vendex and Hip-Fractures

To study the effects of resistance training on muscle strength parameters, mobility, and balance.. Randomized controlled trial.. Research laboratory and senior gym.. Population-based sample of eligible 60- to 85-year-old community-dwelling men and women 0.5 to 7.0 years after hip fracture. Forty-six people had no contraindications and were willing to participate in the exercise trial.. Twelve-week intensive progressive strength-power training (n=24), aiming to reduce asymmetric deficit in leg muscle strength and power, or no intervention (n=22).. Isometric knee extension torque (KET) and leg extension power (LEP) measured in the weaker and stronger leg and the asymmetric deficit ([weak/sum both legs]x100%), 10-m walking speed, dynamic balance test, and self-reported outdoor mobility.. KET increased in both legs (P<.021), LEP tended to increase in the weaker leg (P=.071), and asymmetric LEP deficit decreased (P=.010) after training compared with the control group. LEP of the stronger leg, asymmetric KET deficit, walking speed, and balance performance were not significantly affected by training. Self-reported ability to walk outdoors improved after training. The compliance to the training was over 90%, and few adverse events (n=4; mainly musculoskeletal) were likely to be caused by the training.. Intensive resistance training is feasible for people with a hip fracture and improved muscle strength and power. More intensive training especially for the weaker leg may be needed to obtain more marked effects on asymmetric deficit, mobility, and balance. Also, the timing and duration of training program should be considered. (ISRCTN identifier ISRCTN34271567.)

Topics: Aged; Aged, 80 and over; Analysis of Variance; Anthropometry; Chi-Square Distribution; Exercise Therapy; Female; Hip Fractures; Humans; Lower Extremity; Male; Middle Aged; Mobility Limitation; Muscle Strength; Recovery of Function; Torque; Treatment Outcome; Walking; Weight-Bearing

Effects of clockwise torque rotation onto proximal femoral fracture fixation have been subject of ongoing debate: fixated right-sided trochanteric fractures seem more rotationally stable than left-sided fractures in the biomechanical setting, but this theoretical advantage has not been demonstrated in the clinical setting to date. The purpose of this study was to identify a difference in early reoperation rate between patients undergoing surgery for left- versus right-sided proximal femur fractures using cephalomedullary nailing (CMN).. The American College of Surgeons National Surgical Quality Improvement Program was queried from 2016-2019 to identify patients aged 50 years and older undergoing CMN for a proximal femoral fracture. The primary outcome was any unplanned reoperation within 30 days following surgery. The difference was calculated using a Chi-square test, and observed power calculated using post-hoc power analysis.. In total, of 20,122 patients undergoing CMN for proximal femoral fracture management, 1.8% (n=371) had to undergo an unplanned reoperation within 30 days after surgery. Overall, 208 (2.0%) were left-sided and 163 (1.7%) right-sided fractures (p=0.052, risk ratio [RR] 1.22, 95% confidence interval [CI] 1.00-1.50), odds ratio [OR] 1.23 (95%CI 1.00-1.51), power 49.2% (α=0.05).. This study shows a higher risk of reoperation for left-sided compared to right-sided proximal femur fractures after CMN in a large sample size. Although results may be underpowered and statistically insignificant, this finding might substantiate the hypothesis that clockwise rotation during implant insertion and (postoperative) weightbearing may lead to higher reoperation rates.. Therapeutic level II.

Topics: Aged; Bone Nails; Femoral Fractures; Femur; Fracture Fixation, Intramedullary; Hip Fractures; Humans; Middle Aged; Proximal Femoral Fractures; Reoperation; Retrospective Studies; Torque; Treatment Outcome

Hydroxyapatite (HA) augments are frequently used in orthopedic surgery. However, the effectiveness of HA augments on the treatment of intertrochanteric femoral fractures remains unknown. This study aimed to investigate whether the use of HA tubes affects the intraoperative insertion torque of the lag screw during intertrochanteric femoral fracture surgery.. From January 2016 to October 2020, 58 patients with intertrochanteric femoral fractures were included and divided into the HA treatment group (HA group, n = 29) and non-HA treatment group (N group, n = 29). Patients with intertrochanteric femoral fractures were treated using the Gamma3 nail system® with or without two HA tubes. HA tubes were inserted into the femoral head through the lag screw hole before the insertion of the lag screw. The mean and maximum intraoperative insertion torques of the lag screw, bone mineral density (BMD) of the uninjured opposite side femoral neck, and tip apex distance (TAD) of the lag screw on postoperative radiographs were assessed. To assess the loss of reduction after the surgery, we investigated the amounts of telescoping of the lag screw and the changes in the neck shaft angle.. The mean and maximum insertion torques were correlated with BMD in the HA and N groups, respectively. The mean and maximum insertion torques were not correlated with TAD in the HA and N groups, respectively. The mean torque/BMD ratio was significantly higher in the HA group than in the N group (p = 0.03). There were no significant differences in the maximum torque/BMD ratio between HA and N groups (p = 0.06), while the maximum torque/BMD ratio tended to be higher in the HA group than in the N group. The amounts of telescoping of the lag screw in the HA group were significantly lower than that in the N group (p = 0.04), while there were no significant differences in the changes in the neck shaft angle between two groups (p = 0.32).. Our results strongly suggest that the use of HA tubes increases the intraoperative lag screw insertion torque/BMD ratio and may improve the lag screw fixation by strengthening the bone/metal thread interface in the treatment of intertrochanteric femoral fractures.

Topics: Bone Nails; Bone Screws; Durapatite; Femoral Fractures; Fracture Fixation, Intramedullary; Hip Fractures; Humans; Torque; Treatment Outcome

Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances.. Synthetic femora with canals drilled to 18 mm were used. Five fixation types were examined: a 2 - hole and a 4 - hole Dynamic Hip Screw with a 2 - hole plate, a standard gamma nail with dynamic and static distal locking and a long gamma nail. The specimens were tested with cyclic axial loading, from 500 N increasing of 50 N increments in each cycle. Force at failure, overall stiffness, stiffness at the fracture site, location and mode of failure were recorded.. The short gamma nails dislocated into varus under preload because the nail migrated laterally. The Dynamic Hip Screw was initially stable, but some specimens rotated around the lag screw. The gamma nail was rotationally stable. Both implants failed through femur fracture. The long gamma nailed failed by screw cut - out at forces lower than the ultimate force of the short gamma nail.. This study shows that the gamma nail is unstable in a large medullary canal but offers better rotational stability of the proximal fragment. A modification of the nail design or the operative technique may be considered.

Topics: Biomechanical Phenomena; Bone Nails; Bone Plates; Bone Screws; Equipment Design; Femoral Fractures; Femur; Fracture Fixation, Internal; Fracture Fixation, Intramedullary; Gamma Rays; Hip Fractures; Humans; Pressure; Prosthesis Failure; Range of Motion, Articular; Torque; Weight-Bearing

This study evaluated whether patients with a left-sided femoral neck fracture (FNF) treated with a sliding hip screw (SHS) had a higher implant failure rate than patients treated for a right-sided FNF. This was performed to determine the clinical relevance of the clockwise rotational torque of the femoral neck lag screw in a SHS, in relation to the rotational stability of left and right-sided FNFs after fixation.. Data were derived from the FAITH trial and Dutch Hip Fracture Audit (DHFA). Patients with a FNF, aged ≥50, treated with a SHS, with at least 3-month follow-up data available, were included. Implant failure was analyzed in a multivariable logistic regression model adjusted for age, sex, fracture displacement, prefracture living setting and functional mobility, and American Society for Anesthesiologists Class.. One thousand seven hundred fifty patients were included, of which 944 (53.9%) had a left-sided and 806 (46.1%) a right-sided FNF. Implant failure occurred in 60 cases (3.4%), of which 31 were left-sided and 29 right-sided. No association between fracture side and implant failure was found [odds ratio (OR) for left vs. right 0.89, 95% confidence interval (CI) 0.52-1.52]. Female sex (OR 3.02, CI: 1.62-6.10), using a mobility aid (OR 2.02, CI 1.01-3.96) and a displaced fracture (OR 2.51, CI: 1.44-4.42), were associated with implant failure.. This study could not substantiate the hypothesis that the biomechanics of the clockwise screw rotation of the SHS contributes to an increased risk of implant failure in left-sided FNFs compared with right-sided fractures.. Therapeutic Level II.See Instructions for Authors for a complete description of levels of evidence.

