The iWALK crutch provides significant advantages compared to crutches or knee scooters

iWALK is preferred by 9 out of 10 patients which has implications in improving compliance, preventing complications and faster recovery

The iWALK is preferred by 86% of foot and ankle patients over crutches (Martin et al., 2019). Patient satisfaction and preference determines the level patients comply to non-weight bearing recommendations (Martin et al., 2019) which is of paramount importance to achieving optimal results and prevent postoperative complications such as wound breakdown, loss of fracture fixation or hardware failure (Chiodo et al., 2016; Gershkovich et al., 2016).

Allows hands free mobility with patients being able to do activities of daily living that can impact a patient’s wellbeing and improve compliance

Unlike crutches and knee scooters, the iWALK is a hand free mobility device. Thus, activities of daily living (ADLs and IADLs) that are impossible to do with crutches and knee scooters such as shopping, working, cooking, child care, etc. are possible with the iWALK. A randomized control trial with 80 patients with both upper and lower limb injuries showed that they were able to complete activities around the house using the iWALK (Rambani et al., 2007) and patients had a more positive attitude to life due to the improved independence with the iWALK (Barth et al., 2019). This could be just one of the reasons why the iWALK has a higher preference rating than crutches (Martin et al., 2019).

Increases muscle activity (which leads to decreased muscle atrophy, increased blood flow, and faster healing)

Research proves that the iWALK provides statistically significant increases in muscle activity for the hip, quadriceps and calf muscles in the non-weight bearing leg with muscle activity patterns consistent with normal unassisted ambulation in terms of both intensity and activation per EMG recordings (Dewar & Martin, 2020; Sanders et al., 2018). On the other hand, crutches and knee scooters lead to statistically significant reductions in muscle activity in the non-weight bearing leg compared to normal unassisted ambulation (Clark et al., 2004; Dewar & Martin, 2020; Sanders et al., 2018; Seynnes et al., 2008). The heightened level of muscle engagement in the non-weight bearing leg using the iWALK compared to crutches could potentially lead to decreased atrophy, increased blood flow and enhanced healing (Dewar & Martin, 2020).

Decreases muscle atrophy

The heightened recruitment of the muscles in the non-weight bearing leg when using the iWALK compared to crutches is expected to decrease the level of disuse muscle atrophy (Dewar & Martin, 2020), based on associated research that shows the degree a muscle will atrophy is dependent on the activity of the muscle (Antonutto et al., 1999; Clark, 2009; Clark et al., 2004). This is further supported by prior research that shows a muscle fixed in a shorted position atrophies faster than if a muscle is fixed in a lengthened position (Booth, 1982; Booth & Gollnick, 1983). Thus, the knee flexion angle was shown to play an important role in muscle atrophy (Campbell et al., 2019). Because the iWALK fixes the knee angle at 90° flexion which increases the muscle length, the muscle atrophy after a period of non-weight bearing is expected to be less compared to crutches that fixes the knee angle at approximately 30°. This could partially explain why crutches have been shown to have led to significant muscle atrophy with reductions in muscle size and strength as well as structural changes in muscle fibers in various prior studies (De Boer et al., 2007; Hather et al., 1992; Tesch et al., 2016).

Increases blood flow (reduced risk of developing blood clots and enhance healing)

Using the iWALK crutch leads to increased blood flow in the non-weight bearing limb. Research has shown that an iWALK provides the greatest muscle activity compared to both crutches and knee scooters (Dewar & Martin, 2020; Sanders et al., 2018) and associated research has shown that muscle activity has a major impact on blood flow while having a larger effect on flow than knee flexion angle (Berlet et al., 2021). This corroborates the findings of prior works which reported a significant decline in blood flow for knee scooters (Ciufo et al., 2018) with crutches leading to the greatest decrease secondary to the static position the leg is held in (Berlet et al., 2021). When poor blood flow continues, it can cause DVT (blood clots) in the lower extremities (Faghri et al., 1997; McLachlin et al., 1960; 1960; 1960) and causing pain venous congestion and life-threatening pulmonary embolisms (PE). Reduced blood flow can also impact oxygen delivery to the injured muscle and bone which is important for healing (Lu et al., 2013).

