Quadriceps Tendon With Bone Autograft Has Better Stability and Magnetic Resonance Imaging Maturation Than Hamstring Tendon Autograft After Anterior Cruciate Ligament Reconstruction in Patients With Knee Hyperextension.

PURPOSE: To compare the clinical outcomes of anterior cruciate ligament (ACL) reconstruction between methods using quadriceps tendon with bone (QTB) and hamstring tendon (HT) in patients with hyperextension of the knee. METHODS: The medical records of patients with knee hyperextension greater than 8° who underwent arthroscopic ACL reconstruction between October 2010 and October 2020 with follow-up for at least 2 years (median, 3 years; interquartile range [IQR], 2.0-4.6 years) were retrospectively reviewed. Side-to-side difference in anterior translation, pivot-shift test grade, Lysholm score, and graft intensity using the Howell grade on magnetic resonance imaging at final follow-up were compared between the QTB and HT groups. RESULTS: The HT and QTB groups consisted of 42 patients and 21 patients, respectively. The overall mean age was 21.5 years (range, 14-48 years), and the median Tegner Activity Scale score was 6 (range, 3-9). Postoperatively, the median side-to-side difference in anterior translation was 1.75 mm (IQR, 1-3 mm) in the HT group and 1.0 mm (IQR, 0-1.75 mm) in the QTB group (P = .01). Pivot-shift testing showed grade 0 in 74.7%, grade 1 in 18.7%, and grade 2 in 6.6% of patients in the HT group and grade 0 in 85.7% and grade 1 in 14.3% of those in the QTB group (P = .03). The median postoperative Lysholm score was 99 in both groups. Graft signal intensity showed a significant between-group difference: grade I in 52%, grade II in 36%, and grade III in 12% of patients in the HT group versus grade I in 85.7%, grade II in 9.5%, and grade III in 4.8% of those in the QTB group (P = .03). CONCLUSIONS: In patients who underwent ACL reconstruction for hyperextension of the knee, QTB yielded better clinical outcomes than HT with respect to anterior stability, rotational stability, and graft signal intensity on median 2-year follow-up magnetic resonance imaging. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

Arthroscopic surgery for symptomatic discoid lateral meniscus improves meniscal status assessed by magnetic resonance imaging T2 mapping.

INTRODUCTION: Discoid lateral meniscus (DLM) is an anatomic knee variant associated with increased tears and degeneration. This study aimed to quantify meniscal status with magnetic resonance imaging (MRI) T2 mapping before and after arthroscopic reshaping surgery for DLM. MATERIALS AND METHODS: We retrospectively reviewed the records of patients undergoing arthroscopic reshaping surgery for symptomatic DLM with ≥ 2-year follow-up. MRI T2 mapping was performed preoperatively and at 12 and 24 months postoperatively. T2 relaxation times of the anterior and posterior horns of both menisci and of the adjacent cartilage were assessed. RESULTS: Thirty-six knees from 32 patients were included. The mean age at surgery was 13.7 years (range 7-24), and the mean follow-up duration was 31.0 months. Saucerization alone was performed on five knees and saucerization with repair on 31 knees. Preoperatively, the T2 relaxation time of the anterior horn of the lateral meniscus was significantly longer than that of the medial meniscus (P < 0.01). T2 relaxation time significantly decreased at 12 and 24 months postoperatively (P < 0.01). Assessments of the posterior horn were comparable. The T2 relaxation time was significantly longer in the tear versus non-tear side at each time point (P < 0.01). There were significant correlations between the T2 relaxation time of the meniscus and that of the corresponding area of the lateral femoral condyle cartilage (anterior horn: r = 0.504, P = 0.002; posterior horn: r = 0.365, P = 0.029). CONCLUSIONS: The T2 relaxation time of symptomatic DLM was significantly longer than that of the medial meniscus preoperatively, and it decreased 24 months after arthroscopic reshaping surgery. The meniscal T2 relaxation time of the tear side was significantly longer than that of the non-tear side. There were significant correlations between the cartilage and meniscal T2 relaxation times at 24 months after surgery.

Posterior subtotal meniscectomy revealed the worst scenario for the progression of osteocartilaginous damage in cases of juvenile discoid lateral meniscus with peripheral tear.

