Hisateru Niki

Purpose Forefoot deformities in rheumatoid arthritis (RA) cause painful plantar callosities and severely impair quality of life. Although resection arthroplasty has historically been the standard surgical treatment, it sacrifices metatarsophalangeal (MTP) joint function. This review describes Combination Metatarsal Osteotomies for Shortening (CMOS), a joint-preserving surgical technique of Japanese origin, and presents its concept, indications, surgical technique, and clinical outcomes. Methods CMOS combines three types of proximal metatarsal shortening osteotomies tailored to the anatomical characteristics of each metatarsal: a modified Lapidus procedure for the first metatarsal, proximal oblique shortening osteotomy for the second to fourth metatarsals, and diaphyseal oblique shortening osteotomy (modified Coughlin procedure) for the fifth metatarsal. Results Proximal shortening osteotomy simultaneously achieves shortening and elevation of the metatarsal head, relieving soft tissue tension around the MTP joint and facilitating joint reduction without extensive soft tissue release. Long-term follow-up studies have confirmed maintenance of correction and preservation of joint function. A review of the international literature reveals that the vast majority of publications on joint-preserving surgery for RA forefoot deformity originate from Japan, with the corresponding author’s 2010 publication serving as the foundation for subsequent research by numerous Japanese investigators. Conclusion CMOS is an effective joint-preserving procedure that restores both function and appearance in RA patients with forefoot deformity, and represents a central technique in a field where Japan continues to lead the world.

This article provides an overview of the classification of progressive collapsing foot deformity (PCFD), along with a mnemonic aid for memorization. It also outlines the classification of spring ligament insufficiency, the surgical procedure selection process for stage 1 PCFD, and a detailed summary of surgical techniques, including key tips and potential pitfalls.The surgical overview covers the following: patient positioning, evaluation of spring ligament insufficiency and procedure selection using tendoscopy, assessment and management timing of gastrocnemius–Achilles tendon contracture, preparation of the calcaneocuboid joint, and medial exposure for flexor digitorum longus tendon (FDLT) transfer. Two novel techniques developed by the author are introduced: corrective repair of the spring ligament (CORRS), a repair method addressing forefoot varus associated with spring ligament damage; and spring ligament reconstruction by remnant posterior tibial tendon (PTT) preservation (SREPP), a reconstruction technique that uses remnant PTT tissue to treat extensive spring ligament ruptures and concurrently correct forefoot varus. The article also offers surgical tips for FDLT transfer, bone grafting, and lateral column lengthening (LCL) via calcaneocuboid distraction arthrodesis (CCDA), with special attention to avoid residual forefoot varus.Correction of midfoot and forefoot varus is emphasized as a crucial element in performing LCL for stage 1 PCFD. CORRS and SREPP are presented as effective adjunctive techniques that enhance the outcomes of CCDA by preventing over-lengthening and residual forefoot varus.

Mechanical stress is known to be a pivotal risk factor in the development of OA. However, the involvement of repetitive compressive loading in mitochondrial dysfunction in chondrocytes remains unclear. The aim of this study was to investigate whether physiologic levels of repetitive mechanical force affect the regulation of energy metabolism and activities of mitochondrial function regulators, sirtuin 1 and nicotinamide adenine dinucleotide (NAD) in chondrocytes, and to clarify any correlation with chondrocyte catabolic activity. Repetitive physiological mechanical stress was applied in a 3D chondrocyte-collagen scaffold construct, and the 3D cultured tissues were collected at different time points by collagenase treatment to collect cellular proteins. Changes in chondrocyte activity (cell proliferation, MMP-13 production), energy metabolism regulator levels (sirtuin 1), mitochondrial function (ATP production, NAD level), and the expression level of the osteogenic and hypertrophic chondrogenic transcription factor, runt-related transcription factor 2 (Runx2), were measured. Treatment with repetitive compressive loading resulted in no significant change in the cell viability of chondrocytes. In the repetitive mechanical loading group, there were statistically significant increases in MMP-13 production and expression of both sirtuin 1 and Runx2 in chondrocytes relative to the non-loading control group. Furthermore, ATP production and NAD activity in mitochondria decreased in the repetitive mechanical loading group. Our present study reveals that in chondrocytes, repetitive compressive loading accelerated sirtuin activation, which requires and consumes NAD within mitochondria, leading to a decrease of NAD and ultimately in reduced mitochondrial ATP production. Additionally, since sirtuin 1 is known to positively regulate Runx2 activity in chondrocytes, the activation of sirtuin 1 by repetitive load stimulation may induce an increase in the expression of Runx2, which promotes the expression of MMP-13, and subsequently enhances MMP-13 production. Our findings indicate that repetitive compression loading-mediated mitochondrial dysfunction plays a pivotal role in the progression of OA, primarily by driving the downregulation of ATP production and promoting the expression of the matrix-degrading enzyme MMP-13.

