Characteristics of the synovial microenvironment and synovial mesenchymal stem cells with hip osteoarthritis of different bone morphologies

BACKGROUND

Variations in bone morphology in patients with hip osteoarthritis (HOA) can be broadly categorized into three types: atrophic, normotrophic, and hypertrophic. Despite the investigations examining clinical elements, such as bone morphology, pain, and range of motion, our understanding of the pathogenesis of HOA remains limited. Previous studies have suggested that osteophytes typically originate at the interface of the joint cartilage, periosteum, and synovium, potentially implicating synovial mesenchymal stem cells (SMSCs) in the process. This study aimed to investigate the potential factors that drive the development of bone morphological features in HOA by investigating the characteristics of the synovium, differentiation potential of SMSCs, and composition of synovial fluid in different types of HOA.

METHODS

Synovial tissue and fluid were collected from 30 patients who underwent total hip arthroplasty (THA) with the variable bone morphology of HOA patients. RNA sequencing analysis and quantitative reverse transcription-polymerase chain reaction (RT-qPCR) were performed to analyse the genes in the normotrophic and hypertrophic synovial tissue. SMSCs were isolated and cultured from the normotrophic and hypertrophic synovial tissues of each hip joint in accordance with the variable bone morphology of HOA patients. Cell differentiation potential was compared using differentiation and colony-forming unit assays. Cytokine array was performed to analyse the protein expression in the synovial fluid.

RESULTS

In the RNA sequencing analysis, 103 differentially expressed genes (DEGs) were identified, predominantly related to the interleukin 17 (IL-17) signalling pathway. Using a protein-protein interaction (PPI) network, 20 hub genes were identified, including MYC, CXCL8, ATF3, NR4A1, ZC3H12A, NR4A2, FOSB, and FOSL1. Among these hub genes, four belonged to the AP-1 family. There were no significant differences in the tri-lineage differentiation potential and colony-forming capacity of SMSCs. However, RT-qPCR revealed elevated SOX9 expression levels in synovial tissues from the hypertrophic group. The cytokine array demonstrated significantly higher levels of CXCL8, MMP9, and VEGF in the synovial fluid of the hypertrophic group than in the normotrophic group, with CXCL8 and MMP9 being significantly expressed in the hypertrophic synovium.

CONCLUSION

Upregulation of AP-1 family genes in the synovium and increased concentrations of CXCL8, MMP9, and VEGF were detected in the synovial fluid of the hypertrophic group of HOA patients, potentially stimulating the differentiation of SMSCs towards the cartilage and thereby contributing to severe osteophyte formation.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Effect of posterior capsular release on intraoperative joint gap mismatch in the mid-flexion range during posterior-stabilized total knee arthroplasty

INTRODUCTION

Intraoperative mismatch between extension and mid-flexion joint gaps remains a critical issue in posterior-stabilized total knee arthroplasty (PS-TKA). Posterior capsular release has been found to increase the extension joint gap. However, there is still a lack of robust evidence for the effect of posterior capsular release on the mid-flexion joint gap. The purpose of the present study was to quantify the effect of posterior capsular release on the intraoperative joint gap from extension through 45° mid-flexion to flexion and to clarify how this procedure might affect the improvement of gap mismatch in the mid-flexion 45° range.

MATERIALS AND METHODS

In total, 38 consecutive cases of primary PS-TKA were reviewed. The center, medial, and lateral component gaps from extension to flexion were measured with a tensor device before and after posterior capsular release. The minimal detectable change for joint gap measurement was calculated using two methods, error variance and intra-observer intraclass correlation coefficients. Pre- and post-release joint gap differences were assessed using the paired t-test.

RESULTS

Minimal detectable change was found to be 0.59 mm. At 0° and 10° of flexion, the post-release center, medial, and lateral component gaps were significantly greater than at pre-release. At 45° and 90° and maximum flexion, there were no joint gap differences exceeding the minimal detectable change. The joint gap mismatches between 0° and 10°, and 45°, 90° and maximum flexion were significantly smaller at post-release than those at pre-release with the change values exceeding the minimal detectable change (P < 0.05).

CONCLUSION

Posterior capsular release significantly decreased both joint gap mismatch between extension and 45° mid-flexion, and extension and flexion, showing clinical usefulness in PS-TKA.

Analysis of survivorship following periacetabular osteotomy for hip dysplasia based on three-dimensional acetabular coverage

Periacetabular osteotomy (PAO) is an established procedure for correcting acetabular coverage and preventing osteoarthritis progression in hip dysplasia. However, it is unclear how acetabular coverage changes three-dimensionally after PAO and how it affects survival. Therefore, this study aimed to investigate the change in three-dimensional acetabular coverage preoperatively and postoperatively and identify demographic, clinical and radiographic factors associated with conversion to total hip arthroplasty (THA) and radiographic osteoarthritis progression after PAO. We retrospectively reviewed 46 consecutive patients (66 hips) who underwent PAO, using preoperative and postoperative radiographs and pelvic computed tomography (CT). Three-dimensional acetabular coverage based on CT data was investigated. Kaplan-Meier survival analysis was performed, and hazard ratios were calculated using univariate Cox regression models to identify the risk factors associated with conversion to THA and radiographic osteoarthritis progression after PAO as the endpoints. Radiographic osteoarthritis progression was defined as a minimum joint space of <2.0 mm. The mean follow-up was 10.7 years. Post-PAO, acetabular coverage gradually increased from the anterosuperior to the superior to the posterosuperior direction. The survival rate after PAO was 98.0% at 10 years. Less postoperative superior acetabular coverage, with a hazard ratio of 0.93, was significantly associated with conversion to THA and radiographic osteoarthritis progression after PAO (P = 0.03). In this study, poor superior acetabular coverage after PAO was a significant risk factor for conversion to THA and radiographic progression of osteoarthritis. Therefore, surgeons should attempt to prioritize the correction of the superior acetabular coverage when performing PAO.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Low central sensitisation inventory score is associated with better post-operative outcomes of osteotomy around the knee

PURPOSE

The purpose of this study was to investigate the potential association between central sensitisation inventory (CSI) scores and post-operative patient-reported outcomes (PROs) in patients underwent osteotomy around the knee (OAK), with a CSI cut-off score specific for knee osteoarthritis.

METHODS

CSI scores were collected from 173 patients who underwent OAK, along with their knee injury and osteoarthritis outcome score (KOOS) and pain numeric rating scale (NRS) scores. Patients were divided into high-CSI score group and low-CSI score group with a cut-off score of 17. Multivariate linear regression was performed to test the association between CSI scores and post-operative outcomes. Pre-surgery KOOS and NRS scores and the rate of attainment of minimal clinically important difference (MCID) of KOOS scores was analysed as secondary outcomes.

RESULTS

Low-CSI score group had significantly higher post-operative KOOS scores and lower pain NRS scores compared to the high-CSI score group (< p = 0.01) after adjusting for confounding factors. For pre-operative scores, only the KOOS-Symptom score was significantly different between the groups (64.7 ± 20.1 when CSI < 17 vs.55.1 ± 19.7 when CSI ≥ 17; p = 0.008). The low-CSI score group had significantly higher MCID achievement rates of KOOS-Pain, Symptom, and ADL than the high-CSI score group (86% vs. 68%; 74% vs. 55%; 86% vs. 67%, respectively; P < 0.05).

CONCLUSIONS

This study established an association between post-operative CSI scores ≥ 17 and poorer outcomes following OAK, highlighting the potential value of the CSI in identifying patients in need of more comprehensive peri-operative pain management.

LEVEL OF EVIDENCE

Level III. Retrospective comparative study.

Effect of posteromedial vertical capsulotomy with medial collateral ligament liberation on intraoperative medial component gap mismatch between extension and mid-flexion during total knee arthroplasty

PURPOSE

The aim of this study was to quantify the effect of posteromedial vertical capsulotomy on intraoperative component gaps and angles from extension through mid-flexion to flexion during total knee arthroplasty (TKA).

METHODS

In the present study, 47 cases of primary posterior-stabilized TKA using the measured resection technique for varus knee osteoarthritis (hip-knee-ankle angles < 0°) were reviewed. Component gaps and angles at 0°, 10°, 45°, 90°, and maximum flexion were measured intraoperatively, before and after posteromedial vertical capsulotomy. Differences in pre- and post-posteromedial vertical capsulotomy medial and lateral component gaps and angles and medial component gap mismatches among knee flexion angles were assessed using the Wilcoxon signed rank test for two paired samples.

RESULTS

The medial component gaps at 0° and 10° of flexion of post-posteromedial vertical capsulotomy were significantly greater, exceeding the minimal detectable change, than those pre posteromedial vertical capsulotomy (change of the gap after the procedure at 0° of flexion was 0.7 ± 0.7 mm and at 10° of flexion was 0.8 ± 0.8 mm; all P values < 0.05). The medial component gap mismatches between both 0° and 10°, and 45°, 90°, and maximum flexion were significantly smaller post posteromedial vertical capsulotomy than pre posteromedial vertical capsulotomy, with the values of the change exceeding the minimal detectable change (change of the gap mismatch after the procedure: knee flexion at 0° and 45° was - 0.6 ± 0.9 [mm], at 0° and 90° was 0.7 ± 1.0, at 0° and maximum flexion was - 0.6 ± 1.2, at 10° and 45° was - 0.7 ± 0.9, at 10° and 90° was - 0.8 ± 0.9, at 10° and maximum flexion was - 0.7 ± 1.1; all P values < 0.05).

