Lateral Laxity in Flexion Influences Patient-Reported Outcome After Total Knee Arthroplasty.

Introduction: Slight lateral laxity exists in normal knee especially in flexion. The lateral laxity in flexion has possibility to affect the outcome after total knee arthroplasty (TKA). Purpose: The purpose of this study was to determine how intraoperative laxity in flexion affects patient-reported outcome after total knee arthroplasty. Methods: We retrospectively analysed 98 knees with osteoarthritis that underwent total knee arthroplasty. After bone resection, ligament imbalance and joint component gaps were measured using an offset-type tensor while applying a 40-lb joint distraction force at 0° and 90° of knee flexion. The lateral laxity in flexion was determined by subtracting polyethylene insert thickness from the lateral gap at 90°. All patients were divided into three groups: ≤ 2 mm (A), 2-5 mm (B), and > 5 mm (C). One year after surgery, patients were asked to fill out questionnaires using the new Knee Society Score after examination outside the consultation room. Results: The mean intraoperative lateral laxities at 90° were - 0.2 ± 2.1 mm, 3.5 ± 0.7 mm, and 6.7 ± 1.9 mm in groups A, B, and C, respectively. The symptom score of group C was significantly lower than those of groups A or B. There were no significant differences in terms of satisfaction or the expectation and activity scores among all groups. There were no significant differences in terms of alignment after total knee arthroplasty among all groups. Conclusions: Excessive lateral laxity possibly resulted in worse patient-reported outcomes. However, slight lateral laxity of 2-5 mm might have no effect on patient-reported outcome and this slight varus imbalance could be acceptable. Altogether, our findings would lead to avoidance of excessive medial release in soft tissue balancing.

Remnant tissue enhances early postoperative biomechanical strength and infiltration of Scleraxis-positive cells within the grafted tendon in a rat anterior cruciate ligament reconstruction model.

When ruptured, ligaments and tendons have limited self-repair capacity and rarely heal spontaneously. In the knee, the Anterior Cruciate Ligament (ACL) often ruptures during sports activities, causing functional impairment and requiring surgery using tendon grafts. Patients with insufficient time to recover before resuming sports risk re-injury. To develop more effective treatment, it is necessary to define mechanisms underlying ligament repair. For this, animal models can be useful, but mice are too small to create an ACL reconstruction model. Thus, we developed a transgenic rat model using control elements of Scleraxis (Scx), a transcription factor essential for ligament and tendon development, to drive GFP expression in order to localize Scx-expressing cells. As anticipated, Tg rats exhibited Scx-GFP in ACL during developmental but not adult stages. Interestingly, when we transplanted the flexor digitorum longus (FDP) tendon derived from adult Scx-GFP+ rats into WT adults, Scx-GFP was not expressed in transplanted tendons. However, tendons transplanted from adult WT rats into Scx-GFP rats showed upregulated Scx expression in tendon, suggesting that Scx-GFP+ cells are mobilized from tissues outside the tendon. Importantly, at 4 weeks post-surgery, Scx-GFP-expressing cells were more frequent within the grafted tendon when an ACL remnant was preserved (P group) relative to when it was not (R group) (P vs R groups (both n = 5), p<0.05), and by 6 weeks, biomechanical strength of the transplanted tendon was significantly increased if the remnant was preserved (P vsR groups (both n = 14), p<0.05). Scx-GFP+ cells increased in remnant tissue after surgery, suggesting remnant tissue is a source of Scx+ cells in grafted tendons. We conclude that the novel Scx-GFP Tg rat is useful to monitor emergence of Scx-positive cells, which likely contribute to increased graft strength after ACL reconstruction.

Can accuracy with the iASSIST navigation be confirmed by assessment? A multi-center prospective randomized controlled trial with independent three-dimensional image assessment.

