Posterior wall blowout on computed tomography after anterior cruciate ligament reconstruction.

BACKGROUND: During anterior cruciate ligament (ACL) reconstruction, even when a posterior wall of the femoral bone tunnel is identified, computed tomography (CT) occasionally demonstrates a breach of the posterior femoral cortex of the femoral bone tunnel, i.e., posterior wall blowout, after ACL reconstruction (posterior wall blowout-like phenomenon). This study aimed to investigate the influence of the posterior wall blowout-like phenomenon on clinical outcomes after ACL reconstruction using hamstring tendon. METHODS: A total of 105 patients who underwent CT examination two weeks after ACL reconstruction were enrolled. A cortical suspension device was used for femoral side fixation in all cases. Posterior wall was identified in all cases during the surgery. The side-to-side difference in anterior knee laxity, pivot shift test, Lysholm knee score, the International Knee Documentation Committee (IKDC) subjective form, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were evaluated one year after the surgery. A second CT examination was performed 6-12 months after the surgery, if a posterior wall blowout-like phenomenon was identified in the first CT examination. RESULTS: Two weeks after the surgery, 16 of the 105 patients showed a posterior wall blowout-like phenomenon. Twelve of the 16 cases demonstrated a regenerated posterior femoral cortex of the femoral bone tunnel on their second CT images. There were no significant differences between the posterior wall blowout-like phenomenon group and the normal posterior wall group in terms of a side-to-side difference in anterior knee laxity (0.4 ± 1.5 mm and 0.1 ± 1.6 mm, respectively), pivot shift test, Lysholm knee score, IKDC score, and KOOS at one year after surgery. The length and diameter of the femoral bone tunnel were not significantly different between the two groups. CONCLUSIONS: Posterior wall blowout-like phenomenon after ACL reconstruction using a cortical suspension device did not negatively influence clinical outcomes. LEVEL OF EVIDENCE: III - retrospective comparative clinical study.

An older age, a longer duration between injury and surgery, and positive pivot shift test results increase the prevalence of articular cartilage injury during ACL reconstruction in all three compartments of the knee in patients with ACL injuries.

PURPOSE: To investigate factors that influence the prevalence of articular cartilage injury in patients with anterior cruciate ligament (ACL) injury. METHODS: This multicentre study included patients with ACL injury. Logistic regression analysis was conducted to identify factors that influence the prevalence of cartilage injury during ACL reconstruction. RESULTS: A total of 811 patients were enrolled. The factors that significantly influenced the prevalence of cartilage injury were age (odds ratio [OR], 1.04; P = 0.000), a positive pivot shift test result (OR, 1.43; P = 0.021), medial meniscal injury (OR, 2.55; P = 0.000), and delayed surgery (≥ 12 months) (OR, 2.52; P = 0.028) in the medial compartment of the knee; age (OR, 1.05; P = 0.000), subjective grades of apprehension during the pivot shift test (OR, 1.46; P = 0.010), lateral meniscal injury (OR, 1.98; P = 0.003), femoro-tibial angle (FTA) (OR, 0.92; P = 0.006), and delayed surgery (≥ 12 months) (OR, 2.63; P = 0.001) in the lateral compartment; and age (OR, 1.06; P = 0.000), body mass index (OR, 1.07; P = 0.028), a positive pivot shift test result (OR, 1.60; P = 0.018), FTA (OR, 0.90; P = 0.006), and delayed surgery (≥ 12 months) (OR, 3.17; P = 0.008) in the patellofemoral compartment. CONCLUSION: An older age, a longer duration between injury and surgery, and a positive pivot shift test result were positively associated with the prevalence of cartilage injury in three compartments in patients with ACL injuries. Early ACL reconstruction is recommended to prevent cartilage injury. LEVEL OF EVIDENCE: Level III.

Application of a true lateral virtual radiograph from 3D-CT to identify the femoral reference point of the medial patellofemoral ligament.

