5 The Norwegian Arthroplasty Register



Ynvar Krukhaug


Abstract


The Norwegian Arthroplasty Register (NAR) is a nationwide register that receives information on primary and revision joint replacements performed in Norway.


From 1994 to 2018, 300 primary total wrist replacements were performed. The survival of the total wrist arthroplasties in the NAR is similar to other studies of wrist arthroplasties, but not as good as most total knee and hip arthroplasties. The annual number of total wrist replacements changed over time. The number of arthroplasties for inflammatory arthritis reduced (p < 0.001), but operations for osteoarthritis increased (p < 0.001).


From 1994 to 2011, 515 primary thumb CMC joint arthroplasties were registered in 432 patients. The overall 5-year and 10-year survivals were 91% and 90%, respectively. There were no statistically significant differences between the implant brands (p = 0.60). The annual number of arthroplasties performed due to IA decreased (p = 0.003), whereas the number for OA increased (p < 0.001) during the period.


From 1994 to 2018, 3786 primary MCP joint arthroplasties were registered. During the period, 768 prostheses were revised. The annual number of primary prosthesis has decreased over the last 20 years.


From 1994 through 2018, 105 primary PIP arthroplasties were registered. Sixteen (13%) have been revised. The annual number of primary prosthesis in PIP has remained constant over the last 20 years.




5 The Norwegian Arthroplasty Register



5.1 Introduction


The Norwegian Arthroplasty Register (NAR) is a nationwide register that receives information on primary and revision joint replacements performed in Norway.


The NAR started to collect data on total hip replacements in 1987. In 1994, this register was extended to include all artificial joints. 1 Individual reports are received from all seven hospitals that perform total wrist replacements in the country (population: 5.3 million at January 1, 2019).


The completeness of registration in the NAR was recently evaluated by comparing it to the mandatory reporting of administrative data to the Norwegian Patient Register (NPR); it was found to be 97% for hip replacements, 97% for knee replacements, 94% for all primary ankle replacements, and 86% for wrist replacements (The annual report from NAR, nrlweb.ihelse.net/eng/Rapporter/Report2018_english.pdf).


One explanation for the under-reporting could be that relative to the hip and knee, few wrist replacements are performed, and for this reason reporting to the Arthroplasty Register is not so well established among wrist surgeons.


The magnitude of under-reporting is unclear, however, as the NBD code group (except for NBD 8) of the NOMESCO 2006 coding system, which is used by the hospitals in their reports to the NPR, does not require it to be specified whether the prosthesis has been inserted in the radiocarpal joint or in other joints in the carpus. Also, the code NBD 99 applies to any prosthesis operation in the wrist or hand. Thus, the NPR data on wrist implants most probably also include data from implants in joints other than the radiocarpal joint. 2 We have no reason to believe that there is any systematic under-reporting to the NAR.



5.2 Wrist Replacements


From 1994 to 2018, 300 primary total wrist replacements were performed (Table 5.1). Three types of wrist prostheses were used: “Biax,” “Motec Wrist,” and “ReMotion Wrist.”







































































Table 5.1 Demography
Type of prosthesis Number of primary prostheses Percentage of women Mean age [range] years Cause: non-inflammatory arthritis (numbers) Cause: inflammatory arthritis (numbers) Number of hospitals Mean number of operations per hospital [range] Number of revisions (%) Median follow-up (y)
Biax 90 89% 57 [28–77] 6 84 5 18 [1–46] 21 15.2
ReMotion 56 43% 59 [20–79] 53 3 4 14 [3–27] 7 4.3
Motec 154 47% 55[17–79] 111 43 5 31 [4–94] 33 9.0
Total 300 59% 56 [17–85] 170 130 9 21 [1–94] 61 9.0

The diagnoses were grouped into “inflammatory arthritis” (IA) (n = 130) comprising rheumatoid arthritis and psoriatic arthritis, and into “noninflammatory arthritis” (NIA) (n = 170) comprising primary osteoarthritis (OA), postfracture disorders, ligament injuries, and joint destruction after infection.



