Learning Objectives/Outcomes:After participating in this CME/CNE activity, the provider should be better able to:
1. Describe the anatomy of the hip joint and pathophysiology of hip-related pain.
2. List the diagnostic tests for hip-related pain and indications for each.
3. Evaluate the options for hip-related pain management, including surgical and nonsurgical therapies.
The hip is the largest joint of the body and carries the weight of the body in static and dynamic activities. Described as a multiaxial ball-and-socket synovial joint, the hip performs a wide range of movements including flexion, extension, adduction, abduction, medial rotation, and external rotation. It is not surprising that when the hip or associated movement is painful, the pain significantly affects function and quality of life. Assessment, diagnostic workup, and thorough multimodal treatment of hip pain are essential for restoring function and mobility. This article provides an overview of assessment techniques, diagnostic testing, and options for treatment, including surgical and nonsurgical approaches.
Overview of Hip Pain
It is estimated that hip pain affects more than 15% of adults 40 years and older, with the prevalence increasing with age. Hip pain disproportionately affects women.1 Although less common, hip pain in younger adults and children can be severely disabling and typically associated with femoroacetabular impingement (FAI) syndrome, hip dysplasia, and early osteoarthritis.2 The differential diagnosis for hip pain is broad, necessitating a thorough history and physical examination.
The multiaxial motion of the hip joint, along with its load-bearing function, makes it vulnerable to wear and tear. To protect from shear and compressive forces, the articular surfaces are covered by hyaline cartilage and the acetabular rim is lined by fibrocartilage (labrum) to add depth and stability to the femoroacetabular joint.3 In addition, multiple muscle groups surround the hip to provide stability and allow motion.
The muscle groups involved in specific motions include:
* Flexion-iliopsoas, rectus femoris, pectineus, sartorius;
* Extension-gluteus maximus, hamstring; and
* Abduction, adduction, and internal and external rotation-gluteus medius, gluteus minimus, piriformis, obturator externus, obturator internus, quadratus femoris.
Innervation of the hip joint by the sciatic, femoral, and obturator nerves can make it difficult to discern whether pain originates in the spine or hip, and because these nerves also innervate the knee, pain can be referred to the lower extremity. The ligaments of the hip joint also contribute to stability of the joint (Figure 1). The iliofemoral ligament is Y-shaped and connects the pelvis to the femoral head at the front of the joint, whereas the pubofemoral ligament is triangular and extends between the upper portion of the pubis and iliofemoral ligament to connect the pubis to the femoral head. The iliotibial band, a long tendon, runs from the femur at the hip to the knee and serves as an attachment site for many hip muscles.
Assessment of Hip Pain
A detailed history and physical examination should narrow the differential diagnosis and guide the selection of diagnostic testing.4 Patient demographic information, including age, biological sex, occupation, and daily activities should be collected. The practitioner should also ask the patient about the onset and location of pain; characteristics of the pain; precipitating, provoking, and alleviating factors; and impact on daily functions.
Information should be obtained on history of congenital hip deformities, recent/past trauma, musculoskeletal injury or surgery, ability to bear weight, or popping/clicking sensations.
Prescribed and over-the-counter medication use, nutritional therapies, herbals and supplements, and substance use should be ascertained. Patients should be asked about a birth history of developmental dysplasia of the hip or risk factors such as first-borns, females, breech births, and oligohydramnios.5
A history of childhood obesity or endocrine disorders may raise suspicion for slipped capital femoral epiphysis. Risk factors for avascular necrosis should also be considered, including asking the patient about corticosteroid use, alcohol use, diving, HIV/AIDS, or antiretroviral therapy.
A thorough musculoskeletal physical examination entails the steps of observation, palpation, range of motion, motor strength, sensation, and reflexes, followed by stability and provocative maneuvers.
A positional sequence to the examination can be useful for providing a systematic approach by performing specific techniques while the patient is in a standing position, seated, supine, lateral, and prone.6 Tenderness over the bursa of the greater trochanter and over the iliotibial band insertion on Gerdy tubercle can provide evidence of bursitis or iliotibial band tightness, respectively, whereas groin tenderness may represent hernia, iliopsoas disease, or inflamed hip capsule.5
The relationship between pain and hip movement and position during the physical examination can indicate whether the hip is involved-meaning an intra-articular pathology-or whether the pain is likely due to a pathology outside the hip joint (extra-articular).2
Specific provocative maneuvers can be helpful in locating the most likely source of pain. Although no single maneuver is diagnostic, the collective evaluation of pain during different movements and positions provides a profile to guide the selection of diagnostic testing (Table 1).
