What Is Hip Osteoarthritis?
Hip osteoarthritis (OA), also called coxarthrosis, is the progressive degeneration of the coxofemoral joint — the joint between the femoral head and the acetabulum of the pelvis. It is the second most common location of OA, after the knee.
The hip joint is one of the largest and most stable in the body, a spheroid (ball-and-socket) joint. It supports loads of up to 5-8 times body weight during activities such as running and jumping. This high mechanical demand contributes to OA development over time.
Unlike the knee, where OA is frequently primary (without identifiable cause), hip OA has an important secondary component: conditions such as femoroacetabular impingement, acetabular dysplasia, and avascular necrosis can precede and accelerate the development of arthrosis.
High-Demand Joint
The hip supports loads of 5-8 times body weight during vigorous activities, requiring cartilaginous integrity.
Impact on Mobility
Loss of internal rotation is the first sign of hip OA. Progressive limitations affect gait and daily activities.
Frequent Secondary Causes
Femoroacetabular impingement, dysplasia, and avascular necrosis are common causes, especially in younger patients.
Epidemiology
Hip OA prevalence increases with age, affecting about 10% of the population over 60. It is slightly more common in men up to age 50 (due to secondary causes such as femoroacetabular impingement) and more common in women after that age.
Risk factors include age, obesity, family history, heavy-load occupational activities, anatomic malformations (dysplasia, femoroacetabular impingement), prior injuries, and Legg-Calve-Perthes disease in childhood. Genetics account for up to 60% of hip OA susceptibility.
Pathophysiology
The coxofemoral joint is lined by thick hyaline cartilage (2-4 mm) and has an acetabular labrum — a fibrocartilaginous ring that deepens the acetabulum and increases stability. Hip cartilage is nourished by synovial fluid, since it has no direct blood supply.
Mechanisms of Degradation
In primary OA, cartilage degeneration follows the same pattern described in the knee: imbalance between matrix anabolism and catabolism, driven by metalloproteases and pro-inflammatory cytokines. The superolateral region of the femoral head is most frequently affected, as it is the área of greatest load concentration.
Femoroacetabular impingement (FAI) is an increasingly recognized secondary cause. In CAM type, a bony prominence at the head-neck junction of the fêmur causes abrasion of the acetabular cartilage during flexion. In PINCER type, excessive acetabular coverage compresses the labrum and peripheral cartilage.
Acetabular dysplasia, with insufficient coverage of the femoral head, concentrates load over a smaller área, accelerating cartilaginous degeneration. It is an important cause of early OA in young women.
Symptoms
The main symptom of hip OA is pain, typically located in the groin (inguinal área). Many patients confuse hip pain with pain in the lateral trochanteric region or in the buttocks, which frequently have other causes.
Symptoms of Hip Osteoarthritis
- 01
Groin pain (inguinal)
The most typical location of articular hip pain. May radiate to the anterior thigh.
- 02
Pain on starting to walk
Pain in the first steps after standing up, which improves as walking continues ("start-up pain").
- 03
Limitation of internal rotation
First movement lost in hip OA. Difficulty crossing the legs or putting on socks.
- 04
Claudication (limping)
Gait alteration with trunk inclination toward the affected side (Trendelenburg gait).
- 05
Pain when climbing stairs or rising from a chair
Activities requiring hip flexion under load provoke significant pain.
- 06
Brief morning stiffness
Stiffness on waking that lasts less than 30 minutes, improving with movement.
- 07
Referred knee pain
Up to 20% of hip OA patients have referred knee pain, which can lead to misdiagnosis.
- 08
Limb shortening
In advanced stages, cartilage loss and femoral head collapse can cause limb-length discrepancy.
Diagnosis
Hip OA diagnosis is based on the combination of typical symptoms, physical exam showing limited movement (especially internal rotation), and radiographic confirmation. MRI may be useful in early stages when the radiograph is normal.
