METHODS: Twelve fresh-frozen cadaveric knees were used. Five components of the quadriceps and the iliotibial band were loaded physiologically with 175N and 30N, respectively. The force required to displace the patella 10mm laterally and medially at 0°, 20°, 30°, 60° and 90° knee flexion was measured. Patellofemoral contact points at these knee flexion angles were marked. The trochlea cartilage geometry at these flexion angles was visualized by Computed Tomography imaging of the femora in air with no overlying tissue. The sulcus, medial and lateral facet angles were measured. The facet angles were measured relative to the posterior condylar datum.
RESULTS: The lateral facet slope decreased progressively with flexion from 23°±3° (mean±S.D.) at 0° to 17±5° at 90°. While the medial facet angle increased progressively from 8°±8° to 36°±9° between 0° and 90°. Patellar lateral stability varied from 96±22N at 0°, to 77±23N at 20°, then to 101±27N at 90° knee flexion. Medial stability varied from 74±20N at 0° to 170±21N at 90°. There were significant correlations between the sulcus angle and the medial facet angle with medial stability (r=0.78, p<0.0001).
CONCLUSIONS: These results provide objective evidence relating the changes of femoral profile geometry with knee flexion to patellofemoral stability.
METHODS: The MS of 5 fresh-frozen cadavers were sequentially dissected. Irrigation was evaluated with a squeeze bottle (SB) in different head positions and using different volumes of fluid. Surgical reach and visualization were examined using common sinus instruments and different angled endoscopes. A disease simulation was also performed to check for residual debris after instrumentation and irrigations.
RESULTS: Irrigation penetration improved as antrostomy size increased (p < 0.0001), with a significant difference observed between the extended procedures and MMA. The effect of the volume was significant for SB (p < 0.0001) but head positions appeared irrelevant (p = 0.613). Overall visualization improved for Mega-A and EMMA. A similar trend was seen for the reach of the instruments to all sinus wall subsites. EMMA facilitated the most removal of "sinus disease" in the disease simulation model when compared with both MMA and Mega-A, due to its reach of the anteroinferior aspects of the maxillary sinus.
CONCLUSIONS: High-volume irrigation using SB achieved good sinus penetration, irrespective of head position. Extended MS procedures appear to further increase irrigation penetration as well as surgical access.
MATERIALS AND METHODS: We retrospectively assessed 107 cadavers that had undergone conventional autopsy and PMCT. We made 5 measurements from the PMCT that included cervical length (CL), thoracic length (TL), lumbosacral length (LS), total column length of the spine, excluding the sacrum and coccyx (TCL), and ellipse line measurement of the whole spine, excluding the sacrum and coccyx (EL). We compared these anthropometric PMCT measurements with AL and correlated them using linear regression analysis.
RESULTS: The results showed a significant linear relationship existed between TL and LS with AL, which was higher in comparison with the other parameters than the rest of the spine parameters. The linear regression formula derived was: 48.163 + 2.458 (TL) + 2.246 (LS).
CONCLUSIONS: The linear regression formula derived from PMCT spine length parameters particularly thoracic and lumbar spine gave a finer correlation with autopsy body length and can be used for accurate estimation of cadaveric height. To the best of our knowledge, this is the first ever linear regression formula for cadaveric height assessment using only post mortem CT spine length measurements.
METHODOLOGY: Jaw sections containing 67 teeth (86 roots) were collected from unclaimed bodies due for cremation. Imaging was carried out to detect AP by digital PR with a central view (DP group), digital PR combining central with 10˚ mesially and distally angled (parallax) views (DPS group) and CBCT scans. All specimens underwent histopathological examination to confirm the diagnosis of AP. Sensitivity, specificity and predictive values of PR and CBCT were analysed using rater mean (n = 5). Receiver-operating characteristic (ROC) analysis was carried out.
RESULTS: Sensitivity was 0.27, 0.38 and 0.89 for DP, DPS and CBCT scans, respectively. CBCT had specificity and positive predictive value of 1.0 whilst DP and DPS had specificity and positive predictive value of 0.99. The negative predictive value was 0.39, 0.44 and 0.81 for DP, DPS and CBCT scans, respectively. Area under the curve (AUC) for the various imaging methods was 0.629 (DP), 0.688 (DPS), and 0.943 (CBCT).
