n Case Report
Loosening of the Patellar Component
and Extra-articular and Transcutaneous
Migration After TKA
Camilo Partezani Helito, MD; Riccardo Gomes Gobbi, MD; Luis Eduardo Passarelli Tirico, MD;
Jose Ricardo Pecora, MD, PhD; Gilberto Luis Camanho, MD, PhD
abstract
Full article available online at Healio.com/Orthopedics. Search: 20140124-28
Replacement of the patella during total knee arthroplasty (TKA) remains controversial.
Despite some attempts to establish guidelines for this procedure, there is still no consensus in the literature. When the patella is replaced, the patient is subjected to certain
complications, including loosening of the component. The loosened patellar component most commonly migrates to the intra-articular region of the knee. However, there
have been a few reports of migration of the component to the extra-articular region,
particularly when release of the lateral retinaculum and osteonecrosis of the patella
are involved. The authors report a case of patellar component loosening and extraarticular and transcutaneous migration of the component 9 years after TKA. This report
is unique because, during the primary procedure, no lateral release was performed
and no patellar necrosis was evident on radiographs. The component was removed in
the operating room and the wound cleaned and closed. Because of the probable slow
migration of the component, there was no communication between the external environment and the joint at the time of surgery. There were no further complications after
the wound healed. This case emphasizes the need for periodic radiographic follow-up
after TKA.
Figure: Photograph showing the frontal view of the
transcutaneous extrusion of the patellar component of total arthroplasty of the left knee.
The authors are from the Institute of Orthopedics and Traumatology, Hospital das Clinicas, University of São Paulo, São Paulo, Brazil.
The authors have no relevant financial relationships to disclose.
Correspondence should be addressed to: Camilo Partezani Helito, MD, Institute of Orthopedics and
Traumatology, Hospital das Clinicas, University of São Paulo, Rua Dr Ovídio Pires de Campos, 333,
Cerqueira Cesar, CEP: 05403-010, São Paulo, Brazil ([email protected]).
Received: April 23, 2013; Accepted: September 5, 2013; Posted: February 7, 2014.
doi: 10.3928/01477447-20140124-28
FEBRUARY 2014 | Volume 37 • Number 2
e211
n Case Report
R
eplacement of the patella during
total knee arthroplasty (TKA)
remains controversial. Despite
some attempts to establish guidelines for
this procedure, there is still no consensus
in the literature.1,2 When the patella is
replaced, the patient is subjected to certain complications,3,4 including loosening
of the component.5 The loosened patellar component most commonly migrates
to the intra-articular region of the knee.6
However, there have been a few reports of
migration of the component to the extraarticular region,7,8 particularly when release of the lateral retinaculum and osteonecrosis of the patella are involved.9
The authors report a case of patellar
component loosening and extra-articular
and transcutaneous migration of the component 9 years after TKA. This report is
unique because, during the primary procedure, no lateral release was performed
and no patellar necrosis was evident on
radiographs.
A
Figure 1: Photographs showing the frontal (A) and medial (B) views of the transcutaneous extrusion of
the patellar component of total arthroplasty of the left knee.
Case Report
An 83-year-old man who had undergone cemented TKA (Duracon; Stryker
Orthopaedics, Mahwah, New Jersey) 9
years earlier presented at a routine annual
outpatient consultation with transcutaneous extrusion of the patellar component of
the prosthesis (Figure 1). He reported no
pain or signs of local infection. The integrity of the knee extensor mechanism was
preserved, with active and passive range
of motion from 0 to 110. He reported
that the component had started to extrude through a small orifice in the skin 3
months earlier. At presentation, half of the
component was extruding through an approximately 4-cm long cutaneous fistula.
The patient reported that this process was
not preceded by a significant joint complaint such as locking or crackling.
Hemogram data were gathered and
tests on inflammation performed, revealing values within the normal range. Radiographs performed on hospital admission
showed that the tibial and femoral com-
e212
A
B
Figure 2: Anteroposterior (A) and lateral (B) radiographs of the left knee showing loosening and transcutaneous migration of the patellar component of total knee arthroplasty.
ponents of the TKA did not have signs of
loosening (Figure 2), the remaining part
of the patella bone had no signs of fracturing or osteonecrosis, and the patellar component was half inside and half outside the
anterior soft tissues of the knee.
The patient was taken to the operating
room for removal of the patellar component and surgical exploration of the cutaneous wound. Intraoperatively, it was
observed that the patellar component was
lodged in the subcutaneous region medially to the patella, without communication with the joint region. Local cleaning
was done and the skin closed without
performing arthrotomy. There were no
complications during this procedure. The
patient received broad-spectrum antibiotic
therapy intravenously. Once the final results, which were negative, from cultures
ORTHOPEDICS | Healio.com/Orthopedics
n Case Report
of samples collected during surgery were
received, this was stopped.
Two weeks postoperatively, the wound
had healed well and the stitches across
the incision were removed. The patient
maintained the initial knee range of motion, with a complete extensor mechanism and no reports of pain. Evaluations
performed 1, 3, and 6 months postoperatively found that the patient was asymptomatic with preserved function.
Discussion
The current case involved extra-articular migration of the patellar component
a long time after TKA. There had been no
lateral release and the patella was complete on radiographs. Thus, the likely etiology was aseptic loosening of the component.
Even after the component had loosened, the patient reported none of the
complaints that are common in this situation, such as pain or restriction of knee
movements.6 The event was only noticed
when transcutaneous extrusion of the
component occurred. The patient only
FEBRUARY 2014 | Volume 37 • Number 2
presented because it was time for his annual routine post-arthroplasty consultation. He had not attended these consultations during the preceding 4 years because
he had been asymptomatic.
In this case, because of the probable
slow migration of the component, there
was no communication between the external environment and the joint when surgery was performed to remove the component. Therefore, there was no infection of
the arthroplasty. The patellar component
alone was removed and the femoral and
tibial components were left in place because they showed no signs of loosening.
The current case is unique because the
transcutaneous migration evolved asymptomatically and occurred with a complete
patella, without signs of osteonecrosis.
This emphasizes the need for periodic radiographic follow-up after TKA.
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