The effect of medial and lateral calcaneal osteotomies on the tarsal tunnel.

BACKGROUND: As an entrapment phenomenon, tarsal tunnel syndrome has been described after calcaneal osteotomy, and since the tibial nerve has also been shown to be very sensitive to ankle position, position of the calcaneus after osteotomy and displacement was thought to likely influence the environment of the tibial nerve within the tarsal canal. The respective volume of the tarsal canal was therefore hypothesized to decrease with medial or lateral displacement osteotomies of the calcaneus. METHODS: Anterior and posterior calcaneal osteotomies were made in cadaveric matched pairs and brought through sequential medial and lateral displacements. Magnetic resonance imaging was used to estimate the comparative resultant volume of the tarsal canal after each of these new positions were assumed, as compared with baseline. The proximity of the osteotomy cut to the nerve's location was also measured. RESULTS: The tarsal tunnel volume was calculated for all 5 displacement states and were as follows: far-lateral (9506 mm(3)), near-lateral (10 073 mm(3)), normal (11 839 mm(3)), near-medial (11 489 mm(3)), and far-medial (11 760 mm(3)). No significant difference in tarsal tunnel volume was identified between the normal, nondisplaced specimens in the anterior or posterior groups (11 954 mm(3) vs 11 809 mm(3)). No difference in tarsal tunnel volume was identified between the anterior and posterior osteotomies at any of the 4 displacements. The distance from tibial nerve to the medial exit site of the osteotomy was found to be significantly less in the anterior group compared to the posterior group (4 mm vs 14.2 mm, P < .0001). CONCLUSION: Lateral, but not medial, osteotomy fragment displacement results in significant reduction of tarsal tunnel volume. The location of the cut does not seem to affect any substantive change in volume. Anteriorly placed osteotomies appear to jeopardize the neurovascular structures more than posteriorly placed osteotomies. CLINICAL RELEVANCE: These findings provide surgeons with clinical evidence in support of performing a prophylactic tarsal tunnel release for patients undergoing lateralizing calcaneal osteotomies.

81 year-old male with confusion and weakness.

Glioblastoma, the most common primary brain tumor, is a highly infiltrative, malignant astrocytic neoplasm that demonstrates a wide spectrum of morphologic heterogeneity. Cases with a primitive neuroectodermal tumor (PNET)-like component are rare, but are being increasingly recognized and studied. The primitive component typically shows immunohistochemical features that are indicative of potential for divergent differentiation along glial and neuronal pathways; when present, the entire neuraxis may be at risk for involvement, portending a particularly poor prognosis. Recently, data from the largest case series studying malignant gliomas with a PNET-like component suggest that the primitive component likely arises from the malignant glial component. This report presents an example of glioblastoma with a prominent primitive neuroectodermal-like component in an 81 year-old male who, during the course of concurrent chemotherapy and radiation therapy, died five weeks following initial diagnosis.

Outcomes after heart transplantation in patients with and without pretransplant renal dysfunction.

OBJECTIVE: To compare long-term survival and incidence of ESRD between patients with and without preoperative renal dysfunction following heart transplantation. DESIGN: Fifty consecutive patients with preoperative estimated GFR < or = than 50 ml/min were compared with 50 age-matched patients with estimated GFR > or = than 80 ml/min who underwent heart transplantation between 1994 and 1998. We investigated two primary outcomes: death and development of ESRD. We also analyzed risk factors. RESULTS: Eight patients (16%) developed ESRD and 19 (38%) died in the control group whereas 10 patients (20%) developed ESRD and 26 (52%) died in the renal failure group during a mean follow-up period of 6.74 +/- 3.31 years. Survival and time to ESRD were not significantly different. In univariate and multivariate analysis, waiting time was the only risk factor found to predict mortality but not ESRD. High cyclosporine levels were only found to be associated with lower estimated GFR (p < 0.009). Among the control group, mortality was significantly higher in the subgroup of patients that developed > or = 50% reduction of estimated GFR at the end of the first post transplant year (p < 0.05). CONCLUSIONS: This study suggests that low pre-transplant estimated GFR may not accurately predict long-term development of ESRD.

Characterization of membrane rafts isolated from rat sertoli cell cultures: caveolin and flotillin-1 content.

Membrane rafts from Sertoli cell cultures were isolated as detergent-insoluble glycosphingolipid-enriched (DIG) fractions on the basis of their enriched content of glycosphingolipids and cholesterol and the resulting insolubility in 1% Triton X-100 and their low buoyant density. Because lipid rafts have been implicated in numerous cell functions, including cell signaling and sites for actin/membrane attachment, studies were initiated to characterize Sertoli cell rafts. This study reports the distribution of the raft structural proteins, caveolin and flotillin-1, implicated in raft microdomain organization. Methods employed included the immunoblotting of cell lysates and detergent-insoluble glycosphingolipid-enriched (DIG) fractions, the immunofluorescent microscopy of peritubular myoid cell (PMC) cultures and cryostat-sectioned testis, and the immunohistochemical staining of paraffin-embedded sections following microwave antigen retrieval techniques. Sertoli cells and Sertoli DIG fractions were found to lack the common raft-associated protein, caveolin, a marker protein for caveolae, but they are enriched in the 48-kd protein, flotillin-1, a protein also implicated in raft formation, cell signaling, and cell motility. Since the primary cell contaminant of Sertoli cell cultures is the PMC, these cells, along with spermatogenic cell fraction (SPGC), were also examined for caveolin and flotillin-1 content. The PMCs contained significant concentrations of both caveolin and flotillin-1. PMCs in culture exhibited a punctate caveolin staining pattern at the cell surface characteristic of a caveolar location. These data support the idea that the pinocytotic vesicles observed in PMCs are caveolae. PMCs also show a perinuclear location for caveolin characteristic of a Golgi location. Cryostat sections of rat testis showed a marked concentration of caveolin in the PMCs. The PMC location of caveolin was also confirmed by the immunohistochemical staining of sections from paraffin-embedded rat testis following microwave antigen retrieval techniques. Similar experiments showed a more ubiquitous, stage-specific distribution of flotillin-1 among testicular cell types.

Effects of simulated vastus medialis strength variation on patellofemoral joint biomechanics in human cadaver knees.

Selective strengthening of the vastus medialis (VM) muscle is a conservative treatment used to address some patellofemoral joint (PFJ) problems. The objective of this study was to examine the effects of varying VM strength on PFJ kinematics and contact pressures and areas. We tested five fresh-frozen cadaveric knees using a custom knee jig, which permits the simulation of physiologic quadriceps loading while also allowing the VM force to be varied. PFJ kinematics were measured with a magnetic tracking device. PFJ contact pressures and areas were measured with Fuji pressure-sensitive film. For PFJ kinematics, the change in the medial-lateral and superior-inferior translation was significant at 0% of VM strength and 150% of VM strength with respect to the 100% of VM strength condition (p < 0.05). Extreme changes in the VM force had a statistically significant effect on patellofemoral contact pressures (0% of VM strength (19 +/- 10%) and 150% of VM strength (17 +/- 3%) with respect to 100% of VM strength condition (p < 0.05)). No statistically significant differences were shown in the patellofemoral contact areas (p > 0.05). The functional range of VM strength is between 75% and 125% of total VM strength. The PFJ kinematics and contact pressures were not significantly influenced by VM strength except at extreme conditions (0% of VM strength or 150% of VM strength) in human cadaveric knees.