BACKGROUND: The combined associations of changes in cardiorespiratory fitness and body mass index (BMI) with mortality remain controversial and uncertain.
METHODS AND RESULTS: We examined the independent and combined associations of changes in fitness and BMI with all-cause and cardiovascular disease (CVD) mortality in 14 345 men (mean age 44 years) with at least 2 medical examinations. Fitness, in metabolic equivalents (METs), was estimated from a maximal treadmill test. BMI was calculated using measured weight and height. Changes in fitness and BMI between the baseline and last examinations over 6.3 years were classified into loss, stable, or gain groups. During 11.4 years of follow-up after the last examination, 914 all-cause and 300 CVD deaths occurred. The hazard ratios (95% confidence intervals) of all-cause and CVD mortality were 0.70 (0.59-0.83) and 0.73 (0.54-0.98) for stable fitness, and 0.61 (0.51-0.73) and 0.58 (0.42-0.80) for fitness gain, respectively, compared with fitness loss in multivariable analyses including BMI change. Every 1-MET improvement was associated with 15% and 19% lower risk of all-cause and CVD mortality, respectively. BMI change was not associated with all-cause or CVD mortality after adjusting for possible confounders and fitness change. In the combined analyses, men who lost fitness had higher all-cause and CVD mortality risks regardless of BMI change.
CONCLUSIONS: Maintaining or improving fitness is associated with a lower risk of all-cause and CVD mortality in men. Preventing age-associated fitness loss is important for longevity regardless of BMI change.
BACKGROUND: The goal of anterior cruciate ligament reconstruction is to attain a graft that closely resembles the native anterior cruciate ligament anatomy. By reconstructing the original anatomy, one hopes to eliminate issues related to graft elongation, impingement, and excessive tension while achieving ideal knee kinematics.
HYPOTHESIS: Clinical grafts placed using the transtibial technique will differ in the sagittal and coronal planes when compared with obliquity of the anatomic anterior cruciate ligament.
STUDY DESIGN: Controlled laboratory study/case series; Level of evidence, 4.
METHODS: With the assistance of computer navigation, our study compared the anterior cruciate ligament orientation of 5 cadaver knees with 12 clinical anterior cruciate ligament-reconstructed knees using the transtibial technique.
RESULTS: Clinical graft obliquity differed from the anatomic anterior cruciate ligament in all flexion angles: 0 degrees, 30 degrees, 60 degrees, and 90 degrees. In the sagittal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 13.6 degrees, 12.7 degrees, 16.7 degrees, and 17 degrees, respectively. In the coronal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 4.9 degrees, 7.6 degrees, 8.9 degrees, and 12.7 degrees, respectively. Paired t tests demonstrated that the difference between the clinical and anatomic anterior cruciate ligament was significant (P <.05), except in the coronal plane at 0 degrees of flexion. In spite of this, all patients demonstrated a negative pivot shift and Lachman at the conclusion of their reconstructions and at 6-month follow-up.
CONCLUSION: The sagittal and coronal plane obliquity of well-functioning grafts placed using the transtibial technique were more vertical than anatomic fibers.
CLINICAL RELEVANCE: Graft obliquity, in both the coronal and sagittal plane, may be an important means to target appropriate anterior cruciate ligament graft position and can be monitored using surgical navigation systems.
BACKGROUND: The native anterior cruciate ligament (ACL) does not behave as a simple bundle of fibers with constant tension but as a continuum of ligament fibers with differential length change during knee flexion/extension. Computer-assisted navigation can be used to assess length change in different fibers within the native ACL and to evaluate how different reconstruction grafts replicate the range of native ligament fiber length change behavior.
HYPOTHESIS: Anterior cruciate ligament reconstruction graft size and configuration (single-vs double-bundle) are deciding factors as to how much of the native ACL fiber length change behavior is replicated.
STUDY DESIGN: Controlled laboratory study.
