Femoral cam deformity due to anterior capsular force: A theoretical model with MRI and cadaveric correlation.

BACKGROUND: Cam deformity is associated with epiphyseal extension onto the anterosuperior femoral head-neck before physeal closure. A century ago, anatomists speculated that this femoral prominence acts as a pulley bar to withstand capsular compression in hip extension with pressure concentrated where the zona orbicularis (ZO) joins the iliofemoral ligament (IFL). An animal model has shown that growth plates deflect laterally and distally when exposed to forces perpendicular to growth. These observations raise the question of whether capsular pressure against the epiphysis can stimulate cam formation. PURPOSE: The purposes are to measure: (1) the distance from the ZO/IFL confluence to the maximal epiphyseal extension (MEE) and cam apex; and (2) acetabular depth at this location, since less coverage increases capsular contact on the physis. METHODS: MRI scans of 39 subjects (47 hips) were measured. Acetabular depth was compared between those with and without a cam deformity. Secondarily, anatomic findings were correlated on a cadaveric specimen. RESULTS: The cam apex and MEE were adjacent to the ZO/IFL confluence in all subjects (mean, 6.3 mm). Controlling for sex, acetabular depth was less (12.5%, p = 0.012) in the group with cam deformity. Contact points were confirmed in the specimen. CONCLUSIONS: The cam apex and MEE occur at the ZO/IFL confluence in the thickest region of the anterosuperior capsule and vary with acetabular depth. This supports a theoretical model postulating that capsular forces against an immature epiphysis may induce cam formation, particularly in individuals who repetitively tension the anterior capsule.

The effect of collagenase and hyaluronidase on transient perfusion in human osteosarcoma xenografts grown orthotopically and in dorsal skinfold chambers.

BACKGROUND: Collagenase and hyaluronidase are enzymes which degrade the extracellular matrix and increase the uptake and improve the distribution of therapeutic macromolecules in tumours. The purpose of the present work was to investigate whether collagenase or hyaluronidase had any effects on transient perfusion and/or changes in vascular areas. MATERIALS AND METHODS: The effects were studied in human osteosarcomas in BALB/c nu/nu mice growing orthotopically around and infiltrating the femurs, and in dorsal skinfold chambers using confocal laser scanning microscopy. RESULTS: Both collagenase and hyaluronidase reduced the number of vessels that closed, but only collagenase increased the number of vessels which opened up, i.e. both enzymes improved the perfusion but collagenase to a greater extent than hyaluronidase. CONCLUSION: Destroying the structural protein network seems to be more efficient than degrading the gel of hyaluronan with respect to increase perfusion.

Relative electron dosimetry using the Scanditronix-Wellhöfer Beam Imaging System-2G.

The Beam Imaging System 2G (BIS-2G) from Scanditronix-Wellhöfer is a two-dimensional (2D) charge-coupled device (CCD)-camera that measures the scintillation light produced by incident radiation. We examined the performance of the BIS-2G as a tool in quality control of patient boluses. In an attempt to simplify the production of the patient boluses, bolus edges were built as staircases and the dose distributions were measured and compared to the dose profiles below corresponding sloped bolus edges. Perspex plates covering half the irradiated field were used as generalized bolus edges. All BIS-2G measurements were performed using buildup of solid water while a diode measured corresponding dose profiles in a water phantom. Below the patient boluses, regions with doses < 95% and > 107% of the prescribed dose were defined. Below the edge, the relative doses measured by the BIS-2G were generally within 3% in dose and 3 mm in position compared to the diode measurements. Close to the field edge below the bolus, the BIS-2G measurements were in some cases as much as 7% lower in dose than the diode measurements. The BIS-2G measurements revealed hotspots below the patient boluses covering 1-16% of the total irradiated area. The highest point dose measured below the patient boluses ranged from 105% to 125% of the prescribed dose. For all bolus thicknesses, each edge in the staircase bolus caused a fluctuation in dose and increased the maximum dose compared to the sloped edge. For several cases, the maximum dose increased with 13% in relative dose, e.g., from 103% to 116%. The BIS-2G was found to be a useful tool in quality control of patient boluses, revealing large hot spots in the treatment volume for several patients. Bolus edges built as staircases cause considerable dose fluctuations and increase the maximum dose, and can therefore not be recommended.

Measurements and treatment planning calculations of electron dose distributions below bolus edges.

Electron dose distributions below bolus edges of various thicknesses and angles were measured using a diode in a water phantom. The measurements were compared with treatment planning calculations using the gamma method. Below 5 mm boluses, the dose variations were acceptable for all angles, while for boluses thicker than 5mm, the lowest edge gave the smallest dose variations. The calculated dose distributions agreed well with the measured dose distributions.