Age-related injuries and pathologies can help to narrow the differential diagnosis.3 In children and adolescents, the most common reasons for pain include FAI syndrome, hip dysplasia, avulsion fractures, apophyseal or epiphyseal injuries, and early osteoarthritis. For young individuals presenting with progressive hip pain or night pain, immediate radiographs should be procured to evaluate for osteosarcoma or Ewing sarcoma, which can progress quickly in some cases.
In later adulthood, hip pain is most commonly associated with musculotendinous strain, ligamentous sprain, contusion, or bursitis. Older adults should be evaluated for degenerative osteoarthritis or fractures, particularly in those with a history of osteoporosis or falls.
The location of pain can also assist with narrowing the differential diagnosis. Anterior hip and groin pain, indicated by the patient making a C sign when describing their pain, may be caused by intra-articular pathology such as FAI, osteoarthritis, and hip labral tears.2 The C sign is demonstrated when patients place their hand around the anterolateral hip where the pain is located, with the thumb and forefinger making the shape of a "C." Anterior groin pain that is sharp (knife-like) and pinching is most commonly associated with acetabular labrum injury or irritation caused by FAI or hip dysplasia.7
Patients may describe pain while sitting that is aggravated by confined spaces.2 Catching, popping, locking, or grinding of the hip may also be described by the patient.
A more insidious onset of anterior groin pain that is worse with weight bearing and relieved with rest is a common presentation of osteonecrosis of the femoral head.
Stress fractures are likely associated with overuse, whereas hip osteoarthritis often presents as stiffness, with night pain reported.8
Medial groin pain with vague anterior pelvic pain and tenderness can be caused by osteitis pubis, or inflammation of the pubic symphysis, and is commonly associated with kicking sports.2
Posterior pain is most often caused by piriformis syndrome, sacroiliac dysfunction, lumbar radiculopathy, or ischiofemoral impingement and vascular claudication. Lateral hip pain is most commonly associated with greater trochanter pain syndrome, trochanteric bursitis, or iliotibial band friction syndrome.
Diagnostic Testing
Plain radiographs of the hip, including anteroposterior view of the pelvis and a frog-leg lateral view of the symptomatic hip, should be obtained for suspicion of acute fracture, dislocation, or stress fracture.9 In the presence of persistent pain, conventional MRI may detect soft-tissue abnormalities. Detection of labral tears is more accurate with magnetic resonance arthrography, which provides a sensitivity of 90% and a specificity of 91%, compared with conventional MRI with a sensitivity of 30% and a specificity of 36%.10 Ultrasonography can be used to evaluate tendons, identifying bursitis or joint effusions, as well in safely performing joint injections and aspiration.11 Electromyelography is helpful in identifying nerve compression, such as with lumbar radiculopathy.
For patients with suspected osteoarthritis, intra-articular injection of a local anesthetic agent may provide temporary pain relief and can be used to differentiate from other extra-articular causes of pain.4 If infection is suspected, aspiration of synovial fluid can be a crucial diagnostic tool used to guide treatment.
Nonsurgical Management of Hip Pain
For patients without mechanical deformity, nonsurgical management may encompass activity modification, physical therapy, chiropractic or osteopathic therapy, and weight loss when indicated.5 Administration of nonopioid analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs), thermal therapy, and topical anesthetics can be useful for providing relief of pain. Joint injections with corticosteroids or anesthetics administered under imaging may also be an option for reducing pain and/or delaying the need for surgery.
Osteoarthritis
Osteoarthritis is one of the most common degenerative joint conditions and is caused by inflammation and/or injury resulting in breakdown of cartilage tissue. The pain due to osteoarthritis of the hip is usually described as a dull aching that worsens with activities.
Hyaluronic acid injection is a common treatment for patients with ongoing or chronic hip pain.12,13
A small clinical trial of a new hybrid low- and high-molecular-weight hyaluronic acid for injection was recently investigated for efficacy in the treatment of hip osteoarthritis.14 In the study, 20 patients with moderate-severe hip osteoarthritis received an intra-articular ultrasound-guided injection of the new hyaluronic acid compound at baseline and 40 days. Patients were followed up for a period of 6 months. Data were compared with a sex-, age- and severity-matched cohort treated with high-molecular-weight hyaluronic acid. A significant improvement in pain (P < 0.04) and functional outcomes (P < 0.02) was seen after 6 months, providing initial evidence on the efficacy of the combination form of hyaluronic acid.
A prospective randomized double-blind multicenter study evaluated the effectiveness of abobotulinumtoxinA injections versus placebo on hip range of motion, pain, and quality of life.15 Patients with hip osteoarthritis were randomized to the treatment (n = 32) or placebo group (n = 15). The treatment group received 400 U of abobotulinumtoxinA injected into the adductor muscles, and the placebo group received placebo solution, with all assessments performed at 4 weeks.
