A case of damage control after polytrauma and bilateral femur fracture.

Introduction: Multi-trauma patients require a multidisciplinary team, especially in the presence of various body systems injuries. The evaluation focuses on the decision regarding the DCO and ETC approaches. Case presentation: A 24-year-old male patient with Glasgow Coma Score 8, arrived at the emergency room, followed by ATLS protocol. Orthopedic trauma included D8 vertebra unstable burst fracture, right open femur shaft fracture, left closed midshaft femur fracture, and right tibial plateau fracture of the knee. Case summary: A hemodynamically stable patient with bilateral femur fractures is directed toward the DCO approach. Discussion: An initial treatment for an external fixator across the knee on the right leg and a spine fusion and decompression of D5-10 surgery was made on the day of admission. Definitive fixation and conversion to internal fixators were done on day 9 after the accident. Postoperative drop-foot injury was seen in the right leg. A Masquelet technique was applied for the right femur segmental fracture due to gaps. Conclusion: DCO may be employed to temporarily stabilize fractures, allowing the patient to recover from other life-threatening injuries before definitive fixation. Further secondary procedures, such as the Masquelet technique, should be considered to optimize the results. Long-term follow-up and rehabilitation are part of recovery, aiming to optimize functional recovery and improve the patient's quality of life.

Osteophytes' position in subjects with DISH and right-sided aorta: verification of the 'aortic pulsation protective effect' theory.

OBJECTIVES: To validate in a large cohort with right-sided aorta the theory that thoracic right-sided flowing osteophytes in DISH results from a 'protective' effect of the pulsating descending left-sided thoracic aorta. METHODS: Chest CTs of patients with DISH and right-sided aorta and controls with DISH and left-sided aorta were evaluated and compared on each intervertebral space (IS) for the location of the aorta (right, left, centre) and the location of the osteophyte relative to the aorta (contralateral, ipsilateral, bilateral). RESULTS: The study and control cohorts included 31 and 35 subjects, respectively (male 22/9 and female 27/8; median age 64.8/65.3 years; P = 0.86). Osteophytes contralateral to the aorta's location were recorded in the majority of ISs in both the study and control groups (47% and 60%, respectively; P > 0.05), while ipsilateral osteophytes were recorded in 6.9% and 7.7%, respectively (P = 0.002). Bilateral osteophytes located to the right and the left of the aorta were significantly more prevalent in the study group compared with the controls (17.2% and 5.4%, respectively; P = 0.04). CONCLUSIONS: Aortic pulsation plays an important role in inhibiting the development of osteophytes and results in the majority of contralateral osteophytes on both right-sided and left-sided aortas. However, since both ipsilateral and bilateral osteophytes were not at all rare in both groups, other parameters, which are yet to be established, probably contribute to the location of osteophytes.

[NOVEL CONCEPTS AND CHANGES IN TOTAL JOINT ARTHROPLASTY IN THE 21ST CENTURY].

INTRODUCTION: Total joint arthroplasty (TJA) is amongst the most common elective orthopedic surgeries. Since their introduction in 1951 there have been changes not only in prosthesis design and surgical approaches, but also in patient management, anesthesia, drug regimen and robotic arm assistance. These changes led to advancement in patient safety and shorter hospitalization. Today TJA is accessible for a wider age and function range of patients, which has led to an exponential growth in the number of procedures conducted.

Plantar pressure modifications in experienced runners following an exhaustive run.

Running-induced fatigue alters foot strike pattern. The purpose of this study was to assess plantar pressure and centre of pressure (CoP) trajectory alterations after a 30-minute run at sub-maximal speed in experienced long-distance runners. Plantar pressure data from 9 experienced heel-to-toe male runners was collected before and after a 30-minute run on a treadmill at a speed 5% above the respiratory compensation point (RCP) of each participant. Significant changes in the plantar-pressure map were found post-run, including increased impulses in the first metatarsal head (9.92%, p < 0.001) and hallux areas (16.19%, p < 0.001), and decreased impulses in the fourth and fifth metatarsal heads (4.95%, p < 0.05). The CoP curve showed a medial shift (p < 0.01). The plantar-pressure map and CoP trajectory were altered following a 30-minute exhausting run. These changes may indicate an increase in stress on joints and tissues when individuals are fatigued and may promote overload injuries.

