ABSTRACT
BACKGROUND: Progenitor cells serve as a promising source of regenerative potential in a variety of tissue types yet remain underutilized in tendinopathy. Tendon-derived progenitor cells (TDPCs) have previously been isolated from hamstring tendon but only as part of a concomitant medical procedure. Determining the presence of TDPCs in patellar tendon may facilitate clinical utilization of these cells because of the relative accessibility of this location for tissue harvest. PURPOSE: To characterize TDPCs in human patellar tendon samples. STUDY DESIGN: Descriptive laboratory study. METHODS: Human patellar tendon samples were obtained during elective knee surgery. TDPCs were isolated and seeded at an optimal low cell density and subcultured to confluence for up to 2 passages. Flow cytometry was used to analyze for the expression of CD90+, CD105+, CD44+, and CD31-, CD34-, and CD45- markers. The multilineage differentiation potential of TDPCs was tested in vitro via adipogenic, osteogenic, and chondrogenic culture with subsequent cytochemical staining for Oil Red O, Alizarin Red, and Alcian Blue, respectively. Enzyme-linked immunosorbent assay was used to quantify the amount of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 secreted into cell culture supernatant for further confirmation of lineage differentiation. Results were analyzed statistically using the 2-tailed Student t test. RESULTS: TDPCs demonstrated near-uniform expression of CD90, CD105, and CD44 with minimal expression of CD34, CD31, and CD45. Adipogenic, osteogenic, and chondrogenic differentiation of TDPCs was confirmed using qualitative analysis. The expression of adiponectin, alkaline phosphatase, and SRY-box transcription factor 9 were significantly increased in differentiated cells versus undifferentiated TDPCs (P < .05). CONCLUSION: TDPCs can be successfully isolated from human patellar tendon samples, and they exhibit characteristics of multipotent progenitor cells. CLINICAL RELEVANCE: These data demonstrate the promise of patellar tendon tissue as a source of progenitor cells for use in biologic therapies for the treatment of tendinopathy.
ABSTRACT
Background: This study compares knee kinematics in two groups of patients who have undergone primary total knee arthroplasty (TKA) using two different modern designs: medially congruent (MC) and posterior-stabilized (PS). The aim of the study is to demonstrate only minimal differences between the groups. Methods: Ten TKA patients (4 PS, 6 MC) with successful clinical outcomes were evaluated through 3D knee kinematics analysis performed using a multicamera optoelectronic system and a force platform. Extracted kinematic data included knee flexion angle at heel-strike (KFH), peak midstance knee flexion angle (MSKFA), maximum and minimum knee adduction angle (KAA), and knee rotational angle at heel-strike. Data were compared with a group of healthy controls. Results: There were no differences in preferred walking speed between MC and PS groups, but we found consistent differences in knee function. At heel-strike, the knee tended to be more flexed in the PS group compared to the MC group; the MSKFA tended to be higher in the PS group compared to the MC group. There was a significant fluctuation in KAA during the swing phase in the PS group compared to the MC group, PS patients showed a higher peak knee flexion moment compared to MC patients, and the PS group had significantly less peak internal rotation moments than the MC group. Conclusions: Modern, third-generation TKA designs failed to reproduce normal knee kinematics. MC knees tended to reproduce a more natural kinematic pattern at heel-strike and during axial rotation, while PS knees showed better kinematics during mid-flexion.
ABSTRACT
BACKGROUND: Surgical site infections (SSIs) after anterior cruciate ligament (ACL) reconstruction procedures are an unfortunate complication. Soaking grafts in vancomycin before implantation has been reported to reduce the incidence of postoperative SSI after ACL reconstruction. There is potential for vancomycin to compromise graft integrity because of tenocyte toxicity. PURPOSE: To examine the in vitro toxicity of varying doses of vancomycin on human tenocytes. STUDY DESIGN: Controlled laboratory study. METHODS: Human patellar tenocytes were isolated and expanded in vitro. Tenocytes in culture were exposed to vancomycin at 5 different concentrations (400, 1600, 3200, 6400, and 12,800 µg/mL) and 3 time intervals (2, 6, and 24 hours). The control for all series was tenocyte exposure to only culture medium for each time interval. After treatment, a 10% Cell Counting Kit-8 solution in cellular growth medium was applied to the cells to examine cytotoxicity. A live/dead assay was used to assess tenocyte viability through fluorescence microscopy and flow cytometry. Results were analyzed statistically using multivariable logistic regression models with Tukey honest significant difference post hoc tests. RESULTS: Vancomycin did not cause significant changes in tenocyte viability after 2 and 6 hours of incubation at any concentration between 0 and 12,800 µg/mL. Incubation with vancomycin for 24 hours led to a significant decrease in cell viability at higher concentrations. CONCLUSION: Tenocytes derived from human patellar tendons exposed to relatively high concentrations of vancomycin for short periods of time do not demonstrate significant cell death and toxicity. CLINICAL RELEVANCE: Exposing tendons to vancomycin for a short period of time, such as before ACL reconstruction, is not likely to cause tenocyte toxicity because of vancomycin administration.