At the follow-up assessment, patients in the abobotulinumtoxinA group showed significant improvement in hip range of motion and pain compared with baseline and the placebo group. No adverse effects were noted in either group. The results suggest that abobotulinumtoxinA may be an effective treatment for increased function and pain in patients with osteoarthritis of the hip.
Arthroplasty is a surgical procedure in which the articular surface of the joint is replaced, remodeled, or realigned to improve pain and function in patients with moderate to severe osteoarthritis. In a randomized controlled trial, 80 patients were assigned to either a posterior or a modified direct lateral arthroplasty for treatment of hip osteoarthritis.16 Patient-reported outcomes were collected at 3, 6, and 12 months, postoperatively. They found no significant differences in patients treated with either surgical approach. However, limping was more severe in the lateral arthroplasty patients.
Arthroplasty and Postoperative Pain Management
Pain management after hip arthroplasty can be challenging. In one study, local infiltration analgesia was investigated as an approach to decrease the need for postoperative opioids after osteosynthesis of extracapsular hip fracture.17
In this study, 49 patients undergoing osteosynthesis with a sliding hip screw were randomized into 2 groups in a double-blind study, with 23 patients receiving ropivacaine and 26 receiving saline in an intraoperative infusion, followed by 6 postoperative injections through a wound catheter in 8-hour intervals. Intraoperative infiltration with 200-mg ropivacaine and postoperative repeated infiltration with 100-mg ropivacaine did not result in a statistically significant difference in postoperative analgesic use or pain scores.
In a study of the postoperative patterns of opioid use after hip surgery, data over a 12-year period were examined in military and civilian population.18 The number of days postoperative to the last opioid prescription (date of the last opioid prescription - date of surgery) and the days' supply variable (strength and daily frequency) were used to cluster patients into a short-duration, high total days' supply or long-duration, lesser total days' supply.
The long-duration, lesser total days' supply was associated with lower costs and use, giving rise to questions regarding whether a longer opioid taper can provide optimal patient outcomes compared with an abrupt taper.
In another study that examined opioid use in smokers versus nonsmokers after total hip arthroplasty (n = 248), it was found that smokers demonstrated significantly higher opioid consumption in the immediate postoperative and 90-day postoperative periods.19 This study adds to the evidence and importance of addressing preoperative smoking cessation as part of a thorough pain management plan. Gaffney and colleagues20 recommend a multimodal perioperative pain management plan that consists of cryotherapy, NSAIDs, neuromodulators, peripheral nerve blocks, intra-articular injections, and spinal or epidural anesthesia to reduce opioid consumption and improve pain outcomes after hip arthroplasty.
Hip Dysplasia
The umbrella term of hip dysplasia encompasses a spectrum of abnormal hip morphology, including acetabular version and proximal femoral deformities.5 Depending on the developmental stage of the patient and severity of the condition, hip dysplasia may be treated with bracing, casting, or operative procedures to prevent dislocation, reduce pain, and improve physical functioning.
Among 55 children receiving open or closed reduction or treatment with bony surgery for hip dysplasia, there were no identified factors playing a role in preventing early dislocation. However, the experience of the treating surgeon and technical factors are known to influence the rate.21
Slipped capital femoral epiphysis is a common adolescent hip disorder causing deformity of the proximal femur and early osteoarthritis.22 Surgical correction of this disorder, including use of the modified Dunn procedure, can cause significant risk for avascular necrosis, necessitating investigation of other approaches to decrease this risk.23 In a retrospective study that involved 19 patients (15 male, 4 female), the use of the Imhauser osteotomy combined with osteochondroplasty via surgical hip dislocation approach was found to be a safe and effective treatment that mitigated the risk of avascular necrosis.24 Patients treated in a delayed fashion had similar outcomes, providing surgeons with an option to use this approach for patients who present with either acute or chronic symptomatology.
Femoroacetabular Impingement
Patients with FAI often describe an insidious onset of pain that worsens with sitting, leaning forward, or rising from a seated position.2 The pain is caused by impingement between the femoral neck and the anterior rim of the acetabulum during normal range of functional hip movement due to subtle deformities in the hip shape. Movements in flexion adduction and internal rotation typically cause pain and can be detected using the flexion, abduction, and external rotation (FABER) test, and the flexion, adduction, and internal rotation (FADIR), log roll, and straight-leg raise against resistance. Impingement can irritate and damage the acetabular labrum and adjacent acetabular cartilage, leading to early osteoarthritis.
