The clock gene Bmal1 controls inflammatory mediators in rheumatoid arthritis fibroblast-like synoviocytes.

OBJECT: To clarify the involvement of clock genes in the production of inflammatory mediators from RA-FLS, we examined the role of Bmal1, one of the master clock genes. METHODS: RA-FLSs were stimulated with IL-1ß (0, 20 ng/mL), IL-6 (0, 20 ng/mL), IL-17 (0, 20 ng/mL), TNF-α (0, 20 ng/mL) or IFN-γ (0, 20 ng/mL) to examine the expression of Bmal1, MMP-3, CCL2, IL-6, IL-7 and IL-15 by qPCR and immunofluorescence staining. After silencing Bmal1, RA-FLSs were stimulated with IL-1ß (0, 20 ng/mL), TNF-α (0, 20 ng/mL) or IFN-γ (0, 20 ng/mL) to examine the expressions of inflammatory mediators; MMP-3, CCL2, IL-6 and IL-15 by qPCR, ELISA and immunofluorescence staining. RESULTS: Bmal1 expressions were increased by IL-1ß, TNF-α and IFN-γ stimulations. Under stimulations with TNF-α, IL-1ß, and IFN-γ, mRNA and protein expressions of MMP-3, CCL2 and IL-6 were suppressed by siBmal1. CONCLUSION: Results indicate that Bmal1 contributes the production of MMP-3, CCL2, and IL-6 from RA-FLS, implying Bmal1 is involved in the pathogenesis of RA by regulating the inflammation.

Four stem fractures in a 12-year follow-up study of 9,135 patients with Exeter hip stems at seven teaching facilities in Japan.

BACKGROUND: Although excellent long-term results have been reported for the Exeter stem, stem fracture is recognized as a rare complication. However, there have been no reports on the incidence and risk factors for stem fractures based on detailed population information. This study aimed to clarify the incidence of Exeter hip stem fracture based on detailed population information from seven Exeter stem teaching centers in Japan and to examine the risk factors for stem fracture. METHODS: A total of 8,499 primary total hip arthroplasties (THA) and 636 revision hip arthroplasties (revisions) performed at seven Exeter teaching hospitals between 1999 and 2021 were included and retrospectively investigated based on medical records. RESULTS: Stem fractures were identified in two primary THA (fracture rate: 0.02%) and two revision THA (fracture rate: 0.21%) cases. The stem length was ≤125 mm in three out of these four cases. Revision and 30 stem were the risk factors for stem fractures. Weight and body mass index (BMI) were not significantly associated with the occurrence of stem fractures. CONCLUSIONS: In Western countries, the incidence of Exeter stem fractures is reportedly 0.017-0.15% for primary THA and 0.99-1.21% for revision THA. In this study, the incidence of primary THA was 0.02%, which is similar to the lowest reported rate, whereas the incidence of revision THA was 0.21%, which is lower than that reported in previous studies. Revision surgery had the same risk factors as those reported in the West-namely, stem length ≤125 mm (except for the 30 stem) and BMI, which were not risk factors in Japanese patients.

Early postoperative clinical recovery of robotic arm-assisted vs. image-based navigated Total hip Arthroplasty.

BACKGROUND: This study compared the early clinical recovery of total hip arthroplasty (THA) using computer navigation systems (nTHA) and robotic arm-assisted THA (rTHA). METHODS: Thirty prospective subjects who underwent rTHA were clinically compared to 30 subjects who underwent nTHA. Clinical data (surgical time, intraoperative blood loss, pain severity, number of days to independent walking, and Harris Hip Score (HHS) at discharge), and radiographic parameters (inclination and anteversion angles) were statistically compared between the two groups. RESULTS: Follow-up times were 24.3 ± 6.0 and 27.0 ± 7.0 days in the rTHA and nTHA groups, respectively. The surgical time (135.1 ± 13.9 min vs. 146.2 ± 12.8 min, p = 0.002), number of days to independent walking (7.2 ± 2.0 vs. 11.5 ± 3.0 days, p < 0.001), and postoperative pain using a numeric rating scale on postoperative days 7, 10,, and 14 (1.4 ± 0.9 vs. 2.2 ± 1.2, p = 0.005; 1.0 ± 0.8 vs. 1.8 ± 1.1, p = 0.002; 0.3 ± 0.5 vs. 1.1 ± 0.9, p < 0.001; respectively) were significantly reduced in the rTHA group compared to the nTHA group. The rTHA group showed a significantly higher postoperative HHS compared to the nTHA group (85.3 ± .3.2 vs. 81.0 ± 8.5, p = 0.014). No statistically significant difference was observed in radiographic parameters between the groups; however, the incidence of intraoperative target angle changes was significantly lower in the rTHA group than in the nTHA group (0/30 subjects [0%] vs. 11/30 subjects [36.7%], p < 0.001). CONCLUSION: The surgical time, postoperative pain, and number of days to independent walking were significantly shorter, and the HHS at discharge was significantly higher in the rTHA group than in the nTHA group. Thus, compared to the nTHA group, the rTHA group showed improved early clinical recovery.

