Whiteley B, Rees S.  A Randomized Controlled Trial to Compare Two Techniques for Partial Digital Local Anesthetic Blocks.  J Foot Ankle Surg.  2010 Mar-Apr; 49(2): 143-6.   (PubMed ID: 20188280)

WHY did the authors undertake this study?
Injections hurt, but most podiatric physicians are charged with the performance of these diagnostic and therapeutic interventions on a near daily basis.  Some would even argue that we should be experts in performing peripheral local anesthetic blockade.  As such, it is our duty and responsibility as physicians to minimize the overt noxious, and more subtle psychological components, of these procedures if possible. The aim of this study was to compare a 2-stage injection test method with a more traditional 1-stage injection technique when considering hallux infiltration.

HOW did they attempt to answer this question?
The primary outcome measure of the study was maximum pain intensity as measured on a 100mm visual analog scale (VAS).  Secondary outcome measures included pain duration (measured in seconds), effect of starting on either the medial or lateral side of the hallux, and gender. 

The 2-stage injection test technique consisted of a quick stick (approximately 5 seconds) where the needle was advanced from dorsal to plantar and then withdrawn as a small quantity of anesthetic was released (approximately 0.2ml).  Following a 2-minute interval, the remainder of the anesthetic (approximately 0.8ml) was slowly administered in a dorsal to plantar direction over a period of 60 seconds.  All patients received the 1-stage injection on one side of the digit, and the 2-stage technique on the other side in a randomized order.

WHAT were the specific results?
Statistically significant differences were found with respect to the pain intensity level (P<0.001; a difference of 39 VAS points [mms]) and pain duration (P<0.001; a difference of 18 seconds) between the two methods with a predilection for the 2-staged technique.  Moreover, nearly 94% of patients self-reported preferring the 2-stage technique.

Neither pain intensity nor duration was found to be associated with the gender of the patient or the medial/lateral injection sites.

HOW did the authors interpret these results?
From these results, the authors concluded that the described 2-stage technique may be of benefit to practitioners looking to decrease the level and duration of pain associated with digital peripheral nerve blockade.

Mickle KJ, Munro BJ, Lord SR, Menz HB, Steele JR.  ISB Clinical Biomechanics Award 2009:  Toe weakness and deformity increase the risk of falls in older people.  Clin Biomech (Bristol, Avon).  2009 Dec; 24(10): 787-91. (PubMed ID#: 19751956)

WHY did the authors undertake this study?
Older individuals are known to have an increased prevalence of first ray and lesser digital deformities, in addition to balance and functional abnormalities putting these patients at an increased risk for falls.  The primary aim of this study was to determine if patients with digital deformities and toe flexor strength abnormalities were at an increased risk of falls.

HOW did they attempt to answer this question?
The primary outcome measures in this study included the presence of hallux valgus deformity, the presence of lesser digital deformity, hallux and lesser toe flexor strength (as measured with a validated force plate analysis), and the incidence of a fall over a 12 month prospective period.  312 volunteers aged over 60 years were recruited for inclusion in the study cohort.

WHAT were the specific results?
More than 1 in 3 individuals (35%) fell during the 12 month prospective period.  Fallers were more likely to have hallux valgus (P<0.01), more likely to have lesser digital deformity (P<0.01), and were more likely to have less flexion strength of the hallux (P<0.01) and lesser toes (P<0.01).

HOW did the authors interpret these results
From these results the authors concluded that patients with structural forefoot deformities were at an increased risk of falls.  Prophylactic intervention in the form of flexor strengthening exercises may be of benefit when considering the presence of this significant occurrence. 

Let’s take a closer look at the topic of the difference between a statistically significant difference and a clinically significant difference.  The Whitely and Rees local anesthetic blockade article provides a good opportunity for doing so.  In this article they found a statistically significant difference in pain intensity between their two groups.  The standard 1-stage injection technique had a median pain intensity of 56 [interquartile range of 35,69] while the 2-stage test injection technique had a median intensity of 17 [interquartile range 7,26].  Put in plain terms using the 10-point scale that we are all familiar with, the 1-stage group rated their pain at about “6/10” and the 2-stage group rated their pain at about “2/10”.  They found a statistically significant difference between these two groups of numbers (with a P-value <0.001), but would this make a clinical difference in your patients? 

I think that most of us would agree that yes, it would.  In this case there was a big jump between these two numbers from a “moderate” pain score (usually defined as 5-6) to a “mild” pain score (usually defined as 1-4).  I would rather have a patient in a mild amount of pain than in a moderate amount of pain.  So in this situation, most people would agree, that we have both a statistical and clinical difference between the two groups in terms of pain intensity.  The authors of the paper provide us with information about the statistical difference (through the specific statistical test and P-value), but it is up to us readers to take it a step further to determine if it is clinically significant for our practices.

I also want to take a quick minute and talk about the outcome measures we use to assess pain.  In case you haven’t figured it out yet, I spend a lot of time and energy thinking about pain in our patients.  Certainly the visual analog scale is an easy and validated measure of pain (in addition to being pushed by JCAHO for in-patients), but how much is it really telling us about what the patient is experiencing?  Pain is a biologic and psychologic experience that cannot be completely measured by a simple, instantaneous 10-point scale.  It is influenced by previous history, culture, religious beliefs, mood and even the time of day or number of people in the room.  The measurement of pain should include measures of function, disability, emotion, duration/timing, etc.  There are measurements tools available such as the pain assessment and documentation tool (PADT), McGill pain questionnaire, and the brief pain inventory that may provide us with a more complete sense of our real effect on patients through our interventions.