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ABSTRACT: We hypothesized that the tibial plafond revealed a novel anatomical reference axis associated with the axial alignment through an image processing technique. The plafond axis (PLA) was defined as the line connecting the midpoints of the medial and lateral plafond margin. In terms of intraclass correlation coefficient, the reproducibility to identify the PLA was not less than that to identify a conventional trans-malleolar axis (TMA). When the proximal medial-lateral axis was applied, the tibial torsion with reference to the PLA and the TMA was 12.0°±8.4°, and 23.3°±8.6°, respectively. The PLA can be considered a reproducible reference and is expected to be applicable in preoperative planning as well as postoperative evaluation of the implant alignment in total knee arthroplasty.
The Journal of arthroplasty 03/2013; · 1.79 Impact Factor
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ABSTRACT: We present a case of an 8-year-old boy diagnosed with melorheostosis who was suffering from severe genu valgum, permanent dislocation of the patella, knee flexion contracture and leg length shortening. Soft tissue contracture of the limb and subsequent joint deformities were reported to represent clinical manifestations of pediatric melorheostosis. As the epiphyseal plate had not closed, patellar reduction was achieved by soft tissue surgical stabilization, including lateral retinacular release, medial retinaculum plication, and transfer of the lateral half of the patellar tendon. At 4years postoperatively, as a result of improved limb alignment and knee flexion contracture, the leg length shortening has improved, and the patient does not limp and participates in sports activities. Surgical intervention should be performed as early as possible, because genu valgum and external rotation of the tibia may deteriorate with age, rendering the patellar dislocation irreversible in patients with melorheostosis before epiphyseal closure.
The Knee 01/2013; · 1.74 Impact Factor
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ABSTRACT: BACKGROUND: Consensus has been lacking as to how to reconstruct the posterolateral corner (PLC) of the knee in patients with posterolateral instability. We describe a new reconstructive technique for PLC based on Larson's method, which reflects the physiological load-sharing pattern of the lateral collateral ligament (LCL) and popliteofibular ligament (PFL). FINDINGS: Semitendinosus graft is harvested, and one limb of the graft comprises PFL and the other comprises LCL. Femoral bone tunnels for the LCL and popliteus tendon are made at their anatomical insertions. Fibular bone tunnel is prepared from the anatomical insertion of the LCL to the proximal posteromedial portion of the fibular head, which corresponds to the insertion of the PFL. The graft end for popliteus tendon is delivered into the femoral bone tunnel and secured on the medial femoral condyle. The other end for LCL is passed through the fibular tunnel from posterior to anterior. While the knee is held in 90 of flexion, the graft is secured in the fibular tunnel using a 5 mm interference screw. Then, the LCL end is passed into the femoral bone tunnel and secured at the knee in extension. CONCLUSIONS: Differential tension patterns between LCL and PFL is critical when securing these graft limbs. Intrafibular fixation of the graft using a small interference screw allows us to secure these two graft limbs independently with intended tension at the intended flexion angle of the knee.
Sports Medicine Arthroscopy Rehabilitation Therapy & Technology 06/2012; 4(1):21.
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Masanori Nakayama, Yasuo Niki,
Toshiki Kawasaki,
Yuki Takeda,
Keisuke Horiuchi,
Aya Sasaki,
Yasunori Okada,
Kazuo Umezawa,
Hiroyasu Ikegami,
Yoshiaki Toyama,
Takeshi Miyamoto
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ABSTRACT: The present study assessed the potential functions of interleukin (IL)-32α on inflammatory arthritis and endotoxin shock models using IL-32α transgenic (Tg) mice. The potential signaling pathway for the IL-32-tumor necrosis factor (TNF)α axis was analyzed in vitro.