Faster recovery that can allow quicker returns to work and reduce costs to the healthcare system

A randomized control trial conducted using 80 patients showed that patients were discharged significantly faster after using an iWALK compared with using other mobility devices (Rambani et al., 2007). Reductions in muscle atrophy and improvement in blood flow when using an iWALK could impact the total recovery time for lower limb injuries with quicker rehabilitation, potentially faster healing and less cases of blood clots (Dewar & Martin, 2020). The increased muscle oxygenation saturation using the iWALK via improved blood flow could also potentially impact healing (Lu et al., 2013). Crutches cause reductions in cross-sectional area of the quadriceps femoris muscle of 0.4% per day (Clark et al., 2004). Because the iWALK increases the muscle activity of both lower extremities that could reduce muscle atrophy, it could lead to faster therapeutic gains. In addition to these, secondary injuries as a result of using crutches are nonexistent when using an iWALK which could also contribute to reducing the recovery times of lower limb injuries.

Eliminates crutch and knee scooter associated secondary injuries

Crutches lead to seven-fold increase in the force that runs through the axilla (Rambani et al., 2007). This increased force at the axilla has been shown to lead to secondary injuries such as axillary artery thrombosis (Tripp & Cook, 1998) and crutch palsy (Raikin & Froimson, 1997). Other complications as a result of crutch use are carpal tunnel syndrome (Gellman et al., 1988) and shoulder joint degeneration (Shabas & Scheiber, 1986). Secondary injuries may also occur with knee scooters due to the increased risk of falling (Rahman et al., 2020; Yeoh et al., 2017). Because there is no loading of the hands and upper extremity when using an iWALK, secondary injuries have not been reported with the iWALK.

Increases compliance to non-weight bearing that can allow less complications and subsequently faster recovery

The iWALK could improve patient compliance to non-weight bearing restrictions, due to prior research that shows that patients prefer an iWALK over crutches and the important role patient preference plays on patient compliance (Martin et al., 2019). In addition to this, because patients are able to function independently using an iWALK with the ability to do activities of daily living (Rambani et al., 2007), the iWALK will lead to better compliance for patients with lower limb injuries who have been known to be noncompliant with prescribed weight bearing restrictions in prior studies (Chiodo et al., 2016; Gershkovich et al., 2016; Kubiak et al., 2013). Lack of compliance may lead to complications such as wound breakdown, loss of fracture fixation or hardware failure (Gershkovich et al., 2016).

Reduces the energy cost of ambulation that can allow patients to ambulate for longer durations and increase compliance

Increased physiological demand has been shown to be an important factor in discontinuance and noncompliance to weight bearing restrictions with the use of assistive devices (Bateni & Maki, 2005). Therefore, mobility devices designed to assist ambulation should keep energy expenditure to a minimum while still allowing normal walking speeds. Prior research shows that the physiological demand and exertion are lowest for the iWALK compared to both crutches and knee scooters (Kocher et al., 2016; Martin et al., 2019). Crutches lead to lower gait speed and increased rate of perceived exertion (Bhambani & Clarkson, 1989). This is further supported in other prior studies where crutches have significantly higher energy costs compared to normal unassisted ambulation (Dounis et al., 1980; Mcbeath et al., 1974; Nielsen et al., 1990; Sankarankutty et al., 1979; Thys et al., 1996).

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DIRECT RESEARCH

Patient Preference and Physical Demand for Hands-Free Single Crutch vs. Standard Axillary Crutches in Foot and Ankle Patients

Kevin D. Martin, DO, Alicia M. Unangst, DO, Jeannie Huh, MD and Jamie Chisholm, MBA

Summary: This study proved that 9 out of 10 patients prefer a hands-free crutch (iWALK) over crutches. Patients experienced less discomfort and exertion when using the hands-free crutch compared with crutches.

“The Hands-Free Single Crutch (HFSC) was preferred by 86% of patients. Significantly lower dyspnea scores (2.8 vs 5.3; P<0.001), fatigue scores (2.4 vs 5.5; P<0.001), pre-activity and post-activity change in heart rate (28 vs 46 bpm; P<0.001), and mean post-activity heart rate (107 vs 122 bpm; P<0.001) were found using the HFSC compared with the Standard Axillary Crutches (SACs)… SACs have demonstrated a substantial energy cost compared with normal gait, and they have been also been associated with injury… Selecting an appropriate assistive device is multifactorial and should be patient specific to improve patient compliance and optimize mobility and safety… Understanding physiologic cost, function, fall risk, and overall patient satisfaction could aid healthcare providers in determining an appropriate ambulatory device that is patient specific.”

