Effects of adjustable‐volume transfemoral prosthetic sockets on balance and falls: A randomized clinical trial

BACKGROUND: Adjustable-volume prosthetic sockets have been developed to allow users to accommodate volume fluctuations throughout the day. Improvement in socket fit is thought to enhance the connection between the user's residual limb and prosthesis and may therefore improve postural control and balance. However, no studies have assessed balance-related outcomes or falls between different adjustable socket designs. OBJECTIVE: To compare balance-related outcomes for people with transfemoral limb loss using three styles of adjustable-volume sockets and a laminated socket. DESIGN: Randomized clinical trial. SETTING: Prosthetics clinics and research laboratories. PARTICIPANTS: A convenience sample of 29 individuals with unilateral transfemoral amputation were recruited, of whom 23 completed testing in at least one adjustable-volume socket and were included. INTERVENTION: Participants completed four 4-week trials with each of three adjustable-volume prosthetic sockets and a laminated socket, in random order. Adjustable-volume sockets included Infinite (LIM Innovations, San Francisco, CA, USA), CJ (CJ Sockets Technologies, Beverly, MA, USA), and Quatro (Quorum, Windsor, CO, USA). MAIN OUTCOME MEASURES: The primary outcomes were self-reported balance, number of falls and stumbles, and balance confidence. Secondary outcomes included the Narrow Beam Walk Test (NBWT) and Timed Up and Go Test (TUG). Surveys were conducted after at least 3 weeks of use of each socket, and functional measures were collected after 4 weeks. RESULTS: There were no main effects of socket type on self-reported balance (p = .316), balance confidence (p = .963), NBWT (p = .159), or TUG (p = .581). Eighteen participants (78%) reported falling or stumbling at least once in a 3-week period in at least one socket condition. There were no differences in the proportion of fallers (1+ falls) or stumblers (1+ stumbles) between the laminated condition and any adjustable-socket condition (p > .210). CONCLUSIONS: The adjustable-volume prosthetic sockets tested demonstrated comparable performance to laminated sockets for balance and fall-related outcomes. The high number of falls and stumbles reported suggests that future studies should focus on balance and falls training, acknowledging that changes to the socket may be insufficient to address this issue.