Weight-bearing Stress Research Articles

Improvements in Vascular Function with Swimming vs. Cycling Training in Patients with Osteoarthritis

Osteoarthritis (OA) is the leading cause of disability in older adults and is associated with increased risk of vascular disease. Aerobic exercise is widely recommended for patients with OA, but OA and its associated joint pain acts as a significant barrier for performing a variety of land-based exercises. Swimming can be an ideal form of exercise for patients with OA adults as it includes minimum weight-bearing stress and reduced heat load. However, no study has investigated if swimming exercise improves markers of vascular function in patients with OA. PURPOSE: We compared the effects of swimming exercise and cycling exercise on key markers of vascular function, central arterial stiffness and endothelial vasodilatory function. METHODS: Forty-eight patients with OA were randomly assigned to swimming (n=24, age=59±8 yr) or cycling (n=24, age=61±4 yr) training groups. Supervised exercise was performed for 45 min/day 3 days/week at 60-70% heart rate reserve, for 12 weeks. Cycling training was included as a non-weight bearing land-based comparison group. Central arterial stiffness was determined by carotid-femoral pulse wave velocity. Brachial flow-mediated dilation (FMD) was used as a marker of endothelial vasodilatory function. RESULTS: Before the exercise interventions, there were no significant group differences in any of the physical characteristics and dependent variables. After 12-weeks of exercise training, carotid-femoral pulse wave velocity decreased significantly after both swimming (12.9±1.9 vs. 12.0±2.1 m/sec) and cycling (12.0±1.9 vs. 11.0±2.4 m/sec) training (both p<0.05). Brachial FMD increased significantly after swimming (3.0±3.5 vs. 6.0±4.0 %, p<0.05) but not after cycling training (2.9±3.1 vs. 3.3±3.2 %). CONCLUSION: Swimming exercise intervention was effective in reducing central arterial stiffness and improving endothelial dependent vasodilatory function in middle-aged and older adults with osteoarthritis. This is a clinically important finding since swimming is a desirable exercise mode for patients with OA in whom vascular disease is highly prevalent. Supported by the National Swimming Pool Foundation.

Primary bone cancer in Leonbergers may be associated with a higher bodyweight during adolescence

Weight-bearing stress may be a risk factor for both human and canine primary bone cancer. A cohort of Leonbergers (LB) was followed from birth to death and the cause of death recorded. We hypothesised that dogs dying due to primary bone cancer would be larger; measured by bodyweight (BW) and the circumference of the distal radius and ulna (CDRU) than those of the same breed that died of other causes. Information obtained from breeders, owners and veterinary surgeons were questionnaire-based. The dogs were examined by a veterinary surgeon at pre-specified “observational ages” (3, 4, 6, 12, 18, and 24m). Data were recorded, including BW and CDRU. The study population consisted of 196 LB, 9 of which died due to primary bone cancer (6 males, 3 females). Individual growth curves, showing BW and CDRU during the first 2 years of life, were made for these 9 dogs and compared to gender-specific mean values for LB that died from other causes. These curves showed that LB succumbing to primary bone cancer generally had a higher BW during the growth period than the remaining dogs, and that this difference appeared to be largest in the male LB. Male LB that developed primary bone cancer later in life also had a larger CDRU during most part of this period, as compared to those that did not develop this disease. Logistic regression showed a statistically significant effect of BW on the odds ratio of developing primary bone cancer at 12m and 18m and of CDRU at 18m, and a Poisson regression verified consistency of these results. At these ages, an increase in BW of 1kg yielded a nearly 20% higher risk of developing primary bone cancer, while a 1cm larger CDRU was associated with a nearly 70% increased risk. These findings support that weight-bearing stress during the period of high proliferative activity in the long bones associated with growth may increase the risk of canine primary bone cancer.

Optimal management of ankle syndesmosis injuries.

Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains), and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid) and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on controlling swelling and recovery from surgery. The protocols then progress to restoration of motion, early protected weight bearing, restoration of strength, and eventually a functional progression back to desired activities.