IL-32α Tg mice were generated under control of a ubiquitous promoter. Two disease models were used to examine in vivo effects of overexpressed IL-32α: Toll-like receptor (TLR) ligand-induced arthritis developed using a single injection of lipopolysaccharide (LPS) or zymosan into the knee joints; and endotoxin shock induced with intraperitoneal injection of LPS and D-galactosamine. TNFα antagonist etanercept was administered simultaneously with LPS in some mice. Using RAW264.7 cells, in vitro effects of exogenous IL-32α on TNFα, IL-6 or macrophage inflammatory protein 2 (MIP-2) production were assessed with or without inhibitors for nuclear factor kappa B (NFκB) or mitogen-activated protein kinase (MAPK).
Single injection of LPS, but not zymosan, resulted in development of severe synovitis with substantial articular cartilage degradation in knees of the Tg mice. The expression of TNFα mRNA in inflamed synovia was highly upregulated in the LPS-injected Tg mice. Moreover, the Tg mice were more susceptive to endotoxin-induced lethality than the wild-type control mice 48 hours after LPS challenge; but blockade of TNFα by etanercept protected from endotoxin lethality. In cultured bone marrow cells derived from the Tg mice, overexpressed IL-32α accelerated production of TNFα upon stimulation with LPS. Of note, exogenously added IL-32α alone stimulated RAW264.7 cells to express TNFα, IL-6, and MIP-2 mRNAs. Particularly, IL-32α -induced TNFα, but not IL-6 or MIP-2, was inhibited by dehydroxymethylepoxyquinomicin (DHMEQ) and U0126, which are specific inhibitors of nuclear factor kappa B (NFκB) and extracellular signal regulated kinase1/2 (ERK1/2), respectively.
These results show that IL-32α contributed to the development of inflammatory arthritis and endotoxin lethality. Stimulation of TLR signaling with LPS appeared indispensable for activating the IL-32α-TNFα axis in vivo. However, IL-32α alone induced TNFα production in RAW264.7 cells through phosphorylation of inhibitor kappa B (IκB) and ERK1/2 MAPK. Further studies on the potential involvement of IL-32α-TNFα axis will be beneficial in better understanding the pathology of autoimmune-related arthritis and infectious immunity.
Arthritis research & therapy 05/2012; 14(3):R120. · 4.27 Impact Factor
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ABSTRACT: Several biomarkers have been used to evaluate osteoarthritis of the limb joints. Here we evaluated the use of serum cartilage metabolites as biomarkers for degenerative lumbar scoliosis (DLS). Fifty-two DLS patients with Cobb angle > 10° were compared with 19 control patients. Serum levels of hyaluronic acid (HA), keratan sulfate (KS), cartilage oligomeric matrix protein (COMP), collagen type II cleavage (C2C), and procollagen type II C-propeptide (CPII) were measured. Serum levels of KS (DLS 1.20 ± 0.44 µg/ml vs. control 0.98 ± 0.33 µg/ml), CPII (DLS 1905.1 ± 948.2 ng/ml vs. control 1223.6 ± 884.4 ng/ml), and C2C (DLS 219.1 ± 59.2 ng/ml vs. control 177.7 ± 71.7 ng/ml) were significantly higher in DLS. There were no significant differences in the levels of HA or COMP. There was a significant positive correlation between the Cobb angle and CPII in DLS. This is the first study to evaluate the cartilage biomarkers in DLS. The results suggest DLS patients have higher levels of type II collagen synthesis and degradation, indicated by elevated serum CPII and C2C, respectively. As type II collagen is a major component of collagens in the nucleus pulposus and facet joint cartilages, its enhanced turnover may be related to the development and progression of DLS.
Journal of Orthopaedic Research 01/2012; 30(8):1249-53. · 2.81 Impact Factor
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ABSTRACT: With the current use of biologics in rheumatoid arthritis (RA), there is a need to monitor ongoing structural joint damage due to the dissociation of articular cartilage damage from disease activity of RA. This study longitudinally analyzed levels of serum cartilage biomarkers during 54 weeks of infliximab therapy, to evaluate the feasibility of biomarkers for monitoring structural joint damage.