Topics: Bone Screws; Female; Femoral Neck Fractures; Fracture Fixation, Internal; Hip Fractures; Humans; Torque

Reported rates of dislocation in hip hemiarthroplasty (HA) for the treatment of intra-capsular fractures of the hip, range between 1% and 10%. HA is frequently performed through a direct lateral surgical approach. The aim of this study is to determine the contribution of the anterior capsule to the stability of a cemented HA through a direct lateral approach. A total of five whole-body cadavers were thawed at room temperature, providing ten hip joints for investigation. A Thompson HA was cemented in place via a direct lateral approach. The cadavers were then positioned supine, both knee joints were disarticulated and a digital torque wrench was attached to the femur using a circular frame with three half pins. The wrench applied an external rotation force with the hip in extension to allow the hip to dislocate anteriorly. Each hip was dislocated twice; once with a capsular repair and once without repairing the capsule. Stratified sampling ensured the order in which this was performed was alternated for the paired hips on each cadaver. Comparing peak torque force in hips with the capsule repaired and peak torque force in hips without repair of the capsule, revealed a significant difference between the 'capsule repaired' (mean 22.96 Nm, standard deviation (sd) 4.61) and the 'capsule not repaired' group (mean 5.6 Nm, sd 2.81) (p < 0.001). Capsular repair may help reduce the risk of hip dislocation following HA.

Topics: Aged; Aged, 80 and over; Cadaver; Hemiarthroplasty; Hip Dislocation; Hip Fractures; Humans; Joint Capsule; Joint Instability; Sensitivity and Specificity; Torque

Fixation of periprosthetic hip fractures with intracortical anchorage might not be feasible in cases with bulky implants and/or poor bone stock.. Rotational stability of new plate inserts with extracortical anchorage for cerclage fixation was measured and compared to the stability found using a standard technique in a biomechanical setup using a torsion testing machine. In a synthetic PUR bone model, transverse fractures were fixed distally using screws and proximally by wire cerclages attached to the plates using "new" (extracortical anchorage) or "standard" (intracortical anchorage) plate inserts. Time to fracture consolidation and complications were assessed in a consecutive series of 18 patients (18 female; mean age 81 years, range 55-92) with periprosthetic hip fractures (ten type B1, eight type C-Vancouver) treated with the new device between July 2003 and July 2010.. The "new" device showed a higher rotational stability than the "standard" technique (p < 0.001). Fractures showed radiographic consolidation after 14 ± 5 weeks (mean ± SD) postoperatively in patients. Revision surgery was necessary in four patients, unrelated to the new technique.. In periprosthetic hip fractures in which fixation with intracortical anchorage using conventional means might be difficult due to bulky revision stems and/or poor bone stock, the new device may be an addition to the range of existing implants.

Topics: Age Factors; Aged; Aged, 80 and over; Arthroplasty, Replacement, Hip; Biomechanical Phenomena; Bone Plates; Bone Wires; Equipment Design; Female; Fracture Fixation, Internal; Hip Fractures; Hip Joint; Hip Prosthesis; Humans; Middle Aged; Periprosthetic Fractures; Radiography; Range of Motion, Articular; Retrospective Studies; Torque; Treatment Outcome