INTRODUCTION: We compared subtotal meniscectomy and saucerization with stabilization for osteocartilaginous damage based on injured location and further examined the factors related to osteocartilaginous damage in juvenile discoid lateral meniscus (DLM) with peripheral tear after a follow-up period of at least 5 years. MATERIALS AND METHODS: We retrospectively reviewed juvenile DLM patients with peripheral tear who underwent arthroscopic surgery with more than 5 years of follow-up. Osteocartilaginous damage, which was identified by osteochondritis dissecans (OCD) development and the whole-organ magnetic resonance imaging score (WORMS) of cartilage grade ≥ 3, was compared between subtotal meniscectomy and saucerization with stabilization. A subgroup analysis examining the location of the tear site was performed. Factors for osteocartilaginous damage were analyzed between the damaged and non-damaged groups. RESULTS: Forty-one patients, including 29 who underwent saucerization with stabilization and 12 who underwent subtotal meniscectomy, were included in this study. Seven patients developed OCD lesions; six patients showed cartilage WORMS of more than grade 3. Overall, there was a significant difference in the total cartilage and meniscus WORMS between the two groups at the final follow-up. The subgroup analysis demonstrated more severe osteocartilaginous damage developed in posterior subtotal meniscectomy than in posterior stabilization following saucerization. The damaged group showed significant difference compared to the non-damaged group in terms of age (p = 0.003), sex (p = 0.036), and posterior subtotal meniscectomy (p < 0.001). CONCLUSIONS: Posterior subtotal meniscectomy revealed the worst scenario for the progression of osteocartilaginous damage in cases of juvenile DLM with peripheral tear over a minimum follow-up period of 5 years.

Biochemical Characteristics and Clinical Result of Bone Marrow-Derived Fibrin Clot for Repair of Isolated Meniscal Injury in the Avascular Zone.

PURPOSE: To characterize bone marrow aspirate-derived fibrin clot (BMA clot) and evaluate the clinical result of meniscal repair with a BMA clot for isolated meniscal injury in the avascular zone. METHODS: Blood counts of total leukocytes, platelets, and concentrations of basic fibroblast growth factor (bFGF), transforming growth factor ß (TGF-ß), and stromal cell-derived factor 1 (SDF-1) were analyzed with BMA, peripheral blood (PB), BMA clot, and PB clot from 5 patients treated for meniscal repair. In addition, a retrospective analysis of 30 patients with isolated avascular meniscal injuries who underwent repair with a BMA clot was performed to assess rate failure. Avascular meniscal injury was identified as horizontal tear, radial tear, and flap tear. Clinical failure was defined as the presence of 1 or more of Barrett's criteria. Anatomic failure was defined as the existence of equivalent signal intensity to intra-articular fluid along the repair area on follow-up magnetic resonance imaging (MRI). Patients' demographic and clinical data were compared between the overall failure group and the success group. RESULTS: The bFGF, TGF-ß, and SDF-1 levels of BMA clots were more highly concentrated compared with PB clots. The Lysholm scores and meniscal status evaluated by MRI were significantly improved from preoperatively to postoperatively (both P < .001). The Kellgren-Lawrence grading of knee radiographs did not significantly differ pre- and postoperatively (P = .140). Rates of clinical failure, anatomic failure, and retear were 10%, 6.7%, and 3.3%, respectively. The demographic characteristics and surgical and postoperative status did not significantly differ between the overall failure group and the success group. CONCLUSIONS: BMA clots had increased levels of cytokines compared to PB clots. The retrospective analysis revealed that the rates of clinical failure and anatomic failure after meniscal repair with a BMA clot for isolated avascular meniscal injury were 10% and 6.7%, respectively. LEVEL OF EVIDENCE: Level IV, case series.

Two positioned MRI can visualize and detect the location of peripheral rim instability with snapping knee in the no-shift-type of complete discoid lateral meniscus.

