Polaris OBark

My wife just had a hip replacement. Her right femur is now about 5cm longer than her left. Her PT is alarmed. We will talk to the surgeon in a few days. Even if this does settle in a bit, somehow, it looks like she now has a significant difference that will need to be considered. She currently is using a 165mm GRX crankset and flat pedals.

Would it make any sense to have a 172.5 or 175 mm right-side crank-arm and a 165 mm on the left? This still is only 20% of the length difference.

I can't imagine having a huge shim. I tried a 3mm shim once and it drove me nuts; I had to take it out mid-ride. 25 to 50 mm seems extreme. Also, her knees will be in different places if it is shimmed like this.

The irony is that before the hip replacement, biking was her escape from pain. Walking was the main problem. She did a 50 mile ride with 120 Strava achievements 4 days before the operation. Now I worry biking will be torture.

zandoval 

WOW! - Unfortunately its one of those wait and see dilemmas... RATS!

Also try to remember that a majority of people have almost 2cm leg length differences naturally and have no problems at all. So really you are only looking at about 2.5 cm of critical differences.

Again, you are still at the have to wait and see stage of this whole thing. As an active woman she has a great advantage in recovery. When she gets back to ridding again be sure to drop the seat about 2cm at the start and no mashing. Remember that Docs often forget the importance of Calcium Magnesium and Zinc supplementation along with Glucosamine and Chondroitin. Also remember that if she has low estrogen levels she will not be able to absorb the extra calcium supplements she is taking.

As a PA-C I usually end up addressing these things in my post hip surgical patients.

Polaris OBark

She is 8 days out, so I agree it is early. Apart from that, the recovery has been going really well.

jon c. 

No advice to offer, but good luck to her.

Russ Roth

Can always do a couple of origin8 crank sets and go square taper. They have a 140mm that you could pair with a 165 or 170 to make up most of the difference. Other than that, it is possible to find a halfway decent crankset that can be cut down on one side, drilled and tapped. Its been a few years but I ended up recommending this with I think an sr suntour crankset for the wife's cousin. He's got a birth defect that resulted in a 4cm difference, once we found the crank he managed to find a LBS that was willing to drill and tap. You're looking for a crank that isn't hollow and doesn't have a lot of relief cutout on the back of the arms, something that's flat and solidly square front to back. Sram s300 cranks had been good for this as well.

Leisesturm

I would think that cycling will be the least of her adaptations after something like this. I would not be looking at crank or pedal solutions just yet because, if it were me, I would be pursuing a surgical correction of the issue. It does not sound like it was foreseen. It's not the most informative or helpful article ever, but I found this during a Google search on your behalf.

Iride01 

5 cm? Almost 2 inches? If you are correct on the units and didn't mean mm, then I'd be asking a lot of questions of all the doctors and medical staff involved with the replacement.

Was there any advance notice by the doctors that there'd be a big difference in leg length?

Polaris OBark

Yes, the difference is about 2" relative to the other one. It was initially her shorter leg. We were informed leg length difference was a common complication, but this one seems a bit extreme.

Probably the best correction is doing the other hip when the time comes (it is well on its way) and matching them. But if their error bars for matching are 2", who knows?

tomato coupe

Where did you come up with that? Real world statistics tell a different story:

41% < 4mm
37% 5mm - 9mm
15% 10mm - 14mm
6% > 14mm

Polaris OBark

I had assumed he meant mm. But yes, an approx. inch difference is extreme.

I really hope in my wife's case it is some sort of artifact.

zandoval 

Its true, but functional leg discrepancies vary. Especially in places other then the USA. The old rule was don't really consider treatment till approaching 20mm. At 20mm small changes can make a difference. Of course things vary also when comparing recommendations of Orthotists v/s Orthopods v/s Podiatrists v/s Kinesiologists. Whats also a factor here is that we are looking at increased Femur Length. Tib/Fib length and knee size and function is the same.

All in all its is unfortunately a wait and see problem. To bad we can't kick the can down the road about 18 months for an observation and try to fix things now.

Here is a good German Publication from more than 20 years ago for an illustration.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477698/

Kontact 

Femur differences are best dealt with via fore/aft cleat location. (Long femur has aft cleat, short femur gets forward cleat.)

Shin length differences with cleat shims.

This may require a bit of both.

Polaris OBark

Sorry, only just saw this. She is on flat pedals at the moment, and appears to be doing naturally what you suggest for the femur length difference. (Her shin lengths are the same).

Fredo76

After my left hip replacement was re-done (due to four dislocations, ugh), I had to wear a right shoe with a 3/4" thicker sole (just took it to a shoe repair place to add the needed sole thickness).

You have already surmised the remedy - get the other hip done. My doctor did not want me cycling until both were finished and healed.