Acute Lower Extremity Fracture Management in Chronic Spinal Cord Injury: 2022 Delphi Consensus Recommendations.

Our objective was to develop a clinical practice guideline (CPG) for the treatment of acute lower extremity fractures in persons with a chronic spinal cord injury (SCI). Methods: Information from a previous systematic review that addressed lower extremity fracture care in persons with an SCI as well as information from interviews of physical and occupational therapists, searches of the literature, and expert opinion were used to develop this CPG. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to determine the quality of evidence and the strength of the recommendations. An overall GRADE quality rating was applied to the evidence. Conclusions: Individuals with a chronic SCI who sustain an acute lower extremity fracture should be provided with education regarding the risks and benefits of operative and nonoperative management, and shared decision-making for acute fracture management should be used. Nonoperative management historically has been the default preference; however, with the advent of greater patient independence, improved surgical techniques, and advanced therapeutics and rehabilitation, increased use of surgical management should be considered. Physical therapists, kinesiotherapists, and/or occupational therapists should assess equipment needs, skills training, and caregiver assistance due to changes in mobility resulting from a lower extremity fracture. Therapists should be involved in fracture management as soon as possible following fracture identification. Pressure injuries, compartment syndrome, heterotopic ossification, nonunion, malunion, thromboembolism, pain, and autonomic dysreflexia are fracture-related complications that clinicians caring for patients who have an SCI and a lower extremity fracture may encounter. Strategies for their treatment are discussed. The underlying goal is to return the patient as closely as possible to their pre-fracture functional level with operative or nonoperative management.

Post-exercise heart rate recovery in individuals with spinal cord injury.

STUDY DESIGN: Prospective comparison of spinal cord injured (SCI) subjects and ambulatory subjects. OBJECTIVES: To determine the effects of the presence and level of SCI on heart rate recovery (HRR). SETTING: Outpatient SCI center. METHODS: HRR was determined in 63 SCI subjects (26 with tetraplegia, 22 with high-level paraplegia, 15 with low-level paraplegia) and 26 ambulatory subjects. To adjust for differences in heart rate reserve between groups (HR peak minus HR rest), HRR was also 'normalized' to a range of 1 at peak heart rate and to 0 at 8 min, and the shapes of HRR curves were compared. RESULTS: Although absolute HRR was similar between high- and low-level paraplegia, it was significantly more rapid in participants with paraplegia at 2, 5 and 8 min after exercise than in those with tetraplegia (39+/-14 vs 29+/-14 b.p.m., P<0.05; 51+/-14 vs 33+/-16 b.p.m., P<0.01 and 52+/-16 vs 36+/-17 b.p.m., P<0.01, respectively). HRR among ambulatory subjects was more rapid than among those with tetraplegia at all time points in recovery. However, when normalized for heart rate reserve, HRR was significantly more rapid in tetraplegic subjects (P<0.001 vs paraplegia and ambulatory subjects). CONCLUSION: In SCI, HRR is strongly associated with the peak exercise level and peak heart rate achieved during exercise testing.

Homocysteine and hypertension in persons with spinal cord injury.

STUDY DESIGN: Cross-sectional analysis of a convenience sample of locally recruited participants, including both patients and volunteers. OBJECTIVES: To determine whether there is an association between plasma homocysteine and hypertension in persons with spinal cord injury (SCI). SETTING: Spinal Cord Injury Service of the Veterans Affairs Palo Alto Medical Center (California, United States of America). METHODS: The incidence of hypertension, dyslipidemia, insulin resistance, and the presence of metabolic syndrome were determined in 168 individuals with SCI (mean age 50.2 +/- 12.8 years). Fasting lipids, insulin, glucose, plasma homocysteine, and anthropometric data was gathered for each subject. RESULTS: Blood pressure values (P < 0.001) and mean arterial pressure (P < 0.05) increased with higher plasma homocysteine levels. Homocysteine values were also significantly greater among individuals with hypertension compared with those who were normotensive or prehypertensive (P < 0.0001). There was an inverse relationship between plasma homocysteine levels and glomerular filtration rate and effective renal plasma flow (P < 0.05). CONCLUSIONS: Plasma homocysteine levels are elevated in persons with SCI who have hypertension and inversely related to renal function, which suggests that renal dysfunction may be a link between homocysteine and hypertension in persons with SCI. SPONSORSHIP: Funded by the VA Rehabilitation Research and Development Service, Merit Review Grant #B2549R.

