Add like
Add dislike
Add to saved papers

Does Screw Location Affect the Risk of Subtrochanteric Femur Fracture After Femoral Neck Fixation? A Biomechanical Study.

BACKGROUND: Case reports suggest that there is an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws when the distal-most screw is placed distal to the lesser trochanter. However, to our knowledge, there are no biomechanical data supporting this observation.

QUESTIONS/PURPOSES: (1) Is there an increased risk of subtrochanteric femur fracture after femoral neck fixation with cannulated screws in normal density and osteoporotic Sawbones when the distal-most screw is started distal to the lesser trochanter? (2) Does the screw starting point position after femoral neck fixation with cannulated screws affect load to failure when normal density and osteoporotic Sawbones are loaded through their mechanical axis?

METHODS: Normal density and osteoporotic Sawbones femora were instrumented with three cannulated screws in a triangular apex distal configuration with the distal-most screw starting either proximal to, at, or distal to the level of the lesser trochanter. Specimens were loaded along the mechanical axis to failure. The fracture location and ultimate load to failure were compared between groups.

RESULTS: The screw start point distal to the lesser trochanter resulted in a greater proportion of subtrochanteric femur fractures compared with screw start points at or proximal to the lesser trochanter in the subset of osteoporotic specimens (three of 10 specimens versus 0 of 20 specimens; p = 0.030). No subtrochanteric femur fractures were observed in the normal density specimens. Load to failure was lower when the distal-most screw was started distal to the lesser trochanter than when it was started at or proximal to the lesser trochanter (normal density subset 13,502 ± 1980 N versus 14,675 ±1528 N; osteoporotic subset 8946 ± 1509 N versus 10,026 ± 1256 N; linear regression coefficient 1127 N [95% CI 298 to 1956 N]; adjusted r = 0.71; p = 0.009).

CONCLUSIONS: A screw start point distal to the lesser trochanter was associated with subtrochanteric femur fractures in the osteoporotic subset. Additionally, there was decreased load to failure when the distal-most screw was started distal to the lesser trochanter.

CLINICAL RELEVANCE: These data suggest that avoiding a screw start point distal to the level of the lesser trochanter in femoral neck fracture fixation may decrease the risk of catastrophic subtrochanteric femur fractures, especially in patients with osteoporosis. However, it should be noted that a more overall varus screw alignment could theoretically compromise the ability to achieve compression across the fracture, with attendant implications with regard to fracture union in the acute setting.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

Related Resources

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app