Petr Suchomel

Heterotopic ossification in total cervical artificial disc replacement.

Study Design. Prospective clinical study enrolled in 2 centers (Munich and Liberec) as part of a prospective European multicenter study with ProDisc C (Synthes Inc., Paoli, PA). Objectives. The first goal of the study was to evaluate the rate of heterotopic ossifications identified with plain radiograph following total cervical disc replacement (TCDR). The second goal was to show whether segmental motion can be preserved, and whether TCDR can provide improvement of the patient’s ability to perform activities of daily living as well as a decrease of pain. Summary of Background Data. Only a few reports about the radiologic outcome after TCDR are published so far. Heterotopic ossification is a well-known phenomenon after total hip arthroplasty. The rate of heterotopic ossification following TCDR is unclear. Methods. The radiographs of 54 patients (in total, 77 implanted prostheses) were analyzed 1 year after TCDR with a ProDisc C prosthesis. We classified the heterotopic ossification in 5 grades according to a recently published classification system for lumbar total disc replacement. For clinical parameters, the visual analog scale and the Neck Disability Index were evaluated preoperatively and 1 year postoperatively. The Student t test and Wilcoxon test were used for statistical analysis. Results. In 26 treated segments (33.8%), no heterotopic ossification was detectable. Grade 1 ossifications were present in 6 levels (7.8%). A total of 30 segments (39.0%) showed grade 2 ossifications. Heterotopic ossifications that led to restrictions of the range of motion were present in 8 cases (10.4%). One year postoperatively, 7 cases (9.1%) had a spontaneous fusion of the treated segment. The clinical parameters improved significantly and were similar to previous reports about TCDR. Conclusions. Only 33.8% of the patients did not show any signs of heterotopic ossification, and the rate of spontaneous fusion after TCDR 1 year after surgery was unexpectedly high. There were 49.4% of the patients with grade 2-3 ossification, which lets us suspect an even higher rate of spontaneous fusion after long-term follow-ups. Motion preservation after TCDR is only guaranteed if spontaneous fusion can be prevented. Thus, mobility of the implanted segments needs to be further studied.

Autologous versus allogenic bone grafts in instrumented anterior cervical discectomy and fusion: a prospective study with respect to bone union pattern

BackgroundThe purpose of this prospective semi-randomised comparative study was to compare fusion rates, course of fusion, and occurrence of collapse and subsidence of autologous and allogenic bone grafts in instrumented anterior cervical fusion. The number of fused levels and the smoking status were investigated as potential factors influencing the bone-healing process. No similar prospective study on instrumented anterior cervical discectomy and fusion was found in the literature.MethodsSeventy-nine consecutive patients were operated on using the Smith–Robinson technique with a single instrumentation system at one or two levels. Seventy-six cadaverous fibular bone grafts and 37 autologous iliac-crest bone grafts were inserted. All patients were followed up for at least 2 years.ResultsThe radiographs obtained during the follow-up were analysed, and showed no statistical difference in fusion and collapse rate between autografts and allografts. Allografts showed significantly longer time to union. No case of graft migration was observed. No difference was found between fusion and collapse rate with respect to the number of fused levels in general, but greater time to union was seen in two-level fusions. When one- and two-level subgroups were compared, there was no evidence of any significant difference in fusion or collapse rates between autografts and allografts, and the healing process took longer in allogenic grafts. Smoking status did not alter any of the fusion or collapse rates, or the course of bone fusion.ConclusionsThis study demonstrates that allografts are suitable substitutes for autografts in instrumented ACDF. Prolonged time to union observed in allogenic bone grafts does not seem to be an important factor in instrumented procedures. Two-level grafting does not imply a significantly lower fusion rate, but longer time to union can be expected than with single-level instrumented procedures in both allograft and autograft subgroups. Our relatively small number of patients may not have been sufficient to decipher significant differences between smokers and non-smokers in the rate or course of fusion as previously reported.

Prognostic factors in intramedullary astrocytomas: a literature review

Astrocytomas affect a significant portion of patients with intramedullary tumors. These infiltratively growing tumors are treated by a variety of methods—biopsy and decompressive surgery, maximal safe resection, adjuvant oncological therapy. Also, numerous prognostic factors are reported in the literature. Better understanding of factors that influence prognosis may help in treatment planning with the goal of prolonging survival. We have thus undertaken an extensive literature review in order to define factors affecting prognosis. A total of 38 articles were studied. Only tumor grade was consistently reported as the major factor affecting prognosis. The influence of other clinical factors (age, gender, history length, functional status, tumor location or extent, syrinx or cyst presence) can be speculated upon, but cannot be assessed adequately from the available literature. For both low- and high-grade (HG) astrocytomas, maximal safe tumor resection should be the primary treatment objective but is often not feasible in contrast to other intramedullary and spinal neoplasms. Since the biological nature of spinal cord HG glioma is identical to that of the brain, the same treatment algorithm of maximal safe resection followed by concomitant radio- and chemotherapy would be sensible to implement.