PURPOSE: The purpose of this study is two-fold: (1) to describe the femoral reference point of the medial patellofemoral ligament (MPFL) on a virtual true lateral radiograph reconstructed from a three-dimensional computed tomography (3D-CT) image and (2) to compare this point with that of patients without patellofemoral instability and with Schöttle's point. METHODS: A total of 26 consecutive patients (29 affected knees) with recurrent patellar dislocation (RPD), who underwent MPFL reconstruction were included in this study (4 males; 22 females; mean age, 24.0 years old). Using a true lateral 3DCT image, the MPFL femoral insertion was identified and marked with a 2-mm circle, and this image was reconstructed as a virtual true lateral radiograph. Following Schöttle's method, the point of intersection was described by their anterior-posterior and proximal-distal positions. As a control population, 29 age- and gender-matched patients with anterior cruciate ligament (ACL) injuries were also analysed. RESULTS: The points in RPD patients were located significantly posterior (-2.5 ± 2.3 mm, p < 0.01) to the line representing an extension of the posterior cortex of the femur and distal (- 6.9 ± 2.4 mm, p < 0.01) to the posterior origin of the medial femoral condyle compared with those in the control population. The mean reference point of RPD patients was located in a 3.8-mm posterior and 4.4-mm distal position compared with Schöttle's point. CONCLUSIONS: An anatomical and radiographic femoral reference point of the MPFL on a true lateral virtual radiograph was described with our method. In patients with RPD, this reference point was identified to be more posterior and distal to Schöttle's point. More anatomical and individualized MPFL reconstruction will be secured using our method. LEVEL OF EVIDENCE: Level IV.

The safety and efficacy of magnetic targeting using autologous mesenchymal stem cells for cartilage repair.

PURPOSE: A new cell delivery system using magnetic force, termed magnetic targeting, was developed for the accumulation of locally injected cells in a lesion. The aim of this study was to assess the safety and efficacy of mesenchymal stem cell (MSC) magnetic targeting in patients with a focal articular cartilage defect in the knee. METHODS: MSC magnetic targeting for five patients was approved by the Ministry of Health Labour and Welfare of Japan. Autologous bone marrow MSCs were cultured and subsequently magnetized with ferucarbotran. The 1.0-T compact magnet was attached to a suitable position around the knee joint to allow the magnetic force to be as perpendicular to the surface of the lesion as possible. Then 1 × 107 MSCs were injected into the knee joint. The magnet was maintained in the same position for 10 min after the MSC injection. The primary endpoint was the occurrence of any adverse events. The secondary endpoints were efficacy assessed by magnetic resonance imaging (MRI) T2 mapping and clinical outcomes using the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation and the Knee Injury and Osteoarthritis Outcome Score (KOOS). RESULTS: No serious adverse events were observed during the treatment or in the follow-up period. Swelling of the treated knee joint was observed from the day after surgery in three of the five patients. The swelling resolved within 2 weeks in two patients. MRI showed that the cartilage defect areas were almost completely filled with cartilage-like tissue. MOCART scores were significantly higher 48 weeks postoperatively than preoperatively (74.8 ± 10.8 vs 27.0 ± 16.8, p = 0.042). Arthroscopy in three patients showed complete coverage of their cartilage defects. Clinical outcome scores were significantly better 48 weeks postoperatively than preoperatively for the IKDC Subjective Knee Evaluation (74.8 ± 17.7 vs 46.9 ± 17.7, p = 0.014) and knee-related quality-of-life (QOL) in the KOOS (53.8 ± 26.4 vs 22.5 ± 30.8, p = 0.012). CONCLUSION: Magnetic targeting of MSCs was safely performed and showed complete coverage of the defects with cartilage-like tissues and significant improvement in clinical outcomes 48 weeks after treatment. The magnetic targeting of MSCs is useful as a minimally invasive treatment for cartilage repair. LEVEL OF EVIDENCE: IV.

Morphologic evaluation of remnant anterior cruciate ligament bundles after injury with three-dimensional computed tomography.

PURPOSE: This study aimed to investigate the morphological patterns of remnant anterior cruciate ligament bundles after injury (ACL remnant) on three-dimensional computed tomography (3DCT) and compare them with those on arthroscopy. METHODS: Sixty-three patients (33 males and 30 females; mean age 25.2 ± 10.1 years) who had undergone primary ACL reconstruction between March 2011 and December 2012 were included in this study. The average durations between traumas and 3DCT and between 3DCT and surgery were 101.7 ± 87.2 and 38.2 ± 38.7 days, respectively. ACL remnants were classified into four morphological patterns on 3DCT. 3DCT findings were compared with arthroscopic findings with and without probing. RESULTS: The morphological patterns of the ACL remnants on 3DCT were well matched with those on arthroscopy without probing (the concordance rate was 77.8%). However, the concordance rate was reduced to 49.2% when arthroscopic probing was used to confirm the femoral attachment of ACL remnants (p ≤ 0.05). CONCLUSIONS: This study demonstrates that the morphological patterns of ACL remnants on 3DCT were well matched with those on arthroscopy without probing. Therefore, the technique can be useful for preoperative planning of the ACL reconstruction or informed consent to the patients. However, for definitive diagnosis, arthroscopic probing is required. LEVEL OF EVIDENCE: IV.

