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Biomedical subjects

U Quint

Publications and source records attributed to U Quint.

18 recordsLinked to original sources
PubMed2007

[Structural femoral head allografts in revision surgery of loosened acetabular cups].

BACKGROUND: Treatment of acetabular bone defects presents a great challenge in revision total hip arthroplasty (THA). Many methods of acetabular reconstruction have been described. The purpose of this study was to evaluate the midterm results of structural femoral head allografts for acetabular reconstruction. METHODS: Thirty-six patients (33 females and 3 males) with acetabular defects ranging from type 2C to type 3B according to Paprosky's classification were included in the study. In all cases acetabular defects were closed using allografts from femoral heads. In 13 cases an uncemented press-fit cup, in 17 cases a cemented polyethylene socket, and in 6 cases a Burch-Schneider antiprotrusion cage was implanted. The mean follow-up period was 84.2 months (range: 5-147). RESULTS: Four acetabular components failed. All 36 grafts were osseointegrated radiographically and formed a mechanically stable construction. The mean Harris Hip Score at the most recent follow-up was 79.8 points. The distance from the obturator line to the prosthesis head center was 3.73 cm (1.17-5.80 cm) preoperatively and 2.79 cm (0.85-4.8 cm) postoperatively (p<0.05). The distance from the teardrop figure to the prosthesis head center was 3.02 cm (1.0-5.8 cm) preoperatively and 3.25 cm (1.6-4.8 cm) postoperatively (p<0.001). CONCLUSIONS: Closure of acetabular defects of types 2C to 3B according to Paprosky's classification can be satisfactorily accomplished using femoral head allografts. These allografts may facilitate future revision surgery. Femoral heads are readily available due to widespread primary total hip replacement surgery. However, the use of structural femoral head allografts for acetabular reconstruction is cost intensive. Individual patient-related aspects, such as the function of revision arthroplasty, have to be considered when planning revision arthroplasty using femoral head allografts.

Acetabulum↗
PubMed2007

[Minimally invasive injection therapy in lumbar syndromes].

Minimally invasive injection therapy is an effective approach for the treatment of sciatica with less complications. This therapy is a sufficient option in cases without absolute indications for operation.The paper describes in detail the different injection techniques like spinal nerve analgesia, epidural dorsal/perineural injections, vertebral joint infiltrations, and radiculographies.

Analgesics↗
PubMed2005

[Spinal manipulative therapy and cervical artery dissections].

Severe complications after cervical spine manipulation are rare. As experts for medical treatment errors, we received between July 2002 and February 2004 cases with serious complications in the central nervous system after manipulation. 5 vertebral artery dissections with subsequent brain infarction were registered. In all cases, the patients showed complete persisting remission of symptoms. In addition, a kinematic estimation model was developed to study the possible causes of vertebral artery damage. We were able to demonstrate that material extension is dependent on cervical rotation and the "free length" of the vertebral artery in the upper cervical spine.

Adult↗
PubMed2004

[Titanium as an implant material for rods of transpedicular instrumentation of the lumbar spine].

BACKGROUND AND AIM: Titanium alloys are increasingly being used as an implant material in orthopaedics and for spinal instrumentation. In this study a metallographic analysis and mechanical testing were performed to evaluate the resistance of rods of Ti-A16-V4 in particular to tensile forces. METHOD: The surface texture of unprepared Ti-A16-V4 and a rod of the same material for spinal instrumentation were evaluated in a metallographic analysis using light microscopy and electron microscopy. Tensile strength measurements were performed on 2 rods, and the strength of the connection between rod and pedicle screws was tested in 9 cases. An electron microscopic analysis of surface changes of the connections between rod and pedicle screws after loading was performed. RESULTS: The titanium alloy Ti-A16-V4 has a mill-annealed appearance, which has a high resistance to tearing under stress. Titanium rods show high tensile strength before failure under loading. The connection between rod and pedicle screws also as high resistance to tensile loads (> 27 kN) with only little deformation of the connecting surface and no tearing. CONCLUSION: The titanium alloy Ti-A16-V4 is an appropriate material for dorsal spinal instrumentation rods because of its low weight, high biocompability and high tensile strength.

Alloys↗
PubMed1998

Importance of the intersegmental trunk muscles for the stability of the lumbar spine. A biomechanical study in vitro.

