Relationship between increased knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures.

INTRODUCTION: This study evaluated the correlation between postoperative knee joint line obliquity after medial open-wedge high tibial osteotomy and patient-reported outcome measures excluding excessively overcorrected knees. This study further identified preoperative radiological factors related to the increased postoperative knee joint line obliquity. MATERIALS AND METHODS: We retrospectively evaluated patients who underwent medial open-wedge high tibial osteotomy between March 2013 and March 2021. Postoperative excessively overcorrected knees with hip-knee-ankle angle > 7° were excluded. We investigated radiological parameters and patient-reported outcome measures preoperatively and at the last follow-up. The following radiologic parameters were measured: hip-knee-ankle angle, weight-bearing line ratio, mechanical medial proximal tibial angle, mechanical lateral distal femoral angle, lateral distal tibial angle, joint line convergent angle, knee joint line obliquity, ankle joint line obliquity, hip abduction angle, tibial posterior slope, Carton-Deschamps index, and patella tilting angle. Clinical outcomes were evaluated using Japanese knee outcome measures. This assessment criterion is based on the Western Ontario McMaster Universities Arthritis Index and MOS Short Form 36. Multiple regression analysis was performed to evaluate the association between postoperative knee joint line obliquity and patient-reported outcome measures or preoperative radiological factors (P < .05). RESULTS: A total of 52 knees were included. The mean age at the time of the surgery was 61.6 ± 9.0 years and the mean follow-up period was 30.6 ± 10.1 months. Increased postoperative knee joint line obliquity was associated with lower Japanese knee outcome measures. The preoperative hip-knee-ankle angle was significantly associated with postoperative knee joint line obliquity. CONCLUSIONS: Increased knee joint line obliquity after medial open-wedge high tibial osteotomy is associated with inferior clinical outcomes. Care should be given to the center of the rotational angulation in around-knee osteotomy to avoid postoperative increased knee joint line obliquity. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Revascularization of a Necrotic Femoral Head in Severely Slipped Capital Femoral Epiphysis With a Modified Dunn Procedure: A Case Report.

Avascular necrosis, a serious slipped capital femoral epiphysis (SCFE) complication, is difficult to treat. We report a rare case of revascularization of the necrotic femoral head in a 12-year-old male patient with a severe SCFE (posterior tilting angle, 87°). We performed the modified Dunn procedure (MDP), followed by long-term unloading therapy. Blood flow to the epiphysis had partially resumed 2.3 years postoperatively. At the final 4.5-year follow-up, blood flow had been restored, leading to epiphyseal closure without significant femoral head deformity or hip pain. The patient could walk unassisted, with a flexion range of 120°. These findings support the use of the MDP with long-term unloading therapy as a potential treatment option for severe SCFE.

Influence of anterior talofibular ligament injury and mechanical ankle anterior displacement on symptoms in individuals with chronic ankle instability.

CONTEXT: Repeated ankle sprains can lead to injuries, including those of the anterior talofibular ligament; however, the extent to which these ligament injuries are associated with symptoms of chronic ankle instability remains unclear. OBJECTIVE: To examine the influence of anterior talofibular ligament injury and ankle anterior displacement on symptoms of chronic ankle instability. DESIGN: Case-Control Study. SETTING: A university laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 426 college students completed a questionnaire survey on the history of ankle sprain. Thirty-four (24 males, 10 females; age = 20.6 ± 0.5 years), 49 (38 males, 11 females; age = 20.2 ± 1.2 years), and 39 (24 males, 15 females; age = 20.1 ± 1.1 years) participants were enrolled in the healthy, coper, and chronic ankle instability groups, respectively. DATA COLLECTION AND ANALYSIS: One examiner measured the anterior talofibular ligament delineation using ultrasound and anterior ankle displacement using a capacitance-type sensor device. The Cumberland Ankle Instability Tool was applied to assess pain and perceived instability. RESULTS: The anterior talofibular ligament was normal significantly more frequently in healthy participants and abnormal significantly more frequently in patients with chronic ankle instability (p < 0.001). Anterior ankle displacement was significantly greater in the coper and chronic ankle instability groups than in healthy individuals (p < 0.001), but no significant difference was observed between the coper and chronic ankle instability groups. There was no significant correlation between the anterior ankle displacement and Cumberland Ankle Instability Tool scores (p = 0.709) in participants with previous ankle sprains. CONCLUSION: Observation of an abnormal anterior talofibular ligament on ultrasonography is associated with anterior displacement of the ankle joint. However, it is assumed that the influence of anterior ankle displacement due to damage to the anterior talofibular ligament on the pain and perceived instability in chronic ankle instability is small.

