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By J. D. Davis

Coke Since the beginning of manufacturing of metallurgical coke in the United States, which dates from about 1859, Pennsylvania has main tamed supremacy in coke production Available statistics for the year 1880 show an output of 3,338,300 short tons, which was neatly trebled by the end of the succeeding 10 years. From this time on the increase was steady, though not rapid, and in 1922 the total production was 13,991,892 tons, which is approximately 37 per cent of the total coke production of the United States. The main reason for the rapid development of the coke industry in Pennsylvania lies in the abundance of coals particularly adapted to beehive coking, for which purpose the Pittsburgh bed in the Connellsville district has long been looked upon as standard At first practically all metallurgical coke was made in beehive ovens, the only exception being the short lived and wasteful method of coking in piles, byproduct owns did not make then appearance until after 1893 The suitability of a beehive coking coal cannot be accurately predicted from its chemical analysis, but it can be said, perhaps, that the volatile matter should be about 32 per cent, and that the oxygen content should not be mole than 10 pet cent or less than 4 per cent The sulphur and phosphorus content should be small-not over 1 25 per cent sulphur and under 0 02 pen cent phosphorus-and the ash content should not be over 7 per cent The Pittsburgh bed at Connellsvnlle fills these requirements well, as may be seen from the following representative analysis. Analysts of coal from Pittsburgh bed Moisture 1 70 Volatile matter 31 10 Fixed carbon 59 80 Ash 7 40 Sulphur 0 85 B t u 13,990

Jan 1, 1928

By R. J. Matetic

The National Institute for Occupational Safety and Health (NIOSH) has recognized that Noise-Induced Hearing Loss (NIHL) is the most common occupational illness in the United States. The use of heavy equipment, the drilling of rock, and the confined work environment are some of the factors that contribute to high levels of noise exposure to workers in the mining industry. Every day 80% of the nation’s miners go to work in an environment where the time weighted average (TWA) exceeds 85 dBA. Moreover, 25% of the miners are exposed to a TWA noise level that exceeds 90 dBA, the Permissible Exposure Limit (PEL). Furthermore, a NIOSH analysis of a large sample of audiograms showed that at age 50 approximately 90% of coal miners and 49% of metal/non-metal miners have a hearing impairment. By contrast, only 10% of the non-occupational-noise exposed population has a hearing impairment at age 50 (Franks, 1997) (Stephenson, 1998). Simply stated, the majority of miners have a hearing loss by the time they retire. While NIHL is the most common occupational disease in this country, this problem is especially acute among workers in the mining industry. There are several barriers to reducing NIHL in the mining industry. These include: gaps in knowledge of noise dose/source relationships, the unavailability of effective noise controls, and needs for worker education and worker empowerment. A related issue is the difficulty of communication in noisy workplaces by both hearing impaired and normal hearing workers. The Pittsburgh Research Laboratory (PRL) at NIOSH has strategically developed a hearing loss prevention program for overcoming these respective barriers in an attempt to reduce NIHL in the mining industry. This paper provides an overview of the research program being conducted at the PRL.

By L. C. IlsLey

The Bureau of Mines has collected field data and made laboratory investigations of trailing- cable performance in the hope of developing a better and safer cable for use with permissible mining machines . Because of their better insulation and performance , only rubber- sheathed cables were finally considered . The cables tested represented the product of six manufacturers . : After consideration of the results of the preliminary investigations , the conditions under which cables are used in mines , and the better performance of the later types of cables that were submitted as the investigation progressed , the bureau formulated a performance - test requirement and notified the cable manufacturers as follows : The hazards of the trailing cable are such that the bureau has been unable to extend beyond the machine its formal approval to cover the cable as at present developed . However , in the attempt to reduce the hazard as much as possible , cables passing certain tests will be recommended for this service and it is hoped that several cables will be developed to meet this requirement .

Sep 1, 1930

By David M. Hyman

Outbursts are sudden and violent releases of gas and coal that result from a complex function of geology, stress regime, and gas pressure and content. The Bureau of Mines has reviewed methods for prediction and mitigation of such outbursts in use worldwide, as an aid in selecting the proper techniques for use in specific mine environments. Outburst-prone coal may be distinguished from normal coal by its sorption-desorption velocity. Three types of methods used to characterize the kinetics of sorption-desorption are described; all are based on the ability of outburst-prone coal to release, through desorption, methane or carbon dioxide much more rapidly than normal coals. Other prediction methods, based on borehole samples, are also described. Various mitigation methods described and evaluated include (1) working the least stressed, less disturbed, lowest gas content seam in multiple-seam areas; (2) mine opening geometry; (3) inducer shot firing; (4) water infusion; (5) localized stress relief, using boreholes or by cutting a reliever slot in the longwall face; and (6) other gas drainage methods.

