Biomedical subjects

J Zeichen

Publications and source records attributed to J Zeichen.

At least 19 recordsLinked to original sources

PubMed2006

Tibial press-fit fixation of the hamstring tendons for ACL-reconstruction.

Press-fit fixation of patellar tendon bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary to achieve fixation. Up till the present point, there is no biomechanical data available for the tibial press-fit fixation of the hamstring tendons. Hamstring tendons of 21 human cadavers (age: 41.9 +/- 13.1 years) were used. A press-fit fixation with looped semitendinosus and gracilis tendons secured by a tape (T) over a bone bridge, or by a baseball-stitched suture (S), was compared with degradable interference screw fixation (I) in 21 porcine tibiae. The constructs were cyclically strained and subsequently loaded to failure. The maximum load to failure, stiffness, and elongation during cyclical loading were measured. The maximum load to failure was highest for the T-fixation at 970 +/- 83 N, followed by the I-fixation with 544 +/- 109 N, and the S-fixation with 402 +/- 78 N (P < 0.03). Stiffness of the constructs averaged 78 +/- 13 N/mm for T, 108 +/- 18 N/mm for S, and 162 +/- 27 N/mm for I (P < 0.03). Elongation during initial cyclical loading was 2.0 +/- 0.6 mm for T, 3.3 +/- 1.1 mm for S, and 1.4 +/- 0.5 mm for I (S inferior to I and T, P<0.05). Elongation between the 20th and 1,500th loading cycle was lower for T (2.2 +/- 0.7 mm) compared with I (4.1 +/- 2.7 mm) and S (4.8 +/- 0.7 mm; P < 0.001). The T-fixation technique exhibited a significantly higher failure load than the S-, and I- techniques. All techniques exhibited larger elongation during initial cyclical loading than is reported in the literature for grafts with bone blocks. Only one technique (T) showed satisfactory elongation behavior during long-term cyclic loading. Interference screw fixation demonstrated significantly higher stiffness. Only one of the investigated techniques (T) seemed to exhibit adequate mechanical properties necessary for early aggressive rehabilitation programs.

Adolescent↗

PubMed2006

Navigated open-wedge high tibial osteotomy: advantages and disadvantages compared to the conventional technique in a cadaver study.

High tibial osteotomy (HTO) is an established therapy for the treatment of symptomatic varus malaligned knees. A main reason for disappointing clinical results after HTO is the under- and overcorrection of the mechanical axis due to insufficient intraoperative visualisation. Twenty legs of fresh human cadaver were randomly assigned to navigated open-wedge HTO (n=10) or conventional HTO using the cable method (n=10). Regardless of the pre-existing alignment, the aim of all operations was to align the mechanical axis to pass through 80% of the tibial plateau (beginning with 0% at the medial edge of the tibial plateau and ending with 100% at the lateral edge). This overcorrection was chosen to ensure a sufficient amount of correction. Thus, the medial proximal tibia angle (MPTA) increased by 9.1+/-2.9 degrees (range 5.2 degrees -12.3 degrees ) on the average after navigated HTO and by 8.9+/-2.9 degrees (range 4.7 degrees -12.6 degrees ) after conventional HTO. After stabilization with a fixed angle implant, the alignment was measured by CT. After navigated HTO, the mechanical axis passed the tibial plateau through 79.7% (range 75.5-85.8%). In contrast, after conventional HTO, the average intersection of the mechanical axis was at 72.1% (range 60.4-82.4%) (P=0.020). Additionally, the variability of the mean corrections was significantly lower in the navigated group (3.3% vs. 7.2%, P=0.012). Total fluoroscopic radiation time was significantly lower in the navigated group (P=0.038) whereas the mean dose area product was not significantly different (P=0.231). The time of the operative procedure was 23 min shorter after conventional HTO (P<0.001). Navigation systems provide intraoperative 3-dimensional real time control of the frontal, sagittal, and transverse axis and may increase the accuracy of open-wedge HTO. Future studies have to analyse the clinical effects of navigation on corrective osteotomies.

Adult↗

PubMed2006

[Knee injuries of vulnerable road users in road traffic].

