Proximal femoral anatomy in the normal human population.

UNLABELLED: In this study, we developed a complete description of the morphology of the proximal femur. Then, using this framework, we (1) determined normal population means, standard deviations, and ranges; (2) established differences among subpopulations; and (3) showed correlations among the various measurements. To accomplish these objectives, we analyzed 375 adult femurs. Specimens were digitally photographed in standardized positions, measurements being obtained using ImageJ software. Three parameters of the head-neck relationship were assessed. Translation was examined through four raw offset measurements (anterior, posterior, superior, inferior) used to calculate anterior-posterior and superior-inferior ratios. Rotation was investigated through anteroposterior (AP) and lateral physeal angles. Concavity was examined using alpha, beta, gamma, and delta angles. Two parameters of the neck-shaft relationship were assessed, neck version and angle of inclination. Average anterior-posterior and superior-inferior ratios were 1.14 and 0.90. Average AP and lateral physeal angles were 74.33 degrees and 81.83 degrees , respectively. Averages for alpha, beta, gamma, and delta angles were 45.61 degrees , 41.85 degrees , 53.46 degrees , and 42.95 degrees , respectively. Average neck version and angle of inclination were 9.73 degrees and 129.23 degrees , respectively. Differences existed between males and females and between those younger and older than 50 years. Correlations were observed between translation and concavity, and translation and the neck-shaft relationships. LEVEL OF EVIDENCE: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Relationship of inferior gluteal nerves and vessels: target for application of stimulation devices for the prevention of pressure ulcers in spinal cord injury.

A study was carried out to determine whether the location of the inferior gluteal nerve could be reliably predicted using external anatomy or vascular imaging. This study was motivated by our group's development of an electrical stimulation system to provide direct gluteal stimulation in paralyzed individuals, in particular those with spinal cord injury (SCI). Pressure ulcers are a common complication for many individuals with reduced mobility. Numerous approaches have been employed to treat and prevent pressure ulcers; however no procedure or nursing care regimen has been successful in eradicating them completely. Our group seeks to prevent skin breakdown in susceptible patients by direct electrical stimulation of the paralyzed gluteal muscle, leading to improved circulation and increased muscle mass (hypertrophy) in the treated area. Currently, percutaneous electrodes are placed through an extensive probing process to select the motor point of the target muscle. We examined 15 cadaver gluteal regions to identify the relationship between the internal anatomy of the inferior gluteal artery and nerve as well as the relationship to external anatomic landmarks. The cadavers displayed variability with regard to the morphology of the branches of both nerve and artery. Furthermore, there did not appear to be any relationship between the relative positions of the nerve and artery. However, the potential target area of the proximal origin of the inferior gluteal nerve could reliably be predicted from the external bony anatomy of the lower pelvis.

Analysis of anatomic periarticular tibial plate fit on normal adults.

Implant manufacturers are producing anatomically contoured periarticular plates to improve the treatment of proximal tibia fractures. We assessed the accuracy of the designation anatomic. We applied eight-hole medial and lateral anatomically contoured periarticular plates to 101 cadaveric tibiae. The tibiae and the plate fits were mapped, quantified, and analyzed using a MicroScribe G2LX digitizer, Rhinoceros software, and MATLAB software. By corresponding the clinical appearance of good fit with our digital findings, we created numerical criteria for plate fit in three planes: coronal (volume of free space between the plate and bone), sagittal (alignment with the tibial plateau and shaft), and axial (match in curvature between the proximal horizontal part of the plate and the tibial plateau). An anatomic fit should mirror the shape of the tibia in all three planes, and only four medial and four lateral plate fits qualified. Recognizing and understanding the substantial variations in fit that exist between anatomically contoured plates and the tibia may help lead to a more stable fixation and prevent malreduction of the fracture and/or soft tissue impingement.

Anatomic considerations for the placement of C2 laminar screws.

STUDY DESIGN: Cadaveric study. OBJECTIVE: To study the applicability of C2 laminar screw placement in the general adult population and to provide useful guidelines for their safe placement. SUMMARY OF BACKGROUND DATA: Laminar screws for fixation into the second cervical vertebra are becoming an increasingly used technique since they eliminate the risk of vertebral artery injury. Although it is being used clinically, there are no published data that describe the anatomic considerations and potential limitations of this technique in the general population. METHODS: The C2 vertebrae of 420 adult specimens were studied. Laminar thickness, spinolaminar angle, and the length from the spinolaminar junction to the contralateral lamina/lateral mass junction were measured. Statistical analysis was performed using unpaired Student t tests and regression analysis (P < 0.05). RESULTS: Mean laminar thickness was 5.77 +/- 1.31 mm; 70.6% of specimens had a laminar thickness > or =5 mm; 92.6% had a thickness > or =4.0 mm. The spinolaminar angle was 48.59 degrees +/- 5.42 degrees. The mean screw length that could be used was 2.46 +/- 0.23 cm. More than 99% of specimens had an estimated screw length of at least 20 mm. Gender had a significant effect on all of the measurements studied, but race, height, and weight did not. CONCLUSION: The majority of specimens can safely accept placement of a laminar screw. This study establishes anatomic guidelines to allow for accurate screw selection and insertion. Preoperative planning is essential for safe screw placement via this technique.