Dynamic Joint Loading Research Articles

The relationship of vibratory perception to dynamic joint loading, radiographic severity, and pain in knee osteoarthritis

Patients with knee osteoarthritis (OA) have been shown to have somatosensory deficits of the lower extremity. This study was designed to assess the association of these deficits with dynamic joint loading and their relationship to the structural and symptomatic severity of knee OA. Subjects with symptomatic knee OA underwent evaluation of the vibratory perception threshold (VPT) using a biothesiometer at 5 sites at the lower extremity. Dynamic joint loading was assessed through gait analyses. Knee pain was evaluated using a visual analog scale score for pain based on the Western Ontario and McMaster Universities OA Index. Radiographic severity of knee OA was assessed using the Kellgren/Lawrence (K/L) grading scale on radiographs obtained with the knee in a standing position. Dynamic knee joint loading was directly associated with the VPT at the metatarsophalangeal (MTP) joint (Spearman's rho=0.384, P=0.033), indicating that the worse the vibratory sense, the higher the knee load during gait. The K/L severity grade was directly associated with the VPT at the MTP joint and lateral femoral condyle, after adjustment for age, sex, body mass index, and knee pain. After adjustment for confounders, there were no significant associations observed between the VPT and pain at any of the sites tested. These findings demonstrate an association between greater somatosensory deficits and higher dynamic loads in OA. They also demonstrate structural consequences associated with somatosensory deficits in OA, since the extent of sensory loss directly correlated with the radiographic severity of knee OA. However, there was no relationship observed between vibratory sense and symptomatic knee OA pain.

Asymmetric loading and bone mineral density at the asymptomatic knees of patients with unilateral hip osteoarthritis

In patients with unilateral end-stage hip osteoarthritis (OA), the contralateral knee is known to be at greater risk for end-stage knee OA compared to the ipsilateral (i.e., same-side) knee. The contralateral knee is known to have increased dynamic joint loads compared to the ipsilateral knee. The present study was undertaken to examine patients who had unilateral hip OA but who did not have symptoms of knee OA, in order to detect early asymmetries in knee loading. Data on 62 patients with unilateral hip OA were evaluated. Patients underwent gait analyses of dynamic knee loads as well as dual x-ray absorptiometry for determination of bone mineral density (BMD) in both knees. Differences between knees were compared. Peak dynamic knee loads were significantly higher at the contralateral knee compared to the ipsilateral knee (mean ± SD 2.46 ± 0.71 percent of body weight × height versus 2.23 ± 0.81 percent of body weight × height; P = 0.029). Similarly, medial compartment tibial BMD was significantly higher in the contralateral knee compared to the ipsilateral knee (mean ± SD 0.897 ± 0.208 gm/cm(2) versus 0.854 ± 0.206 gm/cm(2); P = 0.033). Interestingly, there was a direct correlation between the contralateral:ipsilateral dynamic knee load and contralateral:ipsilateral medial compartment tibial BMD (ρ = 0.287, P = 0.036). The risk of developing progressive symptomatic OA in contralateral knees is higher compared to the risk in ipsilateral knees in patients with unilateral hip OA. The present study demonstrates that loading and structural asymmetries appear early in the disease course, while the knees are still asymptomatic. These early biomechanical asymmetries may have corresponding long-term consequences, providing further evidence for the potential role of loading in OA onset and progression.

Normal Anatomy and Biomechanics of the Knee

Functionally, the knee comprises 2 articulations-the patellofemoral and tibiofemoral. Stability of the joint is governed by a combination of static ligaments, dynamic muscular forces, meniscocapsular aponeurosis, bony topography, and joint load. The surgeon is ill equipped to undertake surgical treatment of a dislocated knee without a sound footing in the anatomic complexities of this joint. We review the normal anatomy of the knee, emphasizing connective tissue structures and common injury patterns.

