Author: Evrim S. Altinkaynak, PhD
March 21, 2023
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It is generally understood that the incidence of developing a deep vein thrombosis (DVT) is higher for patients with lower limb non-weight bearing injuries than for the general population (Saragas et al., 2014; Sullivan et al., 2019). For instance, the prevalence of DVT for patients after a foot and ankle surgery were reported to be as high as 32% (Saragas et al., 2014). The risk of DVT is a direct consequence of immobilization for prolonged periods of time due to the reduction in blood flow (Bleeker et al., 2004; Bradley et al., 2022; Ciufo et al., 2019) and muscle pump activity as was shown in various prior studies for both knee scooters and crutches (Dewar et al., 2021; Dewar & Martin, 2020). A recently published study comparing the blood flow and vessel dimensions after using the HFC, knee scooter and crutches found that unlike knee scooters and crutches, the HFC did not lead to statistically significant reductions in popliteal blood flow and vessel dimension when compared to unassisted normal walking (Bradley et al., 2022). In addition to this, the HFC leads to a heightened level of muscle activity in the injured limb explaining the increased blood flow observed using the HFC due to prior studies that have shown the influence muscle activity has on blood flow (Bradley & Hernandez, 2011; Dewar et al., 2021; Dewar & Martin, 2020; Reb et al., 2021). This result is impactful as it has been argued in prior studies that a flexed knee angle leads to increasing the risk of DVTs. For instance, subjects who sat for a prolonged period of time were shown to be more likely to develop a DVT according to one study (Kurosawa et al., 2022). Knee scooters like sitting fixes the knee angle to be approximately 90 degrees for a prolonged period of time. Another prior study argued that knee scooter users are more susceptible to developing a DVT due to the knee flexion (Ciufo et al., 2019). Furthermore, this study argued that knee flexion had a direct impact on blood flow due to the reduction in blood flow observed using a knee scooter (Ciufo et al., 2019). However, these studies were limited in that it did not consider the decrease in muscle activity when both sitting and ambulating using the knee scooter. Like scooters, the HFC has a knee flexion angle that is approximately 90 degrees. However, unlike knee scooters and also crutches, the HFC does not lead to reductions in blood flow and muscle activity (Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020). This result shows that the negative effects of knee flexion can be mitigated with the HFC and that muscle activity has a greater impact on blood flow and reducing the risk of DVT than knee flexion.
A recently published study in Foot and Ankle Orthopaedics compared the blood flow and vessel dimensions following ambulation using the HFC, knee scooter and crutches for 40 participants (Bradley et al., 2022). This study found that the HFC led to a significantly lower decline in blood flow when compared to both knee scooters and crutches in popliteal blood flow and vessel dimension (Bradley et al., 2022). The results of this study corroborate the findings of other prior works which reported a significant decline in blood flow for knee scooters (Ciufo et al., 2019) with crutches leading to the greatest decrease (Reb et al., 2021). The increased blood flow observed with the HFC was attributed to the heightened muscle activity with the HFC in the suspended limb compared to both crutches and knee scooters (Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020). This study along with other research have shown that muscle activity has a major impact on blood flow (Bradley et al., 2022; Bradley & Hernandez, 2011; Reb et al., 2021).
Reductions in blood flow is a major concern during a period of immobilization which can be reduced by 61% of 8 hours of constant sitting (Kurosawa et al., 2022). When poor blood flow continues as a consequence of prolonged immobilization, it can present as deep vein thrombosis (DVT) in the lower extremities (Broderick et al., 2009; Faghri et al., 1997; McLachlin et al., 1960; Vinay et al., 2021) and cause pain venous congestion and life-threatening pulmonary embolisms (PE) (Bradley et al., 2022). Reduced blood flow can also impact oxygen delivery to the injured muscle and bone which is important for healing (Lu et al., 2013). A fixed knee angle has been believed to have a direct impact on increasing the risk of developing a deep vein thrombosis in some prior studies (Bleeker et al., 2004; Ciufo et al., 2019). In particular, one study found that the flexed knee position during knee scooter use led to a significant reduction in blood flow (Ciufo et al., 2019). However, these aforementioned negative effects of knee flexion angle can be negated with the HFC due to the increased muscle activity in the suspended limb as was shown in recently published studies (Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020). Moreover, these studies concluded that muscle activity in the suspended limb has a greater impact on blood flow than the knee flexion angle (Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020) which is in agreement to another study which argued a similar conclusion (Reb et al., 2021) thereby changing the notion that knee flexion angle alone leads to developing a deep vein thrombosis. These findings are further supported by additional research that showed that the popliteal venous blood flow when using HFC was most similar to the blood flow that would be observed during normal unassisted walking, while popliteal venous blood flow of both crutches and knee scooters were impaired.
