Ac a O hopaedica 2016; 87 (1): 5–11 5
Changes in a es o a h oscopy due o degene a i e knee
disease and auma ic meniscal ea s in Finland and Sweden
Ville M MATTILA1,2, Raine SIHVONEN 3, Juha PALONEVA4, and Li FELLÄNDER-TSAI 2
1 Di ision o O hopedics and T auma ology, Depa men o T auma, Musculoskele al Su ge y and Rehabili a ion, Tampe e Uni e si y Hospi al, Tampe e,
Finland; 2 Depa men o Clinical Science, In e en ion and Technology, Ka olinska Ins i u e , Di ision o O hopedics and Bio echnology, Ka olinska
Ins i u e and Depa men o O hopedics a Ka olinska Uni e si y Hospi al Huddinge, S ockholm, Sweden; 3 Depa men o O hopedics, Ha anpää
Hospi al, Tampe e; 4Depa men o Su ge y, Cen al Finland Hospi al, Jy äskylä, Finland
Co espondence: [email p o ec ed]
Submi ed 2015-03-07. Accep ed 2015-05-26.
© 2016 The Au ho (s). Published by Taylo & F ancis on behal o he No dic O hopedic Fede a ion. This is an Open Access a icle dis ibu ed unde he e ms
o he C ea i e Commons A ibu ion-Non-Comme cial License (h ps://c ea i ecommons.o g/licenses/by-nc/3.0)
DOI 10.3109/17453674.2015.1066209
Backg ound and pu pose — Knee a h oscopy is commonly pe -
o med o ea degene a i e knee disease symp oms and au-
ma ic meniscal ea s. We e alua ed whe he he ecen high-qual-
i y andomized con ol ials no a o ing a h oscopic su ge y
o degene a i e knee disease a ec ed he p ocedu e incidence
and ends in Finland and Sweden.
Pa ien s and me hods — We conduc ed a bi-na ional egis y-
based s udy including all adul (aged ≥18 yea s) inpa ien and ou -
pa ien a h oscopic su ge ies pe o med o degene a i e knee
disease (os eoa h i is (OA) and degene a i e meniscal ea s) and
auma ic meniscal ea s in Finland be ween 1997 and 2012, and
in Sweden be ween 2001 and 2012.
Resul s — In Finland, he annual numbe o ope a ions was
16,389 in 1997, eached 20,432 in 2007, and declined o 15,018
in 2012. In Sweden, he numbe o ope a ions was 9,944 in 2001,
eached 11,711 in 2008, and declined o 8,114 in 2012. The knee
a h oscopy incidence o OA was 124 pe 105 pe son-yea s in
2012 in Finland and i was 51 in Sweden. The incidence o knee
a h oscopies o meniscal ea s coded as auma ic s eadily
inc eased in Finland om 64 pe 105 pe son-yea s in 1997 o 97
pe 105 pe son-yea s in 2012, bu no in Sweden.
In e p e a ion — The incidence o a h oscopies o degene a-
i e knee disease declined a e 2008 in bo h coun ies. Rema k-
ably, he incidence o a h oscopy o degene a i e knee disease
and auma ic meniscal ea s is 2 o 4 imes highe in Finland
han in Sweden. E icien implemen a ion o new high-quali y e i-
dence in clinical p ac ice could educe he numbe o ine ec i e
su ge ies.

Degene a i e knee disease p oduces a a ie y o symp oms,
clinical indings, and issue abno mali ies, e en ually lead-
ing o knee os eoa h i is (OA). Nonope a i e ea men o
degene a i e knee disease is ecommended in guidelines,
bu a h oscopy is widely used (Kim e al. 2011, Nelson e
al. 2014). A h oscopic ea men includes deb idemen
(la age, smoo hening, and emo al o loose a icula ca ilage
agmen s), ea men o ca ilage lesions, and esec ion o
meniscal lesions (Felson 2010). Meniscal epai is p e e ed
o acu e auma ic ea s o he meniscus (Sgaglione 2005).