INTRODUCTION: We evaluated the efficacy of two positioned magnetic resonance imaging (MRI) for visualizing the snapping phenomenon and detecting peripheral rim instability (PRI) in no-shift-type complete discoid lateral meniscus (CDLM). MATERIALS AND METHODS: The records of 39 patients diagnosed with no-shift-type CDLM under routine MRI who underwent arthroscopic surgery were reviewed. The snapping phenomenon and meniscal shift on two positioned MRI in full extension and deep flexion were evaluated and calculated the agreement between these findings. The positive predictive value (PPV), sensitivity, and specificity of meniscal shift on two positioned MRI for predicting PRI were calculated; PRI was further investigated according to anterior and posterior location. The hypotheses of this study were asfollows: (1) Two positioned MRI can visualize the snapping phenomenon and (2) Meniscal shift on two positioned MRI is an important predictive sign of detecting the instability site in no-shift-type CDLM. RESULTS: The κ values between the snapping phenomenon and meniscal shift on two positioned MRI were 0.84. The snapping and two positioned MRI findings had high PPV (1.0, 0.96), sensitivity (0.82, 0.85), and specificity (1.0, 0.91) for predicting overall PRI. For anterior PRI, the snapping and posterior shift on two positioned MRI had moderate and high PPV (0.78, 0.9), high sensitivity (0.9, 0.9), and specificity (0.8, 0.89). The anterior shift on two positioned MRI findings predicted posterior PRI with high PPV (1.0) and specificity (1.0). CONCLUSIONS: Two positioned MRI visualized the snapping phenomenon. Meniscal shift on two positioned MRI was an important predictive sign of overall PRI, anterior PRI, and posterior PRI in no-shift-type CDLM.

Predictive signs of peripheral rim instability with magnetic resonance imaging in no-shift-type complete discoid lateral meniscus.

PURPOSE: To investigate the associations between the preoperative MRI findings suggestive of meniscal instability and the intraoperative finding of peripheral rim instability (PRI) in patients with complete discoid lateral meniscus (CDLM) of no-shift-type, which was identified as the peripheral portion was not separated from the capsule. METHODS: The records of 56 patients diagnosed with no-shift-type CDLM who underwent arthroscopic surgery were reviewed. We evaluated MRI findings of anterior parameniscal soft-tissue edema, linear fluid signal at the anterior meniscal margin, bulging of the meniscal margin, absence of popliteomeniscal fascicles, and hiatus widening on routine MRI. The positive predictive value (PPV), sensitivity, and specificity of these findings in predicting PRI were calculated; PRI was further investigated according to anterior and posterior location. RESULTS: Linear fluid signal at the anterior meniscal margin and bulging had high PPV and specificity (P = .004 and = .029, respectively) for overall of PRI. The presence of either anterior parameniscal soft-tissue edema or linear fluid signal at the anterior meniscal margin predicted anterior PRI with high PPV, sensitivity, and specificity. Bulging of the meniscal margin had high specificity, and either bulging of the meniscal margin or absence of popliteomeniscal fascicle had high sensitivity in predicting posterior PRI. CONCLUSIONS: A linear fluid signal at the anterior meniscus and anterior parameniscal soft-tissue edema were important signs of anterior PRI, whereas bulging of the margin had high specificity and either bulging of the meniscal margin or absence of popliteomeniscal fascicle had high sensitivity in detecting posterior PRI on routine MRI of no-shift-type CDLM. LEVEL OF EVIDENCE: Level IV therapeutic case series.

Magnetic Resonance Imaging T2 Relaxation Times of Articular Cartilage Before and After Arthroscopic Surgery for Discoid Lateral Meniscus.

PURPOSE: To quantitatively evaluate degeneration of articular cartilage using magnetic resonance imaging (MRI) T2 mapping before and after arthroscopic surgery for discoid lateral meniscus (DLM). METHODS: We retrospectively reviewed the medical records of patients who underwent arthroscopic reshaping surgery for symptomatic DLM from September 2013 to October 2017 and who had undergone follow-up for ≥2 years. MRI T2 relaxation examinations had been performed preoperatively and at 3, 6, 12, and 24 months postoperatively. The T2 relaxation times of the whole lateral femoral condyle and the tibial plateau were assessed. In addition, the lateral femoral condyle was divided into 3 subcompartmental areas: anterior, middle, and posterior. RESULTS: In total, 30 knees of 27 patients were included in this study. The patients' mean age at operation was 13.3 years (range 6-23 years), and the mean follow-up period was 31.6 months. Saucerization alone was performed in 3 knees and saucerization with repair in 27 knees. The T2 relaxation time of the whole lateral femoral condyle was significantly increased at 3 and 6 months postoperatively and significantly decreased at 12 and 24 months. The T2 relaxation time of the whole lateral tibial plateau was significantly increased at 3 months postoperatively and significantly decreased at 24 months. The T2 relaxation time of the posterior subcompartment of the lateral femoral condyle was significantly increased at 3 months and significantly decreased at 12 and 24 months. CONCLUSIONS: The T2 relaxation time of the lateral femorotibial joint cartilage increased at 3 and 6 months postoperatively and then had decreased at 12 and 24 months. Quantitative MRI allowed us to monitor the substantial changes in the cartilage during the early postoperative period and the recovery at the distant time point after reshaping surgery for DLM. LEVEL OF EVIDENCE: Level IV, case series.

