In Vivo Kinematics and Cruciate Ligament Tension Are Not Restored to Normal After Bicruciate-Preserving Arthroplasty.

BACKGROUND: Whether cruciate ligament forces in cruciate-preserving designs, such as unicompartmental knee arthroplasty (UKA) or bi-cruciate-retaining total knee arthroplasty (BCR-TKA), differ from those in normal knees remains unknown. The purpose of this study was to compare the in vivo kinematics and cruciate ligament force in knees before and after UKA or BCR-TKA to those in normal knees during high-flexion activity. METHODS: Overall, twenty normal knees, 17 knees with medial UKA, and 15 knees with BCR-TKA were fluoroscopically examined while performing a squatting activity. A 2-dimensional or 3-dimensional registration technique was employed to measure tibio-femoral kinematics. Ligament strains and tensions in the anteromedial bundle of the anterior cruciate ligament and posterolateral bundle of the anterior cruciate ligament and the anterolateral bundle of the posterior cruciate ligament (aPCL) and posteromedial bundle of the posterior cruciate ligament (pPCL) during knee flexion were analyzed. RESULTS: Tension in both bundles of the anterior cruciate ligament decreased with flexion. At 60° of flexion, anteromedial bundle of the anterior cruciate ligament tension in postoperative UKA knees was greater than that in normal knees. At 30° of flexion, posterolateral bundle of the anterior cruciate ligament tension in postoperative UKA knees was greater than that in normal knees. On the other hand, aPCL and pPCL tensions increased with flexion. From 40 to 110° of flexion, the postoperative aPCL tension in UKA knees was greater than that in normal knees. At 110° of flexion, the preoperative pPCL tension in UKA knees was greater than that in normal knees. In addition, the postoperative pPCL tension in UKA knees was larger than that in normal knees beyond 20° of flexion. Furthermore, the pPCL tension of postoperative BCR-TKA knees was larger than that in normal knees from 20 to 50° and beyond 90° of flexion. CONCLUSIONS: The cruciate ligament tensions, especially posterior cruciate ligament tension in knees after UKA, were greater than those in the normal knees. Surgeons performing bi-cruciat-preserving knee arthroplasties should therefore balance cruciate ligament tension more carefully in flexion and extension.

Androgen receptor suppresses ß-adrenoceptor-mediated CREB activation and thermogenesis in brown adipose tissue of male mice.

Thermoregulation is a process by which core body temperature is maintained in mammals. Males typically have a lower body temperature than females. However, the effects of androgens, which show higher levels in males, on adrenergic receptor-mediated thermogenesis remain unclear. Here, we demonstrate that androgen-androgen receptor (AR) signaling suppresses the ß-adrenergic agonist-induced rise of core body temperature using castrated and AR knockout (ARKO) male mice. Furthermore, in vitro mechanistic studies show that activated AR inhibits cAMP response element (CRE)-mediated transcription by suppressing cAMP response element-binding protein (CREB) phosphorylation. The elevation of body temperature induced by the ß-adrenergic agonist CL316243 was higher in ARKO and castrated mice than in the control mice. Similarly, CL316243 induced a greater increase in Uncoupling protein 1 (Ucp1) expression and CREB phosphorylation in the brown adipose tissue of ARKO mice than in that of controls. We determined that activation of AR by dihydrotestosterone suppressed ß3-agonist- or forskolin-induced CRE-mediated transcription, which was prevented by AR antagonist. AR activation also suppressed CREB phosphorylation induced by forskolin. Moreover, we found AR nuclear localization, but not transcriptional activity, was necessary for the suppression of CRE-mediated transcription. Finally, modified mammalian two-hybrid and immunoprecipitation analyses suggest nuclear AR and CREB form a protein complex both in the presence and absence of dihydrotestosterone and forskolin. These results suggest androgen-AR signaling suppresses ß-adrenoceptor-induced UCP1-mediated brown adipose tissue thermogenesis by suppressing CREB phosphorylation, presumably owing to a protein complex with AR and CREB. This mechanism explains sexual differences in body temperature, at least partially.

Risk factors for hamstring strain injury in male college American football players -a preliminary prospective cohort study.

