Prognostic Factors after Surgical Treatment for Spinal Metastases

Study Design

A retrospective multicenter case series was conducted.

Purpose

This study aimed to investigate survival and prognostic factors after surgery for a metastatic spinal tumor.

Overview of Literature

Prognostic factors after spinal metastasis surgery remain controversial.

Methods

A retrospective multicenter study was conducted. The study participants included 345 patients who underwent surgery for spinal metastases from 2010 to 2020 at nine referral spine centers in Japan. Data for each patient were extracted from medical records. To identify the factors predicting survival prognosis after surgery, univariate analyses were performed using a Cox proportional hazards model.

Results

The mean age was 65.9 years. Common primary tumors were lung (n=72), prostate (n=61), and breast (n=39), and 67.8% (n=234) presented with osteolytic lesions. The epidural spinal cord compression scale score 2 or 3 was recognized in 79.0% (n=271). Frankel grade A paralysis accounted for 1.4% (n=5), and 73.3% (n=253) were categorized as intermediate or high risk according to the new Katagiri score. The overall survival rates were -71.0% at 6 months, 57.4% at 12, and 43.3% at 24. In the univariate analysis, Frankel grade A (hazard ratio [HR], 3.59; 95% confidence interval [CI], 1.23-10.50; p<0.05), intermediate risk (HR, 3.34; 95% CI, 2.10-5.32; p<0.01), and high risk (HR, 7.77; 95% CI, 4.72-12.8; p<0.01) in the new Katagiri score were significantly associated with poor survival. On the contrary, postoperative chemotherapy (HR, 0.23; 95% CI, 0.15-0.36; p<0.01), radiation therapy (HR, 0.43; 95% CI, 0.26-0.70; p<0.01), and both adjuvant therapy (HR, 0.21; 95% CI, 0.14-0.32; p<0.01) were suggested to improve survival.

Conclusions

Surgical indications for patients with Frankel grade A or intermediate or high risk in the new Katagiri score should be carefully considered because of poor survival. Chemotherapy or radiation therapy should be considered after surgery for better survival.

Pressure Dynamics on Intervertebral Disc Cages in Transforaminal Lumbar Interbody Fusion: A Cadaver Study

OBJECTIVE

This study aimed to quantify the change in pressure on the cage during compression manipulation in lumbar interbody fusion. While the procedure involves applying compression between pedicle screws to press the cage against the endplate, the exact compression force remains elusive. We hypothesize that an intact facet joint might serve as a fulcrum, potentially reducing cage pressure.

METHODS

Pressure on the intervertebral disc cage was measured during compression manipulation in 4 donor cadavers undergoing lumbar interbody fusion. Unilateral facetectomy models with both normal and parallel compression and bilateral facetectomy models were included. A transforaminal lumbar interbody fusion cage with a built-in load cell measured the compression force.

RESULTS

Pressure data from 14 discs indicated a consistent precompression pressure average of 68.16 N. Following compression, pressures increased to 125.99 N and 140.84 N for normal and parallel compression postunilateral facetectomy, respectively, and to 154.58 N and 150.46 N for bilateral models. A strong linear correlation (correlation coefficient: 0.967, P < 0.0001) between precompression and postcompression pressures emphasized the necessity of sufficient precompression pressure for achieving desired postcompression outcomes. None of the data showed a decrease in compression force to the cage with the compression maneuver.

CONCLUSIONS

Both normal and parallel compression maneuvers effectively increased the pressure on the cage, irrespective of the facet joint resection status. Compression manipulation consistently enhanced compressive force on the cage. However, when baseline pressure is low, the manipulation might not yield significant increases in compression force. This underlines the essential role of meticulous precompression preparation in enhancing surgical outcomes.

Are Dental Procedures Associated With Pyogenic Vertebral Osteomyelitis?

BACKGROUND

Dental procedures can lead to bacteremia and have been considered a potential risk factor for pyogenic vertebral osteomyelitis (PVO). However, data on the association between dental procedures and PVO are limited.

QUESTIONS/PURPOSES

(1) After controlling for relevant confounding variables, are dental procedures associated with an increased risk of PVO? (2) Does antibiotic prophylaxis before dental procedures effectively decrease the risk of PVO?

METHODS

A case-crossover study was conducted to investigate the association between dental procedures and PVO using a Japanese claims database. The advantage of this study design is that confounding factors that do not vary over time are automatically adjusted for, because cases act as their own controls. From April 2014 to September 2021, the database included 8414 patients who were hospitalized for PVO. Of these, 50% (4182 of 8414) were excluded because they had not undergone any dental procedures before the index date, a further 0.1% (10 of 8414) were excluded because they were younger than 18 years at the index date, and a further 7% (623 of 8414) were excluded because they did not have at least 20 weeks of continuous enrollment before the index date, leaving 43% (3599 of 8414) eligible for analysis here. The mean age was 77 ± 11 years, and 55% (1985 of 3599) were men. Sixty-five percent (2356 of 3599) of patients had a diagnosis of diabetes mellitus, and 42% (1519 of 3599) of patients had a diagnosis of osteoporosis. We compared the frequency of dental procedures between a 4-week hazard period before the admission date for PVO and two control periods, 9 to 12 weeks and 17 to 20 weeks before the admission date for PVO, within individuals. We calculated odds ratios and 95% confidence intervals using conditional logistic regression analysis.

RESULTS

Comparing the hazard and matched control periods within individuals demonstrated that dental procedures were not associated with an increased risk of PVO (OR 0.81 [95% CI 0.72 to 0.92]; p < 0.001). Additional analysis stratified by antibiotic prophylaxis use showed that antibiotic prophylaxis was not associated with a lower OR of developing PVO after dental procedures (with antibiotic prophylaxis: OR 1.11 [95% CI 0.93 to 1.32]; p < 0.26, without antibiotic prophylaxis: OR 0.72 [95% CI 0.63 to 0.83]; p < 0.001). Our sensitivity analyses, in which the exposure assessment interval was extended from 4 to 8 or 12 weeks and exposure was stratified by whether the dental procedure was invasive, demonstrated results that were consistent with our main analysis.

CONCLUSION

Dental procedures were not associated with an increased risk of subsequent PVO in this case-crossover study. The effectiveness of antibiotic prophylaxis was not demonstrated in the additional analysis that categorized exposure according to the use of antibiotic prophylaxis. Our results suggest that the association between dental procedures and PVO may have been overestimated. Maintaining good oral hygiene may be important in preventing the development of PVO. The indications for antibiotic prophylaxis before dental procedures should be reconsidered in view of the potential risk of adverse drug reactions to antibiotic prophylaxis and the emergence of drug-resistant pathogens. Larger randomized controlled trials are needed to confirm these findings and assess the role of antibiotic prophylaxis.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Neurological recovery rate and predictive factors of incomplete AIS grade C spinal cord injury in the older aged population

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To define the prognosis and predictive factors for neurological improvement in older patients with incomplete spinal cord injury (SCI) of American Spinal Injury Association Impairment Scale grade C (AIS-C).

SETTINGS

Multi-institutions in Japan.

METHODS

We included patients aged ≥65 years with traumatic SCI of AIS-C who were treated conservatively or surgically with >3 follow-up months. To identify factors related to neurological improvement, patients were divided into three groups according to their neurological status at the final follow-up, with univariate among-group comparisons of demographics, radiographic, and therapeutic factors. Significant variables were included in the multivariate logistic regression analysis.

RESULTS

Overall, 296 older patients with SCI of AIS-C on admission were identified (average age: 75.2 years, average follow-up: 18.7 months). Among them, 190 (64.2%) patients improved to AIS-D and 21 (7.1%) patients improved to AIS-E at final follow-up. There were significant among-group differences in age (p = 0.026), body mass index (p = 0.007), status of pre-traumatic activities of daily living (ADL) (p = 0.037), and serum albumin concentrations (p = 0.011). Logistic regression analysis showed no significant differences in variables in the stratified group of patients who improved to AIS-D. Meanwhile, serum albumin was a significant variable in patients who improved to AIS-E (p = 0.026; OR: 6.20, pre-traumatic ADL was omitted due to data skewness).

CONCLUSIONS

Most older patients with incomplete AIS-C SCI demonstrated at least 1 grade of neurological improvement. However, <10% of patients achieved complete recovery. Key predictors of complete recovery were high serum albumin levels on admission and independent pre-traumatic ADL.

SPONSORSHIP

No funding was received for this study.

S2 Alar Screw Insertion Accuracy and Factors Associated With Screw Loosening and Lumbosacral Nonunion

OBJECTIVE

To investigate S2 alar screw (S2AS) accuracy and factors associated with S2AS loosening and lumbosacral nonunion.

METHODS

We retrospectively reviewed patients who underwent lumbosacral fusion surgery with S2AS addition under fluoroscopy. S2AS loosening and lumbosacral nonunion were analyzed using a 1-year postoperative computed tomography. S2AS insertion accuracy was originally classified as accurate, short, anterior perforation, lateral perforation, and sacroiliac joint (SIJ) deviation among lateral perforation. Clinical data including sex, age, body mass index, fused segments, fusion procedure, primary or revision surgery, Japanese Orthopedic Association scores and complications were collected. Factors associated with S2AS loosening and lumbosacral nonunion were analyzed.

RESULTS

A total of 37 patients (74 screws, age: 63.78 ± 13.57 years, female/male: 14/23 patients, body mass index: 23.11 ± 2.53, fused segments: 1-4 levels, revision: 38%) were included. S2AS loosening and lumbosacral nonunion were observed in 18 screws (13%) and 8 patients (22%) respectively. Only 35 screws (47%) were inserted accurately in our classification. Short, lateral perforation, and anterior perforation were observed in 14 screws (19%), 22 screws (30%), and 3 screws (4.1%). SIJ deviation was seen in 15 screws (20%) Factors associated with S2AS loosening were older age (P = 0.038), fusion levels (P = 0.011), and SIJ deviation (P < 0.001). S2AS loosening affects S1 pedicle screw (S1PS) loosening (P = 0.001). Furthermore, S2AS loosening is a risk factor for lumbosacral nonunion (P = 0.046).

CONCLUSIONS

S2AS insertion under fluoroscopy is inaccurate. S2AS loosening induces S1PS loosening and lumbosacral nonunion. Surgeons should avoid deviating to SIJ, especially in older patients and relatively longer fusion.

