Internet use and physical activity of older adults during the COVID-19 pandemic: a cross-sectional study in a northern Japanese City.

BACKGROUND: Little is known of whether Internet use is associated with physical activity among socially isolated older adults during the coronavirus disease 2019 (COVID-19) pandemic. This study investigated the association between Internet use and physical activity, and whether this association differs depending on social isolation among community-dwelling Japanese older adults. METHODS: A cross-sectional study was conducted with 1048 community-dwelling residents aged 65-90 years. Data were obtained using a self-reported questionnaire in August 2020. Physical activity was assessed using the International Physical Activity Questionnaire-Short Form. Multivariable logistic regression analyses were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between Internet use and moderate-to-vigorous physical activity (MVPA). RESULTS: Internet use showed a significant association with MVPA (OR = 1.42, 95% CI: 1.06-1.90) after adjusting for age, sex, self-reported socioeconomic status, and other health-related characteristics. When the results were stratified by social participation and living status, Internet use was associated with a significantly higher likelihood of MVPA among participants with no social participation (OR = 1.81, 95% CI: 1.03-3.17) and living with family (OR = 1.40, 95% CI: 1.02-1.93). CONCLUSION: Internet use was associated with sufficient physical activity, and this association may differ depending on the social isolation among community-dwelling older adults in Japan.

Associations between Socioeconomic Status, Social Participation, and Physical Activity in Older People during the COVID-19 Pandemic: A Cross-Sectional Study in a Northern Japanese City.

Physical activity (PA) is a key determinant of health in older adults. However, little is known about the effect of social factors on PA among older adults during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, we aimed to clarify the association between socioeconomic status, social participation, and PA during the pandemic. A cross-sectional study was conducted on 999 community-dwelling residents aged 65-90 years. A self-administered questionnaire was used to collect socioeconomic status, social participation, and PA data in August 2020. Multivariable logistic regression analyses were used to calculate the odds ratios (ORs) for the associations between socioeconomic status, social participation, and maintaining PA. For both sexes, PA was reduced by approximately 5%-10% after the onset of COVID-19-related distancing restrictions. Men with a low socioeconomic status were less physically active (OR = 0.49, 95% CI: 0.30-0.82). Women who reported social participation had higher odds of maintaining PA (OR = 1.67, 95% CI: 1.13-2.45) during the restrictions. Higher socioeconomic status and social participation levels before the COVID-19 pandemic may have helped older adults to maintain PA during the COVID-19 pandemic. Further research is needed to clarify the potential effects of these factors on the health of older adults.

An Acute Oblique Osteotomy and Suture Ligation Procedure to Shorten the Fibula in Lateral Closing-Wedge High Tibial Osteotomy.

The purpose of this description is to report an "acute oblique osteotomy and ligation" (AOOL) procedure to shorten the fibula in high tibial osteotomy (HTO). A 4-cm longitudinal skin incision is made at the lateral aspect of the leg. After the central portion of the fibula is circumferentially isolated from all the periosteal tissues, a simple osteotomy is performed at the mid-portion of the fibular diaphysis in the quasi-frontal plane, which is inclined by 25 to 30° to the long axis of the fibula. Two thin holes are created beside the osteotomy line on the lateral surface of the fibula. A polyester thread is passed through the 2 holes. After the HTO is completed, the surgeon easily reduces the displaced fibular ends using this thread. This thread is securely tied to keep the contact between the 2 osteotomized surfaces. The AOOL procedure is technically easy and safely performed. We believe that the AOOL procedure is clinically useful to shorten the fibular shaft in HTO.

Comparison of Graft Length Changes During Knee Motion Among 5 Different Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction Approaches: A Biomechanical Study.