Jan 1, 1987

By VAN. H. MANNING

During the nine years that have elapsed since the Bureau of Mines was established in 1910, the work of the bureau has included many investigations that have proved of high value to the Nation. Eleven mining experiment stations established by act of Congress have greatly increased the bureau's usefulness; being situated in the mining fields, these stations are closely in touch with industrial needs, and the results of their research and educational work are more directly available to those engaged in the mining, metallurgical, and mineral industries. In the United States mining is second in importance to agriculture only. The Federal Government annually appropriates large sums in the interest of agriculture, whereas the appropriations for mining are relatively small. But the nation-wide popularity of Government assistance to agriculture should not overshadow the need of Federal assistance to the mineral industry. With scientific management farms can be made to produce indefinitely without any depletion of the potential resources of the soil, but the mineral wealth of a country is a fixed quantity, and every year's production brings nearer its ulti- mate exhaustion. As the deposits of the richer or more readily available ores, espe- cially those in the West, have been depleted, development of methods for mining and treating the leaner or more inaccessible ores has lagged, so that meeting the increasing demands for certain metals is becoming more and more difficult. In some branches of mining the small inde- pendent operator is greatly handicapped. He has to rely on custom mills and smelters for the profit or loss of his product, and because of relatively inefficient methods of milling or smelting he may receive no return for much of the ore he mines. Even though the small operator thinks he knows of improved methods of obtaining the metals from the ores, he can not afford to install the necessary machinery or to carry on experiments that may or may not prove successful. In view of the increasing need of metals and the impossibility of renewing the ore supplies, efforts should be directed toward developing the most economical and efficient methods in mining and metal- lurgy. The great mining companies carry on independent research work, some of them on a large scale; but as such work is usually undertaken for gainful purposes, these companies do not feel under any obligation to give the results of their investigations to the world. Clearly the solution of the difficulty is to place in the mining districts trained mining and metallurgical engineers who will investigate and solve the problems for the benefit of the whole industry. It is with this purpose in view that experiment stations of the Bureau of Mines have been established to investigate economy, efficiency, and safety in mining, and to make public the results of the investigations. The Federal Government can be of most help in developing the mineral resources of the country when its forces are brought in direct contact with these resources. Mining is as old as civilization, but only within a generation has this country busied itself with any other problem of mining than the amount of mineral products that could be put upon the market. Little concern was felt if much of the metal in an ore was wasted, if the miner lived in unsanitary surround- ings and died of preventable disease, or if accidents occurred fre- quently and from causes that could easily be controlled. Now we realize that the waste of any resource is inexcusable. The mineral wealth of the country can be mined but once. The task before the Nation is to recover as much metal as possible from the ore in the ground, and to do this in the most economical way without waste of human life. This task is of such magnitude as to warrant aid from the Government through experiment stations. In its efforts to make the work of these stations of most benefit to the mineral industry the Bureau of Mines seeks the cooperation of State authorities, of mine operators, of miners' organizations, and of every person interested. These experiment stations also serve an educational purpose. Gen- erally speaking, mining is not a preferred occupation. The miner should have reason to take greater interest in his work; he should feel that the experiments the Government is making affect him vitally by enabling him to increase his production and by making his work safer. The mine operator should realize that the Government stands ready to aid him, and he should know that he can bring his own problems to a Government organization that is trained and equipped to solve them. The surest method of accomplishing these results is to carry the work of the Bureau of Mines into the mining regions through the establishment of experiment stations easily accessible both to the mine operator and to the miner. Many miners in this country do not read English, but they can understand motion pictures of mining methods; they can learn how lives can be saved in case of accident; and they can appreciate the larger results gained by modern methods and equipment. In every

