ABSTRACT
A 59-year-old woman was seen at the ER with a painful right knee locked in extension. This was caused by unloaded hyperextension in bed. Interlocking patellofemoral osteophytes and a superior patella dislocation tilted away from the femur were seen on the X-ray, which are both pathognomonic signs of a superior dislocation of the patella.
Subject(s)
Patellar Dislocation/diagnosis , Female , Humans , Knee , Knee Joint/pathology , Middle Aged , RadiographyABSTRACT
A 59-year-old woman with a painful right knee that became locked in extension after a trivial trauma was seen at the emergency room. This was caused by unloaded hyperextension in bed. She was diagnosed with a superior dislocation of the patella. A closed reduction was performed, but a recurrent episode was seen within a week. An arthroscopy was performed, in which the causative osteophytes were removed. In the 12-month follow-up after treatment, no recurrence was seen. A superior dislocation of the patella is caused by patellofemoral osteophytes that interlock. This can cause a degenerative knee to become locked in extension. Beside interlocking osteophytes of the patella and the distal femur, the superior part of the patella is tilted away from the femur. This is caused by the pull of the patella tendon and the simultaneous relaxation of the quadriceps tendon. This is a pathognomonic finding on radiographs that, to the best of our knowledge, has been identified but not been appreciated as such in previous reports. As illustrated in this report, a superior dislocation of the patella can easily be recognized on physical examination and radiographic imaging alone when familiar with the specific abnormalities. This will reduce unnecessary diagnostic imaging studies and delay in treatment. This case report illustrates a recurrent case of superior dislocation of the patella. We summarize and evaluate previous reports, discuss trauma mechanisms, physical examination, classification, and treatment including recurrent cases. After reading this case report the reader will be able to diagnose a superior dislocation of the patella with near certainty on physical examination and radiographic imaging of the knee alone.
Subject(s)
Osteophyte/complications , Patellar Dislocation/diagnostic imaging , Patellar Dislocation/etiology , Arthroscopy , Female , Humans , Middle Aged , Patellar Dislocation/surgeryABSTRACT
BACKGROUND: Osteosarcoma (OS) is the most common bone tumour in children and adolescents. Despite aggressive therapy regimens, treatment outcomes are unsatisfactory. Targeted delivery of drugs can provide higher effective doses at the site of the tumour, ultimately improving the efficacy of existing therapy. Identification of suitable receptors for drug targeting is an essential step in the design of targeted therapy for OS. METHODS: We conducted a comparative analysis of the surface proteome of human OS cells and osteoblasts using cell surface biotinylation combined with nano-liquid chromatography - tandem mass spectrometry-based proteomics to identify surface proteins specifically upregulated on OS cells. This approach generated an extensive data set from which we selected a candidate to study for its suitability as receptor for targeted treatment delivery to OS. First, surface expression of the ephrin type-A receptor 2 (EPHA2) receptor was confirmed using FACS analysis. Ephrin type-A receptor 2 expression in human tumour tissue was tested using immunohistochemistry. Receptor targeting and internalisation studies were conducted to assess intracellular uptake of targeted modalities via EPHA2. Finally, tissue micro arrays containing cores of human OS tissue were stained using immunohistochemistry and EPHA2 staining was correlated to clinical outcome measures. RESULTS: Using mass spectrometry, a total of 2841 proteins were identified of which 156 were surface proteins significantly upregulated on OS cells compared with human primary osteoblasts. Ephrin type-A receptor 2 was highly upregulated and the most abundant surface protein on OS cells. In addition, EPHA2 was expressed in a vast majority of human OS samples. Ephrin type-A receptor 2 effectively mediates internalisation of targeted adenoviral vectors into OS cells. Patients with EPHA2-positive tumours showed a trend toward inferior overall survival. CONCLUSION: The results presented here suggest that the EPHA2 receptor can be considered an attractive candidate receptor for targeted delivery of therapeutics to OS.
