Unicompartmental knee arthroplasty in patients aged less than 65

Figures & data

Table 1.  Number of UKAs and proportion of primary knee replacements per year in Sweden (1975–1997) and in Australia (1999–2007) for all ages

Year of procedure	Australia		Sweden
	N	% of primary knees	N	% of primary knees
1975–1997	a	a	21,152	33
1998	a	a	1,033	20
1999	24	5.2	842	18
2000	637	12	912	15
2001	2,312	14	942	15
2002	3,860	15	908	12
2003	4,102	15	982	12
2004	3,724	12	894	9.8
2005	3,875	12	928	9.5
2006	3,625	11	903	8.6
2007	3,448	9.7	720	7.0

^aPre-registry

Figure 1.  Number of UKA procedures for OA in Australia and Sweden from 2002 through 2007, by year of procedure and age.

Table 2.  The number and proportion of UKAs in Australia (1999–2007) and Sweden (1998–2007), by sex and age

Age	Australia				Sweden
	Females		Males		Females		Males
	N	%	N	%	N	%	N	%
< 55	2,023	57	1,504	43	657	63	393	37
55–64	3,998	48	4,298	52	1,767	55	1,433	45
65–74	3,718	46	4,393	54	1,574	54	1,348	46
≥ 75	2,603	49	2,769	52	972	60	648	40
Total	12,342	49	12,964	51	4,970	57	3,822	44

Table 3.  Number and percentage of UKA prostheses for OA (all ages) in Australia (1999–2007) and Sweden (1998–2007)

UKA prosthesis	N	%
Australia
Oxford 3	8,540	34
Repicci	2,357	9.3
Unix	1,895	7.5
Preservation-Fixed	1,888	7.5
M/G	1,884	7.4
Allegretto Uni	1,652	6.5
Genesis	1,574	6.2
GRU	1,366	5.4
ZUK	798	3.2
Endo-Model Sled	776	3.1
Total	22,730	90
Sweden
Link-Uni	3,790	43
MillerGalante-Uni	2,440	28
Oxford-Uni	1,299	15
Genesis	513	5.8
Total	8,042	91

Figure 2.  Cumulative revision rate of primary UKA for OA in Australia and Sweden, by age.

Table 4.  7-year cumulative revision rate (with 95% confidence interval) for primary UKA for OA, by sex and age

Age group	MalesCRR (%)(95% CI)	FemalesCRR (%)(95% CI)	TotalCRR (%)(95% CI)
< 55	19 (16–24)	19 (16–22)	19 (17–21)
55–64	12 (11–13)	13 (11–15)	13 (11–14)
65–74	7.4 (6.5–8.4)	9.7 (8.6–11)	8.6 (7.8–9.4)
≥ 75	6.0 (4.8–7.4)	5.6 (4.7–6.6)	5.7 (5.0–6.5)

Figure 3.  Cumulative revision rate of primary UKA in OA patients aged less than 65 years, by country. Shaded area: 95% CI.

Figure 4.  Cumulative revision rate of primary UKA in OA patients aged less than 65 years in Australia and Sweden, by sex. Shaded area: 95% CI.

Table 5.  Main reason for revision of primary UKA in OA patients less than 65 years old in Australia and Sweden

Revision diagnosis	Australia			Sweden
	N	% of revision	% of primary	N	% of revision	% of primary
Loosening/Lysis	506	54	4.3	142	39	3.3
Progression of disease	134	14	1.1	95	26	2.2
Pain	113	12	1.0
Infection	40	4.3	0.3	9	2.5	0.2
Bearing/Dislocation	26	2.8	0.2
Fracture	20	2.1	0.2	9	2.5	0.2
Wear tibial	19	2.0	0.2	13	3.6	0.3
Malalignment	17	1.8	0.1
Instability	9	1.0	0.1	14	3.8	0.3
Dislocation	9	1.0	0.1
Incorrect sizing	8	0.9	0.1
Patello femoral pain	6	0.6	0.1	11	3.0	0.3
Implant breakage (femoral/tibial)	9	0.6	0.1
Arthrofibrosis	4	0.4	0.0
Avascular necrosis	3	0.3	0.0
Synovitis	1	0.1	0.0
Other	12	1.3	0.1	69	19	1.6
Unknown				4	1.1	0.1
Total revision	936	100	7.9	366	100	8.6
Total primary	11,823			4,250