During insertion of a cancellous bone screw, the torque level reaches a plateau, at the engagement of all the screw threads prior to the screw head contact. This plateau torque (T(Plateau)) was found to be a good predictor of the insertion failure torque (stripping) and also exhibited strong positive correlations with areal bone mineral density (aBMD) in ovine bone. However, correlations between T(Plateau) and aBMD, as well as correlations between T(Plateau) and bone microarchitecture, have never been explored in human bone. The aim of this study was to determine whether T(Plateau), a predictor of insertion failure torque, depends on aBMD and/or bone microarchitecture in human femoral heads. Fifty-two excised human femoral heads were obtained. The aBMD and microarchitecture of each specimen were evaluated using dual X-ray Absorptiometry and micro-computed tomography. A cancellous screw was inserted into specimens using an automated micro-mechanical test device, and T(Plateau) was calculated from the insertion profile. T(Plateau) exhibited the strongest correlation with the structure model index (SMI, R=-0.82, p<0.001), followed by bone volume fraction (BV/TV, R=0.80, p<0.01) and aBMD (R=0.76, p<0.01). Stepwise forward regression analysis showed an increase for the prediction of T(Plateau) when aBMD was combined with microarchitectural parameters, i.e., aBMD combined with SMI (R(2) increased from 0.58 to 0.72) and aBMD combined with BV/TV and BS/TV (R(2) increased from 0.58 to 0.74). In conclusion, T(Plateau), a strong predictor for insertion failure torque, is significantly dependent on bone microarchitecture (particularly SMI and BV/TV) and aBMD.

Topics: Absorptiometry, Photon; Aged; Aged, 80 and over; Animals; Bone and Bones; Bone Density; Bone Screws; Female; Femur Head; Hip Fractures; Humans; Male; Regression Analysis; Sheep; Torque; X-Ray Microtomography

Fourth generation composite femurs (4GCFs, models #3406 and #3403) simulate femurs of males <80 years with good bone quality. Since most hip fractures occur in old women with fragile bones, concern is raised regarding the use of standard 4GCFs in biomechanical experiments. In this study the stability of hip fracture fixations in 4GCFs was compared to human cadaver femurs (HCFs) selected to represent patients with hip fractures. Ten 4GCFs (Sawbones, Pacific Research Laboratories, Inc., Vashon, WA, USA) were compared to 24 HCFs from seven females and five males >60 years. Proximal femur anthropometric measurements were noted. Strain gauge rosettes were attached and femurs were mounted in a hip simulator applying a combined subject-specific axial load and torque. Baseline measurements of resistance to deformation were recorded. Standardized femoral neck fractures were surgically stabilized before the constructs were subjected to 20,000 load-cycles. An optical motion tracking system measured relative movements. Median (95% CI) head fragment migration was 0.8mm (0.4 to 1.1) in the 4GCF group versus 2.2mm (1.5 to 4.6) in the cadaver group (p=0.001). This difference in fracture stability could not be explained by observed differences in femoral anthropometry or potential overloading of 4GCFs. 4GCFs failed with fracture-patterns different from those observed in cadavers. To conclude, standard 4GCFs provide unrealistically stable bone-implant constructs and fail with fractures not observed in cadavers. Until a validated osteopenic or osteoporotic composite femur model is provided, standard 4GCFs should only be used when representing the biomechanical properties of young healthy femurs.

Topics: Aged; Biomechanical Phenomena; Cadaver; Female; Femoral Neck Fractures; Femur; Fracture Fixation, Internal; Hip Fractures; Humans; Male; Materials Testing; Middle Aged; Models, Anatomic; Motion; Torque

