Non-linear Effect of Preexisting Cranial Adjacent Disc Degeneration on Cumulative 12-year Revision Risk Following Lumbar Fusions.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: To evaluate how preexisting adjacent segment degeneration status impacts revision risk for adjacent segment disease (ASD) after lumbar fusions. SUMMARY OF BACKGROUND DATA: ASD incurs late reoperations after lumbar fusion surgeries. ASD pathogenesis is multifactorial. Preexisting adjacent segment degeneration measured by Pfirrmann is suggested as one of the predisposing factors. We sought to find deeper insights into this association by using a more granular degeneration measure, the Combined imaging score (CIS). METHODS: A total of 197 consecutive lumbar fusions for degenerative pathologies were enrolled in a prospective follow-up (median 12 years). Preoperative cranial adjacent segment degeneration status was determined using Pfirrmann and CIS, which utilizes both radiographs and magnetic resonance imaging. Based on CIS, patients were trichotomized into tertiles (CIS <7, CIS 7-10, and CIS >10). The cumulative ASD revision risk was determined for each tertile. After adjusting for age, sex, body mass index, sacral fixation, and fusion length, hazard ratios (95% confidence intervals, CI) for ASD revisions were determined for each Pfirrmann and CIS score. RESULTS: Patients in the intermediate CIS tertile had a cumulative ASD revision risk of 25.4% (17.0% to 37.0%), while both milder degeneration (CIS <7) [13.2% (6.5% to 25.8%)] and end-stage degeneration (CIS >10) [13.6% (7.0% to 25.5%)] appeared to be protective against surgical ASD. Pfirrmann failed to show a significant association with ASD revision risk. Adjusted analysis of CIS suggested increased ASD revisions after CIS 7, which turned contrariwise after CIS 10. CONCLUSIONS: The effect of preexisting adjacent segment degeneration on ASD reoperation risk is not linear. The risk seems to increase with advancing degeneration but diminish with end-stage degeneration. Therefore, end-stage degenerative segments may be considered to be excluded from fusion constructs. LEVEL OF EVIDENCE: Therapeutic Level III.

Incidence of lumbar discectomy during pregnancy and within 12 months post-partum in Finland between 1999 and 2017: a retrospective register-based cohort study.

BACKGROUND CONTEXT: Both lumbar disc herniation in the general population and lower back pain in the pregnant population are known to be common conditions. The physiological and anatomical of the mother predispose to increased strain of the lumbar disc, whereas pregnancy may promote caution in physicians contemplating surgical care. PURPOSE: We aimed to report the incidence of lumbar discectomy during pregnancy and 12 months postpartum in Finland between 1999 and 2017. STUDY DESIGN: Retrospective register-based cohort study. PATIENT SAMPLE: Using nationwide data from the Finnish Care Register for Health Care and the Finnish Medical Birth Register, all women aged 15 to 49 years with a lumbar discectomy or pregnancy ending in delivery from 1st January, 1999 to 31st December, 2017 were included. OUTCOME MEASURES: Incidence rates and their 95% confidence intervals were calculated for lumbar discectomy. Incidence rate ratios (IRR) were calculated between the study population and the control population. The effect of smoking on surgery risk was reported using odds ratios. METHODS: A retrospective statistical analysis was performed to identify patients undergoing lumbar discectomy during pregnancy or the first 12 months after delivery. Incidence rates were compared with the age-adjusted values of the age-matched female general population. The effect of smoking on the risk of lumbar discectomy was analyzed using age-adjusted odds ratios. RESULTS: In total, 91 discectomies were performed during pregnancy and 508 within 12 months postpartum. The total incidence of lumbar discectomy during pregnancy was 11 operations per 100,000 person-years with an IRR of 0.2 (95% CI 0.1-0.2) when compared with the age-adjusted female general population. Women with active smoking before pregnancy were at a higher risk for lumbar discectomy during pregnancy (OR 2.0, 95% CI 1.2-3.2). Caesarean section was more common after lumbar discectomy (22%). No perinatal mortality was observed. During the first-year postpartum the rate of lumbar discectomy increased to 47 per 100 000 person-years with an IRR of 0.7 (95% CI 0.6-0.8). 90-day reoperation rates were higher than in the general population with an IRR of 1.7 (95% CI 1.1- 2.7). CONCLUSIONS: Lumbar discectomy during pregnancy is rare, but smoking increases the risk. Lumbar discectomy during pregnancy seems to be safe for the neonate. Postpartum incidences increased towards the end of the first year, but remained below the rates in the general population with a higher risk for short-term reoperation.

