Overview of the first carpometacarpal joint Disorders

Abstract

The 1st CMC It is one of the most important joints in the human body. It provides the thumb with the ability to cross over the palm of the hand, thus enabling motions of pinch and grip essential in performing routine daily activities. The unique prehensile ability of the human hand is largely due to the biomechanical function of the shallow, saddle-shaped, multi-axial CMC joint at the base of the thumb. A pinch force of 1 kg at the thumb tip can translate to a 13.42 kg force at the 1st CMC joint. Therefore the 1st CMC joint receives a significant amount of mechanical stress even during daily use of the hand. The surfaces of this articulation are kept in position by the surrounding ligaments. Five main ligamentous structures were identified: Anterior oblique ligament (AOL), Dorsoradial ligament (DRL), Ulnar collateral ligament (UCL), intermetacarpal ligament (IML) and Posterior oblique ligament (POL). The 1st CMC joint could be affected by many disorders either congenital, traumatic, neoplastic, rheumatic or degenerative disorders. The most common disease is primary osteoarthritis. Thumb CMC OA is a common disease, affecting up to 11% and 33% of men and women in their 50s and 60s.There are many classifications systems for the 1st CMC joint OA, but the most widely used system is Eaton and Glickel's radiological staging system. The staging is important in treatment decision making. Summary 161 1st CMC joint dislocation is a rare hand injury. The lesion is usually due to an axial force transmitted through partially flexed thumb, forcing the joint to deflect toward dorsal as the volar part of the ligament being thicker and stronger. The majority of patients with rheumatoid arthritis will develop thumb CMC joint involvement. The 1st CMC joint could be subluxated in 16 per cent of SLE patients. Severe erosive changes were found in the CMC joint in PSS patient. Gout in the thumb CMC joint is very painful, and the attacks often last longer than in other joints. The clinical assessment of the 1st CMC joint should include history asking about the risk factors and about any activity that involves pinch or grasp can trigger discomfort and about history of trauma. Inspecting any deformity or swelling and palpation for tenderness and crepitus. Special tests for CMC OA as grind test, abduction stress test and extension stress test. Special tests for ligamentous stability as test for AOL and test for UCL. Radiological investigations are very important in diagnosis of 1st CMC joint disorders. Routine radiographic views dedicated evalution of the thumb CMC joint. Special CMC joint views are helpful in confirming the diagnosis as stress view and Robert view. US could be used to identify and evaluate both the integrity and thickness of the AOL and other first CMC joint ligaments and to evaluate for joint effusions and synovitis.CT could be indicated for those patients who are eligible for thumb base surgery and who showed no radiographical OA in the STT joint. MRI has the ability to diagnose the degree of ligamentous injury and differentiate avulsions from partial tears. Summary 162 The management of CMC joint disorders could be conservative or surgical. A-Conservative treatment: Conservative treatment is the first line to treat the 1st CMC arthritis. It includes activity modification tips: Patients are trained to be aware of how various activities affect their joints and modify how they perform activities to reduce joint stress. Analgesics and NSAIDs: The risk of adverse events associated with NSAID use decreases significantly when topical gels are used instead of oral preparations. Splinting (Orthosis): There are three types of splints: Immobilization splints, Dynamic Stability splints and push splints.Physical therapy: A significant improvement in grip strength and improved global hand function scores in patients given joint protection education and hand exercises is reported. A combined program of mobilization with movement (MWM) and kinesiology tape has been shown to reduce pain, increase range of motion, and increase tip pinch strength.The median nerve & radial nerve mobilization therapy decreases pain in the 1st CMC joint and increases grip strength in patients with 1st CMC OA. Grip strength usually improves with thermotherapy or cryotherapy. Heat can be administered by a variety of techniques, including ultrasounds, shortwave or microwave diathermy, local application of hot packs or immersion in warm water and wax baths.Electrical stimulation provides a wide variety of benefits, including increasing muscle strength and joint ROM, decreasing edema and pain.