BACKGROUND: Given the frequency of hamstring strain injuries (HSI) among male college American football players, several studies have attempted to determine whether certain risk factors can predict their occurrence. However, no consensus on modifiable risk factors for HSIs in male college American football players has yet been reached to prevent these injuries. This study aimed to clarify risk factors for HSI prospectively in college male American football players. METHODS: A total of 78 male college American football players, whose positions were limited to skill positions, were medically assessed for potential risk factors of HSI. The preseason medical assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability. RESULTS: HSI occurred in a total of 25 thighs from 25 players (32.1%). Injured players had significantly lower hamstring flexibility (p = 0.02) and hamstring to quadriceps strength ratio (H/Q) (p = 0.047) compared to uninjured players. Additionally, injured players had significantly lower general joint laxity scores, especially for the total (p = 0.04), hip (p = 0.007), and elbow (p = 0.04) scores, compared to uninjured players. CONCLUSIONS: Lower hamstring flexibility, lower hamstring to quadriceps strength ratio, and lower general joint laxity score were identified as risk factors for HSI in male college American football players placed in skill positions. The muscle flexibility and H/Q ratio could be useful in preventing HSI in such players.

Short-term clinical results of bicruciate-retaining total knee arthroplasty using personalized alignment.

BACKGROUND: Bicruciate-retaining (BCR) prosthesis has been introduced to recreate normal knee movement by preserving both the anterior and posterior cruciate ligaments. However, the use of BCR total knee arthroplasty (TKA) is still debatable because of several disappointing reports. We have been performing BCR TKAs with personalized alignment (PA). This study aimed to reveal the limb alignment and soft tissue balance of FA-BCR TKAs and compare the clinical outcomes of FA-BCR TKAs with those of unicompartmental knee arthroplasty (UKA). METHODS: Fifty BCR TKAs and 58 UKAs were included in this study. The joint component gaps of BCR TKA were evaluated intraoperatively and the postoperative hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were measured using full-length standing radiography. The short-term clinical outcomes of BCR TKAs were compared with those of UKA using the scoring system of 2011 Knee Society Scoring (KSS) and the knee injury and osteoarthritis outcome score (KOOS) at an average of 2 years postoperatively (1-4yeras). RESULTS: The coronal alignment values of PA-BCR TKA were as follows: HKA angle, 177.9° ± 2.3°; MPTA, 85.4° ± 1.9°; and LDFA, 87.5° ± 1.9°. The joint component gaps at flexion angles of 10°, 30°, 60°, and 90° were 11.1 ± 1.2, 10.9 ± 1.4, 10.7 ± 1.3, and 11.2 ± 1.4 mm for the medial compartment and 12.9 ± 1.5, 12.6 ± 1.8, 12.5 ± 1.8 and 12.5 ± 1.7 mm for the lateral compartment, respectively. The patient expectation score and maximum extension angle of PA-BCR TKA were significantly better than those of UKAs. CONCLUSIONS: The short-term clinical outcomes of PA-BCR TKA were comparable or a slightly superior to those of UKAs.

Bicruciate-retaining total knee arthroplasty procedure reduced tensile force in the middle and posterior components of lateral collateral ligament during deep knee flexion activities with no effect on tensile force of the medial collateral ligament.

PURPOSE: To analyse the effects of bicruciate-retaining total knee arthroplasty (BCR-TKA) on the tensile force of the collateral ligaments during two deep knee flexion activities, cross-leg sitting and squatting. METHODS: Thirteen patients (15 knees) treated using bicruciate-retaining total knee arthroplasty (BCR-TKA) for knee joint osteoarthritis were analysed. Knee joint kinematics during cross-leg sitting (open-chain flexion) and squatting (closed-chain flexion) were evaluated through fluoroscopy. The tensile force was calculated in vivo based on the change in the distance between the femoral and tibial attachment areas for the anterior, middle, and posterior components of the superficial (sMCL) and deep (dMCL) medial collateral ligament and the lateral collateral ligament (LCL). Differences in the calculated tensile forces of the collateral ligaments were evaluated using repeated measures of analysis of variance, with post hoc pairwise comparison (Bonferroni test). Statistical significance was set at P ≤ 0.05. RESULTS: The correction of the coronal alignment was related to the surgical technique, not to the implant design. No significant change in the tensile force in all three components of the sMCL from pre- to post-TKA (n.s.) was observed. For dMCL, a pre- to post-TKA change in the tensile force was observed only for the anterior dMCL component (p = 0.03). No change was observed in the tensile force of the anterior LCL with increasing flexion, with no difference in pre- to post-TKA and between activities (n.s.). In contrast, tensile force in the middle LCL slightly decreased with increasing flexion during squatting, pre- and post-TKA. After surgery, lower forces were generated at 40° of flexion (p = 0.04). Tensile force in the posterior LCL was higher in extension than flexion, which remained high in the extension post-TKA. However, after surgery, lower tensile forces were generated at 10° (p = 0.04) and 40° (p = 0.04) of flexion. CONCLUSIONS: The in vivo change in tensile forces of the collateral ligaments of the knee before and after BCR-TKA can inform the development of appropriate ligament balancing strategies to facilitate recovery of deep knee flexion activities after TKA, as well as for continued improvement of BCR-TKA designs. LEVEL OF EVIDENCE: III.

