FAQ – Bone Cysts

I Have Bone Cysts – Can I Have a Hip Resurfacing?

Dr. Rubinstein
Cysts are very common in arthritic hips and can usually be seen on x-rays. Most
of the time they are not a problem with resurfacing because they are small and
in the part of the bone removed in milling the femoral head for a resurf. Most
larger ones can be filled with a cement of bone chips and still do a good resurf.
The only cysts that are problematic are those that erode the superior femoral
neck weakening the bone at a critical place. This can lead to fracture with a
resurf and that is an indication for a THR instead. They can usually be seen on
a pre op x-ray so I can tell the patient that a resurf may not be possible and a
decision can be made at surgery. In the one case I was surprised on the cyst was
under a large osteophyte and was obscured on the x-ray. The patient got a big
head metal-metal THR and is doing fine.

Many cysts can be seen on plain x-ray. For 3-D analysis a CT scan is much better
then an MRI but rarely needed. If no cysts are seen on x-ray it is unlikely that
clinically significant ones will be seen at the time of surgery. When I
encounter larger cysts on x-ray I will sometimes get a CT but usually not. I
will instead inform the patient that the cysts may make a resurf impossible
depending on the size and location of the cyst. A final decision is made in
surgery. Most cysts can be bone grafted or if smaller filled with cement. If
cysts large enough to prevent a resurf are encountered then I proceed with a mig
head M-M THR using the same acetabular component as for the resurf. Only once
have I been surprised and needed to do a THR unexpectedly and that was a
superior neck cyst that was hidden under an osteophyte. The other times I needed
to go with a THR intraop I had predicted it on the pre op x-rays and counseled
the patient accordingly.

As a patient I wouldn’t worry about it because the anatomy is what it is. The
anatomy will dictate the course us surgeons need to take. Just get a surgeon you
trust and who is a fan of resurfs and let them do their job with the best
judgement they know.

Scott Rubinstein M.D.

Dr. Bose

I have bone cysts, can I have a hip resurfacing?

The presence of a cysts by itself is not a contraindication for resurfacing. It
does not preclude resurfacing automatically. One must keep in mind that cyst
formation is a natural occurrence in osteoarthritis and is very common though
the extent, quantity & location may vary.

Cysts are of course much more common and invariably present in AVN. The
assessment of certain technical factors would the real issue. This is based on
the amount of residual bone after head preparation. Some resurfacing prosthesis
are thicker at the top and tend to replace more bone in the head of the femur
than other prosthesis. This is a great advantage in managing cysts as at the end
of head preparation one is left with nearly 100% head support in a majority of
cases. The cysts get reamed away in bone that would have been removed anyway.
The BHR is a good example of a prosthesis of this type.

The technical criteria which we we have been using in our centre ( ARCH) for the
last 7 yrs without any problems has been termed as ‘mid – path recommendations’
because we chose 50% as an arbitrary value when we started.

1.The criteria are an intact – head neck junction across the entire
circumference to a height of 50% of profile cut ( the actual height would vary
depending on the size used)

2. Residual bone above the intack head neck junction must be at least 50%

Dr . Sugano from Japan has done an experiment where he removed 50% of head of
fresh cadaveric bones and implanted a cemented resurfacing on them . He also
implanted a cemented resurfacing on an equal amt of fresh cadaveric bones with
an intact head. He compared the mechanical strength of both in the lab and found
the mech. strength to be equal in both groups.

The surgeon has to see the x-rays and CT scan before he can comment on a
particular case.

I have tackled successfully some hips with significant cyst formation. http://www.hipresurfacingindia.com/Hip_Resurface_Complex_Cases.php
please see advanced OA with cysts and AVN

Dr. Mont

Bone spurs on femoral neck are not a contraindication for resurfacing–but
obviously each x-ray would have to be looked at individually–almost all
arthritis is associated with spurs on neck by the way.

Dr. Vail
Among the criteria Dr. Vail considers (for hip resurfacing) are age (under 60 is
ideal), bone density and the shape of a person’s hip. He also looks for cysts in
the ball of the hip, which signal the bone might be too weak for capping.

FDA on Bone Cysts involved in BHR

Its use (BHR) is also contraindicated in patients who are severely overweight
and those whose bones are not strong/healthy enough due to osteoporosis or a
family history of severe bone loss; bone loss affecting more than half of the
femoral head; or multiple cysts larger than 1 cm in the femoral head. A test
such as a DEXA scan may be required to determine the level of bone loss.