Knee osteoarthritis (KOA) is an irreversible condition involving structural deformation of the joint. Albeit KOA is characterized by several symptoms, pain is the most prevalent symptom limiting patients daily life. Previous studies suggest that the increased pain in KOA, i.e. hyperalgesia, can be attributed to peripheral and central sensitization1,2. Peripheral sensitization involves increased biochemical processes at nociceptors3,4. Central sensitization involves alterations in the biochemical properties of segmentally located secondary neurons, increased function of various brain areas and decreased function of descending pain inhibitory pathways5,6. The presence of pain sensitization has high importance in KOA due some authors attribute the sensitization to the emergence of e.g. neuropathic-like pain and to the structural changes in joint innervation7,8.
Pressure pain threshold (PPT) measurement is the most relevant method for assessing pain sensitization in KOA. PPT measurement consists of an externally applied, controlled, gradually increased, in normal condition harmless stimuli performed until the onset of pain. PPT measurement can be performed locally around the knee for measuring peripheral sensitization and distant away from the knee for measuring central sensitization. Lower PPT suggests increased pain sensitivity, higher PPT proposes decreased pain sensitivity. Many trials presented enhanced mechanical pain sensitivity in KOA compared to healthy controls9.
The positive results of different types of manual mobilization on decrease of pain sensitivity have previously been reported in KOA10,11. Interestingly, the effect of Maitland® mobilization on decrease of peripheral and central sensitization has been rarely investigated in KOA. Moss et al. demonstrated the immediate effect of Grade II accessory (not end-range) Maitland® mobilization on reduction of pressure-induced hyperalgesia in KOA12. Moreover, Courtney et al. also presented that Grade II accessory (not end-range) Maitland® mobilization decreases peripheral pain sensitivity immediately and after 1-week period too in KOA13. However, no study investigated the effect of end-range Maitland® mobilization on deep mechanical pain sensitivity immediately and after 1-week period in KOA. In addition, no study has investigated the effect of end-range and not end-range Maitland® mobilization on pain sensitivity in a certain time-period in KOA. Therefore, the aim of our studies were the following:
- Investigating the effect of single end-range Maitland® mobilization on pain sensitization and knee function immediately and after 1-week period in KOA;
- Investigating the return of pain sensitization and some function-related measures to baseline after single end-range and not end-range Maitland® mobilizationin a 6-day period in KOA.
The first study comprised randomised, controlled clinical trial conducted with overall 40 female patients. Twenty patients assigned to end-range Maitland® group (EMGr) received single end-range Maitland® mobilization and 20 patients allocated to Control Group (CGr) were treated with single sham manual therapy. End-range Maitland® mobilization consisted of Grade III or IV accessory Maitland® mobilization performed in flexion and extension end-range position of the tibiofemoral joint. Sham manual therapy was applied as a hands-on cutaneous input technique performed in end-range positions of both knees without any movement. Both mobilizations were performed 2-times for 3 minutes with 30 seconds rest intervals. Outcome measures were assessed before treatment, 30 minutes and 1 week after treatment. Outcomes were local PPT and distant PPT, general pain intensity during the previous week via VAS scale (this variable was determined only prior the treatment session and after 1 week), pain intensity during dynamic balance measured with Numerating Pain Rating Scale (NPRS), dynamic balance measured with TUG test and the strength of passive resistance of the knee joint, which consisted of the maximal pain-free passive knee flexion range of motion (ROM) and the degree of resistance of connective tissues during passive knee flexion at the same time. Wilcoxon signed-rank test and Mann-Whitney U test was used to compare differences in within-group comparison and between-group comparison, respectively, during our statistical analysis. Significance level was set at p<0.05.
All outcome measures improved significantly in EMGr postintervention and no difference was revealed in CGr postintervention. Despite general pain VAS, between-group comparison revealed significant difference in all measured variables in favor of EMGr. Within-group comparison revealed no significant difference in EMGr and CGr at 1-week after treatment. Between-group comparison revealed significant difference in strength of passive resistance after 1-week period in favor of EMGr.
The second study contained randomised, controlled clinical trial conducted with overall 66 (50 female and 16 male) patients. Twenty-two patients assigned to end-range Maitland® group (EMGr) received single end-range Maitland® mobilization, 22 patients assigned to not end-range Maitland® group (nEMGr) received single not end-range Maitland® mobilization and 22 patients assigned to Control Group (CGr) received single sham manual therapy. End-range Maitland® mobilization and sham manual therapy was performed as previously described; not end-range Maitland® mobilization consisted of Grade II accessory Maitland® mobilization performed in loose position of the joint. All mobilizations were performed 2-times for 3 minutes with 30 seconds rest intervals. Outcome measures were assessed pre-, 30 minutes postintervention and on the following consecutive second days within 6-day period. Outcomes were the previously mentioned local and distant PPT, TUG test and strength of passive resistance. Analysis was performed with mixed model for calculation differences. Results were calculated as the change compared to baseline in every measurement point. A two-sided p value of <0.05 was regarded as statistically significant.