Subjects comprised 33 patients with early RA and 33 patients with established RA. All patients received 3 mg/kg of infliximab and methotrexate for 54 weeks. Levels of the following serum cartilage markers were measured at baseline and at weeks 14, 22, and 54: hyaluronan (HA); cartilage oligometric matrix protein (COMP); type II collagen (CII)-related neoepitope (C2C); type II procollagen carboxy-propeptide (CPII); and keratin sulfate (KS). Time courses for each biomarker were assessed, and relationships between these biomarkers and clinical or radiographic parameters generally used for RA were investigated.
Levels of CRP, MMP-3, DAS28-CRP, and annual progression of TSS were improved to similar degrees in both groups at week 54. HA and C2C/CPII were significantly decreased compared to baseline in the early RA group (p<0.001), whereas HA and COMP, but not C2C/CPII, were decreased in the established RA group. Strikingly, serum C2C/CPII levels were universally improved in early RA, regardless of EULAR response grade. Both ΔHA and ΔC2C/CPII from baseline to week 54 correlated significantly with not only ΔCRP, but also ΔDAS28 in early RA. Interestingly, when partial correlation coefficients were calculated by standardizing CRP levels, the significant correlation of ΔHA to ΔDAS28 disappeared, whereas correlations of ΔC2C/CPII to ΔDAS28, ΔJNS, and ΔHAQ remained significant. These results suggest a role of ΔC2C/CPII as a marker of ongoing structural joint damage with the least association with CRP, and that irreversible cartilage damage in established RA limits restoration of the C2C/CPII level, even with tight control of joint inflammation.
The temporal course of C2C/CPII level during anti-TNF therapy indicates that CII turnover shifts toward CII synthesis in early RA, but not in established RA, potentially due to irreversible cartilage damage. ΔC2C/CPII appears to offer a useful marker reflecting ongoing structural joint damage, dissociated from inflammatory indices such as CRP and MMP-3.
PLoS ONE 01/2012; 7(5):e37447. · 4.09 Impact Factor
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ABSTRACT: The effects of surgical approaches and patellar positions on joint gap measurement during total knee arthroplasty (TKA) remain unclear. We hypothesized that joint gap changes with different knee flexion angles would not be consistent within four different approaches and two different patellar positions.
This study enrolled 80 knees undergoing posterior-stabilized TKA. For 60 varus knees, parapatellar, midvastus, and subvastus approaches were used in 20 knees each. For 20 valgus knees, a lateral subvastus approach was used. Component gap length and inclination were measured intra-operatively using a specific tensor device under 40 lb with the patella reduced or shifted laterally, at 0°, 45°, 90°, and 135° of knee flexion.
Mean gap lengths at 45° and 90° of knee flexion were significantly larger with the parapatellar approach than with midvastus or lateral subvastus approaches (P < 0.05). Regarding gap inclination, varus angle increased linearly through the entire arc of flexion in all four approaches. When the patella was shifted laterally, gap lengths at 45°, 90°, and 135° were significantly reduced compared with those for the patella reduced in the subvastus approach, whereas gap length was constant in the parapatellar approach, regardless of patellar position.
Joint gap kinematics was not consistent within four different approaches and two different patellar positions. Relatively large gaps at 45° and 90° were unique features for the parapatellar approach. Surgeons should be aware that the flexion gap is reduced when the patella is shifted laterally in vastus medialis-preserving approaches such as the subvastus approach.
II.
Knee Surgery Sports Traumatology Arthroscopy 12/2011; 20(10):2022-7. · 2.21 Impact Factor
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ABSTRACT: The purpose of this study was to evaluate the prevalence of anterior knee pain in anatomic double-bundle anterior cruciate ligament (ACL) reconstruction and to identify critical factors affecting postoperative anterior knee pain development.
Subjects comprised 171 patients (171 knees) who underwent anatomic double-bundle ACL reconstruction with a follow-up period of ≥2 years. The procedure used bone-patellar tendon-bone plus gracilis tendon (BTB-G) in 56 knees, semitendinosus tendon (ST) in 71 knees, and ST-G in 44 knees. Clinical results and prevalence and severity of anterior knee pain were assessed at 3 months and 2 years postoperatively. Clinical variables influencing anterior knee pain development at each postoperative period were subjected to univariate analysis, followed by logistic regression analysis to identify risk factors for anterior knee pain.
