Bone cement product and failure in total knee arthroplasty

Figures & data

Figure 1. Bone cements used for TKAs in Norway in the period 1997–2013. TKAs with patellar component, unknown diagnosis, fixation without antibiotic-loaded bone cement, and hybrid fixation (or unequal bone cement in distal and proximal part) are not included.

Figure 2. The selection procedure from the data registered in the NAR. n = number of knees with TKA. ^a Illustrated in Figure 1.^b The time period of use included in study.

Table 1. Inclusion criteria for bone cements and prostheses with product information

Inclusion criteria	Products included	Distributor	Comments
Cements
Used >3 years. Used in over 1,000 knees. Equal bone cement in proximal and distal part of prosthesis
	Palacos with	Schering-Plough^a	The cement components (poly/monomers) was produced by Heraeus Kulzer
	gentamicin		and antibiotics were added by Schering-Plough. The single most used cement
			before 2005, and considered as the gold standard for many years. Mostly used in
			Scandinavia. Also referred to as Palacos R with gentamicin or Palacos R40G in
			some papers. Withdrawn from the market in 2005.
	Palacos	Merck	Identical cement components (poly/monomers) as in Palacos with gentamicin.
	Refobacin R		Antibiotics added under license from Merckby Heraeus Kulzer, and end product
			distributed by Merck^b. Withdrawn from the market in 2005.
	Palacos R + G	Heraeus Kulzer^c	The cement components (poly/monomers) are identical to those in Palacos with
			gentamicin. New vendor for gentamicin. Minor differences in production method
			for the addition of the gentamicin.
	Refobacin BCR	Biomet^d	Copy product of the old "Palacos" cement. New vendor of cement monomers/
			polymers. Antibiotics added with the same procedure as in Palacos Refobacin R.
	Optipac	Biomet^d	Identical components as Refobacin BCR, but all ingredients come
	Refobacin BCR		pre-packaged in a mixing system, which remains closed until the cement is appl
Prostheses
Used in the whole study period (1997–2013). Used in over 2,000 knees. Equal prosthesis proximally and distally.
	Profix	Smith and Nephew	Cruciate retaining.
	LCS	DePuy	Mobile bearing. LCS was used until 2006.
	LCS Complete	DePuy	Mobile bearing. Assessed as same prosthesis as LCS in this paper, due to the
			similarities. Used from 2003.
	AGC	Biomet	Cruciate retaining.
	NexGen	Zimmer	Cruciate retaining.

a Merged with Merck & Co. in 2009

b Later Biomet-Merck

c Heraeus Medical from year 2009 (company re-organization)

d Zimmer Biomet from year 2015

Table 2. Patient and procedure characteristics for the different bone cement products

Variables	Palacos with gentamicin	Refobacin Palacos R	Palacos R + G	Refobacin BCR	Optipac Refobacin BCR	Total
TKAs	7,650	1,206	8,278	4,505	4,508	26,147
Proportion of total, %	29	5	32	17	17	100
Males, %	29	31	35	35	37	33
Age in years, %
< 60	15	15	17	18	18	16
60–69	27	29	34	34	36	32
70–79	43	41	36	35	36	38
> 79	15	15	14	13	10	14
Prosthesis, %
AGC	22	20	6	28	9	15
NexGen	2	9	15	8	11	9
Profix	40	39	52	16	7	34
LCS/LCS complete	36	33	27	48	73	42
Diagnosis, %
Osteoarthritis	85	89	88	88	91	88
Other	15	11	12	12	9	12
No. of hospitals	65	33	52	40	29	75

Figure 3. Cox survival curves with cement product as stratification variable for all TKAs with revision for any reason as endpoint. The curves were estimated with adjustment for age, sex, diagnosis, and prosthesis brand.

Table 3. Cox relative revision risk (RR) estimates with revision for any reason as endpoint. Unadjusted and adjusted for age, sex, diagnosis, and prosthesis brand

Bone cement	Median follow-up, years	Maximum follow-up, years	No. revised	No. at risk, 6 years	Unadjusted		Adjusted
					Kaplan-Meier survival at 6 years (95% CI)	RR (95% CI)	RR (95% CI)	p-value
Palacos R + G	3.9	8.4	299	2,034	95.2 (94.6–95.7)	1 (ref)	1 (ref)	–
Palacos with gentamicin	2.9	9.0	259	821	94.9 (94.2–95.6)	1.00 (0.85–1.18)	0.98 (0.83–1.17)	0.9
Refobacin BCR	5.2	8.3	183	1,771	95.2 (94.5–95.9)	0.98 (0.82–1.18)	0.88 (0.73–1.06)	0.2
Optipac Refobacin BCR	2.2	6.0	120	^a	^b	0.96 (0.78–1.19)	0.84 (0.67–1.05)	0.1
Refobacin Palacos R	7.7	9.0	53	1,020	95.5 (94.3–96.7)	0.88 (0.66–1.18)	0.86 (0.64–1.16)	0.3

a Last revision at 4.5 years; at risk: 339.

b Last revision at 4.5 years; survival (95% CI): 95.3% (94.2–96.5).

Figure 4. Cox survival curves with cement product as stratification variable for TKAs with revision due to deep infection within one year postoperatively as endpoint. The curves were estimated with adjustment for age, sex, diagnosis, and prosthesis brand.

Table 4. Cox relative revision risk (RR) estimates with revision due to deep infection within 1 year postoperatively as endpoint. Adjusted for age, sex, diagnosis, and prosthesis brand

Bone cement	At risk, 1 year	No. revised	Adjusted RR (95% CI)	p-value
Palacos R + G	7,027	55	1 (ref)	–
Palacos with gentamicin	6,812	26	0.52 (0.32–0.84)	0.01
Refobacin BCR	4,220	27	0.92 (0.56–1.50)	0.7
Optipac Refobacin BCR	3,975	32	1.18 (0.73–1.91)	0.5
Refobacin Palacos R	1,190	7	0.87 (0.39–1.92)	0.7