Effect of nonablative laser energy on the joint capsule: an in vivo rabbit study using a holmium:YAG laser

Treatment of snoring disorder with a non-ablactive Er:YAG laser dual mode protocol. An interventional study

Background

Snoring disorder is a common problem among world population. Treatment modalities may involve surgical and non-surgical procedures. As main objective we proposed to evaluate the efficacy of non-ablative Er:YAG laser in the treatment of snoring disorder.

Material and Methods

We performed an interventional study in 30 patients with snoring disorders. Three sessions were performed with Er:YAG laser 2940nm in long pulse mode (2J/cm2) and smooth mode (10-8J/cm2) in oropharynx region. We analyzed the efficacy of this protocol using questionnaires for snoring intensity, snoring related characteristics of quality of life (including the Epworth sleepness scale and OHIP-14), the satisfaction of the patients and existence of adverse effects comparing the results before and after the treatment using Wilcoxon Signed Rank test.

Results

There was a 96.7% satisfaction rate after one month of treatment, and 96.4% after 6 months. A reduction of the severity of snoring from 8±1.9 before the treatment to 1.6±1.1 one month after treatment was observed (p<0.001). Decrease in mean values of Epworth sleepness scale (9.97±5.3 to 6.54±4.3) (p=0.002), and OHIP-14 score (10.9±6.2 to 5.9±5) (p<0.001) were also noted. A significant decrease in the Mallampatti and Friedman classification scores were observed (p=0.001 and p<0.001, respectively). No anesthesia was required, nor adverse effects were observed.

Conclusions

Non-ablative Er:YAG laser treatment is a safe, painless, and can be an effective treatment option to reduce snoring and is well accepted by the patient. However, further controlled studies with longer follow-up are required.

Key words:Er:YAG laser, snoring, sleep disorders, epworth sleepiness scale, OHIP-14.

The effect of postoperative immobilization on the healing of radiofrequency heat probe modified tissue: assessment of tissue length, stiffness, and morphology

The effect of postoperative immobilization on the length, stiffness, and structure of connective tissue after radiofrequency probe shrinkage was examined in a rabbit patellar tendon model. Tendon lengths were measured before, immediately following, and 2, 4, and 8 weeks following heat application, with the contralateral tendon as a control. The animals were randomly assigned to three groups. In Group I, the controls, the animals were allowed free caged activity for 8 weeks. In Groups II and III, the experimental limb was immobilized at 15 degrees of knee flexion for 2 and 4 weeks, respectively, after which the animals were allowed 6 and 4 weeks of free caged activity. Changes in tendon length, stiffness, and cross-sectional area were compared using repeated measures ANOVA and differences between groups examined using Tukey's post-hoc analysis. Patellar tendon lengths were increased in all 3 groups at 8 weeks (P< .001). Tissue elongation was less extensive in group III compared to group I at 8 weeks (P< .001), while tissue cross-sectional area was decreased in both groups II and III compared to group I at 8 weeks (P< .001). All groups demonstrated decreases in tensile strength when compared to controls (P< .001). These findings suggest that postoperative immobilization is important following thermal shrinkage of connective tissue, as early activity can lead to stretching of the heat-modified tissue.

Laser-induced collagen remodeling and deposition within the basilar membrane of the mouse cochlea

The cochlea is the mammalian organ of hearing. Its predominant vibratory element, the basilar membrane, is tonotopically tuned, based on the spatial variation of its mass and stiffness. The constituent collagen fibers of the basilar membrane affect its stiffness. Laser irradiation can induce collagen remodeling and deposition in various tissues. We tested whether similar effects could be induced within the basilar membrane. Trypan blue was perfused into the scala tympani of anesthetized mice to stain the basilar membrane. We then irradiated the cochleas with a 694-nm pulsed ruby laser at 15 or 180 Jcm(2). The mice were sacrificed 14 to 16 days later and collagen organization was studied. Polarization microscopy revealed that laser irradiation increased the birefringence within the basilar membrane in a dose-dependent manner. Electron microscopy demonstrated an increase in the density of collagen fibers and the deposition of new fibrils between collagen fibers after laser irradiation. As an assessment of hearing, auditory brainstem response (ABR) thresholds were found to increase moderately after 15 Jcm(2) and substantially after 180 Jcm(2). Our results demonstrate that collagen remodeling and new collagen deposition occurs within the basilar membrane after laser irradiation in a similar fashion to that found in other tissues.

Thermal capsulorrhaphy for the treatment of shoulder instability

Thermal capsulorrhaphy has been used to treat many different types of shoulder instability, including multidirectional instability, unidirectional instability, and microinstability in overhead-throwing athletes. A device that delivers laser energy or radiofrequency energy to the capsule tissue causes the collagen to denature and the capsule to shrink. The optimal temperature to achieve the most shrinkage without causing necrosis of the tissue is between 65 degrees and 75 degrees centigrade. This treatment causes a significant decrease in mechanical stiffness for the first 2 weeks, and then, after the tissue undergoes active cellular repair from the surrounding uninjured tissue, the mechanical properties return to near normal by 12 weeks. If the thermal energy is applied in a grid pattern, then the tissue heals with more stiffness by 6 weeks. Clinical studies on thermal capsulorrhaphy for the treatment of multidirectional instability have shown a high rate of recurrent instability (12%-64%). The clinical studies on unidirectional instability showed much better recurrence rates (4%-25%), but because most of the patients also underwent concomitant Bankart repairs and superior labral anterior posterior lesion repairs, the efficacy of the thermal treatment cannot be ascertained. A randomized controlled trial would be needed to assess whether instability with Bankart lesions requires augmentation with thermal capsulorrhaphy. For the patients with microinstability who are overhead-throwing athletes, thermal capsulorrhaphy has shown varying results from a 97% rate of return to sports to a 62% rate of return to sports. Complications of this technique include temporary nerve injuries that usually involve the sensory branch of the axillary nerve and thermal necrosis of the capsule, which is rare.

