Association Between Osteoarthritis Burden and Intervertebral Disk Degeneration in Patients Undergoing Lumbar Spine Surgery for Degenerative Lumbar Spondylolisthesis.

STUDY DESIGN: A retrospective analysis of prospectively collected data. OBJECTIVE: To assess the association between intervertebral disk degeneration and hip and knee osteoarthritis (OA) in patients with degenerative lumbar spondylolisthesis. BACKGROUND: The co-occurrence of hip OA and degenerative spinal pathologies was first described as the "hip-spine syndrome" and has also been observed in knee OA. It remains unclear whether both pathologies share an underlying connection beyond demographic factors. MATERIALS AND METHODS: Intervertebral disk degeneration was classified by the Pfirrmann Classification and intervertebral vacuum phenomenon. Intervertebral vacuum phenomenon was classified into mild (1 point), moderate (2 points), and severe (3 points) at each level and combined into a lumbar vacuum score (0-15 points). Similarly, a lumbar Pfirrmann grade was calculated (5-25 points). Patients with previous hip or knee replacement surgery were classified as having an OA burden. We used multivariable regression to assess the association between OA and disk degeneration, adjusted for age, body mass index, and sex. RESULTS: A total of 246 patients (58.9% female) were included in the final analysis. Of these, 22.3% had OA burden. The multivariable linear regression showed an independent association between OA burden and lumbar vacuum (ß = 2.1, P <0.001) and Pfirrmann grade (ß = 2.6, P <0.001). Representing a 2.1 points higher lumbar vacuum and 2.6 points higher lumbar Pfirrmann grade after accounting for demographic differences. CONCLUSIONS: Our study showed that OA burden was independently associated with the severity of the intervertebral disk degeneration of the lumbar spine. These findings give further weight to a shared pathology of OA of large joints and degenerative processes of the lumbar spine. LEVEL OF EVIDENCE: 3.

MRI-based measurements of spondylolisthesis and kyphosis in degenerative cervical myelopathy.

BACKGROUND: To provide normative data and to determine accuracy and reliability of preoperative measurements of spondylolisthesis and kyphosis on supine static magnetic resonance imaging (MRI) of patients with degenerative cervical myelopathy. METHODS: T2-weighted midsagittal images of the cervical spine were in 100 cases reviewed twice by one junior observer, with an interval of 3 months, and once by a senior observer. The spondylolisthesis slip (SSlip, mm) and the modified K-line interval (mK-line INT, mm) were assessed for accuracy with the standard error of measurement (SEm) and the minimum detectable change (MDC). Intraobserver and interobserver reliability levels were determined using the intraclass correlation coefficient (ICC). RESULTS: The SEm was 0.5 mm (95% CI 0.4-0.6) for spondylolisthesis and 0.6 mm (95% CI 0.5-0.7) for kyphosis. The MDC, i.e., the smallest difference between two examinations that can be detected with statistical certainty, was 1.5 mm (95% CI 1.2-1.8) for spondylolisthesis and 1.6 mm (95% CI 1.3-1.8) for kyphosis. The highest reliability levels were seen between the second observation of the junior examiner and the senior observer (ICC = 0.80 [95% CI 0.70-0.87] and ICC = 0.96 [95% CI 0.94-0.98] for SSlip and mK-line INT, respectively). CONCLUSIONS: This study provides normative values of alignment measurements of spondylolisthesis and kyphosis in DCM patients. It further shows the importance of taking measurement errors into account when defining cut-off values for cervical deformity parameters and their potential clinical application in surgical decision-making.

Manipulation of osteogenic and adipogenic differentiation of human degenerative disc and ligamentum flavum derived progenitor cells using IL-1ß, IL-19, and IL-20.

