Lower preseason reactive strength index scores are associated with injury in female collegiate volleyball players but not male collegiate basketball players.

OBJECTIVES: Functional tests are used by sports medicine professionals to discriminate injury risk in athletes. One test that has shown promise is the drop vertical jump (DVJ); however, it is primarily used to evaluate measures associated with anterior cruciate ligament injury. The DVJ test can also be used to calculate the reactive strength index (RSI); a measure used to assess an athlete's power. The ability of the RSI to discriminate injury risk is unknown. The purpose of this study was to prospectively evaluate the ability of preseason RSI scores to identify athletes at risk for a noncontact time-loss injury to the low back or lower extremities. DESIGN: Prospective cohort. METHODS: One hundred and fifty-five male collegiate basketball (BB) players and 117 female collegiate volleyball (VB) players were recruited for this study. DVJ tests were performed in a motion capture lab. RESULTS: Female VB players with a RSI 0.9125m/s or less (30.48cm box) were 4 times (relative risk=4.2 [95% CI: 1.0, 17.7]; p-value=0.024) more likely to be injured. There was no association between preseason scores and injury in the male BB athletes. CONCLUSION: RSI scores should be collected for female collegiate VB players as part of a preseason screen.

Prevalence of Patellar Tendinopathy and Patellar Tendon Abnormality in Male Collegiate Basketball Players: A Cross-Sectional Study.

CONTEXT: Patellar tendinopathy (PT) is a degenerative condition known to affect athletes who participate in sports such as basketball and volleyball. Patellar tendinopathy is a challenging condition to treat and may cause an athlete to prematurely retire from sport. The prevalence of PT in male collegiate basketball players is unknown. OBJECTIVE: To determine the prevalence of PT and patellar tendon abnormality (PTA) in a population of male collegiate basketball players. DESIGN: Cross-sectional study. SETTING: National Collegiate Athletic Association Divisions II and III, National Association of Intercollegiate Athletics, and Northwest Athletic Conference male collegiate basketball teams were assessed in a university laboratory setting. PATIENTS OR OTHER PARTICIPANTS: Ninety-five male collegiate basketball players (age = 20.0 ± 1.7 years). MAIN OUTCOME MEASURE(S): A diagnostic ultrasound image of an athlete's patellar tendon was obtained from each knee. Patellar tendinopathy was identified based on a player's symptoms (pain with palpation) and the presence of a hypoechoic region on an ultrasonographic image. RESULTS: A majority of participants, 53 of 95 (55.8%), did not present with pain during palpation or ultrasonographic evidence of PTA. Thirty-two basketball players (33.7%) displayed ultrasonographic evidence of PTA in at least 1 knee; 20 of those athletes (21.1%) had PT (pain and tendon abnormality). Nonstarters were 3.5 times more likely to present with PTA (odds ratio = 3.5, 95% confidence interval = 1.3, 9.6; P = .017) and 4 times more likely to present with PT (odds ratio = 4.0, 95% confidence interval = 1.1, 14.8; P = .038) at the start of the season. CONCLUSIONS: One in 3 male collegiate basketball players presented with either PT or PTA. Sports medicine professionals should evaluate basketball athletes for PT and PTA as part of a preseason screening protocol.

Gait patterns in children with limb length discrepancy.

BACKGROUND: Very few articles describe the compensations in gait caused by limb-length discrepancy (LLD). Song and colleagues explored kinematic and kinetic variables utilizing work equalization as a marker of successful compensation for LLD. They found no difference in strategies based on the location of pathology. The purpose of this study was to define the various gait patterns in patients with LLD and the impact of these compensations on gait kinetics. METHODS: Forty-three children (mean age 12.9±3.7 y) with LLD >2 cm were evaluated in the motion lab using a VICON motion system with 2 AMTI force plates. Etiologies included Legg-Calve-Perthes, developmental hip dysplasia, growth plate damage due to infection or trauma, congenital shortening of the femur or tibia, and syndromes creating shortening of the limb. Evaluation included physical examination and 3-dimensional motion data generated using the model described by Vicon Clinical Manager (VCM). For data analysis, 3 representative trials were processed with the Plug-in Gait lower-body model using the "VCM spline" filter. Walking strategies were identified by visual review. A kinematic threshold of 2 SD away from normal values was used for inclusion in each group. Strategies included: (1) pelvic obliquity with the short side lower (<-1.5 degrees); (2) flexion of the knee of the longer leg in stance (>5.2 degrees); (3) plantar flexion of the ankle on the shorter leg through the gait cycle (<0 degrees); and (4) early plantarflexion crossover of the shorter limb (plantarflexion crossover occurred before 35% of the gait cycle). Variables were extracted into Excel using PECS (Vicon Motion Systems). The mean of the 3 trials was used for analysis. Scanograms were used to establish lengths of the femur and the lower leg including the foot. The percentage difference for the subject (%LLD) was calculated as the leg length between the 2 sides divided by the length of the long side. The total mechanical work over the stride was the sum of the positive work and the absolute value of the negative work in all planes. Paired t tests were used to analyze the work differences between the short limb versus the long limb. Unpaired t tests were used to compare between the different groups (short tibias, short femurs, and controls). RESULTS: Distribution of single strategies for the group included: pelvis (11), equinis (5), vaulting (7), knee flexion (3); 17 subjects used multiple strategies. If the discrepancy was in the femur, patients chose a more distal compensation strategy, utilizing ankle movements, which resulted in more work at the ankle joint on the short limb compared with normal (P<0.0001). All subjects with tibia shortening showed pelvic obliquity (3 combined with knee flexion), which caused more work at the hip joint on the short limb compared with normal (P<0.01). Total mechanical work on the uninvolved limb was above normal for all groups (P<0.0001). CONCLUSIONS: Our study contradicts previous literature that found no difference in strategy on the basis of location of the shortening and also a higher number of children with pelvic obliquity than previously described. It appears that different compensation schemes are used by patients with LLD. The increase in work may have long-term implications for management. Future studies will include changes in kinematics and work, after intervention. Better understanding of postoperative changes from different surgical methods may provide more insight for preoperative planning and may lead to a more satisfactory outcome for specific patients. LEVEL OF EVIDENCE: Level II.

