The effect of total ankle arthroplasty on mechanical energy exchange.

Total ankle arthroplasty (TAA) is a common surgical solution for patients with debilitating arthritis of the ankle. Prior to surgery patients experience high levels of pain and fatigue and low mechanical energy recovery. It is not known if TAA restores healthy levels of mechanical energy recovery in this patient population. This study was designed to determine whether mechanical energy recovery was restored following TAA. Ground reaction forces during self-selected speed walking were collected from patients with symptomatic, unilateral ankle arthritis (N = 29) before and one and two years after primary, unilateral TAA. The exchange of potential (PE) and kinetic (KE) energy was examined, and direction of change (%congruity) and energy exchange (%recovery) between the two curves was calculated, with those subjects with low congruity experiencing high energy recovery. Linear regressions were used to examine the impact of walking speed, congruity, and amplitude of the center of mass (COM) displacement on %recovery, while ANOVA and ANCOVA models were used to compare energy recovery and congruity across the three time points. Gender, BMI, and age at surgery had no effect in this study. TAA improved walking speed (p = 0.001), increased energy recovery (p = 0.020), and decreased congruity (p = 0.002), and these levels were maintained over at least two years. Differences in congruity were independent of walking speed. In some patients, especially those who are severely debilitated by ankle arthritis, TAA is effective in restoring mechanical energy recovery to levels similar to an asymptomatic population of a similar age recorded by other studies.

Health Care Utilization After Major Limb Loss in Adults (18-64) Receiving Care in the Military Health System From 2001 to 2017.

OBJECTIVE: To characterize and quantify health care utilization of Military Health System beneficiaries with major limb loss. DESIGN: Retrospective cohort study. SETTING: Military treatment facilities and civilian health care facilities that accept TRICARE insurance across the United States. PARTICIPANTS: A total 5950 adult Military Health System beneficiaries with major limb amputation(s) acquired between January 1st, 2001, and September 30th, 2017 (N=5950). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: This study was an exploratory analysis designed to identify common care specialties, services, and devices utilized by Military Health System beneficiaries with major limb loss. RESULTS: Most beneficiaries were retirees/dependents (63.3%), men (73.1%), and had a single amputation (88.7%), with a mean age of 42 years. Differences between beneficiary categories were found. Active-duty service members used a larger proportion of inpatient, emergency, primary care, physical and occupational therapy, prosthetics and orthotics, physical medicine and rehabilitation, and psychiatry services than retirees/dependents. Most common procedures included "revision of amputation stump" (57.2%) for the active-duty population and "other amputation below knee" (24.3%) for the retirees/dependents. CONCLUSIONS: These findings highlight the rehabilitation trajectories of beneficiaries receiving treatment for major limb loss in military and civilian care settings. The results could inform staffing decisions and training programs for military treatment facilities, American trauma centers, rehabilitation hospitals, and outpatient health care providers treating individuals with amputation.

Diagnostic ultrasound of the residual limb: A narrative review.

Globally, 57.7 million people lived with traumatic limb loss in 2017, with the prevalence of amputation in the United States alone expected to reach 3.6 million by 2050. Pain is a common complication after limb loss, with up to 59% of patients experiencing residual limb pain (RLP). Although RLP is often due to a structural etiology, it is difficult to treat because the exact structure involved is frequently not apparent on history and physical examination alone. This narrative review aims to summarize the available literature on diagnostic ultrasound of the residual limb and examine the utility of ultrasound in identifying specific pathology. A total of 31 peer-reviewed manuscripts published between 1989 and 2021 were included, grouped by pathology. Although ultrasound presents a promising and cost-effective approach to identifying pathology within the residual limb, many gaps remain in the current knowledge, and no specific protocol for a sonographic assessment of the residual limb has ever been proposed. Future studies of diagnostic ultrasound of the residual limb should focus on replicable sonographic techniques and standardized exam protocols.

Development of a 30-Day Readmission Risk Calculator for the Inpatient Rehabilitation Setting.