STUDY DESIGN: A biomechanical study was performed to determine the consequences of a simulation of muscle forces on the loads imposed on the functional spinal units. OBJECTIVES: No biomechanical study has investigated the effect of incorporation of agonist and antagonist muscle forces on the loading of functional spinal units. SUMMARY OF BACKGROUND DATA: Spinal disorders and low back pain are increasingly becoming a worldwide problem. Traditional conservative therapies are intended to strengthen the muscles of the trunk using a judicious regimen of physical exercises. METHODS: Eighteen whole, fresh-frozen human cadaveric lumbar spine specimens (L2-S2; average age, 53.4 years) were tested in a spine tester using pure flexion-extension, lateral bending, and axial moments. The effects of coactivation of psoas and multifidus muscles on L4-L5 mobility were simulated in vitro by applying two pairs of corresponding force vectors to L4. The segmental stability was defined by the correlation of an applied moment to the resultant deformation as shown in load-displacement curves, and the range of motion was defined as the angular deformation at maximum load. RESULTS: The coactivation of muscles was accompanied by a 20% decrease in the range of motion (i.e., a significant increase in stability) during lateral bending and axial moments. Application of flexion-extension moments and muscle coactivation resulted in a 13% increase in the sagittal range of motion. CONCLUSIONS: The action of the intersegmental agonist and antagonist muscles biomechanically increases the overall stiffness (stability) of the intervertebral joints in axial torque and lateral bending, whereas it may destabilize the segment in flexion.

Biomechanical Phenomena↗
PubMed1998

[Possibilities for static and dynamic stabilization of the spine in lesions of the anterior and posterior ligament complex].

Defects of the dorsal and ventral ligament complexes of the lumbar spine results to an instability of the functional spinal unit. For the prognosis of secondary instability due to disko-ligamentous injuries the functional insufficiency of the lasting scars is a larger problem than the primary loss of osseous stability with fast healing tendency. The main goal of the present biomechanical study in vitro was to demonstrate the different grades of instability in the correlation to progressive disko-ligamentous defects as well as stabilisation through dynamic and static procedures. With a transpedicular screw-ringband-system the segmental function was preserved and instability was abolished. After rigid instrumentation with a fixateur intern remained a residual range of motion due to which can result refuse to bending moments without spondylodesis in an implant failure.

Adult↗
PubMed1998

Characteristics of phenol. Instillation in intralesional tumor excision of chondroblastoma, osteoclastoma and enchondroma.

Because of the typical metaphyseal-epiphyseal growth of giant cell tumors and chondroblastomas, the optimal result of an en bloc resection can usually only be achieved by a loss of joint function. For this reason, intralesional excision has prevailed, though it leads to a high rate of relapses. Adjuvant therapy involving irrigation of the remaining bone cavity with phenol can distinctly decrease the rate of relapse. Little is known about the amount of phenol applied that is absorbed. This study investigated the urinary excretion of phenol following the instillation of 102 ml of a 5% phenol solution. The method consisted of urine collection from 11 patients treated by phenol instillation preoperatively, and at 1, 3, 6, 12 and 24 h postoperatively. The urine specimens were analysed for phenol by mass spectrometry. Preoperatively, the value was 5.1 mg/l on average. The maximum concentration of 62 mg/l was found 1 h after instillation, with an average value of 41.5 mg/l, and after 3 h of 18.9 mg/l. A further rapid decrease in the excretion rate was recorded, with normal values being reached after 12 h. This means a maximum of 9% and an average of 2% of the instilled amount of phenol were excreted in the urine within 24 h postoperatively. By comparing these urinary concentrations to published standards, we conclude that the instillation of a 5% phenol solution into bony lesions is associated with a relatively low risk of systemic toxicity.

Adult↗
PubMed1998

Laminectomy and functional impairment of the lumbar spine: the importance of muscle forces in flexible and rigid instrumented stabilization--a biomechanical study in vitro.

Laminectomy is the accepted treatment for spinal canal stenosis in cases where conservative treatment has failed. Opinions diverge on the resulting clinical instability and the necessity of instrumented stabilization. The present biomechanical study was performed to determine the functional impairment following laminectomy and the stabilizing effect of flexible and rigid devices. This was the first time that the effects of agonist and antagonist intersegmental lumbar muscle forces acting on intact, unstable and instrumentally stabilized functional spinal units have been investigated. Six human cadaveric lumbar spines were tested in a spine tester. The coactivation of agonist and antagonist muscle forces resulted in increased stability under the load conditions of bending and rotation; a slight increase in the range of motion was noted during flexion. The functional impairment following laminectomy was corrected by ligamentoplasty and by means of muscle forces. Ligamentoplasty appears to be an alternative to decompression with spondylodesis, especially in patients with well-developed muscles.

