Bone involvement is a common cause of morbidity and disability in systemic lupus erythematosus (SLE).¹ This is both a consequence of the disease itself and treatments, including steroids.² As survival has improved, this has also led to long-term conditions being more prevalent, including osteoporosis and the risk of fractures.

Prevalence of osteoporosis is increased in SLE patients. In cohort studies the incidence of osteopenia is reported as being up to 74% and osteoporosis up to 68.7%.³ Disease-specific risk factors as well as traditional risk factors increase the risk of osteoporosis. These include systemic inflammation, hormonal abnormalities, autoantibodies and medications.⁴ Fracture risk is also increased in lupus by 1.2–4.7x.⁵ Steroids are frequently used in the management of lupus and are a common cause of bone loss.⁶ Treatment choices include lifestyle modification, anabolic and antiresorptives.²

Avascular necrosis (AVN) is a well described complication of lupus.⁴ Avascular necrosis can affect any bone, but is most commonly seen in the femoral head and knee.⁴ Cause of AVN is multifactorial and rates are increased in lupus patients with reports of up to 33% of symptomatic AVN and up to 45% of asymptomatic AVN.⁴ Use of steroids is reported as one of the key risk factors for AVN in lupus, although there are other disease-specific risk factors including vasculopathy and antiphospholipid syndrome.⁴ Treatment can include bisphosphonates and surgery.⁴

Rates of infection are higher in lupus patients than the general population and this includes increased rates of osteomyelitis.^{4 7} Clinical features of osteomyelitis may mimic lupus flares and therefore diagnosis may be delayed.⁴ An index of suspicion is required along with laboratory testing and imaging to distinguish infection from flare.

Early detection of bone involvement and distinguishing this from flares in lupus is important for appropriate management.

References

1. Garelick D, Pinto SM, Farinha F, et al. Fracture risk in systemic lupus erythematosus patients over 28 years. Rheumatology (Oxford). 2021;60(6):2765–72. doi: 10.1093/rheumatology/keaa705.

2. Humphrey MB, Russell L, Danila MI, et al. 2022 American college of rheumatology guideline for the prevention and treatment of glucocorticoid-induced osteoporosis. Arthritis Rheumatol. 2023;75(12):2088–102. doi: 10.1002/art.42646.

3. Xia J, Luo R, Guo S, et al. Prevalence and risk factors of reduced bone mineral density in systemic lupus erythematosus patients: A meta-analysis. Biomed Res Int. 2019;2019:3731648. doi: 10.1155/2019/3731648.

4. Rella V, Rotondo C, Altomare A, et al. Bone involvement in systemic lupus erythematosus. Int J Mol Sci. 2022;23(10) doi: 10.3390/ijms23105804.

5. Bultink IE, Lems WF. Systemic lupus erythematosus and fractures. RMD Open. 2015;1(Suppl 1):e000069. doi: 10.1136/rmdopen-2015-000069.

6. Kaneko K, Chen H, Kaufman M, et al. Glucocorticoid-induced osteonecrosis in systemic lupus erythematosus patients. Clin Transl Med. 2021;11(10):e526. doi: 10.1002/ctm2.526.

7. Huang YF, Chang YS, Chen WS, et al. Incidence and risk factors of osteomyelitis in adult and pediatric systemic lupus erythematosus: A nationwide, population-based cohort study. Lupus. 2019;28(1):19–26. doi: 10.1177/0961203318811601.

Learning Objectives At the end of this presentation participants will be able to:

• Discuss the incidence and risk factors for osteoporosis and fractures in lupus

• Describe how to assess fracture risk in lupus patients and consider whether osteoporosis treatment is required

• Explain when and how to investigate for AVN and the potential treatment options

• Explain when and how to investigate for osteomyelitis in lupus