The relationship between diffusion tensor imaging and the clinical classification of cubital tunnel syndrome.

The purpose of the study was to investigate the relationship between diffusion tensor imaging (DTI) and the clinical classification of cubital tunnel syndrome (CuTS). Ten patients with CuTS (7 men and 3 women; mean age: 52.7 years) and 5 patients without ulnar neuropathy (2 men and 3 women; mean age: 38.0 years) were enrolled in this retrospective study. Fifteen patients were clinically classified into three groups: "Normal", "1 and 2A", and "2B and 3" by an orthopedic surgeon using the modified McGowan stages. DTI was acquired using a 3.0-T MRI. Fractional anisotropy (FA) of the ulnar nerve was measured in slices covering 20 mm proximal to 20 mm distal to ulnar sulcus. Median FA values in each group were compared by Kruskal-Wallis and Steel-Dwass test (P < 0.05). Five patients with CuTS were classified as "1 and 2A" and five patients as "2B and 3". The FA values, proximal 12 mm to the ulnar sulcus were 0.486 ± 0.117, 0.425 ± 0.166 and 0.298 ± 0.0386 in the "Normal", "1 and 2A" and "2B and 3" groups, respectively. The FA values of patients classified as "Normal" were significantly higher than those classified as "2B and 3" (P = 0.0326 in Steel-Dwass test). FA proximal to the ulnar sulcus might be associated to the modified McGowan stages for the clinical classification of CuTS.

The use of ultrasonography as an effective screening tool for chronic posterior cruciate ligament injuries.

PURPOSE: We aimed to explore the applicability and validity of ultrasonography for diagnosing chronic posterior cruciate ligament (PCL) injuries. METHODS: PCL thickness was measured at 2 cm proximal to the tibia insertion site. Using the same ultrasonography image, the angle tangent to the PCL from the tibia insertion site was also measured. These data were analyzed by plotting the receiver operating curve (ROC), and the sensitivity and specificity were calculated according to the optimal cut-off point. Ultrasonography data from the PCLinjured knee were compared with those from the contralateral uninjured knee of the same patient. RESULTS: Twelve men and six women, with a mean age of 28.8 ± 14.0 years, were included in this study. The mean time from injury to medical examination was 10.0 ± 6.7 months. The mean thickness of the PCL was 8.1 ± 1.9 mm on the affected side and 5.8 ± 1.2 mm on the uninjured side, with the affected side being significantly thicker. ROC analysis revealed that the optimal cut-off value for the thickness of chronic PCL injuries was 6.5 mm (sensitivity 83.3%, specificity 77.8%, area under the curve [AUC] = 0.87). The optimal cut-off value for the angle was 20° (sensitivity 88.9%, specificity 94.4%, AUC = 0.96). CONCLUSION: Ultrasonography is useful as a screening tool for chronic PCL injuries. The optimal cut-off point was 6.5 mm for thickness and 20° for angle. LEVEL OF EVIDENCE: IV.

Speed whip ripstop technique during anterior cruciate ligament reconstruction using quadriceps tendon results in higher fixation strength.

PURPOSE: To compare the biomechanical strength of different fixation configurations using a suspensory button in a soft-tissue quadriceps tendon graft for Anterior Cruciate Ligament (ACL) reconstruction. METHODS: Thirty fresh-frozen bovine Achilles tendons (10 mm wide, 50 mm long, and 4 mm thick) were used in this study. Tendons were assigned to three groups (n = 10 per group) with different suture configurations using adjustable loops with a suspensory button: group A, with the threads of an adjustable loop fixed by crossing at the tip of the loop and the entire loop; group B, continuous loops with hanging buttons were directly sutured to the tendon with eight simple sutures; group C, fixation was performed using the speed whip ripstop technique. Tensile tests with five cycles of preloading were performed at 50 N, held at 50 N for 1 min, and load-to-failure testing was conducted until rupture at 5 mm/min. The difference in the elongation and the maximum load-to-failure force were measured. RESULTS: The average elongation was significantly larger in group B (16.6 ± 2.2 mm) than in groups A (10.3 ± 2.4 mm) and C (10.0 ± 1.0 mm), (p < 0.001). The average load-to-failure force varied significantly between the three groups, 157.5 ± 33.4 N in group A, 253.4 ± 45.5 N in group B, and 337.7 ± 21.0 N in group C, (p < 0.001). CONCLUSION: Fixation using the speed whip ripstop technique to fix the suspensory button and soft-tissue transplant tendon resulted in minimal elongation and higher fixation strength. Simple devices that use this method have already been developed. Since it can be fixed using a relatively simple method, speed whip ripstop technique was shown to be advantageous for femoral fixation in ACL reconstruction using soft-tissue quadriceps tendon. The findings of this study could help surgeons reduce graft re-tear rates in ACL reconstruction using quadriceps tendons. LEVEL OF EVIDENCE: N/A, laboratory control study.

Growth-related changes in the ultrastructure of the quadriceps tendon.

BACKGROUND: The purpose of this study was to investigate the effect of growth on the ultrastructural characteristics of the quadriceps tendon (QT). METHODS: Eighteen included patients were classified into three groups based on age and epiphyseal plate condition: the 'immature group' consisted of patients with open epiphyseal plates (11.5 ± 1.6 years old; mean ± standard deviation), the 'young group' consisted of patients aged <20 years with closed epiphyseal plates (15.8 ± 1.0 years), and the 'adult group' consisted of all patients aged >20 years (29.8 ± 11.3 years) irrespective of epiphyseal plate condition. Tendon tissue samples were used for ultrastructural analysis by transmission electron microscopy. Minimum collagen fibril diameters were measured from the cross sections of collagen fibril images using Image J software. The average number of collagen fibers per sample was 797 ± 109, and the average collagen fibril diameter of each sample was compared using one-way analysis of variance. RESULTS: The mean collagen fibril diameter was 89.7 ± 14.4 nm in the immature group, 94.8 ± 16.4 nm in the young group, and 107.2 ± 12.1 nm in the adult group, with significant differences between the immature and adult groups, and between the young and adult groups (P = 0.001 and P = 0.021, respectively); however, no significant differences were observed between the immature and young adult groups (P = 0.49). CONCLUSIONS: The collagen fibril diameter of the QT was found to have increased with growth. The study provided insights into graft selection.

Particle bombardment-assisted peptide-mediated gene transfer for highly efficient transient assay.

OBJECTIVE: A centrifugation-assisted peptide-mediated gene transfer (CAPT) method was recently developed as an efficient system for gene delivery into plant cells. However, the gene transfer efficiency of CAPT into plant cells was not entirely satisfactory for detecting transient expression of a transgene driven into mitochondria. Here, we report a new gene delivery system using a method called particle bombardment-assisted peptide-mediated gene transfer (PBPT). RESULTS: We investigated various parameters of the PBPT method to increase transient gene expression efficiency in Brassica campestris. The optimal conditions for PBPT were a single bombardment with gold particles coated with a DNA‒peptide complex (6 µg of DNA and 2 µg of peptide) at an acceleration pressure of 5 kg/cm2 and a target distance of 12.5 cm. Moreover, bombardment under the optimal conditions successfully transferred the transgene into the cells of other plant species, namely B. juncea and tomato. Thus, we developed a PBPT method for highly efficient delivery of a DNA‒peptide complex into plant mitochondria.

Relationship of early postoperative perceived leg length discrepancy to the progression of osteoarthritis in the contralateral hip after unilateral total hip arthroplasty-a retrospective cohort study using propensity score matching.