Patients with a quadriceps tendon shorter than 60 mm require a patellar bone plug autograft in anterior cruciate ligament reconstruction.

PURPOSE: To assess the length and thickness of the quadriceps tendon (QT) and anterior cruciate ligament (ACL) to predict the required QT length for individual ACL reconstruction. METHODS: Thirty patients (9 females, 21 males; mean age 24.5 years; mean height 169.3 cm) who underwent ACL reconstruction using the QT with a bone plug autograft were enrolled. The length and thickness of the QT on preoperative magnetic resonance imaging (MRI) were compared with those measured under direct visualization. The ACL length was measured on preoperative MRI and three-dimensional computed tomography after ACL reconstruction. The QT length on MRI was compared with the required graft length, and the factors related to an adequate QT length were assessed. RESULTS: The mean QT length on MRI was 60.8 ± 1.3 mm and was significantly positively correlated with the QT length under direct visualization (P < 0.01). On MRI, the mean ACL length was 30.8 ± 1.2 mm and the mean QT thickness was 6.3 ± 0.2 mm. Although the mean QT was 0.1 mm longer than the mean required graft length, the QT on MRI was shorter than the required graft length in 37% of patients (11/30). Adequate QT length was related to a QT length of more than 60 mm, but not to age, sex, height, or ACL length. CONCLUSION: Although preoperative MRI predicted the required QT length for ACL reconstruction, 37% of patients lacked an adequate QT length, and a QT shorter than 60 mm required the addition of patellar bone. LEVEL OF EVIDENCE: III.

Factors Related to Postoperative Osteochondritis Dissecans of the Lateral Femoral Condyle After Meniscal Surgery in Juvenile Patients With a Discoid Lateral Meniscus.

PURPOSE: The purpose was to assess the incidence of postoperative osteochondritis dissecans (OCD) and the related epidemiologic factors following meniscal surgery for juvenile discoid lateral meniscus (DLM). METHODS: The study was a retrospective review of 103 knees in 89 patients with a mean age of 12.1 years who underwent arthroscopic meniscal surgery for DLM. Mean follow-up was 4.2 years. The surgical procedures were either saucerization, saucerization with repair or subtotal meniscectomy, depending on the type of DLM tear. Postoperative OCD lesions were identified radiographically. Age, sex, weight, Lysholm score, Tegner activity scale, exercise frequency, and surgical procedure were compared between the postoperative OCD diagnosis group and non-OCD control group. RESULTS: Postoperative OCD was diagnosed in 8/103 (7.8%) knees following DLM surgery. The incidence of postoperative OCD was significantly greater for patients age less than 10 years old, and male sex, low weight, Lysholm score, Tegner activity scale preinjury and after returning to sports, and exercise frequency per week on univariate analyses. On multivariate analyses, postoperative OCD occurred more commonly with subtotal meniscectomy than with saucerization or saucerization with repair, and in patients less than 11 years of age. Receiver operating characteristic curve analysis revealed a cutoff value of age at surgery of 10 years. CONCLUSIONS: Subtotal meniscectomy and patients younger than 10 years at the time of surgery are at greater risk for postoperative OCD. To decrease this risk, if possible, we recommend performing saucerization or saucerization with repair in patients undergoing surgery for DLM. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Incidence and Risk Factors for Meniscal Cyst After Meniscal Repair.