Biomechanical Phenomena↗
PubMed1996

Cytotoxicity of phenol to musculoskeletal tumours.

Local treatment with phenol is often used after intralesional excision of chondroblastomas and giant-cell tumours which involve bone near joints, and has been shown to reduce the rate of recurrence. The ideal concentration of phenol is uncertain, but may be important because of the high rate of absorption and toxicity. We have studied the effectiveness of different concentrations on standard sarcoma cell lines. Our results suggest that a 5% solution of phenol is effective against dispersed single cells, and that higher concentrations give no significant advantage, but create problems due to lack of homogeneous mixing, temperature and safety.

Bone Neoplasms↗
PubMed1995

Surgical treatment of enchondroma in long tubular bones. Preservation of function versus extensive excision in the humerus.

Insufficient criteria to distinguish enchondroma from low-grade chondrosarcoma occasionally lead to uncertainty concerning the optimal extent of surgery. For either tumor the clinical outcome is mainly compromised by local recurrence. Reviewing our medical records, we retrospectively identified a female patient who was diagnosed as suffering from a large enchondroma of the left humerus in childhood and could be followed up for almost two decades. Following local excision of the tumor at the age of 14 years, clinical follow-up was uneventful for 20 years. A potential primary extensive excision or amputation would have substantially compromised this young woman's quality of life. The complete preservation of function here following a local excision has stimulated a critical discussion of radical surgical treatment.

Biopsy↗
PubMed1995

[Experiences with combined interventions on the lumbar spine].

Lumbar fusion is practicable by combined operations with dorso-ventral combined procedures. The indication is advisable following degenerative, inflammative, neoplastic processes and fractures of the spine. We operated 125 patients with combined procedures in 10 years. Beside dorsal instrumentation an intervention at the spinal canal is mostly necessary, only in 9 patients we preferred first the ventral part for the correction of a deformity. According to our experience the advantage for delayed dorso-ventral procedure is the preoperative blood donation, perioperative ferrum substitution and intraoperative cell saver system. In contrast to 1 combined procedure, most patients with 2 operations during the same hospital stay do not need homologous blood, the addition of time for 2 delayed procedures is shorter than for a single operation with intraoperative patient turn round in anesthesia, the convalescence was better, complications were seldom and hospital stay shorter. This comes out very clear in the group of lumbar degeneration in high age, who otherwise were bedridden for a long time following frequent complications.

Adult↗
PubMed1991

[Stabilization of hip para-articular femoral fractures. A report of experiences with 1,698 patients].

Between 1973 and 1987 a total of 1698 patients with fractures of the proximal femur were operatively treated at the surgical accident and emergency department of the Städtische Krankenanstalten Krefeld. The most commonly observed fracture in the high age group (mean: 81.4 years) was that of the subcapital femoral neck (n = 901). A total hip replacement (n = 648) was commonly indicated - followed by a hemiarthroplasty (n = 114) and 130 AO plate (n = 70). Fractures of the femoral neck in young patients were treated with a cancellous screw in order to preserve the femoral head (n = 69). The majority of pertrochanteric fractures (n = 603) were stabilized with 130 degrees AO plates (n = 520) and most of the subtrochanteric fractures (n = 194) were treated either with an angle plate (n = 130) or with a 95 degrees AO plate (n = 64). In principle early internal fixation followed by immediate mobilization was the aim in all patients (68% of patients were operated on within three days of admission). Sufficient stability was achieved using internal fixation to allow full weight bearing in 76% of the injuries, or partial weight bearing in 21% postoperatively. The paper shows that the patients need spend less time in the hospital (60% stayed less than three weeks on the ward, 80% were discharged within four weeks) and that the mortality in this study was reduced to 10.1%. Complications such as fracture of the implant (0.5%) and dislocation (0.9%) were described. The rate of bone infection amounted to 0.9% of all operations.

Adolescent↗
PubMed1991

[Osteosynthesis of proximal femoral fractures. Experience in the treatment of 2012 patients].