PURPOSE: To elucidate whether pro-inflammatory cytokines might influence the commitment of intervertebral disc (IVD)- and ligamentum flavum (LF)-derived progenitor cells toward either osteogenesis or adipogenesis, specifically Interleukin-1ß (IL-1ß), IL-19, and IL-20. METHODS: Sixty patients with degenerative spondylolisthesis and lumbar or lumbosacral spinal stenosis were included in the study. Injuries to the spine, infections, and benign or malignant tumors were excluded. From nine patient samples, IVD- and LF-derived cells were isolated after primary culture, and two clinical samples were excluded due to mycoplasma infection. The effects of IL-1ß, IL-19, as well as IL-20 in regulating osteogenic and adipogenic differentiation in vitro were investigated. RESULTS: Primary IVD- and LF-derived cells were found to have a similar cell morphology and profile of surface markers (CD44, CD90, and CD105) as placenta-derived mesenchymal stem cells (MSCs). Primary IVD/LF cells have a high capacity to differentiate into osteocytes and adipocytes. IL-19 had a tendency to promote adipogenesis. IL-20 inhibited osteogenesis and promoted adipogenesis; IL-1ß promoted osteogenesis but inhibited adipogenesis. CONCLUSION: IL-1ß, IL-19, and IL-20 impact the adipogenic and osteogenic differentiation of IVD-derived and LF-derived cells. Modulating the expression of IL-1ß, IL-19, and IL-20 provides a potential avenue for controlling cell differentiation of IVD- and LF-derived cells, which might have beneficial effect for degenerative spondylolisthesis and spinal stenosis.

Imaging analysis and predictive nomogram construction for degenerative lumbar spondylolisthesis with severe clinical symptom based on propensity score matching.

Intervertebral disc degeneration, local lumbar segmental morphology changes, and atrophy of multifidus muscle have been considered to be associated with degenerative lumbar spondylolisthesis. However, there remains a great deal of controversy. To further investigate their relationship with degenerative lumbar spondylolisthesis, we conducted a retrospective study that included 67 patients with degenerative spondylolisthesis and 182 control subjects. Propensity score matching was employed to match the case group and the control group. Disc height was evaluated by the anterior disc height index (DHIA) and posterior disc height index (DHIP). Local lumbar segmental morphology was assessed by segmental lordosis (SL). The fatty infiltration and atrophy of multifidus muscle was evaluated by multifidus muscle net content (MFNC). Our results indicate that DHIA, DHIP, SL, and MFNC in the case group were significantly lower than in the control group. Furthermore, the DHIA, DHIP, and MFNC of the slipped segment (L4/5) were lower than those of the non-slipped segment (L3/4). Correlation analysis showed a high relationship between DHIA and MFNC and the degree of degenerative lumbar spondylolisthesis. Logistic regression analysis revealed that DHIA and MFNC might act as protective factors against the development of degenerative lumbar spondylolisthesis. Additionally, a prognostic nomogram was developed and validated to assess the likelihood of patients with severe symptoms requiring surgical intervention.

Utility of Flexion-Extension Radiographs with Brackets and Magnetic Resonance Facet Fluid for the Assessment of Lumbar Instability in Degenerative Lumbar Spondylolisthesis.

OBJECTIVE: To propose a new standardized technique for evaluating lumbar stability in degenerative lumbar spondylolisthesis using lumbar lateral flexion-extension radiographs with brackets and magnetic resonance facet fluid. METHODS: A retrospective analysis of 57 patients diagnosed with lumbar (L4-5) spondylolisthesis was performed. We analyzed lateral flexion-extension radiographs obtained with a bracket (LFEB) and without a bracket (LFE). Sagittal translation, segmental angulation, posterior opening, lumbar instability, and changes in lumbar lordosis were compared using functional radiographs. The mean width and maximum width of the facet fluid, mean facet joint length, and facet fluid index (FFI) of the 2 groups were compared using sagittal translation. RESULTS: The average value of sagittal translation was 1.68 ± 0.96 mm in LFE and 3.07 ± 1.29 mm in LFEB, and the difference was significant (P < 0.05). Segmental angulation, posterior opening, and changes in lumbar lordosis were significantly greater in LFEB than in LFE. The instability detection rate was 14.0% in LFE and 35.1% in LFEB. The FFI, maximum width, and mean width were significantly increased in the unstable lumbar spondylolisthesis group compared with the stable group in LFEB. The FFI and maximum width of the facet fluid were significantly increased in the unstable lumbar spondylolisthesis group compared with the stable group in LFE. CONCLUSIONS: Lumbar lateral flexion-extension radiographs with brackets can standardize the operation process and provide sufficient hyperflexion and hyperextension images. The width of the facet fluid and FFI are significant factors in the evaluation of lumbar stability in patients with lumbar spondylolisthesis.