Progressive decrease in bone density over 10 years of androgen deprivation therapy in patients with prostate cancer.

OBJECTIVES: Several reports suggest an increased incidence of osteoporosis and concomitant fractures in men receiving androgen deprivation therapy (ADT) for prostate cancer. We sought to estimate the longitudinal effects of ADT on loss of bone density in this cross-sectional study. METHODS: Hip and spine bone mineral density (BMD) studies were performed by dual-energy x-ray absorptiometry on 36 patients with prostate cancer. The year 0 cohort (n = 8) consisted of patients who had not yet begun planned ADT. These men were compared to patients receiving ADT who underwent BMD evaluation at year 2 (n = 6), year 4 (n = 7), year 6 (n = 5), year 8 (n = 5), and year 10 (n = 5) of therapy. All BMD values for the patients with prostate cancer were compared to age-matched control subjects. RESULTS: Hip BMD was significantly lower in patients on ADT (mean BMD 0.802 g/cm(2)) compared with those not on ADT (mean BMD 0.935 g/cm(2)). Patients at year 0 had hip and spine BMD similar to age-matched control subjects. There was a significant trend for decreased hip BMD with increasing years of ADT (r = 0.46, P = 0.00008). This relationship was more dramatic when hip BMD at each time point was compared to age-matched control subjects (r = 0.55, P = 0.5 x 10(-16)). This bone loss was evident even up to year 10. BMD loss was more dramatic in patients who had undergone surgical castration than those receiving medical ADT (P = 0.08). Patients on intermittent ADT had similar BMD loss as patients on continuous ADT at year 2 and year 4 but demonstrated less bone loss at year 6 (P = 0.07) despite equivalently low testosterone levels. CONCLUSIONS: There is diminished BMD with increasing duration of ADT. Continuous ADT and surgical castration may be more deleterious than medical therapy, particularly when the medical therapy is given in an intermittent fashion.

Bone mineral and geometric changes through the femur with immobilization due to spinal cord injury.

This cross-sectional study describes bone mineral and geometric properties of the midshaft and distal femur in a control population and examines effects of immobilization due to spinal cord injury (SCI) at these skeletal sites. The subject populations were comprised of 118 ambulatory adults (59 men and 59 women) and 246 individuals with SCI (239 men and 7 women); 30 of these were considered to have acute injury (SCI duration <1 year). Bone mineral density (BMD) was assessed at the femoral neck, and midshaft and distal femur by dual energy absorptiometry. Geometric properties, specifically cortical area, polar moment of inertia, and polar section modulus, were estimated at the midshaft from cortical dimensions obtained by concurrent radiography. Reduction in BMD was noted in all femoral regions (27%, 25%, and 43% for femoral neck, midshaft, and distal femur, respectively) compared with controls. In contrast, although endosteal diameter was enlarged, geometric properties were not significantly reduced in the midshaft attributable to the age-related increase in periosteal diameter. These results suggest that simultaneous assessment of bone mineral and geometric properties may improve clinically relevant evaluation of skeletal status.

Mechanobiology of femoral neck structure during adolescence.

Understanding femoral neck structure may be critical to preventing fractures at this site. We examined the correlates of changes in the femoral neck during adolescence. Dual energy x-ray absorptiometry measurements of proximal femora were made in 101 Caucasian youths (ages 9 to 26 years). Relationships were examined between developmental parameters (age, pubertal stage, height, body mass, lean mass, and fat mass) and femoral structure (bone mineral content, bone mineral density, neck width, cross-sectional area, and cross-sectional strength). Lean body mass was the best predictor of femoral neck structure, explaining 53-87 percent of the variance, and was independent of gender. Body mass only explained 51-79 percent of the variance. Previously we found body mass to be the strongest predictor of femoral mid-diaphyseal cross-sectional properties. These findings suggest that trabecular bone of the femoral neck may be more responsive to its mechanical environment than the cortical diaphysis. In addition, lean body mass may be a more reliable predictor of muscle loading than body mass.

DXA-derived section modulus and bone mineral content predict long-bone torsional strength.

