Eyþór Örn Jónsson¹, Hera Jóhannesdóttir², Anna Stefánsdóttir³

¹Department of Orthopedics, Sahlgrenska University Hospital, Gothenburg, Sweden ²Department of Orthopedics, Landspitali University Hospital, Reykjavik, Iceland, ³Lund University, Skane University Hospital, Department of Clinical Sciences Lund, Orthopaedics, Lund, Sweden

An 80-year old male presented with an infected knee replacement following repeated joint aspirations. They were carried out due to recurrent hemarthrosis resulting from an initially missed quadriceps tendon injury. The infection was eradicated first after arthrodesis. This case highlights that prosthetic joints are sensitive to infection, which once established can be difficult to eradicate. Careful consideration is necessary before aspirating prosthetic joints. Diagnosing quadriceps tendon injuries can be difficult and they must be included in the differential diagnosis of traumatic hemarthrosis. We review the initials steps in the diagnosis and management of periprosthetic joint infections.

Table I. The MSIS (Muskuloskeletal Infection Society) definition for periprosthetic joint infection. Infection is present if one of two major criteria or four of six minor criteria are met.14

Major criteria

There is a sinus tract communicating with the prosthesis

A pathogen is isolated by culture from at least two separate periprosthetic tissue or fluid samples

Minor criteria

Elevated serum erythrocyte sedimentation rate and serum C-reactive protein

Elevated synovial leukocyte count

Elevated synovial neutrophil percentage

Presence of purulence in the affected joint

Isolation of a microorganism in one culture of periprosthetic tissue or fluid

Elevated neutrophil count observed from histologic analysis of periprosthetic tissue*

* Greater than five neutrophils per high-power field in five high-power fields at x400 magnification

Figure 1. A radiograph of the patients left knee. The prosthesis has been replaced with a spacer made of bone cement.

Figure 2. A radiograph of the patients left knee after arthrodesis has been performed with an intramedullary nail.