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Results for “Joint Capsule”

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At least 181 records · Page 10Linked to original sources
PubMed1999

In situ force distribution in the glenohumeral joint capsule during anterior-posterior loading.

Our objective was to examine the function of the glenohumeral capsule and ligaments during application of an anterior-posterior load by directly measuring the in situ force distribution in these structures as well as the compliance of the joint. We hypothesized that interaction between different regions of the capsule due to its continuous nature results in a complex force distribution throughout the glenohumeral joint capsule. A robotic/universal force-moment sensor testing system was utilized to determine the force distribution in the glenohumeral capsule and ligaments of intact shoulder specimens and the joint kinematics resulting from the application of external loads at four abduction angles. Our results suggest that the glenohumeral capsule carries no force when the humeral head is centered in the glenoid with the humerus in anatomic rotation. However, once an anterior-posterior load is applied to the joint, the glenohumeral ligaments carry force (during anterior loading, the superior glenohumeral-coracohumeral ligaments carried 26+/-16 N at 0 degrees and the anterior band of the inferior glenohumeral ligament carried 30+/-21 N at 90 degrees). Therefore, the patient's ability to use the arm with the humerus in anatomic rotation should not be limited following repair procedures for shoulder instability because the repaired capsuloligamentous structures should not carry force during this motion. Separation of the capsule into its components revealed that forces are being transmitted between each region and that the glenohumeral ligaments do not act as traditional ligaments that carry a pure tensile force along their length. The interrelationship of the glenohumeral ligaments forms the biomechanical basis for the capsular shift procedure. The compliance of the joint under our loading conditions indicates that the passive properties of the capsule provide little resistance to motion of the humerus during 10 mm of anterior or posterior translation with anatomic humeral rotation. Finally, this knowledge also enhances the understanding of arm positioning relative to the portion of the glenohumeral capsule that limits translation during examination under anesthesia.

Aged↗
PubMed2000

Comparative effects of laser and radiofrequency energy on joint capsule.

The study compared the effects of laser and monopolar radiofrequency energy on thermal and architectural properties of joint capsular tissue in an in vitro ovine model. Sheep glenohumeral joint capsular specimens were treated with laser (5, 10, 15 W) or radiofrequency energy (55 degrees, 65 degrees, 75 degrees C) (n = six per group). Energy application caused significant tissue shrinkage and decreased surface area in all laser and radiofrequency treatment groups. Tissue thickness significantly increased in all treatment groups except for radiofrequency 55 degrees C. Tissue shrinkage, surface area, and thickness each correlated significantly with the delivered laser energy per tissue area or mean radiofrequency probe temperature. There were no significant differences among laser 10 W, laser 15 W, and radiofrequency 75 degrees C treatment groups for these three architectural parameters. Tissue temperature was elevated significantly in the laser 10 W, laser 15 W, radiofrequency 65 degrees C, and radiofrequency 75 degrees C groups when compared with the control. Tissue temperature changes between the laser 10 W and radiofrequency 75 degrees C groups were similar; however, laser treatment produced a steeper temperature increase accompanying its peak temperature. Despite different mechanisms, laser and radiofrequency energy can achieve similar and predictable tissue modification, which is temperature dependent. Additional in vivo studies must be performed to evaluate the applicability of these techniques to clinical use.

Animals↗
PubMed2000

Cystic adventitial disease of the popliteal artery: elongation into the media of the popliteal artery and communication with the knee joint capsule: report of a case.

Cystic disease of the popliteal artery is a rare disorder in which most cases involve the formation of an adventitial cyst that disturbs the popliteal artery blood flow. We present herein the case of a patient presenting with popliteal artery occlusion due to compression by a cyst which formed at the media of the popliteal artery. The onset occurred during a baseball game in which he played catcher. Preoperative magnetic resonance imaging demonstrated a communication of the cyst with the adjacent knee joint. This unusual case could provide important clues to help identify the pathogenesis of this disease.

Adult↗
PubMed1993

Does the glenohumeral joint capsule have proprioceptive capability?