Previous studies have used dual energy x-ray absorptiometry (DXA) scans to calculate the section modulus (Z) of adolescent and adult human femurs. The DXA-derived values of Z were assumed to be proportional to bone strength in bending and torsion. In this study we used dog (n 5), pig (n 4), and human (n 13) femurs covering a linear bone mineral content (BMCL) range of 0.91-6.1 g/cm. Using DXA scans, ex vivo torsional strength tests, and torsional finite element models, we assessed the validity of using the DXA-derived Z value as an indicator of strength. The correlation between BMCL and strength was r2 = 0.87 and the correlation between Z and strength was r2 = 0.86. Based on finite element results, the dog and pig section moduli were adjusted to be comparable to the human data based on cross-sectional shape and bone tissue shear strength differences. With these adjustments, the correlation between adjusted section modulus and measured strength did not improve (r2 = 0.87). These data indicate that DXA-derived section modulus can be used to predict strength over a wide range of bone sizes. However, a clear advantage of using DXA-derived section modulus rather than BMCL could not be found.

Effect of spinal cord injury on the heart and cardiovascular fitness.

The use of various FES protocols to encourage increases in physical activity and to augment physical fitness and reduce heart disease risk is a relatively new, but growing field of investigation. The evidence so far supports its use in improving potential health benefits for patients with SCI. Such benefits may include more efficient and safer cardiac function; greater stimulus for metabolic, cardiovascular, and pulmonary training adaptations; and greater stimulus for skeletal muscle training adaptations. In addition, the availability of relatively inexpensive commercial FES units to elicit muscular contractions, the ease of use of gel-less, reusable electrodes, and the increasing popularity of home and commercial upper body exercise equipment mean that such benefits are likely to be more accessible to the SCI population through increased convenience and decreased cost. The US Department of Health and Human Services has identified those with SCI as a "special population" whose health problems are accentuated, and so need to be specifically addressed. FES presents "a clear opportunity.... For health promotion and disease prevention efforts to improve the health prospects and functional independence of people with disabilities." As a corollary to this, the Centers for Disease Control and Prevention have recommended the development of techniques to prevent or ameliorate secondary disabilities in persons with a SCI. Patients with SCI have an increased susceptibility to cardiac morbidity and mortality in the acute and early stages of their injury. Most of these patients make an excellent adaptation except when confronted with infection or hypoxia. SCI by itself does not promote atherosclerosis; however, in association with multiple secondary conditions related to SCI, along with advancing age, patients with SCI are predisposed to relatively greater risk of heart disease. The epidemiologic significance of this is reflected in demographic studies that indicate an increasing number of SCI patients becoming aged. Currently 71,000 (40%) of the total 179,000 patients with SCI living in the United States are older than 40 years, and 45,000 have injuries sustained more than 20 years earlier. In addition, new injuries in the older population are increasing (currently 11% of all injuries), and some of these new patients with SCI already have pre-existing cardiac disease. Studies have demonstrated that improved lifestyle, physical activity, lipid management, and dietary restrictions can affect major risk factors for coronary artery disease. Therefore an aggressive cardiac prevention program is appropriate for patients with SCI as part of their rehabilitation. At a given submaximal workload, arm exercise is performed at a greater physiologic cost than is leg exercise. At maximal effort, however, physiologic responses are generally greater in leg exercise than arm exercise. Arm exercise is less efficient and less effective than lower body exercise in developing and maintaining both central and peripheral aspects of cardiovascular fitness. The situation is further compounded in SCI because of poor venous return as a result of lower-limb blood pooling, as a result of lack of sympathetic tone, and a diminished or absent venous "muscle pump" in the legs. This latter mechanism perhaps contributes the greatest diminution in the potential for aerobic performance in the SCI population. Obtaining a cardiopulmonary training effect in individuals with SCI is quite possible. Current studies indicate decreases in submaximal HR, respiratory quotient, minute ventilation, and oxygen uptake, with increases in maximal power output, oxygen uptake, minute ventilation, and lactic acid. Individuals with SCI have been shown to benefit from lower limb functional electrical stimulation (FES)-induced exercise. Studies have consistently reported increases in lower limb strength and cycle endurance performance with these protocols, as well as improvements in metabolic and

Body mass is the primary determinant of midfemoral bone acquisition during adolescent growth.