Low Hounsfield unit values on computed tomography as a potential predictor of vertebral fracture in patients with rheumatoid arthritis: The KURAMA cohort study

OBJECTIVE

Hounsfield units (HU) measured using computed tomography (CT) have gained considerable attention for the detection of osteoporosis. This study aimed to investigate whether opportunistic CT could predict vertebral fractures in patients with rheumatoid arthritis (RA).

METHODS

A total of 233 patients with RA who underwent chest CT were included in this study. The HU values of the anterior 1/3 of the vertebral bodies based on the sagittal plane at T11-L2 after reconstruction were measured. The incidence of vertebral fractures was investigated with respect to the HU value.

RESULTS

Vertebral fractures were identified in 32 patients during a mean follow-up period of 3.8 years. In patients who experienced vertebral fractures within 2 years of CT imaging, the HU values of the vertebral bodies (T11-L2) were lower than those in patients who did not experience fractures. Receiver operating characteristic curve analysis identified that a T11 HU value of <125 was a risk factor for vertebral fracture within 2 years. Multivariate analysis showed that a T11 HU value of <125 and the existence of prevalent vertebral fractures were significant risk factors for fracture.

CONCLUSION

HU measurements of the anterior 1/3 of the vertebral body are a potential predictor for vertebral fractures in patients with RA.

Sagittal Section Hounsfield Units of the Upper Instrumented Vertebrae as a Predictor of Proximal Junctional Vertebral Fractures Following Adult Spinal Deformity Surgery

STUDY DESIGN

A retrospective observational study.

PURPOSE

This study aimed to determine an accurate and convenient screening method for predicting proximal junctional fractures (PJFr) following surgery for adult spinal deformity (ASD) using computed tomography (CT)-based measurement of Hounsfield units (HUs).

OVERVIEW OF LITERATURE

CT-based measurement of HUs is an alternative tool for assessing bone mineral density. However, the optimal method for predicting adjacent vertebral fractures following spinal fusion using HUs remains unclear.

METHODS

This retrospective observational study included 42 patients who underwent reconstructive surgery for ASD. Elliptical regions of interest (ROIs) on the axial section and rectangular ROIs on the sagittal section were placed at the upper instrumented vertebrae (UIV), UIV+1, and UIV+2. In addition, the HU value of the L2 vertebra was used as the representative.

RESULTS

PJFr occurred in 28.6% of patients within 2 years following surgery. The HU values obtained from the axial sections of L2, UIV, UIV+1, and UIV+2 were not significantly associated with the incidence of PJFr within 2 years, except for the ROI set in the lower region of the L2 vertebra. However, the HU value of the anterior third of the UIV in the sagittal section was significantly lower in the PJFr group than in the nonPJFr group (87.0 vs. 160.3, p =0.001). A UIV HU value of <100 was associated with a higher incidence of PJFr than an HU vaue of >100 (p <0.05).

CONCLUSIONS

Measurements of HU in the anterior one-third of the UIV in the sagittal section demonstrated predictive ability for PJFr following ASD surgery. A UIV HU value of <100 emerged as a risk factor for PJFr.

Bone ingrowth into a porous structure is achieved by preceding fibrogenesis and vascularization

Porous structures are frequently used in surgical implants to strengthen the interlocking power produced by bone ingrowth. Therefore, we aimed to elucidate the mechanism underlying bone ingrowth into a porous structure accompanied by vascularization. A nonbioactive polyetheretherketone implant with a 3D-printed porous structure was prepared and implanted in a bone hole created in the tibias of rabbits. We observed bone ingrowth in the same individual specimens immediately and at 2, 4, 8, and 12 weeks post-implantation using in-vivo computed tomography (CT). Furthermore, a detailed evaluation with blood vessels of each specimen at 2, 4, and 12 weeks was performed with ex-vivo CT and histological specimen. Additional histological evaluation was performed using thin sections of an implant made with thermoplastic polyurethane having the same structure. As a result, the bone invasion began after four weeks, when the construction of fibrous tissue and the spread of new blood vessels within the voids matured. As the bone matured in the load-bearing area, new blood vessels outside the bone matrix regressed. This longitudinal evaluation study suggests that preceding fibrogenesis and vascularization may be key in developing bone ingrowth. STATEMENT OF SIGNIFICANCE: A porous structure is an essential structure for dental and orthopedic implants because it provides strong fixation through bone invasion. Although it was known that vascularization was involved in this, the details were not known. This in vivo study revealed that in order for bone ingrowth to begin, a preparatory period of approximately 4 weeks was required to establish blood flow inside and outside the implant. Furthermore, it was confirmed that by spreading the fibrous structure in advance, it has an advantageous effect on the migration of cells involved in the formation of bones and blood vessels. We pointed out that it is necessary to consider fibrogenesis and vascularization when creating future implants.

Impact of malnutrition on mortality and neurological recovery of older patients with spinal cord injury

This retrospective cohort study established malnutrition's impact on mortality and neurological recovery of older patients with cervical spinal cord injury (SCI). It included patients aged ≥ 65 years with traumatic cervical SCI treated conservatively or surgically. The Geriatric Nutritional Risk Index was calculated to assess nutritional-related risk. Overall, 789 patients (mean follow-up: 20.1 months) were examined and 47 had major nutritional-related risks on admission. One-year mortality rate, median survival time, neurological recovery, and activities of daily living (ADL) at 1 year post-injury were compared between patients with major nutrition-related risk and matched controls selected using 1:2 propensity score matching to adjust for age, pre-traumatic neurological impairment, and activity. In the Kaplan-Meier analysis, the median survival times were 44.9 and 76.5 months for patients with major nutrition-related risk and matched controls, respectively (p = 0.015). Matched controls had more individuals with a neurological improvement of American Spinal Injury Association Impairment Scale ≥ 1 grade (p = 0.039) and independence in ADL at 1 year post-injury than patients with major nutrition-related risk (p < 0.05). In conclusion, 6% of older patients with cervical SCI had major nutrition-related risks; they showed a significantly higher 1 year mortality rate, shorter survival time, poorer neurological improvement, and lower ADL at 1 year post-injury than matched controls.

Strontium-loaded 3D intramedullary nail titanium implant for critical-sized femoral defect in rabbits

The treatment of critical-sized bone defects has long been a major problem for surgeons. In this study, an intramedullary nail shaped three-dimensional (3D)-printed porous titanium implant that is capable of releasing strontium ions was developed through a simple and cost-effective surface modification technique. The feasibility of this implant as a stand-alone solution was evaluated using a rabbit's segmental diaphyseal as a defect model. The strontium-loaded implant exhibited a favorable environment for cell adhesion, and mechanical properties that were commensurate with those of a rabbit's cortical bone. Radiographic, biomechanical, and histological analyses revealed a significantly higher amount of bone ingrowth and superior bone-bonding strength in the strontium-loaded implant when compared to an untreated porous titanium implant. Furthermore, one-year histological observations revealed that the strontium-loaded implant preserved the native-like diaphyseal bone structure without failure. These findings suggest that strontium-releasing 3D-printed titanium implants have the clinical potential to induce the early and efficient repair of critical-sized, load-bearing bone defects.

Early Versus Delayed Surgery for Elderly Traumatic Cervical Spinal Injury: A Nationwide Multicenter Study in Japan

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVES

The effectiveness of early surgery for cervical spinal injury (CSI) has been demonstrated. However, whether early surgery improves outcomes in the elderly remains unclear. This study investigated whether early surgery for CSI in elderly affects complication rates and neurological outcomes.

METHODS

This retrospective multicenter study included 462 patients. We included patients with traumatic acute cervical spinal cord injury aged ≥65 years who were treated surgically, whereas patients with American Spinal Injury Association (ASIA) Impairment Scale E, those with unknown operative procedures, and those waiting for surgery for >1 month were excluded. The minimum follow-up period was 6 months. Sixty-five patients (early group, 14.1%) underwent surgical treatment within 24 hours, whereas the remaining 397 patients (85.9%) underwent surgery on a standby basis (delayed group). The propensity score-matched cohorts of 63 cases were compared.

RESULTS

Patients in the early group were significantly younger, had significantly more subaxial dislocations (and fractures), tetraplegia, significantly lower ASIA motor scores, and ambulatory abilities 6 months after injury. However, no significant differences in the rate of complications, ambulatory abilities, or ASIA Impairment Scale scores 6 months after injury were observed between the matched cohorts. At 6 months after injury, 61% of the patients in the early group (25% unsupported and 36% supported) and 53% of the patients in the delayed group (34% unsupported and 19% supported) were ambulatory.

CONCLUSIONS

Early surgery is possible for CSI in elderly patients as the matched cohort reveals no significant difference in complication rates and neurological or ambulatory recovery between the early and delayed surgery groups.

Prognostic Factors for Respiratory Dysfunction for Cervical Spinal Cord Injury and/or Cervical Fractures in Elderly Patients: A Multicenter Survey

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

The purpose of this study was to investigate the prognosis of respiratory function in elderly patients with cervical spinal cord injury (SCI) and to identify predictive factors.

METHODS

We included 1353 cases of elderly cervical SCI patients collected from 78 institutions in Japan. Patients who required early tracheostomy and ventilator management and those who developed respiratory complications were defined as the respiratory disability group. Patients' background characteristics, injury mechanism, injury form, neurological disability, complications, and treatment methods were compared between the disability and non-disability groups. Multiple logistic regression analysis was used to examine the independent factors. Patients who required respiratory management for 6 months or longer after injury and those who died of respiratory complications were classified into the severe disability group and were compared with minor cases who were weaned off the respirator.

RESULTS

A total of 104 patients (7.8%) had impaired respiratory function. Comparisons between the disabled and non-disabled groups and between the severe and mild injury groups yielded distinct trends. In multiple logistic regression analysis, age, blood glucose level, presence of ossification of posterior longitudinal ligament (OPLL), anterior vertebral hematoma, and critical paralysis were selected as independent risk factors.

CONCLUSION

Age, OPLL, severe paralysis, anterior vertebral hematoma, hypoalbuminemia, and blood glucose level at the time of injury were independent factors for respiratory failure. Hyperglycemia may have a negative effect on respiratory function in this condition.

Risk Factors for Cage Migration Following Lateral Lumbar Interbody Fusion Combined With Posterior Instrumentation: A Multicenter Retrospective Study of 983 Cases

STUDY DESIGN

A multicenter retrospective study.

OBJECTIVE

This study aimed to elucidate the incidence and risk factors of lateral cage migration (LCM) after lateral lumbar interbody fusion (LLIF) combined with posterior instrumentation.