BACKGROUND: The purpose of this study was to assess the risk of knee injuries among vulnerable road users, such as pedestrians, bicyclists and motorcyclists. METHODS: Two different periods (years 1985-1993 and 1995-2003) were compared. Inclusion criteria were furthermore Abbreviated Injury Scale knee 2-3 (AIS(knee)). Technical analysis assessed the type of collision, direction and speed as well as the injury pattern, and different injury scores (AIS, ISS) were examined documented by the accident research unit, which analyses technical and medical data collected shortly after the accident at the scene. This study included 2,580 pedestrians, 2,279 motorcyclists and 4,322 bicyclists from a total number of 22,794 victims in 17,382 accidents. RESULTS: Among vulnerable road users, 2% (196/9181 patients) had serious ligamentous or bony injuries of the knee. The risk of injury was higher for motorcyclists and bicyclists than for pedestrians. Knee injury severity was higher for pedestrians. Over the course of 18 years, the knee injury risk was significantly reduced in more recent times (35%>28%, p<0.0001). Improved aerodynamic design of car fronts reduced the risk for severe knee injuries significantly (p=0.0015). CONCLUSIONS: The highest risk for knee injuries among vulnerable road users is encountered by motorcyclists followed by bicyclists and pedestrians. Over time, the knee injury risk for pedestrians could be significantly reduced due to aerodynamic changes of current car fronts. Further modification of the exterior car design might decrease the risk for knee injuries among vulnerable road users.

Accidents, Traffic↗

PubMed2006

[Gymnastic school sport injuries--aspects of preventive measures].

INTRODUCTION: Gymnastic school sport injuries account for a significant morbidity and mortality among children and adolescents. Preventive issues may be derived from a thorough in-depth analysis of the pattern and circumstances of gymnastic injuries. METHODS: During a school year among 3993 schools in 43 889 classes with 993 056 pupils 2234 school sport injuries have been reported to the Gemeinde Unfall Versicherung (GUV) Niedersachsen, Germany. RESULTS: Gymnastic sport injuries account for 18 % (403 accidents), which is second after ball sports injuries. Regarding the distribution of the gymnastic disciplines, vault was the major discipline with 34 %, followed by floor exercise (21.3 %), mini- and competition trampoline (16.8 %), and parallel bars (8.2 %). The analysis of the type of injury during vault accidents revealed contusion (31 %) as the predominant injury, followed by sprains (15.4 %), and fractures (15.4 %). Floor exercise injuries distributed among distorsions (26.7 %), contusions (18.6 %), muscle tears (14 %). Back injuries especially of the cervical and thoracic spine, accounted for 40 % of all their injuries. Minor head injuries account for 4.7 % of all floor exercise injuries. Mini-trampoline injuries distribute among contusions (30 %), fractures (22.5 %), distorsions (7.5 %). 21.8 % collisions were noted against a box in comparison to 6.8 % in case of the horse. CONCLUSION: Gymnast injuries account for a significant number of all school sport related injuries. Vault and floor exercise account for the vast majority of all injuries, with alarming high numbers of spine injuries during floor exercise and mini-trampoline. A preservation of a high level of attention during a sport lesson, safety measures including appropriate mats and landing zones are mandatory to reduce injuries. Muscle injuries and ankle sprains can be prevented by a prospective proprioceptive training intervention to be implemented in school sports.

Adolescent↗

PubMed2005

Influence of cyclic mechanical strain and heat of human tendon fibroblasts on HSP-72.

Heat shock protein 72 (HSP-72) is a member of a superfamily of different proteins that are synthesized as a cytoprotective response following cellular stress. Mechanical strain is an important component in ligament and tendon healing. Up to the present point of time, the influence of mechanical strain on the expression of HSP-72 is unknown. Tendon fibroblasts from the patellar tendons of nine individuals were isolated and amplified in vitro. First, the effect of 15 or 60 min of heat exposition was studied immunohistochemically and by Western blotting. In a second experiment, the effects of 15 and 60 min of cyclic longitudinal stretching were investigated. Samples were taken after 2, 4 and 8 h. The heat exposition experiments indicate that HSP-72 accumulates in the nucleus and that there is a transient upregulation. This effect is more prominent after 60 min of heat exposure. The same reaction was found after stretching stimulation, however, to a lesser extent. There was a transient up regulation of HSP-72 after short-term stretching and a biphasic increase after 60 min of stretching. Upregulation of HSP-72 by heat and mechanical stress is a response in human fibroblasts which involves a nuclear translocation. The response differs with regard to the time points beyond 2 h after the application of either stress.

