Vibration acceleration enhances proliferation, migration, and maturation of C2C12 cells and promotes regeneration of muscle injury in male rats.

Vibration acceleration (VA) using a whole-body vibration device is beneficial for skeletal muscles. However, its effect at the cellular level remains unclear. We aimed to investigate the effects of VA on muscles in vitro and in vivo using the C2C12 mouse myoblast cell line and cardiotoxin-induced injury in male rat soleus muscles. Cell proliferation was evaluated using the WST/CCK-8 assay and proportion of Ki-67 positive cells. Cell migration was assessed using wound-healing assay. Cell differentiation was examined by the maturation index in immunostained cultured myotubes and real-time polymerase chain reaction. Regeneration of soleus muscle in rats was assessed by recruitment of satellite cells, cross-sectional area of regenerated muscle fibers, number of centrally nucleated fibers, and conversion of regenerated muscle from fast- to slow-twitch. VA at 30 Hz with low amplitude for 10 min promoted C2C12 cell proliferation, migration, and myotube maturation, without promoting expression of genes related to differentiation. VA significantly increased Pax7-stained satellite cells and centrally nucleated fibers in injured soleus muscles on Day 7 and promoted conversion of fast- to slow-twitch muscle fibers with an increase in the mean cross-sectional area of regenerated muscle fibers on Day 14. VA enhanced the proliferation, migration, and maturation of C2C12 myoblasts and regeneration of injured rat muscles.

Deep Infection After Anterior Cruciate Ligament Reconstruction Diagnosed by Intratunnel Suspensory Fixation Device Migration: A Case Report.

CASE: A 43-year-old woman sustained an anterior cruciate ligament injury while kickboxing and underwent anterior cruciate ligament reconstruction with hamstring autograft with suspensory fixation. Lateral thigh wound was superficially infected at 2 weeks postoperatively with resolution of signs and symptoms after debridement. Three months later, posterolateral knee pain developed and radiographs revealed intratunnel migration of the device. That observation with abnormal magnetic resonance imaging and serology results led to the diagnosis of deep infection. Immediate device removal and debridement were performed. Consequently, the grafts were preserved, and the patient could perform kickboxing 2 years thereafter. CONCLUSIONS: Intratunnel migration of suspensory fixation devices can support a diagnosis of infection.

Ultrasonic Technique for Femoral Tunnel Creation in Anterior Cruciate Ligament Reconstruction.

Bone tunnel creation in the anatomical location is essential in anterior cruciate ligament (ACL) reconstruction with an autogenous graft and is commonly performed with a drill bit matched to graft diameter. Anatomic rectangular tunnel ACL reconstruction with a bone-patellar tendon-bone autograft has been developed to anatomically create bone tunnels inside the ACL footprints and has been reported to achieve excellent outcomes. To make the rectangular tunnel, the surgeon needs to dilate 2 adjacent bone tunnels after creation of 2 round tunnels with a drill bit, while the tunnel wall occasionally cracks during dilating. An ultrasonic (US) device was developed with improvement of output power and has been implemented with a rectangular shape blade in the field of arthroscopic surgery. This US device can provide a precise and effective bone cut compared to drills. We introduced this device to clinically create a rectangular tunnel during ACL reconstruction. The US device can be useful for rectangular femoral tunnel creation and can create a precise rectangular femoral tunnel in the ACL footprint.

Knot location in arthroscopic inside-out meniscal repair: Cadaveric evaluation.

BACKGROUND: The inside-out repair technique is the gold standard for treatment of meniscal tears, while some soft tissues can be hung as the sutures are tied outside the capsule. The purpose was to clarify the association between the suture site and knot location in the arthroscopic inside-out technique. METHODS: Inside-out meniscal suture was arthroscopically performed on medial and lateral menisci in twenty-three cadaveric knees, on the assumption that longitudinal tear existed. A retractor was inserted above the semi-membranous tendon and anterior to the gastrocnemius for the medial side, while the retractor was placed in the anterior space of the gastrocnemius for the lateral side. After identifying three segments (anterior, middle and posterior segments), eight sutures were inserted into the following eight areas in each knee: anterior (M1, L1) and posterior (M2, L2) areas of the middle segment, and anterior (M3, L3) and posterior (M4, L4) areas of the posterior segment. Twelve knees underwent meniscal repair on femoral side and eleven passed sutures on the tibial side, while knots were tied outside of the joint. Attentive dissection was performed to assess the relation between knot locations and the principal structures around the knee joint. RESULTS: In medial meniscal suture, most sutures for the middle portion (M1, 2) bound medial collateral ligament (MCL), while a few cases included the semi-membranous tendon for the M4 area. In lateral meniscal suture, sutures for the L1 area tied some fibers of lateral collateral ligament (LCL) in high frequency, while popliteal muscles/tendons were tied over at the L3 area. CONCLUSIONS: Most suture knots were located on MCL or capsule in medial meniscus suture, while more than half sutures passed through LCL or popliteal tendon/muscle in lateral meniscus suture. An assistant should retract LCL under direct observation and the surgeon must confirm the direction of needle for lateral meniscal repair.

