Total knee arthroplasty (TKA) is one of the most popular surgical procedures today. It is
designed and proven to effectively reduce pain caused by end-stage osteoarthritis. Despite
its achievements, up to 25% of patients remain dissatisfied after the procedure due to
lingering pain, amongst other complaints. Post-operative swelling of the knee and leg is
thought to be a contributor to this persistent pain.
Traditionally, a standard gradient compression stocking is applied to the knee and leg after
surgery to reduce this pain and swelling. However, due to ineffectiveness or patient
non-compliance, compression stockings are often not entirely successful at preventing edema.
The recently developed NCPS is a lower extremity garment comprised of a technical fabric that
is thought to be able to prevent edema and reduce pain all in a comfortable, user-friendly
manner. The purpose of this study is to determine if the NCPS is effective at improving
post-operative pain, swelling, ROM and analgesic use associated with TKA.
Pain and prolonged recovery time associated with post-operative swelling are two factors that
contribute to patient dissatisfaction following TKA. Swelling of the knee following TKA is
caused by intraarticular bleeding and inflammation of the periarticular tissues, which can
lead to a decrease in functional performance including pain and delayed rehabilitation. In a
study by Noble et al, 1/3 of dissatisfied patients reported that their knees swelled at least
once per week, leading to pain and discomfort1. Decreased quadriceps strength following knee
surgery has been shown to prolong recovery1-8. Fahrer et al showed that knee effusions
inhibited reflex neurons and altered kinetics and muscle activity in quadriceps, which
ultimately causes decreased strength2. Holm et al later showed us that knee swelling played a
part in post-operative quadriceps strength following TKA3. Ultimately, if post-operative
swelling can effectively be reduced, patient recovery could be expedited and patient
satisfaction could be improved.
Compression stockings have been utilized to attempt to reduce post-operative swelling.
Compression works to prevent swelling by reducing the hydrostatic pressure in the leg.
Reducing hydrostatic pressure prevents the capillaries from oozing and allows blood to move
freely from the superficial to the deep venous system, subsequently allowing excess fluid to
flow away from the interstitial space9.
More recently, the use of gradient compression stocking following TKA has come into question
for its efficacy. While the application of external pressure from these gradient compression
stocking is beneficial for a period, they are often unable to exert a sufficient amount of
pressure long enough to prevent painful edema for an extended amount of time. A study by
Bowling et al showed that these garments showed sufficient compression during the first few
hours after surgery, but the pressure they applied dropped with time and required daily
measurements and refitting to maintain appropriate and therapeutic compression10. This poses
a problem not only medically, but financially as well. These compression stockings lose their
fit so quickly, new ones must be prescribed frequently, leading to costly bills for the
patient. It's clear that compression stockings are not as effective as once thought when it
comes to controlling pain and swelling post-operatively.
A potential solution to the problems posed by traditional compression stocking is the NCPG.
The garment is comprised of a semi-conductive material ground to nanoparticles that are
embedded into the fibers, formed into a three-dimensional woven fabric for optimized comfort.
Instead of relying on compression, NCPS utilizes the body's own thermal energy to generate
infrared energy. The infrared energy generated is reflected back at the body and modifies
cellular activity at the level of the mitochondria through a process known as
photobiomodulation14-15. This process of photobiomodulation is hypothesized to improve
swelling and tissue healing by increasing the activity of mitochondria and the availability
of cellular energy in the form of ATP.
This study seeks to determine if NCPS use of infrared energy is more successful at reducing
pain and swelling following TKA than traditional gradient compression dressing.
We will enroll 100 subjects throughout all sites involved in the study.
Patients will be recruited in the office setting after all non-operative modalities for
controlling pain associated with end-stage osteoarthritis of the knee have been exhausted.
Patients will then be presented with the option of total knee replacement. After patient has
agreed to undergo TKA, patients will then be asked (in a face-to-face setting) if they would
like to participate in the study.
Patients will be approached in the office setting after it has been determined that they have
failed conservative management of advanced knee arthritis. Patients will be in the surgeons'
clinic behind closed doors with the performing surgeon and potentially other members of the
research team. Consent will be obtained in the office after scheduling total knee
arthroplasty procedure. The consent process is expected to take 30 minutes, but more time is
available to ensure that patients have all their questions answered prior to signing the
consent form.
Patients will be enrolled in study prior to surgery, outlined above in the consent process.