Adolescent↗

PubMed2005

Femoral avulsion fracture of the posterior cruciate ligament in association with a rupture of the popliteal artery in a 9-year-old boy: a case report.

Ruptures of the posterior cruciate ligament (PCL) and especially proximal bony avulsion fractures in children are very rare. This in combination with a rupture of the popliteal artery is extremely rare. Thus, an exact incidence is not available from the literature. Overall, these injuries are severe and often lead to chronic knee instability. We report a case of a 9-year-old boy who suffered a traumatic displacement of the left knee with a rupture of the popliteal artery. Prior to transfer to our department, he was treated by a saphenous vein bypass graft and by a transfixation of the knee using two oblique percutaneous pins. We performed magnetic resonance imaging (MRI) scan of the knee which revealed a femoral avulsion fracture of the PCL. Other ligaments and menisci were intact. A transosseous femoral fixation using non-absorbable stitches was carried out. A 1-year follow-up after surgery demonstrates intact peripheral perfusion and sensation, straight axes of both legs and a physiological gait. Minimal differences of the length and circumference of both legs could be measured. The posterior laxity (Lachman-test) was about 5/8 mm (right/left knee) and 2/5 mm (right/left knee) in 90 degrees flexion. The range of motion (extension/flexion) was 5/0/140 degrees -/5/100 degrees (right-left knee). Intact cruciate ligaments were confirmed by MRI. Minimal experience exists in treatment of combined injuries to the PCL and the popliteal artery in children.

Bone Nails↗

PubMed2005

[Cartilage cell transplantation as an alternative to endoprosthesis].

The incidence of cartilage lesions is high. Due to pain and loss of function, long-term therapy is often necessary. Isolated, full-thickness articular cartilage lesions with a diameter of 4 cm2 are indications for chondrocyte transplantation. Many outcome studies report good long-term results. In recent years, the cultivation of chondrocytes has changed. Histologic investigations show hyalin-like cartilage after transplantation. Large cartilage lesions facing each other are a therapeutic dilemma in young patients. Implanting unicondylar or bicondylar prostheses is sometimes the last resort for these patients, and there are several reports of good clinical outcome. Cartilage transplantation has until now been recommended for patients younger than 50. It is not an alternative to joint replacement.

Adult↗

PubMed2005

[Treatment of chronic knee dislocation with an external fixator].

Chronic knee dislocations are rare but represent a therapeutic challenge. A staged concept is necessary to correctly address the pathological components. This article uses a case study to provide an algorithm for the successful treatment of chronic knee dislocations.

Adult↗

PubMed2005

[Prevention of school sport injuries--an analysis of ballsports with 2234 injuries].

PURPOSE: Ball sport school injuries account for a significant morbidity among children and adolescents. MATERIALS AND METHODS: During a school year 2234 school sport injuries have been reported to the Gemeinde Unfall Versicherung (GUV) Niedersachsen, Germany. RESULTS: Regarding the non-gender-specific distribution of the ball sport disciplines, basketball leads with 32 % (n = 431), followed by soccer (24 %, n = 316), volleyball (17 %, n = 232), handball (8.3 %, n = 110) and hockey (4.9 %, n = 65). Sprains (27 %) dominate in basketball, followed by ligament distorsions and ruptures (23 %) and fractures (21 %), with frequent finger injuries (61 %) without contact of an opponent, and injuries of the lower extremity (28 %). Soccer leads to contusions (29 %), in 52 % of the lower extremity frequently after collision with an opponent (22 %) or the ball (20 %). In volleyball upper extremity injuries (71 %) dominate with 53 % finger sprains in individual volleyball play. CONCLUSION: Ball school sport injuries account for a significant morbidity with frequent finger injuries. Proprioceptive deficits may play a role in those finger injuries in basketball, volleyball and handball. During hockey, severe dental and facial injuries were apparent. A prospective proprioceptive training program aiming on fingers and the ankle region may therefore be a preventive measure such as helmets with facial protection in hockey school sport.

Adolescent↗

PubMed2005

[Prospective proprioceptive and coordinative training for injury reduction in elite female soccer].