Howe e , i is o en di icul o dis inguish be ween degen-
e a i e and auma ic meniscal ea s. In olde indi iduals and
in pa ien s wi h knee OA, meniscal ea s a e o en degene a-
i e and hei p e alence inc eases wi h age (Cu l e al. 1997,
Me cal and Ba e 2004, Englund e al. 2008). In younge
pa ien s, auma ic meniscal ea s usually esul om acu e
knee inju y and a e o en associa ed wi h ea s o he an e io
c ucia e ligamen (Poehling e al. 1990).
The p ac ice o knee a h oscopy is in u moil. In 2002, a
pi o al andomized and placebo- (su ge y) con olled ial
ound ha a h oscopic deb idemen o la age is no be e han
a sham p ocedu e o ea ing knee OA (Moseley e al. 2002).
This inding was la e co obo a ed by Ki kley e al. (2008).
This e idence led o ecommenda ions o a oid knee a h os-
copy p ocedu es o pa ien s wi h a p ima y diagnosis o knee
OA (Conaghan e al. 2008, Richmond e al. 2009, Zhang e al.
2010). The ecommenda ions, howe e , p o ided he op ion
o knee a h oscopy in pa ien s wi h signs and symp oms o a
o n meniscus (Conaghan e al. 2008, Richmond e al. 2009)
and o pa ien s wi h low-g ade OA (Zhang e al. 2010).
P e ious epo s ega ding he ends in a numbe o knee
a h oscopic p ocedu es indica e a educed incidence o
a h oscopies o knee OA, and a s eady inc ease in he numbe
o a h oscopic meniscus su ge ies (Hawke e al. 2008, Kim
e al. 2011, Ab ams e al. 2013). In he UK, he incidence o
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6 Ac a O hopaedica 2016; 87 (1): 5–11
a h oscopic meniscal esec ions mo e han doubled om
2000 o 2012 in pa ien s o e 60 yea s o age (Lazic e al.
2014). Simila ly, in Denma k he numbe o meniscal p oce-
du es in pa ien s aged 35 yea s o mo e inc eased du ing he
pe iod 2000–2011 (Tho lund e al. 2014).
In his bi-na ional egis y-based s udy in ol ing he en i e
popula ions o Finland and Sweden, we assessed he numbe s
and incidence ends o a h oscopic knee p ocedu es o degen-
e a i e knee disease and meniscal ea s in Finland (be ween
1997 and 2012) and in Sweden (be ween 2001 and 2012).
Pa ien s and me hods
We used he Finnish and Swedish Na ional Hospi al Discha ge
Regis e s (NHDRs) o e alua e he incidence o and ends in
a h oscopic su ge y o degene a i e knee disease and menis-
cal ea s. All pa ien s 18 yea s o age o olde in bo h NHDRs
we e included. In Finland, da a we e a ailable om Janua y 1,
1997 h ough Decembe 31, 2012, and in Sweden, da a we e
a ailable om Janua y 1, 2001 h ough Decembe 31, 2012.
The Finnish and Swedish NHDRs p o ide excellen da abases
o epidemiological s udies, as hey con ain da a on age, sex,
and domicile o he subjec ; leng h o hospi al s ay; p ima y
and seconda y diagnoses; and ope a ions pe o med du ing
he hospi al s ay. The da a collec ed by he NHDR a e man-
da o y o all hospi als o p o ide—including p i a e, public,
and o he ins i u ions— o bo h inpa ien and ou pa ien se -
ings. Al hough co e age and accu acy o bo h NHDRs is
good (Lud igsson e al. 2011, Sund 2012, Hu unen e al.
2014), an in e nal alidi y con ol o he da a e ealed ha 2
hospi als in S ockholm, Sweden had pe o med app oxima ely
1,800 knee a h oscopies annually o degene a i e knee dis-
ease o meniscal ea s in ecen yea s, whe eas he numbe had
doubled in 2012, aising suspicion o double-coding o p oce-
du es (Socials y elsen 2009, Socials y elsen 2014). Thus, due
o he po en ial p oblems wi h in e nal alidi y, we excluded
hese 2 hospi als in S ockholm om he analysis wi h ega d
o he whole s udy pe iod (2001—2012).
