The transverse pelvic plane: A new and practical referenceframe for hip arthroplasty

Figures & data

Figure 1. Anteroposterior view showing the anterior pelvic plane (plane ABC or APP_Cor, shown in green); planes APP_Sag and APP_Ax are represented by the blue and green dashed lines respectively.

Figure 2. Cephalocaudal view showing the transverse pelvic plane (ADE or TPP_Ax, shown in green); planes TPP_Sag and TPP_Cor are represented by the blue and red dashed lines respectively.

Figure 3. Right lateral view showing the angle between planes TPP_Ax (green) and APP_Cor (red); points A and D are overlapping with points B and E, respectively.

Figure 4. Cephalocaudal view showing the relationship between the plane of the acetabulum and plane APP_AX; line FG is formed by the intersection of the two planes, and the angle between this line and plane APP_Sag (blue dashed line) is the anteversion relative to the APP coordinate system (AV_APP). [Color version available online.]

Figure 5. Cephalocaudal view showing the relationship between the plane of the acetabulum and plane TPP_Ax; line HI is formed by the intersection of the two planes, and the angle between this line and plane TPP_Sag is the anteversion relative to the TPP coordinate system (AV_TPP). [Color version available online.]

Table I.  Acetabular anteversion (AV) and inclination (Inc) in relation to the APP and TPP coordinate systems.

Hip/Observer	AVAPP			AVTPP			IncAPP			IncTPP
	1	2	3	1	2	3	1	2	3	1	2	3
1	28	26	27	33	31	32	52	52	52	57	59	57
2	18	19	19	28	24	27	61	63	61	67	71	66
3	19	20	29	33	29	30	57	59	58	65	66	64
4	12	11	10	16	18	15	56	55	57	53	54	59
5	20	15	19	24	25	24	58	55	58	63	62	60
6	22	22	23	30	31	28	54	54	54	57	60	60
7	26	27	22	33	32	32	50	53	51	57	57	57
8	18	12	13	25	19	24	52	47	46	55	48	51
9	39	38	44	41	42	46	58	59	65	62	65	69
10	22	22	21	31	35	28	53	54	53	56	65	58
11	21	20	20	25	28	26	57	57	55	64	64	62
12	26	25	24	41	42	41	48	43	49	67	57	63
13	18	14	14	35	29	30	49	47	48	58	53	57
14	26	26	26	37	37	36	46	47	47	52	55	54
15	15	15	15	25	26	25	48	48	49	53	53	54
16	7	8	8	24	22	23	51	51	51	56	48	56
17	8	8	9	22	18	23	56	57	56	65	69	63
18	12	11	12	39	35	36	44	45	44	63	57	58
19	18	20	21	25	26	26	54	56	56	57	56	64
20	21	22	21	32	31	33	55	56	56	64	66	63
21	18	15	20	32	30	35	47	48	46	61	58	55
22	21	21	20	28	23	28	57	59	57	63	62	63
23	23	22	25	28	25	27	57	58	55	56	52	55
24	36	40	37	42	41	42	59	61	61	71	69	68
25	28	30	30	32	31	34	60	62	60	68	66	64
26	18	20	19	28	24	24	55	56	58	59	56	61
27	26	25	27	41	36	40	47	50	49	60	57	61
28	21	21	21	27	23	25	60	60	60	67	54	63
29	32	30	30	35	33	31	56	58	58	61	61	60
30	25	26	25	29	28	25	65	66	66	68	68	67
31	20	20	19	23	23	23	54	54	55	56	55	58
32	31	33	33	35	33	37	53	50	52	58	58	55
33	25	26	26	27	34	27	56	58	56	56	57	56
34	18	13	22	32	20	30	51	55	55	63	61	62
Average	22	21	22	31	29	30	54	55	55	61	59	60
Maximum	39	40	44	42	42	46	65	66	66	71	71	69
Minimum	7	11	8	16	18	15	44	43	44	52	48	51
Range	32	29	36	26	24	31	21	23	22	19	23	18
Std Dev	7	8	8	6	6	7	5	5	5	5	6	4

Table II.  Reliability correlations for the APP and TPP coordinate systems. (AV = anteversion; Inc = inclination)

	Reliability	Lower 95%	Upper 95%
AVAPP	0.94	0.89	0.97
AVTPP	0.88	0.79	0.93
IncAPP	0.72	0.57	0.84
IncTPP	0.92	0.87	0.96

Figure 6. Scatter diagram showing the average anteversion (AV_APP) and inclination (Inc_APP) angles for the 34 hips relative to the APP. The “safe zone” of Lewinnek is also shown (dashed lines). [Color version available online.]