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
Scott Rubinstein M.D.
I have bone cysts, can I have a hip
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
please see advanced OA with cysts and AVN
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.
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.
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.
Alan Ray – A Patient’s answer
The size of a cyst isn’t
always the issue. Successful resurfacing also depends upon the
location of the cyst. If a cyst occurs in the wrong place on the
femur it can change the way the prosthesis would or could be
If the location of the cyst would compromise the loading angle,
or if it simply occurred along the line where the femoral cap
would be inserted, the load integrity of the resurfacing would