The main ou come a iable was he numbe o knee a h os-
copies pe o med o degene a i e knee disease (including
OA and degene a i e meniscal ea s) and auma ic meniscal
ea s (Table 1). Fo diagnoses, he ICD-10 coding sys em was
used, and o p ocedu al coding, we used he na ional NCSP
p ocedu al codes main ained by NOMESCO (Socials y elsen
2004, Leh onen e al. THL 2013). These coding sys ems allow
physicians o se mul iple diagnoses. We ca ego ized knee
a h oscopies based on he diagnosis and p ocedu al codes
as ollows: (a) Os eoa h i is, (b) Degene a i e meniscal ea ,
(c) T auma ic meniscal ea unde going deb idemen / esec-
ion, and (d) T auma ic meniscal ea unde going epai (Table
1). The code M23* (meniscal de angemen due o old ea o
inju y o o he meniscal de angemen s) was used o degene -
a i e meniscal ea s, and he code S83.2 (acu e meniscal ea )
was used o auma ic ea s. In cases o mul iple knee diag-
noses o he same su gical p ocedu e (e.g. a i s diagnosis o
M23* and a second o M17*, o a i s diagnosis o M23* and
a second o S83.2), he p ocedu e was ca ego ized acco ding
o he mo e degene a i e diagnosis (e.g. M17 and M23 was
de ined as M17, and M23 and S83 as M23).
Table 1. ICD-10 diagnosis and NCSP p ocedu al codes included in Finland and in Sweden
ICD-10 diagnoses P ocedu al codes in Finnish coding sys em P ocedu al codes in Swedish coding sys em
(Leh onen e al. THL 2013) (Socials y elsen 2004)
Os eoa h i is
M17.0 P ima y gona h osis, bila e al NGA30 A h oscopic explo a ion o knee join NGA11 A h oscopic explo a ion o knee join
M17.1 Gona h osis, bila e al NGD05 A h oscopic pa ial esec ion o menisci NGD11 A h oscopic pa ial esec ion o menisci
M17.3 O he pos - auma ic gona h osis NGF25 A h oscopic deb idemen o knee join NGF31 A h oscopic deb idemen o knee join
M17.9 Gona h osis, unspeci ied NGF35 A h oscopic pa ial excision o join ca ilage NGF91 Pa ial excision o join ca ilage o knee
M22.4 Chond omalacia pa ellae o knee
Degene a i e meniscal ea
M23.2 De angemen o meniscus due o NGA30 A h oscopic explo a ion o knee join NGA11 A h oscopic explo a ion o knee join
old ea o inju y
M23.3 O he meniscal de angemen s NGD05 A h oscopic pa ial esec ion o menisci NGD11 A h oscopic pa ial esec ion o menisci
M23.4 Loose body in knee NGF25 A h oscopic deb idemen o knee join NGF31 A h oscopic deb idemen o knee join
M23.8 O he in e nal de angemen s o knee NGF35 A h oscopic pa ial excision o join ca ilage NGF91 Pa ial excision o join ca ilage o knee
M23.9 In e nal de angemen o knee, o knee
unspeci ied
T auma ic meniscal ea , deb idemen
S83.2 Tea o meniscus, cu en NGA30 A h oscopic explo a ion o knee join NGA11 A h oscopic explo a ion o knee join
NGD05 A h oscopic pa ial esec ion o menisci NGD11 A h oscopic pa ial esec ion o menisci
NGF25 A h oscopic deb idemen o knee join NGF31 A h oscopic deb idemen o knee join
NGF35 A h oscopic pa ial excision o join ca ilage NGF91 Pa ial excision o join ca ilage o knee
o knee
T auma ic meniscal ea , epai
S83.2 Tea o meniscus, cu en NDG25 e-inse ion o meniscus NGD21 e-inse ion o meniscus
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Ac a O hopaedica 2016; 87 (1): 5–11 7
S a is ics
To compu e he incidence o knee a h oscopy, he age- and
sex-speci ic annual mid-popula ion was ob ained om he
Finnish and Swedish O icial S a is ics, which yield da a om
an elec onic na ional popula ion egis y (O icial S a is ics o
Finland 2015, S a is ics Sweden 2015). The incidence o knee
a h oscopy (pe 105 pe son-yea s) was based on he esul s o
he en i e adul popula ion (≥18 yea s) o Finland and Sweden
a he han coho - o sample-based es ima es, and he e o e
con idence in e als we e no calcula ed. S a is ical analysis
was pe o med using SPSS e sion 21.0.