Functional and radiographic outcomes of unstable juvenile osteochondritis dissecans of the knee treated with lesion fixation using bioabsorbable pins.

BACKGROUND: The purpose of this study was to evaluate the functional and radiographic outcome of fixation of unstable juvenile osteochondritis dissecans lesions of the knee after a minimum of 2 years of follow-up. METHODS: A total of 33 unstable juvenile osteochondritis dissecans lesions in 30 patients underwent fixation using bioabsorbable pins through arthrotomy or under arthroscopy. The patients consisted of 23 males and 7 females, and the average age at the time of operation was 14.4 years (range, 11 to 17 y). The functional outcomes were evaluated using the Lysholm score and Hughston's criteria at a mean follow-up of 3.3 years (range, 2.1 to 6.3 y). Healing of the osteochondritis dissecans lesions were confirmed by plain radiographs and magnetic resonance imaging. RESULTS: The Lysholm score improved significantly at 3 months after the surgery, and was maintained until the final follow-up. Radiographically, 32 of 33 lesions healed after fixation of the lesion (healing rate was 97.0%). Healing was achieved at an average of 2.4 months on plain radiographs and 4.2 months on magnetic resonance imaging. According to Hughston's criteria, 25 patients were graded as excellent, 4 as good, and 1 as poor at the final follow-up. CONCLUSIONS: The fixation of the unstable juvenile osteochondritis dissecans lesions with bioabsorbable pins demonstrated improved clinical outcomes and radiographic high healing rates at a mean of 3.3 years of follow-up. We advocate this procedure for patients with unstable juvenile osteochondritis dissecans lesions of sufficient quality to enable fixation which will preserve the normal contour of the distal femur. LEVEL OF EVIDENCE: Level IV-retrospective case series.

Implantation of tissue-engineered cartilage-like tissue for the treatment for full-thickness cartilage defects of the knee.

PURPOSE: The purposes of this study were to evaluate early- to midterm clinical results after implantation of tissue-engineered cartilage-like tissue for the treatment for full-thickness cartilage defects of the knee and to identify the factors affecting the final clinical results. METHODS: Tissue-engineered cartilage-like tissue was prepared by culturing autologous chondrocytes in atelocollagen gel for 3-4 weeks. A total of 73 knees of 72 patients with full-thickness cartilage defects were implanted with this tissue-engineered cartilage-like tissue. The follow-up of these patients for >5 years (range 5-11 years, median 8.0 years) is reported. The patients were evaluated clinically using a rating scale, as well as arthroscopically, biomechanically, and histologically. A modified magnetic resonance observation of cartilage repair tissue (MOCART) system was used to quantify the magnetic resonance imaging (MRI) findings of the lesions. The patient or defect factors influencing the final clinical outcomes were also investigated. RESULTS: Clinical rating improved significantly after implantation of tissue-engineered cartilage-like tissue. Arthroscopic findings at 2 years after implantation were graded as normal or nearly normal according to the International Cartilage Repair Society (ICRS) scale in 64 of 73 knees (87.7%). Biomechanically, stiffness of the graft almost equalled the surrounding normal cartilage (87.9-102.5%) at 2 years after implantation. Histologically, overall assessment of the repaired tissue by ICRS Visual Assessment Scale II was 70.4 ± 20.8. The average MOCART score was 13.5 ± 11.3 (0-45) preoperatively, 66.6 ± 16.8 (10-90) at 1 year after implantation, 70.4 ± 16.1 (15-90) at 2 years after implantation, and 72.5 ± 17.4 (15-95) at the final follow-up, indicating that MRI results were maintained. Among the factors investigated, only arthroscopic grade of the repaired lesion at 2 years after implantation was significantly correlated with the final clinical scores. CONCLUSIONS: Implantation of tissue-engineered cartilage-like tissue for the cartilage defects of the knee was effective in short- to midterm post-operatively. This procedure can be proposed as one option for repairing full-thickness cartilage defect of the knee. LEVEL OF EVIDENCE: IV.