Iliopsoas tenotomy at the lesser trochanter versus at the pelvic brim in ambulatory children with cerebral palsy.

BACKGROUND: Progressive hip flexion deformity is a common problem in ambulatory children with spastic cerebral palsy, causing static and dynamic deformity. The iliopsoas muscle is recognized as a major deforming force in the development of this problem. Many clinicians address this problem by lengthening the iliopsoas, either in an intramuscular location at the pelvic brim or by complete tenotomy at the lesser trochanter. The goal of this study was to compare the outcomes of patients with ambulatory cerebral palsy who had intramuscular lengthening at the pelvic brim to those who underwent complete release of the iliopsoas tendon at the level of the lesser trochanter. METHODS: Twenty patients were included in the study, 11 of whom had iliopsoas release at the lesser trochanter (group 1) and 9 of whom had intramuscular lengthening at the pelvic brim (group 2). All patients had physical examinations, plus kinematic and kinetic analyses in our gait laboratory before and 1 year after surgery. RESULTS: Hip flexion contracture was decreased significantly only in group 1, although there was a trend of decrease in group 2. There was a significant increase in maximum hip extension in terminal stance and a reciprocal decrease in maximum swing phase hip flexion in group 1, with a similar trend that did not reach significance in group 2. Stride length increased significantly in both groups. There was no significant change in power generation of hip flexion during the swing phase in either group. CONCLUSIONS: We found improved static and dynamic parameters of hip extension after iliopsoas lengthening and did not detect any adverse kinematic or kinetic change in hip function after surgery. The improvement was more robust in the group who underwent release at the lesser trochanter. Because there are no adverse effects of iliopsoas release from the lesser trochanter and the improvement in hip extension is greater, this approach should be considered in ambulatory patients with spastic diplegia when a hip flexor weakening procedure is considered. LEVEL OF EVIDENCE: Comparative cohort study, level III, case-control study.

Comparison of rectus femoris transposition with traditional transfer for treatment of stiff knee gait in patients with cerebral palsy.

PURPOSE: To assess the outcome of children with cerebral palsy following reposition of the distal rectus femoris tendon for treatment of stiff knee gait. METHODS: Children with cerebral palsy with stiff knee gait who underwent rectus femoris transfer were studied retrospectively. Inclusion criteria were cerebral palsy of diplegic or quadriplegic type, preoperative and 1 year postoperative three-dimensional motion analysis, and no other surgery except rectus femoris transfer at the time of study. The patients were separated into two groups: in group I, the rectus femoris was transferred to the distal medial hamstring tendons, either the gracilis or the semitendinosus; in group II, the distal tendon of the rectus femoris was transposed laterally and attached to the iliotibial band/intermuscular septum. RESULTS: Peak knee flexion during swing phase, total dynamic knee range of motion, knee range of motion during swing phase, and time to peak knee flexion during swing phase were all improved in both groups. Hip and pelvic kinematics were not influenced by the surgery. Velocity, stride length, and cadence were all improved following the surgery. There was no difference between the transfer group and the transposition group. CONCLUSION: These findings suggest that distal transfer of the rectus femoris is effective in improving swing phase knee function by diminishing the mechanical effect of the dysphasic swing phase activity of the rectus femoris, not by converting the rectus femoris to an active knee flexor.

Triceps surae force, length and velocity during walking.

Individuals with neuromuscular conditions may develop muscle contractures that limit joint motion. Decreased muscle length is clinically obvious, but deviations in other functional characteristics of muscle, such as underlying weakness or decreased shortening velocity are more obscure. Therefore, a more comprehensive assessment of muscle characteristics may be required to fully restore function in these individuals. To provide normative comparison data on the force, length and velocity of the triceps surae during walking, 20 adults free from neuromuscular and orthopedic problems were assessed using instrumented gait analysis. Kinematic and kinetic data were used to calculate gastrocnemius and soleus length and velocity, and plantarflexor force during walking. Gastrocnemius length was shortest in early swing and longest in terminal swing and again in midstance. Soleus length was longest throughout the period of single limb stance and was shortest at foot-off. Gastrocnemius shortening velocity was greatest in early swing phase whereas soleus shortening velocity was greatest in pre-swing. Plantarflexor force increased steadily throughout stance phase and peaked in terminal stance at 33.8+/-3.6 N/kg bodyweight. These data provide target levels on the functional parameters of plantarflexor force, length and velocity in order that therapeutic and surgical interventions could be focused on the deviations observed, and the outcomes of these interventions more objectively assessed.

Length and force of the gastrocnemius and soleus during gait following tendo Achilles lengthenings in children with equinus.

Nine subjects (12 sides) with cerebral palsy who walked in equnius were evaluated prior to and 1 year after surgical tendo Achilles lengthening. Gastrocnemius and soleus length [Gait Posture, 6 (1997) 9] and plantarflexor force [Gait Posture, 6 (1997) 9; J Biomech, 23 (1990) 495] were calculated. The length of the gastrocnemius and soleus increased significantly (P<0.01) following the intervention. Force output of the triceps surae during push-off increased significantly (13.95 N/kg body weight (BW) preop to 30.31 N/kg BW postop; P<0.01). Assessment of the force-length capacity of the triceps surae in candidates for tendo Achilles lengthenings may identify individuals at risk of residual weakness and iatrogenic crouch.