacrum PSF had a high quality of life similarly to those with other commonly seen medical conditions. Many were able to exercise, travel, and participate in family activities. The EQ-5D questionnaire has been used previously to quantify PROs for patients undergoing orthopaedic surgery. 26 While there did not appear to be a significant difference in EQ-5D scores between those who underwent reoperation after C2-sacrum PSF and those who did not, this study’s small sample size may have resulted in inadequate power to detect a significant difference that may exist in the population. Interestingly, the median EQ-5D was .74, which compared favorably to patients with hip/knee osteoarthritis (EQ-5D .63), diabetes (.69) and hypertension (.73) 15 (Figure 5). This may indicate that patients adapt well to daily life after having C2-sacrum PSF. This is consistent with prior findings that many factors, especially social determinants of health, can affect postoperative outcomes, including the risk of pseudarthrosis and the decision to pursue revision surgery. 27
Limitations
The small sample size is the key limiting factor in this study. As there were only 6 subjects who required reoperation, it is challenging to generalize observations in any individual patient, whether it be about timing of C2-sacrum PSF failure or HRQoL measures. Additionally, the patients in this study were observed at a single institution, which may affect the generalizability of our results. HRQoL metrics were not uniformly obtained in all patients, which made it challenging to compare self-reported outcomes of patients. Additionally, while EQ-5D scores were obtained during our phone survey, we did not have the EQ-5D scores recorded for patients preoperatively, making it impossible to compare EQ-5D preoperatively and postoperatively. Furthermore, the EQ-5D scores were consecutively recorded at 1 time point, thus creating discrepancies in the timing of scores relative to C2-sacrum PSF, making it difficult to compare scores for patients at specific times relative to their C2-sacrum PSF procedure.
Future Directions
Future studies will require larger samples of patients receiving C2-sacrum PSF with control groups. Control groups will better identify risk factors for complications such as prominent instrumentation or mechanical failure observed in this cohort. Moreover, additional surgeons from multiple centers will increase the generalizability of this study. The patients who were reviewed experienced complications at an average of 1.5 years after C2-sacrum PSF. Additional complications may only manifest later; therefore, further longitudinal study of these patients may alert us to complications occurring later in clinical course. Future studies will need to measure HRQoL metrics at regular time intervals following C2-sacrum PSF, enabling more accurate postoperative comparisons between patients.
Conclusion
In a sample of 23 patients with C2-sacrum PSF, a relatively high quality of life was seen with most patients able to complete normal ADLs, partake in hobbies, exercise, travel, and participate in family activities. That said, approximately a quarter of patients undergoing C2-sacrum PSF required reoperation, most commonly due to mechanical failure. Nevertheless, patients in this population fared well after C2-sacrum PSF with improvements in quality of life. Those who required reoperation did not have significantly poorer scores by these metrics than patients who did not require reoperation. These data represent one of the largest samples of patients with C2-sacrum PSF and hopefully leads to further multi-institutional studies.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
IRB Number
AAAT2038