Comparison by ultrasound shear wave elastography of toe flexor muscle contraction during MTP flexion exercise and short-foot exercise.

BACKGROUND: The intrinsic foot muscles play an important role in medial longitudinal arch support, as well as several extrinsic foot muscles. While various strength training methods specific to intrinsic foot muscles have been conducted, these exercises are associated with certain concerns regarding their effectiveness and difficulty. We developed a new exercise for the intrinsic muscles (MTP flexion exercise). OBJECTIVE: The aim was to compare the shear modulus of the toe flexors as the muscle contraction activity during MTP flexion and short-foot exercises using ultrasound shear wave elastography. METHODS: Eleven healthy participants were included in this study. The shear modulus of the toe flexor muscles was measured during MTP flexion and short-foot exercises using ultrasound shear wave elastography. The muscle shear modulus was statistically compared between the resting phase, and during the two exercises. RESULTS: The shear modulus during MTP flexion exercise was significantly greater than in the resting phase in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, and flexor digitorum longus. The flexor digitorum longus showed greater shear modulus during MTP flexion exercise than during short-foot exercise. CONCLUSION: MTP flexion exercise showed equivalent or greater contraction activity in certain intrinsic and extrinsic foot muscles when compared with short-foot exercise. This exercise is considered one of the training options for strengthening the intrinsic muscles of the foot.

Surgical Treatment for Non-union of the Great Toe Proximal Phalanx Stress Fracture in an Adolescent Jumping Athlete.

Stress fractures of the proximal phalanx of the great toe are primarily attributed to repetitive shear forces, with the vertical ground reaction forces exerting several times the body weight. In the initial stages of injury, conservative management anticipates bone healing within approximately five weeks, followed by a gradual return to sports activities over an additional five weeks. Athletes presenting with pain in this region warrant a thorough evaluation for stress fractures to initiate timely conservative care. In instances of delayed healing or non-union, surgical intervention is indicated. However, literature on the management and optimal timing of surgery, particularly in adolescent athletes, remains sparse. This case report, complemented by a literature review, offers insights into management based on the patient's clinical course.

Minimizing the risk of injury to the popliteal artery during pullout repair of medial meniscus posterior root tears: A cadaveric study.

Background: The purpose of this study was to investigate the positional effect of guide pins used in the transtibial pullout repair of medial meniscus posterior root tears on the popliteal artery. Methods: We used eight cadaveric knees. Two 2.4-mm guide pins were inserted into the posterior root of the medial meniscus at 50° to the articular surface from the medial edge of the tibial tuberosity (anteromedial group) and the anterior edge of the medial collateral ligament (posteromedial group) using an aiming guide placed at the posterior root attachment of the medial meniscus from the anteromedial portal. The posterior capsule was dissected, and the popliteal artery was identified. The positional effect of the guide pins on the popliteal artery was photographed arthroscopically at 0°, 30°, 60°, and 90° knee flexion angles. The popliteal artery diameter and the minimum distance between the popliteal artery center and the guide pin tip were measured. Results: At 90° knee flexion, most of the guide pins in the anteromedial (6 knees; 75 %) and posteromedial groups (7 knees; 87.5 %) collided with the femoral intercondylar wall. The rate of collision was significantly higher at the 90° knee flexion position than that at other angles (p = 0.02). The average shortest distance between the popliteal artery center and the guide pin tip at 0° knee flexion in the posteromedial group (5.4 mm ± 3.4 mm) was significantly greater than that at other knee flexion angles, although the mean distance in the posteromedial group was so negligible that the guide pin could penetrate the popliteal artery. Conclusions: Knee flexion at 90° causes less damage to the popliteal artery during the transtibial pullout repair of medial meniscus posterior root tears.