BACKGROUND: In several anatomic single-bundle anterior cruciate ligament (ACL) reconstruction (ASB-ACLR) procedures, the femoral and tibial tunnel apertures are created at different locations within the native ACL attachment area. HYPOTHESIS: Graft length changes during knee motion will be different among ASB-ACLR procedures with different femoral and tibial tunnel aperture locations. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 12 cadaveric knees were used in this study. In each knee, 4 and 3 thin tunnels were created within the ACL attachment area on the femur and the tibia, respectively. Using 1 of 5 different combinations of femoral and tibial tunnel aperture location, 5 ASB-ACLRs were performed on each knee. In each reconstruction approach, a strong thread was used in place of the tendon graft, and the tibial graft end was tethered to a custom-made isometric positioner at 0° of knee flexion, with an approximately 12-N load applied to the thread. Then, each specimen underwent 5 cycles of knee flexion-extension motion in a range between 0° and 120°, and graft length changes were determined for each SB-ACLR approach. RESULTS: The length changes of the graft were significantly different among the 5 ASB-ACLRs. The maximum length change values of the 3 grafts that were implanted between the femoral and tibial centers of the posterolateral bundle attachments or implanted into the femoral tunnel created at the center of the fanlike extension fiber attachment were significantly greater than those of the graft implanted between the centers of the anteromedial bundle attachments (P < .0001) and of the graft implanted between the centers of the whole ACL attachments (P < .0001). CONCLUSION: The length changes of the graft during knee motion were significantly different among the 5 ASB-ACLR approaches, even though all of the tunnel apertures were created within the femoral and tibial attachments of the native ACL. CLINICAL RELEVANCE: The grafts in the first 3 graft locations may be so relaxed during knee flexion that they cannot resist anterior drawer loads exerted on the tibia.

Is the Grafted Tendon Shifted Anteriorly in the Femoral Tunnel at the Postremodeling Phase After Anterior Cruciate Ligament Reconstruction? A Clinical MRI Study.

BACKGROUND: Based on previous in vitro studies, it has been commonly believed that during anterior cruciate ligament (ACL) reconstruction with hamstring tendon, the grafted tendon is shifted anteriorly in the tunnel permanently after the graft is anchored to the tunnel wall. However, this has not been proven by in vivo studies. HYPOTHESIS: At 1 year after anatomic double-bundle ACL reconstruction, the grafted tendons may not be shifted anteriorly in the femoral tunnel but anchored to the bony wall at the center of the tunnel. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Participants consisted of 40 patients who underwent anatomic double-bundle ACL reconstruction. The grafted tendons located in the femoral tunnel were examined 1 year after surgery using 2 different magnetic resonance imaging (MRI) protocols. In the first substudy, with 20 patients, the grafted tendon location was evaluated on an inclined sagittal multiplanar reconstruction (MPR) image taken using a standard T2-weighted protocol. In the second substudy with the remaining 20 patients, tendon location was evaluated on a pure axial MPR image taken using a VISTA (volume isotropic turbo spin echo acquisition) protocol. RESULTS: On the inclined sagittal T2-weighted images of the anteromedial (AM) graft, the anterior width of the newly formed fibrous tissue, which surrounded the tendon graft, was significantly greater than the posterior width (P = .001). The center of the grafted tendon was slightly (mean, 2.5% of the tunnel diameter) but significantly (P = .0310) shifted posteriorly from the tunnel center. On the axial T2-VISTA images, the center of the AM graft was slightly but significantly shifted posteriorly (3.9%; P = .022) and medially (5.5%; P = .002) from the tunnel center. The center of the posterolateral (PL) graft was not significantly shifted to any direction from the center of the tunnel. CONCLUSION: The grafted tendons were not shifted anteriorly in the femoral tunnel 1 year after anatomic double-bundle ACL reconstruction. The PL graft was located approximately at the center of the tunnel outlet, while the AM graft was slightly but significantly shifted posteriorly and proximally.

Clinical results of anterior cruciate ligament reconstruction with ligament remnant tissue preservation: A systematic review.