OBJECTIVES: Readmission to acute care from the inpatient rehabilitation facility (IRF) setting is potentially preventable and an important target of quality improvement and cost savings. The objective of this study was to develop a risk calculator to predict 30-day all-cause readmissions from the IRF setting. DESIGN: Retrospective database analysis using the Uniform Data System for Medical Rehabilitation (UDSMR) from 2015 through 2019. SETTING AND PARTICIPANTS: In total, 956 US inpatient rehabilitation facilities and 1,849,768 IRF discharges comprising patients from 14 impairment groups. METHODS: Logistic regression models were developed to calculate risk-standardized 30-day all-cause hospital readmission rates for patients admitted to an IRF. Models for each impairment group were assessed using 12 common clinical and demographic variables and all but 4 models included various special variables. Models were assessed for discrimination (c-statistics), calibration (calibration plots), and internal validation (bootstrapping). A readmission risk scoring system was created for each impairment group population and was graphically validated. RESULTS: The mean age of the cohort was 68.7 (15.2) years, 50.7% were women, and 78.3% were Caucasian. Medicare was the primary payer for 73.1% of the study population. The final models for each impairment group included between 4 and 13 total predictor variables. Model c-statistics ranged from 0.65 to 0.70. There was good calibration represented for most models up to a readmission risk of 30%. Internal validation of the models using bootstrap samples revealed little bias. Point systems for determining risk of 30-day readmission were developed for each impairment group. CONCLUSIONS AND IMPLICATIONS: Multivariable risk factor algorithms based upon administrative data were developed to assess 30-day readmission risk for patients admitted from IRF. This report represents the development of a readmission risk calculator for the IRF setting, which could be instrumental in identifying high risk populations for readmission and targeting resources towards a diverse group of IRF impairment groups.

Hip, Knee, and Ankle Osteoarthritis Negatively Affects Mechanical Energy Exchange.

BACKGROUND: Individuals with osteoarthritis (OA) of the lower limb find normal locomotion tiring compared with individuals without OA, possibly because OA of any lower limb joint changes limb mechanics and may disrupt transfer of potential and kinetic energy of the center of mass during walking, resulting in increased locomotor costs. Although recovery has been explored in asymptomatic individuals and in some patient populations, the effect of changes in these gait parameters on center of mass movements and mechanical work in patients with OA in specific joints has not been well examined. The results can be used to inform clinical interventions and rehabilitation that focus on improving energy recovery. QUESTIONS/PURPOSES: We hypothesized that (1) individuals with end-stage lower extremity OA would exhibit a decrease in walking velocity compared with asymptomatic individuals and that the joint affected with OA would differntially influence walking velocity, (2) individuals with end-stage lower extremity OA would show decreased energy recovery compared with asymptomatic individuals and that individuals with end-stage hip and ankle OA would have greater reductions in recovery than would individuals with end-stage knee OA owing to restrictions in hip and ankle motion, and (3) that differences in the amplitude and congruity of the center of mass would explain the differences in energy recovery that are observed in each population. METHODS: Ground reaction forces at a range of self-selected walking speeds were collected from individuals with end-stage radiographic hip OA (n = 27; 14 males, 13 females; average age, 55.6 years; range, 41-70 years), knee OA (n = 20; seven males, 13 females; average age, 61.7 years; range, 49-74 years), ankle OA (n = 30; 14 males, 16 females; average age, 57 years; range, 45-70 years), and asymptomatic individuals (n = 13; eight males, five females; average age, 49.8 years; range, 41-67 years). Participants were all patients with end-stage OA who were scheduled to have joint replacement surgery within 4 weeks of testing. All patients were identified by the orthopaedic surgeon as having end-stage radiographic disease and to be a candidate for joint replacement surgery. Patients were excluded if they had pain at any other lower extremity joint, previous joint replacement surgery, or needed to use an assistive device for ambulation. Patients were enrolled if they met the study inclusion criteria. Our study was comparative and cohorts could be compared with each other, however, the asymptomatic group served to verify our methods and provided a recovery standard with which we could compare our patients. Potential and kinetic energy relationships (% congruity) and energy exchange (% recovery) were calculated. Linear regressions were used to examine the effect of congruity and amplitude of energy fluctuations and walking velocity on % recovery. Analysis of covariance was used to compare energy recovery between groups. RESULTS: The results of this study support our hypothesis that individuals with OA walk at a slower velocity than asymptomatic individuals (1.4 ± 0.2 m/second, 1.2-1.5 m/second) and that the joint affected by OA also affects walking velocity (p < 0.0001). The cohort with ankle OA (0.9 ± 0.2 m/second, 0.77-0.94 m/second) walked at a slower speed relative to the cohort with hip OA (1.1 ± 0.2 m/second, 0.96-1.1 m/second; p = 0.002). However, when comparing the cohorts with ankle and knee OA (0.9 ± 0.2 m/second, 0.77-0.94 m/second) there was no difference in walking speed (p = 0.16) and the same was true when comparing the cohorts with knee and hip OA (p = 0.14). Differences in energy recovery existed when comparing the OA cohorts with the asymptomatic cohort and when examining differences between the OA cohorts. After adjusting for walking speeds these results showed that asymptomatic individuals (65% ± 3%, 63%-67%) had greater recovery than individuals with hip OA (54% ± 10%, 50%-58%; p = 0.014) and ankle OA (47% ± 13%, 40%-52%; p = 0.002) but were not different compared with individuals with knee OA (57% ± 10%, 53%-62%; p = 0.762). When speed was accounted for, 80% of the variation in recovery not attributable to speed was explained by congruity with only 10% being explained by amplitude. CONCLUSIONS: OA in the hip, knee, or ankle reduces effective exchange of potential and kinetic energy, potentially increasing the muscular work required to control movements of the center of mass. CLINICAL RELEVANCE: The fatigue and limited physical activity reported in patients with lower extremity OA could be associated with increased mechanical work of the center of mass. Focused gait retraining potentially could improve walking mechanics and decrease fatigue in these patients.

