Notas / Notes - Active Congress.......

JUEVES / THURSDAY
134
motion, absence of inflammatory arthritis or diffuse synovitis
and the absence of severe instability with relatively well
maintained range of motion. Significant instability should
be managed prior to procedures directed to managing the
cartilage deterioration, but most procedures directed to
isolated uni-compartmental disease assume that the knee
is intrinsically stable .
UNICONDYLAR KNEE ARTHROPLASTY
In general arthroplasty, including unicondylar knee arthroplasty
is most appropriate for older, more sedentary patients with
true isolated uni-compartmental tibio-femoral arthritis. Patients
with isolated uni-condylar osteonecrosis with reasonable
amounts of healthy underlying bone to support the component
are also excellent candidates. Optimal results are obtained
in non-obese patients without patellofemoral symptoms who
have functioning anterior and posterior cruciate ligaments
and range of motion greater than 120 degrees. Minor degrees
of patello-femoral symptoms and less range of motion may
be considered, but in general the isolated re-surfacing of the
joint will not improve these findings. Minimal and passively
correctable deformity are important pre-requisites for optimum
results. Some consider that early arthritis isolated to the
antero-medial aspect of the joint is the ideal indication for
this procedure. In this setting the presence of a normal
postero-medial compartment prevents medial collateral ligament
contracture and renders ligament releases unnecessary.
More severe involvement of the medial com-partment leads
to contracture of the ligament and may require some degree
of release to appropriately balance the joint but more than
15 degrees of varus is considered the upper limit of acceptable
deformity. Additionally the patient should not exhibit more
than one centimeter of medial-lateral translation, this degree
of instability precludes the likelihood of a durable result with
uni-compartmental arthroplasty.
Contraindications for uni-compartmental arthroplasty would
include tri-compartmental or inflammatory arthritis of the
knee. Significant patello-femoral symptoms and greater than
Outerbridge grade 2 chondrosis of the patellofemoral or contralateral
compartments as determined intra-operatively
would also be contra-indications. Clinically relevant findings
of range of motion less than 90 degrees, flexion contracture
more than 10 degrees and deformity of more than 10 degrees
of varus or15 degrees of valgus would favor total knee arthroplasty.
Deficiency of the anterior or posterior cruciate ligaments,
and certainly clinical evidence of any medial or lateral
ligamentous instability would also contra-indicate UKA.
Less rigid contra-indications include the desire to return to
strenous activities involving running, high impact loading and
high torque load, obesity as well as unrealistic expectations
from surgical intervention. This would include patients with
fibromyalgia or those who have responded poorly to multiple
previous interventions.
TOTAL KNEE ARTHROPLASTY
Total knee arthroplasty is indicated for patients with osteoarthritis
of the knee who have failed non-operative treatment
and are not considered to be a good candidate for one of
the alternative procedures previously mentioned. The majority
of patients have arthritis affecting two compartments of the
knee although good results have been reported for the treatment
of older patients with isolated patello femoral arthritis.
Excellent long-term results have been reported with survivorship
exceeding 90% at a follow-up of more than 20 years
in one recently reported series. Additional evidence indicate
that patients may obtain higher levels of physical function
after TKA than do patients who have undergone osteotmy.
Unicompartmental Arthroplasty versus Total Knee Arthroplasty
In our experience, it is most common to have to decide between
total knee and unicondylar arthroplasty than between
high tibial osteotomy and unicompartmental arthroplasty.
Deciding between these two options can be difficult. The
selection criteria for unicompartmental arthroplasty is much
more exacting than for total knee arthroplasty and thus the
results may not be as predictable as total knee arthroplasty
for many surgeons. Specifically, it is unclear how much radiological
or clinical involvement of the other compartments
is acceptable and the surgeon must carefully judge how
much tolerance a particular patient may have for persistent
pain from the other compartments of the joint that have not
been resurfaced.