Rigid Boot Research Articles

Achilles Tendon Loading During Walking Differs Between Commonly Used Immobilizing Boots

Category: Sports; Basic Sciences/Biologics Introduction/Purpose: Achilles tendon ruptures have increased 10-fold in the past three decades, leading to long-term functional deficits in nearly two-thirds of patients. To counter this, rehabilitation protocols have been developed to strike a balance between protecting the healing tendon from re-rupture while allowing patients to return to activities of daily living as early as possible. However, Achilles tendon loading is neither prescribed nor quantified during immobilization and there is no standardized method of immobilization. Therefore, the purpose of this study was to quantify the amount of tendon loading experienced while walking in 3 different kinds immobilizing boot with respect to prescribed ankle angle and walking speed. Methods: Two healthy-young adults (2M; Age: 29.6 +- 2.3 y/o; BMI: 30 +- 7) walked over flat ground while wearing 3 different immobilizing boots and athletic shoes after providing written informed consent in this IRB approved study. We calculated Achilles tendon loading while subjects walked in 3 boots that positioned the ankle in 30 degrees of plantar flexion (Figure A, Air Cam Walker, United Ortho; AirSelect Walker, Aircast, VACOped, OPED). In all three boots, an instrumented insole (Loadsol, Novel) was placed under the foot to quantify load experienced by the tendon. We calculated the Achilles tendon loading profiles during gait for each immobilizing boot and compared them against the normal shod condition. We also provided the surgical repair threshold of 0.5 bodyweights to visualize the potential efficacy of each immobilizing boot for early rehabilitation when the tendon is early in the healing phase. Results: As expected, tendon loading was highest in the shod condition with no ankle bracing and lowest in the fully plantarflexed adjustable boot (Figure B). On average, the immobilizing boots reduced tendon loading decreased by 68% compared to unsupported walking in shoes but there were differences among the boots. The 3 different immobilizing boots provided differing levels of support. The 2 walking boots that use heel wedges to support the ankle in plantar flexion provided the least support, reducing loading by an average of 60-68%. The more rigid boot that constrained ankle angle using a posterior strut reduced tendon loading by 77% compared to gait in a normal walking shoe. Based on biomechanical studies of Achilles tendon repair strength in cadaveric experiments, only the rigid boot with the posterior strut reduced tendon loading biomechanics to levels that could be resisted by the surgical repair (Figure B). Conclusion: In this study, we used an instrumented insole to quantify Achilles tendon loading in a variety of immobilizing boots used by rupture patients. Our initial findings show that tendon loading is varies greatly between boot types and patients, highlighting the importance of understanding how these loads change in patients. Our future work centers around identifying the tendon loading profiles that promote tendon healing and optimize patient outcomes. These loading profiles will then provide the quantitative data needed to personalize loading for patients and guide rehabilitation to improve outcomes.

Acute Achilles tendon rupture: Do cast boots produce adequate equinus when used for functional rehabilitation?

Acute Achilles tendon rupture is frequently treated conservatively using functional rehabilitation protocols in which the ankle is held in equinus. Equinus is achieved using a variety of means including equinus casts and rigid boots with heel wedges. Concerns have been raised that rigid boots with heel wedges do not achieve adequate equinus.Patients presenting to our institutions with an acute Achilles tendon rupture were randomised to treatment with an equinus cast or rigid boot with heel wedges. After application of these lateral radiographs of the hindfoot and ankle were taken, and these used to measure tibiotalar angle (TTA), tibio-1st metatarsal angle (TMA) and posterior malleolar to calcaneal tip height (PCH).15 patients were randomised to a rigid boot and 14 to an equinus cast. The mean TTA was 124° in the rigid boot group and 136° in the equinus cast group (p<0.001). The mean TMA was 134° in the rigid boot group and 147° in the equinus cast group (p<0.001). The mean PCH was 25mm in the rigid boot group and 15mm in the equinus cast group (p<0.05).Our results demonstrate that the rigid boots with heel wedges used in our institutions produce significantly less equinus than an equinus cast. Whilst the clinical relevance of this remains uncertain, clinicians should be aware that rigid boots with wedges and equinus casts may not achieve the same degree of Achilles tendon shortening.

The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking.

BackgroundRobotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing of positive prosthesis push-off work in isolation and measure the effects on energetics, mechanics and muscle activity.MethodsWe tested 10 able-bodied participants walking on a treadmill at 1.25 m · s−1. Participants wore a tethered ankle-foot prosthesis emulator on one leg using a rigid boot adapter. We programmed the prosthesis to apply torque bursts that began between 46% and 56% of stride in different conditions. We iteratively adjusted torque magnitude to maintain constant net positive push-off work.ResultsWhen push-off began at or after leading leg contact, metabolic rate was about 10% lower than in a condition with Spring-like prosthesis behavior. When push-off began before leading leg contact, metabolic rate was not different from the Spring-like condition. Early push-off led to increased prosthesis-side vastus medialis and biceps femoris activity during push-off and increased variability in step length and prosthesis loading during push-off. Prosthesis push-off timing had no influence on intact-side leg center-of-mass collision work.ConclusionsProsthesis push-off timing, isolated from push-off work, strongly affected metabolic rate, with optimal timing at or after intact-side heel contact. Increased thigh muscle activation and increased human variability appear to have caused the lack of reduction in metabolic rate when push-off was provided too early. Optimal timing with respect to opposite heel contact was not different from normal walking, but the trends in metabolic rate and center-of-mass mechanics were not consistent with simple model predictions. Optimal push-off timing should also be characterized for individuals with amputation, since meaningful benefits might be realized with improved timing.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-015-0014-8) contains supplementary material, which is available to authorized users.

Percutaneous Drilling for Early-Stage Osteonecrosis About the Ankle.

The mid-term clinical, patient-reported, and radiographic outcomes of percutaneous drilling to treat early-stage osteonecrosis (without joint collapse) of the distal part of the tibia or of the talus are promising. Obtain anteroposterior and lateral ankle radiographs as well as magnetic resonance imaging (MRI) studies of the ankle to evaluate the stage of the osteonecrotic disease. Insert a 1.8-mm Steinmann pin or Ilizarov wire percutaneously under biplanar fluoroscopic visualization. Make one, two, or three passes with a 3.2-mm cannulated drill bit over the pin into the lesion(s). Infiltrate the defect with demineralized bone matrix to backfill the drill track and the deep necrotic bone defect. The patient bears weight as tolerated in a removable short leg rigid boot for the first four weeks and avoids high-impact activities for at least ten months. In our study, there were significant improvements in the mean American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score (p = 0.001), University of California Los Angeles (UCLA) activity score (p = 0.025), and visual analog scale (VAS) pain score (p = 0.001) at a mean of five years (range, two to nine years) postoperatively.IndicationsContraindicationsPitfalls & Challenges.

Ski-ing Injuries

Injuries sustained while ski-ing do not differ significantly from injuries due to other sports. Tears of the medial meniscus however are rare in ski injuries compared with football. The increasing frequency of the unstable boot top fracture due to the modern high rigid boot resembles the type of fracture sustained in a sliding tackle on the football field. Discussion on ski injuries therefore should emphasise prevention rather than treatment. Statistics suggest certain common factors in the clinical history of ski injuries which indicates the need for a safety code which might reduce the incidence of injury and thereby increase the pleasure derived from this sport. In this article common ski injuries will be mentioned, prevention will be discussed and a safety code for skiers will be suggested.

Rotational knee laxity: Reliability of a simple measurement device in vivo

BackgroundDouble bundle ACL reconstruction has been demonstrated to decrease rotational knee laxity. However, there is no simple, commercially-available device to measure knee rotation. The investigators developed a simple, non-invasive device to measure knee rotation. In conjunction with a rigid boot to rotate the tibia and a force/moment sensor to allow precise determination of torque about the knee, a magnetic tracking system measures the axial rotation of the tibia with respect to the femur. This device has been shown to have acceptable levels of test re-test reliability to measure knee rotation in cadaveric knees.MethodsThe objective of this study was to determine reliability of the device in measuring knee rotation of human subjects. Specifically, the intra-tester reliability within a single testing session, test-retest reliability between two testing sessions, and inter-tester reliability were assessed for 11 male subjects with normal knees.ResultsThe 95% confidence interval for rotation was less than 5° for intra-tester, test-retest, and inter-tester reliability, and the standard error of measurement for the differences between left and right knees was found to be less than 3°.ConclusionIt was found that the knee rotation measurements obtained with this device have acceptable limits of reliability for clinical use and interpretation.

