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JUEVES / THURSDAY
222
SOURCES OF ERRORS IN
TOTAL KNEE ARTHROPLASTY:
THE IMPORTANCE OF
CAREFUL, ACCURATE
INTRA-OPERATIVE
MEASUEREMENT
D. Stulberg
Northwestern University Feinberg School
of Medicine - Chicago, Illinois, USA
EVOLUTION OF THE
CRUCIATE RETAINING TKA
V. M Goldberg, M.D
Department of Orthopaedics
Case Western Reserve University
University Hospitals of Cleveland
Cleveland, Ohio, USA
The function of the PCL includes transmission
of load, preventing posterior tibial subluxation
in fl exion, enhanced femoral rollback which
increases flexion, enhanced quadriceps
power and increased effi ciency in stair climbing.
The PCL provides primary and secondary
stability, enhanced proprioception and
reduced the shear stresses at the implant
interface. Additionally if one retains the PCL
the jointline is usually more easily maintained;
kinematics of the total knee replacement is
enhanced, and femoral bone stock may be
preserved. However, if the PCL is retained,
you must have optimum component design
and excellent surgical technique.
Critical in the femoral component design is
an optimal fi t of the femur reconstructing the
anterior-posterior dimensions of the medial
femoral condyle and duplicating the different
radius of curvatures of the lateral and
medial condyle for effective kinematics of
the knee. Tibial articulating geometry also
should support the knee rollback and rotation.
The sagittal plane resection (posterior slope)
of the tibial must also duplicate the patient’s
anatomy. Studies of stair climbing and walking
by Andriacchi, Dorr and Kelman indicate
the PCL-sparing knee replacements provide
an improved kinematic outcome for total knee
arthroplasty. Our own initial experience with
442 consecutive primary knees retaining the
posterior cruciate between August, 1989 and
June, 1994, demonstrated over 90% excellent/good
results with an average range of
motion of 112 degrees. With a minimum
twelve year follow-up there have been 20
revisions. (2 for loosening, 18 for wear/osteolysis).
A newer design to address the
issues of wear, enhance range of motion and
femoral-patellar function has been used since
1995. Our fi rst 104 PCL sparing knees for osteoarthritis
have been followed for 7-9 years.
The average Knee Score is 94.6, Function
score 88.9 and average range of motion of
117 degrees. There is a 100% survival of
these total knee replacements without any
pending revisions. There are still a number
of issues that require solution
These include: range of motion, better materials
for improved wear, enhanced soft
tissue balancing. and component position
and improved rate of recovery of the patient
Issues which have been resolved are fi xation,
instrumentation, alignment, excellent pain
relief and good function. Successful total
knee replacement still depends on patient
selection, implant design and post-operative
rehabilitation.