Patient presents with right knee pain and swelling following a twisting injury sustained while playing basketball yesterday.  The patient reports hearing a popping sensation at the time of injury.  Examination reveals tenderness and mild effusion over the medial aspect of the right knee.  Range of motion is limited due to pain, particularly with flexion and extension.  Medial joint line tenderness is noted.  Lachman test and anterior drawer test are negative, suggesting intact anterior cruciate ligament.  McMurray test is negative, ruling out meniscal tear.  Valgus stress test at 30 degrees of flexion elicits pain and laxity compared to the left knee, indicative of a medial collateral ligament sprain.  Diagnosis of right knee sprain, likely MCL sprain, is made.  Radiographs of the right knee are negative for fracture.  Treatment plan includes RICE therapy (rest, ice, compression, elevation), NSAIDs for pain and inflammation, and a referral to physical therapy for rehabilitation exercises to restore strength and range of motion.  Patient education provided on activity modification and crutch use for ambulation as needed.  Follow-up scheduled in one week to assess progress and adjust treatment plan as necessary.  Differential diagnoses considered included meniscus tear, ACL tear, and fracture, but clinical findings support the diagnosis of right knee sprain.  ICD-10 code S13.411A will be used for right knee sprain, unspecified site, initial encounter.  Keywords:  knee pain, knee injury, knee sprain, MCL sprain, LCL sprain, medial collateral ligament, lateral collateral ligament, knee swelling, valgus stress test, Lachman test, anterior drawer test, McMurray test, RICE therapy, physical therapy, knee rehabilitation, ICD-10 S13.411A, CPT codes, medical billing, healthcare, clinical documentation, EHR documentation.