PURPOSE: To investigate the incidence of magnetic resonance imaging-confirmed cyst formation after meniscal repair and to analyze associated risk factors. METHODS: This retrospective study included cases repaired arthroscopically with the all-inside (AI) technique (using suture anchors) and/or the inside-out (IO) technique between October 2008 and December 2014. A meniscal cyst was detected on T2 fat-suppressed magnetic resonance images. All cases were divided into 3 groups according to the repair method (AI, IO, and combined technique). The incidence of radiographically confirmed meniscal cyst formation in each group and the associated risk factors (age, sex, AI device, medial meniscus, Tegner activity scale preinjury) were analyzed. RESULTS: A total of 102 menisci in 96 knees were evaluated. The mean follow-up period was 3.8 (range, 2-8) years. The mean patient age was 21.0 (range, 6-53) years. Thirty cases were in the AI group, 60 in the IO group, and 12 in the combined group. Demographically, there were significant differences among groups regarding the number of medial, lateral, and discoid tears; concomitant anterior cruciate ligament tears; Tegner scale; and suture number. Meniscal cysts developed in 14 of 102 cases. Two of the 14 cysts were symptomatic, requiring open cystectomy. The incidence of meniscal cyst was significantly higher in the AI group (12 of 30, 40%) than in the IO group (1 of 60, 1.7%) or the combined-technique group (1 of 12, 8.3%) (P < .001). Both symptomatic cysts were in the AI group and were in continuity with the anchors. Medial meniscus tear (odds ratio = 6.92) and the use of AI suture anchors (odds ratio = 15.03) significantly increased the risk of cyst formation. CONCLUSIONS: The incidence of meniscal cysts after arthroscopic meniscal repair was 1.7% to 40.0%, depending on the surgical method. Medial meniscus tears and use of an AI device are suggested as risk factors for cyst formation in this retrospective study. LEVEL OF EVIDENCE: Level Ⅲ, retrospective comparative study.

Prevalence, development, and factors associated with cyst formation after meniscal repair with the all-inside suture device.

PURPOSE: To investigate the prevalence of cyst formation after using all-inside meniscal repair device and analysed the risk factors associated with it. METHODS: Between August 2008 and September 2013, 51 menisci of 46 patients were included in the study, 46 menisci of which had concomitant anterior cruciate ligament (ACL) ruptures and had an ACL reconstruction. Magnetic resonance imaging (MRI) of the knee was performed at 3, 6, 12 and 24 months after meniscal surgery. The MRIs were assessed to detect the development of cysts encasing the suture anchors and to evaluate meniscal healing. Statistical analysis was performed using multiple regression analysis. RESULTS: Out of the 51 menisci examined, MRI revealed cysts in 15 menisci. Cysts were detected in 3 menisci at 6 months, in 9 menisci at 12 months, and in 3 menisci at 24 months after surgery. Only 3 patients (6.5%) were symptomatic, and cystectomy was performed in 2 of these patients and arthroscopic debridement in the other. Compared with using both the suture device and an inside-out suture repair, using the suture device alone was more likely to be associated with cyst development [odds ratio (OR), 12.04]. The medial meniscus was also significantly more likely to develop a cyst compared with the lateral meniscus (OR, 12.48). There was an increased outcome for the number of device use (P = 0.033). Though it was not statistically significant, the patients with anterior knee laxity (side-to-side difference > 3 mm using a knee arthrometer) were more likely to develop cysts than those without anterior knee laxity (P = 0.06). There were no significant differences between the remaining variables. CONCLUSIONS: The prevalence of cyst formation around the suture implant was 29%, but most cases were not symptomatic. Significant risk factors for cyst formation included the use of a suture device alone, and a location in the medial meniscus. LEVEL OF EVIDENCE: III.

The relationship between graft intensity on MRI and tibial tunnel placement in anatomical double-bundle ACL reconstruction.

