Bursitis of the Shoulder in Coal Miners Using Boring Machines
Occupational and Environmental Medicine
The boring machine may in certain circumstances cause well-defined lesions of the skin and deeper structures of the shoulder loosely termed " beat shoulder ". Although these lesions have not been specifically described many doctors in mining areas are aware of their association. We have examined clinically 35 full-time borers only three of whom presented themselves for treatment at a colliery medical centre. The rest were selected at random from six collieries which gave a wide range of work in
... de range of work in different thicknesses of seam, a factor which was early realized to be important. The Machine and Working Environment The boring machine with trailing cable weighs approximately 40 lb. It is not a percussive tool but consists of a long drill driven by an electric motor having a substantial base against which the men push ( Fig. 1) . The electric motor is geared down from 2,400 r.p.m. to 750-500 r.p.m. on the actual drill. At intervals along the coal face holes are bored to depths varying from 2 ft. to 4 ft. 6 in., that is 6 in. less than the depth of coal cut by the coal-cutting machine. When the coal is cut near the floor the holes are bored near the roof or, alternatively, near FIG. 1.-The boring machine. the floor when the coal is cut near the roof. The former is more common. Explosive is inserted into the hole and then fired to loosen the coal. A full-time borer will bore between 70 and 150 holes per shift of seven and a half hours. For top hole boring the borer presses his shoulder against the base of the boring machine, the relationship of this base to the shoulder region varying with seam thickness and the idiosyncrasy of the operator. For bottom hole boring the borer usually uses his feet. When roadways are enlarged or developed boring occasionally is required, and here it is in stone, not coal. The majority of cases we have described are of borers drilling in coal. Clinical Findings The exact relationship of the skin of the shoulder to the base plate of the machine plays a large part in determining the variance in the clinical picture, this in turn being related to the seam thickness and personal habits of the operator. The tissue changes in the region of the shoulder are in the skin (bruising, pigmentation, and sepsis) and in the formation of bursae, of which two types are described; one lying near the point of the shoulder being superficial and subcutaneous, the other lying medially below the lateral third of the clavicle and partially deep to the medial fibres of deltoid. This latter bursa may be a continuation of the sub-deltoid bursa. Three cases were radiographed (one in Group II and two in Group III) and showed no abnormality. Cases Grouped According to Physical Signs The borers could be divided into four groups. Group I.-Nine men had no signs or symptoms. Group 11.-Eight men each had a large bursa situated below the lateral third of the clavicle, also showing diffuse skin changes. 265 on 22 July 2018 by guest. Protected by copyright.