Quantification of wrist joint laxity.

PURPOSE: Laxity may be a trigger for chronic unidentified wrist pain. To determine whether this is the case, first an objective method to quantify wrist laxity needs to be defined. This study investigates different quantification methods (reference tests) from the literature and compares these with the judgment of 2 independent experienced clinicians (index test, or gold standard). METHODS: Fifty healthy women (ages 19-43 y) without wrist complaints were included. For each subject, both clinicians were asked to give a laxity score for both wrists on a Likert scale of 1 to 5 (1 = very stiff, 5 = very lax). Subjects also had 3 reference tests: the Garcia-Elias method (passive range of motion), the Beighton method (general hypermobility), and the active range of motion method (specially designed measurement device). RESULTS: There was no significant difference between the average laxity scores of clinicians 1 and 2. The intraclass correlation between clinician 1 and clinician 2 was significant but low. Correlation between the clinicians with the Garcia-Elias test as well as the Beighton method was significant but low (0.431 and 0.378). The correlation between reference tests was higher but still moderate. CONCLUSIONS: This study showed that the index test used (clinical assessment) did not produce a satisfactory quantification of wrist laxity. Also, the reference tests are not suitable for quantification of laxity and seem to measure mobility rather than laxity. To quantify wrist laxity in a reliable and clinically relevant manner, it seems that consensus needs to be established between clinicians as to what elements of (abnormal) wrist motion define the wrist as "lax." In addition the development and testing of a measurement device that quantifies wrist translation might be needed for determining an objective score for wrist laxity.

Complete 3D kinematics of upper extremity functional tasks.

Upper extremity (UX) movement analysis by means of 3D kinematics has the potential to become an important clinical evaluation method. However, no standardized protocol for clinical application has yet been developed, that includes the whole upper limb. Standardization problems include the lack of a single representative function, the wide range of motion of joints and the complexity of the anatomical structures. A useful protocol would focus on the functional status of the arm and particularly the orientation of the hand. The aim of this work was to develop a standardized measurement method for unconstrained movement analysis of the UX that includes hand orientation, for a set of functional tasks for the UX and obtain normative values. Ten healthy subjects performed four representative activities of daily living (ADL). In addition, six standard active range of motion (ROM) tasks were executed. Joint angles of the wrist, elbow, shoulder and scapula were analyzed throughout each ADL task and minimum/maximum angles were determined from the ROM tasks. Characteristic trajectories were found for the ADL tasks, standard deviations were generally small and ROM results were consistent with the literature. The results of this study could form the normative basis for the development of a 'UX analysis report' equivalent to the 'gait analysis report' and would allow for future comparisons with pediatric and/or pathologic movement patterns.

Permanent wall stretching in porcine coronary and internal mammary arteries.

BACKGROUND: Anastomotic connectors may induce substantial arterial wall deformation and, hence, wall injury. We studied arterial wall damage and repair after sustained large longitudinal elongation in the porcine coronary and internal mammary arteries in vivo. METHODS: A stretch device that elongates a part of the artery by 80% was implanted in 8 pigs. Elongated coronary arteries (n = 14) and internal mammary arteries (n = 15) were examined histologically at either 2 days (4 pigs) or 5 weeks of follow-up (4 pigs). RESULTS: No mural thrombus was observed at the elongated site. In the coronary artery at 2 days, few and only minor histologic changes were found. At 5 weeks, in two of seven coronary segments, a thin rim of intimal hyperplasia was found, in one case with a maximum thickness of 76 micro m. The internal mammary artery hardly showed any changes. CONCLUSIONS: Permanent longitudinal elongation by 80% caused little structural changes in the porcine coronary and internal mammary artery wall. Anastomotic connectors that impose relatively large deformations can be safely evaluated in the pig.

Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress.

OBJECTIVE: This study compares the area of blood-exposed non-intimal surface in device-constructed anastomoses with the conventionally sutured anastomosis and examines the technical feasibility of 0 blood-exposed non-intimal surface anastomosis configurations. METHODS: In the device-constructed anastomosis, blood-exposed non-intimal surface was estimated in all anastomosis configurations identified in truly new (ie, nonduplicate and nonrelated) patent applications and in anastomotic devices recently introduced by several institutions. In the sutured anastomosis, blood-exposed non-intimal surface area was estimated by analysis of previously investigated anastomoses. In 0 blood-exposed non-intimal surface anastomosis configurations, finite element modeling was used to calculate coronary wall stress. RESULTS: By the end of 2001, 57 truly new applications for the distal coronary anastomosis had been published, categorized in 11 types of anastomosis configurations. The tissue blood-exposed non-intimal surface area (ie, non-intimal tissue surface area) ranged from 0 to 6 mm(2). Approximate total blood-exposed non-intimal surface areas (ie, sum of tissue blood-exposed non-intimal surface and foreign body surface area) in recent devices are 80 mm(2) (GraftConnector, Jomed, Helsingborg, Sweden); 33 mm(2) (Magnetic Vascular Positioner rings, Ventrica, Inc, Fremont, Calif); 4.3 mm(2) (distal connector of St Jude Medical, Inc, St Paul, Minn); and 0.3 mm(2) (Crinoline frame, University Medical Center Utrecht/Delft University of Technology, The Netherlands). The sutured anastomoses, in contrast, contained approximately 1.3 mm(2) blood-exposed non-intimal surface area. The mean peak porcine coronary wall stress in 0 blood-exposed non-intimal surface anastomosis configurations with greater than 90 degrees arteriotomy edge eversion ranges from 0.4 to 0.8 N/mm(2) compared with the mean porcine coronary tear stress of 0.8 N/mm(2). CONCLUSIONS: In recently introduced devices for clinical use, the total blood-exposed non-intimal surface area ranges from 4.3 to 80 mm(2) compared with 1.3 mm(2) in sutured anastomoses. The blood-exposed non-intimal surface area depends on anastomotic orifice size, wall thickness, and bonding components' location and size. Deforming the coronary wall to most of the 0 blood-exposed non-intimal surface anastomosis configurations leads to dangerously high stress concentrations in the coronary arteriotomy corners.

Mechanical properties of porcine and human arteries: implications for coronary anastomotic connectors.

BACKGROUND: To determine whether the pig is an appropriate experimental animal for studies on distal anastomotic connectors in coronary artery bypass surgery, the mechanical properties of young porcine and old human coronary and internal mammary arteries were compared within and beyond the physiologic range of strains. METHODS: Coronary arteries from 6 humans and 8 pigs were studied as well as internal mammary arteries of 3 humans and 6 pigs (human, aged 61 to 85 years; pig, 78.7 +/- 5.8 kg [mean +/- SD]). Pressure-diameter, pressure-axial force, circumferential and axial stress-strain relations, and dimensions were measured. RESULTS: The dimensions of the porcine and human coronary and internal mammary artery were generally similar but wall thickness was smaller in the porcine internal mammary artery (0.35 +/- 0.07 mm versus 0.71 +/- 0.06 mm, respectively, p = 0.002). The porcine internal mammary artery wall was less elastic than the coronary artery wall, whereas in humans both arteries displayed similar elasticity. Overall the porcine arteries were far more elastic in both circumferential and axial direction compared with the human arteries. Consequently the porcine arteries could be safely stretched by 60% to 70% compared with about 20% for the human arteries before reaching their maximum circumferential strain. CONCLUSIONS: The three times greater elasticity of porcine compared with human coronary and internal mammary artery walls may result in underestimation of wall stress and the risk of wall injury when coronary connectors that involve overstretching of the wall are evaluated in the pig.