Rheumatology & Internal Medicine
Rheumatic coxitis
Rheumatic coxitis refers to inflammatory arthritis of the hip—the hip joint—that occurs as part of a systemic inflammatory or autoimmune rheumatic disease, as opposed to mechanical hip disorders (primary coxarthrosis, dysplasia), infectious (septic coxitis), or metabolic (chondrocalcinosis, gout). The hip, a deep weight-bearing joint enclosed by a strong joint capsule, is less frequently affected than the small joints in most chronic inflammatory rheumatic conditions—but its involvement is of particular clinical importance because it directly compromises walking, independence, and quality of life, and can progress, in the absence of appropriate treatment, to rapid and irreversible joint destruction requiring total hip arthroplasty (THA). Ankylosing spondylitis and spondyloarthropathies are the leading cause of rheumatic coxitis in young adults, with hip-femoral involvement observed in 25 to 50% of cases over the course of the disease — often bilateral, rapidly destructive, and with a poor functional prognosis. Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis, reactive arthritis, and juvenile idiopathic arthritis (JIA) can also be complicated by coxitis. The diagnostic challenge of rheumatic coxitis is twofold: to distinguish early on between inflammatory arthritis and early-stage coxarthrosis or septic coxitis (a surgical emergency), and to identify the underlying systemic disease in order to initiate appropriate disease-modifying treatment that limits joint destruction. Hip MRI, with its ability to detect early synovitis, cartilage erosions, and enthesitis before any radiographic abnormalities appear, is the gold standard for the early diagnosis and monitoring of rheumatic coxitis.
Rheumatic diseases causing coxitis
| Illness | Hip joint involvement frequency | Specific features |
|---|---|---|
| Ankylosing spondylitis (AS) and spondyloarthritis (SpA) | 25–50 % over the course of development | The leading cause of rheumatic coxitis—coxitis is often bilateral and symmetrical (40–60% of cases); enthesitis of the hip joint capsule and synovitis; concentric cartilage destruction (global narrowing of the joint space) unlike coxarthrosis (supero-external narrowing); frequently associated with sacroiliitis and spinal involvement; HLA-B27 positive in 80–90% of cases; marker of poor overall functional prognosis for AS; response to NSAIDs and anti-TNF agents (adalimumab, etanercept, certolizumab, golimumab) and anti-IL-17A agents (secukinumab, ixekizumab) |
| Rheumatoid arthritis (RA) | 15–25 % advanced forms | Late-onset hip involvement in RA — generally occurs after several years of disease progression or in severe, uncontrolled forms; synovitis with peripheral erosions and concentric joint space narrowing; eroded subchondral bone; context of predominant distal polyarthritis (hands, wrists, feet); often positive RF and anti-CCP; conventional disease-modifying drugs (methotrexate) and biologics (anti-TNF, abatacept, rituximab, tocilizumab, baricitinib) |
| Psoriatic Arthritis (PsA) | 10-20 % | Possible asymmetric oligoarticular involvement including the hip; axial forms (sacroiliitis, spondylitis) are often associated; erosive and proliferative lesions (osteophytes and erosions coexist—a «pencil-in-a-cup» appearance in small joints but less typical impingement in the hip); cutaneous or nail psoriasis often present; HLA-B27 in 40–50% of axial forms |
| Systemic lupus erythematosus (SLE) | 5-15 % | Rare but serious lupus-associated coxitis—usually non-erosive synovitis; a feared complication: aseptic osteonecrosis of the femoral head (avascular necrosis) due to prolonged corticosteroid therapy or vasculitis of the capsular vessels (antiphospholipid syndrome)—occurs in 5–10% of lupus patients; Hip pain in a patient with lupus should always prompt an urgent MRI to rule out avascular necrosis |
| Juvenile idiopathic arthritis (JIA) | Variable by subtype | Coxitis is common in polyarticular RF+ and systemic onset forms; risk of rapid coxal destruction and irreducible hip flexion contracture in untreated JIA; THA often necessary in young adults with severe JIA; challenge of acetabular and femoral head growth in early pediatric forms |
| Reactive arthritis (formerly Reiter's syndrome) | 10-15 % | Aseptic arthritis triggered by a distant infection (enterobacteria — Salmonella, Yersinia, Shigella ; Urogenital infections Chlamydia trachomatis); asymmetric, oligoarticular, primarily affecting the large joints of the lower extremities; classic triad (arthritis + urethritis + conjunctivitis); HLA-B27 in 60–80% of cases; usually resolves within 3–6 months, but chronic forms occur in 15–20% of cases |
| Psoriatic arthritis, enteropathic arthritis (IBD) | Variable | Enteropathic arthritis associated with Crohn's disease or ulcerative colitis — axial involvement (sacroiliitis, spondylitis) with possible coxitis; inconsistent parallelism with digestive activity for axial forms; anti-TNF effective on both components |
Risk factors and at-risk populations