Between 1973 and 1990 a total of 2012 patients with fractures of the proximal femur were operatively treated at the surgical accident and emergency department of the Städtische Krankenanstalten Krefeld. The most commonly observed fracture in the high age group (mean: 81.2 years) was that of subcapital femoral neck (n = 1067). A total hip replacement (TEP n = 768) or a hemiarthroplasty (n = 135) was indicated in 85% of the cases. All patients in which a head preserving internal fixation was possible, were normally treated as an emergency with a cancellous screw (n = 81) or stabilized with 130 grade angled plate (n = 83). Pertrochanteric femur fractures (n = 715) were mainly stabilized with 130 grade angled plates (n = 605). In subtrochanteric femur fractures (n = 230) a 130 grade angled plate (n = 155) or a 95 grade condylar plate (n = 75) was used. In principle early internal fixation followed by immediate mobilization was the aim in all patients (68% of patients were operated on within three days of admission). Sufficient stability was achieved using internal fixation to allow full weight bearing in 76% of the injures, or partial weight bearing in 21% postoperatively. The paper shows that the patients need spend less time in the hospital (60% stayed less than three weeks on the ward, 80% were discharged within four weeks) and that the mortality in this study was reduced to 10.1% in comparison with formerly studies. Complications such as fracture of the implant (0.5%) and dislocation (0.9%) were described. The rate of bone infection amounted to 0.9% of all operations.

Adult↗
PubMedDate not supplied

[Follow-up study after dynamic and static stabilisation of the lumbar spine].

INTRODUCTION: The clinical indication for graf's ligamentoplasty and dorsoventral fusion may be described as the "lumbar instability syndrome". A follow-up comparison between Graf's ligamentoplasty and instrumental dorsoventral fusion in a consecutive series of 52 patients was performed. METHODS: 52 patients operated on for low back pain were recalled for a clinical and radiological review (at mean 79 months postoperatively). 26 patients underwent Graf' ligamentoplasty and 26 patients underwent dorsoventral fusion. We evaluated the surgical results and measured an objective outcome using the Oswestry Score, Low Back Outcome Score (LBOS) and Visual Analogue Scale (VAS). For radiological evaluation the Mimura and the Pathria Scores were used. RESULTS: There was no statistically significant difference between the two groups, when measured by the Oswestry Score, LBOS and VAS at the latest follow-up. The difference between the preoperative and actual VAS in each group was statistically significant (p < 0.001). Furthermore, there was no provable preoperative parameter in favour of either one of these therapies. CONCLUSION: Both methods for stabilisation methods of the lumbar spine had a comparable clinical outcome.

Adult↗
PubMedDate not supplied

[Psychological stress of inpatients with acute and chronic lumbar syndrome].

PURPOSE: As a result of its increasing incidence and social medical implications, low back pain with either chronic or acute symptoms presents a major challenge for our society. The psychological background of pain perception and valuation has been explored in various studies; frequently, no positive correlation was found between subjective pain perception and structural orthopedic findings. METHOD: A symptoms checklist (SCL-90-R) was used to compare a group of patients hospitalized because of low back pain with a group of asymptomatic controls. Additionally, the pain-specific questionnaire (ERSS) was employed to verify the validity of the depressive mood scale by means of the corresponding scale in the SCL-90-R. RESULTS: When the SCL-90-R was given to both groups, significant differences could be observed between the patients and the controls on the scales for somatisation, depressive mood, anxiety, phobias and psychoticism. Moreover, patients with chronic pain had higher scores on the scales for phobias and the global marker of "positive symptom total" (PST) than patients with acute back pain. On the scales for somatisation and insecurity during social contacts, women reported higher levels of psychological distress than men. Age-related differences were not observed. The depressive mood scale of the ERSS appears to be valid. With the SCL-90-R we could demonstrate significant differences between patients with acute and chronic pain, and between the sexes. No differences were found in the age-group comparison. CONCLUSION: In patients with low back pain, psychological parameters have to be taken into account in any comprehensive concept of conservative treatment.

Acute Disease↗
PubMedDate not supplied

[Functional sequelae of surgical decompression of the lumbar spine--a biomechanical study in vitro].

PURPOSE: Dorsal decompression has become accepted as the standard surgical treatment for spinal stenosis. However, no consensus has been reached to date concerning the extent of resectioning required or the ensuing functional impairment of the segment. As a result, a discussion is now underway on the necessity of employing various additional methods for instrumented stabilisation. The aim of this biomechanical in vitro study is to objectify the functional impact of various defined decompression techniques. METHODS: With the aid of a universal spine tester, the increasing defect situations following left hemifacetectomy, bilateral hemifacetectomy, left hemilaminotomy and laminectomy of the functional spinal unit L4/5 were assessed. A three-dimensional motion analysis was performed on six human lumbar spine specimens under the loading conditions flexion/extension, left/right bending and right/left rotation. RESULTS: The results showed an increase in both the neutral zone and the range of motion under all the loading components. No significant differences were observed in coupled motions following decompression. CONCLUSIONS: Laminectomy leads to a distinct instability and the question arises of how much additive stability achieved by instrumented stabilization will be adequate.

Adult↗