Long-term effects of intra-articular oxygen-ozone therapy versus hyaluronic acid in older people affected by knee osteoarthritis: A randomized single-blind extension study
Available accessResearch articleFirst published online May, 2020
Long-term effects of intra-articular oxygen-ozone therapy versus hyaluronic acid in older people affected by knee osteoarthritis: A randomized single-blind extension study
There is little evidence on intra-articular (IA) treatment in knee osteoarthritis (KOA) and there is a lack of long-term follow-up studies.
OBJECTIVE:
To assess the long-term effectiveness and safety of IA oxygen-ozone (OO) and hyaluronic acid (HA) in terms of functioning in KOA patients over a 31-week period.
METHODS:
Patients aged 60 years with KOA were randomly allocated to receive 4 IA knee injections (1/week) of OO or HA (T0–T3) and a follow-up visit 4 weeks after the fourth injection (T4). In this extension study we assessed VAS and safety in patients with Visual Analogue Scale (VAS) 4 at the at 6-month follow-up visit (T5), undergoing a second treatment cycle (T5–T8) and 1-month follow-up visit (T9).
RESULTS:
Forty-two patients (aged 70.5 5.8 years) were randomly allocated to OO ( 22) or HA group ( 20). Twenty-three underwent another IA cycle: 12 (54.6%) in the OO group and 11 (55.0%) in the HA group. Both groups showed significant reduction in VAS ( 0.013) compared to baseline during both cycles. At follow-up visits (T4 and T9), VAS was significantly lower in the HA group ( 0.013). There were no differences in adverse events occurrence between groups.
CONCLUSIONS:
IA OO might be comparable to HA in terms of effectiveness and safety in reducing pain in KOA patients, although at both follow-up visits (T4 and T9) VAS was significantly lower in the HA group.
Osteoarthritis (OA) is a chronic degenerative musculoskeletal disease, characterized by a progressive loss of articular cartilage, formation of osteophytes, subchondral bone remodeling, and joints’ inflammation [1, 2]. Although its etiology remains still unknown, several risk factors have been identified, including age, physical inactivity, obesity, diet, and inflammaging, that include OA in a wider range of systemic low-grade inflammation diseases [3, 4].
Therefore, early diagnosis of this pathological condition is mandatory in order to define the proper therapeutic interventions to reduce the degenerative progression of OA with crucial implications for both patients’ health status and the economic impact on healthcare services [5]. In particular, patients affected by severe OA usually report joint pain with a progressive loss of function and subsequent disability resulting in a reduction of health-related quality of life (HRQoL) [6].
Intra-articular (IA)-injectable forms of hyaluronic acid (HA) are commonly used in the clinical practice to recover the viscoelastic properties of the synovial fluid [7, 8] and to a reduce the synovial inflammation [7], exerting a protective effect against cartilage erosion [9] and promoting endogenous IA hyaluronan production [10]. IA HA is considered a safe and relatively well-tolerated treatment, whereas the most common adverse event might be the mild and transient inflammatory reaction or flare at the injection site [11, 12].
On the other hand, the effectiveness of IA HA is controversial and is still considered a second-line approach in patients affected by OA, with an unsuccessful response to acetaminophen and/or nonsteroidal anti-inflammatory drugs (NSAIDs) [13, 14]. In fact, several international guidelines still do not recommend HA for the treatment of either knee or multiple-joints OA [13, 14, 15].
In the last years, there has been a growing interest in the therapeutic use of non-pharmacological techniques in subjects affected by knee OA (KOA), such as local vibration [16] or IA OO therapy [17, 18, 19, 20, 21].
OO is a mixture of oxygen (O) and ozone (O) produced from pure O passing through a high-voltage gradient (5–13 mV) in a medical generator and is used in several painful conditions, in particular in patients affected by low back pain and/or lumbar disc herniations [22, 23, 24, 25, 26, 27, 28]. OO probably exerts its positive effects on pain management through O intrinsic chemical properties and an anti-inflammatory activity that has been recently proposed in the literature [29]. The use of OO at IA level has been documented in humans and a recent randomized controlled trial (RCT) showed the efficacy of IA OO therapy compared to placebo in patients with KOA, in terms of pain relief, functional improvement, and HRQoL [20]. Moreover, our group has recently provided insights about the reliability and safety in the short-term (only one treatment cycle) of IA OO in patients affected by KOA [17]. In this pilot study, we showed that both IA OO and HA treatments significantly reduced pain, without differences between groups at any follow-up evaluations, except for the one month follow up. However, up to date, there is a lack of data on longer follow-up periods and multiple treatment cycles in patients affected by KOA.
