Using a microprocessor knee (C-Leg) with appropriate foot transitioned individuals with dysvascular transfemoral amputations to higher performance levels: a longitudinal randomized clinical trial

Background

Individuals with transfemoral amputations who are considered to be limited community ambulators are classified as Medicare functional classification (MFCL) level K2. These individuals are usually prescribed a non-microprocessor controlled knee (NMPK) with an appropriate foot for simple walking functions. However, existing research suggests that these individuals can benefit from using a microprocessor controlled knee (MPK) and appropriate foot for their ambulation, but cannot obtain one due to insurance policy restrictions. With a steady increase in older adults with amputations due to vascular conditions, it is critical to evaluate whether advanced prostheses can provide better safety and performance capabilities to maintain and improve quality of life in individuals who are predominantly designated MFCL level K2. To decipher this we conducted a 13 month longitudinal clinical trial to determine the benefits of using a C-Leg and 1M10 foot in individuals at K2 level with transfemoral amputation due to vascular disease. This longitudinal clinical trial incorporated recommendations prescribed by the lower limb prosthesis workgroup to design a study that can add evidence to improve reimbursement policy through clinical outcomes using an MPK in K2 level individuals with transfemoral amputation who were using an NMPK for everyday use.

Methods

Ten individuals (mean age: 63 ± 9 years) with unilateral transfemoral amputation due to vascular conditions designated as MFCL K2 participated in this longitudinal crossover randomized clinical trial. Baseline outcomes were collected with their current prosthesis. Participants were then randomized to one of two groups, either an intervention with the MPK with a standardized 1M10 foot or their predicate NMPK with a standardized 1M10 foot. On completion of the first intervention, participants crossed over to the next group to complete the study. Each intervention lasted for 6 months (3 months of acclimation and 3 months of take-home trial to monitor home use). At the end of each intervention, clinical outcomes and self-reported outcomes were collected to compare with their baseline performance. A generalized linear model ANOVA was used to compare the performance of each intervention with respect to their own baseline.

Results

Statistically significant and clinically meaningful improvements were observed in gait performance, safety, and participant-reported measures when using the MPK C-Leg + 1M10 foot. Most participants were able to achieve higher clinical scores in gait speed, balance, self-reported mobility, and fall safety, while using the MPK + 1M10 combination. The improvement in scores were within range of scores achieved by individuals with K3 functional level as reported in previous studies.

Conclusions

Individuals with transfemoral amputation from dysvascular conditions designated MFCL level K2 benefited from using an MPK + appropriate foot. The inference and evidence from this longitudinal clinical trial will add to the knowledgebase related to reimbursement policy-making.

Trial registration This study is registered on clinical trials.gov with the study title “Functional outcomes in dysvascular transfemoral amputees” and the associated ClinicalTrials.gov Identifier: NCT01537211. The trial was retroactively registered on February 7, 2012 after the first participant was enrolled.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00879-3.

Outcomes of major lower extremity amputations n dysvascular patients: Room for improvement

OBJECTIVES

Dysvascular patients account for >80% of major amputations in the US. We sought to determine if early mobilization and discharge disposition decreased post-operative hospital length of stay (PO-LOS) and expedited independent ambulation.

METHODS

A retrospective review of dysvascular patients undergoing major amputations was performed. Primary outcomes included PO-LOS, discharge disposition, and days to ambulation.

RESULTS

130 patients were included. Patients evaluated by Physical Therapy (PT) within 1 day of formal amputation had decreased PO-LOS (5.6 vs 6.5 days, p = 0.029). Patients discharged to rehab had a shorter PO-LOS (4 days) than those discharged to SNF or home (8 and 5 days, respectively; p = 0.008). Time to ambulation was shorter for patients discharged to rehab (109 days vs home = 153 days; SNF = 175 days; p = 0.033).

CONCLUSION

Modifiable factors, including early PT and rehab placement, decreased PO-LOS and expedited time to ambulation. A need exists for a standardized multidisciplinary team approach to improve outcomes.

Using Perforated Liners to Combat the Detrimental Effects of Excessive Sweating in Lower Limb Prosthesis Users

BACKGROUND

Excessive sweating of the residual limb has a substantial effect on the daily activities of people with lower limb amputation. Prosthetic liners offer protection and comfort to sensitive areas but often exacerbate perspiration. They act as insulators, trapping sweat on the skin's surface to the detriment of skin health. Recently, liners with perforations have been developed, allowing the moisture to escape. The goal of this study was to assess the impact of such liners.

METHODS

A sample group of 13 patients with unilateral transtibial amputation, who wore a perforated liner (PL) as part of their current prescription, was compared to 20 control patients who wore non-perforated liners (NPL). During their routine appointments, they completed a survey of scientifically validated outcome measures relating to their limb health, pain and the impact on daily life over a 12-month period.

RESULTS

Patients using the PL had healthier residual limbs, reporting higher scores on questions relating to limb health, experiencing fewer skin issues (p<0.001) and estimating a 61.8% lower rating in perceived sweat (p=0.004). Perhaps consequentially, there was a lower incidence of residual (p=0.012) and phantom (p=0.001) limb pain when compared to the control group. The prevalence of individual issues affecting the residual limbs of PL users was also lower. Of the issues that remained, only 23% were attributed to sweating in PL users, compared to 49% for the NPL group (p=0.066). PL users missed fewer days of work in the year (2.4 vs 11.6, p=0.267) and were also limited on fewer days (1.4 vs 75.4, p=0.009).

CONCLUSION

The use of perforated liners shows much promise within prosthetic care, significantly improving the health of the residual limb. The observed effects on perceived sweat reduction, residual skin health, pain levels and patient limitation suggest that perforated liners are highly beneficial to patients.

