What are the causes of revision total knee arthroplasty in Japan?

BACKGROUND: There is limited information regarding the cause of revision TKA in Asia, especially Japan. Owing to differences in patient backgrounds and lifestyles, the modes of TKA failures in Asia may differ from those in Western countries. QUESTIONS/PURPOSES: We therefore determined (1) causes of revision TKA in a cohort of Japanese patients with revision TKA and (2) whether patient demographic features and underlying diagnosis of primary TKA are associated with the causes of revision TKA. METHODS: We assessed all revision TKA procedures performed at five major centers in Hokkaido from 2006 to 2011 for the causes of failures. Demographic data and underlying diagnosis for index primary TKA of the revision cases were compared to those of randomly selected primary TKAs during the same period. RESULTS: One hundred forty revision TKAs and 4047 primary TKAs were performed at the five centers, indicating a revision burden of 3.3%. The most common cause of revision TKA was mechanical loosening (40%) followed by infection (24%), wear/osteolysis (9%), instability (9%), implant failure (6%), periprosthetic fracture (4%), and other reasons (8%). The mean age of patients with periprosthetic fracture was older (77 versus 72 years) and the male proportion in patients with infection was higher (33% versus 19%) than those of patients in the primary TKA group. There was no difference in BMI between primary TKAs and any type of revision TKA except other causes. CONCLUSIONS: The revision burden at the five referral centers in Hokkaido was 3.3%, and the most common cause of revision TKA was mechanical loosening followed by infection. Demographic data such as age and sex might be associated with particular causes of revision TKA.

Posterior femoral condylar offset after total knee replacement in the risk of knee flexion contracture.

The aim of this study was to clarify the risk of knee flexion contracture associated with a posterior femoral condylar offset after total knee replacement (TKR). Radiographs from 100 healthy Japanese volunteers were included in the study. We evaluated femoral component posterior offset in various implants and compared them with the normal Japanese knee. Posterior offset of the femoral condyle is up to a maximum of 4.7 times greater than that of the healthy Japanese knee in all knee implants. Excess posterior offset of the femoral condyle in TKR prostheses may cause knee joint flexion contracture due to the relative shortening of the posterior soft tissue.

Patella Eversion Reduces Early Knee Range of Motion and Muscle Torque Recovery after Total Knee Arthroplasty: Comparison between Minimally Invasive Total Knee Arthroplasty and Conventional Total Knee Arthroplasty.

We hypothesized that patella eversion during total knee arthroplasty (TKA) reduces early return of active knee extension and flexion, quadriceps muscle strength, and postoperative pain. In 100 conventional TKA knees and 100 minimally invasive TKA (MIS TKA) knees, we compared knee range of motion (ROM), postoperative pain, and quadriceps muscle strength at 1 day, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 12 weeks, 1 year, and 5 years after surgery. The differences of surgical approach between MIS TKA and conventional TKA of this study are length of skin incision with subcutaneal flap and patella eversion. In MIS TKA, skin incision is shorter than conventional TKA. Furthermore, patella is not everted in MIS TKA procedure. There were no significant differences in preoperative factors. Postoperative improvement of ROM, postoperative muscle strength recovery, and postoperative improvement of visual analog scale were faster in patients with MIS TKA when compared to that in patients with conventional TKA. On the other hand, no significant difference was observed in complication, 5-year clinical results of subjective knee function score, and the postoperative component angle and lower leg alignment. These results indicate that patella eversion may affect muscle strength recovery and postoperative pain.