Wrist osteoarthritis is a group of mechanical abnormalities resulting in joint destruction, which can occur in the wrist. These abnormalities include degeneration of cartilage and hypertrophic bone changes, which can lead to pain, swelling and loss of function. Osteoarthritis of the wrist is one of the most common conditions seen by hand surgeons.Osteoarthritis of the wrist can be idiopathic, but it is mostly seen as a post-traumatic condition. There are different types of post-traumatic osteoarthritis. Scapholunate advanced collapse (SLAC) is the most common form, followed by scaphoid non-union advanced collapse (SNAC). Other post-traumatic causes such as intra-articular fractures of the distal radius or ulna can also lead to wrist osteoarthritis, but are less common. Types
SLAC and SNAC are two patterns of wrist osteoarthritis, following predictable patterns depending on the type of underlying injury. SLAC is caused by scapholunate ligament rupture, and SNAC is caused by a scaphoid fracture which does not heal and because of that will develop in a non-union fracture. SLAC is more common than SNAC; 55% of the patients with wrist osteoarthritis has a SLAC wrist. SLAC
Scapholunate advanced collapse (SLAC) is a predictable pattern of wrist osteoarthritis that results from untreated long-standing scapholunate instability, which in turn is secondary to a rupture of the scapholunate ligament. The main type of such misalignment is dorsal intercalated segment instability (DISI) which is where the lunate angulates to the posterior side of the hand. SNAC
Scaphoid non-union fractures changes scaphoid bone shape, which leads to abnormal joint kinematics.
A target plasma concentration is entered as ng/ml into the pump, which calculates its infusion rate according to patient factors like age and weight. Induction levels of 40 ng/ml are commonly used, but it generally varies between 3–8 ng/ml. For certain surgical procedures that produce particularly strong stimuli a level of up to 15 ng/ml might be needed. The relatively short context-sensitive half-life of remifentanil allows the desired blood plasma level to be achieved quickly, and also for the same reason, recovery occurs quickly. This allows remifentanil to be used in unique circumstances such as cesarean section.Remifentanils short context-sensitive half-life makes it ideal for intense pain of short duration. As such, it has been used for analgesia in labor successfully; however, it is not as effective as epidural analgesia.In combination with propofol, remifentanil is used for anesthesia of patients undergoing electroconvulsive therapy. Metabolism
Remifentanil is considered a metabolic soft drug, one that is rapidly metabolized to an inactive form. Unlike other synthetic opioids which are hepatically metabolized, remifentanil has an ester linkage which undergoes rapid hydrolysis by non-specific tissue and plasma esterases. This means that accumulation does not occur with remifentanil and its context-sensitive half-life remains at 4 minutes after a 4-hour infusion. Remifentanil is metabolized to a compound (remifentanil acid) which has 1/4600th the potency of the parent compound.Due to its quick metabolism and short effects, remifentanil has opened up new possibilities in anesthesia. When remifentanil is used together with a hypnotic (i.e. one that produces sleep) it can be used in relative high doses.