🏥ACR Criteria for Hip OA
Fonte: American College of Rheumatology
Clinical-Radiographic Criteria
Hip pain + at least 2 of the 3 remaining criteria- 1.Hip pain on most days of the past month
- 2.Femoral or acetabular osteophytes on radiograph
- 3.ESR (erythrocyte sedimentation rate) less than 20 mm/h
- 4.Joint space narrowing on radiograph
Differential Diagnosis
- 1.Trochanteric bursitis (lateral, not inguinal pain)
- 2.Isolated labral tear (pain with clicking)
- 3.Avascular necrosis (acute pain, MRI required)
- 4.Stress fracture (runners, osteoporosis)
- 5.Referred pain from lumbar spine (L2-L3 radiculopathy)
- 6.Inflammatory arthritis (stiffness > 60 min)
IMAGING STUDIES IN HIP OA
| TEST | INDICATION | TYPICAL FINDINGS |
|---|---|---|
| AP radiograph of pelvis | Standard initial evaluation | Joint space reduction, osteophytes, subchondral sclerosis, cysts |
| Magnetic Resonance Imaging | Normal radiograph with symptoms, suspicion of FAI or necrosis | Marrow edema, labral tear, cartilage, avascular necrosis |
| Computed Tomography | Preoperative planning | Detailed bony anatomy, acetabular version |
| Ultrasonography | Evaluation of joint effusion, guidance for injection | Effusion, synovitis, bursitis |
DIFFERENTIAL DIAGNOSIS
Differential Diagnosis
Trochanteric Bursitis
Read more →- Lateral pain over the greater trochanter
- Pain on palpation of the trochanter
- Does not improve with hip rotations
Diagnostic Tests
- Ultrasonography
- MRI
Piriformis Syndrome
Read more →- Deep gluteal pain
- Pain on piriformis compression
- No alteration on spine imaging
Diagnostic Tests
- FAIR test
Hip Rheumatoid Arthritis
Read more →- Bilateral
- Long morning stiffness
- Systemic signs
Diagnostic Tests
- RF
- Anti-CCP
- Hip radiograph
Femoral Neck Stress Fracture
- Groin pain on weight bearing
- Athletes or osteoporotic patients
- Radiograph may be initially normal
- Risk of complete fracture if undiagnosed
Diagnostic Tests
- MRI
- Scintigraphy
Low Back Pain Referred to the Hip
Read more →- Pain originating in the lumbar spine
- Hip movements do not reproduce the pain
- Positive Lasegue
Diagnostic Tests
- Lumbar spine exam
- Diagnostic block
Trochanteric Bursitis
Trochanteric bursitis (or greater trochanteric pain syndrome) is one of the most common diagnostic errors in patients with suspected hip OA. The pain is lateral, over the greater trochanter of the fêmur, with maximum tenderness on direct palpation of the trochanter. Unlike OA, bursitis pain is not in the groin, and internal rotation and flexion movements of the hip usually do not reproduce it.
A simple test: if the patient points to the pain and the finger touches the lateral hip (over the trochanter), think bursitis; if they point to the groin, think coxofemoral arthropathy. Ultrasound confirms the diagnosis and can guide therapeutic injection.
Low Back Pain Referred to the Hip
Pain referred from the lumbar spine to the hip and buttock region is extremely common and can mimic hip OA. The L2 and L3 lumbar nerve roots innervate the anterior thigh and the groin — exactly the typical location of hip OA pain. Physical exam is crucial: in referred low back pain, passive hip movements (especially internal rotation) do not reproduce the patient's pain.
An image-guided diagnostic intra-articular hip block with local anesthetic can help determine whether pain originates from the coxofemoral joint or from adjacent structures. If the block completely eliminates the pain, articular origin is confirmed.
Femoral Neck Stress Fracture
Femoral neck stress fracture is a diagnosis that cannot be missed. It occurs primarily in long-distance athletes and osteoporotic patients. Pain is in the groin, worsens progressively with load, and may be mild at first. Plain radiograph may be normal in early stages.