Therefore, considering the few recommendations in the literature on IA treatment in OA and the absence of long-term follow-up studies on IA OO therapy in KOA, the aim of this randomized single-blind extension study was to evaluate the effectiveness and safety of multiple IA OO and HA treatment cycles in terms of pain, knee function, and HRQoL in older people affected by KOA over a 31-week period.
Materials and methods
Participants
In this randomized single-blind extension study we recruited patients referred to the Physical and Rehabilitative Medicine Outpatient Clinic, University Hospital “Maggiore della Carità”, Novara, Italy, from December 2014 to June 2015.
Inclusion criteria, as previously described in the pilot of this extension study [17], were: a) older people (age 60 years); b) knee pain, assessed by a Visual Analogue Scale (VAS) 4; c) radiological diagnosis of knee OA (grade II or III according to the Kellgren & Lawrence classification) [30]; d) ineffective previous rehabilitative treatment and/or oral NSAIDs, corticosteroid, and analgesic drugs; e) 1-week-wash-out from oral analgesic drugs and NSAIDs prior to the intervention.
We excluded patients with: a) infection in the injection area; b) knee ligaments’ lesions; c) knee replacement; d) knee surgery in the previous year; e) femur or tibia/fibula fractures; f) previous IA corticosteroid therapy; g) clinical history of diseases that could be worsened by OO (i.e. hyperthyroidism, thrombocytopenia, myocardial infarction, bleeding disorders); h) contraindications for IA treatment.
This study was approved by the Local Ethics Committee and was performed according to the Declaration of Helsinki, with pertinent national and international regulatory requirements. All participants provided written informed consent and were free to withdraw from the study at any time.
Study design
We performed a digitally-generated randomization algorithm with 1:1 distribution and no blocks to allocate the participants to the two different groups: OO group and HA group.
Both groups underwent a first treatment cycle consisting of 4 IA injections, once per week for 4 consecutive weeks (T0–T3); moreover, an additional follow-up visit was performed at 4 weeks after the fourth injection (T4).
Furthermore, in this extension study we evaluated all the participants at 6-month follow-up visit (T5); patients with a VAS score 4 underwent a second treatment cycle (T5–T8) and another follow-up visit at 1 month after the last injection (T9), while patients with a VAS score 4 were scheduled for follow up visit (T9) only.
In the period lasting between the two treatment cycles patients were instructed to perform specific rehabilitative therapeutic exercises for knee OA.
Intervention
As previously described in the pilot study [17], in both groups 0.7 32 mm (22 G) sterile needles were used. We performed IA injections on supine patients with knee flexed at 90, in sterile conditions (skin cleanse and double disinfection with iodopovidone 7.5%). The injection approach performed was anterior, lateral to rotula tendon and between the inferior margin of condilus-femoralis lateralis and superior margin of tibial plateau. Needles were always substituted after drawing up the drug. No pre-medication or anesthesia were used.
In the OO group, OO was generated before each visit, by an Ozonline E80 generator (Eco3 s.n.c., Brandizzo, TO, Italy), connected to a pure O source. According to recent literature [17, 20], we used a OO concentration of 20 mcg/ml for the IA infiltrations with an injection time of 15 seconds, considering that O is instable and might decay after 20 seconds.
The HA group performed an IA HA treatment, through a pre-filled syringe device (Hyalgan Fidia Farmaceutici s.p.a., Abano Terme, PD, Italy) containing a high-molecular weight (500,000–730,000 Da) fraction of purified natural sodium hyaluronate in buffered physiological sodium chloride (pH 6.8–7.5). The viscous solution was injected into knee joint using the same approach as the OO group.
Outcomes
Knee pain assessed by the VAS [31] was the primary outcome of this study. Moreover, we considered the following as secondary outcome measures: knee pain and function, using the Oxford Knee Questionnaire (OKQ) [32]; general health and well-being, assessed by the 12-Item Short Form Health Survey (SF-12), and its summary measures, Physical Component Summary (PCS) and Mental Component Summary (MCS) [33]; HRQoL using the European Quality of Life-5 dimensions (EQ5D) [34]. All evaluations were performed at any study visit by an author unaware of patients’ allocation from T0 to T9, whereas EQ5D assessment was performed only at the beginning and at the follow-up visit (4 weeks after the fourth injection) in both treatment cycles.
