Back Pain OSCE - Ankylosing Spondylitis

Case Overview

• Age/Sex: 19-year-old male
• Occupation: College student, varsity rower / athletic
• Setting: Primary care / student health clinic
• Chief complaint: "My lower back has been stiff and sore for months, especially in the morning."

Patient Script

Who I Am

I'm a 19-year-old college student who rows on the varsity crew team and works out most days.

What Brings Me In

My lower back has been getting stiffer and more painful for months, and it's starting to mess with training and sleep.

My Story

It started about 8 months ago as a dull ache around my lower back and buttocks. At first I thought it was from a new weight-training routine and rowing harder than usual, but it didn't go away with rest. I have stiffness in the morning for about an hour, and it feels better after I get moving. I often wake in the second half of the night with back pain that sometimes wakes me up. Over the last 3 months it has been more constant and sometimes I get a deep ache in the buttock that switches sides. I had a minor twist playing soccer last week which made it worse for a few days, but that settled. I also had a red, sore eye for a few days about 4 months ago that my eye doctor said was probable conjunctivitis and gave drops for. I haven't had any fever, weight loss, or recent infections that I remember.

My Medical Background

• Past medical history: none of significance
• Medications: occasional ibuprofen (over-the-counter) when it flares; protein shakes after workouts (no steroids)
• Allergies: none known
• Social: non-smoker, drinks alcohol rarely, lives in shared house with teammates
• Family: dad has "bad back" in his 40s; maternal aunt has ulcerative colitis (not sure how serious)

What I Think & Worry About

• I think it might be something I did lifting or rowing that I need to rest for.
• I'm worried this could stop me from competing this season or be something long-term.
• I expect you might tell me to rest, give me stronger painkillers, or refer me to a specialist.

If You Ask Me About Other Symptoms...

• Neck pain: I sometimes get a bit of tightness after long training sessions, but nothing like my lower back.
• Leg symptoms: I get occasional twinges down the back of my thigh but no obvious numbness or weakness.
• Bowel/bladder: no problems, no blood in stool
• Eye: the red eye episode was painful and light-sensitive for a couple of days, then improved with drops
• Skin/rashes: none
• Recent infections: I had a cold this past winter but nothing else
• Recent travel: none
• Medication use: I haven't taken any prescription meds; I take ibuprofen intermittently and a lot of protein powder

---

Clinical Summary

Examination

• General: alert, well-looking, afebrile, BMI 23
• Vitals: HR 64 bpm, BP 118/72 mmHg, Temp 36.8°C
• Spine: reduced lumbar flexion — modified Schober test shows increase of 2 cm on forward flexion (normal >5 cm)
• Chest expansion: 2 cm at 4th intercostal space (reduced; normal >5 cm)
• Sacroiliac provocation (FABER/Patrick test): reproduces deep gluteal pain, more on the left
• Palpation: tenderness over sacroiliac joint region bilaterally
• Neurological: normal lower limb power, sensation and reflexes; straight leg raise negative
• Peripheral joints: no synovitis or significant swelling
• Enthesitis: mild tenderness at insertion of Achilles bilaterally

Investigations

• CBC: WBC 6.8 x10^9/L (normal) (no leukocytosis)
• ESR: 28 mm/hr (mildly elevated)
• CRP: 16 mg/L (elevated; normal <5)
• HLA-B27: positive
• Pelvic X-ray (AP): bilateral sacroiliac joint sclerosis and blurring of joint margins, consistent with sacroiliitis (radiographic grade 2 bilaterally)
• MRI sacroiliac joints: bone marrow edema at both SI joints consistent with active sacroiliitis
• Urinalysis: normal (no infection)
• Liver and renal function: within normal limits (baseline for NSAID use)

Diagnosis

• Primary: Ankylosing spondylitis (probable early disease) — supported by: age <40 with insidious onset of inflammatory back pain (morning stiffness >30 minutes, improvement with exercise, nocturnal pain), reduced spinal mobility (Schober 2 cm), reduced chest expansion (2 cm), objective sacroiliitis on imaging (MRI and pelvic X-ray), raised inflammatory markers, and positive HLA-B27.

• Differentials:

  • Mechanical low back pain from rowing/weightlifting — considered because of athletic activity and recent minor twisting injury, but persistent morning stiffness and improvement with exercise favor inflammatory cause.
  • Lumbar disc herniation/sciatica — would expect focal radicular signs, reproducible neural tension, or paresthesia; exam and MRI do not support this.
  • Infective spondylodiscitis — unlikely given lack of fever, normal WBC, and MRI pattern consistent with sacroiliitis rather than disc infection.
  • Reactive arthritis or other seronegative spondyloarthropathy — possible; history lacks recent significant GI/urogenital infection, but family history of IBD increases consideration of spondyloarthritis spectrum.

Management

• Acute symptom control:
  • Start an NSAID (e.g., naproxen 500 mg twice daily) unless contraindicated; check renal function and counsel on GI risk.
  • Offer a trial of physiotherapy focused on spinal mobility and posture-preserving exercises; recommend regular daily exercise rather than prolonged rest.
• Further workup and referrals:
  • Refer to rheumatology for confirmation and ongoing management (disease-modifying therapy assessment).
  • Baseline bloods for rheumatology: LFTs, creatinine, hepatitis B/C, and TB screening prior to any biologic therapy.
  • Consider ophthalmology review if eye pain/redness recurs (suspect uveitis history).
• Patient advice:
  • Continue gentle exercise and stretching; avoid prolonged inactivity.
  • Discuss impact on sports and training plan with physiotherapist and rheumatologist.
  • Smoking cessation advice if applicable; review vaccinations before immunosuppression.
• If inadequate response or progressive disease on follow-up: initiation of biologic therapy (TNF inhibitor or IL-17 inhibitor) after specialist assessment and appropriate screening.

Key Learning Points

• Inflammatory back pain often presents in young adults (<40) with insidious onset, morning stiffness >30 minutes, improvement with exercise, and nocturnal pain — ask about these features to distinguish from mechanical pain.
• Examination clues for ankylosing spondylitis include reduced lumbar flexion (Schober test), decreased chest expansion, and sacroiliac joint tenderness; MRI can detect early active sacroiliitis even when X-ray changes are subtle.
• First-line management combines NSAIDs and regular exercise/physiotherapy; refer to rheumatology for consideration of biologic therapy and for appropriate screening before immunosuppression.