Does a microprocessor-controlled prosthetic knee affect stair ascent strategies in persons with transfemoral amputation?

BACKGROUND: Stair ascent can be difficult for individuals with transfemoral amputation because of the loss of knee function. Most individuals with transfemoral amputation use either a step-to-step (nonreciprocal, advancing one stair at a time) or skip-step strategy (nonreciprocal, advancing two stairs at a time), rather than a step-over-step (reciprocal) strategy, because step-to-step and skip-step allow the leading intact limb to do the majority of work. A new microprocessor-controlled knee (Ottobock X2(®)) uses flexion/extension resistance to allow step-over-step stair ascent. QUESTIONS/PURPOSES: We compared self-selected stair ascent strategies between conventional and X2(®) prosthetic knees, examined between-limb differences, and differentiated stair ascent mechanics between X2(®) users and individuals without amputation. We also determined which factors are associated with differences in knee position during initial contact and swing within X2(®) users. METHODS: Fourteen individuals with transfemoral amputation participated in stair ascent sessions while using conventional and X2(®) knees. Ten individuals without amputation also completed a stair ascent session. Lower-extremity stair ascent joint angles, moment, and powers and ground reaction forces were calculated using inverse dynamics during self-selected strategy and cadence and controlled cadence using a step-over-step strategy. RESULTS: One individual with amputation self-selected a step-over-step strategy while using a conventional knee, while 10 individuals self-selected a step-over-step strategy while using X2(®) knees. Individuals with amputation used greater prosthetic knee flexion during initial contact (32.5°, p = 0.003) and swing (68.2°, p = 0.001) with higher intersubject variability while using X2(®) knees compared to conventional knees (initial contact: 1.6°, swing: 6.2°). The increased prosthetic knee flexion while using X2(®) knees normalized knee kinematics to individuals without amputation during swing (88.4°, p = 0.179) but not during initial contact (65.7°, p = 0.002). Prosthetic knee flexion during initial contact and swing were positively correlated with prosthetic limb hip power during pull-up (r = 0.641, p = 0.046) and push-up/early swing (r = 0.993, p < 0.001), respectively. CONCLUSIONS: Participants with transfemoral amputation were more likely to self-select a step-over-step strategy similar to individuals without amputation while using X2(®) knees than conventional prostheses. Additionally, the increased prosthetic knee flexion used with X2(®) knees placed large power demands on the hip during pull-up and push-up/early swing. A modified strategy that uses less knee flexion can be used to allow step-over-step ascent in individuals with less hip strength.

Prevalence of late amputations during the current conflicts in Afghanistan and Iraq.

During the current conflicts, over 950 soldiers have sustained a combat-related amputation. The majority of these are acute, but an unknown number are performed months to years after the initial injury. The goal of this study is to determine the prevalence of late amputations in our combat wounded. Electronic medical records and radiographs of all soldiers who had a combat-related, lower extremity injury that resulted in amputation were reviewed to confirm demographic, injury, and amputation information. Time to amputation was defined as a late amputation when it occurred more than 12 weeks following the date of injury. There were 348 major limb amputees that met inclusion criteria. Fifty-three (15.2%) amputees had a late amputation (range = 12 wk-5.5 yr). While the majority of combat-related amputations occur acutely, more than 15% occur late. This study demonstrates that further research is needed to identify predictive factors and outcomes of the late amputation.

Amputation is not isolated: an overview of the US Army Amputee Patient Care Program and associated amputee injuries.

Rates of amputation as a percentage of all combat injuries have increased significantly since the Korean War. Following traumatic and combat-related amputation, definitive treatment and rehabilitation require a large, multidisciplinary team to provide comprehensive medical and supportive care. Associated injuries are remarkably frequent, complicating treatment and potentially delaying rehabilitation and/or limiting outcomes. Patient and family psychosocial issues also must be assessed and appropriately addressed. The US Army Amputee Patient Care Program, with the support of numerous other government and private organizations, has been developed to meet the comprehensive medical, rehabilitative, and social needs of amputees injured in the current global war on terrorism, with the goal of maximizing subsequent patient outcomes utilizing a sports medicine approach.

Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective four-year evaluation of 859 West Point cadets.