Prognosis of Ankle Syndesmosis Injury

Ankle syndesmosis injury has been associated with persistent pain and prolonged recovery; however, no predictors of prolonged recovery have been identified. The aims of this study were to establish prognosis for ankle syndesmosis injury compared with a lateral ankle sprain and to explore factors associated with prolonged recovery. Participants (n = 63) age 21 ± 3.2 yr, with acute ankle ligament injuries (diagnosed through magnetic resonance imaging), were recruited from 10 sport clubs and sports medicine and physiotherapy clinics in two Australian cities. Follow-up was until full recovery and with preinjury activity level. Time to return to play was compared between injury types using Kaplan-Meier survival curves. Secondary analysis investigated putative factors that increased risk of prolonged recovery. For this analysis, participants unrecovered at 2 wk completed the following: Fear Avoidance Beliefs Questionnaire (FABQ); Star Excursion Balance Test, weight-bearing lunge, and vertical jump (VJ). These variables were correlated with time to recovery using bivariate Pearson's r correlation coefficient. The median recovery time for conservatively treated ankle syndesmosis injury was 62 and 15 d for lateral sprain. The sport-specific subscale scores of the FABQ were significantly higher (P = 0.017) for the ankle syndesmosis group, whereas vertical jump height was lower for this group, (P = 0.052). No baseline variables were strong predictors (r ≥ 0.6) of recovery. Moderate correlations were found for VJ (r = -0.471, P = 0.004) and the sport-specific subscale of the FABQ (r = 0.463, P = 0.004). Conservatively treated ankle syndesmosis injuries took four times longer to recover than lateral ankle sprain. Tests such as VJ and FABQ may identify individuals at risk of prolonged recovery and allow health professionals to determine realistic and appropriate time to recovery.

Diabetic Foot Ulcerations: Biomechanics, Charcot Foot, and Total Contact Cast

Diabetes is the seventh leading cause of death in the United States; approximately 6% of the US population has been diagnosed with diabetes. Fifteen percent of all people with diabetes will develop a foot ulceration, and 14% to 20% of them will require an amputation. During the past 25 years, much has been learned and written about lower extremity complications associated with diabetes. The single most significant discovery relative to diabetic foot ulceration is the role of peripheral sensory neuropathy. Once the correlation between the absence of sensation and foot breakdown was made, treatment algorithms began to develop. For the first time, the concept of biomechanics and the role of weight-bearing stress were considered when applying different treatments to the patient with a diabetic foot ulcer. Wound classification systems developed to aid the physician in treating what had been a very frustrating group of patients; those with diabetic foot ulcerations. From that, a myriad of treatments developed. In fact, the technology of wound management became a billion dollar business and, to this day, continues to present the clinician with unending options to effectively manage and heal wounds on the diabetic lower extremity.

Impact of strut height on offloading capacity of removable cast walkers

BackgroundReducing weight-bearing stress to diabetic foot ulcers is critical to healing and commonly called offloading. Removable cast walkers are frequently used for offloading; however, patient compliance is often poor. Walkers commonly extend to the knee. Patients complain about walkers' weight and diminished balance with their use. This study compared the offloading capacity of walkers that varied by height. Heights included: knee, ankle, and shoe levels. To ensure a fair comparison the outsole and insole were standardized across the devices. MethodsEleven diabetic subjects with moderate to high risk of ulceration were recruited. Subjects completed four 20m walking trials. Subjects performed one trial with each walker and one trial with an athletic shoe. Primary outcomes focused on plantar loading and were measured by pressure insoles. Secondary outcomes were associated with gait kinematics as collected by body worn sensors. FindingsSignificant differences were found for the peak pressure and pressure time integrals of the different footwear. All walkers performed better than the athletic shoe. The ankle and knee-high devices performed best. Center of mass rotation data showed a trend of the ankle walker yielding a smaller range of motion (18% medial/lateral and 22% anterior/posterior) than the knee level. InterpretationThe ankle-high walker was able to provide similar offloading capacities as the knee-high walker. The diminished weight, along with potentially improved stability, may result in improved compliance with ankle-high walkers. A study comparing the use of the two devices for treating ulcers is now suggested.

Effects of Swimming Training on Blood Pressure and Vascular Function in Adults >50 Years of Age

Swimming is ideal for older adults because it includes minimum weight-bearing stress and decreased heat load. However, there is very little information available concerning the effects of regular swimming exercise on vascular risks. We determined if regular swimming exercise would decrease arterial blood pressure (BP) and improve vascular function. Forty-three otherwise healthy adults >50 years old (60 ± 2) with prehypertension or stage 1 hypertension and not on any medication were randomly assigned to 12 weeks of swimming exercise or attention time controls. Before the intervention period there were no significant differences in any of the variables between groups. Body mass, adiposity, and plasma concentrations of glucose and cholesterol did not change in either group throughout the intervention period. Casual systolic BP decreased significantly from 131 ± 3 to 122 ± 4 mm Hg in the swimming training group. Significant decreases in systolic BP were also observed in ambulatory (daytime) and central (carotid) BP measurements. Swimming exercise produced a 21% increase in carotid artery compliance (p <0.05). Flow-mediated dilation and cardiovagal baroreflex sensitivity improved after the swim training program (p <0.05). There were no significant changes in any measurements in the control group that performed gentle relaxation exercises. In conclusion, swimming exercise elicits hypotensive effects and improvements in vascular function in previously sedentary older adults.

