Cotrel-dubousset instrumentation for the correction of adolescent idiopathic scoliosis. Long-term results with an unexpected high revision rate

Long-term Outcomes of Posterior Multilevel Crack Osteotomy: Revisional Surgery for Scoliosis With a Fusion Mass

OBJECTIVE

Osteotomies are required for the mobilization of spinal segments in patients with revisional scoliosis surgery with a fusion mass; however, only a few techniques have shown efficacy and safety, and their mid- and long-term outcomes remain unelucidated. This study aimed to analyze long-term outcomes of the posterior multilevel crack osteotomy (PMCO) technique for revisional surgery for scoliosis with a fusion mass.

METHODS

Data from 18 patients who underwent revisional scoliosis surgery using PMCO between 2009 and 2015 and had more than 5-year follow-up were retrospectively reviewed. The Cobb angle and coronal and sagittal balance parameters were examined preoperatively, postoperatively, and during the final follow-up. Perioperative parameters and complications were also assessed.

RESULTS

Preoperative and postoperative Cobb angles were 60.5° and 29.9°, respectively (p < 0.001); this improvement was maintained until the final follow-up (33.4°, p = 0.058). The difference in preoperative and postoperative coronal balance was statistically significant (15.9 mm and 9.2 mm, respectively; p < 0.001); this was maintained until the final follow-up (p = 0.071). There was no change in sagittal balance parameters over the 3 measurement periods. Only 1 patient showed PMCO-related motor weakness, but he spontaneously recovered 3 months after postsurgery. Pseudarthrosis was not observed during the follow-up period.

CONCLUSION

Incomplete osteotomy using PMCO provided satisfactory deformity correction without severe complications during revisional surgery for scoliosis with a fusion mass. It may be a less invasive procedure that maintains cortical continuity, preserves soft tissues, and provides sufficient mobility for the correction of spinal segments.

Is there an indication for surgery in patients with spinal deformities? - A critical appraisal

Background

High-quality evidence exists to support physiotherapy and brace treatment for scoliosis and other spinal deformities. However, according to previous systematic reviews, it seems that no evidence exists for surgery. Nevertheless, the number of research articles focussing on spinal surgery highly exceeds the number of articles focussing on conservative treatment.

Objective

The purpose of this study is to conduct an updated search for systematic reviews providing high-quality evidence for spinal surgery in patients with spinal deformities.

Method

A narrative review including PubMed and the Cochrane database was conducted on April 12, 2020, with the following search terms: (1) spinal deformities, surgery, systematic review and outcome; (2) kyphosis, surgery, systematic review and outcome; (3) Scheuermann's disease, surgery, systematic review and outcome, and (4) scoliosis, surgery, systematic review and outcome.

Results

No reviews containing prospective controlled or randomised controlled studies were found providing evidence for surgery.

Conclusions

A general indication for spine surgery just based on the Cobb angle is not given. In view of the long-term unknown variables and the possible long-term complications of such treatment, a surgical indication for patients with spinal deformities must be reviewed on an individual basis and considered carefully. A current systematic review appears necessary in order to be able to draw final conclusions on the indication for surgery in patients with spinal deformities.

Clinical implications

In view of the increasing number of surgeons with an affiliation to industry, the indication for surgery needs to be given by independent conservative specialists for spinal deformities in order to provide an objective recommendation.

Mid-long-term outcome and degeneration of the remaining unfused lumbar intervertebral disc in adolescent idiopathic scoliosis patients who had posterior spinal fusion surgery

PURPOSE

To investigate mid-long-term effects of the lowest instrumented vertebra (LIV) selection on adolescent idiopathic scoliosis (AIS) patients who had posterior spinal fusion (PSF) surgery.

METHODS

Forty-eight patients were recruited. Inclusion criteria were AIS patients who have had PSF surgery more than 10 years ago. Patients were divided into G1: LIV L3 or higher and G2: LIV L4 or lower. MRI evaluation was classified using Pfirrmann grades. Pfirrmann scores were average of Pfirrmann grades for all unfused discs below LIV. SRS-22r, SF-36, Oswestry Disability Index (ODI) and Modified Cincinnati Sports Activity Scale (MCSAS) were used.