Mid-flexion stability in the anteroposterior plane is achieved with a medial congruent insert in cruciate-retaining total knee arthroplasty for varus osteoarthritis.

PURPOSE: This study aimed to compare the intraoperative kinematics, especially for mid-flexion femorotibial anteroposterior (AP) stability, between newly developed medial congruent (MC) inserts and cruciate-retaining (CR) inserts in navigated cruciate-retaining total knee arthroplasty (CR-TKA). METHODS: Thirty consecutive patients with varus osteoarthritis undergoing CR-TKA using an image-free navigation system were enrolled. AP kinematics, the AP translation under manual maximum stress to the knee joint at 45° flexion, rotational kinematics, and varus-valgus laxity were evaluated using a navigation system and statistically compared between the MC and CR inserts. RESULTS: AP kinematic analysis showed that the femoral position with the CR insert was significantly anterior at a maximum extension to 45° flexion compared with the MC insert (p < 0.05). The amount of AP translation at 45° flexion with the MC insert was significantly smaller than that with the CR insert (p < 0.05). Rotational kinematics found that the tibial position at maximum extension was significantly externally rotated with the MC inserts than with the CR inserts. Varus-valgus laxity was comparable between the MC and CR inserts. CONCLUSION: The current results showed that greater mid-flexion AP stability was achieved with the MC inserts than with the CR inserts in CR-TKA. Intraoperative kinematics with the MC inserts more closely resembled those with preoperative conditions in CR-TKA. LEVEL OF EVIDENCE: III, prospective comparative study.

Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting total knee arthroplasty.

PURPOSE: To investigate the correlation between intraoperative tibiofemoral anteroposterior changes at 90° of flexion and postoperative maximum flexion angles in navigated cruciate-substituting TKA. The hypothesis of this study was that intraoperative tibiofemoral anteroposterior changes at 90° of flexion indirectly reflect posterior cruciate ligament (PCL) function and associate with postoperative maximum flexion angles. METHODS: Fifty-five consecutive patients with varus osteoarthritis treated with primary TKA were retrospectively analysed. All patients received the same type of implant, placed with an image-free navigation system. The PCL was retained, and cruciate-substituting inserts were used in all cases. The mean follow-up was 44 ± 8 months. The preoperative and postoperative kinematics were measured intraoperatively with a navigation system, and the preoperative and postoperative tibiofemoral anteroposterior positions at 90° of flexion were determined. The correlation between intraoperative anteroposterior position changes and postoperative maximum flexion angles was investigated. The correlation between the change of anteroposterior position and tibiofemoral rotational angles was also assessed. RESULTS: The intraoperative anteroposterior position change was -1.7 ± 3.4 mm (a positive value indicates tibial posterior shift). Flexion angle improvement was negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.17, p < 0.005). Postoperative maximum flexion angles were also negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.09, p < 0.05). The postoperative amount of tibial internal rotation was positively correlated with the preoperative amount (R2 = 0.60, p < 0.0001); however, the intraoperative anteroposterior position change was not correlated with the postoperative amount of tibial internal rotation (n.s.). CONCLUSION: A navigation system may be able to indirectly evaluate PCL function and predict the postoperative flexion angles in cruciate-substituting TKA. Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting TKA. LEVEL OF EVIDENCE: Level 3, retrospective comparative study.

Influence of Narrow Femoral Implants on Intraoperative Soft Tissue Balance in Posterior-Stabilized Total Knee Arthroplasty.

