Yun-Jin Choi

Magnetic Resonance Imaging Evidence of Meniscal Extrusion in Medial Meniscus Posterior Root Tear

PURPOSE The purpose of this study was to evaluate the relation between meniscal extrusion on magnetic resonance imaging (MRI) and tearing of the posterior root of the medial meniscus, as well as to understand the relation between meniscal extrusion and chondral lesions. METHODS From January 2007 to December 2008, 387 consecutive cases of medial meniscal tears were treated arthroscopically. Of these cases, 248 (64.1%) with MRI were reviewed. Arthroscopic findings were reviewed for the type of tear and medial compartment cartilage lesion. Root tear was defined as a radial tear in the posterior horn of the medial meniscus near the tibial spine (i.e., within 5 mm of the root attachment). An MRI scan of the knee was used to evaluate the presence and extent of meniscal extrusion. Meniscal extrusion of 3 mm or greater was considered pathologic. Arthroscopic findings were compared with respect to the extent of meniscal extrusion. RESULTS There were 98 male patients and 150 female patients. The mean age was 53.5 years (range, 15 to 81 years). The results showed 127 cases (51.2%) in which the medial meniscus had meniscal extrusion of 3 mm or greater. Posterior root tears were found in 66 (26.6%) of the 248 knees. The mean meniscal extrusion in patients with root tear was 3.8 ± 1.4 mm, whereas the mean extrusion of those who had no root tear was 2.7 ± 1.3 mm. We found an association between pathologic meniscal extrusion and root tear (P < .001). Meniscal extrusion showed a low positive predictive value (39%) and specificity (58%) with regard to the meniscal root tear. Meniscal extrusion was also significantly correlated with severity of chondral lesions (P < .001). CONCLUSIONS Considerable extrusion (≥3 mm) can be associated with tearing of the medial meniscus root and chondral lesion of the medial femoral condyle. LEVEL OF EVIDENCE Level IV, therapeutic case series.

Comparative Outcomes of Open-Wedge High Tibial Osteotomy With Platelet-Rich Plasma Alone or in Combination With Mesenchymal Stem Cell Treatment: A Prospective Study

PURPOSE This study compared the clinical results and second-look arthroscopic findings of patients undergoing open-wedge high tibial osteotomy (HTO) for varus deformity, with or without mesenchymal stem cell (MSC) therapy. METHODS This prospective, comparative observational study was designed to evaluate the effectiveness of MSC therapy. The patients were divided into 2 groups: HTO with platelet-rich plasma (PRP) injection only (n = 23) or HTO in conjunction with MSC therapy and PRP injection (n = 21). Prospective evaluations of both groups were performed using the Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), and a visual analog scale (VAS) score for pain. Second-look arthroscopy was carried out in all patients at the time of metal removal. RESULTS The patients in the MSC-PRP group showed significantly greater improvements in the KOOS subscales for pain (PRP only, 74.0 ± 5.7; MSC-PRP, 81.2 ± 6.9; P < .001) and symptoms (PRP only, 75.4 ± 8.5; MSC-PRP, 82.8 ± 7.2; P = .006) relative to the PRP-only group. Although the mean Lysholm score was similarly improved in both groups (PRP only, 80.6 ± 13.5; MSC-PRP, 84.7 ± 16.2; P = .357), the MSC-PRP group showed a significantly greater improvement in the VAS pain score (PRP only, 16.2 ± 4.6; MSC-PRP, 10.2 ± 5.7; P < .001). There were no differences in the preoperative (PRP only, varus 2.8° ± 1.7°; MSC-PRP, varus 3.4° ± 3.0°; P = .719) and postoperative (PRP only, valgus 9.8° ± 2.4°; MSC-PRP, valgus 8.7° ± 2.3°; P = .678) femorotibial angles or weight-bearing lines between the groups. Arthroscopic evaluation, at plate removal, showed that partial or even fibrocartilage coverage was achieved in 50% of the MSC-PRP group patients but in only 10% of the patients in the PRP-only group (P < .001). CONCLUSIONS MSC therapy, in conjunction with HTO, mildly improved cartilage healing and showed good clinical results in some KOOS subscores and the VAS pain score compared with PRP only. LEVEL OF EVIDENCE Level II, prospective comparative study.

Biomechanical comparison of fixed- and mobile-bearing for unicomparmental knee arthroplasty using finite element analysis.