RESULTS

There were 19 patients in G1 and 29 patients in G2. Demographic parameters showed no significant differences. We found no significant differences in Pfirrmann grades or scores between G1 and G2. There was significant correlation between age and mean Pfirrmann scores (r = 0.546, p < 0.001), Pfirrmann grade for adjacent disc + 1 below LIV (r = 0.475, p = 0.001) and adjacent disc below LIV (r = 0.365, p = 0.011). G2 had significantly lower scores for SRS-22r pain (G1: 4.3 ± 0.5, G2: 4.0 ± 0.6, p = 0.044) and the SF-36 bodily pain (G1: 88.7 ± 12.3, G2: 77.8 ± 18.7, p = 0.018) domains. There were no significant differences in ODI and MCSAS between the two groups.

CONCLUSIONS

Patients with fusion to L4 or lower had more significant back pain. However, both groups had similar physical function, self-image, satisfaction with treatment, mental health, and functional sports activity. We did not find any significant association between lumbar discs degeneration and the selection of LIV.

A systematic scoping review and textual narrative synthesis of long-term health-related quality of life outcomes for adolescent idiopathic scoliosis

INTRODUCTION

Idiopathic scoliosis is a musculoskeletal condition leading to deformity of the spinal column. There is strong evidence reporting short term health-related quality of life outcomes, but less is known about the longer-term impact of adolescent idiopathic scoliosis (AIS). This paper reports the current evidence on long-term non-clinical outcomes of AIS.

METHOD

A systematic scoping literature review combining descriptive and textual narrative synthesis was undertaken. Studies were included if they: sampled or followed up participants at least 10 years after diagnosis and/or treatment, contained health-related quality of life data that could be extracted, where the intervention (or diagnosis in the case of untreated) occurred after 1980, and where data was extractable for modern rod and screw or fusion techniques, non-surgical interventions or untreated patients.

RESULTS

Twenty-three studies were included. Overall, the HRQOL measures utilised by these studies suggest that HRQOL is not related to participant demographics or AIS characteristics or type or extent of surgical intervention. Some studies suggest that those with AIS scored worse than controls.

DISCUSSION

Results suggest that AIS participants had a generally good quality of life, although this was often worse than those without AIS. No other clear relationships were found. The available literature fails to address more fundamental questions about how HRQOL is conceptualised for those with AIS, and there is value in pursuing qualitative inquiry in this area.

Health-related quality of life, including marital and reproductive status, of middle-aged Japanese women with posterior spinal fusion using Cotrel-Dubousset instrumentation for adolescent idiopathic scoliosis: Longer than 22-year follow-up

BACKGROUND

Few studies have examined long-term outcomes after posterior spinal fusion using Cotrel-Dubousset instrumentation (CDI) for adolescent idiopathic scoliosis (AIS). Most patients with AIS are female, and their main concern is how spinal fusion will affect their future life. This study aimed to investigate the long-term health-related quality of life (HRQOL), including marital and reproductive status, of middle-aged Japanese women who underwent posterior spinal fusion using CDI for AIS in its earliest days in Japan.

METHODS

Japanese women who were younger than 20 years of age at the time of surgery using CDI, between 1985 and 1995, were targeted. Roland-Morris Disability Questionnaire, Oswestry Disability Index, Scoliosis Research Society-22 questionnaire, and 36-Item Short-Form Survey (SF-36) were used to evaluate HRQOL. Marital and reproductive status were also investigated. These results were compared to those of healthy women controls and Japanese national data for 2015.

RESULTS

Of 87 female patients, 29 (33.3%) were included, with 71 healthy women as controls. The average age of the patient group was 42.7 years (range 37-48 years), and the average follow-up period was 27.5 years (range 22-32 years). HRQOL scores in the patient group were generally lower than that in the healthy control group, although there was no significant difference between the two groups in the role component summary score (RCS) of SF-36. Marital and reproductive status were not significantly different between patient and control groups, and results for the patient group were similar to Japanese national data.

CONCLUSIONS

This is the first study of HRQOL in middle-aged patients who underwent posterior spinal fusion using CDI for AIS in Japan. Although HRQOL scores expect RCS of the patient group were lower than those of the healthy control group, the effects of posterior spinal fusion using CDI on women's social life and marital and reproductive statuses were minimal.

