Morphological changes in the human cervical intervertebral disc post trauma: response to fracture-type and degeneration grade over time.

PURPOSE: In the first 24 h post-intervertebral disc (IVD) trauma, up to 75 % cell death has been reported. In addition, burst fractures cause post-traumatic disc degeneration by elevated pro-apoptotic and pro-inflammatory gene transcription. Moreover, some patients have pre-trauma degenerative disc disease. The aim of the study was to assess histological changes and cell-death over a time period of up to 1 year caused by mechanical and structural factors. METHODS: 116 anterior portions of IVDs of the cervical spine were studied histologically by light microscopy and ultrastructurally by transmission electron microscopy (TEM). The group was investigated with regard to three main parameters: fracture mechanism (compressive vs. tensile/shear loads), degeneration grade (low vs. high) and endplate fracture (with vs. without). Disc architecture (e.g. ruptures) was studied histologically. Cell morphology was examined ultrastructurally to quantify cell-death, healthy and balloon cells. According to ultrastructural observations, two time-groups (up to 6 days vs. later) were established. Statistical analyses were carried out within and between time-groups. RESULTS: Histological changes were obvious in the annulus fibrosus where ruptures with haematoma were replaced by granulation tissue. Significant differences in cell-death were seen in the first few days due to different loads. In contrast to the more degenerated segments, low degenerated ones revealed significantly less cell death with time post-trauma. Interestingly, no difference was found between groups after the sixth day. Cell-death (mean 44 % for all investigated groups) remained high after day 6 post-trauma. CONCLUSION: IVDs retrieved from low grade degenerated segments revealed a significant recovery, with less cell-death and a partially restored disc matrix, although cell-death remained high. Long-term clinical studies of stabilized segments arising from different fracture mechanisms are required.

Morphological similarities after compression trauma of bovine and human intervertebral discs: Do disc cells have a chance of surviving?

To study the behavior of bovine disc cells and changes in disc matrix following in vitro compression tests; to compare the findings to investigations on human intervertebral discs (IVD) after burst fracture of the cervical spine. Healthy IVDs (n = 21) from three bovine tails were studied at 6 and 12 h post-mortem, with 16 IVDs subjected to impact loading and five as unloaded controls. IVDs (n = 8) from patients with burst fractures were compared to the bovine compression group. Specimens were studied macroscopically, histologically, and ultrastructurally for healthy cells, balloon cells, and disc cell death (DCD). Annulus ruptures were seen in both post-trauma groups, with radial ruptures being present histologically in all loaded bovine discs. Balloon cells were found in some human IVDs and were induced in vitro in bovine loaded discs within a distinct range of absorbed energy. There was a positive correlation between DCD and absorbed energy in all compartments of bovine discs. Both species showed similar patterns of DCD in the different compartments. This study was able to show similarities between both species in cell morphologies and matrix damage. The survival of the disc after substantial compression trauma thus seems to remain highly questionable.

Morphological differences in adolescent idiopathic scoliosis: a histological and ultrastructural investigation.

STUDY DESIGN: Histological and ultrastructural evaluation of cell morphologies at the concave and convex side of apical intervertebral discs (IVD) of adolescent idiopathic scoliosis (AIS). OBJECTIVE: To determine changes in cell morphology, viability, and cell death after asymmetric disc loading in AIS and to compare the findings with the tilt angles. SUMMARY OF BACKGROUND DATA: The reaction of cells to loading stimuli in the IVD seems to be specific. Although dynamic loads are more beneficial to the disc cells and maintain the matrix biosynthesis, static compressive loads suppress gene expression. METHODS: Apical IVDs (Th8-Th9 to L1-L2) from 10 patients with AIS were studied histologically (including TUNEL [TdT-mediated dUTP-biotin nick end labeling] staining to identify disc cell death by apoptosis) and ultrastructurally for matrix evaluations and to quantify healthy, balloon, chondroptotic, apoptotic, and necrotic cells on the concave and convex sides. Patients' spines were classified according to the Lenke classification. Degeneration was assessed according to the Pfirrmann grading system. Two groups were established; group 1 (G1) with a tilt of 5° to 9° and group 2 (G2) with a tilt of 10° to 19°. RESULTS: Balloon cells were found in significantly higher numbers at the concave side (G1-annulus fibrosus [AF]: mean 16%), with almost none found at the convex side. Mean numbers of healthy cells did not show differences comparing both sides. Significantly higher numbers of healthy cells were found with increasing tilt angle at the concave side. Necrosis (mean, 47%) increased toward the center of the disc but did not differ between the sides of the IVDs. The fibrils found in the outer AF on the convex side were 30% thinner. CONCLUSION: This study was able to show significant differences in cell morphologies in the AF on both sides and in correlation to the different tilt angles. The type and magnitude of load seem to influence disc cells. Further studies are required to provide more information on disc and cell changes in scoliosis.

