Background: Lateral thrust is known to be risk factors for knee osteoarthritis progression. Medial meniscus extrusion is also known to be risk factors for knee osteoarthritis progression; moreover, the amount of change in medial meniscus extrusion from non-weight bearing to weight bearing is an important factor for the progression of knee osteoarthritis. This study aimed to investigate the correlation between lateral thrust and the change in medial meniscus extrusion. Methods: In total, 44 knees from 44 patients (mean age, 68.9 years) with knee osteoarthritis were divided into two groups according to the KellgreneLawrence grade: early-stage osteoarthritis (Kellgren eLawrence ¼ 2) and severe osteoarthritis (KellgreneLawrence ¼ 3 or 4). The lateral thrust during gait, represented as the lateral acceleration peak immediately after heel strike, was recorded by an inertial sensor. The amount of change in medial meniscus extrusion, which was the difference between weightbearing (unipedal standing) and non-weight-bearing (supine) conditions, was evaluated using ultrasonography. Results: The mean value of the lateral acceleration peak in the severe osteoarthritis group was higher than that of the early-stage osteoarthritis group (p < 0.05). The non-weight-bearing and weight-bearing medial meniscus extrusion in the severe OA group were significantly higher than those of the early-stage osteoarthritis group (p < 0.001). However, the amount of change in medial meniscus extrusion in severe osteoarthritis group was significantly lower than in the early-stage osteoarthritis group (p < 0.05). The amount of change in medial meniscus extrusion showed a significant correlation with the lateral acceleration peak in the early-stage osteoarthritis group (r ¼ 0.56, p < 0.001). On the other hand, there was no significant correlation in the severe osteoarthritis group. Conclusion: The lateral thrust shows a positive correlation with the amount of change in medial meniscus extrusion by weight bearing in patients with early-stage knee osteoarthritis.

PurposeTo report second‐look arthroscopic assessment after all‐arthroscopic autologous chondrocyte implantation (ACI) for articular cartilage defects at the patella. MethodsA second‐look arthroscopy after all‐arthroscopic ACI using chondrospheres® (ACT3D) was performed in 30 patients with 30 full‐thickness retropatellar cartilage defects. The mean time from ACI to second‐look arthroscopy was 14.9 ± 16.3 (6–71) months. The quality of cartilage regeneration was evaluated by the International Cartilage‐Repair Score (ICRS)—Cartilage Repair Assessment (CRA). ResultsEleven lesions (36.7%) were classified as CRA grade I (normal) and 19 lesions (63.3%) as grade II (nearly normal). Concerning the degree of defect repair, 25 lesions (83.3%) were repaired up to the height of the surrounding articular retropatellar cartilage. Five lesions (16.7%) showed 75% repair of defect depth. The border zone was completely integrated into the surrounding articular cartilage shoulder in 28 lesions (93.3%) and demarcated within 1 mm in 2 lesions (6.7%). Macroscopically and by probing, 12 lesions (40%) had intact smooth surface, 17 lesions (56.7%) had fibrillated surface and 1 lesion (3.3%) had small, scattered fissures. A negative correlation was found between the overall repair assessment score and the defect size (r2 = − 0.430, p = 0.046) and between integration into border zone and defect size (r2 = − 0.340, p = 0.045). A positive correlation was found between macroscopic appearance and age (r2 =  + 0.384, p = 0.036). ConclusionsAll‐arthroscopic ACI using chondrospheres® (ACT3D) for full‐thickness retropatellar articular cartilage defects proved to be reproducible and reliable. The advantage of the procedure is that it is minimal invasive. Arthroscopic second‐look demonstrated a high grade of normal or nearly normal cartilage regeneration. Although statistically significant differences were not observed, larger defect size and younger age may compromise the result of overall repair. Level of evidenceIII.

