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

Outcomes of Holmium Laser, Cryoablation, and Budesonide Inhalation for Treating Severe Central Airway Stenosis in Infants

BACKGROUND

Central airway stenosis (CAS) in infants is characterized by dysphonia, dyspnea, cyanosis, repeated apnea, and infection. This case series study aimed to evaluate the safety and efficacy of holmium laser, cryoablation and budesonide inhalation in treating infants with severe CAS.

METHODS

This retrospective study reviewed medical records data of 28 infants with severe CAS who underwent holmium laser treatment with cryoablation and/or balloon dilatation and budesonide inhalation therapy at Shanghai Children's Medical Center between June 2014 and May 2020. Outcomes were defined as treatment success when the stenotic area was <25% for the normal age group with stable reopening diameter at one-year follow-up.

RESULTS

Patients' mean age was 12.8 ± 8.8 months and 17 (60%) were male. Sixteen cases had web-like stenosis and 12 had scar contracture stenosis. Among 16 patients with web-like stenosis, 8 (50%) underwent balloon dilation with cryotherapy and 8 (50%) underwent balloon dilation only; treatment success was achieved in 10 (62.5%) cases and after revised treatments in 5 (31.25%) cases. Among 12 patients with scar contracture stenosis, 6 (50%) underwent balloon dilation with cryotherapy, 4 (33.3%) underwent cryotherapy and 2 (16.7%) underwent balloon dilation only; treatment success was achieved in 3 (23.1%) cases and after 1-4 revised treatments in 8 (61.5%) cases. Symptoms of the 2 unsuccessful (7.1%) cases were relieved after tracheal stent insertion. Neither severe adverse events nor complications were observed during follow-up.

CONCLUSION

Holmium laser with cryoablation followed by budesonide inhalation therapy safely and effectively cleans stenotic tissues and maintains airway reopening. Balloon dilation after holmium laser is recommended for treating web-like stenosis.

History of surgical stabilization for posterior shoulder instability

Background

Posterior shoulder instability is common in young athletes. Although the posterior shoulder instability literature is less robust than its anterior counterpart, many surgical procedures have been developed and refined over the past several centuries to address this condition.

Materials and methods

This article represents a retrospective historical analysis of the most common procedures used to treat posterior shoulder instability after sports injuries. A systematic approach to obtain published information on posterior shoulder instability was performed using the PubMed/MEDLINE database, manual searches of high–impact factor journals, and conference proceedings and books.

Results

A wide array of both soft tissue–based and bone-based procedures have been developed for the treatment of posterior shoulder instability, ranging from procedures addressing the soft tissue alone (capsular shift, labral repair, reverse Putti-Platt) or bone-based procedures (glenoid and/or humeral osteotomy, glenoid bone block) to a combination of both bone and soft-tissue procedures (modified McLaughlin procedure).

Discussion

Over the past several centuries, a number of procedures have been developed to address posterior shoulder instability, particularly as this pathology has become better understood. Future work is required not only to continue to advance these procedures but also to assess their outcomes. An understanding of the historical perspective of posterior shoulder instability procedures is essential as surgeons continue to modify these procedures in an effort to best help their patients.

Thermal shrinkage for shoulder instability

Thermal capsular shrinkage was popular for the treatment of shoulder instability, despite a paucity of outcomes data in the literature defining the indications for this procedure or supporting its long-term efficacy. The purpose of this study was to perform a clinical evaluation of radiofrequency thermal capsular shrinkage for the treatment of shoulder instability, with a minimum 2-year follow-up. From 1999 to 2001, 101 consecutive patients with mild to moderate shoulder instability underwent shoulder stabilization surgery with thermal capsular shrinkage using a monopolar radiofrequency device. Follow-up included a subjective outcome questionnaire, discussion of pain, instability, and activity level. Mean follow-up was 3.3 years (range 2.0-4.7 years). The thermal capsular shrinkage procedure failed due to instability and/or pain in 31% of shoulders at a mean time of 39 months. In patients with unidirectional anterior instability and those with concomitant labral repair, the procedure proved effective. Patients with multidirectional instability had moderate success. In contrast, four of five patients with isolated posterior instability failed. Thermal capsular shrinkage has been advocated for the treatment of shoulder instability, particularly mild to moderate capsular laxity. The ease of the procedure makes it attractive. However, our retrospective review revealed an overall failure rate of 31% in 80 patients with 2-year minimum follow-up. This mid- to long-term cohort study adds to the literature lacking support for thermal capsulorrhaphy in general, particularly posterior instability.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s11420-010-9187-7) contains supplementary material, which is available to authorized users.

