Autocitrullination confers monocyte chemotactic properties to peptidylarginine deiminase 4.

Peptidylarginine deiminase 4 (PAD4) contributes to the production of citrullinated proteins as autoantigens for anti-citrullinated protein antibodies (ACPAs) in rheumatoid arthritis (RA). PAD4 can also self-deiminate via autocitrullination. However, the role of this process in RA pathogenesis has not been elucidated. This study aimed to clarify PAD4 function before and after autocitrullination and identify citrullinated PAD4 in the synovial fluid of patients with RA. The autocitrullination of recombinant human PAD4 (rhPAD4) was catalyzed in vitro and determined using anti-modified citrulline immunoblotting. Monocyte chemotaxis was evaluated using Boyden chambers, and citrullinated rhPAD4's ability to induce arthritis was assessed in a C57BL/6J mouse model. Citrullinated PAD4 levels were measured in the synovial fluid of patients with RA and osteoarthritis using a novel enzyme-linked immunosorbent assay. Chemotactic findings showed that citrullinated rhPAD4 recruited monocytes in vitro, whereas unmodified rhPAD4 did not. Compared to unmodified rhPAD4, citrullinated rhPAD4 induced greater inflammation in mouse joints through monocyte migration. More citrullinated PAD4 was found in the synovial fluid of patients with RA than in those with osteoarthritis. Citrullinated PAD4 was even detected in ACPA-negative patients with RA. The autocitrullination of PAD4 amplified inflammatory arthritis through monocyte recruitment, suggesting an ACPA-independent role of PAD4 in RA pathogenesis.

Mass spectrometric quantitation of AGEs and enzymatic crosslinks in human cancellous bone.

Advanced glycation end-products (AGEs) deteriorate bone strength. Among over 40 species identified in vivo, AGEs other than pentosidine were roughly estimated as total fluorescent AGEs (tfAGEs) due to technical difficulties. Using LC-QqTOF-MS, we established a system that enabled the quantitation of five AGEs (CML, CEL, MG-H1, CMA and pentosidine) as well as two mature and three immature enzymatic crosslinks. Human bone samples were collected from 149 patients who underwent total knee arthroplasty. Their clinical parameters were collected to investigate parameters that may be predictive of AGE accumulation. All the analytes were quantitated and showed significant linearity with high sensitivity and precision. The results showed that MG-H1 was the most abundant AGE, whereas pentosidine was 1/200-1/20-fold less abundant than the other four AGEs. The AGEs were significantly and strongly correlated with pentosidine, while showing moderate correlation with tfAGEs. Interestingly, multiple linear regression analysis revealed that gender contributed most to the accumulation of all the AGEs, followed by age, tartrate-resistant acid phosphatase-5b and HbA1c. Furthermore, the AGEs were negatively correlated with immature crosslinks. Mass spectrometric quantitation of AGEs and enzymatic crosslinks is crucial to a better understanding of ageing- and disease-related deterioration of bone strength.

Impact of posterior femoral condylar cartilage and posterior intercondylar distance on rotation of femoral component in total knee arthroplasty.

BACKGROUND: Greater accuracy is needed when determining the final femoral component (FC) rotation during total knee arthroplasty (TKA), because this parameter affects soft tissue balance during flexion and patellar tracking. Anatomical markers, such as the epicondylar axis, are typically used to determine the final FC rotation, although intraoperative confirmation may be challenging. Therefore, rotational position is frequently determined with the posterior condylar axis (PCA) as a landmark. However, the thickness of the posterior condylar cartilage has not been considered and may not be represented on preoperative images. We used plain X-rays to measure the thickness of the medial and lateral posterior condylar cartilage fragments postoperatively, and investigated the effects of differences in cartilage thickness on final FC rotation. METHODS: Fifty knees (19 men, 31 women) underwent primary TKA to treat medial knee osteoarthritis at our hospital between August 2015 and May 2017. All knees were treated using an Attune PS (DePuy Synthes, Inc., Warsaw, IN). We first measured the distance between the posterior femoral condyles, resected the posterior condyle, and measured the thickness of the resected cartilage fragments. We then took X-ray images from a direction tangential to the osteotomy surface, secured the cartilage fragments with digital calipers, and measured the thickness of the cartilage. We investigated the effects of differences in cartilage thickness on final FC rotation of the residual medial and lateral cartilage with a trigonometric function. RESULTS: Medial condylar cartilage thickness averaged 0.6 ± 0.5 mm and the lateral condylar thickness averaged 1.8 ± 0.6 mm; posterior intercondylar distance averaged 46.1 ± 3.3 mm and average impact on rotation of the cartilage remnant was 1.5 ± 0.9° (- 0.1-3.9°). There may be measurement error of up to 4° in the maximum values compared with the preoperative plan in cases with short intercondylar distance. CONCLUSIONS: In cases where the FC external rotation angle is determined using the posterior condyles as landmarks, this angle can be affected by the intercondylar distance, especially in Japanese women who have small physical stature. This angle can potentially be much larger, so caution is advised. Our results suggest that several anatomical landmarks should be referenced to achieve accurate FC rotation.