CT-guided internal fixation of a hangman's fracture.

Abstract Most hangman’s fractures are treated conservatively. If surgery is indicated, an anterior approach using a C2/C3 graft and plate fusion is usually preferred. Another surgical method according to Judet is direct transpedicular osteosynthesis by the dorsal approach. This surgery is frequently rejected because of the high risk of spinal cord damage or vertebral artery tear. Direct transpedicular osteosynthesis of hangman’s fracture according to Judet is a “physiological operation” that does not cause fusion and creates anatomical conditions. This procedure enables appropriate reduction, compression of fragments and immediate stabilization of the C2 segment. A new aspect of Judet’s method of internal fixation of a hangman’s fracture is now proposed. Computed tomographic (CT) guidance is used to ensure safe and exact introduction of two screws from the posterior approach. This method of CT-guided internal fixation of hangman’s fracture allows, preoperatively, for an accurate assessment of the pattern and course of fracture line, selection of the anatomically safest screw path and determination of an appropriate screw length. The procedure also allows for accurate intraoperative control of instrument and implant placement, screw tightening, fracture reduction and anchoring of the screw tip in the contralateral cortex, using repeated CT scans. The procedure is performed in a CT unit under sterile conditions. This method was used in the treatment of eight male and two female patients aged 21–71 years. All treated patients were without neurological deficit. Follow-up ranged from 12 to 57 months (mean 33.3 months). No intraoperative or early or late postoperative complications were apparent. This new aspect of the surgical procedure ensures highly accurate screw placement and minimal risks, and fully achieves the “physiological” internal fixation.

Pyogenic osteomyelitis of the odontoid process: single stage decompression and fusion.

Study Design. A case report. Objectives. To document our experience with single stage decompression and fixation in the treatment of pyogenic osteomyelitis of the odontoid process. Summary of Background Data. Although several investigators have reported a handful of these unusual cases, up until now, there have been no studies concerning a single stage solution in the surgical treatment of this pathology. Methods. Three patients with osteomyelitis of the odontoid process caused by Staphylococcus aureus underwent surgical treatment in single sessions (transoral decompression combined with posterior fusion as the second step of the operation). Following surgery, the patients underwent a 6-week antibiotic course administered both intravenously and orally. Furthermore, we recommended the use of a hard cervical collar for 8 weeks together with isometric rehabilitation of the cervical muscles. Currently, follow-up results are available for two patients. Results. On examination at 3 months, 6 months, and 1 year after the surgery, both patients had completely recovered with no neurologic deficit. Plain radiographs showed complete posterior fusion after 6 and 12 months, respectively. Conclusions. We emphasize the advantages of our method in comparison with nonoperative treatment or multisession surgery. The single stage surgical solution led to a shortening of hospitalization time with no need for halo bracing, to excellent results with respect to C-spine stability and to better compliance from the patients.

Mesenchymal stem cells isolated from the human bone marrow: cultivation, phenotypic analysis and changes in proliferation kinetics.

Mesenchymal Stem Cells (MSCs) are rare elements living in various organs (e.g., bone marrow), able to differentiate into specialized tissues, such as bone, cartilage, tendon, and myocardium. Since the first description of MSCs by Fridenshtein, several investigators have shown that these cells can also differentiate into chondrocytes, adipocytes, and, at least, in rodents into skeletal myoblasts. Later on, more primitive progenitor cells were characterized, able to give rise not only to limb-bud mesoderm, but also to cells of visceral mesoderm. Those cells were named mesodermal progenitor cells (MPCs). The aim of our study was to characterize and compare the biological properties and spontaneous differentiation potential of two different cell types (MSCs and MPCs) isolated from the human vertebral body bone marrow. The results of our experiments proved that the MPCs can be expanded beyond Hayflicks limit and differed from MSCs in morphology, biological and phenotypic characteristics. Because of their high proliferative and differentiation potential, MPCs can become more attractive source of adult stem cells for therapeutic purposes.

Four-year results of a prospective single-arm study on 200 semi-constrained total cervical disc prostheses: clinical and radiographic outcome.