Intradiscal thermal therapy does not stimulate biologic remodeling in an in vivo sheep model

STUDY DESIGN

Thermal energy was delivered in vivo to ovine cervical discs and the postheating response was monitored over time.

OBJECTIVES

To determine the effects of two distinctly different thermal exposures on biologic remodeling: a "high-dose" regimen intended to produce both cellular necrosis and collagen denaturation and a "low-dose" regimen intended only to kill cells.

SUMMARY OF BACKGROUND DATA

Thermal therapy is a minimally invasive technique that may ameliorate discogenic back pain. Potential therapeutic mechanisms include shrinkage of collagenous tissues, stimulation of biologic remodeling, and ablation of cytokine-producing cells and nociceptive fibers.

METHODS

Intradiscal heating was performed using directional interstitial ultrasound applicators. Temperature and thermal dose distributions were characterized. The effects of high (>70 C, 10 minutes) and low (52 C-54 C, 10 minutes) temperature treatments on chronic biomechanical and architectural changes were compared with sham-treated and control discs at 7, 45, and 180 days.

RESULTS

The high-dose treatment caused both an acute and chronic loss of proteoglycan staining and a degradation of biomechanical properties compared with low-dose and sham groups. Similar amounts of degradation were observed in the low-dose and sham-treated discs relative to the control discs at 180 days after treatment.

CONCLUSIONS

While a high temperature thermal protocol had a detrimental effect on the disc, the effects of low temperature treatment were relatively minor. Thermal therapy did not stimulate significant biologic remodeling. Future studies should focus on the effects of low-dose therapy on tissue innervation and pro-inflammatory factor production.

The effect of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament: an experimental study

PURPOSE

The purpose of this study was to determine the acute effects of electrothermal shrinkage on the biomechanical properties of the anterior cruciate ligament (ACL).

TYPE OF STUDY

Randomized trial.

METHODS

Fifty fresh femur-ACL-tibia complexes harvested from fully matured pigs were used. The femur-anteromedial bundle-tibia complex specimens were randomly divided into 5 groups of 10 specimens each. In each group, radiofrequency energy set at nonablative levels was applied to the anteromedial bundle of the ACL with a bipolar radiofrequency generator. In groups I and II, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 30 seconds. In groups III and IV, radiofrequency treatment was applied to the ACL using 28 W and 45 W power, respectively, for 60 seconds. In group V, no treatment was applied in order to obtain normal control data. The treatment was performed in physiological saline solution under a 1-N load. In each group, 8 of the 10 specimens were used for biomechanical evaluation, and the remaining 2 were used for histologic observation.

RESULTS

Concerning the length of the anteromedial bundle after the treatment, the analysis of variance (ANOVA) showed a significant difference among the 5 groups. The length in groups I, II, III, and IV was significantly shorter than that of group V. In tensile testing, the stiffness was 120, 116, 113, 89, and 156 N/mm in groups I, II, III, IV, and V, respectively. The ANOVA showed a significant difference among the groups. Groups I, II, III, and IV were significantly lower than group V, respectively. Histologic examination showed diffuse collagenous denaturation and pyknotic nuclear changes in fibroblasts at the treated portion. The collagen crimp pattern was not present in the treated area.

CONCLUSIONS

Application of RF energy to the specimens caused both shortening and weakening according to the magnitude and duration of the application.

CLINICAL RELEVANCE

These results may explain one of the causes of the poor results reported in some clinical studies. This study warns against a too optimistic application of electrothermal shrinkage to the ACL as a clinical treatment.

Laser irradiation of the guinea pig basilar membrane

BACKGROUND AND OBJECTIVES

The cochlea is the part of the inner ear that transduces sound waves into neural signals. The basilar membrane, a connective tissue sheet within the cochlea, is tonotopically tuned based on the spatial variation of its mass, stiffness, and damping. These biophysical properties are mainly defined by its constituent collagen fibers. We sought to assess the effect of laser irradiation on collagen within the basilar membrane using histological analysis.

STUDY DESIGN/MATERIALS AND METHODS

Four excised guinea pig cochleae were stained with trypan blue. From these, two were irradiated with a 600 nm pulsed dye laser and two were used as controls. Collagen organization was visualized using polarization microscopy.

RESULTS

Laser irradiation reduced the birefringence within the basilar membrane as well as within other stained collagen-containing structures. Larger reductions in birefringence were measured when more laser pulses were given. The effects were similar across all turns of each cochlea.

CONCLUSIONS

Laser irradiation causes immediate alterations in collagen organization within the cochlea that can be visualized with polarization microscopy. These alterations may affect cochlear tuning. Ongoing research is aimed at analyzing the effect of laser irradiation on cochlear function. It is conceivable that this technique may have therapeutic benefits for patients with high-frequency sensorineural hearing loss.

Efeito do Hólmio YAG laser (Ho: YAG) sobre o tendão patelar de ratos após 12 e 24 semanas de seguimento