Furthermore, the occurrence of adverse events has been recorded during the entire study and they have been classified as: mild, self-limiting and not requiring medical intervention or severe, and requiring medical intervention.
Statistical analysis
In light of the small sample size, we assumed a non-Gaussian distribution of the variables considered. Differences between each variable in the OO and HA groups have been evaluated with Friedman’s analysis of variance (ANOVA). Dunn post hoc comparison was used to identify significant differences between mean values. Differences between single variables in different groups were evaluated with the Mann-Whitney U-test. A type I error (alpha) level of 0.05 was chosen, and the Bonferroni correction for multiple comparisons was applied considering four variables, which resulted in a new alpha-error level of 0.013. All statistical analyses were performed using the GraphPad Prism package, version 6.0 (GraphPad Software, Inc., San Diego, CA, USA).
Anamnestic and demographical characteristics of study population at baseline ( 42)
Total ( 42)
OO group ( 22)
HA group ( 20)
values
Age (years)
70.5 5.8
70.3 6.5
70.7 5.4
ns
BMI (kg/m)
27.0 1.8
27.1 1.9
26.8 1.7
ns
Sex (female/male)
29/13
16/6
13/7
ns
Smokers
9 (21.4)
5 (22.7)
4 (20.0)
ns
Previous treatment with NSAIDS and/or GC
7 (16.7)
5 (22.7)
2 (10.0)
ns
Kellgren-Lawrence Grade II
29 (69.0)
15 (68.2)
14 (70.0)
ns
Kellgren-Lawrence Grade III
13 (31.0)
7 (31.8)
6 (30.0)
ns
Continuous variables are expressed as means standard deviations, categorical variables are expressed as counts (percentages). Abbreviation: BMI Body Mass Index; NSAIDs nonsteroidal anti-inflammatory drugs; GC glucocorticoids.
Study flowchart.
Results
Of the 120 patients screened for eligibility, 42 patients (29 females and 13 males), mean age of 70.5 5.8 years, were enrolled and randomly allocated to the OO group ( 22) and HA group ( 20). Their anamnestic and demographical characteristics are listed in Table 1.
There were no drop outs in the first treatment cycle, but at the 24-week follow-up visit (T5) we recorded 2 drops out (9.1%) in the OO group and 1 drop out in the HA group (5.0%).
Twenty-one patients showing a VAS 4 at T5 underwent a second treatment cycle: 11 (50.0%) in the OO group and 10 (50.0%) in the HA group, without significant differences in prevalence between the two groups, as showed by the study flowchart (Fig. 1).
There were no significant differences in adverse events occurrence between the two groups, at any study visit. In the OO group, 2 patients (9.1%) experienced adverse events in the first two minutes after treatment (swelling and joint heaviness) during the first treatment cycle and 1 patient (9.1%) during the second treatment cycle. In the HA group, 3 patients (15.0%) complained of self-limiting pain and encumbering sensation following the IA injection during the first treatment cycle and 1 patient (10.0%) experienced swelling and joint heaviness during the second treatment cycle. However, all adverse events were self-limiting, resolving spontaneously 24 hours after treatment.
Visual Analogue Scale (VAS) modifications in the HA and OO groups at different study visits. Within-group differences compared to T0 ( 0.013); Between-group differences ( 0.013).
Secondary outcomes modifications in the HA and OO groups at different study visits. Within-group differences compared to T0 ( 0.013); Between-group differences ( 0.013).
Both OO and HA groups showed statistically significant variations in VAS scores ( 0.013) at all study visits compared to baseline (T0 and T5, respectively) during both treatment cycles, except for the first time periods (T1–T0 and T6–T5, respectively), as shown in Fig. 2. At both follow-up visits (T4 and T9) the VAS score was significantly lower in the HA group compared to the OO group ( 0.013) (see Fig. 2 for further details).
Considering the secondary outcomes, there were statistically significant differences ( 0.013) in OKQ scores in both groups and in both treatment cycles only between the last injection visits (T3 and T8) and the baseline visits (T0 and T5) and between the two follow-up visits (T4 and T9) and the baseline visit (T0 and T5). Both groups showed no statistically significant differences in SF-12 PCS, SF-12 MCS, and EQ5D in all the timeframes in both treatment cycles (Fig. 3).
