Knee Septic Arthritis after Palm Tree Thorn Injury
This work presents the case of a 68-year-old male with a palm tree thorn penetrating injury to the lateral supra-patellar side of his left knee while gardening and which was claimed to have been immediately removed. Only diabetes mellitus type 2 was found as relevant comorbidity. Two days later, he presented to the ER feeling feverish, with a swollen, painful left knee which exacerbated by articular movement despite being on rest, ice, and anti-inflammatory medication. No other articular involvement was found.

Physical examination demonstrated an auricular temperature of 37.3oC and a swollen, warm, and highly painful knee. There was a relevant intra-articular effusion with a range of movement restricted to 30o–90o. Skin inspection revealed a lateral millimetric entry wound. Blood tests disclosed a leukocytosis with neutrophilia (89.1%) and RCP of 4.44 mg/dL. Plain radiographs were unremarkable. Ultrasound excluded the presence of any foreign bodies near the entry wound or intra-articular.

As septic arthritis was suspected, urgent arthroscopy was performed. No tourniquet was used and 2g Cefazolin was administered after the synovial fluid was harvested to culture. Anterolateral and anteromedial portals were used, and generalized synovitis was found. Mild damage to the patellofemoral joint was found, presumed chronic. At the suprapatellar pouch, a foreign body was found that matched the distal end of the thorn. Lavage with 9L saline and arthrotomy was performed to exclude the thorn pathway. The knee was protected with Robert–Jones dressing (soft-padded bandages) for 5 days to allow careful mobilization and a faster functional recovery. Total weight-bearing was advised according to pain. Empiric antibiotic therapy was initiated with amoxicillin + clavulanic acid, 875 mg + 125 mg tid. On the 6th postoperative day, Pantoea agglomerans were identified in the synovial fluid susceptible to amoxicillin + clavulanic acid and resistant to ampicillin and amoxicillin. The patient was discharged on day 6 and kept antibiotic therapy for 6 weeks. At that time, physical examination, as well as the analytic control, were unremarkable (no inflammatory parameters were elevated, namely, RCP and leucocytes).