The impact of bariatric surgery on nonalcoholic fatty liver disease as measured using non-invasive tests.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is common in bariatric surgery candidates. We evaluated the effect of sleeve gastrectomy (SG) on NAFLD using validated non-invasive measures. METHODS: Patients with morbid obesity and NAFLD, planned for SG, were evaluated before and after surgery. Data collected included anthropometrics, biochemistry, adiponectin, SteatoTest™, NashTest™, FibroTest™, OWLiver® test and real-time ShearWave™ elastography (SWE). RESULTS: Twenty-six subjects were included in the study, mean age 44.1 ± 4.8 years, 69.2% males. One year following SG, body mass index decreased significantly from 41.7 ± 4.8 kg/m2 to 29.6 ± 4.5 kg/m2. Concomitantly, significant improvements in triglycerides, ALT, diabetes markers and adiponectin were observed. Mean steatosis, as measured by SteatoTest™, was significantly improved. Steatohepatitis score measured by NashTest™ and OWLiver® significantly decreased. Mean fibrosis, as measured by SWE liver stiffness and FibroTest™, did not change over time. CONCLUSION: Steatosis and steatohepatitis are significantly improved by SG as measured by non-invasive measures.

Keeping the Finger on the Pulse: Cardiac Arrhythmias in Hand Surgery Using Local Anesthesia with Adrenaline.

BACKGROUND: The wide-awake local anesthesia no tourniquet (WALANT) technique in hand surgery is gaining popularity. The authors aimed to prospectively analyze the frequency and type of arrhythmias in patients undergoing hand surgery under local anesthesia and to examine whether the addition of adrenaline affects their incidence. METHODS: Adult patients undergoing hand surgery under local anesthesia were randomized into two groups: group 1, local anesthesia with lidocaine and tourniquet; and group 2, local anesthesia with lidocaine and adrenaline (WALANT). Patients with a history of arrhythmias were excluded. Patients were connected to Holter electrocardiographic monitoring before surgery and up until discharge. The records were blindly compared between the groups regarding types of arrhythmias, and frequency and timing relative to injection and tourniquet inflation. RESULTS: One hundred two patients were included between August of 2018 and August of 2019 (age, 59.7 ± 13.6 years; 71 percent women; 51 in each group). No major arrhythmia (ventricular tachycardia, ventricular fibrillation, atrial fibrillation) or arrhythmia-related symptoms were recorded for either group. Minor arrhythmias (including atrial premature beats, ventricular premature beats, and atrial tachycardia) were recorded in 68 patients (66.6 percent), with no statistical difference between the groups. There were three patients with minor arrhythmias during inflation of the tourniquet. Patients in the adrenaline group had 2 percent sinus tachycardia during injection and 4 percent asymptomatic bradyarrhythmias. These findings do not require any further treatment. CONCLUSIONS: The authors' results show that hand operations using WALANT technique in patients with no history of arrhythmia are safe and are not arrhythmogenic; therefore, there is no need for routine perioperative continuous electrocardiographic monitoring. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Use of Intraoperative Tranexamic Acid and Wound Complications in Spine Surgery: A Retrospective Cohort Study.