MRI is the test of choice for early diagnosis. The risk is progression to complete fracture with displacement, which can compromise femoral head vascularization and result in avascular necrosis. When suspected, the patient should be advised not to bear weight until a physician confirms or rules out the diagnosis.
Treatments
Treatment principles for hip OA mirror those for the knee: exercise, education, and weight loss are the foundation. Response to conservative treatment tends to be slightly weaker than in the knee, and arthroplasty is needed more frequently.
TREATMENT OPTIONS
| TREATMENT | MECHANISM | EVIDENCE | RECOMMENDATION |
|---|---|---|---|
| Therapeutic exercise | Strengthening of abductors and stabilizers | Strong (level A) | First line — all patients |
| Weight loss | Reduction of joint load | Strong (level A) | Patients with overweight |
| Hydrotherapy | Exercise without load, thermal analgesia | Moderate (level B) | Significant pain that limits land-based exercises |
| Topical and oral NSAIDs | Anti-inflammatory | Moderate | Topical NSAIDs less effective in the hip (deep joint) |
| Acupuncture | Neuroendocrine modulation of pain | Moderate (level B) | Adjunct to exercise |
| Intra-articular injection | Corticosteroid: direct anti-inflammatory | Moderate | Temporary relief, image-guided |
| Total arthroplasty | Prosthetic replacement of the joint | Strong | Severe OA with conservative failure |
Specific Exercises
Strengthening of the hip abductor muscles (gluteus medius and minimus) is the priority, as their weakness contributes to claudication and instability. Bridge exercises, side-lying abduction, and controlled single-leg squats are the foundation of the program.
Hydrotherapy is particularly effective in hip OA, as buoyancy reduces joint load by up to 50-80%, allowing range-of-motion exercises that would be painful on land. Water temperature (32-34 degrees C) also contributes to muscle relaxation and pain relief.
Acupuncture as Treatment
Evidence for acupuncture in hip OA is less robust than for the knee, in part because fewer studies have been conducted specifically on this joint. The NICE NG226 (2022) guidelines for osteoarthritis do not recommend acupuncture as routine treatment for OA (including hip), considering the evidence insufficient. Other guidelines (ACR, OARSI) maintain acupuncture as a conditional recommendation for OA in general. The decision should be individualized by the physician.
Acupuncture may work in hip OA through modulation of local and central pain, reduction of synovial inflammation, and improved periarticular muscle function. Needling trigger points in the gluteal muscles, tensor fascia lata, and iliopsoas can relieve referred pain and improve biomechanics.
As complementary therapy, acupuncture may be especially useful in patients awaiting arthroplasty, helping to control pain and maintain function until surgery.
Prognosis
Hip OA progresses variably. Some patients maintain stability for years, while others deteriorate more rapidly. Total hip arthroplasty, when indicated, is one of the most successful surgeries in medicine, with high satisfaction rates and durability above 25 years in 80% of implants.
Progressive Management Strategy
Level 1
PermanentBasic Measures
Regular exercise (strengthening + aerobic), weight loss, education, self-management.
Level 2
As neededAdjunctive Therapies
Targeted physical therapy, hydrotherapy, acupuncture, topical NSAIDs. Cane if needed.
Level 3
Intermittent periodsAdvanced Pharmacotherapy
Oral NSAIDs, duloxetine for chronic pain component, image-guided joint injection.
Level 4
When neededTotal Arthroplasty
Indicated when optimized conservative treatment fails to adequately control symptoms and quality of life is significantly impacted.
Myths and Facts
Myth vs. Fact
Hip pain is always on the lateral side or in the buttock.
Hip OA pain is typically in the groin (inguinal region). Lateral pain is usually trochanteric bursitis, not arthrosis.
A hip prosthesis doesn't last long and needs to be replaced.