iWALK leads to better stability compared to crutches making iWALK users less susceptible falls and improving user safety
Dr. Jason Wilken PhD, an expert in walking stability and falls in the Department of Physical Therapy and Rehabilitation Science at the University of Iowa conducted a research study that directly compared the walking stability of the HFC and crutches using the range of angular momentum as the outcome measure for both mobility devices. This study found that HFC users had a significantly lower range of angular momentum compared to crutches which suggested that HFC users are less susceptible to falls and are able to better control balance. This result corroborates other prior studies which showed that patients feel safer using the HFC (Rambani et al., 2007) and prefer the HFC over crutches (Martin et al., 2019). The result of this study is impactful as it relates to the overall safety of mobility device choices and can guide medical providers during the prescription of an assistive device for patients with lower limb injuries.
The HFC is preferred by 86% of foot and ankle patients over crutches (Martin et al., 2019). Patient satisfaction and preference can be a major determinant for compliance 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). A recent student currently under review discovered that subjects preferred the HFC compared to both crutches and knee scooters in completing activities of daily life while knee scooters presented a clear limitation in environments that contain stairs or rough terrain. One other reason why the HFC is favorable among subjects compared to crutches may be explained by the lower exertion and pain scores the HFC provides as was shown in recently published studies (Hackney et al., 2022; Martin et al., 2019).
Unlike crutches and knee scooters, the HFC 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, childcare, stairs, etc. are possible with the HFC. 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 HFC (Rambani et al., 2007) and patients had a more positive attitude to life due to the improved independence with the HFC (Barth et al., 2019). This is just one of the reasons why the HFC has a higher preference rating than crutches (Martin et al., 2019). Researchers Dr. Timmerman and Dr. Reidy at the Department of Kinesiology and Health of Miami University conducted a direct study that aimed to investigate the ability to perform activities of daily living (ADLs) using a HFC compared to crutches and knee scooters. This study found that subjects preferred the HFC over both crutches and knee scooters during ambulation, stair climbing and activities of daily living while the knee scooter led to a clear disadvantage for stair climbing and on rough terrain. Furthermore, subjects found the HFC easier to use than crutches and knee scooters.
The HFC improves patient compliance to non-weight bearing restrictions, due to prior research that shows that patients with lower limb injuries prefer a HFC 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 the HFC with the ability to do activities of daily living (Rambani et al., 2007), the HFC will lead to better compliance. A recent study showed that patients prefer the HFC over crutches and knee scooters when completing activities of daily living. Patients with lower extremity injuries have been known to be noncompliant with prescribed weight bearing restrictions while using crutches likely due to the pain, discomfort and limitations of performing activities of daily living (Chiodo et al., 2016; Gershkovich et al., 2016; Kubiak et al., 2013; Martin et al., 2019). However, lack of compliance can lead to secondary injuries and further complications such as wound breakdown, loss of fracture fixation or hardware failure (Gershkovich et al., 2016).
Research proves that the HFC 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 et al., 2021; Dewar & Martin, 2020). 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 as was shown in various prior studies (Clark et al., 2004; Dewar et al., 2021; 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 HFC compared to crutches has a direct impact on decreasing muscle atrophy, increasing blood flow, reducing the risk of deep vein thrombosis (DVT) and enhancing healing (Bradley et al., 2022; Broderick et al., 2009; Dewar et al., 2021; Dewar & Martin, 2020; Faghri et al., 1997; Rasouli & Reed, 2020; Vinay et al., 2021). Each of these benefits of the heightened muscle activation using the HFC are supported with direct and associated studies in the following sections.
