Temperature and current flow effects of different electrode placement in shoulder capacitive-resistive electric transfer applications: a cadaveric study

Background Impingement syndrome is currently estimated to represent 60% of all shoulder pain disorders. Capacitive-Resistive electric transfer therapy is aimed to provoke temperature and current flow changes in superficial and deep tissues. This in vitro study has evaluated the variation of temperature and current flow in the shoulder tissues during two different areas of application of the movable capacitive-resistive electric transfer electrode. Methods A cross-sectional study designed, five fresh cryopreserved cadavers (10 shoulders) were included in this study. Four interventions (capacitive and resistive modes; low- and high-power) were performed for 5 min each by a diathermy “T-Plus” device in two shoulder regions: postero-superior and antero-lateral. Supraspinatus tendon, glenohumeral capsule and superficial temperatures were recorded at 1-min intervals and 5 min after treatment. Results A statistically significant difference was found only for the superficial area and time interaction, with high power-resistive application at the postero-superior shoulder area (P< 0.035). All the applications showed a 5 min after treatment temperature increase compared with the basal data, in all the application points. Superficial temperature in the high power-resistive application showed the greatest percent increase (42.93% ± 22.58), followed by the temperature in the tendon area with the same high power-resistive application (22.97% ± 14.70). The high power-resistive application showed the greatest percent of temperature increase in the applications, reaching 65.9% ± 22.96 at 5-min at the superficial level, and 32% ± 24.25 at 4-min at the level of the supraspinatus tendon. At the capsule level, high power-resistive was also the application that showed the greatest percent of increase, with 21.52% ± 16.16. The application with the lowest percent of temperature increase was the low power-capacitive, with a mean value of 4.86% at supraspinatus tendon level and 7.47% at capsular level. Conclusion The shoulder postero-superior or antero-lateral areas of application of capacitive-resistive electric transfer did not cause statistically significant differences in the temperature changes in either supraspinatus tendon or glenohumeral capsule tissues in cadaveric samples. The high power-resistive application in the postero-superior area significantly increased superficial temperature compared with the same application in the antero-lateral position area.

Are the Effects in Temperature and Current Flow Dependent on the Areas of Electrode Application of Capacitive-resistive Electric Transfer on the Shoulder? A Cadaveric Study

Background Impingement syndrome is currently estimated to represent 60% of all shoulder pain disorders. Capacitive-Resistive electric transfer therapy is aimed to provoke temperature and current flow changes in superficial and deep tissues. This in vitro study has evaluated the variation of temperature and current flow in the shoulder tissues during two different areas of application of the movable capacitive-resistive electric transfer electrode. Methods A cross-sectional study designed, five fresh cryopreserved cadavers (10 shoulders) were included in this study. Four interventions (capacitive and resistive modes; low- and high-power) were performed for 5 minutes each by a diathermy “T-Plus” device in two shoulder regions: postero-superior and antero-lateral. Supraspinatus tendon, glenohumeral capsule and superficial temperatures were recorded at 1-min intervals and 5 min after treatment. Results A statistically significant difference was found only for the superficial area and time interaction, with high power-resistive application at the postero-superior shoulder area (P < 0.035). All the applications showed a final temperature increase compared with the basal data, in all the application points. Superficial temperature in the high power-resistive application showed the greatest percent increase (42.93% ± 22.58), followed by the temperature in the tendon area with the same high power-resistive application (22.97% ± 14.70). The high power-resistive application showed the greatest percent of temperature increase in the applications, reaching 65.9% ± 22.96 at 5-min at the superficial level, and 32% ± 24.25 at 4-min at the level of the supraspinatus tendon. At the capsule level, high power-resistive was also the application that showed the greatest percent of increase, with 21.52% ± 16.16. The application with the lowest percent of temperature increase was the low power-capacitive, with a mean value of 4.86% at supraspinatus tendon level and 7.47% at capsular level. Conclusion The shoulder postero-superior or antero-lateral areas of application of capacitive-resistive electric transfer did not cause statistically significant differences in the temperature changes in either supraspinatus tendon or glenohumeral capsule tissues in cadaveric samples. The high power-resistive application in the postero-superior area significantly increased superficial temperature compared with the same application in the antero-lateral position area.

