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Arthroplasty Revisited: Hip and Knee Revisions in Canada
Excerpts from the 2004 CJRR Analytical Bulletin
Sukanya Gopinath, Senior Analyst
Dereck Cyrus, Senior Analyst
Nicole de Guia, Consultant
Canadian Joint Replacement Registry
Canadian Institute for Health Information
Toronto, ON
In June 2004, the Canadian Joint Replacement Registry (CJRR) released an analytical bulletin entitled Revisions of Hip and Knee Replacements in Canada. This bulletin contained information on revisions to replacements by province, age and gender, associated length of stay, reasons for revision, components replaced, and also compared Canadian statistics with revisions reported by other international registries. Highlights of the bulletin are presented here.
The primary data source for this article is the Hospital Morbidity Database (HMDB), managed by the Canadian Institute for Health Information (CIHI). This database captures information on all admissions to acute care facilities in Canada. Quebec does not specifically report revisions in the Hospital Morbidity Database and hence revisions for this province were excluded. It is important to note that the revision rates reported in this article are cross-sectional and not longitudinal. Rates reported reflect the volume of revision surgeries as a proportion of all hip and knee replacement procedures, rather than the percent of primary hip and knee replacement patients who later required revision surgery. Provincial statistics are based on where the surgery was performed, rather than where the patient resided.
Primary and Revision Totals
Between April 1, 2001 and March 31, 2002, 3,789 revision procedures were performed in acute care facilities across Canada (Table 1), representing 9.4% of the 40,250 hip and knee replacements conducted during this period. Of these, 2,081 pertained to hip revisions representing an estimated 11.1% of all hip arthroplasty procedures and 1,708 were knee revisions, representing 7.9% of all knee arthroplasty procedures.
Table 1. Number of Hip and Knee Replacements
(Primary and Revision), Canada, HMDB 2001-2002
Replacements
(Primary/Revisions)
|
HMDB FY 2001-2002
|
Hips
|
Knees
|
Total2
|
Primary Replacements1
|
16,613
|
19,848
|
36,461
|
Revision Replacements
|
2,081
|
1,708
|
3,789
|
Total Primary and Revision Replacements
|
18,694
|
21,556
|
40,250
|
% Revisions
|
11.1%
|
7.9%
|
9.4%
|
1Counts include partial replacements.
2Counts from Quebec are excluded.
Source. Hospital Morbidity Database (HMDB), CIHI 2001-2002
Age and Gender Differences
While the average age of a patient undergoing a revision was the same for hip versus knee replacements (69 years), the average age of male patients (68 years) was slightly lower than female patients (70 years).
Provincial Differences
There was considerable variation among provinces in terms of the percentage of reported revisions in 2001-2002, measured as a proportion of all hip and knee replacement procedures performed in that province (Figure 1). Manitoba had the highest percentage of hip revisions (16.5%) followed by Nova Scotia (14.3%) and New Brunswick (13.9%). Ontario conducted the lowest percentage of hip revisions (10.2%). In the case of knee revisions, New Brunswick had the highest percentage of revisions (12.8%), followed by Nova Scotia (9.7%) and Manitoba (9.2%). Newfoundland had the lowest percentage of knee revisions among the provinces (3.9%).
Figure 1. Percent of Hip and Knee Revisions by Province, 2001-2002.
Length of Hospital Stay
On average, hip revision patients remained in hospital 14.4 days, compared to 9.5 days for knee revision patients (Figure 2). Considerable variation in length of stay was seen among the provinces. Patients from Newfoundland and Manitoba had the highest average lengths of stay for both hip (24.4 days and 17.5 days, respectively) and knee revisions (14.7 days and 14.0 days, respectively). Patients in Ontario had the shortest average lengths of stay for hip revisions (12.8 days), and patients in Saskatchewan had the shortest average length of stay for knee revisions (8.3 days).
Hip revision patients in Canada stayed an average of 4.1 days longer in hospital than primary hip replacement patients (14.4 days for a revision versus 10.3 days for a primary replacement). Similarly, knee revision patients averaged 2.5 days longer in hospital than their primary replacement counterparts (9.5 days for a revision versus 7.0 days for a primary replacement).
Length of stay in hospital for patients undergoing revisions was also found to be considerably different among women compared to men. Women undergoing a hip or knee revision arthroplasty remained in hospital longer than men undergoing the same procedure. Women undergoing a hip revision stayed an average of 15.5 days in hospital compared to 12.9 days for their male counterparts. Similarly, women undergoing a knee revision stayed, on average, 10.2 days in hospital compared to 8.6 days for men.
Figure 2. Average Length of Stay (Days) for Hip and Knee Revision Patients by Province, 2001- 2002.
International Comparisons
There is little variation in the proportion of primary versus revision procedures for hip and knee replacements performed in Canada, Sweden, Norway, Australia and New Zealand (Table 2). Though the total number of hip and knee procedures varies based on country size and geography, the proportion of revision and primary procedures performed was found to be similar across countries for both hip and knee surgeries. In Sweden, Norway and Australia, the revisions reported are longitudinal, i.e. patients are followed over time from previous primary procedure to monitor outcomes.
Table 2. International Comparison of Primary and Revision Procedures for Hip and Knee Replacements, 2001
Countries
|
Hip Replacements (Total and/or Partial)
|
Knee Replacements (Total and/or Partial)
|
Primary (counts)
|
% of Total
|
Revision
(counts)
|
% of Total
|
Total
|
Primary
(counts)
|
% of Total
|
Revision
(counts)
|
% of Total
|
Total
|
|
Canada1 (2001/
2002)
|
16,613
|
89%
|
2,081
|
11%
|
18,694
|
19,848
|
92%
|
1,708
|
8%
|
21,556
|
|
Sweden2
(2001)
|
|
|
|
|
|
920
|
89%
|
109
|
11%
|
1,029
|
|
Norway3
(2001)
|
6,150
|
87%
|
916
|
13%
|
7,066
|
2,235
|
92%
|
192
|
8%
|
2,427
|
|
Australia4
(2001/02)
|
22,979
|
86%
|
3,710
|
14%
|
26,689
|
23,786
|
91%
|
2,303
|
9%
|
26,089
|
|
New Zealand5
(2001)
|
4,880
|
87%
|
759
|
13%
|
5,639
|
3,041
|
92%
|
280
|
8%
|
3,321
|
|
|
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1 Hospital Morbidity Database, CIHI, 2001-2002. Counts for primary and revision hip and knee replacements pertaining to Quebec are excluded, as revisions are not reported by Quebec in this database.
2 The Swedish Knee Arthroplasty Register Annual Reports 2002, 2003 (computed from cumulative counts).
3 The Norwegian Arthroplasty Register, Norway, Annual Report 2003.
4 Australian Orthopaedic Association National Joint Replacement Registry. Annual Report. Adelaide: AOA; 2003.
5 New Zealand National Joint Register, New Zealand, January December 2001.
About CJRR
The CJRR is a joint effort between CIHI and the orthopaedic surgeons of Canada. This initiative was championed by CIHI and orthopaedic surgeons working under the auspices of the Canadian Orthopaedic Association and the Canadian Orthopaedic Foundation. To obtain the entire CJRR June 2004 analytical bulletin, visit www.cihi.ca/cjrr. If you are an orthopaedic surgeon and wish to participate in the CJRR, please contact
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