Abstract: A generally rectangular intra-spinous spacer preferably made of bone material advantageously has a low potential for bone fusion. The spacer has depressions sized and positioned on opposite sides to receive spinal processes. The depressions reduce the amount of bone-to-spinal process contact. A fixation strap of the spacer secured either to both the superior and inferior spinous processes or to only one of the superior or inferior processes laterally maintains the implanted position of the spacer and limits either flexion and extension, just flexion, or just extension.

Abstract: A device for guarding and retaining a cotter pin in place after insertion in a pin or bolt. The device is formed from springy sheet material, preferably in the form of a spring steel stamping. It has a washer portion with a central opening to fit over a pin or bolt and a shelf portion extending to one side. The washer portion has one or more tabs or spurs which frictionally engage the shank of a pin or bolt so as to retain the washer in place thereon. The shelf portion is joined to the washer portion by a step or shoulder. At its outer end the shelf has a fence which extends from the floor of the shelf in the same direction as the step. The step has an opening through which the shank of a cotter pin may be inserted on through the aperture in a pin or bolt. The shelf may be flexed so the fence is out of the way when a cotter pin is inserted. On release the shelf springs back in place and the fence is in position to engage the head of the cotter pin and prevent its removal.

Abstract: A device for automatically spreading and locking cotter pins as they are driven into place. The device is an improvement on the cotter pin spreading devices disclosed in U.S. Pat. Nos. 1,751,013 dated Mar. 18, 1930 and 2,345,141 dated Mar. 28, 1944. The improved devices have locking extensions which, during the act of driving cotter pins into place, become deformed into locking engagement with the heads on the driven and spread cotter pins. Several forms of locking extensions are disclosed.

Abstract: A combined washer and cotter pin anti-snag device comprises a base portion, a raised portion integral with the base portion, a transverse hole in the raised portion through which a fastener is adapted to extend, and a longitudinal hole in the raised portion above the base portion through which a cotter pin is adapted to extend so that the legs of the cotter pin may be passed through the fastener and then be spread apart above the base portion.