PURPOSE: To clarify the effects of ACL remnant tissue preservation on the clinical outcome of ACL reconstruction. METHODS: This is a systematic review. RESULTS: The majority of the reviewed articles suggested that remnant preservation significantly improved knee stability after ACL reconstruction, although there was some controversy. In addition, it was suggested that the degree of initial graft coverage significantly affected postoperative knee stability. Remnant preservation did not increase the occurrence rate of cyclops lesion. CONCLUSION: Sufficient coverage of the graft with remnant tissue improves postoperative knee stability without any detrimental effects on the subjective and functional results.

A pilot study of anatomic double-bundle anterior cruciate ligament reconstruction with ligament remnant tissue preservation.

PURPOSE: The purpose of this pilot study was to evaluate the preliminary results of an anatomic double-bundle anterior cruciate ligament (ACL) reconstruction procedure with ligament remnant tissue preservation. METHODS: By use of the transtibial technique, 2 doubled semitendinosus tendons were grafted into 4 tunnels created at the center of each bundle attachment, penetrating the ACL remnant tissue. In total, 44 patients (27 male and 17 female patients) with an isolated ACL injury underwent ACL reconstruction with this procedure. The mean age of the patients was 29 years (range, 17 to 58 years). Postoperative clinical evaluations were performed at 16.6 months on average (range, 12 to 23 months). Radiologic evaluations were also performed to evaluate the tunnel location in the femur and the tibia. RESULTS: The mean operation time was 86 minutes (range, 72 to 96 minutes) in the cases with ACL reconstruction only. Postoperatively, the mean anterior laxity was 0.7 mm. The postoperative pivot-shift test was negative in 81.8% of the patients, whereas there were no patients evaluated as ++. No patients showed any extension or flexion deficit. There were no patients evaluated as "nearly abnormal" or "abnormal" according to the International Knee Documentation Committee evaluation. The tunnel angles of the 4 tunnels were identical to those reported in a previous study. CONCLUSIONS: The minimal 1-year clinical results of anatomic double-bundle ACL reconstruction with ligament remnant tissue preservation were comparable to previously reported results of anatomic double-bundle reconstruction without remnant tissue preservation. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Anatomic double-bundle anterior cruciate ligament reconstruction.

Several double-bundle anterior cruciate ligament (ACL) reconstruction procedures were reported in the 1980s and 1990s. However, no significant differences were found in the clinical results between these double-bundle procedures and single-bundle procedures because the double-bundle procedures appeared to reconstruct only the anteromedial bundle with 2 bundles. In the early 2000s, we proposed a new concept of anatomic reconstruction of the anteromedial and posterolateral bundles, in which 4 independent tunnels were created through the center of each anatomic attachment of the 2 bundles. We called it "anatomic" double-bundle ACL reconstruction. Biomechanical studies have shown that the anatomic double-bundle ACL reconstruction can restore knee stability significantly more closely to the normal level than the conventional single-bundle reconstruction. Recent intraoperative measurement studies have shown that the clinically available anatomic double-bundle procedures can reconstruct knee stability significantly better and improve knee function close to the normal level at the time immediately after surgery compared with the conventional single-bundle procedures. However, the greatest criticism of the anatomic double-bundle reconstruction is whether its clinical results are better than the results of single-bundle reconstruction. To date (January 2010), 10 prospective comparative clinical trials (Level I or II) and 1 meta-analysis have been reported comparing single-bundle and anatomic double-bundle reconstructions using hamstring tendons. In 8 of the 10 studies, the anterior and/or rotatory stability of the knee was significantly better with the anatomic double-bundle ACL reconstruction than with the conventional single-bundle reconstruction. However, 1 original trial and the meta-analysis found that there were no differences in the results between the 2 types of reconstructions. Thus the utility of the anatomic double-bundle reconstruction has not yet been established. Our review does show how much evidence exists as to the benefits of double-bundle ACL reconstruction at present.

Implantation of autogenous meniscal fragments wrapped with a fascia sheath enhances fibrocartilage regeneration in vivo in a large harvest site defect.

