Existence of a neuropathic pain component in patients with osteoarthritis of the knee.
OBJECTIVE
Pain from osteoarthritis (OA) is generally classified as nociceptive (inflammatory). Animal models of knee OA have shown that sensory nerve fibers innervating the knee are significantly damaged with destruction of subchondral bone junction, and induce neuropathic pain (NP). Our objective was to examine NP in the knees of OA patients using painDETECT (an NP questionnaire) and to evaluate the relationship between NP, pain intensity, and stage of OA.


METHODS
Ninety-two knee OA patients were evaluated in this study. Pain scores using Visual Analogue Scales (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), painDETECT, duration of symptoms, severity of OA using the Kellgren-Lawrence (KL) system, and amount of joint fluid were evaluated and compared using a Spearman's correlation coefficient by rank test.


RESULTS
Our study identified at least 5.4% of our knee OA patients as likely to have NP and 15.2% as possibly having NP. The painDETECT score was significantly correlated with the VAS and WOMAC pain severity. Compared with the painDETECT score, there was a tendency for positive correlation with the KL grade, and tendency for negative correlation with the existence and amount of joint fluid, but these correlations were not significant.


CONCLUSIONS
PainDETECT scores classified 5.4% of pain from knee OA as NP. NP tended to be seen in patients with less joint fluid and increased KL grade, both of which corresponded to late stages of OA. It is important to consider the existence of NP in the treatment of knee OA pain.
Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. sohtori@faculty.chiba-u.jp
Seiji
S
Ohtori
Sumihisa
S
Orita
Masaomi
M
Yamashita
Tetsuhiro
T
Ishikawa
Toshinori
T
Ito
Tomonori
T
Shigemura
Hideki
H
Nishiyama
Shin
S
Konno
Hideyuki
H
Ohta
Masashi
M
Takaso
Gen
G
Inoue
Yawara
Y
Eguchi
Nobuyasu
N
Ochiai
Shunji
S
Kishida
Kazuki
K
Kuniyoshi
Yasuchika
Y
Aoki
Gen
G
Arai
Masayuki
M
Miyagi
Hiroto
H
Kamoda
Miyako
M
Suzkuki
Junichi
J
Nakamura
Takeo
T
Furuya
Gou
G
Kubota
Yoshihiro
Y
Sakuma
Yasuhiro
Y
Oikawa
Masahiko
M
Suzuki
Takahisa
T
Sasho
Koichi
K
Nakagawa
Tomoaki
T
Toyone
Kazuhisa
K
Takahashi
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007717:Knee / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology*