Plantar loading during cutting while wearing a rigid carbon fiber insert.

CONTEXT: Stress fractures are one of the most common injuries in sports, accounting for approximately 10% of all overuse injuries. Treatment of fifth metatarsal stress fractures involves both surgical and nonsurgical interventions. Fifth metatarsal stress fractures are difficult to treat because of the risks of delayed union, nonunion, and recurrent injuries. Most of these injuries occur during agility tasks, such as those performed in soccer, basketball, and lacrosse. OBJECTIVE: To examine the effect of a rigid carbon graphite footplate on plantar loading during 2 agility tasks. DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 19 recreational male athletes with no history of lower extremity injury in the past 6 months and no previous metatarsal stress fractures were tested. MAIN OUTCOME MEASURE(S): Seven 45° side-cut and crossover-cut tasks were completed in a shoe with or without a full-length rigid carbon plate. Testing order between the shoe conditions and the 2 cutting tasks was randomized. Plantar-loading data were recorded using instrumented insoles. Peak pressure, maximum force, force-time integral, and contact area beneath the total foot, the medial and lateral midfoot, and the medial, middle, and lateral forefoot were analyzed. A series of paired t tests was used to examine differences between the footwear conditions (carbon graphite footplate, shod) for both cutting tasks independently (α = .05). RESULTS: During the side-cut task, the footplate increased total foot and lateral midfoot peak pressures while decreasing contact area and lateral midfoot force-time integral. During the crossover-cut task, the footplate increased total foot and lateral midfoot peak pressure and lateral forefoot force-time integral while decreasing total and lateral forefoot contact area. CONCLUSIONS: Although a rigid carbon graphite footplate altered some aspects of the plantar-pressure profile during cutting in uninjured participants, it was ineffective in reducing plantar loading beneath the fifth metatarsal.

Plantar loading during jumping while wearing a rigid carbon graphite footplate.

Fifth metatarsal stress fractures are common in sports and often result in delayed and non-union. The purpose of this study was to examine the effect of a rigid carbon graphite footplate (CGF) on plantar loading during take-off and landing from a jump. Nineteen recreational male athletes with no history of lower extremity injury in the past 6 months and no foot or ankle surgery in the past 3 years participated in this study. Subjects completed 7 jumping tasks while wearing a standard running shoe and then the shoe plus the CGF while plantar loading data was recorded. A series of paired t-tests were used to examine differences between the two footwear conditions independently for both takeoff and landing (a = 0.05). The contact area in the medial midfoot (p < .001) and forefoot (p = .010) statistically decreased when wearing the CGFP. The force­time integral was significantly greater when wearing the CGFP in the middle (p < .001) and lateral forefoot (p = .019). Maximum force was significantly greater beneath the middle (p < .001) and lateral forefoot (p < .001) when wearing the CGFP, while it was decreased beneath the medial midfoot (p < .001). During landing, the contact area beneath the medial (p = .017) and lateral midfoot (p = .004) were significantly decreased when wearing the CGFP. The force­ time integral was significantly decrease beneath the medial midfoot (p < .001) when wearing the CGFP. The maximum force was significantly greater beneath the medial (p = .047) and middle forefoot (p = .001) when the subject was wearing the CGFP. The maximum force beneath the medial midfoot (p < .001) was significantly reduced when wearing the carbon graphite footplate. The results of the study indicate that the CGF is ineffective at reducing plantar loading during jumping and landing.

Plantar Loading During Cutting While Wearing a Rigid Carbon Fiber Insert.

