David Kubosch

Long-term T2 and Qualitative MRI Morphology After First-Generation Knee Autologous Chondrocyte Implantation Cartilage Ultrastructure Is Not Correlated to Clinical or Qualitative MRI Outcome

Background: There are several reports on long-term clinical outcomes after autologous chondrocyte implantation (ACI) for knee cartilage defect treatment. Few published articles have evaluated defect quality using quantitative magnetic resonance (MR) imaging techniques. Purpose: To evaluate clinical outcomes and the quality of repair tissue (RT) after first-generation periosteum-covered ACI (ACI-P) using qualitative MR outcomes and T2-weighted relaxation times. Study Design: Case series; Level of evidence, 4. Methods: All patients (n = 86) who underwent knee joint ACI-P (from 1997 through 2001) with a postoperative follow-up of at least 10 years were invited for clinical and MR evaluation. Clinical outcomes analysis included pre- and postoperative Lysholm and numeric analog scale (NAS) for pain (10 = worst, 0 = best). Radiographic analysis included postoperative T2-weighted mapping of the RT, RT-associated regions, and healthy control cartilage; MOCART (magnetic resonance observation of cartilage repair tissue) score; a modified Knee Osteoarthritis Scoring System (mKOSS; 0 = best, 15 = worst) score; as well as numeric grading for subjective RT and whole knee joint evaluation (1 = best, 6 = worst). Results: A total of 70 patients (45 male, 25 female; mean age, 33.3 ± 10.2 years; 81% follow-up rate) with 82 defects were available for follow-up at an average 10.9 ± 1.1 years postoperatively, with MR analysis for 59 patients with 71 transplant sites (average defect size, 6.5 ± 4.0 cm2). Final Lysholm (71.0 ± 17.4) and NAS (7.2 ± 1.9) scores improved significantly when compared with preoperative scores (Lysholm: 42.0 ± 22.5; NAS: 2.1 ± 2.1; P < .01 for both). Average transplant T2 was 35.2 ± 11.3 ms and thereby significantly lower (P = .005) when compared to the intraknee healthy femur T2 (39.7 ± 6.8 ms). The MOCART was 44.9 ± 23.6 and mKOSS was 4.8 ± 3.2. RT subjective grading was 3.3 ± 1.4, while it was 2.3 ± 0.7 for whole joint evaluation. The RT T2 significantly correlated with postoperative NAS (P = .04; r = −0.28); it also correlated with the healthy femur T2 (P = .004; r = 0.4). The MOCART significantly correlated with the mKOSS (P < .001). Conclusion: The MRI outcome is imperfect in this collective of patients. There is only weak correlation of quantitative imaging data and clinical function. Qualitative imaging data are much better correlated to functional outcomes.

Effect of graft size on graft fracture rate after anterior lumbar spinal fusion in a sheep model

STUDY DESIGN Sheep anterior spinal fusion model with autogenous and xenogenous bone grafts. OBJECTIVE To investigate whether the relationship between cross-sectional area of the bone graft and area of the adjacent vertebral endplates has an effect on graft fracture rate. SUMMARY OF BACKGROUND DATA Anterior spondylodesis with autogenous iliac crest transplant is a frequently performed operation to stabilize spinal motion segments but to date no precise recommendations with respect to minimum graft size are available in the literature. METHODS Anterior spondylodesis using autogenous and xenogenous grafts of constant size in combination with an angular stable plate (Macs TL). Autogenous iliac crest graft was inserted in eight sheep and xenogenic, commercially available bovine graft (Tutobone) in the additional eight animals. The surface areas of the endplates of the fused intervertebral space were calculated using CT scans and contact radiographs of the specimens obtained after 24 weeks. The graft itself was evaluated for fractures and osteolysis. RESULTS A fracture occurred in tricortical, autogenous grafts if the graft cross-sectional area was less than 21% of the area of the adjacent endplates. All xenogenic grafts fractured and therefore a comparable value could not be determined. CONCLUSION The results clearly indicate that the relation between graft cross-sectional area and endplate area defines the survival or fracture of the graft in anterior spinal fusion. Although it is difficult to directly apply the results to the clinical situation it is suggested to choose a sufficiently large graft, in order to reduce the risk of autogenous graft fracture in anterior spondylodesis.

Detection of Bone Graft Failure in Lumbar Spondylodesis: Spatial Resolution with High-Resolution Peripheral Quantitative CT