Regional variations in lumbar spine surgery in Finland.

INTRODUCTION: The regional variation in spine surgery rates has been shown to be large both within and between countries. This variation has been reported to be less in studies from countries with spine registers. The aim of this study was to describe the regional variation in lumbar spine surgery in Finland. MATERIALS AND METHODS: This is a retrospective register study. Data from the Finnish National Hospital Discharge Register (NHDR) were used to calculate and compare the rates of lumbar disc herniation (LDH), decompression, and fusion surgeries in five University Hospital catchment areas, covering the whole Finnish population, from January 1, 1997, through December 31, 2018. RESULTS: A total of 138,119 lumbar spine operations (including LDH, decompression, and fusion surgery) were performed in Finland between 1997 and 2018. The regional differences in the rate of LDH surgery were over fourfold (18 vs. 85 per 100,000 person years), lumbar decompression surgery over threefold (41 vs. 129 per 100,000 person years), and lumbar fusion surgery over twofold (14 vs. 34 per 100,000 person years) in 2018. The mean age of the patients increased in all regions during the study period. CONCLUSIONS: In Finland, the regional variations in spine surgeries were vast. In a country with a publicly funded healthcare system, this finding was surprising. The recently created national spine register may serve to shed more light on the reasons for this regional variation.

Pregnancy and delivery after spine fracture or surgery: A nationwide population-based register study in Finland.

BACKGROUND: The incidences of spine fractures and fusion surgeries have increased. A few studies have reported an increased rate of caesarean sections (CS) in women who have undergone spine surgery but have not reported on the health of neonates. OBJECTIVE: We report the incidence of spine fractures, spine fracture surgeries and fusion surgery for other reasons and the effect of these injuries and procedures on later pregnancy outcomes in Finland. METHODS: Data on all fertile-aged women (1998-2018) who had undergone spine fracture or spine fusion surgery were retrieved from the Care Register for Healthcare and combined with data from the National Medical Birth Register. Women with spine fracture or spine surgery before pregnancy were compared with women without previous spine fracture or surgery. We calculated incidences of spine fracture, spine fracture surgery and fusion surgery for other reasons with 95% confidence intervals (CI). We used multivariable logistic regression to evaluate CS and neonatal health. Results are reported as adjusted odds ratios (AOR). RESULTS: The main finding of our study was the increasing incidence (156%) of spine fusion surgeries for other reasons in fertile-aged women. A total CS rate (including elective and unplanned CS) in the spine fracture group was 19.7% (AOR 1.26, CI 1.17-1.34), in fusion surgery for other reasons group 25.3% (AOR 1.37, CI 1.30-1.49) and 15.9% in the control group. The rate for neonates requiring intensive care in the spine fracture group was 12.2% (AOR 1.18, CI 1.08-1.29), in fusion surgery for other reasons group 13.6% (AOR 1.12, CI 1.02-1.23) and 10.0% in the control group. CONCLUSIONS: The incidence of fusion surgery for other reasons increased during our study period. The rate of CS was higher in women with preceding spine fracture or fusion surgery. Our results suggest that vaginal delivery after fractures of the spine is both possible and safe for mother and neonate.

Postoperative Sagittal Balance Has Only a Limited Role in the Development of Adjacent Segment Disease After Lumbar Spine Fusion for Degenerative Lumbar Spine Disorders: A Subanalysis of the 10-year Follow-up Study.

