Tenenbaum S, Dreiangel N, Segal A, Herman A, Israeli A, Chechik A.  The percutaneous surgical approach for repairing acute Achilles tendon ruptures: a comprehensive outcome assessment.  J Am Podiatr Med Assoc.  2010 Jul-Aug; 100(4): 270-5.  (PubMed ID: 20660878)

WHY did the authors undertake this study?
The foot and ankle surgeon is faced with several decisions when presented with a patient with an acute Achilles tendon rupture.  These primarily involve cast immobilization versus surgical repair, and open versus percutaneous surgical repair.    The authors of this study aimed to evaluate patient outcomes following percutaneous repair of acute Achilles tendon ruptures. 

HOW did they attempt to answer this question?
The primary outcome measures of the study  were a variety of measures of function:  subjective activity level, post-operative AOFAS scales, post-operative modified Boyden scores, post-operative VAS scores, ankle passive range of motion, and isokinetic muscle evaluation. 

Inclusion criteria of the population cohort were patients retrospectively identified with percutaneous repair of an acute Achilles tendon rupture that followed-up for at least 1 year.  Exclusion criteria were patients with open rupture, systemic illness (including diabetes), previous Achilles rupture, pathologic abnormality of the contralateral extremity, and corticosteroid use. 

A total of 29 patients met inclusion criteria over a data collection period of 8 years.

WHAT were the specific results?
No statistically significant differences were found  as this was purely a descriptive study of post-operative outcomes.  They report that about 90% of patients returned to pre-injury activity levels at a mean of 5.5 months.  Average post-operative VAS (<2), modified Boyden score (74.3) and AOFAS scale (94.5) means were reported.  Ankle range of motion and isokinetic strength were approximately equal to the contralateral extremity.   

HOW did the authors interpret these results?
From these results, the authors concluded  that percutaneous repair of acute Achilles tendon ruptures lead to good functional results with low complication rates

Brattwall M, Turan I, Jakobsson J.  Pain management after elective hallux valgus surgery: a prospective randomized double-blind study comparing Etoricoxib and Tramadol.  Anesth Analg.  2010 Aug; 111(2): 544-549. (Pubmed ID#: 20584877)

WHY did the authors undertake this study?
There is no single post-operative pain management algorithm following elective forefoot orthopedic surgery, and most clinicians utilize a combination of anti-inflammatories, narcotics and non-pharmacologic treatments.  The aim of this study was to compare the efficacy of two different analgesic medications for post-operative pain management following HAV surgery. 

HOW did they attempt to answer this question?
A total of 100 patients undergoing elective HAV surgery were prospectively randomized  to receive one of two different post-operative pain management strategies:  (1)  etoricoxib 120 mg PO qday for 4 days, and then 90mg PO qday for 3 days, or (2) tramadol sustained release 100mg bid for 7 days. 

Several pain management related outcome measures were analyzed during the first 7 post-operative days including pain (VAS and Brief Pain Inventory Scale), patient satisfaction (Health Profile Quality of Life) and need for rescue medication.  In addition, a CT scan was performed in all patients at 12 weeks given potential concerns for delayed bone healing. 

WHAT were the specific results?
The etoricoxib group demonstrated significantly lower VAS scores compared to the tramadol group over the 7 days, and reported significantly less side effects.  They also reported higher satisfaction levels with respect to their pain management.  There was no difference noted in the need for rescue analgesics, as well as no significant findings with respect to the CT scans. 

HOW did the authors interpret these results?
Based on these results, the authors concluded that etoricoxib represents an effective primary means of achieving post-operative pain management in patients undergoing elective HAV surgery. 

Let’s take a closer look at the topic of levels of clinical evidence and how it applies to each of our articles.  Both The Journal of Foot and Ankle Surgery [https://www.elsevier.com/wps/find/journaldescription.cws_home/662210/authorinstructions] and The Journal of Bone and Joint Surgery [https://www2.ejbjs.org/misc/instrux.dtl#levels] utilize the same “levels of clinical evidence” scheme, and reprint identical tables in their “author information” sections (found at the links provided above).  The concept of “levels of clinical evidence”, and the tables, are not unique to these two journals, but are instead  adapted from the Centre for Evidence-Based Medicine in Oxford, England (and information can be found at their website:  www.cebm.net). 

Put most simply, there are five “levels” of evidence, and the evidence is “stronger” from an evidence-based, critical analysis standpoint as you move up the table.  In other words, Level I evidence is relatively the “strongest”, while Level V evidence is relatively the “weakest”.  The foot and ankle surgical literature generally deals with the second column of the table, or “therapeutic studies”.   The Tenebaum et al Achilles study certainly fits this bill.  The authors are investigating the results of percutaneous surgical intervention of the Achilles tendon.  The Brattwall et al HAV study also falls into this category, as the authors are investigating the results of different pain management interventions following a surgical procedure.  Let’s utilize the Tenebaum et al study to examine differences in study design based on these levels of clinical evidence.

Level V represents “expert opinion”.  The Tenebaum et al study would have fallen into this level if it had examined no patients, but instead reviewed the concepts and history of percutaneous Achilles tendon repair. The authors could have also explained general reasons why they felt percutaneous repair was superior or inferior, but not directly provided any new evidence why this was the case. 

Level IV represents a “case series”, and this is exactly what our actual Tenebaum et al authors performed.  There was no comparison of different techniques or different groups of patients, simply a description of outcomes from one cohort of patients treated the same way.  All the patients in this study were treated with the same surgical procedure, and had the same post-operative course. 

Level III most often involves a “case-controlled study” or a “retrospective comparative study”.  The Tenebaum et al authors would have performed a “case-controlled study” had they, for example, compared two groups of patients that had percutaneous Achilles tendon repairs.  One group could have been patients who re-ruptured, while the other group could have been patients who maintained an intact tendon for a given period of time.  This comparison of two different groups that had the same initial diagnosis and intervention would have provided Level III evidence.

The Tenebaum et al authors would have performed a Level III “retrospective comparative study” if they had retrospectively compared, for example, two groups of patients with Achilles tendon rupture where group 1 was repaired with open technique and group 2 was repaired with percutaneous technique.  This comparison of two different groups that had the same diagnosis, but two different treatments, would have provided Level III evidence.

Level II evidence is similar to our last example, but the data is collected prospectively instead of retrospectively.  So if the we had the same two groups of patients ( [1] Achilles repair with open technique and [2] Achilles repair with percutaneous technique), and data was collected prospectively instead of retrospectively.  Level II evidence can also be achieved with “lesser-quality randomized controlled trials (e.g. <80% follow-up, no blinding, improper randomization, etc).”

And Level I evidence involves “high-quality randomized controlled trials”.  The Tenebaum et al authors would have performed this if they had, for example, randomized patients presenting with acute Achilles tendon rupture into two blinded groups (open repair versus percutaneous repair), and then had all follow-up performed by physicians who were blinded as to which type of surgery was performed. 

Hopefully this introduces you to the “levels of clinical evidence”, and allows you as a critical reader to appreciate how study design can influence the level of evidence.