Tomoki Izumi

Lengthening of the Pectoralis Minor Muscle During Passive Shoulder Motions and Stretching Techniques: A Cadaveric Biomechanical Study

Background and Purpose: Lengthening of the pectoralis minor muscle (PMi) during passive shoulder motions and the effect of stretching techniques for this muscle are unclear. The purposes of this study were: (1) to investigate the amount and pattern of the lengthening between passive shoulder motions and (2) to determine which stretching technique effected the greatest change in PMi length. Methods: Nine fresh cadaveric transthoracic specimens were used. Lengthening in the lateral and medial fiber group of the PMi was directly measured during 3 passive shoulder motions (flexion, scaption, and external rotation at 90° of abduction) and 3 stretching techniques (scapular retraction at 0° and 30° of flexion and horizontal abduction) for this muscle. The measurement was conducted by using a precise displacement sensor. Results: Although the length of the PMi linearly increased during all shoulder motions, lengthening during flexion and scaption was steeper and significantly larger than that during external rotation at 90 degrees of abduction. For the stretching techniques, scapular retraction at 30 degrees of flexion and horizontal abduction stretched the PMi more than scapular retraction at 0 degrees of flexion. In comparison with lengthening at 150 degrees of flexion, scapular retraction at 30 degrees of flexion significantly stretched the medial fiber group of the muscle. Discussion and Conclusion: The extensive lengthening of the PMi is necessary during shoulder motions, especially flexion and scaption. Scapular retraction at 30 degrees of flexion makes the greatest change in PMi length. This study suggests the importance of the PMi in shoulder motion and provides anatomical and biomechanical evidence that might guide appropriate selection of stretching techniques.

Effect of distal radius volar plate position on contact pressure between the flexor pollicis longus tendon and the distal plate edge.

PURPOSE Some clinical studies have suggested that distal radius plates placed distal to the watershed line have the potential to impinge on the traversing flexor tendons. However, the validity of this theory remains unclear. The purpose of this study was to evaluate the quantitative effect of volar plate position on flexor pollicis longus (FPL) tendon friction by measuring the contact pressure between the FPL tendon and the distal edge of the locking plate. METHODS We used 7 fresh cadaveric upper extremities without wrist osteoarthritis or any deformity. External loads of 1.5 and 3.0 kgf were applied to the FPL tendon to simulate the pinch function of the thumb. A distal radius volar plate was applied to these cadaveric specimens in various positions relative to the watershed line. We measured contact pressure between the distal plate edge and the FPL tendon using a thin flexible pressure sensor and compared it among various positions of the volar plate for wrist extension angles of 0°, 30°, and 60° and ulnar deviation angles of 0° and 20°. RESULTS Under the 30° or 60° wrist extension condition, contact pressure significantly increased when the distal plate edge was placed distal to the watershed line, compared with when it was placed proximal to or at the watershed line. CONCLUSIONS Our quantitative results support the theory that plates placed distal to the watershed line have the potential to impinge on the traversing FPL tendon, even when a radius fracture heals anatomically. CLINICAL RELEVANCE This study clarifies a mechanism of FPL tendon irritation after volar plate fixation for distal radius fractures.

Stretching Positions for the Posterior Capsule of the Glenohumeral Joint: Strain Measurement Using Cadaver Specimens

Background Various stretches have been introduced for the posterior shoulder; however, little quantitative analysis to measure stretching of the posterior capsule has been performed. Hypothesis The current shoulder stretching program is not sufficient to stretch the entire posterior capsule. Study Design Controlled laboratory study. Methods Using 8 fresh-frozen cadaver shoulders (average age, 82.4 years), 8 stretching positions for the posterior capsule were simulated by passive internal rotation. Stretching positions of 0°, 30°, 60°, and 90° of elevation in the scapular plane; 60° of flexion; 60° of abduction; 30° of extension; and 60° of flexion and horizontal adduction were adopted. Strain was measured in the upper, middle, and lower parts of the capsule. The measurement of strain was instituted from reference length. Results With internal rotation, mean strain on the upper capsule was 3.02% at 0° of elevation and 3.35% at 30° of extension. Strain on the middle capsule at 0° and 30° elevation was 0.78% and 4.77%, respectively; on the lower capsule, it was 5.65% and 2.24% at 30° and 60° of elevation, respectively, and 2.88% at 30° of extension. Increase in strains of the upper, middle, and lower capsule with internal rotation at 0°, 30°, and 60° of elevation were statistically significant, respectively (P < .01). Other shoulder positions demonstrated no positive strain values. Conclusions Based on the results of this cadaver study, large strains on the posterior capsule of the shoulder were obtained at a stretching position of 30° of elevation in the scapular plane with internal rotation for the middle and lower capsule, while a stretching position of 30° of extension with internal rotation was effective for the upper and lower capsule. Clinical Relevance The current posterior capsule stretching program of the shoulder was not sufficient to stretch the entire posterior capsule.