Palbociclib, a dual CDK4/6 kinase inhibitor used for breast cancer, has been explored as a treatment option for rheumatoid arthritis (RA). Preclinical studies have reported palbociclib-induced myelosuppression, but no such effects have been observed in Cdk4 or Cdk6 single-deficient mice. Synoviocyte proliferation-associated in collagen-induced arthritis 1/serum amyloid A-like 1 (SPACIA1/SAAL1) is involved in G1 phase progression. Given that SPACIA1/SAAL1 upregulates CDK6 (but not CDK4) expression, we aimed to determine whether suppressing CDK6 expression alone could prevent synovial hyperplasia without myelosuppression. The effects of CDK6 expression on TNF-α-induced rheumatoid arthritis synovial fibroblast (RASF) proliferation and synovial hyperplasia in collagen-induced arthritis (CIA) mice were investigated by modulating the transcriptional level with a CDK6 expression inhibitor (indole-3-carbinol), CDK6 small interfering RNA (siRNA), and Cdk6-deficient mice. Indole-3-carbinol or CDK6 siRNA inhibited TNF-α-induced RASF proliferation without suppressing CDK4 expression and reduced retinoblastoma protein phosphorylation. In CIA mice, indole-3-carbinol did not cause myelosuppression, considerably delayed CIA onset and progression, and reduced arthritis severity. Cdk6-deficient mice showed similar improvements in CIA pathogenesis but had lower serum anti-type II collagen IgG levels. Notably, synovial hyperplasia was not observed in Cdk6-deficient mice. CIA-synovial hyperplasia depends on CDK6, but not CDK4, expression.

Background and Objectives: Total hip arthroplasty (THA) requires accurate implant placement to ensure optimal outcomes. In this study, the AR Hip navigation system, an imageless portable navigation tool using augmented reality (AR), was evaluated for measuring radiographic inclination (RI), anteversion (RA), leg lengthening (LL), and offset (OS) changes in supine and lateral decubitus THA. Notably, this is the first report to assess the accuracy of LL and OS measurements using AR technology. Methods: We analyzed 48 hips from primary THA patients: 17 in the supine (S) group and 31 in the lateral (L) group. RI, RA, LL, and OS were measured intraoperatively using AR Hip and postoperatively using Zed Hip 3D software (Version 18.0.0.0). The absolute errors and outlier rates (≥5° for RI/RA and ≥5 mm for LL/OS) were compared between groups. Results: The mean intraoperative RI values with AR Hip were 40.1 ± 0.6° (S), 40.2 ± 1.2° (L), and 40.1 ± 1.0° (total), while the postoperative RI values with Zed Hip were 39.7 ± 2.9° (S), 39.5 ± 2.5° (L), and 39.6 ± 2.6° (total). The absolute errors were 1.8 ± 1.7° (total), with no significant group differences (p = 0.957). For RA, the errors were 2.0 ± 1.2° (total) (p = 0.771). The LL errors were 2.3 ± 2.2 mm (total) (p = 0.271), and the OS errors were 3.5 ± 2.8 mm (total) (p = 0.620). The outlier rates for RI were 11.8% (S) and 3.2% (L); for RA, 0% (S) and 3.2% (L); for LL, 29.4% (S) and 6.5% (L) with a significant difference (p = 0.031); and for OS, 23.5% (S) and 25.8% (L). No significant differences were observed for RI, RA, or OS. Conclusions: AR Hip provided accurate measurements of cup orientation, LL, and OS in both supine and lateral THA. Importantly, this study is the first to report the accuracy of LL and OS measurements using AR technology, demonstrating the potential of AR Hip for improving THA precision.

Balance is important in lifesaving competitions. We aimed to investigate the relationship between dynamic balance and physical characteristics and functions in elite lifesavers by measuring the foot muscle cross-sectional area, ankle joint muscle strength, toe grasp strength, plantar superficial sensation, and dynamic balance (Y-balance test). In this observational study, we measured the foot muscle cross-sectional area, ankle dorsiflexion, plantar flexion, external flexion, isometric muscle strength, toe grasp strength, and superficial foot sensation of 15 adult lifesavers (12 males). The results show that toe grasp strength and ankle plantar flexion isometric muscle strength are particularly important for the dynamic balance of elite lifesavers working on sandy surfaces. Sand training improves intrinsic muscle strength and dynamic balance function. However, high training intensity may reduce plantar surface sensation; this needs to be verified through sand training interventions in the future.

Balance is important in lifesaving competitions. We aimed to investigate the relationship between dynamic balance and physical function in elite lifesavers by measuring the foot muscle cross-sectional area, ankle joint muscle strength, toe grasp strength, plantar superficial sensation, and dynamic balance. In this observational study, we measured the foot muscle cross-sectional area, ankle dorsiflexion, plantar flexion, external flexion, isometric muscle strength, toe grasp strength, and superficial foot sensation of 15 adult lifesavers (12 males). The results showed that toe grasp strength and ankle plantar flexion isometric muscle strength are particularly important for the dynamic balance function of elite lifesavers working on sandy surfaces. Sand training improves intrinsic muscle training and dynamic balance function. However, high training intensity may cause a decrease in plantar surface sensation, which needs to be verified with sand training interventions in the future.