PURPOSE: To determine whether the graft signal intensity of the anteromedial bundle (AMB) on MRI was related to the tibial tunnel placement, anterior-posterior (A-P) stability, and/or cyclops lesion formation following double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. METHODS: Between January 2010 and August 2016, 65 patients underwent arthroscopic DB-ACL reconstruction and were followed up for a minimum of 2 years. Follow-up included 1-week postoperative CT evaluation, 1-year postoperative MRI evaluation, and 2-year postoperative measurement of A-P instability using a KT-2000 arthrometer. Tibial tunnel placement and the location of Parson's knob were expressed as percentages. Patients were divided into two groups according to the graft signal intensity of the AMB on MRI: the high group (grades 2, 3; group H) and the low group (grade 1; group L). RESULTS: There were 23 knees in group H and 42 knees in group L. There was no difference between the two groups regarding the position of Parson's knob. The AMB placement in the tibial tunnel in group H was more anterior than that in group L. The incidence of a cyclops lesion was significantly greater in group H [13 cases (56.5%)] compared with group L [7 cases (16.7%); P = .05]. The arthrometric side-to-side difference was significantly greater in group H (1.67 mm) than in group L (0.90 mm; P = .019). CONCLUSION: Group H had a more anterior tunnel location and significantly greater incidence of cyclops lesions than group L. An increased signal intensity of the AMB on MRI indicates A-P instability. LEVEL OF EVIDENCE: Level III retrospective cohort study.

Novel Method of Quantifying Radioactive Cesium-Rich Microparticles (CsMPs) in the Environment from the Fukushima Daiichi Nuclear Power Plant.

Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined. Here, we report a novel method to quantify the number of CsMPs in surface soils at or around Fukushima and the fraction of radioactivity they contribute, which we call "quantification of CsMPs" (QCP) and is based on autoradiography. Here, photostimulated luminescence (PSL) is linearly correlated to the radioactivity of various microparticles, with a regression coefficient of 0.0523 becquerel/PSL/h (Bq/PSL/h). In soil collected from Nagadoro, Fukushima, Japan, CsMPs were detected in soil sieved with a 114 µm mesh. There was no overlap between the radioactivities of CsMPs and clay particles adsorbing Cs. Based on the distribution of radioactivity of CsMPs, the threshold radioactivity of CsMPs in the size fraction of <114 µm was determined to be 0.06 Bq. Based on this method, the number and radioactivity fraction of CsMPs in four surface soils collected from the vicinity of the FDNPP were determined to be 48-318 particles per gram and 8.53-31.8%, respectively. The QCP method is applicable to soils with a total radioactivity as high as ∼106 Bq/kg. This novel method is critically important and can be used to quantitatively understand the distribution and migration of the highly radioactive CsMPs in near-surface environments surrounding Fukushima.

Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant.

Trace U was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the meltdowns, but the speciation of the released components of the nuclear fuel remains unknown. We report, for the first time, the atomic-scale characteristics of nanofragments of the nuclear fuels that were released from the FDNPP into the environment. Nanofragments of an intrinsic U-phase were discovered to be closely associated with radioactive cesium-rich microparticles (CsMPs) in paddy soils collected ∼4 km from the FDNPP. The nanoscale fuel fragments were either encapsulated by or attached to CsMPs and occurred in two different forms: (i) UO2+X nanocrystals of ∼70 nm size, which are embedded into magnetite associated with Tc and Mo on the surface and (ii) Isometric (U,Zr)O2+X nanocrystals of ∼200 nm size, with the U/(U+Zr) molar ratio ranging from 0.14 to 0.91, with intrinsic pores (∼6 nm), indicating the entrapment of vapors or fission-product gases during crystallization. These results document the heterogeneous physical and chemical properties of debris at the nanoscale, which is a mixture of melted fuel and reactor materials, reflecting the complex thermal processes within the FDNPP reactor during meltdown. Still CsMPs are an important medium for the transport of debris fragments into the environment in a respirable form.

Predictive factors for osteochondritis dissecans of the lateral femoral condyle concurrent with a discoid lateral meniscus.