The heightened recruitment of the muscles in the non-weight bearing leg when using the HFC compared to crutches decreases the level of disuse muscle atrophy (Altinkaynak, 2022; Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020). Prior research shows that the degree a muscle will atrophy is dependent on the activity of the muscle (Clark, 2009; MacLennan et al., 2020; Magill et al., 2019; Sanders et al., 2018). 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 (Magill et al., 2019). Because the HFC fixes the knee angle at 90° flexion which lengthens the muscle, 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° (Altinkaynak, 2022). 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., 2008; Hather et al., 1992; Tesch et al., 2016).
There is a large body of research that have shown that crutches are attributed to significantly higher energy costs compared to normal unassisted ambulation (Dounis et al., 1980; Holder et al., 1993; Mcbeath et al., 1974; Nielsen et al., 1990; Sankarankutty et al., 1979; Thys et al., 1996). Increased physiological demand has been shown to be an important factor in discontinuance and noncompliance to weight bearing restrictions with crutch use (Bateni & Maki, 2005). Therefore, mobility devices designed to assist ambulation should keep energy expenditure to a minimum while still allowing normal walking speeds and the ability to do their activities of daily living.
A recent study published in the journal of Foot and Ankle Orthopedics compared the metabolic cost of ambulation using a portable metabolic analyzer for subjects using a HFC, crutches and knee scooter. This study found that the HFC led to substrate utilization most similar to normal unassisted gait with the least amount of aerobic energy while allowing one to use both hands for activities pertaining to daily life (Hackney et al., 2022). Similar to this study, another study was designed to measure the energy expenditure with a portable indirect calorimetry system for the HFC, knee scooter and crutches this time while completing activities that simulate tasks one would complete in daily life. The results of this study suggested that the HFC was the only mobility device that resulted in energy expenditure similar to normal walking while also allowing users to complete all tasks within the ADL course. Immediately after completing the ADL course subjects were asked how difficult they found ambulating with each assistive device using a Likert scale. The results of this data showed that subjects found using the HFC significantly easier than crutches which correlates with the lower energy expenditure measured using the HFC (Hackney et al., 2022) as well as the lower exertion reported for HFC user in other prior studies (Bhambani & Clarkson, 1989; Hackney et al., 2022; Martin et al., 2019).
Although crutches are the most prescribed assistive device (Martin et al., 2019; Rambani et al., 2007), prolonged use of crutches have been shown to lead to various secondary injuries (Dalton et al., 2002; Manocha et al., 2021). 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 (McFall et al., 2004; 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). Because there is no loading of the hands and upper extremity when using a HFC, secondary injuries have not been reported with the HFC. Secondary injuries also occur with knee scooters due to the increased risk of falling (Rahman et al., 2020; Yeoh et al., 2017). Because the HFC leads to better stability, HFC users are less susceptible to fall related injuries.
Reduces the structural plastic changes in gray matter and white matter after a period of non-weight bearing
It is well accepted that limb immobilization effects human brain plasticity (Langer et al., 2012). In particular, it was shown that the cortical thickness (gray matter) of the sensorimotor cortex and fractional anisotropy (white matter) decreased after a period of immobilization which are both responsible for processing somatosensory information and impact motor movement (Langer et al., 2012). Because the HFC is the only mobility device that leads to muscle activity in the non-weight bearing limb consistent with normal walking when compared to crutches and knee scooters (Dewar et al., 2021; Dewar & Martin, 2020), the reorganization of the sensorimotor system as well as the overall effect of remaining non-weight bearing for prolonged periods on human brain plasticity is minimized with the HFC when compared to crutches and knee scooters.
