Weight-bearing Capability Research Articles

Locomotor Adaptation to an Asymmetric Force on the Human Pelvis Directed Along the Right Leg.

In this work, we study locomotor adaptation in healthy adults when an asymmetric force vector is applied to the pelvis directed along the right leg. A cable-driven Active Tethered Pelvic Assist Device (A-TPAD) is used to apply an external force on the pelvis, specific to a subject's gait pattern. The force vector is intended to provide external weight bearing during walking and modify the durations of limb supports. The motivation is to use this paradigm to improve weight bearing and stance phase symmetry in individuals with hemiparesis. An experiment with nine healthy subjects was conducted. The results show significant changes in the gait kinematics and kinetics while the healthy subjects developed temporal and spatial asymmetry in gait pattern in response to the applied force vector. This was followed by aftereffects once the applied force vector was removed. The adaptation to the applied force resulted in asymmetry in stance phase timing and lower limb muscle activity. We believe this paradigm, when extended to individuals with hemiparesis, can show improvements in weight bearing capability with positive effects on gait symmetry and walking speed.

A vascularized elbow allotransplantation model in the rat

The aim of this research was to develop a rat model for vascularized composite allotransplantation (VCA) of the elbow. We developed an animal model for VCA of the elbow in rats. Microvascular VCA was performed in 9 rats across a major histocompatibility barrier. Three different immunosuppressive regimens were provided. Joint mobility and weight-bearing capability were assessed throughout 90 days of life. Pedicle patency, bone blood flow, and histologic analyses were performed. In the cyclosporine group, forelimb activity was recovered during the postoperative 90 days. The extremity that was operated on was used in daily activities. There was minimal motion or use of the limb in the cyclosporine taper and control groups. The vascular pedicles were patent at the time of death in the cyclosporine-treated group but not in the remaining groups. Micro-computed tomography scan performed 3 months after transplantation revealed union at the bone junctions, and the elbow joint appeared grossly normal on death in the cyclosporine treatment group only. Incomplete healing was observed in the other 2 groups, and the elbow joints were grossly destroyed. Histologic examination revealed normal cartilage and bone cells in the cyclosporine-treated group, whereas the nontreated groups demonstrated lymphocytic infiltration and loss of normal histologic features. Flow cytometry of blood samples obtained on days 14, 30, 60, and 90 showed no recipient cell chimerism in any of the groups. We developed an animal model for elbow VCA. Immunosuppressed animals regained nearly normal function of forelimbs and maintained grossly normal elbow cartilage. Without cyclosporine treatment, the elbow transplants were rejected.

The push-off test: Development of a simple, reliable test of upper extremity weight-bearing capability

Study designLongitudinal clinical measurement study. IntroductionThe push-off test (POT) is a novel and simple measure of upper extremity weight-bearing that can be measured with a grip dynamometer. There are no published studies on the validity and reliability of the POT. The relationship between upper extremity self-report activity/participation and impairment measures remain an unexplored realm. PurposeThe primary purpose of this study is to estimate the intra and inter-rater reliability and construct validity of the POT. The secondary purpose is to estimate the relationship between upper extremity self-report activity/participation questionnaires and impairment measures. MethodsA convenience sample of 22 patients with wrist or elbow injuries were tested for POT, wrist/elbow range of motion (ROM), isometric wrist extension strength (WES) and grip strength; and completed two self-report activity/participation questionnaires: Disability of the Arm, Shoulder and the Hand (DASH) and Work Limitations Questionnaire (WLQ-26). POT's inter and intra-rater reliability and construct validity was tested. Pearson's correlations were run between the impairment measures and self-report questionnaires to look into the relationship amongst them. ResultsThe POT demonstrated high inter-rater reliability (ICC affected = 0.97; 95% C.I. 0.93–0.99; ICC unaffected = 0.85; 95% C.I. 0.68–0.94) and intra-rater reliability (ICC affected = 0.96; 95% C.I. 0.92–0.97; ICC unaffected = 0.92; 95% C.I. 0.85–0.97). The POT was correlated moderately with the DASH (r = −0.47; p = 0.03). While examining the relationship between upper extremity self-reported activity/participation questionnaires and impairment measures the strongest correlation was between the DASH and the POT (r = −0.47; p = 0.03) and none of the correlations with the other physical impairment measures reached significance. At-work disability demonstrated insignificant correlations with physical impairments. ConclusionThe POT test provides a reliable and easily administered quantitative measure of ability to bear the load through an injured arm. Preliminary evidence supports a moderate relationship between loading bearing measured by the POT and upper extremity function measured by the DASH. Level of evidence1b

Psychometric Testing of a Clinical Test to Assess Upper Extremity Weight-Bearing Capability: The Push-Off Test

The primary purpose of this study is to analyze the inter-rater reliability, intra-rater reliability and construct validity of the push-off test (POT). The secondary purpose of this study was to examine the relationship amongst self-reported functional limitation, work limitation and physical impairment measures.

