Citations

Regional cerebral ischemia was produced in the rabbit by unilateral transorbital occlusion of the middle cerebral artery (procedure I); the middle cerebral and azygos anterior cerebral or anterior communicating artery (procedure II); or the middle cerebral, azygos anterior cerebral or anterior communicating, and internal carotid artery (procedure III). Evolution of ischemic lesions was examined with the immunohistochemical reaction for tubulin. With procedure I, ischemic lesions did not become constantly visible for 6 h in the basal ganglia and for 8 h in the frontoparietal region of the cerebral cortex. With procedure II, it was shortened to 3 h in the basal ganglia and to 6 h in the cerebral cortex. With procedure III, the ischemic lesions were observed in 1 h both in the basal ganglia and in the cerebral cortex as loss of the reaction for tubulin in the neuropil, nerve cell bodies, and dendrites. The evidence of neuronal damage became apparent in the same areas later by staining with hematoxylin–eosin. The experimental model presented here may be suitable for investigation of the mechanism that shifts reversible ischemia to cerebral infarction and for evaluation of the effectiveness of pharmacological intervention.

The success of vascularized bone grafts from the medial femoral condyle in various clinical applications has sparked renewed interest in the microvascular anatomy of this region. This study describes the arterial supply of the distal medial femoral condyle and its implications in harvesting vascularized bone grafts. The location, branching pattern, internal diameter, and distribution of perforators of the descending genicular artery and superior medial genicular artery in 19 fresh cadaveric lower limbs were recorded. The descending genicular artery was present in 89% and the superior medial genicular artery was present in 100% of specimens with average distances proximal to the articular surface of 13.7 cm and 5.2 cm, respectively. The average number of perforating vessels was greatest in the posterior distal quadrant of the condyle. The blood supply of the medial femoral condyle is plentiful and consistent making it a useful source for free vascularized bone grafts.

Background Tightness of the posteroinferior capsule is assumed to be the cause of internal rotation loss in baseball pitchers. Although the relationship between posterior capsule and subacromial impingement has been recognized, this relationship during the baseball-pitching motion is unclear. Hypothesis Contact pressure during baseball-pitching motion increases with posterior capsule tightness. Study Design Controlled laboratory study. Methods Eight fresh-frozen shoulders were used. The peak contact pressure and area on the coracoacromial arch were measured on a custom-designed shoulder experimental device capable of 6 degrees of freedom motion. Simultaneously, the sites of peak pressure on the coracoacromial arch and humerus were observed from various angles. The posteroinferior capsule tightness was simulated by plicating the capsule in the region from 6 to 8 o'clock. The static testing positions correlated to the early cocking, late cocking, acceleration, deceleration, and follow-through phases of the pitching motion. Results The peak contact pressure during the follow-through phase (0.63 ± 0.50 MPa) significantly increased with posteroinferior capsule tightness (1.00 ± 0.65 MPa) (P = .014). Additionally, the contact area on the coracoacromial ligament during the follow-through phase (0.98 ± 0.67 cm2) significantly increased with posteroinferior capsule tightness (1.47 ± 0.91 cm 2) (P < .001). The site of the peak contact pressure did not change between the 2 conditions. Conclusion Our findings demonstrate that posteroinferior capsule tightness leads to higher contact pressure under the subacromial arch and increased contact area, particularly on the coracoacromial ligament during the follow-through phase. Clinical Relevance This tightness may affect risk of injury of the rotator cuff and its surrounding tissues by increasing subacromial contact during pitching.

Background There have been few biomechanical studies to clarify which size of a glenoid defect is critical. However, those studies have assumed that the defect occurred anteroinferiorly. Recent studies have reported that the defect is located anteriorly rather than anteroinferiorly. Therefore, the effect of the anterior, not anteroinferior, glenoid defect on shoulder stability needs to be investigated. Hypothesis The anterior glenoid defect would have a similar effect on anterior shoulder stability as that of the anteroinferior glenoid defect. Study Design Controlled laboratory study. Methods Eight fresh-frozen cadaveric shoulders were used (mean age, 74 years). The specimen was attached to a shoulder-testing device with the arm in abduction and external rotation. An osseous defect was created stepwise with a 2-mm increment of the defect width. The stability ratio was used to evaluate joint stability. With a 50-N axial force, the translational force applied to the humeral head was measured by a force transducer. Results The stability ratio without a defect (32% ± 6%) significantly decreased after creating a 6-mm defect (17% ± 5%; P = .0001), which was equivalent to 20% of the glenoid length. Conclusion An osseous defect at 3 o'clock with a width that was equal to or greater than 20% of the glenoid length significantly decreased anterior stability. Clinical Relevance The results suggest that reconstruction of the glenoid concavity might be necessary in shoulders with an anterior glenoid defect of at least 20% of the glenoid length.