The advantages of a rolling foot in human walking

The plantigrade human foot rolls over the ground during each walking step, roughly analogous to a wheel. The center of pressure progresses on the ground like a wheel of radius 0.3 L (leg length). We examined the effect of varying foot curvature on the mechanics and energetics of walking. We controlled curvature by attaching rigid arc shapes of various radii to the bottoms of rigid boots restricting ankle motion. We measured mechanical work performed on the center of mass (COM), and net metabolic rate, in human subjects (N=10) walking with seven arc radii from 0.02-0.40 m. Simple models of dynamic walking predict that redirection of COM velocity requires step-to-step transition work, decreasing quadratically with arc radius. Metabolic cost would be expected to change in proportion to mechanical work. We measured the average rate of negative work performed on the COM, and found that it followed the trend well (r2=0.95), with 2.37 times as much work for small radii as for large. Net metabolic rate (subtracting quiet standing) also decreased with increasing arc radius to a minimum at 0.3 L, with a slight increase thereafter. Maximum net metabolic rate was 6.25 W kg(-1) (for small-radius arc feet), about 59% greater than the minimum rate of 3.93 W kg(-1), which in turn was about 45% greater than the rate in normal walking. Metabolic rate was fit reasonably well (r2=0.86) by a quadratic curve, but exceeded that expected from COM work for extreme arc sizes. Other factors appear to increase metabolic cost for walking on very small and very large arc feet. These factors may include effort expended to stabilize the joints (especially the knee) or to maintain balance. Rolling feet with curvature 0.3 L appear energetically advantageous for plantigrade walking, partially due to decreased work for step-to-step transitions.

Experimental Vertical Jump Model Used to Evaluate the Pivot Location in Klap Speed Skates

This study used a vertical jump model to simulate the push-off phase for a skater using klap speed skates and evaluated die effects of pivot location and shoe base flexion on energy production. Boards of different lengths and one board with a hinge under the metatarsal heads were attached to the running shoes of volunteers. Six skaters performed 3 maximal effort vertical jumps across 5 different base conditions: running shoe, board that hinged under metatarsal heads, and rigid boards that pivoted with the ground al -25 mm (typical pivot location for klapskales), 0 mm, and +25 mm from the toes. There were no significant differences in total energy at take-off among the 3 rigid base conditions, but there were differences in potential and kinetic energy production. The total and kinetic energy produced at take-off was 9% greater in the hinged base condition than the corresponding rigid base condition. If differences in energy measures from the vertical jump reflect those for skating, a hinged boot base could increase skating speeds by about 3% over the current klap-skales, which have a rigid boot base.

Snowboard traumatology: an epidemiological study.

In the past 10 years, snowboarding has become a popular winter sport among young people, and the number of accidents has increased proportionately. The incidence of traumas from snowboarding is shown to be 4 to 6 for every 1000 medical examinations, which is similar to that of downhill skiing. However, other important statistical differences exist between the two sports. This study of 106 snowboarding-related injury cases analyzes the epidemiology of these injuries in Italy. Results found that 45.1% of injuries are located in the upper limbs and that significant advantages are obtained with the introduction of guards to protect the upper limbs during descent. Serious ligament injuries to the knee are more rare in snowboarding than in downhill skiing. In both sports, injuries are more common with rigid boots, which lead to a higher incidence of injury to the upper limbs. Finally, a high percentage of injury to beginners was found in this study. Training courses for those who are considering taking up the sport of snowboarding could significantly lower their risk of trauma.

An unusual ankle injury in top skiers

Although skiers' feet are immobilized in extremely rigid boots, ligamentous lesions of the ankle may occur, especially in world class slalom skiers. The lesion arises when a sudden external rotation of the ankle causes the talus to press against the fibula and thus open the distal tibiofibular articulation. This study reports on a group of 10 skiers recruited between 1975 and 1986. These are professional skiers participating in World Cup races. Three patients underwent an operation for lesion of the tibiofibular syndesmosis, while the other seven were treated conservatively. All were able to resume their previous level of competition and only one skier later complained of painful instability in distal tibiofibular joint.