Abstract
Objectives:
Knee viscosupplementation yields variable results for osteoarthritis. Establishing patient and treatment factors that predict a favorable response to intra-articular hyaluronic acid (HA) treatment will better guide patient and treatment selection.
Methods:
This prospective study evaluated patients presenting with Kellgren-Lawrence grade 1-3 painful, primary knee osteoarthritis. The primary outcome measures were the Western Ontario and McMaster Universities Arthritis Index/ Knee Injury and Osteoarthritis Outcome Score (WOMAC/KOOS) and a standardized visual analog scale (VAS). Surveys were completed at the first and subsequent injections, then at three months post-treatment. Response to treatment was defined according to the Osteoarthritis Research Society International 2004 criteria.
Results:
We enrolled 135 patients, 102 remained for final analysis. Fifty-seven percent of patients had a positive response to treatment. Factors related to a positive response included those with grade 1 or 2 osteoarthritis (RR=2.17; 95%CI, 1.40-3.37), and those who showed improvement after the first injection (RR=2.22; 95%CI, 1.49-3.31). Seventy-eight percent of people who responded to the first injection had a positive response at follow-up. In multi-variable analysis, those aged 60 or older responded more positively with grade 2 osteoarthritis than those less than 60 years (RR=1.98; 95%CI, 1.18-3.21). Gender, race, BMI, smoking status, HA brand, and initial VAS and KOOS scores were not significant predictors of success in either independent or multivariable analysis.
Conclusion:
Patients with mild to moderate osteoarthritis (grades 1 and 2), and those who responded positively to the first injection were two times more likely to respond positively to the injection series than those with grade 3 osteoarthritis, or those who did not respond initially. Patients aged 60 or older are twice as likely to respond than those less than 60 years for grade 2 osteoarthritis. Judicious patient selection and counseling may improve outcomes associated with intra-articular HA injections.
Characteristics of patients according to successful treatment with hyaluronic acid. T-test probabilities are provided. Data are given as mean and standard or frequency and percent, as appropriate.
Positive Response
No Response
N=58 (57%)
N=44 (43%)
P-value
Age
61 (9.4)
59 (10.3)
0.436
Sex
Male
16 (55)
13 (45)
0.830
Female
42 (58)
31 (42)
BMI
33.2(6.2)
33.2 (8.4)
0.962
Smoking Status
Non-smoker
51 (57)
39 (43)
0.914
Smoker
7 (58)
5 (42)
Race
White
48 (58)
35 (42)
Black
10 (53)
9 (47)
0.683
OA Grade
I
22 (85)
4 (15)
II
21 (66)
11 (34)
III
15 (34)
29 (66)
Ist Injection Response
Yes
40 (78)
11(22)
No
18 (35)
33(65)
VAS Score
Initial
6.1 (2.3)
5.2 (2.3)
0.066
2nd Visit
4.4 (2.4)
4.4 (2.3)
0.924
Follow-up
2.4 (2.1)
5.1 (2.7)
Change in VAS
3.7 (2.0)
0.1 (2.0)