BACKGROUND: Concerning meniscal tissue regeneration, many investigators have studied the development of a tissue-engineered meniscus. However, the utility still remains unknown. HYPOTHESIS: Implantation of autogenous meniscal fragments wrapped with a fascia sheath into the donor site meniscal defect may significantly enhance fibrocartilage regeneration in vivo in the defect. STUDY DESIGN: Controlled laboratory study. METHODS: Seventy-five mature rabbits were used in this study. In each animal, an anterior one-third of the right medial meniscus was resected. Then, the animals were divided into the following 3 groups of 25 rabbits each: In group 1, no treatment was applied to the meniscal defect. In group 2, the defect was covered with a fascia sheath. In group 3, after the resected meniscus was fragmented into small pieces, the fragments were grafted into the defect. Then, the defect with the meniscal fragments was covered with a fascia sheath. In each group, 5 rabbits were used for histological evaluation at 3, 6, and 12 weeks after surgery, and 5 rabbits were used for biomechanical evaluation at 6 and 12 weeks after surgery. RESULTS: Histologically, large round cells in group 3 were scattered in the core portion of the meniscus-shaped tissue, and the matrix around these cells was positively stained by safranin O and toluisin blue at 12 weeks. The histological score of group 3 was significantly higher than that of group 1 and group 2. Biomechanically, the maximal load and stiffness of group 3 were significantly greater than those of groups 1 and 2. CONCLUSION: This study clearly demonstrated that implantation of autogenous meniscal fragments wrapped with a fascia sheath into the donor site meniscal defect significantly enhanced fibrocartilage regeneration in vivo in the defect at 12 weeks after implantation in the rabbit. CLINICAL RELEVANCE: This study proposed a novel strategy to treat a large defect after a meniscectomy.

Stress deprivation from the patellar tendon induces apoptosis of fibroblasts in vivo with activation of mitogen-activated protein kinases.

The effect of stress deprivation on the tendon tissue has been an important focus in the field of biomechanics. However, less is known about the in vivo effect of stress deprivation on fibroblast apoptosis as of yet. This study was conducted to test a hypothesis that complete stress deprivation of the patellar tendon induces fibroblast apoptosis in vivo with activation of Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38) within 24 h after treatment. A total of 35 mature rabbits were divided into stress-shielded (n=15), sham-operated (n=15), and control (n=5) groups. To completely shield the patellar tendon from stress, we used an established surgical method. Animals were sacrificed at 24 h, and 2, 4, 7, and 14 days after the treatment. Tendon specimens underwent TUNEL assay and immunohistological examinations of active caspase-3, JNK, and p38. Both the number and the ratio of TUNEL-positive and caspase-3-positive cells were significantly greater (p<0.0001) in the stress-shielded group than in the sham group at 24 h, 2, 4, and 7 days. Concerning JNK and p38, both the number and the ratio were significantly greater (p<0.0001) in the stress-shielded group than in the sham group at 24 h, 2, and 4 days. This study demonstrated that complete stress deprivation induces fibroblast apoptosis in vivo with activation of JNK and p38 within 24 h. This fact suggested that the fibroblast apoptosis caused by stress deprivation is induced via the mitogen-activated protein kinase signaling pathway.

Prospective clinical comparisons of anatomic double-bundle versus single-bundle anterior cruciate ligament reconstruction procedures in 328 consecutive patients.