Postoperative quadriceps weakness and male sex are risk factors for patellofemoral articular cartilage lesions after anatomical anterior cruciate ligament reconstruction.

PURPOSE: Patellofemoral (PF) compartment cartilage lesions are a frequent problem after anterior cruciate ligament (ACL) reconstruction. This study aimed to determine the factors that influence PF cartilage lesions after anatomical ACL reconstruction. METHODS: This study enrolled a total of 114 patients who did not manifest PF compartment cartilage lesions during anatomical ACL reconstruction and underwent second-look arthroscopy 18 months postoperatively. Arthroscopy using the International Cartilage Repair Society (ICRS) classification was used to assess cartilage lesions. The correlation between surgical findings, radiographic factors, and clinical factors and change of ICRS grade was analysed. Multivariate regression analysis was conducted to reveal the independent risk factors for PF cartilage lesions among patients' demographic data and parameters that correlated with the change of ICRS grade in the correlation analyses. RESULTS: ICRS grade changes in PF cartilage were significantly correlated with age, sex, quadriceps strength at 1 year postoperatively, hamstrings strength at pre- and 1 year postoperatively, and single leg hop test at 1 year postoperatively. However, no significant correlation was found between the time between injury and surgery, posterior tibial slope angle, pre- and postoperative Tegner activity scale, graft type, initial graft tension, meniscus injury, meniscus injury treatment, pre- and postoperative range of motion, anteroposterior laxity and preoperative quadriceps strength, and the change in ICRS grade. Multivariate regression analysis revealed male (P = 0.019) and quadriceps strength weakness at 1 year postoperatively (P = 0.009) as independent risk factors for PF cartilage lesions. CONCLUSIONS: Quadriceps strength weakness 1 year after ACL reconstruction and males were correlated with a new PF cartilage lesion after anatomical ACL reconstruction, with no significant correlation between bone-patellar tendon-bone autograft, initial graft tension, or extension deficit and new PF cartilage lesion. Rehabilitation that focuses on quadriceps strength after ACL reconstruction is recommended to prevent new PF cartilage lesions. LEVEL OF EVIDENCE: Level IV.

Curcumin activates G protein-coupled receptor 97 (GPR97) in a manner different from glucocorticoid.

Curcumin is a yellow pigment in turmeric (Curcuma longa) with various physiological effects in the body. To elucidate the molecular mechanisms by which bioactive compounds exert their function, identification of their molecular targets is crucial. In this study, we show that curcumin activates G protein-coupled receptor 97 (GPR97). Curcumin dose-dependently activated serum-response element-, but not serum-response factor-response element-, nuclear factor of activated T-cell-response element-, or cAMP-response element-, mediated transcription in cells overexpressed with GPR97. The structure-activity relationship indicated that (i) the double-bonds of the central 7-carbon chain were essential for activation; (ii) a methoxy group on the aromatic ring was required for maximal activity; (iii) the addition of glucuronic acid moiety or a methoxy group to the aromatic ring, but not the methylation of the aromatic p-hydroxy group, eliminated the activity; (iv) the stability of curcumin would be related to receptor activation. Both mutant GPR97(T250A) lacking the cleavage at GPCR proteolysis site and mutant GPR97(ΔN) lacking the N-terminal extracellular region were activated by curcumin and its related compounds similar to wild-type GPR97. In contrast, the synthetic glucocorticoid beclomethasone dipropionate and l-Phe activated wild-type GPR97 and GPR97(T250A), but not GPR97(ΔN). Moreover, curcumin exerted an additive effect on the activation of wild-type GPR97 with beclomethasone dipropionate, but not with l-Phe. Taken together, these results indicate that curcumin activates GPR97 coupled to Gi/Go subunit, and suggest that curcumin and glucocorticoid activate GPR97 in a different manner.

Regulation of osteoarthritis development by ADAM17/Tace in articular cartilage.

