Jin Wha Chung

Effect of pore sizes of PLGA scaffolds on mechanical properties and cell behaviour for nucleus pulposus regeneration in vivo

This study investigated the influence of pore sizes of poly(lactic‐co‐glycolic acid) (PLGA) scaffolds on the compressive strength of tissue‐engineered biodiscs and selection of the best suitable pore size for cells to grow in vivo. PLGA scaffolds were fabricated by solvent casting/salt‐leaching with pore sizes of 90–180, 180–250, 250–355 and 355–425 µm. Nucleus pulposus (NP) cells were seeded on PLGA scaffolds with various pore sizes. Each sample was harvested at each time point, after retrieval of PLGA scaffolds seeded with NP cells, which were implanted into subcutaneous spaces in nude mice at 4 and 6 weeks. MTT assay, glycosaminoglycan (GAG) assay, haematoxylin and eosin (H&E) staining, safranin O staining and immunohistochemistry (for collagen type II) were performed at each time point. As the pores became smaller, the value of the compressive strength of the scaffold was increased. The group of scaffolds with pore sizes of 90–250 µm showed better cell proliferation and ECM production. These results demonstrated that the compressive strength of the scaffold was improved while the scaffold had pore sizes in the range 90–250 µm and good cell interconnectivity. Suitable space in the scaffold for cell viability is a key factor for cell metabolism. Copyright

Average 10.1-year follow-up of cementless total knee arthroplasty in patients with rheumatoid arthritis

BACKGROUND Total knee arthroplasty (TKA) using a cemented technique has been recommended in patients with rheumatoid arthritis owing to the initial stability of the fixation and long-term durability of the components; however, similar long-term follow-up results have been reported in patients who have undergone cementless TKA. The purpose of this study was to evaluate the radiologic and clinical outcomes of cementless TKA in patients with rheumatoid arthritis. METHODS We enrolled patients undergoing cementless TKA from March 1990 to February 2000. Clinical and radiologic evaluations were performed using the Knee Society clinical rating system and radiographic evaluation and scoring system. RESULTS We included the cases of 112 patients who underwent 179 cementless TKA procedures in our analysis. Their mean age was 62.3 years, and the mean follow-up period was 10.1 years. The final survival rate was 0.968 at the 15.5-year follow-up. Regarding radiologic results after surgery, the mean total valgus angle was 6.7°, the mean femoral flexion angle was 97.5° and the mean tibial angle was 89.2° on the anteroposterior radiographs. On the lateral films, the mean femoral flexion angle was 1.6° and the mean tibial angle was 89.2°. At the last follow-up, the mean total valgus angle was 6.5°, the mean femoral flexion angle was 97.4° and the mean tibial angle was 89.1°, as seen on the anteroposterior view. On the lateral views, the mean femoral flexion angle was 1.4° and the mean tibial angle was 89.0°. Regarding the clinical outcome, the mean knee score and function score on the Knee Society clinical rating system were also enhanced from 47.5 and 43.6, respectively, before the operation to 91.2 and 82.3, respectively, at the last follow-up. CONCLUSION On radiologic and clinical follow-up of cementless TKA for patients with rheumatoid arthritis, there were no serious complications, and the results of the operation were satisfactory with improvement in range of motion and clinical symptoms.

Long-term clinical and radiological outcomes of hybrid total knee arthroplasty

OBJECTIVES The purpose of this study was to evaluate the clinical effectiveness and radiological results of hybrid total knee arthroplasty (TKA). METHODS This study recruited 105 patients (169 cases) who underwent hybrid TKA for osteoarthritis and rheumatoid arthritis from 1999 to 2002. Maxim (Biomet Inc., Warsaw, IN, USA) prosthesis was used, and average follow-up was 8.6 years. Radiologically, femorotibial angle was measured in a standing anteroposterior (AP) view, and a femoral flexion angle and a tibial angle were measured using the Knee Society roentgenographic evaluation and scoring system. Radiolucent lines were detected at the last follow-up. Clinically, range of joint motion and the Knee Society clinical rating system scores were evaluated. RESULTS The femorotibial angle was improved from varus 4.5° to 6.4° at the last follow-up. The femoral flexion in an AP view at the postoperative and last follow-up was 96.5° and 95.7°, respectively, and the tibial angle was 89.1° and 88.7°, respectively. In lateral view, the femoral flexion was 2.6° and 2.7°, respectively, and the tibial angle was 88.4° and 87.8°, respectively. Total scores of radiolucencies were 4 points or less in all cases, and the average width was 1.1 mm. Flexion contracture was improved from 10.0° to 3.5°, and further flexion was increased from 110.5° to 130.4°. Knee score and function score were also enhanced from 47.6 and 46.8 preoperatively to 89.7 and 88.4 after the operation, respectively. CONCLUSION Hybrid technique for TKA can be effective clinically and radiologically on longterm follow-up.