Overview. Current Treatments

Transcription

1 ASTRO XO Overview Plantar fasciitis (PF) is a perplexing and often chronic condition that is the third most prevalent injury in runners but also affects 10% of the average population at some point in their lifetime [1,2]. The most common complaint is plantar heel pain, especially with first steps in the morning and during ambulation. The primary risk factor is mechanical overload of the plantar tissues, which frequently occurs as a result of tightness in the gastrocnemius soleus (GS) complex, pes planus (flatfoot deformity), decreased ankle dorsiflexion ROM and high BMI [1,4,6]. While it has traditionally been treated as a fasciitis (inflammation of the plantar fascial tissues), research points more toward a fasciosis involving microtears of the plantar fascial ligament origin at the calcaneus [3]. Current Treatments PF usually takes 6-18 months to resolve [7] often causing frustration for the patient and treating practitioner. Experts agree that early management of this condition is key to achieving greater success with non-invasive therapies. Traditional treatment includes stretching and strengthening exercises, modalities, orthotics, night splints and anti-inflammatories. Chronic cases may be treated with more invasive treatments such as corticosteroid injections and even surgical release. The more aggressive treatments for PF have concerning limitations. A literature review by Tahririan et al. looked at the efficacy of surgical release and found it is inconsistent, providing complete symptomatic relief in only 50% of patients [5] and usually requiring permanent use of orthotics due to post-op pes planus development [8]. Corticosteroid injections were found to 1

2 be as effective for symptomatic relief as plantar stretching over the course of 8 weeks [9], and run a low, but concerning risk of plantar fascial rupture [10,11]. Thus, risk of corticosteroid use compared to its efficacy is questionable given the non-inflammatory nature of PF [3]. While pain reduction can be attained through these approaches, their limitation lies in how to address the root cause of the problem. The persistent stress of daily weight bearing, especially with prolonged ambulation, continually exacerbates the plantar fascial microtears delaying recovery from PF. Biomechanical Factors in Plantar Fasciitis Rubeiro et al. investigated plantar pressures in runners with PF. They found significantly higher rearfoot plantar loads were present in those with acute and chronic PF when compared to controls [1]. It stands to reason that decreasing heel contact time and plantar loads would be an important goal in restoring normal gait and reducing plantar fascial pain. A study by Kibler et al. looked at biomechanical deficits associated with PF in runners and found a high percentage of them have plantar flexion strength deficits and dorsiflexion ROM deficits [13]. GS tightness, usually linked to decreased dorsiflexion ROM, has also been associated with increased Achilles tendon and plantar fascial strain [14]. Ankle ROM deficits were further investigated in a recent study comparing foot and ankle pain between subjects with varying amounts of dorsiflexion. They found that subjects reporting foot and ankle pain had significantly reduced ankle dorsiflexion ROM when compared to controls [15]. Since decreased ankle dorsiflexion is associated with increased pain and is a hallmark of PF, this data supports the importance of regaining full ankle ROM to help decrease pain and reduce plantar fascial strain. 2

3 ASTRO XO Biomechanics The ASTRO XO passive exoskeleton (Figure 1) is a unique device that assists the foot and ankle to manage the damaging forces associated with PF that occur during ambulation. The exoskeleton employs the use of elastic actuators to assist the GS complex eccentrically and concentrically during the gait cycle, thus reducing the amount of work done by the GS during ambulation. Recent work by Collins et al. published in Nature showed that an exoskeleton similar to that of ASTRO XO (Figure 2) reduced the biological ankle moment required to ambulate as the exoskeleton absorbed some of the work done by the lower leg to generate forward propulsion [12]. The net result of ASTRO XO use is reduced stress on lower leg tissues during the healing process and encouragement of normal gait biomechanics. 3

4 The ingenuity of the ASTRO XO device lies in its simplicity, essentially using light forces from an elastic actuator to add pounds of force in the form of plantar flexion assist. It is designed to be worn during gait training (walking) for only 20 to 30 minutes per day for approximately 8 weeks. Walking with the device reduces stress to the GS musculature and plantar fascia while helping to normalize gait. ASTRO XO Clinical Results [16] The ASTRO XO exoskeleton clinical trial was conducted by the Scholl School of Podiatry at Rosalind Franklin University, North Chicago, IL in conjunction with Weil Foot and Ankle Research Institute, Des Plaines, Illinois. This study recruited 12 participants who had experienced PF for an average of 11.7 months and treated them with the ASTRO XO device for 12 weeks. The patients were asked to walk minutes per day using the device. Ten patients completed the study resulting in the following findings after 12 weeks of use: Pain Reduction & Improved Foot Function - A 71% reduction in first step morning pain (Figure 3) and a 65% reduction in evening pain on the VAS scale, which combined with the ratings on the Foot Function Index (FFI) to result in a 46% improvement in foot function (Figure 4). 4

5 Increased Ankle Dorsiflexion - Restoration of ankle joint ROM as seen by a 38% improvement in ankle dorsiflexion (Figure 5) during the Lunge Test. Increased Tibialis Anterior Active Time - A 95% increase in the active time of tibialis anterior (TA) during stance phase, contributing to increased ankle DF ROM (Figure 6). Increased Gastrocnemius Active Time - Gastrocnemius activation time was increased by 74% (lateral) and 33% (medial), which is thought to support increased plantar flexion ROM and strength (Figure 7). Improved Measures of Forward Propulsion - A 39% reduction in heel contact time and 41% reduction in peak plantar pressure time integral, both of which promote forward propulsion by encouraging the patient to move faster and more effectively into toe off (Figure 8). TA active time was increased significantly by 95% during stance phase (Figure 6). The increased TA activation is thought to assist the ankle into a position of greater dorsiflexion and aid in eccentric GS loading. The loading of the GS generates an increase in ankle moment and power, resulting in greater forward propulsion. 5

