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After more than 20 years of
debate the decision whether to resurface the patella or not
during primary Total Knee Arthroplasty (TKA) remains
controversial. So the ideal treatment for patella in primary TKA
remains unclear. Patellar complications during primary TKA have
begun to emerge as a major cause of failure.
Placement of patellar component
is usually more difficult than placement of any other component
in TKA. It is usually the first component to fail after TKA.
There are no specialized jigs available to do the patellar cut,
even in Computer Assisted Orthopaedic Surgery (CAOS), but
several jigs are being perfected but even now a perfect jig is
not available commercially. In 1980s, there were several reports
of complications related to patellar resurfacing.
Many randomized trials have
provided inconclusive evidence regarding the fact that patellar
should be resurfaced or not. There are reports that a resurfaced
patella may also be symptomatic with anterior knee pain. I aimed
to understand the current concept from literature regarding
whether the patella should be resurfaced or not routinely during
primary TKA.
Arnold MP et al1 in their study concluded
that using a blood supply preserving approach and a
biomechanically adequate implant TKA without patellar
replacement gives excellent long term results. They showed in a
long term follow up study of TKA that the femoro-patellar joint
is an important problem after TKA.
Barrack RL2 in his study was of the opinion
that every study to date has suggested that kinematics are more
abnormal when patella is resurfaced than when it is retained. He
also concluded that the patello-femoral contact areas are higher
and contact stresses are lower in the native patella compared
with resurfaced patella after TKA. Virtually every clinical
study of bilateral knee arthroplasty in which patella has been
resurfaced and the other has not shown either equivalent results
or a preference for the unresurfaced side. Laboratory and
clinical data indicate that not resurfacing the patella is a
viable if not a preferable option in most TKA patients.
Burnett RS et al3 concluded that the
management of patella in TKA traditionally has been one of the
three options: always resurface, never surface or selectively
resurface the patella. They also concluded that anterior knee
pain before and after TKA much not always be presumed to be
secondary to patello-femoral resurfacing / non-resurfacing
etiology and other factors may play a role in the dynamic
development of anterior knee pain after TKA. The decision to
resurface the patella in TKA remains controversial, and the
results of long term randomized controlled trails will improve
the understanding of this complex issue in the future.
Churchill DL et al4 were of the opinion
that increasing the femoral roll back in flexion is thought to
reduce the patello-femoral contact load in total knee
arthroplasty. Posterior cruciate ligament (PCL) substituting TKA
produced greatest and the most reproducible roll back. Moving
the tibial post posteriorly, further increase the roll back.
Increased roll back correlated with reduced patellar load.
Quadriceps loads were reduced by increasing the roll back but to
a smaller degree. The roll back primarily affects patellar load
rather than the quadriceps or efficiency.
Feller JA et al5 concluded that stair
climbing ability was significantly better in the patellar
retention group. Although there were no complications related to
patellar resurfacing, in the medium term follow up, they did not
find any significant benefit from re-surfacing the patella
during TKA for osteoarthritis, if it was not severely deformed.
Harwin SF et al6 opined that successful
femoropatellar resurfacing (PFR) can be accomplished with
minimal complications if the following technical considerations
are met: 5-7 degrees of valgus alignment; medial placement of
patellar component, taking care not to increase either the AP
diameter of the knee or the thickness of the patella; avoiding
internal rotation either in the tibia or in the femor and proper
soft tissue balance. If anything goes wrong, patello-femoral
complication is a usual outcome.
Holt GE et al7 in their study made a final
conclusion that patello-femoral complications the greatest
argument against resurfacing of the patella can be diminished
with improved surgical techniques and better implant designs.
Kelly MA8 was of the opinion that the
diagnosis and treatment of the more-frequent complications
should be studied in detail. Although this complications may be
successfully treated, most may be largely avoided with proper
surgical technique and prosthetic component design.
Levitsky KA et al9 inferred that in
patients meeting the selection criteria, TKA without resurfacing
the patella provided satisfactory long term results and a high
degree of patient satisfaction with an absence of mechanical
complications and no reoperations at an average of 7½ years of
follow up evaluation.
Matsuda S et al10 opined that design
features of the patello-femoral portion of TKA component are
important factors that affect contact stresses in the
patellofemoral joint. These features will likely affect the
clinical results of TKA with an unresurfaced patella.
