Muscle specific declines in oxygen saturation during acute ambulation with hands-free and conventional mobility devices.

Disuse is associated with reduced muscle oxygen saturation (SmO2). Improving oxygen delivery to tissues is important for healing, preventing muscle atrophy, and reducing the risk of deep vein thrombosis. Mobility devices are used during disuse periods to ambulate and protect the injured limb. This study examined SmO2 in walking and ambulation with various mobility devices. Thirty-eight participants randomly completed four, ten-minute trials which included: (1) walking, (2) medical kneeling scooter (MKS), (3) hands-free crutch (HFC), and (4) axillary crutch (AC). During each trial, near infrared spectroscopy sensors were placed on the vastus lateralis (VL), biceps femoris (BF), and lateral gastrocnemius (LG) of the right limb. Compared to walking, all mobility devices showed a decline in SmO2 in the VL of ∼10% (mean ± SD; 75% ± 12%-65% ± 17%, P < 0.05). In the BF, SmO2 declined ∼9% in AC compared to walking (76% ± 12%-67% ± 17%, P = 0.025). In the LG, SmO2 declined in AC (64% ± 16%) compared to MKS (70% ± 15%, P = 0.005). There were no differences in LG SmO2 compared to walking (69% ± 13%) in MKS (P > 0.05) or HFC (65% ± 15%, P > 0.05). In young, healthy volunteers, the use of mobility devices altered muscle oxygenation in several muscles. AC reduced muscle oxygenation in the VL, BF, and LG; while MKS and HFC maintained BF and LG muscle oxygenation at a level consistent with ambulatory walking.

Energy Expenditure and Substrate Utilization with Hands-Free Crutches Compared to Conventional Lower-Extremity Injury Mobility Devices.

Background: A Hands-Free crutch (HFC) is a relatively new device that can be used during the nonweightbearing period to increase mobility. The primary aim of this investigation was to examine aerobic oxygen consumption (V.o2) and substrate utilization with HFC compared to conventional ambulation devices as well as normal ambulation. A secondary purpose was to quantify perceived exertion, pain, and performance during each ambulation condition. Methods: Forty participants completed 4 separate 10-minute ambulation conditions around a rectangular course. The order of the ambulation conditions was randomized and consisted of (1) walking, (2) medical knee scooter (MKS), (3) HFC, and (4) axillary crutch (AC). Indirect calorimetry was used to determine V.o2 and the respiratory exchange ratio (RER), an indicator of substrate utilization. Perceived exertion and pain were also assessed using questionnaires. Results: All mobility devices significantly elevated V.o2 (+35%) compared to walking (13.14 ± 1.70 mL/kg/min; P < .001). AC had significantly greater V.o2 requirements (20.26 ± 2.62 mL/kg/min) compared to both the MKS (15.28 ± 2.29 mL/kg/min; P < .001) and HFC (15.88 ± 2.03 mL/kg/min; P < .001). There was no difference in average V.o2 between MKS and HFC (P = .368). Compared to walking (0.78 ± 0.43), RER was significantly elevated in MKS (0.81 ± 0.05, P < .001) and AC (0.84 ± 0.06, P < .001), but not in HFC (0.79 ± 0.04, P = .350). RPE and pain were elevated in all ambulatory conditions (all P values <.001). Pain was significantly greater in AC compared with MKS (P < .001) and HFC (P < .001). Conclusion: HFC and MKS share similar V.o2 requirements over a 10-minute ambulation interval and are below those needed in AC. Substrate utilization in HFC was similar to regular walking with a greater reliance on lipid utilization for energy as evidenced by a lower RER. Exertion and pain scores were the most tolerable in HFC and MKS. Level of Evidence: Level II, prospective comparative study.

Assessing Stability of Crutch Users by Non-Contact Methods.

Enhancing gait stability in people who use crutches is paramount for their health. With the significant difference in gait compared to users who do not require an assistive device, the use of standard gait analysis tools to measure movement for temporary crush users and physically disabled people proves to be more challenging. In this paper, a novel approach based on video analysis is proposed as non-contact low-cost solution to the more expensive alternative with the data collected from processed videos, two values are calculated: the Signal to Noise Ratio (SNR) of acceleration, and the Signal to Noise Ratio of the jerk (time derivative of acceleration), to assess the user's stability while they walk with crutches. The adopted methodology has been tested on a total of 10 participants. Five are temporary users of assistive devices with one being a long-term user and the other four novice users, and five are disabled participants who use those assistive devices permanently. Preliminary results show differences between novice users, long-term users, and physically disabled users. The approach is promising and could improve the assessment of crutch user stability, allowing for the correction of gait for individuals while using an inexpensive non-contact setup and preventing unnecessary falls.