Hip instability

Understanding of the etiology and pathology of hip instability has increased in recent years as new information has emerged regarding the disease processes of the hip. Hip instability, heretofore considered uncommon in clinical practice, is increasingly recognized as a pathologic entity. Instability may be classified as traumatic or atraumatic, and diagnosis is made based on patient history, physical examination, and imaging studies. Plain radiography, MRI, MRI arthrography, and hip instability tests (eg, posterior impingement, dial) can be used to confirm the presence of instability. Nonsurgical management options include physical therapy and protected weight bearing. Surgical intervention, whether arthroscopic or open, is required for large acetabular fractures and refractory instability. Knowledge of the etiology and evolving research of hip instability is essential to understand the spectrum of hip disease.

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.

Treatment of ligament laxity by electrothermal shrinkage or surgical plication: a morphologic and mechanical comparison

Capsular plication or thermal shrinkage can be used to enhance surgical joint stabilization. We compared mechanical or morphologic properties of the medial collateral ligament of the rabbit knee treated by either bipolar radiofrequency electrothermal shrinkage or surgical plication. After 12 weeks, the medial collateral ligaments were procured from treated and contralateral knees to undergo viscoelastic (creep) testing, quantitative transmission electron microscopy, and immunohistochemistry. Creep strain in thermal (1.85% +/- 0.32%) and plicated (1.92% +/- 0.36%) ligaments was almost twice that of the control group (1.04% +/- 0.15%), although there was no difference between treatment modalities. The morphologic parameters of all 3 groups were significantly different (P < .001). The thermal ligaments demonstrated predominantly small fibrils, whereas the plicated group displayed an intermediate distribution of heterogeneous fibrils, suggesting a different pattern of remodeling. Viscoelastic properties are similar after thermal shrinkage or plication, though inferior to those of intact ligaments.

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.

A multi-centre randomized controlled trial comparing electrothermal arthroscopic capsulorrhaphy versus open inferior capsular shift for patients with shoulder instability: protocol implementation and interim performance: lessons learned from conducting a multi-centre RCT [ISRCTN68224911; NCT00251160]

BACKGROUND

The shoulder is the most frequently dislocated joint in the body. Multiple causes and pathologies account for the various types of shoulder instability. Multi-directional instability (MDI) and multi-directional laxity with antero-inferior instability (MDL-AII) are similar in pathology, less common and more difficult to treat. These instabilities are caused by ligamentous capsular redundancy. When non-operative management fails for these patients, quality of life is significantly impaired and surgical treatment is required to tighten the ligaments and joint capsule. The current reference (gold) standard treatment for MDI/MDL-AII is an open inferior capsular shift (ICS) surgical procedure. An alternative treatment involves arthroscopic thermal shrinkage of redundant capsular tissue to tighten the joint. However, there is a lack of scientific evidence to support the use of this technique called, electrothermal arthroscopic capsulorrhaphy (ETAC). This trial will compare the effectiveness of ETAC to open ICS in patients with MDI and MDL-AII, using patient-based quality of life outcome assessments.

METHODS

This study is a multi-centre randomized clinical trial with a calculated sample size of 58 patients (p = 0.05, 80% power). Eligible patients are clinically diagnosed with MDI or MDL-AII and have failed standardized non-operative management. A diagnostic shoulder arthroscopy is performed to confirm eligibility, followed by intra-operative randomization to the ETAC or ICS surgical procedure. The primary outcome is the disease-specific quality of life questionnaire (Western Ontario Shoulder Instability Index), measured at baseline, 3, 6, 12 and 24 months. Secondary outcomes include shoulder-specific measures (American Shoulder and Elbow Surgeons Score and Constant Score). Other outcomes include recurrent instability, complications and operative time. The outcome measurements will be compared on an intention-to-treat basis, using two-sample independent t-tests to assess statistical significance. A Generalized Estimated Equations (GEE) analysis will determine whether there is an effect over time.