Ogon M et al11 concluded that Patellar
complications were more often found in the resurfaced group than
in the group without resurfacing. The results indicate overall
no advantage of patella resurfacing compared with patella
retention in the long run.
Poll FE et al12 using temporal-spatial
parameters and kinematic and kinetic variables at the knee joint
were tested for significance using the repeated measures
analysis of variance (ANOVA). There were no significant
differences in the biomechanics of walking, stair climbing or
chair rising between patients after TKA with and without a
resurfaced patella. So they did not find any advantage of
resurfacing the patella.
Reuben JD et al13 inferred that TKA system
should include instrumentation that allows precise restoration
of overall patellar thickness while maintaining a bony patellar
thickness of at least 15mm will only produce better results.
They also concluded that patellar complications following total
knee arthroplasty have begun to emerge as a major cause of
failure.
Stiehl JB et al14 were of the opinion that
kinematic abnormalities of the prosthetic patellofemoral joint
may reduce the effective extensor movement after TKA.
Majority of the current
articles are favouring the non-resurfaced patella in terms of
anterior-knee pain, functional outcome and patient satisfaction.
Newer designs are compatible with natural patella and there is a
perfect remodeling of the natural patella in the non-resurfaced
group.
So majority of the future TKA
may be of patellar non-surfaced type provided better prosthetic
designs are available.
References:
Arnold MP, Friedrich NF, Widmer H, Muller
W. Patellar Substitution in total knee prosthesis – is it
important?, Orthopade, 1998; 27(9) 637-41.
Barrack RL. Orthopaedic Crossfire – All
patellae should be resurfaced during primary total knee
arthroplasty : in opposition. J. Arthroplasty. 2003; (3 Suppl
1) 35-8.
Burnett RS, Bourne RB. Indications for
patellar resurfacing in total knee arthroplasty. Instr Course
Lect. 2004; 53: 167-86.
Churchill DL, Incavo SJ, Johnson CC,
Beynnon BD. The Influence of femoral rollback on patellofemoral
contact loads in total knee arthroplasty. J Arthroplasty. 2001;
Oct.16(7): 909-18.
Feller JA, Bartlett RJ, Lang DM. Patellar
resurfacing versus retention in total knee arthroplasty. JBJS
Br. 1996; 78(2): 226-8.
Harwin SF, Stein AJ, Stern RE.
Patellofemoral resurfacing at total knee arthroplasty. Contemp
Orthop. 1994; 29(4): 265-71.
Holt GE, Dennis DA. The role of patellar
resurfacing in total knee arthroplasty. Clin. Orthop. 2003; 416:
76-83.
Kelly MA. Patellofemoral complications
following total knee arthroplasty. Instr Course Lect. 2001; 50:
403-7.
Levitsky KA, Harris WJ, McManus J, Scott
RD. Total knee arthroplasty without patellar resurfacing.
Clinical outcomes and long-term follow-up evaluation. Clin.
Orthop. 1993; 286: 116-21.
Matsuda S, Ishinishi T, Whiteside LA.
Contact stresses with an unresurfaced patella in total knee
arthroplasty : the effect of femoral component design.
Orthopedics, 2000; 23(3): 213-8.
Ogon M, Hartig F, Bach C, Nogler M,
Steingruber I, Biedermann R. Patella resurfacing : no benefit
for the long-term outcome of total knee arthroplasty. A 10 to
16.3 year follow up. Arch Orthop Trauma Surg. 2002; 122(4):
229-34.
Pollo FE, Jackson RW, Koeter S, Ansari S,
Motley GS, Rathjen KW. Walking, chair rising and stair climbing
after total knee arthroplasty: patellar resurfacing versus
non-resurfacing. Am J Knee Surg. 2000 Spring 13(2): 103-8.
Disussion 108-9.
Reuben JD, McDonald CL, Woodard PL,
Hennington LJ. Effect of patella thickness on patella strain
following total knee arthroplasty. Arthroplasty. 1991; 6(3):
251-8.
Stiehl JB, Komistek RD, Dennis DA, Keblish
PA. Kinematics of the patellofemoral joint in total knee
arthroplasty. J Arthroplasty. 2001; 16(6): 706-14. |