E hics
We ob ained he app o al o he Ins i u ional Re iew Boa ds
o Finland (en y no. THL 89/5.0500/2012) and Sweden (The
Regional E hics Commi ee o S ockholm, en y no. 2013/
5:6).
Resul s
Du ing he s udy pe iod in Finland, om 1997 h ough 2012, a
o al o 287,225 knee a h oscopies o ea degene a i e knee
disease (n = 233,375) o auma ic meniscal ea s (n = 53,850)
we e iden i ied in he adul popula ion (4.0–4.3 million). The
o al numbe o knee a h oscopies o degene a i e knee dis-
ease o auma ic meniscal ea s in 1997 was 16,389, and in
2007 he numbe peaked o 20,432. The ea e , he numbe o
a h oscopies declined and was 15,018 in 2012. The mean age
o male and emale pa ien s was 47 and 52 yea s, and i did
no change ma kedly du ing he s udy pe iod. In Sweden wi h
an adul popula ion o 7.1–7.6 million, he o al numbe o
a h oscopies pe o med o degene a i e knee disease o au-
ma ic meniscal ea s om 2001 h ough 2012 was 115,907
(100,469 and 15,438, espec i ely). The numbe o ope a ions
in 2001 was 9,944, and he highes numbe o a h oscopies
(11,711) was pe o med in 2008. The numbe o a h oscopies
hen declined o 8,114 in 2012 (Figu e, Tables 2 and 3). In
gene al, he incidence a es o knee a h oscopy we e ma k-
edly lowe in Sweden han in Finland.
I Finland, he incidence o knee a h oscopy o OA inc eased
o 240 pe 105 pe son-yea s in 2002 and hen dec eased by
48% o 124 pe 105 pe son-yea s in 2012. In Sweden, he
incidence o knee a h oscopy o OA inc eased o 87 pe 105
pe son-yea s in 2008, and hen dec eased by 41% o 51 pe
105 pe son-yea s in 2012. The mean age o OA pa ien s was
54 yea s in Finland and 52 yea s in Sweden.
The incidence o a h oscopy o degene a i e meniscal ea s
in Finland inc eased sligh ly om 1997 o 2007 (incidence
167 pe 105 pe son-yea s in 2007) and hen declined o 125
pe 105 pe son-yea s in 2012. The incidence o a h oscopic
deb idemen o auma ic meniscal ea s inc eased by 55%
du ing he s udy pe iod om 63 pe 105 in 1997 o 97 pe 105
in 2012. In bo h g oups o meniscal ea s in Finland, he mean
age inc eased sligh ly du ing he s udy pe iod om 49 yea s in
1997 o 52 yea s in 2012 o hose wi h degene a i e meniscal
ea s and om 42 yea s in 1997 o 46 yea s in 2012 o hose
wi h auma ic meniscal ea s unde going deb idemen .
In Sweden, he incidence o a h oscopy o degene a i e
meniscal ea s emained p ac ically unal e ed (39 o 46 pe 105
pe son-yea s) du ing he s udy pe iod, excep in 2008 when
he incidence was 59 pe 105 pe son-yea s. The mean age o
hese pa ien s did no change ei he (46 yea s in 2001 and 47
yea s in 2012). The incidence o auma ic ea s unde going
deb idemen dec eased du ing he s udy pe iod om 27 pe
105 pe son-yea s in 2001 o 13 pe 105 pe son-yea s in 2012.
Unlike in Finland, he mean age o pa ien s wi h auma ic
ea s unde going deb idemen dec eased in Sweden du ing he
s udy pe iod om 39 yea s in 2001 o 35 yea s in 2012.