METHODS: The fiber length change behavior of the entire native ACL was assessed by measuring the length change pattern of representative anteromedial (AM) and posterolateral (PL) bundle fibers (1 at the center and 4 at the periphery of each bundle). The tibial and femoral ACL attachment areas in 5 fresh-frozen cadaveric knees were digitized, and the length change of each representative fiber was recorded during knee flexion/extension using an image-free, optical navigation system. Subsequently, single-bundle ACL reconstructions of different diameters (6, 9, and 12 mm) positioned at the center of the overall native femoral and tibial attachment sites were modeled to assess how much of the range of ligament fiber length change of the native ligament was captured. This was compared with a double-bundle graft using 6-mm-diameter AM and PL grafts positioned at the centers of the femoral and tibial attachment sites of each separate bundle.
RESULTS: The 6-, 9-, and 12-mm single-bundle grafts simulated 32%, 51%, and 66% of the ligament fiber length change behavior of the native ACL, respectively. The length change patterns in these grafts were similar to the central fibers of the native ACL: the PL fibers of the AM bundle and AM fibers of the PL bundle. However, even a 12-mm graft did not represent the most AM and PL native fibers. The 6-mm AM and PL bundle grafts (equivalent in cross-sectional area to a 9-mm single-bundle graft) simulated 71% of the native ACL and better captured the extremes of the range of native ligament fiber length change.
CONCLUSION: Increasing single-bundle graft size appears to capture more of the range of native ACL fiber length change. However, for a similar graft cross-sectional area, a 2-bundle graft simulates the length change behavior of the native ligament more precisely and thus may better emulate the synergistic actions of anisometric and isometric fibers of the native ligament in restraining knee laxity throughout the range of flexion.
CLINICAL RELEVANCE: The range of native ACL fiber length change behavior is better replicated by larger diameter grafts but may be best reproduced by double-bundle reconstruction.
ACL insufficiency can be documented clinically with the pivot shift maneuver, but the specific pathologic kinematics of the pivot shift is difficult to quantify. Navigation provides an opportunity to analyze in vivo the motions that comprise the pivot shift and the kinematic changes that are inherent after ACL reconstruction. We hypothesized that tibial rotation, anterior tibial translation (ATT), acceleration of posterior translation (APT) and the newly described angle of P, quantified during navigated pivot shift examination, correlate with clinical grading of the pivot shift phenomena. Navigation data from 12 patients who underwent navigated ACL surgery were retrospectively reviewed. A characteristic P-shaped track of motion is recorded by the navigation software during the pivot-shift examination. The "angle of P" was developed as a means characterizing this track of motion and was measured in all cases. The tibial rotation, maximum anterior tibial translation and acceleration of posterior translation during the pivot shift were also measured. The charts of these patients were reviewed to obtain information on the clinical grading of the pivot-shift before and after ACL reconstruction. Spearman correlation analysis was then used to identify significant correlations between clinical grade of the pivot shift and the angle of p measured with computer navigation. After reconstruction, the clinical grade of the pivot shift was zero in all patients. The tibial rotation, maximum ATT, APT and the angle of p also decreased. On analysis of 24 EUAs, 12 before reconstruction and 12 after, there was excellent and significant correlation between the clinical grade of pivot shift examination and the angle of P (R2 = 0.97, p < 0.001). Only good correlation was noted between the clinical pivot shift and the rotation (R2 = 0.77, p < 0.0001), maximum ATT (R2 = 0.87, p < 0.0001) and APT (R2 = 0.81, p < 0.0001). There was a stepwise increase of 6-7 mm of translation and 5-6 degrees of rotation for each increasing grade of pivot shift. There were also increases in the angle of P and APT for each increasing grade of pivot. A decrease in tibial rotation, maximum ATT, APT and angle ofp is detected by computer navigation with ACL reconstruction, correlating with clinical grading. Clinical quantification of the distinct elements of the pivot shift may allow for more accurate evaluation of different ACL reconstruction constructs. There is also potential for these variables to be measured intraoperatively and guide ACL reconstruction when computer navigation is employed.