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.
METHODOLOGY: Jaw sections containing 67 teeth (86 roots) were collected from nine fresh, unclaimed bodies that were due for cremation. Imaging was carried out to detect AP lesions using film and digital PR with a centred view (FP and DP groups); film and digital PR combining central with 10˚ mesially and distally angled (parallax) views (FPS and DPS groups). All specimens underwent histopathological examination to confirm the diagnosis of AP. Sensitivity, specificity and predictive values of PR were analysed using rater mean (n = 5). Receiver operating characteristics (ROC) analysis was carried out.
RESULTS: Sensitivity was 0.16, 0.37, 0.27 and 0.38 for FP, FPS, DP and DPS, respectively. Both FP and FPS had specificity and positive predictive values of 1.0, whilst DP and DPS had specificity and positive predictive values of 0.99. Negative predictive value was 0.36, 0.43, 0.39 and 0.44 for FP, FPS, DP and DPS, respectively. Area under the curve (AUC) for the various imaging methods was 0.562 (FP), 0.629 (DP), 0.685 (FPS), 0.6880 (DPS).
CONCLUSIONS: The diagnostic accuracy of single digital periapical radiography was significantly better than single film periapical radiography. The inclusion of two additional horizontal (parallax) angulated periapical radiograph images (mesial and distal horizontal angulations) significantly improved detection of apical periodontitis.
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.
METHODS: Twenty six donkey cadavers of mixed, age, sex and use presented for reasons unrelated to disease of the guttural pouch were subjected to carotid and cerebral angiography using rotational angiography. Rotational angiographic and 3 dimensional multiplanar reconstructive (3D-MPR) findings were verified with an arterial latex casting technique followed by dissection and photography.
RESULTS: The following variations of the carotid arterial tree were identified: [1] the internal carotid and occipital arteries shared a common trunk, [2] the linguofacial trunk originated from the common carotid artery causing the common carotid artery to terminate as four branches, [3] the external carotid artery was reduced in length before giving rise to the linguofacial trunk, mimicking the appearance of the common carotid artery terminating in four branches, [4] the internal carotid artery originated at a more caudal position from the common carotid artery termination.
CONCLUSION: Veterinarians should be aware that considerable variation exists in the carotid arterial tree of donkeys and that this variation may differ markedly from that described in the horse.
OBJECTIVE: The aim of this study was to assess the safety and pullout strength of medial, partial nonthreaded thoracic pedicle screws compared with conventional screws.
SUMMARY OF BACKGROUND DATA: The perforation rate of the pedicle screws has been reported as high as 41%. Nerve injury and irritation can result from the compression of malpositioned screw on neural structures.
METHODS: Ten fresh cadavers were studied. Screws, 5.0 and 6.0 mm, were inserted from T1 to T6 and T7 to T12, respectively. Pedicle perforations and fractures were recorded upon screw insertion and final positioning (nonthreaded portion facing medially) after a wide laminectomy. Pullout strength of novel and conventional screws were then tested using an Instron machine in an artificial bone substitute.
RESULTS: A total of 240 thoracic pedicle screws were inserted. Of them, 88.8% (213 screws) were fully contained during screw insertion. There were 5.0% (12 screws) grade 1 medial perforations and 6.2% (15 screws) grade 1 lateral perforations during screw insertion. Upon final positioning, 93.8% (225 screws) were fully contained. All grade 1 medial perforations, which occurred during insertion, were converted to grade 0. No dural or nerve root injuries occurred. Pedicle split fractures were noted in 6.7% (16 screws). The use of medial, partial nonthreaded screws reduced the overall perforation rate from 11.2% to 6.2%. The mean pullout load for the 5 mm fully threaded screw versus medial, partial nonthreaded was 1419.3±106.1 N (1275.8-1538.8 N) and 1336.6±44.2 N (1293.0-1405.1 N) respectively, whereas 6 mm pullout load averaged 2126.0±134.8 N (1986.3-2338.3 N) and 2036.5±210.0 N (1818.4-2355.9 N). The difference was not statistically significant.
CONCLUSIONS: The use of medial, partial nonthreaded pedicle screws reduced the medial perforation rate from 5.0% to 0%; however, the pullout strength was not significantly reduced. The use of this novel screw can potentially reduce the incidence of nerve injury or irritation after medial pedicle perforations.