Discussion
The results obtained in this randomized single-blind extension study not only confirmed the safety of a 1-month weekly IA OO and HA treatment protocol in patients affected by KOA, as shown in the pilot study [17], but demonstrated also the overall safety of two OO and HA treatment cycles over a 31-week follow up in patients affected by KOA. Moreover, this study suggests that IA HA treatment might have a more prolonged effect in terms of pain reduction compared to OO therapy in the short term, even though the differences in terms of pain reduction and other functional outcome measures were not statistically different after a longer follow-up (6 months).
Results of this study not only confirmed the safety of a 1-month weekly IA OO and HA treatment protocol in patients affected by KOA, as shown in the pilot study [17], but demonstrated also overall safety of two OO and HA treatment cycles over a 31-week follow up.
The few adverse events recorded were mild and self-limiting until 24 hours after treatment in both groups; patients treated with OO reported adverse events in 9.1% of cases during both treatment cycles. Oh the other hand, in the IA HA group, 15.0% of patients complained self-limiting pain and encumbering sensation after the first injection during the first treatment cycle and 10.0% experienced adverse events during the second treatment cycle.
OO has been widely considered an overall safe therapeutic option for several diseases, although the most typical adverse event associated with IA HA treatment is an inflammatory reaction, or flare, commonly mild, and often self-limiting [10], at the injection site characterized by pain and swelling [8, 10, 12, 35, 36].
On the other hand, Gazzeri et al. reported the only case of fatal septic shock after intramuscular-paravertebral OO injection [37], probably due to an inadequate asepsis during the invasive procedure that might have been easily prevented using a sterile procedure [22].
Several evidences suggest that the OO might modulate the cytokine activity, inhibiting the pro-inflammatory prostaglandins and stimulating of pro-inflammatory cytokines antagonists [17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29] with a resulting immunomodulation [38], and antiinflammatory [39] and analgesic effect [40].
The role of IA OO therapy in treating KOA has been recently investigated with a growing interest in the literature, with promising effects in reducing pain and in improving functional recovery in the short-middle term [41]. Lopes de Jesus et al. showed in a randomized, double-blinded, placebo-controlled study the effectiveness of IA OO therapy in terms of pain relief, functional improvement, and quality of life in a cohort of patients with knee OA [20]. In comparison with a recent RCT performed by Duymus et al. [18], in our study we showed similar effects in pain reduction of OO and HA in KOA patients; moreover, IA OO therapy determined a statistically significant pain reduction at any evaluation (with the exception of the first week) in both treatment cycles without any statistical difference at any evaluation compared to the HA group.
However, VAS scores in the IA OO group were significantly higher at 1 month follow-up visit (T4) compared to the HA group, suggesting a more prolonged efficacy of HA in the short-term period. At T5 (6 months after the first injection), the VAS score was not statistically different in the two groups and the prevalence of patients requiring a second treatment cycle (VAS 4) was similar in both groups. Thus, a less durable effect of OO on pain reduction in the short term compared to HA could be suggested, but not on a longer follow-up (6 months). Furthermore, also at the second cycle 1-month follow-up visit (T9), the VAS score was significantly lower in the HA group than in the OO group.
This study has several limitations. The first was the small sample size that made not possible a statistically powered data analysis on the effectiveness of IA OO compared to IA HA in terms of VAS reduction. Another study limitation lies in the choice to perform a treatment cycle of four IA OO in order to be comparable to the IA HA treatment protocol. In common clinical practice protocols, the recommended number of consecutive IA OO treatment is higher and thus the effects of IA OO observed in this study could have been underestimated.
Conclusions
In this randomized single-blind extension study, we showed that IA OO therapy was comparable to IA HA in terms of pain reduction in two treatment cycles in patients affected by KOA. Data analysis reported a significant difference in VAS ( 0.013) at all study visits compared to baseline (T0 and T5, respectively) during both treatment cycles, except for the first time periods (T1–T0 and T6–T5, respectively). However, at both 1-month follow-up visits, pain was significantly lower in the group treated by IA HA, suggesting a more prolonged effectiveness in terms of pain reduction in the short period (at 1 month after the beginning of treatment cycle). Moreover, the results obtained demonstrated also the overall safety of two OO and HA treatment cycles over a 31-week follow up, confirming data of the pilot study [17]. Further evidence is necessary to better investigate the effectiveness of these IA techniques in patients affected by KOA.
Footnotes
Conflict of interest
The authors declare no personal or funding interests.
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