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Biomedical subjects

L Gotzen

Publications and source records attributed to L Gotzen.

144 records · Page 8Linked to original sources
PubMed1977

[A simple device for examination of the ankle joint (author's transl)].

Ligamentous injuries of the ankle joint can be demonstrated radiologically by special techniques using lateral and A.P. projections. A device is described for obtaining the requisite views. It enables accurate projections to be achieved and a standardised technique is assured by applying a pull of constant weight. The problem of muscle spasm, resulting as a reflex from pain, is discussed.

Ankle Joint↗
PubMed1977

[Distribution and causes of injuries in seat belt-wearing automobile passengers].

We analized 71 car head-on collisions with 100 persons involved wearing seat belts. All 31 passengers with faulty belt function (group II) suffered injuries, 7 of them fatal. 69 passengers with correct belt function were only slightly injured if at all (group I). The majority of the injuries in group I are those of the chest and lower extremities, in group II, however, of the head and lower extremities. The "absolute degree of trauma" revealed the maximal extent of trauma for group II in the region of head, chest and pelvis/abdomen. Increased deformation of the vehicle results in an increase of severe injuries especially in passengers of group II.

Abdominal Injuries↗
PubMed1976

[Experimental examinations in plate-prebending--a contribution to the biomechanics of compression osteosynthesis (author's transl)].

The rigid fixation of bone fragments by compression osteosynthesis with plate produces a high degree of resistance against bending forces, and over the surface friction against rotatory movements. In this way, a uniform distribution of pressure extending over the whole bone section is effected. But by virtue of the asymmetric positioning of the plate on bone-shaft, a torque effect is caused when strain is applied bringing about a distraction of the cortex on the side opposite the plate. Human femoral and tibial specimens would be osteomatized and then stabilized with AO plate adapted to conform to the surface of the bones, under a tension of 70 and 140 kp. With narrow plates having a inferior rigidity there is a greater distraction than is the cause with the wide plates. To compensate against the torque effect, the plates would be prebent. Two measuring methods would be investigate by which the correlation between prestraining and prebending could be determined. To achieve a constant distribution of pressure the narrow plates would have to be prebent to a greater degree than the wide ones, and the DC plates more than the standard plates.

Biomechanical Phenomena↗
PubMed1975

[Injuries, --causes and mechanics of motor vehicle side impacts].

In 228 vehicle-accidents the incidence of side-impact was 25%, being second to frontal impact. 20% of passengers involved sustained severe trauma (AISm 3 - 5). Characteristic of side-impact is a higher trauma rate of upper body with relative sparing of the cervical spine. Pelvic and abdominal injuries are rare but usually severe. The high risk for head and thorax is shown by the "absolute-trauma-index" (incidence x severity of trauma). Severity of trauma rises with vehicle-deformation and is more severe on the side of the impact.

Accidents, Traffic↗
PubMedDate not supplied

[Biocompatibility testing of different sterilised or disinfected allogenous bone grafts in comparison to the gold standard of autologous bone grafts--an "in vitro" analysis of immunomodulation].

INTRODUCTION: Repair of large skeletal defects using bone allografts has become a routine procedure in orthopaedic and trauma surgery. Different procedures of sterilisation (82.5 degrees C disinfection; 121 degrees C autoclaving; PES; Tutoplast; 25 kGy gamma irradiation) are available to inactivate bacteria and fungi, including their spores, as well as viruses in human bone allografts. The efficiency of these procedures has been proven. However, the effects on the cellular response are rarely investigated. This present in vitro study investigates the immunological answer of human bone marrow cells to human allogenous and autologous bone platelets which were sterilised by different methods. MATERIALS AND METHODS: Human bone marrow cells and the bone platelets were harvested from patients undergoing a total hip replacement. All patients provided informed consent. Human bone platelets, 10 mm in diameter, 3 mm in height, were produced from femoral heads which were removed within the scope of total hip replacements. They were sterilised by different procedures or were disinfected (gamma radiotherapy, PES/ethanol treatment, Tutoplast procedure, 121 degrees C autoclaving, > 82.5 degrees C thermodisinfection). In addition, an autologous in vitro bone donation was simulated and compared with the allogenous bone grafts. Endobon was evaluated as a bovine hydroxyapatite ceramic. As control a human bone marrow cell culture without bone platelets was used. Over a period of four weeks the changes of the immunogenic cell populations were analysed in vitro (FACS analysis). Light and scanning microscopy were done to reveal morphological differences. As a vitality test the trypan-blue staining was performed. RESULTS: Light and scanning microscopy demonstrated large differences between the various sterilisation and disinfection methods. After 4 weeks the autologous bone platelets were completely covered with homogenously distributed human osteoblast like cells. The heat-sterilised/disinfected transplants demonstrated similar effects compared to the autologous bone grafts while the irradiated bone platelets demonstrated less cell coverage. 2/3 of the cells were vital on average after four weeks, with the exception of the irradiated bone platelets. The FACS analysis revealed in comparison to the control group provable differences in the immunological answer for the autologous bone donation as well as for the differently sterilised or disinfected allogenous bone grafts. The heat sterilisation or, respectively, disinfection methods compared to the autologous bone donation demonstrated almost similar in vitro effects. By far the worst results, characterised by an excessively increased portion of cytotoxic T-cells and a decreased amount of viable cells, were seen in the 25 kGy gamma irradiation samples. CONCLUSIONS: The results demonstrate the influence of the different sterilisation and disinfection procedures on the differentiation of human marrow cells (host). Similar in vitro effects were seen for the autologous and heat-treated bone platelets. The treatment of allogenous bone grafts with PES/ethanol and the Tutoplast procedures showed, just as Endobon, only low differences in comparison with the control cultures. The worse results in the case of the irradiated bone platelets may be explained by the production of free radicals which led to an excessive cell death.