Os autores estudaram os efeitos do laser Hólmio:Ítrio-Alumínio-Granada (Ho: YAG) sobre as dimensões do tendão (comprimento e largura proximal e distal) e sobre a celularidade e arranjo das fibras de colágeno em 20 ratos adultos, machos, brancos (Ratus Novergicus) da varidade Wistar. Os animais foram divididos em dois grupos de acordo com o tempo de seguimento (12 e 24 semanas) e de acordo com a forma de aplicação do laser (contínua e em dois pontos). Utilizou-se aparelho de laser de Hólmio (pulsátil, estado sólido, com ondas de 2,1 microns, com potência de 40 watts, ponteira OmniTip de 30º) . Após o sacrifício, foram comparadas por meio de testes não paramétricos (considerando p = 0,05) as medidas de comprimento e da largura (proximal e distal) dos tendões do lado operado e do lado não operado. A medida do comprimento do lado operado foi significativamente maior nos dois grupos de seguimento, quando comparado com o lado não operado, porém, não houve diferença significativa dessas medidas em função do tipo de aplicação do laser. Do mesmo modo, a medida da largura, tanto na região proximal quanto distal, foram significativamente maiores no lado operado nos dois grupos de seguimento, sem apresentar diferença significativa em função do tipo de aplicação. Quando se compararam as medidas nos dois grupos de seguimento, o comprimento e a largura distal tenderam a ser maiores após 24 semanas, enquanto que a largura, na região proximal, foi significativamente maior nesse grupo. Quanto à avaliação microscópica subjetiva, tanto nos cortes longitudinais como transversais, pôde-se verificar aumento do número de fibroblastos, principalmente no grupo de 12 semanas. A concentração média de fibroblastos nos tendões com 24 semanas de seguimento foi considerada como intermediário entre o grupo de 12 semanas e os tendões não operados. Na região entre os fascículos, o tecido conjuntivo era exuberante no grupo com 12 semanas, com neoformação vascular evidente. No grupo de 24 semanas as fibras de colágeno se apresentavam com disposição regular e paralela ao longo eixo do tendão.

Complications of thermal ablation in wrist arthroscopy

Wrist arthroscopy is a valuable diagnostic and therapeutic tool. Thermal ablation can be used concomitantly to treat partial ligamentous tears, triangular fibrocartilage cartilage complex tears, and to perform partial synovectomy. We reviewed 47 consecutive patients who underwent wrist arthroscopy with concomitant thermal ablation between 1997 and 2001. Three patients sustained serious complications. The serious complications included, in all three patients, tendon ruptures and in one case, a 5 x 10-mm full-thickness skin burn. Thermal treatment of collagenous tissues has recently gained popularity in the orthopedic literature, but there is little information on the potential complications. The arthroscopist of large and small joints must be aware of the risks involved when using thermal ablation.

Does immobilization after radiofrequency-induced shrinkage influence the biomechanical properties of collagenous tissue? An in vivo rabbit study

BACKGROUND

Despite widespread use of radiofrequency-induced shrinkage of collagenous tissue, there have been no animal studies on the effects of postoperative immobilization on the biomechanical behavior of shrunken tissue.

PURPOSE

To examine the role of postoperative immobilization after radiofrequency-induced shrinkage, with special emphasis on the biomechanical properties of shrunken collagenous tissue.

STUDY DESIGN

Controlled laboratory study.

METHODS

One patellar tendon of 66 New Zealand White rabbits was shrunk. Six rabbits were sacrificed immediately after surgery. Twenty rabbits were not immobilized, twenty were immobilized for 3 weeks, and twenty were immobilized for 6 weeks. The biomechanical parameters failure strength, stiffness, and relaxation were tested.

RESULTS

Nine weeks after surgery, biomechanical parameters were still low compared to control tendons. Shrunken tendons did not reach levels of normal tissue at any time after surgery, regardless of whether the animals had been immobilized. According to time-related development, all biomechanical parameters had the lowest levels 3 weeks after surgery. Immobilized tendons demonstrated a better and faster recovery than nonimmobilized tendons compared to the immediate postoperative level.

CONCLUSION

Postoperative immobilization supports recovery of biomechanical properties after shrinkage. Despite immobilization, biomechanical properties of shrunken tissue did not completely reach levels of normal tissue.

CLINICAL RELEVANCE

Careful rehabilitation is imperative after radiofrequency-induced shrinkage. This animal model supports an immobilization period of at least 6 weeks after surgery.

The effect of radiofrequency thermal capsulorrhaphy on glenohumeral translation, rotation, and volume

The purpose of this study is to evaluate the effects of radiofrequency (RF) thermal capsulorrhaphy on the kinematic properties of the glenohumeral joint as determined by changes in resistance to multidirectional translational forces, alteration in the range of internal and external rotation, and changes in glenohumeral joint volume. Nonablative RF thermal energy was used to contract the glenohumeral joint capsule in 6 cadaveric shoulders. Measurements of translation were made after application of a 30-N load in anterior, posterior, and inferior directions. The maximum arc of internal and external rotation after application of a 1-N-m moment was also determined for vented specimens before and after thermal capsulorrhaphy. The percent reduction in glenohumeral capsular volume was measured by use of a saline solution injection-aspiration technique. Capsular shrinkage resulted in reductions in anterior, posterior, and inferior translation. The largest percent reductions in anterior translation were seen in external rotation at 45 degrees (48%, P <.05) and 90 degrees (41%, P <.05) abduction. For inferior translation, the largest percent reductions were seen in internal rotation at 45 degrees (40%, P <.05) and 90 degrees (45%, P <.05) abduction. Reductions in posterior translation were noted in internal rotation at 45 degrees (27%, P <.05) and 90 degrees (26%, P <.05) abduction. Other changes in translation were observed but were not statistically significant. The maximum arc of humeral rotation was reduced by a mean of 14 degrees at 45 degrees abduction and 9 degrees at 90 degrees abduction. The mean percent reduction in capsular volume for all shoulders was 37% (range, 8%-50%). This could not be correlated with percent reductions in translation and rotation. This study demonstrated the significant effect of RF thermal capsulorrhaphy in reducing glenohumeral multidirectional translation and volume with only a small loss of rotation in cadaveric shoulders.

Thermal-assisted capsular shrinkage of the glenohumeral joint in overhead athletes: a 15- to 47-month follow-up

STUDY DESIGN

Descriptive postoperative follow-up research.

OBJECTIVES

The purpose of this investigation was to describe the return-to-competition rate and functional outcome of overhead athletes following arthroscopic thermal-assisted capsular shrinkage (TACS).

BACKGROUND

Traditional open procedures to correct instability in overhead athletes, such as capsulolabral repairs and capsular shifts, have produced less-than-favorable results, which have led to the development of TACS. Currently there are no long-term follow-up studies documenting the efficacy of this procedure in groups greater than 31 subjects or for a time period greater than 27 months.