STUDY DESIGN: Retrospective additional analysis of a prospective follow-up study. OBJECTIVES: We aimed to find out whether poor postoperative sagittal alignment increases revisions for adjacent segment disease (ASD) after lumbar spine fusion (LSF) performed for degenerative lumbar spine disease. SUMMARY OF BACKGROUND DATA: Revisions for ASD accumulate over time after LSF for degenerative lumbar spine disease. The etiology of ASD is considered multifactorial. Yet, the role of postoperative sagittal balance in this process remains controversial. MATERIALS AND METHODS: A total of 215 consecutive patients who had undergone an elective LSF surgery for spinal stenosis with (80%) or without (20%) spondylolisthesis were analyzed. Spinal reoperations were collected from the hospital records. Preoperative and postoperative sagittal alignment were evaluated from standing radiographs. The risk of revisions for ASD was evaluated by Cox proportional hazards regression models. RESULTS: We did not find the poor postoperative balance [pelvic incidence-lumbar lordosis (LL) >9°] to significantly increase the risk of revisions for ASD: crude hazard ratio (HR)=1.5 [95% confidence interval (CI): 0.8-2.7], adjusted (by age, sex, pelvic incidence, fusion length, and the level of the caudal end of fusion): HR=1.7 (95% CI: 0.9-3.3). We found higher LL outside the fusion segment (LL-segmental lordosis) to decrease the risk of revisions for ASD: HR=0.9 (95% CI: 0.9-1.0). CONCLUSION: Poor sagittal balance has only a limited role as a risk factor for the revisions for ASD among patients with degenerative spinal disease. However, the risk for ASD might be the greatest among patients with reduced spinal mobility.

Trends in emergency department visits due to back pain and spine surgeries during the COVID-19 pandemic in Finland.

ABSTRACT: We aim to report the incidences of ED visits due to back pain, hospitalizations, and urgent spine surgeries during the first and second waves of COVID-19 in Finland. The number of emergency department visits and hospitalizations due to back pain as well as urgent spine surgeries in the adult population was collected from hospital discharge registers for the years 2017 through 2019 (reference years) and 2020.This study was conducted at three large Finnish hospitals. The monthly incidence with 95% confidence intervals (CI) of emergency department visits and hospitalizations due to back pain and spine surgeries in the three participating hospitals were calculated and compared by incidence rate ratios (IRR).Visits to ED due to back pain decreased during the pandemic. The incidence of ED visits due to back pain was similar in February (IRR 0.95, CI: 0.82-1.10), but a decrease was seen after lockdown began (March IRR 0.67, CI: 0.57-0.78; April IRR 0.65, CI: 0.56-0.76) compared to the reference years. A second decrease in visits was seen after regional restrictions were implemented in October (IRR 0.88, CI: 0.76-1.02). The most common diagnoses were non-specific back pain, lumbar disk herniation, and back contusion. Incidence of non-specific back pain decreased during the lockdown (March IRR 0.65, CI: 0.55-0.78) and regional restrictions (October IRR 0.83, CI: 0.70-0.98), whereas the rates of other diagnoses remained unchanged, and incidences of hospitalizations and urgent spine surgeries remained stable.A clear decrease in ED visits due to back pain was seen during the first and second waves of the pandemic. This decrease was mainly the result of patients with non-specific back pain avoiding visits to the ED. The incidence of specific back pain, hospitalizations, and urgent spine surgeries remained unchanged during the pandemic.

Median 10-year whole blood metal ion levels and clinical outcome of ReCap-M2a-Magnum metal-on-metal total hip arthroplasty.