OBJECTIVE Recent studies have described encouraging outcomes after cervical total disc replacement (cTDR), but there are also critical debates regarding the long-term effects of heterotopic ossification (HO) and the prevalence of adjacent-level degeneration. The aim in this paper was to provide 4-year clinical and radiographic outcome results on the activ C disc prosthesis. METHODS A total of 200 subjects underwent single-level activ C (Aesculap AG) implantation between C-3 and C-7 for the treatment of symptomatic degenerative disc disease. Clinical and radiographic assessments were performed preoperatively, intraoperatively, at discharge, and again at 6 weeks, 6 months, 1 year, 2 years, and 4 years. Radiographic evaluations were done by an independent core laboratory using a specific software for quantitative motion analysis. RESULTS Neck Disability Index (NDI) and visual analog scale (VAS) score for neck and arm pain decreased significantly from baseline to the 4-year follow-up. The mean improvement for NDI was 20, for VAS severity and frequency of neck pain 26.4 and 28, and for VAS severity and frequency of arm pain 30.7 and 35.1, respectively. The neurological situation improved for the majority of patients (86.4%); 76.1% of cases were asymptomatic. Subsequent surgical interventions were reported in 7% of the cases, including device removals in 3%. In 2.5% a subsidence greater than 3 mm was recorded; 1 of these cases also had a migration greater than 3 mm. No device displacement, expulsion, disassembly, loose or fractured device, osteolysis, or facet joint degeneration at the index level was observed. Segmental lordotic alignment changed from -2.4° preoperatively to -6.2° at 4 years, and postoperative height was maintained during the follow-up. Advanced HO (Grade III and IV) was present in 27.1% of the cases; 82.4% showed segmental mobility. A progression of radiographic adjacent-segment degeneration occurred in 28.2%, but only 4.5% required surgical treatment. CONCLUSIONS The activ C is a safe and effective device for cervical disc replacement confirming the encouraging results after cTDR. Clinical trial registration no.: NCT02492724 ( clinicaltrials.gov ).

Portable CT scanner-based navigation in lumbar pedicle screw insertion

Since the introduction of frameless stereotactic navigation systems for intra-cranial surgery, technology has progressed significantly [1]. Computer-assisted techniques became available for spine surgery in the 1990s and helped improve safety and accuracy, particularly in instrumented procedures. CT-based optoelectronic navigation in spine was originally suggested by Nolte et al. [2]. Amiot et al. [3] later performed successful in vitro testing, using a magnetic-field based navigator, which, however, never gained clinical acceptance. Laine et al. [4] presented evidence for improvement of optoelectronic technique accuracy under clinical conditions, and this became an option to support implant insertion in recent years. Navigation systems in clinical practice are nowadays based on computer tomography imaging (CT-based navigation) or on fluoroscopy imaging (twoor three dimensional fluoroscopy based navigation). The conventional CT-based navigation technique requires extensive preoperative preparation, including computed tomography with a defined protocol of data acquisition and transfer requirements, as well as a complex patient registration. The development of intraoperative CT scanning also addressed such issues. The conventional CT scanners can soon be expected to be replaced by portable CT scanners. The following paper aims to describe the intraoperative portable CT scanner image acquisition technique, data reconstruction and the planning for a screw trajectory, using a frameless stereotactic image-guidance system as well as demonstrating a safe pedicle screw placement.

Single stage total endolesional C2 spondylectomy for chordoma

Chordomas are locally invasive, malignant bone tumors, which rarely occur in the cervical spine [5, 12]. En-bloc, or even marginal resection, offers improved survival and potential cure. Complete resection of tumors, involving the upper cervical vertebrae, requires combined anterior and posterior approaches and is complicated by the presence of vertebral arteries. A reconstruction of the post-resection defect is prone to failure. We present a case of a chordoma, involving the axis that was treated by a single stage total endolesional C2 spondylectomy, with preservation of both vertebral arteries, as the patient did not tolerate preoperative occlusion test. A novel approach to the reconstruction is also presented.

Cervical total disc replacement C5/6

Anterior cervical discectomy and fusion (ACDF) was the standard treatment for cervical disc degenerative disease (CDDD), and an alternative to conservative therapy, for several decades [1]. While highly successful in the diseased segment, a fusion procedure is likely to be detrimental to the remaining motion segments [2, 3]. On the other hand, the cervical total disc replacement (CTDR) technique aims to decrease the incidence of adjacent segment disease (ASD) through motion pattern preservation, at both the operated level and the adjacent ones [4]. One of the most important issues of a successful CTDR application is the correct surgical indication and the proper insertion technique. Case description