Jan 1, 1919

By F. B. Tough

An inusual job in controlling a gas well was executed on No. 1 well, Inland Oil and Refining Co., situated on the Alkali Butte structure, Freemont County, Wyoming. The work was done by the company in cooperation with the . S. Bureau of Minos, and resulted in a fuel saving of $5,000 in one season and of a repair job estimated at $15,000, or a total of $21,000. The woll had an open flow of 6,000,000 cubic feet of gas per day with a rock pressure of 560 pounds per square inch. A string of 6-1/4 inch casing with a toothed shoe was set on the cap rock above the gas sand at 2181 feet. Then the well was shut in, the gas worked out around both the 6-1/4 inch and 6-1/4 inch strings, breaking through the ground surface at several points under the derrick. Casing troubles encountered while drilling made it unsafe to attempt Coving the 6-1/4 inch string. Moreover, it was important from the standpoint of good management to make the gas from this well immediately available for fuel in other operations and, in addition, to save the gas from wasting. An ordinary mudding and cementing job would have necessitated sitting down this well for probably two months out of a very short operating season. For these rousons it was determined to mud the well, if possible, between the 6 and 8 inch strings by pumping mud fluid through the connection from the gas clamps. The gas clamps used wore of ordinary construction with a side outlet, making them equivalent to a Braden-hoad. When the mud fluid was pumped through the gas clamp into the space between the two strings, it began to appear inside the 6-1/4 inch string. It apparently entered the well either around the toothed shoe or through a "line sawed" leak in the string and was blown out of the well as fast as it was pumped in. In order to stop the leaks, about a half a gunny sack of finely chopped bull ropa was fed with the mud between the casings as before. The hemp gathered around the valves of the mud pump to some extent, and it also stuck in the casing-head fittings a few times. An obstruction in the casing- head would be removed by permitting the woll to "blow back" for a few seconds, and one in the pump valves, by removing the valves when necessary. In two days' time sufficient hemp and mud had been pumped into these strings to kill external and internal pressure. The wall was shut in and allowed to stand over night. The next day, by opening and closing the master gate at intervals,

Mar 1, 1921

By C. A. Herbert

"The Workman's Compensation Law of Indiana, enacted in 1915, amended in 1917, 1919, 1923, and 1927, and in 1929 named the Indiana Workmen's Compensation Act of 1929, provides for a weekly compensation for disability due to accidents of 55 per cent of the average weekly wage of the employee, to start on the eighth day of disability. Compensation is computed from a maximum and minimum weekly wage of $30 and $16, respectively. Thus, the maximum weekly compensation is $16.50 and the minimum $8.80; the total compensation paid is not to exceed $5,000.In addition to the compensation the employer is required to pay all medical, surgical, hospital, and nurse fees for a period of 30 days and may be required to pay such fees for an additional 30 days at the direction of the Industrial Board of Indiana. In the case of fatalities the employer must contribute $100 toward funeral expenses.The law also stipulates that ""the employer shall keep a record of all injuries, fatal or otherwise, received by his employees in the course of their employment,"" also that the employer shall report within one week of their occurrence all accidents that cause either the death of the employee or the loss of more than one day's work. However, no standard form is furnished or required by the industrial board on which the employer shall keep a record of accidents, neither is he required to report the time of return to work of the injured employee unless the period of disability exceeds seven days and the accident thus becomes compensable. Hence, no record is kept of noncompensable accidents other than the first report sent to the industrial board by the employer.If the employer were required to keep a complete and concise record of all accidents, in duplicate, on a special form either furnished or required by the board, giving all of the essential data in regard to the accidents, and if he were required to submit a copy of this record to the board at the end of the fiscal year, the data thus assembled would not only be of material assistance to the board, particularly in making up its annual report, but would also furnish information of much value in the study of accident causes and what may be done to remove them.Those industries that have made marked progress in reducing accidents keep such records, as it is only through a full knowledge of how accidents occur that intelligent steps can be taken to prevent their recurrence. Unfortunately, the mining industry as a whole in Indiana has not kept pace with many other industries in reducing accidents, and it is urged as an aid to improvement that a thorough and complete record of mining accidents be kept."

