Ankylosing Spondylitis
Jill C. Cash and Julie Barnes
Definition
A.Ankylosing spondylitis (AS) is a chronic, inflammatory joint disease that causes chronic joint pain/swelling, which primarily affects the spine and sacroiliac (SI) joints; however, larger peripheral joints can also be affected.
Incidence
A.AS occurs in approximately 1% to 2% of the general population.
B.Prevalence rates differ between races. AS occurs in approximately 0.04% to 0.06% of non-Caucasians and in approximately 0.1% to 1.4% of Caucasians.
Pathogenesis
A.Inflammation occurs at the entheses (insertion site of the ligaments and tendons of the bone) throughout the body. Primary sites of involvement include the lower back, SI joint, and lower extremities. Inflammatory cells invade the joint and erode the bone and fibrocartilage of the joints. The body responds by trying to repair the tissue, in which fibrous scar tissue is formed. The structure is replaced by the ossified scar tissue, which causes fusion of the joint; in return, flexibility of the joint is lost. The eroded joint tries to repair itself by osteoblast formation in building new bone tissue. This results in the production of new enthesis that deposits itself on top of the existing enthesis. Calcification of the spinal ligaments also occurs and the appearance of the vertebral bodies looks more square
and distinct. This is referred to as a bamboo spine.
Predisposing Factors
A.Gender (men > women, 3:1 ratio).
B.Race (Caucasians more prevalent, occurring more in the northern European countries).
C.Age: Onset of symptoms usually occurs during the early 20s. However, diagnosis usually is made several years after the onset of symptoms, more into the late 20- to 30-year range. AS rarely occurs after the age of 50.
D.Family history of AS.
E.Thought to have a genetic predisposition: Serum human leukocyte antigen (HLA)-B27 positive. Approximately 90% to 95% of patients with AS have a positive HLA-B27. However, only 5% of patients with a positive HLA-B27 develop any type of spondyloarthropathy.
Common Complaints
A.Gradual onset of low back pain with initial onset of symptoms occurring in the early 20s.
B.SI joint pain.
C.Joint pain occurring for more than 3 months, with morning stiffness.
D.Low back pain/joint pain that improves with activity, worsens with rest.
E.Dactylitis (sausage digits of the fingers/toes).
F.Enthesitis (inflammation/pain at insertion site of the tendon or ligament to the bone).
Other Signs and Symptoms
A.Peripheral joint pain and swelling.
B.Decreased range of motion (ROM) in joints/back/neck.
C.Extra-articular features such as anterior uveitis or iritis.
D.Fatigue.
E.Weight loss.
F.Shortness of breath (SOB).
G.Psoriasis.
Subjective Data
A.Ask the patient when back/joint pain began. Have symptoms been present for several months/years? At what age did pain initially begin?
B.Is pain intermittent or constant?
C.Does pain improve or worsen with activity? Inflammatory back pain improves with activity and worsens with rest.
D.Does patient have complaints of other joint pain?
E.Has the patient noted any weight gain/loss, fatigue, or fevers?
F.Any history of psoriasis or other skin rashes?
G.Any gastrointestinal (GI) changes or chronic problems such as Crohn’s disease, ulcerative colitis, or diarrhea?
H.Any pulmonary problems such as SOB, difficulty breathing, or SOB with activity?
I.Any cardiac changes or problems?
J.Any history of amyloidosis?
Physical Examination
A.Check vital signs, blood pressure (BP), pulse, respirations, and temperature as indicated.
B.Inspect:
1.Assess the cervical spine. Ask the patient to stand straight and assess the degree of cervical change. Ask the patient to perform flexion, extension, lateral flexion, and rotate the head.
2.Inspect the thoracic and lumbar spine. Note degree of chest expansion of thoracic spine. Assess lumbar spine noting the ROM with flexion/extension. Have the patient bend to the right and left side and note any difference in flexion.
3.Assess gait. If abnormal gait, assess for hip pain/involvement.
4.Inspect hands/feet for sausage digits.
5.Inspect joints in hands/wrists/feet/knees for tender, swollen joints.
C.Auscultate:
1.Heart.
2.Lungs.