The incidence o meniscal epai o auma ic meniscal
ea s emained low and unal e ed du ing he s udy pe iod in
bo h coun ies, anging om 2.2 o 1.3 pe 105 pe son-yea s in
Finland and om 0.4 o 0.8 pe 105 pe son-yea s in Sweden.
The mean age o pa ien s unde going meniscal epai emained
he same du ing he s udy pe iod—38 yea s in Finland and 30
yea s in Sweden.
Incidence o knee a h oscopy o os eo-
a h i is, degene a i e meniscal ea s, and
auma ic meniscal ea s in Finland om
1997 o 2012 (le panel) and in Sweden
om 2001 o 2012 ( igh panel), pe 105
pe son-yea s. 2 hospi als in Sweden we e
excluded due o suspec ed double-coding.
1997 2000 2003 2006 2009
2012
Yea
0
50
100
150
200
250
300
Incidence pe 10
5
pe son-yea s – Sweden
Os eoa h i is
Degene a i e ea
T auma ic ea
1997 2000 2003 2006 2009
2012
Yea
0
50
100
150
200
250
300
Incidence pe 10
5
pe son-yea s – Finland
Os eoa h i is
Degene a i e ea
T auma ic ea
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8 Ac a O hopaedica 2016; 87 (1): 5–11
Discussion
The 2 main indings o ou bi-na ionwide s udy conduc ed in
Finland and Sweden we e ha he incidence o a h oscopy
o knee OA has dec eased in bo h coun ies (in Finland since
2006 and in Sweden since 2008), and ha he o e all inci-
dence o knee a h oscopy due o degene a i e knee disease
and auma ic meniscal ea s was almos 4 imes highe in Fin-
land han in Sweden. In Finland, he incidence o a h oscopy
o degene a i e meniscal ea s has dec eased since 2007, bu
he e has been a simul aneous inc ease in deb idemen su -
ge y o meniscal lesions coded as auma ic meniscal ea s.
Addi ionally, he mean age o hese pa ien s has inc eased. In
Sweden, he incidence o deb idemen a h oscopy o bo h
degene a i e meniscal inju ies and inju ies coded as auma ic
has been p ac ically unchanged and in con as o Finland, he
mean age o pa ien s wi h auma ic ea has dec eased.
P e ious s udies ha e ound simila changes in he inci-
dence o knee a h oscopy. A 49% o e all inc ease in knee
a h oscopies in he USA be ween 1996 and 2006 has been
epo ed (Kim e al. 2011); he incidence o a h oscopy o
OA dec eased while he incidence o meniscal ea s inc eased.
Po s e al. (2012) epo ed a dec ease in a h oscopy o OA
acco ding o he Ame ican Boa d Exam when compa ing he
esul s in 1999 wi h hose in 2009. A epo om England and
On a io, Canada, showed ha he numbe o knee a h os-
copies o OA had dec eased om 1993 o 2004, while he
numbe o knee a h oscopies o meniscal ea s had inc eased
Table 2. Incidence o knee a h oscopy (pe 105 pe son-yea s) and mean age o pa ien s o os eoa h i-
is, degene a i e meniscal ea , and auma ic meniscal ea (deb idemen and epai ) in Finland om
1997 o 2012
T auma ic meniscus T auma ic meniscus
Yea Os eoa h i is Degene a i e meniscus (deb idemen ) ( epai )
Incidence Mean age Incidence Mean age Incidence Mean age Incidence Mean age
1997 214 52 134 49 63 42 1.2 44
1998 222 53 136 50 64 42 1.4 40
1999 235 53 139 50 63 43 1.9 39