INTRODUCTION: A disintegrin and metalloproteinase 17 (Adam17), also known as TNFα-converting enzyme (Tace), is a membrane-anchored protein involved in shedding of TNF, IL-6 receptor, ligands of epidermal growth factor receptor (EGFR), and Notch receptor. This study aimed to examine the role of Adam17 in adult articular cartilage and osteoarthritis (OA) pathophysiology. MATERIALS AND METHODS: Adam17 expression was examined in mouse knee joints during OA development. We analyzed OA development in tamoxifen-inducible chondrocyte-specific Adam17 knockout mice of a resection of the medial meniscus and medial collateral ligament (medial) model, destabilization of the medial meniscus (DMM) model, and aging model. We analyzed downstream pathways by in vitro experiments, and further performed intra-articular administration of an Adam17 inhibitor TAPI-0 for surgically induced mouse OA. RESULTS: Adam17 expression in mouse articular cartilage was increased by OA progression. In all models, Adam17 knockout mice showed ameliorated progression of articular cartilage degradation. Adam17 knockout decreased matrix metallopeptidase 13 (Mmp13) expression in both in vivo and in vitro experiments, whereas Adam17 activation by phorbol-12-myristate-13-acetate (PMA) increased Mmp13 and decreased aggrecan in mouse primary chondrocytes. Adam17 activation enhanced release of soluble TNF and transforming growth factor alpha, a representative EGF ligand, from mouse primary chondrocytes, while it did not change release of soluble IL-6 receptor or nuclear translocation of Notch1 intercellular domain. Intra-articular administration of the Adam17 inhibitor ameliorated OA progression. CONCLUSIONS: This study demonstrates regulation of OA development by Adam17, involvement of EGFR and TNF pathways, and the possibility of Adam17 as a therapeutic target for OA.

In Vivo three-dimensional kinematics of normal knees during sitting sideways on the floor.

BACKGROUND: The normal knee kinematics during asymmetrical kneeling such as the sitting sideways remains unknown. This study aimed to clarify in vivo kinematics during sitting sideways of normal knees. METHODS: Twelve knees from six volunteers were examined. Under fluoroscopy, each volunteer performed a sitting sideways. A two-dimensional/three-dimensional registration technique was used. The rotation angle, varus-valgus angle, anteroposterior translation of the medial and lateral sides of the femur relative to the tibia, and kinematic pathway in each flexion angle was evaluated. RESULTS: Bilateral knees during sitting sideways showed a femoral external rotation relative to the tibia with flexion (ipsilateral: 13.7 ± 3.5°, contralateral: 5.8 ± 6.8°). Whereas the ipsilateral knees showed valgus movement of 4.6 ± 2.5° from 130° to 150° of flexion, and the contralateral knees showed varus movement of -3.1 ± 4.4° from 110° to 150° of flexion. The medial side of the contralateral knees was more posteriorly located than that of the ipsilateral knees beyond 110° of flexion. The lateral side of the contralateral knees was more anteriorly located than that of the ipsilateral knees from 120° to 150° of flexion. In the ipsilateral knees, a medial pivot pattern followed by a bicondylar rollback was observed. In the contralateral knees, no significant movement followed by a bicondylar rollback was observed. CONCLUSION: Even though the asymmetrical kneeling such as sitting sideways, the knees did not display asymmetrical movement.

Effects of a 1-mm difference in bearing thickness on intraoperative bearing movement and kinematics in Oxford unicompartmental knee arthroplasty.

BACKGROUND: The choice of mobile bearing (MB) thickness is essential for obtaining successful results after mobile-bearing Oxford unicompartmental knee arthroplasty (UKA). This study aimed to investigate the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and intraoperative knee kinematics in Oxford UKAs. METHODS: We prospectively investigated the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and knee kinematics in 25 patients who underwent Oxford UKAs when surgeons didn't know which bearing thickness to choose with 1-mm difference. A trial tibial component that was scaled every 2 mm was used to measure the intraoperative MB movement, and the tibial internal rotation relative to the femur and the knee varus angle was simultaneously evaluated using the navigation system as the knee kinematics. We separately evaluated sets of two MB thicknesses with 1-mm differences, and we compared the intraoperative parameters at maximum extension; 30º, 45º, 60º, and 90º flexion; and maximum flexion between the thicker MB (thick group) and the thinner MB (thin group). RESULTS: The MB in the thin group was located significantly posteriorly at 90º flexion compared with that in the thick group; however, there were no differences at the other flexion angles. There was significantly less tibial internal rotation in the thin group at 90º flexion than that in the thick group; however, there were no differences at the other flexion angles. The knee varus angles in the thick group were significantly smaller than those in the thin group by approximately one degree at all angles other than at 30º and 45º flexion. CONCLUSION: The thicker MB could bring the less posterior MB movement and the more tibial internal rotation at 90º flexion, additionally the valgus correction angle in the thicker MB should be paid attention. These results could help surgeons to decide the thickness of MBs when they wonder the thickness of MB.

