Quantifying the differential functional behavior between the medial and lateral meniscus after posterior meniscus root tears.

Meniscus tears of the knee are among the most common orthopedic knee injury. Specifically, tears of the posterior root can result in abnormal meniscal extrusion leading to decreased function and progressive osteoarthritis. Despite contemporary surgical treatments of posterior meniscus root tears, there is a low rate of healing and an incidence of residual meniscus extrusion approaching 30%, illustrating an inability to recapitulate native meniscus function. Here, we characterized the differential functional behavior of the medial and lateral meniscus during axial compression load and dynamic knee motion using a cadaveric model. We hypothesized essential differences in extrusion between the medial and lateral meniscus in response to axial compression and knee range of motion. We found no differences in the amount of meniscus extrusion between the medial and lateral meniscus with a competent posterior root (0.338mm vs. 0.235mm; p-value = 0.181). However, posterior root detachment resulted in a consistently increased meniscus extrusion for the medial meniscus compared to the lateral meniscus (2.233mm vs. 0.4705mm; p-value < 0.0001). Moreover, detachment of the posterior root of the medial meniscus resulted in an increase in extrusion at all angles of knee flexion and was most pronounced (4.00mm ± 1.26mm) at 30-degrees of knee flexion. In contrast, the maximum mean extrusion of the lateral meniscus was 1.65mm ± 0.97mm, occurring in full extension. Furthermore, only the medial meniscus extruded during dynamic knee flexion after posterior root detachment. Given the differential functional behaviors between the medial and lateral meniscus, these findings suggest that posterior root repair requires reducing overall meniscus extrusion and recapitulating the native functional responses specific to each meniscus.

Effect of acute aerobic exercise and histamine receptor blockade on arterial stiffness in African Americans and Caucasians.

African Americans (AA) exhibit exaggerated central blood pressure (BP) and arterial stiffness measured by pulse wave velocity (PWV) in response to an acute bout of maximal exercise compared with Caucasians (CA). However, whether potential racial differences exist in central BP, elastic, or muscular arterial distensibility after submaximal aerobic exercise remains unknown. Histamine receptor activation mediates sustained postexercise hyperemia in CA but the effect on arterial stiffness is unknown. This study sought to determine the effects of an acute bout of aerobic exercise on central BP and arterial stiffness and the role of histamine receptors, in AA and CA. Forty-nine (22 AA, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either histamine receptor antagonist or control placebo. Central blood BP and arterial stiffness measurements were obtained at baseline, and at 30, 60, and 90 min after 45 min of moderate treadmill exercise. AA exhibited greater central diastolic BP, elevated brachial PWV, and local carotid arterial stiffness after an acute bout of submaximal exercise compared with CA, which may contribute to their higher risk of cardiovascular disease. Unexpectedly, histamine receptor blockade did not affect central BP or PWV in AA or CA after exercise, but it may play a role in mediating local carotid arterial stiffness. Furthermore, histamine may mediate postexercise carotid arterial dilation in CA but not in AA. These observations provide evidence that young and healthy AA exhibit an exaggerated hemodynamic response to exercise and attenuated vasodilator response compared with CA.NEW & NOTEWORTHY African Americans are at greater risk for developing cardiovascular disease than Caucasians. We are the first to show that young and healthy African Americans exhibit greater central blood pressure, elevated brachial stiffness, and local carotid arterial stiffness following an acute bout of submaximal exercise compared with Caucasians, which may contribute to their higher risk of cardiovascular disease. Furthermore, African Americans exhibit attenuated vasodilator response compared with Caucasians.

Partial Tears of the Distal Biceps Brachii Tendon: A Systematic Review of Surgical Outcomes.

PURPOSE: To systematically review the literature regarding surgical outcomes for treatment of partial tears of the distal biceps brachii tendon. METHODS: This study was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. A systematic review of the literature regarding treatment of partial tears of the distal biceps tendon was conducted using PubMed, Embase, and Cochrane. Inclusion criteria consisted of studies in the English language on the treatment of partial distal biceps tendon tears. Exclusion criteria consisted of (1) studies without outcome data, (2) studies that did not specify the degree of distal biceps tendon tear (ie, complete rupture vs partial tear), and (3) studies without partial tear subgroup data. Two investigators independently reviewed the abstracts from all identified articles. RESULTS: Only 5 patients who underwent successful nonsurgical treatment were identified; all were treated with different algorithms, and because of the small number, outcomes for nonsurgical treatment are not included in this review. Therefore, 19 studies involving 86 partial tears that underwent surgical treatment are reported; at least 65 of these received a trial of nonsurgical treatment before surgery. Surgery resulted in 94% satisfactory clinical outcomes. Of the 16 studies (n = 83) that specified the presence or absence of surgical complications, lateral antebrachial cutaneous nerve paresthesia (17%), posterior interosseous nerve palsy (6%), elbow discomfort (2%), surgical revision (2%), and asymptomatic heterotopic ossification (1%) were reported. CONCLUSIONS: Surgical treatment including tendon tear completion and anatomic repair to the radial tuberosity can yield satisfactory results and appears to provide predictable outcomes. Further research is necessary to better define the optimal regimen and duration of nonsurgical treatment, as well as the indications for surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Differential Post-Exercise Blood Pressure Responses between Blacks and Caucasians.

Post-exercise hypotension (PEH) is widely observed in Caucasians (CA) and is associated with histamine receptors 1- and 2- (H1R and H2R) mediated post-exercise vasodilation. However, it appears that blacks (BL) may not exhibit PEH following aerobic exercise. Hence, this study sought to determine the extent to which BL develop PEH, and the contribution of histamine receptors to PEH (or lack thereof) in this population. Forty-nine (22 BL, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either a combined H1R and H2R antagonist (fexofenadine and ranitidine) or a control placebo. Supine blood pressure (BP), cardiac output and peripheral vascular resistance measurements were obtained at baseline, as well as at 30 min, 60 min and 90 min after 45 min of treadmill exercise at 70% heart rate reserve. Exercise increased diastolic BP in young BL but not in CA. Post-exercise diastolic BP was also elevated in BL after exercise with histamine receptor blockade. Moreover, H1R and H2R blockade elicited differential responses in stroke volume between BL and CA at rest, and the difference remained following exercise. Our findings show differential BP responses following exercise in BL and CA, and a potential role of histamine receptors in mediating basal and post-exercise stroke volume in BL. The heightened BP and vascular responses to exercise stimulus is consistent with the greater CVD risk in BL.