Risks and Risk Factors for Ipsilateral Re-Amputation in the First Year Following First Major Unilateral Dysvascular Amputation

OBJECTIVE

To identify timing, incidence, and risk factors for ipsilateral re-amputation within 12 months of first dysvascular amputation and to determine specific subgroups of patients at each amputation level that are at increased risk.

METHODS

A retrospective cohort study evaluating 7187 patients with first unilateral transmetatarsal (TM), transtibial (TT), or transfemoral (TF) amputation secondary to diabetes and/or peripheral artery disease (PAD) were identified in the VA Surgical Quality Improvement Program database between 2004 and 2014. Re-amputation was defined as any subsequent ipsilateral soft tissue/bony revision or amputation to a higher level. Twenty-three potential pre-operative risk factors (and nine potential interactions) were identified. A backward stepwise Cox regression was used to identify risk factors. Incidence rates and hazard ratios (HR) with 95% confidence intervals (CI) were computed.

RESULTS

The median time to highest level of re-amputation in the first year was 33 (interquartile range, 13-73) days. Risk of requiring at least one re-amputation was 41% (TM), 25% (TT), and 9% (TF). Risk factors associated with requiring re-amputation included chronic obstructive pulmonary disease, elevated white blood cell count, abnormal ankle brachial index (ABI), history of revascularisation, and alcohol misuse. TM patients who had diabetes only (HR 1.9; 95% CI 1.4-2.5), diabetes with an abnormal ankle brachial index (ABI) score (HR 2.4; 95% CI 1.8-3.2), and kidney failure (HR 1.7; 95% CI 1.3-2.1) were at the greatest risk of re-amputation. TT amputees who were smokers were also at an increased risk (HR 1.4; 95% CI 1.2-1.6).

CONCLUSION

This research identified important risk factors for failure of primary healing and need for re-amputation at the TM and TT level. If considering a TM amputation, caution should be exercised in patients with diabetes, in particular those with an abnormal ABI and/or renal failure. At the TT level, caution should be exercised in those who smoke.

Comorbidity and Non-prosthetic Inpatient Rehabilitation Outcomes After Dysvascular Lower Extremity Amputation

BACKGROUND

Dysvascular amputations arising from peripheral vascular disease and/or diabetes are common. Patients who undergo amputation often have additional comorbidities that may impact their recovery after surgery. Many individuals undergo post-operative inpatient rehabilitation to improve their non-prosthetic functional independence. Thus far, our characterization of comorbidity in this population and how it is associated with non-prosthetic inpatient functional recovery remains relatively unexplored.

OBJECTIVE

The objective of this study was to describe comorbidities, using the Charlson Comorbidity Index (CCI), and to examine associations between comorbidity and functional outcomes in a cohort of patients with dysvascular limb loss undergoing non-prosthetic inpatient rehabilitation.

METHODOLOGY

A retrospective cohort design was used to analyze a group of 143 patients with unilateral, dysvascular limb loss who were admitted to inpatient rehabilitation. Age, sex, amputation level, amputation side, length of stay (LOS), time since surgery, Functional Independence Measure (FIM) scores (Total and Motor at admission and discharge), and CCI scores were collected.

FINDINGS

The data showed that neither total or specific comorbidities were associated with functional outcomes or LOS in this cohort and rehabilitation model. Multivariate analysis demonstrated an inverse relationship with age and FIM scores, where increased age was associated with lower Total and Motor FIM at admission and discharge. Comorbidities were not associated with functional outcomes. Dementia was negatively associated with FIM scores, however this requires more study given the low number of patients with dementia in this cohort.

CONCLUSION

These data suggest that regardless of burden of comorbidity or specific comorbidities that patients with dysvascular limb loss may derive similar functional benefit from post-operative non-prosthetic inpatient rehabilitation.

A Depiction of Rehabilitation Patients 65 Years and Younger With Dysvascular Lower Extremity Amputation

BACKGROUND

The majority of lower limb amputations (LLA) in Canada are dysvascular due to complications of diabetes and/or vascular disease. Traditionally dysvascular amputations have occurred in the elderly. With younger onset of adult diabetes, amputations are now occurring in non-geriatric populations. An understanding of younger patients with dysvascular LLA is needed to determine their risk factors, and unique health and psychosocial challenges.

OBJECTIVES

To obtain a depiction of the key demographic and impairment characteristics of adults 65 years and younger with dysvascular LLA undergoing inpatient rehabilitation.

METHODOLOGY

A retrospective chart review was completed on inpatient adult amputation rehabilitation patients over a five year period. Data extracted included socio-demographics, Functional Independence Measure (FIM) scores, comorbidities, and discharge outcomes.

FINDINGS

One hundred and forty-three patients who were 65 years and younger were included, which represented almost a quarter of all admissions. Most patients were male (79%) with an average age of 55 years old (SD=8). The majority (72%) were unemployed. The mean number of co-morbidities was 5.2 (SD=8.2). Individuals discharged home (n=122) had higher (p<0.05) FIM scores than those readmitted to acute care or discharged to long-term care (n=20).

CONCLUSIONS

Similar to the literature on older dysvascular LLA patients, our study found high rates of disability and co-morbidities in younger patients with dysvascular LLA, which might impact their ability to work. Given these challenges, better amputation prevention strategies and targeted rehabilitation programming for this population are needed.

Epidemiology of limb loss

In 2005, 1.6 million people were estimated to be living with limb loss; by 2050, the rate is expected to double to 3.6 million in the United States. Past data have shown that the rates of dysvascular amputations were increasing. However, recent studies looking at single diseases of peripheral arterial disease and diabetes mellitus show amputations related to these conditions are now decreasing. The authors think that it may not be a single disease process but rather the cumulative illness burden that is leading to amputations. In addition to cause, age, gender, and race continue to play a role in limb loss.