DYNAMIC JOINT LOAD TRANSFER EFFICIENCY OF RIGID PAVEMENT

Abstrac t — the mechanistic analysis presented in this paper is only the beginning of new approach for understanding the real joint load transfer capability on airport and highway concrete pavements. It gives up the two major assumptions those have been popularly adopted by hundreds of published papers: the load is transferred under a wheel with zero speed and with fixed position. The real load transfer in field is always under wheels with non-zero speed and with varied position at any moment. The objective of this study focuses on quantifying the dynamic effects of a moving wheel while it is crossing a joint on a pavement. The analysis is conducted using a model of two-slab system on Kelvin foundation under a moving wheel with variable speed v, different pavement damping C s , foundation reaction modulus k and foundation damping C k . The dynamic joint load transfer efficiency is temporarily and empirically defined by the peak strain ratio LTE(S) on the two sides of a joint. The primary findings include: (1) The higher speed of a moving wheel leads to the higher LTE(S);(2) The larger the pavement damping C s leads to the higher LTE(S);(3) The numerical ratio c(=LTE(S) dynamic / LTE(S) static ) varies in the range 1 to 2 mainly depending on speed v and damping C s ;(4) The LTE(S) dynamic is not

Comparative diagnostic accuracy of knee adduction moments in knee osteoarthritis: A case for not normalizing to body size

Previous authors have questioned the practice of normalizing the external knee adduction moment during gait to body size when investigating dynamic joint loading in knee osteoarthritis (OA). The purpose of this study was to compare the abilities of non-normalized and normalized external knee adduction moments during gait in discriminating between patients with least and greatest severity of radiographic medial compartment knee OA. Subjects with mild (n=118) and severe (n=115) medial compartment knee OA underwent three-dimensional gait analysis. The peak external knee adduction moment was calculated and kept in its original units (Nm), normalized to body mass (Nm/kg) and normalized to body weight and height (%BW×Ht). Receiver Operating Characteristic (ROC) curve analysis indicated that non-normalized values better discriminated between patients with mild and severe knee OA. The area under the ROC curve for non-normalized peak knee adduction moments (0.63) was significantly (p<0.05) greater than when normalized to body mass (0.58), or to body weight times height (0.57). Post-hoc analysis of covariance indicated the mean difference in peak knee adduction moment between OA severity groups (7.23Nm, p=0.003) was reduced by approximately 50% (3.60Nm, p=0.09) when adjusted for mass. These findings are consistent with the suggestion that non-normalized values are more sensitive to radiographic disease progression. We suggest including knee adduction moment values that are not normalized to body size when investigating knee OA.

Simulated Whiplash Modulates Expression of the Glutamatergic System in the Spinal Cord Suggesting Spinal Plasticity Is Associated with Painful Dynamic Cervical Facet Loading

The cervical facet joint and its capsule have been reported to be injured during whiplash scenarios and are a common source of chronic neck pain from whiplash. Both the metabotropic glutamate receptor 5 (mGluR5) and the excitatory amino acid carrier 1 (EAAC1) have pivotal roles in chronic pain. In this study, spinal mGluR5 and EAAC1 were quantified following painful facet joint distraction in a rat model of facet-mediated painful loading and were evaluated for their correlation with the severity of capsule loading. Rats underwent either a dynamic C6/C7 joint distraction simulating loading experienced during whiplash (distraction; n = 12) or no distraction (sham; n = 6) to serve as control. The severity of capsular loading was quantified using strain metrics, and mechanical allodynia was assessed after surgery. Spinal cord tissue was harvested at day 7 and the expression of mGluR5 and EAAC1 were quantified using Western blot analysis. Mechanical allodynia following distraction was significantly (p < 0.001) higher than sham. Spinal expression of mGluR5 was also significantly (p < 0.05) greater following distraction relative to sham. However, spinal EAAC1 was significantly (p = 0.0003) reduced compared to sham. Further, spinal mGluR5 expression was significantly positively correlated to capsule strain (p < 0.02) and mechanical allodynia (p < 0.02). Spinal EAAC1 expression was significantly negatively related to one of the strain metrics (p < 0.003) and mechanical allodynia at day 7 (p = 0.03). These results suggest that the spinal glutamatergic system may potentiate the persistent behavioral hypersensitivity that is produced following dynamic whiplash-like joint loading; chronic whiplash pain may be alleviated by blocking mGluR5 expression and/or enhancing glutamate transport through the neuronal transporter EAAC1.

