Robot-assisted primary cementless total hip arthroplasty with a short femoral stem: a prospective randomized short-term outcome study

Figures & data

Table 1. Comparison of demographic data between robotic milling and manual rasping groups.

	Robotic group (n = 24)	Manual group (n = 25)	p Value
Age (years)	51.2 (19–67)	45.6 (21–65)	0.107
Gender (male/female)	11/13	13/12	0.525
Body-mass index (kg/m^2)	24.7 (21–29)	25.1 (20–31)	0.608
Etiology			0.285
Osteonecrosis	16	13
Osteoarthitis	8	10
Others	0	2

Values are presented as mean (range).

Figure 1. Photograph of tri-lock bone preservation stem (DePuy/J&J, Warsaw, IN).

Figure 2. Intraoperative photograph showing a new femoral fixator clamp attached to the femoral head.

Table 2. Comparison of outcome data between robotic milling and manual rasping groups.

	Robotic group (n = 24)	Manual group (n = 25)	p Value
Total operation time (min)	103 (83–141)	78 (57–147)	0.012
Registration time (min)	8.9 (5–15)	n/a
Milling time (min)	11.2 (7–20)	n/a
Total blood loss (cc)	1010 (610–1800)	895 (410–1370)	0.271
Harris hip score (points)
Preoperative	52 (37–61)	55 (41–60)	0.155
24 months post-operative	93 (85–100)	95 (89–100)	0.512
WOMAC score (points)
Preoperative	60 (44–85)	61 (45–89)	0.517
24 months post-operative	11 (6–17)	12 (5–15)	0.301
Stem alignment (°)	0.3 (0–2.8)	2.2 (0–7.4)	0.005
Outlier (>±3°)	0	6	0.022
Leg length discrepancy (mm)	1.9 (0–6.4)	4.9 (0–16)	0.011
Outlier (>10 mm)	0	3	0.235
Loosening of stem	0	0	1.000
Complications
Intraoperative femoral fracture	0	2	0.490
Infection	0	0	1.000
Nerve palsy	0	0	1.000
Dislocation	0	0	1.000

Values are presented as mean (range).

Figure 3. Anteroposterior radiograph of both hips after robotic milling THA shows that stem is fixed in a satisfactory position with no leg length discrepancy.

Figure 4. Anteroposterior radiograph of the right hip after manual rasping THA shows a stem alignment in 7.9° of varus.