5.2.1 Method


The NAR has registered wrist replacements since 1994. From 1994 to 2018, 300 patients had 300 primary wrist replacements (90 Biax prostheses of which 80 were cementless, 154 cementless Motec, and 56 ReMotion arthroplasties). Prostheses survival was analyzed using Cox regression analyses. The three implant designs were compared and time trends were analyzed.



5.2.2 Results


The annual number of total wrist replacements changed over time. The number of arthroplasties for IA reduced (p < 0.001), but operations for NIA increased (p < 0.001). These findings are consistent with a general trend for arthroplasty of other joints. 3 , 4 , 5 , 6 , 7


The survival of the total wrist arthroplasties in the NAR is similar to other studies of wrist arthroplasties, but not as good as most total knee and hip arthroplasties (Table 5.1 and Table 5.2, and Fig. 5.1).

Fig. 5.1 Survival (Kaplan–Meier) with confidence interval (95% CI) in red. All implants (a), Biax (b), Motec (c), ReMotion (d).






































































Proximal component loosening Distal component loosening Table 5.2 Reasons for revision (more than one reason could be given)
Brand Biax ReMotion Motec Total
Proximal component loosening 3 1 2 6
Distal component loosening 9 3 14 26
Dislocation 2 2
Instability 4 3
Axis problems 7 1 4 12
Deep infection 1 2 5 8
Pain 8 13 21
Wear of liner 3 3
Total number of revisions 21 7 33 61


5.3 CMC IA Replacements


The NAR has registered thumb carpometacarpal (CMC) joint arthroplasties since 1994.


From 1994 to 2011, 515 primary thumb CMC joint arthroplasties were registered in 432 patients. Thirty-six cases were excluded from the analysis; 12 because they had been operated on with rarer implants (Custom made in 5 and Avanta in 7), 16 due to missing information about implant brand, and 8 due to missing (5) or rare (3) diagnoses.


Four different brands of CMC implants were included in the analysis: “Silastic Trapezium” (Swanson Silastic), “Swanson Titanium Basal” (Swanson Titanium), “Elektra,” and “Motec.”


The patient diagnoses were stratified in two groups: “inflammatory arthritis” (IA) (108) and “osteoarthritis” (OA) (371). In the IA group 99 cases had rheumatoid arthritis, 8 had psoriatic arthritis, and 1 had lupus.



5.3.1 Results


The rate of thumb CMC joint arthroplasties did not change during the study period (p = 0.55) (Fig. 5.2). The number of arthroplasties performed due to IA decreased (p = 0.003), whereas the number for OA increased (p < 0.001). 6

Fig. 5.2 Kaplan–Meier survival curves.


Type of Prosthesis

The Swanson Silastic and Titanium implants were used in both diagnostic groups.


The Motec and the Elektra implants were only used in patients with OA (Table 5.3). The median follow-up time was longer for the Swanson Silastic (7.9 years) and the Swanson Titanium (11.7 years) than for the Elektra (2.0 years) and Motec (1.9 years) implants (p < 0.001). The median follow-up for all prostheses as a group was 7.4 years.


















































































Table 5.3 Demography
Prosthesis Number of primary prostheses Percentage of women Mean age [range] years Osteoarthritis (OA) Inflammatory arthritis (IA) Number of hospitals Mean number of operations per hospital [range] Number of revisions Median follow-up (y)
Silastic Trapezium 326 89% 64 [21–86] 239 97 14 23 [2–185] 33 7.9
Swanson Titanium Basal 71 82% 63 [38–82] 60 11 4 18 [1–52] 4 11.7
Elektra 29 72% 62 [50–72] 29 0 1 29 [29–29] 2 2.0
Motec 53 60% 63 [51–85] 53 0 3 18 [4–38] 3 1.9
Total 479 84% 64 [21–86] 371 108 16 30 [1–202] 42 7.4

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May 4, 2022 | Posted by in ORTHOPEDIC | Comments Off on 5 The Norwegian Arthroplasty Register
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