Far anteromedial portal technique for posterolateral femoral tunnel drilling in anatomic double-bundle anterior cruciate ligament reconstruction: a cadaveric study.

PURPOSE: To identify the relationship between knee flexion angle and femoral tunnel length, as well as the exit points of guidewires, when using a far anteromedial portal technique for posterolateral femoral tunnel drilling in double-bundle anterior cruciate ligament reconstruction. METHODS: Using the far anteromedial portal technique in 8 cadaveric knees, femoral tunnel drilling for the posterolateral bundle was performed at 3 knee flexion angles: 90°, 110° and 130°. We measured the femoral tunnel length and the distances from each guidewire to the closest relevant structures. RESULTS: The mean tunnel length at 90° knee flexion (25.8 ± 1.8 mm) was significantly shorter than the length at 110° and 130° knee flexion (32.1 ± 2.6 and 33.1 ± 2.5 mm, respectively). The average distance between the exit point of the guidewire and the posterior articular cartilage of the lateral femoral condyle was the shortest at 90° knee flexion (3.3 ± 2.2 mm). The distance between the guidewire and the centre of the origin of the lateral collateral ligament was the shortest at 130° knee flexion (8.0 ± 1.8 mm). The guidewires penetrated the origin of the lateral gastrocnemius tendon in 2 cases at 110° knee flexion and in 1 case each at 90° and 130° knee flexion. CONCLUSIONS: When using the far anteromedial portal technique, more than 110° knee flexion is desirable to achieve ideal femoral tunnel length and avoid articular cartilage injury. In addition, the risk of damage to the origin of the lateral collateral ligament increases when the knee flexion angle increases to 130°. A knee flexion angle between 110° and 120° was recommended when using the far anteromedial portal technique.

Regenerative medicine in orthopedics using cells, scaffold, and microRNA.

Cells, scaffold, and growth factors are crucially important in regenerative medicine and tissue engineering. Progress in science and technology has enabled development of these three factors, with basic research being applied clinically. In the past decade, we have investigated tissue regeneration in animal models of musculoskeletal disorders by using cells, scaffold, and delivery systems which has been relatively easy to apply and develop in clinical settings. Moreover, microRNA (miRNA), which are important in biological processes and in the pathogenesis of human diseases, have been used in research on regenerative medicine. For the cell source, we focused on mesenchymal stem cells (MSC) and CD34(+) and CD133(+) cells as endothelial progenitor cells for regeneration of musculoskeletal organs. These cells are accessible and safe. For less invasive and more effective therapy, we developed a novel cell-delivery system using magnetic force to accumulate cells at a desired site. Furthermore, administration of synthetic miRNA could enhance tissue regeneration. In our studies, use of these cells combined with a cell-delivery system, miRNA, scaffold, and cytokines has led to effective regeneration of musculoskeletal tissues including cartilage, bone, ligaments, muscle, peripheral nerves, and spinal cord. The current and future objective is more effective and less invasive cell-based therapy with spatial control of transplanted cells by use of an external magnetic force. Analysis of efficiency, safety, and the mechanism of tissue regeneration by cells, scaffold, and miRNA will lead to more promising regenerative medicine, involving the development of a new generation of therapy. This review will focus on our regenerative medicine research, which focuses on clinical application of cells, scaffold, and miRNA.

Increased Posterior Condylar Offset Decreases the Extension Gap in Cases With Flexion Contracture in Modified Gap Technique Total Knee Arthroplasty.

