Occupational Lower Extremity Risk Assessment Modeling

Introduction: Lower extremity (LE) work-related musculoskeletal disorders (WMSDs) are known to occur with cumulative exposure to occupational and personal risks. The objective of this dissertation study was to find if creating a quantifiable risk detection model for the LE was feasible. The primary product of the literature review conducted for this study resulted in focusing the attention of the model development process onto creating the initial model of the LE for assessing knee disorder risk factors. Literature Review: LE occupational disorders affect numerous industries and thousands of people each year by affecting any one of the musculoskeletal systems deemed susceptible by the occupational and personal risk factors involved. Industries known to be affected tend to have labor intensive job descriptions. Some of the numerous industry examples include mining, manufacturing, firefighting, and carpet laying. Types of WMSDs noticed by the literature include bursitis, osteoarthritis, stress fractures, tissue inflammation, and nerve entrapment. In addition to the occupationally related disorders that may develop, occupationally related discomforts were also taken into consideration by this study. Generally, both the disorders and the discomforts can be traced to either a personal or occupational risk factor or both. Personal risk factors noted by the literature include a person\u27s physical fitness and health history (such as past injuries). Meanwhile, occupational risks can be generalized to physical postures, activities, and even joint angles. Prevalence data over a three year interval (2003-2005) has found that LE WMSDs make up on average approximately 7.5% of all the WMSD cases reported to the US Occupational Safety and Health Administration (OSHA). When the literature is refined to the information pertaining to occupational knee disorders, the mean prevalence percentage of the same three year range is about 5%. Mean cost for knee injuries were found to be $18,495 (for the year between 2003 and 2004). Methodology: Developing a risk model for the knee meant using groups of subject matter experts for model development and task hazard analysis. Sample occupational risk data also needed to be gathered for each of a series of tasks so that the model could be validated. These sample data were collected from a sample aircraft assembly plant of a US aerospace manufacturer. Results: Based on the disorder and risk data found in the literature, a knee risk assessment model was developed to utilize observational, questionnaire, and direct measure data collection methods. The final version of this study\u27s knee model has an inventory of 11 risk factors (8 occupational and 3 personal) each with varying degrees of risk exposure thresholds (e.g., high risk, moderate risk, or minimal risk). For the occupational risk assessment portion of the model, the results of task evaluations include both an occupational risk resultant score (risk score) and a task risk level (safe or hazardous). This set of results is also available for a cumulative (whole day) assessment. The personal risk assessment portion only produces a risk resultant score. Validation of the knee risk model reveals statistically (t (34) = 1.512, p = 0.156), that it is functioning as it should and can decide between hazardous and safe tasks. Additionally, the model is also capable of analyzing tasks as a series of cumulative daily events and providing an occupational and personal risk overview for individuals. Conclusion: While the model proved to be functional to the given sample site and hypothetical situations, further studies are needed outside of the aerospace manufacturing environment to continue testing both the model\u27s validity and applicability to other industrial environments. The iterative adjustments generated for the occupational risk portion of the model (to reduce false positives and negatives) will need additional studies that will further evaluate professional human judgment of knee risk against this model\u27s results. Future investigations must also make subject matter experts aware of the minimal risk levels of this knee risk assessment model so that task observational results are equally comparable. Additional studies are moreover needed to assess the intimate nature between variable interactions; especially multiple model defined minimal risks within a single task

The effect of unsupportive and supportive footwear on children’s multi-segment foot dynamics during gait