BACKGROUND: Narrow femoral implants were developed to improve fit and prevent overhang in primary total knee arthroplasty (TKA). We compared intraoperative soft tissue balance between standard and narrow implants in posterior-stabilized (PS) TKA. METHODS: We enrolled 30 consecutive patients with varus osteoarthritis undergoing PS TKA using an image-free navigation system. Standard and narrow femoral trial implants were inserted, and their soft tissue balance was measured. Subgroup analysis, based on the actual implanted femoral implant, was performed to assess the influence of narrow implants on soft tissue balance. RESULTS: Narrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 60° (P < .05). For the standard implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at 30°, 120°, and 135° flexion (P < .05). For the narrow implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 0° and 60° (P < .05). Narrow trial group had significantly larger varus ligament balance than standard trial group at 45° and 60° flexion (P < .05). The varus angles for standard implants were comparable between groups; however, narrow trial group had significantly larger varus angles for narrow implants than standard trial group at 45°, 60°, and 120° flexion (P < .05). CONCLUSION: The medial-lateral dimension and volume of the femoral component may influence intraoperative soft tissue balance in PS TKA. The effects may be greater when narrow implants are selected to avoid component overhang.

Expressions of circadian clock genes represent disease activities of RA patients treated with biological DMARDs.

Objectives: Rheumatoid Arthritis (RA) is the autoimmune disease representing the circadian variations of symptoms such as morning stiffness of joints or increased production of cytokines around midnight. Clock genes have been reported to affect on the pathogenesis of RA, however, the detailed relation between clock genes and disease activities of RA has remained unclear.Methods: In this study, 15 RA patients treated with biological disease modifying anti-rheumatic drugs (bDMARDs) were enrolled (TNF inhibitor, 5; IL-6 inhibitor, 5; CTLA4-IgG, 5). Blood samples were collected from RA patients before treatment and at the study end-point fulfilling DAS28-ESR < 3.2. Total RNA was extracted from leukocytes to examine the expressions of the clock genes. We then evaluated the correlation of the clock gene expression with disease activity and the diagnostic values of the clock genes.Results: The expressions of the clock genes were significantly modulated by bDMARDs treatments. Disease activities were significantly correlated with the clock genes expressions, and disease remission/low disease activity could be distinguished from moderate/high disease activity due to the sensitivities, the specificities and the areas under the curves of that.Conclusion: The expressions of the clock genes in leukocytes could be useful as novel biomarkers predicting disease activities and therapeutic efficacies for bDMARDs in RA treatments.

A vertical load applied towards the trunk unilaterally increases the bilateral abdominal muscle activities.

[Purpose] It is considered that evaluation of the vertical trunk function is important, because humans stand and move with two legs. To evaluate this, a novel method named Trunk Righting Test has been reported. The purpose of this study was to examine the trunk muscle activity during a TRT using electromyogram analysis. [Participants and Methods] This study included 7 healthy volunteer males. The TRT evaluated the supportability of the posture after moving 10 cm laterally from the sitting position using a hand-held dynamometer. The TRT measurements were analyzed separately at the measurement side (ipsilateral side) and at the non-measurement side (contralateral side). The measurements were obtained bilaterally, and the evaluated muscles included the rectus abdominis, internal oblique, external oblique, multifidus, and transversus abdominis. The measured value was expressed as a percentage after comparing with the value at the maximum voluntary contraction (% MVC) for standardization. The changes in the muscle activities in the sitting position and TRT were evaluated. [Results] All the muscle activities significantly increased during the TRT in contrast to that in the sitting posture. [Conclusion] The load support of the trunk on one side during the TRT was significant in all the muscles on both the sides, which increased the muscle activity, in contrast to that in the sitting position.

TNF-α induces expression of the circadian clock gene Bmal1 via dual calcium-dependent pathways in rheumatoid synovial cells.

