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.

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

BACKGROUND: Weightbearing restrictions following foot and ankle surgery require the use of appropriate assistive devices for nonweightbearing ambulation during the recovery period. Selecting an appropriate assistive device that safely optimizes mobility and participation in daily activities is important to patient compliance and satisfaction. The purpose of this study was to compare physiologic demand, perceived exertion, and patient preference between a hands-free single crutch (HFSC) and standard axillary crutches (SACs) in foot and ankle patients. METHODS: Using 44 preoperative orthopedic foot and ankle patients who had a mean age of 32 (19-51) years, a prospective, randomized, crossover study was performed. The sample consisted of 35 males and 9 females. The mean body mass index (BMI) was 26 (19-36), the mean height was 1.7 m, and the mean weight was 82 kg. Patient data and preactivity heart rate were recorded for all patients, who were then randomized to either an HFSC or SACs. Each patient was randomly assigned to the device they would utilize first using a random number generator. They then crossed over to the other device after vitals returned to within 10% of their baseline heart rate. Every subject completed a 6-minute walk test (6MWT) using both assistive devices in a crossover manner. Immediately following each 6MWT, postactivity heart rate, self-selected walking velocity (SSWV), perceived exertion using the OMNI Rating of Perceived Exertion (OMNI-RPE), and perceived dyspnea using the Modified Borg Dyspnea Scale were obtained. After completing both 6MWTs, patients were asked which assistive device they preferred the most. RESULTS: The HFSC was preferred by 86% of patients. Significantly lower dyspnea scores (2.8 vs 5.3; P < .001), fatigue scores (2.4 vs 5.5; P < .001), preactivity and postactivity change in heart rate (28 vs 46 bpm; P < .001), and mean postactivity heart rate (107 vs 122 bpm; P < .001) were found using the HFSC compared with the SACs. The SAC group trended toward a higher SSWV (0.8 vs 0.77 m/s; P = .08). Those with a BMI greater than 25 also preferred iWALK over SACs (P < .05). Neither group had any falls. Sixty-eight percent of patients complained of axillary/hand pain with the SACs, while 7% complained of proximal leg strap discomfort with the HFSC. CONCLUSION: The results of the current study in our relatively healthy cohort found that foot and ankle patients who were nonweightbearing preferred the HFSC over SACs. They experienced less physiologic demand as well as discomfort and perceived less exertion when using the HFSC compared with SACs. LEVEL OF EVIDENCE: Level II, prospective comparative study.

Prosthetic options available for the diabetic lower limb amputee.

Although the rate of lower limb amputation in patients with diabetes is decreasing, amputation still remains a major complication of diabetes. Prosthetics have been long used to help amputees ambulate. The last decade has seen many advances in prostheses with the enhanced understanding of the mechanics of ambulation and improved use of technology. This review describes the different types of prosthetic options available for below knee, ankle, and foot amputees, emphasizing the latest advances in prosthetic design.