SUMMARY OF BACKGROUND DATA

LLIF has recently become a widely accepted procedure for the treatment of lumbar degenerative diseases. Although LLIF complications include vascular, nerve, and abdominal organ injuries, few studies have identified specific risk factors for LCM after LLIF.

MATERIALS AND METHODS

Between January 2015 and December 2020, 983 patients with lumbar degenerative diseases or osteoporotic vertebral fractures underwent LLIF combined with posterior instrumentation. The fusion sites were located within the lumbosacral lesions. LCM was defined as a change of >3 mm in the movement of the radiopaque marker on radiographs. The patients were classified into LCM and non-LCM groups. Medical records and preoperative radiographs were also reviewed. The 1:5 nearest-neighbor propensity score matching technique was used to compare both groups, and radiologic parameters, including preoperative disk height (DH), preoperative sagittal disk angle, disk geometry, height variance (cage height minus DH), and endplate injury, were analyzed to identify the factors influencing LCM incidence.

RESULTS

There were 16 patients (1.6%) with LCM (10 men and 6 women; mean age 70.1 yr). The Cochran-Armitage trend test showed a linear trend toward an increased rating of LCM with an increasing number of fused segments ( P =0.003), and LCM occurred at the terminal cage-inserted disk level in all patients in the LCM group. After propensity-matched analysis, we identified high DH ( P <0.001), large sagittal disk angle ( P =0.009), round-type disk ( P =0.008), and undersized cage selection ( P <0.001) as risk factors for LCM.

CONCLUSION

We identified risk factors for LCM after LLIF combined with posterior instrumentation. To avoid this complication, it is important to select the appropriate cage sizes and enhance posterior fixation for at-risk patients.

Recurrence rate after posterior percutaneous screw fixation without anterior debridement for pyogenic spondylitis compared with conservative treatment: a propensity score-matched analysis

PURPOSE

Previous studies have shown that percutaneous pedicle screw (PPS) posterior fixation without anterior debridement for pyogenic spondylitis can improve patient quality of life compared with conservative treatment. However, data on the risk of recurrence after PPS posterior fixation compared with conservative treatment is lacking. The aim of this study was to compare the recurrence rate of pyogenic spondylitis after PPS posterior fixation without anterior debridement and conservative treatment.

METHODS

The study was conducted under a retrospective cohort design in patients hospitalized for pyogenic spondylitis between January 2016 and December 2020 at 10 affiliated institutions. We used propensity score matching to adjust for confounding factors, including patient demographics, radiographic findings, and isolated microorganisms. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence of pyogenic spondylitis during the follow-up period in the matched cohort.

RESULTS

148 patients (41 in the PPS group and 107 in the conservative group) were included. After propensity score matching, 37 patients were retained in each group. PPS posterior fixation without anterior debridement was not associated with an increased risk of recurrence compared with conservative treatment with orthosis (HR, 0.80; 95% CI, 0.18-3.59; P = 0.77).

CONCLUSIONS

In this multi-center retrospective cohort study of adults hospitalized for pyogenic spondylitis, we found no association in the incidence of recurrence between PPS posterior fixation without anterior debridement and conservative treatment.

Wrong-level spine surgery: A multicenter retrospective study

BACKGROUND

Wrong-level spine surgery is a rare but serious complication of spinal surgery that increases patient harm and legal risks. Although such surgeries have been reported by many spine surgeons, they have not been adequately investigated. Therefore, this study aimed to examine the causes and preventive measures for wrong-level spine surgeries.

METHODS

This study analyzed cases of wrong-level spine surgeries from 10 medical centers. Factors such as age, sex, body mass index, preoperative diagnosis, surgical details, surgeon's experience, anatomical variations, responses, and causes of the wrong-level spine surgeries were studied. The methods used by the surgeons to confirm the surgical level were also surveyed using a questionnaire for each surgical procedure and site.

RESULTS

Eighteen cases (13 men and 5 women; mean age, 61.2 years; mean body mass index, 24.5 kg/m2) of wrong-level spine surgeries were evaluated in the study. Two cases involved emergency surgeries, three involved newly introduced procedures, and five showed anatomical variations. Wrong-level spine surgeries occurred more frequently in patients who underwent posterior thoracic surgery than in those who underwent other techniques (p < 0.01). Twenty-two spinal surgeons described the methods used to confirm the levels preoperatively and intraoperatively. In posterior thoracic laminectomies, half of the surgeons used preoperative markers to confirm the surgical level and did not perform intraoperative fluoroscopy. In posterior thoracic fusion, all surgeons confirmed the level using fluoroscopy preoperatively and intraoperatively.

CONCLUSIONS

Wrong-level spine surgeries occurred more frequently in posterior thoracic surgeries. The thoracic spine lacks the anatomical characteristics observed in the cervical and lumbar spine. The large drop in the spinous process can make it challenging for surgeons to determine the positional relationship between the spinous process and the vertebral body. Moreover, unfamiliarity with the technique and anatomical variations were also risk factors for wrong-level spine surgeries.

Feasibility of total and partial uncinectomy during anterior cervical approach: MRI-based analysis of 176 patients regarding vertebral artery location

PURPOSE

To determine the technical feasibility of uncinate process (UP) resection (uncinectomy) during anterior cervical approach with risk-avoidance of vertebral artery (VA) injury.

METHODS

One hundred and seventy-six magnetic resonance imaging images with cervical spondylosis were evaluated. The diameter between UP and VA (UP-VA distance), the presence of a fat plane, and the VA's anterior-posterior position relative to UP (anterior[A], middle[M], posterior[P]) at C3-4 to C6-7 segments were investigated. Subsequently, easy-to-use classifications were developed according to the feasibility of total and partial uncinectomy. Total uncinectomy: easy (distance: > 2 mm); moderate (distance: ≤ 2 and fat plane: +); advanced (no fat plane). Partial uncinectomy: easy (distance: > 2 mm and P, A, or M position); moderate (distance: ≤ 2; fat plane: + and P position), and advanced (no fat plane and P position).

RESULTS

UP-VA distance of C5-6 on the right side (left/right: 0.41/0.31 mm) was the smallest. The ratio of no fat plane of C5-6 (46.6%/49.4%) was the highest. C5-6 had a high rate of P position (7.4%/8.5%) while C6-7 had a high rate of A position (19.3%/18.2%). More than 90% individuals were classified as easy for partial uncinectomy at any vertebral segment (C3-7), while more than 30% were classified as advanced at C4-7 with the highest rate at C5-6 for total uncinectomy.

CONCLUSION

When performing uncinectomy during the anterior cervical approach, the C5-6 segment may be at the greatest risk of VA injury. Hence, preoperative MR images should be thoroughly evaluated to avoid VA injury.

Blade-Related Vertebral Fracture After Anterior Cervical Discectomy and Fusion with a Zero-Profile Cage: A Case Report

CASE

We present a case of a 79-year-old man with degenerative cervical myelopathy treated with anterior cervical discectomy and fusion (ACDF) using a zero-profile cage. Postoperatively, the patient experienced a rare complication of anchoring blade-related adjacent vertebral fracture leading to construct failure and recurrence of myelopathic symptoms, necessitating revision surgery.

CONCLUSION

This case emphasizes the importance of precision in the surgical technique, specifically in the placement of Caspar pins and anchoring blades. It also underscores the need for a high index of suspicion for potential hardware-related complications in patients presenting with recurring symptoms post-ACDF, contributing to the understanding of such rare complications.

Prognostic impact of respiratory dysfunction in elderly patients with cervical spinal cord injury and/or fractures: a multicenter survey

PURPOSE

To investigate the impact of early post-injury respiratory dysfunction for neurological and ambulatory ability recovery in patients with cervical spinal cord injury (SCI) and/or fractures.

METHODS

We included 1,353 elderly patients with SCI and/or fractures from 78 institutions in Japan. Patients who required early tracheostomy and ventilator management and those who developed respiratory complications were included in the respiratory dysfunction group, which was further classified into mild and severe respiratory groups based on respiratory weaning management. Patient characteristics, laboratory data, neurological impairment scale scores, complications at injury, and surgical treatment were evaluated. We performed a propensity score-matched analysis to compare neurological outcomes and mobility between groups.

RESULTS

Overall, 104 patients (7.8%) had impaired respiratory function. In propensity score-matched analysis, the respiratory dysfunction group had a lower home discharge and ambulation rates (p = 0.018, p = 0.001, respectively), and higher rate of severe paralysis (p < 0.001) at discharge. At the final follow-up, the respiratory dysfunction group had a lower ambulation rate (p = 0.004) and higher rate of severe paralysis (p < 0.001). Twenty-six patients with severe disability required respiratory management for up to 6 months post-injury and died of respiratory complications. The mild and severe respiratory dysfunction groups had a high percentage of severe paraplegic cases with low ambulatory ability; there was no significant difference between them. The severe respiratory dysfunction group tended to have a poorer prognosis.

CONCLUSION

Respiratory dysfunction in elderly patients with SCI and/or cervical fracture in the early post-injury period reflects the severity of the condition and may be a useful prognostic predictor.

Preoperative and Postoperative Factors Affecting Patient Satisfaction with Double-Door Laminoplasty for Cervical Spondylotic Myelopathy

Introduction

Few articles have investigated patient satisfaction with laminoplasty in patients with cervical spondylotic myelopathy (CSM) alone, excluding other diseases, such as ossification of the posterior longitudinal ligament. In this study, we aimed to investigate patient satisfaction after double-door laminoplasty for CSM and determine the preoperative and postoperative factors that affect patient satisfaction.

Methods

We retrospectively reviewed cases of laminoplasty for CSM. We measured sagittal imaging parameters (cervical lordosis [CL], C2-C7 cervical sagittal vertical axis [cSVA], and T1 slope [T1S]), Japanese Orthopaedic Association (JOA) score, and patient-reported outcomes (PROs) such as the neck disability index (NDI) and visual analog scale (VAS) preoperatively, 3 months postoperatively, and 1 year postoperatively. In addition, a multiple regression analysis was performed to investigate factors affecting patient satisfaction.

Results

Ninety patients were included in the analysis. After surgery, CL decreased significantly (p<0.01), whereas cSVA increased significantly (p<0.01). No significant differences were observed in the preoperative and postoperative T1S values (p=0.61). The JOA, NDI, and VAS scores significantly improved postoperatively (p<0.01). The median patient satisfaction was 85 (range, 12-100) at 1 year postoperatively and 80 (range, 25-100) at 3 months postoperatively. In the multiple regression analysis, lower-extremity sensory disorder in the JOA score at 1 year postoperatively (p<0.01) and VAS scores for neck pain preoperatively and 1 year postoperatively (p=0.01 and p<0.01, respectively) were determined as factors affecting patient satisfaction.