Background Posterior cruciate ligament (PCL) degeneration is often seen in knee osteoarthritis (OA); however, there is no established method for its evaluation. The purpose of this study is to investigate whether the Hounsfield unit (HU) using computed tomography (CT) could be a useful scale to evaluate the degeneration of PCL in knee OA. Methods Knee OA treated with total knee arthroplasty (21 patients, 21 knees) and non-osteoarthritic knees (21 patients, 21 knees) were retrospectively observed and studied. All PCLs in the knees were analyzed using CT. The PCL in the sagittal section was divided into three regions: proximal, middle, and distal sections. The HU value of the PCL at each area was measured. In osteoarthritic knees, tissues from the PCL were collected and histologically graded. The correlation between the radiological classification by Kellgren and Lawrence and the histological grade was analyzed. The average CT HU values for each degenerative grade were also calculated and compared. Results The HU values in OA and non-OA were 70.7 and 88.4 HU (p < 0.05) at the proximal region, 75.7 and 85.3 HU (p < 0.05) in the central region, and 82.3 and 86.5 HU (p > 0.05) in the distal region, respectively. The degeneration of PCL was graded as follows: one, three, and 17 mild, moderate, and severe cases at the proximal portion, and 16, 4, and one mild, moderate, and severe cases at the distal portion, respectively. The radiological classification and the grade of degeneration were not correlated in either the proximal (r = 0.047, p = 0.84) or the distal (r = − 0.21, p = 0.35) portions. The HU value was 84.5, 72.1, and 70.6 HU for mild, moderate, and severe grades, respectively (mild versus moderate: p < 0.05, mild versus severe: p < 0.05, moderate versus severe: p > 0.05). Conclusions In knee OA, a lower HU value in the PCL indicates the progression of degeneration. The CT HU value could be a useful measurement to predict the grade of PCL degeneration.

Background: The degeneration of posterior cruciate ligament (PCL) is often seen in knee osteoarthritis (OA), however there is no established method for its evaluation. The purpose of this study is to investigate whether Hounsfield unit (HU) using CT (computed tomography) could be a useful scale to evaluate the degeneration of PCL in knee OA.Methods: Knee OA treated with total knee arthroplasty (21 patients, 21 knees) and non-osteoarthritic knees (21 patients, 21 knees) were prospectively studied. All PCLs in the knees were analyzed by CT scan. PCL in sagittal section was divided into three regions: proximal, middle and distal portions. The HU value of PCL at each area was measured. In osteoarthritic knees, tissues from PCL were collected and histologically graded.Results: The HU value in OA and non-OA was 70.7 and 88.4 HU (p<0.05) at proximal region, 75.7 HU and 85.3 (p<0.05) at central region and 82.3 and 86.5 HU (p>0.05) at distal region, respectively. The degeneration of PCL was graded as follows; mild: 1 case, moderate: 3 cases and severe: 17 cases at proximal portion and mild: 16 cases, moderate: 4 cases and severe: 1 case at distal portion. The HU value was 84.5 HU for mild, 72.1 HU for moderate and 70.6 HU for severe (mild versus moderate: p<0.05, mild versus severe: p<0.05, moderate versus severe: p>0.05).Conclusions: In knee OA, lower HU value in PCL indicates progression of degeneration. The CT HU value could be a useful measurement to predict the grade of degeneration of PCL.

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Background The degeneration of posterior cruciate ligament (PCL) is often seen in knee osteoarthritis (OA), however there is no established method for its evaluation. The purpose of this study is to investigate whether Hounsfield unit (HU) using CT (computed tomography) could be a useful scale to evaluate the degeneration of PCL in knee OA.Methods Knee OA treated with total knee arthroplasty (21 patients, 21 knees) and non-osteoarthritic knees (21 patients, 21 knees) were prospectively studied. All PCLs in the knees were analyzed by CT scan. PCL in sagittal section was divided into three regions: proximal, middle and distal portions. The HU value of PCL at each area was measured. In osteoarthritic knees, tissues from PCL were collected and histologically graded.Results The HU value in OA and non-OA was 70.7 and 86.5 HU (p < 0.05) at proximal region, 75.7 HU and 86.6 (p < 0.05) at central region and 82.3 and 88.1 HU (p > 0.05) at distal region, respectively. The degeneration of PCL was graded as follows; mild: 1 case, moderate: 3 cases and severe: 17 cases at proximal portion and mild: 16 cases, moderate: 4 cases and severe: 1 case at distal portion. The HU value was 84.5 HU for mild, 72.1 HU for moderate and 70.6 HU for severe (mild versus moderate: p < 0.05, mild versus severe: p < 0.05, moderate versus severe: p > 0.05).Conclusions In knee OA, lower HU value in PCL indicates progression of degeneration. The CT HU value could be a useful measurement to predict the grade of degeneration of PCL.