BACKGROUND: iASSIST is one of the novel accelerometer-based navigation systems for total knee arthroplasty (TKA). Although the accuracy of iASSIST compared with conventional instruments has been reported, such evaluations were performed on two-dimensional (2D) images (X-rays). This multi-center prospective randomized controlled trial aimed to assess component positioning between TKA with and without iASSIST by 3D image assessment, and to clarify whether the iASSIST provides any benefit with regard to alignment accuracy. METHODS: Eighty-three knees with primary knee osteoarthritis were enrolled in this study. iASSIST was used for distal femoral and proximal tibial resection in 42 knees (iA group) and a conventional guide was used in 41 knees (CONV group). At 6 months postoperatively, component alignment was evaluated with 3D images by the independent orthopaedic surgeons, and surgical parameters, range of motion and clinical outcomes were examined. RESULTS: The rate of knees who have the alignment within 3° of neutral compared with the iA group and CONV group were 92.9% (39/42) vs. 87.8% (36/41) for femur and 76.2% (32/42) vs. 56.1% (23/41) for tibia in the coronal plane, respectively, whereas in the sagittal plane, the rate was 85.7% (36/42) vs. 58.5% (24/41) for femur and 83.3% (35/42) vs. 78.0% (32/41) for tibia, respectively. Compared with the CONV group, the iA group had a significantly improved femoral alignment in the sagittal plane (P = 0.006). There were no clinical or patient-reported differences at 6 months postoperatively. CONCLUSIONS: The iASSIST provides technically high accuracy in femoral resection at TKA compared with a conventional procedure.

CD271+CD51+PALLADIN- Human Mesenchymal Stromal Cells Possess Enhanced Ossicle-Forming Potential.

Human mesenchymal stem/stromal cells (hMSCs), when engrafted into immunodeficient mice, can form ectopic bone organs with hematopoietic stem cell (HSC) supportive functions. However, the ability to do so, through a cartilage intermediate, appears limited to 30% of donor bone marrow samples. In this study, we characterize the heterogeneous nature of hMSCs and their ability to efficiently form humanized ossicles observed in "good donors" to correlate with the frequency and functionality of chondrocyte progenitors. Flow cytometry of putative hMSC markers was enriched in the CD271+CD51+ stromal cell subset, which also possessed enhanced hMSC activity as assessed by single-cell colony-forming unit fibroblast (CFU-F) and undifferentiated mesensphere formation. Transcriptome analysis of CD271+ cells presented upregulation of chondrogenesis-/osteogenesis-related genes and HSC/niche maintenance factors such as C-X-C motif chemokine 12 (CXCL12) and ANGIOPOIETIN 1. Among the candidate genes selected to enrich for subsets with greater chondrogenic ability, cells negative for the actin cross-linker PALLADIN displayed the greatest CFU-F potential. Our study contributes to a better characterization of ossicle-forming hMSCs and their efficient isolation for the optimized engineering of human bone organs.

Edoxaban Enhances Thromboprophylaxis by Physiotherapy After Total Knee Arthroplasty　- The Randomized Controlled ESCORT-TKA Trial.

BACKGROUND: The pharmacological advantage of combining physiotherapy with anticoagulants for the prevention of venous thromboembolism (VTE) after total knee arthroplasty (TKA) is not fully known. Herein we investigated the potential benefit of this combination therapy in patients undergoing TKA.Methods and Results:The 38 patients were randomly assigned to a physiotherapy group (n=19) or a physiotherapy plus 30 mg/day edoxaban group (n=19). The occurrence of VTE was evaluated, as were serial changes in parameters measured by the Total Thrombus-formation Analysis System, a novel system for quantitatively analyzing thrombus formation using microchips with thrombogenic surfaces (collagen plus tissue factor, atheroma [AR]-chip). Combination therapy significantly reduced the incidence of VTE after TKA compared with monotherapy (P=0.038). The area under the curve (AUC) of thrombus formation for the AR-chip (AR10-AUC30) was significantly lower in the combination group (P=0.001) on Day 7 after TKA than before TKA, but no significant change was observed with monotherapy (P=0.809). In 13 VTE-positive patients, AR10-AUC30was significantly lower in the combination group (n=3) than in the monotherapy group (n=10) on Day 7 (P=0.045). CONCLUSIONS: The combination of physiotherapy and edoxaban significantly reduced the incidence of VTE after TKA compared with physiotherapy alone. However, it is possible that VTE occurrence after TKA is not only associated with thrombogenicity, but also rheological factors.

