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H M Mayer

Publications and source records attributed to H M Mayer.

At least 19 recordsLinked to original sources
PubMed2005

[Degenerative disorders of the lumbar spine Total disc replacement as an alternative to lumbar fusion?].

Spinal fusion is accepted worldwide as a therapeutic option for the treatment of degenerative disorders of the lumbar spine. Because there are only few evidence-based data available supporting the usefulness of lumbar spinal fusion, its questionable benefit as well as the potential for complications are the reasons for an ongoing discussion. In recent years, total disc replacement with implants has emerged as an alternative treatment. Although early results are promising, there is still a lack of evidence-based data as well as of long-term results for this technology. This article gives a critical update on the implant systems currently in use (SB Charité, Prodisc II L, Maverick, Flexicore, Mobidisc), which all have to be considered as "first-generation" implants. Morphological and clinical sequelae of the different biomechanical properties, designs, and materials have not yet been sufficiently investigated. There is no international consensus on the indication spectrum and on the preoperative diagnosis of discogenic low back pain. The same is true for the (minimally invasive) surgical access strategies. Complication rates seem to be somewhat lower compared to spinal fusion techniques. There are no standardized revision concepts in cases of implant failure. Lumbar disc replacement has opened a new era in spinal surgery with a still unproven benefit for the patient. It is strongly recommended that these techniques should only be applied by experienced and well-trained spine surgeons. Until evidence-based data are available, all patients should be treated under scientific study conditions with close postoperative follow-up.

Adolescent↗
PubMed2003

[Microsurgery of acquired degenerative lumbar spinal stenosis. Bilateral over-the-top decompression through unilateral approach].

Degenerative lumbar spinal stenosis is diagnosed with an increasing incidence. Clinical and radiological signs of progression often result in a significant decrease in the patient's quality of life. The indication for surgical treatment follows the spectrum of clinical symptoms. In cases with "structural" spinal stenosis and predominant "leg symptoms" such as neurogenic claudication and/or radicular symptoms, decompressive types of surgery are indicated. However, due to the multimorbidity of the mostly elderly patients, the surgical risk should be as low as possible whereas the surgical efficacy should be as high as possible. We describe a microsurgical technique, which can achieve a bilateral decompression of the central and lateral lumbar spinal canal through a unilateral surgical approach. In a consecutive series of 275 patients, a significant increase in standing time and walking distance could be attained. The surgical complication rate was low. A complete decompression of the spinal canal with preservation of the "tension band" of the posterior spinal column could be achieved. Although this type of surgery is adequate for patients with "predominantly leg symptoms" only, low back pain improved as well in nearly 50% of the patients. However, in cases with dynamic spinal stenosis and/or disturbed curvature with predominant low back pain, a combination of the described procedure with stabilizing surgery (spinal fusion, dynamic fixation etc.) is recommended.

Adult↗
PubMed2003

A memory coiling spiral as nucleus pulposus prosthesis: concept, specifications, bench testing, and first clinical results.

The intradiscal cavity left after a discectomy can be filled by a new nucleus prosthesis made of polycarbonate urethane in the form of a "memory coiling spiral." Biomechanical tests have demonstrated that this device compensates for the loss of disc height, decreases the compression of the facet joints, and restores the kinematics of the spinal segment, without deformation of the vertebral endplates or migration. The device is currently under clinical investigation. Inclusion and exclusion criteria of the pilot study are presented, and preliminary results of the first five patients supplied with the spiral are reported after an average follow-up time of 24 months. No migration of the device has been observed so far. With its easy application due to the standardized approach and the memory coiling mechanism, this device represents an advance within the nonfusion techniques.

Adolescent↗
PubMed2002

Minimally invasive total disc replacement: surgical technique and preliminary clinical results.

Total disc replacement has become an option for the treatment of degenerative disc disease of the lumbar spine. A new generation of implants has been developed that can be implanted through minimally invasive anterior approaches to the lumbar levels L2/3, L3/4, L4/5 and L5/S1. However mid- and long-term data are still lacking. This paper describes the minimally invasive surgical approach - techniques as well as the preliminary results of our first 34 consecutive patients. The intervertebral spaces L5/S1, L4/5, L3/4 and L2/3 were each approached through slightly different, but standardized, mini-laparotomies either through a retroperitoneal or a transperitoneal route. The clinical results with a follow-up of up to 1 year show satisfactory outcomes in about 80% of the patients. Oswestry score as well as VAS values show significant changes during the postoperative course. There have been three complications (8.8%), two of which were specific to the implantation process, but were resolved with a good clinical outcome in both patients. The preliminary results suggest that total disc replacement may become a reasonable alternative to spinal fusion under the selection criteria used in this study.