Strain Reduction of the Extensor Carpi Radialis Brevis Tendon Proximal Origin Following the Application of a Forearm Support Band

STUDY DESIGN Experimental laboratory design. OBJECTIVES To measure the strain at the proximal origin of the extensor carpi radialis brevis (ECRB), and to determine the influence of a forearm support band. BACKGROUND A forearm support band is often used with the intent to decrease stresses around the origin of the wrist extensors. However, the influence of the location of the band has not been studied. METHODS AND MEASURES The forearm support band was applied on 8 cadaver arms (mean +/- SD age, 78.4 +/- 10.3 years) and 2 experimental conditions were performed. First, strain measurements were made without applying tension to the distal ECRB tendon, then strain measurements were made with a traction force of 21.5 N being applied to the distal ECRB tendon. Strain of the proximal origin of the ECRB, 1.0 cm distal from the lateral epicondyle, was recorded using a strain gauge. The band was mounted on the forearm at distances equal to 80%, 70%, 60%, 50%, 40%, 30%, and 20% of the forearm length as measured from the wrist. Testing order was randomized. Tension applied to the band was 19.6 N. RESULTS When no tension was applied to the ECRB, there was no statistically significant difference (P>.05) in strain values at the ECRB origin by mounting the band at any of the forearm positions. In the tension condition, the average (SD) strain with no band was 2.40% (1.40%). The average strain value of 0.85% (0.65%), when the band was mounted 80% of the forearm length proximal to the wrist, was statistically smaller than that obtained without the band (P<.05). CONCLUSIONS The strain on the ECRB origin was less when the forearm support band was applied 80% proximal from the wrist joint. LEVEL OF EVIDENCE Therapy, level 5.

Effect of Elbow and Forearm Position on Contact Pressure Between the Extensor Origin and the Lateral Side of the Capitellum

PURPOSE Bone-to-tendon contact in the origin of the common extensor tendons is considered to be one of the causes of lateral epicondylitis. Some factors, including elbow and forearm position, varus stress to the elbow, or contraction of the wrist extensor tendons, are considered to affect this bone-to-tendon contact. However, no studies have evaluated the effect of the elbow and forearm position on bone-tendon interface. The purpose of this study is to evaluate the effect of the position of the elbow and forearm on the contact pressure of the tendinous origin of the common wrist and finger extensors. METHODS We used 8 fresh cadaveric upper extremities. Contact pressure between the origin of the common extensor tendons and the lateral side of the capitellum was measured with a pressure sensor and was compared among various conditions, including elbow flexion angle (0°, 30°, 60°, and 90°), forearm rotation position (neutral and 81.5° pronation position), and varus stress load of the elbow (none, gravity on the forearm, and gravity on the forearm +1.96 Nm). Contact pressure was also measured during tension force of the extensor carpi radialis longus, extensor carpi radialis brevis, and extensor digitorum communis by 0, 9.8, and 19.6 N. RESULTS Contact pressure was significantly increased with the elbow extension position, forearm pronation position, and varus stress to the elbow under tension of the extensor carpi radialis longus or extensor carpi radialis brevis. CONCLUSIONS This study provides data about the amount of contact pressure between bone and tendon at the origin of the common extensor tendons in the elbow. This information may lead to a better understanding of, and better treatment for, lateral epicondylitis.

Evaluation of stretching position by measurement of strain on the ilio-femoral ligaments: An in vitro simulation using trans-lumbar cadaver specimens

The ilio-femoral ligament is known to cause flexion contracture of the hip joint. Stretching positioning is intended to elongate the ilio-femoral ligaments, however, no quantitative analysis to measure the effect of stretching positions on the ligament has yet been performed. Strains on the superior and inferior ilio-femoral ligaments in 8 fresh/frozen trans-lumbar cadaveric hip joints were measured using a displacement sensor, and the range of movement of the hip joints was recorded using a 3Space Magnetic Sensor. Reference length (L(0)) for each ligament was determined to measure strain on the ligaments. Hip positions at 10 degrees adduction with maximal external rotation, 20 degrees adduction with maximal external rotation, and maximal external rotation showed larger strain for the superior ilio-femoral ligament than the value obtained from L(0), and hip positions at 20 degrees external rotation with maximal extension and maximal extension had larger strain for the inferior ilio-femoral ligament than the value obtained from L(0) (p<0.05). Superior and inferior ilio-femoral ligaments exhibited positive strain values with specific stretching positions. Selective stretching for the ilio-femoral ligaments may contribute to achieve lengthening of the ligaments to treat flexion contracture of the hip joint.