STUDY DESIGN: A retrospective cohort study. PURPOSE: This study aims to examine the effect of tranexamic acid (TXA) on postoperative wound healing in spine surgery. OVERVIEW OF LITERATURE: TXA (Cyklokapron, Hexakapron) is a widely used anti-fibrinolytic drug that is shown to be effective in mitigating hemorrhage during and after surgery by competitively blocking plasminogen in fibrinolytic cascade. Plasminogen also plays a role in inflammatory and infectious diseases. The modulation of this role by TXA may influence the development of postoperative infectious complications. METHODS: We collected and reviewed the charts of 110 patients who underwent spine surgery at our academic center. We used multivariate regression analysis to assess the factors affecting surgical site infection (SSI). RESULTS: Of the 110 patients included in this study, 21 patients (19%) were categorized as having postoperative wound complications, 16 patients (14%) had deep or superficial wound infection, and five patients (4%) had wound dehiscence. Patients with a higher surgical invasiveness index score, longer surgeries, and older patients were found to be at risk for wound complications. TXA was determined not to be a direct risk factor for wound healing complications and SSIs. CONCLUSIONS: We found no risk of wound healing complications and SSI directly attributable to preoperative and intraoperative treatment with TXA in spine surgeries.

Multivariate analysis of risk factors for re-dislocation after revision for dislocation after total hip arthroplasty.

BACKGROUND: The treatment for recurrent dislocation of a total hip arthroplasty is surgical using varied techniques and technologies to reduce the chances of re-dislocation and re-revision. The goal of this study is to compare operative techniques to reduce re-dislocation and re-revision in revision hip arthroplasty due to recurrent dislocations. METHODS: A retrospective study of revision hip arthroplasties done due to recurrent dislocation prior to 01 January 2014. Electronic physician and provincial health records were used to collect patients' initial and follow-up data. Treatment failure was defined as either aseptic re-revision or re-dislocation without revision. Time to event was considered as the re-revision date or the date of second dislocation when the latter endpoint was used. RESULTS: Of 379 operations, 88 (23.2%) had aseptic repeat revision or recurrent dislocation. Of these: 66 (75.0%) due to dislocation with re-revision; 10 (11.4%) due to dislocation with no re-revision surgery; 5 (5.7%) due to aseptic loosening of components; 3 (3.4%) due to osteolysis; 3 (3.4%) due to pseudotumour; and 1 (1.1%) due to periprosthetic fracture. The following factors increase risk of failure: the use of augmented-liners (lipped, oblique and high-offset liners; HR = 1.68, 95% CI, 1.05-2.69), periprosthetic femur fracture (HR = 2.80, 95% CI, 1.39-8.21) and pelvic discontinuity (HR = 3.69, 95% CI, 1.66-8.21). Femur head sizes 36-40 mm are protective (HR = 0.54, 95% CI, 0.31-0.86). In abductor dysfunction the use of focal constrained liners decreases the risk of failure (HR = 0.13, 95% CI, 0.018-0.973). CONCLUSIONS: Larger head sizes and focal constrained liners (abductors dysfunction) should be used and fully constrained liners and augmented-liners should be avoided in a revision hip arthroplasty due to recurrent dislocations.

Checkpoint Genes at the Cancer Side of the Immunological Synapse in Bladder Cancer.

Immune checkpoint inhibitors have revolutionized cancer therapy, but not all cancers respond to the currently available drugs, and even within cancers considered responsive to such modality, response rates range between 15 and 40%, depending on the cancer type, the line of treatment, and yet unknown clinical/molecular factors. Coordinated expression of checkpoint proteins was shown to occur on T cells, probably allowing fine-tuning of the signal transmitted to the cell. We performed a bioinformatic analysis of the expression of putative checkpoint mRNAs at the cancer side of the immunological synapse from the bladder cancer tumorgenome atlas (TCGA) database. Fifteen mRNAs, corresponding to both coinhibitory and costimulatory checkpoints, were shown to be expressed above a designated threshold. Of these, seven mRNAs were found to be coexpressed: CD277, PD-1L, CD48, CD86, galectin-9, TNFRSF14 (HVEM), and CD40. The expression of 2 of these mRNAs-BTN3A1 (CD277) and TNFRSF14 (HVEM)-was positively correlated with overall survival in the TCGA database. All these seven mRNA share putative binding sites of a few transcription factors (TFs). Of these, the expression of the TF BACH-2 was positively correlated with the expression of checkpoint mRNAs from the network. This suggests a joint transcriptional regulation on the expression of checkpoint mRNAs at the bladder tumor side of the immunological synapse.

