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Background: Chronic mechanical stress on the second metatarsal head (2 MH) can be a risk factor for osteoarthritis (OA) and dislocation of the second metatarsophalangeal joint (2MTPJ) in hallux valgus (HV). This study aimed to investigate the stress distribution of the 2 MH in HV patients and determine the factors associated with dislocation and OA of the 2MTPJ., Methods: In total, 115 feet with HV were retrospectively reviewed and divided into two groups: those with subluxation or dislocation of the 2MTPJ (group D, 27 feet) and those without (group N, 88 feet). The control group (group C) included 33 feet without HV. Group N was divided into OA and non-OA (NOA) groups according to the presence or absence of OA of the 2MTPJ. The Hounsfield Unit (HU) value of the subchondral bone of the 2 MH was measured on sagittal slices of the preoperative computed tomography images and divided by the HU value of the navicular region (HU ratio). The relationship between the HU ratios and radiographic parameters was compared., Results: The HU ratios were significantly higher in group N than those in groups C and D. In group N, the protrusion of the second metatarsal relative to the third and fourth metatarsals (M2-M3, M2-M4) was positively correlated with the dorsal and central HU ratios, respectively. Group D had a significantly larger HV angle (HVA) and M2-M3 than group N. HVA, the first-second intermetatarsal angle, M2-M3, M2-M4, and dorsal and central HU ratios were significantly larger in the OA group than in the NOA group. The cutoff value of M2-M3 was 5.5 mm when comparing groups D and N, and 4.4 mm when comparing the OA and NOA groups., Conclusions: Severe HV and a longer M2-M3 and M2-M4 may be associated with a high risk of dislocation and OA of the 2MTPJ., Level of Evidence: Ⅲ., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2024 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: In the treatment of chronic lateral ankle instability (CLAI), the repair of the calcaneofibular ligament (CFL) and anterior talofibular ligament (ATFL) is still being discussed, possibly due to the difficulty in assessing CFL injuries. In particular, it is challenging to evaluate the extent of CFL deficiency quantitively. We hypothesized that CFL tension change would alter morphology of the CFL on magnetic resonance imaging (MRI) and that measuring this morphological change allows assessing CFL injury quantitatively. Thus, this study aimed to analyze the feasibility of quantitatively assessing CFL injuries using MRI., Methods: Sixty-four ankles with CLAI were included and divided into two groups: with (ATFL and CFL group, 31 ankles) or without CFL repair (ATFL group, 33 ankles) in addition to arthroscopic ATFL repair. The angle between the CFL and calcaneal axis (CFLCA) and the bending angles of the CFL was defined as the flexed CFL angle (FCA) were measured on the oblique CFL view of preoperative MRI. The diagnostic abilities of these angles for CFL injury and correlations between these angles and stress radiographs were analyzed., Results: The sensitivity and specificity of CFLCA were 86.7 % and 88.7 %, and those of FCA were 63.3 % and 77.4 %, respectively. The combination of CFLCA and FCA improved the sensitivity to 93.3 %. The cutoff points of CFLCA and FCA were 3.8° and 121.2°, respectively. There were significant moderate and weak correlations between the talar tilting angle and CFLCA or FCA (rs = -0.533, and rs = -0.402, respectively). The CFLCA and FCA were significantly smaller in the ATFL and CFL group than those in the other groups., Conclusions: Measurement of CFLCA and FCA in oblique CFL view on MRI could be useful for the quantitative evaluation of CFL injury in patients with CLAI． LEVEL OF EVIDENCE: Level IV. case-control study., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Studies have shown that the first metatarsal contributes to hallux valgus. The proximal phalanx, another factor that defines the hallux valgus angle, also contributes to the development of hallux valgus. There have been no reports on the use of computed tomography to evaluate bone morphology of the proximal phalanx. The purpose of this study was to analyze the morphology and deformity of the proximal phalanx and its relationship to hallux valgus using computed tomography, and to consider the indications for proximal phalanx surgery in hallux valgus., Methods: Patients who consulted at our clinic for foot and ankle disorders and underwent both weight-bearing radiography and computed tomography between May 2019 and March 2022 were included in the study. The hallux valgus angle, sesamoid subluxation, first metatarsal length, proximal phalanx length, metatarsal-proximal phalanx ratio, proximal phalanx valgus angle, metatarsal-proximal phalanx angle, proximal phalanx rotation angle, and distal phalanx-proximal phalanx angle were measured. These parameters were compared between the hallux valgus and control groups. In the hallux valgus group, the hallux valgus and proximal phalanx valgus angles were measured and compared using weight-bearing radiographs., Results: A total of 83 feet in 65 patients were diagnosed with hallux valgus (hallux valgus group; mean age of 68.0 ± 13.8 years) and 30 feet in 22 patients without hallux valgus (control group; mean age of 67.0 ± 25.8 years) were included in the study. The proximal phalanx length, metatarsal-proximal phalanx ratio and angle, and distal phalanx-proximal phalanx angle were significantly greater in the hallux valgus group than in the control group. However, the proximal phalanx valgus and rotation angles were not significantly different between the groups., Conclusion: Since there was no significant difference in the proximal phalanx morphology, except length, between the hallux valgus and control groups, the indications for osteotomy of the proximal phalanx should be carefully considered., Competing Interests: Declaration of competing interest None., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: During surgery for osteochondral lesions of the talus (OLT), preservation or excision of the osteochondral fragment is chosen based on the cartilage condition which influences the indication and clinical outcomes of surgical treatments. However, it is difficult to predict arthroscopic and histological findings of the cartilage on osteochondral fragments by radiographic evaluation. We focused on osteoarthritis (OA) changes on plain radiographs to predict the cartilage condition of the OLT. This study aimed to evaluate whether OA changes, including osteophyte and joint space narrowing, could predict arthroscopic and histological findings of the cartilage in OLT., Methods: Seventy ankles with OLT were included in this study. Osteophytes and joint space narrowing were scored on plain radiographs. Lesion sizes were measured on computed tomography images. The cartilage surfaces of fragments were arthroscopically assessed using