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Biomedical subjects

M Reinhold

Publications and source records attributed to M Reinhold.

16 recordsLinked to original sources
PubMed2007

[An improved vertebral body replacement for the thoracolumbar spine. A biomechanical in vitro test on human lumbar vertebral bodies].

BACKGROUND: In recent years, the use of expandable titanium cages for vertebral body replacement in the thoracolumbar spine has been well established for the treatment of tumors, unstable traumatic lesions, or posttraumatic deformity. Collapse of the implant into the vertebral body remains a point of concern. A biomechanical compression test was designed to assess implant subsidence for a newly developed prototype for vertebral body replacement in the thoracolumbar spine using human cadaveric lumbar vertebrae. The objective of this study was to compare the compressive performance of a new expandable cage with modified end-plate design with three commonly available expandable cages for vertebral body replacement. MATERIALS AND METHODS: The compressive strengths at the implant-vertebral body interface were measured via axial loading of the new prototype (Synex II) in comparison with three different expandable titanium cages: Synex I (Synthes), Obelisc (Ulrich Medical) and X-Tenz (DePuy Spine). Twenty-four intact, fresh frozen human lumbar vertebrae (L1-L4) were distributed into four identical groups according to BMD (determined by quantitative computed tomography) and the vertebral level. Specimens were loaded in the craniocaudal direction with a material testing machine at a constant speed of 5 mm/min. Load displacement curves were continuously recorded for each specimen until failure (diminishment of compressive force (F)/obvious implant migration through the vertebral body endplate). One-way analysis of variance and post-hoc tests (Bonferroni) were applied to detect differences at 1, 2, 3, 4 mm displacement (F1-4 mm), and Fmax between implant groups. RESULTS: The four expandable cages did not show statistically significant biomechanical differences in terms of maximum compression force (Fmax) until failure: Synex II (1,782 N/4.7 mm); Synex I (1,645 N/4.7 mm); Obelisc (1,314 N/4.2 mm); X-Tenz (1,470 N/6.9 mm). However, the mean compression force until 4 mm displacement (F1-4 mm: 300-1,600 N) was highest for Synex II. The difference at 2 mm displacement was significant (p=0.028) between Synex II (F2 mm=879 N) and X-Tenz (F2 mm=339 N). CONCLUSION: The modified endplate design of the new prototype was found to improve its compressive performance under constrained uniaxial loading conditions at the implant-bone interface. The improved compressive behaviour of the new implant might help to reduce the risk of implant subsidence and collapse into the vertebral body in vivo.

Aged↗
PubMed2006

Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data.

This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS) placement using newly designed aiming devices. Transpedicular fixation is increasingly used for stabilizing the subaxial cervical spine. Development of the demanding technique is based on morphometric studies of the pedicle anatomy. Several surgical techniques have been developed and evaluated with respect to their feasibility and accuracy. The study was carried out on six conserved human cadavers (average age 85 years). Axes and dimensions of the pedicles C3-C7 (60 pedicles) were measured using multislice computed tomography (CT) images prior to surgery. Two groups consisting of 3 specimens and 30 pedicles each were established according to the screw placement technique. For surgical technique 1 (ST1) a para-articular mini-laminotomy was performed. Guidance of the drill through the pedicle with a handheld aiming device attached onto the medial aspect of the pedicle inside the spinal canal. Screw hole preparation monitored by lateral fluoroscopy. In surgical technique 2 (ST2) a more complex aiming device was used for screw holes drilling. It consists of a frame with a fully adjustable radiolucent arm for carrying the instruments necessary for placing the screws. The arm was angled according to the cervical pedicle axis as determined by the preoperative CT scans. Drilling was monitored by lateral fluoroscopy. In either technique 3.5 mm screws made of carbon fiber polyetheretherketone (CF-PEEK) were inserted. The use of the CF-PEEK screws allowed for precise postoperative CT-assessment since this material does not cause artifacts. Screw placement was qualified from ideal to unacceptable into four grades: I = screw centered in pedicle; IIa = perforation of pedicle wall less than one-fourth of the screw diameter; IIb = perforation more than one-fourth of the screw diameter without contact to neurovascular structures; III = screw more than one-fourth outside the pedicle with contact to neurovascular structures. Fifty-six pedicle screws could be evaluated according to the same CT protocol that was used preoperatively. Accuracy of pedicle screw placement did not reveal significant differences between techniques 1 and 2. A tendency towards less severe misplacements (grade III) was seen in ST2 (15% in ST2 vs. 23% in ST1) as well as a higher rate of screw positions graded IIa (62% in ST2 vs. 43% in ST1). C4 and C5 were identified to be the most critical vertebral levels with three malpositioned screws each. Because of the variability of cervical pedicles preoperative CT evaluation with multiplanar reconstructions of the pedicle anatomy is essential for transpedicular screw placement in the cervical spine. Cadaver studies remain mandatory to develop safer and technically less demanding procedures. A similar study is projected to further develop the technique of CPS fixation with regard to safety and clinical practicability.

