Clive:

You wrote:

<<Patient presented c/o right lateral ankle pain following an injury 2 years
ago, painful every day on rising from bed. He had right medial knee pain
which nags all the time, on and off weight bearing.  There is pain in both
knees related to sitting with knees flexed and to exercise - especially
cycling ( a keen competitive cyclist). He had chronic low back pain.

Exam revealed both patellofemoral syndrome (Clarke's sign).  Biomechanical
exam revealed

B/ Fhl
B/ forefoot evertus 7 degrees
STJ - 5 degrees varus
No equines
Tibial position - left 5 degrees varus, right 10 degrees varus
B/STJ axis orientation - average
Right leg 15 mm short.
Chronic low back pain -  stiffness or pain in lumbar region every day

I initially prescribed B/rearfoot 10 degrees varus/ kinetic wedges. Patient
has put a 10mm raise under the right PMP area in his cycling shoes. After 8
weeks the R/ ankle problem had resolved. The knees were 60% better in
walking and running but still hurt during and after cycling.

He does not ear orthoses when cycling.

I have increased the rearfoot on his orthoses to 15 degrees varus which has
helped the knees off the bike.

I have made him 7 degrees valgus posts under the PMP area on frelens for the
cycling shoes. He finds these "cut of his blood supply" and tilt his knees
in toward the crossbar of the bike and cause his right medial knee pain to
play up. They do not help his knee pain when cycling.

I have already given him a 15mm right heel raise to use if the symptoms do
not continue to improve on walking - he has not used that yet. On my advice
he has raised the saddle on his bike so that the knees are fully extended at
the end of the down stroke

Any cycling biomechanics specialist out there who can offer me advice about
how to proceed from here?>>

The key to treating cyclists is that you need to evaluate them while riding
their bicycle, just as you would evaluate a runner by watching him/her run.
I have the patient bring in the bike, get it set up on a "wind-trainer", and
then have them ride at their normal pace while I watch them ride from
anterior, posterior and lateral.  I don't have the time currently to go
through the whole bike evaluation I do but in this patient I would pay close
attention to the distance from medial malleoulus to the crank arm at the
bottom of the power stroke when observing from anterior.  This is a good
indicator of the position of the STJ/MTJ complex during loading of the foot
during the power stroke.  Also, from anterior, check position and movement
pathway of the knee since this will give you an indication of the
forces/moments acting on the knee.

My advice on the  information you have provided includes:

1.  Get him into at least some form of foot orthosis during cycling, even if
it is only medial arch wedging.
2.  Keep forefoot valgus wedge in cycling shoe, but decrease it by half.
3.  Try wedging between the bike shoe cleat and the shoe sole with a varus
wedge to unload the medial knee.

I have written a few Precision Intricast Newsletters on biking and treating
cyclists:

Kirby, K.A.: Foot and lower extremity biomechanics during cycling. Precision
Intricast Newsletter. May 1999.  Precision Intricast, Inc., Payson, AZ.

Kirby, K.A.: Evaluation and orthosis treatment of the cyclist. Precision
Intricast Newsletter. June 1999.  Precision Intricast, Inc., Payson, AZ.

Kirby, K. A.  "Bicycle biomechanics - volume I and volume II." in: Foot and
Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast
Newsletters.  Precision Intricast, Inc.,  Payson, Arizona, 1997, pp.
227-230.

In addition, I have been involved in two bike studies at UC Davis with the
Department of Mechanical Engineering, the first one is listed below.  The
second one should be published within the next year.

Ruby, Patricia, Maury L. Hull, Kevin A. Kirby, and David W. Jenkins:  "The
Effect of Lower-Limb Anatomy on Knee Loads During Seated Cycling", Journal
of Biomechanics, 25 (10): 1195-1207, October 1992.

Hope this helps.

Cheers,

Kevin

************************************************
Kevin A. Kirby, DPM
Assistant Clinical Professor of Biomechanics
California College of Podiatric Medicine

e-mail:  [log in to unmask]
************************************************

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