Does final component alignment correlate with alignment of the bone resection surfaces in cemented total knee arthroplasty?
OBJECTIVE
To examine, with a navigation, whether the final component alignments correlate with alignment of the bone resection surfaces in cemented total knee arthroplasty (TKA), and to evaluate the factors affecting alignment deviation.


METHODS
A total of 222 patients (276 knees) who underwent navigation-assisted TKA between September 2012 and January 2014 due to osteoarthritis were retrospectively reviewed. The deviation between the alignment of bone resection surfaces and the final alignment of femoral and tibial components was measured. Factors associated with alignment deviation of greater than 2° (outliers) were evaluated. These included age, sex, body mass index, bone mineral density (T score), preoperative and postoperative mechanical femorotibial angle, preoperative and postoperative flexion contractures, and the difference between medial and lateral gaps in knee extension or flexion.


RESULTS
Outliers consisted of 24 cases (8.6%) on the femoral coronal plane, 4 cases (1.4%) on the tibial coronal plane, and 48 cases (17.4%) on the tibial sagittal plane. In the coronal plane (femur and tibia), the outliers were associated with preoperative [p < 0.001; odds ratio (OR) 0.774; 95% confidence interval (CI) 0.672-0.891] and postoperative (p < 0.001; OR 0.240; 95% CI 0.123-0.468) flexion contractures; a difference of 3 mm or more between the medial and lateral gaps in knee extension (p < 0.041; OR 5.805; 95% CI 1.075-31.343); and a T score of less than -2.5(p < 0.024; OR 5.899; 95% CI 1.258-27.664). In the sagittal plane of the tibia, the outliers were associated with preoperative (p < 0.001; OR 0.886; 95% CI 0.829-0.946) and postoperative (p < 0.031; OR 0.803; 95% CI 0.659-0.980) flexion contractures.


CONCLUSIONS
There was a deviation between the alignments of the bone resection surfaces and the final alignments of components. With larger preoperative and postoperative flexion contractures in the coronal and sagittal planes, there were more outlier risks. The outliers in the coronal plane were associated with a difference of 3 mm or more between the medial and lateral gaps in knee extension and poor bone quality. Awareness of such alignment deviation and related factors can help diminish the outliers after TKA.


METHODS
IV.
Department of Orthopedic Surgery, Bumin Hospital, 59, Mandeok-daero, Buk-gu, Busan, 46555, Republic of Korea.
Seung-Suk
SS
Seo
Department of Orthopedic Surgery, Busan Paik Hospital, College of Medicine, Inje University, 75, Bokji-ro, Busanjin-gu, Busan, 47392, Republic of Korea.
Chang-Wan
CW
Kim
Department of Orthopedic Surgery, Busan Paik Hospital, College of Medicine, Inje University, 75, Bokji-ro, Busanjin-gu, Busan, 47392, Republic of Korea. leechangrack@gmail.com.
Chang-Rack
http://orcid.org/0000-0002-1745-0273
CR
Lee
Department of Orthopedic Surgery, Bumin Hospital, 59, Mandeok-daero, Buk-gu, Busan, 46555, Republic of Korea.
Jin-Hyuk
JH
Seo
Department of Orthopedic Surgery, Bumin Hospital, 59, Mandeok-daero, Buk-gu, Busan, 46555, Republic of Korea.
Do-Hun
DH
Kim
Department of Orthopedic Surgery, Bumin Hospital, 59, Mandeok-daero, Buk-gu, Busan, 46555, Republic of Korea.
Ok-Gul
OG
Kim
Department of Orthopedic Surgery, Busan Paik Hospital, College of Medicine, Inje University, 75, Bokji-ro, Busanjin-gu, Busan, 47392, Republic of Korea.
Young-Kyoung
YK
Min
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012399:Rotation; D025321:Surgery, Computer-Assisted
Alignment; Bone resection surface; Component position; Navigation; Total knee arthroplasty