Early stabilization of the uncemented Symax hip stem in a 2-year RSA study

Figures & data

Figure 1. Design features of Symax hip stem, illustrating the anatomically anteverted proximal geometry, with the BONIT-HA coating; and the straight distal part with the DOTIZE surface treatment and a posterior chamfer.

Figure 2. The Elementary Geometrical Shapes (EGS) model used to determine the migration of the Symax hip stem.

Table 1. Baseline characteristics of included patients

	Female	Male	Total
Factor	(n = 22)	(n = 23)	(n = 45)
Mean age (range)	60 (44–70)	59 (30–70)	60 (30–70)
BMI (SD)	27 (4)	27 (3)	27 (3)
Osteoarthritis/avascular necrosis	22/0	22/1	44/1

Table 2. Number of patients per follow-up moment

Evaluation	Baseline	4 weeks	3 months	6 months	1 year	2 years
RSA analysis	35	33	32	32	31	31
Clinical	45	–	45	45	45	44
Radiographic	45	–	45	45	45	44

Figure 3a. Mean translation results for the Symax hip stem.

Figure 3b. Mean rotation results for the Symax hip stem.

Table 3. Clinical outcomes as mean (CI) HHS, OHS, WOMAC, and EQ-5D over time

Score/subscore	Preoperatively	3 months	6 months	1 year	2 years
HHS	63 (33 to 93)	96 (82 to 110) ^a	98 (91 to 105) ^a	98 (90 to 107)	99 (92 to 105) ^a
OHS	37 (22 to 53)	23 (7 to 39) ^a	20 (6 to 34) ^a	19 (5 to 33)	18 (5 to 31) ^a
WOMAC
Total	50 (13 to 86)	17 (–8 to 41) ^a	13 (–13 to 39) ^a	12 (–14 to 38)	10 (–14 to 34)
Pain	10 (2 to 18)	2 (–3 to 7) ^a	2 (–4 to 7)	2 (–4 to 8)	1 (–4 to 7)
Stiffness	4 (0 to 8)	2 (–1 to 5) ^a	2 (–1 to 5) ^a	1 (–1 to 4)	1 (–1 to 4)
Physical functioning	36 (10 to 62)	12 (–6 to 30) ^a	9 (–10 to 28) ^a	9 (–10 to 27)	7 (–11 to 25)
EQ-5D
Index	69 (42 to 96)	88 (68 to 107) ^a	91 (72 to 110) ^a	91 (72 to 110)	93 (75 to 111)
VAS	67 (26 to 108)	83 (56 to 109) ^a	84 (58 to 110)	84 (55 to 113)	87 (58 to 116) ^a

^aIndicates Wilcoxon signed-rank test p-value < 0.05 compared with the preceding clinical outcome.

Table 4. Spearman’s rho correlation coefficients (CC), with p-values, for correlation between Y-translation and Y-rotation at 4 weeks and clinical outcomes (HHS, OHS, WOMAC, and EQ-5D) after 2 years

	CC Y			CC Y
Score/subscore	translation	p-value	rotation	p-value
HHS	0.013	0.9	–0.22	0.2
OHS	0.11	0.5	0.080	0.7
WOMAC	0.068	0.7	0.072	0.7
EQ-5D
Index	–0.063	0.7	–0.21	0.3
VAS	0.062	0.7	–0.27	0.1

Figure 4. Outcomes of radiographic evaluation: number of patients per Gruen zone with cancellous hypertrophy (“spotweld formation”).