Page 86 - Journal of Special Operations Medicine - Summer 2014

The informed consent document explained that pa- line on which the patients were to mark their cur-
tients would be randomly assigned to receive an intra- rent pain at each time interval while in the ED up to
articular knee injection of either morphine, lidocaine, the 2-hour point. At the 2-hour point, the patients
or a combination of morphine and lidocaine to treat were discharged with a written pain survey to take
their acute pain. They were notified that they would be home and mail back to the investigators in a provided
asked to rate their pain at various time intervals and stamped, preaddressed envelope. The home pain sur-
mail back a pain survey after discharge from the ED. vey asked patients to report their current pain at 6
Furthermore, patients were warned of risks involving hours after injection on a 100mm VAS and again at
local discomfort, infection, reactive synovitis, iatrogenic 24 hours on a new 100mm VAS. At 24 hours, the
injury, damage to cells composing the cartilage, and al- patients also answered questions on the home pain
lergic reactions. Patients were then advised to not drive survey as to the estimated amount of time they ap-
or operate dangerous machinery or perform dangerous plied ice to the knee, how many ice applications were
activities within 8 hours of the treatment. Finally, they made, and the amount of oxycodone 5mg/ acetamin-
were assured that if they did not want to participate, ophen 325mg and ibuprofen 800mg they consumed
there were other treatment modalities available such as in the previous 24 hours. The home pain survey also
oral analgesia and ice. solicited any patient-perceived negative side effects of
the medication.
After consent, patients were randomized to one of the
following three treatment arms (Figure 1): The VAS is a validated method of assessing clinically
important changes in pain severity. Measurements of
10
1. Morphine only: 5mL of morphine (5mg) and 5mL of where the patient placed a mark for their pain on the
saline (10mL total solution) VAS were made in millimeters and measured by a third
2. Lidocaine only: 5mL of 2% lidocaine (100mg) and party emergency physician not otherwise affiliated with
5mL of saline (10mL total solution) the study. For ice application, patients were instructed
3. Lidocaine and morphine: 5mL of morphine (5mg) to use an over-the-counter ice pack or home-made ice
and 5mL of 2% lidocaine (100mg) (10mL total pack using a quart-sized bag.
solution)
Results
Figure 1 Participant Selection and Flow.
The original design was to have 45 patients in each of
the 3 arms. Once 30 patients were in each arm, an in-
terim power analysis was planned to adjust the target
patient sample size as appropriate. However, due to
the nature of convenience enrollment in this unfunded
study, the number of patients enrolled was eight.

Due to low patient enrollment numbers and a lack of
statistical power, analyses consisted of averaging VAS
pain measurements, oral analgesia usage, and ice usage.
The raw data (Table 2) showed a possible positive trend
toward a greater reduction in pain on the VAS for injec-
tions containing morphine versus lidocaine-only injec-
tions (Figure 3). The average reduction in patient-rated
pain by millimeters on VAS at each time interval for the
The study medication was then injected into the knee lidocaine group was 30 minutes, 22mm; 60 minutes,
by an emergency medicine resident or staff emergency 34mm; 90 minutes, 34.5mm; 2 hours, 25mm; 6 hours,
physician, both familiar with acute knee injuries. The 21mm; and 24 hours, 20mm. The average reduction in
injecting provider was provided a handout on aspiration patient-rated pain by millimeters on VAS at each time
and injection techniques and instructed to conform to interval for the lidocaine and morphine group was 30
the handout (Figure 2). minutes, 33mm; 60 minutes, 44mm; 90 minutes, 45mm;
2 hours, 46mm; 6 hours, 29mm; and 24 hours, 27mm.
The patients self-reported their level of knee pain via The average reduction in patient-rated pain by milli-
a standard 100mm VAS just before the injection and meters on VAS at each time interval for the morphine
30 minutes, 60 minutes, 90 minutes, 2 hours, 6 hours, group was 30 minutes, 35mm; 60 minutes, 40mm; 90
and 24 hours postinjection. The initial VAS data were minutes, 44mm; 2 hours, 48mm; 6 hours, 46mm; and
collected on a written pain survey with a new VAS 24 hours, 60mm.

76 Journal of Special Operations Medicine Volume 14, Edition 2/Summer 2014