Effect of femoral head size on polyethylene wear and synovitis after total hip arthroplasty: A sonographic and radiographic study of 39 patients

Figures & data

Figure 1. Sonographic measurement of the capsular distance in THA. AC: echo from the anterior surface of the anterior hip joint capsule; FN: echo from the anterior surface of the prosthetic femoral neck; FH: echo from the anterior surface of the prosthetic femoral head; d represents the distance between the anterior capsule and the prosthetic femoral neck.

Figure 2. Schematic drawing showing sonographic findings in THA patients. FH: prosthetic femoral head; FN: prosthetic femoral neck; AC: anterior capsule; d is the distance between the anterior capsule and the prosthetic femoral neck; 1 is the echo from the prosthetic femoral head (FH); 2 is the echo from the prosthetic femoral head (FN); 3 is the echo from the prosthetic collar (not always present).

Table

	28 mm (n = 23)	32 mm (n = 16)	P‐value
Linear wear/year, mm	0.09 (0.05)	0.18 (0.09)	< 0.001
Volumetric wear/year, mm^3	51 (28)	136 (70)	< 0.001
Capsular distance, mm	13.1 (2.7)	16.6 (3.0)	< 0.001
Activity level	5.1 (1.2)	5.3 (1.3)	0.7
Age	71 (10)	74 (6.5)	0.2
BMI	30 (5.5)	28 (3.9)	0.3
Cup inclination angle	51 (7.7)	52 (5.4)	0.7
PE wear angle	47 (19)	55 (13)	0.1