Conclusions

Cervical laminoplasty is a useful and satisfactory surgical procedure to restore patient function. However, patients with severe preoperative and postoperative neck pain and those with severe postoperative sensory disorders of the lower extremities may be less satisfied with the procedure. It is important to keep these things in mind when treating patients.

Acute non-traumatic spinal subarachnoid hematomas: A report of five cases and a systematic review of literature

BACKGROUND

There is a lack of evidence on spinal subarachnoid hematomas because of the rarity of their spontaneous development and difficulty in diagnosis. The aim of this study was to identify the characteristics and outcomes of surgically confirmed acute non-traumatic spinal subarachnoid hematomas from a multicenter surgical database and conduct a systematic review of existing literature.

METHODS

Five surgically confirmed cases of acute non-traumatic spinal subarachnoid hematomas were identified from our multicenter database with 22 cases from a systematic review of existing literature.

RESULTS

The mean age of the 27 patients was 59 years. The length of the hematoma was longer than five vertebrae in 70% of the patients, most commonly distributed in the thoracic spine; 63% of all cases were idiopathic, 30% were under anticoagulant therapy, and the remaining 7% presented with coagulation abnormalities. As many as 70% of the patients showed some improvement in neurological symptoms after surgery during a mean follow-up period of 14 months.

CONCLUSIONS

This study elucidated the characteristics of acute non-traumatic spinal subarachnoid hematomas in patients who were surgically confirmed. Most patients were middle-aged, complained of back pain, and had the hematoma located in the thoracic spine. Seventy percent of the patients in this study had some improvement in their neurological status, most likely due to surgical decompression and hematoma evacuation.

Minimally invasive LLIF surgery to decrease the occurrence of adjacent-segment disease compared to conventional open TLIF

PURPOSE

Lateral lumbar interbody fusion with percutaneous pedicle screw fixation (Mis-LLIF) can establish indirect decompression by lifting the vertebra with a large intervertebral cage, which causes less damage to the posterior elements. Thus, Mis-LLIF is expected to reduce the incidence of adjacent segment disease (ASD). The aim of the study was to compare the occurrence of ASD between Mis-LLIF and conventional open transforaminal interbody fusion (TLIF).

METHODS

A total of 156 patients (TLIF group = 88, Mis-LLIF group = 68) who underwent single-level lumbar interbody fusion (L2/3, L3/4, or L4/5) at a single institution between 2003 and 2018 with minimum 2-year follow-up were retrospectively reviewed. The incidence of symptomatic ASD requiring reoperation (S-ASD) and radiological adjacent segment degeneration (R-ASD) 2 years postoperatively were investigated between 51 paired patients from both groups who were propensity score (PS) matched by demographic and baseline clinical data. The effect of characteristics arising from differences in surgical methods between Mis-LLIF and TLIF, such as the amount of distraction of the index fused level (∆H), on S-ASD and R-ASD was also examined.

RESULTS

There were no significant differences in the incidence of S-ASD between the Mis-LLIF and TLIF groups (adjusted OR 1.3; 95% CI 0.41-3.9). There was no significant difference in the incidence of R-ASD between the Mis-LLIF and TLIF groups both at the cranial (adjusted OR 1.0; 95% CI 0.22-4.5) and caudal level (adjusted OR 1.5; 95% CI 0.44-5.3). On the other hand, ∆H was significantly higher in the Mis-LLIF group than in the TLIF group (3.6 mm vs. 1.7 mm, respectively, P < 0.0001), and was extracted as a significant independent risk factor for S-ASD (adjusted HR 2.7; 95% CI 1.1-6.3) and R-ASD at the cranial side (adjusted HR 6.4; 95% CI 1.7-24) in multivariable analysis with PS adjustment.

CONCLUSIONS

The incidence of R-ASD or S-ASD was not significantly reduced in the Mis-LLIF group compared to the TLIF group, with greater ∆H potentially being a contributing factor. Using a thin cage in both TLIF and Mis-LLIF may decrease the occurrence of ASD.

Prognosis of Cervical Diffuse Idiopathic Skeletal Hyperostosis-Related Spine Injuries in Elderly Patients: Analyses of Both Fracture and Spinal Cord Injury Without Fracture

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

The purpose of this study was to compare the prognosis of elderly patients with injuries related to cervical diffuse idiopathic skeletal hyperostosis (cDISH) to matched control for each group, with and without fractures.

METHODS

The current multicenter study was a retrospective analysis of 140 patients aged 65 years or older with cDISH-related cervical spine injuries; 106 fractures and 34 spinal cord injuries without fracture were identified. Propensity score-matched cohorts from 1363 patients without cDISH were generated and compared. Logistic regression analysis was performed to determine the risk of early mortality for patients with cDISH-related injury.

RESULTS

Patients with cDISH-related injuries with fracture did not differ significantly in the incidence of each complication and ambulation or severity of paralysis compared to matched controls. In patients with cDISH-related injury without fracture, those who were nonambulatory at discharge comprised 55% vs 34% of controls, indicating significantly poorer ambulation in those with cDISH-related injuries (P = .023). There was no significant difference in the incidence of complications and ambulation or paralysis severity at 6 months as compared with controls. Fourteen patients died within 3 months. Logistic regression analysis identified complete paralysis (odds ratio [OR] 36.99) and age (OR 1.24) as significant risk factors for mortality.

CONCLUSIONS

The current study showed no significant differences in the incidence of complications, ambulation outcomes between patients with cDISH-related injury with fracture and matched controls, and that the ambulation at discharge for patients with cDISH-related injury without fractures were significantly inferior to those of matched controls.

Incidence of Surgical Site Infection Following Lateral Lumbar Interbody Fusion Compared With Posterior/Transforaminal Lumbar Interbody Fusion: A Propensity Score-Weighted Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The objective of this study was to compare the incidence of surgical site infection (SSI) after lateral lumbar interbody fusion (LLIF) and posterior/transforaminal lumbar interbody fusion ( P /TLIF).

SUMMARY OF BACKGROUND DATA

Previous studies have shown that LLIF can improve neurological symptoms to a comparable degree to P /TLIF. However, data on the risk of SSI after LLIF is lacking compared with P /TLIF.

MATERIALS AND METHODS

The study was conducted under a retrospective cohort design in patients undergoing LLIF or P /TLIF for lumbar degenerative diseases between 2013 and 2020 using a hospital administrative database. We used propensity score overlap weighting to adjust for confounding factors including age, sex, body mass index, comorbidities, number of fusion levels, hospital size, and surgery year. We estimated weighted odds ratios (ORs) and 95% CIs for SSI within 30 days postoperatively.

RESULTS

We compared the risk of SSI between 2874 patients who underwent LLIF and 24,245 patients who received P/TLIF Patients who had received LLIF were at significantly less risk of experiencing an SSI compared with those receiving P/TLIF (0.7% vs. 1.2%; weighted OR: 0.57; 95% CI: 0.36 -0.92; P=0.02). As a secondary outcome, patients who had received LLIF had less risk of transfusion (7.8% vs. 11.8%; weighted OR: 0.63; 95% CI:0.54 -0.73; P <0.001).

CONCLUSIONS

In this large retrospective cohort study of adults undergoing lumbar interbody fusion, LLIF was associated with a significantly lower risk of SSI than P /TLIF. The small, but significantly, decreased risk of SSI associated with LLIF may inform decisions regarding the technical approach for lumbar interbody fusion.

Risk of further surgery after decompression in patients with diffuse idiopathic skeletal hyperostosis extending to the lumbar segments: focus on the number of residual lumbar/lumbosacral and sacroiliac mobile segments

PURPOSE

Patients with diffuse idiopathic skeletal hyperostosis (DISH) that extends to the lumbar segments (L-DISH) have a high risk of further surgery after lumbar decompression. However, few studies have focused on the ankylosis status of the residual caudal segments, including the sacroiliac joint (SIJ). We hypothesized that patients with more ankylosed segments beside the operated level, including the SIJ, would be at a higher risk of further surgery.

METHODS

A total of 79 patients with L-DISH who underwent decompression surgery for lumbar stenosis at a single academic institution between 2007 and 2021 were enrolled. The baseline demographics and radiological findings by CT imaging focusing on the ankylosing condition of the residual lumbar segments and SIJ were collected. Cox proportional hazard analysis was conducted to investigate the risk factors for further surgery after lumbar decompression.

RESULTS

The rate of further surgery was 37.9% during an average of 48.8 months of follow-up. Cox proportional hazard analysis demonstrated that the presence of fewer than three segments of non-operated mobile caudal segments was an independent predictor for further surgery (including both the same and adjacent levels) after lumbar decompression (adjusted hazard ratio 2.53, 95%CI [1.12-5.70]).

CONCLUSIONS

L-DISH patients with fewer than three mobile caudal segments besides index decompression levels are at a high risk of further surgery. Ankylosis status of the residual lumbar segments and SIJ should be thoroughly evaluated using CT during preoperative planning.

Predictors of the Need for Surgery in Cervical Ossification of the Posterior Longitudinal Ligament: A Retrospective Cohort Longitudinal Study Using a Claims-based Database

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to determine predictors associated with the needfor cervical ossification of the posterior longitudinal ligament (cOPLL) surgery amongindividuals with cOPLL.

SUMMARY OF BACKGROUND DATA

cOPLL is a spinal disorder caused by ectopic ossification of the posterior longitudinal ligament. However, factors associated with a higher rate of surgery to treat the neurological symptoms of cOPLL are poorly understood.

MATERIALS AND METHODS

This retrospective population-based cohort study using a commercial administrative claims database from JMDC Inc. (Tokyo, Japan) enrolled patients newly diagnosed with cOPLL from April 2005 to October 2020 and followed to April 2021. A total of 1506 cOPLL patients aged 18 years or older with no history of cervical spine surgery and with a record of metabolic profiles obtained at general health checkups were included. Cox proportional hazards regression models identified patient characteristics and comorbidities associated with cOPLL surgery.

RESULTS

Of 1506 patients with cOPLL with a median of 1.8 years of follow-up after initial cOPLL diagnosis, 439 (29.2%) received cOPLL surgery. The 1-year cumulative incidence (95% CI) was 26.0% (23.7-28.2). In multivariable Cox proportional regression analysis, male (hazard ratio: 1.68; 95% CI: 1.26-2.24; P < 0.001) and obesity (body mass index: ≥25) (hazard ratio: 1.45; 95% CI: 1.10-1.89; P = 0.007) were associated with an increased risk of cOPLL surgery.