OBJECTIVE In spinal surgery, anterior spondylodesis is often combined with bone grafting, and graft integration is assessed with CT. High-resolution peripheral quantitative CT offers a resolution of 82 mum. The aim of this study was to compare the outcome of anterior spondylodesis as assessed with three radiologic procedures. MATERIALS AND METHODS Monosegmental lumbar spondylodesis with autologous iliac crest graft or solvent-preserved bovine cancellous bone was performed on seven sheep. The fused spinal segments were explanted after 24 weeks and examined with clinical 64-MDCT, high-resolution peripheral quantitative CT, and contact radiography. In 2D views, the area of the disk space bridged by bone was assessed, and the grafts were examined for fractures. RESULTS In three of seven sheep, clinical CT erroneously showed stable consolidation, whereas contact radiography revealed a clearly visible graft fracture, as did high-resolution peripheral quantitative CT. There was a statistically significant difference (p = 0.038) between bone volume assessed with clinical CT and that assessed with contact radiography. There was an almost significant difference (p = 0.053) between volumes assessed with high-resolution peripheral quantitative CT and clinical MDCT. CONCLUSION High-resolution peripheral quantitative CT, a technique approved for clinical use, has higher resolution in imaging of bone structure than does 64-MDCT. Our results show that high-resolution peripheral quantitative CT is superior to 64-MDCT in assessing osseous implant integration after anterior spondylodesis. The specimen size limit, however, prohibits in vivo use of this method in evaluation of the human spine. Our results suggest that in clinical practice, persisting symptoms despite radiologic findings of consolidated spondylodesis may be related to graft failure, which cannot be detected with clinically available methods.

The Lumbar Spine as a Dynamic Structure Depicted in Upright MRI.

AbstractSpinal canal stenosis is a dynamic phenomenon that becomes apparent during spinal loading. Current diagnostic procedures have considerable short comings in diagnosing the disease to full extend, as they are performed in supine situation. Upright MRI imaging might overcome this diagnostic gap.This study investigated the lumbar neuroforamenal diameter, spinal canal diameter, vertebral body translation, and vertebral body angles in 3 different body positions using upright MRI imaging.Fifteen subjects were enrolled in this study. A dynamic MRI in 3 different body positions (at 0° supine, 80° upright, and 80° upright + hyperlordosis posture) was taken using a 0.25 T open-configuration scanner equipped with a rotatable examination bed allowing a true standing MRI.The mean diameter of the neuroforamen at L5/S1 in 0° position was 8.4 mm on the right and 8.8 mm on the left, in 80° position 7.3 mm on the right and 7.2 mm on the left, and in 80° position with hyperlordosis 6.6 mm (P < 0.05) on the right and 6.1 mm on the left (P < 0.001).The mean area of the neuroforamen at L5/S1 in 0° position was 103.5 mm2 on the right and 105.0 mm2 on the left, in 80° position 92.5 mm2 on the right and 94.8 mm2 on the left, and in 80° position with hyperlordosis 81.9 mm2 on the right and 90.2 mm2 on the left.The mean volume of the spinal canal at the L5/S1 level in 0° position was 9770 mm3, in 80° position 10600 mm3, and in 80° position with hyperlordosis 9414 mm3.The mean intervertebral translation at level L5/S1 was 8.3 mm in 0° position, 9.9 mm in 80° position, and 10.1 mm in the 80° position with hyperlordosis.The lordosis angle at level L5/S1 was 49.4° in 0° position, 55.8° in 80° position, and 64.7 mm in the 80° position with hyperlordosis.Spinal canal stenosis is subject to a dynamic process, that can be displayed in upright MRI imaging. The range of anomalies is clinically relevant and dynamic positioning of the patient during MRI can provide essential diagnostic information which are not attainable with other methods.

Biomechanical comparison of three types of bone graft for anterior spondylodesis

BACKGROUND Anterior spondylodesis with bone grafting for fusion of spinal motion segments is a common procedure in clinical routine. Bone grafts for fusion include autologous, allogenic and xenogenic grafts that are inserted in the unstable spinal motion segment. Nevertheless, biomechanical data for autologous, allogenic and xenogenic grafts are rare. OBJECTIVE The purpose of this study was to conduct biomechanical comparison of native and conserved bone grafts used in spondylodesis of the spine. METHODS Grafts examined were native ovine tricortical iliac crest grafts, bovine cancellous bone blocks and ovine, tricortical iliac crest grafts, conserved in the same way as the bovine cancellous bone blocks. The grafts were tested biomechanically to failure. Compared parameters were maximum torque, maximum rotation angle and graft stiffness at failure. The Mann-Whitney-U test with Bonferroni adjustment was used for statistical analysis. RESULTS Maximum torque at failure of the bovine cancellous bone graft did not differ significantly from that of the native ovine tricortical graft. Comparison of the conserved ovine tricortical graft revealed significantly lower values compared to the native ovine tricortical bone graft.Maximum rotation angle at failure of the untreated ovine tricortical bone grafts was significantly higher compared to the other grafts tested. Regarding graft stiffness no significant differences were found. CONCLUSIONS Based on the functional demands exerted on the spinal motion segment, our results suggest that torsional strength and deformational behavior of the bone graft influence the stability of the spondylodesis. The native tricortical graft best fulfills this requirement.

