Posts tagged achilles tendinitis
How Heavy Should I Load My Achilles Tendon After An Overuse Injury?
achilles-tendon-exercise-treatment

In the achilles tendinopathy (artist formally known as tendonitis) research two main themes have emerged. First, there is little to no evidence to support the use of injections of any kind into an injured tendon. Authors have advocated against steroid injections due to the risk of tendon rupture outweighing any potential benefits. Studies have also been limited in the use of PRP (platelet rich plasma) injections for tendon pain. Significant methodological concerns have impacted this area of research including the lack of large human trials, lack of placebo or alternative treatment (exercise) comparison, and small sample sizes. Without improvements in this line of research, PRP remains an expensive, experimental treatment compared to other proven treatment strategies.

Strengthening exercises remain the gold standard of care, both in the research and our Boulder Physical Therapy practice, for these tendon injuries. Although eccentric exercise was first published in the late 1990s as an effective treatment for tendinopathy, many other forms of strength training including isometric and isotonic exercise have also been shown to be effective. The key take home message from these trials remains the same, injured tendons must be progressively loaded based on their clinical presentation to recover. Initially improvements in a patient’s symptoms and function are secondary to improved strength of the surrounding muscles while long term improvements are attributed to structural healing of the tendon (remodeling).

A recent review of the evidence highlights the importance of intensity or resistance during achilles strength training exercises for patients with mid portion achilles tendinopathy (Murphy et al. Br J Sp Med. 2019). Authors reviewed the available literature on the use of heavy eccentric training for this patient population compared to a wait and see or traditional Physical Therapy approach (modalities, massage). They reviewed the data from 7 studies and reported heavy eccentric training may be superior to a wait and see approach and traditional Physical Therapy. Authors also found a trend showing these heavy eccentric exercises may be less effective than other forms of exercise (isometric, isotonic).

This review is consistent with our current understanding on tendon management. Tendons should be progressively loaded based on the tendon’s tissue tolerance and irritability. Although eccentric exercise has become popular, other forms of exercise and loading strategies should also be considered as part of the tendon loading plan of care. When it comes to tendons, one size does not fit all.

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Ankle Mobility and Achilles Tendon Injury

The achilles tendon is a strong, durable structure capable of absorbing and producing large loads as we walk, hike, and run.  When the tendon is overloaded without adequate recovery periods this structure is prone to painful and limiting conditions such as achilles tendonitis and tendinopathy.  One of the important risk factors for achilles injury among athletes and patients is a lack of ankle mobility.  If the ankle is unable to bend adequately during functional movements the achilles is placed under increased load leading to tendon injury.  In our Boulder Physical Therapy practice, we commonly see a loss of ankle mobility among patients with achilles tendon injury.

During our Physical Therapy examination we often see a loss of rear foot or ankle mobility and a compensatory increase in motion at the mid foot or arch (pronation).  A recent study in the journal Clinical Biomechanics confirmed our observations (Chimenti, R. et al. 2016).  The authors assessed individuals with and without achilles tendinopathy to determine their ability to bend their ankle as well as which areas of the ankle and foot where contributing to this movement.  The group with achilles tendinopathy had significantly less ankle mobility than the control group.  Importantly, this group compensated during testing with increased mobility of their arch instead due to an inability to move through the rearfoot.

This study highlights the importance of treating the ankle in patients with achilles tendon injury.  To learn more about how to safely and effectively treat this condition contact your local PT.

Increased Achilles Tendon Loading In Treadmill Running

The treadmill remains a necessary evil when completing run training allowing athletes to escape inclement weather to complete their workouts.  Thankfully, in Boulder we have few inclement days as we move through the Spring and Summer months allowing athletes to train outside.  Prior research has noted significant bio-mechanical differences in treadmill vs. ground running including athletes adopting a shorter stride length on the treadmill.  This reduction in stride length is accompanied by an increased in step frequency to maintain a given speed.  These changes will impact the rate and magnitude of loading across the leg during landing.  Recently, a Physical Therapy article examined the biomechanical impact of treadmill and over ground running on the knee and ankle structures. 

Willy and colleagues studied 18 healthy runners (9 female) who were running at least 10 km per week over the last 6 months and were free of injury over the previous 3 months (JOSPT. 2016).  Runners were analyzed in a Physical Therapy biomechanics laboratory while running on a treadmill and overground both at a previously self selected gait speed.  

Similar to prior research, runners selected a shorter stride length when using the treadmill compared to level ground.  The authors did not find differences in knee mechanics or loading between the two conditions.  Conversely, the authors noted greater achilles tendon loading and calf muscle contraction during treadmill running.  They attributed these changes to increased peak tendon forces during the treadmill run.  