the International Cartilage Repair Society (ICRS) grade. Biopsy specimens from 32 ankles were histologically analyzed using the Mankin score. The relationships between OA scores, lesion size, ICRS grades, and Mankin score were analyzed., Results: OA changes were frequently observed with increasing ICRS grades, especially in the medial tibiotalar joint. OA scores in patients with ICRS grade 1 were significantly lower than those in ICRS grades 2,3, and 4. The lesion sizes in patients with ICRS grade 3 and 4 were significantly smaller than those in patients with ICRS grade 1 and 2. Histological analysis showed increasing Mankin scores as the ICRS grade worsened. A mild correlation existed between the OA and Mankin scores (rs = 0.494)., Conclusions: OA changes, such as osteophyte formation and joint space narrowing, are associated with arthroscopic findings of the articular surface and cartilage degeneration in osteochondral fragment in OLT. Articular cartilage conditions can be predicted by OA changes on plain radiographs, which is useful for choosing the appropriate treatment for patients with OLT., Level of Evidence: Level Ⅳ, case series., Competing Interests: Declaration of competing interest No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Poor clinical outcomes in bone marrow stimulation (BMS) for the osteochondral lesion of the talus (OLT) are caused by subchondral bone deterioration. It is reported that microfracture induces endochondral ossification in the subchondral bone, which may affect the subchondral bone condition after BMS. This study analyzed osteosclerotic patterns of the bed in OLTs on computed tomography (CT) images and the relationship between the subchondral bone condition and clinical outcomes of BMS., Methods: Sixty-nine ankles in 61 patients with OLT were included. Hounsfield unit (HU) on the bed of OLTs was measured on CT images and the pattern of osteosclerosis or absorption in the bed was analyzed. In these patients, 25 ankles in 24 patients underwent BMS. They were divided into 2 groups according to the presence of bone marrow edema (BME) one year after surgery, and clinical outcomes were compared., Results: HUs in the anterior region were significantly higher than those of other areas. In patients with BMS, the JSSF scale for BME positive group (88.0 ± 7.7 points) was significantly lower than that for BME negative group (95.0 ± 6.1 points) (p < 0.05) at the final follow-up. On preoperative CT images, HU values of the central region in the BME-positive group were significantly lower than those in the BME-negative group (p < 0.05)., Conclusion: Osteosclerotic changes in the anterior part of the bed were frequently observed, and BMS for the area with low HU values decreased clinical outcomes. BMS should be performed with attention to subchondral bone condition to obtain good clinical outcomes., Level of Evidence: 4, case series., Competing Interests: Declaration of Competing Interest No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Hypermobility of the first tarsometatarsal joint plays an important role in hallux valgus pathogenesis. The peroneus longus is recognized as a dynamic stabilizer of the first tarsometatarsal joint. However, the association between the peroneus longus function and the hallux valgus deformity remains unknown. This study aimed to determine the effect of peroneus longus contraction induced by electrical muscle stimulation on the correction of hallux valgus radiographic parameters in patients with hallux valgus., Methods: Thirty-five patients with hallux valgus (47 feet; 2 men, 33 women; mean age 64.9 years) were included. Non-weight-bearing dorsoplantar radiographs of the foot were obtained with and without electrical muscle stimulation of the peroneus longus. Radiographic parameters of hallux valgus deformities, including the hallux valgus angle, intermetatarsal angle, first metatarsal protrusion distance, and distance between the first and second metatarsal bases, were measured and compared between the two conditions., Results: All hallux valgus radiographic parameters were significantly improved by contraction of the peroneus longus. The median hallux valgus angle decreased by 13.2°. Fewer changes in the hallux valgus angle were identified in patients with severe deformity and geriatric patients., Conclusions: Although the peroneus longus muscle has received little attention in the management of hallux valgus, our findings suggest that it has the potential to be a novel conservative approach for treating mild-to-moderate hallux valgus., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: The severity of hallux valgus (HV) deformity is associated with recurrence after corrective surgery because of the degenerative change of the medial capsule including the medial collateral ligament (MCL) at the metatarsophalangeal joint. This study aimed to assess the effectiveness of the MCL augmentation using a suture tape anchor of the recurrence of HV and to evaluate the histological changes of the medial joint capsule in HV patients., Methods: Thirty-four feet with severe hallux valgus were included and divided into 2 groups. Seventeen feet had the MCL reconstruction using suture tape anchor with a combination of the corrective osteotomy as the suture tape group (mean age, 64.0 years), and other seventeen feet had the corrective osteotomy without MCL reconstruction as the control group (mean age, 62.0 years). HV angle (HVA) and intermetatarsal angle (IMA) on the weight-bearing radiograms and the Japanese Society for Surgery of the Foot (JSSF) score in both groups were compared at the final follow-up. The medial capsule was harvested from other 20 feet with HV and the relationship between the severity of HV and the histological findings was analyzed., Results: HVA, IMA, and JSSF scores in both groups were significantly improved from preoperatively to the final follow-up (P < 0.01). At the final follow-up, HVA in the suture tape group (9.2°) was significantly smaller than that in the control (15.4°) (P < 0.01). There were no significant differences in the IMA and the JSSF score at the final follow-up between both groups. Histological scores in HV with ≥40° HVA was significantly worse than those in <40°., Conclusion: The medial joint capsule in severe HV deformity showed the degenerative change and the MCL reconstruction using suture tape combined with osteotomy provides a strong medial constraint to prevent the recurrence of the deformity in severe hallux valgus., Level of Clinical Evidence: 3., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Arthroscopic ankle arthrodesis (AAA) has become popular because of its higher rate of bone union, lower invasiveness, and shorter hospital stays compared to those of open arthrodesis. However, postoperative malalignment is often observed for severe varus deformity, which can cause nonunion, pain, and adjacent joint arthrosis. A compression staple can provide a persistent, strong compressive force