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, http://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.”

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.

5.2.2 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).

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

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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