Anxiety and insomnia in young- and middle-aged adult hip pain patients with and without femoroacetabular impingement and developmental hip dysplasia

Abstract

Background:

Hip pain in young and middle- aged adults with and without hip deformity receive treatment focused primarily related to hip structure. Because their hip pain may be chronic, these patients develop other modifiable co-existing disorders related to pain that go undiagnosed in this young and active population including insomnia and anxiety.

Objective:

The objective is to compare assessments of insomnia and anxiety in young and middle-aged adults presenting with hip pain with no greater than minimal osteoarthritis (OA) compared to asymptomatic (healthy) controls.

Comparisons between types of hip deformity and no hip deformity in hip pain patients were performed to assess if patients with specific hip deformities were likely to have insomnia or anxiety as a cofounding disorder to their hip pain.

Design:

Prospective case series with control comparison.

Setting:

Two tertiary university physiatry outpatient clinics.

Participants:

Fifty hip pain patients aged 18–40 years and 50 gender and aged matched healthy controls.

Methods:

Patients were enrolled if: 2 provocative hip tests were found on physical examination and hip radiographs had no or minimal OA. Radiographic hip deformity measurements were completed by an independent examiners. Comparisons of insomnia and anxiety were completed between: 1) 50 hip pain patients and 50 controls and 2) patients with different types of hip deformity.

Main Outcome Measures:

Insomnia severity Index (ISI) and Pain anxiety Symptom Scale (PASS)

Results:

Fifty hip pain patients (11 male, 39 female) with mean age of 31.2±8.31 years enrolled. Hip pain patients slept significantly less (p=.001) per night than controls. Patients experienced significantly greater insomnia (p=.0001) and anxiety (p=.0001) compared to controls. No differences were found in insomnia and anxiety scores between hip pain patients with and without hip deformity or between types of hip deformity.

Conclusion:

Hip pain patients with radiographs demonstrating minimal to no hip arthritis with and without hip deformity experience significant cofounding yet modifiable disorders of sleep and anxiety. If recognized early in presentation, treatment of insomnia and anxiety ultimately will improve outcomes for hip patients treated conservatively or surgically for their hip disorder.

Introduction

Hip pain can result in considerable impairment and disability. Many young and middle-aged adults experience hip pain for a prolonged period prior to an accurate diagnosis and/or intervention.[1–3] Many of these people experience hip pain associated with hip deformity and or acetabular labral tears. [1–3] Chronic pain is considered a complex interaction among physiological, psychological, and social factors often resulting in or maintaining disability.[4] This complexity of pain is especially evident when it persists over time, as psychological, economic, and social factors can interact with physical factors to change a patient’s report of pain and subsequent disability.[4] Specifically, pain as it relates to insomnia and anxiety has been the focus of low back pain research.[5–7] This research is important as insomnia and pain related anxiety including components of anxiety, fear avoidance, and pain catastrophizing are potentially modifiable. Little is known about the burden of chronic pain in young and middle-aged adults with hip pain with little to no radiographic osteoarthritis. A better understanding of modifiable disorders such as insomnia, fear avoidance and pain catastrophizing will direct more effective treatment for hip pain patients treated either with or without surgery. Patients considered candidates for hip preservation surgery often present with pain for prolonged periods of time and, therefore, often have unaddressed co-existing insomnia and anxiety disorders that should be treated to maximize outcomes following surgery. Likewise, young and middle-aged adult hip pain patients undergoing conservative treatment should also be assessed for these co-existing disorders to maximize function and improve quality of life.

Insomnia has been found to be a comorbidity associated with musculoskeletal disorders and chronic pain.[6, 8–13] For example, 53% of a chronic low back pain (LBP) population and 73% of a chronic musculoskeletal pain population demonstrated clinical insomnia.[6, 14] Chronic pain patients who experience insomnia admit to increased severity of pain, longer duration of pain, higher levels of anxiety and depression, and worse impairment in physical and psychosocial functioning when compared with chronic pain patients without insomnia.[6, 14–17]

Much of our understanding of the relationships between anxiety and pain related to musculoskeletal disorders includes studies involving people with LBP. Newcomer et al. found that people with chronic LBP as compared to acute LBP had a higher general anxiety level but similar transitory anxiety levels on the day of testing.[5] This suggests people with chronic pain recall more anxiety-provoking experiences than those with acute pain. Similarly, people with fear avoidance beliefs will avoid physical activity, which eventually leads to deconditioning, disability, and decreased function.[5] Identifying fear avoidance behavior ( a specific component of general anxiety) is important because these beliefs can be modified through cognitive behavioral interventions.[5, 18, 19] Leeuw et al.’s work suggests that pain catastrophizing can lead to pain related fear.[20] Catastrophizing behavior ultimately leads to poor outcomes.[7, 21] The ability to modify pain catastrophizing behavior has been verified and associated with better outcomes as compared to people not offered behavioral modification intervention.[7, 22–24]

Descriptions of patient characteristics of young- and middle-aged adults experiencing hip pain in the setting of hip deformity, including DDH and FAI, have been limited to pain distribution and physical examination findings.[1–3] These same descriptive studies report the insidious onset of pain with the average time of symptom onset to diagnosis being 3.1 years and 5.1 years respectively.[2, 3] Like other chronic pain disorders, patients with hip pain may develop insomnia. Further, coping with chronic pain can place an individual at risk for compensatory anxiety. Insomnia and anxiety have not been described in this patient population. Recognizing these adaptive or accentuated disorders would provide important information to healthcare providers to direct treatment to these disorders in addition to the functional and structural disorders related to the hip.

The purpose of this study was to describe insomnia and anxiety disorders in young- and middle-aged adult patients presenting for the evaluation of hip pain with little to no radiographic hip arthritis and compare these findings with those of age- and gender-matched asymptomatic healthy controls. Further, comparisons between types of hip deformity and no hip deformity in patients with hip pain were performed to assess if patients with specific hip deformities were more or less likely to have insomnia or anxiety as a cofounding disorder to their hip pain.

Materials and Methods

After obtaining the approval of the Human Studies Committee at Washington University School of Medicine, 50 patients between the ages of 18 and 40 years of age presenting for evaluation of hip pain by physiatrists at two tertiary medical centers were recruited. Inclusion criteria included: 1) pain for more than 3 months 2) a distribution of pain including the groin, lateral hip, with or without distribution in the buttock, 3) minimum of two positive provocative hip tests on physical examination and 4) a hip radiograph with a Tonnis grade of 0 or 1 with appropriate patient positioning to assess measurements for hip deformity. Exclusion criteria included: previous hip or lumbar spine surgery, inflammatory arthropathy, pregnancy, tumor or fracture of the hip or spine.

The provocative hip tests were performed by the examining physiatrists (HP,MR) and were deemed positive if the test reproduced their groin and/or lateral hip pain. Tests were chosen based on: 1) our experience of finding excellent inter-rater agreement in performing these tests between multiple examiners,[25] 2) a published consensus of hip preservation experts,[26] and 3) a recent systematic review of tests performed in patients with FAI.[27] Patients were included if groin and/or lateral hip pain was reproduced with a minimum of 2 of any of the following provocative tests: FABER(Flexion abduction external rotation), anterior impingement test (hip flexion to 90° and end range internal rotation), hip scour (end range hip flexion, internal and external rotation) FADIR test (end rang hip flexion, adduction and internal rotation), IROP (hip flexion to 90° with internal rotation overpressure), log roll test (passive hip internal and external rotation with the hip in a neutral position).

All patients had hip radiographic imaging, including an anteroposterior (AP) radiograph of the pelvis and either a lateral hip frog–leg of the affected side or a 45° Dunn view of both hips at the time of evaluation or within the prior 6 months. A physician (SS) blinded to the patient findings independently reviewed the radiographs. This physician has experience performing hip measurements and was found to have excellent intra-rater reliability (ICC ranges 0.88-.0.99) in performing these measurement for a sample of 22 hip radiographs assessed prior to this study. Measurements assessed included: Lateral center of edge angle (LCEA), alpha angle, acetabular inclination, crossover sign and Tonnis grade. Based on these measurements, the patients were grouped into 1 of 4 groups: no deformity, femoroacetabular impingement (FAI), developmental dysplasia of the hip (DDH) and mixed deformity (measurements with cutoffs consistent with combined type of deformity).

Patients completed the Insomnia Severity Index (ISI), and Pain Anxiety Symptoms Scale (PASS). The ISI is a standardized questionnaire consisting of 7 questions regarding length and quality of sleep.[28] Total scores were used to subgroup patients into 4 groups including: normal sleep, occult sleep disorder, definitive and severe insomnia. The PASS is a standardized 25 question tool used to assess anxiety related to pain.[16] The ISI and PASS scores of patients with hip pain were then compared to 50 asymptomatic gender- and age- matched controls.

The ISI and PASS scores of patients with pain and hip deformity were compared to those without hip deformity. Further comparisons of the ISI and PASS scores were made between patients with different types of hip deformity.

Analysis

All continuous variables were first tested for normality using a Shapiro Wilks test. For data that were normally distributed, independent t-tests were used to test for differences between patients and controls. For data that were not normally distributed, Mann-Whitney U tests were used to test for differences in distributions between patients and controls. Chi-square tests were used to test for differences in distribution of age and race. Patients were then classified by radiographic findings as 1) no deformity, 2) femoroacetabular impingement (FAI), 3) developmental hip dysplasia (DDH), or 4) mixed deformity. One-way analysis of variance (ANOVA) tests were used to examine differences on the BII and PASS between groups of patients with each of the 4 of radiographic classifications. An independent samples t-test was used to test for differences in ISI and PASS between patients classified with no deformity and patients with a deformity. Frequencies of normal and pathological findings were calculated for crossover, posterior wall, and ischial spine. Averages and standard deviations were calculated for the radiographic variables Averages and standard deviations for pain rating were calculated for the following regions of a body pain diagram: groin, anterior thigh, knee, lateral thigh, posterior thigh, buttocks, low back, and lateral hip.

Results

Fifty patients with hip pain (11 male, 39 female) with a mean age of 31.2±8.31 yrs. and BMI of 26.3kg/m² enrolled. (Table 1) There were no differences found between subjects with hip pain and the 50 asymptomatic healthy controls for age, BMI, race or gender. The mean length of time for patient’s reporting pain was 32.66 ±52.61 months. Average reports of pain using a numeric pain scale (NPS) ranged from average pain 2.78±2 to most pain 7.91±1.8. Radiographic measurements in hip pain patients revealed: 8 (16%) had no deformity, 13 (26%) had FAI, 13 (26%) had DDH and 16 (32%) had mixed deformity. The distribution of pain in patients presenting for evaluation of hip pain was variable (Table 2). Of the patients presenting with hip pain, 37/50 (74%) scored in the occult or absolute sleep disturbance category as compared to 7/50 (14%) of the controls. Patients with hip pain slept significantly less (p=.001) per night compared to controls by nearly a full hour. Prior to hip pain, 14/50 (28%) reported sleep problems and 12 of these 14 (85.7%) patients reported sleeping became more difficult following the onset of hip pain. Patients with hip pain also experienced significantly greater insomnia (p<.001) and anxiety (p<.001) as compared to controls (Table 3).

Table 1.

Demographics for patients with hip pain and controls. Numeric pain score and pain duration for patients with hip pain.

	Hip Pain Patients		Healthy Controls
Variable	Mean	StDev	Mean	StDev	P-value
Age (years)	31.2	8.31	32.33	8.74	.817
Height (inches)	66.0	5.41	67.33	3.85	.358
Weight (lbs)	158.3	34.56	159.5	29.9	.481
Numeric Pain Scale Average (0–10)	5.2	1.99	NA	NA	NA
Numeric Pain Scale Worst (0–10)	7.9	1.84	NA	NA	NA
Numeric Pain Scale Least (0–10)	2.7	2.03	NA	NA	NA
Duration of Hip Pain (months)	32.7	52.61	NA	NA	NA

^*Denotes a significant difference of P < .05

Table 2.

Descriptive statistics for each location on the pain diagram.