- Ankylosing spondylitis with severe axial involvement: coxitis is the main marker of poor functional prognosis in AS — patients with early bilateral hip involvement show progression toward joint fusion and ankylosis much faster than patients without hip involvement
- Uncontrolled active inflammatory disease: any rheumatic disease with persistent high inflammatory activity (elevated ESR and CRP, persistent clinical synovitis) — untreated chronic inflammation accelerates cartilage and bone destruction; early initiation of disease-modifying treatment is the main joint protection measure
- Prolonged systemic corticosteroid therapy: a major risk factor for avascular necrosis of the femoral head (corticosteroid osteonecrosis) - a frequent complication in lupus patients, transplant recipients, and patients with chronic inflammatory diseases undergoing long-term corticosteroid treatment; the cumulative dose and duration of treatment determine the risk
- HLA-B27 positive: genetic marker for predisposition to spondyloarthritis — in the presence of inflammatory hip pain in an HLA-B27+ subject, spondyloarthritis should be suspected first
- Male sex and young age in AS: AS preferentially affects young men (peak incidence 20–30 years old) with more frequent and severe hip involvement than in women
Symptoms
- Hip pain of an inflammatory nature: deep groin pain radiating to the anterior thigh, greater trochanter, or knee; typical inflammatory characteristics—pain predominating at rest and in the latter half of the night with nocturnal awakening, prolonged morning stiffness (> 30–60 minutes), improvement with physical activity and NSAIDs; to be distinguished from mechanical coxarthrosis pain (worsens with walking, relieved at rest, no prolonged stiffness).
- Progressive limitation of hip mobility: reduced internal rotation (first movement limited—an early and sensitive sign of hip involvement), flexion, abduction, and external rotation; hip flexion contracture (limitation of extension) in advanced forms—responsible for compensatory lumbar hyperlordosis and gait disturbances
- Antalgic hindlimb lameness: painful lameness with reduced stance phase on the affected side; Trendelenburg's limp (gluteal muscle insufficiency) in severe cases with muscle atrophy
- Hip joint effusion: less easily detectable clinically than at the knee due to the joint's depth; can manifest as pain on palpation of the groin and on passive movement; detectable by ultrasound or MRI
- Systemic and extra-articular signs according to the causal disease: morning spinal stiffness and alternating buttock pain (SpA); small joint polyarthritis (RA); skin or nail psoriasis (PsA); mucocutaneous, renal, or serosal manifestations (lupus); acute anterior uveitis (SpA, PsA); enterocolopathy (enteropathic arthritis)
- Patrick's 4th sign (FABER) positive: hip flexion, abduction, and external rotation - groin pain reproduced by this maneuver in case of coxitis; useful for routine clinical evaluation but not very specific
ℹ️
The inflammatory nature of hip pain is the key element in diagnostic orientation: pain that is predominant at night, prolonged morning stiffness, and improvement with activity suggest rheumatic coxitis, while mechanical pain that worsens with walking and is relieved by rest suggests coxarthrosis. However, advanced rheumatic coxitis can take on a mixed character due to secondary cartilage lesions — MRI is then essential to distinguish the two components.
Diagnosis
- Inflammatory and immunological biological assessment: CBC (neutrophilic leukocytosis, inflammatory anemia), ESR, CRP, fibrinogen (inflammatory syndrome); rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (anti-CCP) - RA; ANA, anti-native DNA, complement C3/C4, ANCA - lupus and vasculitis; HLA-B27 - spondyloarthropathies; joint aspiration if effusion is accessible (cytological analysis of fluid: > 2,000 WBC/mm³ with lymphocytic or polymorphonuclear predominance depending on the disease - to distinguish from septic arthritis: > 50,000–100,000 WBC/mm³)
- Standard radiograph of the pelvis and hips (AP and Lauenstein views): evaluation of the coxofemoral joint space (concentric narrowing suggestive of inflammatory coxitis vs. superolateral narrowing of coxarthrosis), subchondral bone erosions, osteophytes, sacroiliitis (narrowing and irregularity of the sacroiliac joints - New York stages 0 to IV), periarticular calcifications; normal in early forms
- Pelvic and hip MRI with gadolinium injection: reference examination for early detection of coxitis — visualizes synovitis (contrast enhancement of thickened synovium), joint effusion, subchondral bone marrow edema (active inflammatory signal), early cartilage and bone erosions, active sacroiliitis (bone marrow edema of the sacroiliac joints), and aseptic femoral head osteonecrosis (subchondral band T2 hyperintensity — early sign); essential before any major therapeutic changes
- Hip ultrasound: detection of coxal joint effusion (sensitive for even small effusions), synovial thickening, associated trochanteric bursitis; guidance of coxal intra-articular infiltrations (joint depth making morphological guidance essential); less effective than MRI for bone and cartilage evaluation