TGF-ß1 Improves Biomechanical Strength by Extracellular Matrix Accumulation Without Increasing the Number of Tenogenic Lineage Cells in a Rat Rotator Cuff Repair Model.

BACKGROUND: Transforming growth factor ß1 (TGF-ß1) positively regulates the tenogenic marker genes scleraxis ( Scx) and tenomodulin ( Tnmd) in mesenchymal progenitors in vitro. However, little is known about the effect of TGF-ß1 on the expression of tenogenic markers during rotator cuff (RC) healing in rats. HYPOTHESIS: TGF-ß1 improves the biomechanical properties and histological maturity of reparative tissue in a rat RC repair model by stimulating the growth of tenogenic cells. STUDY DESIGN: Controlled laboratory study. METHODS: Adult male Sprague-Dawley rats (N = 180) underwent unilateral supraspinatus tendon-to-bone surgical repair and were randomly treated with a gelatin hydrogel presoaked in TGF-ß1 (100 ng) or phosphate-buffered saline. The effects of TGF-ß1 on RC healing were investigated at 2, 4, 6, 8, and 12 weeks postoperatively by immunostaining for proliferating cell nuclear antigen, by real-time reverse transcription polymerase chain reaction and in situ hybridization or immunostaining for enthesis-related markers (SRY-box containing gene 9 [ Sox9], Scx, and Tnmd), and by real-time reverse transcription polymerase chain reaction and immunostaining for type I and III collagen. At 6 and 12 weeks postoperatively, biomechanical testing, micro-computed tomography, and biochemical analysis were also performed. At 2 and 4 weeks postoperatively, mesenchymal stem cell-related markers, phospho-Smad2, and matrix metalloproteinase 9 (MMP-9) and MMP-13 were assessed by immunostaining. RESULTS: The TGF-ß1-treated group had significantly higher ultimate load to failure and tissue volume at 6 and 12 weeks postoperatively and a higher collagen content at 12 weeks compared with the saline group. Tendon-related gene expression, histological maturity, cell proliferation, and mesenchymal stem cell-related marker immunoreactivity were not affected by exogenously administrated TGF-ß1 at all time points. In the TGF-ß1-treated group, the percentage of phospho-Smad2-positive cells within the healing tissue increased, whereas the expression of MMP-9 and MMP-13 significantly decreased at 2 and 4 weeks postoperatively. CONCLUSION: TGF-ß1 enhances formation of tough fibrous tissues at the healing site by inhibiting MMP-9 and MMP-13 expression to increase collagen accumulation but without the growth of tenogenic lineage cells. CLINICAL RELEVANCE: These findings suggest that TGF-ß1 could be used for enhancing biomechanical strength after RC surgical repair.

Neuropathic pain in patients with rotator cuff tears.

BACKGROUND: Recent studies have confirmed the existence of neuropathic pain (NeP) components in patients with musculoskeletal disorders. However, the presence of NeP in patients with rotator cuff tears has not been investigated thus far. Therefore, we studied the prevalence of NeP and the prognostic factors for NeP in patients with rotator cuff tears. METHODS: Data were collected from 110 patients with rotator cuff tears, diagnosed by physical examination and magnetic resonance imaging, who attended an outpatient clinic between August 2013 and August 2014. The measured parameters included visual analog scale (VAS) pain scores, painDETECT questionnaire (PDQ) responses, a physical examination, and magnetic resonance imaging. To evaluate the factors associated with NeP, we performed a two-stage analysis. For univariate analysis, we used the Mann-Whitney U test. For multivariate analysis, forward stepwise regression was performed using factors that demonstrated statistical significance in the univariate analysis. RESULTS: Patients were classified into three groups according to their PDQ score: an NeP group (n = 12; 10.9 %), possible NeP group (n = 33; 30.0 %), and a nociceptive pain (NoP) group (n = 65; 59.1 %). In the univariate analysis between the NeP group and NoP group, NeP was affected by sex (p = 0.034), VAS score (average pain during the past 4 weeks; p = 0.013), and positive Neer and Hawkins impingement signs (p = 0.039). In the multivariate analysis, VAS score (p = 0.031) was an independent prognostic factor for NeP. CONCLUSIONS: Using the PDQ, we found that 10.9 % of patients with rotator cuff tears may have NeP. The VAS score (average pain during the past 4 weeks) was a prognostic factor for NeP. Clinicians should remain vigilant for heterogeneous etiologies of pain in patients with rotator cuff tears.