on the bone surface. This study aimed to clarify the difference in alignment correction in AAA by comparing a compression staple and screws fixation with screws-only fixation pre- and postoperatively., Methods: Seventy ankles in 67 patients undergoing AAA were retrospectively reviewed. AAA with three screws through the distal tibia was performed in 53 ankles, and 17 ankles underwent AAA with a compression staple and two screws. After the preparation of the joint surface arthroscopically, patients in the S group had three canulated cancellous screws inserted through the medial tibia. Patients in the CS group had a compression staple placed at the lateral aspect of the tibiotalar joint and two screws inserted through the medial side. Clinical scores and pre-and postoperative alignment on plain radiographs were compared between the two procedures., Results: There were no significant differences in the pre-and postoperative Japanese Society for Surgery of the Foot scale. One ankle in the S group exhibited nonunion. There were no significant differences in talar tilt and tibiotalar angles between the groups. The tibial plafond angle in the CS group was significantly lower than that in the S group (p < 0.05). Postoperatively, talar tilt and tibiotalar angles on the coronal image, and the lateral tibiotalar angle in the CS group were significantly lower than those in the S group (p < 0.05)., Conclusion: AAA with a compression staple and two-screw fixations could obtain more optimal alignments than AAA with screw-only fixation, even in cases with severe varus deformity., Competing Interests: Declaration of competing interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2024 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: It is unclear whether osteochondral lesions of the talus (OLTs) without chronic lateral ankle instability (CLAI) progress to osteoarthritis, which affects the therapeutic strategy. Especially, the efficacy of conservative treatment for OLT remains controversial. Since various anatomical abnormalities have been reported, there may be abnormal movement of the talus in the mortise, causing ankle instability. We hypothesized that OLTs have frequent osteoarthritic changes even without CLAI. This study aimed to evaluate the incidence of osteoarthritic changes and stress distribution on the talus in OLT., Methods: Fifty-eight ankles with medial OLT without CLAI were retrospectively reviewed. Osteophytes and joint space narrowing on radiographs were scored using Kraus's classification and compared to ankles without OLTs. OA scores were compared between over 18 years and less than 17 years in OLTs. On computed tomography images, the area of OLTs was measured. Besides, Hounsfield Units (HU) of the talus in patients with and without OLTs were measured and compared., Results: Osteoarthritic changes were observed in 54 of the 58 ankles (94.8%) in the OLT patients. Osteophytes were frequently observed at the medial gutter and anterior tibial plafond. The OA score in patients aged over 18 years was significantly higher than that in patients aged less than 17 years (P < 0.05). HU values in the talus were significantly higher than those in non-OLT patients. OLTs more than 100 mm 2 had a significantly higher osteoarthritic score than those less than 100 mm 2 ., Conclusion: Medial OLT without CLAI has frequently osteoarthritic changes, especially large lesions. Osteoarthritic changes in OLTs will progress over time, which needs to be considered when deciding whether to perform the surgical or non-surgical treatment., Competing Interests: Declaration of competing interest No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Ligament quality can affect clinical outcomes of ligament repair in chronic lateral ankle instability (CLAI). Magnetic resonance imaging (MRI) is used to assess the morphological changes of ligaments, but the measurement of signal intensity enables quantitative evaluation, which can evaluate the degree of the ligament quality. This study aimed to evaluate the qualitative diagnostic capacity for anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injuries of the signal intensity on MRI., Methods: Thirty-eight and 20 ankles with and without CLAI, respectively, were included. The regions of interest (ROIs) were set in the ATFL, CFL, and tibialis anterior tendon (TAT) on MRI, and the signal intensities were measured. The signal intensities of the ATFL and CFL were corrected using TAT as the signal intensity ratio (SIR). The SIRs of the ATFL and CFL in the control and CLAI groups were compared. The relationship between the SIR of the ATFL and the arthroscopic findings was analyzed. Finally, the SIRs of the CFL in CLAI with and without CFL repair were compared., Results: The mean SIR of the ATFL in the CLAI group (6.1 ± 2.4) was significantly higher than that in the control (2.1 ± 0.4) (P < 0.01). The SIR of the ATFL was associated with the arthroscopic grading. The mean SIR of the CFL in the CLAI groups (4.1 ± 2.5) was significantly higher than that in the control (1.7 ± 0.4) (P < 0.01). The SIR of the CFL in patients with the requirement of the CFL repair (6.2 ± 1.9) was significantly higher than that without the CFL repair (2.1 ± 0.5) (P < 0.05)., Conclusions: The SIR is useful for evaluating the quality of the ATFL and CFL, which enables the decision of the treatment strategy of the CLAI., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Medial malleolar osteotomy has been widely performed for posteromedial osteochondral lesions of the talus (OLT) to expose the lesion. In osteochondral fragment fixation, bioabsorbable pins should be inserted as perpendicular as possible to obtain the rigid fixation. However, the exposure of the lesion may depend on the osteotomy angle, which affects the pin insertion angles. This study aimed to analyze the relationship between pin insertion and osteotomy angles in the medial malleolar osteotomy., Methods: Twenty-four ankles of 23 patients were included. The malleolar bisector angle which was calculated from radiographs and actual osteotomy angles were measured on radiographs, and the pin insertion and osteotomy angles were measured using MRI. The intersection angle was defined by the tangential line of the tibial plafond and medial malleolar articular facet, and the bisector of this angle was defined as the malleolar bisector angle. The relationship between pin insertion and osteotomy angles was analyzed., Results: There was no significant difference between the actual osteotomy (55.7° ± 6.6°) and malleolar bisector angles (57.4° ± 4.3°) on the radiograph. There was a significant correlation between pin insertion and osteotomy angles (rs = 0.601). The pin insertion angle (54.3° ± 5.9°) in the lower actual osteotomy angle than the malleolar bisector angle was smaller than those in the higher actual osteotomy angle (63.4° ± 8.2°)., Conclusions: This study showed the osteotomy angle affected pin insertion angle. The osteotomy angle