METHODS AND MEASURES

Two hundred thirty-one consecutive overhead athletes who due to symptoms of hyperlaxity had previously undergone a TACS procedure from 1997 to 1999 were selected for inclusion in the study. During a 1-month period, 130 of these athletes (mean age +/- SD, 24 +/- 6 years; 113 male, 17 female) were contacted by phone for follow-up at a mean of 29.3 months postoperatively (range, 15.4-46.6 months). Of the 130, 105 participated in baseball (80 pitchers), 14 in softball, 4 in football (quarterbacks), 4 in tennis, and 3 in swimming. Fifty-four (42%) subjects were professional, 49 (38%) collegiate, 16 (12%) high school, and 11 (8%) recreational athletes. One hundred twenty-three of the 130 (95%) underwent 1 or more concomitant procedure(s) at the time of TACS. Most commonly performed were labral debridements (69%), rotator cuff debridements (65%), and superior labral repairs (35%). Subjects who returned to competition were retrospectively evaluated using a modified Athletic Shoulder Outcome Rating Scale to subjectively assess pain, strength and endurance, stability, intensity, and performance. Overall results were based on a 90-point scale with scores of 80 to 90 representing excellent, 60 to 79 good, 40 to 59 fair, and less than 40 poor results.

RESULTS

One hundred thirteen out of 130 subjects (87%) returned to competition. Mean (+/-SD) time from surgery to return to competition was 8.4 +/- 4.6 months. Mean outcome score for all subjects was 79/90; 75 (66%) subjects had excellent, 24 (21%) good, 11 (10%) fair, and 3 (3%) poor result. The mean outcome score for males was 80/90 and for females was 70/90.

CONCLUSIONS

The majority of overhead athletes (87%) successfully returned to competition following a TACS procedure with good-to-excellent long-term outcomes (88%). Based on the results of this study, TACS of the glenohumeral joint is a viable option for overhead athletes with pathological instability.

Glenohumeral joint translation after arthroscopic thermal capsuloplasty of the posterior capsule

Treatment of recurrent posterior or multidirectional glenohumeral instability in athletes with traditional operative management has produced variable results at long-term follow-up. The purpose of this study was to determine whether an arthroscopic thermal capsuloplasty of the posterior capsule with a radiofrequency probe significantly decreases anterior-posterior glenohumeral translation. Successive posterior and anterior loads of 10, 15, and 20 N were applied sequentially to 7 cadaveric shoulder joints that were mounted in a translation testing apparatus with an electromagnetic tracking device measuring posterior and anterior glenohumeral translation. Arthroscopic thermal capsuloplasty was then performed on the posterior capsular tissue with a radiofrequency probe. The identical posterior-anterior loading protocol was then repeated, and translations were recorded. The results demonstrated no statistically significant differences in the mean posterior translation measurements before and after arthroscopic thermal capsuloplasty of the posterior capsule for the 10-N (+8.9%), 15-N (-3.1%), or 20-N (-1.8%) load (P >.50 to.62). Slightly greater changes occurred in anterior translation after posterior capsuloplasty at 10 N (-1.0%), 15 N (-6.0%), and 20 N (-10.3%). However, these changes were not found to be significant either (P =.06 to.62). The results of this study demonstrated that neither posterior nor anterior glenohumeral translation was significantly decreased by thermal capsuloplasty of the posterior capsule. Perhaps the lack of substantial collagenous material in the thin posterior capsule accounts for the inability of thermal capsuloplasty to be effective in this region.

Glenohumeral joint translation after arthroscopic thermal capsuloplasty of the rotator interval

The treatment of recurrent anterior, posterior, or multidirectional glenohumeral instability by operative closure of the rotator interval has been proposed. The purpose of this study was to determine whether arthroscopic thermal capsuloplasty of the rotator interval with the radiofrequency probe significantly decreases anterior-posterior glenohumeral translation. Anterior and posterior loads of 10, 15, and 20 N were sequentially applied to 8 cadaveric shoulder joints while mounted in a translation testing apparatus with an electromagnetic tracking device measuring anterior and posterior glenohumeral translation. Arthroscopic thermal capsuloplasty was then performed on the rotator interval with a radiofrequency probe. The identical anterior-posterior loading protocol was then repeated, and translations were recorded. The results showed a significant reduction in anterior and posterior translation after thermal capsuloplasty. After rotator interval thermal capsuloplasty, anterior translation decreased by 31.5%, 28.8%, and 27.2% for the 10-, 15-, and 20-N loads, respectively. Posterior translation decreased by 43.1%, 43.8%, and 40.7%, respectively. The results of this study indicate that arthroscopic thermal capsuloplasty of the rotator interval is an effective way by which to decrease both anterior and posterior glenohumeral translation in vitro. To date, no in vivo studies that sufficiently document long-term clinically successful outcomes of such a procedure exist. Future studies are warranted to evaluate the effects of the biologic response to thermal shrinkage and whether these reduced glenohumeral translations will be maintained.

Influence of postoperative immobilization on tendon length after radiofrequency-induced shrinkage. An in vivo rabbit study

BACKGROUND

Despite the widespread use of radiofrequency-induced shrinkage of collagenous tissues, there have been no animal studies on the effects of postoperative immobilization after such treatment.

PURPOSE

To examine the effects of postoperative immobilization after radiofrequency energy treatment, with special emphasis on any tissue length increases.

STUDY DESIGN

Controlled laboratory study.

METHODS

The right patellar tendon of 60 New Zealand White rabbits was shrunk with a radiofrequency probe. Tendon length was measured intraoperatively before and after shrinkage and via radiographs immediately postoperatively and at 3, 6, and 9 weeks. Twenty rabbits were not immobilized, 20 were immobilized for 3 weeks, and 20 were immobilized for 6 weeks.

