Objectives:The purpose of this study was to investigate the electromechanical properties of atrophied muscle in patients with anterior cruciate ligament (ACL) reconstruction and to examine the relationship of changes in these properties for a voluntarily elicited maximal isometric contraction and peripherally stimulated twitch contraction. Background: It is not known if, following ACL reconstruction, a prolonged reaction time to a sudden stimulus is due to impaired proprioception in the knee joint, a prolonged processing interval in the central nervous system, or a greater elasticity in the series elastic component of the quadriceps femoris. Methods: Seventeen patients were recruited 2 to 3 months following a unilateral ACL reconstruction. Both the involved leg (ACL-invo group) and the uninvolved leg (ACL-uninvo group) were studied. Twenty-two athletes (training group) and 18 control subjects (control group) were also tested. These subjects performed voluntary maximal isometric contraction (MVC) of the quadriceps femoris. Maximal twitch response was also elicited by a supramaximal electrical stimulation to the femoral nerve, and surface electromyograms were recorded from the vastus lateralis in all four groups. Results: Total reaction time for MVC in the ACL-invo group (250.47 ms) was prolonged compared to that of the control and training groups. Twitch response in the ACL-invo group (25.26 ms) was prolonged compared to that of the other three groups. Premotor time during both MVC and twitch response did not differ among the four groups. Electromechanical delay during MVC (53.62 ms) and the evoked electromechanical delay in twitch response (20.04 ms) were prolonged in the ACL-invo group as compared to the other three groups. Conclusions: Prolonged electromechanical delay in twitch response may be due to peripheral physiological disruptions (eg, stiffness of the series elastic component, changes of peripheral Science and Biomedical Engineering, Tsukuba, muscle fiber-type composition, or a decrease in function of the excitation-contraction coupling process). A prolonged electromechanical delay in twitch response can also explain the prolonged electromechanical delay observed for MVC. These findings suggest that prolonged total reaction time in MVC, when secondary to a visual stimulus in atrophied human quadriceps femoris muscle after ACL reconstruction, may be principally due to prolongation of electromechanical delay produced by peripheral physiological alterations. However, the contribution of premotor time to prolonged total reaction time was not revealed. Our results do not completely eliminate the possibility that central nervous system processing time and other neural factors are involved in the prolongation of reaction time. J Orthop Sports Phys Ther 2002;32:158-165.

Purpose The objective of this study was to investigate factors that inluence the prevalence of medial and lateral meniscal injuries at the time of anterior cruciate ligament (ACL) reconstruction in patients with ACL injuries. Methods Patients with ACL injuries at 9 institutions were enrolled in this multicentre study. Age, sex, duration between injury and surgery, pivot shift test grade, anterior knee laxity determined using the Kneelax 3 arthrometer, and other variables were assessed by logistic regression analysis. Meniscal conditions were evaluated via arthroscopy. Results In all, 830 patients were enrolled. The prevalence of medial and lateral meniscal tears was 32.0% (266 knees) and 26.5% (220 knees), respectively. Signiicant factors that inluenced the prevalence of medial meniscal injuries were age [odds ratio (OR) 1.03; P = 0.000], side-to-side diferences in instrumented anterior knee laxity before surgery (OR 1.12; P = 0.002), duration between injury and surgery (≥ 12 months) (OR 1.86; P = 0.023), and pivot shift test grade (OR 1.36; P = 0.014). Signiicant factors of lateral meniscal injury were side-to-side diferences in anterior knee laxity before surgery (OR 1.12; P = 0.003) and the male sex (OR 1.50; P = 0.027). Conclusion Greater anterior knee laxity, age, a longer duration between injury and surgery, and a higher pivot shift test grade predicted medial meniscal injury. Greater anterior knee laxity and the male sex predicted lateral meniscal injury. In patients with ACL injuries, the importance of side-to-side diferences in anterior knee laxity should be rediscovered from the viewpoint of meniscal conditions. Level of evidence Level III.

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Introduction: Blount disease is a growth disorder of the medial proximal tibial physis causing a multi-planar deformity of the lower limb. Several types of surgical approaches have been described for the correction of angular deformity including external fixation, opened-/closed- wedge high tibial osteotomy (HTO), and tibial condylar valgus osteotomy. However, they are associated with various disadvantages such as limb length discrepancy, risk of infections, and delayed union at the osteotomy site, especially in cases of severe varus deformity. Case Report: We report a case of a 16-year-old boy with unilateral severe genu varum caused by Blount disease. Considering that the current case, the patient was severely obese and a highly active young boy with severe unilateral genu varum, with the epiphyseal line almost closed, and with no abnormalities with respect to the intra-articular anatomical structures, inverted V-shaped HTO was applied. After the treatment, the boy was not only able to perform his daily activities but was also able to participate in sports quite early. Although the required correction angle was quite large, inverted V-shaped HTO successfully corrects the deformity with minimal disadvantages Conclusion: Inverted V-shaped HTO would be selected as one of the effective treatments for a severely obese, young, and highly active patient suffering from severe genu varum caused by Blount disease. Keywords: Blount disease, genu varum, obesity, high tibial osteotomy (HTO), inverted V-shaped high tibial osteotomy (iVHTO).