A comparison of measuring mechanical axis alignment using three-dimensional position capture with skin markers and radiographic measurements in patients with bilateral medial compartment knee osteoarthritis

The mechanical axis alignment of the lower extremity is typically measured from frontal plane radiographs of the entire lower extremity during double support standing. The purpose of this study was to test the hypothesis that the mechanical axis alignment can be predicted from skin markers on anatomical landmarks and anthropometric measurements and a stereophotogrammetric system based on significant correlation with the mechanical axis alignment measured from standing radiographs. Mechanical axis alignment was measured using full-limb radiographs for both knees of 62 patients with bilateral medial compartment knee osteoarthritis (OA). Mechanical axis alignment was also measured using a stereophotogrammetric system with markers on anatomical landmarks and anthropometric measurements to determine joint centers. The mechanical axis alignment from position capture correlated with that from radiographs ( R 2 = 0.544; P < 0.001). This relationship did not depend on age, gender, BMI, or OA severity. A small but significant difference in the mechanical axis alignment between the two methods was observed (radiograph: 2.6 varus; position capture: 3.8 varus; P = 0.001). Associations between mechanical axis alignment and OA severity were found for both methods (radiographic: R 2 = 0.563; position capture: R 2 = 0.807). The proposed method allows the measurement of the mechanical axis alignment without exposure to radiation. This method enables the establishment of the relationship between lower limb alignment and functional variables such as dynamic joint loading in degenerative joint disease and joint injury even in populations who typically do not undergo radiographic examination.

Effects of specialized footwear on joint loads in osteoarthritis of the knee

Elevated dynamic joint loads have been associated with the severity and progression of osteoarthritis (OA) of the knee. This study compared the effects of a specialized shoe (the mobility shoe) designed to lower dynamic loads at the knee with self-chosen conventional walking shoes and with a commercially available walking shoe as a control. Subjects with knee OA were evaluated in 2 groups. Group A (n = 28) underwent gait analyses with both their self-chosen walking shoes and the mobility shoes. Group B (n = 20) underwent gait analyses with a control shoe and the mobility shoe. Frontal plane knee loads were compared between the different footwear conditions. Group A demonstrated an 8% reduction in the peak external knee adduction moment with the mobility shoe compared with self-chosen walking shoes (mean +/- SD 49 +/- 0.80 versus 2.71 +/- 0.84 %BW x H; P < 0.05). Group B demonstrated a 12% reduction in the peak external knee adduction moment with the mobility shoe compared with the control shoe (mean +/- SD 2.66 +/- 0.69 versus 3.07 +/- 0.75 %BW x H; P < 0.05). Specialized footwear can effectively reduce joint loads in subjects with knee OA, compared with self-chosen shoes and control walking shoes. Footwear may represent a therapeutic target for the treatment of knee OA. The types of shoes worn by subjects with knee OA should be evaluated more closely in terms of their effects on the disease.

The Long-term Consequence of Anterior Cruciate Ligament and Meniscus Injuries

The objectives of this study are to review the long-term consequences of injuries to the anterior cruciate ligament and menisci, the pathogenic mechanisms, and the causes of the considerable variability in outcome. Injuries of the anterior cruciate ligament and menisci are common in both athletes and the general population. At 10 to 20 years after the diagnosis, on average, 50% of those with a diagnosed anterior cruciate ligament or meniscus tear have osteoarthritis with associated pain and functional impairment: the young patient with an old knee. These individuals make up a substantial proportion of the overall osteoarthritis population. There is a lack of evidence to support a protective role of repair or reconstructive surgery of the anterior cruciate ligament or meniscus against osteoarthritis development. A consistent finding in a review of the literature is the often poor reporting of critical study variables, precluding data pooling or a meta-analysis. Osteoarthritis development in the injured joints is caused by intra-articular pathogenic processes initiated at the time of injury, combined with long-term changes in dynamic joint loading. Variation in outcome is reinforced by additional variables associated with the individual such as age, sex, genetics, obesity, muscle strength, activity, and reinjury. A better understanding of these variables may improve future prevention and treatment strategies. In evaluating medical treatment, we now expect large randomized clinical trials complemented by postmarketing monitoring. We should strive toward a comparable level of quality of evidence in surgical treatment of knee injuries. In instances in which a randomized clinical trial is not feasible, natural history and other observational cohort studies need to be as carefully designed and reported as the classic randomized clinical trial, to yield useful information.