2000 244 53 154 51 65 43 2.0 43
2001 218 54 142 51 64 43 1.8 37
2002 240 54 153 51 65 43 1.9 38
2003 221 54 144 52 71 44 1.6 39
2004 208 54 140 52 76 44 1.7 41
2005 225 54 151 52 90 45 1.9 39
2006 233 55 164 53 87 45 2.0 39
2007 224 55 167 53 95 45 1.9 42
2008 210 55 163 53 91 45 1.3 38
2009 187 55 155 53 85 45 1.5 40
2010 155 54 138 52 92 46 1.7 38
2011 145 54 138 53 101 46 2.2 37
2012 124 54 125 52 97 46 2.1 40
Table 3. Incidence o knee a h oscopy (pe 105 pe son-yea s) and mean age o pa ien s o os eoa h i-
is, degene a i e meniscal ea , and auma ic meniscal ea (deb idemen and epai ) in Sweden om
2001 o 2012
T auma ic meniscus T auma ic meniscus
Yea Os eoa h i is Degene a i e meniscus (deb idemen ) ( epai )
Incidence Mean age Incidence Mean age Incidence Mean age Incidence Mean age
2001 76 52 40 46 27 39 0.4 28
2002 71 52 39 47 22 39 0.4 30
2003 71 51 41 46 21 38 0.4 31
2004 69 52 43 46 20 38 0.4 31
2005 72 52 42 46 20 38 0.8 28
2006 76 53 44 47 16 38 0.7 29
2007 77 53 45 47 16 38 0.5 31
2008 87 53 59 48 13 37 0.5 31
2009 78 53 47 47 13 36 0.7 30
2010 66 52 46 46 13 36 0.8 30
2011 59 52 46 46 14 35 0.8 29
2012 51 53 42 47 13 35 0.7 30
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Ac a O hopaedica 2016; 87 (1): 5–11 9
(Hawke e al. 2008). This change in p ac ice was e iden a e
he publica ion o highly ci ed a icles demons a ing a lack o
e icacy o knee a h oscopy in OA (Moseley e al. 2002, Ki k-
ley e al. 2008). Acco dingly, he cu en ea men guidelines
s and agains knee a h oscopy o he ea men o es ablished
OA (Zhang e al. 2010, B own 2013). Scien i ic e idence
demons a ing he lack o e icacy o a h oscopic ea men
o knee OA may also be he main cause o he decline in su -
ge y a es in Finland and Sweden.
Al hough he incidence o knee a h oscopy o OA has
dec eased wo ldwide, he incidence o a h oscopy o menis-
cal ea s has inc eased. Mos ecen ly, Tho lund e al. (2014)
om Denma k epo ed ha he incidence o meniscus su ge y
had doubled om 2000 o 2011 ( he annual incidence inc eased
om 164 o 312 pe 105 pe son-yea s). Fu he mo e, in hei
o he s udy he inc ease in incidence was seen especially in he
p i a e sec o (Ha e e al. 2015). In addi ion, qui e ema kably,
he incidence inc eased 3- old in pa ien s o e 55 yea s o age
(Tho lund e al. 2014). These indings a e consis en wi h ou s,
as he da a we e ex ac ed om a Na ional Pa ien Regis e
in a Scandina ian coun y simila o hose in he cu en bi-
na ional s udy. Mo eo e , Lazic e al. (2014) epo ed a simila
inc ease in meniscus su ge y o pa ien s o e 65 yea s o age
in he UK be ween 2000 and 2012. In he p esen s udy, he
incidence o su ge y o degene a i e meniscal ea s inc eased
in Finland om 1997 o 2007, bu no in Sweden. Al hough he
incidence in Finland has declined since 2007, he incidence o
knee a h oscopy o degene a i e meniscal ea s was s ill 3
imes highe han ha in Sweden in 2012 and he pa ien s we e
ma kedly olde in Finland han in Sweden.