WE-G-217BCD-04: Diagnostic Image Quality Evaluation of a Dedicated Extremity Cone- Beam CT Scanner: Pre-Clinical Studies and First Clinical Results.

To assess the diagnostic performance of a prototype cone-beam CT (CBCT) scanner developed for musculoskeletal extremity imaging. Studies involved controlled observer studies conducted subsequent to rigorous technical assessment as well as patient images from the first clinical trial in imaging the hand and knee. Performance assessment included: 1.) rigorous technical assessment; 2.) controlled observer studies using CBCT images of cadaveric specimens; and 3.) first clinical images. Technical assessment included measurement of spatial resolution (MTF), constrast, and noise (SDNR) versus kVp and dose using standard CT phantoms. Diagnostic performance in comparison to multi- detector CT (MDCT) was assessed in controlled observer studies involving 12 cadaveric hands and knees scanned with and without abnormality (fracture). Observer studies involved five radiologists rating pertinent diagnostics tasks in 9-point preference and 10-point diagnostic satisfaction scales. Finally, the first clinical images from an ongoing pilot study were assessed in terms of diagnostic utility in disease assessment and overall workflow in patient setup. Quantitative assessment demonstrated sub-mm spatial resolution (MTF exceeding 10% out to 15-20 cm-1) and SDNR sufficient for relevant soft-tissue visualization tasks at dose <10 mGy. Observer studies confirmed optimal acquisition techniques and demonstrated superior utility of combined soft-tissue visualization and isotropic spatial resolution in diagnostic tasks. Images from the patient trial demonstrate exquisite contrast and detail and the ability to detect tissue impingement in weight-bearing exams. The prototype CBCT scanner provides isotropic spatial resolution superior to standard-protocol MDCT with soft-tissue visibility sufficient for a broad range of diagnostic tasks in musculoskeletal radiology. Dosimetry and workflow were advantageous in comparison to whole-body MDCT. Multi-mode and weight-bearing capabilities add valuable functionality. An ongoing clinical study further assesses diagnostic utility and defines the role of such technology in the diagnostic arsenal. - Research Grant, Carestream Health - Research Grant, National Institutes of Health 2R01-CA-112163.

Literature review of prosthetics for transtibial amputees

Approximately 82% of all amputations performed in the USA are transtibial amputations, in which the leg is removed below the knee. Because the knee joint is left intact the use of prosthetics is one of the most preferred methods for returning mobility to amputees. The improvement of prosthetics for transtibial amputees is currently an area of intense research. The purpose of this paper is to have a technical survey for transtibial prosthetic including four major components associated with standard transtibial prosthetic. The socket transfers the forces between the residual limb and the prosthetic. A suspension system ensures that solid contact is maintained between the leg and the artificial limb. The prosthetic foot is attached to the socket by a pylon, which also accounts for length of limb lost during amputation. Prosthetic feet come in many forms ranging from little more than wooden blocks to carbon fibre sprinting feet. Two recent advances in transtibial prosthetics include the procedures of direct skeletal attachment, and distaltibiofibular bone bridging which increases the weight bearing capability of the residual limb.

Abstract 5325: Localized tumor growth in bone: Quantification of tumor burden, bone destruction, and weight-bearing capability in MDA-MB-231 human mammary carcinoma xenograft-bearing immunodeficient rats