CONCLUSIONS

Posteromedial vertical capsulotomy increased the medial component gaps during knee extension but not during mid-flexion or full flexion during posterior-stabilized TKA. Posteromedial vertical capsulotomy improved mild medial component gap mismatch between extension and mid-flexion and full flexion during posterior-stabilized TKA. Surgeons can consider posteromedial vertical capsulotomy when there is intraoperative constriction of the medial component gap during extension in patients undergoing posterior-stabilized TKA.

Mid-term clinical outcomes of a posterior stabilized total knee prosthesis for Japanese patients: A minimum follow-up of 5 years

BACKGROUND

A high-flexion posterior-stabilized total knee prosthesis has been developed for the Asian population. The component design was based on computed tomography images of Japanese osteoarthritic knees. The femoral component is composed of zirconia ceramics, which exhibit low friction and high durability. The present study aimed to evaluate the mid-term clinical outcomes of this implant.

METHODS

This study included 334 knees of 210 patients who underwent primary total knee arthroplasty with this implant at our hospital between October 2010 and December 2014. The patients comprised 28 men and 172 women with an average age of 73 years. The average follow-up period was 5.9 years, and the follow-up rate was 71.1%. Clinical outcomes were assessed using the Knee Society scoring system, 2011 Knee Society questionnaire, and Knee Injury and Osteoarthritis Outcome Score. Kaplan-Meier survivorship analysis was performed to determine the cumulative prosthesis survival rate.

RESULTS

In terms of clinical outcomes at the final follow-up, the average ranges of motion were -2.0 in extension and 126.7 in flexion. The Knee Society knee and function scores were 94.2% and 72.6%, respectively. With revision surgery or radiographic failure for any reason as the endpoint, the survival rates at 5 and 9 years were 98.2% and 95.5%, respectively. The most common reason for revision surgery or radiological failure was aseptic loosening.

CONCLUSIONS

Despite several revision cases mainly due to aseptic loosening, the present study found that this new high-flexion posterior-stabilized total knee arthroplasty prosthesis design showed comparable results for Asian populations with other PS prosthesis.

LEVELS OF EVIDENCE

Level Ⅱ (Prospective cohort study).

Hyaluronic acid sheet transplantation attenuates infrapatellar fat pad fibrosis and pain in a rat arthritis model

Fibrosis of the infrapatellar fat pad (IFP) occurs after knee joint surgery or during knee osteoarthritis (KOA) and causes persistent pain and limited mobility. Previous studies demonstrated that treating IFP fibrosis alleviated pain in animal models. In this study, we examined the effects of hyaluronic acid (HA) sheet transplantation on IFP fibrosis and articular cartilage degeneration in a monoiodoacetic acid (MIA) rat arthritis model (95 male rats). Rats received bilateral intra-articular MIA injections (1.0 mg/30 μL) and underwent surgery 4 days later. HA sheets were transplanted on the right knee of each rat (HA group), with the left knee receiving sham surgery (sham group). Incapacitance tests were performed at multiple time points up to 28 days after MIA injection. Macroscopic, histological, and immunohistochemical analyzes were performed 14 and 28 days after injection. The concentrations of HA and interleukin-1β (IL-1β) in the synovial fluid were measured using ELISA. Transplantation of HA sheets could alleviate persistent pain 10-28 days after injection. The HA sheets inhibited articular cartilage degeneration at 14 days. Fibrosis and the invasion of calcitonin gene-related peptide-positive nerve fiber endings in the IFP were inhibited at both 14 and 28 days. Moreover, the HA sheets remained histologically until 10 days after transplantation. The concentration of HA reached its peak on Day 10 after transplantation; the concentration of IL-1β in the sham group was significantly higher than that in the HA group on Day 7. Therefore, HA sheets could be a promising option to treat IFP fibrosis occurring in KOA and after knee joint surgery.

Limited medial posterior capsular release increases the intraoperative medial component gap while maintaining the joint varus angle at extension in posterior-stabilized total knee arthroplasty

PURPOSE

There is a lack of robust evidence for the magnitude of the effects of posterior capsular release (PCR) on intraoperative component gaps during total knee arthroplasty (TKA). The purpose of the present study was to quantify and compare the effects of partial versus full PCR on the intraoperative component gaps at various degrees of flexion during posterior-stabilized TKA.

METHODS

Full PCR was performed on 39 consecutive cases (full PCR group), and partial PCR (the medial side up to and including the intercondylar notch) was performed on the subsequent 39 consecutive cases (partial PCR group) during posterior-stabilized TKA using the measured resection technique for varus knee osteoarthritis. Medial component gaps and varus angles at 0°, 10°, 45°, 90°, and a maximum of flexion were measured with a tensor device before and after the PCR. Differences between the two groups in post-release medial component gap increase and post-release joint varus angle increase were assessed using a t test. Pre- to post-release medial component gaps and joint varus angles in each group were compared using a paired samples t test.

RESULTS

In both groups at 0° and 10° of flexion, post-release medial compartment gaps were significantly greater than pre-release gaps (all P < 0.001). At 45°, 90° and maximum flexion, the medial compartment gap increase did not exceed the minimal detectable change in either group. At 0° and 10° of flexion, there was no significant difference in post-release medial compartment gap change between the two groups. In the full PCR group, post-release joint varus angles at 0° of flexion were significantly greater than pre-release angles (P < 0.001), while there was no significant pre- and post-release difference in the partial PCR group. The change in post-release joint varus angles at 0° of flexion was significantly greater in the full PCR group than in the partial PCR group.

CONCLUSION

Both full and partial PCR show similar clinical usefulness for increasing the medial component gap at extension and reducing component gap mismatch. A partial PCR can be used to avoid increasing joint varus angles at 0° of flexion.

LEVEL OF EVIDENCE

Level 2 (prospective comparative study).

Older Age, Poor Preoperative Quadriceps Muscle Strength, and Residual Pain as Risk Factors for Poor Quadriceps Muscle Strength Recovery at 1 Year After ACL Reconstruction: A TMDU MAKS Study of 402 Patients

Background

Poor postoperative quadriceps muscle strength recovery after anterior cruciate ligament reconstruction (ACLR) leads to delayed return to sports and lower patient satisfaction.

Purpose/Hypothesis

The purpose of this study was to examine factors that affect quadriceps muscle strength 1 year after ACLR. It was hypothesized that older age, poor preoperative quadriceps muscle strength, and residual pain would be risk factors for poor quadriceps muscle strength recovery.

Study Design

Case-control study; Level of evidence, 3.

Methods

Included were patients from multiple institutions who underwent primary ACLR using autologous hamstring tendon grafts between August 1, 2013, and March 31, 2018, and who had at least 1 year of follow-up data. Patients with past ligamentous injuries in the affected knee, previous injuries or operations in the contralateral knee, accompanying ligament injuries of grade 2 or 3, or inflammatory or other types of osteoarthritis were excluded. Patients were categorized as having muscle strength ≥80% (good strength recovery) or <80% (poor strength recovery) compared with the contralateral leg at 1 year postoperatively. Multivariate logistic regression analysis was performed to investigate the factors influencing postoperative quadriceps muscle strength. In addition, a categorical analysis was conducted based on factors extracted by the multivariate logistic regression analysis.

Results

A total of 402 patients were included. Multivariate logistic regression analysis revealed that age at surgery (P = .020), preoperative quadriceps muscle strength (P = .006), and postoperative Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain score (P = .002) were significantly associated with quadriceps muscle strength at 1 year postoperatively. The odds of poor muscle strength recovery according to categorical analysis were 5.0-fold higher for patients aged >40 versus ≤20 years, 4.2-fold higher for those with preoperative quadriceps muscle index <60% versus ≥80%, and 7.7-fold higher for those with a postoperative KOOS-Pain score of <85 versus 100.

Conclusion

Older age, poor preoperative quadriceps muscle strength, and low postoperative KOOS-Pain score were risk factors for poor quadriceps muscle strength 1 year after primary ACLR. Surgical indications, including age, preoperative active rehabilitation, and pain control, should be considered for optimization of postoperative quadriceps muscle strength recovery.

Decision regret following opening wedge high tibial osteotomy: Older age as a risk factor

BACKGROUND

Understanding risk factors that can predict decision regret after surgical procedures can potentially increase the quality of patient decision making and reduce decision regret after opening wedge high tibial osteotomy (OWHTO). The purpose of the present study was to identify the risk factors that predict the likelihood of decision regret after OWHTO.

METHOD

Questionnaires were administered to 98 eligible OWHTO recipients more than one year post-operatively. They answered "Yes" or "No" to the question "Would you go for the same choice (OWHTO) if you had to do it over again?" Univariate and multivariate logistic regression analyses were conducted using the decision regret questionnaire as the dependent variable against patient characteristics and surgery related factors. A receiver operating characteristic curve and area under the curve were constructed and calculated for age at surgery. Cut-off values were determined using the Youden principle and receiver operating characteristic curves.

RESULTS

Among the 98 respondents, 18 (18%) reported regretting their decision. Older age at surgery was the only predictive risk factor for decision regret (P < 0.01). The area under the curve for the model using age to predict failure was 0.722. The cut-off value was 71 years. Patients aged 71 years or more had a 7.841 odds ratio for decision regret (P < 0.01).