Enthesopathy of the anterior chest wall joints in patients with diffuse idiopathic skeletal hyperostosis (DISH): a retrospective analysis of computed tomography scans.

PURPOSE: To evaluate and characterize anterior chest wall (ACW) joint's enthesopathy on CT scans in patients with DISH compared with age- and gender-matched control group. MATERIAL AND METHODS: Retrospective evaluation for enthesopathy features of ACW joints-sterno-clavicular (SCJ), manubrio-sternal (MSJ), costo-sternal 1-7 (CSJ)-on chest CT scans of subjects with DISH (Resnick criteria) and of age- and gender-matched control subjects was performed. 183 subjects (DISH: 92, control: 91); male:female: 126:57, average age: 71.7 years (range 50-94) were evaluated. Total enthesopathy scores per subjects and per each joint were compared. RESULTS: Total enthesopathy score of ACW joints was significantly higher among DISH compared to controls (64.03 ± 15.1, 50.47 ± 12.4, p < 0.001). At joint level, SCJ and CSJ enthesopathy, but not MSJ was significantly more prevalent in DISH compared to controls. CONCLUSION: ACW joints' enthesopathy as seen on CT scans, an entity not included in the Resnick classification criteria, is common among DISH subjects. The difference between SCJ and CSJ prevalence compared to MSJ may result from different joint type. ACW joints' enthesopathy may be considered to be included in future modified radiographic criteria for DISH.

The impact of upright radiographs of midshaft clavicle fractures on treatment recommendations.

Clavicle fractures' treatment recommendations are based on displacement. The goal of this paper is to determine upright clavicle radiographs at initial presentation changes timing and method of treatment. Retrospective study in a level 1 trauma center. 356 patients with clavicle fractures were reviewed. Patients with only supine radiographs (Group 1, 285 patients) were compared to patients with supine and upright radiographs (Group 2, 71 patients). Higher proportion of fractures in the upright vs supine radiographs were displaced 100% or more of the clavicle width, (52.1% vs. 33.5%, p =0.004). Treatment assignment changed from nonoperative to operative treatment more commonly in the Group 2 compared to Group 1 (43.7% vs 21.9%, p =0.019). The most common reason for surgery in Group 1 was presence of continued pain or failure to develop radiographic evidence of callus on serial radiographs (17, 53.1%) as compared to Group 2 (2, 14.2%, p =0.014). In Group 2 the most common cause for treatment change was displacement (12, 85.7%) as compared to Group 1 (15, 46.9%, p =0.014). Patients with upright x-rays are more likely to have a change in treatment because of displacement while patients that had supine x-rays have more delayed/nonunion.

Pseudotumors and High-Grade Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesions Around Total Knee Replacements Identified at Aseptic Revision Surgery: Findings of a Large-Scale Histologic Review.

BACKGROUND: Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) development (including pseudotumors) secondary to metal debris generation around total hip arthroplasties is a well-recognized histopathologic phenomenon. Emerging data have highlighted a similar potential concern around TKAs although the body-of-knowledge has largely been limited to individual case reports or small retrospective case series. This study sought to establish the prevalence of pseudotumors or high-grade ALVALs seen at the revision of primary TKAs and to establish the correlation between histologic ALVAL grade and patient-reported functional outcome measures. METHODS: The findings of 321 non-infective (aseptic) patients undergoing unilateral revision knee surgery, at a high-volume tertiary referral center, were reviewed. Each case was independently histologically classified. Complete patient-reported functional outcome measures were available for 134 patients (42%) allowing correlation between functional performance and histopathology results. RESULTS: Five distinct pseudotumors and a further 18 high-grade ALVALs were histologically identified representing 1.6% and 5.6% of the cohort, respectively. When compared by histologic grade, Oxford Knee Score and Western Ontario and McMaster University's Osteoarthritis Index suggested a high correlation between ALVAL grade and functional knee scores. CONCLUSION: These findings suggest a prevalence of pseudotumors or high-grade ALVALs at revision TKA surgery of >7%. This unexpectedly high result may contribute insight into the previously under-appreciated significance of metal debris-related local tissue reactions around TKAs. The findings also demonstrate a strong near-linear inverse relationship between patient-reported clinical knee performance and the underlying histologic grade of local tissue reaction. These results have potential management implications for patients with underperforming TKAs and should prompt consideration of an ALVAL secondary to metallosis in the differential diagnosis. LEVEL OF EVIDENCE: This is a retrospective cohort study with Level III evidence.