BACKGROUND AND PURPOSE: We have previously reported that the whole blood (WB) chromium (Cr) and cobalt (Co) ion levels decrease in the short term after ReCap-M2a-Magnum large-diameter head (LDH) metal-on-metal (MoM) total hip arthroplasty (THA). This study reports long-term metal ion levels and clinical outcomes after ReCap-Magnum THA. PATIENTS AND METHODS: ReCap-M2a-Magnum LDH THA was used in 1,450 patients in our hospital district from 2005 to 2012. Median follow-up time was 10 years. 991 patients had 2 or more metal ion measurements. The median measurement interval was 4 years. Individual metal ion change was assessed using logarithmic metal ion values in a random coefficient model. Kaplan-Meier survival estimates were calculated for revision surgery for any reason for revision, and separately for metal-related adverse events (metal ions above safe upper limit [SUL], revision due to ARMD, or pseudotumor). RESULTS: Geometric mean of Cr decreased from 1.8 ppb (geometric standard deviation [GSD] 1.8) to 1.0 ppb (GSD 2.8, p < 0.001). The Co levels decreased from 1.7 ppb (GSD 2.4) to 1.4 ppb (GSD 2.8, p < 0.001). The hip-specific survival was 85% for revision due to any reason at 14 years and the hip-specific survival for any metal-related adverse event was 69% at 14 years. INTERPRETATION: WB Cr and Co levels continued to decrease in the long-term follow-up of ReCap-M2a-Magnum THA patients. The amount of metal-related adverse events was rather high, but revision surgery was seldom required. We suggest that after 10 years from the implantation a 5-year measurement interval may be sufficient for asymptomatic ReCap-M2a-Magnum patients.

Isthmic Spondylolisthesis is Associated with Less Revisions for Adjacent Segment Disease After Lumbar Spine Fusion Than Degenerative Spinal Conditions: A 10-Year Follow-Up Study.

STUDY DESIGN: Prospective, follow-up study. OBJECTIVE: We aim to compare the rate of revisions for ASD after LSF surgery between patients with IS and DLSD. SUMMARY OF BACKGROUND DATA: ASD is a major reason for late reoperations after LSF surgery. Several risk factors are linked to the progression of ASD, but the understanding of the underlying mechanisms is imperfect. If IS infrequently becomes complicated with ASD, it would emphasize the role of the ongoing degenerative process in spine in the development of ASD. METHODS: 365 consecutive patients that underwent elective LSF surgery were followed up for an average of 9.7 years. Surgical indications were classified into 1) IS (n = 64), 2) DLSD (spinal stenosis with or without spondylolisthesis) (n = 222), and 3) other reasons (deformities, postoperative conditions after decompression surgery, posttraumatic conditions) (n = 79). All spinal reoperations were collected from hospital records. Rates of revisions for ASD were determined using Kaplan-Meier methods. RESULTS: Altogether, 65 (17.8%) patients were reoperated for ASD. The incidences of revisions for ASD in subgroups were 1) 4.8% (95% CI: 1.6%-22.1%); 2) 20.5% (95% CI: 15.6%-26.7%); 3) 20.6% (95% CI: 12.9%-31.9%). After adjusting the groups by age, sex, fusion length, and the level of the caudal end of fusion, when comparing with IS group, the other groups had significantly higher hazard ratios (HR) for the revision for ASD [2) HR (95% CI) 3.92 (1.10-13.96), P = 0.035], [3) HR (95% CI) of 4.27 (1.11-15.54), P = 0.036]. CONCLUSION: Among patients with IS, the incidence of revisions for ASD was less than a 4th of that with DLSD. Efforts to prevent the acceleration of the degenerative process at the adjacent level of fusion are most important with DLSD.Level of Evidence: 3.

Decreasing Incidence of Lumbar Discectomy Surgery in Finland in 1997-2018.