Overall prevalences of anterior knee pain at 3 months and 2 years postoperatively were 42.0 and 11.1%, respectively. Use of BTB-G graft represented the highest prevalence of anterior knee pain between the 3 different grafts (P = 0.001); however, this statistical significance disappeared at 2 years postoperatively. Prevalence of postoperative extension deficit was significantly higher in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 3 months postoperatively. Level of quadriceps strength was significantly lower, and Lysholm score was significantly worse in anterior knee pain-positive cohort than in anterior knee pain-negative cohort at 2 years postoperatively. According to logistic regression analysis, knee extension deficit was a predisposing factor for the development of anterior knee pain at 3 months postoperatively (odds ratio, 2.76; P = 0.004); however, there was no significant predisposing factor for anterior knee pain at 2 years postoperatively.
Knee extension deficit was an important predisposing factor for postoperative anterior knee pain in the early postoperative period, and anterior knee pain was associated with impaired quadriceps function and inferior subjective results over 2 years postoperatively. Early recovery of full extension may prevent postoperative development of anterior knee pain and achieve successful outcomes for ACL reconstruction.
Retrospective comparative study, Level III.
Knee Surgery Sports Traumatology Arthroscopy 11/2011; 20(8):1543-9. · 2.21 Impact Factor
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ABSTRACT: Vascular endothelial growth factor 165 (VEGF165) and its receptors, including neuropilin 1 (NRP-1), are overexpressed in human osteoarthritic (OA) articular cartilage, although their functional roles in the cartilage are not fully understood. An axon-guidance molecule, semaphorin 3A (Sema3A), which binds to NRP-1, acts as an antagonist of VEGF signaling in endothelial cells. The aim of this study was to examine the expression of Sema3A and the functions of the VEGF165/Sema3A/NRP-1 axis in OA cartilage.
The expression of Sema3A in OA and normal cartilage samples was examined by real-time polymerase chain reaction and immunohistochemical analyses. Functional analyses of VEGF165 and Sema3A were carried out using OA chondrocytes in culture. The migration activity of chondrocytes was examined in a monolayer wound assay. The effects of Sema3A on VEGF165-induced up-regulation of matrix metalloproteinases (MMPs) and intracellular signaling were also studied in cultured chondrocytes.
Sema3A expression was significantly elevated in OA cartilage as compared to normal cartilage. Sema3A immunoreactivity directly correlated with the Mankin score and with chondrocyte cloning. VEGF165 promoted the migration of chondrocytes, and this activity was suppressed by VEGF receptor 2 tyrosine kinase inhibitors. Sema3A antagonized the chondrocyte migration promoted by VEGF165, and the activity was blocked by a selective inhibitor of, or small interfering RNA for, Sema3A. VEGF165-induced overexpression of MMPs and phosphorylation of ERK and focal adhesion kinase in chondrocytes were inhibited by Sema3A.
Our findings provide the first evidence that Sema3A is overexpressed, with a direct correlation with cloning, in OA cartilage and that it suppresses the VEGF165-promoted migration of chondrocytes. Our findings also suggest that Sema3A plays a role in chondrocyte cloning through inhibition of cell migration in OA cartilage.
Arthritis & Rheumatism 10/2011; 63(10):3000-9. · 7.87 Impact Factor
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ABSTRACT: The purpose of this study was to assess the clinical results of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction by use of bone-patellar tendon-bone and gracilis tendon (BPTB-G) grafts and to compare them with the results of double-bundle ACL reconstruction by use of semitendinosus tendon (ST) or semitendinosus-gracilis tendon (ST-G) grafts, with particular emphasis on the postoperative incidence of anterior knee pain.