FGF-2 Stimulates the Growth of Tenogenic Progenitor Cells to Facilitate the Generation of Tenomodulin-Positive Tenocytes in a Rat Rotator Cuff Healing Model.

BACKGROUND: Fibroblast growth factor (FGF)-2 has the potential to enhance tendon-to-bone healing after rotator cuff (RC) injury. HYPOTHESIS: FGF-2 stimulates tenogenic differentiation of progenitors to improve the biomechanical strength and histological appearance of repaired RCs in rats. STUDY DESIGN: Controlled laboratory study. METHODS: Adult male Sprague-Dawley rats (N = 156) underwent unilateral surgery to repair the supraspinatus tendon to insertion sites. The FGF-2-treated group (gelatin hydrogel containing 5 µg of FGF-2) and a control group (gelatin hydrogel only) were compared to investigate the effects of FGF-2 at 2, 4, 6, 8, and 12 weeks postoperatively. Biomechanical testing was performed at 6 and 12 weeks. Semiquantitative histological analysis and immunohistochemical analysis for the proliferating cell nuclear antigen (PCNA) were performed, and the expression of tendon-related markers, including Scleraxis (Scx) and Tenomodulin (Tnmd), was monitored by real-time reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization. SRY-box containing gene 9 (Sox9) expression was monitored by RT-PCR and immunohistochemical analysis. At 2 and 4 weeks, immunohistochemical analysis for mesenchymal stem cell (MSC) markers was also performed. RESULTS: The FGF-2-treated group demonstrated a significant improvement in mechanical strength at 6 and 12 weeks and significantly higher histological scores than the control group at ≥4 weeks. The average incidence of PCNA-positive cells was significantly higher at 2 and 4 weeks, and more cells expressing MSC markers were detected at the insertion site in the FGF-2-treated group. The expression level of Scx increased significantly in the FGF-2-treated group from 4 to 8 weeks, while the Tnmd level increased significantly from 4 to 12 weeks postoperatively. The localization of Tnmd overlapped with the locations of reparative tissues accompanying collagen fibers with an aligned orientation. Sox9 expression was significantly upregulated at 4 weeks in the FGF-2-treated group. CONCLUSION: FGF-2 promotes growth of the tenogenic progenitor cells, which participate in tendon-to-bone healing, resulting in biomechanical and histological improvement of the repaired RC. CLINICAL RELEVANCE: These findings provide clues regarding the clinical development of regenerative repair strategies for RC injury.

Functional and structural comparisons of the arthroscopic knotless double-row suture bridge and single-row repair for anterosuperior rotator cuff tears.