Purpose There have been no reports comparing the change in medial and lateral posterior condylar offset (PCO) and the extension gaps. The purpose of this study was to elucidate the relationship between the change in medial and lateral PCO and the extension gap in total knee arthroplasty (TKA). The hypothesis is that an increase in both medial and lateral PCO can be a factor for a decrease in the extension gap, especially in cases of flexion contracture. Methods This retrospective study included 63 patients with medial osteoarthritis who underwent mobile-bearing PS-TKA using the modified gap techniques. Patients consisted of seven men (seven knees) and 53 women (56 knees), with the mean age of 76 (range, 58-88) years. The patients with valgus knee and cruciate retaining TKA were excluded. The medial ΔPCO (ΔPCO defined as the amount of change of the PCO before the resection of the posterior condyle and after the implant setting), lateral ΔPCO, the rotation angle of the posterior condyle osteotomy, and the gap differences were evaluated. The data were compared among three groups（Group A: ΔPCO increase on both sides, Group B: ΔPCO increase on only one side, Group C: ΔPCO decrease on both sides. The gap differences were compared between the cases with flexion contracture of ≥ 15° and the cases with flexion contracture of < 15°. The correlations between the gap differences and flexion contracture were evaluated in each group. Results There was no gap difference evident in any group (P≥0.05). The gap difference in Groups A (P=0.0067) and group C (P=0.0484) was significantly larger in cases with flexion contracture of ≥ 15° compared to those with flexion contracture of < 15°. Conclusions There was no correlation between the change in PCO and the extension gap. However, there was an inverse correlation between the flexion contracture and extension gap in cases with increased medial and lateral PCO.

Combined over-the-top reconstruction with posterolateral bundle remnant re-tensioning in pediatric anterior cruciate ligament reconstruction: A technical note.

Epiphyseal injury, particular on femoral side, is a major concern in pediatric anterior cruciate ligament (ACL) reconstruction. Therefore, the over-the-top route (OTTR) method has frequently been selected in pediatric ACL reconstruction, with good clinical results reported. However, a cadaver study reported the inferior rotational stability of the OTTR method to that of anatomical single bundle reconstruction. In recent years, a new method of reconstruction, which involves the remnant being detached, re-tensioned, and re-attached, achieved good short-term results. We developed a surgical method to restore the remnant to the posterolateral (PL) bundle footprint and obtain rotational stability in patients, thereby preserving the remnant. We hypothesized that repairing the residual remnant to the PL bundle footprint in pediatric ACL reconstruction could achieve rotational stability. This report offers the surgical techniques for PL bundle tensioning repair using remnants in the pediatric ACL OTTR procedure.

Effect of lateral wedge insole on medial meniscus extrusion and its association with knee osteoarthritis progression.

BACKGROUND: Medial meniscus extrusion (MME) is associated with knee osteoarthritis (OA) progression because of increased loading stress in the medial compartment of the knee. Using a lateral wedge insole (LWI) decreases loading stress and immediately reduces MME. OBJECTIVE: To investigate whether the wearing duration of LWI affects the midterm response to MME and is associated with knee OA progression. STUDY DESIGN: Cohort study. METHODS: Twenty-three patients with knee OA who were conservatively treated with LWI were classified according to the duration of the LWI wear per day: less than 5 h (short-duration group) or over 5 h (long-duration group). MME was evaluated in the single-leg standing position by ultrasound. Knee OA progression and limb alignment were evaluated radiographically. These evaluations were performed thrice: at the initial office visit as a baseline without LWI (time 0), with LWI (LWI-time 0), and 1 year after intervention with LWI (LWI-1 year). RESULTS: In both groups, the MMEs at LWI time 0 were significantly decreased compared with those at time 0. In the long-duration group, this reduction in MME was maintained 1 year after the intervention compared with time 0 (time 0: 3.9 ± 0.9, LWI-1 year: 2.6 ± 1.1), but this improvement was not observed in the short-duration group (time 0: 3.8 ± 1.7, LWI-1 year: 3.6 ± 1.7). In addition, three of four patients demonstrated OA progression, and varus alignment had significantly progressed compared with that at time 0 in the short-duration group. However, the long-duration group showed OA progression only in one patient and maintained limb alignment. CONCLUSIONS: The duration of wearing LWI affects the midterm reduction of MME and knee OA progression while maintaining limb alignment.

Medial meniscus extrusion during gait is associated with decrease in knee rotation in early-stage knee osteoarthritis.