Return to sports after chronic anterior exertional compartment syndrome of the leg: Conservative treatment versus surgery.

AIM: To evaluate whether surgical treatment for anterior chronic exertional compartment syndrome (CECS) of the lower leg will lead to full athletic activity recovery compared to conservative treatment. METHODS: Patients diagnosed with anterior CECS of the leg were offered surgical treatment, as surgery considered today to be the mainstay of treatment. Patients unwilling to be treated surgically were treated conservatively. They were followed up, assessing both groups for pain, functional status, and the Tegner sports activity score with comparisons at diagnosis and following treatment. RESULTS: Forty-three patients were treated for CECS (31; 72.1% with surgery and 12; 27.9% conservatively) with a mean follow-up of 28.15 (4.16-54.09) months. Reported pain improved at follow-up by 1.59 (0-6) points and by 4.27 ± (0-10) points in the conservatively and the surgically treated patient groups, respectively ( p = 0.014) with a mean change in the Tegner score of 0.09 (-5 to 5) and 3.22 (-4 to 7), respectively ( p = 0.009). Three patients in the conservatively treated group (25% of 12) and 24 patients in the operated group (77.4% of 31) reported full resumption of their pre-diagnosis activity level ( p = 0.001). CONCLUSION: This study supports surgery as the treatment of choice for anterior CECS of the leg with differential benefit for fasciotomy in terms of pain and return to pre-diagnosis athletic activity.

Trunk kinematic, kinetic, and neuro-muscular response to foot center of pressure translation along the medio-lateral foot axis during gait.

Footwear devices that shift foot center of pressure (COP), thereby impacting lower-limb biomechanics to produce clinical benefit, have been studied regarding degenerative diseases of knee and hip joints, exhibiting evidence of clinical success. Ability to purposefully affect trunk biomechanics has not been investigated for this type of footwear. Fifteen healthy young male subjects underwent gait and electromyography analysis using a biomechanical device that shifts COP via moveable convex elements attached to the shoe sole. Analyses were performed in three COP configurations for pairwise comparison: (1) neutral (control) (2) laterally deviated, and (3) medially deviated. Sagittal and frontal-plane pelvis and spine kinematics, external oblique activity, and frontal and transverse-plane lumbar moments were affected by medio-lateral COP shift. Transverse-plane trunk kinematics, activity of the lumbar longissimus, latissimus dorsi, rectus abdominus, and quadratus lumborum, and sagittal-plane lumbar moment, were not significantly impacted. Two linear mixed effects models assessed predictive impact of (I) COP location, and (II) trunk kinematics and neuromuscular activity, on the significant lumbar moment parameters. The COP was a significant predictor of all modeled frontal and transverse-plane lumbar moment parameters, while pelvic and spine rotation, and lumbar longissimus activity were significant predictors of one frontal-plane lumbar moment parameter. Model results suggest that, although trunk biomechanics and muscle activity were altered by COP shift, COP offset influences lumbar kinetics directly, or via lower-limb changes not assessed in this study, but not by means of alteration of trunk kinematics or muscle activity. Further study may reveal implications in treatment of low back pain.

Classic Markers for Infection Perform Poorly in Predicting Residual Infection Prior to Reimplantation.