Abstract Metastatic bone disease is common in multiple myeloma, breast, prostate, and lung cancer patients and is a frequent cause of morbidity in advanced disease. Metastatic bone tumors destroy bone and cause severe bone remodeling which leads to structural weakening and bone fractures and often results in severe bone pain in a large percentage of patients. These studies examined tumor growth, bone erosion, and pain in a nude rat model. A surgical defect was created in the tibia, exposing the marrow cavity. Luciferase-expressing MDA-MB-231 mammary tumor cells were injected into the exposed bone cavity. Rats inoculated with tumor cells were treated with either doxorubicin (3 mg/kg/week, iv) or risedronate (80 ug/kg/day, ip). Animals were monitored weekly for tumor burden by optical imaging and for bone erosion by CT. In addition to clinical observations, weight bearing was measured using an incapacitance tester with separate force transducers for each hind paw. Compared to controls, rats treated with doxorubicin demonstrated a significant decease in luminescence, indicating tumor growth inhibition (bone protection). Decreased luminescence correlated with sparing of the bone as measured by CT. In contrast, the bisphosphonate, risedronate, had limited effect on tumor growth, but preserved bone integrity. In both treatments, protection of bone was associated with normalization of weight-bearing. This finding supports the premise that pain in metastatic bone cancer is attributable to bone loss (destruction) and remodeling. Weight-bearing data correlated directly with clinical observations This model, leveraging multiple imaging modalities, enables longitudinal and quantitative assessment of tumor growth; bone loss, remodeling and sparing, and weight-bearing in test animals that provides a sensitive and robust screening tool to evaluate compounds for anti-tumor, bone-sparing and pain amelioration effects. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5325. doi:10.1158/1538-7445.AM2011-5325

Tibial Plateau Fracture Repairs Augmented With Calcium Phosphate Cement Have Higher In Situ Fatigue Strength Than Those With Autograft

This study compared the biomechanical fatigue strength of calcium phosphate augmented repairs versus autogenous bone graft (ABG) repairs in lateral tibia plateau fractures. Eight matched pairs of tibias (six male, two female; age, 75 ± 14 years) were harvested from fresh-frozen cadavers. Reproducible split-depression fractures were simulated and repaired by an orthopaedic traumatologist using a lateral tibial plateau plate. One tibia from each donor was randomly assigned to either calcium phosphate (Callos; Acumed, Hillsboro, OR) or ABG as augmentation. The femoral component of a hemitotal knee arthroplasty was attached to the actuator of a servohydraulic press and centered above the repair site. Cyclic, physiological compression loads were applied at 4Hz starting with a maximum load of 15% body weight and increasing by 15% body weight every 70,000 cycles. Loading conditions were determined from calculations of weight distribution, joint contact area, and gait characterization from existing literature. Repair site depression and stiffness were measured at regular intervals. Specimens were then loaded to failure at 1 mm/min. Calcium phosphate augmented repairs subsided less and were more stiff during the fatigue loading than were ABG repairs at the 70,000, 140,000, and 210,000 cycle intervals (P < 0.03) All repairs survived to 210,000 cycles. The average ultimate load of the calcium phosphate repairs was 2241 ± 455 N (N = 6) and 1717 ± 508 N (N = 8) for ABG repairs (P = 0.02). Calcium phosphate repairs have significantly higher fatigue strength and ultimate load than ABG repairs and may increase the immediate weightbearing capabilities of the repaired knee.

Oral administration of a tri‐therapy for central pattern generator activation in paraplegic mice: Proof‐of‐concept of efficacy

Spinal cord injury (SCI) is a neurological condition, for which no cure exists, typically leading to an immediate and irreversible loss of sensory and voluntary motor functions accompanied by significant health problems. We conducted proof-of-concept experiments aimed at assessing efficacy upon oral administration of a novel combination therapy for central pattern generator (CPG) activation and corresponding locomotor movement generation in completely paraplegic animals. Co-administration orally (by gavage) of buspirone, levodopa and carbidopa was found to dose-dependently induce episodes of steady weight-bearing stepping in low-thoracic (Th9/10) spinal cord-transected (Tx) mice (with no other form of assistance or training). Robust hindlimb stepping with weight-bearing capabilities was induced with the tri-therapy but not with clinically relevant doses of these compounds administered separately. These results provide evidence suggesting that this drug combination may be ideally suited to constitute a first-in-class therapy (CPG activator) for locomotor activity induction in chronic SCI individuals, given that efficacy was shown using commercially available brain-permeable small molecules, already known as safe for the treatment of various neurological indications.

