Biomedical subjects

Christian Krettek

Publications and source records attributed to Christian Krettek.

78 records · Page 5Linked to original sources

PubMed2002

Effects of intramedullary femoral fracture fixation: what is the impact of experimental studies in regards to the clinical knowledge?

This review manuscript summarizes the available literature on animal studies dealing with the local and systemic effects of intramedullary (IM) reamed and unreamed nailing. It focuses on the question of whether the large numbers of studies have contributed to our clinical knowledge about its impact on perfusion, fracture healing, and about the clinical relevance of systemic side effects. The effects of IM contents that are squeezed out of the medullary canal into the venous and the systemic circulation due to reaming and nailing has been a major issue. In addition, the impact of the surgical procedure and the timing of such a major operation as femoral fractures surgery has been a major source of debate within the last decade. The compilation of relevant studies investigating the degree of impact of a surgical procedure and the influence of concomitant injuries depends on the design and the type of the animal model. If this fact is considered and if a model is selected that reflects the systemic impact comparable with the clinical situation, animal studies represent a valuable source of information. In this respect, fat embolization represents an additive surgical impact and can cause clinically relevant side effects if cofactors (e.g., thoracic trauma, severe shock, and polytrauma) are present that set the individual up for postoperative complications.

Animals↗

PubMed2002

Upper sympathetic trunk lesion after video-assisted fracture stabilization of the thoracic spine: a case report.

This case report draws attention to the upper sympathetic trunk lesion as a complication of video-assisted thoracic spine surgery. A 39-year-old man developed an upper sympathetic trunk lesion after right-sided thoracoscopic fracture stabilization of T5 and T6. Dizziness and reduced perspiration persisted at the most recent follow-up 8 months after surgery. This rare complication can be overlooked and remain undiagnosed. Diagnosis is based on clinical symptoms and neurologic examination. There are no treatment options. Symptoms can be bothersome for the patient and may persist. In the upper thoracic spine, the course of the sympathetic trunk lies in close proximity of the vertebral bodies; thus, care must be taken to avoid it when resecting the posterior parts of the vertebral body.

Adult↗

PubMedDate not supplied

Modulation of proliferation and differentiation of human bone marrow stromal cells by fibroblast growth factor 2: potential implications for tissue engineering of tendons and ligaments.

Bone marrow stromal cells (BMSCs) play a central role in the repair and regeneration of mesenchymal tissues. For tissue engineering of ligaments and tendons, both stimulation of cell proliferation and differentiation with increased expression of essential extracellular matrix proteins and cytoskeletal elements are desirable. This study analyzes the effect of low-dose (3 ng/mL) fibroblast growth factor 2 (FGF-2) and high-dose FGF-2 (30 ng/mL) on proliferation (bromodeoxyuridine content, spectrophotometry), differentiation (transcription of collagen I, collagen III, fibronectin, elastin, alpha-smooth muscle actin, and vimentin, reverse transcription-polymerase chain reaction, and cell density and apoptosis (annexin V, fluorescence-activated cell sorting) of human BMSCs, and compares the results with those of a control group without FGF-2. Low-dose FGF-2 triggered a biphasic BMSC response: on day 7, cell proliferation reached its maximum and was significantly higher compared with the other groups. On days 14 or 28, collagen I, collagen III, fibronectin, and alpha- smooth muscle actin mRNA expression was significantly enhanced in the presence of low-dose FGF-2. In contrast, high-dose FGF-2 did not stimulate differentiation or proliferation. Vimentin mRNA was expressed only in cultures with low-dose and high-dose FGF-2 after 14 and 28 days. Cell density was significantly higher in cultures with low-dose FGF-2 compared with the group with high-dose FGF-2 on days 7, 14, and 28. The apoptosis rate remained stable, at a rather high level, in all groups. Microscopic investigation of the cell cultures with low-dose FGF-2 showed more homogeneous, dense, fibroblast-like, spindle-shaped cells with long cell processes compared with cultures with high-dose, or no FGF-2. Low-dose FGF-2 may be useful for tissue engineering of ligaments and tendons by increasing BMSC proliferation and stimulating mRNA expression of specific extracellular matrix proteins and cytoskeletal elements.

Bone Marrow Cells↗

PubMedDate not supplied

Minimally invasive exchange tibial nailing for a broken solid nail: case report and description of a new technique.