Two-stage exchange arthroplasty remains the treatment of choice for chronic periprosthetic joint infections. This retrospective study conducted between 2009 and 2015 examined the diagnostic value of biomarkers for residual infection between stages. The biomarkers evaluated included C-reactive protein prior to reimplantation, preimplantation synovial fluid white blood cell count and percent neutrophils, and the intraoperative histologic synovial white blood cell count per high-power field (×400) on permanent sections. Residual infection was defined as either positive cultures (more than 1) at second stage, any further surgery (eg, amputation, arthrodesis, or another 2-stage revision), or the need for infection suppression with antibiotics. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios were calculated accordingly. A total of 182 two-stage exchange operations that included 109 (59.9%) prosthetic hips and 73 (40.1%) prosthetic knees met the inclusion criteria. Residual infection was present in 38 (20.9%) of the procedures. The area under the curve-receiver operating characteristic values were 0.677 for C-reactive protein (P=.002), 0.506 for aspiration white blood cell count (P=.944), 0.623 for aspiration percent neutrophils (P=.200), and 0.524 for white blood cell count per high-power field (P=.801). Positive and negative predictive values were poor and ranged between 26% and 57% and 78% and 85%, respectively. Analyses using specific combinations of biomarkers did not significantly improve predictive values. This study showed that classic markers perform poorly in identifying residual infection prior to second-stage revision. Further research is necessary to evaluate the diagnostic utility of other, more recently introduced biomarkers to determine whether infection has been eradicated between stages. [Orthopedics. 2019; 42(1):34-40.].

Closed Wound Subfascial Suction Drainage in Posterior Fusion Surgery for Adolescent Idiopathic Scoliosis: A Prospective Randomized Control Study.

STUDY DESIGN: A prospective randomized control study. OBJECTIVE: The aim of this study was to compare the complication rate in adolescent idiopathic scoliosis (AIS) posterior spinal fusion (PSF) surgery with and without drainage. SUMMARY OF BACKGROUND DATA: PSF is the mainstay of surgical treatment for AIS. Drains are commonly used despite contradictory findings in the literature for their having any clear advantage. METHODS: A total of 100 AIS patients undergoing instrumented PSF were blindly randomized into two groups of either a deep drain or no drain. The collected data included wound follow-up findings, hemoglobin, hematocrit, vital signs and fever levels, and mean 20 months follow-up. RESULTS: Fifty-two patients were randomly allocated to the "no drain" group and 48 to the "drain" group. There were no differences in patient characteristics, surgical data, and hemoglobin and hematocrit levels between the two groups. Only 4 units of packed cells were given in total. Fever during the first postoperative 1 to 3 days was equal, but increased in the no drain group on day 6 (P = 0.017). Length of hospitalization was equal (6 days) for all the patients. The mean follow-up period was 20 months [8.5-30.7 (SD 6.4)]. Complications included one case (1.9%) of pneumonia in the "no-drain" group, wound dehiscence in two cases (3.8%) in the "no-drain" group and in one case (2.1%) in the "drain" group, and two cases (3.8%) of superficial wound infection in the "no-drain" group. There was no case of deep infection in either group. CONCLUSION: The current results indicate that there is no advantage to deep drainage in AIS patients undergoing PSF. The number of wound healing complications was low and identical for both the drain and no-drain groups. LEVEL OF EVIDENCE: 2.

A Biomechanical Foot-Worn Device Improves Total Knee Arthroplasty Outcomes.

