Similar results are found www.selleckchem.com/products/MG132.html in the literature. 4 , 5 , 7 , 10 The superior migration of the humeral component is associated with a worse functional outcome of the pacientes. 11 The standard measurement of this migration can be made through the height of the subacromial space 3 or by breakdown of the so called “Gothic arch”. 12 Our study found no correlation between the first measurement and functional outcomes. However, the superior migration evaluated by breaking of the Gothic arch positively correlated with a worse clinical outcome. Although contradictory, the presence of correlation between superior migration of the humeral head and the absence of correlation between the height of the subacromial space can be explained by several factors.
The evaluation of the subacromial space is influenced by the patient positioning, the slope of the scapula, the arm rotation, retroversion of the prosthesis and the slope of the acromion or the presence of subacromial osteophytes. However, the top of the head migration, evaluated by breaking of the Gothic arch 12 has less dependence on the radiographic technique, and possibly has greater sensitivity to assess the superior migration of the prosthesis head. The rotator cuff tear is a common cause of superior migration of the humerus and is directly related to worse outcomes in shoulder arthroplasty. 11 , 13 It is also a risk factor for loosening of the glenoid. 6 , 14 Other factors that can decrease the space are incorrect positioning of the humeral shaft, high-cut osteotomy of the humerous head, the eccentricity of the humeral head and large humeral head or long neck use.
The greater tuberosity of the humerus is positioned generally between 2 to 5mm below the top of the head. When the humeral component is positioned below the edge of the greater tuberosity, the joint rotation center descends relatively to the humerus, resulting in subacromial impingement due to the relatively higher position of the greater tuberosity. Acho que ficaria melhor: On the other hand, a high positioned head causes increased tension in the rotator cuff and also increased chances of polyethylene wear or erosion of the glenoid cavity. 9 The supraspinatus tendon lying above the prosthesis head can cause later tendinopathy. 9 , 15 In this situation increased tension in the capsule bottom also occurs, according to Nyffeler et al.
16 There was no statistically significant correlations of this parameter with functional assessments. Singh et Brefeldin_A al. 10 found worse function in partial arthroplasty, but found no difference regarding to pain and state that both types of substitution (partial and total) improved the quality of life of patients with OA. In our study it was not possible to correlate the results for each type of arthroplasty due to the small number of patients. In primary OA, there is usually eccentric posterior erosion of the glenoid cavity, which may cause posterior subluxation of the humeral head.