BACKGROUND: We compared the outcomes of knotless double-row suture bridge and single-row repairs in patients undergoing arthroscopic repair for anterosuperior rotator cuff tears. METHODS: We included 61 full-thickness anterosuperior rotator cuff tears treated by arthroscopic repair, namely, single-row repair (group 1: 25 shoulders; mean patient age, 64 years) and the knotless double-row suture bridge repair (group 2: 36 shoulders; mean patient age, 62 years). Preoperative and postoperative magnetic resonance imaging was performed for all shoulders. Clinical outcomes were evaluated for mean follow-up periods of 81 months (range, 72-96 months) in group 1 and 34 months (range, 24-42 months) in group 2, using the University of California, Los Angeles and Japanese Orthopaedic Association assessments. RESULTS: At the final follow-up, both groups showed improvement in the average University of California, Los Angeles and Japanese Orthopaedic Association scores and range of motion, although no intergroup differences were observed. Both groups showed improved abduction strength, and the average score was higher in group 2 (P = .0112). The lift-off and belly-press test results were improved in both groups. Postoperatively, the incidence of positive lift-off tests tended to be lower (P = .075) and that of positive belly-press tests was lower in group 2, P = .049). The repair failure rate tended to be lower in group 2 (14% [5 of 36]) than in group 1 (32% [8 of 25]; P = .0839). CONCLUSIONS: Arthroscopic knotless double-row suture bridge repair of anterosuperior rotator cuff tears yielded functional outcomes equivalent to those of single-row repair and may be useful for improving subscapularis function, abduction strength, and tendon healing.

Evaluation of the relationship between T1ρ and T2 values and patella cartilage degeneration in patients of the same age group.

OBJECTIVE: The aim of this study was to investigate the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. MATERIALS AND METHODS: Sagittal T1ρ and T2 mapping and three-dimensional (3D) gradient-echo images were obtained from 78 subjects with medial knee osteoarthritis (OA). The degree of patella cartilage degeneration was classified into four groups using MRI-based grading: apparently normal cartilage, mild OA, moderate OA, and severe OA group. We measured the T1ρ and T2 values (ms) in the regions of interest set on the full-thickness patella cartilage. Then, we analyzed the relationship between the T1ρ and T2 values and the degree of patella cartilage degeneration. RESULTS: There were no significant differences in age among the four groups. Both the T1ρ and T2 values showed a positive correlation with the degree of OA progression (ρ=0.737 and ρ=0.632, respectively). By comparison between the apparently normal cartilage and the mild OA groups, there were significant differences in the T1ρ mapping, but not in the T2 mapping. CONCLUSIONS: Our study confirmed that T1ρ and T2 mapping can quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group.

Development and validation of formulae to predict leg length following medial opening-wedge osteotomy of the proximal tibia with hemicallotasis.

BACKGROUND: A medial open-wedge osteotomy of the proximal tibia with hemicallotasis (HCO) affects the relative coronal alignment of the femur and tibia with respect to the floor; this also potentially reflects a change in leg length. PURPOSE: The aims of this study are to develop and verify formulae for predicting the postoperative whole leg length (WLL) in HCO. METHODS: We analyzed a training set of 25 HCOs in 25 patients. Formulae for predicting the postoperative leg length were developed using various factors including the length and coronal alignment of the femur and tibia, the length of the proximal or distal fragment from the tibial osteotomy site, the femoro-tibial angle, and the correction angle. The formulae were then verified using the interclass correlation coefficient in an independent consecutive set of 25 HCOs. RESULTS: Significant postoperative increases in tibial bone length and WLL were noted with no postoperative change in femoral bone length. Furthermore, the coronal alignments of femoral and tibial bone axes were significantly abducted. For the formulae for predicting postoperative WLL developed in the training set, the interclass correlation coefficients between the predicted values and the real radiographic measurements in the validation set were more than 0.90, showing great consistency. CONCLUSION: The mathematical models established in this study seemed to predict almost completely the change in leg length after HCO. Our results suggest that these formulae may offer accurate, extremely useful information about the postoperative possibility of leg lengthening for patients planning an HCO. LEVEL OF EVIDENCE: Therapeutic case series; level 4.

In vivo kinematic comparison between mobile-bearing and fixed-bearing total knee arthroplasty during step-up activity.