Radiographic Measures of Knee Alignment in Patients with varus Gonarthrosis

Background Radiographic measures of lower limb malalignment are used to indicate abnormal loading of the knee and to plan corrective procedures. Hypotheses Weightbearing status during hip-to-ankle radiographs will significantly affect malalignment measures; malalignment in single-limb standing will be most highly correlated to the external knee adduction moment during gait, a proposed dynamic measure of functional knee joint load. Study Design Controlled laboratory study. Methods Mechanical axis angle was measured in 40 patients with varus gonarthrosis from hip-to-ankle radiographs taken with patients in single-limb standing, double-limb standing, and supine positions. Kinematic and kinetic data were collected during walking and used to calculate the peak adduction moment about the knee. Results Repeated-measures analysis of variance and Scheffé post hoc tests indicated that mechanical axis angle measured on single-limb standing radiographs (-8.7°± 4.0°) was significantly greater than on double-limb standing radiographs (-7.1°± 3.8°), which was significantly greater than on supine radiographs (-5.5°± 2.8°). The peak knee adduction moment (2.8 ± 0.8 percentage body weight × height) was only moderately correlated with mechanical axis angle on single-limb standing (r = -0.46), double-limb standing (r = -0.45), and supine (r = -0.43) radiographs. Conclusion Patient position significantly affects frontal plane knee alignment. However, the peak knee adduction moment is only moderately correlated to mechanical axis angle, regardless of weightbearing status. Clinical Relevance These findings are inconsistent with the hypothesis that mechanical axis angle measured in single-limb standing is more representative of dynamic joint load and further highlight the differences between static and dynamic measures. Results also underscore the importance of reporting patient position during radiographs and keeping positions consistent when evaluating patients over time.

The Evaluation of Patellofemoral Pain in the Clinic

Static measures taken in the clinic are commonly used to infer the cause and treatment of patients with patellofemoral pain (PFP). Functional joint loading parameters taken from a three-dimensional gait analysis also provide useful data to investigate potential mechanisms of lower limb injury, although this takes time, expertise, and expensive equipment. It would be useful for a clinician to assess dynamic joint loading from some simple measures taken in the clinic. Particular focus is given to the hip muscles due to their ability to control femoral rotation and valgus posture at the knee. PURPOSE: To determine if routine clinical measures predict dynamic joint loading response during gait in patients with PFP. METHODS: Gait analysis data and clinical measurements were obtained from 24 subjects with PFP (10 males, 14 females). Subjects walked at a self-selected pace and data were averaged across five trials. Three dimensional kinematics and kinetics were determined using an 8-camera motion analysis system, Bertec force plate, and a standard lower limb marker set. The following parameters were obtained; peak hip adduction moment, hip adduction angle, knee adduction moment, and knee flexion moment. An experienced clinician then took the following clinical measures for each subject; Q-angle, absolute hip abduction strength, hip internal rotation range of motion, iliotibial band tightness, and thigh circumference. A Pearson correlation coefficient was used to compare individual gait variables with clinical measures. A multiple linear regression was also used to determine the ability of the clinical measures to predict the gait variables. RESULTS: Decreased hip abductor strength was associated with decreased hip adductor moments. (R2 = 0.196, p = 0.03). Increased Q-angle was associated with increased peak hip adduction angle (R2 = 0.309, p = 0.005). Agreater ratio of hip internal/ external rotation (IE ratio) was associated with increased hip adduction moments during gait (R2 = 0.179, p = 0.04). Multiple regression using factors hip abductor strength, hip IE ratio, and Q-angle improved the predictions of peak hip adduction moment to 37%. The Q angle and absolute hip abductor strength combined to predict 30% of the knee peak adduction moment. CONCLUSION: In the evaluation of PFP, Q-angle, hip strength, and hip IE ratio were simple clinical measures that were predictive of relevant lower extremity moments and angles during active gait. Supported by Veterans Affairs Rehabilitation R&D (#A2592R), NIH (EB005790-01), and Stanford Regenerative Medicine (1R-90DK071508).

Bone mineral density of the proximal femur is not related to dynamic joint loading during locomotion in young women

We characterized the extent to which body mass influences the relationship between hip joint moments during locomotion and bone mineral density (BMD) of the proximal femur in healthy young women ( n = 24). There is some evidence of a direct relationship between hip joint moments during locomotion and BMD of the proximal femur in patients with osteoarthritis. Nevertheless, based on expected simultaneous influences of body mass on BMD and joint moments during locomotion, we hypothesized that BMD would not be significantly associated with hip joint moments during locomotion independently of body mass. BMD of the nondominant proximal femur was determined using DXA. The hip joint moments were determined by gait analysis. The correlation between peak internal rotation moment and BMD of the intertrochanteric region was significant ( r = 0.48; P = 0.019). However, body mass was significantly correlated to both BMD and the internal rotation moment ( r = 0.59 and 0.70; P = 0.002 and <0.001, respectively). After accounting for the relationship between body mass and hip joint moment, the internal rotation moment was not significantly correlated to BMD of the proximal femur ( r = 0.04, P = 0.34) indicating that BMD is not significantly associated with hip joint moments during locomotion independent of body mass in young healthy women.