6 Practitioners may question the effect on the TA, which needs to work harder during swing phase to overcome the plantarflexion force provided by the exoskeleton. However, trial participants reported only 1-2 days of mild fatigue in the TA, likely due to the pounds applied concentrically to the TA by the elastic actuator during swing phase. During stance phase, there was an increase in the gastrocnemius active time over the treatment period (Figure 7). The data shows that the gastrocnemius was initially less active, likely due to the altered biomechanics and ankle joint ROM associated with PF. As gait biomechanics are restored and pain decreases, the gastrocnemius active time without the ASTRO XO in place increases, suggesting that the gastrocnemius has regained its strength and ability to provide plantar flexion and forward propulsion. 6

7 The ASTRO XO clinical trial showed that dynamic plantar pressures initially focused in the rearfoot of the injured leg at Week 0 were redistributed more evenly through rearfoot and forefoot by Week 12 (Figure 8). Additionally, the ASTRO XO device brought the injured, supinated foot into a more neutral stance. It is thought the decreased medial calcaneal pain at the plantar fascial insertion enables a more normal gait pattern. This is further supported by the data that showed a 39% reduction in heel contact time and 41% reduction in the peak pressure time integral. It is reasonable to conclude that a combination of decreased time and pressure on the heel would reduce the stress to the injured plantar fascial tissues and decrease pain. Furthermore, less time spent on the heel translates to more time spent on forward propulsion. 7

8 It is important to remember that the study results we have discussed are those from data without the ASTRO XO device on the participant, providing strong evidence for long-term, positive changes in gait biomechanics after 12 weeks of ASTRO use. Notably, using the ASTRO XO brought about desirable biomechanical changes simply with daily walking while wearing the device, serving as a valuable adjunct to therapy. Additionally, many of the results achieved were evident after only 8 weeks of gait training with the ASTRO XO. Summary The ASTRO XO exoskeleton is a new approach to PF treatment that puts recovery into the hands of the patient. It holds a clear advantage in that it is efficacious compared to other treatment options and is easy to use in the patient s home setting. The ASTRO XO recovery protocol recommends simple stretching in the morning and walking while wearing the device for minutes per day for approximately 8 weeks. For patients with plantar fasciitis, ASTRO XO is a non-invasive, effective treatment that: Reduces pain in PF patients as shown by a decrease in pain ratings on the VAS scale. Improves overall foot function as reported on the FFI, primarily after the first 2 weeks of ASTRO use. Improves ankle joint DF leading to normalized gait patterns and restoration of normal ankle ROM. Increases TA and Gastrocnemius active time during stance, contributing to improved forward propulsion and ankle DF during the gait cycle. Promotes forward propulsive gait as shown by a decrease in heel contact time and more anteriorly concentrated plantar pressures. Decreases heel pressure as evidenced by a decrease in peak pressure time integral. All of these benefits lead to significant reduction in pain and expedited healing allowing these patients to rapidly return to normal activities. 8

9 References: 1. Ribeiro AP, João SMA, Dinato RC, Tessutti VD, Sacco ICN. Dynamic Patterns of Forces and Loading Rate in Runners with Unilateral Plantar Fasciitis: A Cross-Sectional Study. PLoS ONE. 2015; 10(9): e doi: /journal.pone Riddle D, Schappert SM. Volume of ambulatory care visits and patterns of care for patients diagnosed with plantar fasciitis: A national study of medical doctors. Foot and Ankle International. 2004; 25(5): Lemont H, Ammirati KM, Usen N. Plantar Fasciitis: A Degenerative Process (Fasciosis) Without Inflammation. J Am Podiatric Med Assoc. 2003; 93(3): Van Leeuwen KD, Rogers J, Winzenberg T, van Middelkoop M. Higher body mass index is associated with plantar fasicopathy/ plantar fasciitis : systematic review and meta-analysis of various clinical and imaging factors. Br J Sports Med Dec 7. [Epub ahead of print] 5. Tahririan MA, Motififard M, Tahmasebi MN, Siavashi B. Plantar fasciitis. Journal of Research in Medical Sciences : The Official Journal of Isfahan University of Medical Sciences. 2012; 17(8): Irving DB, Cook JL, Menz HB. Factors associated with chronic plantar heel pain: a systematic review. J. Science and Med.in Sport. 2006; 9(1): Young CC, Rutherford DS, Neidfeldt MW. Treatment of plantar fasciitis. Am Fam Physician. 2001; 63: Shazia A, Davinder P, Singh B. Plantar heel pain. Clin Focus Prim Care. 2011; 5: Siavashi B, Naghshbandi SF, Zehtab MJ. Comparison of two methods of decreasing heel pain: Corticosteroid injection versus plantar fasciitis stretching. Iran J Surg. 2009; 17: Acevedo JI, Beskin JL. Complications of plantar fascia rupture associated with corticosteroid injection. Foot Ankle Int. 1998; 19: Sellman JR. Plantar fascia rupture associated with corticosteroid injection. Foot Ankle Int. 1994; 15: Collins SH, Wiggin MB, Sawicki GS. Reducing the energy cost of human walking using an unpowered exoskeleton. Nature 2015; 522: doi: /nature Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med.1991; 19(1): Solan MC, Carne A, Davies MS. Gastrocnemius shortening and heel pain. Foot Ankle Clin. 2014; 19: doi: /j.fcl Jastifer JR, Marston J. Gastrocnemius contracture in patients with and without foot pathology. Foot Ankle Int. July 2016; doi: / Williams B, Fleischer A, Patel N, Cheung A, Crews R, Yalla S. Effectiveness of a novel ankle exoskeleton device for the treatment of plantar heel pain. APMA Poster Presentation, July