Mobile-bearing total knee arthroplasty (TKA) expects high conformity and low contact stress. It is designed to correct the rotational mismatch between femoral and tibial components. We examined the difference in weight-bearing knee kinematics in patients with mobile-bearing and fixed-bearing TKA performing step-up activities. We randomly assigned 40 knees (37 patients) to mobile-bearing TKA (n=20) or fixed-bearing TKA (n=20). Using fluoroscopic imaging we evaluated knee kinematics during step-up activity one year after surgery. The total extent of rotation was not different for the two TKAs. Due to the axial rotation of the polyethylene insert, patients with mobile-bearing TKA had a wider range of absolute axial rotation. The position of the medial and the lateral condyles was significantly more posterior in the fixed-bearing TKA. There were only minor kinematic differences between the two TKAs. The polyethylene insert in the mobile-bearing TKA moved as designed especially with respect to the self-alignment feature.

Predictive value of E-PASS and POSSUM systems for postoperative risk assessment of spinal surgery.

OBJECT: The Estimation of Physiological Ability and Surgical Stress (E-PASS) and Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) systems are surgical risk scoring systems that take into account both the patient's preoperative condition and intraoperative variables. While they predict postoperative morbidity and mortality rates for several types of surgery, spinal surgeries are currently not included. The authors assessed the usefulness of E-PASS and POSSUM algorithms and compared the predictive ability of both systems in patients with spinal disorders considered for surgery. METHODS: The E-PASS system includes a preoperative risk score, a surgical stress score, and a comprehensive risk score that is determined by both the preoperative risk score and surgical stress score. The POSSUM system is composed of a physiological score and an operative severity score; its total score is based on both the physiological score and operative severity score. The authors calculated the E-PASS and POSSUM scores for 601 consecutive patients who had undergone spinal surgery and investigated the relationship between the individual scores of both systems and the incidence of postoperative complications. They also assessed the correctness of the predicted morbidity rate of both systems. RESULTS: Postoperative complications developed in 64 patients (10.6%); there were no in-hospital deaths. All EPASS scores (p ≤ 0.001) and the operative severity score and total score of the POSSUM (p < 0.03) were significantly higher in patients with postoperative complications than in those without postoperative complications. The morbidity rates correlated linearly and significantly with all E-PASS scores (p ≤ 0.001); their coefficients (preoperative risk score, ρ = 0.179; surgical stress score, ρ = 0.131; and comprehensive risk score, ρ = 0.198) were higher than those for the POSSUM scores (physiological score, ρ = 0.059; operative severity score, ρ = 0.111; and total score, ρ = 0.091). The area under the receiver operating characteristic curve for the predicted morbidity rate was 0.668 for the E-PASS and 0.588 for the POSSUM system. CONCLUSIONS: As E-PASS predicted morbidity more correctly than POSSUM, it is useful for estimating the postoperative risk of patients considered for spinal surgery.

Articular cartilage lesions increase early cartilage degeneration in knees treated by anterior cruciate ligament reconstruction: T1ρ mapping evaluation and 1-year follow-up.

BACKGROUND: Articular cartilage degeneration can develop after anterior cruciate ligament reconstruction (ACLR). Although radiological studies have identified risk factors for the progression of degenerative cartilage changes in the long term, risk factors in the early postoperative period remain to be documented. HYPOTHESIS: Cartilage lesions that are present at surgery progress to cartilage degeneration in the early phase after ACLR. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: T1ρ is the spin-lattice relaxation in the rotating frame magnetic resonance imaging. Sagittal T1ρ maps of the femorotibial joint were obtained before and 1 year after ACLR in 23 patients with ACL injuries. Four regions of interest (ROIs) were placed on images of the cartilage in the medial and lateral femoral condyle (MFC, LFC) and the medial and lateral tibia plateau (MTP, LTP). Changes in the T1ρ value (milliseconds) of each ROI were recorded, and differences between patients with and without cartilage lesions were evaluated. The relationship between changes in the T1ρ value and meniscal tears was also studied. RESULTS: Arthroscopy at ACLR detected cartilage lesions in 15 MFCs, 7 LFCs, and 2 LTPs. The baseline T1ρ value of the MFC and LFC was significantly higher in patients with cartilage lesions (MFC, 40.7 ms; LFC, 42.2 ms) than in patients without cartilage lesions (MFC, 38.0 ms, P = .025; LFC, 39.4 ms, P = .010). At 1-year follow-up, the T1ρ value of the MFC and LFC was also significantly higher in patients with lesions (MFC, 43.1 ms; LFC, 42.7 ms) than in patients without such lesions (MFC, 39.1 ms, P = .002; LFC, 40.4 ms, P = .023, respectively). In patients with cartilage injury, the T1ρ value of the MFC increased during the year after treatment (P = .002). There was no significant difference in the baseline and follow-up T1ρ value in patients with or without meniscal tears on each side although the T1ρ value of the MFC, MTP, and LFC increased during the first year after surgery regardless of the presence or absence of meniscal injuries. CONCLUSION: Using T1ρ mapping to detect minimal changes, our study demonstrated that cartilage lesions are related to progressive degenerative cartilage changes during the early phase after ACLR.