BACKGROUND: Several trials have been conducted to compare the clinical results between anatomic double-bundle and single-bundle anterior cruciate ligament (ACL) reconstruction procedures. In these studies, however, the number of patients was insufficient to compare the clinical results of the 2 procedures. HYPOTHESIS: The anatomic double-bundle procedure may be significantly better concerning the anterior laxity and the pivot-shift test than the single-bundle procedure, while there may be no significant differences in the other clinical evaluations and the intra-operative and postoperative complications between the 2 procedures. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Three hundred and twenty-eight patients with unilateral ACL reconstruction using hamstring autografts were divided into 2 groups. The first 157 consecutive patients underwent single-bundle reconstruction and the remaining 171 patients underwent anatomic double-bundle reconstruction. Concerning all background factors, there were no statistical differences between the 2 groups. Each patient was examined 2 years after surgery. RESULTS: No serious complications were experienced in either group. The anterior laxity was significantly less in the double-bundle reconstruction (mean, 1.2 mm) than in the single-bundle reconstruction (mean, 2.5 mm). In the pivot-shift test, the double bundle (+ indication, 16%; ++, 3%) was significantly better than the single bundle (+ result, 37%; ++, 12%). The mean Lysholm score averaged 96.5 points and 97.3 points in single-bundle and double-bundle reconstructions, respectively, while the International Knee Documentation Committee evaluation showed that 90 and 110 patients, respectively, were evaluated as rank A (no significant difference between groups). There were no significant differences in the other clinical evaluations and the complications between the 2 procedures. CONCLUSIONS: The postoperative anterior and rotational stability after the anatomic double-bundle ACL reconstruction was significantly better than that after the single-bundle reconstruction, although there were no significant differences between the 2 procedures concerning the complications and the clinical evaluations.

An in vivo biomechanical study on the tension-versus-knee flexion angle curves of 2 grafts in anatomic double-bundle anterior cruciate ligament reconstruction: effects of initial tension and internal tibial rotation.

PURPOSE: The purposes of this study were to determine the relation between the graft tension and the knee flexion angle in the anteromedial (AM) and posterolateral (PL) bundles of a clinically simulated anatomic double-bundle anterior cruciate ligament (ACL) reconstruction procedure and to clarify the effect of initial tension on the tension-versus-flexion curve of each graft, as well as the effect of internal rotation of the tibia on the tension of the 2 grafts. METHODS: During ACL reconstruction in 30 patients, 2 suture anchors with a No. 1 polyester suture were firmly screwed into the center of the anatomic attachment of the AM and PL bundles on the femur, respectively, and each graft tension was measured with a strain gauge-type tensiometer attached at the end of the suture under 2 conditions of initial tension. RESULTS: The averaged tension-versus-flexion curves were significantly different between the AM and PL grafts under each initial tension condition (P < .0001). The initial tension applied at 30 degrees of knee flexion significantly affected the absolute values of each graft tension at each knee flexion angle (P < .0001) but did not significantly affect the tension-versus-flexion curve pattern of each graft. The maximal internal rotation of the tibia significantly increased the tension on both the AM and PL grafts at knee flexion angles of less than 60 degrees under each initial tension condition (P < .0001). CONCLUSIONS: The tension-versus-flexion curves of the 2 sutures, which mimicked the AM and PL grafts reconstructed clinically with the anatomic double-bundle ACL reconstruction procedure, were significantly different in the tension values. Differences in initial tension applied to the 2 grafts significantly affected the absolute values of each graft tension at each knee flexion angle but did not significantly affect the tension-versus-flexion curve pattern. The maximal internal rotation of the tibia significantly increased the tension on both the AM and PL suture grafts at knee flexion angles of less than 60 degrees . LEVEL OF EVIDENCE: Level I, testing of previously developed diagnostic criteria in series of consecutive patients with universally applied gold standard.

Biological responses of novel high-toughness double network hydrogels in muscle and the subcutaneous tissues.

The study evaluated biological reaction of four types of novel double network gels in muscle and subcutaneous tissues, using implantation tests according to the international guideline. The implantation tests demonstrated that, although poly (2-acrylamide-2-metyl-propane sulfonic acid)/poly (N,N'-dimetyl acrylamide) (PAMPS/PDMAAm) gel induced a mild inflammation at 1 week, the degree of the inflammation significantly decreased into the same degree as that of the negative control at 4 and 6 weeks. This gel has a potential to be applied as artificial cartilage. In addition, Cellulose/Gelatin gel showed the same degree of inflammation as that of the negative control at 1 week, and then, showed a gradually absorbable property at 4 and 6 weeks. This gel has a potential to be applied as an absorbable implant. The PAMPS/polyacrylamide and Cellulose/PDMAAm gels induced a significant inflammation at each week. These DN gels are difficult to be applied as clinical implants in the current situation.