Tumor necrosis factor (TNF)-α is responsible for expressions of several clock genes and affects joint symptoms of rheumatoid arthritis (RA) with diurnal fluctuation. We tried to determine the mechanism involved in over-expression of Bmal1, induced by TNF-α, in primary cultured rheumatoid synovial cells. Cells were incubated with intra-cellular Ca2+ chelator BAPTA-AM, calcineurin inhibitor FK506 and p300/CBP (CREB binding protein) inhibitor C646, respectively, or transfected with p300 and CBP small interfering RNA (siRNA) before stimulation with TNF-α. Oscillation phase and amplitude of Bmal1, transcriptional activator Rorα, transcriptional repressor Rev-erbα, and histone acetyltransferases (p300 and Cbp) were evaluated by quantitative real-time PCR. As results, TNF-α did not influence the oscillation phase of Rev-erbα, while enhanced those of Rorα, resulting in over-expression of Bmal1. When Ca2+ influx was inhibited by BAPTA-AM, TNF-α-mediated up-regulation of Rorα was cancelled, however, that of Bmal1 was still apparent. When we further explored another pathway between TNF-α and Bmal1, TNF-α suppressed the expression of Rev-erbα in the absence of Ca2+ influx, as well as those of p300 and Cbp genes. Finally, actions of TNF-α, in increasing Bmal1/Rorα and decreasing Rev-erbα, were cancelled by C646 treatment or silencing of both p300 and Cbp. In conclusion, we determined a novel role of TNF-α in inducing Bmal1 via dual calcium dependent pathways; Rorα was up-regulated in the presence of Ca2+ influx and Rev-erbα was down-regulated in the absence of that. Results proposed that inhibition of p300/CBP could be new therapeutic targets for RA.

Tibiofemoral rotational alignment affects flexion angles in navigated posterior-stabilized total knee arthroplasty.

PURPOSE: To investigate the tibiofemoral rotational profiles during navigated posterior-stabilized (PS) total knee arthroplasty (TKA) and investigate the effect on post-operative maximum flexion angles. METHODS: Twenty-five subjects, treated with navigated PS TKA, were enrolled, and the effect of posterior cruciate ligament (PCL) resection and component implantation on tibiofemoral rotational kinematics was statistically evaluated. Then, the effect of rotational alignment changes on the post-operative maximum angles was retrospectively examined in 96 subjects using the multiple regression analysis. RESULTS: Tibial internal rotation was significantly increased in full extension (p < 0.01 and <0.001, respectively) and at 60° and 90° flexion (p < 0.05) after PCL resection, which further increased after implantation, compared with that before resection. The amount of tibial internal rotation from 90° flexion to maximum flexion was significantly decreased after PCL resection and implantation, compared with that before resection (p < 0.05). The internal changes in the rotational alignment were independent factors for the minimal improvement in the post-operative maximum flexion angles (R 2 = 0.078, p = 0.0067). CONCLUSION: PCL resection changed the tibial rotational alignment and decreased the amount of tibial internal rotation. The implantation of PS components further increased the internal rotational alignment and could not compensate for the tibiofemoral rotation. Finally, the internal changes in rotational alignment affected the improvement of the maximum flexion angles, suggesting that rotational alignment is an important factor for improving post-operative maximum flexion angles. LEVEL OF EVIDENCE: II.

Posterior Reference Position Affects Intraoperative Kinematic and Soft Tissue Balance in Navigated Posterior-Stabilized Total Knee Arthroplasty.

BACKGROUND: The importance of medial compartment stability is recognized in total knee arthroplasty (TKA). To manage the medial extension-flexion gap, the posterior reference position can be changed from conventional posterior center to posterior medial in measured resection techniques. This study aimed to compare the intraoperative soft tissue balance and rotational kinematics between the posterior medial and posterior center reference groups. METHODS: We enrolled 57 consecutive patients with varus osteoarthritis undergoing posterior-stabilized (PS) TKA using an image-free navigation system. The detailed surgical plan in both groups and intraoperative kinematics were recorded using navigation, and soft tissue balance measured with an offset-type tensor was statistically compared between groups. RESULTS: Patients were divided into the posterior center reference group (n = 32) and posterior medial reference group (n = 25). The posterior medial and posterior lateral condyles were significantly thicker in the posterior center reference group (P < .05). Although preoperative rotational kinematics were comparable between groups, the tibial rotational position was significantly more externally rotated in the posterior center reference group than in the posterior medial reference group at 45°, 60°, and 90° of flexion (P < .05). The varus angle and joint component gap were significantly smaller in the posterior medial reference group than in the posterior center reference group at 60° and 90° of flexion (P < .05). CONCLUSION: The posterior reference position affects intraoperative kinematics and soft tissue balance in navigated PS TKA. Posterior medial reference PS TKA decreases the excessive tibial external rotation during midflexion and increases the flexion stability compared with conventional posterior center reference PS TKA.

