What is the management for a patient with Systemic Lupus Erythematosus (SLE) on Mycophenolate Mofetil (MMF), Hydroxychloroquine (HCQ), and Prednisolone (Wysolone) at 5mg alternate day who has developed Avascular Necrosis (AVN) of the femur?

Management of AVN of the Femur in SLE Patient on MMF, HCQ, and Low-Dose Prednisolone

Your SLE patient with AVN of the femur requires immediate orthopedic consultation for surgical evaluation while continuing hydroxychloroquine and mycophenolate mofetil through any planned surgery, with prednisolone maintained at the current low dose to prevent disease flare while minimizing further bone damage.

Immediate Orthopedic Referral and Surgical Planning

• Urgent orthopedic consultation is essential as AVN management is primarily surgical, with treatment options ranging from core decompression in early stages to total hip arthroplasty in advanced disease 1
• MRI is the most sensitive imaging modality for staging AVN and should be obtained if not already done to guide surgical decision-making 1
• The bilateral femoral heads are the most common site of AVN involvement in SLE patients, so screening the contralateral hip with MRI is warranted even if asymptomatic 2

Perioperative Medication Management

Continue Through Surgery

• Hydroxychloroquine should be continued without interruption as it is recommended to continue through surgery for all SLE patients undergoing total hip arthroplasty 3, 4
• Mycophenolate mofetil should be continued through surgery given that this patient does not have severe SLE (on only 5mg prednisolone alternate day suggests well-controlled disease), and the ACR recommends continuing MMF for severe SLE patients 3
• Prednisolone at 5mg alternate day should be continued at the current dose rather than administering supraphysiologic stress doses, as the ACR conditionally recommends continuing current glucocorticoid doses through surgery 3

Critical Caveat for Non-Severe SLE

• If your patient's SLE is classified as "not severe" (no major organ involvement, stable disease), the ACR recommends withholding MMF 1 week prior to surgery 3
• However, given the patient is on very low-dose alternate-day steroids suggesting excellent disease control, and the risk of flare must be weighed against infection risk, this decision requires careful assessment of disease activity and flare history 3

Corticosteroid Management Strategy

Minimize Further Steroid Exposure

• Do not increase prednisolone dose as corticosteroids are the major predisposing factor for AVN in SLE, with higher cumulative doses and peak doses strongly associated with AVN development 2, 5, 6
• The highest cumulative prednisolone dose in 4 months and maximum daily dosage are independent risk factors for AVN 5
• Your patient's current regimen of 5mg alternate day (approximately 2.5mg daily equivalent) is already minimal and should not be increased unless absolutely necessary for SLE disease control 6

Long-Term Steroid-Sparing Strategy

• Maintain MMF and HCQ as steroid-sparing agents to keep prednisolone at the lowest possible dose and prevent the need for dose escalation 4, 7, 8
• Hydroxychloroquine monotherapy or immunosuppressant monotherapy (like MMF) are reasonable maintenance strategies that reduce flare rates compared to no therapy 8

Risk Factor Assessment and Monitoring

Identify Additional AVN Risk Factors

• Check for lupus anticoagulant and antiphospholipid antibodies as these are independent risk factors for AVN (odds ratio 2.88) 5
• Assess for Cushingoid body habitus, which is associated with higher AVN incidence (79% vs 53% in controls) 5
• Male gender and younger age are associated with higher AVN risk in SLE 2

Screen for Bilateral Disease

• Obtain MRI of the contralateral hip even if asymptomatic, as bilateral femoral head involvement is most common in SLE-associated AVN 2
• Early detection allows for earlier intervention and potentially better outcomes 1

Postoperative Medication Resumption

• Resume all antirheumatic medications approximately 14 days after surgery once the wound shows evidence of healing, sutures/staples are removed, there is no significant swelling, erythema, or drainage, and no ongoing infection 3
• This timing applies to any medications that were withheld perioperatively 3

Disease Activity Monitoring

• Maintain close surveillance for SLE flares during the perioperative period, as medication adjustments and surgical stress may trigger disease activity 4, 7
• Monitor complement levels, anti-dsDNA antibodies, CBC, renal function, and urinalysis every 3-6 months 4
• Use validated disease activity indices at each visit to detect early flares 4, 7

Common Pitfalls to Avoid

• Do not administer high-dose "stress steroids" for surgery, as this increases AVN risk and the ACR specifically recommends against supraphysiologic dosing 3, 6
• Do not discontinue hydroxychloroquine, as it is the backbone of SLE therapy and reduces long-term flare risk without increasing surgical complications 3, 4
• Do not delay orthopedic referral thinking medical management alone will suffice—AVN is primarily a surgical condition and early intervention improves outcomes 1