Intervertebral Disc Degeneration During Postoperative Follow-up More Than 10 Years After Corrective Surgery in Idiopathic Scoliosis: Comparison Between Patients With and Without Surgery

STUDY DESIGN

A retrospective comparative study.

OBJECTIVE

The aim of this study was to evaluate the difference in trends of disc degeneration (DD) at lower unfused segments (LUS) for postoperative patients who have gone through spinal instrumentation at 10-year follow-up with the natural progression of idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Studies that used magnetic resonance imaging (MRI) state that DD rates at LUS are higher than in the normal population. However, current studies do not prove that surgery is the most effective clinical method to treat idiopathic scoliosis, as no existing report compares the rates of DD with the natural history of idiopathic scoliosis.

METHODS

Female patients diagnosed of scoliosis were divided into three groups: 1) surgical group: postoperative 10-year patients with severe scoliosis before operation; 2) mild scoliosis group: with comparatively equal scoliosis to postoperative patients of the same age at 10 years follow-up; 3) severe scoliosis group: without any record of corrective surgery under the assumption that the scoliosis of the surgical group have progressed according to natural history.

RESULTS

MRI findings of the surgical group show DD in 32 patients (62.7%) where the highest rate of DD occurred at L5/S. In the mild scoliosis group, 21 patients (47.7%) had DD, with higher rates at L4/5 and L5/S. DD was most common in L3/4 and L4/5 in the severe scoliosis group where 27 patients (81.8%) had DD. As such, DD rates were significantly higher in the severe scoliosis group than the surgical group at the same spinal level. The same was true for the existence of low back pain, where the severe scoliosis group had greater incidence of low back pain than the surgical group.

CONCLUSION

Corrective surgeries were able to reduce the incidence of DD. Radiological analysis also suggests that surgical intervention is a clinically feasible treatment for idiopathic scoliosis patients.

LEVEL OF EVIDENCE

3.

Management of Spinal Deformities and Evidence of Treatment Effectiveness

INTRODUCTION

The review evaluates the up-to-date evidence for the treatment of spinal deformities, including scoliosis and hyperkyphosis in adolescents and adults.

MATERIAL AND METHODS

The PubMed database was searched for review articles, prospective controlled trials and randomized controlled trials related to the treatment of spinal deformities. Articles on syndromic scoliosis were excluded and so were the articles on hyperkyphosis of the spine with causes other than Scheuermann's disease and osteoporosis. Articles on conservative and surgical treatments of idiopathic scoliosis, adult scoliosis and hyperkyphosis were also included. For retrospective papers, only studies with a follow up period exceeding 10 years were included.

RESULTS

The review showed that early-onset idiopathic scoliosis has a worse outcome than late-onset idiopathic scoliosis, which is rather benign. Patients with AIS function well as adults; they have no more health problems when compared to patients without scoliosis, other than a slight increase in back pain and aesthetic concern. Conservative treatment of adolescent idiopathic scoliosis (AIS) using physiotherapeutic scoliosis-specific exercises (PSSE), specifically PSSR and rigid bracing was supported by level I evidence. Yet to date, there is no high quality evidence (RCT`s) demonstrating that surgical treatment is superior to conservative treatment for the management of AIS. For adult scoliosis, there are only a few studies on the effectiveness of PSSEs and a conclusion cannot as yet be drawn.For hyperkyphosis, there is no high-quality evidence for physiotherapy, bracing or surgery for the treatment of adolescents and adults. However, bracing has been found to reduce thoracic hyperkyphosis, ranging from 55 to 80° in adolescents. In patients over the age of 60, bracing improves the balance score, and reduces spinal deformity and pain. Surgery is indicated in adolescents and adults in the presence of progression of kyphosis, refractory pain and loss of balance.

DISCUSSION

The available evidence reviewed has suggested that different approaches are needed towards the management of different spinal deformities. Specific exercises should be prescribed in children and adolescents with a Cobb angle in excess of 15°. In progressive curves, they should be used in conjunction with bracing. Clarity regarding differences and similarities is given as to what makes PSSE and PSSR specific exercises. As AIS is relatively benign in nature, conservative treatment should be tried when the curve is at a surgical threshold, before surgery is considered. Similarly, bracing and exercises should be prescribed for patients with hyperkyphosis, particularly when the lumbar spine is afflicted. Surgery should be considered only when the symptoms cannot be managed conservatively.