Biodegradation of high-toughness double network hydrogels as potential materials for artificial cartilage.

This study evaluated biodegradation properties of four novel high-toughness double network (DN) hydrogels as potential materials for artificial cartilage. Concerning each DN gel material, a total of 12 specimens were prepared, and 6 of the 12 specimens were examined to determine the mechanical properties without any treatments. The remaining 6 specimens were implanted into the subcutaneous tissue, using 6 mature female rabbits. At 6 weeks after implantation, the mechanical properties and the water content of the implanted specimens were measured. In the poly(2-acrylamide-2-methyl-propane sulfonic acid)/poly(N,N'-dimethyl acrylamide) DN gel, the ultimate stress and the tangent modulus were significantly increased from 3.10 and 0.20 MPa, respectively, to 5.40 and 0.37 MPa, respectively, with a significant reduction of the water content after implantation (94 to 91%). In the poly(2-acrylamide-2-methyl-propane sulfonic acid)/polyacrylamide DN gel and the cellulose/poly(dimethyl acrylamide) DN gel, the stress (11.4 and 1.90 MPa, respectively) and the modulus (0.30 and 1.70 MPa, respectively) or the water content rarely changed after implantation (90 and 85%, respectively). In the bacterial cellulose/gelatin DN gel, the ultimate stress was dramatically reduced from 4.30 to 1.98 MPa with a significant increase of the water content after implantation (78 to 86%). This study implied that these DN gels except for the cellulose/gelatin DN gel are potential materials that may meet the requirements of artificial cartilage.

Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction procedure using hamstring tendon grafts: comparisons among 3 different procedures.

PURPOSE: To compare the clinical outcome of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with that of nonanatomic single- and double-bundle reconstructions. TYPE OF STUDY: Prospective comparative cohort study. METHODS: Seventy-two patients with unilateral ACL-deficient knees were randomly divided into 3 groups. Concerning all background factors, there were no statistical differences among the 3 groups. In group S (n = 24), single-bundle ACL reconstruction was performed. In group N-AD (n = 24), nonanatomic double-bundle reconstruction was carried out. In group AD (n = 24), anatomic double-bundle reconstruction was performed. One surgeon performed all operations using hamstring tendon autografts. Each patient underwent clinical examinations, before surgery and at 2 years. RESULTS: No intraoperative and postoperative complications were experienced in each group. There were no significant differences concerning the time for operation among the 3 groups. The statistical analysis showed a significant difference in the postoperative side-to-side anterior laxity among the 3 groups (P = .006). The laxity was significantly less (P = .002) in group AD (1.1 mm) than in group S (2.8 mm), while there was no significant difference (P = .072) between groups AD and N-AD. Concerning the pivot-shift test, group AD was significantly superior to group S (P = .025). There were no significant differences in the range of knee motion, the muscle torque, and the International Knee Documentation Committee evaluation. CONCLUSIONS: On the basis of the KT-2000 measurement, the side-to-side anterior laxity of our anatomic double-bundle ACL reconstruction was significantly better than that of the single-bundle reconstruction with the hamstring tendon graft, although there were no significant differences in the other clinical measures among any of the 3 procedures. LEVEL OF EVIDENCE: Level II.

Primary stability of three posterior cruciate ligament reconstruction procedures: a biomechanical in vitro study.

