UNA PATELLA PARTICULARE
Patellar resurfacing in total knee arthroplasty: a randomized controlled clinical trial

Total knee arthroplasty (TKA) is a well-established surgical procedure
effective in relieving pain and improving function in patients suffering from
knee osteoarthritis (OA). However, it remains unclear whether the patella
should be resurfaced during TKA. Resurfacing the patella is considered to
lower the incidence of patellofemoral complaints after this procedure.
Numerous studies have analysed the results and risks of patellar resurfacing. A
meta analysis including 1223 knees showed a reduction in the absolute risk on
postoperative anterior knee pain of 14% (95% confidence interval, 6% to 21%).
Also, the risk of re-operation after resurfacing the patella is significantly
lower. Other reports have demonstrated that re-operation for only patellar
resurfacing after TKA leads to inferior results compared to initial patellar
resurfacing during primary TKA.
Resurfacing the patella, however, is not without problems. Complications
include patellar fracture, tendon rupture, osteonecrosis, overstuffing, and
soft tissue impingement. Unsatisfactory results may also be caused by patellar
tilt, maltracking, instability, polyethylene wear, and the patellar clunk
syndrome.
According to most authors, indications for patellar resurfacing during primary
TKA include: older age, anterior kneepain or other patellofemoral symptoms,
rheumatoid arthritis (RA), obesity, history of patellar subluxation or
dislocation, large and/or thick patellae, multi operated knee and major loss of
patellofemoral articular cartilage noted intraoperatively.
Current prospective reports fail to recognize any clinical outcome differences
among patients after TKA with or without a resurfaced patella. Most studies use
established clinical knee scoring systems, such as the Knee Society clinical
rating system (KSS) and the Hospital for Special Surgery score (HSS). These
scoring systems mainly focus on tibiofemoral aspects, whereas specific
patellofemoral symptoms can be missed or underscored.
Recently, Baldini et al. published a validated scoring system specifically
designed to evaluate the patellofemoral joint after total knee arthoplasty.
Furthermore, most studies have reported that when anterior knee pain develops,
it occurs within the first 18 months after performing TKA.
We hypothesize that patients with patellofemoral knee OA receiving TKA and
patellar resurfacing will have significantly better clinical results using the
Baldini scoring system compared to patients without patellar resurfacing after
24 months.

Primary outcome
The primary objective of the study is to evaluate if patients undergoing
resurfacing of the patella during TKA show at least 10 % improvement in the
Baldini score (after 24 months) compared to patients undergoing TKA without
resurfacing of the patella.
Hypothesis:
-Patella resurfacing in patients with symptomatic knee OA who are indicated
for total knee replacement and show clinically and radiologically signs of
patellofemoral OA will give an improvement of the Baldini score > 10% (after
TKA) compared to patients without resurfacing the patella

Secondary outcomes
The secondary outcomes of the study are to:
-Evaluate the Knee Injury and Osteoarthritis Outcome score (KOOS)
-Evaluate the correlation between the Knee Injury and Osteoarthritis Outcome
score (KOOS) and the patellofemoral scoring system by Baldini with regard to
patellofemoral symptoms
-Evaluate the correlation between the Knee Society clinical rating system (KSS)
and the patellofemoral scoring system by Baldini with regard to patellofemoral
symptoms

Single- blinded randomized controlled trial. Patients suitable for enrollment
in the study are patients who show clinically and radiologically signs of
patellofemoral OA and are candidates for total knee replacement. Patients will
undergo patellar resurfacing, denervation and osteophyte resection or
denervation and osteophyte resection of the patella during TKA. This will be
done so that the results are comparable: in case of patellar resurfacing one
resects the surrounding tissues of the patella in order to resect the patella.
One also resects possible osteophytes. The patients will be randomly assigned
to one of the two regiments in a 1:1 ratio. Investigators and patients will
remain blinded to the assigned regiment.

Surgery:
The surgeon will start surgery according to the designated treatment
allocation. He or she will start bij placing a total knee prosthesis. Then
denervation of the patella and osteophyte resection.
- In the group of patients who have been randomised to receive
patellarresurfacing the patella wil be resected and a hole will be drilled so
that a patellabutton can be cemented into place
-Both groups will undergo the same procedure with the same incision and
material so the only difference between the groups will be the
patellarresurfacing

Risks accompanying the placement of a total knee replacement are similar for
both treatment groups. Regarding the patellarresurfacing there is a risk of
complications such aforementioned patellafracture, patellatendonrupture, soft
tissue impingement, maltracking of the patella and patella-clunck syndrome.

Outpatient inspections take place after 6 weeks and then at 6, 12, 18 and 24
months after surgery. This means that these patients take three more outpatient
visits than patients not participating in the study and have received a total
knee prosthesis. Also completing the questionnaires which will take
approximately 15 minutes extra to complete.