CONCLUSIONS

In this large claims-based study of adults newly diagnosed with cOPLL, males and obesity were associated with a higher risk of cOPLL surgery. These findings may help clinicians to predict the future course of cOPLL in patients, although further research is needed to elucidate the biological role of these progression-associated factors.

Worsening ambulation in elderly patients with cervical odontoid fractures: A nationwide multicenter study in Japan

BACKGROUND

Despite the increasing prevalence of cervical odontoid fractures in older adults, the treatment strategy is controversial. The objectives of the current study are to investigate the prognosis and complications of cervical odontoid fractures in elderly patients and to identify factors associated with worsening of ambulation after 6 months.

METHODS

This multicenter, retrospective study included 167 patients aged 65 years or older with odontoid fractures. Patient demographic and treatment data were investigated and compared according to the treatment strategy. To determine associations with worsening ambulation after 6 months, we focused on the treatment strategies (nonsurgical treatment [collar immobilization or halo vest], conversion to surgery, or initial surgery) and patients' background.

RESULTS

Patients who received nonsurgical treatment were significantly older, and patients who underwent surgery had more Anderson-D'Alonzo type 2 fractures. Of the patients initially treated nonsurgically, 26% later underwent surgery. Numbers of complications, including death, and degrees of ambulation after 6 months did not differ significantly among treatment strategies. Patients who had worsened ambulation after 6 months were significantly more likely to be older than 80 years, to have needed assistance with walking before injury, and to have cerebrovascular disease. Multivariable analysis showed that a score of ≥2 on the 5-item modified frailty index (mFI-5) was significantly associated with worsening ambulation.

CONCLUSIONS

Preinjury mFI-5 scores of ≥2 were significantly associated with worsening ambulation 6 months after treatment of cervical odontoid fractures in older adults.

CT-based analysis of sagittal and coronal lumbar endplate morphology: multivariate analysis of factors associated with endplate depth

PURPOSE

Lumbar endplate morphology varies in individuals; thus, custom-made implants are sometimes more useful than standardized implants. This study aimed to analyze endplate morphology and factors associated with endplate depth using computed tomography (CT) in a non-symptomatic population.

METHODS

In total, 118 lumbar CT images of non-symptomatic individuals without severe degenerative change (aged 20-79 years) were retrospectively reviewed. The following radiographic parameters were measured in each lumbar vertebral segment (T12-S1) to determine endplate depth: superior/inferior endplate depth in the midsagittal and midcoronal planes, disk angle, and height. The relationship between baseline demographics (age, sex, body mass index [BMI], Hounsfield unit of the L1 vertebral body, and pelvic incidence [PI]) and endplate depth was analyzed.

RESULTS

Toward the caudal level, the superior endplate depth increased, sagittal inferior depth decreased, and coronal inferior depth increased. Multivariate analysis revealed that endplate depth was significantly associated with age (p < 0.001), while inferior endplate depth was associated with PI (p = 0.01). Superior endplate depth was associated with female sex (sagittal: p = 0.005, coronal: p = 0.002). Endplate depth, except for the inferior coronal region, was associated with low BMI (sagittal superior: p = 0.005; coronal superior and sagittal inferior: p = 0.02).

CONCLUSION

Endplate depths tend to be larger toward the caudal level, particularly in the superior endplate. Surgeons should thoroughly evaluate the preoperative CT image because various endplate morphologies require attention to cage shape when performing lumbar interbody fusion, especially in patients who are older, are female, have low BMI, and have large PI.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

The Efficacy of CT Temporal Subtraction Images for Fibrodysplasia Ossificans Progressiva

Purpose: To evaluate the usefulness of CT temporal subtraction (TS) images for detecting emerging or growing ectopic bone lesions in fibrodysplasia ossificans progressiva (FOP). Materials and Methods: Four patients with FOP were retrospectively included in this study. TS images were produced by subtracting previously registered CT images from the current images. Two residents and two board-certified radiologists independently interpreted a pair of current and previous CT images for each subject with or without TS images. Changes in the visibility of the lesion, the usefulness of TS images for lesions with TS images, and the interpreter’s confidence level in their interpretation of each scan were assessed on a semiquantitative 5-point scale (0–4). The Wilcoxon signed-rank test was used to compare the evaluated scores between datasets with and without TS images. Results: The number of growing lesions tended to be larger than that of the emerging lesions in all cases. A higher sensitivity was found in residents and radiologists using TS compared to those not using TS. For all residents and radiologists, the dataset with TS tended to have more false-positive scans than the dataset without TS. All the interpreters recognized TS as useful, and confidence levels when using TS tended to be lower or the same as when not using TS for two residents and one radiologist. Conclusions: TS improved the sensitivity of all interpreters in detecting emerging or growing ectopic bone lesions in patients with FOP. TS could be applied further, including the areas of systematic bone disease.

Low hounsfield unit values at sagittal section on computed tomography predicts vertebral fracture following short spinal fusion

BACKGROUND

Preoperative identification of osteoporosis during spine surgery is of critical importance. Additionally, the Hounsfield units (HU) measured using computed tomography (CT) have gained considerable attention. This study aimed to propose a more accurate and convenient screening method for predicting vertebral fractures after spinal fusion in elderly patients by analyzing the HU value of different range of interests of thoracolumbar spine.

METHODS

Our sample pool for analysis consisted of 137 elderly female patients aged >70 years who underwent one- or two-level spinal fusion surgery with a diagnosis of adult degenerative lumbar disease. The HU values of the anterior 1/3 of the vertebral bodies based on sagittal plane and those of vertebral bodies based on axial plane at T11-L5 were measured using the perioperative CT. The incidence of postoperative vertebral fractures with respect to the HU value was investigated.

RESULTS

Vertebral fractures were identified in 16 patients during the mean follow-up period of 3.8 years. While no significant association was found between HU value of L1 vertebral body or minimum HU value from axial plane and the incidence of the postoperative vertebral fracture, the minimum vertebral HU value of the anterior 1/3 of vertebral body from sagittal plane was associated with the incidence of the postoperative vertebral fracture. Patients with a minimum anterior 1/3 vertebral HU value of <80 had a higher incidence of postoperative vertebral fractures. The adjacent vertebral fractures occurred at the level of the vertebra with the lowest HU value, with a high probability. The existence of the vertebra with a minimum HU value of <80 within two levels of upper instrumented vertebrae was a risk factor for adjacent vertebral fracture.

CONCLUSION

HU measurement of the anterior 1/3 of vertebral body predicts the risk of vertebral fracture after short spinal fusion surgery.

Right transmanubrial approach to the cervicothoracic spine with venous reconstruction

The transmanubrial approach first reported by Grunenwald in 1997 is well-known for superior sulcus lung malignancies involving the thoracic inlet. Because an anterior approach to levels below Th2 is difficult without removing the manubrium, we used the transmanubrial approach for anterior cervicothoracic corpectomy and fusion (C7-Th3) in a patient with bilateral lower extremity paralysis due to ossification of the posterior longitudinal ligament in the cervicothoracic spine. To ensure more working space in the deep surgical field, which was hindered by a prior cardiac operation with median sternotomy and a goiter protruding into the upper mediastinal region, the right brachiocephalic vein was temporarily divided and subsequently reconstructed using bovine pericardium.

Association of two-staged surgery with systemic perioperative complications in lateral lumbar interbody fusion for adult spinal deformity: a propensity score-weighted study

PURPOSE

Adult spinal deformity (ASD) surgery carries a higher risk of perioperative systemic complications. However, evidence for the effect of planned two-staged surgery on the incidence of perioperative systemic complications is scarce. Here, we evaluated the effect of two-staged surgery on perioperative complications following ASD surgery using lateral lumbar interbody fusion (LLIF).

METHODS

The study was conducted under a retrospective multi-center cohort design. Data on 293 consecutive ASD patients (107 in the two-staged group and 186 in the one-day group) receiving corrective surgery using LLIF between 2012 and 2021 were collected. Clinical outcomes included occurrence of perioperative systemic complications, reoperation, and intraoperative complications, operation time, intraoperative blood loss, transfusion, and length of hospital stay. The analysis was conducted using propensity score (PS)-stabilized inverse probability treatment weighting to adjust for confounding factors. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated in a PS-weighted cohort.

RESULTS

In this cohort, 19 (18.4%) patients in the two-staged group and 43 (23.1%) patients in the one-day group experienced any systemic perioperative complication within 30 days following ASD surgery. In the PS-weighted cohort, compared with the patients undergoing one-day surgery, no association with the risk of systemic perioperative complications was seen in patients undergoing two-staged surgery (PS-weighted OR 0.78, 95% CI 0.37-1.63; p = 0.51).

CONCLUSION

Our study suggested that two-staged surgery was not associated with risk for perioperative systemic complications following ASD surgery using LLIF.

Effects of Dementia on Outcomes after Cervical Spine Injuries in Elderly Patients: Evaluation of 1512 Cases in a Nationwide Multicenter Study in Japan

We aimed to retrospectively investigate the demographic characteristics and short-term outcomes of traumatic cervical spine injuries in patients with dementia. We enrolled 1512 patients aged ≥ 65 years with traumatic cervical injuries registered in a multicenter study database. Patients were divided into two groups according to the presence of dementia, and 95 patients (6.3%) had dementia. Univariate analysis revealed that the dementia group comprised patients who were older and predominantly female and had lower body mass index, higher modified 5-item frailty index (mFI-5), lower pre-injury activities of daily living (ADLs), and a larger number of comorbidities than patients without dementia. Furthermore, 61 patient pairs were selected through propensity score matching with adjustments for age, sex, pre-injury ADLs, American Spinal Injury Association Impairment Scale score at the time of injury, and the administration of surgical treatment. In the univariate analysis of the matched groups, patients with dementia had significantly lower ADLs at 6 months and a higher incidence of dysphagia up to 6 months than patients without dementia. Kaplan-Meier analysis revealed that patients with dementia had a higher mortality than those without dementia until the last follow-up. Dementia was associated with poor ADLs and higher mortality rates after traumatic cervical spine injuries in elderly patients.