STUDY DESIGN: Retrospective register study. OBJECTIVE: The aim of this study was to assess the incidence and trends of lumbar disc surgeries in Finland from 1997 through 2018. SUMMARY OF BACKGROUND DATA: The evidence on lumbar spine discectomy has shifted from supporting surgical treatment toward nonoperative treatment. Still, the incidence of lumbar discectomy operations increased until the 1990 s. In the United States, the incidence began to decline after a downward turn in 2008, yet recent trends from countries with public and practically free health care are not widely known. METHODS: Data for this study were obtained from the Finnish nationwide National Hospital Discharge Register. The study population covered all patients 18 years of age or older in Finland during a 22-year period from January 1, 1997, to December 31, 2018. RESULTS: A total of 65,912 lumbar discectomy operations were performed in Finland from 1997 through 2018. The annual population-based incidence of lumbar discectomy decreased 29% during the 22-year period, from 83 per 100,000 person-years in 1997 to 58 per 100,000 person-years in 2018. In addition, the incidence of microdiscectomy increased 12%, from 41 per 100,000 person-years in 1997 to 47 per 100,000 person-years in 2018, whereas the incidence of open discectomy decreased 71%, from 41 per 100,000 person-years in 1997 to 12 per 100,000 person-years in 2018. The total reoperation rate for microendoscopic, microscopic, and open discectomy surgeries was 16.3%, 15.3%, and 14.9%, respectively. CONCLUSION: The nationwide incidence of lumbar discectomy decreased in Finland from 1997 through 2018. Additionally, the incidence of open discectomy is decreasing rapidly, whereas the incidence of microsurgical techniques is increasing.Level of Evidence: 3.

Repeated cobalt and chromium ion measurements in patients with bilateral large-diameter head metal-on-metal ReCap-M2A-Magnum total hip replacement.

Background and purpose - Whole-blood (WB) chromium (Cr) and cobalt (Co) measurements are vital in the follow-up of metal-on-metal total hip replacement (MoM THR) patients. We examined whether there is a substantial change in repeated WB, Co, and Cr levels in patients with bilateral ReCap-M2A-Magnum THR. We also specified the number of patients exceeding the safe upper limit (SUL) of WB Co and Cr in the repeated measurement.Patients and methods - We identified 141 patients with bilateral ReCap-M2A-Magnum THR operated in our institution. 61 patients had repeated WB metal ion measurements with bilateral MoM implants still in situ in the second measurement. The mean time elapsing from the first measurement (initial measurement) to the second (control measurement) was 1.9 years (SD = 0.6, range 0.2-3.5). We used earlier established SUL levels for bilateral implants by Van Der Straeten et al. (2013).Results - The median (range) Co and Cr values decreased in the repeated measurement from 2.7 (0.6-25) to 2.1 (0.5-21) and 2.6 (0.8-14) to 2.1 (0.5-18) respectively. In 13% of the patients Co levels exceeded the SUL in the initial measurement and the proportion remained constant, at 13%, in the repeated measurement. In 5% of the patients, Cr levels were above SUL in the initial measurement and an equal 5% in the control measurement.Interpretation - Repeated WB metal ion levels did not increase in patients with bilateral ReCap-M2A-Magnum THR with a mean 1.9-year measurement interval. Long-term development of WB metal ion levels is still unclear in these patients.

Repeated cobalt and chromium ion measurements in patients with large-diameter head metal-on-metal ReCap-M2A-Magnum total hip replacement.

Background and purpose - Whole blood (WB) cobalt (Co) and chromium (Cr) ion levels have a major role in the follow-up of metal-on-metal total hip replacement (MoM THR). We investigated, first, if there was a change in WB Co or Cr levels over repeated measurements in patients with ReCap-M2A-Magnum THR, and, second, determined how many patients had WB Co or Cr levels that exceeded the safe upper limits (SUL) in the repeated whole blood metal ion assessment. Patients and methods - A Recap-M2A-Magnum THR was used in 1,329 operations (1,188 patients) at our institution between 2005 and 2012. We identified all patients (n = 319) with unilateral ReCap-M2A-Magnum implants who had undergone at least 2 repeated metal ion measurements with the first blood sample taken mean 5.5 years (1.8-9.3) after surgery and the second taken mean 2 years (0.5-3) after the first. Results - The median WB Co and Cr ion levels decreased in repeated measurements from 1.40 (0.40-63) ppb to 1.10 (0.20-68) ppb and from 1.60 (0.60-13.0) ppb to 1.10 (0.30-19.0) ppb, respectively. 7% of the Co ion values exceeded SUL at the initial measurement, and 7% at the control measurement. The proportion of Cr ion values exceeding the safe upper limit (SUL) decreased during the measurement interval from 5% to 4%. Interpretation - Repeated metal ion measurements in unilateral ReCap-M2A-Magnum patients in a mean 2-year time interval did not show any increase. Long-term ion levels are, however, not yet known.