DISCUSSION

This ongoing trial has encountered unexpected operational and practical issues, including slow patient enrollment due to high intra-operative exclusion rates. However, the authors have a greater understanding of multi-directional laxity in the shoulder and anticipate the results of this trial will provide the medical community with the best scientific clinical evidence on the efficacy of ETAC compared to open ICS.

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.

Radiofrequency energy effects on the mechanical properties of tendon and capsule

PURPOSE

To compare the mechanical properties of tendon and capsule after radiofrequency (RF) energy treatment.

TYPE OF STUDY

An in vitro study.

METHODS

RF energy was applied to ovine extensor tendon and human cadaveric glenohumeral capsule varying in the treatment wattage and time (5, 10, or 20 W for 10 or 30 seconds). The associated tissue length changes and dynamic and failure properties of the tissues were investigated using a materials testing machine.

RESULTS

Length changes in the 2 tissues were comparable across the range of treatment settings used with both increases in the treatment wattage and time increasing the amount of tissue shrinkage observed. However, tendon showed greater changes in its mechanical properties after RF treatment, with significant decreases in the failure properties of the tissue as well as the dynamic and static stiffness.

CONCLUSIONS

RF treatment shrinks collagenous tissues in a progressive manner correlated to the treatment wattage. However, it has different effects on the mechanical properties of tendon and capsule with the properties of tendinous tissues dramatically reduced.

CLINICAL RELEVANCE

RF treatment has been shown to effect the mechanical properties of different collagenous tissues differently; therefore, it must be used specifically and with caution around areas of mixed tissue origin.

Suture plication, thermal shrinkage, and sclerosing agents: effects on rat patellar tendon length and biomechanical strength

BACKGROUND

Shortening or tightening of dense, collagenous tissues is often desirable in the treatment of laxity.

PURPOSE

To compare the effect of stress-protection suture, radiofrequency thermal shrinkage combined with stress-protection suture, and a 5% sodium morrhuate sclerosing injection on the length and biomechanical strength of the rat patellar tendon.

HYPOTHESIS

Sclerosing agents will increase tendon mechanical strength. Thermal shrinkage combined with stress-protection suture and stress-protection suture only will cause a short-term decrease in tendon strength. All 3 methods will produce equivalent shortening of the tendon.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty-six female retired breeder rats were split into 4 groups, each receiving 1 of the 3 aforementioned treatments plus a control group that received a saline injection. After 4 weeks' survival, the length and biomechanical properties of the patellar tendons were measured and compared to the contralateral untreated tendon.

RESULTS

Rats treated with stress-protection suture had shorter tendons. Radiofrequency thermal shrinkage combined with stress-protection suture yielded tendons that were both shorter and stronger than were the untreated contralateral tendons. The sodium morrhuate-injected tendons were stronger whereas the saline-treated tendons were weaker than were their respective untreated contralateral tendons.

CONCLUSION

Surgical stress-protection suture without radiofrequency shrinkage is most effective at shortening the length of the rat patellar tendon, whereas radiofrequency thermal shrinkage combined with stress-protection suture as well as sodium morrhuate are effective at increasing the strength of rat patellar tendons.

CLINICAL RELEVANCE

Judicious use of thermal shrinkage in combination with stress protection may improve ligament strength and decrease laxity.

Revision surgery for failed thermal capsulorrhaphy

BACKGROUND

With the failure of thermal capsulorrhaphy for shoulder instability, there have been concerns with capsular thinning and capsular necrosis affecting revision surgery.

PURPOSE

To report the findings at revision surgery for failed thermal capsulorrhaphy and to evaluate the technical effects on subsequent revision capsular plication.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fourteen patients underwent arthroscopic evaluation and open reconstruction for a failed thermal capsulorrhaphy. The cause of the failure, the quality of the capsule, and the ability to suture the capsule were recorded. The patients were evaluated at follow-up for failure, which was defined as recurrent subluxations or dislocations.

RESULTS

The origin of the instability was traumatic (n = 6) or atraumatic (n = 8). At revision surgery in the traumatic group, 4 patients sustained failure of the Bankart repair with capsular laxity, and the others experienced capsular laxity alone. In the atraumatic group, all patients experienced capsular laxity as the cause of failure. Of the 14 patients, the capsule quality was judged to be thin in 5 patients and ablated in 1 patient. A glenoid-based capsular shift could be accomplished in all 14 patients. At follow-up (mean, 35.4 months; range, 22 to 48 months), 1 patient underwent revision surgery and 1 patient had a subluxation, resulting in a failure rate of 14%.