CONCLUSION

There is at present high quality evidence in support of the conservative treatment of AIS. The current evidence supports the use of PSSE, especially those using PSSR, together with bracing in the treatment of AIS. In view of the lack of medical consequences in adults with AIS, conservative treatment should be considered for curves exceeding the formerly assumed range of conservative indications.There is, however a lack of evidence in support of any treatment of choice for hyperkyphosis in adolescents and spinal deformities in adults. Yet, conservative treatment should be considered first. Yet to date, there is no high quality evidence (RCT`s) demonstrating that surgical treatment is superior to conservative treatment for the management of AIS and hyperkyphosis. Additionally, surgery needs to be considered with caution, as it is associated with a number of long-term complications.

Scoliosis in adulthood-a case with untreated early onset scoliosis presenting at the age of 76 years

[Purpose] Untreated early-onset scoliosis may eventually progress to more than 90° after growth, cause severe health problems, and increase chance of mortality. Therefore, surgical intervention is often indicated prior to the development of a life-threatening deformity. This case report aims to reveal how a 76-year-old male patient with curves exceeding 110° is functioning with minimal difficulty. [Subject and Methods] The patient, who has never had surgical intervention for scoliosis, can perform his everyday activities. His curves were 111° thoracic and 118° lumbar when he presented at the author’s office in January 2015. [Results] The patient reported that he rarely needs a physician and participates in endurance sports like jogging. Despite this, the patient recognizes his restrictive ventilation disorder (shortness of breath) when he is inactive. The patient complained of shortness of breath and cosmetic concerns. [Conclusion] The current guidelines indicate that early-onset scoliosis should be operated at a young age; however, this protocol is not supported by high-quality evidence. Notably, patients with curvatures exceeding 100° after puberty may have a reasonable quality of life when they lead an active life with regular participation in endurance sports and physical rehabilitation.

Long-Term Effects of Untreated Adolescent Idiopathic Scoliosis: A Review of the Literature

Currently, adolescent idiopathic scoliosis (AIS) is principally regarded as benign, but some researchers have cited serious or extreme effects, including severe pain, cardiopulmonary compromise, social isolation, and even early death. Therefore, exploration of the long-term effects of AIS, the most common type of idiopathic scoliosis, is warranted. The purpose of this review was to examine the long-term studies on the natural history of AIS and/or reviews concerning the long-term effects of untreated AIS. A PubMed search was conducted using the key words idiopathic scoliosis, long-term effects and idiopathic scoliosis, natural history. For further analysis, references cited in those studies were reviewed for additional, related evidence not retrieved in the initial PubMed search. A review of the pertinent bibliography showed that older natural history studies did not distinguish between late-onset scoliosis (referred to in this paper as AIS) and early-onset scoliosis (EOS). The more recent studies offer such important distinction and reach to the general conclusion that untreated AIS does not lead to severe consequences with respect to signs and symptoms of scoliosis. It is possible that earlier studies may have included patient populations with EOS, leading to the perception of untreated scoliosis as having an unusually high morbidity rate. Studies on the long-term effects of AIS that specifically excluded EOS patients conclude that AIS is a benign disorder. This indicates that for research and reporting purposes, it is important to distinguishing between AIS and EOS. This will allow the practitioner and patient and their families to decide on an optimal treatment plan based on the most appropriate prognosis.

A Comparison of Patient-Reported Outcome Measures Following Different Treatment Approaches for Adolescents with Severe Idiopathic Scoliosis: A Systematic Review

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine which is usually not symptomatic and which can progress during growth and cause a surface deformity. In adulthood, if the final spinal curvature surpasses a certain critical threshold, the risk of health problems and curve progression is increased. Although surgery is usually recommended for curvatures exceeding 40° to 50° to stop curvature progression, recent reviews have shed some light on the long-term complications of such surgery and to the lack of evidence for such complicated procedures within the scientific literature. Furthermore, a number of patients are very fearful of having surgery and refuse this option or live in countries where specialist scoliosis surgery is not available. Other patients may be unable to afford the cost of specialist scoliosis surgery. For these patients the only choice is an alternative non-surgical treatment option. To examine the impact of different management options in patients with severe AIS, with a focus on trunk balance, progression of scoliosis, cosmetic issues, quality of life, disability, psychological issues, back pain, and adverse effects, at both the short-term (a few months) and the long-term (over 20 years). We searched CENTRAL, MEDLINE, EMBASE, CINHAL and two other databases up to January 2016 with no language limitations. We also checked the reference lists of relevant articles and conducted an extensive hand search of the grey literature. We searched for randomised controlled trials as well as prospective and retrospective controlled trials comparing spinal fusion surgery with no treatment or conservative treatment in AIS patients with a Cobb angle greater than 40°. We did not identify any evidence of superiority of effectiveness of operative compared to nonoperative interventions for patients with severe AIS. Within the present literature there is no clear evidence to suggest that a specific type of treatment is superior to other types of treatment.