Clinical outcomes in patients with adamantinoma: Report from the bone and soft tissue tumor registry in Japan.

BACKGROUND: Adamantinomas are rare malignant bone tumors. Due to their low incidence, there are few reports on the clinical results of adamantinoma. OBJECTIVES: This study aims to clarify outcomes in patients with adamantinoma using data from the National Bone and Soft Tissue Tumor Registry. METHODS: From 2006 to 2019, 38 cases of tibial origin were included. Twenty-four were male and 14 were female, with a mean age of 37 (6-87) years and a mean follow-up of 35 (1-128) months. RESULTS: Surgery was performed in 33 cases (87%) (curettage: 4 cases, wide resection: 27 cases, amputation: 2 cases). Reconstruction was performed in 27 patients who underwent wide resection. A total of 12 additional surgeries were performed in 11 patients. The main reason for the additional surgeries was nonunion of grafting bone in 6 cases. Oncologic outcomes were DOC (death from other causes) in one case and NED (no evidence of disease) in 37 cases. CONCLUSIONS: The results of treatment of adamantinomas in Japan have been extremely favorable. This may be due in part to the large number of cases with wide resection.

Platelet-rich plasma does not accelerate the healing of damaged muscle following muscle strain.

Although platelet-rich plasma (PRP) has been widely used regardless of the severity of muscle strain, there have been very few basic studies in which its effects on muscle injury were examined by using models that accurately mimic the clinical muscle strain injury process. Therefore, the aim of this study was to confirm by physiological and structural analyses whether PRP purified by a general preparation method has a muscle healing effect on muscle damage caused by eccentric contraction (ECC). Male Wistar rats were subjected to muscle injury induced by ECC in bilateral plantar flexor muscles using electrical stimulation and an automatically dorsiflexing footplate. The rats were randomly assigned to three groups by type of injection: phosphate-buffered saline (PBS), leukocyte-poor PRP (LP-PRP), or leukocyte-rich PRP (LR-PRP) injection into gastrocnemius muscles three times at weekly intervals. The platelet concentrations of the LP-PRP and LR-PRP were three to five times higher than that of whole blood. The recovery process of torque strength in the plantar flexor muscle, signal changes in MRI images, and histological evaluation 3 weeks after injury showed no obvious differences among the three groups, and every muscle recovered well from the injury without marked fibrosis. The results that neither LP-PRP nor LR-PRP was found to accelerate healing of muscle injuries suggested that conventional preparation and use of PRP for simple muscle injuries caused by muscle strain should be carefully considered, and further basic research using models that accurately mimic clinical practice should be carried out to determine the optimal use of PRP.

Characteristics of Nonunion After Arthroscopic Ankle Arthrodesis: A Multicenter Retrospective Cohort Study.

Nonunion is a major complication of arthroscopic ankle arthrodesis. However, the characteristics and risk factors of nonunion are not well understood. This retrospective multicenter observational study aimed to clarify the characteristics of nonunion after arthroscopic ankle arthrodesis. We included 154 patients who underwent arthroscopic ankle arthrodesis at any 1 of 5 institutions. Patients were divided into 2 groups: union and nonunion, and the groups were compared. Age, sex, body mass index, diabetes, smoking, corticosteroid use, diagnosis, treatment information, treatment protocol, radiographic evaluation, and patient-reported outcomes were recorded and analyzed. On radiographs, bony union was observed in 142 ankles (91.0%) but not in 12 ankles (9.0%). Postoperative radiographic tibial bony gap (mm) was significantly larger in the nonunion group (medial = 1.98, center = 1.65, anterior = 2.21, middle = 1.72, posterior = 3.01) than in the union group (medial = 1.35, center = 1.13, anterior = 1.28, middle = 1.03, posterior = 2.03). Furthermore, the visual analog score (VAS) of pain and pain-related self-administered foot evaluation questionnaire (SAFE-Q) subscale score significantly worsened in the nonunion group (VAS = 3.83, SAFE-Q subscale score = 69.8) compared to that in the union group (VAS = 1.35, SAFE-Q subscale score = 76.6). A larger radiographic tibiotalar bony gap was observed in the nonunion group. Other measurement outcomes were not associated with nonunion. Additionally, patient-reported outcomes markedly worsened in the nonunion group.

