Anterior tibial stress fractures elicit focal tenderness on the anterior tibial crest, while posterior medial stress fractures can be tender at the posterior tibial border. Causes
Bones are constantly attempting to remodel and repair themselves, especially during a sport where extraordinary stress is applied to the bone. Over time, if enough stress is placed on the bone that it exhausts the capacity of the bone to remodel, a weakened site—a stress fracture—may appear on the bone. The fracture does not appear suddenly. It occurs from repeated traumas, none of which is sufficient to cause a sudden break, but which, when added together, overwhelm the osteoblasts that remodel the bone. Potential causes include overload caused by muscle contraction, amenorrhea, an altered stress distribution in the bone accompanying muscle fatigue, a change in ground reaction force (concrete to grass) or the performance of a rhythmically repetitive stress that leads up to a vibratory summation point.Stress fractures commonly occur in sedentary people who suddenly undertake a burst of exercise (whose bones are not used to the task) They may also occur in athletes completing high volume, high impact training, such as running or jumping sports. Stress fractures are also commonly reported in soldiers who march long distances. Muscle fatigue can also play a role in the occurrence of stress fractures. In a runner, each stride normally exerts large forces  at various points in the legs. Each shock—a rapid acceleration and energy transfer—must be absorbed. Muscles and bones serve as shock absorbers.
Propantheline bromide (INN) is an antimuscarinic agent used for the treatment of excessive sweating (hyperhidrosis), cramps or spasms of the stomach, intestines (gut) or bladder, and involuntary urination (enuresis). It can also be used to control the symptoms of irritable bowel syndrome and similar conditions. This agent can also be used for patients who experience intense GI symptoms while tapering off of TCAs. Indications
By relaxing the gut muscle, propantheline can relieve pain in conditions caused by spasm of the muscle in the gut. Relaxing the smooth muscle in the bladder prevents the involuntary spasms that can allow leakage of urine from the bladder in the condition known as enuresis (involuntary urination in adults). Propantheline can also be used to treat excessive sweating because acetylcholine block also reduces secretions such as sweat and tears. Adverse effects
Side effects include tachycardia, constipation, hypersensitivity to light, dry mouth, and urinary retention. This can also be prescribed by dentists for certain patients who salivate excessively. By giving this medication it becomes easier to do "dry" dentistry. Mechanism of action
Propantheline is one of a group of antispasmodic medications which work by blocking the action of the chemical messenger acetylcholine, which is produced by nerve cells, to muscarinic receptors present in various smooth muscular tissues, in places such as the gut, bladder and eye. Normally, the binding of acetylcholine induces involuntary smooth muscular contractions. == References ==