The objective of this study was to evaluate the torsion stiffness of locked and unlocked distal fixation of long cephalomedullary nail constructs, in both a fresh fracture and healed, stable intertrochanteric fracture model. Samples were tested in both internal and external rotation (0±3 Nm) for a duration of 10 cycles. Each femur was tested without instrumentation (intact femur), with instrumentation and no fracture (healed intertrochanteric fracture), and with instrumentation with an osteotomy creating a stable intertrochanteric fracture (fresh fracture). All specimens were instrumented with a long cephalomedullary nail. A distal interlock was placed in the dynamic position in 1 femur, and the other femur of the matched pair was left unlocked. Mean external (ER) and internal (IR) rotation stiffness for intact femurs without instrumentation (ER, 2.1±0.5 Nm/degree; IR, 2.2±0.5 Nm/degree) was statistically stiffer (P<.05 for all) compared with fresh fractured locked (ER, 1.1±0.2 Nm/degree; IR, 1.1±0.3 Nm/degree) and fresh fractured unlocked (ER, 0.9±0.3 Nm/degree; IR, 1.0±0.2 Nm/degree) samples. Similarly, healed locked (ER, 2.5±0.2 Nm/degree; IR, 2.8±0.1 Nm/degree) and healed unlocked (ER, 2.5±0.5 Nm/degree; IR, 2.4±0.3 Nm/degree) samples had statistically higher stiffness compared with fresh fractured treatments. These results suggest that the unlocked distal constructs provide similar torsional strength compared with locked fixation in these models.

Topics: Aged, 80 and over; Bone Nails; Bone Screws; Cadaver; Elastic Modulus; Equipment Failure Analysis; Female; Fracture Fixation, Internal; Hip Fractures; Humans; Tensile Strength; Torque; Treatment Outcome

As one of the major functions of bone is to provide structural support for the musculoskeletal system, it is important to evaluate its mechanical strength. Bones may be subjected to multiaxial stresses due to bone pathologies, accidental loads which may lead to hip, wrist fracture, or to a prosthetic joint replacement. Twist loading may lead to fractures, especially involving long bones from lower limbs. The aim of this work was to study the effect of the strain rate on the shear properties of trabecular bone samples from women with hip fracture (from 65 to 100 years). Cylindrical samples were core drilled from human femoral heads along the primary trabecular direction. The cylinder's ends were polished and embedded in blocks of polymeric material which fit the grips of the testing device. Deformation rates of 0.005, 0.01, 0.015, and 0.05 s⁻¹ were applied. Twisting tests were conducted with or without an applied axial load of 500 N. From the torque-angular displacement curves, the shear stress-strain curves were obtained. The maximum shear strength and the shear modulus (i.e. the slope of the linear region) were determined. A large scatter of the results of the shear strength and the shear modulus was found, which is probably related to the heterogeneity of nonhealthy human bone samples. There is no significant effect of the strain rate on the maximum shear stress and the shear modulus, either in tests undertaken with or without the application of an axial load. The effect of strain rate on nonhealthy bone trabecular twisting properties did not follow the trend observed on the effect of strain rate in healthy bone, where an increase is detected.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Female; Femur; Hip Fractures; Humans; Shear Strength; Stress, Mechanical; Torque

The purpose of this study was to compare the biomechanical strength of the cephalomedullary nail InterTAN in cases of intertrochanteric fractures with the commonly used PFNA.. Sixteen fresh specimens of the proximal femur were used as intertrochanteric fracture models and were fixed using two fixation devices: the new proximal femoral nail (InterTAN) and proximal femoral nail antirotation (PFNA). An intertrochanteric fracture was created in composite bone models. Each specimen was loaded to simulate single leg stance while stiffness, migration (cut out), compressive force across the fracture site, and distal fragment rotation were monitored. The different internal fixation methods were tested by an experimental press analysis.. Results of tests for femoral strength, stiffness, stability, and bearing capacity demonstrated that the biomechanical function of InterTAN was better than that of PFNA (P < 0.05). Compared with the PFNA nail, InterTAN showed increased strength, stiffness, and resistance torque of 30%, 15%, and 27%, respectively.. Comparison of the treatment of intertrochanteric fractures with InterTAN and PFNA internal fixation showed that the InterTAN yielded improvement relative to the PFNA. InterTAN has a firmer and biomechanically superior performance and is therefore an ideal internal fixation method for treating intertrochanteric fractures. Additional research in osteopenic bone is necessary to comprehensively characterize the effects of the design enhancements of these two implants.

