FDG-PET Imaging in Painful Joint Prosthesis

The purposes of this study are: 1. To determine the normal pattern of FDG uptake demonstrated
by pet up to two years following total joint replacement surgery 2. To establish the optimal
diagnostic criteria for differentiating septic from aseptic painful joint prosthesis by
FDG-PET imaging and determine its accuracy 3. To compare the accuracy of FDG-PET imaging to
conventional techniques for the differentiation of septic from aseptic painful joint
prostheses.

We intend to enroll 100 patients per year for 5 years. These patients will be selected from
more than 300 cases that undergo joint revisions at the collaborating institutions. After
each patient undergoes an appropriate evaluation including history, physical examination,
radiographic and laboratory evaluation, he/she will be assigned into one of the groups listed
below based on the degree of suspicion of an infectious process. Every effort will be made to
have approximately one-third of the patients recruited from each of the following groups.

Study Plan Study I: FDG-PET imaging in the painful partial or total joint prosthesis We
intend to enroll 100 patients per year for 5 years. These patients will be selected from more
than 300 cases that undergo joint revisions at the collaborating institutions. After each
patient undergoes an appropriate evaluation including history, physical examination,
radiographic and laboratory evaluation, he/she will be assigned into one of the groups listed
below based on the degree of suspicion of an infectious process. Every effort will be made to
have approximately one-third of the patients recruited from each of the following groups.

Group 1: Low pre-scan suspicion of infection. The incidence of infection based on past
experience is <10% in this population.

Group 2: High pre-scan suspicion of infection. The incidence of infection in this group is
quite high based on past experience.

Group 3: Intermediate pre-scan suspicion of infection. Criteria: Any patient who does not fit
into either group 1 or 2 will be considered for this category. The incidence of infection in
this group based on past experience is intermediate.

Considering the large number of patients who undergo joint revision (more than 300 annually)
in the participating institutions combined, we expect no difficulties in recruiting adequate
numbers in all 3 categories.

Each patient will undergo only one preoperative diagnostic FDG-PET scan. After the PET scan
is completed, a diagnosis and detailed description of the observations made will be
communicated to the attending surgeon before the operation. We believe this information will
enable investigators to establish the correct diagnosis during surgical intervention.

Study II: FDG-PET imaging following uncomplicated partial or total joint arthroplasty To
accomplish this goal, we will enroll 10 patients per year for the first 3 years. FDG-PET
scans will be performed at approximately 12 months, 18 months and/or 2 years following
surgery. All scans will occur within 2 months of the 12-, 18-, and/or 24-month anniversary of
that patient's most recent joint replacement surgery. It is unknown how long FDG uptake
persists in an uncomplicated partial or total joint arthroplasty. The expected pattern of FDG
uptake following arthroplasty will provide a basis for the correct diagnosis of
periprosthetic infection and loosening during the life of the implant.

Inclusion Criteria:

- Patients selected for entry into this study will be men or women of any ethnic
background who are scheduled to undergo clinical and diagnostic evaluation by a member
of the Department of Orthopedic Surgery at the Hospital of the University of
Pennsylvania Health System or by the collaborating physicians at the Rothman Institute
or the VA Philadelphia Medical Center.

Study I: FDG-PET imaging in painful partial or total joint prostheses Each patient who is a
candidate will be evaluated by one of the collaborators mentioned above for a painful
partial or total joint prosthesis. The patient will undergo an appropriate routine
evaluation including history, physical examination, radiographic, scintigraphic, and
necessary laboratory evaluation. An initial diagnosis must be made for each patient. The
diagnosis of loosening will be established based on clinical examination and/or
radiographic evaluation demonstrating clear evidence of this complication. Other etiologies
for the joint pain, except for infection and aseptic loosening, need to be excluded.
Surgical intervention (prosthesis revision) may or may not be planned for the patient who
is a candidate for this study.

Study II: FDG-PET imaging following uncomplicated partial or total joint arthroplasty All
patients fulfilling the criteria below will be considered potential candidates for this
study. Each patient must have a diagnosis of degenerative joint disease caused by
osteoarthritis (no previous hip surgery) and have undergone primary partial or total joint
arthroplasty by a member of the Department of Orthopedic Surgery at the Hospital of the
University of Pennsylvania or referring hospitals. Other causes of degenerative joint
disease will be excluded by physical, radiographic and laboratory evaluation as clinically
indicated. Osteoarthritis is the most common cause of degenerative joint disease, and in
order to avoid any confounding factors in experimental results that may be caused by other
types of disorders, only this group of patients will be studied. A patient will be
eliminated from this group at anytime if the post-operative course is complicated by any
process that is thought to influence the outcome. Variations from an uncomplicated
postoperative course will be determined by the operating surgeon and include clinical signs
or other evidence to suggest infection, early loosening, or any other process directly
involving the prosthesis.

Exclusion Criteria:

- Patients with other etiologies for pain, other than for infection and aseptic
loosening, will be excluded from enrollment into the study.