Scoliosis bracing and exercise for pain management in adults-a case report

[Purpose] For adult patients with late-onset idiopathic scoliosis, cosmetic concerns and pain are the main reasons for seeking treatment at a physician’s office. The purpose of this paper was to describe the mid-term effect of physical rehabilitation and part-time bracing on an adult scoliosis patient who had been suffering from chronic low back pain for fourteen years. [Subject and Methods] Case description: A 37-year-old female patient with late-onset idiopathic scoliosis presented in the office of the first author in January 2014. She reported having chronic pain (low back pain) since the age of 23 and reported daily pain at a level of 5–7 on average on a Visual Analogue Scale of 0 to 10. She received a short scoliosis-specific Schroth exercise program and was also fitted with a Gensingen brace for part-time wear. [Results] At a 16 month follow-up, the patient no longer suffered from daily low back pain (with heavy lifting only) and was fully active. Additionally, her lumbar Cobb angle and angle of trunk rotation improved. [Conclusion] Patients with late-onset idiopathic scoliosis and pain may benefit from a pattern-specific conservative treatment approach. In this population, surgical intervention should be regarded as the last resort, since there are many long-term unknowns with surgery.

Radiologic and histological observations in experimental T1-T12 dorsal arthrodesis: A qualitative description of T1-T12 segment and other body parts involved, between prepubertal age and skeletal maturityxs

BACKGROUND

This experimental study provides a qualitative description and the morpho-structural features of the fusions taking place in the thoracic spine between prepubertal age and skeletal maturity. There is a lack of informations regarding the influence of partial or total dorso-thoracic vertebral arthrodesis on the development of the thoracic cage as well as its potential effects on different intra and extra-thoracic organs. This study admits the hypothesis that vertebral arthrodesis may have influence on other body areas and so, it intends to verify the possible secondary involvement of other body parts, such as intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs.

MATERIALS AND METHODS

Fifty-four female New Zealand white rabbits were submitted to dorsal arthrodesis. The radiologic imaging and light microscopy histological pictures were taken and studied in all. Computed tomography (CT) scan measurements were performed in operated and sham operated rabbits at different time. Similarly, histological specimens of intervertebral discs, cervical and thoracic spinal ganglia, sternocostal cartilage, ovaries and lungs were analyzed at different times. The study ended at the age of 17-18 months.

RESULTS

Most rabbits had formed a fusion mass, which was only fibrous at first, then osteofibrous and finally, in the older subjects, structured in lamellar-osteon tissue. Intervertebral foramens were negatively involved in vertebral arthrodesis, as shown by CT scans. Intervertebral discs showed irregular aspects. The increase of atresic follicles and the reduction of primordial follicles in operated rabbits led to the hypothesis of a cause-effect relationship between arthrodesis and modified hormonal status. Dorsal root ganglia showed microscopic alterations in operated rabbits especially.

CONCLUSIONS

The process of fusion mass and bone formation, associated with the arthrodesis, involves at different degrees of the vertebral bodies, discs and intervertebral foramens, ganglia and spinal nerve roots.

Surgical management of neurologically complicated kyphoscoliosis using transposition of the spinal cord: Case report

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Case of patient with single-stage correction of severe congenital kyphoscoliotic spinal deformities is provided.

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Combined anterior-posterior approach was applied.

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Transposition of the spinal cord followed by correction using vertebral instrumentation made it possible to improve trunk balance and stop deformity progression.

Background

Transposition of the spinal cord made it possible to achieve mobilization of the fixed kyphoscoliosis, significantly increase spinal canal volume and improve spinal canal shape. This helped to eliminate spinal cord compression and achieve complete regression of the existing neurological symptoms.

