Twenty three (62 %) of the 37 enrolled people with knee OA (males = 16, females = 7, age = 51.20 ± 12.00 years, mass = 96.35 ± 18.14 kg, height = 178.00 ± 10.10 cm, BMI = 29.24 ± 9.52) met the inclusion criteria. Two participants did not complete the allocated intervention; one from the PA-PRP group who withdrew due to minor injection-related pain and swelling which resolved without further treatment, and one from the HA group who suffered an acute meniscal tear unrelated to the treatment. Two additional participants withdrew from the study due to other unrelated injuries after the four week follow up assessments. Consequently, data was available for 21 participants (PRP = 11 participants, HA = 10 participants) for the four week follow up and for 19 participants at 12 weeks (Fig.
1). Participant characteristics are displayed in Table
1. No differences were found between the two groups (
p > 0.05).
Table 1
Comparison of participant characteristics who completed the intervention by group
Age, mean (SD) years | 49.91 (13.72) | 52.70 (10.30) |
BMI, mean (SD) kg/m2
| 27.92 (11.94) | 30.87 (5.64) |
Previous surgery, no. (%) | 5 (45 %) | 8 (80 %) |
Gender (Male), no. (%) | 8 (72.73 %) | 7 (70 %) |
Symptom duration, mean (SD) years | 8.50 (4.95) | 15 (7.07) |
Cause of osteoarthritis, no. | | |
Degeneration/unknown | 6 | 4 |
Post joint injury/surgery | 3 | 3 |
Sport related degeneration | 2 | 3 |
No treatment-related major adverse events were experienced by participants. Two participants from the PA-PRP group experienced minor pain and swelling during the injection period believed to be related to the injection technique. Both participants completed the injection course, and had resolution of symptoms by the following week. No further adverse events were experienced during the intervention or follow-up period.
Average pain recorded using the 100 mm VAS reduced from baseline at the four and 12 week follow up time points for both the PA-PRP and HA groups (Table
2). Although there was a slight increase in pain at the 12 weeks in the PA-PRP group, this still represented a 24 % improvement above baseline pain. Repeated Measures ANOVA revealed the reduction in pain was significant for the PA-PRP group only (
p = 0.017). Post hoc tests showed that the reduction in pain at four weeks was significantly less than baseline (27.67 mm, 95 % CI 12.39 to 42.95,
p = 0.003, ETA = 0.686), however the 11.4 mm reduction in VAS at 12 weeks was not statistically significant. No significant reductions in pain were found for the HA group.
Table 2
Mean (SD) for VAS, KOOS, KQoL and functional tests at baseline and four and 12 weeks following final injection
Pain | VAS | 48.09 (23.75) | 19.64 (17.61)** | 36.89 (25.42) | 39.70 (21.90) | 12.90 (14.06) | 14.13 (9.30) |
KOOS | Symptoms | 48.70 (15.83) | 57.14 (20.33) | 57.86 (22.76) | 62.14 (17.99) | 61.07 (26.86) | 80.16 (8.40) |
| Pain | 57.07 (11.21) | 71.47 (16.67)** | 68.89 (15.76)* | 70.00 (11.25) | 67.22 (25.55) | 79.32 (9.33) |
| Function | 70.72 (13.64) | 79.27 (15.08) | 78.68 (15.87) | 75.44 (12.42) | 79.12 (28.63) | 90.03 (7.31)** |
| Sport | 31.82 (20.40) | 40.46 (28.32) | 41.00 (27.77) | 47.00 (28.69) | 46.50 (33.75) | 64.44 (23.64) |
