HISTORY: A 15 year old H.S. football quarterback sustained a right thumb injury while throwing a pass. His hand hit a defender’s chest during follow through, jamming his thumb. He noted swelling and bruising over thenar eminence and his 2^nd MCP joint. This resulted in limited ROM of the right thumb especially of abduction and opposition. PHYSICAL EXAMINATION: Examination of the right hand showed edema along the 1^st MCP joint, thenar eminence with ecchymosis in 1^st webspace extending into 2^nd MCP joint. Skin was intact. Thumb was well vascularized. No tenderness over 2^nd metacarpal or 2^nd MCP joint. Thumb opposition and 1^st MCP flexion and extension less than 20° were limited by edema and pain, IP ROM was within functional limits. Tenderness over ulnar aspect of 1^st MCP joint . Pain and tenderness present during MCP extension with mild laxity with UCL stressing. Laxity at the CMC joint with some dorsal subluxation, reducible. Tenderness proximal to trapezium. Contralateral side thumb revealed also some laxity at the CMC. DIFFERENTIAL DIAGNOSIS: 1. Fracture of the right 1^st Metacarpal bone 2. Fracture of the right thumb proximal phalanx 3. Fracture of the wrist bones 4. Right 1^st MCP joint UCL sprain TEST AND RESULTS: X-rays of the right hand 3V: No bony or soft tissue abnormalities. MRI right hand ordered to rule out occult fracture(s), ligament tears : 1. Nondisplaced fracture of the trapezium. Diffuse bone marrow contusion in the 1^st metacarpal with small avulsion fragment of the radial metacarpal at RCL attachment 2. Bone contusion of the distal dorsal capitate 3. Moderate grade sprain of UCL and RCL at the thumb MCP joint with partial tearing of proximal RCL at the avulsion fragment. 4. Diffuse low grade muscle strain with superimposed partial musculotendinous tear of flexor pollicis brevis muscle. TREATMENT AND OUTCOMES: 1. Wrist and thumb immobilization in Custom thumb spica splint to enable graduated ROM as tolerated and Occupational Therapy 2. Restriction from all contact sports for 6 weeks 3. Consultation with Hand Orthopedist to evaluate for surgical necessity determined patient to be appropriate for conservative treatment. Patient seen in Sports Medicine Clinic 39 days after initial injury. Returned to sports after 6 weeks of immobilization with thumb/wrist taped . Patient denied pain with activity.