Pre-operative hemoglobin level and use of sedative-hypnotics are independent risk factors for post-operative delirium following total knee arthroplasty.

BACKGROUND: Delirium is a well-known complication following surgery, especially with the increasing age of patients undergoing surgery. The increasing demands resulting from a prolonged healthy life expectancy has resulted in more arthroplasties despite their age and existing comorbidities. The purpose of this study is to explore the various risk factors that may contribute to delirium in unilateral and bilateral total knee arthroplasties in the elderly population. METHODS: 170 patients who underwent unilateral or bilateral total knee arthroplasties were analyzed retrospectively for delirium. Age, sex, comorbidities, use of sedative-hypnotics, peri-operative blood loss, pre- and post-operative laboratory blood test results were investigated and analyzed. RESULTS: The incidence of post-operative delirium was 6.5% (11 out of 170 patients) with a mean age of 79.5 (± 6.9) years, compared to 73.0 (± 9.0) years in the non-delirium group. Higher age, use of sedative-hypnotics, low pre-operative Hb and Ht, low post-operative Hb, Ht and BUN were observed in the delirium group. Multivariate logistic regression analysis identified that the use of sedative-hypnotics and pre-operative Hb level were independent risk factors for post-operative delirium after TKA. The odds ratios for the use of sedative-hypnotics and pre-operative Hb level were 4.6 and 0.53, respectively. Receiver operating characteristic curve analysis showed that pre-operative Hb of less than 11.1 g/dL was a predictor for the development of delirium, with a sensitivity of 54.6% and a specificity of 91.6%. CONCLUSION: Patients with a pre-operative Hb level of < 11.1 g/dL or those using sedative-hypnotics are associated with post-operative delirium. Peri-operative management and preventative measures are therefore needed to reduce the risks of post-operative delirium in such patients.

Enhancement of tendon-bone interface healing and graft maturation with cylindrical titanium-web (TW) in a miniature swine anterior cruciate ligament reconstruction model: histological and collagen-based analysis.

BACKGROUND: Tendon-bone interface healing and ligamentization of the graft in anterior cruciate ligament (ACL) reconstruction with autografts are important factors affecting treatment outcome. This study aimed to investigate the effectiveness of a cylindrical titanium-web (TW) in tendon-bone interface healing and graft maturation in ACL reconstruction. METHODS: Fourteen mature female CLAWN miniature swine underwent bilateral ACL reconstructions with patellar tendon (PT) autografts. In one limb, the TW/tendon complex was placed into the proximal side of the tibial tunnel. Only the graft was transplanted into the tunnel in the control limb. The proximal side of the graft was sutured into the stump of the native ACL and the distal end was stapled to the tibia. The animals were euthanized at 4 and 15 weeks postoperatively, for histological and biochemical analyses. RESULTS: Microscopic images in TW limbs showed that ingrowth of tendon-like tissue and mineralized bone tissue into the TW connected the bone and the tendon directly. In contrast, fibrous tissue intervened between the bone and tendon in the control limbs. The total amount of collagen cross-links (which defines the strength of collagen fibers) and the maturation of collagen cross-links in TW tendons were significantly higher (p < 0.05) than those of control limbs. There was no significant difference in the ratio of dihydroxy-lysinonorleucine to hydroxy-lysinonorleucine (an indicator of tissue specific collagen maturation) between TW tendons and that of the native PT. CONCLUSIONS: TW promoted the maturation and formation of collagen cross-links in the grafted tendon while maintaining the cross-links pattern of native tendon collagen, and enabled direct binding of tendon to bone.

