Thumb problems are common in some health professionals such as physical therapists. The purpose of this case-control study is to investigate the influence of clinical experience and different mobilization techniques on the kinematics of the thumb.Twenty-three participants without exposure to manual techniques (the Novice Group) and fifteen physical therapists with at least 3 years of orthopedic experience (the Experienced Group) participated. The kinematics of the thumb while performing 3 different simulated posteroanterior (PA) glide mobilization techniques on a load cell was monitored. These 3 techniques were: 1) unsupported, 2) with digital support and 3) with thumb interphalangeal joint supported by the index finger. The amount of forces exerted were 25% to 100% of maximum effort at 25% increments. The main effects of experience and technique on thumb kinematics were assessed.Both experience and technique had main effects on the flexion/extension angles of the thumb joints. Experienced participants assumed a more flexed position at the carpometacarpal (CMC) joint, and the novice participants performed with angles closer to the neutral position (F = 7.593, p = 0.010). Participants' metacarpophalangeal (MCP) joints were in a more flexed position while performing PA glide with thumb interphalangeal (IP) joint supported by the index as compared to the other two techniques (p < .001).Negative correlations were generally obtained between the sagittal plane angles of adjacent thumb joints during mobilization/manipulation. Therapists are recommended to treat patient with more stable PA glide mobilization techniques, such as PA glide with thumb interphalangeal joint supported by the index finger, to prevent potential mobilization-related thumb disorders.
Joint mobilization is a complicated task to learn and to teach and is characterized by great intersubject variability. This study's purpose was to investigate whether quantitatively augmented feedback could enhance the learning of joint mobilization and, more specifically, to compare the effects of training with concurrent or terminal feedback by using a joint translation simulator (JTS).Thirty-six undergraduate physical therapist students were randomly assigned to control (no feedback), concurrent feedback, and terminal feedback groups.The JTS was designed to simulate tissue resistance based on load-displacement relationships of glenohumeral joint specimens. Subjects applied specific mobilization grades of force on the JTS while quantitative feedback was given to the feedback groups either during a trial (ie, concurrent feedback) or after a trial (ie, terminal feedback). The skill acquisition phase lasted a total of 40 minutes, and a total of 75 repetitions were performed for each grade of each joint model. Pretest and no-feedback retention tests were conducted.During acquisition and retention, both feedback groups performed more accurately than did the control group. No obviously superior performance was shown by the terminal feedback group compared with concurrent feedback group during retention testing.Subjects who trained with augmented feedback had less variability, and thus more consistency, than the control group subjects who received no feedback. Augmented feedback provides the student with a reference force and the status of his or her performance. The effectiveness of the JTS feedback compared with no feedback was clearly demonstrated. Skill acquisition in mobilization can be enhanced by either concurrent or terminal feedback.
Tissue ingrowth into the implanted artificial ligaments is to be expected after reconstructive procedures and several groups have reported soft tissue ingrowth of the implanted LARS (Ligament Augmentation and Reconstruction System, Dijon, France) artificial ligament. Up to now the influence of the tissue ingrowth on the mechanical properties of the artificial ligament is uncertain. The purpose of this research was to study the mechanical property after tissue ingrowth on LARS artificial ligament. Five LARS ligaments were implanted subcutaneously in the abdomen of five pigs. After six months of implantation, four successful implants were explanted and tested. The results showed that fibroblasts and collagen fibers had grown into the unknotted middle part of the LARS. However, 12.2 ± 2.2% of fibres were surrounded by foreign body giant cells. Tensile tests showed that the explanted LARS possessed similar elastic characteristics as native ligaments. The tensile strength of the explanted LARS decreased by 23.53 ± 18.04% (p < 0.001) and the elongation of the middle part of the explanted LARS increased by 69.84 ± 38.38% (p < 0.002) in comparison with unimplanted control ligaments. Since there were not apparent surface cracking on the LARS fibers, it was inferred that activities of foreign-body giant cells might have weakened the strength and adversely affected the mechanical properties of the fibers of the LARS.
Negative intra-articular pressure (IAP) is a passive stabilizer during joint movement. In contrast to that of large joints, the IAP within the metacarpophalangeal (MCP) joint has not been well studied. The objective of this study was to evaluate the biomechanics of the MCP joint in terms of load–displacement relation and IAP during the application of long-axis distraction to fresh cadaver specimens. Nine fresh MCP joints specimens from four hands were used. A long-axis distraction load of 16 kg was applied to the cadaver MCP joint before and after venting of the joint capsule. In addition to load–displacement data, a pressure transducer was used to measure the IAP of the MCP joint during loading. After venting the capsule, significant increases were found in displacement at a load of 16 kg (4.60 ± 0.80 mm in an intact MCP joint and 5.22 ± 0.97 mm in a vented MCP joint) and in displacement at the cross-point (3.44 ± 0.82 and 4.01 ± 0.81 mm). No significant difference was found in the displacement difference between a load of 16 kg and the cross-point (1.16 ± 0.26 and 1.20 ± 0.33 mm) as well as stiffness at the terminal range under both the intact and venting conditions (12.59 ± 2.53 and 12.28 ± 2.70 kg/mm). The IAP decreased dramatically during the 5% to 10% total distraction of load. It was found that negative IAP of the MCP joint contributes significantly to initial stability.
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