Local PPT increased significantly postintervention in all groups compared to pre-intervention, but the significant increase persisted until 6th day only in EMGr. Between-group comparison revealed significant improvements postintervention and on the 2nd day in favor of EMGr compared to nEMGr and CGr. Distant PPT increased significantly postintervention compared to pre-intervention in EMGr and this significant increase persisted until the 4th day. Between-group comparison revealed significant difference in favor of EMGr compared to CG and nEMGr postintervention and in all measurement points except 6th day. TUG time decreased significantly postintervention in EMGr compared to pre-intervention and the significant decrease was maintained on every consecutive follow-up. Despite no change was revealed postintervention compared to pre-intervention in nEMGr and CGr, significant decrease was found on every consecutive follow-up in both of these groups. Both within-, and between-group comparison revealed significant decrease of passive resistance postintervention in EMGr. No significant change was observed in any further measurement point regarding either outcome in both within-, and between-group comparison.
Despite previous studies investigated the immediate effect of single not end-range Maitland® mobilization on local and distant PPT and physical function in KOA12-13, neither applied single end-range Maitland® mobilization on these outcomes and on knee joint tension measured at maximal pain-free passive ROM as well. As mentioned previously, pain is the prevalent reported symptom in KOA leading often to loss of function, and in severe case, to movement restriction and disability too. As the prevailing pain in sensitization may lead to the development of severe pain5, we aimed to investigate pain sensitization further from a different perspective in KOA. In fact, pain is very difficult measuring objectively due to it’s subjective nature. However, applying the PPT measurement in KOA is relevant as a result of sensitization. Based on our results, applying single end-range Maitland® mobilization reduced peripheral and central sensitization immediately and increased the functional status of the knee as well. In addition, we also confirmed the increase of local and distant PPT persisting for 2 days and 4 days, respectively. In contrast, patients’ pain perception over the past week, as defined by the VAS scale, remained unchanged after single end-range Maitland® mobilization. Patients' dynamic balance (TUG test) also improved immediately after single end-range Maitland® mobilization, whereas no improvement was observed after single not end-range Maitland® mobilization. Noticeably, the improvement observed from 2nd day in all groups can be explained by the fact that patients could gain practice during the bi-daily testing and the performance of the test itself improved their dynamic balance. In contrast, our first study comprised only after one week the forthcoming TUG test, which hindered practicing for them. Therefore, we concluded that the outcome of our first study is realistic and that neither single not end-range Maitland® mobilization, nor single sham manual therapy has long-term effect on dynamic balance. The effect of single end-range Maitland® mobilization resulted in reduction of passive tension of periarticular tissues around the knee immediately after treatment, whereas single not end-range Maitland® mobilization had no effect. This decrease was also observed in women patients even after 1 week in our first study. However, reduction was no longer significant after 6th day in the case of our second study involving men patients too, which could be attributed to characteristic of men representing increased connective tissue tightness.
In conclusion, single end-range Maitland® mobilization increased the local and distant PPT immediately and these effects endured in 2-day period and 4-day period, respectively, moreover, decreased the TUG time and the strength of passive resistance immediately in KOA. As single not end-range Maitland® mobilization produced immediate effect only in increase of local and distant PPT, we suggest that end-range Maitland® mobilization is the superior intervention option for obtaining immediate and long-term effect in clinical practice in KOA. Based on our suggestion’, performing end-range Maitland® mobilization on every second day could be favourable for maintaining alleviation of pain and improvement of physical function in long-term too. In addition, end-range Maitland® mobilization could also be applied prior physiotherapy or alone in KOA. In future, longer interventional studies could investigate the long-term effect of end-range Maitland® mobilization performed every second day or at least 3-times per week for several weeks either alone or in combination with physiotherapy in KOA.
Dr. Miklós Pozsgai, physiotherapist, Maitland® trained therapist
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The studies mentioned in the blog are published as the following (for reading in full-length, open the link found below each article):
M Pozsgai, IA Péter, N Farkas, P Than, N Nusser: End-range Maitland® mobilization decreasing pain sensitivity in knee osteoarthritis: randomised, controlled clinical trial, European Journal of Physical and Rehabilitation Medicine, 2022; 58(3): 442 – 451.
M Pozsgai, K Udvarácz, IA Péter, P Than, N Nusser: Effect of single end-range and not end-range Maitland® mobilization on pressure pain threshold and functional measures in knee osteoarthritis: randomised, controlled clinical trial, European Journal of Physical and Rehabilitation Medicine, 2022; 58(5): 774 – 783.
Cover image by wayhomestudio on Freepik