Serum vitamin D insufficiency is correlated with quadriceps neuromuscular functions in patients with anterior cruciate ligament injury: A preliminary study.

Background: This study aimed to investigate the correlations of serum vitamin D insufficiency with quadriceps neuromuscular function in patients with anterior cruciate ligament (ACL) injury. Methods: A cross-sectional study was conducted. Eighteen patients with a primary, unilateral ACL injury who had insufficient serum vitamin D concentrations (<30 ng/ml) were recruited for the study. Bilateral quadriceps neuromuscular function, including maximal strength, the speed of rapid contraction, and inhibition, were measured on an isokinetic dynamometer with the hip and the knee joint flexion at 90° and 45°, respectively. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC); the speed of rapid contraction was quantified by the rate of torque development (RTD), which was divided into the early (RTD0-50) and the late phase (RTD100-200); quadriceps inhibition was quantified by the central activation ratio (CAR). Serum vitamin D concentration was quantitatively determined by serum 25(OH)D concentration measured by the 25(OH)D ELISA kit. The Spearman rank correlation analysis was used to examine the correlation between the vitamin D concentration and bilateral quadriceps MVIC, RTD0-50, RTD100-200, and CAR, respectively. Results: The results of Spearman rank correlation analyses showed that the serum 25(OH)D concentration was significantly correlated with bilateral quadriceps MVIC (injured: r = 0.574, p = 0.013; uninjured: r = 0.650, p = 0.003) and RTD0-50 (r = 0.651, p = 0.003), and CAR (r = 0.662, p = 0.003) on the uninjured limb. However, no significant correlations were found between the serum 25(OH)D concentration and the other outcomes. Conclusions: The serum vitamin D concentration correlates with quadriceps neuromuscular function in patients with ACL injury who had vitamin D insufficiency.

Associations of patient characteristics, rate of torque development, voluntary activation of quadriceps with quadriceps strength, and knee function before anterior cruciate ligament reconstruction.

Good preoperative knee function (KF) and quadriceps strength (QS) relate to good prognoses after anterior cruciate ligament reconstruction (ACLR). This study aimed to investigate the associations between patient characteristics, rate of torque development (RTD), voluntary activation (VA) of the quadriceps against preoperative KF and QS. A cross-sectional study was conducted. Forty patients with a primary, unilateral ACL injury who had finished the preoperative rehabilitation and scheduled for an ACLR were included. KF was evaluated using the International Knee Documentation Committee score. QS was measured by maximal voluntary isometric contractions. RTD was divided into the early (RTD0-50) and the late (RTD100-200) phases. Quadriceps VA was measured using the superimposed burst technique. Our results showed that patients with poor preoperative KF had more deficits in RTD0-50 (P = 0.025), higher BMI(P = 0.043), and more meniscus injuries (MI) (P = 0.001) than those with good KF. Patients with asymmetrical QS showed lower BMI (P = 0.020) and shorter time from injury (TFI) (P = 0.027) than those with symmetrical QS. Additionally, a higher pre-injury Tegner score combined with greater RTD100-200 contributed to greater QS on the injured limb (R2 = 0.357, P = 0.001). To conclude, BMI, TFI, concomitant MI, pre-injury physical activity level, and quadriceps RTD are related to QS and KF before ACLR.

Bilateral impairments of quadriceps neuromuscular function occur early after anterior cruciate ligament injury.

The study aimed to investigate the impairments in quadriceps neuromuscular function, including strength, rate of torque development (RTD) and activation failure (QAF) early after an ACL injury. A cross-sectional study was conducted. Thirty physically active patients with a primary ACL injury within three months, aged 18 to 40 years old, and who were scheduled for ACL reconstruction were included. Thirty matched healthy controls were also recruited. All the outcomes were measured on an isokinetic dynamometer with knee flexion at 45°. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC). Early (RTD0-50) and late (RTD100-200) phases of RTD were retrieved from the MVIC test from 0 to 50 ms and 100-200 ms, respectively. QAF was quantified by the central activation ratio (CAR) measured by superimposed burst technique. The results of Mann-Whitney U test showed that compared with the healthy limbs, the injured limbs of the ACL group showed lower quadriceps strength (P < 0.001), RTD0-50 (P < 0.001) and RTD100-200 (P < 0.001); the uninjured limbs showed lower quadriceps strength (P = 0.009), RTD0-50 (P = 0.006) as well as greater QAF (P = 0.010). To conclude, bilateral quadriceps suffered from neuromuscular impairments early after an ACL injury.