Uncemented total hip arthroplasty for primary osteoarthritis in young patients: A mid-to long-term follow-up study from the Finnish Arthroplasty Register

Figures & data

Table 1.  Design, surface and material of the femoral and acetabular components in the study

Brand	Material	Surface	Design	Screw-holes
Stems
ABG I	Titanium alloy	Proximal HA-coating	Anatomic	–
Anatomic Mesh	Titanium alloy	Proximal porous-coating	Anatomic	–
Bi-Metric	Titanium alloy	Proximal porous-coating	Straight	–
Lord Madreporiq	Cobalt-chromium	Proximal porous-coating	Straight	–
PCA Std	Cobalt-chromium	Proximal porous-coating	Anatomic	–
Profile Porous	Titanium alloy	Proximal porous-coating	Anatomic	–
CLS Spotorno	Titanium alloy	Grit-blasted	Straight, proximal fins	–
Cups
ABG I	Titanium alloy	HA-coating	Hemispherical	Open
ABG II	Titanium alloy	HA-coating	Hemispherical	Closed
Biomet Mallory	Titanium alloy	Porous-coating	Hemispherical	Open
Biomet Romanus	Titanium alloy	Porous-coating	Hemispherical	Open
Biomet Universal	Titanium alloy	Porous-coating	Hemispherical	Open
Biomet Vision	Titanium alloy	Porous-coating	Hemispherical	Closed
Harris-Galante II	Titanium alloy	Porous-coating	Hemispherical	No screw-holes
Morscher Press-Fit	Titanium alloy	Fiber-mesh	Hemispherical	Open
PCA Pegged	Cobalt-chromium	Porous-coating	Hemispherical	Open
Profile Duraloc	Titanium alloy	Porous-coating	Hemispherical	Open

Table 2.  Reasons for revision of components in the study. Values are no. of revisions (revision burden %)

A	B	C	D	E	F	G	H	I	J
Stems
ABG I	390	2 (0.5)	–	4 (1.0)	–	–	–	…	6 (1.5)
Anatomic Mesh	135	13 (8.5)	–	–	1 (0.7)	4 (3.0)	–	…	18 (12)
Bi-Metric	1982	37 (1.8)	7 (0.3)	15 (0.8)	12 (0.6)	–	2 (0.1)	…	73 (3.6)
Lord Madréporique	286	26 (8.3)	1 (0.3)			2 (0.6)		…	29 (9.2)
PCA Std	111	9 (7.4)	1 (0.8)	–		1 (0.8)	–	…	11 (9.0)
Profile Porous	115	–	1 (0.8)	4 (3.2)	2 (1.6)	2 (1.6)	–	…	9 (7.3)
CLS Spotorno	108	1 (0.9)	–	1 (0.9)	–	1 (0.9)	1 (0.9)	…	4 (3.7)
Cups
ABG I	108	4 (3.1)	0	4 (3.1)	0	…	…	14 (11)	22 (17)
ABG II	473	1 (0.2)	1 (0.2)	0	0	…	…	0	2 (0.4)
Biomet Mallory	110	5 (3.8)	0	1 (0.8)	1 (0.8)	…	…	14 (11)	21 (16)
Biomet Romanus	114	18 (11)	1 (0.6)	2 (1.3)	0	…	…	23 (15)	44 (28)
Biomet Universal	898	34 (3.4)	2 (0.2)	12 (12)	8 (0.8)	…	…	58 (5.7)	114 (11)
Biomet Vision	418	0	1 (2.4)	1 (2.4)	1 (2.4)	…	…	1 (2.4)	4 (0.9)
Harris-Galante II	277	16 (5.1)	2 (0.6)	3 (1.0)	1 (0.3)	…	…	15 (4.8)	37 (12)
Morscher Press-Fit	136	2 (1.4)	0	1 (0.7)	0	…	…	0	3 (2.2)
PCA Pegged	122	37 (23)	1 (0.6)	0	0	…	…	1 (0.6)	39 (24)
Profile Duraloc	145	1 (0.7)	0	3 (2.0)	1 (0.7)	…	…	3 (2.0)	8 (5.2)

A Brand B Operations (n) C Aseptic loosening D Infection E Dislocation F Malposition G Fracture of stem H Fracture of bone I Other reasons for cup revision including exchange of liner J Total

