Osteoporotic risk and physeal closure in prepubertal ovariohysterectomized cats.

We aimed to examine the early effects of prepubertal ovariohysterectomy (P-OHE) on bone loss and proximal physeal closure in cats. Fourteen kittens randomly underwent P-OHE or sham operations (S-OP) at three months (mo) of age and were allocated to group I and group II. Each mo between four and nine mo of age, dual-energy X-ray absorptiometry (DEXA) scans were performed to determine the total body bone mineral density (BMD) and bone mineral content (BMC). Proximal radial physeal closure and radial length were determined by radiography. Bone-specific alkaline phosphatase (BAP), carboxy-terminal collagen teleopeptide (CTX), 17-ß estradiol, progesterone, calcium (Ca) and phosphorus (P) were measured in the serum samples. No significant differences were observed between the groups in terms of BMD, BMC, BAP, BAP/CTX, P, progesterone and body weight (BW) (between 4 and 9mo) and for Ca (between 5 and 9mo) and for CTX levels (between 4 and 8mo). The 17-ß estradiol was significantly higher at 6, 8 and 9mo of age in the S-OP group due to puberty (P=0.02, P=0.03 and P=0.02 respectively). Although there was a significant difference (P=0.0002) between the P-OHE and S-OP groups in terms of the proximal radial physeal closure times (7.43±0.20mo and 6.14±0.14mo, respectively), no significant difference was observed for the mean radius length (10.59±0.10cm and 10.06±0.27cm, respectively) at the last evaluation time. In conclusion, prepubertal ovariohysterectomized cats do not have any osteoporotic risks until nine mo of age and exhibit a delayed physeal closure time without a change in radius length.

[Hot saline irrigation as an alternative local adjuvant therapy in local aggressive bone tumors]. / Lokal agresif kemik tümörlerinde alternatif bir adjuvan tedavi olarak sicak su uygulamasi.

OBJECTIVES: This study aimed to develop an alternative thermoinactivation method for biological inactivation of microscopic contamination on the cavity wall following curettage of local aggressive tumors. Hot saline irrigation was applied at various temperatures to bone cavity, with or without tourniquet on the extremity and temperature changes and local effects were investigated in vivo. METHODS: Bone cavities 12 cm3 in size were created in the condylar regions of the hind legs in nine female adult sheep. The cavities were irrigated by hot saline solution at 60, 70, 75, 80, or 100 degrees C, with and without the presence of a tourniquet, and the temperatures 1, 2, 3, and 10 mm distant to the cavity wall were recorded. The animals were sacrificed postoperatively at 2 days, 3 and 6 weeks, and 3 and 7 months for histologic studies. RESULTS: The mean body temperature and temperature inside the bone prior to surgery were measured as 38.1 degrees C and 27.34 degrees C, respectively. Tourniquet application caused a mean decrease of 1.5 degrees C (range 1-2 degrees C) in bone temperature. The highest temperatures measured below 80 degrees C and at 80 degrees C were 55.5 degrees C and 62.5 degrees C in the cavity, and 40.5 degrees C and 42.5 degrees C in the bone, respectively. At 100 degrees C, the color of the bone together with the surrounding soft tissue and muscle tissue turned to yellow-brown-black, and the animal died on the second postoperative day. At temperatures

A robotic indenter for minimally invasive measurement and characterization of soft tissue response.

The lack of experimental data in current literature on material properties of soft tissues in living condition has been a significant obstacle in the development of realistic soft tissue models for virtual reality based surgical simulators used in medical training. A robotic indenter was developed for minimally invasive measurement of soft tissue properties in abdominal region during a laparoscopic surgery. Using the robotic indenter, force versus displacement and force versus time responses of pig liver under static and dynamic loading conditions were successfully measured to characterize its material properties in three consecutive steps. First, the effective elastic modulus of pig liver was estimated as 10-15 kPa from the force versus displacement data of static indentations based on the small deformation assumption. Then, the stress relaxation function, relating the variation of stress with respect to time, was determined from the force versus time response data via curve fitting. Finally, an inverse finite element solution was developed using ANSYS finite element package to estimate the optimum values of viscoelastic and nonlinear hyperelastic material properties of pig liver through iterations. The initial estimates of the material properties for the iterations were extracted from the experimental data for faster convergence of the solutions.

[Comparison of temperature increments in bone cavities induced by methylmethacrylate and heated saline solution]. / Metilmetakrilat ve isitilmis serum fizyolojik uygulamalarinda kemik kavitelerinde olusan sicaklik degisikliklerinin karsilastirilmasi.

OBJECTIVES: We administered saline solution at 70 degrees C and methylmethacrylate to varying volumes of bone cavities and compared temperature changes produced in bone regions at varying distances to the cavity wall. METHODS: We created varying sizes of cavities in the femoral heads of 20 human cadavers (6, 10, 12, and 20 cubic centimeters) and in the knee region of a human cadaver (6, 10, 12, 20, 30, and 40 cubic centimeters). Initially, saline solution at 70 degrees C was administered to all the cavities for 15 minutes by a pulse-irrigation method, during which temperature changes induced within the bone cavity and at specific distances (1, 2, 3, and 10 mm) to the cavity wall were recorded. The bone temperatures were allowed to return to initial values; thereafter, cement was applied and temperature changes at the same distances to the cavity wall, in the cement center, and on the cement surface were recorded. RESULTS: Cement volumes up to 40 cubic centimeters applied to the bone cavities did not produce temperature increments that are reported to be adequate to induce necrosis in the cavity wall. It was thought that cement-induced necrosis in the bone-cement interface was not related to heat, but to other effects exerted by cement application. Compared to cement-induced temperature changes, saline solution at 70 degrees C was always associated with higher temperature increments in the cavity wall. CONCLUSION: Due to its simple applicability at desired temperatures and for any lengths of time, heated saline solution seems to have credentials to be incorporated into local adjuvants that are utilized to eliminate tumoral contamination in the cavity wall following curettage for local aggressive tumors.