Hop tests are used to determine return to sports after ACL reconstruction. They mostly measure distance and symmetry but do not assess kinematics and kinetics. Recently, biomechanical evaluations have been incorporated into these functional jump tests for the better assessment of return to sport. We assessed the sagittal plane range of motion (ROM) of the knee, the deviation axis of rotation (DAOR), and the vertical ground reaction force (vGRF) normalized to body weight in nine healthy participants during the single leg (SLH) and crossover hop tests (COHT).

Participants' leg lengths were measured. Jumping distances were marked in the test area as being 4/5 of the leg length. Four sensors were placed on the thighs, the legs and the feet. These body parts were handled as a single rigid body. Eight 480 Hz cameras were used to capture the movements of these rigid bodies. vGRF at landing were measured using a force plate (Bertec, Inc, USA). The ROM of the knee joint and the DAOR were obtained from kinematic data.

Participants' joint kinematics metrics were similar in within-subjects statistical tests for SLH and COHT. We therefore asked whether the repeated vGRF normalized to body weight will be similar in both legs during these jumps. Joint kinematics metrics however were different in between subjects indicating the existence of a personalized jumping strategy. These hop tests can be recorded at the beginning of the training season for each individual, which can establish a comparative evaluation database for prospective lower extremity injury recovery and return to sport after ACL injury.

Adductor strain is a common injury among football players. The adductor muscle group contains the three adductor muscles. (adductor longus, magnus and brevis) Adductor longus muscle is a triangular-shaped long muscle. This muscle originates from the superior ramus of the pubic bone and inserted into the middle part of the linea aspera. Adductor longus muscle is the most commonly injured muscle of adductors. Sudden acceleration, jumping, stretching, and kicking the ball are common causes of an adductor injury. Adductor muscle strains can result in missed playing time for football players.

We present a 26-year-old man soccer player with pain in the left groin and proximal thigh. The symptoms had started during training and after kicking the ball with left foot (dominant side), he felt an acute pain in the groin region and proximal thigh. Despite the injury, he managed to finish the training. The team physician examined the patient immediately after training. The range of motion of both hip joints was in normal ranges and mild pain with adduction. There was a palpable mass at the inner proximal thigh during contraction of adductor muscles. There was no history of groin pain or adductor problems before this injury. Conventional radiographs showed no osseous abnormalities. 36 hours after the injury, MRI revealed acute grade IIB strain in the left adductor longus muscle, including both superior and inferior parts of the muscle. A hematoma was observed in the superior part of the left adductor muscle, with a craniocaudal length of 42 millimeters. There was an adductor muscle strain with hyperintensity extending for a craniocaudal length of approximately 12 centimeters involving more than 50% crosses sectional diameter of the muscle belly. Conservative treatment started immediately, consisting of cold therapy and soft tissue massage. Compression of the injured tissue using a 15-cm elastic bandage roll is done to limit bleeding and provide support. Iced water machine (Game Ready) was used. The team physician examined the player every day and prescribed physiotherapy protocol daily. Additionally, short interval follow-up MRI is used to evaluate the injury. (After 7 and 14 days of the injury) No injection was performed. The player is able to return to play immediately, despite MRI's strain images. The player started straight running 5 days later and joined to team training 8 days later and played 90 minutes-league-match 12 days after injury without any pain. No injection was performed. The player is able to return to play immediately, despite MRI's strain images. The player started straight running 5 days later and joined to team training 8 days later and played 90 minutes-league-match 12 days after injury without any pain.

MRI is a useful technique in diagnosing trauma in football players presenting with groin pain. In this case, to estimate time-to-return-to-play, MRI alone is not strong evidence. MRI is a good option for follow up, but anamnesis and clinical examination is not inferior to diagnostic imaging.