PURPOSE: Posterior cruciate ligament (PCL) reconstruction procedures have not been thoroughly evaluated under cyclic loading conditions. We tested the hypothesis that PCL reconstruction with a quadrupled flexor-tendon graft and fixation using tapes and staples is biomechanically superior to that fixed with sutures, a button, and a post-screw, and is comparable to reconstruction with a bone--patellar tendon--bone (BPTB) graft. STUDY DESIGN: In vitro biomechanical study. METHODS: A total of 45 porcine knees were used. The quadrupled flexor-tendon graft was fixed using the suture/button/post-screw procedure in 15 knees, and with the tape/staples procedure in another 15 knees. The remaining 15 knees underwent reconstruction with a BPTB graft secured with screws as the standard control. In each group of 15 knees, 5 underwent tensile testing without cyclic loading, and 10 underwent the same tensile test after 5,000 cycles of load-controlled or displacement-controlled loading. RESULTS: Each type of cyclic loading produced larger biomechanical changes in the knees fixed with the suture/button/post-screw procedure than in the knees secured using the other 2 procedures. CONCLUSIONS: In PCL reconstruction, the tape/staples procedure is biomechanically superior to the suture/button/post-screw procedure, and is comparable to the BPTB/screws procedure with regard to the ultimate failure load. Neither of the procedures using the quadrupled flexor-tendon graft was comparable to the BPTB graft in linear stiffness and the initial displacement after load-controlled cyclic testing. CLINICAL RELEVANCE: The biomechanical behaviors of PCL-reconstructed knees are significantly different, depending on surgical techniques.

Effects of separate application of three growth factors (TGF-beta1, EGF, and PDGF-BB) on mechanical properties of the in situ frozen-thawed anterior cruciate ligament.

OBJECTIVE: To clarify effects of a separate application of TGF-beta1, EGF, and PDGF-BB on the material properties of the in situ frozen-thawed anterior cruciate ligament. DESIGN: Twenty-eight rabbits were divided into four groups after undergoing the in situ freeze-thaw treatment in the right anterior cruciate ligament. In 3 of the 4 groups, 4 ng TGF-beta1, 20 ng EGF, and 4 microg PDGF-BB was applied to the frozen anterior cruciate ligament, respectively. In the remaining sham treatment group, only fibrin sealant as a vehicle was applied. Each animal was sacrificed at 12 weeks after surgery. BACKGROUND: If the role of growth factors in ligament healing and remodeling is understood, better therapies can be designed for ligament trauma. METHODS: The freeze-thaw treatment was performed three times using the originally developed cryo-probe. The cross-sectional area of the anterior cruciate ligament was measured by the optical non-contact method. After preconditioning, each specimen was stretched to failure. The ligament strain was determined with a video dimension analyzer. RESULTS: The tensile strength and the tangent modulus of the anterior cruciate ligament in the TGF-beta1 group was significantly higher than in the sham group, but significantly lower than in the normal control group. There were no significant differences in the strength and the modulus between the EGF group, the PDGF-BB group, and the sham group. CONCLUSIONS: In this model, an application of 4 ng TGF-beta1 significantly inhibited some of the material deterioration that occurs in the in situ frozen-thawed anterior cruciate ligament, while an application of 20 ng EGF or 4 microg PDGF-BB did not significantly affect the deterioration. RELEVANCE: This information will be useful in the future to develop a new biological therapy for ligament reconstruction to prevent the graft deterioration after transplantation.

Biomechanical properties of high-toughness double network hydrogels.