Sequential differentiation of human bone marrow stromal cells for bone regeneration

In this study we hypothesized that as a simulation of endochondral bone formation, bone marrow stromal cell (BMSC) provide a sequential chondro-osteogenic differentiation potential. A chondrogenic priming of BMSC leads to a spontaneous three-dimensional cell formation. BMSC were chondrogenically differentiated prior to an osteogenic stimulation. Duration of cell culture was 28 days, whereas in group A BMSC were chondrogenically differentiated for 1 day, followed by an osteogenic differentiation for 27 days. In group B BMSC were chondrogenically differentiated for 14 days prior to an osteogenic differentiation of 14 days and group C BMSC were differentiated chondrogenically for 28 days serving as a chondrogenic control group. Chondrogenic priming induced a spontaneous three-dimensional cell formation. To survey the stability of the osteogenic phenotype in the absence of an osteogenic stimulus, investigations were performed in vivo in a specially adapted chorioallantoic membrane model of fertilized White Leghorn eggs. Histology and real time polymerase chain reaction revealed a higher amount of osteogenic extracellular matrix synthesis and significant higher expressions of osteogenic marker genes in group B after 14 days of chondrogenic and 14 days of osteogenic stimulation. Matrix calcification in vivo in the absence of an osteogenic stimulus could be demonstrated. The results of the present study support the theory of a sequential differentiation potential of BMSC. A chondrogenic priming of BMSC stimulated into the osteogenic lineage result in a stable osteogenic phenotype in a scaffold-free, three-dimensional tissue engineering application.

Relationship between autologous bone graft osteointegration and correction loss after antero-posterior spondylodesis of traumatic vertebral body fracture

BACKGROUND A common method to restore the sagittal alignment and stabilize the spinal column is a dorso-ventral spondylodesis. It is assumed that correction loss after posttraumatic spondylodesis results from inadequate incorporation of the autologous iliac crest graft. MATERIALS AND METHODS Retrospective documentation of patients with unstable vertebral body fractures of the thoracic or lumbar spine with concomitant rupture of at least one adjacent intervertebral disk who received surgical treatment at our institution from 2000 to 2006. Followed by analysis of the computer tomography documentation of a total of 142 patients with unstable vertebral body fracture stabilized by posterior internal fixator and anterior iliac crest spondylodesis. RESULTS The following mean angle changes were derived from the second series of CT scans performed on average 283 days after anterior spondylodesis: vertebral wedge angle (VWA): 2.1°; segmental kyphotic angle: 4.9°; adjusted-SKA: 4.8°; sagittal index (SI): -0.04; segmental-scoliotic-angle (SSA): 0°; adjusted-SSA: 0°. Changes in VWA, both SKAs and SI postoperatively and prior to ME, were statistically significant (P<0.05). The McAfee fusion assessment of the graft showed: full fusion: cranial 64%, caudal 47%; partial fusion: cranial 20.5%, caudal 29%; lysis: cranial 8.5%, caudal 17%; graft resorption: 7%. No correlation was found between the above-mentioned angle changes and fusions grade. DISCUSSION The importance of radiological evidence of fusion deficiency is questionable, because the extent of fusion only has a minimal effect on correction loss. LEVEL OF EVIDENCE Level IV.

[Radiological comparison between two procedures for ventral spondylodesis: autologous iliac crest bone graft vs bovine bone graft].

BACKGROUND The objective of this study was the radiological evaluation of osseous integration of autologous iliac crest graft and bovine bone graft after spondylodesis based on a standardized score. MATERIAL AND METHODS Spondylodesis was performed on 18 sheep, divided into 2 groups, 1 with an autologous iliac crest graft and the other with a bovine bone graft. Computed tomography was performed 12 and 24 weeks postoperatively. The osseous integration was assessed by the Tübinger Score. RESULTS The evaluation of the CT scans demonstrated a significantly better osseous integration of the autologous iliac crest graft compared to the bovine bone graft. CONCLUSIONS Based on our results, the bovine bone graft as a transplant for spondylodesis is inadvisable.

Therapie der Humerusschaftfraktur

Fractures of the humeral shaft are less frequent than those of the proximal humerus. The formerly recommended treatment of humeral shaft fractures was conservative according to Böhler. This still remains an adequate concept of treatment but according to a change in the technical possibilities and the demands of patients and physicians on fast restoration of function and low pain, there is a trend towards surgical stabilization of humeral shaft fractures. The implant of choice is discussed controversially and consists of various types of nails versus plating. The technique of nailing is antegrade or retrograde and depends on the localization of the fracture. In our opinion good indications for plating are combined fractures of the proximal humerus and the shaft as well as very distal humeral shaft fractures. A primary lesion of the radial nerve is no imperative indication for exploration and different studies have shown the same results for exploration after 2 or 3 months if there is no spontaneous remission.

Therapy of humeral shaft fractures

Fractures of the humeral shaft are less frequent than those of the proximal humerus. The formerly recommended treatment of humeral shaft fractures was conservative according to Böhler. This still remains an adequate concept of treatment but according to a change in the technical possibilities and the demands of patients and physicians on fast restoration of function and low pain, there is a trend towards surgical stabilization of humeral shaft fractures. The implant of choice is discussed controversially and consists of various types of nails versus plating. The technique of nailing is antegrade or retrograde and depends on the localization of the fracture. In our opinion good indications for plating are combined fractures of the proximal humerus and the shaft as well as very distal humeral shaft fractures. A primary lesion of the radial nerve is no imperative indication for exploration and different studies have shown the same results for exploration after 2 or 3 months if there is no spontaneous remission.