Adult↗
PubMed2002

A spiral implant as nucleus prosthesis in the lumbar spine.

Microdiscectomy represents the gold standard in disc surgery on the lumbar spine. The remaining defect in the intervertebral disc space can be filled with a newly developed nucleus prosthesis presented in this paper. This prosthesis consists of polycarbonate urethane (Sulene PCU), and takes the form of a memory coiling spiral. It can be easily implanted using the standard microdiscectomy approach with no further tissue damage. Biomechanical tests have shown that anatomical distances can be restored by the spiral for both the facet joints and the endplates. Endplate deformations are not statistically different when compared to intact conditions. Inclusion and exclusion criteria of an in vivo pilot study are presented. The paper describes the insertion setup for the spiral and the technique of implantation. Five patients have been supplied with the implant to date. The first results on postoperative magnetic resonance images are presented.

Adult↗
PubMed2001

[Discogenic low back pain and degenerative lumbar spinal stenosis - how appropriate is surgical treatment?].

Surgery in acute and/or chronic low back pain is still a matter of intensive and controversial discussions. A vast number of minimally invasive or so called semi-invasive procedures have been published in the last 3 decades, but evidence-based data on efficacy and benefit of most of these techniques are still lacking. However, empirical data suggest good or at least satisfactory clinical results for a limited number of procedures if they are applied under restrictive indication criteria. Discogenic low back pain and lumbar spinal stenosis belong to the most frequent diagnoses associated with low back pain. This article gives a survey on definitions, indication criteria and modern surgical or semi- invasive techniques used for the treatment of these two pathologic entities. Discogenic low back pain: This clinical and morphological entity is defined as low back pain arising mainly from disc degeneration. Pain generators are usually nociceptors in the cartilaginous endplates, in the outer anulus fibrosus as well as in the periosteum of the vertebral bodies. Clinical symptoms correlate with morphologic changes detected with MR-imaging (modic type I) or with contained disc protrusions mainly without neurological symptoms. Surgery is rarely indicated, spontaneous remissions occur in more than 60% of all cases. Spinal fusion has been the only surgical option in cases which did not respond to conservative therapy. Recently, electro-thermal modulation of the posterior anulus fibrosus has been published as a semi- invasive technique to relieve low back pain generated by fissures in the outer anulus and ingrowing nociceptors (intradiscal electro-thermal therapy, IDET(TM)). First results are promising, however, prospective randomised studies comparing this technique with conservative therapy are still lacking. The same is true for artificial nucleus pulposus replacement using hydrogel cushions implanted in the intervertebral space after removal of the nucleus pulposus from posterior or through an anterior approach (PDN, prosthetic disc nucleus(TM)). In cases with severe disc degeneration total disc replacement is another innovative option (ProDisc(TM)). Two metal endplates with titanium surface coating are implanted through a minimal invasive anterior approach (mini-laparotomy). A polyethylene inlay anchored in the caudal endplate holds the distance between the endplates and preserves the physiological range of motion between the two vertebral bodies. Degenerative lumbar spinal stenosis: Narrowing of the spinal canal due to degenerative changes of the disc, the facet joints and thickening of the yellow ligament is a geriatric disease which is diagnosed in increasing numbers within the last 10 years. More than 80% of the patients present with low back pain in association with neurogenic claudication. Neurological symptoms at rest are less frequently found. The spontaneous course shows progressive symptoms in more than 50% of all patients. More than 35% of the patients have associated diseases which might influence the perioperative course, complication rates and outcomes of surgery. Surgery is indicated in patients with progressive neurological symptoms, unacceptable decrease of quality of life or progressive intractable pain. In patients with mainly "leg symptoms" microsurgical mono- or multisegmental decompression is the procedure of choice. If low back pain is predominant and associated with degenerative instability such as degenerative spondylolisthesis or lumbar scoliosis, decompression must be combined with instrumented spinal fusion. In general a restrictive indication for surgery must be recommended especially for spinal fusion procedures. Non-fusion techniques such as intradiscal electro thermal therapy or spine arthroplasty with replacement of nucleus pulposus or total disc show promising early results; however, little is known about the long-term effect. It should be a principle to apply surgery in the least invasive way.