Footwear is necessary for children’s foot comfort and protection. Despite the popularity of flip-flop (thongs) footwear among children, strong clinical opinion endures of the potential deleterious effect this footwear may have on developing feet. On the contrary, thongs may be beneficial for children’s developing feet due to the footwear’s flexible and unrestrictive nature, as children who mature within habitually barefoot communities are observed to develop stronger and healthier feet. This thesis considers the developing nature of human ambulation and the physiological basis for children’s foot maturation. It then explores the effect of thong footwear on childrens barefoot dynamics with comparisons to traditionally advocated supportive footwear. Foot compensations were observed when thongs were worn while walking and to a lesser extent while jogging. Greater ankle dorsiflexion and reduced hallux dorsiflexion suggests a mechanism to retain the thong. Greater midfoot plantarflexion indicates a gripping action to sustain the thong. Barefoot motions were unaffected by thongs during the sidestep. The midfoot splinting effect of supportive shoes was reinforced while walking, jogging and sidestepping. Thongs had a minimal effect on barefoot dynamics, while supportive shoes limited midfoot power generation with a corresponding increase in ankle power generation. Overall findings suggest that foot motion when wearing thongs may be more replicable of barefoot motion than originally believed. In terms of foot arch development, thongs may be more beneficial than supportive shoes, due to the minimal alterations to barefoot motions when they are worn. The reported midfoot plantarflexion required to grip the thong may be beneficial to children’s foot arch strengthening and overall foot development. While supportive shoes have the necessary protective features, they have been shown to inhibit midfoot and hallux motions with a compensatory increase in ankle motions

Plantar Pressure, Cutaneous Sensation and Stochastic Resonance: An Examination of Factors Influencing the Control and Perception of Posture

The goal of this dissertation was to understand how people control posture in the context of sensory loss. To do so we explored three potential influences on the detection of external information and how they relate to the control of posture and perception of body orientation: 1) does changing posture alter the forces under the foot, and do these changes impact the ability to detect external vibrations? 2) Does decreasing the temperature of the foot influence the ability to detect external vibrations, the perception of body orientation, and the control of posture? And 3) does stochastic resonance (SR) improve the perception of body orientation and the control of posture when the sensory thresholds are elevated to clinical levels through cooling of the feet? The results of the experiments indicate that: 1) increasing the pressure under the feet, elicited by changes in posture, elevates the cutaneous sensory threshold, and that the forefoot appears to be more sensitive than the rearfoot to changes in weighting; 2) decreasing the temperature of the skin elevates cutaneous sensory thresholds, and impacts postural control by constraining the fluctuations of the medial-lateral center of pressure; and 3) applying SR to the soles of the feet improves the ability to perceive body position, with greater amounts of skin cooling resulting in greater improvements in postural performance due to SR. This dissertation demonstrates that decreasing plantar loading lowers cutaneous sensory thresholds, indicating that the changes in postural fluctuations frequently observed among those with clinical sensory loss may serve as a mechanism that allows for improved access to external information if they prove to reduce the pressure under sensory impaired portions of the feet. Additionally, we add to the growing body of literature identifying SR as a means to improve postural performance when cutaneous sensory function is impaired. From a clinical perspective, the results presented here indicate that aids designed to apply SR to the soles of the feet, as a means to improve posture and gait, should modulate their signal such that they apply a signal amplitude appropriate to the amount of loading the foot experiences

Centre of pressure characteristics in normal, planus and cavus feet

Background The aim of this study was to compare centre of pressure (COP) characteristics between healthy adults with normal, planus or cavus feet who were allocated to groups based on reliable foot posture measurement techniques. Methods Ninety-two healthy adult participants (aged 18 to 45) were recruited and classified as either normal (n = 35), pes planus (n = 31) or pes cavus (n = 26) based on Foot Posture Index, Arch Index and normalised navicular height truncated measurements. Barefoot walking trials were conducted using an emed®-x 400 plantar pressure system (Novel GmbH, Munich, Germany). Average, maximum, minimum and range (difference between maximum and minimum) values were calculated for COP velocity and lateral-medial force index during loading response, midstance, terminal stance and pre-swing phases of stance. The COP excursion index was also calculated. One-way analyses of variance were used to compare the three foot posture groups. Results The cavus foot exhibited the slowest average and minimum COP velocity during terminal stance, but this pattern was reversed during pre-swing, when the cavus foot exhibited the fastest maximum COP velocity. The planus foot exhibited the smallest lateral medial force index range during terminal stance. There were no differences between the groups for COP excursion index. Conclusion These findings indicate that there are differences in COP characteristics between foot postures, which may represent different mechanisms for generating force to facilitate forward progression of the body during the propulsive phases of gait