Measurement of various intensities of physical activities and categorization of "Locomotive" and "Household" activities provide a subject-specific detailed assessment.

This study aimed to compare the physical activity (PA) measured by a wearable sensor device (WSD) and the step count measurement, and to investigate the association between PAs and lifestyle. Data of 301 participants were collected from March 2019 to March 2021. Step counts, sedentary behavior, performance time of light/moderate/vigorous PA, METs × hour of "Locomotive" and "Household" categorized activities, and energy expenditure (EE) were measured by the WSD, respectively. Furthermore, the participants were classified into student, standing worker, and sitting worker groups. Data were analyzed using the Steel-Dwass and Pearson correlation coefficient tests. The correlation between the performance time of each PA and step count was weak, except for moderate PA. "Household" EE and step count also had a weak correlation. In the comparison of lifestyle, there was a significant difference in the mean performance time of each type of PA between the groups. Additionally, the standing worker and sitting worker groups had a significant difference in METs × hour of "Household" activities, indicating that the difference between the occupations is reflected in "Household" activities. The WSD measurement can be used to evaluate detailed individual PA, whereas the step count measurement showed weakness in the PA estimation.

Chronic musculoskeletal pain, catastrophizing, and physical function in adult women were improved after 3-month aerobic-resistance circuit training.

Although exercise is beneficial for chronic musculoskeletal pain (CMP), the optimal type and amount of exercise are unclear. This study aimed to determine the impact of circuit training that combines aerobic and resistance exercises on adult women with CMP. A total of 139 women with CMP underwent circuit training for 3 months and were asked to complete the following questionnaires at baseline and 3 months later: Numeric Rating Scale (NRS), Pain Catastrophizing Scale (PCS), Roland-Morris Disability Questionnaire (RDQ), Shoulder36, and Knee injury and Osteoarthritis Outcome Score (KOOS). Significant improvements were observed in NRS, PCS, RDQ, and KOOS activities of daily living (ADL) scores after the intervention relative to baseline (p < 0.0001, p = 0.0013, 0.0004, and 0.0295, respectively), whereas shoulder function did not improve. When considering the impact of exercise frequency, NRS scores improved regardless of exercise frequency. Furthermore, PCS, RDQ, and KOOS scores improved in participants who exercised at least twice a week (24 sessions over the course of 3 months). In conclusion, CMP, pain catastrophizing, and physical function in adult female fitness club participants with CMP of NRS 4 or higher improved after 3 months of aerobic-resistance circuit training.

Integrin α2ß1 plays an important role in the interaction between human articular cartilage-derived chondrocytes and atelocollagen gel.

Although atelocollagen gel is used as a scaffold for culturing human articular cartilage-derived chondrocytes, little is known about cell-gel interactions. In this study, we investigated the mechanism via which atelocollagen gel affects human articular cartilage-derived chondrocytes. Two types of three-dimensional cultures of human articular cartilage-derived chondrocytes (i.e., with and without atelocollagen gel) were compared. While the amount of atelocollagen gel in culture gradually decreased with time, it promoted the expression of matrix metalloproteinases (MMPs) during the early stages of culture. Genome-wide differential gene expression analysis revealed that cell membrane- and extracellular matrix-related genes were highly ranked among up- and down-regulated groups in cells cultured in the presence of atelocollagen gel. Among the integrin family of genes, the expression of integrin subunit alpha 2 and integrin subunit alpha 10 was significantly increased in the presence of atelocollagen gel. Blocking α2ß1 integrin with the specific inhibitor BTT 3033 had a significant effect on cell proliferation, MMP expression, and cell shape, as well as on the response to mechanical stimulation. Taken together, our findings indicate that the α2ß1 integrin pathway plays an important role in the interaction of atelocollagen gel with human articular cartilage-derived chondrocytes and may be a potential therapeutic target for articular cartilage disorders.

Vibration acceleration promotes endochondral formation during fracture healing through cellular chondrogenic differentiation.