Dec 1, 1932

By Joseph V. Mather, E. H. McCleary

"INTRODUCTION Workmen are transported in shafts in various types of cages or skips, most of which were designed primarily for hoisting cars and materials. Therefore, in general the cages or skips are not completely enclosed, adequate and gates are not always provided, and at many mines signaling devices and telephones are re¬stricted to those at the various landings in the shafts.Shaft accidents are usually severe - frequently fatal - and as a rule such an accident is caused by failure to comply with company rules or by ignoring them.Sixty men were killed and 555 men were injured in shafts of the anthracite and bituminous coal mines of the United States during the 5-year period 1938-42. 4/ Many of these accidents could have been prevented by having properly enclosed cages and adequate locking devices on doors to prevent workmen from falling into the shafts.The officials of the Heidelberg Coal Co. contemplated utilizing an old coal-hoisting shaft as a man-hoisting shaft; however, it was their desire to avoid the use of the conventional cage and to try to provide a safer means of transporting men in the shaft. Investigations and studies made by the officials revealed that an elevator similar to those used in large buildings would be more economical in first cost, maintenance, and operating costs would be less, and it would be safer and more convenient for the workmen. Effective safety devices for such elevators have been developed to such a high degree that those properly installed seldom fail. The elevator or man cage finally chosen cannot be pulled above the top landing through mechanical or man failure; it stops automatically at each landing and cannot be moved while a door is open; when the cage leaves the landing the doors opening to the shaft are automatically locked by mechanical and electrically operated locks; electric lights, telephone communication, and push-bottom controls are available on the cage, and adequate safety switches and overspeed controls are provided."

Jun 1, 1947

By Robert F. Chaken

The National Institute of Occupational Safety and Health (NIOSH) is dedicated to achieving "safety and health at work for all people -- through research and prevention." An important procedure in pursuing this goal is the NIOSH surveillance studies where the number of injuries are monitored according to demographic, employment, and injury characteristics. These numeric data are then used to identify injury risk factors, develop safety programs, and monitor implemented remediation methods. In essence, ongoing surveillance data form the bases for directing the resources of NIOSH in setting of research and prevention priorities, and in evaluating safety procedures. This surveillance techmque, which is based on the Public Health Service approach to identification and control of disease (1, 2, has been used quite successfully in dealing with relatively high number injuries such as hearing loss, musculoskeletal disorder, respiratory disorder, falls, etc. (2). However a problem arises when extending this paradigm to lower frequency traumatic events; particularly those often referred to as disasters (i.e., high impact events like mine explosions, airplane crashes, etc.). One can ask the question - there hasn't been a coal mine fire fatality in the U.S. for over ten years, to what extent should we be concerned with mine fire safety (resource-wise)? - The National Traumatic Occupational Fatalities (NTOF) system (4J which NIOSH uses to survey occupational fatalities annually, would suggest that underground mine fires would not be a high priority item in occupational safety. Yet, miners' (i.e., the exposed workers) do consider mine fires and explosions to be major safety concerns. I believe that we need to rethink our evaluation of work place disasters, what is worker exposure, and what are the underlying assumptions (both explicit and implicit) as to the impact that economic, societal and degree of hazard factors make on risk evaluation. The answers to all these problems, will require much broader considerations than those in current surveillance safety and health models. This paper discusses some facets of those considerations.

By C. P. Bowie

During the period of 10 years from January 1, 1908, to January 1, 1918, approximately 12,850,000 barrels of oil and 5,024,506,000 cubic feet of gas were destroyed by fire in the United States, entailing a total estimated property loss of $25,254,200. During this period 503 fires were reported. As is shown in Plates I and II, 310 of these fires were caused by lightning and 193 by all other causes. The losses from the fires caused by lightning were estimated to be $11, 148,000, and from those due to all other causes $14,106,200. Directly and indirectly, the fires resulted in the deaths of nearly 150 persons and were responsible for almost as many more being permanently disabled. For the past three years the Bureau of Mines has been conducting investigations to determine the nature and the specific causes of these fires, with a view to suggesting means whereby they may be suc- cessfully combatted and, in some places, perhaps eliminated entirely. As the subject of oil and gas fires is necessarily broad, no attempt is made in this bulletin to treat it exhaustively; rather the bulletin aims to point out what has been done by operators in the past, and to describe various fire-prevention methods and fire-fighting appa- ratus which are being used or adopted by many of the larger oil companies. These methods and apparatus, it is believed, if uni- versally employed by operators, will largely decrease the present enormous annual losses. In the discussion of oil-well fires, the methods used in extinguishing several of the larger and more perplexing ones are described. As the right procedure for extinguishing any oil-well fire must be de- termined largely by local conditions, it is not probable that all of the methods used at some one fire, as described, will be applicable to a future fire. However, the operator, from these descriptions, may at least gain suggestions that will greatly assist him in fighting similar fires.