Context : Stress fractures are one of the most common injuries in sports, accounting for approximately 10% of all overuse injuries. Treatment of fifth metatarsal stress fractures involves both surgical and nonsurgical interventions. Fifth metatarsal stress fractures are difficult to treat because of the risks of delayed union, nonunion, and recurrent injuries. Most of these injuries occur during agility tasks, such as those performed in soccer, basketball, and lacrosse. Objective : To examine the effect of a rigid carbon graphite footplate on plantar loading during 2 agility tasks. Design : Crossover study. Setting : Laboratory. Patients or Other Participants : A total of 19 recreational male athletes with no history of lower extremity injury in the past 6 months and no previous metatarsal stress fractures were tested. Main Outcome Measure(s) : Seven 45° side-cut and crossover-cut tasks were completed in a shoe with or without a full-length rigid carbon plate. Testing order between the shoe conditions and the 2 cutting tasks was randomized. Plantar-loading data were recorded using instrumented insoles. Peak pressure, maximum force, force-time integral, and contact area beneath the total foot, the medial and lateral midfoot, and the medial, middle, and lateral forefoot were analyzed. A series of paired t tests was used to examine differences between the footwear conditions (carbon graphite footplate, shod) for both cutting tasks independently (α = .05). Results : During the side-cut task, the footplate increased total foot and lateral midfoot peak pressures while decreasing contact area and lateral midfoot force-time integral. During the crossover-cut task, the footplate increased total foot and lateral midfoot peak pressure and lateral forefoot force-time integral while decreasing total and lateral forefoot contact area. Conclusions : Although a rigid carbon graphite footplate altered some aspects of the plantar- pressure profile during cutting in uninjured participants, it was ineffective in reducing plantar loading beneath the fifth metatarsal.

Stair ascending and descending in hip resurfacing and large head total hip arthroplasty patients.

Large head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) are alternatives to standard THA that generally have head sizes larger than 36mm. This study examined 20 patients (10 large head THA and 10 HRA), at an average of 18months postoperatively, and 15 healthy control subjects during stair negotiation. Hip kinetic and kinematic variables and ground reaction forces were measured. The THA and HRA groups ascended the stairs with increased peak hip flexion angles and decreased hip extension angles as compared with controls. The operative groups also descended the stairs with decreased hip flexion moments. No differences between the operative groups were observed. Eighteen months postoperatively, patients with large head THA or HRA display abnormal flexion and extension during a physically-demanding task.

Effect of increased weight on ankle mechanics and spatial temporal gait mechanics in healthy controls.

BACKGROUND: Ankle osteoarthritis has been associated with trauma, instability, and inflammatory arthritis. Limited literature exists examining the effect of body weight on ankle joint loading. The purpose of this study was to examine the relationship between increased weight and gender on ankle kinematics and kinetics. METHODS: Fifty-three (28 male, 25 female) subjects were recruited for the study. All subjects underwent a standard level walking gait analysis in four different weight conditions (normal, 10%, 15%, and 20% increased body weight). Testing order was randomized. A series of mixed-factor, repeated-measures analyses of variance (weight by gender) were used to determine statistical differences between the groups (p < .05). RESULTS: Walking speed was not significantly different between gender or weight conditions. No significant differences existed for step length, step time, stride length, swing time, or sagittal plane ankle kinematics and kinetics. A significant increase in plantarflexion moment existed for the males (p < .05). The peak plantarflexion moment increased as weight increased. Single support time (p = .042) was significantly different between the no weight and the 15% and 20% increased weight conditions. In addition, double support time was significantly longer in the males compared with females (p < .001) and significantly increased for each weight condition (p < .001). CONCLUSION: Increasing weight alters spatial temporal mechanics and sagittal plane ankle kinetics in a healthy control population. The effect of increasing weight appears to be similar between genders. CLINICAL RELEVANCE: The findings of the present study may be relevant for future studies to assess the role of weight as a potential covariate on postoperative outcomes and gait mechanics.

Differences in wrist mechanics during the golf swing based on golf handicap.

