RESUMO
The purpose of this study was to determine the initial effects of Holmium:YAG laser energy on the shoulder joint capsule. A new surgical procedure to correct shoulder joint instability uses Holmium:YAG laser energy to cause "shrinkage" of joint capsular tissues. To date there has been no information concerning an intraoperative measurable end point for the application of laser energy at surgery or the resultant depth and degree of tissue alteration. Seven greyhound dogs were used in this study. Preoperative intraarticular pressures (IAP) were measured on entry and after injection of 10 ml of solution. Laser energy was applied to the cranial medial glenohumeral ligament and joint capsule of all right shoulders with arthroscopic visualization. The unoperated left shoulders served as the control group. Six weeks after surgery pressure measurements were performed on both shoulders. A "second look" arthroscopy was performed on the shoulders. After euthanasia was performed, the anterior capsular tissues were harvested from both shoulders for histologic examination. The specimens were inspected by three blinded examiners. After 6 weeks the postoperative laser-treated IAP were higher than the same joint preoperative IAP in four of six dogs for both static nondistension and 10 ml distension measurements. At this same interval the marked tissue damage of the treated capsule was easily discerned by blinded observers. On histologic evaluation the laser-treated capsule showed synovitis and pericapsular tissue reactivity. The depth of the injury was beyond the joint capsule into the pericapsular tissue. It was not possible to determine the end point of the capsular "shrinkage" operation by combined pressure/volume intraoperative measurements. There was no uniform joint capsule compliance at 6 weeks. The histologic changes were extensive in both magnitude and depth. Future studies in this animal should include decreased laser energy plus other means of monitoring the intraoperative effects of laser use.
Assuntos
Terapia a Laser , Articulação do Ombro/cirurgia , Animais , Artroscopia , Cães , Ligamentos Articulares/patologia , Pressão , Articulação do Ombro/patologia , Articulação do Ombro/fisiopatologia , Membrana Sinovial/patologiaRESUMO
Comparison of perilesional cartilage, lesional repair tissue, and subchondral bone activity 6 months after application of holmium-yttrium-aluminum-garnet (Ho:YAG) laser energy to chronic (10 week) induced 10-mm full-thickness (FT) circular articular cartilage craters followed by 6 months' intermittent active motion (IAM) in a free exercise environment was investigated. The 2.1-microns wavelength was delivered in hand-controlled near-contact mode by arthroscopic surgery in a saline medium. Bilateral arthroscopy was performed on normal antebrachiocarpal, intercarpal, and metacarpophalangeal joints of six adult horses. Full-thickness craters were created in nine sites per limb on weight-bearing articular surfaces with a motorized bur. Right limb craters served as sham operated controls. Animals were killed at 10 weeks after FT crater creation (n = 2), and at 24 weeks (6 months) after laser energy application (n = 4). Histological analysis using hematoxylineosin (HE) and Safranin-O staining consisted of a modified Mankin grading of perilesional cartilage and lesional repair tissue scoring. Biochemical analysis was performed for cellularity and glycosaminoglycan (GAG) synthesis. Histological analysis showed clustering of chondrocytes or perilesional zonal cloning (PZC) in 83% of laser-treated lesions and in no control lesions. No differences were observed between treated and control lesional repair activity. Laser-treated perilesional cartilage showed a significant (P < .02) decrease in GAG synthesis. No adverse effects to distant cartilage were observed after application of laser energy regarding cell proliferation or GAG synthesis. Significance of decreased GAG synthesis in treated perilesional cartilage and perilesional zonal cloning of chondrocytes in treated cartilage is unknown. Additional study of Ho:YAG laser energy application to cartilage and subchondral bone is needed before its application in the surgical management and repair of cartilage damage.