CONCLUSIONS

Older age emerged as a predictive risk factor for decision regret after OWHTO. Patients aged 71 years or older had a higher decision regret rate after OWHTO than younger patients and should more carefully weigh the suitability of OWHTO against other options.

Therapeutic effect of C-type natriuretic peptide on persistent pain in a rat knee arthritis model

BACKGROUND

Intra-articular injection of C-type natriuretic peptide (CNP) at the acute inflammatory stage suppressed fibrotic changes in the infrapatellar fat pad (IFP), articular cartilage degeneration, and persistent pain in a monoiodoacetic acid (MIA)-induced rat knee arthritis model. In this study, we administered CNP during the inflammation subsiding period to evaluate CNP effectiveness in knees with osteoarthritis (OA) pathology.

METHODS

20 male Wistar rats were randomly divided into two groups. The rats received an intra-articular injection of MIA solution in the right knee to induce inflammation-induced joint degeneration. One group subsequently received an intra-articular CNP injection for six consecutive days from day 8, whereas another group received vehicle solution. Pain avoidance behavior tests and histological analyses were conducted to examine the therapeutic effects of CNP.

RESULTS

The incapacitance test indicated that the percent weight on the ipsilateral limb decreased after MIA injection by day 4 and continued to decrease until the end of the experiment in the vehicle group, suggesting persistent pain in the knee. Intra-articular injection of CNP reversed the weight-bearing ratio on day 19. Histological evaluation showed that the CNP group had more residual fat tissue in the IFP and fewer calcitonin gene-related peptide-positive nerve endings compared to the vehicle group. CNP could not reverse articular cartilage degeneration.

CONCLUSIONS

Intra-articular injection of CNP after the IFP fibrosis onset had no significant effect on OA severity and extent. Nevertheless, CNP might be utilized therapeutically for OA treatment since it can alleviate persistent knee pain and inhibit structural changes in residual fat tissue.

Association of Infrapatellar Fat Pad Fibrosis at 3 Months After ACL Reconstruction With Short-term Clinical Outcomes and Inflammatory Cytokine Levels in the Synovial Fluid

Background

Infrapatellar fat pad (IFP) fibrosis is reportedly associated with anterior knee pain and the progression of patellofemoral osteoarthritis after anterior cruciate ligament reconstruction (ACLR). However, causes of IFP fibrosis after ACLR have not been sufficiently investigated.

Purpose

To compare the descriptive characteristics, clinical outcomes, and inflammatory cytokine levels in the synovial fluid between patients who underwent ACLR with versus without severe IFP fibrosis.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients who underwent primary ACLR using autologous hamstring tendon were divided into 2 groups based on magnetic resonance imaging IFP fibrosis scoring (grades 0-5) at 3 months after surgery: the severe fibrosis group (grades 4 and 5) and mild fibrosis group (grades 0-3). Synovial fluid was aspirated on postoperative day 3 or 4 to measure inflammatory cytokine levels. Patient characteristics, clinical outcomes at 3 and 12 months after surgery, and inflammatory cytokine (interleukin [IL]-1β, IL-2, IL-6, IL-8, IL-10, tumor necrosis factor-α, and interferon-γ) levels were compared between the groups.

Results

Of the 36 patients included, 7 were allocated to the severe fibrosis group and 29 were allocated to the mild fibrosis group. The severe fibrosis group had a significantly longer operation time (153.0 vs 116.5 minutes for mild fibrosis; P = .007). Compared with the mild fibrosis group, the severe fibrosis group had greater pain during stair climbing (2.0 vs 0.7; P = .01) and a lower extension muscle strength ratio (operated/healthy side, 52.9% vs 76.1%; P < .001) at 3 months, and the severe fibrosis group had a lower Lysholm score (93.7 vs 97.3; P = .026) and greater knee extension (0.3° vs 1.9°; P = .043) and flexion angle restriction (142.9° vs 149.0°; P = .013) at 12 months. The severe fibrosis group demonstrated higher IL-1β (2.6 vs 1.4 pg/mL; P = .022), IL-6 (2.0 vs 1.1 ng/mL; P = .029), and interferon-γ levels (11.3 vs 4.0 pg/mL; P = .044).

Conclusion

Severe IFP fibrosis was associated with a longer operation time, higher inflammatory cytokine level in the synovial fluid, and worse clinical outcomes at 3 and 12 months after ACLR.

Association between knee cartilage thickness determined by magnetic resonance imaging three-dimensional analysis and the International Cartilage Repair Society (ICRS) arthroscopic grade

BACKGROUND

The purpose of this study was to retrospectively investigate whether the average cartilage thickness calculated by magnetic resonance imaging (MRI) three-dimensional (3D) analysis system was correlated with the International Cartilage Repair Society (ICRS) grade at each subregion, as a representative scoring for arthroscopic evaluation.

METHODS

The subjects were 102 patients who underwent arthroscopy for meniscus repair or high tibial osteotomy for medial osteoarthritis of the knee. Cartilage lesions were arthroscopically quantified according to the ICRS grade at each subregion. Fluoroscopy was used to compare the subregions on arthroscopic evaluation with subregions on MRI. The average cartilage thickness at each subregion was also automatically calculated from MRI data using our 3D analysis system. The association between ICRS grade and the average cartilage thickness at 18 subregions in the medial femoral and medial tibial regions was evaluated using Spearman's rank correlation coefficient.

RESULTS

Examination of the fluoroscopic images revealed that the posterior subregions in the medial femoral region did not match the position between arthroscopy and MRI; therefore, those three subregions were excluded. In the medial femoral region, the ICRS grade correlated moderately with cartilage thickness at five subregions and weakly at one subregion. In the medial tibial region, the ICRS grade correlated moderately with cartilage thickness at four subregions and weakly at one subregion, but it did not correlate at the other four subregions.

CONCLUSION

The average cartilage thickness determined by MRI 3D analysis correlated with arthroscopic grade at 11 of 15 subregions in the medial femoral and tibial regions.

Implant placement using the bone ring technique with and without membrane placement : a preclinical 12-month study in dogs

The bone ring technique is applied for vertical augmentation, in which the dental implant and autogenous block bone graft are simultaneously inserted.  We investigated the healing of bone around implants placed simultaneously using the bone ring technique with and without membrane placement after a 12-month healing period.  Vertical bone defects were created on both sides of the mandible of beagle dogs.  Implants were inserted into the defects through bone rings and fixed with membrane screws as healing caps.  The augmented sites on one side of the mandible were covered with a collagen membrane.  Samples were harvested 12 months after implantation and assessed histologically and by microcomputed tomography analysis.  All implants remained throughout the healing period; however, except for one implant, they showed lost caps and/or exposure to the oral cavity.  The implants had contact with newly formed bone despite frequent bone resorption.  The surrounding bone appeared mature.  The medians of bone volume and percentages of total bone area and bone-to-implant contact within the bone ring were slightly higher in the group with membrane placement than in that without membrane placement.  Nevertheless, none of the evaluated parameters were significantly affected by the membrane placement.  In the present model, soft tissue complication was frequent and the membrane application didn't reveal the effect at 12 months after the implant placement using the bone ring technique.  Sustained osseointegration and maturation of surrounding bone were observed in both groups after a 12-month healing period.

Short-Term Outcomes after High Tibial Osteotomy Aimed at Neutral Alignment Combined with Arthroscopic Centralization of Medial Meniscus in Osteoarthritis Patients

The study aimed to improve the long-term outcomes of open-wedge high tibial osteotomy (OWHTO); procedures combining OWHTO aimed at neutral alignment and arthroscopic centralization for meniscal extrusion have been introduced. The present study evaluated short-term patient-reported outcome measures; namely, the patient subjective satisfaction scores and Numeric Rating Scale (NRS) for walking pain after OWHTO aimed at neutral alignment with and without arthroscopic centralization for an extruded medial meniscus. A retrospective review of 50 primary OWHTO patients was conducted. Thirty-nine patients were included in the analysis after applying the exclusion criteria. The centralization group included 21 patients with knee osteoarthritis patients who underwent the OWHTO with arthroscopic meniscal centralization, while the control group included 18 patients who underwent OWHTO alone. The patient subjective satisfaction scores and NRS for walking pain were recorded at outpatient visits from before surgery to 3 years after surgery. In terms of the Lysholm knee scale, International Knee Documentation Committee subjective score, and Knee Osteoarthritis Outcome Score, the latest data (at least 2 years after surgery) were reviewed. Radiographic changes in joint space width and joint line congruence angle were measured 2 years postoperatively. Patient demographic data were also reviewed. One patient in the centralization group experienced a superficial surgical site infection. The patient subjective satisfaction and NRS scores for walking pain gradually improved by 1 year after surgery and were sustained until 3 years after surgery in both groups, with no significant difference between the groups. The course of patient-reported outcome measures from before surgery to 3 years after surgery for solely OWHTO aimed at neutral alignment and OWHTO aimed at neutral alignment with arthroscopic centralization showed the similar trends.

Double-Crown Prosthesis Retention Using Polyetherketoneketone (PEKK): An In Vitro Study

PURPOSE

To assess the retentive force of telescopic crowns using polyetherketoneketone (PEKK) high-performance polymer in relation to conventional materials over a long period of time in an in vitro setting.