should not be smaller than the malleolar bisector angle at medial malleolar osteotomy to insert pins as perpendicular as possible for fixation of posteromedial OLTs., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Although arthroscopic anterior talofibular ligament (ATFL) repair for chronic lateral ankle instability (CLAI) has been widely performed, there are several issues such as the efficacy of the isolated ATFL repair for the ATFL and calcaneofibular ligament (CFL) injury and the influence of the poor remnant on the clinical outcomes to be discussed. This study aimed to evaluate clinical outcomes of the arthroscopic ATFL repair with the stepwise decision regarding the requirement of CFL repair and the influence of remnant qualities on clinical outcomes., Methods: Forty-four ankles underwent arthroscopic surgery to repair the lateral ankle ligament for CLAI. After arthroscopic ATFL repair, CFL repair was performed if instability remained. Clinical outcomes including the Karlsson-Peterson (KP) scores, Japanese Society for Surgery of the Foot (JSSF) scale, and the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) were assessed at the final follow-up. ATFL remnants were classified into excellent, moderate, and poor according to the arthroscopic findings, and the clinical outcomes of each remnant group were compared., Results: Twenty-five ankles were required for CFL repair after ATFL repair. K-P score was significantly improved from 66.1 ± 5.3 to 94.8 ± 6.5 points (p < 0.01). JSSF scale was significantly improved from 70.5 ± 4.5 to 95.9 ± 6.0 points (p < 0.01). The SAFE-Q was also significantly improved on all subscales. There were no significant differences in clinical outcomes among excellent, moderate, and poor remnants., Conclusions: Stepwise decision for CFL repair in addition to arthroscopic ATFL repair gave satisfactory clinical outcomes in CLAI regardless of the remnant quality., Competing Interests: Declaration of competing interest None., (Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Lateral ankle ligament repair for chronic lateral ankle instability is common, and arthroscopic repair of the anterior talofibular ligament (ATFL) has been widely performed. However, it is desirable to repair of calcaneofibular ligament (CFL) combined with arthroscopic ATFL repair to obtain good long term clinical outcomes. Repairing CFL through small skin incision, there is the possibility to interfere with ATFL and CFL anchors because of close attachment of ATFL and CFL at fibula. The purpose of this study is to determine the safety anchor insertion angles for ATFL and CFL on CT images and to achieve ATFL and CFL repair with minimally invasive technique., Methods: Fifty ankles in 50 patients were included in this study. On a sagittal CT image, the anchor drill hole angles for ATFL and CFL were measured to avoid interference with these anchors. Then, arthroscopic ATFL repair combined with CFL repair was performed on 15 patients according to the safety insertion angles obtained by CT. CFL repair was performed through 1.5 cm length of accessory anterolateral portal. Clinical outcome was evaluated using the Japanese Society for the Surgery of the Foot (JSSF) ankle hindfoot scale and the Karlsson score before surgery and at final follow-up., Results: On the CT image, the mean angles between the ATFL drill hole and anterior border of the fibula was 59.4 ± 6.5°, and those between the longitudinal axis of the fibula and ATFL drill hole, and the CFL drill hole were 34.6 ± 5.0°, and 15.1 ± 5.7°, respectively. Postoperative CT after arthroscopic ATFL repair combined with CFL repair showed that no interference with 2 anchors, and JSSF scale and the Karlsson score were significantly improved from preoperative to final follow-up., Conclusions: This study showed how safety ATFL and CFL anchor insertion angles comprise a minimally invasive anatomical repair technique., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Objective: Osteoarthritis (OA) is a progressive joint disorder, with abnormal remodeling of subchondral bone linked to the disruption of cartilage metabolism. Nerves also play an important role in bone remodeling in OA progression, and vasoactive intestinal peptide (VIP), one of the neuropeptides, plays an important role in bone metabolism. The aim of this study was to analyze the expression pattern of VIP in subchondral bone, and its potential as a therapeutic target for OA progression., Design: The pattern of VIP expression in the human tibia was histologically evaluated. The effect of VIP on angiogenesis was investigated using human umbilical vein endothelial cells (HUVECs). Knee OA was induced by the resection of the medial meniscotibial ligament in C57BL/6 mice. A VIP receptor antagonist was intraperitoneally administered postoperatively, and therapeutic effects were analyzed at 4 and 8 weeks., Results: VIP expression in the subchondral bone increased as OA progressed in human tibia. VIP was also expressed in the vascular channels into the cartilage layer. The total length and branch points were significantly increased, due to the VIP receptor agonist in HUVECs. In OA mice, the VIP receptor antagonist could prevent cartilage degeneration and subchondral bone sclerosis. The Osteoarthritis Research Society International score in the VIP receptor antagonist group was significantly lower than in the control group., Conclusion: VIP is involved in the progression of OA through its effect on subchondral bone sclerosis and angiogenesis. Inhibition of VIP signaling has the potential to be a therapeutic target to prevent OA progression., Competing Interests: Declaration of Competing Interest The author(s) declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Lateral thrust is known to be risk factors for knee osteoarthritis progression. Medial meniscus extrusion is also known to be risk factors for knee osteoarthritis progression; moreover, the amount of change in medial meniscus extrusion from non-weight bearing to weight bearing is an important factor for the progression of knee osteoarthritis. This study aimed to investigate the correlation between lateral thrust and the change in medial meniscus extrusion., Methods: In total, 44 knees from 44 patients (mean age, 68.9 years) with knee osteoarthritis were divided into two groups according to the Kellgren-Lawrence grade: early-stage osteoarthritis (Kellgren-Lawrence = 2) and severe osteoarthritis (Kellgren-Lawrence = 3 or 4). The lateral thrust during gait, represented as the lateral acceleration peak immediately after heel strike, was recorded by an inertial sensor. The amount of change in medial meniscus extrusion, which was the difference between weight-bearing (unipedal standing) and non-weight-bearing (supine) conditions, was evaluated using ultrasonography., Results: The mean value of the lateral acceleration peak in the severe osteoarthritis group was higher than that of the early-stage osteoarthritis group (p < 0.05). The