Development of T cell receptor-engineered T cells targeting the sarcoma-associated antigen papillomavirus binding factor.

We previously identified papillomavirus binding factor (PBF) as an osteosarcoma antigen recognized by an autologous cytotoxic T lymphocyte clone. Vaccination with PBF-derived peptide presented by HLA-A24 (PBF peptide) elicited strong immune responses. In the present study, we generated T cell receptor-engineered T cells (TCR-T cells) directed against the PBF peptide (PBF TCR-T cells). PBF TCR was successfully transduced into T cells and detected using HLA-A*24:02/PBF peptide tetramer. PBF TCR-T cells generated from a healthy donor were highly expanded and recognized T2-A24 cells pulsed with PBF peptide, HLA-A24+ 293T cells transfected with PBF cDNA, and sarcoma cell lines. To establish an adoptive cell therapy model, we modified the PBF TCR by replacing both α and ß constant regions with those of mice (hybrid PBF TCR). Hybrid PBF TCR-T cells also showed reactivity against T2-A24 cells pulsed with PBF peptide and to HLA-A24+ 293T cells transfected with various lengths of PBF cDNA including the PBF peptide sequence. Subsequently, we generated target cell lines highly expressing PBF (MFH03-PBF [short] epitope [+]) containing PBF peptide with in vivo tumorigenicity. Hybrid PBF TCR-T cells exhibited antitumor effects compared with mock T cells in NSG mice xenografted with MFH03-PBF (short) epitope (+) cells. CD45+ T cells significantly infiltrated xenografted tumors only in the hybrid PBF TCR T cell group and most of these cells were CD8-positive. CD8+ T cells also showed Ki-67 expression and surrounded the CD8-negative tumor cells expressing Ki-67. These findings suggest that PBF TCR-T cell therapy might be a candidate immunotherapy for sarcoma highly expressing PBF.

Quantitative assessment of anterior talofibular ligament quality in chronic lateral ankle instability using magnetic resonance imaging T2* value.

OBJECTIVE: To determine T2* normal reference values for anterior talofibular ligament (ATFL) and to investigate the feasibility of the quantitative ATFL quality evaluation in chronic lateral ankle instability (CLAI) using T2* values. MATERIALS AND METHODS: This study enrolled 15 patients with CLAI and 30 healthy volunteers. The entire ATFL T2* values from the MRI T2* mapping were measured. The prediction equation (variables: age, height, and weight) in a multiple linear regression model was used to calculate the T2* normal reference value in the healthy group. T2* ratio was defined as the ratio of the actual T2* value of the patient's ATFL to the normal reference value for each patient. A Telos device was used to measure the talar tilt angle (TTA) from the stress radiograph. RESULTS: T2* values of ATFL in the healthy and CLAI groups were 10.82 ± 1.84 ms and 14.36 ± 4.30 ms, respectively, which are significantly higher in the CLAI group (P < 0.05). The prediction equation of the normal reference T2* value was [14.9 + 0.14 × age (years) - 4.7 × height (m) - 0.03 × weight (kg)] (R2 = 0.65, P < 0.0001). A significant positive correlation was found between the T2* ratio and TTA (r = 0.66, P = 0.007). CONCLUSION: MRI T2* values in patients with CLAI were higher than those in healthy participants, and the T2* ratio correlated with TTA, suggesting that T2* values are promising for quantitative assessment of ATFL quality preoperatively.

Coefficient of variation of T2-weighted MRI may predict the prognosis of malignant peripheral nerve sheath tumor.