MATERIALS AND METHODS

Thirty-six sets of primary and secondary crowns were fabricated as per the double crown-retained prostheses approach. Six samples were included in each of the five test groups (1: zirconia/PEKK [Zr/PEKK]; 2: titanium/PEKK [Ti/PEKK]; 3: cobalt-chrome/PEKK [CoCr/PEKK]; 4: PEKK/PEKK; and 5: gold/PEKK [Au/PEKK]) and the single control group (gold/galvano-gold [Au/GA]). The insertion-removal test was performed for 20,000 cycles, and the surface condition was observed. Retentive forces were analyzed using two-way ANOVA (α<0.05).

RESULTS

The retention forces in groups Zr/PEKK and Ti/PEKK significantly decreased over time (group 1: p = 0.035 and group 2: p = 0.001), whereas retentive force increased significantly in groups PEKK/PEKK, Au/PEKK, and control (group 4: p = 0.001, group 5: p = 0.008, and control: p = 0.042). Similar wear was observed on the primary crown in groups PEKK/PEKK, gold/PEKK, and control.

CONCLUSIONS

Groups PEKK/PEKK and Au/PEKK showed a transition of retentive force similar to the control group. Groups PEKK/PEKK and Au/PEKK had similar wear on the surface compared to control. Therefore, PEKK has a promising clinical potential.

The effectiveness of corrective exercises on the KOJI AWARENESS score and activity-related pain intensity

BACKGROUND

The KOJI AWARENESS� screening test is a self-administered screening tool for assessment of mobility, stability, and strength. It provides corrective exercises corresponding to the individual's answers to the KOJI AWARENESS� test questions. However, there is no evidence of the effectiveness of corrective exercises in improving KOJI AWARENESS� screening test scores and activity-related pain.

METHODS

Twenty-six healthy subjects (11 female and 15 male ; age 20?50 years) were selected for participation. In a controlled laboratory setting, subjects were administered the KOJI AWARENESS� test and were provided with individualized exercise programs based on the results of this first test. KOJI AWARENESS� results were checked on the first day immediately after the first exercise session, and then again after the two-week program. Pain intensity was also assessed during daily training using a numerical rating scale.

RESULTS

Compared to pre-intervention, KOJI AWARENESS� scores were significantly higher immediately after the first corrective exercise session and after 2 weeks of intervention (p<0.001). Moreover, pain intensity was significantly lower after 2 weeks of intervention (p<0.001).

CONCLUSIONS

Individualized KOJI AWARENESS� corrective exercises were effective immediately on the first day and also after the two-week program in improving the KOJI AWARENESS� score and reducing pain intensity during daily training. J. Med. Invest. 70 : 208-212, February, 2023.

Simultaneous bilateral total knee arthroplasty is safe and effective for patients in different ages

BACKGROUND

Simultaneous bilateral total knee arthroplasty is considered beneficial for patients with bilateral end-stage knee osteoarthritis, even though there could be potential postoperative complications. Presently, there is a paucity of evidence of the efficacy and safety of SB-TKA for elderly patients. This study aimed to compare the clinical outcomes of simultaneous bilateral total knee arthroplasty by different age groups.

METHODS

A total of 216 knees of 108 patients, who underwent simultaneous bilateral total knee arthroplasty for osteoarthritis at our hospital between April 2015 and September 2018, were divided into three groups based on age: 60s (44 knees), 70s (106 knees), and 80s (66 knees). Perioperative data and postoperative clinical outcomes 1 year after surgery were compared between the age groups.

RESULTS

The patients in the Group 60s were characterized by a higher body mass index (BMI) (P < 0.01), a lower pre-operative knee function score (P < 0.01), longer operation time (P < 0.01), greater intra-operative (P < 0.01), and postoperative bleeding (P = 0.026). No significant difference was found in terms of occurrence of various postoperative complications, although deep vein thrombosis and delirium occurred slightly more frequently in the Group 70s and the Group 80s than in the Group 60s group. The Knee Society Knee Score, a function score, and patient satisfaction scores were significantly improved in all groups 1 year after surgery. Moreover, these indexes of clinical outcomes were similar among the three groups.

CONCLUSION

Performing simultaneous bilateral total knee arthroplasty in 80s patients was found to be as safe and effective as in the 60s and 70s patients.

LEVEL OF EVIDENCE

3 (A retrospective cohort study).

Validity of the KOJI AWARENESS self-screening test for body movement and comparison with functional movement screening

OBJECTIVE

This study aimed to validate the KOJI AWARENESS™, a self-screening movement test, and compare it with the Functional Movement Screen (FMS).

METHODS

Fifty-seven healthy participants completed the KOJI AWARENESS™ and functional movement screening. Pearson's correlation coefficients were used to assess the validity of the test. Subsequently, partial correlation analysis was used to determine the associations between age, sex, body mass index, and sports level as control variables and motor function.

RESULTS

Correlation and partial correlation analyses showed a strong positive correlation between the functional movement screening and the KOJI AWARENESS™ scores.

CONCLUSION

This study found that the KOJI AWARENESS™ test is valid and comparable to functional movement screening. It can be used for self-screening of movement.

Epidemiology of MRI-detected muscle injury in athletes participating in the Tokyo 2020 Olympic Games

OBJECTIVE

Muscle injury is one of the most common injuries occurring at the Olympic Games often with devastating consequences. Epidemiological injury surveillance is recognised by the IOC as essential for injury prevention and management. We aimed to describe the incidence, anatomical location and classification of MRI-detected muscle injuries in athletes who participated in the Tokyo 2020 Olympic Games.

METHODS

Two board-certified orthopaedic surgeons, highly experienced in reviewing MRIs, independently and retrospectively reviewed all MRIs collected at the Tokyo 2020 Olympic Games from clinical reports generated by board-certified musculoskeletal radiologists at the IOC Polyclinic. The presence and anatomical site of muscle injuries were classified as: type a: myofascial/peripheral; type b: muscle belly or musculotendinous junction; and type c: injury which extends into the tendon, with reference to the British Athletics Muscle Injury Classification.

RESULTS

Fifty-nine MRI-detected muscle injuries were seen in 40 male and 19 female athletes. 24 athletes (41%) were unable to fully compete in their event. Fifty-two injuries (88%) involved lower extremity muscles with hamstring muscle injuries most common (32 of 59, 54%). Half of all muscle injuries occurred in athletes participating in athletics (30 of 59, 51%). 21 athletes (35%) sustained type a injuries, 14 athletes (24%) type b injuries and 24 athletes (41%) type c injuries. Of athletes with type c injuries, 18 (75%) did not complete their competition, a rate significantly higher than types a and b (OR 14.50, 95% CI 4.0 to 51.9, p<0.001).

CONCLUSION

For athletes sustaining muscle injuries during the Olympic Games, our study demonstrates the prognostic relevance of muscle injury anatomical site and severity for predicting completion or non-completion of an Olympic athlete's competition.

Medial osteophyte resection width correlates with correction of the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty

BACKGROUND

There is a lack of robust evidence for a correlation between the medial osteophyte resection and correction of the medio-lateral gap imbalance during total knee arthroplasty. The purpose of the present study was to quantify the effect of osteophyte resection on the medio-lateral component gap imbalance during posterior-stabilized total knee arthroplasty.

METHODS

Forty-five cases of primary posterior-stabilized total knee arthroplasty using the measured resection technique with posterior-stabilized prosthesis for varus knee osteoarthritis were reviewed. Medial and lateral joint gaps at 0°, 10°, 45°, and 90° of flexion, and maximum flexion were measured intraoperatively before and after the osteophyte resection. The relationship between medial osteophyte resection width and change of joint varus angle and medial component gap were assessed using Pearson's correlation coefficient.

FINDINGS

Medial component gap and joint varus angle values at post medial osteophyte resection were significantly larger and lower than at pre-resection (Medial gap: pre 9.5 ± 1.8 mm, post 10.3 ± 1.8 mm, P < 0.001, Joint angle: pre 5.2 ± 2.9°, post 4.2 ± 2.9°, P < 0.001). There was no significant difference between pre and post medial osteophyte resection in lateral component gaps. Per each 1 mm of medial osteophyte resection width, increases of 0.13 mm medial component gap and 0.2° valgus were observed (Medial gap: r = 0.38, P < 0.001, Joint angle: r = 0.38, P < 0.001).

INTERPRETATION

Medial osteophyte resection increases the medial component gap without lateral component gap increase, while decreasing the joint varus angle in primary posterior-stabilized total knee arthroplasty for varus knee osteoarthritis. Osteophyte resection width was found to correlate with correction of the medio-lateral component gap imbalance.

Addition of Synthetic Biomaterials to Deproteinized Bovine Bone Mineral (DBBM) for Bone Augmentation-A Preclinical In Vivo Study

(1) Aim: To investigate the effect of synthetic bone substitutes, α-tricalcium phosphate (α-TCP) or bi-layered biphasic calcium-phosphate (BBCP) combined with deproteinized bovine bone mineral (DBBM), on bone formation. (2) Methods: Thirty critical size defects were randomly treated with the following five different treatment modalities: (1) negative control (NC, empty), (2) DBBM, (3) α-TCP + DBBM (1:1), (4) BBCP 3%HA/97%α-TCP + DBBM (1:1), and (5) BBCP 6%HA/94%α-TCP + DBBM (1:1). The samples, at four weeks post-surgery, were investigated by micro-CT and histological analysis. (3) Results: A similar level of new bone formation was demonstrated in the DBBM with α-TCP bone substitute groups when compared to the negative control by histomorphometry. DBBM alone showed significantly lower new bone area than the negative control (p = 0.0252). In contrast to DBBM, the micro-CT analysis revealed resorption of the α-TCP + DBBM, BBCP 3%HA/97%α-TCP + DBBM and BBCP 6%HA/94%α-TCP + DBBM, as evidenced by a decrease of material density (p = 0.0083, p = 0.0050 and p = 0.0191, respectively), without changing their volume. (4) Conclusions: New bone formation was evident in all defects augmented with biomaterials, proving the osteoconductive properties of the tested material combinations. There was little impact of the HA coating degree on α-TCP in bone augmentation potential and material resorption for four weeks when mixed with DBBM.