Positioning the femoral bone socket and the tibial bone tunnel using a rectangular retro-dilator in anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate the positions of femoral bone sockets and tibial bone tunnels made with the rectangular retro-dilator (RRD), which we manufactured for anterior cruciate ligament reconstruction (ACLR) with a bone-patella tendon-bone (BPTB) graft which is fixed into the rectangular bone socket and tunnel made at anatomical ACL insertion sites. METHODS: 42 patients who had undergone ACLR with BPTB using the RRD were evaluated to assess bone socket and tunnel positions by the quadrant method and Magnussen classification using three-dimensional (3-D) CT. Intra-operative complications were also investigated in all patients. RESULTS: 3-D CT of the operated knee joints using the RRD showed that the bone socket and tunnel were placed in anatomical positions. In the quadrant method, the mean position of the femoral bone socket aperture was located at 22.0 ± 4.2% along the Blumensaat's line, and 37.4 ± 7.2% across the posterior condylar rim. The mean positions of the tibial bone tunnel aperture were 37.7 ± 5.2% and 46.1 ± 2.2% antero-posteriorly and medio-laterally, respectively. In addition, according to the Magnussen classification, 39 cases were evaluated as type 1, and almost all were located behind the lateral intercondylar ridge (also known as the resident's ridge). 3 cases were classified as type 2, which overlapped with the resident's ridge. A partial fracture of BPTB bone fragment was observed in 2 patients, but no serious complications including neurovascular injury were observed. CONCLUSION: The study indicates that the use of RRD achieves a safe anatomical reconstruction of the ACL.

Anterior Cruciate Ligament Reconstruction With Bone-Patellar Tendon-Bone Graft Through a Rectangular Bone Tunnel Made With a Rectangular Retro-dilator: An Operative Technique.

Good clinical results have been reported with anatomic anterior cruciate ligament (ACL) reconstructions in which rectangular bone-patellar tendon-bone (BTB) grafts were fixed into rectangular bone tunnels made at anatomic ACL insertion sites of the femur and tibia (anatomic rectangular tunnel BTB ACL reconstruction). Notwithstanding these good results, some problems have remained unsolved, including procedural complexity and risk of damage to the femoral posterior tunnel wall, damage to nerves and blood vessels, and damage to cartilage. The purpose of this report is to present our technique of ACL reconstruction with BTB graft through a rectangular bone tunnel made with a rectangular retro-dilator. Our procedure may become a safe option for anatomic rectangular tunnel BTB ACL reconstruction because of the following advantages: (1) bone tunnels can be created more safely and accurately than in methods using transtibial and far medial portals, (2) the bone tunnel preparation procedure is less invasive than the standard outside-in method, (3) technical failure-related risks are lower because the guidewire is inserted only once, and (4) the operation time is shorter because the method is a single-bundle procedure.

Accuracy of Computed Tomography-Based Navigation-Assisted Total Knee Arthroplasty: Outlier Analysis.

BACKGROUND: Achieving neutral limb alignment during total knee arthroplasty (TKA) has been identified as a potential factor in long-term prosthesis survival. This study aimed to analyze the accuracy of component orientation and postoperative alignment of the leg after computed tomography (CT)-based navigation-assisted TKA, compare these parameters with those of a conventional technique, and analyze differences in the data of outliers. METHODS: We retrospectively compared the alignment of 130 TKAs performed with a CT-based navigation system with that of 67 arthroplasties done with a conventional system. The knee joints were evaluated using radiographs. RESULTS: Mean hip-knee-ankle (HKA) angle, frontal femoral component angle, and frontal tibial component angle were 180.7°, 88.8°, and 90.6°, respectively, for the navigation-assisted arthroplasties and 181.1°, 88.7°, and 90.2°, respectively, for the conventional arthroplasties. All preoperative leg axes of 10 outliers in the navigation group were >193°, whereas the data of 17 outliers in the conventional group were scattered. CONCLUSION: This study demonstrates significant improvements in component positioning with the CT-based navigation system. Furthermore, when analyzing cases with preoperative HKA angles ≤192°, no outliers were found in the navigation group, indicating high alignment accuracy. However, in cases with preoperative HKA angles ≥193°, outliers were found in both groups, and no significant difference between the groups was observed (P = .08). Detailed analysis of the outlier cases in the navigation group revealed that the femoral component was placed in the varus position. These findings indicate that the varus knee is an important factor influencing accurate positioning of the femoral component and the postoperative leg axis.