Morphological changes in disc herniation in the lower cervical spine: an ultrastructural study.

INTRODUCTION: The basis of disc degeneration is still unknown, but is believed to be a cell-mediated process. Apoptosis might play a major role in degenerative disc disease (DDD). The aim of this study was to correlate the viability of disc cells with the radiological degeneration grades (rDG) in disc herniation. MATERIALS AND METHODS: Forty anterior IVD's (C4-C7) from 39 patients with DDD were studied histologically and ultrastructurally to quantify healthy, "balloon", chondroptotic, apoptotic and necrotic cells. Patients were classified to their rDG, as having either prolapse (P: DGII + III) and/or osteochondrosis (O: DGIV + V). Similar studies were undertaken on eight control discs. RESULTS: Cell death by necrosis (mean 35%) was common but differed not significantly in both groups. All patients with a disc prolapse DGII + III revealed balloon cells (iAF: mean 32%). All appeared alive and sometimes were hypertrophic. However, significantly less balloon cells were found in the O-Group. Control samples revealed no evidence of "balloon" cells in DGII and only a minor rate in DGIII. CONCLUSION: According to the different rDG, quantitative changes were obvious in healthy and "balloon" cells, but not for cell death. At the moment it can only be hypothesized if "balloon" cells are part of a repair strategy and/or cause of disc herniation.

Mid-term results of PLIF/TLIF in trauma.

Treatment of thoracolumbar fractures is still controversial. Several treatment options are reported to yield satisfactory results. There is no evidence indicating superiority of any treatment option. We have already presented radiological results of the use of PLIF/TLIF in trauma, which showed satisfactory results concerning intervertebral fusion and acceptable loss of correction. We examined 50 patients regarding loss of correction after implant removal and clinical outcome using a validated visual analogue score. The average time of follow-up (FU) was 35 months. We observed a total loss of correction of 4°. The pre-injury mean VAS score was 92. At FU, there was an average reduction of 17.2 points. Owing to the presented results, we suggest this method as an alternative to combined procedures.

A biomechanical rationale for C1-ring osteosynthesis as treatment for displaced Jefferson burst fractures with incompetency of the transverse atlantal ligament.

