Hibiscus Tea, Hormone Balance, and Thrombosis: A Case Report.

An otherwise healthy and active 42-year-old woman, undergoing In-Vitro Fertilization (IVF), developed a deep vein thrombus (a potential side effect of IVF) in her right lower leg after discontinuing the consumption of hibiscus tea. Hibiscus tea contains phytoestrogens which may affect hormone balance - on the one hand reducing the risk of deep vein thrombosis (DVT) and on the other, interfering with the potential success of IVF-related hormone treatments.

Dynamics of an intervertebral disc prosthesis in human cadaveric spines.

Low-back pain is a common, disabling medical condition, and one of the major causes is disc degeneration. Total disc replacements are intended to treat back pain by restoring disc height and re-establishing functional motion and stability at the index level. The objective of this study was to determine the effect on range of motion (ROM) and stiffness after implantation of the ProDisc-L device in comparison to the intact state. Twelve L5-S1 lumbar spine segments were tested in flexion/extension, lateral bending, and axial rotation with axial compressive loads of 600 N and 1,200 N. Specimens were tested in the intact state and after implantation with the ProDisc-L device. ROM was not significantly different in the implanted spines when compared to their intact state in flexion/extension and axial rotation but increased in lateral bending. Increased compressive load did not affect ROM in flexion/extension or axial rotation but did result in decreased ROM in lateral bending and increased stiffness in both intact and implanted spine segments. The ProDisc-L successfully restored or maintained normal spine segment motion.

The mechanical behavior of locking compression plates compared with dynamic compression plates in a cadaver radius model.

OBJECTIVE: The purpose of this cadaveric study was to compare the mechanical behavior of a locked compression plate, which uses threaded screw heads to create a fixed angle construct, with a dynamic compression plate construct in a cadaver radius model. DESIGN: Mechanical study with cyclic testing and high-speed optical motion analysis. SETTING: Biomechanics laboratory at an academic institution. PATIENTS/PARTICIPANTS: Eighteen pairs of fresh-frozen human cadaver radii were divided into 3 groups of 6 to be tested as a group in each of the following force applications: anteroposterior (AP) bending, mediolateral bending, or torsion. INTERVENTION: Each bone was osteotomized leaving a 5-mm fracture gap and then fixed with a plate. For each pair, 1 radius received a standard plate (limited-contact dynamic compression plates; LC-DCP), the contralateral radius was fixed with a locking compression plate (LCP), and specimens underwent cyclic loading. Normalized stiffness, average energy absorbed, and Newton-cycles to failure were calculated. In addition, a 3-dimensional, high-speed, infrared motion analysis system was used to evaluate motion at the fracture site. MAIN OUTCOME MEASUREMENTS: Construct stiffness, fracture site motion, cycles to failure, and energy absorption. Repeated measures ANOVA were used to detect differences between groups with time. RESULTS: In the torsion group, LCP specimens failed at 60% greater Newton-cycles than the LC-DCP (1473 vs. 918; P < 0.05). In the AP group, the LC-DCP absorbed significantly greater energy during 10,000 cycles compared with the LCP group (P < 0.05). The 2 constructs demonstrated different biomechanical behavior with time. As cycling progressed in the LC-DCP specimens under torsion testing, stiffness (measured at the actuator at the bone ends) did not change significantly; however, fracture motion (measured at the fracture surfaces) decreased significantly (P = 0.04). The LCP specimens did not display similar behavior. CONCLUSIONS: Our findings indicated that LCP constructs may demonstrate subtle mechanical superiority compared with the LC-DCP. The LCP specimens had less energy absorption in the AP group and survived longer in the torsion group. Discordance of motion between measurement regions was observed only in the LC-DCP torsion group, and may have been caused by plate-bone slippage or bone-screw subcatastrophic failure. However, many other compared parameters were found to be similar, and the clinical significance of the few differences found between constructs mandates further investigation.

Cancellous bone strains indicate efficacy of stem augmentation in constrained condylar knees.

Modular augmented stems of a constrained condylar knee implant are intended to improve tibial fixation under increased varus/valgus loads, but conflicting studies have not yet indicated the factors determining stem usage and performance. To address this, we combined a paired-tibiae, cadaveric experiment of unstemmed and stemmed tibial components with specimen-specific computational models. We hypothesized that the stem would improve implant stability by decreasing implant motion and compressive strains in the proximal cancellous bone due to load transfer by the stem. The models also would indicate the important factors governing stem performance. Large variations of the displacements arose because of loading and biologic variability indicating the inconclusive effects of a stem. Despite these variations, the models showed that a stem augment consistently decreased the strains (30%-50%) in the bone beneath the tray. In tibiae of sufficient stiffness, the supporting cancellous bone did not approach yield, suggesting that a stem augment may not always be necessary. On the other hand, tibial specimens with reduced bone quality and lower stiffness benefited from a stem augment that transferred load to the distal cortical bone. Therefore, patient selection and proper sizing of the implant were identified as important factors in the analyses.