Aged, 80 and over↗
PubMed2006

Successful posterior interlaminar fusion at the thoracic spine by sole use of beta-tricalcium phosphate.

We report on a 43-year-old male who sustained an isolated distraction injury of the thoracic spine Th7/Th8 (AO/ASIF B 2.3) with wedge compression Th8 and sagittal split Th10 without neurological injury. A bisegmental posterior stabilisation and a monosegmental interlaminar fusion was the treatment of choice. A synthetic bone substitute, beta-tricalcium phosphate (beta-TCP, Chronos) without additional autogenous bone was used to achieve the monosegmental posterior fusion. The clinical course was favourable and 10 months postoperatively the implant was removed. On implant removal the CT scan showed a fused segment and intraoperatively it was found that the fusion was solidly healed. A biopsy was taken from the fusion mass and histology showed vital bone that was rich with osteocytes. Noncalcified osteoid surrounding the bone marrow cavity could be identified. Several studies and the reported case might indicate that osteoconductive material alone can be sufficient for achieving a solid fusion.

Adult↗
PubMed2006

Improved anchorage in osteoporotic vertebrae with new implant designs.

The goal of our study was to evaluate two newly developed implant designs and their behavior in terms of subsidence in lumbar vertebral bodies under cyclic loading. The new implants were evaluated in two different configurations (two small prototypes vs. one large prototype with similar load-bearing area) in comparison to a conventional screw-based implant (MACS TL). A pool of 13 spines with a total of 65 vertebrae was used to establish five testing groups of similar bone mineral density (BMD) distribution with eight lumbar vertebrae each. In additional to BMD assessment via dual-energy X-ray absorptiometry, cancellous BMD and structural parameters were determined using a new generation in vivo 3D-pQCT. The specimens were loaded sinusoidally in force control at 1 Hz for 1000 cycles at three load levels (100, 200, and 400 N). A survival analysis using the number of cycles until failure (Cox regression with covariates) was applied to reveal differences between implant groups. All new prototype configurations except the large cylinder survived significantly longer than the control group. The number of cycles until failure was significantly correlated with the structural parameter Tb.Sp. and similarly with the cancellous BMD for three of five implants. In both large prototypes the cycle number until failure significantly correlated with the preoperative distance to the upper endplates. Although the direct relationship between bone structure or density and mechanical breakage behavior cannot be conclusively proven, all the prototypes adapted for poor bone structure performed better than the comparable conventional implant.

Aged↗
PubMed2006

[Lower cervical spine trauma: classification and operative treatment].

Injuries to the subaxial cervical spine (C3-7) occur mostly from traffic accidents and in recreational activities. Such lesions that appear on roentgenological or magnetic resonance images must be classified according to stability. Neurologic deficits, accompanying injuries, and the patient's general condition play major roles in the choice of therapy. Fracture and fracture dislocations should be reduced as soon as possible, as neurologic regeneration and successful reduction are closely time related. The classification developed by Magerl et al. for thoracic and lumbar spine can also be used for the lower cervical spine. Stable injuries without neurologic deficits can generally be treated functionally and, sometimes, with external immobilization. Unstable injuries should be stabilized and treated surgically. Ventral intercorporal spondylodesis is a proven, standard surgical technique for open reduction, decompression, and fusion. Disc and whole or partial vertebral resection along with intercorporal fusion with autologous iliac crest bone grafting and plate osteosynthesis enables successful stabilization of almost all mono- and bisegmental lesions. Dorsal surgery is indicated only in case of a compressed spinal canal and/or neuroforamens due to destroyed posterior elements or remaining instability following ventral plate spondylesis.

Accidents, Traffic↗
PubMed2006

[Reduction of traumatic dislocations and facet fracture-dislocations in the lower cervical spine].

BACKGROUND: Traumatic facet dislocations and facet-fracture dislocations in the lower cervical spine (C2/C3 to C7/T1) are frequently associated with devastating neurological symptoms. A good outcome can only be achieved if the operator has wide and sound knowledge of reduction techniques and the best possible strategy is devised for the subsequent treatment of these severe lesions. PATIENTS AND METHODS: Between 1973 and 1997 a total of 117 of our patients met at least one of the following inclusion criteria: unilateral locked facet dislocation (48%), bilateral locked facet dislocations (23%), unilateral "perched" facet subluxation (14%), bilateral perched facet subluxation (12%), uni- or bilateral dislocation/perched subluxation with facet fractures (3%). RESULTS: Most of the lesions were located at the levels of C5/C6 and C6/7 (n=46 for each). Associated neurological deficits were present initially in 65% of patients: 35% had complete or incomplete spinal cord injuries (tetraplegia), 2% were paraplegic, and 28% had cervical radiculopathies. CONCLUSIONS: Closed reduction (e.g. with the aid of a halo ring) should be carried out as soon as possible after lower cervical spine dislocation or facet-fracture dislocation, as both the success rate of reduction and the potential for recovery from neurological deficits are clearly higher when reduction is achieved within the first 4 h after the initial injury.