Femoral rollback at high-flexion during squatting is related to the improvement of sports activities after bicruciate-stabilized total knee arthroplasty: an observational study.

BACKGROUND: In bicruciate-stabilized total knee arthroplasty (BCS-TKA), the relationship between the postoperative kinematics and sports subscales in patient-reported outcome measures (PROMs) remains unknown. The purpose of this study was to determine the relationship between kinematics and sports subscales using the PROMs after BCS-TKA. METHODS: Sixty-one patients with severe knee osteoarthritis were examined at 13.5 ± 7.8 months after BCS-TKA. The patients performed squats under single fluoroscopic surveillance in the sagittal plane. Range of motion of the knee, axial rotation of the femur relative to the tibial component, and anteroposterior (AP) translation of the medial and lateral femorotibial contact points were measured using a 2D-to-3D registration technique. In addition, the relationship between the kinematics and improvement of the sports subscales in the Knee Injury and Osteoarthritis Outcome Score (KOOS) was evaluated. RESULTS: In rotation angle, the femoral external rotation was observed from 0 to 50° of flexion. The amount of femoral external rotation did not correlate with PROMs-SP. In medial AP translation, posterior translation was observed from 0 to 20° and 80-110° of flexion. Mild anterior translation was observed from 20 to 80° of flexion. Beyond 80° of flexion, posterior translation was positively correlated with squatting. In lateral AP translation, posterior translation was observed from 0 to 20° and 80-110° of flexion. Beyond 80° of flexion, posterior translation was positively correlated with running, jumping, twisting/pivoting, and kneeling. CONCLUSION: Femoral rollback at high flexion during squatting may be important to improve sports performance after BCS-TKA.

The higher patient-reported outcome measure group had smaller external rotation of the femur in bicruciate-stabilized total knee arthroplasty.

PURPOSE: The hypothesis of this study was that the kinematics of patients with higher patient-reported outcome measures (PROMs) differ from those of patients with lower PROMs after bicruciate-stabilized total knee arthroplasty (BCS-TKA). METHODS: A total of 32 patients with severe knee osteoarthritis were examined 11.2 ± 3.2 months after BCS-TKA. The patients performed squats under single fluoroscopic surveillance in the sagittal plane. To estimate the spatial position and orientation of the femoral and tibial components, a 2D-to-3D registration technique was used. This technique uses a contour-based registration algorithm, single-view fluoroscopic images and 3D computer-aided design models. Knee range of motion, varus-valgus alignment, axial rotation of the femur relative to the tibial component, anteroposterior translation of the medial and lateral femorotibial contact points, kinematic paths, and anterior and posterior post-cam engagement were measured. The patients were divided into two groups using hierarchical cluster analysis based on the 1-year postoperative Knee Injury and Osteoarthritis Outcome Score and 2011 Knee Society Score. RESULTS: The femoral component had significantly more external rotation in the low-score group than in the high-score group (5.1 ± 1.8° vs. 2.2 ± 2.7°, p = 0.02). The high-score group had a medial pivot pattern from 0 to 20° of flexion, without significant movement from 20 to 70°, and final bicondylar rollback beyond 70°. The low-score group had a medial pivot from 0 to 70° of flexion and bicondylar rollback beyond 70°. There were no significant between-group differences in the varus-valgus angle or post-cam engagement. CONCLUSION: The higher PROM group had smaller external rotation of the femur after BCS-TKA. LEVEL OF EVIDENCE: Level III.

High initial graft tension increases external tibial rotation on the axial plane after anatomical anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to clarify the effects of applying different amounts of initial graft tension on the femorotibial positional relationship on the axial plane after anatomical ACL reconstruction. METHODS: Eighty patients who underwent isolated ACL reconstructions using bone-patellar tendon-bone grafts were included in this study. In 40 of the 80 patients, the grafts were fixed at full knee extension with maximum manual force (high graft tension; Group H), whereas in the other 40 patients, the grafts were fixed at full knee extension with force of 80 N (low graft tension; Group L). One week postoperatively, all patients underwent computed tomography (CT) on bilateral knee joints with knee extension. The femorotibial positional relationship in axial CT images were retrospectively evaluated. Side-to-side differences (the surgical side minus the unaffected side) were calculated in these variables. RESULTS: The side-to-side differences in anterior tibial translation distances were - 1.8 ± 2.1 mm in Group H and - 1.9 ± 2.0 mm in Group L, with no significant difference between the two groups. The side-to-side differences in tibial lateral shifts were - 0.2 ± 1.5 mm in Group H and 0.0 ± 1.4 mm in Group L, with no significant difference between the two groups. The side-to-side differences in tibial external rotation angles were 2.7 ± 4.5° in Group H and 0.3 ± 3.3° in Group L, with a significant difference between the two groups (P < 0.01). CONCLUSION: Applying high initial graft tension (maximum manual force) resulted in the external rotation of the tibia against the femur just after anatomical ACL reconstruction. In contrast, applying low initial graft tension (80 N at full knee extension) did not change the femorotibial rotational relationship.

