This study demonstrated that the values of the muscle torque per unit volume of both injured and uninjured sides of patients with ACL rupture were significantly lower than those of the control group, thereby providing indirect evidence of the hindrance of motor unit recruitment in these patients. The results of the present study also indicate that there may be bilateral QF weakness in patients with ACL rupture. Since persistent QF weakness is a significant barrier to effective rehabilitation in patients with ACL injuries, a better understanding of the underlying mechanisms will allow clinicians and scientists to develop more effective therapeutic strategies for patient rehabilitation.

The purpose of this study was to evaluate motor unit recruitment in the quadriceps femoris (QF) after anterior cruciate ligament (ACL) rupture and repair. Subjects included 24 patients at ≥ 18 months after ACL reconstruction and 22 control subjects with no history of knee injury. A series of cross-sectional magnetic resonance images were obtained to compare the QF of patients' injured side with that of their uninjured sides and that of uninjured control subjects. Muscle torque per muscle volume was calculated as isokinetic peak torque divided by QF muscle volume (cm(3)). The mean muscle torque per unit volume of the injured side of patients was not significantly different from that of the uninjured side or control subjects (one-way ANOVA) Results of the present study were contrary to the results of a previous study that evaluated patients at ≤ 12 months after ACL reconstruction. The present study found that high-threshold motor unit recruitment was restored at ≥ 18 months after ACL reconstruction. Thus, clinicians must develop techniques that increase the recruitment of high-threshold motor units in the QF from the period immediately after the injury until approximately 18 months after ACL reconstruction.

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The scaffold type Leeds-Keio artificial ligament (LK) for ligament reconstruction of the knee provides sufficient strength to require minimal sacrifice of autogenous tissue. This implant works not only as prosthesis but also as scaffold onto which natural tissue grows from the synovium. LK has been in clinical use for anterior cruciate ligament (ACL) reconstruction since 1982, although the operative procedure has been modified and has undergone significant development since that time. Recently, we developed radio frequency-generated glow discharge (RFGGD)-treated LK ligament (LKII, previously indicated as Bio-LK) to improve tissue induction and reported that cell proliferation and cell attachment to artificial fibers increased considerably with this hydrophilic treatment. In this study, we report the findings of reconstructed ACL using LKII, which has been in clinical use since 2003. At reconstruction, LKII was covered with the remnant of the original ACL as much as possible in order to preserve the nerve ending system. Thirteen cases with over 12 months' postoperative history were reviewed. Knee stability was regained after reconstruction without any complications such as joint effusion and chronic synovitis. In one case, postoperative arthroscopy showed that the reconstructed ACL was completely covered with newly formed tissue at 8 weeks postoperatively. Biopsy revealed abundant fibroblasts, collagenous fibers, and vessels around the artificial fibers without marked inflammatory findings. Transmission electron microscope study showed abundant thin collagen fibers, which demonstrated regular orientation to some extent. Fibroblasts were observed with extensive amount of rough endoplasmic reticulum. According to these results, we consider LKII to be superior to LK in tissue induction and maturation.

No abstract

The Leeds-Keio artificial ligament (LK), which was developed not only as a ligament substitute but also as a scaffold for tissue induction in knee ligament reconstruction, has been in clinical use since 1982 in Europe and Japan. Recently, we have developed radio frequency generated glow discharge (RFGD)-treated LK ligament (Bio-LK) to expedite the process of tissue induction and its maturation. In this study of cell adhesion to the scaffold, we report the difference in the covered area with synovial cells when using scaffolds made from treated and untreated materials. Plasma clot methods were used in this study. The covered area on LK and Bio-LK by cells was stained by 0.1% toluidine blue and analyzed using NIH image. The covered area of Bio-LK was about three times higher than that of LK (untreated) at 3 weeks. In scanning electron microscopy, more cells were observed on fibers of Bio-LK, and these filled the space among the fibers more extensively. The spreading of covered area means that cell attachment, cell proliferation, and cell migration on the fibers are likely to be improved. Our experimental study indicates that Bio-LK will possibly speed up the process of induction of autogenous tissue from synovium.

II.

BackgroundThe epidemiological patterns of musculoskeletal injuries or disorders in military personnel have not been well documented and a better understanding is required for proper preventative measures and treatment. Here, we investigated musculoskeletal injuries or disorders among members of the Japan Self-Defense Forces.MethodsAll orthopedic patients (n = 22,340) who consulted to Japan Self-Defense Forces Hospitals were investigated for their type of injury or disorder, the injured body part, the mechanism, and the cause of injuries.ResultsThirty-nine percent of the cases were classified as traumatic injuries, and 61% were classified as non-traumatic disorders. Of the traumatic injury patients, the injured body part was the upper extremity in 32%, the trunk in 23%, and the lower extremities in 45% of the cases. The most common injured body location was the knee followed by the hand/finger and ankle. Exercise was the most common cause of injury, followed by traffic accident and military training.Contusions were the most common traumatic injuries, followed by sprains and fractures. Of non-traumatic disorders, the lower extremities were reported as the injured part in 43% of the disorders. Lumbar spine disorders were the most common non-traumatic disorders, followed by tendon and joint disorders.ConclusionsOver one-third of orthopedic cases among members of the Japan Self-Defense Forces are traumatic injuries, with the knee being the body part most commonly injured and exercise being the leading cause of injury.