A 64-year male presents to the Emergency department on a Sunday morning. He is an obese diabetic who describes himself as an occasional smoker. In his 20’s he underwent an open Lateral Meniscectomy and now has severe lateral compartment osteoarthritis. His BMI is 38. Two years prior he was seen by an orthopaedic surgeon and was recommended to lose weight , take improved analgesia and exercise. He was advised the knee replacement was likely but was told that he really should maximise his non-operative options.
Earlier this year he attended a stem cell clinic in Melbourne, had liposuction, and the fractionated adipose Pericytes were then injected into both of knees as “stem cell” therapy. Some of the Pericytes were then frozen. Due to ongoing pain he went back 5 days ago and had more of the now defrosted Pericytes injected into both of his knees. On Friday he noted increasing pain and swelling in the right knee. On Saturday he saw his GP who diagnosed a possible septic right knee and prescribed oral Cefuroxime. His GP suggested if he didn’t settle, then to attend the EmergencyDepartment. Over the next 24 hours, his knee pain worsened, he developed low-grade fevers and an increasing effusion.
On examination in the Emergency Department, he had a low-grade temperature of 38.4 degrees Celsius and a moderate effusion. His CRP was 87, knee synovial fluid white cell count was 13,600 and he had a mild neutrophilia. He denied a history of gout, but gout crystals were visible on microscopy. No bacteria were visible and the fluid was cultured, but culture results will take 2- 7 days.
What is the diagnosis ?
It could be either an acute attack of gout on a background of chronic gout, or a septic knee. Both could have occurred from the injection. The rate of infection is quite low after knee injection, but it remains the most common cause of a septic native knee joint. Because he was started on antibiotics prior to a synovial specimen being taken, he could have a culture negative infection. Bacteria are rarely visible in septic synovial fluid.
What is the management ?
Because of the high CRP and synovial cell count, a presumptive diagnosis of sepsis was made. The patient was taken to the Operating Theatre and an arthroscopic lavage and synovectomy was performed. Severe synovitis was noted and severe osteoarthritis in the lateral compartment. The synovial fluid was very turbid with gout crystals visible throughout the knee. Intravenous broad-spectrum antibiotics were commenced and the patient was kept in hospital for 1 week. No culture had occurred by day 7. RNA testing of the tissue biopsy was undertaken, but this was equivocal. The patient made a slow recovery over the next weeks, with resolution of the pain and swelling. Oral broad spectrum antibiotics were continued for 4 weeks,
Total knee replacement was delayed for at least 6 months due to the possible infection in the the joint being a contra-indication.
What is the take-home message ?
1 Adipose-derived stem cells have no current role in the management of Osteoarthritis. No controlled study has shown improved symptoms over placebo.
2 If a possible diagnosis of a septic joint is made, antibiotics must not be commenced until a tissue sample is obtained.
3 Weight loss, exercise and appropriate analgesia remain the primarymanagement of uncomplicated Osteoarthritis