BACKGROUND: In patients with medial knee osteoarthritis (OA), medial meniscus extrusion during gait is aggravated by mechanical stress, such as knee adduction moment (KAM). Conversely, the decrease in the range of knee rotation during stance phase is also one of the important issues in early knee OA, whereas the correlation between medial meniscus extrusion and knee rotation during gait are unclear. RESEARCH QUESTION: To investigate the correlation between increase in medial meniscus extrusion and range of knee rotation during gait in patients with early- and late-stage of knee OA. METHODS: Forty patients with medial knee OA were enrolled and divided into early- and late-OA group by Kellgren-Lawrence grading scale. During gait tasks, the extent of medial meniscus extrusion was measured using ultrasonography and kinetic/kinematic data were measured using three-dimensional motion analysis system. The correlation between medial meniscus extrusion and the range of knee rotation or KAM were evaluated in the overall, early-, and late- OA groups. RESULTS: A significant negative correlation was observed between an increase in medial meniscus extrusion and range of knee rotation angle in early-OA group only. However, an increase in medial meniscus extrusion significantly correlated with the second KAM peak in the overall and early-OA groups. SIGNIFICANCE: The decrease in range of knee rotation during stance phase may be associated with the increase in medial meniscus extrusion during gait in patients with early knee OA.

Treatment of cartilage defects by subchondral drilling combined with covering with atelocollagen membrane induces osteogenesis in a rat model.

BACKGROUND: The coverage of the atelocollagen membrane at the chondral defect after subchondral drilling might improve the beneficial effects for cartilage repair because of the prevention of scattering and accumulation of cells and growth factors from bone marrow within the chondral defect. On the other hand, it might block cells and factors derived from the synovium or cause high pressure in the chondral defect, resulting in prevention of cells and growth factors gushing out from the bone marrow, which leads to disadvantages for cartilage repair. METHOD: We tested this hypothesis in a 2-mm-diameter chondral defect created in the articular cartilage of the patellar groove in a rat models. Defects were left untreated, or were drilled or drilled and covered with an atelocollagen membrane; healing was evaluated by histology and gene expression analysis using real-time polymerase chain reaction and immunohistochemistry. RESULTS: Membrane coverage induced bone tissue ingrowth into the punched chondral defect. At 1 week, expression of TGFß, Sox9, Runx2, osteocalcin, Col1a1, and Col2a1 in the drilling group was significantly higher than in the covering group. At 4 weeks, expressions of TGFß, Runx2, and Col1a1 were all significantly higher in the drilling group, while Sox9, osteocalcin, and Col2a1 were significantly higher in the covering group. Immunohistochemistry demonstrated Sox9, osteocalcin, and type II collagen on the bony reparative tissue in the covering group. CONCLUSIONS: These results suggest that the atelocollagen membrane coverage resulted in inhibition of cartilage repair.

Comparison of clinical outcomes between anterior cruciate ligament reconstruction with over-the-top route procedure and anatomic single-bundle reconstruction in pediatric patients.

The purpose of this study is to evaluate the clinical results of over-the-top route (OTTR) reconstruction for pediatric anterior cruciate ligament (ACL) injuries and compare them with results of anatomic single-bundle reconstruction (SBR), which used the bone tunnel technique and was performed early after epiphyseal closure (age ≤15 years). This study included pediatric patients aged 11-15 years who underwent ACL reconstruction. The mean age at surgery was 13.4 years (11-15 years), including 14 men and 29 women. Operative procedures were determined according to growth plate closure. In all cases, the tibial side was reconstructed using a bone tunnel procedure. On the femoral side, we selected the OTTR procedure (group O) with open physis. Where the physis was closed, we selected the anatomical SBR (group B). The clinical results were evaluated with manual examination, the side-to-side difference (SSD) in tibial anterior translation using the Kneelax 3, and knee function score. There were no significant differences in the Lachman and pivot-shift tests, SSD in tibial anterior translation with Kneelax 3, or knee function score between the two groups before or after the surgery. Growth disturbance was not observed on either the femoral or tibial side in group O. The OTTR method provided comparable results with the bone tunnel anatomical method in manual examination, Kneelax 3, and knee clinical function scores, suggesting that the OTTR method is very useful for pediatric ACL reconstructions. Level of evidence: III; retrospective study.

Needle Arthroscopy as a Promising Alternative to MRI for the Diagnosis of Meniscus Injury.