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

BACKGROUND: In order to maintain nonweightbearing restrictions of the lower extremity, an assistive device must be utilized. Currently most devices require the restricted limb to be held in a static position while the contralateral extremity provides forward propulsion. Atrophy and disuse conditions ensue rapidly, slowing healing and prolonging recovery. A hands-free single crutch (HFSC) utilizes both lower extremities, potentially reducing atrophy. The purpose of this study was to examine the electromyographic (EMG) differences between an HFSC and standard axillary crutches (SAC). METHODS: A prospective, crossover study was performed using 21 healthy volunteers from an active duty foot and ankle clinic. Demographic data were obtained and then subjects were fitted with an HFSC and SAC. Wireless surface EMG sensors were applied to the belly of the rectus femoris (RF), vastus lateralis (VL), lateral gastrocnemius (LG), and the gluteus maximus (GM) by a board-certified orthopedic surgeon. Subjects then ambulated at a self-selected velocity for 30 m while 15 seconds of the gait cycle were recorded for each device. Mean muscle activity and the maximum voluntary isometric contraction (MVIC) were recorded. RESULTS: The RF, GM, and LG showed significantly increased levels of muscle activity while using the HFSC compared to SAC (respectively P = .05, P = .03, P = .03). The VL did not show significantly higher muscle activity while using the HFSC (P = .051). The RF, GM, and VL showed statistically significant higher MVIC percentages while using the HFSC compared with SAC (respectively P = .005, P = .005, P = .013). The LG did not show significantly higher MVIC percentage while using the HFSC (P = .076). CONCLUSION: The HFSC subjects demonstrated increased muscle recruitment and intensity while maintaining cyclic contractions consistent with bipedal gait pattern. SAC demonstrated less recruitment and intensity with an isometric pattern regardless of the phase of gait. CLINICAL RELEVANCE: Muscle atrophy following lower extremity immobilization.

Biomechanical study on axillary crutches / 医用生物力学

Axillary crutch is one of the common mobility aids, with extensive usage in the given crowd. Due to the lack of adequate theoretical support, the past design of crutches often leads to occurrence of the secondary damage, such as axillary nerve injury, wrist injury and so on. Thus, it is necessary to carry out biomechanical study on axillary crutches. In this paper, the problems related with biomechanics in axillary crutches were reviewed by inquiring and analyzing the relevant references, and discussed from the aspects of human biomechanics, ergonomics, and industrial design. Also in this paper, through man machine interface research, the mechanical analysis on crutches usage, gait analysis and ergonomics design were made to lay a solid foundation for the design and correct use of axillary crutches so as to provide some reference for the option, adaptation and assessment of axillary crutches, which would have great clinical significance.

Bilateral wrist drop complicating axillary crutches mobilization in a young adult / Mano péndula bilateral que complica la movilización con muletas axilares en un adulto joven

OBJECTIVE: Axillary crutches are simple rehabilitative devices that are globally used temporarily or permanently to assist in ambulation of patients and rarely present with complication. This report is about bilateral wrist drop incidentally noticed in a young adult patient mobilized on axillary crutches after internal fixation of a simple right tibia fracture. METHODS: The fracture was fixed by intramedullary nailing and the patient was mobilized on axillary crutches. At six weeks, patient fearfully refused to be commenced on partial weight bearing and at 12 weeks after surgery he was noticed to be totally weightbearing on the bars of the appropriately long axillary crutches and had developed bilateral wrist drop. There was radiological evidence of healing at the fracture sites. Treatment included mobilization on one elbow crutch on the left, physical therapy and nerve stimulation. RESULTS: At six weeks of physiotherapy, the power of the dorsiflexors of the wrists had recovered completely. CONCLUSION: Bilateral posterior cord palsy of brachial plexus could occur even in young healthy patients but total recovery could occur if the diagnosis and treatment are prompt. Patients should be told in unequivocal terms not to weight bear directly on axillary bars.

OBJETIVO: Las muletas axilares son simples dispositivos de rehabilitación que se utilizan en todo el mundo de manera temporal o permanentemente para ayudar a caminar a los pacientes, y raramente presentan complicación. Este trabajo trata de la mano péndula o mano caída, observada incidentalmente en un paciente adulto joven movilizado en muletas axilares, después de la fijación interna de una fractura simple de la tibia derecha. MÉTODOS: La fractura fue fijada mediante clavo intramedular, y el paciente fue movilizado con muletas axilares. A las seis semanas, el paciente se negó temeroso a la iniciación para sostener parcialmente todo su peso con ayuda de muletas, y a las 12 semanas después de la cirugía, se le vio sostener todo su peso sobre las barras de las muletas axilares de longitud adecuada, y había desarrollado mano péndula bilateral. Había evidencia radiológica de curación en los sitios de fractura. El tratamiento incluyó la movilización con una muleta de codo a la izquierda, terapia física, y estimulación nerviosa. RESULTADOS: A las seis semanas de fisioterapia, la capacidad de los dorsiflexores de las muñecas se había recuperado completamente. CONCLUSIÓN: La parálisis del fascículo posterior bilateral del plexo braquial podría ocurrir incluso en pacientes jóvenes sanos, pero la recuperación total podría ocurrir si el diagnóstico y el tratamiento se hacen a tiempo. A los pacientes se les debe decir en términos inequívocos que no deben soportar todo su peso directamente en las barras axilares.