Parsing multiomics landscape of activated synovial fibroblasts highlights drug targets linked to genetic risk of rheumatoid arthritis.

OBJECTIVES: Synovial fibroblasts (SFs) are one of the major components of the inflamed synovium in rheumatoid arthritis (RA). We aimed to gain insight into the pathogenic mechanisms of SFs through elucidating the genetic contribution to molecular regulatory networks under inflammatory condition. METHODS: SFs from RA and osteoarthritis (OA) patients (n=30 each) were stimulated with eight different cytokines (interferon (IFN)-α, IFN-γ, tumour necrosis factor-α, interleukin (IL)-1ß, IL-6/sIL-6R, IL-17, transforming growth factor-ß1, IL-18) or a combination of all 8 (8-mix). Peripheral blood mononuclear cells were fractioned into five immune cell subsets (CD4+ T cells, CD8+ T cells, B cells, natural killer (NK) cells, monocytes). Integrative analyses including mRNA expression, histone modifications (H3K27ac, H3K4me1, H3K4me3), three-dimensional (3D) genome architecture and genetic variations of single nucleotide polymorphisms (SNPs) were performed. RESULTS: Unstimulated RASFs differed markedly from OASFs in the transcriptome and epigenome. Meanwhile, most of the responses to stimulations were shared between the diseases. Activated SFs expressed pathogenic genes, including CD40 whose induction by IFN-γ was significantly affected by an RA risk SNP (rs6074022). On chromatin remodelling in activated SFs, RA risk loci were enriched in clusters of enhancers (super-enhancers; SEs) induced by synergistic proinflammatory cytokines. An RA risk SNP (rs28411362), located in an SE under synergistically acting cytokines, formed 3D contact with the promoter of metal-regulatory transcription factor-1 (MTF1) gene, whose binding motif showed significant enrichment in stimulation specific-SEs. Consistently, inhibition of MTF1 suppressed cytokine and chemokine production from SFs and ameliorated mice model of arthritis. CONCLUSIONS: Our findings established the dynamic landscape of activated SFs and yielded potential therapeutic targets associated with genetic risk of RA.

Intraoperative rotational kinematics and its influence on postoperative clinical outcomes differ according to age in Unicompartmental knee Arthroplasty.

BACKGROUND: Although Oxford unicompartmental knee arthroplasty (UKA) is used in patients of wide age ranges, there is no clear information regarding the age differences in terms of intraoperative femorotibial rotational kinematics and its influence on clinical outcomes. Therefore, this study was conducted to examine the age differences in terms of intraoperative rotational kinematics and postoperative clinical outcomes and to analyze their relationship with classification according to the age group. METHODS: We investigated 111 knees of patients who underwent Oxford UKA using a navigation system and divided them into two groups: elderly (aged ≥75 years; 48 knees) and nonelderly (aged < 75 years; 63 knees). Intraoperative tibial internal rotational angles relative to the femur during passive knee flexion were measured using a navigation system, and clinical outcomes were evaluated using knee range of motion, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Knee Society Functional Score at 2 years postoperatively. The relationships between intraoperative tibiofemoral rotational angles and clinical outcomes were also evaluated in the two groups. RESULTS: The intraoperative tibial internal rotational angle relative to the femur during knee flexion was significantly larger in the nonelderly group (13.5°) than in the elderly group (9.0°). The intraoperative tibial internal rotational angle showed a positive correlation with the pain subscale of KOOS only in the nonelderly group. CONCLUSION: Intraoperative rotational kinematics and its influence on clinical outcomes were different between elderly and nonelderly patients, and the tibial internal rotational angle could be a more important factor for successful UKA in nonelderly patients.

Influence of surgical factors on patient satisfaction after bi-cruciate stabilized total knee arthroplasty: retrospective examination using multiple regression analysis.