We present a minimally invasive technique for the removal of a broken solid tibial nail. A special device was invented that minimizes the extraction difficulties. After minimal over-reaming, the device is slid in an antegrade fashion over the nail and locked. Retraction is safe and easy. This article is an illustrative case-presentation describing the device and the surgical technique.

Adult↗

PubMedDate not supplied

Comparison of surgical repair or reconstruction of the cruciate ligaments versus nonsurgical treatment in patients with traumatic knee dislocations.

BACKGROUND: Studies of traumatic knee dislocations have failed to provide a consensus regarding the best method of treatment. PURPOSE: Our purpose was to evaluate the results after surgical repair or reconstruction versus nonsurgical treatment and to compare the influence of prognostic factors. STUDY DESIGN: Retrospective study. METHODS: Eighty-nine patients were treated for traumatic knee dislocation. Surgical repair or reconstruction of the cruciate ligaments was performed in 63 patients (repair, 49; reconstruction, 14). In 26 patients, nonsurgical treatment was undertaken. RESULTS: At an average follow-up of 8.2 years, the mean Lysholm and Tegner scores were 75 and 3.7, respectively. The outcome in the surgical group was better than in the nonsurgical group. The scores were higher in patients who were 40 years of age or younger, who had sports injuries rather than motor vehicle accident injuries, and who had undergone functional rehabilitation rather than immobilization. CONCLUSIONS: Surgical repair or reconstruction of the cruciate ligaments was superior to nonsurgical treatment. Functional rehabilitation was the most important positive prognostic factor. Surgical repair or reconstruction of the cruciate ligaments is mandatory to achieve sufficient stability for functional rehabilitation. In cases of cruciate ligament avulsion, repair with transosseous fixation is a reasonable alternative to reconstruction, provided that it is performed within 2 weeks of trauma.

Adolescent↗

PubMedDate not supplied

Femoral press-fit fixation of the hamstring tendons for anterior cruciate ligament reconstruction.

BACKGROUND: Press-fit fixation of patellar tendon-bone anterior cruciate ligament autografts is an interesting technique because no hardware is necessary. For hamstring tendon grafts, no biomechanical data exist of a press-fit procedure. HYPOTHESIS: Press-fit femoral fixation of hamstring tendons is mechanically equivalent to press-fit patellar tendon-bone fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Patellar and hamstring tendons of 30 human cadavers (age, 53.8 +/- 18.0 years) were used. An outside-in press-fit fixation with a knot in the semitendinosus and gracilis tendons and an inside-out and outside-in fixation with the tendons wrapped around a bone block were compared with patellar tendon-bone press-fit fixation in 30 ovine femora. Constructs were cyclically strained and then loaded until failure. Maximum load to failure, stiffness, and elongation during failure testing and cyclical loading were investigated. RESULTS: The maximum load to failure was 561 +/- 309 N for the patellar tendon, 599 +/- 234 N for the semitendinosus/gracilis tendons knot construct, 678 +/- 231 for the semitendinosus/gracilis tendons bone construct inserted outside in, and 339 +/- 236 for the semitendinosus/gracilis tendons bone construct inserted inside out (inferior to the others; analysis of variance, Dunn test, P < .01). Stiffness of the constructs averaged 134 +/- 32 N/mm for the patellar tendon, 124 +/- 21 N/mm for the knot construct, 118 +/- 27 N/mm for the outside-in fixation, and 117 +/- 23 N/mm for inside-out fixation. Elongation during initial cyclical loading was 0.7 +/- 0.6 mm for the patellar tendon, 1.6 +/- 0.5 mm for the knot construct, 1.9 +/- 1.2 mm for the outside-in fixation, and 1.9 +/- 0.9 mm for the inside-out fixation (significantly larger for all semitendinosus/gracilis tendon techniques, P < .05). CONCLUSIONS: Failure loads for the semitendinosus/gracilis tendons bone construct inserted outside in and the semitendinosus/ gracilis tendons knot construct were within the confidence interval of the patellar tendon press-fit fixation. All semitendinosus/ gracilis tendon graft techniques exhibited larger elongation during initial cyclical loading than the patellar tendon graft. There was no difference in stiffness between all techniques. CLINICAL RELEVANCE: Two of the 3 hamstring press-fit fixation techniques showed loads to failure similar to the patellar tendon fixation. Preconditioning of the constructs is critical. These results must be interpreted with care because of high standard deviations.

Adolescent↗