Diagnosis, Differential↗
PubMed2000

The ALIF concept.

The terms 'minimally invasive' or 'less invasive surgery' have been used recently to describe surgical approaches or operations that are performed with less trauma to anatomical structures on the way to or surrounding the surgical 'target area'. These types of surgical procedures are usually performed with the help of 'high-tech' instruments such as surgical endoscopes or surgical microscopes, modern video techniques and automated instruments. Within the last 10 years, such techniques have been developed in the field of spinal surgery. The application of minimally or less invasive procedures has concentrated predominantly on anterior approaches to the thoracic and lumbar spine. This article describes two anterior approach techniques for performing anterior lumbar interbody fusion (ALIF) through a minimally invasive retroperitoneal or transperitoneal approach. The technical principles are microsurgical modifications of traditional anterior approaches to the lumbar spine. Through small (4-cm) skin incisions, the target area can be exposed. Preliminary results suggest decreased peri - and postoperative morbidity, less blood loss, earlier rehabilitation and acceptable complication rates. The technique is currently used by the author for all patients requiring anterior lumbar interbody fusion.

Adolescent↗
PubMed2000

Spinal epidural abscess following blunt pelvic trauma.

A 17-year-old patient with pre-existing grade II spondylolisthesis of L5/S1 sustained a partial disruption of the left sacroiliac joint with haematoma of the iliac muscle after a fall. The haematoma probably led to occlusion of the left ureter, resulting in a urinary tract infection. After initial conservative treatment the patient developed fever and radicular pain of the left leg. Magnetic resonance imaging (MRI) revealed a left-sided epidural abscess at L5/S1, which had probably spread from the infected iliac haematoma along the injured sacroiliac joint. Prompt surgical drainage and antibiotic coverage with cefuroxime and flucloxacillin led to rapid clinical improvement. Staphylococcus aureus was identified as the pathogen. At follow-up 6 months postoperatively all symptoms had resolved, while MRI still revealed residual osseous oedema of the sacroiliac joint. The haematoma of the iliac muscle resolved without surgical intervention.

Accidental Falls↗
PubMed1998

Influence of muscle forces on loads in internal spinal fixation devices.

STUDY DESIGN: The loads acting on an internal spinal fixation device were measured in vivo. OBJECTIVES: To determine the influence of muscle forces on implant loads. SUMMARY OF BACKGROUND DATA: Only limited information exists regarding the loads acting on spinal implants in vivo. Though the muscles greatly influence spinal load, they have been neglected in most studies. METHODS: Telemeterized internal spinal fixation devices were used to study the influence of muscle forces on the implant loads in three patients before and after anterior interbody fusion. RESULTS: Contracting abdominal or back muscles in a lying position was found to significantly increase implant loads. Hanging by the hands from wall bars as well as balancing with the hands on parallel bars reduced the implant loads compared with standing; however, hanging by the feet with the head upside down did not reduce implant loads compared with lying in a supine position. When lying on an operating table with only the foot end lowered so that the hips were bent, the patient had different load measurements in the conscious and anesthetized state before anterior interbody fusion. The anesthetized patient evidenced predominately extension moments in both fixators, whereas flexion moments were observed in the right fixator of the conscious patient. After anterior interbody fusion had occurred, the differences in implant loads resulting from anesthesia were small. CONCLUSIONS: The muscles greatly influence implant loads. They prevent an axial tensile load on the spine when part of the body weight is pulling, e.g., when the patient is hanging by his hands or feet. The implant loads may be strongly altered when the patient is under anesthesia.

Abdominal Muscles↗
PubMed1998

Placing a bone graft more posteriorly may reduce the risk of pedicle screw breakage: analysis of an unexpected case of pedicle screw breakage.

Telemeterized internal spinal fixation devices were implanted in a patient with degenerative instability and a narrow spinal canal in order to measure the fixator loads during daily activities. Anterior interbody fusion was performed three weeks later. During walking, the typical maximum flexion bending moments were 10 N m in the left and 5 N m in the right fixator. On removal of the implants three months later, a fatigue fracture was found not on the high loaded left side but in the upper right pedicle screw. The crack started on the caudal side of the cross-sectional area and progressed cranially. Upper vertebral tilting in the sagittal plane must have caused the screw breakage. This would probably have been prevented by a more posteriorly placed bone graft.

