Predictive factors for coronal and sagittal graft extrusion length after using tendon autograft for medial meniscus reconstruction

Table 1 Demographics

Variable	Description
Age (year)	36.10 ± 4.98
Gender, male/female	6/4
Body mass index	28.30 ± 4.80
Preoperative medial posterior tibial slope (°)	14.42 ± 2.39
Preoperative Kellgren-Lawrence grade, grade 0/grade 1/grade 2/grade 3	2/3/2/3
Preoperative hip-knee-ankle angle (°)	175.40 ± 3.86
Preoperative bilateral hip-knee-ankle angle difference (°)	2.13 ± 3.00
Preoperative absolute joint space width (mm)	3.09 ± 0.77
Preoperative relative joint space width	0.68 ± 0.12
Preoperative medial edge incline angle (°)	6.68 ± 9.68
Preoperative bilateral medial edge incline angle difference (°)	4.88 ± 7.87
Anterior tunnel edge distance (mm)	5.93 ± 3.42
Posterior tunnel edge distance (mm)	11.23 ± 6.15
1 wk after operation
Medial extrusion (mm)	1.00 ± 1.90
Anterior extrusion (mm)	-3.46 ± 2.29
Posterior extrusion (mm)	0.13 ± 2.90
Mean extrusion (mm)	-0.76 ± 2.05
Relative posterior graft position ratio	-0.08 ± 1.09
8 mo after operation
Medial extrusion (mm)	1.73 ± 2.38
Anterior extrusion (mm)	-2.90 ± 2.39
Posterior extrusion (mm)	1.38 ± 4.43
Mean extrusion (mm)	0.07 ± 2.72
Relative posterior graft position ratio	0.49 ± 0.76

Measurement data are given as the mean ± SD. Enumeration and ranked data are given as numbers of each portion.

Table 2 Correlations between graft extrusions and potential factors

	Medial extrusion		Anterior extrusion		Posterior extrusion		Mean extrusion
	Pearson r	P value	Pearson r	P value	Pearson r	P value	Pearson r	P value
1 wk after operation
Preoperative medial posterior tibial slope	0.259	0.575	0.375	0.360	0.381	0.399	0.362	0.425
Preoperative Kellgren-Lawrence grade	0.646	0.044a	0.125	0.732	0.543	0.105	0.488	0.152
Preoperative hip-knee-ankle angle	-0.580	0.079	-0.127	0.727	-0.625	0.053	-0.518	0.125
Preoperative bilateral hip-knee-ankle angle difference	0.736	0.015a	0.272	0.448	0.725	0.018a	0.661	0.038a
Preoperative absolute joint space width	-0.672	0.034a	-0.218	0.545	-0.668	0.035a	-0.591	0.072
Preoperative relative joint space width	-0.934	0.000a	-0.575	0.082	-0.795	0.006a	-0.873	0.001a
Preoperative medial edge incline angle	0.332	0.349	-0.006	0.987	0.455	0.186	0.311	0.382
Preoperative bilateral medial edge incline angle difference	0.678	0.031a	0.133	0.713	0.756	0.011a	0.604	0.064
Medial extrusion			0.711	0.021a	0.733	0.016a	0.914	0.000a
Anterior extrusion	0.711	0.021a			0.480	0.160	0.818	0.004a
Posterior extrusion	0.733	0.016a	0.480	0.160			0.872	0.001a
8 mo after operation
Preoperative medial posterior tibial slope	0.643	0.357	-0.265	0.735	0.469	0.531	0.415	0.585
Preoperative Kellgren-Lawrence grade	0.832	0.040a	0.142	0.789	0.575	0.233	0.596	0.212
Preoperative hip-knee-ankle angle	-0.890	0.018a	-0.142	0.789	-0.799	0.056	-0.735	0.096
Preoperative bilateral hip-knee-ankle angle difference	0.962	0.002a	0.398	0.434	0.867	0.025a	0.868	0.025a
Preoperative absolute joint space width	-0.723	0.105	-0.208	0.692	-0.675	0.142	-0.638	0.173
Preoperative relative joint space width	-0.940	0.005a	-0.266	0.610	-0.887	0.018a	-0.834	0.039a
Preoperative medial edge incline angle	0.509	0.302	-0.398	0.434	0.229	0.662	0.156	0.767
Preoperative bilateral medial edge incline angle difference	0.848	0.033a	-0.052	0.921	0.625	0.185	0.571	0.236
Medial extrusion			0.324	0.531	0.844	0.035a	0.854	0.031a
Anterior extrusion	0.324	0.531			0.614	0.194	0.721	0.106
Posterior extrusion	0.844	0.035a	0.614	0.194			0.985	0.000a

^aP value ≤ 0.05.

Table 3 Correlations between sagittal graft extrusions and tunnel edge distances

	Anterior extrusion		Posterior extrusion
	Pearson r	P value	Pearson r	P value
1 wk after operation
Anterior tunnel edge distance	-0.753	0.012a	-0.151	0.676
Posterior tunnel edge distance	-0.349	0.323	-0.658	0.039a
8 mo after operation
Anterior tunnel edge distance	-0.910	0.012a	-0.634	0.177
Posterior tunnel edge distance	-0.728	0.101	-0.942	0.005a

^aP value ≤ 0.05.

Table 4 Correlations between relative posterior graft position ratio and preoperative medial posterior tibial slope

	Relative posterior graft position ratio
	Pearson r	P value
1 wk after operation
Preoperative medial posterior tibial slope	0.800	0.031a
8 mo after operation
Preoperative medial posterior tibial slope	0.147	0.854

^aP value ≤ 0.05.

Two patients were excluded from the analysis because of the additional anterior closing wedge high tibial osteotomy.

Table 5 Regressions between graft extrusions and potential factors

y	Standardized	Equation	P value				R2
			Regression	x1	x1	x1
				Preoperative relative joint space width	Anterior tunnel edge distance	Posterior tunnel edge distance
1 wk after operation
Medial extrusion	Yes	y = -14.6x1 + 68.9	0.000	0.000			0.873
	No	y = -0.0604x1 + 0.737
Anterior extrusion	Yes	y = -9.755x2 + 5.77	0.006		0.006		0.632
	No	y = -1.185x2 + 1.831
Posterior extrusion	Yes	y = -0.6192x1 - 0.3481x3 + 86.65	0.009	0.024		0.132	0.741
	No	y = -14.75x1 - 0.1744x3 + 12.07
Mean extrusion	Yes	y = -12.6x1 + 44.6	0.001	0.001			0.763
	No	y = -0.0523x1 + 0.63
8 mo after operation
Medial extrusion	Yes	y = -15.13x1 + 88.34	0.005	0.005			0.884
	No	y = -0.04563x1 + 0.7183
Anterior extrusion	Yes	y = -16.80x2 - 6.641	0.012		0.012		0.827
	No	y = -0.9522x2 + 2.994
Posterior extrusion	Yes	y = -0.3597x1 - 0.6639x3 + 99.15	0.016	0.232		0.078	0.936
	No	y = -14.09x1 - 0.5704x3 + 17.02
Mean extrusion	Yes	y = -11.74x1 + 62.93	0.039	0.039			0.696
	No	y = -0.0354x1 + 0.6417