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 purpose of this study was to determine if the parachutist ankle brace (PAB) decreases the number and severity of ankle injuries in an airborne Ranger battalion. A retrospective study was performed covering a 38-month period. A computer database was used to track all jump injuries with a diagnosis of ankle pain, sprain, or fracture. The frequency was calculated for ankle injuries per 1,000 jumps and the average length of medically restricted duty per ankle injury. A total of 13,782 static line parachute jumps were conducted during the study period. Without the PAB, 35 ankle injuries were seen (4.51 1,000 jumps), with 9 fractures and 316 days of medical restriction per 1,000 jumps. Using the PAB, 9 ankle injuries were seen (1.511,000 jumps), with 3 fractures and 71 days of medical restriction per 1,000 jumps. The correct use of the PAB appeared to significantly decrease the incidence of ankle injuries in this battalion.

Introduction

Ankle injuries are the leading injury in airborne Ranger battalions during parachute operations, both in training and in combat. Ankle injuries account for approximately 20% of all injuries related to parachuting in the Rangers, resulting in significant training time and manpower lost to injury. Other studies have reported ankle injuries accounting for 15 to 60% of all injuries sustained during military parachuting.4-11

To decrease these injuries, the parachutist ankle brace (PAB) was developed by the U.S. Army Research Institute of Environmental Medicine and adopted by the Army for use in airborne operations.12 The brace is a one-piece, outside-the-boot brace with a hard plastic outer shell lined with air cells that pad the medial and lateral malleolus (Aircast, Summit, NJ). The brace connects distally by a 2-inch plastic posterior bar. It has a rubber heel strap and two Velcro straps proximal to the ankle that secure the brace to the jumper's leg. The brace allows ankle plantar flexion and dorsiflexion but prevents extremes of ankle motion in inversion and eversion (Fig. 1). At this time, use of the PAB in operational units is variable.

The PAB was tested at the U.S. Army Airborne School and found to reduce the frequency of ankle injuries in personnel making their initial five jumps.13 However, there are no reports on the use of the PAB in an operational airborne unit. This study examines the effectiveness of regular use of the PAB in reducing ankle injuries in an airborne Ranger battalion conducting realistic unit training jumps under simulated combat conditions with experienced jumpers.

Materials and Methods

The data presented here evolved as a natural experiment. This study compares the injury rates from two consecutive cohorts. The first period was from November 1994 through September 1996, when the PAB was not worn in this unit; the second period was from October 1996 through December 1997, after PAB use became mandatory for all parachute jumps in this unit. A review was done of data collected in a database of all sick call and emergency room visits during this 38-month period in which the patient complained of a duty-limiting injury from parachuting. Any injury that required a modification of duty was seen by one of two medical officers (physician or physician assistant) assigned to the battalion before the patient was placed on restricted duty.

We defined an ankle injury as any ankle pain, swelling, or deformity caused by grade I to III ankle sprains and distal tibia/ fibula contusions or fractures. This study did not include metatarsal or calcaneal contusions or fractures in the definition of ankle injury. Additionally, all other injuries sustained during the study period were also tracked by location (e.g., foot, back, knee, etc). Each injury diagnosis was tracked from the date of injury until the Ranger returned to unrestricted duty. Rangers were removed from medical restriction once they could perform all activities with their squad for the same duration and intensity. If a Ranger returned to duty too soon and could not complete all activities such as running or road marching, he was returned to medically restricted duty status with a start date from the original injury.

All soldiers who were members of the 3d Ranger Battalion from November 1994 through December 1997 were included in the study. Injuries that occurred to a member of the battalion when not jumping as part of the battalion were excluded, e.g., during U.S. Army Ranger School. The PAB was not used during any deliberate water jumps, and all of these jumps were excluded from the study data. Military free-fall jumps were also excluded from the study.

A second database of all airborne operations conducted by the battalion was used to track date, time (day or night), aircraft type, parachute type, number of jumpers, wind speed, with or without ankle braces, with or without equipment (rucksack and weapons), and type of drop zone (field, improved airfield, etc.). The jumps were conducted mostly at night onto fields or airfields from U.S. Air Force C- 141 or C-130 aircraft using TIO-C static-line parachutes in low to moderate winds (0-13 knots) with combat equipment. The only significant difference in the execution of parachute jumps during the study period was the introduction of the PAB and elbow and knee pads. In October 1996, all personnel in the battalion were issued one pair of ankle braces and elbow and knee pads with hard plastic exterior shells. Leaders and jumpmasters enforced the policy of wearing ankle braces during airborne operations conducted from October 1996 through December 1997. The ankle braces were inspected during sustained airborne training (prejump training). The elbow and knee pads were worn only when parachuting onto airfields.