Profiling microRNA expression in bovine articular cartilage and implications for mechanotransduction

Articular cartilage is an avascular tissue with precise polarity and organization comprising 3 distinct functional zones: the surface, middle, and deep zones. Each zone has a different gene expression pattern that plays a specific role in articular cartilage development and maintenance. MicroRNA (miRNA) are small noncoding gene products that play an important regulatory role in determining cell differentiation and function. The purpose of this study was to test our hypothesis that miRNA expression profiles in the different articular cartilage zones as well as between regions subjected to different levels of weight-bearing stresses are unique. Using an miRNA microarray approach in conjunction with quantitative reverse transcription-polymerase chain reaction, we identified miRNA in bovine articular cartilage that were differentially expressed in the different functional zones and in the anterior weight-bearing and posterior non-weight-bearing regions of the medial femoral condyle (M1 and M4, respectively). We identified miRNA-221 and miR-222 as part of a subset of differentially expressed miRNA that were up-regulated in articular cartilage in the anterior, M1, greater weight-bearing location. Additionally, miR-126, miR-145, and miR-335 were down-regulated in monolayers of tissue-cultured chondrocytes as compared with levels determined directly from intact native cartilage. In conclusion, miR-222 expression patterns in articular cartilage are higher in the weight-bearing anterior medial condyle as compared with the posterior non-weight-bearing medial condyle. Thus, miR-222 might be a potential regulator of an articular cartilage mechanotransduction pathway. These data implicate miRNA in the maintenance of articular cartilage homeostasis and are therefore targets for articular cartilage tissue engineering and regenerative medicine.

Differential gene expression associated with postnatal equine articular cartilage maturation

BackgroundArticular cartilage undergoes an important maturation process from neonate to adult that is reflected by alterations in matrix protein organization and increased heterogeneity of chondrocyte morphology. In the horse, these changes are influenced by exercise during the first five months of postnatal life. Transcriptional profiling was used to evaluate changes in articular chondrocyte gene expression during postnatal growth and development.MethodsTotal RNA was isolated from the articular cartilage of neonatal (0–10 days) and adult (4–5 years) horses, subjected to one round of linear RNA amplification, and then applied to a 9,367-element equine-specific cDNA microarray. Comparisons were made with a dye-swap experimental design. Microarray results for selected genes (COL2A1, COMP, P4HA1, TGFB1, TGFBR3, TNC) were validated by quantitative polymerase chain reaction (qPCR).ResultsFifty-six probe sets, which represent 45 gene products, were up-regulated (p < 0.01) in chondrocytes of neonatal articular cartilage relative to chondrocytes of adult articular cartilage. Conversely, 586 probe sets, which represent 499 gene products, were up-regulated (p < 0.01) in chondrocytes of adult articular cartilage relative to chondrocytes of neonatal articular cartilage. Collagens, matrix-modifying enzymes, and provisional matrix non-collagenous proteins were expressed at higher levels in the articular cartilage of newborn foals. Those genes with increased mRNA abundance in adult chondrocytes included leucine-rich small proteoglycans, matrix assembly, and cartilage maintenance proteins.ConclusionDifferential expression of genes encoding matrix proteins and matrix-modifying enzymes between neonates and adults reflect a cellular maturation process in articular chondrocytes. Up-regulated transcripts in neonatal cartilage are consistent with growth and expansion of the articular surface. Expression patterns in mature articular cartilage indicate a transition from growth to homeostasis, and tissue function related to withstanding shear and weight-bearing stresses.