CONCLUSIONS

Recurrent capsular laxity after failed thermal capsular shrinkage is common and frequently associated with capsular thinning. In most instances, the capsule quality does not appear to technically affect the revision procedure.

Treatment of glenohumeral subluxation using electrothermal capsulorrhaphy

PURPOSE

The purpose of this study was to review the results of a relatively homogenous group of patients with glenohumeral subluxation without labral pathology who were treated with an electrothermal capsulorrhaphy procedure.

TYPE OF STUDY

Case series without controls.

METHODS

From 1997 to 1998, 42 patients underwent electrothermal capsulorrhaphy using a monopolar radiofrequency probe (Oratec Interventions, Menlo Park, CA). Patients with prior capsular repairs, labral pathology that required repair, or capsular avulsion injuries were excluded from the study. Thirty-one patients met the inclusion criteria. Patients had a minimum of 2 years of follow-up (mean, 25 months), and a mean age of 25 years (range, 16 to 38 years). All of the patients had previously failed conservative treatment. There were 25 patients with unidirectional anterior instability, 2 patients with unidirectional inferior instability, 1 patient with unidirectional posterior instability, and 3 patients with multidirectional instability. The patients were assessed using a modified American Shoulder and Elbow Surgeons (ASES) score that examined pain (30 points), function (60 points), and patient satisfaction (10 points). In addition, subjective stability was assessed using a 10-point scale.

RESULTS

The average modified ASES score increased to 88 points from 56 preoperatively (P < .01). The average subjective stability scale increased to 8.5 from 4.4 preoperatively (P < .01). Nineteen patients (61%) had an excellent result, 4 (13%) had a good result, 5 (16%) had a fair result, and 3 (10%) had a poor result; 22 of 26 patients who participated in sports were able to return to their preinjury level of play. The subset of patients with isolated anterior instability had results similar to the overall group. There were no instances of axillary neuritis or other neurologic injury.

CONCLUSIONS

In carefully selected patients with shoulder instability, including unidirectional anterior instability without associated labral pathology, electrothermal capsulorrhaphy was effective and had few complications.

LEVEL OF EVIDENCE

Level IV, case series without controls.

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.

Tensile strength of ligaments after thermal shrinkage depending on time and immobilization: in vivo study in the rabbit

The effects of immobilization on healing collagenous tissue treated with thermal shrinkage are investigated in an in vivo rabbit model. Thermal shrinkage was performed on 45 of 50 medial collateral ligaments in 25 mature New Zealand rabbit knees. In half of the knees, the joints were immobilized. Animals were killed at 0, 3, 6, and 9 weeks postoperatively. Failure loads of ligaments were determined, and morphologic changes were evaluated by electron microscopy. The failure load of shrunken ligaments was significantly lower than that of the intact ligaments on the day of operation (P<.05). Shrunken ligaments reached their highest failure loads in the third week within the first 9 weeks. The immobilized ligaments remained weaker than the mobile group, but this difference was statistically significant only in the ninth week (P<.05). Immobilization seems to have negative effects on the healing ligament. Ideal timing for remobilization is still controversial, and abandoning immobilization protocols for longer than 3 weeks should be considered.

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.

Ex vivo investigation of the use of hydrothermal energy to induce chondrocyte necrosis in articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of horses

OBJECTIVE

To evaluate the use of hydrothermal ablation of articular cartilage for arthrodesis in horses through investigation of the effects of joint lavage with physiologic saline (0.9% NaCI) solution (80 degrees C) for various treatment times on chondrocyte viability in the articular cartilage of the metacarpophalangeal and metatarsophalangeal joints of cadaveric horse limbs. Sample Population-7 pairs of metacarpophalangeal and 8 pairs of metatarsophalangeal joints from 8 Thoroughbreds.