PURPOSE: Does a prospective proprioceptive-coordinative additional training intervention in elite female soccer changes frequency and pattern of injuries? MATERIALS AND METHODS: 24 female soccer players of the German first division team of FC Bayern München were thoroughly supervised during the season 2003/04 regarding injuries resulting in an absence from at least one scheduled training session or game. During the winter break an additional proprioceptive-coordinative training program was initiated, which was performed on a regular basis during the second half of the season. Furthermore, we evaluated jump&reach, throwing power, coordinative skills, and flexibility. RESULTS: All evaluated fitness results increased significantly during the season after the training intervention, such as jump&reach 44 +/- 4 cm vs. 38 +/- 10 cm (p < 0.05), coordinative power left and right leg, respectively (71 +/- 44 s vs. 45 +/- 37 s, 80 +/- 41 s vs. 50 +/- 32 s, both p < 0.05), flexibility left and right hip (89 +/- 8 degrees vs. 78 +/- 13 degrees and 88 +/- 9 degrees vs. 79 +/- 10 degrees, p < 0.05). Comparing the 1st to the 2nd half of the season, 25 vs. 26 injuries after foulplay and 69 vs. 52 without contact occur (p < 0.05). Muscle injuries resulting in game or training absence were significantly reduced by 400% (12 vs. 3, p < 0.05). In the 1st half of the season, 2 anterior cruciate ruptures (ACL) occur vs. none in the 2nd half after the training intervention. CONCLUSION: An additional proprioceptive-coordinative training intervention increases coordinative abilities, jump power, throwing power, and flexibility during a half season. After initiation of the proprioceptive-coordinative training the incidence of muscle injuries resulting in an absence of at least one game or practice session was reduced significantly by 400 %. Regarding the reduced incidence of ACL injuries after proprioceptive-coordinative training in female elite soccer players, further studies have to be performed to elucidate the value of this training intervention.

Adult↗

PubMed2004

Effects of cyclic longitudinal mechanical strain and dexamethasone on osteogenic differentiation of human bone marrow stromal cells.

The aim of the study was to investigate the effect of cyclic mechanical strain on differentiation markers in the presence or absence of dexamethasone. Human bone marrow stromal cells (BMSC) from seven donors (32.5+/-6.2 years) were cultivated with (D+) or without (D-) dexamethasone. A cyclic mechanical strain with an elongation of 2% (D+2; D-2) or 8% (D+8; D-8) was applied for three days with a stimulation time of three times two hours each day. Levels of alkaline phosphatase (ALP) and osteocalcin (OC) were compared after time intervals of four and seven days. mRNA expression of Collagen I, III and Cbfa1 was investigated after one, four, and seven days. ALP levels were significantly increased in the D+8 group after four and seven days (147.1+/-6.3%; p<0.05 and 168.6+/-6,5%; p<0.03) and in the D-8 group after 7 days (197.4+/-10.4; p<0.04). Cyclic strain had a significant influence on ALP-secretion (F=7.5; p<0.01). In the D-8 group there was a significant increase in OC secretion after 4 days (140.9+/-12.5%; p<0.05).; p<0.01). The effect of stretching was significantly stronger than that of dexamethasone (F=17.2 vs. 1.8). Collagen I (Col I) expression was upregulated in D+8 cultures after 4 days (215.0+/-53.3 p<0.04) and after seven days (166.7+/-55.7; p<0.04). Collagen III (Col III) expression was upregulated in D+2 and D+8 cultures after 4 days (200.7+/-16.3 and 185.9+/-12.7; p<0.04) and after seven days (154.4+/-10.1 and 118.8+/-16.4; p<0.04). There was a significant increase of Cbfa1 expression in D+8 cultures at all investigated time intervals (day 1: 105.5+/-3.7%; day 4: 104.7+/-3.0%; day 7: 104.4+/-2.1%; p<0.03). Stretching (F=20.0; p<0.01) was a stronger contributor to Cbfa-1 expression than dexamethasone (F=12.1; p<0.01). Cyclical mechanical stimulation with 8% elongation increases ALP and OC levels and upregulates Col I and III synthesis and Cbfa1 expression. In the short term, cyclical stretching is a stronger differentiation factor than dexamethasone. Cyclical stretching and dexamethasone both enhance the osteogenic commitment of hBMSC.

