Variations in knee cartilage thickness: Fully automatic three-dimensional analysis of MRIs from five manufacturers.

BACKGROUND: Measurements of knee cartilage thickness derived from MR images are attractive biomarkers for osteoarthritis research. Although some cross-sectional multivendor studies exist, none have employed fully automatic three-dimensional MRI analysis. Our objective was to evaluate the variations in knee cartilage thickness measurements obtained using automated methods and MRI instruments from five different vendors. METHODS: The subjects were 10 healthy volunteers aged 22-60 years. MRI models with 3 Tesla strength from five different companies were used. Cartilage thickness was quantified fully automatically for seven regions. We hypothesized that "the MRI model influences cartilage thickness measurements." Inter-measurement error, defined as the absolute difference between the targeted and median thicknesses determined by the five MRI models, was analyzed using histograms. The factors generating the largest inter-measurement error were also examined. RESULTS: No exceptional trends attributable to a specific instrument model were observed, and the p-value from the Kruskal-Wallis test exceeded 0.05 in all seven regions. Therefore, the study hypothesis was rejected. Of the 350 measurements, the inter-measurement error was ≤0.05 mm in 53 %, ≤0.10 mm in 75 %, and ≤0.20 mm in 95 %. Analysis of the medial tibial cartilage, which had the largest inter-measurement error, revealed mis-extraction of synovial fluid as cartilage. CONCLUSIONS: The choice of MRI model did not influence cartilage thickness measurements. Overall, 95 % of the inter-measurement errors were within 0.20 mm. The greatest error resulted from mis-extracting synovial fluid as cartilage.

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.

Unique Anatomical Features of the Discoid Lateral Meniscus via Three-Dimensional MRI.

Background The discoid lateral meniscus (DLM) is a unique anatomical variant characterized by a larger, thicker lateral meniscus. For clinical diagnosis of DLM, coronal and sagittal slices in two-dimensional (2D) MRI and arthroscopic imaging are typically employed. However, evaluating the entire shape of the DLM is challenging due to the limited views and details provided by these methods. Three-dimensional (3D) visualization with MRI offers a more comprehensive view of the entire meniscus. The purpose of this study was to demonstrate the entire shape of a DLM using 3D images and unveil its unique characteristics. Methods The study population consisted of 31 knees diagnosed with DLM through arthroscopic examination at our hospital between 2017 and 2021. This group comprised 20 males (65%) and 11 females (35%), with ages ranging from 9 to 49 years (mean age, 24.2 years). Furthermore, a control group of 43 knees without DLM was included for comparative analysis. This control group consisted of 22 males (51%) and 21 females (49%), with ages ranging from 9 to 69 years (mean age, 28.5 years). 3D images of the medial meniscus (MM) and lateral meniscus (LM) were reconstructed from 1.5T-MRI images with semi-automatic segmentation using free software. From the coordinate information, the anterior-to-posterior lengths of the MM and LM were obtained, and the medial-to-lateral anterior-to-posterior length (L/M ratio) ratio was calculated and compared with the value of the non-DLM population. Results Our method allows for the detailed delineation of the DLM's unique morphology. The DLM group exhibited a significantly smaller L/M ratio compared to the non-DLM group (DLM: 0.66±0.06, non-DLM: 0.74±0.05, p<0.001). Conclusions Reconstructed 3D images could help to demonstrate the whole morphology of DLM and reveal its unique features, in which DLM shows a significantly smaller L/M ratio as compared to non-DLM.

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.

Cumulative knee adduction moment during jogging causes temporary medial meniscus extrusion in healthy volunteers.

PURPOSE: The cumulative knee adduction moment (KAM) is a key parameter evaluated for the prevention of overload knee injuries on the medial compartment. Medial meniscus extrusion (MME), typical in hoop dysfunctions, is a measure for the cumulative mechanical stress in individual knees; however, its correlation with cumulative KAM is unknown. The aim of this study was to investigate the effect of temporary overload stress on MME and its correlation with cumulative KAM. METHODS: Thirteen healthy asymptomatic volunteers (13 knees) were recruited for a cohort study (mean age, 23.1 ± 3.3 years; males: n = 8). The cumulative KAM was calculated using a three-dimensional motion analysis system, in addition to the number of steps taken while jogging uphill or downhill. MME was evaluated using ultrasound performed in the standing position. The evaluations were performed four times: at baseline (T0), before and after (T1 and T2, respectively) jogging uphill or downhill, and 1 day after (T3) jogging. Additionally, the Δ-value was calculated using the change of meniscus after efforts as the difference in MME between T1 and T2. RESULTS: The MME in T2 was significantly greater than those in T0 and T1. Conversely, the MME in T3 was significantly lesser than that in T2. No significant difference was found between those in T0 and T1, and T3. ΔMME exhibited a significant positive correlation with the cumulative KAM (r = 0.68, p = 0.01), but not for peak KAM. CONCLUSION: The temporary reaction of MME observed in ultrasound correlates with the cumulative stress of KAM.