OBJECTIVES: Variation in swing mechanics between golfers of different skill levels has been previously reported. To investigate if differences in three-dimensional wrist kinematics and the angle of golf club descent between low and high handicap golfers. DESIGN: A descriptive laboratory study was performed with twenty-eight male golfers divided into two groups, low handicap golfers (handicap = 0-5, n = 15) and high handicap golfers (handicap ≥ 10, n = 13). METHODS: Bilateral peak three-dimensional wrist mechanics, bilateral wrist mechanics at ball contact (BC), peak angle of descent from the end of the backswing to ball contact, and the angle of descent when the forearm was parallel to the ground (DEC-PAR) were determined using an 8 camera motion capture system. Independent t-tests were completed for each study variable (α = 0.05). Pearson correlation coefficients were determined between golf handicap and each of the study variables. RESULTS: The peak lead arm radial deviation (5.7 degrees, p = 0.008), lead arm radial deviation at ball contact (7.1 degrees, p = 0.001), and DEC-PAR (15.8 degrees, p = 0.002) were significantly greater in the high handicap group. CONCLUSION: In comparison with golfers with a low handicap, golfers with a high handicap have increased radial deviation during the golf swing and at ball contact.

Gait symmetry: a comparison of hip resurfacing and jumbo head total hip arthroplasty patients.

Proponents of large femoral head total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) have touted the potential for restoration of more normal hip kinematics. This study examined 20 patients (10 THA and 10 HRA patients) approximately 18 months after surgery. Subjects were evaluated at a self-selected pace, while bilateral spatial-temporal gait variables, hip flexion/extension kinematics, and ground reaction forces were collected. For both groups, swing time was increased on the surgical side, whereas peak hip flexion, peak extension, and flexion at heel strike were decreased. Peak hip extension and peak vertical ground reaction forces were decreased in THA subjects compared with HRA subjects. After a large-diameter THA or HRA, subjects do not display symmetric gait approximately 18 months postoperatively. Total hip arthroplasty subjects demonstrated restricted hip extension and reduced limb loading when compared with HRA subjects.

Three-dimensional ankle kinematics and kinetics during running in women.

Stress fractures are common in athletics and are more prevalent in women. The current literature has not identified a reason for this gender difference. We hypothesized that females with a history of a second/third metatarsal stress fracture will demonstrate differences in ankle kinematics, kinetics and ground reaction forces when compared with a group of age-matched females with no stress fracture history. A total of 15 control females and nine females with a history of a second/third metatarsal stress fracture were asked to run at 3.3m/s+/-5% along a 10-m runway. Kinematics and kinetics were obtained using an 8-camera motion analysis system (240Hz) and two force plates (1200Hz). Significant differences existed in height and weight between the groups. No other statistically significant differences existed between the fracture group and the control group. Kinematic measurements do not differ significantly between women with a history of second/third metatarsal stress fracture and female control subjects. The reported kinematic and kinetic measurements do not appear to be influenced in subjects with metatarsal stress fractures, which likely result from the complex relationships between the joints in the foot and ankle. The development of second/third metatarsal stress fractures could result more from over training or changes in plantar loading instead of changes in lower extremity joint kinematics while running.

Effect of shoe type on plantar pressure: a gender comparison.

Despite the differences in materials, racing flats have begun to be used not only for racing, but also for daily training. As there are data suggesting a gender difference in overuse injuries in runners, shoe choice may affect loading patterns during running. The purpose was to determine differences in plantar pressure between genders when running in training shoes and racing flats. In-shoe plantar pressure data were collected from 34 subjects (17m, 17f) who ran over-ground in both a racing flat and training shoe. Contact area (CA), maximum force (MF), and contact time under the entire foot and beneath eight foot regions were collected. Each variable was analyzed using a shoe by gender repeated measures ANOVA (alpha=0.05). In men, MF was increased in the racing flats (p=0.016) beneath the medial midfoot (MMF), yet was increased beneath the medial forefoot (MFF) in the training shoe (p=0.018). Independent of gender, CA was decreased in the racing flats beneath the entire foot (p=0.029), the MMF (p=0.013), and the MFF (p=0.030), and increased beneath the lateral forefoot (LFF) (p=0.023). In the racing flats, MF was increased beneath the entire foot (p<0.001) and the LFF (p<0.001). Independent of the shoe, CA was decreased in men beneath the MFF (p=0.007) and middle forefoot (p<0.001), while MF was increased in the LFF (p=0.002). The LFF is an area of increased stress fracture risk in men. Based on the gender differences in loading, running shoe design should be gender specific in an attempt to prevent injuries.