[Purpose] This study aimed to identify the relationship between the early postoperative perceived leg length discrepancy after unilateral total hip arthroplasty and the progression of osteoarthritis in the contralateral hip. [Participants and Methods] This was a retrospective cohort study of 65 patients who underwent primary unilateral total hip arthroplasty for bilateral hip osteoarthritis. The minimum joint space width of the contralateral hip was measured preoperatively. The change in minimum joint space width one year postoperatively compared with preoperatively was measured. At three weeks postoperatively, patients were divided into the perceived and non-perceived leg length discrepancy groups using the block test. Patients with a perceived leg length discrepancy of 2 mm or more and less than 2 mm were grouped into the perceived and non-perceived leg length discrepancy groups, respectively. Before and after propensity score matching, the change in minimum joint space width between the two groups from the preoperative period to one year postoperatively was compared. [Results] In the pre-propensity matching sample, there was no significant difference in the change in minimum joint space width between the two groups. In the post-propensity matching sample, the change in minimum joint space width in the perceived leg length discrepancy group was significantly larger than that in the non-perceived leg length discrepancy group. [Conclusion] The early postoperative perceived leg length discrepancy after unilateral total hip arthroplasty may affect the progression of osteoarthritis in the contralateral hip.

Statistical injury prediction for professional sumo wrestlers: Modeling and perspectives.

In sumo wrestling, a traditional sport in Japan, many wrestlers suffer from injuries through bouts. In 2019, an average of 5.2 out of 42 wrestlers in the top division of professional sumo wrestling were absent in each grand sumo tournament due to injury. As the number of injury occurrences increases, professional sumo wrestling becomes less interesting for sumo fans, requiring systems to prevent future occurrences. Statistical injury prediction is a useful way to communicate the risk of injuries for wrestlers and their coaches. However, the existing statistical methods of injury prediction are not always accurate because they do not consider the long-term effects of injuries. Here, we propose a statistical model of injury occurrences for sumo wrestlers. The proposed model provides the estimated probability of the next potential injury occurrence for a wrestler. In addition, it can support making a risk-based injury prevention scenario for wrestlers. While a previous study modeled injury occurrences by using the Poisson process, we model it by using the Hawkes process to consider the long-term effect of injuries. The proposed model can also be applied to injury prediction for athletes of other sports.

High initial graft tension is a post-operative risk factor for high UTE T2* value of the graft 6 months after anterior cruciate ligament reconstruction.

BACKGROUND: To evaluate the risk factor of "ligamentization" using the ultrashort echo time (UTE)-T2* imaging. METHODS: Fifty-nine patients (23 males and 36 females, age of 21.9 ± 10.6 years old) who underwent anterior cruciate ligament (ACL) reconstruction with hamstring tendon were evaluated. The UTE T2* values of the reconstructed ACL at 6 months postoperatively were calculated. Circular regions of interest (5-10 mm2) were set at the proximal, mid-substance, and distal regions of the reconstructed ACL. The UTE T2* values of the entire reconstructed ACL were calculated as the average of these three points. Patients were divided into high (27 knees) and low (32 knees) UTE T2* groups by calculating whether their UTE T2* values were greater than the median of the UTE T2* values of all patients. Risk factors for high UTE T2* values were evaluated. Clinical outcomes were compared between the two groups. RESULTS: There were no significant differences in any measured parameters and clinical outcomes between the two UTE T2* groups. Logistic regression analysis revealed that graft tension was a significant risk factor for patients with high UTE-T2* values (P = 0.047, odds ratio [OR] = 2.285). The UTE-T2* values of the 20 N graft tension using the Tension loc system were significantly lower than those of the 40 N using double-spike plate (DSP) with screws at each site and the 30 N using the Tension loc system at the distal site. CONCLUSIONS: Higher graft tension was an independent risk factor for high UTE T2* values of the reconstructed ACL.

Regeneration Using Adipose-Derived Stem Cell Sheets in a Rabbit Meniscal Defect Model Improves Tensile Strength and Load Distribution Function of the Meniscus at 12 Weeks.