Stretching positions for the coracohumeral ligament: Strain measurement during passive motion using fresh/frozen cadaver shoulders

BackgroundContracture of the coracohumeral ligament is reported to restrict external rotation of the shoulder with arm at the side and restrict posterior-inferior shift of the humeral head. The contracture is supposed to restrict range of motion of the glenohumeral joint.MethodsTo obtain stretching position of the coracohumeral ligament, strain on the ligament was measured at the superficial fibers of the ligament using 9 fresh/frozen cadaver shoulders. By sequential measurement using a strain gauge, the ligament strain was measured from reference length (L0). Shoulder positions were determined using a 3 Space Tracker System. Through a combination of previously reported coracohumeral stretching positions and those observed in preliminary measurement, ligament strain were measured by passive external rotation from 10° internal rotation, by adding each 10° external rotation, to maximal external rotation.ResultsStretching positions in which significantly larger strain were obtained compared to the L0 values were 0° elevation in scapula plane with 40°, 50° and maximum external rotation (5.68%, 7.2%, 7.87%), 30° extension with 50°, maximum external rotation (4.20%, 4.79%), and 30° extension + adduction with 30°, 40°, 50° and maximum external rotation (4.09%, 4.67%, 4.78%, 5.05%)(P < 0.05). No positive strain on the coracohumeral ligament was observed for the previously reported stretching positions; ie, 90° abduction with external rotation or flexion with external rotation.ConclusionsSignificant strain of the coracohumeral ligament will be achieved by passive external rotation at lower shoulder elevations, extension, and extension with adduction.

Ligament strain on the iliofemoral, pubofemoral, and ischiofemoral ligaments in cadaver specimens: Biomechanical measurement and anatomical observation

The iliofemoral, pubofemoral, and ischiofemoral ligaments are major structures that stabilize the hip joint. We have sought evidence on which to base more effective hip stretching positions. The purpose of this study was to measure strains on these ligaments and to observe them. Eight fresh/frozen translumbar cadaver specimens were used. Clinically available stretching positions for these ligaments were adopted. Strain on each ligament was measured by a displacement sensor during passive torque to the hip joint. Hip motion was measured using an electromagnetic tracking device. The strained ligaments were captured on clear photographs. Significantly, high strains were imposed on the superior iliofemoral ligament by external rotation of the hip (3.48%); on the inferior iliofemoral ligament by maximal extension and 10° or 20° of external rotation with maximal extension (1.86%, 1.46%, 1.25%); on the pubofemoral ligament by maximal abduction and 10°, 20°, or 30° of external rotation with maximal abduction (3.18%, 3.28%, 3.11%, 2.99%); and on the ischiofemoral ligament by 10° or 20° of abduction with maximal internal rotation (7.11%, 7.83%). Fiber direction in each ligament was clearly identified. Significantly, high strains on hip ligaments corresponded with the anatomical direction of the ligament fibers. Positions were identified for each ligament that imposed maximal increase in strain on it. Clin. Anat. 27:1068–1075, 2014.

Measurement of subclavicular pressure on the subclavian artery and brachial plexus in the costoclavicular space during provocative positioning for thoracic outlet syndrome

BackgroundThoracic outlet syndrome is thought to be caused by compression of the brachial plexus or subclavian artery in the interscalene, costoclavicular, or subcoracoid space. Some provocative tests are widely used for diagnosing thoracic outlet syndrome. However, whether provocative positions actually compress the neurovascular bundle in these spaces remains unclear. The purpose of this study was to investigate the possibility of neurovascular bundle compression in the costoclavicular space by measuring the pressure applied to the brachial plexus and subclavian artery in provocative positions.MethodsBilateral shoulders of eight fresh-frozen transthoracic human cadavers with no obvious anatomical abnormalities were used in this study. There were three female and five male cadavers with a mean age of 81.7 years (range 72–90 years). The pressure on the brachial plexus and subclavian artery between the clavicle and first rib were measured using a 0.13-mm thin pressure sensor in each of four provocative positions (depressed position, alternative Eden position, throwing position, Wright position).ResultsNerve contact pressure was increased in seven shoulders in the Wright position (2.87 ± 3.13 N/cm2; range 0.81–9.76 N/cm2). The frequency of nerve compression in the Wright position was significantly higher when compared to that in the other three limb positions (P = 0.018). Artery contact pressure was increased in three shoulders in the Wright position (mean 0.59 ± 0.13 N/cm2; range 0.45–0.7 N/cm2). As was the case with nerve compression, the frequency of compression tended to be higher for the Wright position, but no significant difference was seen.ConclusionsIn four of eight specimens with no obvious anatomical abnormalities, the brachial plexus was compressed in the costoclavicular space in the Wright position. The Wright position thus may be a useful position for inducing nerve compression in the costoclavicular space.