Residual and sound limb hip strength distinguish between sedentary and nonsedentary adults with transtibial amputation

Abstract

Following a transtibial amputation (TTA), physical activity has known benefits for health and quality of life. Adults post-TTA, however, demonstrate reduced physical activity, predisposing them to adverse health outcomes. Identifying adults at the risk of sedentarism post-TTA via commonly used, objective clinical measures may enhance clinical decisions, including prosthesis prescription. The study’s purpose was to determine whether residual and sound limb hip strength distinguishes between sedentary and nonsedentary adults post-TTA. A secondary analysis of a cross-sectional dataset (n = 44) was conducted. Participant residual and sound limb hip flexion, extension, abduction and adduction strength were assessed via handheld dynamometry. Physical activity was monitored for 7 days and participants were classified as sedentary (<5000 steps/day; n = 13) or nonsedentary (≥5000 steps/day; n = 31). Receiver operating curves revealed that residual and sound limb hip extension, abduction and adduction strength distinguished between sedentary and nonsedentary adults post-TTA (P < 0.050). Preliminary cut-points for hip strength measures to classify adults at the risk of sedentarism were determined. A hip strength composite score (0–6) estimates a 2.2× increased odds of being sedentary with each additional hip strength deficit. Post-TTA, residual and sound limb hip strength can help identify adults at risk of sedentarism to aid clinical decision making, including prosthesis prescription.

After scaling to body size hip strength of the residual limb exceeds that of the intact limb among unilateral lower limb prosthesis users

“…Direct comparisons across the literature are however limited by the substantial methodological variation across studies. Notable variations in data collection and analysis throughout the literature include testing posture (e.g., supine, sitting, or standing) and joint angle [ 5 , 21 , 23 ], testing equipment (i.e., computerized versus handheld dynamometer) [ 11 – 13 , 19 , 20 ], mode of muscle action (i.e., isometric versus isokinetic) [ 5 , 8 , 11 , 13 , 23 ], whether the prosthesis is worn [ 10 – 12 , 21 , 23 ] or removed [ 5 , 8 , 9 , 13 , 19 , 24 , 28 , 31 ] while testing the residual limb, gravity compensation, familiarization (i.e., number of trials) [ 55 ], and normalization for confounding anthropometric variables [ 22 ]. The adoption of standardized methods for data collection, processing, and reporting of strength-related outcomes in LLP users would enable the comparison and aggregation of data across studies.…”

“…Gait deviations [ 10 , 12 , 13 ], reduced walking speed and endurance [ 5 , 11 , 14 , 20 , 21 , 77 , 78 ], as well as increased metabolic cost [ 16 ] have historically been associated with weakness in the residual limb of unilateral LLP users. Several recent studies have however reported that intact limb muscle function may also play a substantial role in determining walking endurance [ 79 ] and physical activity levels [ 19 ] among unilateral LLP users. The results of these latter studies, and our discovery that once scaled to body size the intact not residual limb hip muscles appear weaker, injects uncertainty into whether walking and balance performance in unilateral LLP users is limited primarily by intact or residual limb muscle function.…”

“…Age- and gender-matched controls can be recruited to address the former [ 9 , 12 , 27 ], while the biological influence of body size (i.e., muscle mass) on muscle strength can be addressed by normalizing strength data to appropriate anthropometric variable(s) [ 28 ], ensuring unbiased comparisons between people and legs that differ in size [ 26 , 29 , 30 ]. Second, documentation of hip strength across all four major hip muscle groups, in both the residual and intact limbs, is required to characterize within and between limb patterns of hip strength among unilateral LLP users [ 11 , 13 , 19 , 31 ]. Finally, nearly half of the evidence concerning hip strength in unilateral LLP users is based on data collected almost 20 years ago [ 22 ].…”

“…Hip muscles in transfemoral prosthesis users may also serve to stabilize their residual limb within the socket [6,7] and provide a degree of control over the prosthesis [3]. Given their expansive set of responsibilities, it is perhaps not surprising that residual and intact limb hip muscle weakness [8][9][10][11][12][13] has been associated with a host of gait impairments including reduced walking speed [5,8,10,11,14], increased metabolic cost [15][16][17], decreased balance confidence [18], abnormal joint loading [8,14], as well as reduced mobility [19] and walking endurance [20,21]. Hip strength may therefore prove to be an appealing target for interventions that seek to improve walking and balance performance in LLP users.…”

Key Modifiable Factors in Community Participation Among Adults With Lower Limb Amputation

“…11 That said, physical activity after LLA is influenced by various factors. Previous research suggests, along with patient demographic (i.e., age, sex) and amputation-specific (i.e., amputation etiology, time since amputation) characteristics, 11 modifiable physiological factors, such as hip muscle strength 23 and functional mobility, 24 may play a significant role in determining physical activity. In addition, psychological factors, such as motivation and patient perceptions of their amputation and prosthesis, may influence overall physical activity after LLA.…”