Table 3.  Survival and adjusted risk ratio for revision of stem brands. Endpoint was defined as revision due to aseptic loosening of the stem or stem revision for any reason. 7−, 10−, and 15–year survival rates obtained from the Kaplan–Meier analysis

A	B	C	D	E	F	G	H	I	J	k
Revision for aseptic stem loosening
ABG I	2/390	5.5	128	100 (99–100)	39	100 (99–100)	0	–	0.4 (0.1–1.7)	0.2
Anatomic Mesh	13/135	9.8	116	100 (94–100)	80	92 (87–97)	3	–	2.8 (1.5–5.4)	0.002
Lord Madrép.	26/286	16	264	95 (92–97)	248	92 (88–95)	219	91 (86–94)	2.2 (1.3–3.7)	0.004
Profile Porous	0/115	9.3	100	100	58	100	2	–	–	NA
PCA Standard	9/111	13	102	95 (91–99)	96	93 (89–98)	38	90 (84–97)	1.8 (0.9–3.9)	0.1
CLS Spotorno	1/108	5.9	45	99 (97–100)	28	99 (97–100)	9	–	0.5 (0.1–3.8)	0.5
Bi-Metric	37/1982	6.6	937	99 (98–99)	508	96 (95–98)	117	95 (93–97)	ref.
Any stem revision
ABG I	6/390	5.5	128	99 (98–100)	39	97 (94–100)	0	–	0.5 (0.2–1.2)	0.1
Anatomic Mesh	18/135	9.8	116	95 (91–99)	80	91 (85–96)	3	–	2.2 (1.3–3.7)	0.004
Lord Madrép.	29/286	15.8	264	94 (92–97)	248	91 (88–95)	219	90 (86–93)	1.4 (0.9–2.2)	0.2
Profile Porous	9/115	9.3	101	94 (89–98)	58	93 (88–98)	2	–	1.4 (0.7–2.8)	0.3
PCA Standard	11/111	13.0	102	95 (91–99)	96	93 (88–98)	38	88 (82–95)	1.3 (0.7–2.5)	0.4
CLS Spotorno	4/108	5.9	45	96 (91–100)	28	96 (91–100)	9	–	1.1 (0.4–2.9)	0.9
Bi–Metric	73/1982	6.6	38	97 (96–98)	508	94 (92–95)	117	92 (90–94)	ref.

A Stem brand B Number of revisions/number of total operations C Mean follow–up (years) D Number at risk at 7 years E Percentage 7–year survival (95% CI) F Number at risk at 10 years G Percentage 10–year survival (95% CI) H Number at risk at 15 years I Percentage 15–year survival (95% CI) J Adjusted risk ratio for revision (95% CI) from the Cox regression analysis (other brands of stem compared to the Bi–Metric stem; adjustment made for age and gender) K P-valueNA = not assigned

Figure 1. Cox-adjusted survival curves of 3,127 stems in patients under 55 years of age, with brand of stem as the strata factor. Endpoint was defined as stem revision due to aseptic loosening. Adjustment has been made for age and gender. The curve of the Profile Porous stem is not shown, as it had a 100% survival rate at 10 years.

Table 4a.  Survival and adjusted risk ratio for revision of cup brands. Endpoint was defined as revision due to aseptic loosening of the cup. 5–, 10– and 13–year survival rates obtained from the Kaplan–Meier analysis

Survival A	B	C	D	E	F	G	H	I
ABG I	4/108	8.2	102	99 (97–100)	28	95 (90–100)	0	–
ABG II	1/473	3.3	135	99 (98.– 100)	0	–	0	–
Biomet Mallory	5/110	7.5	98	98 (95–100)	20	87 (73–100)	0	–
Biomet Romanus	18/114	9.6	107	96 (93–100)	66	88 (81–94)	17	–
Biomet Universal	34/898	7.3	724	99 (98–100)	217	93 (91–96)	58	90 (86–94)
Biomet Vision	0/418	2.6	59		0	–	0	–
Harris-Galante II	16/277	9.3	255	99 (98–100)		94 (90–97)	33	91 (86–95)
Morscher Press-Fit	2/136	3.4	23	100	17	–	11	–
PCA Pegged	37/122	10.6	113	97 (93–100)	82	76 (68–85)	40	64 (54–74)
Profile Duraloc	1/145	5.5	90	99 (98–100)	14	–	0	–

