Vitamin D to Improve Quadricep Muscle Strength

The dynamometer (Biodex System 4, Biodex Medical Systems Inc., New York, USA) will be used for measuring Isokinetic muscle strength in N. Subjects will perform a standardized warm-up exercise (5 min cycling) followed by the test. Concentric/concentric contractions of knee extension/flexion will be tested at 60°/s and 180°/s. Subjects will be seated on the dynamometer chair with their hips flexed to 85°.

Blood samples will be taken under non-fasting conditions. Serum / plasma obtained will be immediately stored at -80°C until analysis. Serum 25(OH) Vit-D assay: Serum 25(OH)Vit-D levels will be measured by commercial 25(OH) Vitamin D ELISA kit (Abcam ab213966) according to the manufacturer's instruction, providing the quantitative determination of 25(OH) Vitamin D3 and 25(OH) Vitamin D2. Sensitivity: 1.98 ng/ml (Range: 0.5 ng/ml - 1010 ng/ml).

Muscle volumes of quadricep muscle are measured using a 1.5 or 3.0 Tesla MRI Scanner. Axial (3mm thick cut) T1W images are obtained from the anterior superior iliac supine (ASIS) to patella. Quadriceps muscles were manually outlined in each axial slice. Muscle volume was calculated by summing all of the slice-multiplied by slice thickness. The quality of the muscle is assessed by analyzing the fat content of the muscle mass using technique that has been reported by Reeder et al (6). Bilateral legs will be performed before the start of the vitamin supplementation (4 months post-op) and with the injured side repeated after the completion of the 16-weeks supplementation (8 months postop).The uninjured side will be used as reference for 'normal volume'.

The Aixplorer® ultrasound system and a linear transducer probe with a bandwidth of 2-10 MHz were used to measure the muscle thickness of Vastus Medialis (VM), Vastus Lateralis (VL), and Rectus Femoris (RF) on both the injured and uninjured leg. Participants laid supine on a treatment table for the assessment. A measuring tape was used to locate VM, VL, RF and the patella by palpation, consequently marked with a pen for reference. RF was marked at 1/2 of the distance from the anterior superior iliac spine (ASIS) to the superior pole of the patella, VM was located at 1/5 of the distance away from the midpoint of the medial patella border to the ASIS, and VL was noted at 1/3 of the distance from the midpoint of the lateral patella border to the ASIS. After locating the anatomical points, excess contact gel was applied on these points. The transducer probe was aligned in the transverse plane and moved along the entire muscle bundle to capture a view of the VM, VL and RF.

To measure anterior-posterior knee laxity, the KT-1000 knee ligament arthrometer (MEDmetric Corp, San Diego, CA, USA) will be used. A manual force test will be applied until a 30lb sound signal is activated. Three trials will be performed. A side difference of 3 mm above is considered clinically relevant.

Body Mass Index (BMI) in kg/m^2 would be calculated by the measured height and weight at 4 months post ACLR before vitamin D supplements, during the eighth week of vitamin D supplements, after the completion of 16 weeks vitamin D supplements, and 12-months post-operation.

The Kinetic variables including vertical and horizontal ground reaction force (GRF) will be evaluated by a synchronized force plate at the centre of the capture volume at 1000Hz.

The kinematics will be assessed by the skin marker-based motion analysis system with the lower-body marker setup followed the OSTRC standard using 16-camera and 16 reflective skin marker during the single leg squat and single leg hop test.

The average of single leg hop distance in cm with three attempts will be measured during the single leg hop test.

The subjective measurement for chronic and acute pain will be recorded by the Visual Analogue Scale (VAS). VAS consists of a 10-cm line which represents the continuum between "painless" and "worst pain from 0 cm to 10 cm. The subject will be asked to draw a mark of it before and after each PEMF treatment session.

This is an activity level scaled from 1 (low activity) to 10 (high activity).

Consists of 10 questions on symptoms and activity ranging from 0 to 100 where 100 implies perfect knee function.

Consists of eight items, total score ranging from 0 to 100 where higher scores indicate a better outcome with fewer symptoms or disability.

The level of physical activities during the past 7 days will be evaluated with a validated Chinese version of the quantitative physical activity questionnaire.