| QoL | 30.11 (18.92) | 40.89 (27.55) | 38.75 (28.38) | 41.87 (13.51) | 42.50 (21.21) | 54.86 (9.77) |
KQoL | Physical | 57.72 (18.35) | 65.00 (18.14)* | 68.83 (18.64)** | 71.16 (14.91) | 68.33 (27.54) | 80.55 (13.46) |
| Activity | 59.09 (23.33) | 72.73 (16.79) | 70.00 (22.23) | 75.50 (15.71) | 78.50 (29.16) | 88.89 (7.41) |
| Emotional | 46.97 (26.69) | 58.71 (23.68)* | 58.75 (29.49)** | 58.75 (24.25) | 67.08 (29.88) | 75.00 (16.00) |
Functional tests | Hops | 46.64 (33.04) | 57.64 (41.36)* | 79.33 (34.17)** | 55.50 (35.43) | 51.50 (39.49) | 79.25 (38.04) |
| Knee bends | 19.45 (8.25) | 22.27 (8.37) | 31.44 (7.96)** | 20.50 (13.23) | 25.30 (16.60) | 31.13 (15.63) |
For the PA-PRP group, significant improvements were found at both follow up time points in the KOOS Pain subscale (4 weeks: 13.33, 95 % CI 4.66 to 22.01,
p = 0.007; 12 weeks: 11.67, 95 % CI 2.99 to 20.34,
p = 0.014, ETA = 0.624), the KQoL-26 Physical subscale (4 weeks: 8.50, 95 % CI = 1.84 to 15.16,
p = 0.018; 12 weeks: 9.33, 95 % CI 4.56 to 14.11,
p = 0.002, ETA = 0.706) and the KQoL Emotional subscale (4 weeks: 12.08, 95 % CI 3.26 to 20.91,
p = 0.013; 12 weeks: 9.58, 95 % CI 17.11 %,
p = 0.009, ETA = 0.715) (Table
2). For the HA group, significant improvements were only found in the KOOS Function subscale at 12 weeks (14.05, 95 % CI 18.59 to 24.15,
p = 0.008, ETA = 0.602). Table
2 also demonstrates that the PA-PRP group significantly improved both hopping (4 weeks: 13.44, 95 % CI = 2.23 to 24.66,
p = 0.025; 12 weeks: 22.33, 95 % CI 11.86 to 32.80,
p = 0.001, ETA = 0.799) and knee bend (12 weeks: 9.78, 95 % CI 5.00 to 14.56,
p = 0.002, ETA = 0.756) performance, whereas changes in physical function in the HA group were not found to be significant. To investigate between-group differences in mean change scores on the 100 mm VAS, KOOS, KQoL-26 and functional tests, ANCOVA was performed adjusting for baseline scores (Table
3). No significant between-group differences were found for any of the self-reported measures or for either of the functional tests (
p > 0.05).
Table 3
Adjusted mean difference (95% confidence intervals; CI) between the two groups for VAS, KOOS, KQoL and functional tests at baseline and four and 12 weeks following final injection
Pain | VAS | 1.90 (-13..80 to 17.60) | 0.79 | 18.81 (-0.62 to 38.24) | 0.06 |
KOOS | Symptoms | 7.52 (-17.20 to 32.23) | 0.53 | −15.57 (-34.12 to 2.99) | 0.09 |
| Pain | 15.64 (-9.81 to 41.10) | 0.21 | −4.30 (-19.76 to 11.16 | 0.56 |
| Function | 4.44 (-17.00 to 25.88) | 0.67 | −8.93 (-19.92 to 2.07) | 0.10 |
| Sport | 0.66 (-29.31 to 30.62) | 0.96 | −13.68 (-36.38 to 9.02) | 0.22 |
| QoL | 11.17 (-6.22 to 28.57) | 0.19 | −8.09 (-25.11 to 8.93) | 0.33 |
KQoL | Physical | 10.90 (-9.11 to 30.91) | `0.27 | −0.41 (-8.59 to 7.77) | 0.92 |
| Activity | 6.46 (-16.09 to 29.01) | 0.55 | −11.01 (-25.59 to 3.57) | 0.13 |
| Emotional | 0.18 (-19.76 to 20.11) | 0.99 | −11.60 (-28.49 to 5.28) | 0.17 |
Functional tests | Hops | 17.23 (-19.26 to 53.72) | 0.33 | 8.93 (-5.26 to 23.13) | 0.20 |
| Knee bends | −0.81 (-9.29 to 7.68) | 0.84 | 1.16 (-9.11 to 11.43) | 0.81 |