Further consideration of the curvature of the Neandertal Femur

Sagittal Plane Considerations During Long Cephalomedullary Nailing: Optimal Distal Positioning and the Role of Intraoperative Nail Bending

OBJECTIVE

To retrospectively review a large population of long cephalomedullary nails with special attention to distal implant position in the sagittal plane and assess the ability to avoid anterior cortical contact (ACC) by bending the distal tip of the nail intraoperatively.

DESIGN

Retrospective review of single surgeon experience.

SETTING

Single Level 1 trauma center.

OUTCOMES

Radiographic position of the cephalomedullary nail with respect to the anterior femoral cortex and the effects of intraoperative bending of the distal tip of the nail.

PATIENTS

A total of 215 patients who underwent long cephalomedullary nailing for peritrochanteric hip fractures between 2007 and 2017 were reviewed.

RESULTS

In the period between 2007 and October 2013, ACC of the distal portion of the nail in the sagittal plane was a common finding. Its incidence significantly decreased after intraoperative bending of long cephalomedullary nails was incorporated into practice in cases where sagittal plane impingement was detected (P < 0.0001). ACC was more prevalent if the final nail position was proximal to the level of the patella.

CONCLUSION

Careful attention should be paid to sagittal plane anatomy and distal ACC during insertion of a long cephalomedullary nail. One strategy to prevent anterior impingement or perforation may be intraoperative bending of the distal end of the nail.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Articular Geometry Reconstruction for Knee Joint with a Wearable Compliant Device

Nonlinear articular geometries of biological joints have contributed to highly agile and adaptable human-body motions. However, human–machine interaction could potentially distort natural human motions if the artificial mechanisms overload the articular surfaces and constrain biological joint kinematics. It is desired to better understand the deformable articular geometries of biological joints in vivo during movements for design and control of wearable robotics. An articular geometry reconstruction method is proposed to measure the effective articular profile with a wearable compliant device and illustrated with its application to knee-joint kinematic analysis. Regarding the joint articulation as boundary constraints for the compliant mechanism, the equivalent articular geometry is constructed from the beam deformations driven by knee motions, where the continuous deformations are estimated with strain data from the embedded sensors. Both simulated analysis and experimental validation are presented to justify the proposed method.