	Mean Number of patients with this distribution	Standard. Deviation
Groin R	5.3	2.82
Groin L	4.1	3.21
Ant thigh R	2.3	2.56
Ant thigh L	1.6	2.27
Knee R	2.3	2.98
Knee L	1.3	2.53
Lat thigh R	2.4	2.53
Lat thigh L	2.2	2.86
Post thigh R	1.3	1.90
Post thigh L	1.0	2.37
Buttocks R	3.1	2.60
Buttocks L	1.9	2.59
Low back	3.5	2.96
Lat hip R	4.7	2.79
Lat hip L	3.8	3.22

Abbreviations include: Ant (anterior), Lat (lateral), Post (posterior) R (right), L (left)

Low back pain distribution included pain marked at L5 or above in the low back

Buttock pain distribution included pain marked below L5 but above the gluteal fold

Table 3.

Sleep and anxiety related variables for patients with hip pain and controls.

	Hip Pain		Healthy Controls
Variable	Mean	StDev	Mean	StDev	Statistical Value	P-value
Hours of sleep (hours)	6.0	1.31	6.9	.90	−3.475	.001*
ISI (0–28)	11.9	6.02	3.6	3.96	−6.55	<.001*
PASS (0–100)	30.88	19.89	12.8	11.78	−5.26	<.001*

^*Denotes a significant difference of P < .05

ISI= Insomnia Severity Index Pain Anxiety Symptoms Scale

PASS= Pain Anxiety Symptoms Scale

There were no differences in ISI (p=.80) or PASS scores (p=.62) between patients with each radiographic classification (FAI, DDH, Mixed, or no deformity) (Table 4). For patients without a deformity compared to patients with deformity, there was no difference between PASS (p=.37) and ISI scores (p=.44) (Table 5).

Table 4.

Sleep and anxiety related variables for patients with hip pain grouped by radiograph measurements

	Hip Radiograph Classification
	No deformity	FAI	DDH	Mixed Classification	F	P-value
ISI (0–28)	13.5±7.3	10.7±7.1	11.7±5.6	12.3±5.3	.34	.80
PASS (0–100)	36.6±23.1	32.3±19	24.7±14.6	30.9±24	.60	.62

ISI= Insomnia Severity Index Pain Anxiety Symptoms Scale

PASS= Pain Anxiety Symptoms Scale

Table 5.

Sleep and anxiety variables for patients with hip pain grouped by radiograph measurements comparing those with and without hip deformity.

	No deformity	Deformity	t	P-value
ISI (0–28)	13.5±7.3	11.6±5.9	.91	.37
PASS (0–100)	36.63±23.05	29.50±19.75	.79	.44

Discussion

Hip pain in young- and middle-aged adults without moderate to severe radiographic hip arthritis was found to have significant cofounding disorders of insomnia and anxiety that independently are known to contribute to disturbances in pain processing and ultimately, in overall long-term outcomes. These data suggest that patients presenting with hip pain have or may develop these disorders that, if identified early, could potentially be modified by timely intervention. This is especially important because this patient population is young and at risk for long-term impairment and disability. Further, patients with hip deformity may be offered a hip preservation surgery. Treating co-founding disorders of insomnia and anxiety may improve outcomes following the surgical intervention for the structural disorder.

In adults 18 years and older, the prevalence of insomnia in the general population ranges from 19–27%.[14, 29–31] We found a similar prevalence in our cohort of asymptomatic healthy controls where 7/50 (14%) were found to have a sleep disorder on the insomnia spectrum. The term “insomnia” refers to difficulty initiating sleep, disrupted sleep, and early morning awakening.[14, 32] Insomnia has been found to be comorbid with musculoskeletal disorders and chronic pain.[6, 8–13] Patients with pain and insomnia have been found to report greater pain intensity, longer sleep onset latency, more sleep awakenings, shorter hours of sleep, and less restful sleep than patients who do not.[6, 11–13, 16, 17, 33–36] Foo and colleagues found that alertness signaling may become dysregulated in chronic pain conditions, which results in prolonged sleep loss periods and greater disruption of sleep continuity.[8, 37] Dysregulation of sleep then leads to decreased pain thresholds resulting in hyperalgesia.[8, 11–13, 16, 38] In turn, these hyperalgesic effects result in alterations in important endogenous pain modulatory pathways, leading to persistent pain and nonrestorative sleep.[8, 11, 39] In this way, pain and sleep become a “vicious circle.” A meta-analyses completed by Finan et al. concluded that sleep disturbance is actually a stronger predictor of future pain than pain is of future sleep disturbances.[8, 40] As compared to chronic pain patients without insomnia, patients with chronic pain and insomnia report more severe pain, longer duration of pain, higher levels of anxiety and depression, and worse impairment in physical and psychosocial functioning.[6, 8, 15–17] Our data suggest that young- and middle-aged adults with hip pain without associated moderate-severe radiographic hip arthritis experience cofounding insomnia placing them at risk to experience greater pain and reduced function.