The study comprised 144 patients who underwent unilateral anatomic double-bundle ACL reconstruction with 3 graft types, including 55 BPTB-G, 56 ST, and 33 ST-G grafts. A traumatic graft rupture occurred within 2 years postoperatively in 5 patients (1 BPTB-G, 3 ST, and 1 ST-G). Clinical results and incidence and severity of anterior knee pain were assessed and compared among the 3 different graft groups at 2 years postoperatively. Potential variables influencing postoperative anterior knee pain development were subjected to univariate analysis, followed by logistic regression analysis to identify risk factors for anterior knee pain.
Both subjective and objective clinical results in anatomic double-bundle ACL reconstruction with BPTB-G graft were similar to those using ST or ST-G graft at 2 years postoperatively. The incidences of anterior knee pain at 2 years' follow-up were 18.5%, 9.4%, and 9.3% in the BPTB-G, ST, and ST-G groups, respectively, indicating no statistically significant difference among the 3 groups. Multivariate logistic regression analyses showed that BPTB graft harvest and patellofemoral cartilage defect failed to be significant factors for anterior knee pain whereas quadriceps peak torque at 60°/s was the only significant factor for anterior knee pain at 2 years.
Clinical results including the incidence of anterior knee pain 2 years after anatomic double-bundle ACL reconstruction with BPTB-G grafts were comparable to those after ACL reconstruction with ST or ST-G grafts.
Level III, therapeutic, retrospective comparative study.
Arthroscopy The Journal of Arthroscopic and Related Surgery 07/2011; 27(9):1242-51. · 3.02 Impact Factor
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Yasuo Niki
Knee Surgery Sports Traumatology Arthroscopy 06/2011; 19(9):1608-9; author reply 1610-11. · 2.21 Impact Factor
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ABSTRACT: With increasing confidence and surgical experience, minimally invasive surgery (MIS) in total knee arthroplasty (TKA) is now being applied to more complicated cases. The present study assessed the feasibility of MIS-TKA using a lateral approach for valgus knees.
Subjects comprised 26 patients with valgus knees who underwent MIS-TKA using a lateral subvastus approach. Five cases required a 1-cm snip of vastus lateralis obliquus, to shift the patella medially without eversion. Clinical scores and radiographic parameters of lateral MIS-TKA were examined and compared with those of 26 medial MIS-TKAs matched for preoperative patient characteristics.
The lateral MIS-TKA group showed slightly longer operative time and larger skin incision than the medial MIS-TKA group. Nevertheless, myoglobin index and pain on a visual analog scale on postoperative day 7 were significantly lower in the lateral MIS-TKA group than in the medial MIS-TKA group. Postoperative improvement of clinical scores was quite comparable between lateral and medial MIS-TKA groups. Radiographic assessment revealed that tibiofemoral mechanical axis aligned within ±3° from ideal in 24 of 26 patients after lateral MIS-TKA. MIS technique-related complications occurred in only 1 patient presenting with subsidence of the tibial component, due to malpositioning of the tibial component.
From the perspectives of postoperative pain, clinical scores, radiographic accuracy, and postoperative complication rate, lateral MIS-TKA achieved comparable or superior results to medial MIS-TKA. This technique may offer a promising technical option that can be utilized for most patients with valgus knee deformity.
Knee Surgery Sports Traumatology Arthroscopy 11/2010; 19(6):973-9. · 2.21 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the clinical results of single-stage revision anterior cruciate ligament reconstruction (ACLR) after synthetic ligament failure.
The subjects comprised 20 patients who underwent revision ACLR after synthetic ligament failure. All revisions were performed with bone-patellar tendon-bone graft, and bone tunnel expansion after removal of synthetic materials was treated with bone plugs sized and trimmed as necessary to fill the bone tunnels. Clinical results were assessed at a mean of 2.8 years postoperatively, followed by comparison with the results of 20 primary ACLRs selected as case-matched controls. Assessment included the Lysholm score, International Knee Documentation Committee (IKDC) evaluation, instrumented laxity testing, and radiologic examination.
