Frequency and Circumstances of Falls Reported by Ambulatory Unilateral Lower Limb Prosthesis Users: A Secondary Analysis

Abstract

Background: More than 50% of lower limb prosthesis (LLP) users report falling at least once a year, placing them at high risk for adverse health outcomes such as decreased mobility and diminished quality of life. Efforts to decrease falls in LLP users have traditionally focused on developing clinical tests to assess fall risk, designing prosthetic components to improve patient safety, and identifying risk factors to recognize potential fallers. Little attention has been directed toward recording, reporting, and characterizing the circumstances of falls in LLP users. Identifying the most common types of falls could help guide and prioritize clinical and research needs.

Objective: To characterize the frequency and circumstances of falls reported by unilateral LLP users.

Design: Secondary analysis of data from 2 cross-sectional studies.

Setting: Outpatient clinic and research laboratory.

Participants: Ambulatory unilateral transtibial and transfemoral LLP users (N = 66).

Intervention: None.

Outcome: A fall-type classification framework was developed based on biomechanical theory and published falls terminology. Self-reported falls and accompanying narrative descriptions of LLP users' falls in the previous 12 months were analyzed with the framework. Frequencies, estimated proportions, and estimated counts were compared across fall circumstances using 95% confidence intervals.

Results: Thirty-eight participants (57.6%) reported 90 falls during the previous year. All reported falls were successfully categorized using the proposed framework. Most falls occurred from disruptions to the base of support, intrinsic destabilizing factors, and a diverse set of fall patterns. Walking on level terrain was the most common activity at the time of a fall.

Conclusion: This secondary analysis showed that falls remain frequent in ambulatory LLP users and that clinicians and researchers might wish to prioritize falls owing to disruptions of the base of support that occur while walking. Additional research with a larger sample is required to confirm and expand these results.

Level of evidence: III.

Figure 1.

Fall type classification framework. The proposed framework is a 3-level hierarchical system that characterizes falls based upon the location of the destabilizing force (level one), the source of the destabilizing force (level two), and the fall pattern (level three).

Figure 2.

Number and frequency of fall types among lower limb prosthesis users as categorized by the classification framework. The base-of-support was the most common location of a destabilizing force resulting in a fall (level one). Intrinsic factors were the most common source of a destabilizing force resulting in a fall (level two). Slip, trips, and prosthetic factors accounted for nearly three-quarters of the reported fall patterns (level three).

Figure 3.

Number and frequency of falls reported by lower limb prosthesis users based upon the activity at the time of a fall. Walking was the most commonly reported activity at the time of a fall. More falls occurred while walking on level versus uneven terrain.