ABSTRACT
Objective To make classification and segment measurement for the cases with tibiofibular and ankle fractures in parachuting landing, and investigate main classification types of parachuting fractures and fracture segments of high risk.Methods A total of 56 fracture cases in parachuting landing were collected, and the tibiofibula and ankle fractures were classified according to AO-OTA or Lauge-Hansen classification standards respectively based on their digital X-ray images. The medium plane between talus and tibia joint planes in ankle joint was defined as the reference plane. The highest and lowest injury points of tibia and fibula were marked respectively, and the fracture segment was defined between the highest and lowest point for statistical analysis.Results For tibiofibular and ankle fracture cases in parachuting landing, fracture at both tibia and fibula accounted for 80.4%. The major classification of tibiofibula fracture was 42-D/5.2 (45.8%) and 42-D/5.1 (16.7%). The major classification for ankle fracture was pronation-external rotation (PER, 59.4%) and supination-external rotation (SER, 37.5%). When tibiofibular and ankle fracture cases in parachuting landing occurred, the fracture segment of the tibia was mainly from 57 to 143 mm above the reference plane and from 6 mm below the reference plane to 24 mm above the reference plane, while the fracture segment of the fibula was 4-45 mm and 74-83 mm above the reference plane. Injury risks of all above segments were higher than 50%.Conclusions For protection of lower limbs in parachuting landing, the fracture at both tibia and fibula should be highly noticed. The ankle motion of PER and SER should be especially restricted in parachuting ankle protection.
ABSTRACT
Objective To study effects of backpack gravity center position on kinetics and kinematics of lower-extremity joints in parachuting landing and evaluate the injuries. Methods Seven participants performed parachuting landing with backpack gravity center on three positions: low-back (position 1), upper-back (position 2) and abdomen (position 3). Results The peak vertical ground reaction force (GRF) with backpack on position 2 was significantly lower than that on position 1. The joint moment on sagittal plane of the hip with backpack on position 2 was significantly higher than that on position 1 and position 3. The joint energy absorption of the hip with backpack on position 2 was significantly higher than that on position 1. The angular displacement of the hip on sagittal plane with backpack on position 2 was significantly higher than that on position 1 and was significantly lower than that on position 3. The angular velocity of the hip on sagittal plane with backpack on position 2 was significantly lower than that on position 3. Conclusions Different positions of backpack gravity center could significantly influence kinetic and kinematic parameters of the hip. Backpack gravity center on upper-back position could decrease the lower-extremity injuries. The results can provide evidences for evaluating backpack gravity center and decreasing injuries in parachuting landing.
ABSTRACT
Objective To study effects of different types of high-impact exercises on the increment of bone mineral density (BMD) and bone mineral content (BMC) . Methods Thirty-nine male volunteers, including 13 hoopsters, 13 paratroopers, and 13 common college students as the control, were recruited and divided into two subgroups (subgroup 1:20-22 years old; subgroup 2:23-25 years old). Their BMDs and BMCs on calcaneus, first through fifth metatarsus, hip, and lumbar spine (L1-4) were evaluated. Results The BMC of calcaneus, the first and second metatarsals, total lumbar spine, and total hip in the hoopster group was significantly higher than that in the control group and paratrooper group. The hoopster group obtained statistically higher BMD at the lumbar spine, hip, and femoral neck than the other two groups. However, the BMCs and BMDs of the paratrooper group and control group had no significant differences at almost all measured anatomical locations. Conclusions BMC and BMD are not always in positive correlation with vertical ground reaction forces during normal exercises. Compared with parachuting training, playing basketball as a kind of variable load exercise can effectively increase BMC and BMD, and is more beneficial for reducing the risk of osteoporotic fracture.