Bone tunnel enlargement to 11 mm in diameter or greater was found in 10 of 20 revision ACLRs. However, favorable anteroposterior stability was obtained at final follow-up (1.4 +/- 2.0 mm in revision ACLR group and 1.5 +/- 1.5 mm in primary ACLR group). The overall Lysholm score improved significantly from preoperatively to final follow-up, but the revision ACLR group showed significantly worse results for the pain parameter than the primary ACLR group. The final IKDC results also showed significant postoperative improvement, but the number of cases with grade C was significantly higher in the revision ACLR group than in the primary ACLR group, which was attributed to radiologically confirmed osteoarthritis in the revision ACLR group.
Single-stage revision ACLR with bone-patellar tendon-bone graft after synthetic ligament failure yielded favorable results in terms of IKDC grade, Lysholm score, and anteroposterior stability, despite enlarged bone tunnels after removal of synthetic material. Inferior results for the radiologic and pain parameters of the IKDC and Lysholm scores were attributed to osteoarthritic changes inherent to the revision ACLR group.
Level III, therapeutic case-control study.
Arthroscopy The Journal of Arthroscopic and Related Surgery 08/2010; 26(8):1058-65. · 3.02 Impact Factor
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ABSTRACT: Minimally invasive surgery (MIS) in total knee arthroplasty (TKA) reportedly yields decreased patient morbidity and a rapid return of function, but how much deformity can be accepted for MIS-TKA remains unclear. This study investigated 238 knees from 218 consecutive patients who underwent MIS-TKA. Patients were divided into groups with tibiofemoral mechanical axis (TFM) 195 degrees or greater and TFM less than 195 degrees, then clinical and radiographic results were compared. Similar improvements in knee score at 3 months postoperatively were obtained in the both groups, whereas radiographic accuracy of the coronal alignment in the TFM >or=195 degrees group was inferior to that in TFM <195 degrees group. Postoperative TFM was significantly worsened in patients with lateral bowing angle of the femoral shaft (LBFS) 4 degrees or greater, and 53% of patients in the TFM >or=195 degrees group displayed LBFS 4 degrees or greater, explaining the inferior radiographic accuracy in this group compared with the TFM <195 degrees group. These results indicate that use of MIS techniques decreases radiographic accuracy, particularly in patients with severe genu varum and increased LBFS.
The Journal of arthroplasty 04/2010; 25(3):381-6. · 1.79 Impact Factor
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Journal of Orthopaedic Science 03/2010; 15(2):251-6. · 0.84 Impact Factor
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ABSTRACT: We present an instructive case of habitual left patellar dislocation in which the patella had appeared odd due to lateral tilt relative to contralateral side, but had been radiologically confirmed to be on the trochlea at 1 year prior to the referral. An 11-year-old girl presented to our hospital 2 years after the left patella had dislocated with a 'giving way' when cutting to the left. Our physical and radiological examinations confirmed that the left patella was laterally tilted in the patellar groove with the knee in extension but was dislocated in flexion beyond 45°. In spite of these findings, she had been untreated at the previous hospital since all plain X-rays, including a skyline patellar view, had failed to demonstrate the dislocation. Consequently, in addition to reconstruction of medial patellofemoral ligament, she had to undergo a lateral retinacular release, which might have been unnecessary if treated earlier. This case illustrates that first-time patellar dislocation can gradually lead to habitual dislocation subsequently, and that cautious physical examinations in regard to patella tracking are essential since radiological examinations do not always reveal the pathophysiology of patellar instability.
Sports Medicine Arthroscopy Rehabilitation Therapy & Technology 01/2010; 2:23.
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ABSTRACT: Recent advances in the understanding of blood coagulation processes favor an inflammatory basis for thrombotic events. In this study, thrombotic risk after total knee arthroplasty (TKA) was assessed and compared between patients with rheumatoid arthritis (RA) and those with osteoarthritis (OA).