Comparison of Lower Extremity EMG Muscle Testing with Hands-Free Single Crutch vs Standard Axillary Crutches

Cuyler Dewar, MS, and Kevin Martin, DO, FAAOS, DAL

Summary: With standard crutches there is near zero muscle activity in the injured leg. With a hands-free crutch the leg muscles are firing similar to normal human gait. Electromyography (EMG) proved that there is muscle engagement in the injured lower leg while using the iWALK, which could reduce the atrophy generally seen with crutches and improve blood return that could reduce the risk of developing blood clots. These benefits will allow faster recovery times for people with lower extremity injuries

“The Hands-Free Single Crutch (HFSC) subjects demonstrated increased muscle recruitment and intensity while maintaining cyclic contractions consistent with bipedal gait pattern. Standard Axillary Crutches (SAC) demonstrated less recruitment and intensity with an isometric pattern regardless of the phase of gait… SAC use can result in muscle atrophy and decreased blood flow… When muscle activity is decreased in a nonweightbearing lower extremity, the risk of developing a deep vein thrombosis will increase… The rectus femoris and gluteus maximus had statistically significant increases in mean muscle activity and MVIC percentage, while the lateral gastrocnemius showed statistically significant increase in mean muscle activity and the vastus lateralis showed a statistically significant increase in MVIC percentage. The heightened recruitment of these muscles while using the HFSC will potentially translate to decreased levels of muscle atrophy during the nonweightbearing period after a lower extremity injury. Reduced muscle atrophy will potentially allow for quicker rehabilitation secondary to retained balance and proprioception. The heightened cyclic muscle contractions will also facilitate vascularization of the lower extremity, while reducing potentially slowed venous return.”

Use of a Hands-Free Crutch in Patients with Musculoskeletal Injuries

R. Rambani, M. S. Shadid, and S. Goyal

Summary: Patients that use a hands-free crutch are discharged significantly faster than patients who do not use it.

“The average stay of the patients using a hands-free crutch (HFC) was 2.3 days, with a range of 1-5 days. This was much shorter compared with the stay for patients who had similar injuries and had decided not to use this crutch: 4-14 days (average, 6.7 days). This difference was statistically significant (P=0.05)… This not only helps in decreasing the burden on the hospital in terms of the expenses of hospital stay, but also helps the patient to be independent quickly, after an injury… The HFC was associated with a better overall musculoskeletal functional assessment score (P<0.05), better coping, a trend towards better lower extremity function, and with performing activities around the house. The HFC was well accepted, safe, and easy to use. A clear trend for better function with the HFC was seen. SF-36 physical function tended to be better with the HFC (P<0.05)… The HFC is a viable alternative for patients required to be nonweightbearing during ambulation.”

Alternative Mobilization by Means of a Novel Orthosis in Patients after Amputation

U. Barth, K. Wasseroth, Z. Halloul, F. Meyer

Summary:Patients using an iWALK exhibited improvements in their ability to perform activities of daily living. The iWALK was shown to provide emotional and psychological benefits and was well accepted.

“The successful application of the “hand free” device “iWALK2.0” under the listed clinical condition thus suggest that it is a clear alternative of postoperative rehabilitation in the diagnosis of a surgically treated diabetic foot gangrene after minor amputation ……in addition to giving the patient as much independence as possible, this also made the patient feel positive about life again….overall the iWALK orthosis was considered by the patient to be of a high quality and comfortable, and it was completely accepted, which also helped to motivate the patient with mobilization.”

ASSOCIATE RESEARCH

Pedal Musculovenous Pump Activation Effectively Counteracts Negative Impact of Knee Flexion on Human Popliteal Venous Flow

C. W. Reb, E. T. Haupt, R. A. Vander Griend, and G. C. Berlet

Summary: Crutches with slight knee flexion leads to the greatest decrease in blood flow compared to upright and knee scooter positioning. Muscle activity has been shown to have a greater impact on blood flow than knee flexion angle which has implications in blood clotting.