Detecting ICRS grade 1 cartilage lesions in anterior cruciate ligament injury using T1ρ and T2 mapping.

OBJECTIVE: The purpose of this study was to clarify the detectability of the International Cartilage Repair Society (ICRS) grade 1 cartilage lesions in anterior cruciate ligament (ACL)-injured knees using T1ρ and T2 mapping. MATERIALS AND METHODS: We performed preoperative T1ρ and T2 mapping and 3D gradient-echo with water-selective excitation (WATS) sequences on 37 subjects with ACL injuries. We determined the detectability on 3D WATS based on arthroscopic findings. The T1ρ and T2 values (ms) were measured in the regions of interest that were placed on the weight-bearing cartilage of the femoral condyle. The receiver operating characteristic (ROC) curve based on these values was constructed using the arthroscopic findings as a reference standard. The evaluation of cartilage was carried out only in the weight-bearing cartilage. The cut-off values for determining the presence of a cartilage injury were determined using each ROC curve, and the detectability was calculated for the T1ρ and T2 mapping. RESULTS: The cut-off values for the T1ρ and T2 were 41.6 and 41.2, respectively. The sensitivity and specificity of T1ρ were 91.2% and 89.5%, respectively, while those of T2 were 76.5% and 81.6%, respectively. For the 3D WATS images, the same values were 58.8% and 78.9%, respectively. CONCLUSIONS: Our study demonstrated that the T1ρ and T2 values were significantly higher for ICRS grade 1 cartilage lesions than for normal cartilage and that the two mappings were able to non-invasively detect ICRS grade 1 cartilage lesions in the ACL-injured knee with a higher detectability than were 3D WATS images.

Effect of immobilization on rotator cuff reconstruction with acellular dermal matrix grafts in an animal model.

INTRODUCTION: Using a rat model we determined whether immobilization improves tendon-to-bone healing and tendon maturation after rotator cuff reconstruction with acellular dermal matrix (ADM) grafts. METHODS: Sprague-Dawley rats were randomly assigned to 3 equal groups. All rats were subjected to rotator cuff reconstruction and their shoulder was not immobilized (N-IM controls) or immobilized for 2- or 6 weeks immediately thereafter (2- and 6-IM groups, respectively). After detaching the rotator cuff including the full-thickness supraspinatus tendon at its insertion on the greater tuberosity, a defect was created. ADM patches were used for rotator cuff reconstruction. Specimens obtained 2, 6, and 12 weeks after surgery were subjected to semiquantitative histomorphological measurements to assess cellularity, vascularity, and collagen organization. In addition, specimens at 12 weeks were submitted for biomechanical analysis. RESULTS: Cell density decreased over time in all 3 groups; there was no significant difference among the groups at 2 weeks. However, the 6-IM group harbored more cells in the tendon-to-bone interface than the 2-IM group at 6 weeks and the N-IM group at 12 weeks. Vascularity in the interface decreased over time in the N-IM and 2-IM groups but not the 6-IM rats. At 6 and 12 weeks, the 2-IM group manifested better collagen organization than the other groups. The 2-IM group exhibited higher ultimate load-to-failure than the other groups. Stiffness was similar in the 3 groups. CONCLUSION: Remodeling of ADM grafts placed in rat rotator cuff defects was promoted by 2- but not 6-week immobilization.