PLIF in thoracolumbar trauma: technique and radiological results

Patients with fractures from the 11th thoracic to the 5th lumbar vertebra had a reconstruction of the anterior column with monocortical iliac crest autograft by using a single dorsal approach. The loss of correction was observed using X-rays pre- and post-operatively, at 3 months and after implant removal (IR). Successful fusion was assessed using computed tomography after the implant removal. To assess the loss of correction and intervertebral fusion rate of this technique. There are still controversial discussions about the treatment modalities of spine lesions, especially in cases of burst fractures. Dorsal, combined and ventral procedures are reported with different assets and drawbacks. We want to present a method to restore the weight-bearing capability of the anterior column using a single dorsal approach. From 2001 to 2005, a total of 100 patients was treated with this technique at our department. Follow-up examination was possible in 82 patients. The X-rays and CT scans were proofed for loss of correction and fusion rate. The anterior column has been restored using a monocortical strut graft via a partial resection of the lamina and the apophyseal joint on one side to access the disc space. The dorsal reduction has been achieved using an angular stable pedicle screw system. The mean follow-up time was 15 months (range 8-39); 67 patients had a CT scan at follow-up and 83% showed a 360 degrees fusion. The average post-operative loss of correction was 3.3 degrees (range 0-21). The average duration of operation was 192 min (range 120-360) and the mean blood loss was 790 ml (range 300-3,400 ml). Regarding the complications we did not have any deep wound infections. We had two epidural haematomas postoperatively with a neurological deterioration that had to be revised. We were able to decompress the neurological structures and restore the weight-bearing capability of the anterior column in a one-stage procedure. So we think that this technique can be an alternative procedure to combined operations regarding the presented radiological results of successful fusion and loss of correction.

Transverse Loaded Pronosupination Test

A new test to evaluate the ability of the distal radioulnar joint to sustain transverse loads while the forearm rotates from pronation to supination is described. Both arms were tested in 100 normal volunteers. The average weight-bearing capability of the normal unsupported forearm was 5.07 kg, equating to a force of 49.8 N. The test may be useful in the assessment of pathological conditions involving weakness of the forearm rotator muscles, with or without joint incongruity, as well as being an indirect way to assess the load-bearing capacity of radioulnar implants.

Dynamic loading performance of fasciocutaneous flaps and implications for gait

Recent advancements in microsurgery allow the free tissue transfer for reconstruction of soft-tissue defects on the plantar surface of the foot. Fasciocutaneous flaps are one available option to the reconstructive surgeon. However, their functional weight-bearing capabilities have never been adequately evaluated. This study investigated the dynamic loading performance of selected fasciocutaneous flaps during walking using instrumented gait analysis. We investigated 6 feet with reconstructed heels along with their contralateral normal feet. A control group of normals was included also. Time-distance, ground reaction force parameters and plantar foot pressure distribution were evaluated. Data were normalized to account for anthropometric variations. A series of t-tests were used to investigate contrasts. Walking velocity of injured subjects was decreased (P<0.0001). Step length and single limb support were the shortest for the involved feet (P<0.04). Double limb support and swing were the longest (P<0.0002). The reconstructed heels sustained high pressures (P<0.05) and vertical loadings underlining their functional weight-bearing capabilities. However, the walking patterns implemented by the injured subjects resulted in reduced anterior-posterior shear forces that could help maintain the integrity of the shear plane at the graft-recipient bed interface. The dynamic loading capabilities of the fasciocutaneous flaps make it an effective means for restoring functional gait. Patients implement gait patterns that result in primarily decreasing shear forces. Consequently, the fasciocutaneous flaps should be included in the surgeons' armentarium as a plausible reconstructive means for soft-tissue defects on the plantar surface of the foot.

Weight Bearing Capability Of An Antibiotic Loaded Pre-Formed Articulated Knee Spacer: A Case Report

Weight Bearing Capability Of An Antibiotic Loaded Pre-Formed Articulated Knee Spacer: A Case Report

Effects of Swimming on Functional Recovery after Incomplete Spinal Cord Injury in Rats

One of the most promising rehabilitation strategies for spinal cord injury is weight-supported treadmill training. This strategy seeks to re-train the spinal cord below the level of injury to generate a meaningful pattern of movement. However, the number of step cycles that can be accomplished is limited by the poor weight-bearing capability of the neuromuscular system after injury. We have begun to study swimming as a rehabilitation strategy that allows for high numbers of steps and a high step-cycle frequency in a standard rat model of contusive spinal cord injury. The purpose of the present study was to evaluate the effect of swimming as a rehabilitation strategy in rats with contusion injuries at T9. We used a swimming strategy with or without cutaneous feedback based on original work in the chick by Muir and colleagues. Adult female rats (n=27) received moderately-severe contusion injuries at T9. Walking and swimming performance were evaluated using the Open-Field Locomotor Scale (BBB; Basso et al., 1995) and a novel swimming assessment, the Louisville Swimming Scale (LSS). Rats that underwent swim-training with or without cutaneous feedback showed a significant improvement in hindlimb function during swimming compared to untrained animals. Rats that underwent swim-training without cutaneous feedback showed less improvement than those trained with cutaneous feedback. Rats in the non-swimming group demonstrated little improvement over the course of the study. All three groups showed the expected improvement in over-ground walking and had similar terminal BBB scores. These findings suggest that animals re-acquire the ability to swim only if trained and that cutaneous feedback improves the re-training process. Further, these data suggest that the normal course of recovery of over-ground walking following moderately-severe contusion injuries at T9 is the result of a re-training process.