Jan 1, 1919

By Lynn L. Rethi, Barbara Fotta

Recent employment figures (taken from the Mine Safety and Health Administration's database) indicate that the number of independent contractor' employees working in the coal mining industry has doubled over the past ten years. As their numbers increase, they become a more visible segment of the industry. [ ] Increased exposure to mining hazards has also brought an increase in the number of fatalities involving independent contractor workers. One gauge that is traditionally used to evaluate the overall safety of an entity is the "number of fatalities." Over the five-year period from 1985-89, 27 independent contractor employees were fatally injured while working on coal mine property. This number increased to 45 fatalities during the subsequent five-year period from 1990-94. Nearly half of these fatalities (47%) were due to accidents involving powered haulage (See Table); 13% were electrical accidents; and 9% were machinery accidents. Combined, these three accident classifications accounted for 69% of all coal nine independent contractor fatalities. Information taken from fatality data is an important piece of the safety puzzle; however, other variables need to he examined in order to better define contributing factors associated with accidents. More specifically, information on trends in fatal and nonfatal accident and injury data is necessary before deciding what approach should be used to improve safety. In order to implement appropriate safety strategies, it is important for safety practitioners to examine all available lost time accident and injury information. The following coal industry data sites specific and present trends of independent contractor employees working in underground locations at coal mines, surface areas of underground coal mines, surface coal mines, and preparation plants. The data compares employment and accidents for time periods at the beginning and the end of a ten-year span from 1985 to 1994. Because the number of incidents involving independent contractors in certain accident categories during any one year may be small, three-year totals are used; the first three years (1985-87) of the ten-year period are compared with the last three years (1992-94). [ ]

By H. S. Caldwell

This report describes work by the Bureau of Mines on the vacuum distilla¬tion of some of the more volatile metals such as cadmium, zinc, and magnesium from lead and tin. Evacuation within a distillation apparatus allows rapid diffusion of vapor away from the evaporation surface and prevents reaction of the vapor with residual gases. A reduction of pressure to several tenths of a millimeter makes possible practicable distillation rates, at temperatures for which the partial pressure of the metal vapor exceeds 10-3 atmosphere. The rate and selectivity of distillation depend primarily on the volatility and molal ratios of the alloy metals, and their chemical activity to each other. For very rapid evaporation or low concentration of the more volatile constituent, the rate is determined by the rate of diffusion of the evaporating metal, to the surface of the melt. Cadmium, zinc, magnesium, and tellurium were found to volatilize readily from both lead and tin. Tellurium appears to volatilize as an intermetallic compound rather than the pure metal. Antimony could not be removed from lead at 1,000° C.; the condensate was nearly all lead. Antimony, bismuth, and lead were removed from tin.

Jan 1, 1960

By Ron Merkel, A. Mayton

Operators of underground mobile equipment, particularly shuttle cars, are often exposed to significant levels of whole-body vibration (WBV) and shock. The human factors group at the NIOSH-Pittsburg Research Center has investigated the use of viscoelastic foam to reduce shock for the equipment operator and improve seats on mine shuttle cars.

By T. M. Barton

This paper presents several case studies in which a mechanics-based boundary-element program is used to back-calculate the surface subsidence associated with various panels at several northern Appalachian coal mines. The program used in this case study is called LAMODEL, which incorporates a frictionless, laminated overburden into a general-purpose displacement-discontinuity code primarily designed for calculating the stresses and displacements in coal mines or other thin-seam or vein-type deposits. In this paper, the program is used to calculate both the underground convergence and the resulting surface subsidence at five longwall panels and a room-and-pillar section. The fitted subsidence from the model is compared with the field measurements and analyzed. The results from this work show that the LAMODEL program is not as accurate as available empirical subsidence-predictive methods: the expected correlation between the geology and the optimum input parameters is not evident. However, for a mechanics-based program, LAMODEL does provide moderately accurate subsidence calculations, and it is one of a few programs that can even attempt to practically calculate both underground stress and convergence and the resulting surface subsidence.

By Launa Mallett

This training material focuses on the content of emergency warning messages. Research has shown that when an emergency occurs, people often do not get the information they need for the purpose of taking appropriate action. This safety talk presents a procedure, using mental cues that can be used by senders and receivers of emergency warnings.

Jan 1, 1999

By Launa Mallett, PhD, Charles Vaught, PhD

This training material focuses on the content of emergency warning messages. Research has shown that when an emergency occurs, people often do not get the information they need for the purpose of taking appropriate action. This safety talk presents a procedure, using mental cues that can be used by senders and receivers of emergency warnings.