BACKGROUND: The causes of noncontact anterior cruciate ligament injury remain an enigma. PURPOSE: To prospectively evaluate risk factors for noncontact anterior cruciate ligament injuries in a large population of young athletic people. STUDY DESIGN: Prospective cohort study. METHODS: In 1995, 1198 new United States Military Academy cadets underwent detailed testing and many parameters were documented. During their 4-year tenure, all anterior cruciate ligament injuries that occurred were identified. Statistical analyses were used to identify the factors that may have predisposed the cadets to noncontact anterior cruciate ligament injuries. RESULTS: Among the 895 cadets who completed the entire 4-year study, there were 24 noncontact anterior cruciate ligament tears (16 in men, 8 in women). Significant risk factors included small femoral notch width, generalized joint laxity, and, in women, higher than normal body mass index and KT-2000 arthrometer values that were 1 standard deviation or more above the mean. The presence of more than one of these risk factors greatly increased the relative risk of injury. All female cadets who had some combination of risk factors sustained noncontact anterior cruciate ligament injuries, indicating that some combinations of factors are especially perilous to the female knee. CONCLUSION: Several risk factors may predispose young athletes to noncontact anterior cruciate ligament injury.

Upper body fatiguing exercise and shooting performance.

This study assessed the effect of upper extremity muscle fatigue on shooting performance while in a standing, unsupported firing position. Nine male and three female soldiers fired at targets before and after performing upper extremity exercise to fatigue using both (1) an upper body ergometer and (2) a Military Operations in Urban Terrain obstacle course. Shooting accuracy, assessed by the number of hits, misses, and shot group size, was significantly decreased (p < 0.05) immediately following both types of exercise and recovered to pre-exercise values within 5 minutes for all measures except the number of misses, which returned to pre-exercise values by 10 minutes. There was no relationship between fitness measures and shooting performance, although muscle endurance was a factor in the duration of exercise prior to fatigue. We conclude that shooting accuracy recovers rapidly in fit soldiers following fatiguing lifting, climbing, and pulling activity.

Effect of drain use in the early postoperative period after arthroscopically assisted anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft.

BACKGROUND: Little data exist on the effect of routine use of postoperative drainage after arthroscopic anterior cruciate ligament reconstruction, although clinical studies of other procedures have not shown benefit to this practice. HYPOTHESIS: Use of a postoperative drain will not result in decreased suprapatellar girth, increased range of motion, and decreased pain compared with nonuse. STUDY DESIGN: Prospective randomized clinical trial. METHODS: Twenty-one patients undergoing arthroscopically assisted bone-patellar tendon-bone anterior cruciate ligament reconstruction were randomly assigned to receive a drain for 24 hours (12 patients) or no drain (9 patients). Data for comparison of groups were collected daily through postoperative day 7. RESULTS: Pain scores on a visual analog scale demonstrated the same improving trend over time for both treatment and control groups; however, the treatment group had significantly higher average pain scores, except on day 7. Differences in suprapatellar girth, flexion, and extension were not found to be statistically significant between groups. CONCLUSION: Use of a drain after arthroscopically assisted anterior cruciate ligament reconstruction provided no benefit in terms of range of motion, effusion, or pain in the early postoperative period.

Gender differences in regional body composition and somatotrophic influences of IGF-I and leptin.

This study evaluated the arm, trunk, and leg for fat mass, lean soft tissue mass, and bone mineral content (BMC) assessed via dual-energy X-ray absorptiometry in a group of age-matched (approximately 29 yr) men (n = 57) and women (n = 63) and determined their relationship to insulin-like growth factor I (IGF-I) and leptin. After analysis of covariance adjustment to control for differences in body mass between genders, the differences that persisted (P < or = 0.05) were for lean soft tissue mass of the arm (men: 7.1 kg vs. women: 6.4 kg) and fat mass of the leg (men: 5.3 kg vs. women: 6.8 kg). Men and women had similar (P > or = 0.05) values for fat mass of the arms and trunk and lean soft tissue mass of the legs and trunk. Serum IGF-I and insulin-like growth factor binding protein-3 correlated (P < or = 0.05) with all measures of BMC (r values ranged from 0.31 to 0.39) and some measures of lean soft tissue mass for women (r = 0.30) but not men. Leptin correlated (P < or = 0.05) similarly for measures of fat mass for both genders (r values ranging from 0.74 to 0.85) and for lean soft tissue mass of the trunk (r = 0.40) and total body (r = 0.32) for men and for the arms in women (r = 0.56). These data demonstrate that 1) the main phenotypic gender differences in body composition are that men have more of their muscle mass in their arms and women have more of their fat mass in their legs and 2) gender differences exist in the relationship between somatotrophic hormones and lean soft tissue mass.