RESULTS

In the nonimmobilized limbs, the tendon length increased 34.9% at 3 weeks and another 2.5% at 6 weeks, versus 11.2% at 3 weeks and 6.6% at 6 weeks in the immobilized limbs. Ten of the 20 rabbits that were immobilized for 6 weeks were sacrificed at 9 weeks and were found to have a further length increase of 10.8%. At 9 weeks, the tendons of this group were no longer significantly shorter than the tendons from rabbits that had not been immobilized.

CONCLUSIONS

Careful postoperative rehabilitation is imperative after radiofrequency-induced shrinkage. Without protection, exposure to normal physiologic loads places the shrunken tissue at risk of stretching out beyond the preshrinkage length.

CLINICAL RELEVANCE

Shrunken tissue is at risk of stretching out after radiofrequency-induced shrinkage.

The vascular anatomy of the glenohumeral capsule and ligaments: an anatomic study

BACKGROUND

A detailed description of the vascular anatomy of the shoulder capsule is lacking, yet surgical procedures may put this capsular blood supply at risk. We hypothesized that a hypovascular area is present in the capsule. The purpose of the present study was to describe the vascular anatomy of the human glenohumeral capsule and ligaments and its relevance to surgical treatment of the shoulder.

METHODS

In twenty-four fresh adult cadaveric shoulders, the axillary artery proximal to the thoracoacromial branch and the suprascapular artery were injected with India ink. The specimens were sectioned and then cleared with a modified Spalteholz technique.

RESULTS

The glenohumeral capsule demonstrates consistent arterial contributions from the anterior circumflex, posterior circumflex, circumflex scapular, and suprascapular arteries. The arterial supply is centripetal in nature. The contributing vessels enter the capsule both laterally and medially and arborize toward the middle of the capsule. The rotator cuff provides additional blood supply to the capsule through perforating vessels. The dominant capsular vessels run horizontally and form intracapsular anastomoses via vertical branches. The anterior and posterior bands of the inferior glenohumeral ligament complex are vascularized by adjacent parallel vessels. In five of twelve specimens, a hypovascular zone was located near the humeral insertion of the anterior aspect of the capsule. In these five specimens, there was an associated hypovascular zone in the underlying capsule.

CONCLUSION

The glenohumeral capsule is a well-vascularized structure with direct predictable contributions from four named arteries. These arteries send branches that enter the capsule superficially and from the periphery. These dominant vessels run horizontally toward the midcapsule and to deeper layers of the capsule. Vessels originating from the rotator cuff provide additional blood supply to the capsule.

Complications of thermal energy in knee surgery--Part I

The use of thermal energy in knee surgery has many potentially exciting and useful applications. There is a growing body of literature that demonstrates the effects of these energy probes on different types of tissue. When contemplating the use of these surgical interventions in patients, it is important to recognize the potential limitations and complications that may arise.

Thermal energy in arthroscopic surgery of the wrist

Thermal energy in arthroscopic surgery needs further follow-up evaluation to clarify the potential benefits, specifically with respect to thermal shrinkage. Although the initial findings are promising, the long-term results need to be compared with other accepted standards of management. Preliminary findings seem to show that the addition of these surgical instruments and expanding operative techniques have definite roles in arthroscopic wrist surgery, as demonstrated through meticulous synovectomies and precise tissue debridement, along with the possible thermal shrinkage potential.

Sensorimotor deficits contributing to glenohumeral instability

The conventional perspective has been that capsuloligamentous structures act as a mechanical restraint to humeral translation at the shoulder. Although this is true, the capsuloligamentous structures also have a sensorimotor influence on the musculoskeletal system, providing stability at the shoulder. The purpose of the current study was to discuss the sensorimotor role that the capsuloligamentous structures play in providing stability, how these mechanisms are disrupted with glenohumeral instability, and how surgical intervention restores such mechanisms. Proprioceptive information transmitted from the mechanoreceptors embedded within the capsuloligamentous structures influence the coordinated motor patterns, reflex activity, and joint stiffness to provide enhanced joint stability. The capsuloligamentous injury that occurs with shoulder instability not only affects mechanical restraint, but also alters this proprioceptive input to the central nervous system. As a result of these deficits in proprioception, alterations in reflex activity and motor programs as evident by muscle firing pattern alterations manifest. Although the main goal of surgical intervention is to restore the mechanical restraint that is lost with joint dislocation or subluxation, surgical intervention whether through open, arthroscopic, or thermal techniques seem to restore the proprioceptive deficits that exist after joint injury.

Rehabilitation following thermal-assisted capsular shrinkage of the glenohumeral joint: current concepts

Glenohumeral joint instability is a common pathology observed in the orthopedic and sports medicine settings. Overhead athletes often exhibit a certain degree of acquired laxity that can lead to various pathologies. Unfavorable results often observed with traditional open procedures to correct instability in the overhead athlete have led to the development of arthroscopic thermal-assisted capsular shrinkage (TACS). TACS is not commonly used as an isolated procedure in overhead athletes; various procedures are often performed concomitantly. The overall outcome greatly depends on a postoperative rehabilitation program that must be assessed and adjusted frequently based on several factors. Knowledge of the basic science of TACS as well as emphasis on dynamic stabilization, proprioception, and neuromuscular control are vital to the rehabilitation program for overhead athletes. The purpose of this paper is to discuss the basic science and clinical application of thermal-assisted capsular shrinkage of the glenohumeral joint as well as the postoperative rehabilitation for the overhead athlete and the patient with congenital laxity and related multidirectional instability.

The use of thermal capsulorrhaphy in the treatment of multidirectional instability

The purpose of this study is to report on our experience with thermal capsulorrhaphy in the treatment of multidirectional instability of the shoulder. Thirty-three consecutive patients (33 shoulders) with multidirectional instability were treated with arthroscopic thermal capsulorrhaphy. Twelve patients had a history of traumatic dislocation. Three patients had been previously treated with open inferior capsular shift procedures. At a mean follow-up of 36 months (range, 24-40 months), results were available for 30 patients. On the basis of the UCLA rating scale, out of a possible 35 points, the mean preoperative score was 16.7 points and postoperatively it was 30.1 points, with 3 excellent, 20 good, and 7 poor results. Twenty-three patients (76%) were returned to full activity. In our experience the majority of patients with multidirectional instability were able to return to their previous occupations in the armed forces following thermal capsulorrhaphy. More information further defining the biomechanical pathology of capsular laxity and the specific role of electrothermal shrinkage in treating shoulder instability is needed.