PURPOSE: The purpose of this study was to evaluate the mechanical properties, such as the tensile strength and load distribution function, of the meniscus tissue regenerated using adipose-derived stem cell (ADSC) sheets in a rabbit meniscal defect model. METHODS: ADSC sheets were prepared from adipose tissue of rabbits. The anterior half of the medial meniscus was removed from both knees. One knee was transplanted with an ADSC sheet; the contralateral knee was closed without transplantation. Mechanical tests were performed at 4 and 12 weeks posttransplantation. In the tensile test, tensile force was applied to the entire medial meniscus, including the normal area (n = 10/group). Compression tests were performed on the entire knee, with soft tissues other than the ligament removed. A pressure-sensitive film was inserted under the medial meniscus and a 40-N load was applied (n = 5/group). RESULTS: In the tensile test, the elastic modulus in ADSC-treated knees was higher at 12 weeks (ADSC: 70.30 ± 18.50 MPa, control: 43.71 ± 7.11 MPa, P = .009). The ultimate tensile strength (UTS) in ADSC-treated knees at 12 weeks was also higher (ADSC: 22.69 ± 5.87 N, control: 15.45 ± 4.08 N, P = .038). In the compression test, the contact area was larger in the ADSC group at 4 weeks (ADSC: 31.60 ± 8.17 mm2, control: 20.33 ± 2.86 mm2, P = .024) and 12 weeks (ADSC: 41.07 ± 6.09 mm2, control: 30.53 ± 5.47 mm2, P = .04). Peak pressure was significantly lower in ADSC-treated knees at 12 weeks (ADSC: 11.91 ± 1.03 MPa, control: 15.53 ± 2.3 MPa, P = .002). CONCLUSIONS: The regenerated meniscus tissue, 12 weeks after transplantation of the ADSC sheets into the meniscal defect area, had high elastic modulus and UTS. In the meniscus-tibia compartment, the contact area was large and the peak pressure was low. CLINICAL RELEVANCE: ADSC sheets promoted regeneration of meniscus. ADSC sheet transplantation for meniscal defects could be an effective regenerative therapy.

Relationship between anatomical injury site of rectus femoris muscle strain and time taken to return to play in Japanese professional soccer players.

PURPOSE: The rectus femoris has three myotendinous or myoaponeurosis junctions and causes three types of muscle strain anatomically. We aimed to investigate the anatomical injury site of the rectus femoris muscle strain in professional soccer players as well as the characteristic findings on magnetic resonance imaging (MRI) and to evaluate its relationship with the time taken to return to play at competition levels. METHODS: Thirteen Japanese professional soccer players who sustained injuries to the rectus femoris were included in this study. The mechanism of injury, anatomical injury site, severity, absence of hematomas, and time taken to return to competition were evaluated. RESULTS: Ten patients were injured while kicking and three while sprinting. The anatomical injury site was the origin aponeurosis in two cases, intramuscular tendon in eight cases, and distal aponeurosis in three cases. The severity was one-degree in three cases and two-degree in 10 cases. Hematomas were observed in five cases. Cases with injuries caused by sprinting, two-degree injuries, or clear hematomas were associated with significantly longer periods of return to play than the other cases. Additionally, patients with distal aponeurosis-type injuries tended to take a long time to return to the competition. CONCLUSIONS: In rectus femoris muscle strain, it is important to evaluate the anatomical injury site, severity, and absence of hematomas on MRI. Not only the injury mechanism, a clear hematoma, and high severity but also distal aponeurosis injuries may be associated with long periods of return to play at competition levels.

Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) of the major salivary glands: an assessment of the optimal number and combination of b-values.

Purpose: To examine the optimal number and combination of b-values in intravoxel incoherent motion (IVIM) diffusionweighted imaging (DWI) of the major salivary glands. Material and methods: IVIM-DWI was performed on 10 healthy volunteers using 13 b-values (low b-values: 0-100 s/mm2; high b-values: 200-1000 s/mm2). The IVIM parameters and apparent diffusion coefficient of the bilateral major salivary glands were calculated using 13 b-values and were considered the standard values. We sequentially reduced the number of b-values to 10, 8, 6, and 5. The parameters in each combination were calculated. The standard values were compared with the parameters from each reduced b-value in IVIM-DWI. The Wilcoxon signed-rank test was used to determine whether there were any differences between the parameters in each combination. Bonferroni correction was conducted for multiple comparisons. Results: There were no significant differences between the standard values and parameters from the 2 combinations of 6 b-values. However, significant differences were observed between the standard values and parameters from some combinations of only 2 low or only 2 high b-values. Conclusions: IVIM-DWI of the major salivary glands could be performed using a minimum of 6 b-values. However, they should contain 3 low and 3 high b-values.

