effectiveness of the parachutist ankle brace in reducing ankle injuries in an airborne Ranger battalion, The

Military Medicine, Dec 2000 by Pope, Richard W

The U.S. Army has developed and fielded an over-the-boot ankle brace specifically for use in parachute operations.12 This PAB was tested at the U.S. Army Airborne School and found to reduce ankle injuries in students enrolled in the basic airborne course in a prospective study of 777 volunteer students completing their initial five parachute jumps. The airborne students make four daylight jumps and one night jump onto an open field. That study found that inversion injuries were reduced significantly in the group that wore the PAB.13 Ankle sprains occurred in 1.9% of the non-brace wearers and in 0.3% of the brace wearers, for a risk ratio 6.3:1. The authors of this wellcontrolled study relate the need for further testing in military populations outside the Airborne School.

The ability to estimate and decrease jump injuries assists commanders and medical personnel in planning military airborne operations.3,48 A previous study of parachute injuries sustained by the 3d Battalion, 75th Ranger Regiment in training operations found an overall injury rate of 2.2% (range, 1.4% day/field, 4.7% night/dirt airstrip).2 Interventions to decrease the morbidity from parachute operations will increase the number of troops available for training and combat operations. There is also the cost to the military for the medical care of the injured soldier, which includes medical equipment, supplies, and personnel involved in the soldier's care. Additionally, there is disruption of unit continuity; when a soldier is injured and unable to perform his daily duties, another soldier must fill the void until the injured soldier can resume full duty. There is also the added cost of training new personnel to replace those injured too badly to return to an airborne unit.

Our study conducted in an operational unit found that use of the PAB decreased the rate of ankle injuries by 67% (from 4.5 to 1.5/1,000 jumps; p = 0.002), and the ankle fracture rate decreased by 55% (from 1.1 to 0.5/1,000 jumps; p = 0.297). In addition, the number of days lost to medical restriction as a result of ankle injuries decreased 78%, from 316 days/ 1,000 jumps without the PAB to 71 days/ 1,000 jumps with the PAB (95% confidence interval, 306-327 days without the PAB and 69-78 days with the PAB). The overall rate of injury when jumping with the PAB also decreased (from 16.5 to 13.3/1,000 jumps) more than would be accounted for solely by the reduction in ankle injuries. Several factors could have contributed to the reduced overall injury rate: a slightly lower average wind speed (3.6 knots without the PAB versus 2.9 knots with the PAB) and changing the use of elbow and knee pads when jumping on airfields from elective to mandatory. However, a larger percentage of jumps with the PAB were done under conditions that normally increase injury rates, i.e., at night and onto airfield/ dirt airstrip drop zones.2

In studies of factors that are associated with parachuting injuries, wind speed, darkness, the jumper's load, and the type of drop zone (open field versus dirt airstrip) have all been found to be significant factors in injury rates.2,11,12 In a recent article, it was shown that experienced jumpers have different landing strategies than novice jumpers with respect to ground reactive forces and muscle utilization during landing.23 The previous study of the PAB was limited to novice jumpers. The study of Airborne School students might not translate to operational conditions because the majority of jumps conducted at the Airborne School are daylight jumps onto an open field without combat equipment. The Rangers in this study were more experienced parachutists, with an average of 34 static-line jumps (range, 7-200 jumps).2 During the PAB period, the 3d Ranger Battalion conducted the vast majority of jumps at night with combat equipment onto airfields.