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Journal Title
Title of Journal: Knee Surg Sports Traumatol Arthrosc
Abbravation: Knee Surgery, Sports Traumatology, Arthroscopy
Publisher
Springer Berlin Heidelberg
DOI
10.1007/bf00441712
ISSN
1433-7347
Manufacturers of total knee arthroplasty TKA have introduced narrower femurs to improve boneimplant fit However few studies have reported the clinical consequences of mediolateral oversizing Our hypothesis was that component oversizing negatively influences the results after TKAOne hundred and twelve prospectively followed patients with 114 consecutive TKA 64 females and 50 males were retrospectively assessed The mean age of the patients was 72 years range 56 to 85 years The dimensions of the femur and tibia were measured on a preoperative CTscan and were compared with those of the implanted TKA The influence of size variation on the clinical outcomes 1 year after surgery was assessedMediolateral overhang was observed in at least one area in 66 of the femurs 84 in females and 54 in males and 61 of the tibia 81 in females and 40 in males Twentytwo patients presented no overhang in any area and 16 had overhang in all studied zones The increase in the Pain and KOOS scores were 43 ± 21 and 36 ± 18 in the patients without overhang and 31 ± 19 and 25 ± 13 in patients with overhang p = 0033 p = 0032 Knee flexion was 127° ± 7 and 121° ± 11 respectively Regression and latent class analysis showed a significant negative correlation between overall oversizing and overall outcomeThis study confirms that oversizing may lead to worse clinical results in TKA The clinical consequences are that surgeons should pay attention not to oversize implants during implantation nd that oversizing should be ruled out in case of so called unexplained painRecent anatomical studies have shown that the size and shape of the femur and tibia at the knee vary significantly among individuals most notably between males and females 3 6 24 As a consequence certain manufacturers of total knee arthroplasty TKA prostheses have increased their size range and introduced narrower femurs in an attempt to provide a better fit between the bone and implant and to prevent peripheral component overhang 7 8 14 22 23 Oversizing the implant can theoretically compromise the clinical outcome by increasing tension and capsular/ligamentous friction on the implants However its actual clinical consequences have not been sufficiently studied Mahoney et al 36 showed that femoral component overhang increased the risk of residual pain after TKA but the use of narrower femoral implants did not always improve the results 14 19 35 37 51 Whether these narrower implants are warranted remains under debate