Pain associated biopsychosocial effects has been well studied in people with chronic pain. In this population, pain-related anxiety correlates with affective distress, perceived lack of control, and severity of pain.[5, 41] In chronic LBP patients with fear avoidance beliefs will avoid physical activity, leading to deconditioning, disability, and decreased function.[5] Identifying fear avoidance behavior is important because these beliefs can be modified through cognitive behavioral intervention.[5, 18, 19] Leeuw et al.’s work suggests that pain catastrophizing can lead to pain related fear.[20] A deleterious cycle takes place where a patient who has negative feelings about pain develops a catastrophizing response envisioning the worst possible outcome. This leads to fear in engaging in an activity, distress from disuse and an overall negative assessment of potential outcome.[7, 42] In surgical patients, catastrophizing is associated with greater postsurgical pain and poor quality of life.[7, 43] The ability to modify catastrophizing behavior has been shown and a decrease in pain catastrophizing has been associated with a better outcome.[22–24] Similar to studies of people with chronic LBP, the data from this study suggests young- and middle-aged adults with hip pain without associated hip arthritis experience anxiety. Though not assessed in this study, the strong links of anxiety with fear avoidance and pain catastrophizing suggest that young and middle aged adults with hip pain may develop these disorders leading to impairment and disability that may become chronic. Early identification of these cofounding disorders can allow for early intervention with the potential to reduce impairments related to insomnia and anxiety thereby allowing for improved outcomes following conservative or surgical treatment for the hip disorder.

Hip disorders in young- and middle-aged adults are characterized by bony deformity with or without labral injury and are known to be a precursor to the development of osteoarthritis.[44] Studies of characteristics of patients with hip pain related to DDH and FAI with or without labral tears describe an insidious onset of pain that, on average, can take years to arrive at the appropriate diagnosis and treatment intervention.[1–3] This suggests patients with hip pain and no to minimal radiographic arthritis are at risk for cofounding sleep and anxiety disorders. Comparisons between types of hip deformity or no deformity failed to demonstrate one hip disorder was associated with a greater or lesser degree of sleep and anxiety disorders.

This study has several limitations. A small population of patients with hip pain were evaluated in this study and may not be generalizable to all populations. To address this, we recruited patients from two different tertiary university settings. The study was designed to assess a single point in time and therefore further development of sleep or anxiety disorders in this population is not fully understood. Further, this study aimed to assess a heterogeneous population of young and middle aged adults with and without hip deformity at the time of their initial presentation to a physiatrist with expertise in the evaluation and treatment of hip disorders. We did not describe the eventual course of their care with regards to interventions completed and outcomes. Some of these patients may have responded to conservative treatment and some may have been referred for surgical intervention. However, the data suggest that on average, a young- and middle-aged adult with hip pain and no to minimal radiographic hip arthritis may have unrealized co-morbid disorders such as insomnia and anxiety that may inhibit their response to treatment of the hip.

Conclusion

Young- and middle-aged adults with hip pain and no to minimal radiographic hip arthritis have significant co-morbid insomnia and anxiety disorders as compared to age- and gender-matched asymptomatic healthy controls. These findings were not unique to a specific bony deformity (FAI, DDH, mixed hip deformity) or no hip deformity. Early identification of insomnia and anxiety disorders in this population of patients with hip pain offers an opportunity for treatment to be initiated early and assist in improving pain and function outcomes following conservative or surgical treatment. Future studies are needed to assess response to interventions intended to modify co-existing insomnia and anxiety in this patient population and measure the overall impact on pain, function and quality of life measures.