non-weight-bearing and weight-bearing medial meniscus extrusion in the severe OA group were significantly higher than those of the early-stage osteoarthritis group (p < 0.001). However, the amount of change in medial meniscus extrusion in severe osteoarthritis group was significantly lower than in the early-stage osteoarthritis group (p < 0.05). The amount of change in medial meniscus extrusion showed a significant correlation with the lateral acceleration peak in the early-stage osteoarthritis group (r = 0.56, p < 0.001). On the other hand, there was no significant correlation in the severe osteoarthritis group., Conclusion: The lateral thrust shows a positive correlation with the amount of change in medial meniscus extrusion by weight bearing in patients with early-stage knee osteoarthritis., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Large differences in tibial tubercle-posterior cruciate ligament (TT-PCL) distance were described in several reports between countries, suggesting that abnormal TT-PCL distance is variable due to individual patient size. This study aimed to clarify the relationship between TT-PCL distance and patient size, and to determine a method for describing individualized TT lateralization., Methods: We analyzed 41 patients with recurrent patellar dislocation (RPD) and 41 age-matched patients without patellar instability who underwent primary anterior cruciate ligament reconstruction (control). TT-PCL distance and tibia width (TW) were measured based on preoperative T2-weighted magnetic resonance imaging. Then, TT-PCL distance was standardized based on TW (TT-PCL ratio), and TT-PCL distance and ratio were compared between groups. Correlations were investigated among TT-PCL distance, TT-PCL ratio and each measurement (patient height, weight, TW)., Results: Strong positive correlations were observed between TW and patient height, and weak or moderate positive correlations were found between TT-PCL distance and each parameter. The mean TT-PCL distance was 21.2 and 20.6 mm (P = .39), while the mean TT-PCL ratio was 31.6% and 29.0% (P = .0093) in the RPD and control groups, respectively. The TT-PCL ratio was <34% in 39 of 41 knees (95.1%) in the control group. No correlation was indicated between the TT-PCL ratio and patient size., Conclusions: Our findings demonstrate that the TT-PCL ratio is not affected by patient size, although the TT-PCL distance is associated with knee size and patient height. The TT-PCL ratio could be an important index for identifying patients for whom distal realignment surgery should be considered., Competing Interests: Declaration of competing interest All authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Arthroscopic ankle arthrodesis (AAA) is minimally invasive surgery, whereby percutaneous screw fixation is used through the medial aspect of the distal tibia to fusion the ankle, but it carries the risk of the saphenous vein and nerve injuries. The near-infrared (NIR) vascular imaging system, the VeinViewer ® Flex, projects an image of the vein onto the skin, and the visualization of the vein may reduce the vein and nerve injuries. The purpose of this study is to investigate the risk of the saphenous vein injury by the percutaneous screw insertion during AAA, and to evaluate the effectiveness of the NIR vascular imaging system in the reduction of the saphenous vein injury., Methods: Ten patients with the ankle osteoarthritis underwent AAA. Three screw insertion sites (proximal as number 1, anterior distal as number 2, and posterior distal as number 3) were marked and then the vein was depicted on the medial malleolus using the VeinViewer ® Flex. The distance between the screw insertion sites and the closest vein was measured. Additionally, the pattern of the vein course on the medial aspect of the distal tibia was investigated in 32 ankles using the VeinViewer ® Flex., Results: The distance of number 1, 2, and 3 from the vein was 2.4 ± 1.4 mm (range from 0 to 5 mm), 6.3 ± 6.6 mm (range from 0 to 20 mm) and 3.5 ± 3.1 mm (range from 0 to 11 mm) respectively. In anterior screw insertion site, 3 of 10 cases showed just on the vein. The veins were observed at the anterior region from the center axis of the tibia more than 75% of ankles which was suspected as the greater saphenous vein with closely running of the saphenous nerve, but also other regions had the crossing vein., Conclusions: Percutaneous screw fixation during AAA runs the risk of causing the saphenous structure injury. The NIR light imaging system is beneficial in reducing the complications of saphenous structure damage in AAA., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Patients with discoid lateral meniscus (DLM) are prone to meniscal injuries related to its shape and abnormal mobility. The anatomical joint inclination of the proximal tibiofibular joint (PTFJ) can also affect joint movement in knee motion. However, an association between PTFJ morphology and DLM remains unclear. The purpose of this study was to investigate the morphology of the PTFJ on MRI and how this differs between patients with and without DLM., Materials and Methods: Fifty-eight patients with DLM and 58 age-matched controls (normal meniscus) were included in this study. Slices from preoperative MRI sagittal images that clearly showed the PTFJ were used for measurements. The angle between the PTFJ and the perpendicular line of the fibula axis was measured as the inclination angle, and patients were classified as horizontal-type (<20°) or oblique-type (>20°). The inclination angle was also compared among patients with open and closed epiphysis in both groups to assess the effect of age., Results: Patients in the horizontal-type PTFJ group frequently had DLM. Before epiphyseal closure, most patients had a horizontal-type PTFJ, with or without DLM. However, in older patients with a closed epiphysis, most with a normal meniscus had an oblique-type PTFJ, and those with DLM retained the horizontal-type joint., Conclusion: The horizontal-type PTFJ was significantly associated with DLM, and patients with DLM tended to retain a horizontal-type PTFJ after epiphyseal closure. In contrast, in patients with a normal meniscus, the PTFJ may change from a horizontal-type to an oblique-type PTFJ in line with bone maturity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Osteochondral lesions of the talus (OLT) are recognized as being commonly associated with trauma. However, the etiology of OLT remains unclear. In the case of a posteromedial lesion of OLT (medial OLT), the deep layer of the deltoid ligament is located close to the medial OLT, and this relationship between a medial lesion and deltoid ligament could be a risk factor for medial OLT. The purpose of this study is to investigate the unique anatomic feature of the deep deltoid attachment to the talus in patients with medial OLT compared with patients with non-medial OLT., Methods: Forty ankles with medial OLT and 40 ankles without medial OLT