Improved femoral component rotation in advanced genu valgum deformity using computer-assisted measured resection total knee arthroplasty.
BACKGROUND
Accurate femoral rotational alignment is of vital importance for successful total knee arthroplasty (TKA). The value of computer-assisted surgery TKA (CAS-TKA) in increasing the accuracy of femoral rotational alignment remains controversial. We hypothesize that outcomes are related to the severity of preoperative varus and valgus deformity and that CAS-TKA may be beneficial under certain circumstances.


METHODS
Between January 2007 and December 2013, patients with osteoarthritis and varus angulation in the mechanical axis (MA) ≥ 15° and valgus angulation in the MA ≥ 10° (based on hip-to-ankle standing radiography) who underwent TKA were divided into four groups. CAS-TKA and conventional TKA outcomes were compared in patients who had preoperative advanced genu varum and advanced genu valgum deformities. The accuracy of component alignment and postoperative limb alignment was determined using radiographic parameters and computed tomography (CT).


RESULTS
One hundred and eight patients (144 knees) were included in the analysis. For patients with preoperative advanced genu varum deformity, a significant difference was detected in the sagittal femoral angle (p < 0.001), but no significant improvement of femoral rotational alignment was noted (p = 0.127). In patients with preoperative advanced genu valgum deformity, a significant difference was found in the sagittal femoral angle (p = 0.034). The femoral rotational angle was significantly closer to the proper position in the CAS-TKA group (p < 0.001). When comparing the percentage of knees achieving the proper alignment, there was a decrease in the amount of outlier for the femoral rotational angle for CAS-TKA in advanced genu valgum deformity (p = 0.011).


CONCLUSIONS
Our data demonstrate that CAS-TKA is beneficial in obtaining proper femoral rotational alignment in patients with advanced genu valgum deformity (preoperative MA ≥ 10° valgus). In patients with advanced genu varum deformity (preoperative MA ≥ 15° varus), CAS-TKA did not improve the femoral rotational alignment.
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. b9002092@adm.cgmh.org.tw.
Shih-Jie
SJ
Lin
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. chienyin@gmail.com.
Chien-Ying
CY
Lee
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. kc2672@adm.cgmh.org.tw.|Chang Gung University, Taoyuan, Taiwan, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan, 333, Taiwan. kc2672@adm.cgmh.org.tw.
Kuo-Chin
KC
Huang
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. mr3497@adm.cgmh.org.tw.|Chang Gung University, Taoyuan, Taiwan, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan, 333, Taiwan. mr3497@adm.cgmh.org.tw.
Kuo-Ti
KT
Peng
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. b8601081@adm.cgmh.org.tw.|Chang Gung University, Taoyuan, Taiwan, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan, 333, Taiwan. b8601081@adm.cgmh.org.tw.
Tsan-Wen
TW
Huang
Department of Orthopaedic Surgery, Kaohsiung Chang Gung Memorial Hospital, No. 123, DAPI Rd. Niaosng Dist., Kaohsiung City, 83301, Taiwan. mellee@cgmh.org.tw.|Chang Gung University, Taoyuan, Taiwan, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan, 333, Taiwan. mellee@cgmh.org.tw.
Mel S
MS
Lee
Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chiayi, 6, West Section, Chia-Pu Road, Pu-Tz City, 613, Chia-Yi Hsien, Taiwan. wwh@cgmh.org.tw.|Chang Gung University, Taoyuan, Taiwan, 259 Wen-Hwa 1st Road, Kwei-Shan Tao-Yuan, 333, Taiwan. wwh@cgmh.org.tw.
Robert Wen-Wei
RW
Hsu
Po-Cheng Orthopedic Institute, 100 Bo-ai, 2nd Road, Zuoying District, Kaohsiung, Taiwan. w2212@ms14.hinet.net.
Wun-Jer
WJ
Shen
D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods* / Q000592:standards; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D056304:Genu Valgum / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D016037:Single-Blind Method; D025321:Surgery, Computer-Assisted / Q000379:methods* / Q000592:standards