Risk Factors for Early Mortality in Older Patients with Traumatic Cervical Spine Injuries-A Multicenter Retrospective Study of 1512 Cases

For older patients with decreased reserve function, traumatic cervical spine injuries frequently lead to early mortality. However, the prognostic factors for early mortality remain unclear. This study included patients aged ≥65 years and hospitalized for treatment of traumatic cervical spine injuries in 78 hospitals between 2010 and 2020. Early mortality was defined as death within 90 days after injury. We evaluated the relationship between early mortality and the following factors: age, sex, body mass index, history of drinking and smoking, injury mechanisms, presence of a cervical spine fracture and dislocation, cervical ossification of the posterior longitudinal ligament, diffuse idiopathic skeletal hyperostosis, American Spinal Injury Association Impairment Scale, concomitant injury, pre-existing comorbidities, steroid administration, and treatment plan. Overall, 1512 patients (mean age, 75.8 ± 6.9 years) were included in the study. The early mortality rate was 4.0%. Multivariate analysis identified older age (OR = 1.1, p < 0.001), male sex (OR = 3.7, p = 0.009), cervical spine fracture (OR = 4.2, p < 0.001), complete motor paralysis (OR = 8.4, p < 0.001), and chronic kidney disease (OR = 5.3, p < 0.001) as risk factors for early mortality. Older age, male sex, cervical spine fracture, complete motor paralysis, and chronic kidney disease are prognostic factors for early mortality in older patients with traumatic cervical spine injuries.

Epidemiology of Cervical Fracture/Cervical Spinal Cord Injury and Changes in Surgical Treatment Modalities in Elderly Individuals During a 10-year Period: A Nationwide Multicenter Study in Japan

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVES

To investigate changes over a 10-years period in the profile of cervical spine and spinal cord injuries among the elderly in Japan.

METHODS

The current multicenter study was a retrospective analysis of inpatients aged ≥65 years, suffering cervical fracture (CF) and/or cervical spinal cord injury (CSCI). We analyzed 1413 patients' epidemiology (from 2010 to 2019). Moreover, 727 patients who underwent surgical treatment were analyzed in 2 groups: the early (2010-2014) and late period (2015-2019).

RESULTS

Both the number of patients and number of surgical patients showed a significant increasing trend (P < .001), while the mean age, the distribution of injury levels and paralysis severity, and the proportion of surgical indications remained the same. The number of surgical patients doubled from 228 to 499 from the early to late periods. Posterior surgery was the most common approach (90.4%), instrumentation surgery with screws increased significantly, and the range of fusion was significantly longer in the late period (2.1 vs 2.7 levels, P = .001). Significantly worsening neurological symptoms were recorded in the late period (1.3% vs 5.8%, P = .006), with C5 palsy being the major one. Otherwise, perioperative, major, and other complications, including mortality, did not differ significantly in incidence.

CONCLUSIONS

Both the number of elderly CF and/or CSCI patients and number of patients undergoing surgery increased dramatically over the decade without any change in profile. Instrumentation surgeries with screws increased, without an increase in systemic complications.

Reoperation Rates of Microendoscopic Discectomy Compared With Conventional Open Lumbar Discectomy: A Large-database Study

BACKGROUND

Microendoscopic discectomy for lumbar disc herniation has been shown to be as effective as traditional microdiscectomy or open discectomy in terms of clinical outcomes such as pain relief, and it is less invasive. Nevertheless, the reoperation rate for microendoscopic discectomy compared with microdiscectomy or open discectomy remains unclear, possibly due to difficulties in conducting follow-up of sufficient duration and in obtaining information about reoperation in other facilities.

QUESTIONS/PURPOSES

(1) What is the rate of reoperation after microendoscopic discectomy for primary lumbar disc herniation on a large scale at a median of 4 years postoperatively? (2) Is there any difference in revision rate at a median of 4 years and within 90 days postoperatively based on surgical method?

METHODS

We conducted a retrospective, comparative study of adult patients who underwent microendoscopic discectomy or microdiscectomy or open discectomy for lumbar disc herniation from April 2008 to October 2017 and who were followed until October 2020 using a commercially available administrative claims database from JMDC Inc. This claims-based database provided information on individual patients collected across multiple hospitals, which improved the accuracy of postoperative reoperation rates. We included 3961 patients who received microendoscopic discectomy or microdiscectomy or open discectomy between April 2008 and October 2017 in the JMDC claims database. After applying exclusion criteria, 50% (1968 of 3961) of patients were eligible for this study. Propensity score-weighted analyses were conducted in 646 patients in the microendoscopic discectomy group and in 1322 in the microdiscectomy or open discectomy group, with a median (IQR) of 4 years (3 to 6) of follow-up in both groups. Mean patient age was 42 ± 12 years in the microendoscopic discectomy group and 43 ± 12 years in the microdiscectomy or open discectomy group. Males accounted for 78% (505 of 646) of patients in the microendoscopic discectomy group and 79% (1050 of 1322) of patients in microdiscectomy or open discectomy group. The proportion of patients with diabetes mellitus in the microendoscopic discectomy group (10% [64 of 646]) was less than in the microdiscectomy or open discectomy group (15% [195 of 1322]). The primary outcome was Kaplan-Meier survivorship free from any type of additional lumbar spine surgery at a median of 4 years after the index surgery. The secondary outcome was survival probability using the Kaplan-Meier method with endpoints of any type of reoperation within 90 days after the index surgery. To determine which procedure had the higher revision rate, we conducted propensity score overlap weighting analysis, which controlled for potential confounding variables such as age, sex, comorbidities, and type of hospital as well as Cox proportional hazard models to estimate HRs and 95% confidence intervals (CIs).

RESULTS

The 5-year cumulative reoperation rate was 12% (95% CI 9% to 15%) in the microendoscopic discectomy group and 7% (95% CI 6% to 9%) in the microdiscectomy or open discectomy group. After controlling for potentially confounding variables like age, sex, and diabetes mellitus, the microendoscopic discectomy group had a higher reoperation risk than the microdiscectomy or open discectomy group (weighted HR 1.57 [95% CI 1.14 to 2.16]; p = 0.004). Within 90 days of the index surgery, after controlling for potentially confounding variables like age, sex, and diabetes mellitus, we found no difference between the microendoscopic discectomy group and microdiscectomy or open discectomy group in terms of risk of reoperation (weighted HR 1.38 [95% CI 0.68 to 2.79]; p = 0.38).

CONCLUSION

Given the higher reoperation risk with microendoscopic discectomy compared with microdiscectomy or open discectomy at a median of 4 years of follow-up, surgeons should select microdiscectomy or open discectomy, despite the current popularity of microendoscopic discectomy. The revision risk of microendoscopic discectomy compared with microdiscectomy or open discectomy in the long term remains unclear. Future large, prospective, multicenter cohort studies with long-term follow-up are needed to confirm the association between microendoscopic discectomy and risk of reoperation.

LEVEL OF EVIDENCE

Level Ⅲ, therapeutic study.

Clinical Features and Surgical Outcomes of Lower Lumbar Osteoporotic Vertebral Collapse with Symptomatic Stenosis: A Surgical Strategy from a Multicenter Case Series

STUDY DESIGN

A retrospective multicenter case series was conducted.

PURPOSE

This study was designed to investigate the clinical features and surgical outcomes of lower lumbar osteoporotic vertebral collapse (LL-OVC) with symptomatic stenosis based on various surgical procedures and classify them using the newly developed collapse severity criteria.

OVERVIEW OF LITERATURE

The surgical outcomes of LL-OVC with symptomatic stenosis remain unclear.

METHODS

We investigated patients who underwent surgical intervention for LL-OVC (L3, L4, and/or L5) with symptomatic foraminal and/or central stenosis from eight spine centers. Only patients with a minimum follow-up duration of 1 year were included. We developed new criteria to grade vertebral collapse severity (grade 1, 0%-25%; grade 2, 25%-50%; grade 3, 50%-75%; and grade 4, 75%-100%). The clinical features and outcomes were compared based on the collapse grade and surgical procedures performed (i.e., decompression alone, posterior lateral fusion [PLF], lateral interbody fusion [LIF], posterior/transforaminal interbody fusion [PLIF/TLIF], or vertebral column resection [VCR]).

RESULTS

In this study, 59 patients (average age, 77.4 years) were included. The average follow-up period was 24.6 months. The clinical outcome score (Japanese Orthopaedic Association score) was more favorable in the LIF and PLIF/TLIF groups than in the decompression alone, PLF, and VCR groups. The use of VCR was associated with a high rate of revision surgery (57.1%). No significant difference in clinical outcomes was observed between the collapse grades; however, grade 4 collapse was associated with a high rate of revision surgery (40.0%).

CONCLUSIONS

When treating LL-OVC, appropriate instrumented reconstruction with rigid intervertebral stability is necessary. According to our newly developed criteria, LIF may be a surgical option for any collapse grade. The use of VCR for grade 4 collapse is associated with a high rate of revision.

Multicenter Prospective Study of Lateral Lumbar Interbody Fusions Using Bioactive Porous Titanium Spacers without Bone Grafts

STUDY DESIGN

Prospective multicenter clinical study.

PURPOSE

To evaluate the efficacy of bioactive surface treatment for porous titanium spacers without bone graft for lateral lumbar interbody fusion (LLIF) through clinical and radiological examinations.

OVERVIEW OF LITERATURE

LLIF is a minimally invasive spinal fusion procedure. To achieve bony union, a substantial volume of grafted bone is typically packed into the cage; however, this is related to donor site morbidities-one of the disadvantages of LLIF.

METHODS

For this prospective multicenter study, 40 patients were followed up through radiologic and clinical examinations for at least 1 year postoperatively. All surgical procedures were either single- or double-level LLIF using bioactive porous titanium spacers without bone grafts.

RESULTS

Four patients were excluded from the study owing to aggravation from other comorbidities. Another 36 patients, including 26 and 10 with single- and double-level LLIFs, respectively, participated in the follow-up. The mean age at the time of surgery was 63.7 years. The mean operating time was 50.5 minutes per level. The mean estimated intraoperative blood loss was 11.6 mL per level. Clinical scores improved in all cases and were maintained throughout the follow-up period. The intervertebral bony union rates were 67.4% and 84.8% at 6 and 12 months, respectively. Endplate cyst signs were observed in 13.0% and 8.7% of patients at 6 and 12 months, respectively. Fused segmental angles were maintained throughout the follow-up period, indicating no cage subsidence.

CONCLUSIONS

Single- and double-level LLIFs using bioactive porous titanium spacers without bone grafts were found to be minimally invasive, resulting in clinical and imaging results comparable with conventional procedures. Therefore, this type of implant may be an option for minimally invasive spinal fusion surgery.