were retrospectively reviewed in this study. On the coronal images of MRI, the attachment of deltoid ligament was measured. The continuity of the osteochondral fragment and its bed was evaluated on MRI and arthroscopic findings., Results: Coronal MRI images showed that the attachment of the deep deltoid ligament to the medial OLT was broader and located more proximally than in non-medial OLT. The continuity of fibers from the insertion site of deltoid ligament to the talus to the osteochondral fragment was observed (76.7%). In the arthroscopic findings, the osteochondral fragment was obviously connected to the talus at the medial site in 85.2% of feet., Conclusions: The location of the deep deltoid ligament attachment to the medial OLT was more proximal and there was the possibility of these anatomic feature might contribute to the pathogenesis of medial OLT., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Ankle arthroscopy is a minimally invasive technique for ankle joint treatment. However, injury to the intermediate dorsal cutaneous nerve (IDCN) and the medial dorsal cutaneous nerve (MDCN) is a common complication during anterior portal placement. To prevent injuries, methods such as palpating the nerves topographically and marking the nerves by transilluminating the skin with an arthroscope have been proposed. Easier and more definitive methods of identifying the IDCN and MDCN should result in a reduction of complications. Recently, a vein imaging system was developed that projects images of subcutaneous vasculature directly onto the skin with the use of near-infrared (NIR) light. Because anatomic studies have shown that superficial veins accompany the IDCN and MDCN, protecting the subcutaneous veins could lower the risk of nerve injury. We introduce our technique for the creation of an ankle arthroscopic portal using an NIR imaging system, which displays the vein image on the skin, to prevent injury to the superficial veins and, consequently, reduce IDCN and MDCN injuries. This is the first technical report on the prevention of vein and nerve injuries using an NIR imaging system. Our technique for avoiding vein injury using a peripheral vein illumination device during anterior portal placement in ankle arthroscopy could lower the risk of complications.

Background: A high incidence of dorsomedial cutaneous nerve (DMCN) damage in hallux valgus surgery has been reported. Identification of the vein around 1st metatarsal head is reported to be helpful to reduce the DMCN damage during surgery. The near-infrared (NIR) vascular imaging system, the VeinViewer ® Flex, projects the vein onto the skin. The purpose of this study was to investigate the difference of the vein course between normal and hallux valgus foot using the VeinViewer ® Flex, and to validate that the DMCN was accompanied with its vein., Methods: Twenty-seven feet with the hallux valgus and 27 feet in healthy subjects were included. The vein was projected onto the skin at the metatarsal head by the VeinViewer ® Flex. The distance between the vein and the mid-line of the metatarsal head was measured. The correlation of the distance and hallux valgus angle or 1-2 intermetatarsal angle (IMA) was analyzed. The vein depicted by the VeinViewer ® Flex and operative findings was compared in 4 patients during surgery., Results: The vein in the hallux valgus patients shifted toward the dorsolateral side on the metatarsal bone head compared to that in healthy subjects. The distance from the midline of the 1st metatarsal bone to the vein in the hallux valgus (12.1 mm) was significantly higher than that in healthy subjects (2.7 mm) (p < 0.05). There was a significant correlation between the shift of the vein course toward dorsolateral and IMA. Surgical exploration revealed that the vein depicted by VeinViewer ® Flex could be easily identified and the nerve was along with this vein in all 4 surgical cases., Conclusions: The vein in the hallux valgus patients shifted toward the dorsolateral on the metatarsal bone and it could be a landmark to identify DMCN. The NIR vascular imaging system would be useful to reduce the risk of nerve damage in great toe surgery., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: It is difficult to achieve bone union in case of non-union with non-invasive techniques. MicroRNAs (miRNAs) are short, non-coding RNAs that act as repressors of gene expression at the level of post-transcriptional regulation. This study focuses on microRNA (miR)-222 as it is known to be a negative modulator of angiogenesis, an essential component of fracture healing. The purpose of this study was to analyze the effects of miR-222 on osteogenic and chondrogenic differentiation in human mesenchymal stromal cell (MSC)s in vitro, and to determine whether local administration of miR-222 inhibitor into the fracture site could achieve bone union in vivo., Method: miR-222 expression in human bone marrow mesenchymal stem cells (hMSCs), and osteogenic differentiation in hMSCs, were investigated. The gain or loss of miR-222 function was examined, in order to assess the effects of miR-222 on osteogenic and chondrogenic differentiation in hMSCs. A femoral transverse fracture was completed in rats, and the periosteum at the fracture site was cauterized. Then, either an miR-222 inhibitor or an miR-222 mimics, mixed with atelocollagen, was administered into the fracture site. A non-functional inhibitor negative control was administered to the control group. At 2, 4, 6, and 8 weeks, radiographs of the fractured femurs were obtained. Immunohistochemistry was performed at 2 weeks to evaluate the capillary density. At 8 weeks, micro-computed tomography (μCT) imaging analysis and histological evaluations were performed., Results: The expression of miR-222 significantly decreased as osteogenic differentiation of hMSCs proceeded. Inhibition of miR-222 promoted osteogenic differentiation, and over expression of miR-222 inhibited osteogenic differentiation in hMSCs, which was confirmed by measuring expression of Runx2, collagen type 1A1 (COL1A1), and osteocalcin. Inhibition of miR-222 promoted chondrogenic differentiation in hMSCs, which was confirmed by measuring expression of collagen type II (COL2A1), aggrican, and SOX9. Bone union at the fracture site was achieved in only the groups treated with the miR-222 inhibitor, confirmed by radiographic, μCT and histological evaluation at 8 weeks after administration. Immunohistochemistry showed that capillary density in the miR-222 inhibitor group was significantly higher than that in the control group and in the miR-222 mimics group., Conclusion: Local administration of miR-222 inhibitor can accelerate bone healing by enhancing osteogenesis, chondrogenesis, and angiogenesis in the rat refractory model., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: A symptomatic bipartite patella is rarely seen in athletic adolescents or young adults in daily clinical practice. To date, only a limited number of