Adolescent↗
PubMed2005

Acute traumatic L5-S1 spondylolisthesis: a case report.

STUDY DESIGN: Case report of a patient treated surgically 2 months after sustaining a misdiagnosed acute traumatic lumbosacral dislocation is presented. OBJECTIVES: The aims is to report in full about an uncommon case of anterior traumatic L5-S1 spondylolisthesis treated successfully with combined posterior stabilization and anterior fusion. SUMMARY OF BACKGROUND DATA: Review of literature shows that traumatic lumbosacral dislocations and its treatment by open reduction and internal fixation are rare with only few well-documented case reports. METHODS: We report the case of a 37-year-old man, who sustained a work-related traumatic lumbosacral dislocation. The delayed diagnosis of traumatic L5-S1 spondylolisthesis was initially missed and first treated, when the patient was transferred to the author's institution because of persistent neurological deficits. In the following the patient was successfully reduced and stabilized with posterior internal fixation and anterior interbody fusion. This case is documented in detail with radiographs, CT and MRI scans, as well as clinical pictures. RESULTS: At a 1.5-year follow-up complete fusion was achieved. The patient returned to work on the same job before injury, ambulating pain-free with a good subjective back-function and no limitations carrying out his recreational activities. At follow-up he had persistent sensible S1 nerve root deficits (ASIA grade E). CONCLUSIONS: Traumatic lumbosacral spondylolisthesis is a rare injury pattern. Its diagnosis can be missed initially, therefore computed tomography with biplanar reconstructions is mandatory in addition to good-quality conventional radiographs to plan and carry out such challenging management problems successfully. Surgical treatment for reduction, stabilization and interbody fusion is the method of choice.

Accidents, Occupational↗
PubMed2003

[Non-operative treatment of thoracolumbar spinal fractures. Long-term clinical results over 16 years].

Non-operative treatment of thoracolumbar fractures remains the standard treatment option for stable and slightly unstable spinal injuries at the level of the lower thoracic and lumbar spine. The purpose of the present retrospective study was to determine the outcome and long-term results of patients treated conservatively using either one of the two major non-operative treatment modalities: (1) functional, or (2) closed reduction and immobilisation by cast. The average follow-up time for the 43 patients reviewed was 16.3 years. They showed a radiologic increase in the average kyphosis angle of 5.2 degrees compared to the time of injury. No difference was noted between early functional therapy and treatment with closed reduction and immobilisation by cast. Patients with initial neurologic impairment showed a significant improvement ( P<0.05) in their neurologic status during the follow-up period. Results of validated psychometric questionnaires (SF-36, FSR, VAS-Spinescore) showed the characteristic pattern of a population with chronic back pain. In conclusion, a radiologic increase in the traumatic kyphotic deformity in patients with a non-operative treatment protocol has to be expected. Measurable negative physical and social long-term consequences can be anticipated after sustaining a type-A fracture of thoracolumbar vertebral bodies. Any correlation between radiologic and functional results has not been observed.

Adolescent↗
PubMed2002

Long-term efficacy of preseasonal grass pollen immunotherapy in children.

BACKGROUND: In a previous controlled study we demonstrated that preseasonal grass pollen immunotherapy for three years was effective in children. In the current study we examined the same group of patients to see if there is still a benefit six years after discontinuation of treatment. METHODS: Thirteen of 14 patients with previous specific immunotherapy (SIT) and 10 out of 14 patients of the control group were prospectively followed during the grass pollen season. Outcome measures were seasonal symptom scores for eyes, nose and chest, the use of symptomatic medication and visual analog scale. Objective measures included skin prick test reactivity to seasonal and perennial allergens and conjunctival provocation testing. RESULTS: During the 13 week observation time scores for overall hayfever symptoms (P < 0.004) and individual symptoms for eyes (P < 0.02), nose (P < 0.04) and chest (P < 0.01) as well as combined symptom and medication scores (P < 0.002) remained lower in the group with previous SIT. Only 23% of patients with previous pollen-asthma who had received SIT experienced pollen-associated lower respiratory tract symptoms compared to 70% in the control group (P < 0.05). There was no significant difference in the use of pharmacological treatment during the pollen season except for asthma medication. The average visual analog scale was lower in the post-SIT group (P < 0.05). Six years after cessation of SIT the immediate skin response to grass pollen remained decreased compared to the reaction of the controls (P < 0.01). There was also a tendency for higher allergen concentration to provoke a conjunctival response in the post-SIT group but without reaching statistical significance. Eight years after commencement of SIT, 61% of the initially pollen-monosensitized children had developed new sensitization to perennial allergens compared to 100% in the control group (P < 0.05). CONCLUSIONS: There is still a significant clinical benefit six years after discontinuation of preseasonal grass pollen immunotherapy in childhood. SIT in children with pollen-allergy reduces onset of new sensitization and therefore has the potential to modify the natural course of allergic disease.

Adolescent↗