The role of psychological factors, like that of pain catastrophizing, anxiety, and depression, in the presentation of orthopedic symptoms and patient-reported pain are becoming more recognized.1–3, 6, 11, 35 Hampton et al. demonstrated that patients with hip pathology also present with levels of pain catastrophizing, anxiety, and depression. Hip pain and dysfunction may play a significant role in a patient’s psychological well-being.11 We further confirmed this link between function and psychology; specifically, a link between improved activity of daily living function and improved psychological factors.
Our primary aim was to assess the impact functional improvement had on the levels of pain catastrophizing, anxiety, and depression. Hip function was measured in terms of the patients’ subjective assessment of their hips, rather than with performance-based functional metrics. In patients with differing hip pathologies, we found that patients endorsed a greater level of function after treatment, as measured by scores of HOS function and each of the HOOS subcategories. The most improved absolute measurements from pre-to-post treatment include the HOOS Sports, HOOS Symptoms and HOOS QoL subcategories; thus, patients endorsed the most functional improvement in lower stress, day-to-day activities. Additionally, patients endorsed a lower level of average pain following treatment, as measured by the VAS and HOOS pain subcategory.
Assessment of the psychological parameters of this study began by establishing the levels of pain catastrophizing, anxiety, and depression present in our patients prior to their onset of treatment. Untreated patients presenting with hip pain were affected by clinically significant levels of each of these factors prior to treatment, regardless of their diagnosis. This link between hip pathology and mental health status has been previously documented in OA, FAI, and DDH.2, 3, 7–9, 11, 36 Additionally, it has been previously shown that this relationship is quantifiable, as higher reported subjective functioning in hip patients is associated with lower levels of pain catastrophizing, anxiety, and depression at time of presentation.11, 35 In our cohort, pain catastrophizing scores were particularly elevated in patients with lower function scores, as difficulties with activities of daily living, and the resulting loss of self-sufficiency, lend themselves to pain catastrophizing.8, 37
After assessing the psychological profile of our cohort prior to treatment, we next determined how each measured psychological category changed following treatment. Psychologic improvement may not always occur following treatment, as previous studies have shown that significant levels of various psychiatric conditions can be present after treatment of orthopedic conditions.38, 39 In a study of comorbidity progression following arthroscopic hip surgery, it is shown that psychological issues can worsen following treatment, perhaps due to dissatisfaction with the level of postoperative functional improvement.40 There is no association that shows that treatment itself directly improves psychological metrics if the patient does not experience an improvement in level of function. Our results support that improvement in the mental health measures is dependent on the effectiveness of treatment on improving hip function and overall quality of life.
Although improvement of each of the functional outcomes is related to improvement in pain catastrophizing, HADS anxiety, and HADS depression, our results demonstrate that improvement in HOOS ADL has the greatest magnitude of importance in the relationship with improvement in pain catastrophizing and HADS Depression/Anxiety. Loss of ADL independence has been shown to cause large declines in mental health, as functional impairment and pain have a strong impact on daily life, causing patients to avoid situations and activities that require the use of their problematic hip.41, 42 Conversely, it has been shown that relief from the factors that limit independence and social engagement can reduce feeling of helplessness and isolation, directly impacting feelings of depression and anxiety.43, 44 Our results support this supposition: improved hip function and the decreased burden felt in ADL has a strongest impact the improvement of mental health. Because activities of daily living represent such a large part of a patient’s quality of life it is likely that patients are more aware of their impairment if such activities are affected. Thus, functional improvement that reduces difficulty with ADL has a particularly strong effect on overall wellness.
Of the psychological metrics that improved alongside increased function, the pain catastrophizing total score demonstrated the most relative improvement. Pain catastrophizing is an important pain-related variable that has been adversely linked to disability and quality of life in patients with both hip and knee OA.45, 46 As pain catastrophizing is an exaggerated negative mental state during painful experience, it is a logical conclusion that decreased pain and increased function reduce catastrophizing.8 Our results support this link, revealing a significant decrease of PCS scores as functional assessment improves. As patients feel less hindered by their hip condition, their expectation and anticipation of associated pain and disability decreases accordingly.
There are a few limitations of this study. The cohort of patients included in this study presented to one specialist, and may not reflect all hip patients in a general population. Patients suffering from OA represented a majority of the diagnoses, and the small sample size of diagnoses like LTP and AVN prevented our ability to run a stratified analysis on each subgroup. However, because we are investigating the interplay between overall hip function and its impact on psychosocial health rather than any specific disease-modifying process, we deemed it appropriate to analyze our overall cohort. Additionally, our assessments lack standardization in both length of time from the pre- to post-treatment measurement as well as treatment protocol. Although about 85% of patients received surgery (compared to about 15% who received non-operative treatment) and we statistically controlled for length of time from pre-to-post treatment, the wide range in time elapsed between pre/post assessments and the varying treatment modalities may confound our results. However, we also note that the varying treatment modalities along with the time elapsed between assessments represent a real-life clinic setting—not an artificially-controlled setting—which bolsters the external validity of the current study.
Finally, concern regarding the validity and reliability of using self-report measures to evaluate musculoskeletal complaints has been documented in previous literature.47, 48 We attempted to addressed this issue by using validated assessments, but our reliance on using patient-reported outcomes to determine hip functionality and psychological comorbidity could affect the internal validity of the study.