Anatomical description and short-term follow up clinical results for ultrasound-guided injection of medial collateral ligament bursa: New conservative treatment option for symptomatic degenerative medial meniscus tear.

BACKGROUND: In this study, we investigated newly developed ultrasound (US)-guided medial collateral ligament (MCL) bursa injection as a conservative therapy for symptomatic degenerative medial meniscal (MM) tears. We aimed to describe the anatomical target and precise technique of this injection, confirm its accuracy using fresh cadaveric knees, and then evaluate preliminary clinical outcomes. METHODS: Anatomical studies were performed on three fresh cadavers. For the clinical study, 50 patients with medial knee joint pain without knee osteoarthritis were treated with US-guided MCL bursa injection. Severity of pain was assessed pre-injection, and 1 week and 4 weeks post-injection using a 0-10 numerical rating scale (NRS). Clinical success was defined as a full return to daily activities. All patients underwent magnetic resonance imaging (MRI) within 1 week of the first injection. Patients who underwent surgery within 12 months of the first injection were investigated as clinically unsuccessful cases, and MRI and arthroscopic findings were examined. RESULTS: Compared with pre-injection (6.8 ±â€¯1.2), the average NRS score was significantly lower at 1 week (1.8 ±â€¯2.0) and at 4 weeks (1.5 ±â€¯1.7) post-injection (both P < 0.01). The primary clinical success rate was 76.0%, and injection-related adverse events were not observed. Nine patients underwent surgery (arthroscopic surgery for degenerative flap tear (n = 7) and high tibial osteotomy for medial meniscus posterior root tear and proximal tibial malalignment (n = 2)). CONCLUSIONS: US-guided MCL bursa injection is safe, reproducible, and effective for symptomatic MM degenerative tears. However, US-guided injections of the MCL bursa may be ineffective for flap tears and posterior root tears.

Ligamentization of the reconstructed ACL differs between the intraarticular and intraosseous regions: A quantitative assessment using UTE-T2* mapping.

BACKGROUND: The purpose of this study was to prospectively observe the trends of ultrashort echo time (UTE)-T2* values for the intraarticular and intraosseous regions of reconstructed anterior cruciate ligaments from 6 to 12 months after anterior cruciate ligament reconstruction by using UTE-T2* mapping, and to investigate the changes and differences over time in each region. METHODS: Ten patients underwent UTE-T2* mapping of the operated knee at 6, 9, and 12 months after anterior cruciate ligament reconstruction. The UTE-T2* values of intraarticular and intraosseous regions of reconstructed anterior cruciate ligaments at 6, 9, and 12 months postoperatively were statistically compared. RESULTS: The UTE-T2* values of the intraarticular region at 6 months postoperatively were significantly higher than those at 9 and 12 months. There were no significant differences in the UTE-T2* values at 6, 9, and 12 months postoperatively in the intraosseous region. At 6 months postoperatively, the UTE-T2* values of the intraarticular region were significantly higher than those of the intraosseous region. The UTE-T2* values of the intraosseous region at the tibia were significantly lower than those of the other sites at any postoperative time point. CONCLUSIONS: According to UTE-T2*mapping-based findings, histological maturation of reconstructed ACLs is faster in the intraosseous region than in the intraarticular region. In particular, the intraarticular region is still undergoing rapid histologic changes at 6 months postoperatively, and its tissue structure is less substantial than normal. The findings of this study may provide clues to determine the optimal timing for safe return to sports in terms of ligamentaization of reconstructed ACLs.

Microneedle Array-Assisted, Direct Delivery of Genome-Editing Proteins Into Plant Tissue.