BACKGROUND: One of the causes of dissatisfaction following total knee arthroplasty (TKA) is abnormal knee kinematics. A newly designed bi-cruciate stabilized (BCS) TKA system has been developed to produce close-to-normal kinematics because of its anatomic tibiofemoral articular geometry and cam-post mechanism. Although BCS TKA is expected to improve patient satisfaction, no reports have described the appropriate technique or soft tissue handling required to achieve excellent satisfaction with BCS TKA. This study is to identify intraoperative surgical predictors of patient satisfaction after BCS TKA. METHODS: We studied 104 knees with primary varus knee osteoarthritis that underwent BCS TKA with a navigation system retrospectively. Surgical parameters including coronal, sagittal and axial alignment and joint laxity in each compartment that affected patient satisfaction was evaluated. Satisfaction score was evaluated with use of the 2011 Knee Society Scoring system. The multivariate regression analysis included age, gender, body mass index and intraoperative parameters that correlated with satisfaction scores in the univariate analysis (P < 0.05). The current study focused on the patient satisfaction score at 1 year postoperatively and didn't evaluate the long term clinical results nor survivorship. RESULTS: The postoperative satisfaction score was 28.6 ± 8.1. Multivariate analysis showed that medial joint laxity at 30° flexion (P = 0.003), tibial excessive external rotation alignment (P = 0,009) and tibial varus alignment (P = 0.029) were predictors of poor satisfaction score. CONCLUSIONS: When performing BCS TKA, surgeons should pay attention to maintaining proper stability of the medial compartment at mid flexion range and should avoid tibial varus and excessive external rotational alignment.

Both intraoperative medial and lateral soft tissue balances influence intraoperative rotational knee kinematics in bi-cruciate stabilized total knee arthroplasty: A retrospective investigation.

BACKGROUND: Tibial internal rotation following total knee arthroplasty (TKA) is important in achieving favorable postoperative clinical outcomes. Studies have reported the effect of intraoperative soft tissue balance on tibial internal rotation in conventional TKA, no studies have evaluated the effects of soft tissue balance at medial or lateral compartments separately on tibial internal rotation in bi-cruciate stabilized (BCS) TKA. The purpose of this study was to clarify the relationship between medial or lateral component gaps and rotational knee kinematics in BCS TKA. METHODS: One hundred fifty-eight knees that underwent BCS TKA were included in this study. The intraoperative medial and lateral joint laxities which was defined as the value of component gap minus the thickness of the tibial component were firstly divided into two groups, respectively: Group M-stable (medial joint laxity, ≤ 2 mm) or Group M-loose (medial joint laxity, ≥ 3 mm) and Group L-stable (lateral joint laxity, ≤ 3 mm) or Group L-loose (lateral joint laxity, ≥ 4 mm). And finally, the knees enrolled in this study were divided into four groups based on the combination of Group M and Group L: Group A (M-stable and L-stable), Group B (M-stable and L-loose), Group C (M-loose and L-stable), and Group D (M-loose and L-loose). The intraoperative rotational knee kinematics were compared between the four Groups at 0°, 30°, 60°, and 90° flexion, respectively. RESULTS: The rotational angular difference between 0° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group A at 30° flexion (*p < 0.05). The rotational angular difference between 30° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group D at 30° flexion (*p < 0.05). The rotational angular differences between 30° or 90° flexion and maximum flexion in Group B at 60° flexion were significantly larger than those in Group A at 60° flexion (*p < 0.05). CONCLUSION: Surgeons should pay attention to the importance of medial joint stability at midflexion and lateral joint laxities at midflexion and 90° flexion on a good tibial internal rotation in BCS TKA.

Weight-bearing knee flexion angle better correlates with patient-reported outcome measures than non-weight-bearing condition in total knee arthroplasty: a three-dimensional analysis study.