External validation of the deep learning system "SpineNet" for grading radiological features of degeneration on MRIs of the lumbar spine.

BACKGROUND: Magnetic resonance imaging (MRI) is used to detect degenerative changes of the lumbar spine. SpineNet (SN), a computer vision-based system, performs an automated analysis of degenerative features in MRI scans aiming to provide high accuracy, consistency and objectivity. This study evaluated SN's ratings compared with those of an expert radiologist. METHOD: MRIs of 882 patients (mean age, 72 ± 8.8 years) with degenerative spinal disorders from two previous trials carried out in our spine center between 2011 and 2019, were analyzed by an expert radiologist. Lumbar segments (L1/2-L5/S1) were graded for Pfirrmann Grades (PG), Spondylolisthesis (SL) and Central Canal Stenosis (CCS). SN's analysis for the equivalent parameters was generated. Agreement between methods was analyzed using kappa (κ), Spearman correlation (ρ) and Lin's concordance correlation (ρc) coefficients and class average accuracy (CAA). RESULTS: 4410 lumbar segments were analyzed. κ statistics showed moderate to substantial agreement in PG between the radiologist and SN depending on spinal level (range κ 0.63-0.77, all levels together 0.72; range CAA 45-68%, all levels 55%), slight to substantial agreement for SL (range κ 0.07-0.60, all levels 0.63; range CAA 47-57%, all levels 56%) and CCS (range κ 0.17-0.57, all levels 0.60; range CAA 35-41%, all levels 43%). SN tended to record more pathological features in PG than did the radiologist whereas the contrary was the case for CCS. SL showed an even distribution between methods. CONCLUSION: SN is a robust and reliable tool with the ability to grade degenerative features such as PG, SL or CCS in lumbar MRIs with moderate to substantial agreement compared to the current gold-standard, the radiologist. It is a valuable alternative for analyzing MRIs from large cohorts for diagnostic and research purposes.

Current treatment and decision-making factors leading to fusion vs decompression for one-level degenerative spondylolisthesis: survey results from members of the Lumbar Spine Research Society and Society of Minimally Invasive Spine Surgery.

BACKGROUND: Degenerative spondylolisthesis (DS) is one of the most common pathologies spine surgeons treat. While a number of potential factors have been identified, there is no current consensus on which variables most impact the decision to fuse vs. decompress alone in this population. PURPOSE: The purpose of this study was to describe current DS treatment practices and identify both the radiographic and clinical factors leading to the decision to fuse segments for one level DS. STUDY DESIGN/SETTING: Descriptive cross-sectional survey. PATIENT SAMPLE: Surveys were administered to members of Lumbar Spine Research Society and Society of Minimally Invasive Spine Surgery. OUTCOME MEASURES: Surgeon demographics and treatment practices were reported. Radiographic and clinical parameters were ranked by each surgeon with regards to their importance. METHODS: The primary analysis was limited to completed surveys. Baseline characteristics were summarized. Clinical and radiographic parameters were ranked and compared. Ranking of each clinical and radiographic parameters was reported using best and worst rank, mean rank position, and percentiles. The most important, top 3 most important, and top 5 most important parameters were ordered given each parameter's ranking frequency. RESULTS: 381 surveys were returned completed. With regards to fusion vs. decompression, 19.9% fuse all cases, 39.1% fuse > 75%, 17.8% fuse 50%-75%, and 23.2% fuse <25%. The most common decompressive technique was a partial laminotomy (51.4%), followed by full laminectomy (28.9%). 82.2% of respondents instrument all fusion cases. Instability (93.2%), spondylolisthesis grade (59.8%), and laterolisthesis (37.3%) were the most common radiographic factors impacting the decision to fuse. With regards to the clinical factors leading to fusion, mechanical low back pain (83.2%), activity level (58.3%), and neurogenic claudication (42.8%) were the top 3 clinical parameters. CONCLUSIONS: There is little consensus on the treatment of DS, with society members showing substantial variation in treatment patterns with the majority utilizing fusion for treatment. The most common radiographic parameters impacting treatment are instability, spondylolisthesis grade, and laterolisthesis while mechanical low back pain, activity level, and neurogenic claudication are the most common clinical parameters.