Genome editing in plants employing recombinant DNA often results in the incorporation of foreign DNA into the host genome. The direct delivery of genome-editing proteins into plant tissues is desired to prevent undesirable genetic alterations. However, in most currently available methods, the point of entry of the genome-editing proteins cannot be controlled and time-consuming processes are required to select the successfully transferred samples. To overcome these limitations, we considered a novel microneedle array (MNA)-based delivery system, in which the needles are horizontally aligned from the substrate surface, giving it a comb-like configuration. We aimed to deliver genome-editing proteins directly into the inner layers of leaf tissues; palisade, the spongy and subepidermal L2 layers of the shoot apical meristem (SAM) which include cells that can differentiate into germlines. The array with needles 2 µm wide and 60 µm long was effective in inserting into Arabidopsis thaliana leaves and Glycine max (L.) Merr. (soybeans) SAM without the needles buckling or breaking. The setup was initially tested for the delivery of Cre recombinase into the leaves of the reporter plant A. thaliana by quantifying the GUS (ß-glucuronidase) expression that occurred by the recombination of the loxP sites. We observed GUS expression at every insertion. Additionally, direct delivery of Cas9 ribonucleoprotein (RNP) targeting the PDS11/18 gene in soybean SAM showed an 11 bp deletion in the Cas9 RNP target site. Therefore, this method effectively delivered genome-editing proteins into plant tissues with precise control over the point of entry.

Bursoscopic Ultrasound-Guided Ossicle Resection for Osgood-Schlatter Disease.

Osgood-Schlatter disease commonly affects physically active adolescents. It is a common cause of anterior knee pain and inflammation in this population. Its symptoms typically subside with conservative therapy. Surgery, including resection of mobile ossicles, is considered when the pain persists on kneeling or during sports after the skeletal maturity. In this procedure, we use a direct bursoscopic approach with ultrasound-guided ossicle resection. In comparison with the classical arthroscopic approach, the bursoscopic approach uses more distally placed portals. These reduce the risk of damage to the fat pad, meniscus, and ligament. Endoscopic surgeries, including arthroscopic and bursoscopic surgeries, use intraoperative fluoroscopy to resect ossicles because the ossicle cannot be clearly identified by endoscopic imaging alone. Fluoroscopy exposes patients and surgeons to radiation. Ultrasound-guided surgery identifies the exact positional relationship between the ossicle and grasping forceps without radiation exposure since fluoroscopy is unnecessary. Moreover, the risk of residual ossicles is reduced because tiny ossicles, which are difficult to detect under fluoroscopy, are visible on ultrasound. Ultrasound-guided ossicle resection was a viable treatment option for Osgood-Schlatter disease because it eliminated radiation exposure and reduced the risk of missed ossicles.

Incidence and temporal changes in lumbar degeneration and low back pain in child and adolescent weightlifters: A prospective 5-year cohort study.

This study was conducted to investigate the incidence of lumbar degeneration findings and low back pain (LBP) in children and adolescent weightlifters using magnetic resonance imaging (MRI) and medical questionnaires over a 5-year period. Moreover, we aimed to reveal the temporal changes in the lumbar vertebrae caused by long-term weightlifting training during the growth period. Twelve children and adolescent weightlifters who participated in weightlifting for >2 years (six boys, six girls, 11.4±2.0 years) were enrolled. Participants underwent annual medical questionnaire surveys, including data on practice frequency, competition history, presence of LBP, and lumbar examinations using MRI during the 5-year follow-up. Lumbar disc degeneration was detected in all the participants after 4 years, and lumbar disc herniation findings were detected in 33% of participants after 5 years; one underwent herniotomy during the follow-up period. Lumbar spondylolysis was detected in 58% of patients at 5 years. Although there were three participants who had LBP in the final year, none had LBP that prevented them from returning to weightlifting. This 5-year cohort study of 12 children and adolescent weightlifters detected lumbar degeneration in all participants. High frequency weightlifting training over a long period during the growth period may increase the risk of developing current and future LBP.

Suture Bridge Fixation for Posterior Cruciate Ligament Tibial Avulsion Fracture in Children.