A randomized control trial conducted using 80 patients showed that patients were discharged significantly faster after using a HFC compared with not using the HFC (Rambani et al., 2007). Reductions in muscle atrophy and improvement in blood flow when using a HFC impacts the total recovery time for lower limb injuries with quicker rehabilitation, faster healing and less cases of developing a deep vein thrombosis and pulmonary embolism (Bradley et al., 2022; Dewar et al., 2021; Dewar & Martin, 2020). The increased muscle oxygenation saturation using the HFC via improved blood flow also enhances healing (Lu et al., 2013). Crutches cause reductions in cross-sectional area of the quadriceps femoris muscle of about 0.4% per day (Clark et al., 2004). Because the HFC reduces muscle atrophy, the HFC leads to faster therapeutic gains. Moreover, secondary injuries as a result of using crutches are nonexistent when using a HFC in addition to better stability compared to crutches which all contribute to reducing the recovery times of lower limb injuries.
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Adam P. Bradley, MS, Alexis S. Roehl, Ryan McGrath, PhD, Joseph Smith, PhD, and Kyle J. Hackney, PhD
Summary: The iWALK unlike knee scooters and crutches leads to blood flow most similar to normal unassisted walking. This increase in blood flow for the lower extremities while using the iWALK reduces the risk of blood clots.
“Participants experienced an increase in popliteal arterial flow from baseline following both walking and HFC, whereas knee scooters and crutches resulted in a decrease in flow compared to walking…Deep Vein Thrombosis (DVT) is a concern with prolonged knee flexion and is associated with decreased popliteal venous flow and stasis …Despite having a flexed knee, venous flow following HFC was not different than walking. The effect of knee flexion in HFC was likely mitigated by its unique ambulation similar to walking gait, given that muscular activity is a major determinant of popliteal venous flow… Clinicians aiming to prevent stasis may consider HFC as a promising ambulation device option during period of unloading.”
Kyle J. Hackney, PhD, Adam P. Bradley, MS, Alexis S. Roehl, Ryan McGrath, PhD, and Joseph Smith, PhD
Summary: The energy cost of ambulation using the iWALK is lower compared to crutches. Moreover, the exertion and pain scores are lower with the iWALK than crutches.
“There were significant differences in substrate utilization as evidenced by average respiratory exchange ratio (RER)…There were no differences in RER with the hands-free crutch compared to walking (P=.350). Average RER during crutches was also significantly greater than HFC (P<.001)… Average RER for knee scooters was significantly greater the hands free crutch (P<.001)…Differences in aerobic energy expenditure and comfort during ambulation is critical for safety and ease of use while in the non-weight bearing recovery period. ”
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.”
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.”
Cuyler Dewar, MS, Terry L. Grindstaff, PhD, PT, Brooke Farmer, MS, ATC, Morgan Sainsbury, MS, Sam Gay, BS, Weston Kroes, BS and Kevin D. Martin, DO, FAAOS, FAANA
Summary: The hands-free crutch leads to increased muscle activity and recruitment consistent with normal walking when compared with a knee scooter. The hands-free crutch being the mobility device that is closest to normal walking in terms of muscle activity has various clinical benefits in the recovery of non-weight bearing lower limb injuries such as decreasing muscle atrophy, improving blood flow, reducing the risk of blood clots and enhancing healing. Moreover, the increased muscle activity using the hands-free crutch may reduce changes in brain plasticity.
“The rectus femoris, lateral gastrocnemius and gluteus maximus showed increased peak electromyographic (EMG) activity percentage, and the lateral gastrocnemius showed increased mean muscle activity while using the hands-free single crutch (HFSC) compared with the knee scooter…The heightened intensity and recruitment of these muscles while using the HFSC could potentially translate to decreased levels of muscle atrophy and increased blood leading to heightened venous return during nonweight-bearing recovery. Increased muscle activation has been shown to lead to increased muscle retention and mass…By maintaining in-phase cyclic muscle activation, we have established these neuro-motor pathways remain active regardless of immobilization and weightbearing status while using an HFSC.”
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.”
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 “iWALK Crutch” 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.”
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.”
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.”
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.”
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.”
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.”
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.”
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.”
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.”
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.”
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….”
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.”
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.”
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.”
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%).”
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.”