Modular to Monoblock: Difficulties of Detaching the M(2)a-Magnum(TM) Head Are Common in Metal-on-metal Revisions.

BACKGROUND: Modern hip implants typically feature modular heads, which allow for easy exchange and removal from the femoral stem at the time of revision. However, owing to fretting, corrosion, or cold welding, the modular head may be difficult or impossible to separate from the underlying trunnion, especially if the implant has titanium interfaces between the head and the stem. We have repeatedly encountered difficulty removing the titanium sleeve adapter in the M(2)a-Magnum(TM) implant. Although the manufacturer warns about this complication and cases with these difficulties have been reported to the United States FDA, we believed this topic is important to study, because the frequency of difficulties in head removal is unknown and the complications related to this event have not been characterized. QUESTIONS/PURPOSES: We asked: (1) Do revisions of M(2)a-Magnum(TM) implants differ from those of M(2)a-38(TM) implants in terms of ease of removal of the femoral head? (2) In cases where difficulty with M(2)a-Magnum(TM) head removal occurred, was the operative time, bleeding, risk of periprosthetic fracture, or joint infection increased compared with cases where the M(2)a-Magnum(TM) head was removed without difficulties? METHODS: Between 2004 and 2014, we revised 296 THAs with metal-on-metal implants that involved M(2)a-Magnum(TM) (123) or M(2)a-38(TM) heads (88); of those, 84 were planned to include a femoral stem revision and insufficient data were available for three operations, so they were excluded from this analysis, leaving 124 THAs in the current retrospective study (70 THAs with M(2)a-Magnum(TM) and 54 THAs with M(2)a-38(TM) heads).The method of modular head removal, any difficulties removing the femoral head from the trunnion, operation time, and complications were recorded based on chart review. RESULTS: All the observed problems of detaching the head or taper adapter were among M(2)a-Magnum(TM) heads; there were no problems detaching the head in revisions of the M(2)a-38(TM) implant. In 29% (20 of 70) of revisions of the M(2)a-Magnum(TM) implant, the modular head could not be detached by knocking it with a punch and a mallet. Seventeen percent (12 of 70) of hips needed an unplanned stem revision owing to difficulties with head removal. In revisions of the M(2)a-Magnum(TM) implant that experienced head-removal problems, the median operative time was longer (144 minutes; range, 75-274 minutes) and bleeding was greater (725 mL; range, 300-2200 mL) compared with revisions of the M(2)a-Magnum(TM) implant without head removal problems (77 minutes, range, 33-197 minutes, p < 0.001; 475 mL, range, 50-1500 mL, p = 0.004). With the numbers available, we did not see differences in terms of the proportion of patients experiencing major complications (periprosthetic fracture or postoperative infections) between the groups (difficult versus easy; 25% [five of 20] versus 8% [four of 50]; odds ratio, 3.8 [95% CI, 0.9-16.2], p = 0.067). CONCLUSIONS: The titanium-titanium taper junction can be very difficult to separate during revision THAs, and if not anticipated, this problem can result in larger and more complicated revision procedures in patients who have the M(2)a-Magnum(TM) implant. Although the global use of metal-on-metal implants in THAs has decreased dramatically during the last several years, many thousands remain in service and therefore still might require revision. It is crucial to be prepared with special tools, including a femoral head extraction tool and diamond saw. The patient has to be informed of the possibility of a more extensive operation than preoperatively planned. LEVEL OF EVIDENCE: Level III, therapeutic study.