Risk Factors Affecting Return to Sports and Patient-Reported Outcomes After Opening-Wedge High Tibial Osteotomy in Active Patients

Background:

Although opening-wedge high tibial osteotomy (OWHTO) is favored for active patients who expect to return to sports, there is still a lack of robust evidence for factors affecting their recovery.

Purpose:

To identify (1) risk factors leading to a decreased level of return to preoperative sports after OWHTO and (2) patient characteristics and intraoperative factors influencing patient-reported outcomes after return to sports.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Included were 69 patients who underwent OWHTO and who expected to return to their preoperative level of sports, measured as a Tegner activity level ≥2. All included patients had a minimum of 1 year of follow-up data. Logistic regression analyses were performed to assess the effect of independent variables on the level of return to preoperative sports after surgery; the independent variables were age, sex, body mass index, preoperative Tegner score, preoperative Kellgren-Lawrence grade, preoperative percentage of mechanical axis (%MA), opening gap width, concomitant meniscal treatment, postoperative %MA, postoperative medial proximal tibial angle (MPTA), and postoperative posterior tibial slope. Univariate and multiple regression analyses were performed to assess for influencing factors on postoperative International Knee Documentation Committee (IKDC) subjective scores in patients who were able to return to sports.

Results:

Of the 69 patients, 51 (73.9%) returned to sports after OWHTO. High preoperative Tegner scores were statistically associated with a decrease in return to sports (odds ratio, 1.494; P = .033). Multiple regression analysis (n = 46 patients) identified that a higher postoperative MPTA was associated with a decreased IKDC subjective score after return to sports (r = –0.345; P = .019).

Conclusion:

Higher postoperative MPTA was associated with the worsening of patient-reported outcomes among those patients who did return to their preoperative sports after OWHTO. Also, participation in high-activity sports was confirmed to be a significant risk factor for a decreased rate of return to preoperative sports. These findings can support preoperative planning and intraoperative decision making, particularly for active patients.

Imaging-detected bone stress injuries at the Tokyo 2020 summer Olympics: epidemiology, injury onset, and competition withdrawal rate

Background

Prevention and early detection of injuries are essential in optimising sport participation and performance. The aim of this study is to investigate the epidemiology, athlete injury history, and competition withdrawal rate of imaging-detected bone stress injuries during the Tokyo 2020 Olympic Games.

Methods

We collected and analysed imaging and clinical information in athletes with bone stress injuries diagnosed in the Olympic Village polyclinic during the Games. Two physicians independently and retrospectively reviewed all imaging examinations of bone stress injuries.

Results

A total of 11,315 individual athletes from 206 National Olympic Committees competed at the Games, during which 567 MRIs and 352 X-rays were performed at the Olympic Village polyclinic. Radiology examinations revealed four stress fractures and 38 stress reactions in 29 athletes (median age 24 years, range 18–35 years). Of these, 72% of athletes (n = 21) had symptoms before entering the Olympic Village. Bone stress injuries were most common in women (55%), the lower extremities (66%), and track and field athletes (45%). Six athletes (21%) did not start or did not finish their competitions.

Conclusions

This study revealed 42 imaging-detected bone stress injuries in the polyclinic of the Tokyo 2020 Olympic Village. The high proportion of athletes with symptoms before entering the village and the high proportion of competition withdrawals suggests the usefulness of an early MRI examination.

Short cytoplasmic isoform of IL1R1/CD121a mediates IL1β induced proliferation of synovium-derived mesenchymal stem/stromal cells through ERK1/2 pathway

Objectives

IL1β enhances proliferation of synovial mesenchymal stem/stromal cells (synMSCs) although they don't express its receptor, IL1R1/CD121a, on the cell surface. This study was aimed to elucidate the underlying mechanisms of IL1β-mediated growth promotion.

Methods

Human synMSCs were isolated from the suprapatellar synovial membrane. Cell proliferation was measured by MTT. Flowcytometric analyses were performed for surface antigen expression. Intracellular signaling pathway was analyzed by western blotting, immunocytochemistry and Q-PCR.

Results

IL1β enhanced proliferation through IL1R1/CD121a because IL1 receptor antagonist (IL1Ra) completely inhibited it. Expression analyses indicated that a short isoform of IL1R1/CD121a is expressed in synMSCs. Immunocytochemistry indicated that IL1R1/CD121a was majorly localized to the cytoplasm. Western blotting indicated that IL1β induced delayed timing of the ERK1/2 phosphorylation and IκBα degradation in synMSCs. Q-PCR analyses for IL1β-target genes indicated that cyclin D was specifically downregulated by a MAPK/ERK inhibitor, U0126, but not by a NFκB inhibitor, TPCA-1. In contrast, the expression of inflammatory cytokines such as IL1α and IL6 are significantly decreased by TPCA-1 but less effectively decreased by U0126.

Conclusion

Our data indicated that the cytoplasmic IL1R1/CD121a transduced IL1β signal in synMSCs. And the growth-promoting effect of IL1β can be separated from its inflammatory cytokine-inducing function in synMSCs.

The relationship between movement self-screening scores and pain intensity during daily training

Background : Various musculoskeletal screening and functional performance tests are used to evaluate physical condition. However, validated analysis tools that can identify gaps in pain knowledge during athletes' daily training are lacking. This study aimed to investigate the relationship between pain intensity in athletes during their daily training and the KOJI AWARENESS™ test in order to determine whether body dysfunction is related to pain among athletes. Methods : This cross-sectional study was conducted in a fitness center at the authors' affiliated institution. Thirty-five athletes (17 women and 18 men) aged 20-40 years were selected for study participation. KOJI AWARENESS™ self-evaluated test scores and pain intensity during daily training, as assessed on the numerical rating scale (NRS), were recorded. Results : The KOJI AWARENESS™ score showed a strong negative correlation with the NRS score for pain intensity during daily training (r = -0.640, P < 0.001). There was a significant negative correlation between KOJI AWARENESS™ and NRS scores, even when body mass index, sex, and age were entered as control variables. Conclusions : KOJI AWARENESS™ was highly accurate in detecting pain in athletes during their training. J. Med. Invest. 69 : 204-216, August, 2022.

Effects of different surgical procedures for meniscus injury on two-year clinical and radiological outcomes after anterior cruciate ligament reconstructions. -TMDU MAKS study

BACKGROUND

The treatment of meniscus injuries combined with anterior cruciate ligament (ACL) reconstruction would be important to improve outcomes after ACL reconstruction. However, the effects of treatment methods for meniscus after ACL reconstruction have not been thoroughly investigated. The objective of this study was to investigate the effects of treatment methods for meniscus on clinical and radiological outcomes at 2 years after ACL reconstruction.

METHODS

Three-hundred and eighteen patients with primary ACL reconstruction using autologous hamstring tendon registered in our multicenter study database and who were followed up for 2 years were included. They were then divided into 3 groups, the no meniscal lesion/untreated group (n = 149), the meniscal repair group (n = 139), and the meniscal resection group (n = 30). Patient-based subjective evaluations (Lysholm score, Knee injury and Osteoarthritis Outcome score and International Knee Documentation Committee subjective score), objective evaluations (Lachman test, pivot shift test and KT measurement), and radiological measurements (medial and lateral joint space width) were compared among the 3 groups preoperatively and at 2 years follow-up.

RESULTS

All subjective scores and objective evaluations significantly improved in all groups without significant differences among the groups postoperatively. Regarding radiological findings, the medial joint space width significantly decreased only in the resection group during the 2-year period, and the medial joint space width in the resection group was significantly smaller than that of the other groups at the 2-year follow-up. Moreover, the medial joint space width significantly decreased during the 2-year period when MM was resected.

CONCLUSIONS

In radiological findings, medial meniscus resection decreased medial joint space width two years after ACL reconstruction. On the other hand, treatment methods for meniscus neither significantly affected subjective nor objective findings until the 2-year follow-up.

LEVEL OF EVIDENCE

Ⅱ, Cohort study.

Comparison of Clinical Outcomes after Revision Anterior Cruciate Ligament Reconstruction using a Bone-patellar Tendon-bone Autograft and that Using a Double-Bundle Hamstring Tendon Autograft

PURPOSE

 The purpose of this study was to compare clinical outcomes between revision anterior cruciate ligament reconstruction (ACLR) using a bone-patellar tendon-bone (BPTB) autograft and that using a double-bundle hamstring tendon (HT) autograft.

METHODS

 Consecutive cases of revision ACLRs were reviewed. The Lysholm knee scale and Knee Osteoarthritis Outcome Score (KOOS) were recorded at the final follow-up. The pivot shift test, Lachman test, and anterior knee laxity measurement using an arthrometer were evaluated before revision ACLR and at final follow-up. Contralateral knee laxity was also evaluated, and side-to-side differences noted. The Lysholm knee scale, KOOS, the pivot shift test, Lachman test, and anterior knee laxity were compared between HT versus BPTB autograft recipient groups using the Mann-Whitney test or the t-test.