BACKGROUND: We investigated whether non-enhancement MRI features, including measurement of the heterogeneity of the tumor with MR T2 imaging by calculating coefficient of variation (CV) values, were associated with the prognosis of non-metastatic malignant peripheral nerve sheath tumors (MPNST). METHODS: This retrospective study included 42 patients with MPNST who had undergone surgical resection (mean age, 50 years ± 21; 20 male participants). Non-enhancement MR images were evaluated for signal intensity heterogeneity on T1- and T2-weighted imaging, tumor margin definition on T1- and T2-weighted imaging, peritumoral edema on T2-weight imaging, and CV. We measured the signal intensities of MR T2-weighted images and calculated the corresponding CV values. CV is defined as the ratio of the standard deviation to the mean. The associations between factors and overall survival (OS) were investigated via the Kaplan-Meier method with log-rank tests and the Cox proportional hazards model. RESULTS: The mean CV value of MR T2 images was 0.2299 ± 0.1339 (standard deviation) (range, 0.0381-0.8053). Applying receiver operating characteristics analysis, the optimal cut-off level for CV value was 0.137. This cut-off CV value was used for its stratification into high and low CV values. At multivariate survival analysis, a high CV value (hazard ratio = 3.63; 95% confidence interval = 1.16-16.0; p = 0.047) was identified as an independent predictor of OS. CONCLUSION: The CV value of the signal intensity of heterogenous MPNSTs MR T2-weighted images is an independent predictor of patients' OS.

Remission of hypersensitivity by simple weight load stimuli in a complex regional pain syndrome mouse model.

Painful sensitivity of the hand or foot are the most common and debilitating symptoms of complex regional pain syndrome (CRPS). Physical therapy is standard treatment for CRPS, but evidence supporting its efficacy is minimal and it can be essentially impossible for CRPS patients to actively exercise the painful limb. Using the well-characterized distal tibial fracture CRPS mouse model, we compared the therapeutic effects of several weeks of daily hindlimb loading versus rotarod walking exercise. The effects of loading and exercise were evaluated by weekly testing of hind-paw withdrawal thresholds to von Frey fibers and radiant heat, as well as measurements of paw and ankle edema. At 6 weeks after fracture, the mice were killed and the ipsilateral femur, spinal cord and L4/5 dorsal root ganglia, and hind-paw skin collected for PCR assays and paw skin Immunohistochemistry evaluation. Hindlimb loading reduced hind-paw von Frey allodynia and heat hyperalgesia and edema within a week and these effects persisted for at least a week after discontinuing treatment. These therapeutic effects of loading exceeded the beneficial effects observed with rotarod walking exercise in fracture mice. Levels of nerve growth factor and transient receptor potential vanilloid 1 (TRPV1) immunostaining in the hind-paw skin were increased at 6 weeks after fracture, and both loading and exercise treatment reduced increases. Collectively, these results suggest that loading may be an effective and possibly curative treatment in CRPS patients with sensitivity in the affected limb.

Thumb pronation efficacy of Camitz tendon transfer with insertion on the ulnar capsule of the metacarpophalangeal joint: a cadaver study.

Several studies have indicated that Camitz transfer for severe carpal tunnel does not adequately restore thumb opposition. The aim of this study was to determine whether modification of the distal insertion of the transferred palmaris longus tendon could provide more effective opposition. We used 12 fresh-frozen upper extremity specimens. For spatial analysis, we used a three-dimensional motion-tracking device. At 0 N and 5 N of traction force, the pronation angle was significantly larger for the modified procedure than for the conventional procedure. There was no significant difference in the palmar abduction angle between the two groups. The modified palmaris longus tendon insertion on the ulnar side of the thumb metacarpophalangeal joint provides more effective thumb pronation than conventional Camitz opponensplasty in a cadaver model. .

Association of central sensitization, visceral fat, and surgical outcomes in lumbar spinal stenosis.

BACKGROUND: Controversy remains regarding predictors of surgical outcomes for patients with lumbar spinal stenosis (LSS). Pain sensitization may be an underlying mechanism contributing to LSS surgical outcomes. Further, obesity is associated with dissatisfaction and poorer outcomes after surgery for LSS. Therefore, this study aimed to examine the relationship between central sensitization (CS), visceral fat, and surgical outcomes in LSS. METHODS: Patients with LSS were categorized based on their central sensitization inventory (CSI) scores into low- (CSI < 40) and high- (CSI ≥ 40) CSI subgroups. The participants completed clinical outcome assessments preoperatively and 12 months postoperatively. RESULTS: Overall, 60 patients were enrolled in the study (28 men, 32 women; mean age: 62.1 ± 2.8 years). The high-CSI group had significantly higher mean low back pain (LBP), leg pain, and leg numbness visual analogue scale (VAS) scores than the low-CSI group (p < 0.01). The high-CSI group had a significantly higher mean visceral fat area than the low-CSI group (p < 0.01). Postoperatively, LBP VAS score was significantly worse in the high-CSI group. Relative to preoperatively, postoperative leg pain and leg numbness improved significantly in both groups. CONCLUSIONS: We believe that neuro decompression can be effective for LSS surgical outcomes in patients with CS; nonetheless, it should be approached with caution owing to the potential for worsening LBP. Additionally, visceral fat is an important indicator suggesting the involvement of CS.