Subjects comprised 199 patients (238 knees) with RA and 156 patients (169 knees) with OA. Serum D-dimer levels were measured before and after the operation. Lowdose unfractionated heparin was given for 7 days when patients had a history of previous venous thromboembolism or had a D-dimer level or >or=10 microg/ml of D-dimer on postoperative day 1. Doppler ultrasonography (DUS) was routinely performed preoperatively and on postoperative day (POD) 7 for diagnosing a deep venous thrombosis (DVT).
D-dimer levels on PODs 0, 1, and 7 were, respectively, 4.6, 37.2, and 11.2 microg/ml for RA and 1.8, 42.3, and 13.6 microg/ml for OA. The incidence of DUS-confirmed DVT was 20.6% in the RA group and 43.2% in the OA group, indicating a much higher incidence of postoperative DVT in OA patients (P < 0.001). Interestingly, when patients taking nonsteroidal antiinflammatory drugs (NSAIDs) or those >65 years of age were excluded, the incidence of DVT was comparable in the RA and OA groups. Symptomatic pulmonary embolism and DVT occurred in two and one OA patients and in one and two RA patients, respectively, with one postdischarge DVT included in each group.
The present study revealed that the incidence of DVT following TKA was significantly lower in RA patients than in those with OA. However, when the patients were matched for age and NSAID use, the incidence of DVT was equivalent in the two groups. These findings may allow us to reconsider a prophylactic regimen for venous thromboembolism in patients with RA.
Journal of Orthopaedic Science 01/2010; 15(1):57-63. · 0.84 Impact Factor
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ABSTRACT: Development of bone morphogenetic protein (BMP) signaling modulators may provide useful therapeutic options for the treatment of large bony defects in clinical settings. Controversy remains over whether hepatocyte growth factor (HGF) is a positive or negative modulator of BMP-induced osteogenesis. This study analyzed osteogenic properties of HGF, particularly during BMP-2-induced bone formation. Using a mouse model of ectopic bone formation, HGF-impregnated gelatin sponges displayed significantly reduced bone formation induced by BMP-2, both radiologically and histologically. Abrogation of endogenous HGF production by knockdown of HGF mRNA resulted in upregulation of BMP-2-induced ALP activity for C2C12 myoblasts in vitro. In contrast, addition of exogenous HGF inhibited BMP-2-induced ALP activity and osteocalcin production by mouse embryonic fibroblasts (MEFs) through HGF-c-Met interactions. Inhibition of ALP activity by HGF was rescued by U0126, a MEK1/2 inhibitor, indicating that HGF suppresses the BMP-2-Smad axis via activation of ERK1/2. Importantly, treatment with HGF prior to administration of BMP-2 induced cellular proliferation of MEFs and did not influence subsequent osteoblast differentiation induced by BMP-2. The effects of HGF may differ according to the differentiation stage of mesenchymal stem cells, which would explain the inconsistencies seen in osteogenic properties of HGF in previous reports. The timing of HGF treatment is critical and should be carefully determined for successful induction of bone formation by BMPs.
Biomaterials 11/2009; 31(6):1191-8. · 7.40 Impact Factor
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The Journal of trauma 09/2009; 67(2):E33-5. · 2.48 Impact Factor
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ABSTRACT: This report describes a unique case of bilateral total knee arthroplasty necessitating revision of the polyethylene insert, which showed prominent marks on the tibial post resulting from repeated seiza-style sitting. The patient presented 7 years postoperatively with knee pain and flexion disturbance due to continuous joint effusion persisting for more than 4 months. Proliferating synovia throughout the joint revealed reactive synovitis to polyethylene particles. The retrieved polyethylene inserts displayed double-concave deformity of the tibial post with burnishing and creep in tibiofemoral articulation. The damage pattern of retrieved polyethylene inserts reflected the data from tibiofemoral contact location obtained using a shape-matching technique in the early postoperative phase. This case provides an example of damage to the polyethylene tibial post caused by a floor-sitting lifestyle and the potential clinical sequelae.
The Journal of arthroplasty 04/2009; 25(3):497.e7-10. · 1.79 Impact Factor