Unicomparmental knee arthroplasty (UKA) is a popular alternative to total knee arthroplasty (TKA) and high tibial osteotomy for unicompartmental knee conditions, especially in young patients. However, failure of UKA occurs due to either progressive osteoarthritis (OA) in the other compartment or wear on the polyethylene (PE) insert. This study used finite element (FE) analysis to investigate the effects of PE insert contact pressure and stress in opposite compartments for fixed‐ and mobile‐bearing UKA. Analysis was performed using high kinematics displacement and rotation inputs, which were based on the kinematics of the natural knee. ISO standards were used for axial load and flexion. The mobile‐bearing PE insert had lower contact pressure than the fixed‐bearing PE insert. With the mobile‐bearing UKA, lower stress on the opposite compartment reduces the overall risk of progressive OA in the knee. The fixed‐bearing UKA increases the overall risk of progressive OA in the knee due to higher stress on the opposite compartment. However, the PE insert of mobile‐bearing showed pronounced backside stress at the inferior surface.

Medial Meniscal Tears in Anterior Cruciate Ligament-Deficient Knees: Effects of Posterior Tibial Slope on Medial Meniscal Tear

Purpose To evaluate the incidence of meniscal tears in patients with chronic anterior cruciate ligament (ACL)-deficient knees, and to determine the influence of posterior tibial slope (PTS) on medial meniscal tears in ACL-deficient knees. Materials and Methods We reviewed 174 patients (174 knees) with a mean age of 30.7 years who underwent ACL reconstruction for chronic ACL tears. We divided the patients into two groups: low group (135 knees with a PTS<13°) and high group (39 knees with a PTS≥13°). Results The incidence of medial meniscus tears was 44% (77/174), and that of lateral meniscus tears was 35% (61/174). The mean PTS in patients with medial meniscal tears was 11.4°±3.0°, whereas that in patients without medial meniscal tears was 9.8°±2.4°. The incidence of meniscal tears was 57.8% (78/135) in the low group and 89.7% (35/39) in the high group (p<0.001). Conclusions Our data demonstrate that PTS≥13° is a risk factor for secondary medial meniscal tears in ACL-deficient knees. So, we suggest that PTS is one of the considerations for determining early ACL reconstruction to prevent secondary meniscal tears.

Co-culture with human synovium-derived mesenchymal stem cells inhibits inflammatory activity and increases cell proliferation of sodium nitroprusside-stimulated chondrocytes

Rheumatoid arthritis (RA) and osteoarthritis (OA) are primarily chronic inflammatory diseases. Mesenchymal stem cells (MSCs) have the ability to differentiate into cells of the mesodermal lineage, and to regulate immunomodulatory activity. Specifically, MSCs have been shown to secrete insulin-like growth factor 1 (IGF-1). The purpose of the present study was to examine the inhibitory effects on inflammatory activity from a co-culture of human synovium-derived mesenchymal stem cells (hSDMSCs) and sodium nitroprusside (SNP)-stimulated chondrocytes. First, chondrocytes were treated with SNP to generate an in vitro model of RA or OA. Next, the co-culture of hSDMSCs with SNP-stimulated chondrocytes reduced inflammatory cytokine secretion, inhibited expression of inflammation activity-related genes, generated IGF-1 secretion, and increased the chondrocyte proliferation rate. To evaluate the effect of IGF-1 on inhibition of inflammation, chondrocytes pre-treated with IGF-1 were treated with SNP, and then the production of inflammatory cytokines was analyzed. Treatment with IGF-1 was shown to significantly reduce inflammatory cytokine secretion in SNP-stimulated chondrocytes. Our results suggest that hSDMSCs offer a new strategy to promote cell-based cartilage regeneration in RA or OA.

The Effect of Femoral Cutting Guide Design Improvements for Patient-Specific Instruments

Although the application of patient-specific instruments (PSI) for total knee arthroplasty (TKA) increases the cost of the surgical procedure, PSI may reduce operative time and improve implant alignment, which could reduce the number of revision surgeries. We report our experience with TKA using PSI techniques in 120 patients from March to December 2014. PSI for TKA were created from data provided by computed tomography (CT) scans or magnetic resonance imaging (MRI); which imaging technology is more reliable for the PSI technique remains unclear. In the first 20 patients, the accuracy of bone resection and PSI stability were compared between CT and MRI scans with presurgical results as a reference; MRI produced better results. In the second and third groups, each with 50 patients, the results of bone resection and stability were compared in MRI scans with respect to the quality of scanning due to motion artifacts and experienced know-how in PSI design, respectively. The optimized femoral cutting guide design for PSI showed the closest outcomes in bone resection and PSI stability with presurgical data. It is expected that this design could be a reasonable guideline in PSI.