Vibration acceleration through whole body vibration has been reported to promote fracture healing. However, the mechanism responsible for this effect remains unclear. Purpose of this study was to determine whether vibration acceleration directly affects cells around the fracture site and promotes endochondral ossification. Four-week-old female Wistar Hannover rats were divided into two groups (vibration [V group] and control [C group]). The eighth ribs on both sides were cut vertically using scissors. From postoperative day 3 to 11, vibration acceleration using Power Plate® (30 Hz, low amplitude [30-Low], 10 min/day) was applied in the V group. Mature calluses appeared earlier in the V group than in the C group by histological analysis. The GAG content in the fracture callus on day 6 was significantly higher in the V group than in the C group. The mRNA expressions of SOX-9, aggrecan, and Col-II in the fracture callus on day 6 and Col-X on day 9 were significantly higher in the V group than in the C group. For in vitro analysis, four different conditions of vibration acceleration (30 or 50 Hz with low or high amplitude [30-Low, 30-High, 50-Low, and 50-High], 10 min/day) were applied to a prechondrogenic cell (ATDC5) and an undifferentiated cell (C3H10T1/2). There was no significant difference in cell proliferation between the control and any of the four vibration conditions for both cell lines. For both cell lines, alcian blue staining was greater under 30-Low and 50-Low conditions than under control as well as 30-High and 50-High conditions on days 7 and 14. Vibration acceleration under 30-L condition upregulated chondrogenic gene expressions of SOX-9, aggrecan, Col-II, and Col-X. Low-amplitude vibration acceleration can promote endochondral ossification in the fracture healing in vivo and chondrogenic differentiation in vitro.

Computed Tomography Features of Glenoid Osteophytes in Traumatic Anterior Shoulder Instability: Comparison Between Younger and Older Patients.

BACKGROUND: Osteoarthritis that develops after traumatic anterior shoulder instability is known as dislocation arthropathy, but its frequency and characteristics are still unclear. PURPOSE: To evaluate glenoid osteophytes in shoulders with traumatic anterior instability by using computed tomography (CT) and to elucidate the influence of instability on the progression of dislocation arthropathy in different age groups. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This study involved 214 unoperated patients with unilateral instability who underwent CT of both shoulders. The patients were divided into 2 groups according to age at the time of CT: ≤30 years (younger group; n = 172) and ≥31 years (older group; n = 42). Patient demographics as well as the presence, size, and location of glenoid osteophytes were compared between the 2 groups and also between patients with and without osteophytes. Furthermore, patients with osteophytes in the older group were divided into 2 subgroups according to age at the time of the initial injury: as a teenager (early-onset subgroup; n = 9) or at ≥31 years (late-onset subgroup; n = 14), and the same assessments were conducted. RESULTS: Osteophytes were significantly more frequent on the affected side of the older group compared with the younger group (71.4% vs 13.9%, respectively; P < .001). In the younger group, patients with osteophytes had more multiple-instability events (P = .002) and a longer interval from injury to CT (P < .001) than those without osteophytes. Although there was no difference in osteophyte size between the 2 groups, most osteophytes were located at the anteroinferior part of the glenoid in the younger group, while osteophytes were usually circumferential around the glenoid in the older group. A comparison between the early- and late-onset subgroups in older patients with osteophytes revealed that the osteophytes were more frequently located at the anteroinferior glenoid region in the early-onset subgroup. CONCLUSION: CT allowed a detailed evaluation of glenoid osteophytes, revealing that osteophytes were not uncommon in younger patients. Instability itself might influence the progression of osteoarthritic changes in younger patients, while aging seems to have a greater effect in older patients.

Risk Factors for the Postoperative Recurrence of Instability After Arthroscopic Bankart Repair in Athletes.

BACKGROUND: Several risk factors for the postoperative recurrence of instability after arthroscopic Bankart repair have been reported, but there have been few detailed investigations of the specific risk factors in relation to the type of sport. PURPOSE: This study investigated the postoperative recurrence of instability after arthroscopic Bankart repair without additional reinforcement procedures in competitive athletes, including athletes with a large glenoid defect. The purpose of this study was to investigate risk factors related to the postoperative recurrence of instability in athletes. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 115 athletes (123 shoulders) were classified into 5 groups according to type of sport: rugby (41 shoulders), American football (32 shoulders), other collision sports (18 shoulders), contact sports (15 shoulders), and overhead sports (17 shoulders). First, the recurrence rate in each sporting category was investigated, with 113 shoulders followed up for a minimum of 2 years. Then, factors related to postoperative recurrence were investigated in relation to the type of sport. RESULTS: Postoperative recurrence of instability was noted in 23 of 113 shoulders (20.4%). The recurrence rate was 33.3% in rugby, 17.2% in American football, 11.1% in other collision sports, 14.3% in contact sports, and 12.5% in overhead sports. The most frequent cause of recurrence was tackling, and recurrence occurred with tackling in 12 of 16 athletes playing rugby or American football. Reoperation was completed in 11 shoulders. By univariate analysis, significant risk factors for postoperative recurrence of instability included playing rugby, age between 10 and 19 years at surgery, preoperative glenoid defect, small bone fragment of bony Bankart lesion, and capsular tear. However, by multivariate analysis, the most significant factor was not the type of sport but younger age at operation and a preoperative glenoid defect with small or no bone fragment. Compared with the other sports, there was a significantly greater recurrence rate among rugby players without the aforementioned significant risk factors (small glenoid defect, ≤10%; medium or large bone fragment, >5%; and no capsular tear). CONCLUSION: Younger age at operation and preoperative glenoid defect with small or no bone fragment significantly influenced recurrent instability among competitive athletes.