Patellofemoral joint overstuffing in total knee replacement without patella resurfacing / 中华骨科杂志

ABSTRACT

Objective To investigate the patellofemoral joint overstuffing in total knee replacement without patella resurfacing and try to define the incidence and the mechanism.Methods The imaging data of 117 patients (37 males and 80 females;55-73 years old with a mean age of 65.4±5.63) who underwent TKA operation without patella resurfacing for terminal osteoarthritis were analyzed retrospectively between 2005 to 2015.The DR X-ray system was used to get the full extension lateral films preand post-operatively (within one week) and to complete the digital measurement with the built-in PACS system.The involved parameters included patella thickness,anterior femur offset and patella femur distance pre-and post-operatively.The postoperative patellofemoral joint overstuffing was defined as the over 1 mm increase in the postoperative patella femur distance when compared with that preoperatively.The differences between the overstuffing group and non-overstuffing group and the characteristics between male group and female group were compared.Results The postoperative patella femur distance was 33.10± 1.56 mm,which was significantly thicker than that preoperatively (30.69± 1.45 mm).The anterior femur offset (6.93±0.36 mm) at postoperative was significantly larger than that at preoperative (4.50±0.92 mm).Postoperative patellofemoral joint overstuffing occurred in 79 patients with the incidence of 67.5％.There was no difference in the incidence of postoperative patellofemoral joint overstuffing among different manufacturers.In overstuffing group,the preoperative anterior femur offset was 3.89±0.21 mm,which was significantly less than that in none-overstuffing group (5.72±0.24 mm).However,there was no statistical difference between the two groups in preoperative patella thickness,postoperative patella thickness and postoperative anterior femur offset.The incidence of postoperative overstuffing in female group was 78.8％ (63/80),which was significantly higher than that in male group which was 43.2％ (16/37).The preoperative anterior femur offset (4.30±0.81 mm) in female was significantly less than that in man (4.94±1.00mm).The relative risk for postoperative overstuffing in female was 1.82.Conclusion Patellofemoral joint overstuffing occupies 67.5％ total knee replacement without patella resurfacing.Female patients have a higher incidence of patellofemoral joint overstuffing,which may be caused by the thinner anterior femoral offset in anatomy.