Topics: Aged; Biomechanical Phenomena; Bone Nails; Cadaver; Female; Femur Head; Fracture Fixation, Internal; Hip Fractures; Humans; Male; Middle Aged; Shear Strength; Torque; Treatment Outcome

The gamma nail has an option to statically lock its lag screw (static mode) or to allow its lag screw to move within the nail to compress the intertrochanteric fracture (dynamic mode). The purpose of this study was to compare the biomechanical stiffness of static and dynamic lag screw modes for a cephalomedullary nail used to fix an unstable peritrochanteric fracture.. Unstable four-part peritrochanteric fractures were created in 30 synthetic femurs and fixed with Long Gamma 3 Nails. Mechanical tests were conducted for axial, lateral, and torsional stiffness with intact femurs, femur-nail constructs with static lag screw mode,and femur-nail constructs with dynamic lag screw mode. A paired Student's t test was used for all statistical comparisons between test groups.. Axial and torsional stiffness of intact femurs was significantly greater than femur-nail constructs (p < 0.01 all comparisons),whereas lateral stiffness was significantly less (p < 0.01 all comparisons). Axial stiffness of the femur-nail construct was significantly greater (p < 0.01) in static mode (484.3 N/mm 80.2 N/mm) than in dynamic mode (424.1 N/mm 78.0 N/mm).Lateral stiffness was significantly greater (p < 0.01) in static mode (113.9 N/mm 8.4 N/mm) than in dynamic mode (109.5N/mm 8.8 N/mm). Torsional stiffness was significantly greater (p = 0.02) in dynamic mode (114.5 N/mm 28.2 N/mm) than in static mode (111.7 N/mm 27.0 N/mm).. There is a 60 N/mm (12.4%) reduction in axial stiffness when the lag screw is in dynamic mode. Given the statistically significant reduction in axial and lateral stiffness with use of the dynamic mode, static lag screw mode should be further explored clinically for treatment of unstable peritrochanteric fractures.

Topics: Biomechanical Phenomena; Bone Nails; Bone Screws; Fracture Fixation, Intramedullary; Hip Fractures; Humans; In Vitro Techniques; Stress, Mechanical; Torque

Since cut-out still remains one of the major clinical challenges in the field of osteoporotic proximal femur fractures, remarkable developments have been made in improving treatment concepts. However, the mechanics of these complications have not been fully understood.We hypothesize using the experimental data and a theoretical model that a previous rotation of the femoral head due to de-central implant positioning can initiate a cut-out.. In this investigation we analysed our experimental data using two common screws (DHS/Gamma 3) and helical blades (PFN A/TFN) for the fixation of femur fractures in a simple theoretical model applying typical gait pattern on de-central positioned implants. In previous tests during a forced implant rotation by a biomechanical testing machine in a human femoral head the two screws showed failure symptoms (2-6Nm) at the same magnitude as torques acting in the hip during daily activities with de-central implant positioning, while the helical blades showed a better stability (10-20Nm).To calculate the torque of the head around the implant only the force and the leverarm is needed (N [Nm] = F [N] * × [m]). The force F is a product of the mass M [kg] multiplied by the acceleration g [m/s2]. The leverarm is the distance between the center of the head of femur and the implant center on a horizontal line.. Using 50% of 75 kg body weight a torque of 0.37Nm for the 1 mm decentralized position and 1.1Nm for the 3 mm decentralized position of the implant was calculated. At 250% BW, appropriate to a normal step, torques of 1.8Nm (1 mm) and 5.5Nm (3 mm) have been calculated.Comparing of the experimental and theoretical results shows that both screws fail in the same magnitude as torques occur in a more than 3 mm de-central positioned implant.. We conclude the center-center position in the head of femur of any kind of lag screw or blade is to be achieved to minimize rotation of the femoral head and to prevent further mechanical complications.