To study the determinants of bone mass and structure during adolescence, we analyzed the femoral mid-diaphysis of 375 healthy adolescents and young adults, ages 9-26 years, from four ethnic cohorts (African-American, Asian-American, Caucasian, and Hispanic). Whole-body dual-energy X-ray absorptiometry (DXA) scans were used to determine diaphyseal length and mid-diaphyseal diameter of the left femur, as well as linear bone mineral content (BMCL) of a region at the mid-diaphysis. Cross-sectional geometric properties were estimated and used to calculate two structural strength indicators: the section modulus and the whole bone strength index. When the relationships between the bone measurements and age, pubertal group, height, or body mass were evaluated, all cross-sectional femoral measures correlated most strongly with body mass. Multiple regressions accounting for gender and ethnicity provided little additional predictive value over the simple regressions with body mass alone. Furthermore, accounting for all developmental parameters (age, pubertal group, body mass, lean body mass, calcium intake, physical activity level) as well as ethnicity and gender in a single saturated model also did not generally significantly improve the predictive results achieved using only body mass. Our results indicate that increases in midfemoral bone mass and cross-sectional properties during adolescence are primarily related to increases in mechanical loading as reflected by body mass.

Measurement of bone mineral density by dual-energy x-ray absorptiometry in patients with the Wisconsin hip, an uncemented femoral stem.

Although qualitative evidence of femoral bone remodeling, secondary to total hip arthroplasty (THA), is apparent on radiographs, quantification of change in bone mass from radiographs is limited. Dual-energy x-ray absorptiometry overcomes many of the limitations and yields accurate and precise bone mineral density (BMD) data. In this study, regional changes in femoral BMD were examined in 89 THA patients with a 2-year follow-up period. Thirty-two patients were evaluated initially before surgery and followed through the first 2 postoperative years. A second group was comprised of 57 patients whose surgery had been performed 1 to 6 years prior to entry into the study; they were also followed for 2 years hence. Thus, both immediate and later bone responses were evaluated prospectively. Maximal bone remodeling was seen in the first 6 months after THA and with a near plateau by the end of the first year. A slow yearly decline in BMD appeared to occur as long as 8 years after THA, thus demonstrating the long-term effects of the introduction of a femoral stem. Variance in preoperative BMD was explained by disease only; no other factors (age, weight, sex) showed significant associations, and body weight was the only variable that affected rate of remodeling after THA (not age, weight, sex, prosthesis size, nor disease). All patients were healthy, relatively young individuals who were good candidates for uncemented implantation, and none showed evidence of clinical complications or surgical failure. It is therefore suggested that the patterns and results reported here be viewed as normative data, that is, the typical skeletal adaptation to THA. In future application, observation of disparate BMD results as compared with these "normal" data may be predictive of abnormal response to surgery and potential for later problems.

Noninvasive determination of bone mechanical properties using vibration response: a refined model and validation in vivo.

Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical response tissue analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on the relative accelerations of the probe and bone. The previous mathematical model of the bone and overlying tissue system was reconfigured to incorporate the theoretical finding. This newer model (six-parameter) was used to interpret results using MRTA to determine bone cross-sectional bending stiffness, EIMRTA. The relationship between EIMRTA and theoretical EI values for padded aluminum rods was R2 = 0.999. A biological validation followed using monkey tibias. Each bone was tested in vivo with the MRTA instrument. Postmortem, the same tibias were excised and tested to failure in three-point bending to determine EI3-PT and maximum load. Diaphyseal bone mineral density (BMD) measurements were also made. The relationship between EI3-PT and in vivo EIMRTA using the six-parameter model is strong (R2 = 0.947) and better than that using the older model (R2 = 0.645). EIMRTA and BMD are also highly correlated (R2 = 0.853). MRTA measurements in vivo and BMD ex vivo are both good predictors of scaled maximum strength (R2 = 0.915 and R2 = 0.894, respectively). This is the first biological validation of a non-invasive mechanical measurement of bone by comparison to actual values. The MRTA technique has potential clinical value for assessing long-bone mechanical properties.

Determinants of femoral geometry and structure during adolescent growth.