“There was a significant decrease in pedal musculovenous pump (PMP) time-averaged peak velocity (TAPV) when comparing upright to crutch positioning, and this decrease was slightly more when comparing upright to knee scooter positioning (knee at 90°)… Knee flexion was found to have a variable but generally small negative effect on popliteal venous flow. The trend was toward greater flow impedance with increasing knee flexion… PMP activation where permissible is a potentially valuable venous stasis countermeasure to consider.”

Skeletal muscle responses to lower limb suspension in humans

B. M. Hather, G. R. Adams, P. A. Tesch, and G. A. Dudley

Summary: Crutches lead to decreases in muscle size.

“Magnetic resonance images pre- and post-ULLS showed that thigh muscle cross-sectional area (CSA) decreased (P less than 0.05) 12% in the suspended left lower limb… The three vastus muscles showed similar decreases of approximately 16% (P less than 0.05). The apparent atrophy in the leg was due mainly to reductions in CSA of the soleus (-17%) and gastrocnemius muscles (-26%). Biopsies of the left vastus lateralis pre- and post-ULLS showed a 14% decrease (P less than 0.05) in average fiber CSA. The decrease was evident in both type I (-12%) and II (-15%) fibers.”

Adaptations to unilateral lower limb suspension in humans

G. A. Dudley, M. R. Duvoisin, G. R. Adams, R. A. Meyer, A. H. Belew, and P. Buchanan

Summary: Reductions in muscle strength occur after 6 weeks of crutch use.

“Strength of the KE of the suspended left limb was reduced (p less than 0.05) 21 and 15%, respectively, after ULLS and 4 d later. Average muscle CSA of the left KE decreased (p less than 0.05) 16%… Average muscle CSA of the KE of the suspended limb was 17% less (p less than 0.05) than that of the non-suspended limb. Average muscle CSA of the AE, likewise, was smaller (18%, p less than 0.05) in the left than right leg after ULLS. Maximal integrated EMG of VL and overall mean power frequency of GM and SL for submaximal isometric actions were both decreased (p less than 0.05) post-ULLS.”

Early structural adaptations to unloading in the human calf muscles

O. R. Seynnes, C. N. Maganaris, M. D. de Boer, P. E. di Prampero, and M. V. Narici

Summary: Using crutches cause structural changes in muscle fibers that reduce muscle function.

“Soleus (SOL), gastrocnemius medialis (GM) and lateralis muscle (GL) volume decreased by 5%, 6% and 5%, respectively (P < 0.05), on day 14, and by 7% (SOL), 10% (GM) and 6% (GL) on day 23. In GL, pennation angle and fascicle length were reduced by 3% (P < 0.05) and 2% (NS), respectively, on day 14, and by 5% (P < 0.05) and 4% (P < 0.05), respectively, on day 23. Consequently, GL physiological cross-sectional area (PCSA) declined by 3% (P < 0.05) on day 14, but did not further decrease on day 23. Similarly, the 7% (P < 0.05) loss in GL force/PCSA observed on day 14 persisted until the end of the unloading period.”

Time course of muscular, neural and tendinous adaptations to 23 day unilateral lower-limb suspension in young men

M. D. de Boer, C. N. Maganaris, O. R. Seynnes, M. J. Rennie, and M. V. Narici

Summary: Crutches lead to reductions in tendon collagen synthesis. This can influence the ability to transfer force from muscle contractions to skeleton.

“After 14 and 23 days (i) knee extensor torque decreased by 14.8 +/- 5.5% (P < 0.001) and 21.0 +/- 7.1% (P < 0.001), respectively; (ii) voluntary activation did not change; (iii) knee extensor cross-sectional area decreased by 5.2 +/- 0.7% (P < 0.001) and 10.0 +/- 2.0% (P < 0.001), respectively; fascicle length decreased by 5.9% (n.s.) and 7.7% (P < 0.05), respectively, and by 3.2% (P < 0.05) and 7.6% (P < 0.01); (iv) tendon stiffness decreased by 9.8 +/- 8.2% (P < 0.05) and 29.3 +/- 11.5% (P < 0.005), respectively, and Young’s modulus by 9.2 +/- 8.2% (P < 0.05) and 30.1 +/- 11.9% (P < 0.01), respectively, with no changes in the controls. Hence, ULLS induces rapid losses of knee extensor muscle size, architecture and function.”