We performed a clinical study examining 60 volunteers with stable shoulder joints randomized to two groups. In group 1 we injected 5 ml lidocaine intra-articularly. In group 2 we injected 5 ml saline with 5 ml contrast dye the same way. After the injection we measured the amount of passive anteroposterior translation that occurred during anterior and posterior drawer tests and the amount of inferior subluxation during downward stress. We documented the extent of the passive glenohumeral translation using ultrasound. We had no complications related to the intra-articular injection or to the stability measurement. After the injection neither group had significant pain, and the patients were not apprehensive about the ensuing stability test. In group 1 (lidocaine) anteroposterior translation of 13.2 +/- 6.3 mm was seen in the anterior and posterior drawer test, whereas in group 2 (no lidocaine) the anteroposterior translation was only 6.8 +/- 3.2 mm. The difference between the two groups was statistically significant (P < 0.05). With downward stress during the sulcus test the distance between the acromion and the humeral head increased by 5.6 mm (+/- 3.2) in group 1 and by 2.7 mm (+/- 2.1) in group 2. This difference was also statistically significant (P < 0.05). Clinical consequences: Taking our preliminary findings into account, the capsule of the glenohumeral joint seems to have proprioceptive capability. Nerve fibres and mechanoreceptors seem to be localized in the capsule tissue, being part of a physiological feedback mechanism. If our conclusions proprioceptive capability. Nerve fibres and mechanoreceptors seem to be localized in the capsule tissue, being part of a physiological feedback mechanism.

Adolescent↗
PubMedDate not supplied

The thermal properties of bovine joint capsule. The basic science of laser- and radiofrequency-induced capsular shrinkage.

Orthopaedic surgeons have recently adapted the holmium: yttrium-aluminum-garnet (YAG) laser for the shrinkage of capsular tissues for treatment of glenohumeral instability. The molecular mechanism of capsular shrinkage has not been documented to date. This study examined the effects of heating on bovine calf knee capsule and subsequent shrinkage of the capsule. Capsule specimens were placed in a saline bath at temperatures ranging from 55 degrees to 75 degrees C for 1, 3, 5, and 10 minutes. Shrinkage was quantified by digital imaging, and the tissue was examined by light and polarized light microscopy. Tissue contraction was not measurable at or below 57.5 degrees C. At 60 degrees C, tissue shrinkage occurred with corresponding basophilic staining and loss of birefringence in collagen fibers. For specimens heated at 60 degrees C and 62 degrees C, shrinkage directly correlated with duration of thermal exposure. Maximal shrinkage of approximately 50% in length occurred at and above 65 degrees C with thermal exposures of 1 minute or greater. This study demonstrates that thermal shrinkage of bovine knee capsule correlates with denaturation of collagen fibers and depends on both time and temperature. Capsular shrinkage treatments may be performed with any energy source that is capable of well-controlled heating of capsular tissue and does not depend on the special properties of laser light.

Animals↗
PubMed1996

Responses of mechanoreceptor neurons in the cat knee joint capsule before and after anterior cruciate ligament transection.

It is known that afferent neurons play a protective role in knees made unstable by transection of the anterior cruciate ligament. However, it is not known whether cutting the anterior cruciate ligament has an effect on the response of the sensory neurons that innervate the joint. In this study, the responsiveness (activation threshold and position sensitivity) of single, mechanically sensitive afferent neurons from the cat knee was evaluated by a series of extension, internal, and external rotations. The anterior cruciate ligament then was cut and the same procedure was repeated. Transection of the ligament increased joint laxity for all types of rotation. The responsiveness of the neurons was not changed significantly by cutting the ligament (p > 0.05). Therefore, capsule afferents continue to behave normally in joints in which the anterior cruciate ligament has been transected.

Animals↗
PubMed1998

The distal radioulnar joint capsule: clinical anatomy and role in posttraumatic limitation of forearm rotation.

Posttraumatic limitation of forearm rotation can be the result of pathology at any location along the forearm axis. Scar contracture of the distal radioulnar joint (DRUJ) capsule, independent of the triangular fibrocartilage complex (TFCC), is one of the sources that may influence the pronosupination arc. We dissected the wrists of 8 fresh-frozen cadaver specimens to characterize the precise anatomy, relationships, and dynamic characteristics of the entire DRUJ capsule. Additionally, we performed surgical DRUJ capsulectomy in 9 patients with recalcitrant limited forearm pronosupination that was unattributable to dysfunction at any other anatomic forearm location. We conclude that (1) the DRUJ capsule is a defined entity, separate from the triangular fibrocartilage, that is highly specialized to accommodate the distal ulna in forearm rotation; (2) in patients who have restored osseous anatomy after trauma, but have failed to regain pronosupination after maximal rehabilitation, the DRUJ capsule can be identified as the source of the limitation; and (3) DRUJ capsulectomy can markedly improve the arc of forearm rotation in carefully selected patients.

Biomechanical Phenomena↗