This article was performed in healthy individuals but may have implications for those returning to running from achilles injury or those using the treadmill for the majority of their training runs.  

 

Foot Orthotics and Overuse Injury

Customized foot orthotics based off a clinical examination, plaster or foam cast have been utilized for decades in order to treat overuse injuries of the foot, ankle, knee, hip and even spine.  These orthotics are usually not covered by insurance and usually run into the hundreds of dollars compared to an off the shelf model.  Many businesses have opened up lately specializing in the prescription and fabrication of orthotics for these conditions claiming correction of the foot and ankle can change the mechanics up the kinetic chain.  Up to this point, with a few patient exceptions, customized orthotics have not been proven more effective than cheaper off the shelf orthotics.  

This blog has previously posted on many aspects of achilles tendinopathy.  A recent article examined in the British Journal of Sports Medicine randomized 140 patients with achilles tendinopathy to either a sham orthotic or a customized orthotic (Munteanu et al. 2015).  In addition, both groups were given eccentric calf strengthening exercises.  The patients were followed over a total of 12 months.  Authors noted improvement in both groups, but no difference between groups at either short or long term functional or clinical outcomes.    It appears the orthotic did not improve symptoms or function above or beyond improvements noted with the eccentric exercise.  

In short, consistent with prior research, customized orthotics are not more effective than other interventions for overuse injuries of the lower extremity.  Future research should attempt to identify any individual factors that may indicate a need for an orthotic intervention.  

Why is eccentric exercise helpful for achilles tendinopathy?

One of things I enjoy about the profession of Physical Therapy is its’ constantly changing nature of the medical evidence behind what we do.  Often I come across a new article or research report, which challenges my previous line of thought about an injury or treatment and requires me to change.  Achilles Tendinopathy is commonly and effectively treated with eccentric (lengthening) exercise in our practice.  My previous explanation on the benefits of this exercise was the positive structural effects noted in the tendon following this exercise prescription (see hyperlink above).  It now appears the structural change explanation does not completely explain the beneficial effects of this intervention.

eccentric exercise, achilles injury, physical therapy

Previously it was thought that the higher loads experienced during eccentric contractions in the Achilles tendon promoted structural adaptations, which remodeled (healed) the tendinopathy (Stanish et al. Clin Orthop. 1986).   These adaptations take time, often years, to complete yet our patients demonstrated decreased pain and improved function in less than 12 weeks.  The discrepancy between time to remodel and clinical improvement requires us to consider a different mechanism of action.

Recently, O’Neill and colleagues wrote an excellent clinical commentary in the International Journal of Sports Physical Therapy exploring other mechanisms behind the positive effects of eccentric exercise on this condition.  The authors described literature suggesting the neuromuscular output of the gastrocnemius and soleus muscles may explain more of the benefits behind exercise.  It is very common to find a loss of dorsiflexion (bending) of the ankle during the Physical Therapy examination in patients with Achilles tendinopathy.  Mueller et al. initially suggested patients with weakened plantar flexors of the ankle (heel raise or push off) use a smaller range of ankle dorsiflexion (bending) to optimize push off during walking (Phys Ther. 1995).  Thus treatments to restore ankle dorsiflexion will be more effective if we can restore the motor properties of the ankle plantarflexors.

Achilles Tendinopathy is a very painful condition and the tendon itself often has a lower threshold for producing a pain response through walking, stretch, or touch.  Authors note this may be due to an increase in nerve and blood vessel (neurovascular) growth into the tendon during the tendinopathy (Ohberg et al. Knee Surg Sports Traumatol Arthrosc. 2004).   Eccentric exercise may promote beneficial structural changes within these nerves and vessels through loading, but the contribution of neurovascular changes on a patient’s pain or prognosis is not known.

Authors previously reported a loss of plantarflexion strength and power is an independent risk factor for Achilles tendinopathy (Mahieu et al. Am J Sp Med. 2006).  It is likely that the calf muscle is able to shield the tendon to avoid excessive loading during walking or sports.  Improved strength and coordination through eccentric exercise also appears to coordinate and smooth muscle contractions in the calf thereby decreased asymmetrical loading patterns on the tendon.

physical therapy eccentric exercise, achilles tendinopathy, strengthening

In short, eccentric exercise remains a staple in the conservative Physical Therapy management of Achilles tendinopathy but the reasons on its’ effectiveness continue to develop.  Our current understanding makes passive interventions such as modalities, orthotics, etc. less likely to create the positive effects seen with exercise.  It appears the improvement in neuromuscular strength, balance, and coordination help shield the tendon from excessive loads.  In addition, these mechanismTo learn about the beneficial effects of eccentric exercise on tendon injuries contact the experts at Mend.