Introduction by Tom Goom @TomGoom
Plantar fasciitis can be a nuisance to treat and, to date, we’ve had little high quality evidence to guide us. Today’s blog represents an exciting new direction in treating this stubborn condition. For some time we’ve noted the similarities between plantar fascial problems and tendinopathy. Back in 2006 Scott Wearing wrote an excellent paper on how the two structures shared similar pathology and similar response to load. However, no one has tested whether we might be able to treat plantar fasciitis like a tendinopathy, that is until now… Michael Rathleff and colleagues have just published an exciting new paper that is the first of its kind and represents a new treatment approach for plantar fasciitis, so I was delighted when Michael very kindly agreed to share his findings with us in a guest blog. Michael’s work includes excellent papers on hip strength and patellofemoral pain and patellofemoral pain in adolescents. To find out more about Michael’s research check out his Google Scholar Profile and follow him on Twitter via @MichaelRathleff.
Most of us who have experienced plantar fasciitis know first hand how debilitating and frustrating it can be. Every morning resembles being forced to walk on broken glass and you quickly become grumpy and dissatisfied. The prevalence in the general population is estimated to range from 3.6% to 7% [1 2], and may account for as much as 8% of all running-related injuries [3 4]. The life time prevalence may be as high as 10% which means that quite a big proportion of us will at some point be affected by plantar fasciitis or see these patients in the clinic.
Most previous treatment studies on plantar fasciitis have used a combination of orthotics, plantar specific stretching or similar non-exercise intervention. These interventions have proven successful to some degree and we know they are superior to placebo treatment. However a large proportion of patients still have symptoms two years after the initial diagnosis. Most clinicians who see these patients in the clinic will agree that they can be quite the challenge – especially if they have a long symptom duration. So we definitely need to start thinking about new effective treatments. An interesting thing is that we are starting to realise that there are some similarities between plantar fasciitis and tendinopathy. We know from the literature that high-load strength training appears to be effective in the treatment of tendinopathy . A similar approach to plantar fasciitis therefore seems to be relevant to test. We recently completed a study where we investigated the effect of a high-load strength-training program compared to a standard plantar specific stretching program in the treatment of plantar fasciitis.
Our main question before initiating the trial was how we could induce high tensile forces across the plantar fascia to resemble the loads induced to the patella tendon during e.g. single leg squat. Our approach was to exploit the windlass mechanism during single-leg calf-raises by using a towel to dorsal flex the toes. In theory, the windlass-mechanism would cause a tightening of the plantar fascia during dorsal flexion of the metatarsophalangeal joints while high-loading of the Achilles tendon is transferred to the plantar fascia because of their close anatomical connection [7-9].
We recruited 48 patients with ultrasonography verified plantar fasciitis. They were randomised to either high-load strength training or plantar specific stretching. In addition both groups received a short patient information sheet and gel heel-inserts. The patient information sheet covered information on plantar fasciitis, advice on pain management; information on how to modify physical activity; how to return slowly to sports and information on how to use the gel heel-inserts. On a side note, I think that one of the key things in successful management of plantar fasciitis is to educate the patient. The advice we used can be seen below in table 1.
Table 1: Advice given to the patients
The plantar-specific stretching protocol was identical to that of Digiovanni (2003) . Patients were instructed to perform this exercise whilst sitting by crossing the affected leg over the contralateral leg (Figure 1). Then, while using the hand on the affected side, they were instructed to place the fingers across the base of the toes on the bottom of the foot (distal to the metatarsophalangeal joints) and pull the toes back toward the shin until they felt a stretch in the arch of the foot. They were instructed to palpate the plantar fascia during stretching to ensure tension in the plantar fascia. As in Digiovanni, patients were instructed to perform the stretch 10 times, for 10 seconds, three times per day .
Figure 1: Plantar-specific stretching
High-load strength training consisted of unilateral heel-raises with a towel inserted under the toes to further activate the windlass-mechanism (Figure 2). The towel was individualised, ensuring that the patients had their toes maximally dorsal flexed at the top of the heel-rise. The patients were instructed to perform the exercises every second day for three months. Every heel-rise consisted of a three second concentric phase (going up) and a three second eccentric phase (coming down) with a 2 second isometric phase (pause at the top of the exercise). The high-load strength training was slowly progressed throughout the trial as previously reported by Kongsgaard et al. . They started at 12 repetition maximum (RM) for three sets. After two weeks, they increased the load by using a backpack with books and reduced the number of repetitions to 10RM, simultaneously increasing the number of sets to four. After four weeks, they were instructed to perform 8RM and perform five sets. They were instructed to keep adding books to the backpack as they became stronger.
A key clinical point is that the calf-raises need to be done slowly to decrease the risk of symptom flaring.
Figure 2: High-load strength training
We used the Foot Function Index as our primary outcome after three months but also did follow-ups after 1,6 and 12 months. At our 3 months follow-up we saw that patients randomised to high load strength training had a 29 points lower Foot Function Index. This is far greater than the minimal relevant difference and suggests a superior effect of high-load strength training compared to plantar specific stretching. An important aspect is that we saw no difference between groups at 6 and 12 months indicating no superior long-term effect. However, if you ask patients to choose between two treatments that have similar long-term effect but one will give you a quicker reduction in pain, I am certain that all patients would choose the treatment, which provides them with the quickest reduction in pain.
There are still lots of unanswered questions about why high-load strength training may work in the treatment of plantar fasciitis. One explanation could be that high-load strength training may stimulate increased collagen synthesis which help normalise tendon structure, increase load tolerability of the plantar fascia and thereby improve patient outcomes. Another explanation may be that the exercise help improve ankle dorsal flexion range of motion as well as improving intrinsic foot strength and ankle dorsal flexion strength. When I completed the high-load strength training program as part of our pilot studies I developed good DOMS in the intrinsics which suggest they are active during the exercise. The questions are many and hopefully other researchers will take a critical look at our findings and confirm or contradict our findings.
The loading paradigm for treatment of plantar fasciitis is by no means a miracle treatment. However, it does provide us with the first evidence that high-load strength training may be the road towards more effective treatments for plantar fasciitis. The key message to the patients is that they need to perform the exercises (otherwise they are unlikely to work) and they need to be performed slowly (3s up, 2s pause at the top and 3s down) to decrease risk of symptom flaring and with enough load starting by 12RM for three sets and working their way down to 8RM for five sets.
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