Methods and results

We report the clinical case of surgical management of neurologically complicated kyphoscoliotic deformity of the thoracic spine by transposition of the spinal cord and correction using posterior segmental spinal instrumentation.

Conclusions

The required correction of severe kyphoscoliosis was performed; the risks of trunk imbalance, deformity progression, and instrumentation failure in the long-term postoperative period were reduced.

Level of evidence

Level IV – 1 case.

Reckoning: Assessment of a 21-year activity in spine surgery

Introduction: Of the world-wide used Cotrel–Dubousset instrumentation and surgical technique providing breakthrough for the three-dimensional correction and multi-segmental fixation of spinal deformity surgery in Hungary is linked to the author’s name, who carried out 1655 spine deformity surgeries in the last 21 years. Aim: The aim of the author was to discuss his own results in the field of spine surgery and compare his own data to those published in the international literature. Method: At the beginning hooks, followed by hybrid instrumentation with hooks in thoracic area and transpedicular screws in lumbar spine have been used for the segmental fixation. During the correction process, initially the classic derotation maneuver was used, followed by the translation and then the in situ bending techniques and, finally, a combination of the above three techniques have been applied. Results: In addition to the restoration of normal sagittal balance, an average of 40.8° (SD, 25.9), a 65.5% correction was achieved in the frontal plane, which partly exceeds and partly consistent with the published international results. The incidence of inflammation (3.9%), and mechanical complications (1.7%) was similar to the international average, while the incidence of neurological complications (0.48%) was slightly lower than the average of international data. Conclusions: The author believes that the better correction results as compared to the international average could be due to the always consistent application of the Cotrel–Dubousset instrumentation correction philosophy based on the meticulous segmental analysis of spine deformities. Orv. Hetil., 2015, 156(15), 598–607.

Serial case reporting yoga for idiopathic and degenerative scoliosis

Background:

Non-surgical techniques for treating scoliosis frequently focus on realigning the spine, typically by muscular relaxation or muscular or ligamentous stretching. However, such treatments, which include physical therapeutic, chiropractic, and bracing techniques, are inconsistently supported by current evidence. In this study, we assess the possible benefits of asymmetrical strengthening of truncal muscles on the convex side of the scoliotic curve through a single yoga pose, the side plank pose, in idiopathic and degenerative scoliosis.

Methods:

Twenty-five patients with idiopathic or degenerative scoliosis and primary curves measuring 6 to 120 degrees by the Cobb method had spinal radiographs and were then taught the side plank pose. After 1 week performing the pose with convexity downward for 10 to 20 seconds, they were instructed to maintain the posture once daily for as long as possible on that one side only. A second series of spinal radiographs was taken 3 to 22 months later. Pre- and post-yoga Cobb measurements were compared.

Results:

The mean self-reported practice of the yoga pose was 1.5 minutes per day, 6.1 days per week, for a mean follow-up period of 6.8 months. Among all patients, a significant improvement in the Cobb angle of the primary scoliotic curve of 32.0% was found. Among 19 compliant patients, the mean improvement rose to 40.9%. Improvements did not differ significantly among adolescent idiopathic and degenerative subtypes (49.6% and 38.4%, respectively).

Conclusions:

Asymmetrically strengthening the convex side of the primary curve with daily practice of the side plank pose held for as long as possible for an average of 6.8 months significantly reduced the angle of primary scoliotic curves. These results warrant further testing.

Indication for surgical treatment in patients with adolescent Idiopathic Scoliosis - a critical appraisal

A recent literature search of the pertinent publications in the field revealed that there is poor evidence that would support surgical intervention in patients with Adolescent Idiopathic Scoliosis (AIS). With complications estimated to exceed 50% over a lifetime, surgical intervention is unwarranted in the 'Adolescent Idiopathic Scoliosis' AIS population. In the relatively benign population of patients with AIS, according to the findings in literature, we may conclude that the long-term outcome of surgery for AIS creates a more negative end result over the course of a lifetime than the natural history of the condition itself.As a result, surgeons electing to recommend surgery are strongly advised to openly discuss and inform patients of the long-term probability of potential complications occurring after spinal fusion surgery, and document their explanations accordingly.