BACKGROUND: Biomechanics after total knee arthroplasty (TKA) often remain abnormal and may lead to prolonged postoperative recovery. The purpose of this study is to assess a biomechanical therapy after TKA. METHODS: This is a randomized controlled trial of 50 patients after unilateral TKA. One group underwent a biomechanical therapy in which participants followed a walking protocol while wearing a foot-worn biomechanical device that modifies knee biomechanics and the control group followed a similar walking protocol while wearing a foot-worn sham device. All patients had standard physical therapy postoperatively as well. Patients were evaluated throughout the first postoperative year with clinical measures and gait analysis. RESULTS: Improved outcomes were seen in the biomechanical therapy group compared to the control group in pain scores (88% vs 38%, P = .011), function (86% vs 21%, P = .001), knee scores (83% vs 38%, P = .001), and walking distance (109% vs 47%, P = .001) at 1 year. The therapy group showed healthier biomechanical gait patterns in both the sagittal and coronal planes at 1 year. CONCLUSION: A postoperative biomechanical therapy improves outcomes following TKA and should be considered as an additional therapy postoperatively.

Mechanism of reducing knee adduction moment by shortening of the knee lever arm via medio-lateral manipulation of foot center of pressure: A pilot study.

Prominent conservative treatment options for medial-compartment knee osteoarthritis include footwear that reduces knee adduction moment (KAM) correlated with detrimental loads in the medial compartment of the knee, thus providing clinical benefit. The proposed mechanism by which they reduce KAM is a lateral shift in foot center of pressure (COP) and a consequent shortening of the knee lever arm (KLA), thereby reducing KAM, which can be simply calculated as KLA multiplied by the frontal plane ground reaction force (FP-GRF). The present study investigated this mechanism for a unique biomechanical device capable of shifting COP by means of moveable convex elements attached to the shoe. Fourteen healthy young male subjects underwent gait analysis in two COP configurations of the device for comparison: (1) laterally and (2) medially deviated. Average midstance KLA and KAM were decreased by 8.2% and 8.7%, respectively, in the lateral COP compared to medial. Ground reaction force parameters, frontal plane knee angle (FP-KA), and spine lateral flexion angle (SLF) did not differ between COP configurations. No study parameters differed for terminal stance. Linear mixed effects models showed that COP and FP-GRF components, but not FP-KA and SLF, were significant predictors of KLA. In addition, KLA and FP-GRF were significant predictors of KAM; although, FP-GRF did not change significantly with medio-lateral COP shift, while KLA did. This suggests that the mechanism by which the study device reduces KAM is primarily through shortening of KLA brought on by a lateral shift in COP.

The effect of center of pressure alteration on the ground reaction force during gait: A statistical model.

BACKGROUND: Foot problems and lower-limb diseases (e.g., foot ulcers, osteoarthritis, etc.), are presented with a ground reaction force (GRF) that may deviate substantially from the normal. Thus, GRF manipulation is a key parameter when treating symptoms of these diseases. In the current study, we examined the impact of footwear-generated center of pressure (COP) manipulations on the GRF components, and the ability to predict this impact using statistical models. METHODS: A foot-worn biomechanical device which allows manual manipulation of the COP location was utilized. Twelve healthy young men underwent gait analysis with the device set to convey seven COP conditions: (1) a neutral condition, (2) lateral and (3) medial offset along the medio-lateral foot axis, (4) anterior and (5) posterior offset along the antero-posterior foot axis, and (6) a dorsi-flexion and (7) plantar-flexion condition. Changes in the magnitude and the early stance-phase impulse of the GRF components across COP conditions were observed. Linear models were used to describe relationships between COP conditions and GRF magnitude and impulse. RESULTS: With respect to ANOVA, the vertical and antero-posterior components of the GRF were significantly influenced by the COP configuration throughout the different stages of the stance-phase, whereas the medio-lateral components were not. The models of vertical, antero-posterior and medio-lateral GRF components were statistically significant. SIGNIFICANCE: The study results are valuable for the development of a method and means for efficient treatment of foot and lower-limb pathologies. The ability to predict and control the GRF components along three orthogonal axes, for a given COP location, provides a strong tool for efficient treatment of foot and lower-limb diseases and may also have relevant implications in sports shoe design. This study is a preliminary investigation for our ultimate goal to develop an effective treatment method by developing an autonomous GRF manipulations device based on closed-loop feedback.