Posterior cruciate ligament (PCL) tibial avulsion fractures in children are extremely rare. Due to the rarity of these injuries, careful attention to the specific physical examination and imaging findings is necessary for a proper diagnosis. PCL avulsion fractures can be missed on plain radiography in skeletally immature patients. Magnetic resonance imaging should be considered if sagging or posterior drawer sign is positive after a strong hit to the anterior aspect of the lower leg. With this knowledge, clinicians can formulate treatment plans that can return patients to their original functionality while avoiding potential morbidity from misdiagnoses. We treated these patients using the suture bridge method. In children, ossification is incomplete, and they possess a lot of cartilage, so screw fixation easily destroys avulsed fragment. The suture bridge method can firmly fix the avulsed fragments, reducing the risk of damage to the bone fragment; therefore, a secondary surgery for implant removal is not needed. Arthroscopic surgery also was expected to be technically difficult in children due to the limited scope of the operation. We used open fixation because the outcome was unaffected by open surgery and arthroscopic surgery, and all patients returned to full sporting activity postoperatively.

Tibial graft fixation methods and bone tunnel enlargement: A comparison between the TensionLoc implant system and the double-spike plate.

Background/objective: TensionLoc (Arthrex, Naples, Florida, USA), a tibial graft fixation system for anterior cruciate ligament (ACL) reconstruction, is expected to apply the preoperatively determined level of graft tension and allow setting of lower initial tension. Considering its mechanism, we hypothesised that TensionLoc would prevent postoperative bone tunnel enlargement (TE) through fixation with lower initial tension. Therefore, the present study aimed to compare TE between ACL reconstructions using the double-spike plate (DSP; Smith and Nephew, Andover, Massachusetts) and TensionLoc implant system. Methods: A total of 40 patients who underwent anatomical single-bundle ACL reconstruction with a hamstring tendon graft were retrospectively analysed. In the group in which DSP and screw were used, the initial graft tension was set to 40 N at 20° of knee flexion (group D). In the other group in which TensionLoc was used, the initial graft tension was set to 30 N at 20° of knee flexion (group T). Both groups included 20 patients each. Tunnel areas were measured using computed tomography images at one week and three months after surgery, and the TE ratio was calculated according to the following equation: TE ratio (%) = (tunnel area at three months after surgery - tunnel area at one week after surgery)/tunnel area at one week after surgery × 100. Results: The femoral TE ratios were significantly higher in group T (80.5% ± 28.8%) than in group D (45.5% ± 34.6%) (p = 0.001). However, the tibial TE ratios did not significantly differ between the two groups. Conclusion: Compared with ACL reconstruction using DSP and screw, ACL reconstruction using TensionLoc fixed the graft with lower initial tension but showed greater femoral TE and restricted knee extension in the early postoperative period.

Evaluation of skeletal muscle activity during foot training exercises using positron emission tomography.

The foot exercises "rock-paper-scissors" and "towel gathering" are widely used in patients with lower limb disorders; however, there are no detailed reports on muscle activity during such training. We quantitatively evaluated the difference in skeletal muscle activity between the two exercises using positron emission tomography. Eight university student athletes were included. Four participants each were assigned to the foot rock-paper-scissors and towel gathering groups. Participants in each group underwent continuous training for 15 min, and received an intravenous injection of 18F-fluorodeoxyglucose. After retraining for 15 min, participants rested for 45 min. Regions of interest were defined in 25 muscles. The standardized uptake value (SUV) in the trained limb was compared with that in the non-trained control limb. SUVs increased in four skeletal muscles (tibialis anterior, peroneus brevis, extensor hallucis brevis, and abductor hallucis) in the rock-paper-scissors group, and in four muscles (flexor digitorum longus, extensor hallucis brevis, extensor digitorum brevis, and quadratus plantae) in the towel gathering group. Thus, foot rock-paper-scissors and towel gathering involved skeletal muscles related to the medial longitudinal arch and toe grip strength, respectively. Given that the two exercises target different skeletal muscles, they should be taught and implemented according to their respective purposes.