The e is no clea explana ion o he di e ence in he inci-
dence o knee a h oscopy be ween Finland and Sweden. I is
no likely ha he di e ence in hese a he simila Scandi-
na ian coun ies could be ully explained by a di e en inci-
dence o knee degene a ion o auma. Cul u al issues may
also play a ole. Geog aphical a ia ions in su gical p oce-
du es esul mainly om di e ences in physician belie s abou
he indica ions o su ge y, and he ex en o which pa ien
p e e ences a e inco po a ed in o ea men decisions, while a
smalle deg ee o a ia ion in egional su ge y a es is due o
di e ences in illness bu den, diagnos ic p ac ices, and pa ien
a i udes (Bi kmeye e al. 2013, Ha e e al. 2015). Financial
incen i es also in luence he p ac ice pa e ns o physicians
(Mi chell 2010, Ha e e al. 2015). In addi ion, he numbe o
knee MRIs and knee a h oscopies pe o med appea s o be
co ela ed (Ha e e al. 2015). A ecen Danish s udy e ealed
ha he incidence o meniscus su ge y in Denma k is wice
as high as ha in Finland, and 6 imes highe han ha in
Sweden (Tho lund e al. 2014). The g ea di e ences in he
numbe s o a h oscopic deb idemen p ocedu es pe o med
in hese Scandina ian coun ies can be compa ed o he a ia-
ions in he incidence a es o knee a h oplas y. A ecen s udy
showed ha he incidence o p ima y o al knee eplacemen s
was 180 pe 105 pe son-yea s in Finland, 110 pe 105 pe son-
yea s in Sweden, and 140 pe 105 pe son-yea s in Denma k
(Ku z e al. 2011).
While he incidence o a h oscopy o degene a i e meniscal
ea s began o decline in Finland in 2007, he e was an inc ease
in he incidence o a h oscopy o meniscal ea s, coded as au-
ma ic bu unde going deb idemen . I is no ewo hy ha 44% o
all meniscal ea s we e coded as auma ic in Finland, as com-
pa ed o 24% in Sweden. In addi ion o he abo e-men ioned
easons o he di e en incidences o p ocedu es be ween
hese coun ies, he e may be di e ences in coding. A change
in coding o meniscal ea s may ha e occu ed in Finland,
because he mean age o pa ien s wi h meniscal ea s coded as
auma ic inc eased om 42 o 46 yea s. The e was no change
in ei he he incidence o he mean age, howe e , in Sweden.
A change in coding was pu o wa d o explain he inc ease in
meniscus su ge y in he USA be ween 1996 and 2006 (Kim e
al. 2011). Since 2004, Medica e has no paid o knee a h os-
copy pe o med o ea OA. Thus, o insu ance au ho iza ion,
many cases ha would ha e had a diagnos ic code o knee OA
may ha e been coded mo e ecen ly as meniscal ea s because
many knees wi h OA also show degene a i e meniscal ea s
(Englund e al. 2008, Kim e al. 2011). In Finland, pa o hese
p ocedu es a e inanced by insu ance companies, and ea ed in
p i a e hospi als, bu only i he ea is coded as auma ic. This
may cause o hopedic su geons in Finland o mo e equen ly
code meniscal ea s as auma ic a he han degene a i e. Di -
e en ia ing whe he a ea is auma ic o non- auma ic (degen-
e a i e) is o en clinically di icul , and he e may be a ia ions
be ween su geons and pa ien s ega ding in e p e a ion o he
e iology o he knee complain s. In addi ion, some pa ien s wi h
auma ic meniscal ea s could s ill seek medical ad ice a e a
pe iod o nonope a i e ea men , leading o a ea being coded
old (degene a i e). Also, some pa ien s wi h degene a i e ea s
ha e an acu e/sudden onse o symp oms wi h o wi hou a clea
knee inju y, and hese a e he e o e coded as auma ic (D osos
and Pozo 2004). Based on he cu en li e a u e, only 5–15%
o all ea ed meniscal ea s a e auma ic (Me cal and Ba -
e 2004, Ch is o o akis e al. 2005, Camanho e al. 2006), and
acco ding o a epo om he USA, 75% o pa ien s unde go-
ing meniscus epai a e unde 35 yea s o age (Ab ams e al.
2013). The incidence o meniscus epai s in ou s udy emained
low and unchanged du ing he s udy pe iod in bo h Finland and
Sweden. These ac s a gue agains a ue change in he inci-
dence o auma ic meniscal ea s—and a he o a change in
coding.