Direction of Capsular Strain Implies Surgical Repair Following Recurrent Anterior Shoulder Dislocation

Objectives: Capsular plication is often performed in addition to arthroscopic Bankart repair. However, little is known regarding the direction of capsular injury making the direction of plication fairly arbitrary. This study aimed to determine the optimal direction for capsular plication within four sub-regions of the inferior glenohumeral capsule following multiple dislocations. Methods: Seven fresh-frozen cadaveric shoulders (age range 48-66 yrs) were dissected free of all soft tissue except the glenohumeral capsule. A grid of strain markers was affixed to the anterior and posterior band (A/PB) of the inferior glenohumeral ligament (IGHL), and the axillary pouch. The position of the markers while the capsule was inflated with minimal pressure served as the reference state. The humerus and scapula were then mounted in a 6 degree-of-freedom robotic testing system. At 60 degrees of abduction and 60 degrees of external rotation of the glenohumeral joint, an anterior load was applied to reach an anterior translation of one half the maximum AP width of the glenoid plus 10 mm. This definition of dislocation resulted in non-recoverable strain and a reproducible Bankart lesion. Following 1, 2, 3, 4, 5 and 10 dislocations, the positions of the strain markers were again recorded with the capsule inflated. The difference in these positions compared to the reference state defined the non-recoverable strain. The strain map was split into four sub-regions, the anterior band of IGHL (AB), anterior axillary pouch (AA), posterior axillary pouch (PA), and the posterior band of IGHL (PB) (Fig. 1). The angle of deviation between each of the maximum principle strain vectors and the AB-IGHL or PB-IGHL for the anterior and posterior regions of the capsule were determined using ImageJ. Circular statistics were employed to calculate mean direction of each sub-region and a Watson-Williams test was performed to compare mean direction among each dislocation with significance set at p < 0.05. The mean direction of all strain vectors in each sub-region was categorized as parallel or perpendicular to the AB-IGHL or PB-IGHL serving as the clinical reference. Direction ranging from 0 to 45 or 135 to 180 degrees was categorized as parallel. Direction ranging between 45 and 135 degrees was categorized as perpendicular. Results: The direction of 81.8% of the AB sub-regions was categorized as parallel and 18.2% categorized as perpendicular to the AB-IGHL. Direction of 61.3% of the AA sub-region was categorized as parallel (Table 1) and 38.7% categorized as perpendicular to AB-IGHL. The direction of 33.3% of the PA sub-region was categorized as parallel and 66.7% categorized as perpendicular to the PB-IGHL. The direction of 21.4% of PB sub-region was categorized as parallel and 78.6% categorized as perpendicular to PB-IGHL. A Watson-Williams test demonstrated that the direction of 81.3% of the sub-regions were not significantly different (p > 0.05) among dislocations for each specimen (Table 1). Conclusion: The non-recoverable strain in most of the AB and AP sub-regions were categorized as parallel to the AB-IGHL while for the PA and PB sub-regions mostly perpendicular to the PB-IGHL. These findings imply that it may be more optimal to plicate the anteroinferior capsule parallel to the AB-IGHL while posteroinferior capsular plication, which is often not classically considered for plication in the setting of anterior instability, may also be necessary and best performed perpendicular to the PB-IGHL. [Figure: see text][Table: see text]

A Method for Predicting Collagen Fiber Realignment in Non-Planar Tissue Surfaces as Applied to Glenohumeral Capsule During Clinically Relevant Deformation

Previously developed experimental methods to characterize micro-structural tissue changes under planar mechanical loading may not be applicable for clinically relevant cases. Such limitation stems from the fact that soft tissues, represented by two-dimensional surfaces, generally do not undergo planar deformations in vivo. To address the problem, a method was developed to directly predict changes in the collagen fiber distribution of nonplanar tissue surfaces following 3D deformation. Assuming that the collagen fiber distribution was known in the un-deformed configuration via experimental methods, changes in the fiber distribution were predicted using 3D deformation. As this method was solely based on kinematics and did not require solving the stress balance equations, the computational efforts were much reduced. In other words, with the assumption of affine deformation, the deformed collagen fiber distribution was calculated using only the deformation gradient tensor (obtained via an in-plane convective curvilinear coordinate system) and the associated un-deformed collagen fiber distribution. The new method was then applied to the glenohumeral capsule during simulated clinical exams. To quantify deformation, positional markers were attached to the capsule and their 3D coordinates were recorded in the reference position and three clinically relevant joint positions. Our results showed that at 60deg of external rotation, the glenoid side of the posterior axillary pouch had significant changes in fiber distribution in comparison to the other sub-regions. The larger degree of collagen fiber alignment on the glenoid side suggests that this region is more prone to injury. It also compares well with previous experimental and clinical studies indicating maximum principle strains to be greater on the glenoid compared to the humeral side. An advantage of the new method is that it can also be easily applied to map experimentally measured collagen fiber distribution (obtained via methods that require flattening of tissue) to their in vivo nonplanar configuration. Thus, the new method could be applied to many other nonplanar fibrous tissues such as the ocular shell, heart valves, and blood vessels.