Bone loss from the human tibia epiphysis during 24 days of unilateral lower limb suspension

J. Rittweger, K. Winwood, O. Seynnes, M. de Boer, D. Wilks, R. Lea, M. Rennie, and M. Narici

Summary: Crutches lead to bone loss comparable to those seen with bed rest. Losses in bone mineral content can result in decreased bone strength and increased risk of fracture as well as side effects such as high calcium levels in the blood and kidney stones.

“After 21 days of unilateral lower limb suspension (ULLS), bone mineral content of the peripheral portion of the epiphysis of the suspended tibia was reduced by 0.89 ± 0.48% (from 280.9 ± 34.5 to 278.4 ± 34.2 mg mm−1, P<0.001)… In the peripheral epiphyseal portion, significant bone loss (by 0.32 ± 0.54%, P = 0.045) occurred as early as day 7 of ULLS… Our findings suggest that in its extent bone loss in ULLS resembles the bone loss induced by bed rest.”

One-leg inactivity induces a reduction in mitochondrial oxidative capacity, intramyocellular lipid accumulatio and reduced insulin signaling upon lipid infusion: a human study with unilateral limb suspension

L. Bilet, E. Phielix, T. van de Weijer, A. Gemmink, M. Bosma, E. Moonen-Kornips, J. A. Jorgensen,G. Schaart, D. Zhang, K. Meijer, M. Hopman, M. K. C. Hesselink, D. M. Ouwens, G. I. Shulman, V. B. Schrauwen-Hinderling, P. Schrauwen

Summary: Crutches lead to low mitochondrial oxidative capacity and reduced insulin sensitivity that are common denominators of chronic metabolic disorders, like obesity and type 2 diabetes.

“In vivo, mitochondrial oxidative capacity, assessed by phosphocreatine (PCr)-recovery half-time, was lower in the inactive vs active leg. Ex vivo, palmitate oxidation to 14CO2 was lower in the suspended leg vs the active leg; however, this did not result in significantly higher [14C]palmitate incorporation into triacylglycerol. The reduced mitochondrial function in the suspended leg was, however, paralleled by augmented intramyocellular lipid content in both musculus tibialis anterior and musculus vastus lateralis, and by increased membrane bound protein kinase C (PKC) θ. Finally, upon lipid infusion, insulin signalling was lower in the suspended vs active leg… This demonstrates the importance of mitochondrial oxidative capacity and muscle fat accumulation in the development of insulin resistance in humans.”

Impact of knee scooter flexion position on venous flow rate

D. J. Ciufo, MD, M. R. Anderson, DO, and J. F. Baumhauer, MD, MPH

Summary: Knee scooters demonstrate a significant decrease in blood flow rate. Decreased blood flow is a known risk factor of blood clots.

“Measurements of subjects while standing and on the knee scooter demonstrated a significant decrease in mean velocity (6.5 vs 3.2 cm/s, P < .01) and volumetric flow rate (227.8 vs 106.2 mL/min, P < .01) while subjects were using the scooter… Our findings demonstrated a statistically significant decrease in volumetric flow rate in subjects using a knee scooter device with a flexed knee… Suggesting that the scooter could pose a risk of DVT formation.”

Energy cost of ambulation with crutches

S. V. Fisher and R. P. Patterson

Summary: Crutches increase the energy needed to ambulate as compared to normal walking.

“The energy cost (oxygen consumption) VO2.wt-1 (ml.min-1.kg-1) of ambulating with underarm crutches compared to normal walking was approximately twice as great. The heart rate (HR) and VO2 for any given rate of vertical rise tested was less with crutch stair climbing than with crutch walking. There was no difference in VO2 or HR when ambulating with underarm compared to forearm (Lofstrand) crutches.”

Post-Operative Use of the Knee Walker After Foot and Ankle Surgery, A Retrospective Study

Jane Yeoh MD FRCSD, David Ruta MD, David Richardson, MD, Susan Ishikawa MD, Benjamin Gear MD, Dlayton Bettin MD

Summary: Knee scooters were shown to lead to a significant number of falls with a high percentage of knee scooter users falling multiple times.

