Inflammation of the periostium or sheath surrounding the tibia bone in the lower leg.  Shin splints can be caused by running on hard surfaces, bad shoes, cycling or running down hills.  The muscles start to pull away from the periosteum or sheath surrounding the bone.  It can lead to cramps in the front of the leg – especially while running.  Symptoms can be pain in the front of the leg along the shinds, may have pain alternating with numbness.  A branch of the common peroneal nerve runs into the anterior compartment of the leg which can be impinged from the surrounding inflammation, causing intermittent numbness.