Mismatch between femur and tibia coronal alignment in the knee joint: classification of five lower limb types according to femoral and tibial mechanical alignment

Table 3 Classification of lower limb coronal alignment into five types based on mLDFA and mMPTA

Group	Knee types ^#
Group	Neutral		Varus		Valgus
Variable	Type 1	Type 2	Type 3	Type 4	Type 5	P†
Variable	Neutral	Oblique joint line	Varus of the tibia	Varus of both the tibia and femur	Valgus of the femur	P†
Number (N(total%))	79(36.9)	52(24.2)	43(20.0)	21(9.8)	19(8.9)
Sex						0.155
Female (N(type%))	42(53.1)	27(51.9)	15(34.9)	7(33.3)	11(61.1)
Age (Y)	38.2 ± 17.0	37.0 ± 18.0	47.0 ± 19.7	50.6 ± 18.9^b	43.0 ± 18.2	0.005
Age group						0.001
20–50 year	56	36	17	7	11
51–70 year	23	16	26	14	8
HKAA(°)^*	0.6 ± 1.6	−0.4 ± 1.4	4.2 ± 1.1^ab	5.6 ± 2.3^abc	−4.2 ± 0.9^abcd	< 0.001
mLDFA(°)^*	88.0 ± 1.3	85.0 ± 1.4^a	88.0 ± 1.4^b	91.4 ± 1.4^abc	84.6 ± 1.6^acd	< 0.001
mMPTA(°)^*	87.0 ± 1.5	85.1 ± 1.2^a	83.5 ± 1.6^ab	85.2 ± 2.0^ac	88.8 ± 2.0^abcd	< 0.001
AA-MA(°)^*	4.4 ± 1.1	4.2 ± 1.2	5.4 ± 1.6^ab	6.0 ± 2.1^ab	4.0 ± 1.7^cd	< 0.001
KAA(°)^*	− 4.2 ± 1.5	−5.2 ± 1.5^a	− 2.2 ± 1.7^ab	−1.8 ± 1.7^ab	−7.8 ± 2.4^abcd	< 0.001
TJLA(°) ^*	0.0 ± 1.6	2.7 ± 2.4^a	0.9 ± 2.1^ab	−0.9 ± 2.2^bc	2.0 ± 3.3^ad	< 0.001
JLCA(°) ^*	−0.4 ± 0.7	−0.2 ± 0.7	− 0.2 ± 1.1	−0.2 ± 1.2	− 0.5 ± 0.5	0.510

^*HKAA hip–knee–ankle angle, mLDFA mechanical lateral distal femoral angle, mMPTA mechanical medial proximal tibial angle, AA-MA angle between femoral anatomical axis and mechanical axis, KAA knee alignment angle, TJLA tibial joint line angle, JLCA joint line convergence angle
^# Type 1: valgus of the distal femur and varus of the proximal tibia within 3°; type 2: valgus of the distal femur and varus of the proximal tibia above 3° (neutral with knee joint line obliquity); type 3: genu varus with varus of the tibia; type 4: genu varus with both varus of the tibia and femur; type 5: genu valgus
^aP < 0.05 vs. type 1;^bP < 0.05 vs. type 2;^cP < 0.05 vs. type 3;^dP < 0.05 vs. type 4
^†denotes one-way analysis of variance (ANOVA) for continuous variables with Bonferroni post-hoc test or chi-square test for categorical variables

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