Autoimmunity to citrullinated type II collagen in rheumatoid arthritis.

The production of autoantibodies to citrullinated type II collagen and the citrullination of type II collagen were analyzed in rheumatoid arthritis. Autoantibodies to citrullinated type II collagen were detected in 78.5% of serum samples from 130 rheumatoid arthritis patients. Autoantibodies to native noncitrullinated type II collagen were detected in 14.6% of serum samples, all of which were positive for anti-citrullinated type II collagen antibodies. Serum samples were also positive for anti-citrullinated type II collagen antibodies in 1 of 31 systemic lupus erythematosus patients and 2 of 55 patients with osteoarthritis of the knee. In contrast, sera samples from 24 systemic sclerosis patients, 21 dermatomyositis/polymyositis patients, 21 ankylosing spondylitis patients, and 18 psoriatic arthritis patients were all negative for anti-citrullinated type II collagen antibodies. Anti-citrullinated type II collagen antibodies and fragments of citrullinated type II collagen were found in the synovial fluid obtained from affected knee joints of 15 rheumatoid arthritis patients. Moreover, anti-citrullinated type II collagen antibodies were isolated from the synovium of affected knee joints in 8 rheumatoid arthritis patients using antigen/antibody immunocomplex dissociation buffer but not by using standard buffers. These findings indicate that autoantibodies that react with citrullinated type II collagen are specifically produced and that immunocomplexes composed of fragments of citrullinated type II collagen and autoantibodies are deposited in the inflamed articular synovium in rheumatoid arthritis patients. Assaying for the presence of anti-citrullinated type II collagen antibodies may therefore be useful for diagnosing rheumatoid arthritis, and the deposition of these immunocomplexes in the articular synovium may be involved in pathogenesis.

MRI study of bioabsorbable poly-L-lactic acid devices used for fixation of fracture and osteotomies.

BACKGROUND: The overall clinical results of bioabsorbable fixation devices made of poly-L-lactic acid (PLLA) used for fixation of fractures, bone grafting, and osteotomies have been favorable. However, clinical studies demonstrated no sign of normal bony architecture restored after surgery, although implant channels had been filled with fibrous tissue. The purpose of the present retrospective study was to examine the extent of structural changes in PLLA devices (PLLA-Ds) for fixation of rotational acetabular osteotomies and displaced malleolar ankle fractures using magnetic resonance imaging (MRI). METHODS: Altogether, 14 patients with osteoarthritis of hip joints and 15 with displaced malleolar ankle fractures were operated on using PLLA-D (NEOFIX). Of these patients, 22 were finally enrolled in the study, and the period from operation to the time of the study ranged from 17 to 78 months. The postoperative radiographic findings were evaluated for union, and changes around the implant holes were classified as sclerosis, resorption, or no change. MRI was carried out to estimate changes in the PLLA-Ds. RESULTS: Bone union was obtained in all cases; clinical complications such as infection, joint effusion, soft tissue irritation due to PLLA-D deviation, and motion pain in the joints were not observed. The MRI study suggested that water content in PLLA-D increased mainly due to biodegradation and that implants were not replaced by bony tissue. CONCLUSIONS: The PLLA-Ds were degraded but were not replaced by bony tissue during the observation period. Considering these findings and the assumption that in bony tissues mechanical strength of PLLA-D decreases with time, attention should be paid to mechanical insufficiency, which may occur when the cross-sectional area of a PLLA-D extends beyond the cross-sectional area of the osteosynthesis site.