Adult↗

PubMed2004

[Knee para-articular focal dome osteotomy].

Focal dome osteotomy (FDO) is a cylindrically shaped osteotomy, with corresponding bone cuts rotating around the central axis of the deformity. Thus, complete correction can be achieved without secondary translation. FDO provides high adjustability of the bone ends, optimal bone contact, and high primary stability. As with straight cut closing, neutral, and opening-wedge osteotomies, FDO allows closing, neutral, and opening corrections. Opening FDO allows preservation of bone contact, whereas closing FDO does not require removal of bone stock. The osteotomy can be modified to tighten the medial collateral ligament. A FDO below the tuberosity does not compromise patellofemoral function and reduces the risk of intra-articular fractures. Sufficient bone stock of the proximal tibial or distal femoral fragment allows intramedullary stabilization. FDO is of high value in the treatment of sagittal plane and frontal plane corrections of the knee even in severe deformities.

Bone Malalignment↗

PubMed2004

[Tissue engineering of long bones with a vascular matrix in a bioreactor].

Explore the source record for details and available documents.

Alkaline Phosphatase↗

PubMed2002

[Effect of cyclical stretch on matrix synthesis of human patellar tendon cells].

The significance of mobilization and loading for healing ligaments and tendons is generally accepted today. Local deformation of cells thereby represents the key stimulus for the cellular response. Less is known, however, about the effects of cyclic strain on the cellular and molecular level. The aim of the in vitro investigation was to determine the effect of cyclic mechanical strain on collagen type I and III and on fibronectin formation in human patellar tendon derived fibroblasts. Human patellar tendon derived fibroblasts from 5 donors (mean age 29.2 years) were cultured under standard conditions. Monolayers of subconfluently grown 3rd passage cells were stretched in rectangular silicone dishes with cyclic movement along their longitudinal axes. Cyclic strain (5%, 1 Hz) was applied for 30 min and 60 min, respectively. Carboxyterminal procollagen type I propeptide (P-I-CP) and aminoterminal procollagen type III propeptide (P-III-NP) release was measured by a radio-immunoassay 6 h and 12 h after stretching. The release of fibronectin was measured by nephelometry following immunoreaction with a specific antiserum. Cells from each donor without any cyclic stretching served as controls. Compared with the controls, only cyclic stretching for 60 min resulted in a significantly increased release of P-I-CP and fibronectin after 6 h. The release of P-III-NP was significantly increased 12 h after 30 min of cyclic stretching as well as 6 h and 12 h after 60 min of cyclic stretching, respectively. We conclude that cyclic stretching causes a time-dependent, differential regulation of formation of fibronectin and collagen type I and III. This may effect the quality and thus the mechanical properties of healing tendon and ligament tissues. In order to improve current treatment protocols and to enlarge our knowledge of tissue healing, it is necessary to understand the cellular response to cyclic strain.

Adult↗

PubMed2002

[Grisel syndrome--a trauma surgery rarity].

Atlanto-axial fixed subluxation (Grisel's syndrome) is an uncommon complication of upper neck inflammatory processes and head and neck surgery. We present the case of a 6 year old patient who developed a Grisel's syndrome after an upper respiratory infection. X-rays and CT scans demonstrated a fixed C1 and C2 subluxation which was treated with reposition and application of a Halofixateur. We give a review of the pathogenesis, diagnosis and treatment of this rare syndrome.

Atlanto-Axial Joint↗

PubMed2001

[Outcome analysis after open reconstruction of rotator cuff ruptures. A comparative assessment of recent evaluation procedures].