A prospective randomized comparative study to determine appropriate edoxaban administration period, to prevent deep vein thromboembolism in patients with total knee arthroplasty.

BACKGROUND: This study aimed to determine the appropriate administration duration of edoxaban 15 mg (a factor Xa inhibitor) for the prevention of deep vein thrombosis (DVT) after total knee arthroplasty (TKA). METHODS: Our study comprised 202 patients who underwent TKA (excluding bilateral TKA) at our institution between 2014 and 2015. The subjects received edoxaban 15 mg daily for 1 (n = 93) or 2 (n = 109) weeks; group assignment was random. B-mode ultrasonography was performed 7 and 14 days post-TKA for the detection of DVT. We compared the incidence of DVT between the groups and examined for side effects. RESULTS: The demographic data of the patients in the 1- and 2-week administration groups were similar at baseline. DVT incidence did not differ significantly between the groups at 1 week post-TKA. However, it was significantly lower in the 2-week administration group (n = 0) than in the 1-week administration group (n = 7; p = 0.004) at 2 weeks post-DVT. Neither group exhibited symptomatic DVT. A total of six patients withdrew during the study period because of hepatic dysfunction. CONCLUSIONS: Our results show that the administration of edoxaban 15 mg is more effective in preventing DVT after TKA when administered for 2 weeks than for 1 week.

Computer-assisted surgery prevents complications during peri-acetabular osteotomy.

PURPOSE: The aim of study is to evaluate the accuracy of a navigation system during curved peri-acetabular osteotomy (CPO). METHODS: Forty-seven patients (53 hips) with hip dysplasia were enrolled and underwent CPO with or without navigation during surgery. Clinical and radiographical evaluations were performed and compared between the navigation group and non-navigation group, post-operatively. RESULTS: The clinical outcomes were not significantly different between the navigation and non-navigation groups. Furthermore, post-operative reorientation of the acetabular fragment was similar between the navigation and non-navigation groups. However, the discrepancy between the pre-operative planning line and post-operative osteotomy line was significantly improved in the navigation group compared with that in the non-navigation group (p < 0.05). Further, the complication rate was significantly improved in the navigation group (p < 0.001). CONCLUSION: The accuracy of the osteotomy's position was significantly improved by using the navigation. Therefore, the use of navigation during peri-acetabular osteotomy can avoid complications.

Prothrombin time-international normalized ratio is a useful marker for edoxaban efficacy in preventing venous thromboembolism after total knee arthroplasty.

BACKGROUND: Deep vein thrombosis (DVT) is one of the main complications following total knee arthroplasty (TKA). In this study, oral administration of 15 mg edoxaban (a factor Xa inhibitor) once daily for 14 days efficiently prevented the incidence of DVT. Our hypothesis was that prothrombin time-international normalized ratio (PT-INR) on the third postoperative day could predict the incidence of DVT following TKA. METHODS: In this study, 286 subjects were enrolled and divided into two groups according to the presence or absence of DVT. Several variables [age, body mass index, postoperative D-dimer level, PT-INR, and functional recovery findings (standing)] were analysed to determine the predictors of DVT, and for DVT diagnosis, ultrasonography was performed for seven days after surgery. RESULTS: The PT-INR levels were significantly higher in the group that did not develop DVT (p = 0.01). Further analysis with logistic regression analysis and receiver operating characteristic curve was performed. The PT-INR on the third postoperative day was an independent factor of the incidence of DVT (odds ratio 0.210; p = 0.035). The cut-off PT-INR was calculated to be 1.425. CONCLUSION: PT-INR level is a useful marker in determining whether 15 mg edoxaban administration can prevent DVT after TKA. It is suggested that increment of edoxaban to control PT-INR over the cut-off point might prevent the incidence of DVT.

Effects of Suture and Tourniquet on Intraoperative Kinematics in Navigated Total Knee Arthroplasty.