Satisfactory outcomes after one-stage revision anterior cruciate ligament reconstruction using rectangular tunnel technique.

PURPOSE: One-stage revision anterior cruciate ligament reconstruction (ACLR) with the anatomic rectangular tunnel (RT) technique using bone-patellar tendon-bone (BTB) grafts results in anatomically precise tunnel placement and secure graft fixation. This study evaluated knee joint laxity and clinical outcomes in terms of femoral tunnel overlap. It was hypothesised that there would be no significant differences in knee joint laxity or clinical outcomes regardless of femoral tunnel overlap. METHODS: Between 2012 and 2021, a single surgeon conducted 196 one-stage revision ACLRs with the RT technique using BTB grafts. Patients were divided based on the presence of femoral tunnel overlap. Knee joint laxity was evaluated using the Lachman test, pivot shift test, and side-to-side difference measured with a KT-1000 arthrometer. Clinical outcomes were assessed using the Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) Knee Examination Form 2000. Knee joint laxity and clinical outcomes were compared between groups after a median follow-up of 2.5 years (range 2.0-8.0). RESULTS: The study included 30 and 73 patients in the overlap and non-overlap groups, respectively. No significant differences were observed in the results of the Lachman test, pivot shift test, or KT-1000 arthrometer as well as in the Lysholm, KOOS, or IKDC scores between the two groups. Based on the IKDC scores, all patients were graded as normal or nearly normal. CONCLUSION: One-stage revision ACLR with the RT technique using BTB grafts improved knee joint laxity and had favourable clinical outcomes regardless of femoral tunnel overlap. To achieve optimal results in one-stage revision ACLR, it is crucial to create a tunnel within the anatomical attachment area and ensure proper graft fixation and tensioning. LEVEL OF EVIDENCE: III.

Evaluation of the activities of the intrinsic and extrinsic muscles of the foot during toe flexion with or without interphalangeal joint flexion using ultrasound shear wave elastography.

The intrinsic muscles of the foot are important to maintain the arch of the foot and to participate in sports activities. Using ultrasound shear wave elastography, we investigated the effect of different toe flexion methods on the activity of the intrinsic and extrinsic muscles of the foot. The study included 15 healthy adults who performed toe flexion under 2 conditions: with interphalangeal (IP) joint flexion and without IP joint flexion. The applied load during flexion was 500 g. Muscle stiffness was measured in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, flexor hallucis longus, and flexor digitorum longus muscles using ultrasound shear wave elastography. Muscle stiffness was statistically compared with IP flexion and without IP flexion (P < 0.05). The stiffness of the abductor hallucis (P < 0.0005), flexor hallucis brevis (P = 0.022), and flexor digitorum brevis muscles (P < 0.0005) was significantly greater without IP flexion than with IP flexion. In contrast, the muscle stiffness of the flexor hallucis longus (P = 0.001) and the flexor digitorum longus (P = 0.004) was significantly greater during with IP flexion than without IP flexion. This study shows that the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis muscles are more active during toe flexion without IP flexion. These results suggest that the toe flexion method is important for more effective training of the intrinsic muscles of the foot.

A position-adaptive noise-reduction method using a deep denoising filter bank for dedicated breast positron emission tomography images.

