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Background: Although neuromuscular indices have been extensively studied in adolescents and adults, limited data exist for prepubescent children.

Hypothesis: No differences exist between prepubescent boys and girls in lower limb strength, symmetry on single-legged hop testing, and limb alignment during drop-jump testing.

Study Design: Cross-sectional study (prevalence); Level of evidence, 1.

Methods: The authors tested 27 female and 25 male athletes who were aged 9 to 10 years and matched for both body mass index and years of organized sports participation. In a drop-jump screening test, the distance between the right and left hips, knees, and ankles was measured as an indicator of lower limb axial alignment in the coronal plane. The distance between the knees and ankles was normalized by the hip separation distance. Quadriceps and hamstrings strengths were measured isokinetically at 180 deg/s. Lower limb symmetry was determined from 2 single-legged hop function tests.

Results: Boys demonstrated greater mean absolute and normalized knee and ankle separation distances on the drop-jump test. Even so, 76% of boys had a normalized knee separation distance of 60% or less of the hip separation distance, as did 93% of girls, indicating a distinctly valgus alignment. There were no differences between the sexes in quadriceps and hamstrings peak torques, hamstrings/quadriceps ratio, time to peak torque, total work, or lower limb symmetry values.

Conclusions: A high percentage of the prepubescent athletes studied had a distinctly valgus lower limb alignment during the drop-jump test and a lack of lower limb symmetry during the hop tests. These same indices have been hypothesized to increase the risk for knee ligament injuries in older athletes. Neuromuscular training may be needed to address these issues in children.

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Purpose: Anterior cruciate ligament (ACL) reconstruction is commonly performed in athletes, with

the goal of return to sports activities. Unfortunately, this operation may fail, and the rates of either

reinjuring an ACL-reconstructed knee or sustaining an ACL rupture to the contralateral knee range

from 3% to 49%. One problem that exists is a lack of information and consensus regarding the

appropriate criteria for releasing patients to unrestricted sports activities postoperatively. The purpose

of this study was to determine the published criteria used to allow athletes to return to unrestricted

sports activities after ACL reconstruction. Methods: A systematic search was performed to identify

the factors investigators used to determine when return to athletics was allowed after primary ACL

reconstruction. Inclusion criteria were English language, publication within the last 10 years, clinical

trial, all adult patients, primary ACL reconstruction, original research investigation, and minimum 12

months’ follow-up. Results: Of 716 studies identified, 264 met the inclusion criteria. Of these, 105

(40%) failed to provide any criteria for return to sports after ACL reconstruction. In 84 studies (32%)

the amount of time postoperatively was the only criterion provided. In 40 studies (15%) the amount

of time along with subjective criteria were given. Only 35 studies (13%) noted objective criteria

required for return to athletics. These criteria included muscle strength or thigh circumference (28

studies), general knee examination (15 studies), single-leg hop tests (10 studies), Lachman rating (1

study), and validated questionnaires (1 study). Conclusions: The results of this systematic review

show noteworthy problems and a lack of objective assessment before release to unrestricted sports

activities. General recommendations are made for quantification of muscle strength, stability,

neuromuscular control, and function in patients who desire to return to athletics after ACL reconstruction,

with acknowledgment of the need for continued research in this area. Level of Evidence:

Level IV, systematic review of Level I to IV studies.