Acute biomechanical and histological effects of intradiscal electrothermal therapy on human lumbar discs

STUDY DESIGN

Human cadaver lumbar spines were used to assess the acute effects of intradiscal electrothermal therapy in vitro.

OBJECTIVE

To determine whether intradiscal electrothermal therapy produces acute changes in disc histology and motion segment stability.

SUMMARY OF BACKGROUND DATA

Intradiscal electrothermal therapy has been introduced as an alternative for the treatment of discogenic low back pain. Several hypothesized mechanisms for the effect of intradiscal electrothermal therapy have been suggested including shrinkage of the nucleus or sealing of the anulus fibrosus by contraction of collagen fibers, and thermal ablation of sensitive nerve fibers in the outer anulus.

METHODS

Intradiscal electrothermal therapy was performed with the Spinecath by Oratec on 19 fresh, frozen human lumbar cadaver specimens. In a separate study, eight specimens were tested biomechanically and instrumented to map the thermal distribution, whereas five specimens were tested only biomechanically, both before and after intradiscal electrothermal therapy. Six additional specimens were heated with intradiscal electrothermal therapy, and the resulting canal was backfilled with a silicone rubber compound to allow colocalization of the catheter and anular architecture.

RESULTS

A consistent pattern of increased motion and decreased stiffness was observed. For the specimens in which only biomechanical measurements were taken, a 10% increase in the motion, on the average, at 5 Nm torque was observed after intradiscal electrothermal therapy. No apparent alteration of the anular architecture was observed around the catheter site in the intradiscal electrothermal therapy-treated discs.

CONCLUSION

The data from this study suggest that the temperatures developed during intradiscal electrothermal therapy are insufficient to alter collagen architecture or stiffen the treated motion segment acutely.

Thermal capsular shrinkage: Basic science and clinical applications

Recently, the use of thermal energy to shrink the redundant glenohumeral joint capsule in patients with instability has generated a great deal of interest. Proponents assert that the procedure avoids the need for an open stabilization and it may be used as an adjunct to an open or arthroscopic capsulolabral repair. The use of nonablative thermal energy to shrink soft-tissue collagen appears to induce ultra-structural and mechanical changes at or above 60 degrees C. The microscopic changes reflect the unwinding of the collagen triple helix and loss of the fiber orientation. The fibrils contract into a shortened state and reactive fibroblasts have been shown to grow into this treated area and synthesize the collagen matrix. The biomechanical properties of the tissue do not appear to be detrimentally altered if shrinkage is limited to less than 15% and if ablation or excess focal treatment is avoided. The endpoint of optimal shrinkage is not known and clinical estimations of tissue changes and volumetric reduction are used as guides to treatment. The first clinical follow-up study was only recently published in the peer-reviewed literature and prior preliminary reports were optimistic regarding the use of thermal energy for the treatment of glenohumeral instability. Thermal capsular shrinkage has been used as an adjunct to a capsulolabral repair, as well as an isolated treatment for the disorders of internal impingement and multidirectional instability. Additional evaluation is necessary to determine the optimal quantity of energy needed for tissue shrinkage without inadvertent tissue destruction. The long-term clinical effect, mechanical properties, and durability of the newly produced collagen need to be analyzed further. The basic science and clinical applications of this newly applied technology are reviewed in this article.

The healing effects on the biomechanical properties of joint capsular tissue treated with Ho:YAG laser: An in vivo rabbit study

PURPOSE

The objective of this study was to evaluate the healing response, after thermal treatment with a Ho:YAG laser, on the biomechanical properties of capsular soft tissue.

TYPE OF STUDY

Before and after trial.

METHODS

Forty-five New Zealand white rabbits were used in this study. A medial peripatellar retinacular thermal capsuloplasty using a Ho:YAG laser and a lateral peripatellar retinacular release was performed on 1 knee of each rabbit. The contralateral knee served as a control and had a lateral release of the retinaculum only. The temperature of the medial retinaculum was maintained at 55 degrees C +/- 5 degrees C during treatment. The medial peripatellar retinaculum was evaluated at 0, 6, and 12 weeks postoperatively. Tensile testing of the medial retinaculum and a biomechanical assessment evaluating the structural and material properties were performed.

RESULTS

The ultimate load (force) of the medial retinaculum was 70%, 56%, and 84% of control at 0, 6, and 12 weeks, respectively, after the procedure. The stiffness (force/deformation) of the medial retinaculum was 83% of control at 0 weeks, 54% at 6 weeks, and 85% at 12 weeks. The ultimate stress (force/area) of the medial retinaculum also showed a significant reduction at 0 and 6 weeks postoperatively, 63% and 62% of control, respectively. By 12 weeks, the ultimate stress was 83% of control.

CONCLUSIONS

Thermal treatment of the medial retinaculum with a Ho:YAG laser results in soft tissue with significantly diminished biomechanical properties after treatment. The results of this study suggest that a 12-week period of minimal stress on the capsular tissues should follow a thermal capsuloplasty procedure.

