Back in August, we saw how a rehab program consisting of eccentric heel drops with a bent and straight knee reversed damage to the Achilles tendon by inducing collagen remodeling. One thing I didn't make clear enough is that Alfredson's eccentric heel drop protocol, developed in 1998, was designed for midpoint Achilles tendonitis. In most cases of Achilles injury, the tendon is damaged between 2 and 6 cm from the insertion point at the calcaneus (heel) bone. But in a minority of cases, the tendon is damaged at the insertion point—right at the heel bone. While it might seem like a trivial difference, these are actually parsed into two separate injuries. While both are the result of damage to the collagen fibers, the surrounding tissue at the insertion of the Achilles tendon is very different from the tissue near the midpoint of the Achilles.
Treatment with eccentric exercise
Understandably, people first assumed that the eccentric heel drop protocol devised for the midpoint Achilles tendonitis would work just as well on insertional Achilles tendonitis; however, once researchers got around to investigating this, they found that, in contrast to the >80% return-to-activity rate seen in multiple studies for subjects with midpoint Achilles tendonitis, subjects with insertional Achilles tendonitis had a paltry 32% return-to-activity rate. This problematic result probably stumped researchers for some time—the original study linking eccentric heel drops to good recovery prospects in midpoint Achilles tendonitis was published in 1998, but productive results for insertional Achilles tendonitis did not make it into the literature until 2008. In the interim period, Alfredson and his coworkers discovered how very minute differences in exercise protocol can make a world of difference in injury rehab. As we covered last week, a 2004 pilot study showed that eccentric decline squats are a highly effective rehab exercise for patients with patellar tendonitis. The results, confirmed by a more thorough clinical trial a year later, showed that just a small change in protocol—doing an eccentric squat on a decline instead of on flat ground—had a significant effect on the patients' outcome.
These finding suggest that eccentric exercises to repair tendons should be highly targeted to put a large, controlled stress on the tendon which cannot be mitigated by other muscle groups. One key difference that Alfredson et al. highlighted was that, in a regular eccentric squat, various other muscle groups could help stabilize the knee and take some load off the patellar tendon. In a decline squat, these muscles are inhibited, forcing the quadriceps (via the pateller tendon) to do the lion's share of the work. So, in the case of insertional Achilles tendonitis, might it be possible to alter the exercise to specifically target the insertion point of the tendon instead of the midpoint?
Modifying the eccentric heel drop
|Image from sportsinjuryclinic.net|
|From Jonsson et al.|
Results and limitations
The results from the 2008 paper, which was a small pilot study with 27 patients (34 injured tendons), were promising. After the 12 week program, 67% were able to return to their pre-injury activity levels. Their VAS scores (visual analogue scale, 0-100 scale of tendon pain) decreased significantly. Unfortunately, there were some major flaws and shortcomings in the study's design. Perhaps because this was a pilot study, there was no control group—a rather egregious scientific error, especially considering that Alfredson's research group has been fairly good about adhering to good scientific practices in the past. Without a control group doing some sort of other rehab protocol, it's impossible to compare whether the flat eccentric heel drop program is any better than another recovery plan. Comparing results of one study to another is crude and evokes apple-to-orange comparisons. But because this is only a small pilot study, perhaps we can forgive this sin.
However, in a baffling move, Jonsson et al. parse the study subjects into two groups: those who said they were "satisfied" with their outcome and those who said they were "not satisfied." They then attempted to show statistically significant differences between the groups. This move is puzzling, as it is more an investigation of injury psychology than anything else. This might have been interesting if they could have shown that the dissatified subjects were more likely to have Haglund's deformity on the back of their heel or were older in age, for example, but they found no such associations. In fact, the only difference between satisfied and dissatisfied subjects was their follow-up VAS score. Patients who were satisfied with their outcome experienced (surprise!) less tendon pain than those who were not. Finally, there were some shortcomings that limit this study's applicability to runners. First, the subjects were recreational walkers, joggers, and casual athletes. Second, most were over fifty years old. Like the studies on patellar tendonitis, which usually used volleyball or basketball players due to the higher incidence of that particular injury in those sports, Jonsson's study consists mostly of subjects from the demographic which makes up most insertional Achilles tendonitis cases—moderately active middle-aged men and women. The use of such casual subjects might hint that compliance with the assigned protocol was not spectacular. One reason doctors and physical therapists usually love working with serious athletes is that they are much more likely to actually do the exercises they are prescribed, and hence achieve a better outcome.
Conclusion: the flat eccentric heel drop
Given these shortcomings, it's obvious that a larger, better-designed study should be done, I can only hope that Alfredson's research group is currently conducting one. Despite the flaws, modifying the eccentric heel drop program in this way for insertional Achilles tendonitis is still probably a good idea. Though I usually don't believe in jumping on the bandwagon for a new therapy or treatment after just one paper, in this case, the theoretical underpinnings are fairly sound, and the proposed change is not a radical departure from the well-established eccentric heel drop program for midpoint Achilles tendonitis. Further, it's fairly clear that a) small changes in the way an exercise is done can have a big impact on recovery and b) the traditional eccentric heel drop off a step is not particularly effective for insertional Achilles tendonitis.
In short, the modified protocol is as follows:
- 3 sets of 15 straight-legged eccentric heel drops on flat ground, twice a day for twelve weeks
- Starting with the heels raised and your weight on the injured leg, use the calf muscles to slowly lower your heel to the ground, keeping your knee straight.
- Use your good leg to return to the starting position.
- Exercise into mild or moderate pain, but stop if pain becomes excruciating
- Once you can complete all three sets without pain, add weight using a backpack.
- Once you have recovered, it is not a bad idea to keep doing these exercises for maintenance/prevention.
So, what would you like to hear about in the future? Training? Racing? Speed? Injuries? I'd love to know.