The Utility of Flexion-Extension Radiographs in Degenerative Cervical Spondylolisthesis.

STUDY DESIGN: Retrospective radiologic analysis. OBJECTIVE: The aim was to investigate if lateral flexion-extension radiographs identify additional cases of degenerative cervical spondylolisthesis (DCS) that would be missed by obtaining solely neutral upright radiographs, and determine the reliability of magnetic resonance imaging (MRI) in diagnosis. SUMMARY OF BACKGROUND DATA: DCS and instability can be a cause of neck pain, radiculopathy, and even myelopathy. Standard anteroposterior and lateral radiographs and MRI of the cervical spine will identify most cervical spine pathology, but spondylolisthesis and instability are dynamic issues. Standard imaging may also miss DCS in some cases. METHODS: We compared the number of patients who demonstrated cervical spondylolisthesis on lateral neutral and flexion-extension radiographs in addition to MRI. We used established criteria to define instability as ≥2 mm of listhesis on neutral imaging, and ≥1 mm of motion between flexion-extension radiographs. RESULTS: A total of 111 patients (555 cervical levels) were analyzed. In all, 41 patients (36.9%) demonstrated cervical spondylolisthesis on neutral and/or flexion-extension radiographs. Of the 77 levels of spondylolisthesis, 17 (22.1%) were missed on neutral radiographs ( P ,0.05). Twenty levels (26.0%) were missed when flexion-extension radiographs were used alone ( P =0.02). Twenty-nine levels (37.7%) of DCS identified on radiograph were missed by MRI ( P =0.004). CONCLUSIONS: Lateral flexion-extension views can be useful in the diagnosis of DCS. These views provide value by identifying a significant cohort of patients that would be undiagnosed based on neutral radiographs alone. Moreover, MRI missed 38% of DCS cases identified by radiographs. Therefore, lateral radiographs can be a useful adjunct to neutral radiographs and MRI when instability is suspected or if these imaging modalities are unable to identify the source of a patient's neck or arm pain.

Correlation of bone density to screw loosening in dynamic stabilization: an analysis of 176 patients.

Although osteoporosis has negative impacts on lumbar fusion, its effects on screw loosening in dynamic stabilization remain elusive. We aimed to correlate bone mineral density (BMD) with screw loosening in Dynesys dynamic stabilization (DDS). Consecutive patients who underwent 2- or 3-level DDS for spondylosis, recurrent disc herniations, or low-grade spondylolisthesis at L3-5 were retrospectively reviewed. BMD was assessed by the Hounsfield Unit (HU) in vertebral bodies (VB) and pedicles with and without cortical bone (CB) on pre-operative computed tomography (CT). Screw loosening was assessed by radiographs and confirmed by CT. HU values were compared between the loosened and intact screws. 176 patients and 918 screws were analyzed with 78 loosened screws found in 36 patients (mean follow-up: 43.4 months). The HU values of VB were similar in loosened and intact screws (p = 0.14). The HU values of pedicles were insignificantly less in loosened than intact screws (including CB: 286.70 ± 118.97 vs. 297.31 ± 110.99, p = 0.45; excluding CB: 238.48 ± 114.90 vs. 240.51 ± 108.91, p = 0.88). All patients had clinical improvements. In conclusion, the HU values, as a surrogate for BMD, were unrelated to screw loosening in DDS. Therefore, patients with compromised BMD might be potential candidates for dynamic stabilization rather than fusion.

Strong association of type 2 diabetes with degenerative lumbar spine disorders.