Meniscal injury is a common cause of knee pain and functional impairment, often necessitating surgical intervention. Although magnetic resonance imaging (MRI) is frequently used for diagnosis, its accuracy is variable and may lead to false positives and negatives. To address these issues, needle arthroscopy has gained attention as a potential diagnostic alternative to MRI because of its immediate availability and ability to directly visualize intra-articular structures. This study aimed to assess the diagnostic capabilities of needle arthroscopy in comparison with MRI and diagnostic arthroscopy for meniscal injuries. Forty patients with suspected meniscal injuries requiring surgical treatment were enrolled between November 2017 and March 2019. A needle arthroscope with a 0.95-mm diameter was used to evaluate meniscal injuries. Three orthopaedic surgeons with approximately 10 years of experience independently evaluated the images from the needle arthroscopy, diagnostic arthroscopy, and preoperative MRI without any knowledge regarding patients' information. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each modality were used to compare the diagnostic accuracies. For lateral meniscus (LM) injuries, the sensitivity, specificity, PPV, and NPV of needle arthroscopy compared to diagnostic arthroscopy were 0.706, 0.852, 0.148, and 0.294, respectively. For medial meniscus (MM) injuries, the corresponding values were 0.889, 0.864, 0.136, and 0.111, respectively. In comparison, MRI had a lower sensitivity for LM injuries (0.588) and a higher sensitivity for MM injuries (1.0). The agreement between diagnostic arthroscopy and needle arthroscopy was moderate (kappa=0.517), while the agreements between diagnostic arthroscopy or needle arthroscopy and MRI were poor. Similar patterns were observed for the presence, location, and tear patterns of meniscal injuries. In conclusion, needle arthroscopy shows promise as an effective diagnostic modality for meniscal injuries, surpassing the limitations of MRI.

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy.

Background: This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO. Methods: We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain. Results: Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO. Conclusions: HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Unique patterns of medial meniscus extrusion during walking and its association with limb kinematics in patients with knee osteoarthritis.

Medial meniscus extrusion (MME) is exacerbated by repeated mechanical stress. Various factors would affect MME; however, there is limited information about the behaviour of the medial meniscus during walking in patients with knee osteoarthritis (KOA). This study aimed to investigate the pattern of MME during walking and its association with limb biomechanics in patients with KOA. Fifty-five patients with KOA and ten older adult volunteers as a control group were involved in this study. The MME and limb biomechanics during walking were evaluated simultaneously by ultrasound and a motion analysis system, respectively. The waveform was constructed from the values of MME, and the point showing the highest value of MME was identified during the gait cycle. According to the peak timing of MME in the waveform, the pattern of the waveform was evaluated and compared to the control group. Lateral thrust, knee adduction moment (KAM), and flexion moment were obtained from motion analysis, and their association with the MME was evaluated. The patients with KOA demonstrated unique peak timing during walking. Compared to the control group, there were three groups of MME waveforms, early (< 59%), normal (60-83%), and late (> 84%) from the peak timing in the gait cycle. The pattern of MME waveform in early, normal, and late groups was correlated with the first KAM and lateral thrust, second KAM, and knee flexion moment, respectively. A unique MME pattern during walking was demonstrated, and these patterns were associated with limb biomechanics in patients with KOA.

Visualization of lateral meniscus extrusion during gait using dynamic ultrasonographic evaluation.

PURPOSE: Medial meniscus extrusion is one of the risk factors for knee osteoarthritis (OA). However, lateral meniscus extrusion has not been discussed, and detailed information remains unknown. In particular, the lateral meniscus has high mobility and is expected to be difficult to evaluate in terms of its behavior under static conditions. Dynamic ultrasonographic evaluation was introduced to detect the dynamic behavior of the meniscus during walking. In this study, we aimed to investigate the behavior of the lateral meniscus during walking using dynamic ultrasonographic evaluation. METHODS: Sixteen participants with knee OA were recruited in this study. The change of lateral meniscus extrusion during walking was recorded using ultrasonography. Medial and lateral meniscal extrusion during the stance phase was measured, and meniscal mobility was defined as the difference in meniscal extrusion between minimum and maximum values (mm), medial meniscal extrusion (∆MME), and lateral meniscal extrusion (∆LME), respectively. The walking cycle and gait forms of lateral thrust were also evaluated using three-dimensional motion analysis systems and analyzed in terms of the correlation with ∆MME and ∆LME. RESULTS: The lateral meniscus was depicted in the articular plane, and extrusion decreased during the stance phase of the gait cycle. The ∆LME was significantly higher than the ∆MME (p < 0.01). There was a significant positive correlation between ∆LME and lateral thrust (r = 0.62, p < 0.05). CONCLUSIONS: We found that dynamic ultrasonographic evaluation can be used to visualize lateral meniscus extrusion during walking, and that its behavior is correlated to the degree of lateral thrust.