Residual anterior cord compression after laminoplasty for cervical spondylotic myelopathy: evaluation of risk factors according to the most severely stenotic vertebral segment

OBJECTIVE

Residual anterior spinal cord compression (RASCC) after cervical laminoplasty, which has been confirmed on postoperative MRI, is reportedly associated with poor clinical outcomes. To date, only a few studies have described the risk factors associated with RASCC. The aim of this study was to identify the factors that can predict the occurrence of RASCC after laminoplasty for cervical spondylotic myelopathy (CSM), focusing on the location of the most stenotic segment.

METHODS

In this retrospective, single-center study, 120 patients who underwent C3-7 laminoplasty for multilevel CSM were included. Different techniques were used for C3 decompression, i.e., partial (dome-laminotomy) or complete (laminoplasty/laminectomy) decompression. RASCC was diagnosed using MRI conducted 3 weeks postoperatively. The patients were divided into two groups according to the segment with the most severe stenosis (Seg-MSS; C3-4 vs C4-7). Demographics, radiological data, and C3 decompression technique were compared between the two groups. Furthermore, intergroup comparisons were performed based on Seg-MSS. A logistic regression model was constructed to identify the factors predicting RASCC after patient stratification according to Seg-MSS.

RESULTS

Forty patients (33.3%) had RASCC. The patients with Seg-MSS at C3-4 (51.3%) had a significantly higher incidence of RASCC (p = 0.003) than those with Seg-MSS at C4-7 (24.7%). Logistic regression analysis showed that in patients with Seg-MSS at C3-4, C3 partial decompression demonstrated a greater association with RASCC as opposed to complete decompression. Conversely, in patients with Seg-MSS at C4-7, kyphotic segmental lordotic angle was associated with an increased risk of RASCC.

CONCLUSIONS

The risk factors for RASCC differed depending on the location of the most stenotic segment (C3-4 vs C4-7). If there is segmental kyphosis at the most stenotic segment at C4-7, anterior decompression and fusion should be considered. If C3-4 is the most stenotic segment, anterior surgery is also recommended, but alternatively, one can choose laminoplasty with complete C3 laminectomy and resection of the C2-3 ligamentum flavum.

Comparative Study of Circumferential Decompression and Posterior Decompression in Palliative Surgery for Metastatic Thoracic Spinal Tumors

STUDY DESIGN

This was a case-control study.

OBJECTIVE

The present study aimed to evaluate the significance of circumferential tumor resection around the spinal cord in palliative decompression surgery for patients with metastatic spinal cord compression (MSCC) in the thoracic spine.

SUMMARY OF BACKGROUND DATA

Although the benefits of palliative surgery for MSCC are well known, the significance of circumferential tumor resection with cord compression has not yet been clarified.

MATERIALS AND METHODS

We retrospectively compared the outcomes of 45 and 34 patients with incomplete paralysis of modified Frankel grade B-D caused by MSCC with anterior cord compression (epidural spinal cord compression grade ≥2) treated at 2 different university hospitals (H1 and H2, respectively). All patients in H1 hospital underwent posterior decompression only, while all patients in H2 hospital underwent full circumferential decompression. We analyzed factors that affect the postoperative ambulatory status. evaluated by the modified Frankel classification.

RESULTS

No significant differences were observed in the epidural spinal cord compression grade, spinal instability neoplastic score, new Katagiri score, revised Tokuhashi score, or postoperative survival between patients in H1 and H2 hospitals. A multivariable logistic regression analysis identified preoperative radiotherapy [odds ratio (OR): 0.23, 95% confidential interval (CI): 0.056-0.94] as a negative risk factor and postoperative chemotherapy (OR: 5.9, 95% CI: 1.3-27.0) as a positive risk factor for an improved ambulatory status. Five and 6 patients in H1 and H2 hospitals, respectively, showed deterioration in the ambulatory status. An older age (OR: 1.1, 95% CI: 1.0-1.2) and preoperative radiotherapy (OR: 10.3, 95% CI: 1.9-55.4) were extracted as significant independent risk factors for deterioration in the ambulatory status. Circumferential decompression did not improve the clinical results of patients regardless of the degree of paralysis.

CONCLUSIONS

Preoperative radiotherapy interfered with the recovery of paralysis, and postoperative chemotherapy improved the ambulatory status. Clinical outcomes did not significantly differ between total circumferential decompression and posterior decompression, although further validation in a small number of cases is needed, such as patients with Frankel grade D.

Factors Affecting the Waiting Time from Injury to Surgery in Elderly Patients with a Cervical Spine Injury: A Japanese Multicenter Survey

OBJECTIVE

The management of cervical spine injuries in the elderly is often complicated by the presence of multiple medical comorbidities, and it is not uncommon for preoperative testing to reveal other conditions that require the postponement of surgery. However, the factors that affect the waiting time from injury to surgery have not been clarified. The purpose of this multicenter database study was to analyze the clinical features and identify the factors affecting the number of days waited between injury and surgery in elderly patients with a cervical spine injury.

METHODS

We retrospectively reviewed the case histories of 1512 Japanese patients with a cervical spinal injury, who were seen at 33 institutions. After excluding patients who were not initially receiving a surgery for cervical spinal injury, 694 patients were ultimately analyzed. Based on a multivariate mixed model, we determined the factors related to the number of days from injury to surgery.

RESULTS

The mean time from injury to surgery was 12.3 days. Multivariate analysis revealed delays of 10.7 days for a renal disorder, 7.3 days for anticoagulant use, and 15.2 days for non-surgical thoracolumbar fracture as factors prolonging wait time. In contrast, a C3 or lower spine injury was significantly associated with a shortening of 9.5 days to surgery.

CONCLUSIONS

This multicenter database study identified several factors influencing the time between injury and cervical spine surgery in elderly patients. While renal impairment, anticoagulant use, and non-surgical thoracolumbar fracture may increase the number of days to surgery, trauma to C3 or lower may expedite surgical treatment.

Neurological severity evaluation using magnetic resonance imaging in acute spontaneous spinal epidural haematomas

PURPOSE

This study aimed to elucidate the severity of neurological deficits in a large series of patients with acute spontaneous spinal epidural haematoma (SSEH) using magnetic resonance imaging (MRI).

METHODS

We included 57 patients treated for acute SSEH at 11 institutions and retrospectively analysed their demographic and MRI data upon admission. We investigated MRI findings, such as the haematoma length and canal occupation ratio (COR). The neurological severity of SSEH was assessed based on the American Spinal Injury Association score on admission.

RESULTS

Of the 57 patients, 35 (61%) presented with severe paralysis. The MRI analysis showed that SSEH was often located in the cervical spine, dorsal to the spinal cord, and spread over more than three vertebrae. No differences in age, sex, and aetiology were found between patients with and without severe paralysis. The hypo-intensity layer encircling the haematoma, intra-haematoma heterogeneity, and increased CORs were observed more frequently in the severe paralysis group. Furthermore, pathological examination of a dissected haematoma from one patient with a hypo-intensity layer revealed a collagen layer around the haematoma, and patients with intra-haematoma heterogeneity were more likely to have a bleeding predisposition.

CONCLUSIONS

In this large series of patients with SSEH, we identified some MRI features associated with severe paralysis, such as the hypo-intensity layer, intra-haematoma heterogeneity, and increased COR. Accordingly, patients with these MRI characteristics should be considered for early surgical intervention.

A multicenter study of 1-year mortality and walking capacity after spinal fusion surgery for cervical fracture in elderly patients

Background

The 1-year mortality and functional prognoses of patients who received surgery for cervical trauma in the elderly remains unclear. The aim of this study is to investigate the rates of, and factors associated with mortality and the deterioration in walking capacity occurring 1 year after spinal fusion surgery for cervical fractures in patients 65 years of age or older.

Methods

Three hundred thirteen patients aged 65 years or more with a traumatic cervical fracture who received spinal fusion surgery were enrolled. The patients were divided into a survival group and a mortality group, or a maintained walking capacity group and a deteriorated walking capacity group. We compared patients’ backgrounds, trauma, and surgical parameters between the two groups. To identify factors associated with mortality or a deteriorated walking capacity 1 year postoperatively, a multivariate logistic regression analysis was conducted.

Results

One year postoperatively, the rate of mortality was 8%. A higher Charlson comorbidity index (CCI) score, a more severe the American Spinal Cord Injury Association impairment scale (AIS), and longer surgical time were identified as independent factors associated with an increase in 1-year mortality. The rate of deterioration in walking capacity between pre-trauma and 1 year postoperatively was 33%. A more severe AIS, lower albumin (Alb) and hemoglobin (Hb) values, and a larger number of fused segments were identified as independent factors associated with the increased risk of deteriorated walking capacity 1 year postoperatively.

Conclusions

The 1-year rate of mortality after spinal fusion surgery for cervical fracture in patients 65 years of age or older was 8%, and its associated factors were a higher CCI score, a more severe AIS, and a longer surgical time. The rate of deterioration in walking capacity was 33%, and its associated factors were a more severe AIS, lower Alb, lower Hb values, and a larger number of fused segments.

The Impact of Spinopelvic Parameters on Hip Degeneration After Spinal Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aimed to investigate the effects of spinopelvic alignment parameters after spinal fusion on the rate of joint space narrowing in nonarthritic hips.

SUMMARY OF BACKGROUND DATA

Spinal fusion affects the forces on the adjacent hip joint. Therefore, hip joint narrowing may be increased after spinal fusion surgery. However, the relationship between spinal alignment and hip degeneration remains unclarified.

METHODS

We retrospectively reviewed data from patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with hip osteoarthritis (Kellgren-Lawrence grade ≥II) or hip dysplasia were excluded. The rate of hip joint space narrowing after spinal fusion was measured in 191 patients (382 hips). We assessed the effects of the following spinopelvic alignment parameters on the joint narrowing rate: pelvic tilt, sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL, sagittal vertical axis, and distance between the C7 plumb line, and the central sacral vertical line (C7-CSVL).

RESULTS

The hip joint narrowing rate was greater when four or more levels were fused compared with single-level fusion. After adjusting for the effects of patient-related factors, the alignment parameters significantly associated with the hip joint narrowing rate were the PI ( P = 0.0002), SS ( P = 0.047), and PI-LL ( P = 0.0022). A subgroup analysis of patients who underwent long fusion (four or more levels combined with iliac screws) also indicated that the PI ( P = 0.013), SS ( P = 0.0054), and PI-LL ( P = 0.046) were associated with the hip joint narrowing rate.