Adjusted risk ratio^a	All		Follow-up < 5 years		Follow-up > 5 years
	ARR (95% CI)	p-value	ARR (95% CI)	p-value	ARR (95% CI)	p-value
ABG I	0.6 (0.2–1.7)	0.4	0.5 (0.1–2.2)	0.3	0.8 (0.2–2.7)	0.7
ABG II	0.3 (0.0–2.6)	0.3	–	NA
Biomet Mallory	1.3 (0.5–3.3)	0.6	1.5 (0.3–6.7)	0.6	1.1 (0.3–3.8)	0.8
Biomet Romanus	2.5 (1.4–4.6)	0.002	2.8 (0.9–9.1)	0.08	2.5 (1.3–4.8)	0.009
Biomet Universal	ref.	–	ref.	–	ref.	–
Biomet Vision	–	NA	–	NA	–	NA
Harris-Galante II	1.0 (0.5–1.7)	0.9	0.9 (0.2–3.2)	0.8	1.0 (0.5–1.9)	0.9
Morscher Press-Fit	0.8 (0.2–3.5)	0.8	–	NA	1.1 (0.3–4.9)	0.9
PCA Pegged	3.9 (2.4–6.3)	< 0.001	2.7 (0.8–8.5)	0.1	4.2 (2.4–7.3)	<0.001
Profile Duraloc	0.3 (0.0–2.2)	0.2	0.7 (0.1–5.6)	0.7	–	NA

A Cup brand B Number of revisions/number of total operations C Mean follow–up (years) D Number at risk at 5 years E Percentage 5–year survival (95% CI) F Number at risk at 10 years G Percentage 10–year survival (95% CI) H Number at risk at 13 years I Percentage 13–year survival (95% CI) ^aAdjusted risk ratio (ARR) for revision (95% CI) from the Cox regression analysis (other brands of cup compared tothe Universal cup; adjustment made for age and gender). NA = not assigned

Table 4b.  Survival and adjusted risk ratio for revision of cup brands. Endpoint was defined as cup revision for any reason. 5−, 10− and 13–year survival rates were obtained from the Kaplan-Meier analysis

Survival A	B	C	D	E	F	G	H	I
ABG I	22/108	8.2	102	97 (94–100)	28	79 (70–88)	0	–
ABG II	2/473	3.3	135	99 (98–100)	0	–	0	–
Biomet Mallory	21/110	7.5	99	96 (93–100)	21	61 (45–78)	0	–
Biomet Romanus	44/114	9.6	108	91 (86–96)	68	71 (62–80)	17	–
Biomet Universal	114/898	7.3	726	96 (95–98)	223	79 (75–83)	58	74 (69–79)
Biomet Vision	4/418	2.6	59	99 (98–100)	0	–	0	–
Harris–Galante II	37/277	9.3	255	97 (94–99)	141	87 (83–92)	33	78 (70–85)
Morscher Press–Fit	3/136	3.4	23	99 (97–100)	17	–	11	–
PCA Pegged	39/122	10.6	113	97 (93–100)	82	75 (67–83)	41	63 (53–73)
Profile Duraloc	8/145	5.5	91	93 (89–98)	14	–	0	–

Adjusted risk ratio^a	All		Follow-up < 5 years		Follow-up > 5 years
	ARR (95% CI)	p-value	ARR (95% CI)	p-value	ARR (95% CI)	p-value
ABG I	0.9 (0.6–1.4)	0.6	0.3 (0.1–0.8)	0.02	1.4 (0.8–2.2)	0.2
ABG II	0.2 (0.0–0.6)	0.009	0.2 (0.0–0.7)	0.02	–	NA
Biomet Mallory	1.5 (0.9–2.4)	0.08	1.0 (0.4–2.8)	1.0	1.7 (1.0–2.9)	0.04
Biomet Romanus	1.9 (1.3–2.7)	<0.001	2.4 (1.2–5.0)	0.02	1.8 (1.2–2.7)	0.06
Biomet Universal	ref.	–	ref.	–	ref.
Biomet Vision	0.5 (0.2–1.3)	0.2	0.5 (0.2–1.4)	0.2	–	NA
Harris–Galante II	0.7 (0.5–1.0)	0.04	0.9 (0.4–1.9)	0.7	0.6 (0.4–1.0)	0.03
Morscher Press–Fit	0.4 (0.1–2.9)	0.4	0.4 (0.1–1.6)	0.2	–	NA
PCA Pegged	1.3 (0.9–1.9)	0.2	0.9 (0.3–2.5)	0.8	1.4 (0.9–2.1)	0.1
Profile Duraloc	0.7 (0.3–1.4)	0.3	1.8 (0.8–3.8)	0.2	–	NA

For abbreviations see Table 4a

Figure 2. Cox-adjusted survival curves calculated for 2,801 cups, with brand of cup as the strata factor. Endpoint was defined as cup revision due to aseptic loosening. Adjustment has been made for age and gender. The curve of the Biomet Vision cup is not shown, as it had a 100% survival rate at 5 years.