Temperature dependence of thermal damage to the sclera: exploring the heat tolerance of the sclera for transscleral thermotherapy

Thermal damage to the human sclera in relation to temperature and duration of exposure was studied in order to determine the heat tolerance of the sclera with respect to transscleral thermotherapy of choroidal melanoma. Samples of human sclera were submerged in saline for 10 sec to 10 min at temperatures of 37-100 degrees C. The effects of heat on the shape, weight and size of the samples were studied. Thermal damage of scleral collagen was examined by polarized light microscopy (LM) and electron microscopy (EM). The sclera was embedded in epoxy resin and stained with toluidine blue for LM and with uranyl acetate and lead citrate for EM. Thermal damage of scleral collagen on polarized LM was graded on a five point scale. Scleral damage was visible on macroscopic examination and on LM and EM in sclera heated at 65 degrees C for 20 sec or longer, at 70 degrees C for 10 sec or longer, and at higher temperatures. A sigmoidal function was used to define the relation between temperature and changes in diameter, thickness, and weight of scleral samples. Using fitted functions, the threshold temperature for thermal damage was estimated to be 59-61 degrees C when samples were heated for 10 min, 62-63 degrees C when heated for 1 min, and 66-67 degrees C when heated for 10 sec; the threshold exposure time at 60 degrees C was estimated to be 7-12 min. These results indicate a temperature of 60 degrees C for 1 min is well tolerated by human donor sclera; information of in vivo studies is required to validate whether this setting can be used in transscleral thermotherapy (TSTT) for choroidal melanoma.

Thermally induced shrinkage of joint capsule

Thermal shrinkage of collagen currently is being used in orthopaedic surgery to treat ligamentous laxity. Understanding the kinetics of collagen shrinkage is key to revealing the events that take place during application of thermal energy. To elucidate the thermokinetic properties of collagen, punch biopsies of bovine joint capsule were immersed in a heated saline bath at temperatures between 20 degrees and 90 degrees C for periods up to 60 minutes. The resulting tissue thermal shrinkage was measured by the change in the cross-sectional area of the specimens. Only a small amount of shrinkage occurred at temperatures below 63 degrees C, and increasing amounts and rates of shrinkage were seen at temperatures between 63 degrees and 72 degrees C. The denaturation kinetics of bovine knee collagen, which could be described by a first order reaction rate, had an activation energy of 2.3 x 10(5) kJ/mol.

The effect of monopolar radiofrequency treatment pattern on joint capsular healing. In vitro and in vivo studies using an ovine model

The purpose of this study was to compare joint capsular healing after two delivery patterns of monopolar radiofrequency energy: 1) uniform treatment of the joint capsule (paintbrush pattern) and 2) multiple single linear passes (grid pattern). First, an in vitro study was performed to compare the percent shrinkage of these two treatment patterns using the femoropatellar joints (stifles) of six sheep. Monopolar radiofrequency energy (settings, 70 degrees C/15W) was applied to the lateral joint capsule; the treated area was approximately 10 x 10 mm. There was no significant difference in shrinkage between the grid (27% +/- 8.7%) and paintbrush (29% +/- 7.9%) patterns. In the in vivo study, stifles of 24 sheep were randomly assigned to the paintbrush or the grid pattern groups and treatment was performed arthroscopically. Sheep were sacrificed immediately after surgery, or at 2, 6, or 12 weeks after surgery. At 6 weeks after surgery, confocal microscopy demonstrated that treated areas had almost completely repaired in the grid group; some nonviable areas were still present in the paintbrush group. Mechanical testing at 6 weeks indicated that joint capsule in the grid group had better mechanical properties than capsule in the paintbrush group. This study revealed that radiofrequency treatment of joint capsule in a grid pattern allowed faster healing than tissue treated in a paintbrush pattern.

Thermal modification of connective tissues: basic science considerations and clinical implications

Thermal modification (shrinkage) of capsular connective tissue has gained increasing popularity as an adjunctive or even a primary procedure in the arthroscopic treatment of shoulder instability. Although the physical effects of heat on collagenous tissues are well known, the long-term biologic fate of these shrunken tissues is still a matter of debate. The temperatures required to alter the molecular bonding of collagen and thus cause tissue shrinkage (65 degrees C to 70 degrees C) are also known to destroy cellular viability. Therefore, thermally modified tissues are devitalized and must undergo a biologic remodeling process. During this remodeling, the mechanical properties of the treated tissues are altered (decreased stiffness) and can be at risk for elongation if the postoperative rehabilitation regimen is too aggressive. Although anecdotal reports suggest that thermal capsular shrinkage does have a beneficial effect, the exact mechanism responsible for this clinical improvement has yet to be fully defined. The reported improvement could be due to the maintenance of initial capsular shrinkage, secondary fibroplasia and resultant thickening of the joint capsule, a loss of afferent sensory stimulation due to the destruction of sensory receptors, or a combination of all three. The clinical role for thermal modification of connective tissues has not yet been defined, but it appears that it may prove most useful as a stimulant for inducing a biologic repair response.

Arthroscopic management of glenohumeral instability

There has been substantial development of techniques for performing arthroscopic surgery of the shoulder over the past 20 years. A multitude of arthroscopic techniques have been developed in an attempt to manage the unstable glenohumeral joint while decreasing surgical morbidity. The results obtained with arthroscopic stabilization have been widely variable. This review will examine the current status of arthroscopic management of glenohumeral instability. The techniques and results of arthroscopic stabilization for primary anterior glenohumeral instability, recurrent anterior instability, and multidirectional instability will be discussed. A brief discussion on thermal capsulorrhaphy is included.

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.

The biologic response to laser thermal modification in an in vivo sheep model

The purpose of this study was to evaluate the effect of nonablative laser energy on mechanical, histologic, ultrastructural, and biochemical properties of joint capsular tissue in an in vivo sheep model. Femoropatellar joint capsule was treated with the holmium:yttrium-aluminum-garnet laser via an arthroscope, and tissues were harvested immediately after surgery, or at 3, 7, 14, 30, 60, 90, and 180 days after surgery (n = 8/group). Laser treatment caused significant decreases in tissue stiffness from 0 to 7 days after surgery, then stiffness gradually increased after 14 days. Tissue strength was lowest 3 days after laser treatment. Histologic examination revealed immediate collagen hyalinization and cell necrosis, followed by active cellular response characterized by extensive fibroblast migration and capillary sprouting. Tissue appeared to be normal histologically 60 days after surgery; however, collagen fibrils remained uniformly small. This study showed an active tissue response secondary to thermal modification with concomitant recovery of mechanical properties by 30 days after surgery. Whether the shrinkage or joint stability was maintained with time remains to be evaluated. To clarify the advantages and disadvantages of this technique, a carefully controlled clinical trial with long term followup should be performed.

