Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal bearings

Figures & data

Figure 1. Inclusion of patients in the study population.

Table 1. Patient- and surgery-related characteristics for the patients who received cementless total hip arthroplasty with metal-on-metal (MoM) bearings or metal-on-polyethylene (MoP) bearings. Values are numbers of patients and percentages (%) within each group

	MoM n = 11,567	MoP n = 21,111	p-value
Sex			< 0.001
Female	5,227 (45)	10,689 (51)
Male	6,340 (55)	10,422 (49)
Age groups (years)			< 0.001
< 40	282 (2)	576 (3)
40–49	969 (8)	1,768 (8)
50–59	3,188 (28)	5,578 (27)
60–69	4,712 (41)	8,249 (39)
70–79	2,200 (19)	4,007 (19)
≥ 80	216 (2)	933 (4)
Diagnosis			< 0.001
Primary OA	10,595 (92)	18,694 (89)
Femoral head osteonecrosis	232 (2)	631 (3)
Arthritis	404 (3)	427 (2)
Childhood hip disorders	336 (3)	1,359 (6)
Femoral head size (mm)			< 0.001
≤ 27	7 (0)	221 (1)
28–31	118 (1)	10,374 (49)
32–35	117 (1)	5,842 (28)
36–37	707 (6)	4,068 (19)
38–39	2,317 (20)	17 (0)
40–43	679 (6)	403 (2)
44–47	2,431 (21)	44 (0)
48–51	3,124 (27)	38 (0)
≥ 52	2,067 (18)	104 (1)
Year of surgery			< 0.001
2002	17 (0)	484 (2)
2003	39 (0)	1,394 (7)
2004	109 (1)	1,647 (8)
2005	887 (8)	1,867 (9)
2006	1,641 (14)	2,097 (10)
2007	2,305 (20)	2,385 (11)
2008	2,691 (23)	2,837 (13)
2009	2,357 (21)	3,661 (17)
2010	1,521 (13)	4,739 (23)
Country			< 0.001
Denmark	2,636 (23)	12,103 (57)
Norway	88 (1)	1,141 (6)
Sweden	454 (4)	7,597 (36)
Finland	8,389 (72)	270 (1)

Figure 2. Cumulative incidence for any revision of cementless total hip arthroplasty with metal-on-metal (MoM) bearings and metal-on-polyethylene (MoP) bearings.

Figure 3. Cumulative incidence for revision (for any reason) of metal-on-polyethylene (MoP) total hip arthroplasty (THA) and specific designs of cementless acetabular components in stemmed THA with metal-on-metal bearings.

Figure 4. Cumulative incidence for revision (for any reason) of metal-on-polyethylene (MoP) total hip arthroplasty (THA) and combinations of specific designs of cementless acetabular and femoral components in stemmed THA with metal-on-metal bearings.

Table 6. Median follow-up and revision rate for different sizes of the femoral head used in cementless stemmed total hip arthroplasty (THA) with metal-on-metal (MoM) bearings. Crude and adjusted relative risk (RR) of revision for any reason with 95% confidence intervals (CIs) at 6-year follow-up

	No.(%)	Median follow-up (IQR)	Any revision (n)	Risk time, years	Revision rate per 100 years (95% CI)	Crude RR >(95% CI)	Adjusted RR (95% CI)
All MoM THAs
≤ 37	949 (8)	3.3 (2.2–4.3)	46	3,313	1.39 (1.04–1.85)	1.48 (0.98–2.25)	1.48 (0.95–2.32)
38–39	2,317 (20)	4.9 (3.3–6.1)	93	10,673	0.87 (0.71–1.07)	1 (ref.)	1 (ref.)
40–43	679 (6)	3.0 (2.1–4.3)	20	2,189	0.91 (0.59–1.42)	1.07 (0.65–1.77)	1.14 (0.65–2.02)
44–47	2,431 (21)	3.4 (2.3–4.5)	128	8,443	1.52 (1.27–1.80)	1.77 (1.27–2.48)	1.68 (1.17–2.40)
48–51	3,124 (27)	3.3 (2.3–4.5)	108	10,668	1.01 (0.84–1.22)	1.27 (0.90–1.80)	1.38 (0.93–2.04)
≥ 52	2,067 (18)	3.2 (2.3–4.4)	75	6,917	1.08 (0.86–1.36)	1.14 (0.79–1.62)	1.33 (0.92–1.93)
MoM THAs after exclusion of patients having the ASR acetabular component
≤ 37	938 (9)	3.3 (2.2–4.3)	45	3,257	1.38 (1.03–1.85)	1.38 (0.91–2.08)	1.40 (0.90–2.19)
38–39	2,314 (21)	4.9 (3.3–6.1)	93	10,661	0.87 (0.71–1.07)	1 (ref.)	1 (ref.)
40–43	643 (6)	3.0 (2.1–4.2)	15	2,049	0.73 (0.44–1.21)	0.74 (0.44–1.26)	0.75 (0.42–1.32)
44–47	2,136 (20)	3.4 (2.3–4.4)	83	7,302	1.14 (0.92–1.41)	1.06 (0.76–1.49)	1.00 (0.68–1.48)
48–51	2,866 (26)	3.3 (2.3–4.4)	75	9,696	0.77 (0.62–0.97)	0.83 (0.58–1.18)	0.90 (0.59–1.39)
≥ 52	1,918 (18)	3.2 (2.2–4.3)	59	6,365	0.93 (0.72–1.20)	0.83 (0.58–1.19)	0.97 (0.66–1.43)