Figure 3. Cox-adjusted survival curves calculated for 2,801 cups, with brand of cup as the strata factor. Endpoint was defined as any cup revision. Adjustment has been made for age and gender. The curves of the ABG II and the Biomet Vision cups are not shown, as they had a 100% survival rate.

Table 5.  Survival of THR combinations and adjusted risk ratio for revision. Endpoint was defined as revision due to aseptic loosening of the stem and/or the cup or any revision. 5–, 10– and 13–year survival rates were obtained from the Kaplan–Meier analysis

A	B	C	D	E	F	G	H	I	J	K
ABG I–ABG I	3/105	8.2	99	100	27	60 (91–100)	0	–	0.6 (0.2–1.9)	0.4
ABG I–ABG II	3/266	4.3	122	99 (97–100)	0	–	0	–	0.9 (0.3–3.2)	0.9
Anat. Mesh–HG II	14/127	9.7	120	98 (95–100)	75	93 (88–98)	20	82 (73–92)	1.6 (0.8–3.0)	0.2
Bi-Metric–Mallory	6/107	7.5	95	96 (92–100)	20	87 (74–100)	0	–	1.4 (0.6–3.4)	0.4
Bi-Metric–Universal	36/858	7.4	706	99 (98–99)	216	93 (90–96)	57	89 (85–94)	ref.
Bi-Metric–Vision	0/385	2.6	55	100	0	–	0	–	–	NA
Bi-Metric–Romanus	19/106	9.4	99	95 (91–99)	58	86 (78.–93)	15	–	2.8 (1.6–4.9)	<0.001
PCA Std–PCA Peg.	37/107	11.1	101	95 (91–99)	78	74 (66–83)	40	63 (52–73)	4.0 (2.5–6.5)	<0.001
Any revision
ABG I-–ABG I	21/105	8.2	99	98 (95–100)	27	79 (70–88)	0	–	1.3 (0.8–2.1)	0.3
ABG I–ABG II	3/266	4.3	122	99 (97–100)	0	–	0	–	0.3 (0.1–1.0)	0.04
Anat. Mesh–HG II	29/127	9.7	120	97 (94–100)	76	86 (80–93)	20	63 (51–75)	1.0 (0.7–1.6)	0.9
Bi-Metric–Mallory	21/107	7.5	96	94 (90–99)	21	62 (46–79)	2	–	1.5 (1.0–2.5)	0.07
Bi-Metric–Universal	112/858	7.4	707	96 (95–98)	220	79 (75–83)	57	74 (69–79)	ref.
Bi-Metric–Vision	2/385	2.6	55	100 (99–100)	0	–	0	–	0.3 (0.1–1.1)	0.06
Bi-Metric–Romanus	45/106	9.4	101	90 (84–95)	60	68 (58–77)	15	–	2.2 (1.5–3.1)	<0.001
PCA Std–PCA Peg.	40/107	11.1	101	95 (91–99)	78	72 (64–81)	40	60 (50–70)	1.4 (1.0–2.1)	0.06

A THR brand B Number of revisions–number of total operations C Mean follow–up (years) D Number at risk at 5 years E Percentage 5–year survival (95% CI) F Number at risk at 10 years G Percentage 10–year survival (95% CI) H Number at risk at 13 years I Percentage 13–year survival (95% CI) J Adjusted risk ratio for revision (95% CI) from the Cox regression analysis (other brands of stem compared to the Bi–Metric/Universal THR; adjustment made for age and gender); NA= not assigned K P–value

Figure 4. Cox-adjusted survival curves calculated for 2,061 THRs, with implant combination as the strata factor. Endpoint was defined as revision due to aseptic loosening of the stem and/or the cup. Adjustment has been made for age and gender. The curve of the Bi-Metric – Vision is not shown, as it had a 100% survival rate at 5 years.