CONCLUSIONS: All imaging techniques had similar specificity and positive predictive values. Additional parallax views increased the diagnostic accuracy of PR. CBCT had significantly higher diagnostic accuracy in detecting AP compared to PR, using human histopathological findings as a reference standard.
QUESTION/PURPOSE: Does a controlled deep-freezing temperature during irradiation help preserve the compressive mechanical properties of human femoral cortical bone allografts?
METHODS: Cortical bone cube samples, each measuring 64 mm3, were cut from the mid-diaphyseal midshaft of five fresh-frozen cadaver femurs (four male donors, mean [range] age at procurement 42 years [42 to 43]) and were allocated via block randomization into one of three experimental groups (with equal numbers of samples from each donor allocated into each group). Each experimental group consisted of 20 bone cube samples. Samples irradiated in dry ice were subjected to irradiation doses ranging from 26.7 kGy to 27.1 kGy (mean 26.9 kGy) at a deep-freezing temperature below -40°C (the recommended long-term storage temperature for allografts). Samples irradiated in gel ice underwent irradiation doses ranging from 26.2 kGy and 26.4 kGy (mean 26.3 kGy) in a freezing temperature range between -40°C and 0°C. Acting as controls, samples in a third group were not subjected to gamma irradiation. The mechanical properties (0.2% offset yield stress, ultimate compression stress, toughness, and the Young modulus) of samples from each group were subsequently evaluated via axial compression loading to failure along the long axis of the bone. The investigators were blinded to sample group during compression testing.
RESULTS: The mean ultimate compression stress (84 ± 27 MPa versus 119 ± 31 MPa, mean difference 35 [95% CI 9 to 60]; p = 0.005) and toughness (3622 ± 1720 kJ/m3 versus 5854 ± 2900 kJ/m3, mean difference 2232 [95% CI 70 to 4394]; p = 0.009) of samples irradiated at a higher temperature range (-40°C to 0°C) were lower than in those irradiated at deep-freezing temperatures (below -40°C). The mean 0.2% offset yield stress (73 ± 28 MPa versus 109 ± 38 MPa, mean difference 36 [95% CI 11 to 60]; p = 0.002) and ultimate compression stress (84 ± 27 MPa versus 128 ± 40 MPa, mean difference 44 [95% CI 17 to 69]; p < 0.001) of samples irradiated at a higher temperature range (-40°C to 0°C) were lower than the nonirradiated control group samples. The mean 0.2% offset yield stress (73 ± 28 MPa versus 101 ± 28 MPa, mean difference 28 [95% CI 3 to 52]; p = 0.02; effect size = 1.0 [95% CI 0.8 to 1.2]) of samples irradiated at higher temperature range (-40°C to 0°C) were no different with the numbers available to those irradiated at deep-freezing temperature. The mean toughness (3622 ± 1720 kJ/m3 versus 6231 ± 3410 kJ/m3, mean difference 2609 [95% CI 447 to 4771]; p = 0.02; effect size = 1.0 [95% CI 0.8 to 1.2]) of samples irradiated at higher temperature range (-40°C to 0°C) were no different with the numbers available to the non-irradiated control group samples. The mean 0.2% offset yield stress, ultimate compression stress, and toughness of samples irradiated in deep-freezing temperatures (below -40°C) were not different with the numbers available to the non-irradiated control group samples. The Young modulus was not different with the numbers available among the three groups.
CONCLUSION: In this study, maintenance of a deep-freezing temperature below -40°C, using dry ice as a cooling agent, consistently mitigated the adverse effects of irradiation on the monotonic-compression mechanical properties of human cortical bone tissue. Preserving the mechanical properties of a cortical allograft, when irradiated in a deep-freezing temperature, may have resulted from attenuation of the deleterious, indirect effects of gamma radiation on its collagen architecture in a frozen state. Immobilization of water molecules in this state prevents radiolysis and the subsequent generation of free radicals. This hypothesis was supported by an apparent loss of the protective effect when a range of higher freezing temperatures was used during irradiation.
CLINICAL RELEVANCE: Deep-freezing temperatures below -40°C during gamma irradiation may be a promising approach to better retain the native mechanical properties of cortical bone allografts. A further study of the effect of deep-freezing during gamma radiation sterilization on sterility and other important biomechanical properties of cortical bone (such as, tensile strength, fracture toughness, and fatigue) is needed to confirm these findings.