Dr. Michael Kushner

Knee · Trauma

Distal femur fracture (near the knee)

The distal femur is the end of the thigh bone that forms the upper half of the knee. These fractures occur through high-energy trauma in young people or through falls onto osteoporotic bone in older adults, and they are increasingly common above a knee replacement (a form of periprosthetic fracture). Because they involve a weight-bearing joint, the goal is twofold: realigning the bone y restoring the articular surface of the knee.

The patient has severe pain, deformity and inability to bear weight after the injury. Imaging combines radiographs and CT when the fracture enters the joint, in order to plan the reconstruction.

Most require surgery: depending on the pattern, fixation is with locking plates or an intramedullary nail, aiming for a stable construct that allows early knee movement — the key to avoiding stiffness. When the fracture occurs around a knee replacement, the strategy depends on whether the implant is still well fixed, just as in periprosthetic hip fractures.

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Dr. Kushner’s approach: in the knee, the number one enemy is stiffness. I aim for a construct stable enough to start moving the joint early and regain range of motion.

Signs that mean going to the emergency department

Frequently asked questions

When will I be able to bend the knee?

The aim is to begin mobilisation early, as soon as the fixation allows, to avoid stiffness. Weight-bearing is more gradual.

What if I have a knee replacement?

It is a periprosthetic fracture: it is treated by keeping the implant if it is well fixed, or revising it if it is loose.

Why is this a difficult fracture?

Because it sits next to the knee and involves both the articular surface and the alignment of the limb. Alignment has to be restored and the knee moved early so that it does not stiffen.

When do I start bending the knee?

Generally very early, even in the first few days, even though weight-bearing is delayed. Stiffness is the complication that most limits the final result.

And if I already have a knee replacement?

Then it is a periprosthetic fracture and is managed differently: implant stability has to be assessed before deciding on fixation.

References

  1. Aggarwal S, et al. Comparison of outcomes of retrograde intramedullary nailing versus locking plate fixation in distal femur fractures: a systematic review and meta-analysis. J Orthop. 2022;36:36-48. DOI
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Reviewed by Dr. Michael David Kushner Shrem, orthopaedic and hip, pelvis and trauma surgeon in Panama. AO Foundation Faculty and Education Chair of AO Panama, fellowship-trained at Hadassah Ein Karem Hospital (Hebrew University of Jerusalem).

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Educational information reviewed by Dr. Michael Kushner Shrem. It does not replace an in-person medical assessment.