Hip septic arthritis diagnosed during rehabilitation of a trans-tibial amputation due to a diabetic foot ulcer : a case report

Mr Alexis HOMSa, Prof Arnaud DUPEYRONa

a CHU Nimes Carémeau

Introduction :
A major part of lower limb amputations concerns patients with diabetes, and is related to the appearance of a diabetic foot ulcer, that can cause serious complications if it becomes septic.

Observations :
A 64 years-old woman with diabetes mellitus, socially isolated, is hospitalized, being in a hyperosmolar coma ; her diabetes was decompensated by a toxic shock due to a necrotic diabetic foot ulcer, requiring right trans-tibial amputation.
Then she was admitted to a rehabilitation unit, where she was suffering from increasing left hip pains (strongly limiting her capacity to walk), in a clinical and biological inflammatory context, that led us to make a MRI.
A liquid collection into left ilio-psoas muscle associated to a rapidly destructive left hip arthritis were diagnosed. PET-scan was in favour of a septic arthritis.
Surgery enabled to make biological samples (finding a Bacteroides fragilis and meticillin-resistant Staphylococcus aureus infection), and a to implant a hip spacer, pending a hip prosthetic replacement.

Discussion :
The most likely etiologic diagnosis - although not certain - seems to be an infected psoas hematoma (the first hip pains she notified were accompanied by a slight hemolysis), that caused septic hip arthritis by spreading by contiguity.
Among anaerobic hip infections, Gram-positive cocci are most frequently found in patients having been treated by surgery (such as arthroplasties), whereas Gram-negative bacterias are more related to debilitated patients who had not had any hip surgical treatment1.

Conclusion :
In case of diabetic foot ulcer infection, we should always think about the risk of a systemic infectious complications. Atypical left hip pains can be the only symptom of an infected psoas hematoma in debilitated patients as described in this observation.

1 Fitzgerald RH Jr, Rosenblatt JE, Tenney JH, Bourgault AM. Anaerobic septic arthritis. Clin Orthop Relat Res. 1982 Apr;(164):141-8.

Keywords : infection ; hip ; diabetes ; trans-tibial ; amputation ; psoas hematoma ; hip spacer ; Bacteroides fragilis