Traditionally, conservative care meant non-operative care. You injured your knee or shoulder and the doctor said, "Let's try conservative care first and see if you get better." However, these days, conservative care often means that the insurance company has only authorized physical therapy or medications, with the aim of delaying a full work-up or surgical repair as long as possible. But conservative care may not be in your best interest. How do you know if this is the case?
Let's take my favorite subject, a knee injury. The data show that if a patient twists their knee, hears a pop and the knee swells, then there is a 90 percent chance that a significant injury to the meniscus, articular cartilage or ligaments has occurred. Current understanding of these tissues is that they are crucial to knee function, rarely heal on their own and are best treated with surgical repair as soon as is practical.
In the case of the meniscus cartilage, a tear that results in the patient hearing a pop and the knee swelling means a significant portion of the tissue has been torn. This won't heal on its own. Non-operative care such as physical therapy means that the torn tissues are exposed to repetitive motion, which, in this instance, further damages the tissue beyond the ability of the surgeon to repair it. Unrepaired meniscus tears lead to arthritis. Not very conservative.
In the case of the ligaments such as the ACL, the longer the knee is left unstable, the more the secondary restraints, the ligaments on the side of the knee, become stretched and the higher the chance of a secondary injury to the supporting structures such as the meniscus. This leads to a worse result when surgery is eventually performed, even more so if the patient is young.
The same is true for the articular cartilage, the bearing surface of the joint. Acute damage that leads to knee swelling never heals. Articular cartilage has no nerve supply (it is aneural) and so the damage may not initially be painful, but if left unrepaired, the lesions expand into early arthritis and persistent pain.
In this 21st century, the ability to make extremely accurate diagnosis of joint injuries lies in the combination of careful history, i.e. talking to the patient about exactly how the damage occurred, an experienced examiner, accurate X-rays and high-field, high-quality MRI. It is pennywise and pound foolish to not obtain each of these after significant joint injuries since it is far cheaper and much more efficient to fix injuries sooner rather than later.
I predict that the cost of an MRI will be driven down so low that in the near future most acute joint injuries will be scanned without hesitation and hopefully the knowledge that early repair is far better for the patient than false conservative care will become widespread. In the meantime, after a significant injury, be sure to get thee to an expert.