RESULTS

 Forty-one patients who underwent revision ACLR and followed up for at least 2 years were included. The graft source was a BPTB autograft in 23 patients (BPTB group) and a double-bundle HT autograft in 18 patients (HT group). The mean postoperative follow-up period was 44 ± 28 months in the BPTB group and 36 ± 18 in the HT group (p = 0.38). The HT group had significantly higher KOOS in the pain subscale (less pain) than the BPTB group at the final follow-up (BPTB group 84.2 vs. HT group 94.4; p = 0.02). The BPTB group showed significantly smaller side-to-side difference in anterior knee laxity (superior stability) than the HT group (0.3 vs. 2.6 mm; p < 0.01). The percentage of patients with residual anterior knee laxity in the BPTB group was significantly lower than that in the HT group (9.5% vs. 46.7%; odds ratio, 8.3; p = 0.02).

STUDY DESIGN

 This was a level 3 retrospective study.

CONCLUSION

 Revision ACLR with a BPTB autograft was associated with superior results regarding restoration of knee joint stability as compared with that with a double-bundle HT autograft, whereas double-bundle HT autograft was superior to BPTB autograft in terms of patient-reported outcomes of pain. The rest of the patient-reported outcomes were equal between the two groups.

Clinical outcomes of two-stage revision total knee arthroplasty in infected cases with antibiotic-loaded cement spacers produced using a handmade silicone mold

Purpose

This study assessed the clinical outcomes of periprosthetic joint infection patients who underwent two-stage revision total knee arthroplasty with antibiotic-loaded cement spacers fabricated using a handmade silicone mold.

Materials and methods

This study included seven patients (average age 77 years, average follow-up time 54 months) who underwent surgery at our hospital between 2009 and 2013. Clinical outcomes including knee scores, function scores, knee range of motion, and walking ability at the final observation, period from the primary total knee arthroplasty to implant removal, period from implant removal to revision total knee arthroplasty, and follow-up period after revision total knee arthroplasty were investigated.

Results

At the final follow-up, the average knee range of motion was 99°, with no significant differences at each stage; average knee and function scores were 84 and 77, respectively. With cement spacers, five patients were able to walk with a t-cane. No recurrence of infection was observed.

Conclusions

The clinical outcomes of the current case series demonstrated good knee function with preserved walking ability, without any recurrence of periprosthetic joint infection. This study suggests that using a handmade silicone mold could be an effective option for periprosthetic joint infection after a total knee arthroplasty.

Extracellular vesicles derived from mesenchymal stromal cells mediate endogenous cell growth and migration via the CXCL5 and CXCL6/CXCR2 axes and repair menisci

Background

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are promising candidates for tissue regeneration therapy. However, the therapeutic efficacy of MSC-EVs for meniscus regeneration is uncertain, and the mechanisms underlying MSC-EV-mediated tissue regeneration have not been fully elucidated. The aims of this study were to evaluate the therapeutic efficacy of intra-articular MSC-EV injection in a meniscus defect model and elucidate the mechanism underlying MSC-EV-mediated tissue regeneration via combined bioinformatic analyses.

Methods

MSC-EVs were isolated from human synovial MSC culture supernatants via ultrafiltration. To evaluate the meniscus regeneration ability, MSC-EVs were injected intra-articularly in the mouse meniscus defect model immediately after meniscus resection and weekly thereafter. After 1 and 3 weeks, their knees were excised for histological and immunohistochemical evaluations. To investigate the mechanisms through which MSC-EVs accelerate meniscus regeneration, cell growth, migration, and chondrogenesis assays were performed using treated and untreated chondrocytes and synovial MSCs with or without MSC-EVs. RNA sequencing assessed the gene expression profile of chondrocytes stimulated by MSC-EVs. Antagonists of the human chemokine CXCR2 receptor (SB265610) were used to determine the role of CXCR2 on chondrocyte cell growth and migration induced by MSC-EVs.

Results

In the meniscus defect model, MSC-EV injection accelerated meniscus regeneration and normalized the morphology and composition of the repaired tissue. MSC-EVs stimulated chondrocyte and synovial MSC cell growth and migration. RNA sequencing revealed that MSC-EVs induced 168 differentially expressed genes in the chondrocytes and significantly upregulated CXCL5 and CXCL6 in chondrocytes and synovial MSCs. Suppression of CXCL5 and CXCL6 and antagonism of the CXCR2 receptor binding CXCL5 and CXCL6 negated the influence of MSC-EVs on chondrocyte cell growth and migration.

Conclusions

Intra-articular MSC-EV administration repaired meniscus defects and augmented chondrocyte and synovial MSC cell growth and migration. Comprehensive transcriptome/RNA sequencing data confirmed that MSC-EVs upregulated CXCL5 and CXCL6 in chondrocytes and mediated the cell growth and migration of these cells via the CXCR2 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02481-9.

Effect of transplanted mesenchymal stem cell number on the prevention of cartilage degeneration and pain reduction in a posttraumatic osteoarthritis rat model

BACKGROUND

Mesenchymal stem cells (MSCs) transplantation therapy is considered an alternative therapy to prevent posttraumatic osteoarthritis (PTOA). However, consensus as to the sufficient number of MSCs for the prevention of PTOA is lacking. The purpose of this study was to determine the sufficient number of MSCs to achieve PTOA prevention and the reduction in pain after anterior cruciate ligament transection (ACLT).

METHODS

Eight-week-old male Wistar rats were used. ACLT was conducted in the knee joint as a PTOA model. According to the species-specific knee joint volume, 10⁴ MSCs in rats are equivalent to 3 × 10⁷ MSCs in humans, which was clinically prepared. MSCs (10⁴, 10⁵, or 10⁶ cells) or phosphate-buffered saline were injected into the knee joint at 1, 2, and 3 weeks after ACLT. Histological examinations were performed at 12 weeks after ACLT. The weight-bearing distribution improvement ratio was calculated as an assessment of pain until 12 weeks after ACLT.

RESULTS

Histological evaluations showed that all the MSCs groups except for 10⁴ MSCs group in femur were significantly improved compared to the control group at 12 weeks after ACLT. The weight-bearing distribution in the 10⁴ and 10⁵ MSCs groups at 12 weeks after ACLT and in the 10⁶ MSCs group at 6, 8, 10, and 12 weeks after ACLT were significantly higher than those of the control group.

CONCLUSION

A clinically feasible number of MSCs was found to reduce the articular cartilage degeneration and to decrease pain in the PTOA model. Increasing numbers of the cells further protected the articular cartilage against degeneration.

Inflammatory and healing environment in synovial fluid after anterior cruciate ligament reconstruction: Granulocytes and endogenous opioids as new targets of postoperative pain

Background

Biological processes after anterior cruciate ligament reconstruction (ACLR) is crucial for recovery. However, alterations in the of synovial fluid cell population during the acute phase following ACLR and the relationship between these cells and postoperative pain is unclear. The goal of this study was to reveal alterations in synovial fluid cell population during the acute phase following ACLR and relationship between postoperative pain and proportion of synovial fluid cells.

Methods

Synovial fluids were obtained from all patients (n = 50) before surgery and from patients who showed hydrarthrosis at days 4 (n = 25), and 21 (n = 42) post-surgery. The cell population was analyzed by flow cytometry. IL1β, IL8, and met-enkephalin in synovial fluid were quantitated by enzyme-linked immunosorbent assay. Patients answered numerical rating scale (NRS) questionnaire at 4 days and approximately 4 weeks postoperatively.

Results

The granulocyte population was significantly higher at 4 days after surgery than at any other time points. The population of macrophages was 3.2 times and 7.7 times as high as at surgery on days 4 and 21, respectively. T cell population was significantly higher 21 days after surgery compared to 4 days after surgery. All NRS 4 weeks after surgery showed a significant negative correlation with the granulocyte population in synovial fluid 4 days after surgery. Granulocyte population in synovial fluid significantly correlated with the levels of IL1β and IL8. Postoperative pain at rest tended to decrease with an increase in met-enkephalin concentration 4 days after ACLR.

Conclusions

Synovial fluid after ACLR had an inflammatory environment at early time points and a healing environment in the subsequent phase about concerning to the cellular composition. A proportion of synovial fluid cells and endogenous opioids affected postoperative pain.

•

Granulocyte population was higher at 4 days after ACLR than at other time points.

•

Postoperative pain negatively correlated with the granulocyte in synovial fluid.

•

Granulocyte population in synovial fluid correlate with IL1β and IL8 concentration.

•

Postoperative pain tended to decrease with an increase in met-enkephalin.

Inhibition of fibrotic changes in infrapatellar fat pad alleviates persistent pain and articular cartilage degeneration in monoiodoacetic acid-induced rat arthritis model

OBJECTIVE

We have reported that fibrotic changes in infrapatellar fat pad (IFP) after acute joint inflammation are closely associated with persistent pain in rats. In this study, to examine the effects of anti-fibrotic treatment on persistent pain, we used C-type natriuretic peptides (CNP) at the recovery phase after acute joint inflammation.

