Aims

Present the outcomes of those patients diagnosed with Ewing's Sarcoma of the foot within the past 10 years and treated at the Royal National Orthopaedic Hospital's Bone Tumour Unit, Stanmore.

Infection after knee arthroplasty is a devastating complication. Our aim is to present our outcomes of treating infected knee replacements at a tertiary referral centre.

We performed a consecutive, retrospective case series of all revision knee arthroplasty for infection between January 2006 and December 2008. Case notes were reviewed and data collated on the date and institution of primary arthroplasty, procedures undertaken at our institution, microbiology and bone loss post first stage, serological markers (C-reactive protein, ESR) prior to second stage and outcome.

During this three year period we performed 430 knee revision operations. 51 were in the presence of deep chronic infection. 90% were referred from other hospitals. Overall infection was successfully eradicated in 69%.

Nineteen patients underwent repeat two-stage and overall eleven (58%) patients had successful eradication of infection with multiple two-stages. Of these 47% had F3/T3, the highest grading of Anderson Orthopaedic Research Institute bone loss indicating no metaphyseal bone. A further 12% had bicondylar deficiency on the tibia and no femoral metaphyseal bone (F3/T2b).

Multidrug resistance present in 69% and 47% were infected with multiple organisms. All members of the unsuccessful outcome group had at least one multidrug resistant organism compared to 43% in the successful cohort (P=0.0002). Multiple organisms are associated with an unsuccessful outcome (P=0.056).

Serological markers were not significantly different between the successful and unsuccessful outcome groups.

Where the referring hospital had attempted revision and failed, the chance of eradicating infection dropped from 75% to 58% and the rate of above knee amputation was twelve times higher (3% vs. 36%).

Custom constrained, rotating hinge prostheses enable aggressive soft tissue debridement including ligaments. Successful two-stage requires a multidisciplinary approach including tissue viability nurses, microbiologists and plastic surgeons. Where units lack revision expertise this series suggests early referral increases the chance of limb salvage.

Orthopaedic problems are common in patients with Ehlers-Danlos Syndrome (EDS). Articular hypermobility can be particularly disabling leading to instability in the appendicular skeleton. We present a case of an EDS patient presenting with knee pain and instability. It highlights important lessons to be learned when considering joint replacement in this patient group.

A 51 year old lady with EDS underwent a posterior cruciate retaining total knee replacement for pain and instability. She dislocated her knee replacement three months post-operatively after a fall. Her knee was reduced at her local emergency department causing injury to the popliteal artery. She required urgent popliteal artery repair and fasciotomies. The common peroneal nerve was also irreversibly damaged by the dislocation. She has since had one further dislocation and is now awaiting revision surgery. When considering total knee replacement (TKR) in EDS, the patient must be warned of the inferior results compared to TKR for other causes. The increased risk of complications must be explained and a more constrained TKR design considered to address the inherent joint laxity. The potential consequences of a dislocated TKR can be disastrous and therefore relocation must be performed in a controlled environment in the operating theatre.

Skeletal Cryptococcosis although rare has been reported in immunodeficient individuals and in particular those with HIV. We present a case in a HIV- negative patient who presented to the London Sarcoma service masquerading as a primary bone tumour and review the relevant literature.

A 71 year old lady presented with a three month history of right submammary pain associated with a new lump. Chest radiographs showed an osteolytic lesion in the right 6^th rib. CT scans demonstrated mediastinal lymphadenopathy and numerous lung nodules. Differential diagnosis of the lesion included TB abscess, myeloma, lymphoma or as a primary lung tumour presenting with hilar lymphadenopathy and necrotic skeletal metastasis. CT guided biopsy was performed with histology showing necrotising granulomatous inflammation with numerous yeast like organisms in keeping with Cryptococcus fungal infection. She was treated successfully with a six week course of voriconazole.

Cryptococcal skeletal infections can cause significant morbidity and mortality and should be considered as a rare cause of lytic osseous lesions.