Tantalizing connections between type 2 diabetes and degenerative lumbar spine disorders have become increasingly evident. However, the association of type 2 diabetes with degenerative lumbar spine disorders remains unclear. We sought to clarify the association between type 2 diabetes and lumbar spine disorders using nationwide data in Korea. Furthermore, we explored the association of diabetes with the prevalence of spinal procedures. The data in this study was obtained from Korean health claim database. Between 2016 and 2019, totals of 479,680 diabetes and 479,680 age- and sex-matched control subjects were enrolled. Patients with diabetes had more likely to have degenerative lumbar spine disorders and spinal procedures than controls. Using multivariate-adjusted analysis, patients with diabetes were at increased risk of being concomitantly affected by lumbar disc disorder [adjusted odds ratio 1.11 (95% confidence interval 1.10-1.12)], lumbar spondylotic radiculopathy [1.12 (1.11-1.13)], spondylolisthesis [1.05 (1.02-1.08)] and spinal stenosis [1.16 (1.15-1.18)], compared to controls. Furthermore, diabetic patients had an increased risk of undergoing lumbar spinal injection [1.13 (1.12-1.14)], laminectomy [1.19 (1.15-1.23)], and fusion surgery [1.35 (1.29-1.42)]. We demonstrated that type 2 diabetes was significantly associated with lumbar spine disorders and frequent spinal procedures. Our results suggest diabetes as a predisposing factor for lumbar spine disorders.

Thoracic degenerative spondylolisthesis-associated myelopathy: A case report.

RATIONALE: The thoracic spine is stabilized in the anteroposterior direction by the rib cage and the facet joints, thus thoracic degenerative spondylolisthesis is very uncommon. Here, we report a rare case of thoracic degenerative spondylolisthesis in which the lower thoracic region was the only region involved. PATIENT CONCERNS: We present the case of a 56-year-old Chinese female who suffered from thoracic degenerative spondylolisthesis. She had a 2-year history of gait disturbance and bilateral lower-extremity numbness. The initial imaging examinations revealed Grade I anterior spondylolisthesis and severe cord compression, as well as bilateral facet joint osteoarthritis at T11/12. DIAGNOSIS: The patient was diagnosed with thoracic degenerative spondylolisthesis-associated myelopathy. INTERVENTIONS: She underwent a posterior decompression with transforaminal thoracic interbody fusion (TTIF) at T11/12. OUTCOMES: The patient recovered well after the operation, and MRI at 12-month follow-up revealed that spinal cord compression was relieved and high signal intensity in T2-weighted image was improved. LESSONS: To the best of our knowledge, this is the first reported case of thoracic degenerative spondylolisthesis in which the lower thoracic region was the only region involved. Disruption of joint capsule, instability with micromotion, and degenerative disc may contribute to this rare disease. Posterior decompression with posterolateral fusion or TTIF were the main treatment modalities, however, TTIF has its unique advantages because of sufficient decompression, immediate stability and high fusion rate.

Spino Cranial Angle and Degenerative Cervical Spondylolisthesis.

OBJECTIVE: The purpose of our study was to analyze and compare the spino cranial angle (SCA) in patients with degenerative cervical spondylolisthesis (DCS) and asymptomatic controls and to determine whether SCA could help diagnose DCS. METHODS: We enrolled 50 patients diagnosed with DCS (4.3%) from among 1168 patients and the same number of asymptomatic participants as the control group by using cervical radiographs. Both groups underwent cervical radiographs and computed tomography at the same time. Various sagittal parameters were measured on computed tomography in a standardized supine position and compared with the asymptomatic control group. The Spearman correlation coefficient was applied to test the correlation among the sagittal parameters in the DCS group. Multivariate logistic regression analysis and receiver operating characteristic curve analysis were performed to determine whether SCA could help predict DCS. RESULTS: Fifty patients were enrolled in the DCS group, and 50 asymptomatic participants were included in the control group. The SCA was significantly lower for the DCS group than for the control group (76.84 ± 7.48 degrees vs. 82.47 ± 8.06 degrees, P < 0.001), and the T1 slope (T1s) was significantly greater for the DCS group than for the control group (27.29 ± 7.84 degrees vs. 22.28 ± 6.43 degrees, P = 0.001). Except for SCA and T1s, no other parameters showed significant differences. The SCA on the computed tomography scan was significantly correlated with the values of the T1s (r = -0.890, P < 0.001), cervical lordosis (r = -0.437, P = 0.002), C2-C7 sagittal vertical axis (r = 0.397, P = 0.004), and thoracic inlet angle (r = -0.565, P < 0.001). Multivariate logistic regression analysis and receiver operating characteristic curve analysis showed that both a lower SCA and a higher T1s could be risk factors for DCS, and an SCA of <79.1 degrees demonstrated significant diagnostic value for the detection of DCS. CONCLUSIONS: Patients in the DCS group had a lower SCA and a higher T1s. Both a lower SCA and a higher T1s could be risk factors for DCS, and an SCA of <79.1 degrees demonstrated significant diagnostic value for the detection of DCS.