DESIGN

Thirty-two male Wistar rats were used in this study. Monoiodoacetic acid (MIA) was injected intra-articularly to induce IFP fibrosis and persistent pain. CNP was injected after acute inflammatory phase in the same knee joint. Time-course pain-avoidance behavior tests and histological analyses were performed to examine the effects of CNP.

RESULTS

Histological evaluations indicated that intra-articular injection of CNP inhibited fibrotic changes in IFP after acute inflammation. Incapacitance tests indicated that MIA injection into rat knee joint quickly decreased the percent weight on ipsilateral limb. In the vehicle group, the decrease was maintained up to day 28, suggesting that pain persistence occurred after acute inflammation (Day 0/Day 28, Est Dif -8.15, CI -10.78∼-5.53, Linear mixed-effect model). In contrast, the pain was alleviated in the CNP group after day 14 (Day0/Day 14, -0.51, -2.62-1.59). In addition, we observed significant improvement in the degree of articular cartilage degeneration at day 14 in the CNP group (OARSI score: vehicle 16.14 ± 4.37 vs CNP 6.87 ± 3.44, P < 0.01; Wilcoxon rank sum test).

CONCLUSION

Fibrotic changes in IFP may play important roles in both persistent pain and articular cartilage degeneration.

The impact of the size of bone substitute granules on macrophage and osteoblast behaviors in vitro

Objective

Bone substitute (BS) size might influence the clinical outcomes of guided bone regeneration (GBR) procedures. The aim of the present study was to investigate the influence of BS size on macrophage (Mφ) and osteoblast behaviors in vitro.

Materials and methods

Two different granule sizes (S and M/L) were assessed for four different commercial BSs: deproteinized bovine bone mineral (DBBM), biphasic calcium phosphate type 1 (BCP1), BCP type 2 (BCP2), and carbonate apatite (CO₃Ap). The BSs were compared for their impacts on the cell viability and differentiation potential of THP-1-derived Mφs and human osteoblast-like Saos-2 cells.

Results

The smaller granules showed higher material volumes and surface areas than the larger granules. Significantly higher viability of Mφs and Saos-2 cells was observed with the DBBM_L-size granules than with the DBBM_S-size granules. Gene expression experiments in Mφs revealed few differences between the two sizes of each BS, although higher CD206 mRNA levels were observed in the BCP1_L group and the CO₃Ap_M group than in the respective S-size groups on day 1. Only DBBM showed significantly higher mRNA levels of osteogenic markers, including Runx2 and osteocalcin, in Saos-2 cells in the S-size group than in the L-size group.

Conclusions

The S-size and L-size DBBM granules exhibited clear differences in cell outcomes: cells cultured on the S-size granules exhibited lower cell viability, higher osteopromotive ability, and no noticeable Mφ polarization changes.

Clinical relevance

A smaller granule size might be advantageous due to greater bone regeneration potential in the use of DBBM granules to treat defects.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-03804-z.

Collagen-Based Matrices for Osteoconduction: A Preclinical In Vivo Study

The aim of this study was to evaluate the influence of additional hydroxyapatite (HA) in collagen-based matrices (CM) and membrane placement on bone formation in calvarial defects. Critical size defects in the calvaria of 16 New Zealand White Rabbits were randomly treated with CM or mineralized collagen-based matrices (mCM). Half of the sites were covered with a collagen membrane. Animals were euthanized after 12 weeks of healing. The samples were studied by micro-CT and histology. Newly formed lamellar bone was observed in all samples at the periphery of the defect. In the central areas, however, new bone composed of both woven and lamellar bone was embedded in the soft tissue. Samples treated with mCM showed more residual biomaterial and induced more small bony islands in the central areas of the defects than samples with CM. Nevertheless, a complete defect closure was not observed in any of the samples at 12 weeks. Membrane placement resulted in a decrease in bone density and height. Significant differences between the groups were revealed only between CM groups with and without membrane coverage for bone height in the central area of the defect. Neither mineralization of CM nor membrane placement improved the osteogenic capacity in this particular defect. Nevertheless, mineralisation influenced bone density without a membrane placement and bone volume underneath a membrane. CM may be used as a scaffold in bone regeneration procedures, without the need of a membrane coverage. Further preclinical studies are warrant to optimise the potential of mCM.

Two-Year Outcomes After Meniscoplasty by Capsular Advancement With the Application of Arthroscopic Centralization Technique for Lateral Compartment Knee Osteoarthritis

BACKGROUND

A high prevalence of osteoarthritis (OA) progression in patients with lateral meniscal defects has been reported. However, optimal management techniques for active patients remain ill-defined.

HYPOTHESIS

Meniscoplasty by capsular advancement with the application of the centralization technique would improve clinical and radiological outcomes in patients with lateral compartment OA attributed to lateral meniscal defects.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 27 patients were enrolled who had undergone meniscoplasty by capsular advancement for lateral compartment OA attributed to lateral meniscal defects. In these patients, the meniscotibial capsule was released from the tibia and advanced with the remaining meniscus onto the rim of the tibial plateau to reform a meniscus-like configuration. Measures of clinical outcomes included clinical examination, Lysholm score, International Knee Documentation Committee (IKDC) subjective score, Knee injury and Osteoarthritis Outcome Score (KOOS), subjective rating scales regarding recovery of the operated knee, and sports performance level. Measures of radiographic outcomes included meniscal extrusion width or regeneration of the meniscus-like tissue on magnetic resonance imaging and lateral joint space width on standing extension anteroposterior and Rosenberg views. All clinical and radiographic outcomes were reported preoperatively and 2 years postoperatively, except magnetic resonance imaging findings, which were reported preoperatively and 1 year postoperatively.

RESULTS

The clinical outcomes were significantly improved 2 years postoperatively as compared with baseline: Lysholm score, IKDC subjective score, and KOOS subscores (all P < .0001). The patients' subjective recovery (P < .0001) and sports performance level (P < .0001) were also improved. One year postoperatively, 10 of 11 patients who had no meniscus remaining at the middle segment showed more than one-third the volume of meniscal tissue-like regeneration, and meniscal extrusion width was significantly reduced as compared with baseline in the remaining 16 patients (P = .0006). Joint space width increased at 2 years on the standing anteroposterior view (P < .0001) and the Rosenberg view (P = .0001).

CONCLUSION

Meniscoplasty of the lateral meniscus by capsular advancement improved clinical and radiographic outcomes at 2-year follow-up in patients with lateral compartment OA attributed to lateral meniscal defects.

Investigation of association between the preoperative intra-articular anesthetic test and persistent pain after total knee arthroplasty

BACKGROUND

A better understanding of the etiology of persistent pain after total knee arthroplasty (TKA) is required to prevent unfavorable outcomes. The purpose of this study was to investigate the association of persistent pain after TKA, patient characteristics, and the remaining pain ratio per the preoperative intra-articular anesthetic test.

METHODS

This study included 89 patients who underwent TKA and underwent an intra-articular anesthetic test preoperatively. The remaining pain ratio out of 100 percent 30 min after intra-articular anesthetic injection and demographic data were also evaluated preoperatively. Numerical rating scale (NRS) scores for pain during movement (Q1), at rest (Q2), at first movement in the morning (Q3), and during climbing up and down stairs (Q4) were evaluated 1 year after TKA. Multiple linear regression analysis was performed to assess the impact of independent variables on the NRS score for questionnaire No.4. and the remaining pain ratio per the intra-articular anesthetic.

RESULTS

The mean remaining pain ratio per the preoperative intra-articular anesthetic test was 29.3%. The NRS score for Q4 was significantly higher than those for any of the other NRS questionnaires administered 1 year after TKA (Q1-Q4, Q2-Q4, P < 0.001; Q3-Q4, P < 0.05). The analysis found the weak correlation between the pain ratio of anesthetic test and the NRS score for Q4 after TKA (R = 0.28, P = 0.018). BMI and preoperative FTA were the major predictors of remaining pain ratio per the intra-articular anesthetic test (R = 0.40, P = 0.002).

CONCLUSION

This study revealed that the remaining pain ratio per the preoperative intra-articular anesthetic test was weakly correlated with persistent pain during climbing up and down stairs 1 year after TKA. In addition, BMI and preoperative FTA were associated with the remaining pain ratio per the preoperative intra-articular anesthetic test.

Intra-articular Injection of Pure Platelet-Rich Plasma Is the Most Effective Treatment for Joint Pain by Modulating Synovial Inflammation and Calcitonin Gene-Related Peptide Expression in a Rat Arthritis Model

BACKGROUND

Platelet-rich plasma (PRP) has emerged as a treatment for osteoarthritis (OA). However, the effect that leukocyte concentrations in PRP have on OA remains unclear.

PURPOSE

To clarify the optimal PRP formulation for OA treatment by comparing pure PRP, leukocyte-poor PRP (LP-PRP), and leukocyte-rich PRP (LR-PRP) in a rat arthritis model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee arthritis was induced bilaterally in male Wistar rats with intra-articular injections of monosodium iodoacetate (MIA) on day 0. Rats were randomly assigned to 1 of 3 treatment groups (pure PRP, LP-PRP, and LR-PRP). On day 1, allogenic PRP was injected into the right knee of rats and phosphate-buffered saline was injected into the left knee as a control. Weight distribution on the hindlimbs was measured for 14 days to assess pain behavior. Rats were euthanized at day 5 or 14 for histological assessment of synovial tissue and cartilage. Immunohistochemical staining of calcitonin gene-related peptide (CGRP) and α-smooth muscle actin was performed to determine the mechanism of pain relief induced by the PRP preparations.