- Pelvic and hip scan: assessment of structural bone lesions (erosions, geodes, sclerosis) and sacroiliitis (early stages); useful before hip replacement for surgical planning; irradiating – reserved for situations where MRI is contraindicated
- Bone scintigraphy and FDG PET-CT: useful for assessing the extent of systemic inflammatory disease or the search for a prosthetic infection; hyperfixation of active sacroiliac and hip joints
Treatment
- Treatment of the causal disease — cornerstone: the main objective is the control of systemic inflammatory activity to prevent hip joint destruction; treat-to-target measure — remission or low disease activity according to ASDAS (AS) or DAS28 (RA) criteria; therapeutic delay = irreversible joint destruction
- NSAIDs at full dose: first-line symptomatic treatment for spondyloarthropathies — effective for pain, stiffness, and possibly for structural progression (anti-osteoproliferative effect discussed in AS); naproxen, diclofenac, indomethacin; continuous intake recommended in active AS (superior to on-demand intake); gastric protection (PPI) if digestive risk factors
- Conventional synthetic disease-modifying antirheumatic drugs (csDMARDs): methotrexate — effective in RA (reduced hip involvement with overall disease control); sulfasalazine — effective in peripheral forms of spondyloarthritis; hydroxychloroquine — lupus; methotrexate and azathioprine have little effect on pure axial forms of AS
- Biotherapies and targeted therapies: anti-TNF-α (adalimumab, etanercept, infliximab, certolizumab, golimumab) — gold standard treatment for severe AS and RA refractory to csDMARDs; anti-IL-17A (secukinumab, ixekizumab) — AS with hip involvement, particularly in case of failure or contraindication to anti-TNFs; anti-IL-23 (risankizumab, guselkumab) — psoriatic arthritis; abatacept, rituximab, tocilizumab — RA depending on profile; JAK inhibitors (baricitinib, upadacitinib, tofacitinib) — refractory RA and AS
- Intra-articular hip corticosteroid injection under ultrasound or fluoroscopic guidance: symptomatic local treatment — rapid relief of pain and effusion; short-term benefit (4–12 weeks) well demonstrated; should not be repeated too frequently (risk of long-term cartilage damage, infectious risk); maximum of 1 to 3 injections per site per year; repository corticosteroid (triamcinolone acetonide, methylprednisolone) + local anesthetic
- Kinesiotherapy and functional rehabilitation: maintenance of hip joint range of motion (prevention of hip flexion contracture and ankylosis in RA) - gentle stretching of hip flexors and adductors; strengthening of the gluteus medius and peri-articular hip muscles; balneotherapy (exercises in warm water pool) - particularly beneficial in painful coxitis due to joint unloading in an aquatic environment; regular adapted physical activity
- Total hip arthroplasty (THA): indicated in cases of severe joint destruction with major functional impairment resistant to medical treatments — functional survival of 15–20 years in recent series; generally good functional results in rheumatic coxitis; higher risk of infectious complication than in primary coxarthrosis due to immunosuppression; interruption of biotherapies in the peri-operative period according to SFR/EULAR recommendations
Signs requiring urgent medical assessment
Any acute febrile hip pain in a patient on immunosuppressants or biologics requires an urgent workup to rule out septic hip arthritis. This is a critical differential diagnosis because it is a surgical emergency (joint lavage) with a compromised functional prognosis without immediate treatment. Diagnostic hip aspiration with cytological and bacteriological analysis of synovial fluid is the gold standard. Similarly, acute hip pain in a lupus patient on corticosteroids should prompt an urgent MRI to rule out early aseptic femoral head osteonecrosis, the early treatment of which (surgical decompression) can prevent head collapse and the need for a total hip arthroplasty.
For a rheumatological evaluation of inflammatory hip pain, an MRI prescription, or a referral to a rheumatologist, Clinique Omicron offers consultations at our Quebec branches and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron physicians evaluate hip pain of an inflammatory nature, prescribe appropriate biological and imaging tests (X-ray, pelvic MRI, immunological screening), initiate pain management, and refer patients to rheumatologists and orthopedic surgeons based on the diagnosis and severity. Consultations are available at our Quebec branches as well as through telemedicine for the entire province. To make an appointment, visit cliniqueomicron.ca.
The content of this page is provided for informational purposes only and does not substitute for the advice of a qualified healthcare professional. The diagnosis of rheumatic coxitis requires specialized rheumatological evaluation to identify the underlying systemic disease and initiate appropriate disease-modifying treatment.
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