studies have focused on patellofemoral alignment. The current study revealed a unique patellofemoral alignment in a patient with a symptomatic bipartite patella., Methods: Twelve patients with 12 symptomatic bipartite patellae who underwent arthroscopic vastus lateralis release (VLR) were investigated (10 males and two females, age: 15.7±4.4years). The radiographic data of contralateral intact and affected knees were reviewed retrospectively. From the lateral- and skyline-view imaging, the following parameters were measured: the congruence angle (CA), the lateral patellofemoral angle (LPA), and the Caton-Deschamps index (CDI). As an additional parameter, the bipartite fragment angle (BFA) was evaluated against the main part of the patella in the skyline view., Results: Compared with the contralateral side, the affected patellae were significantly medialized and laterally tilted (CA: P=0.019; LPA: P=0.016), although there was no significant difference in CDI (P=0.877). This patellar malalignment was found to significantly change after VLR (CA: P=0.001; LPA: P=0.003) and the patellar height was significantly lower than in the preoperative condition (P=0.016). In addition, the BFA significantly shifted to a higher degree after operation (P=0.001)., Conclusions: Patients with symptomatic bipartite patellae presented significantly medialized and laterally tilted patellae compared with the contralateral intact side. This malalignment was corrected by VLR, and the alignment of the bipartite fragment was also significantly changed., Level of Evidence: Level IV, case series., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strategy for accelerating the process. Vascular supply plays an important role in primary tendon healing, especially during the early healing phase. MicroRNA (miR)-210 has been reported as being crucial for angiogenesis, which is a key factor of tissue repair. We report herein that local injection of synthetic miR-210 into the injured Achilles tendon of a rat accelerated healing of the tendon., Methods: Achilles tendons were transected and repaired via the Kessler suture technique in Sprague-Dawley rats. Then, double stranded (ds) miR-210 was injected into the repaired sites. The control group was injected with non-functioned dsRNA. At 2, 6 and 12 weeks, histological evaluations were performed. At two and six weeks, mechanical testing and angiogenesis were evaluated. Gene expression analysis using real-time polymerase chain reaction (PCR) and immunohistochemistry were performed at two weeks., Result: At two and six weeks, regular dense collagen tissue in the miR-210 group was observed and the diameter of collagen fiber in the miR-210 group was significantly higher than in the control. At two weeks, the ultimate failure load was significantly higher than in the control group, and expression of VEGF, FGF2 and type I collagen was upregulated. Abundant vessels in the miR-210 group were observed at two weeks, but there was no significant difference in vessel numbers between the two groups at six weeks. At 12 weeks, repaired Achilles tendons in the miR-210 group consisted of parallel and dense fibers, whereas wavy and loose fibers were still observed in the control group., Conclusion: The current study showed that single local injection of synthetic miR-210 promotes Achilles tendon healing in the early phase.

Cells, scaffold, and growth factors are crucially important in regenerative medicine and tissue engineering. Progress in science and technology has enabled development of these three factors, with basic research being applied clinically. In the past decade, we have investigated tissue regeneration in animal models of musculoskeletal disorders by using cells, scaffold, and delivery systems which has been relatively easy to apply and develop in clinical settings. Moreover, microRNA (miRNA), which are important in biological processes and in the pathogenesis of human diseases, have been used in research on regenerative medicine. For the cell source, we focused on mesenchymal stem cells (MSC) and CD34(+) and CD133(+) cells as endothelial progenitor cells for regeneration of musculoskeletal organs. These cells are accessible and safe. For less invasive and more effective therapy, we developed a novel cell-delivery system using magnetic force to accumulate cells at a desired site. Furthermore, administration of synthetic miRNA could enhance tissue regeneration. In our studies, use of these cells combined with a cell-delivery system, miRNA, scaffold, and cytokines has led to effective regeneration of musculoskeletal tissues including cartilage, bone, ligaments, muscle, peripheral nerves, and spinal cord. The current and future objective is more effective and less invasive cell-based therapy with spatial control of transplanted cells by use of an external magnetic force. Analysis of efficiency, safety, and the mechanism of tissue regeneration by cells, scaffold, and miRNA will lead to more promising regenerative medicine, involving the development of a new generation of therapy. This review will focus on our regenerative medicine research, which focuses on clinical application of cells, scaffold, and miRNA.

Background: A magnetic cell targeting system was previously developed to promote the accumulation of transplanted cells in sites of injury in order to effectively treat injured tissues. However, the optimum time of exposure to the magnetic field and the strength of the magnetic force have not yet been clarified. In this study, we investigated the optimum conditions of the magnetic force required to retain iron-labeled human mesenchymal stem cells (hMSCs) at the site of transplantation for muscle repair in a subchronic skeletal muscle injury nude rat model., Methods: First, the optimum strength and time of exposure to the magnetic force for cell retention at the transplantation site were investigated 2 days after cell transplantation (1 × 10(5) cells). Second, the degree of enhancement of muscle repair was investigated at 3 weeks after cell transplantation in the group treated without a magnetic force and two typical magnetic condition groups that exhibited different levels of cell integration in first part of the study., Results: On the basis of the results of the first investigation, it was concluded that a magnetic strength of 1.5 T and 10 min of exposure to the magnetic force were efficient conditions to induce the retention of transplanted cells at the site of transplantation. In the second study, the groups exposed to a 1.5-T magnetic field for 10 min demonstrated significant enhancement of muscle repair, both histologically and electromechanically., Conclusions: This study identified the optimal conditions required to retain transplanted hMSCs at the site of transplantation using a magnetic targeting system. This study also showed that the restoration of subchronic muscle injuries can be enhanced by magnetically labeled hMSCs following the application of a magnetic force.