BACKGROUND: To investigate the effects of suture (soft tissue closure) and air tourniquet use on intraoperative kinematics in navigated total knee arthroplasty. METHODS: The study included 20 patients with varus-type knee osteoarthritis who underwent primary posterior-stabilized total knee arthroplasty using computed tomography (CT)-based navigation. Intraoperative tibiofemoral kinematics from maximum extension to maximum flexion were measured using the computed tomography-based navigation. The measurements were performed 3 times as follows: measurement 1: before suture (tourniquet on), measurement 2: after suture (tourniquet on), and measurement 3: after tourniquet removal. Details of kinematics including knee joint gap, tibiofemoral rotational angles, and anteroposterior (AP) distance between the femur and tibia were compared among the 3 measurements and statistically evaluated. RESULTS: On the medial side, there was no significant difference among the 3 measurements in the extension gap, but measurement 1 showed a significantly larger flexion gap compared with the other 2 measurements. On the lateral side, there was no significant difference between the extension and flexion gaps in all measurements. The anteroposterior distance in measurement 1 showed that the femur was positioned significantly more anterior to the tibia at 10° and 20° of flexion compared with the other 2 measurements after suture. There was no significant difference among the 3 measurements in the tibiofemoral rotation angles. CONCLUSION: These results found that the effect of suture and tourniquet was minimal, and that intraoperative kinematics can effectively evaluate postoperative passive kinematic conditions.

Relationship between trunk function evaluated using the trunk righting test and physical function in patients with knee osteoarthritis.

[Purpose] The present study was to validate the importance of the trunk function evaluated by trunk righting test (TRT) with motor function in patients with knee osteoarthritis (OA) and to show the clinical use of TRT. [Subjects and Methods] This study included 50 patients with knee osteoarthritis who underwent total knee arthroplasty in our hospital. Correlations between physical functional test, such as muscle strength, balance function, and performance and TRT were statistically evaluated. [Results] The independent factors for ipsilateral TRT were maximal isometric knee extensor strength test and ipsilateral step test. The operator and non-operator side TRT were significantly associated with TUG. [Conclusion] The results showed that the physical functions are correlated with the trunk function evaluated by TRT of patients with knee OA, suggesting that healthcare workers must take into consideration the trunk function, as well as lower extremity function to improve physical function.

Navigation-based femorotibial rotation pattern correlated with flexion angle after total knee arthroplasty.

PURPOSE: To investigate whether intraoperative kinematics obtained by navigation systems can be divided into several kinematic patterns and to assess the correlation between the intraoperative kinematics with maximum flexion angles before and after total knee arthroplasty (TKA). METHOD: Fifty-four posterior-stabilised (PS) TKA implanted using an image-free navigation system were evaluated. At registration and after implantation, tibial internal rotation angles at maximum extension, 30°, 45°, 60°, 90°, and maximum flexion were collected. The rotational patterns were divided into four groups and were examined the correlation with maximum flexion before and after operation. RESULTS: Tibial internal rotation from 90° of flexion to maximum flexion at registration was correlated with maximum flexion angles pre- and postoperatively. The four groups showed statistically different kinematic patterns. The group with tibial external rotation up to 90° of flexion, following tibial internal rotation at registration, achieved better flexion angles, compared to those of another groups (126.7° ± 12.0°, p < 0.05). The group with tibial external rotation showed the worst flexion angles (80.0° ± 40.4°, p < 0.05). Furthermore, the group with limited extension showed worse flexion angles (111.6° ± 8.9°, p < 0.05). CONCLUSION: Navigation-based kinematic patterns found at registration predict postoperative maximum flexion angle in PS TKA. Navigation-based kinematics can be useful information during TKA surgery. LEVEL OF EVIDENCE: Diagnostic studies, development of diagnostic criteria in a consecutive series of patients and a universally applied "gold" standard, Level II.

Navigation-based tibial rotation at 90° of flexion is associated with better range of motion in navigated total knee arthroplasty.

