Aims

Osteonecrosis (ON) can cause considerable morbidity in young people who undergo treatment for acute lymphoblastic leukaemia (ALL). The aims of this study were to determine the operations undertaken for ON in this population in the UK, along with the timing of these operations and any sequential procedures that are used in different joints. We also explored the outcomes of those patients treated by core decompression (CD), and compared this with conservative management, in both the pre- or post-collapse stages of ON.

Background. Unicameral bone cysts (UBCs) are difficult to treat and have a high recurrence rate. Their pathogenesis is unknown making targeted therapies difficult. Attributed causes include venous and interstitial fluid obstruction, oxygen free radicals, lysosomal enzymes, prostaglandins and genetic factors. Skeletal stem cells (SSCs) are osteoblast precursors critical to bone formation and cyst fluid may influence their growth, however the association between SSCs and cyst fluid has never been investigated. Aim. To investigate the effect of UBC fluid on SSC growth. Methods. Fluid was aspirated from a UBC in the proximal femur of a nine year old boy and centrifuged to isolate the acellular supernatant. SSCs were harvested from bone marrow of a haematologically normal adult and cultured with graded concentrations of cyst fluid in culture media (0,10,25,50%). Cell growth was assessed by alkaline phosphatase staining, and cytokine levels in the fluid were measured. Results. High levels of cytokines known to be chemo-attractive for cells of the of macrophage-monocyte lineage were found, including Macrophage Chemotactic Protein-1 (1853pg/ml), Monokine Induced by γ-interferon (656pg/ml), Macrophage Inflammatory Protein (MIP)-1α (401pg/ml) and MIP-1β (34pg/ml) suggesting a role of osteoclasts in UBC pathogenesis. Furthermore, SSC growth in vitro was reduced in cyst fluid in a concentration dependent manner. Conclusion. This is the first time altered SSC and osteoprogenitor function has been associated with the fluid of a UBC. A negative effect on osteogenesis was demonstrated, the precise mechanisms of which are under investigation, and macrophage-monocyte chemokines suggest high osteoclast activity. This study has indicated a role of the cyst fluid in limiting osteogenesis and bone turnover, which may explain the high failure rate for current interventions. More patients are needed to validate these findings

We reviewed three infants with destructive osteomyelitis involving the proximal tibial epiphysis at a follow-up of eight to 22 years. All cases showed early radiographic destructive changes in the medial or lateral aspects of the epiphysis and metaphysis. Despite the ominous early appearance of the epiphysis, all cases showed spontaneous re-ossification of the epiphysis with restoration of the tibial condyle and preservation of joint congruity. The patients, however, developed a valgus or varus deformity which was treated satisfactorily with one to three proximal tibial osteotomies. The potential for regeneration of the epiphysis following infantile osteomyelitis of the proximal tibia suggests these cases should be treated expectantly with regard to joint congruity.