Laboratory-specific reference values for cerebrospinal fluid (CSF) Alzheimer disease (AD) biomarkers are necessary. Our objective was to apply well-known CSF biomarkers and redetermine their diagnostic cutoff values for AD in South Korea. CSF samples from matched control subjects (n=71), patients with AD dementia (ADD, n=76), and other neurological disorders with cognitive decline (OND, n=47) were obtained from 6 Korean dementia clinics according to a standardized protocol. CSF biomarker concentrations were measured using enzyme-linked immunosorbent assay. CSF biomarkers differed significantly between the ADD and control groups (P<0.001 for all), and between the ADD and OND groups (P<0.001 for all). The areas under the curve in differentiation of ADD from control subjects were 0.97 for Aβ42, 0.93 for total tau (tTau), 0.86 for pTau, and 0.99 for both tTau/Aβ42 and pTau/Aβ42 ratios. Our revised cutoff value for Aβ42 was higher than our previous one, whereas the values for the Tau proteins were similar. The tTau/Aβ42 ratio had the highest accuracy, 97%. Our findings highlight the usefulness of CSF AD biomarkers in South Korea, and the necessity of continually testing the reliability of cutoff values.

The authors present a case of extension loss of great toe caused by entrapment neuropathy of a peroneal nerve due to an osteochondroma of the proximal fibula. Plain radiographs revealed no bony abnormality around the foot or ankle, but a sessile exophytic bony growth at the proximal fibula. A positive Tinel sign in this area led us to a suspicion of compressive neuropathy of the peroneal nerve, and a subsequent electrophysiologic study confirmed the entrapment neuropathy. The peroneal nerve was decompressed by excisional biopsy. At 3 months postoperatively, normal full extension of the great toe was completely restored. The current case deserves attention in that the only clinical manifestation of peroneal nerve entrapment neuropathy by the osteochondroma at the fibular neck was extension loss of great toe.

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Intra-articular synovial lipoma is rare and clinically manifested mostly by mass effect and occasionally by torsion of the stalk. Patellar dislocation rarely occurs owing to a mass effect of intra-articular tumor of the knee joint. The authors present a case of large intra-articular synovial lipoma at the lateral gutter of the knee joint, which presents as patellar dislocation. A 19-year-old man visited our clinic due to pain and limitation of motion owing to mass at his left knee. MRI revealed an intra-articular soft tissue mass at the lateral gutter of the knee joint with considerable mass effect displacing patella from the trochlear groove. Excisional biopsy confirmed the diagnosis of lipoma, and the final diagnosis was intra-articular synovial lipoma with clinical information. The final radiograph showed well-aligned patella on the trochlear groove. After marginal excision, there was no recurrence or tumor-related morbidity.

We report two cases of ganglion cysts in the posterior septum of the knee joint, one as parameniscal cyst from the posterior horn of the lateral meniscus extending to posterior septum, and the other as a cyst located in the posterior septum adjacent to the posterior cruciate ligament, which were both arthroscopically excised expediently by posterior trans-septal portal. The posterior compartment of the knee is not readily accessible by ordinary arthroscopic portals, and therefore has been considered as 'blind spot' conventionally. The posterior trans-septal portal is useful for assorted diagnostic or manipulative procedures in the posterior compartment of the knee.