RESULTS

In all groups, PRP increased the load-sharing ratio on PRP-injected knees, with pure PRP eliciting the largest effect among the 3 kinds of PRP (P < .05). Structural changes in the synovial tissue were significantly inhibited in the pure-PRP group compared with the control group after both 5 and 14 days (P < .001 and P = .025, respectively), whereas no significant difference was found between the control, LP-PRP, and LR-PRP groups. An inhibitory effect on cartilage degeneration was observed only in the pure-PRP group on day 14. Pure PRP also significantly inhibited expression of CGRP-positive nerve fibers in the infrapatellar fat pad compared with the other groups (P < .05).

CONCLUSION

In an MIA-induced arthritis model, pure PRP injection was the most effective treatment for reduction of pain-related behavior and inhibition of synovial inflammation and pain sensitization.

CLINICAL RELEVANCE

PRP formulations should be optimized for each specific disease. This study shows the superiority of pure PRP for treatment of arthritis and joint pain.

Fibrotic changes in the infrapatellar fat pad induce new vessel formation and sensory nerve fiber endings that associate prolonged pain

The infrapatellar fat pad (IFP) contains nerve fiber endings and is considered to play an important role in the perception of knee pain. However, it is unclear whether and to what degree prolonged pain influences the nociceptive role of the IFP. To answer this question, we established a novel rat model of knee pain in which inflammation is restricted to the IFP. Rats received a single intra-IFP injection of monoiodoacetic acid (MIA) (0.2 mg/10 µL or 1.0 mg/10 µL) in the left knee and a phosphate-buffered saline (10 µL) injection in the right knee as a control. Pain-avoidance behavior and histological changes of the knee joint were measured at multiple time points up to 28 days after MIA injection. Histological analysis showed a transient inflammatory response in the IFP body in the 0.2-mg model, whereas prolonged inflammation followed by fibrotic changes was observed in the 1.0-mg model. Subtle histological alterations were observed in the articular cartilage and IFP surface regardless of the dose. The pain-avoidance behavior test indicated the development of prolonged knee pain throughout the experimental period in the 1.0-mg group. Histological assessments showed a significant increase in calcitonin gene-related peptide (CGRP)-positive nerve fiber endings inside IFPs with fibrosis in newly vascularized surrounding regions. These data suggest that irreversible fibrotic changes in the IFP induce the formation of new vessels and CGRP-positive nerve fiber endings that associate prolonged pain in the joint.

Histological comparison of Platelet rich fibrin clots prepared by fixed-angle versus horizontal centrifugation

Platelet-rich fibrin (PRF) is prepared from whole blood without any exogenous coagulation factors. Several preparation methods have now been introduced, particularly with differences in centrifugation parameters including g-force and time to improve their regenerative potential. Nevertheless, the centrifugation systems have not yet been clearly investigated for their influences on the PRF clot properties. The aim of the present study was to visually and histologically characterize the cell separation manner and blood cell localization on the whole PRF clots prepared by two different centrifugation system, fixed-angle and horizontal centrifugation. Leukocyte- and platelet-rich fibrin (L-PRF) was prepared on a fixed-angle centrifuge machine (IntraSpin, Intra-Lock, FL, USA) at 2700 rpm (~400 g at the RCF-clot; ~700 g at the RCF-max) for 12 min. The PRF prepared by horizontal centrifugation was prepared on a horizontal centrifugation (H-PRF) (Eppendorf 5702, Eppendorf, Germany) at 700 g at the RCF-max for 8 min. The cell morphology and localization were observed on the surface of PRF clots by scanning electron microscopy (SEM) and histologically by transaxial frozen sections by means of a film method. L-PRF clots demonstrated a sloped separation between the upper plasma and the bottom red blood cell (RBC) layers according to the angle of the rotor. Red dots were often observed on the distal walls of the tubes in the upper layers, consisting of aggregations of RBCs, leukocytes and platelets by SEM and histology. Clots produced on the horizontal centrifuge showed much smoother cell layer distribution/separation along the tube surfaces when compared to L-PRF. Horizontal centrifugation also demonstrated more evenly distributed platelets throughout the PRF clots when compared to L-PRF that gathered the majority of cells along the distal tube surface or within the buffy-coat region. In summary, it was found that horizontal centrifugation resulted in a more uniform blood cell separation of PRF clots when compared to the accumulation of cells gathered along the distal tube surfaces produced prepared by fixed-angle centrifugation. Future research is needed to evaluate the benefit of horizontal centrifugation in clinical practice.

Anatomic femoral tunnel placement is difficult by the transtibial technique: comparison of three different femoral tunnel drilling techniques in double-bundle anterior cruciate ligament reconstructions

PURPOSE

To compare the position and direction of femoral and tibial tunnels for both the anteromedial bundle (AMB) and posterolateral bundle (PLB) among three different femoral tunnel drilling techniques, transtibial (TT), transportal (TP), and outside-in (OI) techniques, in anatomic double-bundle ACL reconstruction to clarify advantages and disadvantages of each technique.

METHODS

One-hundred and thirty-nine patients underwent primary ACL reconstruction with an autologous semitendinosus tendon in our institution between 2014 and 2016. Thirteen patients were excluded according to the exclusion criteria. Of the 126 patients, 98 patients agreed to be included in this study. Patients were then randomized into three groups according to the femoral tunnel drilling technique; the TT, TP, and OI groups. Femoral and tibial tunnel angles and positions were measured using three-dimensional computed tomography.

RESULTS

Of patients who agreed to be included in this study, eight patients (seven in TT and one in OI) were excluded since the femoral tunnel could not be created at the intended position. Eighty-six patients (29 in TT, 29 in TP, and 28 in OI) were included for the analyses. Tunnel angles, as well as tunnel lengths, had significant differences among different techniques depending on each technique's characteristics. In terms of tunnel position, femoral tunnel positions of both the AMB and PLB in the TT group were significantly higher than those in the TP group (AMB: p = 0.003, PLB: p = 0.001), and the PLB tunnel position in the TP group had significantly smaller vaciance than that in the TT group (p = 0.004) and OI group (0.002).

CONCLUSIONS

The femoral tunnel positions created by the TT technique were significantly higher, with larger variance, than the TP technique in double-bundle ACL reconstruction, although the positions seemed to be within anatomical footprint. In addition, there were several cases in which femoral tunnels could not be created at the intended position by the TT technique.

LEVEL OF EVIDENCE

I.

Synovial fluid-derived mesenchymal cells have non-inferior chondrogenic potential and can be utilized for regenerative therapy as substitute for synovium-derived cells

Recent progress in the field of mesenchymal stem cell (MSC) biology has enabled their clinical application. In the autologous cell transplantation therapy, the source of MSCs are quite important to reduce patients' physical burden. In this study, we isolated MSCs from the synovial fluid (SF) and synovial membrane (Syn) of the same patients and compared the biological characteristics of them. In vitro and in vivo experiments indicated the non-inferior chondrocytic differentiation and articular cartilage regeneration potential of SF-MSCs compared to that of Syn-MSCs; however, SF-MSCs showed less proliferative potential than Syn-MSCs in vitro. Flow cytometry-based multiplex surface antigen expression analyses indicated that SF-MSCs exhibit fewer cells positive for CD140, which is a functional growth factor receptor for MSCs. Nevertheless, we obtained enough SF-MSCs for transplantation within several passages. Since arthrocentesis is routinely performed during outpatient care in the consultation room and is less invasive than synovial biopsy, MSC derived from synovial fluid could be considered an attractive cell source for cartilage regenerative therapy as a substitute for Syn-MSC. Developing these cells for clinical application may greatly benefit patients undergoing autologous MSC transplantation therapy.

The effect of a longitudinal tear of the medial meniscus on medial meniscal extrusion in anterior cruciate ligament injury patients

PURPOSE

The purpose of this study was to investigate the effect of a longitudinal tear of the medial meniscus (MM) and its meniscal repair on MM extrusion in anterior cruciate ligament (ACL)-injured patients. The hypothesis underlying this study was that a longitudinal tear of the MM is correlated with MM extrusion, and that the extrusion would persist after ACL reconstruction with concomitant MM repair.

METHODS

Forty-three ACL-injured patients with a concomitant MM longitudinal tear were included in the MM tear group. Thirty-four solely ACL-injured patients without any meniscal injuries were included in the Control group. Medial meniscus extrusion width (MEW) was measured pre-operatively and three months after surgery on magnetic resonance imaging.

RESULTS

Pre-operative MEW in the MM tear group was significantly larger than that in the Control group (MM tear group: 1.5 mm, Control: 0.3 mm, P < 0.001). The MEW change in the MM tear group was significantly greater than that in the Control group three months after operation (MM tear group: 0.8 mm, Control: -0.2 mm, P < 0.001). The number of sutures required for repair was correlated with MEW both pre-operatively and postoperatively in the MM tear group (pre-operative: P = 0.005, R = 0.42, postoperative: P < 0.001, R = 0.54).

CONCLUSION

Longitudinal tear of the MM was correlated with MM extrusion and the MM extrusion persisted after ACL reconstruction with concomitant MM repair in the MM tear group. The initial meniscal tear size was directly correlated with the pre-operative MEW. Therefore, meniscal extrusion after longitudinal tears of the medial meniscus should be taken into careful consideration.