THE EFFECT OF FOOTWEAR TO THE POSTURE

The aim of this study is to assess the effect of footwear on postural status of a group of volunteers representing the general population of female students. Based on the assumption that the elegant shoe with tapered toe and high heel does not provide adequate foot support, the study was designed to assess its direct link and impact to body segment alignment and resulting negative effect on posture. Repetition of this misalignment ensures the individual circumstances of posture. Due to the heel elevation, the weight is transferred to the distal part, resulting in a postural response of the entire musculoskeletal system to maintain balance. The group consisted of 30 women of the age 18–28 years with an average age of 22.7 years, height 167±0.3 cm and weight 57±0.9 kg. Anamnesis and aspection were performed to assess of the occurrence of shortened and weakened muscles and subsequently the patient's standing was examined. Two static methods were chosen for evaluation of the posture. The first one was the Silhouette Posture Analysis and the evaluation method by Jaros and Lomnicka. The result was the identification of typical muscle imbalance as the most common presumption of faulty posture, and it was confirmed that footwear affects a person's natural posture. Differences in the sensitivity of the two methods were also identified and studies are not only appropriate that but also evaluate differences in impact among subjects

Investigation of the differences in foot and ankle characteristics of patients with lower limb osteoarthritis : implications for clinical practice

To date, the foot posture of patients with lower limb osteoarthritis (OA) has not been explored from an orthopaedic perspective. In other medical fields such as neurology and sports medicine, a relationship between foot posture, gait and pathology has been acknowledged. In view of the current high incidence of lower limb OA, investigation of any differences in foot posture in patients with lower limb OA that may lead to improved assessment and conservative management is worthy of consideration. The first component of the thesis investigated a clinically observed difference in the foot posture of 60 patients with hip OA, 60 patients with medial compartment osteoarthritis of the knee (MCOA) and 60 healthy volunteers using an observational study. A significant difference in foot characteristics was demonstrated. Patients with hip OA demonstrated a lack of dorsiflexion and a greater degree of calcaneal inversion, presenting with a supinated foot. Patients with MCOA demonstrated ample dorsiflexion and a greater degree of calcaneal eversion, presenting with a pronated foot. In general, the healthy volunteers demonstrated average dorsiflexion and average calcaneal eversion and this gave the appearance of a normal foot. This did not, however, provide evidence of any causal relationship. A pre and post operative observational study of 55 patients with MCOA who underwent the Oxford unicompartmental knee arthroplasty was then undertaken. As a result of this surgery there is a major correction of varus to valgus knee orientation which is significant clinically and statistically. Although there is a major change in knee orientation, this study showed that the foot posture was not altered. This study also does not provide evidence that foot posture is causal in the development of MCOA. It does, however, give an indication of the robustness of the foot postures of these patients. The second component of the thesis was concerned with clinical outcome measures for the assessment of foot posture in patients with lower limb OA. Currently there is no standard practice for physiotherapists. Routine examination of the foot is rare. Two systems of measurement: (a) The Foot Posture Index and (b) the F-Scan in-shoe pressure measurement system were examined in detail with a cohort of patients with lower limb osteoarthritis. The two measurement systems were found to be useful in a clinical setting and sensitive enough to support the findings in Component 1 of the thesis. In addition, the use of the Foot Posture Index score allowed investigation of the relationship between foot posture and talocrural dorsiflexion. A high degree of talocrural dorsiflexion corresponds with a positive FPI score indicating a pronated foot. A low degree of dorsiflexion corresponds with a negative FPI score indicating a supinated foot. This is the first time that talocrural dorsiflexion has been shown to be associated with foot posture, although previously it has been accepted anecdotally in clinical podiatry. The third component was a systematic review which explored the current clinical practice of using lateral wedges in the conservative management of MCOA by orthopaedic surgeons. This contrasts with the use of medial wedges in the world of sports medicine, physiotherapy and podiatry to correct over-pronation problems. As the foot posture of patients with MCOA had been shown to be pronated, it was felt necessary to examine the evidence for the use of lateral wedges. The systematic review found no strong evidence to support the use of lateral wedges in the conservative management of MCOA. Finally, the main findings of the thesis are discussed, the findings summarised and suggestions made for clinical practice and further research