“The goal of this study is to quantify and describe patient use of knee walkers after foot and ankle surgery in the group practice of foot and ankle surgeons at multiple sites and a single institution. Primary endpoints include occurrence of falls, frequency of falls, and injury……..44% fell while using the knee walker, and nearly two-thirds (65%) of those who fell reported multiple falls….”

RESEARCH REVIEW

Prospective Clinical Evaluation Comparing Standard Axillary Crutches versus the Hands Free Crutch

A Dalton, D.Maxwell, C.M. Borkhoff, H.J. Kreder
University of Toronto, Sunnybrook & Women’s College Health Sciences Centre

Summary: Patients experience better overall function when they were able to use their hands while being non-weight bearing for lower extremity injuries with the hands-free crutch.

“Activities of daily living were easier to accomplish with the HFC (p=0.07). None of the patients found the HFC to be uncomfortable, while 2/6 found the SAC to be uncomfortable… The HFC was associated with a better overall MFA score (p<0.05), better coping (p<0.05), and a trend toward better lower extremity function and activities around the house (p=0.07). SF-36 physical function tended to be better with the HFC (p=0.08) in addition to SF-36 vitality (p=0.07). The HFC was well-accepted, safe and easy to use. There was a clear trend for better function with the HFC.”

Evaluation of Crutch Energetics Using Standard and Hands Free Crutches

A.Nagpurkar, A. Troelier

University of Guelph, Clinical Biomechanics

Summary: Crutches lead to higher energy expenditure compared to a hands-free crutch.

“The primary purpose of this study was to compare the two-dimensional mechanical energetics of normal walking, swing-through gait with underarm crutches and a novel “hands-free” crutch. The crutch demonstrated the highest energy inefficiency followed by the hands-free crutch, compared to normal walking. This trend was expected since previous swing-through crutch studies have indicated significant increases in energy compared to normal walking.”

A Hands-free Approach to Patient Mobility: Presenting the Case for a Hands-free Crutch

D. Parker, J. Davis

Summary: A hands-free crutch improves compliance to non-weight bearing recommendations as compared to crutches.

“Crutches can prove awkward and painful for many patients and offers only limited mobility, particularly on stairs. This sometimes causes the patient to ‘cheat’ by putting weight on the affected limb from time to time or discarding their crutches before the required period outlined by their consultant / practitioner… Not only is the resulting lack of mobility frustrating for the patient, crutches may also result in a prolonged hospital stay, which is a drain on resources and may even affect the patient’s feelings of well-being, and in turn, hold back their recovery… With a hands-free crutch, they can, for the most part, get on with life while being NWB, thus their injuries heal which speeds up their recovery by improving their feelings of well-being. The hands-free crutch allows the injured lower leg to be rested on a moulded shelf and strapped into position. This means that the device actively ensures that patients follow their NWB instruction and do not set back their recovery putting weight on the affected leg.”

Mobility Device Use in the United states – Functional Limitations of Crutch Users

H. Stephen Kaye, T. Kang, M. P. LaPlante

National Institute on Disability and Rehabilitation Research, Disability Statistics Report 14

Summary: Crutch users require assistance in performing activities of daily living (ADLs and IADLs).

“81.8% of crutch users report functional limitation… A majority of crutch users have instrumental activities of daily living (IADL) limitations (62.2%), most of whom need assistance (55.7%).”

Comparison of Subjective and Physical Function Outcomes Using Axillary Crutches and a “Hands-Free Crutch”, in Comparison to No Crutch, for Mobility

G. A. Lim, T. D. MacLeaod

California State University, Sacramento Department of Physical Therapy

Summary: Functional outcomes were better using the hands-free crutch compared to crutches and was preferred over crutches.

“During the stair climbing test and timed-up-and-go test, subjects trended towards being faster with the hands-free crutch than the axillary crutches… Functional outcomes were better using the hands-free crutch in comparison to the more standard axillary crutches while performing clinical outcome measures of activity…The majority of subjects preferred the hands-free crutch while performing the stair climbing test and 6-minute-walk-test.”