BACKGROUND: This study aims to elucidate and compare the relationship between the knee flexion angle and patient-reported outcome measures (PROM) in both non-weight-bearing (NWB) and weight-bearing (WB) conditions. METHODS: This retrospective cohort study included 61 knees (47 patients) who underwent total knee arthroplasty. The knee flexion angle was measured by three conditions: NWB in manual goniometer, NWB in fluoroscopic three-dimensional (3D) analysis and WB in the fluoroscopic 3D analysis. The PROM was evaluated by postoperative 2011 Knee Society Score (2011 KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Correlations between the knee flexion angle and PROM was analyzed using Spearman's correlation coefficient. Additionally, whether the angular difference between NWB and WB correlated with the PROM or not was evaluated. RESULTS: The NWB knee flexion angle in a goniometer, NWB in 3D analysis, and WB in 3D analysis were 124.6° ± 8.4°, 118.0° ± 10.5°, and 109.5° ± 13.3°, respectively. The angular difference was 8.5° ± 12.8°. No PROM correlation existed in NWB using a goniometer. Moreover, significant positive correlations in 2011 KSS symptoms (r = 0.35) and 2011 KSS functional activities (r = 0.27) were noted in NWB using 3D analysis. Significant positive correlations existed in 2011 KSS symptoms (r = 0.32), 2011 KSS functional activities (r = 0.57), KOOS pain (r = 0.37), KOOS activity of daily living (ADL; r = 0.45), KOOS sports (r = 0.42), and KOOS quality of life (r = 0.36) in WB using 3D analysis. Significant negative correlations were noted in 2011 KSS functional activities (r = - 0.45), KOOS ADL (r = - 0.30), and KOOS sports (r = - 0.38) in angular difference. CONCLUSIONS: The WB knee flexion angle better correlated with PROM compared with NWB by evaluation of 3D analysis. The larger the angular difference existed between NWB and WB, the lower the PROM score.

Lateral posterior tibial slope and length of the tendon within the tibial tunnel are independent factors to predict tibial tunnel widening following anatomic anterior cruciate ligament reconstruction.

PURPOSE: This study aimed to conduct a multivariate analysis to identify independent factors that predict tibial tunnel widening (TW) after anatomical anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) grafts. METHODS: In total, 103 patients who underwent ACL reconstructions using BPTB grafts were included. Tunnel aperture area was measured using three-dimensional computed tomography 1 week and 1 year postoperatively, and the tibial TW was calculated. The patients were divided into group S comprising 58 patients who had tibial TW < 30% and group L comprising 45 patients who had tibial TW > 30%, retrospectively. Using univariate analyses, age, gender, body mass index, Tegner activity scale, the time between injury and surgery, tibial tunnel location, tibial tunnel angle, medial posterior tibial slope, lateral posterior tibial slope, and length of the tendon in the tibial tunnel were compared between two groups. Multivariate regression analysis was conducted to reveal the independent risk factors for the tibial TW among preoperative demographic factors and radiographic parameters that correlated with the tibial TW in the univariate analyses. RESULTS: Compared with those at 1 week postoperatively, mean tibial tunnel aperture areas were increased by 30.3% ± 26.8% when measured at 1 year postoperatively. The lateral posterior tibial slope was significantly larger (p < 0.001), and the length of the tendon within the tibial tunnel was significantly longer in group L than that in group S (p = 0.03) in the univariate analyses. Multivariate regression analysis showed that the increase in lateral posterior tibial slope (p = 0.001) and the length of the tendon within the tibial tunnel (p = 0.03) were predictors of the tibial TW. CONCLUSIONS: This study showed that increased lateral posterior tibial slope and a longer tendinous portion within the tibial tunnel were independent factors that predicted the tibial TW following anatomical ACL reconstruction with a BPTB graft. LEVEL OF EVIDENCE: III.

Weight-bearing status affects in vivo kinematics following mobile-bearing unicompartmental knee arthroplasty.

PURPOSE: The effects of weight bearing (WB) on knee kinematics following mobile-bearing unicompartmental knee arthroplasty (UKA) remain unknown. The purpose of this study was to clarify the effects of WB on in vivo kinematics of mobile-bearing UKA during high knee flexion activities. METHODS: The kinematics of UKA were evaluated under fluoroscopy during squatting (WB) and active-assisted knee flexion (non-weight bearing, NWB). Range of motion, femoral axis rotation relative to the tibia, anteroposterior (AP) translation of the medial and lateral sides, and kinematic pathway were measured. RESULTS: There were no differences in knee flexion range and external rotation of the femur in each flexion angle between the WB conditions. The amount of femoral external rotation between minimum flexion and 60° of flexion during WB was significantly larger than that during NWB, and that between 60° and 130° of flexion during NWB was significantly larger than that during WB. There were no differences in medial AP translation of the femur in each flexion angle between the WB conditions. However, on the lateral side, posterior translation of 52.9 ± 12.7% was observed between minimum flexion and 130° of flexion during WB. During NWB, there was no significant translation between minimum flexion and 60° of flexion; beyond 60° of flexion, posterior translation was 41.6 ± 8.7%. Between 20° and 80° of flexion, the lateral side in WB was located more posteriorly than in NWB (p < 0.05). CONCLUSION: Mobile-bearing UKA has good anterior stability throughout the range of knee flexion. WB status affects the in vivo kinematics following mobile-bearing UKA. LEVEL OF EVIDENCE: III.