624 - Knee osteonecrosis in a patient receiving chronic trigger point injections containing Triamcinolone

Case Diagnosis: Bilateral knee osteonecrosis

Case Description: A 52-year-old male with a history of chronic low back pain (LBP) and lumbar radiculopathy status post epidural steroid injection (2016) started following with PM&R as an outpatient for post-concussive syndrome after a motor vehicle accident (MVA). Due to LBP, trigger point injections (TPIs) to the bilateral lumbar paraspinals using 1% Lidocaine and 40 mg Triamcinolone were started in September 2019 and repeated every three months. He began complaining of bilateral knee pain in November 2022. Radiographs showed infarcts within the distal femur and proximal tibia bilaterally. Notably, a left knee radiograph from June 2019 (obtained after MVA) showed sclerosis in the distal femur and proximal tibia concerning for bone infarcts. Following his new radiograph results, TPIs were changed to Lidocaine only. Per Orthopedics, no surgical intervention was recommended. Bilateral knee magnetic resonance imaging has been ordered, and further work-up for osteonecrosis is pending per his PCP.

Discussions: Osteonecrosis is a known side effect of long-term, high dose systemic glucocorticoids. While uncommon, a few case reports have documented the development of osteonecrosis following a single intramuscular or intra-articular steroid injection. Additional case reports document osteonecrosis after multiple intramuscular injections, ranging from a duration of three months to 10+ years. While the timeline for the development of osteonecrosis in this patient is unknown, there were signs of it predating the initiation of TPIs. However, given the aforementioned case reports, it is imperative to avoid glucocorticoids in this patient unless absolutely necessary to prevent further bone destruction.


Conclusions: This is a case where pathologic imaging findings led to a change in medication choice for the treatment of an unrelated condition. This highlights the importance of careful chart/imaging review and tailoring treatment to each individual patient as standard practice may worsen a pre-existing problem.