A single set of biomechanical variables cannot predict jump performance across various jumping tasks.

Vertical jump performance is related to high-level function in athletics. The purpose of this study was to determine whether a single set of biomechanical variables exist that can predict vertical jump height during multiple jumping strategies: single foot jump, drop jump, and countermovement jump. Three-dimensional mechanics were collected during the 3 different jumping tasks in 50 recreational male athletes. Three successful trials were analyzed for each jump type. Testing order was randomized to minimize fatigue effects, and the dominant limb was used for analysis. All discrete variables were correlated to jump height and the 10 variables that had the strongest correlation were inserted into a linear regression model to identify what variables predicted maximum jump height. No single set of variables that predicted jump height existed across all 3 jumping tasks. One foot jump height was predicted by peak knee power, peak hip extension moment, peak knee extension velocity, and the percentage of the trial when peak knee flexion velocity occurred (r = 0.58). Countermovement jump height was predicted by peak hip power, ankle range of motion, and knee range of motion (r = 0.65). Drop jump height was predicted by the peak vertical ground reaction force and the percentage of the trial when the peak hip velocity occurred (r = 0.37). A single set of variables was not identified that could predict jump performance across different types of jumping tasks; therefore, additional interventional investigations are needed to better understand how to alter and improve jump performance.

Patient-Reported Outcomes, Function, and Gait Mechanics After Fixed and Mobile-Bearing Total Ankle Replacement.

BACKGROUND: The popularity of total ankle replacement as a treatment for end-stage arthritis continues to grow. The purpose of this study was to assess changes in ankle kinetics and kinematics from a preoperative time point through two years postoperatively in patients who had received either a fixed-bearing or a mobile-bearing implant. METHODS: Ninety patients who received a primary total ankle replacement (forty-nine mobile-bearing and forty-one fixed-bearing) were examined. Three-dimensional joint mechanics and ground reaction forces were measured during level walking preoperatively and one and two years postoperatively. Patient-reported and functional outcomes were also collected. Data were analyzed with use of a 3 × 2 repeated-measures analysis of variance (ANOVA) to determine significant differences between implant types and across time (α = 0.05). RESULTS: No significant difference was observed in the ankle motion or step time between implant types or across time. However, there was a greater increase in the peak plantar flexion moment and the Short Form-36 (SF-36) total score across time in the fixed-bearing group than in the mobile-bearing group. Conversely, visual analog scale (VAS) pain scores exhibited greater improvement in the mobile-bearing group than in the fixed-bearing group. Independent of implant type, a significant improvement was observed in walking speed, results of the functional tests, spatiotemporal variables, patient-reported outcomes, and vertical ground reaction forces. Independent of time, the fixed-bearing group demonstrated a significant increase in both the weight-acceptance and the propulsion ground reaction forces compared with the mobile-bearing group. The mobile-bearing group completed the Sit-to-Stand test significantly faster. CONCLUSIONS: All of the observed changes suggest improved or maintenance of function following total ankle replacement. In general, the group with a fixed-bearing implant demonstrated improvements in ankle moment and ground reaction forces, while the mobile-bearing-implant group demonstrated improvements in patient-reported pain outcome. There were few significant changes between the two implant types. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

The upper limb of Australopithecus sediba.

The evolution of the human upper limb involved a change in function from its use for both locomotion and prehension (as in apes) to a predominantly prehensile and manipulative role. Well-preserved forelimb remains of 1.98-million-year-old Australopithecus sediba from Malapa, South Africa, contribute to our understanding of this evolutionary transition. Whereas other aspects of their postcranial anatomy evince mosaic combinations of primitive (australopith-like) and derived (Homo-like) features, the upper limbs (excluding the hand and wrist) of the Malapa hominins are predominantly primitive and suggest the retention of substantial climbing and suspensory ability. The use of the forelimb primarily for prehension and manipulation appears to arise later, likely with the emergence of Homo erectus.