PURPOSE: In clinical practice, people with better femorotibial rotation in the flexed position often achieve a favourable postoperative maximum flexion angle (MFA). However, no objective data have been reported to support this clinical observation. In the present study, we aimed to investigate the correlation between the amount of intraoperative rotation and the pre- and postoperative flexion angles. METHODS: Fifty-five patients with varus osteoarthritis undergoing computer-assisted posterior-stabilized total knee arthroplasty (TKA) were enrolled. After registration, rotational stress was applied towards the knee joint, and the rotational angles were recorded by using a navigation system at maximum extension and 90° of flexion. After implantation, rotational stress was applied for a second time, and the angles were recorded once more. The MFA was measured before surgery and 1 month after surgery, and the correlation between the amount of femorotibial rotation during surgery and the MFA was statistically evaluated. RESULTS: Although the amount of tibial rotation at maximum extension was not correlated with the MFA, the amount of tibial rotation at 90° of flexion after registration was positively correlated with the pre- and postoperative MFA (both p < 0.005). However, no significant relationship was observed between the amount of tibial rotation after implantation and the postoperative MFA (n.s.). CONCLUSION: The results showed that better femorotibial rotation at 90° of flexion is associated with a favourable postoperative MFA, suggesting that the flexibility of the surrounding soft tissues is an important factor for obtaining a better MFA, which has important clinical relevance. Hence, further evaluation of navigation-based kinematics during TKA may provide useful information on MFA. LEVEL OF EVIDENCE: Diagnostic studies, development of diagnostic criteria in a consecutive series of patients, and a universally applied "gold" standard, Level II.

Periarticular multimodal drug injection improves post-operative pain and functional recovery after total knee arthroplasty.

BACKGROUND: This study retrospectively compared the clinical benefits of periarticular multimodal drug injection (PMDI) and continuous femoral nerve block (CFNB) after total knee arthroplasty (TKA). METHODS: From 2010 to 2012, 520 primary TKAs were performed, and patients were treated with CFNB or PMDI after surgery. Patients who underwent simultaneous bilateral TKA were excluded, leaving 185 and 166 patients in the CFNB and PMDI groups, respectively. Numeric rating scale for pain (NRS) scores and analgesic consumption were evaluated to compare the effectiveness of pain control between the groups. Further, range of motion (ROM), extension lag, the time to recovery of functions, and postoperative C-reactive protein (CRP) levels were monitored. Complications such as deep infection were assessed. RESULTS: The PMDI group displayed a significantly smaller NRS score on postoperative day (POD) 1 and lower analgesic consumption on PODs 0 and 1. The times to functional recovery were significantly shorter and the extension lag was smaller in the PMDI group. Furthermore, CRP levels were lower in the PMDI group by POD 7. No obvious deep infections were noted. CONCLUSION: Our results indicate that PMDI induced earlier functional recovery after TKA than CFNB, partially via its analgesic effect.

Factors affecting intraoperative kinematic patterns and flexion angles in navigated total knee arthroplasty.

PURPOSE: To investigate the factors affecting intraoperative kinematics, as measured with a navigation system, and their effect on maximum flexion angles during total knee arthroplasty (TKA). METHOD: One hundred posterior stabilised (PS) TKAs performed using an image-free navigation system were evaluated. Tibial internal rotation angles at maximum extension, 30°, 45°, 60°, 90°, and maximum flexion were collected at registration and after implantation. The varus angles from the coronal mechanical axis were also collected. The rotational patterns were divided into four groups to investigate whether flexion contracture and varus deformity affected the kinematic patterns, and correlated with the maximum pre- and post-operative flexion angles. RESULTS: At registration, the flexion angles at maximum extension differed significantly between the kinematic groups; the flexion angle at maximum extension at registration was negatively correlated with the pre-operative maximum flexion angle (R(2) = 0.226, p < 0.0001) and the post-operative maximum flexion angle (R(2) = 0.059, p = 0.0167). Varus deformity at registration also differed significantly between the kinematic groups; varus deformity at registration was negatively correlated with the pre-operative maximum flexion angle (R(2) = 0.087, p = 0.0036) and post-operative maximum flexion angle (R(2) = 0.101, p = 0.0027). CONCLUSION: Navigation-based measurements in patients undergoing PS TKA indicated that pre-operative flexion contracture and varus deformity are negatively correlated with both pre- and post-operative maximum flexion angles. The results may improve the ease with which surgeons can interpret intraoperative kinematics, by providing a multi-dimensional perspective. With further knowledge regarding intraoperative kinematics, it might be possible to improve surgical approach, prosthesis design, and clinical outcomes. LEVEL OF EVIDENCE: II.