Topics: Aged, 80 and over; Biomechanical Phenomena; Body Weight; Bone Screws; Cadaver; Equipment Failure Analysis; Femur Head; Fracture Fixation, Internal; Hip Fractures; Humans; Male; Materials Testing; Models, Theoretical; Prosthesis Design; Prosthesis Failure; Range of Motion, Articular; Rotation; Torque; Weight-Bearing

We developed a robot-assisted fracture reduction system (FRAC-Robo) to assist anatomical reduction and to maintain reduction during internal fixation while recording the procedure in a log. We conducted two experiments before using FRAC-Robo clinically. In the first experiment using the FRAC-Robo system, we measured the maximum force and torque required to pull and rotate the limbs of healthy conscious volunteers until they felt pain or abnormality. The average maximum traction force applied to the lower limb was 250.7 N, and the average maximum torque was 5.6 Nm in internal rotation and 7.6 Nm in external rotation for 30 degrees of abduction of hip. In the second experiment, we measured the traction force and rotation torque during the reduction of proximal femoral fractures. The average traction force and rotation torque needed for reduction were 215.9 N and 3.2 Nm, respectively. On the basis of these results, we consider that FRAC-Robo can generate sufficient force and torque to reduce femoral fractures safely.

Topics: Aged; Aged, 80 and over; Feasibility Studies; Female; Femoral Fractures; Femur; Hip Fractures; Humans; Male; Robotics; Surgery, Computer-Assisted; Torque; Traction

Topics: Bone Screws; Fracture Fixation, Internal; Hip Fractures; Humans; Postoperative Complications; Torque

Although the energy available during a fall from standing greatly exceeds that required to produce hip fracture, this occurs in only about 2% of falls in the elderly. This is thought to be due in part to one's ability to reduce the vertical impact velocity (nu(nu)) and kinetic energy (KE(nu)) of the body through energy absorption in the lower extremity muscles during descent. The present study tested the hypothesis that the magnitude and percent attenuation in nu(nu) and KE(nu) associate with the horizontal and vertical excursion of the body's center-of-gravity during descent. Measures were acquired of whole-body kinematics and lower extremity kinetics as young subjects underwent backward descents involving vertical drops of either thigh length (SIT) or lower extremity length (FALL), and horizontal pelvis excursions of either 33 or 66% of lower extremity length. In all trials, subjects attempted to "land as softly as possible." While attenuation in nu(nu) and KE(nu) (which averaged 62 and 92% respectively), did not associate with trial type, raw magnitudes of these parameters did, with nu(nu) averaging 2-fold greater, and KE(nu) averaging 6-fold greater, in 66% FALL than in 33% SIT or 66% SIT trials. This was due to a rapid increase in downward velocity accompanying the final stage of descent in 66% SIT and 66% FALL trials, which coincided with the knee moving posterior to the ankle. Accordingly, severe impacts likely accompany not only large fall heights, but also falls where the feet are thrown rapidly forward, as during a backward slip.

Topics: Accidental Falls; Adult; Biomechanical Phenomena; Biophysical Phenomena; Biophysics; Energy Transfer; Female; Hip Fractures; Humans; Male; Models, Biological; Movement; Postural Balance; Rotation; Torque

A study was performed to assess the effect of clockwise rotational torque onto the fracture configuration in unstable intertrochanteric fractures. The premise is that rotational torque in the sagittal plane imparted during screw insertion can lead to a potentially unstable construct in LEFT-sided DHS fixations when compared to the RIGHT-sided ones. This unstable fixation construct manifests as an anterior spike of the proximal fragment in left-sided fixations due to clockwise torque. Eleven out of 30 unstable left-sided fractures showed an anterior spike compared with none in 26 right-sided fractures (p<0.001). The study concludes that appropriate corrective measures of reducing the torque imparted is probably indicated in unstable left-sided fractures treated with a DHS.

Topics: Aged; Aged, 80 and over; Biomechanical Phenomena; Bone Screws; Chi-Square Distribution; Female; Fracture Fixation; Hip Fractures; Humans; Male; Middle Aged; Torque