Our goal was to understand developmental determinants of femoral structure during growth and sexual maturation by relating femoral measurements to gender and developmental factors (age, pubertal stage, height, and body mass). The bone mineral content of the femur was measured by dual energy x-ray absorptiometry in 101 healthy Caucasian adolescents and young adults, 9-26 years of age. After some simplifying assumptions had been made, cross-sectional geometric properties of the femoral midshaft were estimated. Two geometry-based structural indicators, the section modulus and whole bone strength index, were calculated to assess the structural characteristics of the femur. Femoral strength, as described by these structural indicators, increased dramatically from childhood through young adulthood. Regressions were performed between these femoral measurements and the developmental factors. Our data show that of age, pubertal stage, body mass, and height, body mass is the strongest predictor of femoral cross-sectional properties, and the correlation of body mass with femoral cross-sectional structure is independent of gender. A model including all four developmental factors and gender did not substantially increase the accuracy of predictions compared with the model with body mass alone. In light of previous research, we hypothesize that body mass is an indicator of in vivo loading and that this in vivo loading influences the cross-sectional growth of the long bones.

Determination of bone mineral density by dual x-ray absorptiometry in patients with uncemented total hip arthroplasty.

Bone remodeling is an expected sequela with total hip arthroplasty (THA). Although there are several methods of estimating bone response in THA patients from radiographs, there are no accurate and generally accepted methods for quantitative determinations in vivo. In this study, we describe an application of dual x-ray absorptiometry (DXA) for measuring bone mineral content and bone mineral density in the proximal femur following THA. DXA is a noninvasive technique with minimal radiation exposure (< 5 mrem). Various aspects of measurement error (accuracy and reliability) of this application of DXA were determined in a series of studies reported here. Accuracy error (how similar are the measured and actual values) was < 1% determined in bone phantoms of four densities. Precision error (how reproducible are the measurements) was also < 1% at all four densities in the phantoms and was only slightly elevated (0.9-1.5%) in repeated measurements of implanted cadaver femora. Precision error in vivo, determined both from multiple replicates on five patients and from duplicate scans on 30 patients, was further elevated but remained < 5%. Contributions to precision error, rotation of the leg, and interoperator variability were assessed; none was found to elevate precision error appreciably. We suggest that DXA is a feasible method for quantifying bone response following THA, and will allow discrimination of small changes (> 5%) not previously measurable.

Mechanical effects of sodium fluoride on bovine cortical bone.

Seventeen 5 to 6-month-old Holstein heifer calves were divided into three groups and fed either a control ration alone or a control ration with sufficient sodium fluoride added to furnish an additional 30 or 50 p.p.m. fluoride based on total dry matter intake. After 6 years of the feedings, mean (SEM) fluoride concentrations in the metacarpals were found to be 594.6 (66.2), 2663.8 (319.2), and 4500.0 (417.8) p.p.m. Bone mineral density and mechanical evaluations were also conducted on the harvested metacarpals after the 6-year period. Using dual energy X-ray absorptiometry, mean (SEM) bone mineral densities of 3.030 (0.26), 2.801 (0.34), and 2.456 (0.19) g cm(-2) for the control group, the group receiving 30 p.p.m. fluoride, and the group receiving 50 p.p.m. respectively were found. For the mechanical testing, specimens were cut and tested in compression parallel to the long axis of the metacarpals. Mean (SEM) ultimate stress of 204.53 (3.63), 208.83 (5.25), and 205.93 (5.12) MPa and mean (SEM) Young's elastic moduli of 20.82 (1.52), 22.68 (2.38), and 21.55 (1.60) GPa for the control, the 30 p.p.m., and the 50 p.p.m. fluoride groups respectively were determined. No significant differences were found between control and treatment groups for either mechanical properties or bone mineral density.

Dual photon absorptiometry of the proximal tibia.

Bone mineral content (BMC) and bone mineral density (BMD) of the proximal tibia were determined by dual photon absorptiometry on 44 women, aged 23-87 years. The area of the tibia measured was a 2.01 cm region immediately distal to the medial and lateral tuberosities. Values of BMC ranged between 5.09 and 14.57 g and BMD between 0.380 and 1.180 g/cm2. Both tibial BMC and BMD declined with age and tibial BMD was significantly correlated with lumbar spine (r = 0.70), femoral neck (r = 0.73), and femoral trochanter (r = 0.74). However, the large standard errors of estimate (SEE) (0.08-0.14 g/cm2) do not allow for reliable prediction in an individual of other skeletal sites by the tibia. Repeated measurements demonstrated that dual photon absorptiometry of the proximal tibia is a reliable measurement and may be a useful tool in the monitoring of therapeutic or intervention modalities in those individuals with skeletal diseases in whom measurement of the lumbar spine or proximal femur may not be possible.