D.Palpate:
1.Examine the SI joint by palpating it while lying supine and while lying on the side. Have the patient flex one knee while lying supine, and externally rotate the hip. Assess for pain at the SI joint area while pressure is applied on the knee.
2.Assess for pain at the entheses site. Assess Achilles tendon and plantar fascia areas where the tendon attaches to the calcaneus.
Diagnostic Tests
A.Serum blood work:
1.HLA-B27 commonly positive.
2.Rheumatoid factor (RF) usually negative.
3.C-reactive protein (CRP).
4.Erythrocyte sedimentation rate (ESR).
5.Complete blood count (CBC).
6.Comprehensive metabolic panel (CMP).
7.Creatinine kinase.
8.Alkaline phosphatase.
9.Complement levels (C3, C4).
B.Radiographic studies:
1.X-ray of cervical/thoracic/lumbar spine and pelvis:
a.In AS, the spine is noted to have squaring
of the vertebral bodies.
b.Sclerosis of the SI joint: Sacroiliitis grade 2 or above (grade 2 is bilateral sacroiliitis).
2.X-ray of peripheral joints: Erosions noted in the larger joints, loss of joint space, sclerosis.
3.MRI of SI joints.
4.Bone mineral density (BMD) screening: High incidence of osteoporosis noted in patients diagnosed with AS.
Differential Diagnoses
A.AS.
B.Reactive arthritis.
C.Psoriatic arthritis (PsA).
D.Spondylitis associated with inflammatory bowel disease.
E.Rheumatoid arthritis (RA).
Plan
A.General interventions:
1.Treatment for AS includes nonpharmacological and pharmacological interventions.
2.Osteoporosis screening and treatment are recommended for these patients.
3.Systemic steroids are not routinely prescribed; however, for severe symptoms of pain and swelling, joint injection may be considered.
B.Patient teaching:
1.Encourage a healthy, active lifestyle. Activity improves symptoms. Regular exercises are recommended as tolerated. Physical therapy and/or structured exercises recommended most days of the week.
2.Medications prescribed should be used on a routine basis.
3.Fall prevention should be reviewed with the patient. The home should be modified to prevent falls. Suggestions include installing grab-bars in the bathroom tub/shower, removing loose rugs in the house, keeping walkways in the home clear and clutter free.
4.Seat belts should always be worn properly.
5.For persons with severe spinal involvement, contact sports and high-impact exercises/sports should be avoided.
C.Pharmaceutical therapy:
1.Nonsteroidal anti-inflammatory drugs (NSAIDs) are first-line therapy for pain/symptoms produced from AS. All medications should not be used longer than 4 weeks:
a.Ibuprofen 400 mg every 4 to 6 hours as tolerated.
b.Naproxen 500 mg twice a day (BID) as tolerated.
c.Celecoxib (Celebrex) 100 to 200 mg daily to BID as tolerated.
d.Indomethacin 75 mg one to two times per day.
e.Meloxicam 7.5 to 15 mg daily.
f.Diclofenac 50 mg every 8 hours
2.Nonopioid analgesic:
a.Acetaminophen 325 to 650 mg every 4 to 6 hours or 1,000 mg three times a day (TID).
3.Tumor necrosis factor alpha antagonists (anti-TNF) medications may be prescribed by a rheumatologist after failed NSAID use.
Follow-Up
A.Patients treated with NSAIDs should have routine follow-up at 2 weeks following initial diagnosis or sooner if not improving with treatment.
B.Patients treated with NSAIDs should be followed every 3 months with close monitoring of kidney and liver function.
Consultation/Referral
A.Patients diagnosed with AS should be referred to rheumatology for evaluation and treatment.
Individual Considerations
A.Adults:
1.Young adults, typically during the 20- to 30-year range, are diagnosed with AS. Patients commonly present to the office with complaints of low back pain and are treated for noninflammatory chronic back pain. These patients may go years without the proper diagnosis and treatment. Therefore, delayed diagnosis is not uncommon in these patients.
2.Standard precautions should be followed for NSAIDs for patients with renal insufficiency and patients taking anticoagulants, systemic glucocorticoids, and other interacting medications.
B.Geriatrics:
1.Not commonly diagnosed in this group of patients.