The evolution of functional bracing of fractures

Functional fracture bracing, described in 1967,[1][1] was inspired by the patellar-tendon-bearing prosthesis which had recently been developed for below-knee amputees. This prosthesis had eliminated the traditional thigh corset and allowed the transfer of weight-bearing stresses from the soft

THE CLASSIC: Tibial Plateau Prosthesis

THE CLASSIC: Tibial Plateau Prosthesis

Age-related decrements in cycling and running performance

Objective. This study examined age-related decrements in athletic performance during running and cycling activities. Design. The age group winning times for males aged between 18 and 70 years competing in the 1999 Argus cycle tour (103 km) and 1999 Comrades running marathon (90 km), South Africa's premier endurance cycling and running events respectively, were examined. Main outcome measures. The relationship between speed (cycling and running respectively) and age was calculated using a 4th order polynomial function. The derivative of each of these functions was determined and then the slope of the function corresponding to each age was calculated. Results. The rate of decline in running speed occurred at an earlier age (~ 32 years) during the running race compared with the cycling tour (~ 55 years). Conclusions. These findings establish a trend that there is ‘accelerated' aging during running which can perhaps be attributed to the increased weight-bearing stress on the muscles during running compared with cycling. SA Sports Medicine Vol.16(2) 2004: 8-11

Age-related decrements in cycling and running performance

Objective. This study examined age-related decrements in athletic performance during running and cycling activities. Design. The age group winning times for males aged between 18 and 70 years competing in the 1999 Argus cycle tour (103 km) and 1999 Comrades running marathon (90 km), South Africa's premier endurance cycling and running events respectively, were examined. Main outcome measures. The relationship between speed (cycling and running respectively) and age was calculated using a 4th order polynomial function. The derivative of each of these functions was determined and then the slope of the function corresponding to each age was calculated. Results. The rate of decline in running speed occurred at an earlier age (~ 32 years) during the running race compared with the cycling tour (~ 55 years). Conclusions. These findings establish a trend that there is ‘accelerated' aging during running which can perhaps be attributed to the increased weight-bearing stress on the muscles during running compared with cycling. SA Sports Medicine Vol.16(2) 2004: 8-11

Kinematics of the distal tibiofibular syndesmosis

In 11 healthy volunteers, the normal kinematics of the tibiofibular syndesmosis of the ankle during weight bearing and external rotation stress were compared to a nonweight-bearing neutral position by radiostereometry. We found very small rotations and displacements in this “normal” group, which indicated that the fibula is closely attached to the tibia, thereby preventing larger movements at the level of the ankle. We found no common kinematic pattern during weight bearing in the neutral position.Application of a 7.5 Nm external rotation moment on the foot caused external rotation of the fibula between 2 and 5 degrees, medial translation between 0 and 2.5 mm and posterior displacement between 1.0 and 3.1 mm. These data can be used as normal reference values for studies of patients with suspected syndesmotic injuries.

Kinematics of the distal tibiofibular syndesmosis

In 11 healthy volunteers, the normal kinematics of the tibiofibular syndesmosis of the ankle during weight bearing and external rotation stress were compared to a nonweight-bearing neutral position by radiostereometry. We found very small rotations and displacements in this "normal" group, which indicated that the fibula is closely attached to the tibia, thereby preventing larger movements at the level of the ankle. We found no common kinematic pattern during weight bearing in the neutral position. Application of a 75 Nm external rotation moment on the foot caused external rotation of the fibula between 2 and 5 degrees, medial translation between 0 and 2.5 mm and posterior displacement between 1.0 and 3.1 mm. These data can be used as normal reference values for studies of patients with suspected syndesmotic injuries.

Pain Above the Injury Level

Pain above the injury level is predominantly musculoskeletal in origin and involves the structures of the upper extremity that must assume increased mobility and weight-bearing stresses in performance of transfers and wheelchair propulsion. This article discusses the recognition, diagnosis, and management of painful issues of the shoulder, elbow, wrist, and hand. A brief discussion is presented on pain entities that are familiar to pain treatment centers but possibly not to other health care workers, namely chronic fatigue syndrome and facet syndrome.

Limb salvage with Chopart's amputation and tendon balancing.

For several decades, Chopart's amputation has met with some skepticism owing to reports of significant equinus deformity developing soon after the procedure is performed. However, with appropriate tendon balancing, which generally includes anterior tibial tendon transfer and tendo Achillis lengthening, this level of amputation is often more functional than slightly more distal amputations, such as Lisfranc or short transmetatarsal amputations. The authors offer a rationale for this observation, which includes a discussion of the longitudinal and transverse arch concept of the foot. This concept dictates that the shorter the midfoot-level amputation, the more likely the patient is to develop an equinovarus deformity, thus exposing the fifth metatarsal base and cuboid to weightbearing stress and a high risk of ulceration. Chopart's amputation, in eliminating the cuboid, often obviates the potential varus deformity and thus can have a more acceptable long-term result.

Surgery of the rheumatoid foot and ankle.