Intracellular accumulation of advanced glycation end products induces apoptosis via endoplasmic reticulum stress in chondrocytes.

Mammalian cells attempt to maintain their homeostasis under endoplasmic reticulum (ER) stress. If the stress cannot be alleviated, cells are led to apoptosis through induction of C/EBP homologous protein (CHOP). ER stress is provoked in osteoarthritis chondrocytes, and intracellular accumulation of advanced glycation end products (AGEs) in chondrocytes is a possible cause. To clarify the role of intracellular AGE accumulation in chondrocytes, the present study investigated the effect of intracellular AGE accumulation on ER stress and apoptosis by in vitro and in vivo analysis. Intracellular AGE accumulation induced by AGE precursors caused apoptosis, induced expression of ER stress markers, and led to co-localization of AGEs with glucose-regulated protein 78, leading to formation of high-molecular-weight complexes in cultured chondrocytes. These reactions were inhibited by an AGE formation inhibitor. CHOP deletion inhibited apoptosis induced by intracellular AGE accumulation. In vivo intracellular AGE accumulation induced by intra-articular injection of AGE precursors caused ER stress and apoptosis in chondrocytes and led to degradation of articular cartilage. Additionally, intracellular AGE accumulation increased the degree of cartilage degradation in an osteoarthritis model. These data indicate that intracellular accumulation of AGEs induces modification of unfolded protein response-related protein by AGEs and apoptosis via ER stress in chondrocytes. Moreover, the in vivo study showed that intracellular AGE accumulation in chondrocytes is involved in the occurrence and progression of osteoarthritis through ER stress. Thus, research on mechanisms of apoptosis via ER stress induced by intracellular AGE accumulation in chondrocytes will lead to a new understanding of osteoarthritis pathology.

Three-dimensional kinematics during deep-flexion kneeling in mobile-bearing total knee arthroplasty.

We performed an in vivo radiographic analysis of tibiofemoral and polyethylene (PE) insert motions during weight-bearing kneeling beyond 120° of flexion in one high-flexion knee arthroplasty design to determine if kinematics changed over time and if axial rotation occur between the PE insert and the tibial baseplate. Twenty knees implanted with a posterior-stabilized rotating-platform (RP) knee arthroplasty were postoperatively evaluated at 3, 6, and 12 months. The averaged flexion angles were 122°, 129°, and 131° at 3, 6, and 12 months, respectively, showing that the improvement of flexion was achieved up to 6 months. The femoral condyles translated posteriorly from extension to maximum flexion. There was a significant increase in AP translation of femoral lateral condyle in the maximum flexion kneeling between 12 months and the two other intervals (p=0.0003 at 3 months and p=0.016 at 6 months), while no differences in those of medial condyle between all intervals. Almost all rotation occurred at the surface between the tibial baseplate and the PE insert (p=0.0479 at 3 months, p=0.0008 at 6 months, and p=0.0479 at 12 months), almost no rotation occurred at the surface between the PE insert and the femoral component. There were significant increases in the amount of internal rotation angle during full flexion between the tibial component and the PE insert up to 12 months. Knees implanted with this RP knee arthroplasty design show deep-flexion knee kinematics that are consistent with the implant design intent.

In vivo knee kinematics in patients with bilateral total knee arthroplasty of 2 designs.

Many younger and highly active patients desire to achieve high flexion after total knee arthroplasty. This study's purpose was to determine if a contemporary total knee arthroplasty design improved functional knee flexion compared with a traditional total knee arthroplasty in patients living a Western lifestyle. Ten patients with bilateral total knee arthroplasty of 2 types were studied during weight-bearing lunge, kneeling, and stair activities using fluoroscopic imaging. There were no differences in maximum knee flexion during lunging or kneeling. Statistically significant differences in tibial rotation and condylar translation were observed during the 3 activities. Although several joint kinematic differences were observed, no important functional differences were observed in clinically excellent, high performing subjects with bilateral total knee arthroplasty of 2 types.