P132 Dynamic joint loading alterations are associated with radiographic severity but not pain in subjects with unilateral hip osteoarthritis (OA)

P132 Dynamic joint loading alterations are associated with radiographic severity but not pain in subjects with unilateral hip osteoarthritis (OA)

A biomechanical approach to musculoskeletal disease.

The importance of biomechanical factors in musculoskeletal disease may be appreciated in the clinical characteristics and pathophysiology of joint degeneration in osteoarthritis. The biomechanical characteristics of the neuromuscular system are integral in determining the function and stability of the synovial joint and in mediating the biochemical structure of articular cartilage. Alterations in the neuromuscular system including abnormal gait and dynamic joint loading patterns as well as muscle strength and proprioception deficits have been independently studied and associated with osteoarthritis. These factors have close functional and physiological interactions. Nevertheless, specific relations between muscle strength and proprioception and their independent contributions to dynamic joint loading are not yet clear. Targeted interventions to moderate these factors may, in the future, be a therapeutic option for the management of osteoarthritis.

Dynamic loads are determinants of peak bone mass

This study investigated the association between non-invasive measurements of bone mass and markers of dynamic and static hip joint loads in subjects expected to be at peak bone mass. The bone mineral density (BMD) and bone mineral content (BMC) of three proximal femoral sites (neck, greater trochanter, and total) were measured by dual energy X-ray absorptiometry, and the peak external joint moments at the hip during walking and jogging were calculated from gait analyses of 31 normal human subjects ranging in age from 30 to 49 years (18 females, 13 males). Various multiple regression analyses were performed to determine how much of the variance in BMD and BMC was explained by height, body mass, and the peak hip joint moments. In total, the models explained up to 40% of the variance in BMD and 58% of the variance in BMC. Inclusion of height or body mass did not increase the explanatory power of the models for BMD and explained no more than 8% of the total variance in BMC once the joint moments from walking were allowed to enter the models. These data support the hypothesis that variance in peak bone mass is associated with variance in dynamic hip loads largely independent of the effect of static factors such as height and body mass.

Asymmetric knee loading in advanced unilateral hip osteoarthritis.

Subjects with unilateral end-stage hip osteoarthritis (OA) who undergo total hip replacement (THR) preferentially require subsequent replacement of the contralateral knee compared with the ipsilateral knee. We investigated whether this nonrandom, preferential evolution of lower extremity OA from the hip to the contralateral knee joint may be related to asymmetries in dynamic joint loading at the knees, particularly the peak external knee adduction moment, which has been associated with the progression of knee OA. Gait analysis was performed on 50 subjects who were preoperative for unilateral THR. Twenty-two of these subjects were reevaluated postoperatively 10-23 months after undergoing successful THR. At each analysis, dynamic joint loads in the contralateral knee were compared with those in the ipsilateral knee. Prior to THR, the peak external knee adduction moment and peak medial compartment load were significantly higher in the contralateral knee. This asymmetry persisted after THR. Subjects with unilateral end-stage hip OA preferentially require subsequent replacement of the contralateral knee, as compared with the ipsilateral knee. Among patients with unilateral end-stage hip OA, the contralateral knee is subjected to higher dynamic joint loads than is the ipsilateral knee, and this asymmetric loading persists long after subjects have undergone successful THR. Biomechanical factors appear to be involved in the multiarticular evolution of OA of the lower extremities.

Clinical assessment of musculoskeletal disorders in workers exposed to hand-arm vibration

To describe the clinical assessment of musculoskeletal disorders among vibration-exposed workers and to review the experimental and epidemiological studies of the effects of vibration on the musculoskeletal system of the upper limbs. A total of 212 references in English was found in Pub Med for the years 1980-2000 that dealt with clinical assessment. Many of these references were reviews and few were original research dealing with test performance in diagnostic procedures. The reported effects on bone are osteoporosis and cysts in the hands. Experiments have shown injuries to muscle cells in animals and additional physiological loading of muscles in humans by vibration. Low-frequency vibration exposure of high magnitude was associated with osteoarthrosis in the elbow, wrist and acromioclavicular joint and symptoms in the elbow and shoulder. Impacts, jerks and blows with high-energy transfer to the hands at low frequency might have the potential to result in musculoskeletal disorders considering the general model for injuries. Furthermore, the observed associations with vibration exposure and musculoskeletal disorders might result from the strong dynamic and static joint loading and the repetitive hand-arm motions required in tasks where hand-held machines are used. The clinical assessment of musculoskeletal disorders in workers exposed to hand-arm vibration consists of the clinical and exposure history and evaluation of the physical and laboratory findings. Since most patients with musculoskeletal disorders who are exposed to vibration are also exposed to other ergonomic stressors, accommodation of the injured worker has to take the whole work system into account (task, technology, environment and organisation). The scientific evidence that vibration per se is a risk factor for musculoskeletal disorders is still weak although there is strong evidence that job tasks with vibrating machines are associated with musculoskeletal disorders. The clinical assessment of musculoskeletal disorders in exposed patients imposes special requirements.