Anatomy and dimensions of rotator cuff insertions.

The purpose of this study was to devise and implement an accurate and reproducible method of measuring the area and dimensions of the rotator cuff tendon insertions and their distance from the articular surface. Twenty fresh-frozen cadaveric upper-extremity specimens were divided into 2 groups of 10. In group 1 the specimens were dissected, leaving only the most distal rotator cuff tendons attached to the humerus. The periphery of the insertion onto the greater tuberosity was marked at 3-mm intervals. The specimens were then mounted onto a custom jig, and the insertion was mapped by a 3-space digitizer. In group 2 the specimens were prepared by removing all tissues except the rotator cuff muscles and tendons and the joint capsule. The interval between the muscles of the rotator cuff was identified and marked. The rotator cuff muscles and tendons were then removed, leaving only the most distal tendons attached to the tuberosities. The periphery of the individual cuff insertions was then marked as in group 1 and mapped in the same fashion. The articular margin also was marked at similar intervals and mapped with the same technique. The area of insertion of the 3 tendons on the greater tuberosity averaged 6.24 cm(2) (SD, 2.04 cm(2)) in group 1. The mean minimum transverse dimension across the cuff insertion occurred in the mid portion of the supraspinatus, with a mean distance of 14.7 mm (SD, 3.22 mm). In group 2 the mean area of insertion of the supraspinatus was 1.55 cm(2) (range, 0.68-2.64 cm(2); SD, 0.66 cm(2)) and the mean area of insertion for the infraspinatus was 1.76 cm(2) (range, 1.23-2.53 cm(2); SD, 0.40 cm(2)). The distance from the articular margin to the most medial rotator cuff fibers was less than 1 mm along the anterior-most 2.1 cm of the cuff insertion onto the greater tuberosity. No correlation could be made between humeral head dimension and the dimensions of the rotator cuff insertions. The mean minimum medial-to-lateral distance across the rotator cuff insertion was sizeable, at 14.7 mm. This represents the minimum possible distance, as the mathematical calculation to determine the dimensions used a perpendicular measurement. The rotator cuff inserts very closely to the articular margin along the anterior 2.1 cm of the greater tuberosity. These anatomic measurements may be useful in evaluating and reattaching the rotator cuff to the humerus.

Open reduction and internal fixation of humeral nonunions : a biomechanical and clinical study.

BACKGROUND: Several studies have compared different methods for fixation of the midpart of the humeral shaft, but there are only scattered data regarding which type of plate construct provides the best fixation for humeral nonunion. The objectives of this study were (1) to obtain objective data on the performance of four different plate constructs used for fixation of humeral nonunion, and (2) to report our clinical experience with plate fixation of thirty-seven nonunions of the midpart of the humeral shaft. METHODS: In the first part of the study, four plate constructs were compared in a Sawbones model. The groups consisted of (1) a posterior limited-contact dynamic compression plate alone; (2) a posterior limited-contact dynamic compression plate and an interfragmentary screw; (3) a posterior limited-contact dynamic compression plate, a lateral 3.5-mm reconstruction plate, and an interfragmentary screw; and (4) a posterior limited-contact dynamic compression plate and a lateral 3.5-mm reconstruction plate. Tests were performed with use of an MTS Bionix machine in anterior-posterior four-point bending, medial-lateral four-point bending, and external rotation torque. In the second part of the study, the charts of thirty-seven consecutive patients in whom a nonunion of the midpart of the humeral shaft had been treated with plate fixation were reviewed retrospectively. The average age of the patients was forty-eight years (range, thirteen to seventy-eight years). Nineteen patients were treated with a single posterior plate, and eighteen were treated with a two-plate construct with the plates parallel and lying at 90 degrees to each other. All of the nonunions were treated with bone-grafting, and an interfragmentary screw was used in thirty-six of the thirty-seven patients. Radiographs and the clinical status were evaluated at an average of thirteen months postoperatively. RESULTS: The biomechanical testing showed that the two-plate constructs were significantly stiffer than the single-plate constructs in all test modes (p < 0.05). In the clinical part of the study, thirty-four (92%) of the nonunions healed without complications at an average of 4.8 months. Two nonunions treated with the two-plate construct and one treated with one plate failed to heal. CONCLUSIONS: No significant difference in the healing rate was found between the two clinical groups (p = 0.4, beta = 0.9), and the overall healing rate was 92%. However, a two-plate construct with the plates at right angles is mechanically stiffer than a single-plate construct, which might be helpful if rigid stabilization of the humerus at the midshaft level is needed.