Measurement of change on medial and lateral joint gaps by navigation system in multi-radius PS TKA.
BACKGROUND
The purpose of this study was to evaluate the joint gap kinematics in posterior-stabilized total knee arthroplasty (PS TKA).


METHODS
Between January 2010 and April 2011, 44 consecutive patients (55 knees) who underwent primary PS TKA using the navigation system were assessed. There were 37 women and 7 men with a mean age at operation of 63 years (range; 58-73 years). After fixation of all components with cement and insertion of polyethylene trial insert, medial and lateral joint gap measurements were carried out without distraction force and separately using a navigation system on each flexion angles. The joint gaps were measured before and after deflation of tourniquet, first with patella everted and then reduced.


RESULTS
Deflation of tourniquet did not effect on gap. In patellofemoral joint reduction situation, the medial gap relatively maintained throughout the range of knee motion, but the lateral gap is gradually decreasing with knee flexion from 30° to 120° flexion. However, in patellar eversion situation, the medial gap showed a significant increase and also statistically significantly increased compared with patellar reduced position over 90° knee flexion status, but the lateral gaps are decreased compared with patellofemoral reduction situation throughout the range of knee motion except full flexion status. In more physiologic status that is patella reduced and tourniquet deflated status, the average medial joint gap change was 2.30 ± 1.64 mm and the average lateral joint gap change was 2.90 ± 1.53 mm throughout the range of motion.


CONCLUSIONS
Medial and lateral joint gaps showed different patterns with patellar eversion and patellofemoral joint reduction. However, such changes occurred within 3 mm in average throughout whole range of knee motion even with multi-radius femoral component.
Department of Orthopedic Surgery, Hanyang University Hospital, Seoul, Republic of Korea.
Yeesuk
Y
Kim
Department of Orthopedic Surgery, Hanyang University Hospital, Seoul, Republic of Korea.
Jin Kyu
JK
Lee
Department of Orthopedic Surgery, Hanyang University Hospital, Seoul, Republic of Korea.
Kyu-Sung
KS
Chung
Department of Orthopedic Surgery, Hanyang University Hospital, Seoul, Republic of Korea.
Doo-Yeon
DY
Lee
Department of Orthopedic Surgery, Hanyang University Hospital, Seoul, Republic of Korea. Electronic address: chhchoi@hanyang.ac.kr.
Choong Hyeok
CH
Choi
D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D057071:Patellofemoral Joint / Q000503:physiopathology; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology; D025321:Surgery, Computer-Assisted