Functional Recovery Following Pertrochanteric Hip Fractures Fixated with the Dynamic Hip Screw vs. the Percutaneous Compression Plate

The Dynamic Hip Screw (DHS) is currently the most frequently used implant for the treatment of pertrochanteric hip fractures. The Percutaneous Compression Plate (PCCP) is a recently developed, alternative device that involves minimal invasive surgery. The objective of the present study was to compare functional recovery following these two surgical procedures. A total of 76 consecutive elderly subjects (mean age and standard deviation, 80.6 ± 5.5) following pertrochanteric hip fracture fixation were evaluated prospectively. Functional recovery was assessed 3 and 12 weeks and 2 years following surgery. Differences between groups 3 weeks postsurgery were found only in pain level during ambulation and in the weight-bearing capability of the operated extremity, which were both in favor of the PCCP. By 3 months, both groups had improved in all measures, but did not reach their preinjury level of independence. However, the PCCP group ambulated with fewer assistive devices and demonstrated better recovery of basic activities of daily living (BADL). While the majority of the subjects from both groups ambulated independently 2 years postsurgery, the PCCP group exhibited less pain during ambulation, was more independent in ADL, and required fewer assistive devices for ambulation. To summarize, the PCCP presents enhanced short- and long-term recovery of functional abilities in comparison to DHS. However, given the limited number of patients, further studies are necessary to substantiate these results.

Ilizarovʼs Technique in Correction of Ankle Malunion

A case is reported of ankle malunion corrected using Ilizarov's technique. The malunion, resulting in a varus ankle deformity (30 degrees), was a consequence of a posttraumatic epiphysiodesis of the distal growth plate of the tibia (McFarland's fracture). Ilizarov's procedure is described, and the radiological evolution of the regenerate is presented. Indications of corrective surgery in ankle malunion are discussed. The advantages of Ilizarov's technique (bloodless technique, cosmetic advantage, full weight-bearing capability, immediate talotibial joint rehabilitation) are illuminated.

The ICEROSS concept: a discussion of a philosophy.

Prefabricated ICEROSS (Icelandic Roll On Silicone Socket) sockets have been in use in Iceland since early 1986. Use of custom-made silicone sockets began several years earlier, and a paper devoted to the subject was presented at the 1984 AOPA Assembly by the author of this article. The ICEROSS system is primarily used for suspension. At the same time the author believes it considerably improves the weight-bearing capability of the prosthesis and the interface between prosthesis and user. After being turned inside out and rolled over the stump, the silicone sleeve forces skin in a distal direction, stabilising soft tissue and minimising pistoning. Both prosthetist and user may experience some problems initially, although most can be overcome by careful socket design and skin care.

Motion of the normal and anterior cruciate ligament deficient canine knee during the walk and trot

Motion of the normal and anterior cruciate ligament deficient canine knee during the walk and trot

Experimental osteoarthritis induced by selective myectomy and tendotomy.

A new model of osteoarthritis has been developed that utilizes an extraarticular surgical technique to alter gait and weight-bearing capabilities in the hind limbs of experimental animals. Guinea pigs, averaging 650 gm in weight, were subjected to unilateral resection of a segment of the gluteal muscles at the sacral origin, to section of the infrapatellar ligament, or to both procedures. Progressive changes consistent with osteoarthritis developed over 10-24 weeks as judged by gross, radiologic, and microscopic findings. In addition, an increase in mean cartilage water content and 35SO4(-2) incorporation into proteoglycans by 10 and 14 weeks, respectively, were consistent with the chemical changes observed in early osteoarthritis. Abnormalities developed not only in the operated hind limb, but in the contralateral, unoperated hind limb at a slightly later time. Thus, this animal model provided the opportunity to evaluate a mild gait abnormality and other biomechanical influences on the evolution of osteoarthritis which is uninfluenced by any intraarticular joint trauma.