Modern implants last more than 25 years in 80% of patients. Materials technology has advanced significantly.
After a hip prosthesis, I cannot exercise anymore.
Patients with a prosthesis can and should exercise. Walking, swimming, cycling, and golf are allowed and recommended.
Hip arthrosis only occurs in very elderly people.
Secondary causes such as femoroacetabular impingement can cause hip OA in young adults (30-40 years old).
When to Seek Medical Help
Frequently Asked Questions about Hip Osteoarthritis
Hip osteoarthritis (OA), also called coxarthrosis, is the progressive degeneration of the coxofemoral joint — between the femoral head and the acetabulum. It is the second most common site of arthrosis, after the knee. Causes are primary (no identifiable factor, more common in older adults) and secondary — femoroacetabular impingement, acetabular dysplasia, avascular necrosis, and prior injuries are important causes, especially in younger adults.
The main symptom is groin pain (inguinal region), which can radiate to the anterior thigh. Pain worsens with load (walking, climbing stairs, rising from a chair) and is accompanied by brief morning stiffness. An early sign is loss of internal rotation — difficulty crossing the legs or putting on socks. Advanced cases may show claudication. Up to 20% of patients feel referred pain in the knee.
Diagnosis is clinical-radiographic. ACR criteria require hip pain on most days, plus at least 2 of 3 findings: osteophytes on radiograph, ESR less than 20 mm/h, or joint space narrowing. Limited internal rotation on physical exam is a key sign. MRI is indicated when the radiograph is normal but symptoms are suggestive, especially to evaluate labral tear, avascular necrosis, or stress fracture.
Treatment mirrors that of the knee: therapeutic exercise (strengthening abductors and stabilizers), weight loss, education, and self-management are the foundation. Hydrotherapy is particularly useful in hip OA because it reduces joint load. Pharmacologically, topical NSAIDs are less effective than in the knee (deeper joint). Total arthroplasty, when indicated, has excellent results and durability above 25 years.
Acupuncture works in hip OA through modulation of local and central pain, reduction of synovial inflammation, and improved periarticular muscle function. Needling trigger points in the gluteal muscles, tensor fascia lata, and iliopsoas can relieve referred pain and improve biomechanics. As an adjunct to exercise, acupuncture is especially useful in patients whose pain limits adherence to the rehabilitation program.
The usual protocol is 8 to 12 sessions, 1-2 times per week. Response can be gradual. For patients awaiting hip arthroplasty, periodic acupuncture cycles (every 3-6 months) can help maintain quality of life and function until surgery. The acupuncture physician will assess response and adjust the protocol as needed.
When performed by an acupuncture physician, the safety profile of acupuncture for hip OA is generally favorable, with predominantly mild adverse events (bruising, local discomfort). As with any intervention, rare risks are described in the literature (bleeding, infection, syncope). Patients with a hip prosthesis should inform the physician to avoid needling over the implant region. Anticoagulated patients require additional care.
Yes, the combination is recommended and offers better results than isolated treatment. Acupuncture complements therapeutic exercise, hydrotherapy, and pharmacologic management. The physician may include physical therapy as part of an integrated treatment plan, under their coordination. For patients awaiting surgery, acupuncture can be particularly valuable for pain control and maintaining function.
No. Many patients maintain good function for years with adequate conservative treatment. Speed of progression varies greatly between individuals. Poor prognostic factors include bilateral OA, obesity, significant varus or valgus deformity, and severe functional incapacity. Arthroplasty is indicated when conservative treatment fails and quality of life is significantly impacted, not by radiographic criteria alone.
Seek immediate care if: you feel intense acute hip pain without apparent cause, especially if you cannot bear weight on the leg (may indicate fracture or avascular necrosis); you have hip pain with fever (may indicate septic arthritis); you notice sudden shortening of the limb; or if you have known OA and feel abrupt, disproportionate worsening of pain. In these cases, see a physician immediately, without waiting for a scheduled appointment.
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