[Outcome between surgical and non-surgical treatment of metastatic tumors of the spine: a retrospective study of 259 patients]. / Vergleich zwischen operativen und nicht-operativen Verfahren bei Wirbelsäulenmetastasen: Eine retrospektive Studie an 259 Patienten.

AIM: The purpose of this study was to evaluate the clinical outcome of patients with metastatic tumors of the spine after surgical and non-surgical treatment. METHODS: The charts of 259 patients with metastatic tumors of the spine were reviewed retrospectively to define predictors of outcome. Our data included patient demographics, primary tumor, location of the metastatic tumor within the spine, indication for surgical or non-surgical treatment, type of surgical and non-surgical intervention, post-treatment outcome in terms of neurology, use of adjuvant radiation therapy or systemic therapy. RESULTS: The most frequent indication for surgical treatment was the combination of neurological deficit (ND), pathological vertebral fracture, and pain (50 %). Surgical intervention was performed by the posterior approach in 67 %, by the anterior approach in 13 %, and by an anterior/posterior approach in 10 %. The post-surgical outcome, depending on the type of surgical approach in terms of ND, was for the posterior approach 29 % improved, for the anterior approach 53 % improved, and for the anterior/posterior approach 15 % improved. DISCUSSION: Our data suggest that the indications for metastatic tumor surgery in the spine depend on the location of the metastatic tumor in the spine, clinical symptoms, and prognosis.

[Biomechanical properties of bioabsorbable cannulated screws for surgical fixation of dislocated epiphysiolysis capitis femoris]. / Biomechanische Eigenschaften bioabsorbierbarer kanülierter Schrauben zur operativen Fixierung bei dislozierter Epiphysiolysis capitis femoris.

Bioabsorbable materials are well suited for fixation of slipped capital femoral epiphysis (SCFE) as they are resorbable, compatible with magnetic resonance imaging, and well tolerated by the pediatric population. We compared cannulated 4.5-mm bioabsorbable screws made of self-reinforced polylevolactic acid (SR-PLLA) to cannulated 4.5-mm steel and titanium screws for their resistance to shear stress and ability to generate compression in a polyurethane foam model of SCFE fixation. The maximum shear stress resisted by the three screw types was similar (SR-PLLA 371 +/- 146, steel 442 +/- 43, titanium 470 +/- 91 MPa, NS). The maximum compression generated by both the SR-PLLA screw (68.5 +/- 3.3 N) and the steel screw (63.3 +/- 5.9 N) was greater than that for the titanium screw (3.0 +/- 1.4 N, p < 0.05). These data suggest that cannulated SR-PLLA screws have sufficient biomechanical strength to be used in the treatment of SCFE.

[Effects of early estrogen replacement therapy on bone stability of ovariectomized rats. A biomechanical and radiologic study of the tibial plateau]. / Effekte der frühen Ostrogenersatztherapie auf die Knochenstabilität von ovarektomierten Ratten. Eine biomechanische und radiologische Untersuchung am Tibiaplateau.

Postmenopausal osteoporosis leads to a significant increase in bone fragility. In this study we used the rat tibia plateau fracture model to investigate the efficiency of estrogen replacement therapy (ERT) to mitigate the post-ovariectomy decrease in fracture load. A total of 73 virgin Sprague Dawley rats had been ovariectomized and 26 animals underwent sham operation. The ovariectomized animals were either untreated (n = 35) or treated with estrogen injections (10 micrograms/kg per day 3 days a week until sacrifice), starting treatment at either 0, 5, 8, or 13 days post surgery. Before starting ERT and at 50 days post surgery, the trabecular structure of the right proximal tibial metaphysis of each animal was imaged non-invasively using high resolution X-ray topography. The animals were then sacrificed and the right knee from each animal was harvested and mounted into a servo-hydraulic materials testing system so that the distal femoral condyle could be forced into the proximal tibial plateau until fracture occurred. The failure load (F) of the ovariectomized group without estrogen administration was significantly less than that for the sham group. The mean stiffness (K) of the ovariectomized group was 22 percent less than that of the sham group, though this difference did not reach statistical significance. Across all groups, the failure load and stiffness were significantly correlated with the trabecular bone volume. Our data suggest that prompt ERT can increase the fracture load and stiffness of trabecular bone by allowing bone formation to continue in previously activated bone remodeling units while suppressing the production of new remodeling units. This may be the mechanism by which estrogen and other antiresorptive agents increase bone mass, and thereby reduce the risk of osteoporotic fractures in postmenopausal women.