PURPOSE: Osteochondritis dissecans (OCD) of the lateral femoral condyle is relatively rare, and it is often reported in combination with discoid lateral meniscus. However, little is known about the mechanism underlying this connection. Predictive factors for OCD coinciding with discoid lateral meniscus in Japanese children and adolescents were assessed. METHODS: During 2000-2015, 152 knees in 133 patients aged 5-15 years were diagnosed with symptomatic complete discoid lateral meniscus. Patients were evaluated using radiography and magnetic resonance imaging (MRI). OCD was radiographically graded using the Brückl classification. Based on Ahn's MRI classifications, discoid lateral meniscus was divided into four types of meniscal shift: no shift (N), anterocentral (AC), posterocentral (PC), or central (C). Relationships between OCD and patient sex, age and Ahn's shift type were analysed. RESULTS: OCD of the lateral femoral condyle was associated with discoid lateral meniscus in 22 (14.5%) of 152 knees. OCD was classified as Brückl's stage 1 in 5 knees, stage 2 in 12, stage 3 in 3, stage 4 in 1, and stage 5 in 1. OCD was found in 12 of 96 knees (12.5%) with type N meniscal shift, 4 of 24 knees (16.7%) with type AC, 0 of 21 knees (0%) with type PC, and 6 of 11 knees (54.5%) with type C. Multivariate logistic regression analysis showed that males had a significantly increased odds ratio (OR) [14.8; 95% confidence interval (CI) 2.6-83.4]. Those aged 5-11 years had a significantly higher OR (12.5; 95% CI 2.8-55.9) than those aged 12-15 years. The OR for type C coinciding with OCD was significantly elevated (13.4; 95% CI 2.3-78.7). CONCLUSIONS: Concurrent OCD was found in 22 (14.5%) of 152 knees with discoid lateral meniscus. Male sex, young age (5-11 years), and having a type C meniscal shift of the discoid lateral meniscus as shown by MRI were found to be predictive factors for OCD of the LFC. LEVEL OF EVIDENCE: III.

The origin and distribution of CD68, CD163, and αSMA+ cells in the early phase after meniscal resection in a parabiotic rat model.

We previously reported that circulating peripheral blood-borne cells (PBCs) contribute to early-phase meniscal reparative change. Because macrophages and myofibroblasts are important contributors of tissue regeneration, we examined their origin and distribution in the reparative meniscus. Reparative menisci were evaluated at 1, 2, and 4 weeks post-meniscectomy by immunohistochemistry to locate monocytes and macrophages (stained positive for CD68 and CD163), and myofibroblasts (stained positive for αSMA). Of the total number of cells, 13% were CD68+ at 1 week post-meniscectomy, which decreased to 1% by 4 weeks post-meniscectomy; of these, almost half of CD68+ cells (49.4%: 98.8% as PBCs) were green fluorescent protein (GFP)-positive post-meniscectomy (1, 2, and 4 weeks), indicating that the majority of CD68+ cells were derived from PBCs. Of the total cells, 6% were CD163+ at 1 week post-meniscectomy, which decreased to 1% by week 4. Of the CD163+ cells, the majority were GFP-positive (42.5%: 85.0% as PBCs) after 1 week; however, this decreased significantly over time, which indicates that the majority of CD163+ cells are derived from PBCs during the early phase of meniscal reparative change, but are derived from resident cells at later time points. Of the total cells, 38% were αSMA+ at 1 week post-meniscectomy, which decreased to 3% by 4 weeks. The proportion of GFP-positive αSMA+ cells was 2.8% after 1 week, with no significant change over time, which indicates that the majority of αSMA+ cells originated from resident cells. Here, we describe the origin and distribution of macrophages and myofibroblasts during meniscal reparative change.

A case of asymptomatic bilateral massive pulmonary embolism after arthroscopic multiple knee ligament reconstruction.

Venous thromboembolism, which includes deep venous thrombosis (DVT) and pulmonary embolism (PE), is a serious complication after operations involving the lower extremities, and it can be fatal. However, few reports have described the incidence of PE and its associated risk factors after arthroscopic knee surgery. We present a case of bilateral massive PE of the main pulmonary arteries and DVT detected on multi-detector row computed tomography after arthroscopic multiple knee ligament reconstruction. Our patient was asymptomatic despite having several risk factors for thromboembolic events (43 years of age, a long operation time, obesity, and diabetes mellitus) and receiving no pharmacologic thromboembolic prophylaxis. Although fatality due to PE is relatively uncommon, when a patient has several risk factors for PE, perioperative thromboprophylaxis should be considered. Level of evidence IV.

Proposed Referential Index to Resect Femoroacetabular Cam-Type Impingement During Arthroscopy Using a Cadaveric Hip Model.