Different Types of Double-Level Degenerative Lumber Spondylolisthesis: What Is Different in the Sagittal Plane?

BACKGROUND: Degenerative lumber spondylolisthesis (DLS) is a common orthopedic condition, described as a condition that compared with the lower vertebra, the superior vertebra slides forward or backward in the sagittal plane without accompanying isthmic spondylolisthesis. Information pertaining to different types of double-level DLS is scarce. This study aims to analyze parameters of patients with different types of double-level DLS to provide a reference for guiding surgical treatment and restoring sagittal balance of patients with DLS. METHODS: From January 2014 to January 2020, records of patients with double-level DLS were retrospectively reviewed. Patients with double-level DLS were divided into 3 types: anterior, posterior, and combined; the anterior and combined types were studied. The sagittal spinopelvic parameters included C7 tilt, maximal thoracic kyphosis, maximal lumbar lordosis (LLmax), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). After descriptive analysis, demographic and radiographic data were compared. RESULTS: Forty and 18 patients were included in the anterior and combined type groups, respectively. Both groups had different levels of chronic low back pain, but the incidence of radiating leg pain and neurogenic claudication was significantly higher in the anterior type. Oswestry Disability Index and visual analog scale low back scores were also higher in the anterior type. In the anterior type, C7 tilt (7.14 ± 2.15 vs. 5.41 ± 2.28, P = 0.007), LLmax (50.02 ± 14.76 vs. 36.96 ± 14.56, P = 0.003), PI (68.28 ± 9.16 vs. 55.53 ± 14.19, P < 0.001), PT (28.68 ± 7.31 vs. 19.38 ± 4.70, P < 0.001), and PT/PI (42.45 ± 11.22 vs. 36.04 ± 9.87, P = 0.041) were significantly higher. In the anterior type, PI correlated positively with LLmax (r = 0.59) and SS (r = 0.71). LLmax and SS (r = 0.65) had a positive correlation. PT/PI and SS (r = -0.77) had a negative correlation. In the combined type, PI correlated positively with LLmax (r = 0.61) and SS (r = 0.88), and PT/PI correlated negatively with SS (r = -0.81). CONCLUSIONS: In patients with double-level DLS, the sagittal spinopelvic parameters differed between the anterior and combined types. Overall, spinal surgeons should focus on correcting sagittal deformities, relieving postoperative clinical symptoms, and improving quality of life during fusion surgery.

Modifications in lumbar facet joint are associated with spondylolisthesis in the degenerative spine diseases: a comparative analysis.

BACKGROUND: Magnetic resonance imaging (MRI) is important in the assessment of degenerative spine disease. However, its role is limited in the identification of spinal instability; therefore, weight-bearing and dynamic studies like X-rays are required. The supine position eliminates the gravitational pull, corrects the vertebral slippage, and opens the facet joints leading to the collection of the synovial fluid into the joint space, which is detected on the MRI and can serve as a marker for instability. We aim to compare the facet fluid, facet hypertrophy, facet angle, and disc degenerative changes among the patients presenting with degenerative spondylolisthesis (DS) and those without. METHODS: We performed a retrospective review for all the patients treated at our institution from January 2015 to December 2016. Facet Fluid Index (FFI) (ratio of facet fluid width and facet joint width) was calculated to assess the joint fluid. The percentage of spondylolisthesis was measured on X-rays. Each radiological parameter was compared between the two groups, i.e., patients with DS and patients without DS. A p value < 0.05 was considered significant. RESULTS: In total, 61 patients, 28 with DS and 33 without DS, were enrolled. Baseline characteristics were similar in the two groups (p > 0.05). The average values of FFI, facet fluid width, and the difference between the superior and inferior facet were significantly higher in the group with instability (p < 0.05). Multivariate analysis demonstrated a 4.44 (95% confidence interval [CI] 2.03-5.365) times increase in the odds of instability with a unit increase in FFI, p < 0.0001. CONCLUSIONS: We report a positive linear correlation between the facet joint effusion and facet hypertrophy on MRI and the percentage of vertebral translation on X-ray. Prospective studies will determine if these markers can play a role in predicting spinal instability.

