Abstract
Case report - Introduction
Rheumatoid arthritis (RA) is an autoimmune inflammatory arthropathy with systemic manifestations. It is 4-times more common in females. RA is recognised to induce bone loss and decrease in bone mineral density (BMD). Management may include corticosteroids (CS) for new presentations, acute flares, and more rarely longer-term management, which increases bone fragility. Patients are at 30—50% increased risk of developing osteoporosis with a 30% increase in fracture risk. This risk rises with the level of persistent disease inflammation.
We present a case of a lady with longstanding RA, who sustained multiple bone fractures without significant osteoporosis on bone density scanning.
Case report - Case description
Our patient is a 64-year-old headteacher who took early retirement due to reduced mobility after 20 years of seropositive RA. She had received multiple disease modifying drugs (DMARDs) and biologics therapies, requiring repeated alterations primarily due to treatment failure. She was commenced on alendronic acid due to osteopaenia of the hip but 2 years later sustained a fractured neck of femur and was switched to risedronate.
A year later she presented with acutely painful and swollen right foot and ankle without history of trauma. X-rays showed progressive degenerative change whilst inflammatory markers were normal. Ultrasound demonstrated sub-clinical synovitis. Her medication was optimised but the ankle swelling persisted, rendering her wheelchair-reliant. MRI revealed multiple stress fractures involving calcaneum, talus and 5th proximal phalanx. She was treated with 16 weeks of an Aircast boot. An old right upper medial tibial fracture was also identified.
Repeat dual energy X-ray absorptiometry (DEXA) scan showed osteopaenia but with improvement from the previous scan (T score of -2.1 total hip and -1.6 lumbar vertebra). She smoked 1 cigarette a day, did not drink alcohol and there was no parental history of fractures. No evidence of malabsorption or endocrine disorder was identified. Unusually, she had received tamoxifen in her late 20s for cancer prevention based on breast fibroadenosis and she experienced early menopause aged 36 years.
Inflammatory markers, calcium, parathyroid hormone, and immunoglobulins were normal. Vitamin D3 levels were insufficient at 40.3 nmol/l and replacement was initiated, following which she was switched to intravenous zoledronic acid.
After one infusion of zolendronate, she twisted her right ankle and sustained a new malleolar fracture. She was converted to 6-monthly denosumab injections along with calcium and vitamin D, which has been continued. Her RA remains active, and she has recently commenced JAK2 inhibitors.
Case report - Discussion
Inflammatory arthropathies such as RA predispose to significant morbidity and disability. An earlier age of diagnosis poses a longer inflammatory response in body, with a higher incidence of bone health complications. A treat-to-target strategy in RA aids optimal disease management and reduces fracture risk. Studies have shown the risk of osteoporosis in RA is not just disease dependent but also affected by certain medications.
Treatment challenges arise when a patient sustains fracture despite a BMD above osteoporosis risk criteria, leading us to consider other variables. She was further investigated for secondary causes of osteoporosis, including endocrine causes, and was found to be vitamin D insufficient, which was replaced prior to further antiresorptive treatment.
Our case also highlights a diagnostic dilemma given that our patient presented with a single swollen joint assumed to be due to active RA. Multiple insufficiency fractures were only identified after MRI was performed.
As per EULAR criteria, our patient had difficult to treat RA with a long disease duration. She showed intolerance to a several DMARDs and treatment failure with multiple biologic therapies. She had required local joint injections and repeated short courses of oral steroids. These factors are likely to have played a considerable role in her fracture development. RA is an independent risk factor for fracture in both men and women with disease duration and CS use being important clinical variables.
Bisphosphonates are considered vital in fracture risk reduction. The compliance is an important factor for both primary and secondary prevention of fracture. They are associated with decreased bone remodelling and have been well studied for atypical femoral fractures; however, whether there is any link with stress fractures in the feet requires further studies. Long-term use (>5years) hasn’t shown to be beneficial in preventing hip fractures.
Case report - Key learning points
Oncogenic Osteomalacia with Multiple Insufficiency Fractures: A Case Report