PURPOSE: To establish a reference index for the simple identification of the optimum resection point for cam-type impingement on arthroscopy. METHODS: Twelve cadaveric left hips with a 20° to 40° center-edge angle, without osteoarthritis, were examined (mean age, 85 ± 10.1 years). The pelvis was fixed such that the anterior pelvic plane and femur were parallel to the table. The resection line for impingement was first defined on the femoral head surface 5 mm distal to the acetabular labrum, from the 9-o'clock (anterior) to 12-o'clock (superior) position. Next, we measured the hip flexion angle necessary for the head-neck junction to reach the resection line. After positioning the wire on the femoral head surface along the resection line from the 9- to 12-o'clock area of the femoral head, we measured the target alpha angle on radiographs at 0°, 15°, 30°, 45°, and 60° of hip flexion using the frog-leg 45/45/30 view (45° of flexion, 45° of abduction, and 30° of external rotation) and Dunn 45 view (45° of flexion, 20° of abduction, and neutral rotation). RESULTS: The mean hip flexion angle at which the head-neck junction reached the resection line was 31° ± 4.6°. For 0°, 15°, 30°, 45°, and 60° of hip flexion, the mean target alpha angle was 75.5° ± 5.5°, 65.3° ± 5.6°, 56.3° ± 5.8°, 49.0° ± 6.6°, and 42.6° ± 5.8°, respectively, using the frog-leg 45/45/30 view and 75.0° ± 6.0°, 65.8° ± 6.2°, 57.2° ± 7.3°, 50.7° ± 6.9°, and 44.2° ± 5.8°, respectively, using the Dunn 45 view. There were no significant differences between the 2 radiographic techniques (P = .82, P = .84, P = .76, P = .57, and P = .52, respectively). CONCLUSIONS: A description of the degree of hip flexion during cam resection can affect the final alpha angle when using the labrum as a reference for resection. CLINICAL RELEVANCE: The described index allows systematic navigation of cam lesions during arthroscopy for femoroacetabular impingement patients using the hip flexion angle.

Direct bone-to-bone integration between recombinant human bone morphogenetic protein-2-injected tendon graft and tunnel wall in an anterior cruciate ligament reconstruction model.

PURPOSE: This study was performed to evaluate one-stage anterior cruciate ligament (ACL) reconstruction using a semitendinosus tendon graft injected with bone morphogenetic protein 2 (BMP-2) in a rabbit model. METHODS: We injected recombinant human BMP-2 (rhBMP-2) in the experimental group and phosphate-buffered saline in the control group at two sites of the semitendinosus tendon (15 µg in each site) to replace tendon with bone in the bone tunnel. Twenty minutes later, the injected tendon graft was transplanted for ACL reconstruction by passing the graft through the bone tunnel. The animals were harvested at four, eight, or 12 weeks postoperatively and examined by histological and biomechanical methods. RESULTS: Histological analysis revealed that the tendon graft was replaced with new bone in the tunnel of the experimental group. Characteristic features identical to the regenerated direct insertion morphology at the bone-tendon junction were acquired at eight or 12 weeks in the experimental group. Biomechanical pull-out testing revealed greater stiffness in the experimental than control group at 12 weeks, although the maximum load to failure showed no significant difference between the two groups at four, eight, or 12 weeks. CONCLUSION: These results indicate the potential for ACL reconstruction with regenerated direct insertion morphology.

Simple and convenient preconcentration procedure for the isotopic analysis of uranium in seawater.

The demand for monitoring anthropogenic U isotopes, 236U and 233U, in seawater will continue to increase due to radioecological issues and the need for tools for environmental dynamics research. In response to this growing demand, herein, a novel and simple method was developed for the collection of U isotopes in seawater, both in the laboratory and field, using a fabric-like amidoxime adsorbent. The results from the adsorption studies showed that the optimum conditions for processing seawater in a glass beaker were as follows: seawater pH 4, amidoxime adsorbent 0.20 mmol per 500 g seawater and an adsorption time of 9 hours. Alternatively, when using a closed polyethylene container in experiments on-board a ship and using the same ratio of adsorbent to seawater as in the beaker experiment in the laboratory, the optimum conditions were as follows: seawater pH 8 and an adsorption time of 24 hours. Under the above-mentioned conditions, more than 95% of the U underwent adsorption in both the beaker and the polyethylene container experiments. In the case of analyte desorption, more than 80% of U in seawater was recovered using 2-3 mol dm-3 HCl or HNO3 as the eluent. Thus, it was concluded that the amidoxime adsorbent can serve as a simple and effective pre-concentration method for the ultra-trace monitoring of U isotopes in seawater.