Bone Formation During Correction of Vertebral Rounding Deformity in a Rat Model of Pediatric Spondylolisthesis.

STUDY DESIGN: A study using rat spondylolisthesis models. OBJECTIVE: The aim of this study was to elucidate the mechanism for correction of vertebral rounding deformity. SUMMARY OF BACKGROUND DATA: Vertebral rounding deformity is the strongest risk factor for high-grade slippage associated with spondylolisthesis in adolescents. We previously reported that inadequate endochondral ossification of the anterior upper corner of the vertebral growth plate in response to mechanical stress could be the pathological mechanism of vertebral rounding deformity. METHODS: We created a model of spondylolisthesis using 4-week-old rats. They were divided into a tail suspension group that underwent tail suspension to decrease mechanical stress starting at 2 weeks postoperatively and a ground control group with no intervention. Radiographs and microcomputed tomography scans were obtained once weekly for 6 weeks postoperatively. The lumbar spines were then harvested for histological analysis. Immunohistochemical studies detected types I, II, and X collagen in the growth plate cartilage. Bone histomorphometrical analysis was also performed. RESULTS: Radiological and histological evidence in the ground control group showed progress the rounding deformity with time as previously reported. Formation of normal cancellous bone was observed radiologically over time in the tail suspension group, indicating correction of rounding deformity. Histologically, the site showing radiological evidence of correction was derived from cartilage tissue. After starting tail suspension, the growth plate stained positive for type X collagen and the corrected site stained for types II and X collagen in a mosaic pattern. Chondrocytes expressing types I and II collagen and tartrate-resistant acid phosphatase-positive cells were also present at the corrected site. Histomorphometrically, more endochondral bone was detected at the corrected site than in the posterior aspect of the normal growth plate. CONCLUSION: Correction of vertebral rounding deformity was associated with improvement of chondrocyte differentiation; furthermore, there is possible involvement of a third mechanism, namely transchondroid bone ossification.Level of Evidence: N/A.

Lumbar Vertebral Endplate Defects on Magnetic Resonance Imaging in Degenerative Spondylolisthesis: Novel Classification, Characteristics, and Correlative Factor Analysis.

BACKGROUND: Endplate defects are commonly seen in patients with lumbar degenerative disease. However, little is known about the presence of endplate defects in patients with degenerative spondylolisthesis (DS). In the present study, we have introduced a classification system for endplate defects in patients with DS using routine magnetic resonance imaging findings and explored the correlative factors. METHODS: Endplate defects were classified into 3 major categories (rim defects, focal defects, and erosive defects) and 5 subtypes (anterior type, posterior type, arc type at the anterior rim, notch type, and Schmorl's nodes). The incidence rates of the endplate defects were compared between the slippage and nonslippage levels. The correlations between the endplate defects and age, sex, disc degeneration, Modic changes (MCs), body mass index, slippage segment, and slippage degree were analyzed. RESULTS: Endplate defects were present in 47.43% of the endplates in DS. The most common endplate defects were rim defects. The occurrence of endplate defects, especially anterior defects, was more common at the slippage levels. Endplate defects were associated with age and closely related to MCs and the severity of disc degeneration. The slippage degree, slippage segment, body mass index, and sex differences were not associated with endplate defects in our study. The results obtained using this novel classification system were stable and consistent. CONCLUSIONS: The results from the present study have shown that the novel radiological classification system of endplate defects is reliable. Endplate defects were associated with slippage but not with the slippage degree or slippage segment differences in DS. The correlation between endplate defects and age and between MCs and disc degeneration were important features on the magnetic resonance imaging scans of patients with DS.