Numerous reconstructive procedures have been used to address the manifestations of rheumatoid arthritis in the foot and ankle. Clinical studies have documented that these procedures relieve pain, however they often sacrifice motion essential to the normal function of the foot. In the forefoot, metatarsophalangeal joint resection arthroplasty shortens the lever arm of the foot, defunctions the toes, and disables the plantar plate and fat pad. Arthrodesis of the ankle and hindfoot alters gait and the effective transmission of weight-bearing stresses through the foot and ankle. These ablative procedures may provoke the deterioration of adjacent joints and may cripple the long-term function of the lower extremity. The introduction of reconstructive procedures designed to preserve motion in joints essential to function and the recognition and treatment of muscle imbalances associated with bone and joint deformities are recent advances in the surgical management of the rheumatoid foot and ankle.

Orthopedic surgical management of skeletal complications of malignancy.

Coincident with improved overall cancer palliation during the past 2 decades has been an increasing incidence of clinically apparent bone metastases, and from these metastases subsequent pathologic fractures of the long bones, spine, and pelvis. Current techniques for surgical management of these fractures are extremely effective in alleviating pain and allowing patients to resume an ambulatory status, often without the need of external support. This, in turn, has significantly improved the quality of the remaining months or years of these individuals' lives. In fact, the long term survival of patients after their first long bone pathologic fracture from malignancy has more than tripled for the most common cancers (breast carcinoma, prostate carcinoma, lymphomas, and myelomas) during the past 25 years. Surgical techniques for stabilizing pathologic or impending fractures must be individualized for the area of involvement, the particular qualities of the bone involved, and the potential for involvement of adjacent soft tissue structures. Long bone fractures most commonly occur in the femur and humerus and are typically internally fixed by intramedullary devices that control impaction, distraction, and torquing stresses by the use of proximal and distal interlocking fixation. Such fixation must be able to withstand weight-bearing stresses on lower extremity long bones. Upper extremity pathologic fractures are often subjected to distractive forces inherent in lifting and pulling, but they are also subjected to heavy compressive forces, particularly in patients who require crutches or other devices to assist them in walking. Fixation of upper or lower extremity long bone fractures ordinarily may be accomplished with minimal blood loss or morbidity. In contrast, fractures or impending fractures involving the acetabulum necessitate extensive joint reconstruction, with inherent increased potential for morbidity and complications. For this reason, the anticipated prognosis for survival and mobility should be greater preoperatively for patients with acetabular fractures than for patients with fractures of either upper or lower extremity long bones. Most spinal metastases can be managed conservatively. Those requiring surgical intervention present with progressive neurologic compromise, which requires decompression, or spinal instability, which requires stabilization. Constructs for internal stabilization of the spine must not be adversely affected by local postoperative irradiation. Ninety-six percent of patients experience good or excellent relief of pain after internal fixation of pathologic malignant long bone fractures. Eighty-four percent of patients with acetabular fractures experience good or excellent relief of pain after joint reconstruction. Eighty-two percent of patients with neurologic compromise secondary to vertebral malignancy improve at least one functional grade after decompression and stabilization, and 88% experience good or excellent relief of spinal pain with restoration of walking ability. Thirty-two percent survived for more than 2 years after spinal decompression and stabilization. Patients with pathologic fractures from metastatic carcinoma of the breast had a mean survival of 24.6 months after surgical management of their fractures. There was a similarly encouraging improvement in the survival statistics for patients with other primary tumor types. Most malignant pathologic fractures of the pelvis, long bones, or spine are amenable to effective stabilization by the techniques described in this article. These techniques allow resumption of weight-bearing ambulation in all but a few patients, good or excellent relief of pain in the vast majority, and an enhanced anticipation of survival and improvement in quality of life.

Rotational acetabular osteotomies: a rabbit model.

We investigated the morphological changes in the articular cartilage after rotational acetabular osteotomy in 16 adolescent rabbits. Radiological and histological studies were conducted at 12 and 24 weeks postoperatively. The radiological evaluations at 12 and 24 weeks showed significantly increased femoral head coverage. No cases of osteonecrosis of the acetabulum or femoral head nor narrowing of the joint space was observed. The histology of the articular cartilage at 12 weeks postoperatively showed cloning and hypercellularity of the chondrocytes in the medial portion of the acetabular roof, indicating remodelling due to the increased weight-bearing stress caused by the osteotomy. The histology at 24 weeks postoperatively showed less cloning of the chondrocytes, indicating that the remodelling process in the articular cartilage induced by this procedure was almost complete at 24 weeks. Degeneration of the articular cartilage was not observed within 24 weeks of the operation.