Outcome evaluation is becoming increasingly important for reconstructive surgery in musculoskeletal diseases. In addition to established shoulder-scores, new outcome-scores are being developed to cover all effects caused by a disease or intervention. Three validated, self-administered shoulder questionnaires were applied prospectively in 23 otherwise healthy patients suffering from rotator cuff deficiency. These were correlated to the Constant-Murley Shoulder Score and to a visual analogue scale for satisfaction. 7 women and 16 men with combined tears of supraspinatus and infraspinatus (mean age 55.3 +/- 10.5, r/l: 14/9, FU 57.8 +/- 15.7 weeks) were gathered prospectively and evaluated pre- and postoperatively with the American Shoulder and Elbow Surgeons Shoulder Index (ASES), the Simple Shoulder Test (SST) and the Disabilities of the Arm, Shoulder and Hand Module (DASH questionnaire). In addition, a visual analogue scale for satisfaction was employed. All four scores as well as the visual analogue scale revealed improvement at a statistically significant level (paired, two-tailed t-test, P < 0.01) after surgery. All questionnaires had a significant correlation with the Constant-Murley Shoulder Score (Pearson's correlation coefficient: ASES: r = 0.871, P < 0.01; DASH: r = -0.758, P = < 0.01; SST: r = 0.494, P < 0.05). All were easy to apply and provided a reliable, postoperative evaluation of shoulder function. The SST was easy to apply, however compound outcome analysis was only possible with the ASES Shoulder Index and the DASH questionnaire. The DASH scale was the most complex evaluation instrument. The Constant-Murley Shoulder Score comprises a physical examination which is advantageous but must be carried out in the clinic. For postoperative assessment, without the patient having to return to the clinic, the ASES Shoulder Index is preferred as it correlates well with the Constant-Murley Shoulder Score (r = 0.871) and the visual analogue scale for satisfaction (r = 0.762).

Adult↗

PubMed2001

Cyclic mechanical stretching enhances secretion of Interleukin 6 in human tendon fibroblasts.

Accelerated rehabilitation after tendon and ligament injuries is widely accepted to avoid adverse effects of immobilization. However, progressive rehabilitation may also lead to an excessive inflammatory soft tissue response. To investigate the amount of loading necessary to accelerate the healing process without causing damage to the healing tissue, we experimentally stretched human tendon fibroblasts of healthy tendons 15 and 60 min with 1 Hz and an elongation of 5% and measured the secretion of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1), platelet-derived growth factor (PDGF), and fibroblast growth factor basic (bFGF). Secretion of IL-6 was significantly induced by 15 min of cyclic biaxial mechanical stretching after 4 and 8 h observation time and by 60 min stretching and 2 h observation time. The growth factors TGF-beta1, bFGF, and PDGF were secreted by human tendon fibroblasts both in stretched cells and controls; however, no increases were related to mechanical stretching. There was no measurable secretion of TNF-alpha in human tendon fibroblasts. These findings suggest that the inflammatory reaction often seen during physiotherapy after tendon and ligament injuries is caused in part by secretion of IL-6 from the stretched human tendon fibroblasts. IL-6 may cause exaggerated proliferation of fibroblasts and synovial cells as seen in rheumatoid arthritis and arthrofibrosis. However, physiological proliferative reactions leading to repair of injured tissue are also possible. IL-6 measured in the synovial fluid may be an important predictor for monitoring and improving therapeutic strategies in terms of tendon/ligament healing.

Cell Line↗

PubMed2001

Arthrofibrosis is the result of a T cell mediated immune response.

It is thought that an excessive fibrotic healing response with diffuse intra-articular scarring leads to arthrofibrosis after trauma and surgery around joints. To clarify the specific cellular mechanism of arthrofibrosis during arthrolysis we took fibrotic tissue samples from 18 patients at varying periods after knee trauma or surgery. Sections were stained with hematoxylin and eosin to study the overall histopathological changes. Major histocompatibility complex (MHC) class II expressing cells as well as CD3, CD4, CD25, CD28, CD68, CD80, and CD83 positive cells were localized immunohistologically. The results demonstrated synovial hyperplasia with fibrotic enlargement of the subintima and infiltration of inflammatory cells. The number of MHC class II expressing cells was increased. Mainly, intimal macrophages and dendritic cells showed positive immunostaining for MHC class II antigens. In the subintima moderate infiltration of T cells including activated T cells (CD25), CD4+ T helper (Th) cells and Th1 and Th2 subsets was detected. There was a slight polarization of the Th1/Th2 balance towards Th1 differentiation. Positive immunostaining for CD80/CD28 indicated the costimulatory signal for T cell activation and clonal expansion. These findings strongly support an immune response as the cause of capsulitis leading to formation of diffuse scar tissue within the knee joint. Based on our immunohistological study we conclude that a T cell mediated immune response plays a crucial role in the mechanism of arthrofibrosis.

Adolescent↗