By Wilbert J. Huff

For the past 8 years the technical studies conducted by. the Explo- sives Division of this Bureau have been summarized in a series of annual reports.3 This report deals with activities from July 1, 1942, to June 30; 1943. Specific problems have been in immediate charge of section or unit leaders, to whom credit is given.

Feb 1, 1944

By C. M. Mason

A series of gelatinous permissible explosives was prepared with increasing sodium nitrate content and subjected to an improved technique for evaluating incendivity in coal dust-air and coal dust-gas-air mixtures. Those explosives containing an appreciable amount of sodium nitrate were found to be very hazardous in coal dust-air and coal dust-gas-air mixtures.

Jan 1, 1969

By E. J. Gleim

"Information gathered during recent months by field men of the U. S. Bureau of Mines shows that in one State alone there have been 71 fatalities from electrical causes during the last 51/2 years, of which 55 were from contact with mine trolley wires operated at 250 volts or less, direct current. The 1928 law relating to the guarding of trolley wires in the-mines of this particular State reads: ""All trolley wires carrying a voltage of class 2 must be properly shielded except where the same are at least 61/2 feet above top of rail."" Class 2 voltage is defined as being ""between 300 volts and 600 volts direct current, or 240 volts and 480 volts alternating current."" From this it may be inferred that no guards are required, for 250-volt trolley wires, and the natural conclusion to be drawn is that the lack of guards or shields must be held responsible for these fatalities. To prevent fatalities from this source, it has been advocated that every foot of trolley wire in mines should be guarded. While some such drastic step may appear to be amply justified, a closer examination of the records shows that lack of guards is not entirely responsible but rather that carelessness and neglect in the observance of certain well-established simple rules concerning installation and location of trolley wires must also bear a share in the responsibility. In -other words, if trolley wire is installed carelessly and its maintenance neglected, failure may be expected of any guards that have been put up.There are a-number of factors affecting safety as related to trolley wires in mines, among which the following may be enumerated.1. Installation relative to track and passageways.2. Guarding.3. Maintenance.4. Discipline.Acknowledgment is made to D. Harrington and K. L. Marshall of the safety division of the bureau for assistance given in securing data on cost of installing guards for trolley wires.The statement that fatalities should not be charged in every case to lack of guards is supported by the following example: A man operating a locomotive was electrocuted when the trolley wheel jumped the 250-volt trolley wire and allowed it to sag against his shoulder. He was sitting in the regular place provided in the locomotive, but the wire was 11 inches inside of the rail and only 39 inches above it where the wire touched him, or 11 inches from the roof at a distance of 12 feet from the nearest hanger. The accident occurred between two hangers 44 feet apart, and the trolley wire was inside the rail over the entire distance, being 2 inches inside at one hanger and 10 inches inside at the other hanger. A bolt in the roof indicated that there had been a hanger at one time between the two on the 44-foot span.This example is a violation of good practice in the installation and maintenance of trolley wire. In the first place the wire should have been outside instead of inside the rail. In the second place there should have been at least one intermediate hanger so that the span would not be so great and the sag would be reduced. Furthermore, it is possible that the wire was not taut enough even when the intermediate hanger was in place.To provide a degree of safety for men in the mines certain coal-mining States, recognizing the need, have enacted laws to regulate the installation of trolley wires. These limit the distance that the wire must be kept outside and above the rail. Thus, the 1927 mining laws of Ohio specify that:"

Apr 1, 1932

By Jonisha P. Pollard

In restricted vertical working heights such as low-seam coal mines, workers are forced to assume kneeling or squatting postures to perform work. These postures are associated with increased risks for the development of significant knee pathologies such as meniscal tears and osteoarthritis [1,2]. Previous research has shown an increased applied knee flexion moment when kneeling in high flexion [3]. However, these models have been applied to flexion up to 140° which neglects contact between the thigh and calf which occurs beyond 140°. In addition to thigh-calf contact, when kneeling near full flexion there may be additional contact between the heel and gluteal muscles. To the author?s knowledge, heel-gluteus contact has not been previously investigated, but thigh-calf contact has received some attention. Zelle (2007) reported thigh-calf contact forces up to 30% bodyweight (BW) [4]. Zelle (2009) reported decreased knee forces when accounting for thigh-calf contact [5]. Caruntu (2003) reported erroneous force and moment estimations when thigh-calf contact was neglected from models to determine muscle and ligament forces [6]. In this study thigh-calf and heel-gluteus contact forces were quantified to determine their effect on the externally applied flexion moment in high flexion.

Jan 1, 2009