CONCLUSION

The PI, SS, and PI-LL were associated with the progression of hip joint narrowing after spinal fusion, especially after fusion of four or more levels. Surgeons need to be aware of the risk of increased hip joint narrowing in patients with a large PI, SS, and PI-LL after fusion surgery.

Risk Factors for Proximal Junctional Kyphosis in Fusions from the Sacrum to L1 or L2 for Adult Spinal Deformity

Introduction

Several targets have been proposed to achieve satisfactory alignment and favorable outcomes in adult spinal deformity surgery. Stopping the upper instrumented vertebra (UIV) at the thoracolumbar junction levels, especially between T11 and L1, is considered a high-risk factor for the development of proximal junctional kyphosis (PJK). Nevertheless, it is unknown in which patients the results of surgery are satisfactory when L1 or L2 is set as UIV with lumbosacral fixation. This study aimed to identify the risk factors for PJK in patients with lumbosacral fixation with L1 or L2 as UIV.

Methods

From January 2011 to December 2019, 21 consecutive patients who underwent lumbopelvic fixation for adult spinal deformity were included. The patients were divided into two groups: the PJK group (n=7) and the nonPJK group (n=14). Patients who experienced PJK within half a year of surgery were included in the PJK group. Pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), thoracic kyphosis (TK), thoracic compensation (TK compensation), sagittal vertical axis (SVA), T10-L2 angle, and T1 pelvic angle (TPA) were measured before and after surgery.

Results

No difference was found between the two groups in terms of age and sex at the time of surgery. The indices that were significantly different between the two groups were preoperative PT, PI minus LL, TK, TPA, TK compensation, and postoperative T10-L2 angle. No significant differences were found in postoperative LL, PI minus LL, PT, TK, TPA, or SVA.

Conclusions

Preoperative X-ray indices, including preoperative TPA, TK compensation, TK, PT, and PI-LL, determined the risk of PJK in fusions from the sacrum to L1 or L2. Appropriate patient selection is crucial for the success of this surgery.

Is Blood Loss Greater in Elderly Patients under Antiplatelet or Anticoagulant Medication for Cervical Spine Injury Surgery? A Japanese Multicenter Survey

Introduction

In elderly patients with cervical spinal cord injury, comorbidities such as cardiovascular and cerebrovascular diseases are common, with frequent administration of antiplatelet/anticoagulant (APAC) drugs. Such patients may bleed easily or unexpectedly during surgery despite prior withdrawal of APAC medication. Few reports have examined the precise relationship between intraoperative blood loss and history of APAC use regarding surgery for cervical spine injury in the elderly. The present multicenter database survey aimed to answer the question of whether the use of APAC drugs affected the amount of intraoperative blood loss in elderly patients with cervical spinal cord trauma.

Methods

The case histories of 1512 patients with cervical spine injury at 33 institutes were retrospectively reviewed. After excluding cases without spinal surgery or known blood loss volume, 797 patients were enrolled. Blood volume loss was the outcome of interest. We calculated propensity scores using the inverse probability of treatment weighting (IPTW) method. As an alternative sensitivity analysis, linear mixed model analyses were conducted as well.

Results

Of the 776 patients (mean age: 75.1±6.4 years) eligible for IPTW calculation, 157 (20.2%) were taking APAC medications before the injury. After weighting, mean estimated blood loss was 204 mL for non-APAC patients and 215 mL for APAC patients. APAC use in elderly patients was not significantly associated with surgical blood loss according to the IPTW method with propensity scoring or linear mixed model analyses. Thus, it appeared possible to perform surgery expecting comparable blood loss in APAC and non-APAC cases.

Conclusions

This multicenter study revealed no significant increase in surgical blood loss in elderly patients with cervical trauma taking APAC drugs. Surgeons may be able to prioritize patient background, complications, and preexisting conditions over APAC use before injury when examining the surgical indications for cervical spine trauma in the elderly.

Predictors of the need for rib resection in minimally invasive retroperitoneal approach for oblique lateral interbody fusion at upper lumbar spine (L1-2 and L2-3)

BACKGROUND

This study aimed to identify factors that can predict the need for rib resection in a minimally invasive, oblique retroperitoneal approach for upper lumbar interbody fusion (OLIF at L1-3) using modern tubular retractors.

METHODS

Eighty-six patients, who underwent L1-2 and/or L2-3 OLIF at a single institution, were included. Decision for rib resection was made through intraoperative fluoroscopic view (true lateral view of the desired level). Patients were divided into two groups according to rib resection (rib resection and non-rib resection groups). Baseline demographics, surgical and radiographic data, including coronal/sagittal spinopelvic parameters and perioperative complications, were compared between the groups. Logistic regression analysis was performed to identify the factors predicting the need for rib resection.

RESULTS

The study cohort comprised 31 patients in the rib resection group and 55 patients in the non-rib resection group. There was no significant inter-group difference in terms of the baseline demographics. A total of 79% patients undergoing the two-level (both L1-2 and L2-3) procedures were rib-resected, while 81.6% of the patients undergoing the L2-3 level alone were not rib-resected. Endplate injuries occurred more commonly in the non-rib resection group (3% vs. 14%). Pleural laceration was observed in 6% of the patients in the rib resection group. The mean T10-L2 kyphosis was larger in the rib resection group than in the non-rib resection group (14.9° vs. 6.6°, P = 0.031). Multivariate logistic regression analysis identified the following independent predictors of the need for rib resection: an L1-2 inclusive procedure; T10-L2 kyphosis > 15.9°; and the apex of the coronal curve located above L2.

CONCLUSION

The need for rib resection should be expected when performing L1-2 inclusive procedure. Even in the L2-3 alone case, aggressive decision-making for intraoperative rib resection might be required for an appropriate tubular retractor position, especially for patients with thoracolumbar kyphosis and apex vertebra of the major coronal curve located above L2.

Bioactivity and antibacterial activity of iodine-containing calcium titanate against implant-associated infection

Developing antimicrobial biomaterials is a major challenge in the fields of orthopaedic and dental implants. In this study, we evaluated the bone-bonding ability and antibacterial activity of a novel biomaterial for preventing implant-associated infections. We have previously reported that NaOH heat treatment improved the bone-bonding ability of titanium, which was later modified to release target ions from the calcium titanate surface. Iodine, an essential nutrient, exhibits broad-spectrum antimicrobial activity; hence, we designed a calcium titanate that releases iodine ions (Ca-I-Ti). The material was prepared from a simple solution using heat treatments as well as inexpensive devices and chemical agents. MC3T3-E1 cells seeded on Ca-I-Ti displayed high degrees of bioactivity and viability, and Ca-I-Ti exhibited antibacterial activity against methicillin-susceptible Staphylococcus aureus. In vivo biomechanical and histological experiments showed that Ca-I-Ti had excellent bone-bonding ability at 8 weeks after implantation. In a subcutaneous infection model in rats, methicillin-susceptible Staphylococcus aureus on the implant was reduced by approximately 95% compared to that on commercially pure titanium, indicating that Ca-I-Ti has antibacterial effects in vivo. In addition, no local or systemic complications were observed, and active infection in the surrounding tissues was histologically inhibited. Thus, iodine-containing calcium titanate is a safe biomaterial with excellent bioactivity and antibacterial properties, indicating its potential in preventing implant-associated infections.

Comparative Study of the Usage of Closed Suction and Nonsuction Drains in Cervical Laminoplasty

Introduction

Although previous studies reported the clinical significance of drains in lumbar surgery, their role in and effects on the clinical outcomes of cervical spine surgery remain unclear. The present study compared the clinical outcomes of cervical laminoplasty (CLP) using a closed suction drain (CSD) and closed nonsuction drain (CNSD).

Methods

Prospectively recorded surgical data on consecutive patients who underwent CLP at a single institution between 2014 and 2020 and were followed up for at least 1 year were examined. CSD was used prior to January 2018, and CNSD has since been employed. One hundred patients who underwent surgery before and after the change in drain type (the CSD and CNSD groups, respectively) were selected for analysis. Primary outcome measures were the drainage amount, blood count, and fluid collection at the surgical site defined by magnetic resonance images. The Japanese Orthopaedic Association (JOA) score for the cervical spine was also evaluated as a functional outcome.

Results

No significant differences were observed in demographic, baseline clinical, or surgical data between the CSD and CNSD groups. The drainage amount was significantly greater in the CSD group than in the CNSD group (224 vs. 143 mL, P<0.001). Hemoglobin and hematocrit levels were significantly decreased in the CSD group than in the CNSD group. Medium or large fluid collection was significantly more common in the CNSD group than in the CSD group. No significant differences were observed in the number of surgical site infections, the formation of symptomatic hematoma, or JOA scores between the two groups.

Conclusions

The use of CNSD in CLP decreased the drainage amount and maintained the hemoglobin level compared with that of CSD. Although no patients developed symptomatic hematoma, the amount of epidural fluid collected was larger in the CNSD group than in the CSD group.

The degenerative changes of the sacroiliac joint after S2 alar-iliac screw placement

OBJECTIVE

The goal of this study was to investigate clinical outcomes and risk factors for the progression of sacroiliac joint (SIJ) degeneration and bone formation after S2 alar-iliac screw (S2AIS) insertion.

METHODS

Using preoperative and follow-up CT scan findings (median follow-up 26 months, range 16-43 months), the authors retrospectively studied 100 SIJs in 50 patients who underwent S2AIS placement. The authors measured the progression of SIJ degeneration and bone formation after S2AIS insertion, postoperative new-onset SIJ pain, S2AIS-related reoperation, and instrumentation failures. Stepwise multivariate logistic regression modeling was performed to clarify the risk factors associated with the progression of SIJ degeneration.

RESULTS

Significant progression of SIJ degeneration was observed in 10% of the group with preoperative SIJ degeneration (p = 0.01). Bone formation was observed in 6.9% of joints. None of the patients with these radiographic changes had new-onset SIJ pain or underwent reoperation related to instrumentation failures. Multivariate logistic regression analysis revealed that preoperative SIJ degeneration (p < 0.01) and a young age at surgery (p = 0.03) significantly affected the progression of SIJ degeneration.

CONCLUSIONS

The progression of SIJ degeneration and bone formation neither led to major screw-related complications nor affected the postoperative clinical course during the median follow-up period of 26 months. Although S2AIS insertion is a safe procedure for most patients, the results of this study suggested that preoperative degeneration and younger age at surgery affected SIJ degeneration after S2AIS insertion. Further long-term observation may reveal other effects of S2AIS insertion on SIJ degeneration.