Patellar Height Effect On Knee Function Of Pre Versus Post-total Knee Arthroplasty (TKA)

ObjectiveThe goal of this study was to compare the knee function by Insall-Salvati andimproved Insall-Salvati indices before and after total knee arthroplasty (TKA).MethodsThe X-ray data about Insall-Salvati and improved Insall-Salvati indices of pre andpost-total knee arthroplasty (TKA) were collected from81consecutive patients (106cases). Simultaneously, the knee function of all cases were evaluated through TheHospital for Special Surgery (HSS) score system, that included activity, myodynamia,flexion deformity, stability, etc.ResultsThe postoperative HSS score was89±10(mean). The preoperative Insall-Salvati ratioand modified Insall-Salvati ratio were1.00±0.13and1.61±0.21(mean) respectively,while the postoperative Insall-Salvati ratio and modified Insall-Salvati ratio were0.94±0.19and1.67±0.34(mean) respectively. The postoperative Insall-Salvati ratiosignificantly increased than the preoperative Insall-Salvati ratio (P<0.05), while thepostoperative modified Insall-Salvati ratio significantly decreased than the preoperative modified Insall-Salvati ratio (P<0.05). The postoperative HSS score (range of motion,flexion contracture) in postoperative patella baja group (Insall-salvati ratio<0.8)significantly decreased than that in normal patella group (0.8<Insall-Salvati ratio<1.5)(P<0.05). But, there were no significantly difference between patella alta group(Insall-salvati ratio>1.5) and normal patella group (P>0.05). The postoperative HSSscore (range of motion, stability, functional, quadriceps strength, flexion contracture) ofpatients whose preoperative modified Insall-salvati ratio>1.8significantly increased thanthat <1.8(P<0.05).ConclusionPreoperative modified and postoperative Insall-salvati ratio could be as a potentialcandidate in evaluation of postoperative knee joint function. Both pre and postoperativepatellar position can affect knee joint function followed accurate resection was a keypoint in TKA.