The Amputee Mobility Predictor: An instrument to assess determinants of the lower-limb amputee's ability to ambulate

Abstract

Objectives: To describe the development of the Amputee Mobility Predictor© (AMP) instrument designed to measure ambulatory potential of lower-limb amputees with (AMPPRO) and without (AMPnoPRO) the use of a prosthesis, and to test its reliability and validity. Design: Measurement study using known groups method and concurrence with existing measures. Setting: Academic medical center. Participants: A convenience sample of 191 lower-limb amputee subjects who had completed prosthetic training, 24 in the reliability study (mean age Ϯ standard deviation, 68.3Ϯ17.9y, range, 28-99y) and 167 in the validity study (mean age, 54.8Ϯ18.6y; range, 18-100y). Interventions: Not applicable. Main Outcome Measures: Intra-and interrater reliability; construct validy by known groups method; concurrent validity by comparisons with 6-minute walk test, Comorbidity Index, age, and time since amputation; predictive validity by comparison with 6-minute walk test after controlling for other factors. Results: Interrater reliability was .99 for subjects tested with and without their prosthesis; intrarater reliability was .96 and .97. Both the AMPnoPRO (PϽ.0001) and the AMPPRO scores (PϽ.0001) distinguished among the 4 Medicare functional classification levels. The AMP correlated strongly with 6-minute walk scores (AMPnoPRO rϭ.69, PϽ.

Benefits of microprocessor-controlled prosthetic knees to limited community ambulators: Systematic review

“…In all studies, only the everyday clinical practice of subjective judgment of the prosthetist and/or physical therapist was used to assign the subjects to a certain MFCL. No study used a reproducible method such as the AMP [69] or the walking speed in timed walk tests [69,97] to support this determination. One study assessed the AMP but did not use it to determine the mobility grade [21].…”

“…The individual AMP values ranged from 34 to 41, with most values exceeding 36, the currently recommended upper cutoff for MFCL-2. However, in the original publication of Gailey et al, the mean and standard deviation of AMP values across the MFCL-2 patient sample was 34.65 ± 6.49, with a range of 19 to 41 [69]. The other studies assessed the fastest possible walking speed in timed walk tests [31,[98][99] or during motion analysis [100][101].…”

“…b. Performance-based function and mobility: MFCL classification if determined with all prosthetic interventions and validated outcome measures that objectively assess the physical abilities of subjects with lower-limb amputation, such as the Amputee Mobility Predictor (AMP) with and without prosthesis [69], timed walk tests on level ground [70][71] and uneven terrain [31], the Assessment of Daily Activity Performance in Transfemoral Amputees test for assessing performance in ADLs [72], divided attention tests while walking [34], performance and gait characteristics in slope and stair negotiation such as the Hill and Stair Assessment Indices [34], motion analysis [24,35,[73][74], or the Montreal Rehabilitation Performance Profile [31,75]. c. Perceived function and satisfaction: Validated selfreported outcome measures such as the PEQ [76][77], Orthotic and Prosthetic Users' Survey [78], LCI [79][80], Amputee Activity Score [81], Functional Measure for Amputees [82][83], Houghton Scale [82,[84][85], Prosthetic Profile of the Amputee [82], Orthotics and Prosthetics National Outcomes Tool [82,86], Special Interest Group in Amputation Medicine score [87], and Trinity Amputation and Prosthesis Experience Scales [88][89].…”

“…Because the variability of patient characteristics within the MFCL-2 mobility grade is broad, an attempt was made to stratify the subjects based on two well-validated objective measures of the overall physical capabilities, the AMP [69] and the walking speed in timed walk tests [70][71]97] on the NMPK, because such stratification might possibly allow for relating differing results to different levels of physical capabilities and thus help guide appropriate component selection.…”

The effects of prosthetic ankle stiffness on stability of gait in people with transtibial amputation

“…The common standard of practice in rehabilitation for people with amputation is to optimally match patients with prosthetic components to maximize mobility outcomes, so the outcomes from this study provide valuable insight into our understanding of prostheses effects on user performance [40]. The prescription process will be further enhanced as techniques are improved for classifying patients based on their rehabilitation potential and mobility and classifying prostheses based on their amputee-independent mechanical properties [41,[54][55][56].…”