On the day of surgery, patients will arrive and will be situated in the pre-operative holding
area. A trained member of the research team will meet the patient in the pre-operative
holding area and will measure the circumference of the patient's leg at the mid-thigh,
mid-knee and mid-calf. The patient's range of motion of the operative leg will be measured in
flexion and extension. All measurements will be recorded in redcap.
The patient will then go on to have their primary total knee arthroplasty by standard of care
procedure. Both cruciate retaining and posterior stabilized total knee replacement designs
will be included in the study. Following closure of the surgical site and placement of a
post-operative occlusive dressing, the operative leg will be measured once more for
circumference and range of motion, and the values will be entered into redcap. The patient
will then be placed in their randomized post-operative sleeve/device and will be transferred
to the PACU and will receive the standard post-operative treatment.
On post-operative day one, patient's will be seen and evaluated in their inpatient rooms.
Their leg measurements will be taken again with the knee sleeve/compressive gradient dressing
pulled down. Patient's skin will be inspected for any reactions to the sleeve and a standard
post-operative examination will be performed to ensure no neurovascular compromise, blood
clots, infections or other post-operative complications.
Patients will likely be discharged on post-operative day 1. Patients that have not been
discharged on post-operative day 1 will not be measured on post-operative day 2.
Patients will be provided with a journal that they will use every daily to track their pain
based on a visual analog scale and their narcotic consumption (number of Percocet or tramadol
pills). Patients will also use their journal to log the number of hours they wore their
sleeve each day. Patients will continue to log the number of pain medications taken and hours
wearing the sleeve for 6 weeks. Sleeves will be worn morning and night removing them only for hygiene and washing of sleeve
for 2 weeks. After 2 weeks, the patient's will wear the sleeve as much as they can tolerate
day and night. At 6 weeks, sleeves will be discontinued all together. Final ROM and
Circumference Measurements will be obtained at 12 weeks post-operative mark.
Patients will be asked to fill out the Knee Society Score questionnaire at the time of
consent and at each post-operative visit.
The Reparel leg sleeve is the experimental device being investigated in this study. It is
intended to improve swelling in the post-operative knee.
Allscripts Electronic Medical Records will be used to collect data about patients during
their inpatient, post-operative stay. UH Care ambulatory EMR and Medent EMR will be used in
the outpatient setting to collect data and track post-operative clinic visits.
The enrollment period will be 1 year from the time of the first patient enrolled in the
study. The enrollment period may be expanded to allow for the investigators to reach their
goal of 100 patients. The total amount of time each patient will be involved in the study
will be 12 weeks. Patients will only be required to wear the post-operative sleeve/dressing
for 6 weeks post-operatively. Patients will continue to record their narcotic consumption and
pain scores for 12 weeks post-operatively. Date to be collected:
Mid-thigh, mid-knee, and mid-calf measurements ROM measurements in knee flexion and knee
extension Visual analog Pain scale Knee society score (KSS) Narcotic consumption Name Medical
record number Surgeon weight. Data Analysis Plan:
Demographics will be reported using descriptives such as count data and percentages.
Differences between groups at baseline (pre-op) will be reported using two-tailed independent
t-tests for continuous variables, and chi-square or Fisher's Exact tests for categorical
data, as appropriate.
The primary outcomes of range of motion, leg circumference, and pain ratings will be compared
post-op between conditions using two-tailed independent t-tests. Should clinically relevant
demographics differ significantly between conditions pre-op (baseline), post-op comparisons
will instead be conducted using one-way ANCOVAs controlling for differences at pre-op
(baseline). These comparisons will additionally be made at multiple additional time-points
throughout a 12-week post-op time period.
A priori power analyses were calculated for two-tailed independent t-tests for each primary
outcome, using an alpha of .05, power = .80. Each of these are reported and the average of
these numbers is used to calculate the final sample size. Clinically significant reductions
in pain are defined as a 2-point change with a standard deviation of 2.5 using a 10-point
scale; 84 patients were estimated. Clinically significant changes in range of motion are
defined as: 10 degrees of difference from a 0-140 degree estimated range of values.
Clinically significant changes in leg circumference are defined as: 1 cm difference in leg
circumference using a 15-30 estimated range of values. To identify medium effect sizes of
.55, 106 patients were estimated. Averaging these values, 99 patients were estimated. To
ensure equal numbers of patients in each condition, 100 patients will be recruited for this
study.
The data will be monitored every 10 patients to assess for completeness, accuracy and
adherence to the protocol. We will also be monitoring for any obvious safety concerns that
may arise.
There will not be a designated safety team assigned.