Differences in plantar loading between training shoes and racing flats at a self-selected running speed.

The purpose of this study was to examine the difference in plantar loading between two different running shoe types. We hypothesized that a higher maximum force, peak pressure, and contact area would exist beneath the entire foot while running in a racing flat when compared to a training shoe. 37 athletes (17 male and 20 female) were recruited for this study. Subjects had no history of lower extremity injuries in the past six months, no history of foot or ankle surgery within the past 3 years, and no history of metatarsal stress fractures. Subjects had to be physically active and run at least 10 miles per week. Each subject ran on a 10m runway 7 times wearing two different running shoe types, the Nike Air Pegasus (training shoe) and the Nike Air Zoom Katana IV (racing flat). A Pedar-X in-shoe pressure measurement system sampling at 50Hz was used to collect plantar pressure data. Peak pressure, maximum force, and contact area beneath eight different anatomical regions of the foot as well as beneath the total foot were obtained. The results of this study demonstrated a significant difference between training shoes and racing flats in terms of peak pressure, maximum force, and contact area. The significant differences measured between the two shoes can be of importance when examining the influence of shoe type on the occurrence of stress fractures in runners.

Plantar loading comparisons between women with a history of second metatarsal stress fractures and normal controls.

BACKGROUND: Stress fractures are common in athletics and are more prevalent in women. The current literature has not identified a reason for this gender difference. HYPOTHESIS: Women with a history of a second/third metatarsal stress fracture will demonstrate differences in loading in the middle forefoot. STUDY DESIGN: Controlled laboratory study. METHODS: Fifteen men, 15 control women, and 9 women with a history of a second/third metatarsal stress fracture were asked to run at 3.3 m/s +/- 5% along a 10-m runway. Plantar loading parameters were recorded using a Pedar-X system. RESULTS: The women with fractures demonstrated a decrease in contact area and maximum force beneath the middle forefoot when compared with the female controls. Men demonstrated a decreased contact area in the medial and middle forefoot when compared with the control women. In addition, the women with fractures had decreased maximum force in the middle forefoot when compared with the control women. CONCLUSIONS: The decrease in maximum force in the middle forefoot in patients with a previous stress fracture could have resulted from gait alterations after the fracture. Therefore, prospective studies need to be completed to better understand the loading differences that could be used to predict stress-fracture injury risk. CLINICAL RELEVANCE: It is unclear whether plantar loading can be used as a predictor of stress-fracture injury risk as these patients were tested after a stress fracture.

Hamstring muscle kinematics and activation during overground sprinting.

Hamstring muscle strain injury is one of the most commonly seen injuries in sports such as track and field, soccer, football, and rugby. The purpose of this study was to advance our understanding of the mechanisms of hamstring muscle strain injuries during over ground sprinting by investigating hamstring muscle-tendon kinematics and muscle activation. Three-dimensional videographic and electromyographic (EMG) data were collected for 20 male runners, soccer or lacrosse players performing overground sprinting at their maximum effort. Hamstring muscle-tendon lengths, elongation velocities, and linear envelop EMG data were analyzed for a running gait cycle of the dominant leg. Hamstring muscles exhibited eccentric contractions during the late stance phase as well as during the late swing phase of overground sprinting. The peak eccentric contraction speeds of the hamstring muscles were significantly greater during the late swing phase than during the late stance phase (p=0.001) while the hamstring muscle-tendon lengths at the peak eccentric contraction speeds were significantly greater during the late stance phase than during the late swing phase (p=0.001). No significant differences existed in the maximum hamstring muscle-tendon lengths between the two eccentric contractions. The potential for hamstring muscle strain injury exists during the late stance phase as well as during the late swing phases of overground sprinting.