The knee adduction moment during gait in subjects with knee osteoarthritis is more closely correlated with static alignment than radiographic disease severity, toe out angle and pain

This study tested whether the peak external knee adduction moments during walking in subjects with knee osteoarthritis (OA) were correlated with the mechanical axis of the leg, radiographic measures of OA severity, toe out angle or clinical assessments of pain, stiffness or function. Gait analysis was performed on 62 subjects with knee OA and 49 asymptomatic control subjects (normal subjects). The subjects with OA walked with a greater than normal peak adduction moment during early stance ( p=0.027). In the OA group, the mechanical axis was the best single predictor of the peak adduction moment during both early and late stance ( R=0.74, p<0.001). The radiographic measures of OA severity in the medial compartment were also predictive of both peak adduction moments ( R=0.43 to 0.48, p<0.001) along with the sum of the WOMAC subscales ( R=−0.33 to −0.31, p<0.017). The toe out angle was predictive of the peak adduction moment only during late stance ( R=−0.45, p<0.001). Once mechanical axis was accounted for, other factors only increased the ability to predict the peak knee adduction moments by 10–18%. While the mechanical axis was indicative of the peak adduction moments, it only accounted for about 50% of its variation, emphasizing the need for a dynamic evaluation of the knee joint loading environment. Understanding which clinical measures of OA are most closely associated with the dynamic knee joint loads may ultimately result in a better understanding of the disease process and the development of therapeutic interventions.

Mechanical failure in total hip arthroplasty with cement

The long-term endurance of total hip arthroplasty (THA) depends on lasting mechanical integrity of the bond between implant and bone, the implant bone interface. If that bond, whatever its nature, is destroyed, the dynamic hip joint load produces relative motion between implant and bone. This results in inflammatory reactions, progressive interface bone resorption, fibrous-tissue interposition and, eventually, clinical loosening--this is the unchallenged adagium of successful THA. The question how to protect the interface from disintegrating is less easily answered. That is to say, there are answers in abundance, but there is no consensus. For most orthopaedic surgeons the matter is unresolved, not to say confused by manufacturers and inventors. 1'2 There is general consensus in the literature that two basic scenarios are likely to produce clinical failure to cemented interfaces) According to the particulate reaction scenario, wear particles (cement, polyethylene and metal) migrate in the interfaces, produce inflammatory reactions, and interface osteolysis and fibrous tissue interposition, which progressively debonds the cement from the bone. According to the accumulated damage scenario, the dynamic hip joint loads produce micro cracks in cement, implant cement and cement bone interfaces, relative motions, interface resorption and gradual debonding. These scenarios probably interact. Interface debonding by particulate reactions reduces the interface area available for load transfer, thus enhancing the probability of mechanical

Evaluation of Flowable Fly‐Ash Backfill. II: Dynamic Loading

This is the second paper in a two‐part series describing trench backfill tests designed to evaluate the performance of a flowable fly‐ash backfill (ashcrete) versus that of compacted soil backfills. The site for the tests is Duke Power's Marshall Steam Station. For these tests, a series of parallel trenches is installed in the outbound lane of an on‐site service road. The major use of this road is for the hauling of fly ash to an on‐site storage area. Instrumented pipes are installed in the trenches, which are subsequently backfilled using both compacted soil and ashcrete. Surface strains for the buried pipes and joint loads are monitored for static and dynamic loading conditions. The monitored dynamic strains and joint loads resulted from normal heavy‐vehicle traffic at the site. Comparative surface strain and joint‐load data are presented at two stages of compaction for the soil backfill and the ashcrete backfill. Additional strain data for the ashcrete backfill are included to demonstrate the continued performance of this backfill after additional curing. The project was designed to demonstrate the feasibility, advantages, and safety of using this flowable fly‐ash backfill in a typical continuous high‐load application.