Background: The coverage of the atelocollagen membrane at the chondral defect after subchondral drilling might improve the beneficial effects for cartilage repair because of the prevention of scattering and accumulation of cells and growth factors from bone marrow within the chondral defect. On the other hand, it might block cells and factors derived from the synovium or cause high pressure in the chondral defect, resulting in prevention of cells and growth factors gushing out from the bone marrow, which leads to disadvantages for cartilage repair., Method: We tested this hypothesis in a 2-mm-diameter chondral defect created in the articular cartilage of the patellar groove in a rat models. Defects were left untreated, or were drilled or drilled and covered with an atelocollagen membrane; healing was evaluated by histology and gene expression analysis using real-time polymerase chain reaction and immunohistochemistry., Results: Membrane coverage induced bone tissue ingrowth into the punched chondral defect. At 1 week, expression of TGFβ, Sox9, Runx2, osteocalcin, Col1a1, and Col2a1 in the drilling group was significantly higher than in the covering group. At 4 weeks, expressions of TGFβ, Runx2, and Col1a1 were all significantly higher in the drilling group, while Sox9, osteocalcin, and Col2a1 were significantly higher in the covering group. Immunohistochemistry demonstrated Sox9, osteocalcin, and type II collagen on the bony reparative tissue in the covering group., Conclusions: These results suggest that the atelocollagen membrane coverage resulted in inhibition of cartilage repair.

Background: There are various indirect signs of a discoid lateral meniscus in radiographs, for example lateral joint space widening, hypoplasia of the LFC, etc. There has, however, been no previous report of the characteristic shape of the lateral femoral condyle (LFC) in patients with osteochondritis dissecans (OCD) accompanied by a discoid lateral meniscus. The purpose of this study was to evaluate the characteristic shape of the LFC in patients with OCD accompanied by a discoid lateral meniscus, and sex differences associated with the shape of the LFC in those patients., Methods: This study included 29 males (31 knees) and 29 females (32 knees) of average age 17.7 years. There were 15 knees in 15 patients that were accompanied by OCD of the LFC (9 males, 9 knees; 6 females, 6 knees; average age 14.9 years; OCD group). There were 48 knees in 43 patients that were not accompanied by OCD of the LFC (20 males, 22 knees; 23 females, 26 knees; average age 17.6 years; non-OCD group). Standardized Rosenberg view radiographs of the knee were obtained for all patients. We evaluated the shape of LFC using the Rosenberg view and measured the condylar prominence ratio of the medial and lateral condyles adjacent to the intercondylar notch, in accordance with Ha's procedure., Results: The OCD group had a significantly larger prominence ratio than the non-OCD group. The prominence ratio for males was significantly larger than that for females., Conclusion: We clearly demonstrated that the prominence ratio in the OCD group was significantly larger than that in the non-OCD group, indicating that the shape of the LFC and OCD in the LFC may be associated with the development of these lesions.

Background: It is desirable to maintain the morphology of the semitendinosus muscle-tendon complex after tendon harvesting for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the effect of knee immobilization on morphological changes in the semitendinosus muscle-tendon complex., Methods: In total, 39 patients who underwent ACL reconstruction with autologous semitendinosus tendons were included in this study. After surgery, the knee was immobilized for 3 days in 1 group of patients (group 1; 24 patients; control group) and for a longer period (10-14 days) in the other group (group 2; 15 patients). Three-dimensional computed tomography (3D CT) examination was performed at 6 and/or 12 months after the surgery for all patients. Morphological changes in the semitendinosus muscle-tendon complex (proximal shift of the semitendinosus muscle-tendon junction, width of the regenerated semitendinosus tendons, re-insertion sites of the regenerated tendons, and rate of semitendinosus tendon regeneration) were evaluated., Results: Successful regeneration of the semitendinosus tendon was confirmed in all patients in group 2. In group 1, 3D CT showed that regeneration of the semitendinosus tendon was unsuccessful in 1 of the 24 patients. The average length of the proximal shift of the semitendinosus muscle-tendon junction was 7.3 ± 2.5 cm in group 1 and 7.2 ± 1.9 cm in group 2. There were no significant differences between the 2 groups with regard to the morphological changes in the semitendinosus muscle-tendon complex., Conclusions: This study showed that the structure of regenerated tendons could be clearly identified in 38 of 39 cases (97.4%) after ACL reconstruction. However, prolonged knee immobilization (10-14 days) could not prevent morphological changes in the semitendinosus muscle-tendon complex.

Background: Aggressive early rehabilitation is recommended after reconstruction of the anterior cruciate ligament (ACL) using a patellar tendon-bone graft. However, rehabilitation after reconstruction of ACL using the multistranded hamstring is controversial. In this study, we compared the clinical results of 3-day immobilization after reconstruction of ACL using the multistranded hamstring, with those of 2-week immobilization prospectively., Methods: A total of 30 consecutive patients with ruptured ACL underwent single-socket ACL reconstruction. 10 male and 5 female patients (mean age of 29.2+/-10.0 years) were prospectively randomized for a 3-day immobilization period, and 6 male and 9 female patients (mean age of 27.3+/-10.9 years) were randomized for a 2-week immobilization period. We measured the anterior laxity with a KT-2000 arthrometer, joint position sense, and thigh muscle strength at 3, 6 and 12 months after surgery., Results and Conclusions: There were no statistically significant differences between the two groups. We concluded that the post-operative 3-day immobilization period is preferable to the longer 2-week period in our rehabilitation program from the viewpoint of psychological load to the patients and the duration of hospitalization after ACL reconstruction using multistranded hamstring tendons.