Management of chronic discogenic low back pain with a thermal intradiscal catheter. A preliminary report

STUDY DESIGN

A prospective nonrandomized clinical trial.

OBJECTIVE

To determine the outcome in a group of patients with chronic, function-limiting low back pain who met the criteria for interbody fusion surgery, but were instead treated with an intradiscal thermal catheter (SpineCath, Oratec Interventions, Inc., Menlo Park, CA).

SUMMARY OF BACKGROUND DATA

This study represents the first reported trial of treatment for chronic discogenic low back pain with a novel thermal intradiscal catheter.

METHODS

The authors evaluated 25 consecutive patients. The minimum duration of nonoperative care with the authors was 6 months. The visual analog pain scores, sitting tolerance times, and SF-36 summary scores were tabulated.

RESULTS

The mean follow-up period was 7 months, and the mean duration of symptoms 58.5 months. Of the 25 patients, 20 (80%) reported a reduction of at least 2 points in visual analog pain scores, and 18 (72%) reported an improvement in sitting tolerance as well as reduction or discontinuance of analgesic medication. Visual analog pain scores improved by a mean reduction of 3.74, a 51% change (P = 0.0001). On the SF-36 physical function subscale, 72% of the patients improved by a mean increase of 15 points (P = 0.001), a mean change of 38%, and by a mean increase of 14 points on the bodily pain subscale (P = 0.004), a mean change of 48%.

CONCLUSIONS

A statistically significant improvement in functional outcome was obtained in patients with chronic discogenic low back pain treated thermally by the SpineCath.

Monopolar radiofrequency energy effects on joint capsular tissue: potential treatment for joint instability. An in vivo mechanical, morphological, and biochemical study using an ovine model

The purpose of this study was to evaluate the thermal effect of monopolar radiofrequency energy, a potential treatment means for joint instability, on the mechanical, morphologic, and biochemical properties of joint capsular tissue in an in vivo ovine model. The energy was applied arthroscopically to the synovial surface of the femoropatellar joint capsule of 24 sheep. The sheep were sacrificed at 0, 2, 6, and 12 weeks after surgery (6 per group). Monopolar radiofrequency energy initially caused a significant decrease in tissue stiffness and an increase in tissue relaxation properties, followed by gradual improvement in the tissue's mechanical properties by 6 weeks after surgery. Microscopic examination illustrated that radiofrequency energy initially caused collagen hyalinization and cell necrosis, followed by active tissue repair. Biochemical analysis revealed that treated collagen was significantly more trypsin-susceptibile than untreated collagen at 0 and 2 weeks after surgery, indicating early collagen denaturation. This study demonstrated that this treatment initially caused a significantly deleterious effect on the mechanical properties of the joint capsule, which was associated with partial denaturation of joint capsular tissue. This was followed by gradual improvement of the mechanical, morphologic, and biochemical properties of the tissue over time.

Histologic evaluation of the glenohumeral joint capsule after the laser-assisted capsular shift procedure for glenohumeral instability

Glenohumeral joint capsule obtained from 42 patients who had undergone an arthroscopic laser-assisted capsular shift procedure was evaluated histologically. A total of 53 samples from the anterior inferior glenohumeral ligament of the joint capsule were collected before and at various times after the procedure (range, 0 to 38 months). Despite glenohumeral instability, joint capsule of the patients before the procedure showed no significant histologic lesions. Laser treatment significantly altered the histologic properties of the tissue as evidenced by hyalinization of collagen and necrotic cells (time 0). Tissues sampled during the short-term period (3 to 6 months) after the procedure demonstrated fibrous connective tissue with reactive cells and vasculature. Collagen and cell morphology returned to normal in the middle- to long-term period (7 to 38 months) after the procedure, while the number of fibroblasts remained elevated. Joint capsule collected from the shoulders of six patients who experienced stiffness after the procedure showed persistent synovial, cellular, and vascular reaction even after 1 year postoperatively, the cause of which is unclear. This study revealed histologic evidence of robust tissue healing and maturation after thermal treatment by the laser-assisted capsular shift procedure, although mechanical and biochemical characterization of the tissue was not evaluated. Correlation with clinical follow-up must be performed to further clarify the advantages and disadvantages of this procedure.

The thermal effect of monopolar radiofrequency energy on the properties of joint capsule. An in vivo histologic study using a sheep model

The purpose of this in vivo study was to analyze the short-term tissue response of joint capsule to monopolar radiofrequency energy and to compare the effects of five power settings at 65 degrees C on heat distribution in joint capsule. In 12 mature Hampshire sheep, the medial and lateral aspects of both stifles were treated with monopolar radiofrequency energy under arthroscopic control in a single uniform pass to the synovial surface. The radiofrequency generator power settings were 0, 10, 15, 20, 25, and 30 watts (N = 8/group). The electrode tip temperature was 65 degrees C. Histologic analysis at 7 days after surgery revealed thermal damage of capsule at all radiofrequency power settings. The lesion's cross-sectional area, depth, vascularity, and inflammation were commensurate with radiofrequency power. Tissue damage was indicated by variable inflammatory cell infiltration, fusion of collagen, pyknosis of fibroblasts, myonecrosis, and vascular thrombosis, whereas synovial hyperplasia, fibroblast proliferation, and rowing of sarcolemmal nuclei demonstrated regenerative processes. This study revealed that radiofrequency power settings and heat loss through lavage solution play a significant role in heat distribution and morphologic alterations in joint capsule after arthroscopic application of monopolar radiofrequency energy.