Blood Platelets↗
PubMedDate not supplied

[Biomechanical evaluation of biointegrable suture anchors composed of bovine compact bone in a pull-to-failure test in porcine tibial head specimens].

AIM: Suture anchors of various designs have gained wide acceptance for securing soft tissues to bone. The biointegrable Tutofix CB anchors derived from bovine compact bone are available with diameters of 3 mm (CB3 anchor), 4 mm (CB4 anchor) and 5 mm (CB5 anchor). The CB anchors are push-in anchors and, from the biomechanical standpoint, they are a combination of press-fit and angulation anchors. The purpose of this study was to evaluate the CB anchors for singular pull load-to-failure strength using porcine tibial head specimens as a test model. METHODS: In all specimens, the joint surface was removed by performing a subchondral osteotomy. Axial PQ-CT scans of 12 specimens were obtained to determine the trabecular BMD. The anchors were implanted posteromedially and centrolaterally in the porcine tibial head specimens. After threading the anchors with a steel suture and predrilling of the anchor holes perpendicular to the osteotomy surface they were inserted 4 mm below the osteotomy surface. A universal testing machine applied tensile loads parallel to the axis of insertion at rates of 10 mm/min and 500 mm/min until pull-out failure or anchor breakage and mean anchor fixation strengths were calculated. RESULTS: The fixation strength of the CB anchors was found to be much higher at the dorsomedial implantation site than at the centrolateral implantation site. The CB4 anchors and CB5 anchors provided nearly the same fixation strength at a level much higher than that of the CB3 anchors. Bone mineral density had a strong influence on axial pull-out force of the anchors, especially the CB4 anchors and CB5 anchors. The overall correlation coefficient for bone mineral density with ultimate load-to-failure was 0.869 for the CB4 anchors and 0.716 for the CB5 anchors. Differences in failure strengths were also seen between the low and high extraction rates. With the high extraction rate much higher failure strengths were obtained than with the low extraction rate. The sudden pull eccentrically on the anchors caused a better fixation due to angulation of the anchor within the drill holes. CONCLUSION: In spite of the double worst-case scenario in the testing conditions, the CB anchors provided a high fixation strength in the trabecular bone of porcine tibial head specimens with the CB4 anchors and CB5 anchors being nearly equal and both being superior to the CB3 anchors. Bone mineral density had a strong influence on the axial pull-out force. Our results show that the CB anchors seem to be a reasonable alternative to metal and bioabsorbable suture anchors.

Absorbable Implants↗
PubMedDate not supplied

Acromioclavicular reconstruction augmented with polydioxanonsulphate bands. Surgical technique and results.

During a 5.5-year period, we treated 64 patients with acute acromioclavicular separations by surgical reconstruction. According to the classification of Rockwood and Matsen, 54 patients had type III lesions, 1 patient had a type IV lesion, and 9 patients had type V lesions. Both the coracoclavicular ligaments and the ligaments of the acromioclavicular joint were reconstructed. An additional ligamentous augmentation was performed using completely resorbable 5- and 10-mm polydioxanonsulphate bands. Forty-five patients (70%) were re-examined at 2 to 7.5 years after surgery (mean, 32 months). The results were good or excellent in 40 cases (89%). Forty-one patients (92%) achieved a range of motion with an abduction deficit of less than 20 degrees. Calcifications in the area of the coracoclavicular or acromioclavicular ligaments did not affect the final range of motion. Complications consisted of one subcutaneous infection, one deep infection, and one failure of the reconstruction. Augmenting the reconstruction with polydioxanonsulphate bands allowed an early functional postoperative treatment. With this procedure, patients do not require removal of an implant, and complications from breakage or migration of metal implants are avoided.

Acromioclavicular Joint↗
PubMedDate not supplied

Reconstruction of complete acromioclavicular separations (Tossy III) using PDS-banding as augmentation: experience in 64 cases.

Sixty-four patients with an acute type Tossy III acromioclavicular separation were treated surgically. Both the coracoclavicular ligaments and the ligaments of the acromioclavicular joint were reconstructed. An additional ligamenteous augmentation was performed, using completely resorbable 5 and 10 mm PDS bands. Thirty-nine patients (61%) were reexamined (follow-up time 2-45 months, mean 26 months). Results were good to excellent in 77% of cases. In 91% of patients, a range of motion with an abduction deficit of less than 20 degrees was obtained. Calcifications in the area of the coracoclavicular or acromioclavicular ligaments did not affect the final range of motion. Complications consisted of a subcutaneous infection in one case, a deep infection in another patient and one reluxation. PDS banding enables an early functional postoperative treatment. Implant removal is not required. Complications as breakage or migration of metal implants are avoided.

Acromioclavicular Joint↗