Dedicated breast positron emission tomography (db-PET) is more sensitive than whole-body positron emission tomography and is thus expected to detect early stage breast cancer and determine treatment efficacy. However, it is challenging to decrease the sensitivity of the chest wall side at the edge of the detector, resulting in a relative increase in noise and a decrease in detectability. Longer acquisition times and injection of larger amounts of tracer improve image quality but increase the burden on the patient. Therefore, this study aimed to improve image quality via reconstruction with shorter acquisition time data using deep learning, which has recently been widely used as a noise reduction technique. In our proposed method, a multi-adaptive denoising filter bank structure was introduced by training the training data separately for each detector area because the noise characteristics of db-PET images vary at different locations. Input and ideal images were reconstructed based on 1- and 7-min collection data, respectively, using list mode data. The deep learning model used residual learning with an encoder-decoder structure. The image quality of the proposed method was superior to that of existing noise reduction filters such as Gaussian filters and nonlocal mean filters. Furthermore, there was no significant difference between the maximum standardized uptake values before and after filtering using the proposed method. Taken together, the proposed method is useful as a noise reduction filter for db-PET images, as it can reduce the patient burden, scan time, and radiotracer amount in db-PET examinations.

Ultra-Short Echo Time-MRI T2* Mapping of Articular Cartilage Layers Is Associated with Histological Early Degeneration.

OBJECTIVE: Ultra-short TE (UTE) sequences on MRI are a technique that improves the visualization of tissues with short T2 relaxation time, such as deep cartilage layers. In addition, T2* relaxation time calculated from the UTE has the potential to evaluate water molecules bound to the cartilage matrix. This study was performed to determine if there is an association between UTE-T2* relaxation time by cartilage layer and histological degeneration in knee osteoarthritis (OA). DESIGN: Seven knees that had undergone total knee arthroplasty (TKA) were included in the study, and the lateral tibial cartilage, which had the least degeneration of the resected bones, was used as the sample. The T2* relaxation time of 4 patients with no abnormal findings on MRI was the reference relaxation time. Histological degeneration of TKA samples was assessed by the Mankin score and graded as the early OA group (≤3 points) and the advanced OA group (≥4 points). The association between T2* relaxation time and Mankin grade in each cartilage layer was compared. The effect of angiogenesis to the tidemark on T2* relaxation time was also compared. RESULTS: T2* relaxation time of the cartilage layer was significantly longer in early OA than that in the control group. In the deep cartilage layer, the mean T2* relaxation time for angiogenesis (-) was 15.7 ms, whereas it was significantly shorter for angiogenesis (+) at 8.2 ms. CONCLUSIONS: The UTE-T2* relaxation time was associated with histological cartilage degeneration, suggesting a potential application in monitoring early cartilage degeneration.

Relationships of cross-sectional area of the thigh muscles before or after total knee arthroplasty with postoperative pain or patient satisfaction: A retrospective, exploratory study.

Background: It has been suggested that lower limb strength related to persistent postsurgical pain. The aim of the present study was to investigate the relationships of pre-operative or postoperative cross-sectional area (CSA) of the thigh muscles with knee pain or patient satisfaction after total knee arthroplasty (TKA). Methods: Twenty patients who had undergone TKA (3 men and 17 women; mean age 75.2 ± 8.7 years) were included. CSAs of the thigh muscle (THIGH) and quadriceps muscle (QUAD) were retrospectively measured at the CT slice 10-cm superior to the quadriceps tendon insertion at the proximal pole of the patella. THIGH CSA and QUAD CSA to body weight ratios (mm2/kg), THIGH/W and QUAD/W ratios, respectively, were calculated. Knee pain and patient satisfaction postoperatively were also quantified by patient-reported measurements based on the 2011 Knee Society Score (KSS). The correlations between the THIGH/W and QUAD/W ratios and the KSS were evaluated using Spearman's rank correlation coefficient. Results: The preoperative THIGH/W ratio was positively correlated with KSS-pain, (r = 0.58, p < 0.05). The preoperative QUAD/W ratio was positively correlated with KSS-pain (r = 0.52, p < 0.05) and KSS-satisfaction (r = 0.44, p < 0.05). The postoperative THIGH/W ratio was positively correlated with KSS-pain (r = 0.45, p < 0.05). The postoperative QUAD/W ratio was positively correlated with KSS-pain (r = 0.49, p < 0.05) and KSS-satisfaction (r = 0.48, p < 0.05). Conclusion: There were significant correlations between quadriceps or thigh muscle CSA and pain or patient satisfaction after TKA. This research may help relieve pain and increase patient satisfaction after TKA in the future.