One s eng h o ou s udy is ha he esul s e lec ac ual
ea men policies and p ac ices o Finnish and Swedish o ho-
pedic su geons, and ha we used ue popula ion-based bi-
na ionwide da a. The co e age o he s udy can be conside ed
o be excellen , as medical ea men is equally a ailable o
e e yone in Finland and Sweden. The NHDRs used in Finland
and Sweden ha e excellen co e age and accu acy (Ma ila
e al. 2008, Lud igsson e al. 2011). Thus, we eel ha he
declining end in he p opo ion o ope a i e ea men s o
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10 Ac a O hopaedica 2016; 87 (1): 5–11
degene a i e knee disease ep esen he eal cu en opinion o
Finnish and Swedish physicians ea ing hese diso de s.
A limi a ion o ou s udy was ha 2 la ge hospi als in Sweden
had o be excluded om he analysis due o suspicion o double-
coding o ope a ions in 2012 in he SNHDR (Socials y elsen
2009, Socials y elsen 2014). We excluded hese hospi als o
he en i e s udy pe iod be ween 2001 and 2012, so ou esul s
may unde es ima e he eal incidence o knee a h oscopy in
Sweden by abou 15%. In addi ion, al hough ou decision o
di e en ia e he incidence numbe s as hose wi h knee OA,
hose wi h degene a i e meniscal ea s, hose wi h auma ic
ea s wi h deb idemen , and hose wi h auma ic ea s wi h
epai is consis en wi h clinical p ac ice; i may no e lec he
eali y behind he egis y da a, as i is no possible o ha e
in o ma ion on mo e de ailed a h oscopic indings o indi-
idual pa ien his o y. Besides, i is o en di icul o make a
diagnosis; he coding may also be in luenced by o he ac o s.
As discussed abo e, he e a e ac o s ha a e no dependen on
he ue na u e o he disease—such as habi s, cul u al consid-
e a ions, and insu ance policies— ha could a ec diagnos ic
coding and he ca ego iza ion used in his s udy. Indeed, ou
esul s sugges ha he e is a di e ence in coding be ween he
2 coun ies and ha he coding may ha e changed, pa icula ly
o meniscus ea s in Finland. Howe e , he mean ages and he
ac ual su gical p ocedu e gi e us a eliable clue o he na u e
o he disease. In ha ein, ou esul s a e mo e accu a e han
using he diagnosis code alone and sugges ha he as majo -
i y o pa ien s unde going meniscus su ge y ha e degene a-
i e—no auma ic—pa hology o he knee.
In conclusion, he incidence o a h oscopy o knee OA
declined simila ly du ing he s udy pe iod in Finland and
Sweden. In Finland, bu no in Sweden, he incidence o menis-
cus su ge y inc eased du ing he same pe iod. Fu he mo e, in
Finland a subs an ial p opo ion o meniscal ea s we e coded
as auma ic, a p ac ice ha is no suppo ed by he mean age
o he pa ien s o he su gical p ocedu es. We a e cu en ly
wi nessing a no able shi in he indica ions o knee a h os-
copy. 7 high-quali y andomized con olled ials assessing he
bene i o a h oscopic pa ial meniscec omy o pa ien s wi h
degene a i e meniscal ea s we e ecen ly published (Øs e ås
e al. 2012, He lin e al. 2013, Ka z e al. 2013, Sih onen e
al. 2013, Yim e al. 2013, Gau in e al. 2014, S ens ud e al.
2015). Only 1 o hese ials (Gau in e al. 2014) p o ided
any suppo o su ge y o he degene a i e knee. Implemen-
a ion o e idence akes se e al yea s be o e i is de ec ed in
na ionwide egis y s udies. As we ha e da a ega ding he
incidence o knee a h oscopy un il 2012, we could no de ec
possible changes in he numbe o a h oscopies pe o med o
degene a i e knee disease—namely degene a i e meniscus—
a e he la es e idence was published. The na ional a ia ions
in he su gical ends in degene a i e knee disease be ween
Finland and Sweden a e ema kable. Fu he in es iga ion is
needed o de e mine he easons o hese ends, such as di -
e ences in eimbu semen .
VM and JP we e esponsible o acquisi ion o da a, and o analysis and
in e p e a ion o da a. VM, RS, and LT we e esponsible o he s udy design.
VM and RS w o e he i s d a o he manusc ip .
No compe ing in e es s decla ed. The s udy did no ecei e any ex e nal und-
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