This study evaluated the wear property of four novel double-network (DN) hydrogels, which was composed of two kinds of hydrophilic polymers, using pin-on-flat wear testing. The gels involve PAMPS-PAAm gel which consists of poly(2-acrylamide-2-metyl-propane sulfonic acid) and polyacrylamide, PAMPS-PDAAAm gel which consists of poly(2-acrylamide-2-metyl-propane sulfonic acid) and poly(N,N'-dimetyl acrylamide), Cellulose/PDMAAm gel which consists of bacterial Cellulose and poly dimetyl-acrylamide, and Cellulose-Gelatin gel which consists of bacterial Cellulose and Gelatin. Ultra-high molecular weight polyethylene (UHMWPE) was used as a control of a clinically available material. Using a reciprocating apparatus, 10(6) cycles of friction between a flat specimen and ceramic pin were repeated in water under a contact pressure of 0.1 MPa. To determine the depth and the roughness of the concave lesion created by wear, a confocal laser microscope was used. As a result, the maximum wear depth of the PAMPS-PDMAAm gel (3.20 microm) was minimal in the five materials, while there was no significant difference compared to UHMWPE. There were significant differences between UHMWPE and one of the other three gels. The PAMPS-PAAm gel (9.50 microm), the Cellulose-PDMAAm gel (7.80 microm), and the Cellulose-Gelatin gel (1302.40 microm). This study demonstrated that the PAMPS-PDMAAm DN gel has an amazing wear property as a hydrogel that is comparable to the UHMWPE. In addition, the PAMPS-PAAm and Cellulose-PDMAAm DN gels are also resistant to wear to greater degrees than conventionally reported hydrogels. On the other hand, this study showed that the Cellulose-Gelatin DN gel was not resistant to wear.

Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts.

PURPOSE: To develop and evaluate an anatomic reconstruction procedure of the posterolateral and anteromedial bundles of the anterior cruciate ligament (ACL). TYPE OF STUDY: Anatomic study and case series. METHODS: The femoral attachment of the anteromedial and posterolateral bundles of the ACL was anatomically analyzed with 5 cadaveric knees. Using another 3 cadaveric knees, anatomic reconstruction of the posterolateral and anteromedial bundles was performed with the transtibial technique, and tunnel positioning and graft function in a range of knee motion was observed. Based on this anatomic study, an anatomic reconstruction procedure of the anteromedial and posterolateral bundles was developed using hamstring tendon autografts. This procedure was carried out in 57 consecutive patients with an ACL-deficient knee. The patients were followed-up for a minimum of 24 months. RESULTS: We developed the arthroscopically assisted anatomic reconstruction procedure of the posterolateral and anteromedial bundles, involving a new method of creating the tibial and femoral tunnels for the posterolateral bundle. To visualize the femoral attachment of the posterolateral bundle, the medial infrapatellar portal was more useful than the lateral portal. In clinical results, the side-to-side difference of anterior laxity averaged 1.0 mm with a standard deviation of 0.9. CONCLUSIONS: The anatomic reconstruction of the anteromedial and posterolateral bundles using hamstring tendon autografts is clinically practical in the treatment for the ACL-deficient knee. LEVEL OF EVIDENCE: Level IV.

Rehabilitation after hamstring anterior cruciate ligament reconstruction.

A prospective comparative study was conducted involving 62 patients to determine the effects and limits of accelerated rehabilitation on clinical outcome. The study focused on whether aggressive rehabilitation after anterior cruciate ligament reconstruction with the doubled semitendinosus and gracilis tendon autograft results in stretching the graft. Thirty patients had postoperative rehabilitation according to the current conservative protocol, and 32 patients had rehabilitation using an accelerated regime. Each patient was evaluated subjectively and objectively 36 months or more after surgery. Concerning the side-to-side difference in the anterior laxity, 87% of the patients in the conservative rehabilitation group had 3 mm or less and 80% of the patients in the accelerated rehabilitation group had the same acceptable laxity. There was no significant difference between the two groups. Muscle torque was restored significantly earlier in the patients in the accelerated rehabilitation group than in the patients in the conservative rehabilitation group. Nine months after surgery, however, there were no significant differences in the torque between the two groups. Accelerated rehabilitation significantly increased the incidence of knee effusion during rehabilitation. This study showed that acceleration of postoperative rehabilitation could rapidly restore muscle strength without significantly compromising graft stability in anterior cruciate ligament reconstruction with the doubled hamstring tendon autograft. However, this study also showed that acceleration significantly increases the incidence of synovitis. Acceleration of postoperative rehabilitation has advantages and disadvantages for clinical outcome after anterior cruciate ligament reconstruction.