The purpose of this study was to evaluate robotic-assisted cortical bone trajectory (CBT) screw placement. Early, middle, and late phases of robotic-assisted CBT screw placement were compared for accuracy and screw insertion time by comparing time and accuracy in every phase. A retrospective review was conducted on the initial 40 patients who underwent spinal fusion using CBT screws in one institution from September 2021 to September 2022 utilizing a spine surgery robot system (Mazor X Stealth Edition, Medtronic Inc., Dublin, Ireland). The inclusion criterion was one- or two-level posterior lumbar interbody fusion (PLIF). Exclusion criteria were 1) patients who underwent posterior-lateral fusion in other segments, 2) patients who underwent additional decompression in other segments, 3) patients who underwent reoperation, and 4) patients with spondylolysis. The deviation of the CBT screw was evaluated on computed tomography (CT) one week after surgery using the Gertzbein-Robbins grade system. The rate of Grade A was considered the perfect accuracy rate, and the rate of penetration of 2 mm or more (Grades C, D, and E) was calculated as the deviation rate. To assess the learning curve, patients were divided into three groups. The first 10 cases were in the early phase group, the subsequent 10 cases were in the middle phase group, and the last 10 cases were in the late phase group. We compared the perfect accuracy rate, deviation rate, operative time, operative time per segment, intraoperative blood loss, registration time, and screw insertion time among the three groups. Thirty patients met the criteria. Overall, the perfect accuracy (Grade A) rate of the screw was 95.3% and the deviation rate was 1.4%. The perfect accuracy rate was 90.4% in the early phase, 95.5% in the middle phase, and 100% in the late phase. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase, and there was no statistically significant difference between the three groups. Among the three groups, the operative time, the operative time per segment, the intraoperative blood loss, and the registration time were not significantly different. There was no significant difference in the screw insertion time among the three groups, but it decreased with experience (early phase: 156.9 ± 54.7 sec, middle phase: 139.9 ± 41.6 sec, and late phase: 106.4 ± 39.9 sec, p=0.060). The screw insertion time of the late phase tended to be shorter than that of the early phase (p=0.052). The deviation rate of robotic-assisted CBT screw placement with one- or two-level PLIF was 1.4%, which was highly accurate. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase. Although the deviation rate was low even in the early period, the screw insertion time in the early 10 cases tended to be longer than that in the late 10 cases. After passing the experience of 10 cases, this study concluded that robotic-assisted CBT screw placement was proficient.

Category: Ankle Arthritis; Ankle Introduction/Purpose: In varus-type osteoarthritis of the ankle (VAOA), it is known that the subtalar joint compensates in valgus/eversion for the malalignment of the tibiotalar joint. However, previous studies were mainly based on X-ray measurements and did not take into account peri-talar changes that extend to the subtalar and Chopart joints. Furthermore, the effect on peritalar compensation when tibio-talar arthrodesis is performed is still unclear. Distance Mapping (DM) is a technology that can produce a 3D point-to-point distance map of joint interactions from cone beam weight bearing CT (WBCT) images. The purpose of this study was to quantify the peri-talar changes that occur when the tibiotalar joint is fused. We hypothesized that talar varus would improve and that the Chopart/Subtalar joint complex would present compensatory varus/inversion. Methods: The subjects were 14 patients (15 feet) who underwent arthrodesis for VAOA at our institution. The average postoperative follow-up period was 6.6 months. Foot alignment (Foot Ankle Offset (FAO)) was measured from WBCT datasets pre and postoperatively. The pre to post op shift vectors of the weighted distance maps center points were measured for the tibiotalar, subtalar, calcaneocuboid and talonavicular joints. Statistical analysis was performed by paired T-test, and the significance level set at p<0.05. Results: FAO improved significantly from preoperative -12.9 +-7.4 % to postoperative -6.4 +-3.9 %. The DM vectors were 4.9 +-2.8 mm (lateral direction) for the tibiotalar joint, 0.86 +-0.93 mm (posterior) for the subtalar joint and 4.9 +-2.6 mm (plantar- medial) for the talonavicular joint. Conclusion: The main finding in this study was that foot alignment was improved following tibiotalar arthrodesis with peritalar compensation, more so in the talonavicular than in the subtalar joint and not in the calcaneocuboid joint. The limitations of this study include the small number of cases and the short postoperative follow-up. Our results suggest that the flexibility of the talonavicular joint may be necessary when arthrodesis is performed on VAOA to contribute to the alignment correction. If it is not the case, TAR could be considered an alternative.