Nonsurgical treatment of Jefferson burst fractures (JBF) confers increased rates of C1-2 malunion with potential for cranial settling and neurologic sequels. Hence, fusion C1-2 was recognized as the superior treatment for displaced JBF, but sacrifies C1-2 motion. Ruf et al. introduced the C1-ring osteosynthesis (C1-RO). First results were favorable, but C1-RO was not without criticism due to the lack of clinical and biomechanical data serving evidence that C1-RO is safe in displaced JBF with proven rupture of the transverse atlantal ligament (TAL). Therefore, our objectives were to perform a biomechanical analysis of C1-RO for the treatment of displaced Jefferson burst fractures (JBF) with incompetency of the TAL. Five specimens C0-2 were subjected to loading with posteroanterior force transmission in an electromechanical testing machine (ETM). With the TAL left intact, loads were applied posteriorly via the C1-RO ramping from 10 to 100 N. Atlantoaxial subluxation was measured radiographically in terms of the anterior antlantodental interval (AADI) with an image intensifier placed surrounding the ETM. Load-displacement data were also recorded by the ETM. After testing the TAL-intact state, the atlas was osteotomized yielding for a JBF, the TAL and left lateral joint capsule were cut and the C1-RO was accomplished. The C1-RO was subjected to cyclic loading, ramping from 20 to 100 N to simulate post-surgery in vivo loading. Afterwards incremental loading (10-100 N) was repeated with subsequent increase in loads until failure occurred. Small differences (1-1.5 mm) existed between the radiographic AADI under incremental loading (10-100 N) with the TAL-intact as compared to the TAL-disrupted state. Significant differences existed for the beginning of loading (10 N, P = 0.02). Under physiological loads, the increase in the AADI within the incremental steps (10-100 N) was not significantly different between TAL-disrupted and TAL-intact state. Analysis of failure load (FL) testing showed no significant differences among the radiologically assessed displacement data (AADI) and that of the ETM (P = 0.5). FL was Ø297.5 +/- 108.5 N (range 158.8-449.0 N). The related displacement assessed by the ETM was Ø5.8 +/- 2.8 mm (range 2.3-7.9). All specimens succeeded a FL >150 N, four of them >250 N and three of them >300 N. In the TAL-disrupted state loads up to 100 N were transferred to C1, but the radiographic AADI did not exceed 5 mm in any specimen. In conclusion, reconstruction after displaced JBF with TAL and one capsule disrupted using a C1-RO involves imparting an axial tensile force to lift C0 into proper alignment to the C1-2 complex. Simultaneous compressive forces on the C1-lateral masses and occipital condyles allow for the recreation of the functional C0-2 ligamentous tension band and height. We demonstrated that under physiological loads, the C1-RO restores sufficient stability at C1-2 preventing significant translation. C1-RO might be a valid alternative for the treatment of displaced JBF in comparison to fusion of C1-2.

PLIF in thoracolumbar trauma: technique and radiological results.

Patients with fractures from the 11th thoracic to the 5th lumbar vertebra had a reconstruction of the anterior column with monocortical iliac crest autograft by using a single dorsal approach. The loss of correction was observed using X-rays pre- and post-operatively, at 3 months and after implant removal (IR). Successful fusion was assessed using computed tomography after the implant removal. To assess the loss of correction and intervertebral fusion rate of this technique. There are still controversial discussions about the treatment modalities of spine lesions, especially in cases of burst fractures. Dorsal, combined and ventral procedures are reported with different assets and drawbacks. We want to present a method to restore the weight-bearing capability of the anterior column using a single dorsal approach. From 2001 to 2005, a total of 100 patients was treated with this technique at our department. Follow-up examination was possible in 82 patients. The X-rays and CT scans were proofed for loss of correction and fusion rate. The anterior column has been restored using a monocortical strut graft via a partial resection of the lamina and the apophyseal joint on one side to access the disc space. The dorsal reduction has been achieved using an angular stable pedicle screw system. The mean follow-up time was 15 months (range 8-39); 67 patients had a CT scan at follow-up and 83% showed a 360 degrees fusion. The average post-operative loss of correction was 3.3 degrees (range 0-21). The average duration of operation was 192 min (range 120-360) and the mean blood loss was 790 ml (range 300-3,400 ml). Regarding the complications we did not have any deep wound infections. We had two epidural haematomas postoperatively with a neurological deterioration that had to be revised. We were able to decompress the neurological structures and restore the weight-bearing capability of the anterior column in a one-stage procedure. So we think that this technique can be an alternative procedure to combined operations regarding the presented radiological results of successful fusion and loss of correction.

Study on accuracy and interobserver reliability of the assessment of odontoid fracture union using plain radiographs or CT scans.