Activities of Daily Living↗
PubMed1997

A new microsurgical technique for minimally invasive anterior lumbar interbody fusion.

STUDY DESIGN: A series of patients were prospectively studied to determine the morbidity and possible complications of minimally invasive anterior lumbar interbody fusion by two new microsurgical approaches (retroperitoneal for segments L2-L3, L3-L4, and L4-L5, and transperitoneal for L5-S1). OBJECTIVES: To investigate the feasibility of performing an anterior lumbar interbody fusion through a 4-cm skin incision and a standardized muscle-splitting approach. SUMMARY OF BACKGROUND DATA: The utility of anterior lumbar interbody fusion with or without posterior instrumentation for the treatment of various degenerative or postoperative lesions associated with low back pain is still a matter of debate. Regardless of the indications for surgery, use of the anterior approach in the lumbar spine is known to be associated with considerable surgical trauma, a high postoperative morbidity, and, occasionally, unacceptably high complication rates. Laparoscopic anterior interbody fusion of L5-S1 to eliminate some of these problems has been recently described. However, a minimally invasive surgical concept that covers all lumbar segments from L2 to S1 has not been described before now. METHODS: A standardized, microsurgical retroperitoneal approach to levels L2-L3, L3-L4, and L4-L5 and a microsurgical transperitoneal approach through a "minilaparotomy" to L5-S1 are described. The first 25 patients (retroperitoneal, n = 20; transperitoneal, n = 5) treated with these methods are evaluated with respect to intraoperative data such as blood loss, operating time, intraoperative and postoperative complications, as well as preliminary fusion results. RESULTS: There were no general or technique-related complications in the first series of 25 patients. Postoperative morbidity was low in all patients, with negligible wound pain. Average blood loss was 67.8 ml for the retroperitoneal technique and 168 ml for the transperitoneal approach. No blood transfusion was necessary. All patients showed solid bony fusion. CONCLUSIONS: The microsurgical approaches described in this article are atraumatic techniques to reach the lumbar spinal levels L2-L3, L3-L4, L4-L5, and L5-S1. They represent microsurgical modifications of the surgical approaches well known to the spine surgeon. They can be learned in a step-by-step fashion, starting with a conventional skin incision and, once the surgeon is familiar with the instruments, moving on to the microsurgical technique. The approaches are not restricted to the type of fusion (iliac crest autograft) presented in this series.

Adult↗
PubMed1997

[Not Available].

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Journal Article↗
PubMed1996

Endoscopic discectomy in pediatric and juvenile lumbar disc herniations.

Most herniated lumbar discs in children and adolescents respond to conservative treatment, but some young patients with persistent low back and neurological symptoms do not respond to noninvasive treatment and require operative treatment. Because the long-term results of disc surgery depend not only on the disc disease itself but also on the degree of surgical trauma, disc herniations in children and adolescents should be treated with minimally invasive procedures. We report our experience with four young patients aged 8-17 years with contained or small noncontained lumbar disc herniations who were treated by percutaneous endoscopic discectomy (PED). The clinical results were good to excellent in all four cases, with follow-up of 1 to 5 years. There were no complications, and the operation was tolerated well by the young patients. We recommend percutaneous endoscopic lumbar discectomy in patients with contained or small uncontained disc herniations who do not respond to conservative treatment.

Adolescent↗
PubMed1996

Clamping stiffness and its influence on load distribution between paired internal spinal fixation devices.

The load distribution between two internal spinal fixation devices depends, besides other factors, on their stiffness. The stiffness ranges were determined experimentally for the clamps of the AO internal fixator with lateral nut and with posterior nut as well as for the clamps of the SOCON fixator. The stiffness of eight devices each differed by a factor of 3.1 for the clamp with lateral nut, by a factor of 1.5 for the clamp with posterior nut, and by a factor of 1.4 for the clamp of the SOCON fixator. For the AO clamp with lateral nut, the influence of the nut-tightening torque on the stiffness was determined. Using instrumented internal spinal fixation devices mounted to plastic vertebrae and simulating a corpectomy, the load distribution between the implants was measured for different tightening torques. It could be shown that, for the AO internal fixator whose clamps have a lateral nut, a nut-tightening torque > 5 Nm has only a negligible influence on load-sharing between the implants. Tooth damage occurs when the teeth of the clamp body and clamping jaw of the clamp with lateral nut do not gear together exactly, which leads to changes in the clamping stiffness and load-sharing between the two implants.

Humans↗