Predicting anterior cruciate ligament degeneration using magnetic resonance imaging: Insights from histological evaluation.

BACKGROUND: Mucoid degeneration of the anterior cruciate ligament is a pathological condition that may impair knee mechanics and contribute to the symptomatology of osteoarthritis. This study aimed to evaluate whether preoperative magnetic resonance imaging can predict anterior cruciate ligament degeneration, specifically mucoid degeneration, and to elucidate the histopathological characteristics of mucoid degeneration in knee osteoarthritis patients. METHODS: We evaluated a total of 95 knees of osteoarthritis patients (23 males, 72 females; mean age: 72.7 ± 7.5) scheduled for total knee arthroplasty. The relationship between preoperative magnetic resonance imaging findings and the histopathological evidence of anterior cruciate ligament mucoid degeneration was examined. Immunohistochemical analysis was employed for collagen types (COL-I, COL-II), chondrogenesis (SOX9), and vascularity (CD31). RESULTS: High signal intensity on magnetic resonance imaging showed a positive correlation with Alcian Blue staining areas (rs = 0.59, p < 0.01) and the swelling index (rs = 0.62, p < 0.01), indicating advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament was associated with more severe degeneration. In the histological evaluations, advanced degeneration was characterized by an increase in chondroid metaplasia and collagen disorientation. The Alcian Blue and SOX9 correlation was positive (rs = 0.69, p < 0.01), but negative with COL-I (rs = -0.38, p = 0.03) and vascularity (CD31) (rs = -0.60, p < 0.01). CONCLUSIONS: Preoperative magnetic resonance imaging is an effective tool in assessing the severity of anterior cruciate ligament degeneration; it influences surgical decisions. High signal intensity on magnetic resonance images denotes advanced mucoid degeneration. The absence of synovial lining around the anterior cruciate ligament is associated with more severe degeneration and may accelerate degenerative changes. Chondroid metaplasia and collagen disorientation mark advanced degeneration. Magnetic resonance imaging can be used to gauge the degree of anterior cruciate ligament degeneration in osteoarthritis.

Lower limb alignment in healthy Japanese adults.

BACKGROUND: Knowledge regarding the normal alignment of the lower limb is important when considering alignment for total knee arthroplasty. However, few studies have explored the lower limb alignment of healthy Japanese subjects. METHODS: Between July and October 2020, we performed whole leg standing radiography of 120 legs of 60 healthy adult Japanese volunteers aged <50 years in the closed-leg stance. The measurement parameters were hip knee ankle angle (positive for varus), percentage of constitutional varus (hip knee ankle angle ≥ 3°), mechanical axis deviation ratio, mechanical lateral distal femoral angle, medial proximal tibial angle, joint line convergence angle (positive for lateral opening), and tibial joint line angle (positive for medial inclination). RESULTS: The mean measured values for all volunteers, men and women, were as follows: hip knee ankle angle (°), 2.3, 2.6, and 2.0; mechanical axis deviation ratio, 35.8, 35.6, and 36.9; mechanical lateral distal femoral angle (°), 86.7, 87.0, and 86.7; medial proximal tibial angle (°), 85.6, 85.0, and 86.2; joint line convergence angle (°), 0.6, 0.3, and 0.8; and tibial joint line angle (°), -1.0, -0.7, -1.4, respectively. The percentage of constitutional varus was 35.8% overall, 35.8% in men and 35.3% in women. Only the medial proximal tibial angle was smaller in men than that in women (p = 0.003). CONCLUSIONS: The mechanical lateral distal femoral and medial proximal tibial angles were smaller, hip knee ankle angle was larger, and percentage of constitutional varus was higher in Japanese subjects than those reported for subjects in other countries. Our findings improve the understanding of Japanese-specific alignments when considering alignment for lower limb surgery, especially, total knee arthroplasty.

Biodegradable gelatin hydrogels incorporating fibroblast growth factor 2 promote healing of horizontal tears in rabbit meniscus.

PURPOSE: The purpose of this study was to investigate the in vivo effects of gelatin hydrogels (GHs) incorporating fibroblast growth factor 2 (FGF-2) on meniscus repair in a rabbit model. METHODS: FGF-2 was biologically stabilized by incorporation into GHs. This system enables FGF-2 to be released with its biologic activity intact. A total of 64 skeletally mature female Japanese white rabbits were used. A horizontal tear was made in the medial meniscus, and these tears were divided into 4 groups: GH-FGF, GH-no FGF, FGF (FGF-2 alone), and no treatment. The meniscus was evaluated histologically at 2, 4, 8, and 12 weeks after surgery. Cell density and the percentages of proliferating cell nuclear antigen-positive cells and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were measured, and a scoring system ranging from 5 points (complete healing) to 0 points (no evidence of healing) was used. RESULTS: Cell density was significantly higher in the GH-FGF group than in the other 3 groups at 2, 4, 8, and 12 weeks (P < .01). The percentage of proliferating cell nuclear antigen-positive cells was significantly higher whereas the percentage of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells was significantly lower in the GH-FGF group at 2 and 4 weeks after surgery (P < .05). At 4, 8, and 12 weeks after surgery, healing scores were significantly higher in the GH-FGF group (2.5 points, 2.7 points, and 3.0 points, respectively) than in the GH-no FGF group (1.3 points, 1.4 points, and 2.0 points, respectively) (P < .05). CONCLUSIONS: GHs incorporating FGF-2 significantly stimulated proliferation and inhibited the death of meniscal cells until 4 weeks, thereby increasing meniscal cell density and enhancing meniscal repair in a rabbit model. CLINICAL RELEVANCE: GHs incorporating FGF-2 are able to enhance the healing of meniscal injury.

CASE REPORTS: intraarticular fibroma of the tendon sheath in the knee.

We report a rare case of fibroma of the tendon sheath in the knee. To our knowledge, only three previous cases of fibroma of the tendon sheath in the knee have been reported in the English literature. In our case, T1-weighted magnetic resonance imaging revealed a low intensity signal, T2-weighted magnetic resonance imaging showed a mixed area of high and low signal intensity, and gadolinium-diethylene triaminepentaacetic acid-enhanced magnetic resonance imaging showed faint enhancement at the periphery of the lesion. Magnetic resonance imaging therefore was valid for detection of this intraarticular lesion. The lesion, which was located between the posterior capsule of the left knee and the posterior cruciate ligament, was excised arthroscopically.