In odontoid fracture research, outcome can be evaluated based on validated questionnaires, based on functional outcome in terms of atlantoaxial and total neck rotation, and based on the treatment-related union rate. Data on clinical and functional outcome are still sparse. In contrast, there is abundant information on union rates, although, frequently the rates differ widely. Odontoid union is the most frequently assessed outcome parameter and therefore it is imperative to investigate the interobserver reliability of fusion assessment using radiographs compared to CT scans. Our objective was to identify the diagnostic accuracy of plain radiographs in detecting union and nonunion after odontoid fractures and compare this to CT scans as the standard of reference. Complete sets of biplanar plain radiographs and CT scans of 21 patients treated for odontoid fractures were subjected to interobserver assessment of fusion. Image sets were presented to 18 international observers with a mean experience in fusion assessment of 10.7 years. Patients selected had complete radiographic follow-up at a mean of 63.3 +/- 53 months. Mean age of the patients at follow-up was 68.2 years. We calculated interobserver agreement of the diagnostic assessment using radiographs compared to using CT scans, as well as the sensitivity and specificity of the radiographic assessment. Agreement on the fusion status using radiographs compared to CT scans ranged between 62 and 90% depending on the observer. Concerning the assessment of non-union and fusion, the mean specificity was 62% and mean sensitivity was 77%. Statistical analysis revealed an agreement of 80-100% in 48% of cases only, between the biplanar radiographs and the reconstructed CT scans. In 50% of patients assessed there was an agreement of less than 80%. The mean sensitivity and specificity values indicate that radiographs are not a reliable measure to indicate odontoid fracture union or non-union. Regarding experience in years of all observers taking part in the study, there were no significant differences for specificity (P = 0.88) or sensitivity (P = 0.26). Further analysis revealed that if a non-union was judged present by an observer then, on average, each observer changed decision regarding the presence of a 'stable' or 'unstable non-union' in 4.2 of all the 21 cases (range 0-8 changes per observer). We investigated the interobserver reliability of the assessment of fusion in odontoid fractures using biplanar radiographs compared to CT scans. A sensitivity of 77% and a specificity of 62% for the radiographs resemble a substantial lack of agreement if different observers evaluate odontoid union. Biplanar radiographs are judged not a reliable measure to detect odontoid fracture union or non-union. The union rates of odontoid fractures have to be revisited and CT scans as the endpoint anchor in outcome studies of treatment related union rates are recommended.

Intervertebral disc cell death in the porcine and human injured cervical spine after trauma: a histological and ultrastructural study.

STUDY DESIGN: Histologic and ultrastructural study of disc cell death after traumatic injury to the human cervical spine and postmortem (p-m) in the porcine cervical spine. OBJECTIVE: To determine the changes in disc cell morphology, viability, and manner of cell death after trauma in human discs and p-m in porcine discs. SUMMARY OF BACKGROUND DATA: Similarities in the morphology of human and porcine spine have been shown in many histologic and biomechanical investigations. It is known that compressive or traumatic injuries to cartilage and intervertebral discs can result in cell death by necrosis or apoptosis. An additional form of apoptosis, chondroptosis, has been reported in articular cartilage, but not to date in the disc. METHODS: The anterior portion of intervertebral discs and endplates of 30 patients with traumatic injuries to the cervical spine were studied histologically (including trypan blue exclusion and TUNEL staining) and ultrastructurally. Fractures were classified according to Magerl and degeneration of the intervertebral disc according to Thompson and Benneker. Similar studies of disc and endplate were undertaken on porcine cervical spine 0 to 24 hours p-m. RESULTS: Electron and light microscopy showed up to 75% of human disc cells die within the first 24 hours of trauma, mainly by necrosis, similar to that seen in pig discs p-m. This study reports on 2 morphologies, chondroptosis and balloon cells, previously not described in the disc. Chondroptosis had been significantly higher and ballooned cells were exclusively seen in discs from fractures with compression, where apoptosis was also most common. Porcine samples revealed comparable rates of apoptosis and chondroptosis as fractures with less compression. Glycogen was commonly found in disc cells after trauma. CONCLUSION: Traumatic injuries of the human cervical spine lead to rapid changes in disc cell morphology and cell death, particularly via necrosis. The type of fracture and load seems to influence cell death.