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.

Equivalent outcomes of ACL revision with over-the-top single and double-bundle reconstruction using hamstring tendon compared to anatomical single and double-bundle reconstruction.

PURPOSE: In revision anterior cruciate ligament reconstruction (ACLR), our procedure of choice is the over-the-top route (OTTR) for cases where it is difficult to use a primary bone tunnel or to create a new bone tunnel due to the enlargement or malposition of the bone tunnel. Depending on the condition of the primary bone tunnel, we choose single (bone tunnel or OTTR) or double (bone tunnel or anteromedial (AM) bundle: OTTR /posterolateral (PL) bundle: bone tunnel) for femoral fixation. This study showed the results of single and double OTTR revision ACLR using the hamstring tendon. METHODS: Seventy-eight patients, who underwent revision ACLR using the hamstring tendon and who could be followed up for more than 2 year, were included in this study. The methods of revision ACLR were single in 54 cases (bone tunnel: 24 cases; OTTR method: 30 cases) and double in 24 cases (bone tunnel: 16 cases; OTTR for AM bundle and bone tunnel for PL bundle: eight cases). The cause of re-injury, the meniscus and cartilage injury, the reconstruction method, and the Lysholm score, Lachman test, Pivot-shift test, and the side-to-side difference in the tibial anterior translation were evaluated before and after surgery. RESULTS: There was no statistically significant difference in the Lyshom score, Lachman / Pivotshift test and side-to-side difference anterior translation of the tibia between the four groups. CONCLUSIONS: The clinical results of single and double OTTR revision ACLR are equivalent to those of anatomic single and double bone tunnel procedures.

Inverted V-Shaped High Tibial Osteotomy Decreases the Posterior Tibial Slope More but Shortens the Tibia Less Than Closed-Wedge High Tibial Osteotomy.

PURPOSE: To assess the postoperative anatomical changes in the lower extremity after inverted V-shaped high tibial osteotomy (IVHTO) using 3-dimensional (3D) computed tomography (CT) bone models and compare those changes after closed-wedge high tibial osteotomy (CWHTO). METHODS: Preoperative and 3-week postoperative CT scanning of the lower extremity were obtained from patients who underwent IVHTO and CWHTO between October 2019 and March 2021. 3D CT bone models were reconstructed using ZedKnee software. The postoperative changes (Δ) in (1) posterior tibial slope (PTS), (2) knee rotation angle (KRA), (3) tibial torsional angle (TTA), (4) patella tilt (PT), (5) Insall-Salvati ratio (ISR), and (6) tibial length (TL) were compared between IVHTO and CWHTO. RESULTS: Thirty-seven knees (18 IVHTO and 19 CWHTO) in 34 patients were retrospectively enrolled in this study. ΔPTS at the medial and lateral tibial plateau in the IVHTO group (-6.5° and -5.0°) was larger compared with that in the CWHTO group (-3.3° and -2.0°; P = .024 and P = .002, respectively). No significant differences exist between the IVHTO and CWHTO groups in ΔKRA (0.8 ± 4.5° and -1.5 ± 6.5°; P = 0.631), ΔTTA (-3.9 ± 6.2° and -4.1 ± 7.3°; P = .951), ΔPT (-2.0 ± 4.8° and -0.6 ± 4.1°; P = .353), and ΔISR (0.0 and 0.0; P = .829). ΔTL in the IVHTO group (-1.6 ± 2.3 mm) was smaller compared with that in the CWHTO group (-4.1 ± 1.6 mm; P < .001). CONCLUSIONS: (1) The postoperative PTS in the IVHTO group was further decreased compared to the CWHTO group; (2) no significant differences in ΔKRA, ΔTTA, ΔPT, and ΔISR exist between the 2 groups; and (3) the ΔTL in the IVHTO group was significantly smaller compared with the CWHTO group. LEVEL OF EVIDENCE: Level III, retrospective cohort study.