THE RELATIONSHIP BETWEEN PAIN PATTERN AND DISABILITY IN PATIENTS WITH KNEE OSTEOARTHRITIS

DISCUSSION

This study aims to evaluate OA pain patterns and their relationship to physical function and pain severity.

Previous studies have concentrated on assessing the duration and frequency of knee pain, besides its location, and pattern via several techniques such as the knee diagram[ii].

Our study has shown that OA patients' ages have 35 to 62 years, with an average of 47.6 ± 6.3 years. Most patients have been females (88%). Thompson et al.⁵ have performed a similar study to evaluate the relationship between OA risk factors and the different types of knee pain. Most of the participants' ages have ranged from 45-64 years. Most of patients have been females (62%).

The mean VAS for pain has been 6.95± 0.97. The pain has ranged from moderate (29%) to severe (71%), with no patients experiencing mild pain. The mean WOMAC has been 46.29± 13.03. 

McLendon et al.11 have shown that knee pain is more valuable in determining physical dysfunctions than radiographic characteristics of knee OA.

Zhang and Jordan¹²have illustrated how difficult it is to investigate risk variables for symptomatic OA. While OA pain has been regarded as chronic, it is not always persistent. Throughout the disease, physicians frequently find that patients with OA experience pain aggravation.

However, few studies have been performed to evaluate the association between risk variables and pain patterns due to methodological and practical challenges.

In our study, the WOMAC total pain score has been 12± 3.8. and Most of our patients (75%) have experienced severe WOMAC pain. 

Similarly, Cubukcu et al.¹³ have reported that the WOMAC pain score (mean ± SD) is 14± 3.35, which indicates that most of their patients have experienced severe WOMAC pain.  

In our results there was moderate correlation between VAS pain score and WOMAC pain score (r=0.472, p<0.0001).

Basaran et al.¹⁴ have performed a similar study to assess the reliability and validity of the WOMAC OA index and WOMAC has shown moderate correlation with VAS and his study concluded that WOMAC pain represents a consistent index to be used with OA patients.

Our study has reported that the mean WOMAC for morning stiffness ranges from mild to moderate (1-2). A remarkable association has been found between severe pain measured by VAS pain score and degree of stiffness measured by WOMAC stiffness (r=0.636, p<0.0001).

Our findings have revealed a positive correlation between severe pain measured by WOMAC pain score and the following: severe stiffness measured by WOMAC stiffness (r=0.357, p<0.0001). Physical impairment measured by WOMAC function (r=0.857, p<0.0001). Higher values of total WOMAC score (r=0.916, p<0.0001).

Similarly, Cubukcu et al.¹³ have documented that WOMAC pain scores are significantly associated with WOMAC disability (r=0.631, p<0.0001) and WOMAC stiffness (r=0.342, p<0.01).

Alkan et al.¹⁵ have performed a study to determine relationships between conventional clinical measures and self-reported disability. In OA patients, they have found that pain areas and physical function are significantly correlated with WOMAC subgroup scores and VAS pain (p < 0.05).

There have been significant correlations between severe pain measured by VAS pain score and severe difficulty in physical functions measured by WOMAC function (r=0.521, p<0.0001),

The likelihood of disability is increased in communities where knee pain is prevalent. Thus, it is critical to comprehend the elements that contribute to disability in patients with knee OA. Several studies have examined the association between pain and physical function in people with knee OA^11.16.17

In line with these investigations, we have found a positive association between pain severity and disability using WOMAC subscales. The WOMAC scale has enabled an in-depth examination of pain. Patients have rated the severity of their pain while undertaking activities using the WOMAC pain subscale. We have interpreted this finding as the result of a vicious cycle of pain, causing decreased functional abilities.

According to our findings, most of patients hav been localized pain pattern (63%), consistent with Thompson et al.⁵, who have revealed that localized pain represented 50.6%, then regional (25.9 %), and diffuse pain (23.5%). The pain patterns in both knees have been consistent.

It is critical to detect the precise area of knee pain for diagnosis. It is unknown whether the site of knee pain varies naturally as the condition progresses.^18.19

Sengupta et al.²⁰ have compared pain emanating from the patellofemoral, lateral, and medial regions to osteophytes visible on magnetic resonance imaging scans.

Our results have revealed that there were significant correlations between severe pain measured by VAS pain score female sex (r=0.56, p<0.0001), as well as higher disease duration (r=0.303, p=0.01).

Moreover, there have been significant correlations between severe pain measured by WOMAC pain score and female sex (r=0.44, p<0.0001).

Females are more exposed to experience knee OA¹², which may be due to differences in the pathophysiology. For instance, there may be alterations in cartilage and bone associated with differences in pain sensitivity between the two genders.

Fischbach and Jordan²¹have discovered that female sex is linked with decreased medial cartilage in OA patients using magnetic resonance imaging (MRI). However, variations in pain rating have not been investigated.

 Functional MRI (fMRI) has demonstrated that gender variation is associated with activating pain sensation and processing centers such as the cerebellar cortex, hippocampus, dorsolateral prefrontal cortex, and mid-cingulate cortex.²²

CONCLUSION

Majority of patients with knee OA had moderate level of knee pain and functional disability in daily living and they had the ability to localize site of pain. Also, the severity of knee pain and stiffness may influence the degree of disability in OA patients.  As a result, OA treatments can be based on clinical aspects and functional status rather than relying on radiological findings.