Chondroplasty is an option in cases of mild to moderate cartilage wear. During arthroscopy the loose cartilage flaps and debris within the knee are removed using an arthroscopic shaver. Great care is taken to avoid damaging normal cartilage.
Short Term Investments as Current Assets on the Balance Sheet. These are investments that a company plans to sell shortly or can be sold to provide cash. These short-term investments aren't as readily available as money in a checking account but they provide added cushion if some immediate need were to arise.
If you are talking about stock that the company in question has issued, then it is not an asset at all, but rather a component of owner's equity. However, shares of stock in other companies that have been purchased are in fact current assets. The idea is that if a firms needs to make payments to suppliers, lenders, etc. they can sell stock and turn it to cash immediately. This is typically not the case with fixed assets. Investments in stocks are highly liquid.