Three types of FAI have been described as25:
1. Cam type-asphericity of the femoral head with widening of the femoral neck;
2. Pincer type-overcoverage of the anterosuperior acetabular wall, a deep pocket; and
3. Mixed type-a combination of cam and pincer deformities.
In the general population, cam-type FAI is more common in young men, whereas pincer-type FAI is more common in middle-aged women.26
Greater Trochanteric Pain Syndrome
Patients with greater trochanteric pain syndrome present with pain over the greater trochanter that may limit lying on the affected side and interferes with sleep, and they may describe mild morning stiffness with an increasing pattern of pain that worsens over the day.5 Greater trochanteric pain syndrome is typically associated with iliotibial band thickening, bursitis, and tears of the gluteus medius and minimus muscle attachment.27-29
A literature review that included 209 patients with a mean age of 58.4 years was conducted to evaluate the evidence on use of platelet-rich plasma for reducing pain and increasing function in adults with greater trochanteric pain syndrome.30 Most were females with diagnosis made using ultrasound or MRI and the minimum duration of symptoms was 3 months.
After injection of platelet-rich plasma, significant improvements in pain and function were reported at 3 and 12 months compared with corticosteroid injection. Many of the studies to date lack adequate power, and most of the studies did not describe the details regarding the platelet-rich plasma system they used.
Labral Tear
The labrum is a ring of cartilage that forms the outer rim of the hip socket and acts like a rubber seal. Athletes and patients with hip structural abnormalities or recent trauma are at higher risk of having a labral tear.31 Hip labral tears can cause dull or sharp groin pain that may radiate to the lateral hip, anterior thigh, and buttock. Some patients report catching or clicking of the hip. Although it may present acutely after a traumatic event, the pain usually has an insidious onset. Nonsurgical treatment options are attempted to relieve pain and increase function. With persistent symptoms, arthroscopic surgery may be used for refixation, reconstruction, and/or debridement.
Osteonecrosis
Legg-Calve-Perthes disease is an idiopathic osteonecrosis of the femoral head in children 2 to 12 years of age, with more males affected than females (4:1). Osteonecrosis risk factors in adults include smoking, alcoholism, corticosteroid use, HIV, sickle cell disease, and systemic lupus erythematosus. Pain is usually a presenting symptom, although range of motion and mobility can become limited as the disease progresses. Nonopioid analgesics and rest are typically used initially to relieve pain, whereas hip decompression and bone grafting may be performed surgically to reduce the amount of necrosis. Hip resurfacing surgery or total hip replacement may be necessary for long-term recovery to maintain functional status.
Piriformis Syndrome
The piriformis muscles lie beneath the gluteal muscles and over the sciatic nerve. Irritation of the sciatic nerve around the sciatic notch (where it passes) or due to compression from the piriformis muscle causes the classic signs of buttock pain that worsens with sitting or walking.32 Tenderness of the sciatic notch to palpation and the positive log roll test are indicative of piriformis syndrome on examination. Treatment entails stretching, NSAIDs, thermal therapy, and/or physical therapy, and-for moderate-severe or persistent symptoms-muscle injection of local anesthetics or surgical release of the piriformis muscle.
Stress Fractures
Stress fractures are commonly caused by repetitive weight-bearing exercise and usually present as anterior hip or groin pain that is worse with activity.2 Typical treatment includes rest or cessation of the activity that is causing the pain to worsen. The location of the stress fracture plays a role in the consideration of treatment options.
Transient Synovitis and Septic Arthritis
In patients who present with acute onset of hip pain that impairs weight bearing, a diagnosis of transient synovitis or septic arthritis should be suspected. The joint may be swollen, and the patient may or may not present with a fever. The risk factors for septic arthritis include recent joint surgery or history of joint prosthesis, older than 80 years, diabetes mellitus, and rheumatoid arthritis. To evaluate for infection in these patients, blood work should be performed and include complete blood count, erythrocyte sedimentation rate, and C-reactive protein. Hip aspiration with guided imaging is also recommended.33 Septic arthritis is most commonly caused by Staphylococcus aureus infection, but definitive treatment should be ascertained by aspiration of synovial fluid or debridement of the joint in the operating room. Antibiotic treatment is typically indicated for a prolonged period.
Conclusion
Hip pain can have many causes, challenging even the most astute clinicians to use their full breadth of diagnostic reasoning to identify a specific pathology and deliver effective treatment. The physical examination is crucial for narrowing the differential diagnosis and selecting the appropriate diagnostic testing/imaging to perform. Pain management is an important part of the overall treatment plan and should include nonopioid analgesics and activity modification, and active and passive therapies. Physical and occupational therapists and other rehabilitation specialists play an important role in improving pain and function for patients with hip pain, whether the plan of care is surgical or nonsurgical.
References