PROCEDURE

The horses were euthanatized for reasons unrelated to musculoskeletal disease. On a random basis, 1 joint of each pair underwent intra-articular lavage for 5, 10, or 15 minutes with heated saline solution (80 degrees C); the other joint underwent sham treatment of similar duration with saline solution at 22 degrees C (control). Cartilage samples from the distal articular surface of metacarpus III (or metatarsus III), the proximal surface of the proximal phalanx, and the lateral and medial proximal sesamoid bones were assessed for chondrocyte viability via confocal microscopy and viability staining following enzymatic digestion.

RESULTS

Compared with the control joints, findings of both viability assays indicated that the percentage of sites containing viable chondrocytes in heat-treated joints was decreased. Treatment hazard ratios of 0.048 (confocal microscopy) and 0.2 (digestion assay) were estimated. Histologically, periarticular soft tissues had minimal detrimental effects after heat treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Ex vivo intra-articular lavage with saline solution at 80 degrees C resulted in the death of almost all articular chondrocytes in the joint. This technique may be a satisfactory method for extensive cartilage ablation when performing arthrodesis by minimally invasive techniques.

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.

Neuronal regeneration after application of radiofrequency energy to collagenous tissue is affected by limb immobilization: an in vivo animal study

Despite widespread use of radiofrequency (RF)-shrinkage, there have been no studies on the influence of RF-energy on neural elements of collagenous tissue. The purpose of this study was to examine the effect of RF-shrinkage on neural structures of capsuloligamentous tissue and the recovery of neural elements under different postoperative treatment protocols. One patellar tendon of 46 New-Zealand-White rabbits was shrunk. Six rabbits were sacrificed immediately postoperative. Twenty rabbits were not immobilized, 10 were immobilized for 3 and 10 were immobilized for 6 weeks. A monoclonal antibody, specific against a neurofilament protein, was used to detect nerves and neural structures. Staining pattern of nerve fibres was significantly altered immediately postoperative. After 3 weeks the number of nerve fibres and bundles decreased significantly in immobilized and non-immobilized limbs. The loss of nerve fibres was significantly less in immobilized limbs. At 6 weeks the number of neural elements in immobilized limbs increased to the level of untreated control tissue. In non-immobilized limbs we found no recovery of neural elements 9 weeks postoperatively. At this time the number of nerve fibres and bundles was still significantly less compared to the untreated control limbs. RF-shrinkage causes significant alteration of neural elements. Under immobilization nerve fibres and bundles reach the level of normal untreated tissue. Careful rehabilitation is important after RF-shrinkage. Not only for biomechanical reasons, but also to allow the neural elements to recover, thermally modified tissue should be protected from normal physiologic loads.

Heat-induced changes in porcine annulus fibrosus biomechanics

The intervertebral disc is implicated as the source of low-back pain in a substantial number of patients. Because thermal therapy has been thought to have a therapeutic effect on collagenous tissues, this technique has recently been incorporated into several minimally invasive back pain treatments. However, patient selection criteria and precise definition of optimum dose are hindered by uncertainty of treatment mechanisms. The purpose of this study was to quantify acute changes in annulus fibrosus biomechanics after a range of thermal exposures, and to correlate these results with tissue denaturation. Intact annulus fibrosus (attached to adjacent vertebrae) from porcine lumbar spines was tested ex vivo. Biomechanical behavior, microstructure, peak of denaturation endotherm, and enthalpy of denaturation (mDSC) were determined before and after hydrothermal heat treatment at 37 degrees C, 50 degrees C, 60 degrees C, 65 degrees C, 70 degrees C, 75 degrees C, 80 degrees C, and 85 degrees C. Shrinkage of excised annular tissue (removed from adjacent vertebrae) was also measured after treatment at 85 degrees C. Significant differences in intact annulus biomechanics were observed after treatment, but the effects were much smaller in magnitude than those observed in excised annulus and those reported previously for other tissues. Consistent with this, intact tissue was only minimally denatured by treatment at 85 degrees C for 15 min, whereas excised tissue was completely denatured by this protocol. Our data suggest that in situ constraint imposed by the joint structure significantly retards annular thermal denaturation. These findings should aid the interpretation of clinical outcomes and provide a basis for the future design of optimum dosing regimens.

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.

Arthroscopic repair of lateral ankle instability by using the thermal-assisted capsular shift procedure: a review of 4 cases

The purpose of this study is to determine the preliminary effectiveness of the thermal-assisted capsular shift procedure for treatment of chronic lateral ankle instability. A retrospective preoperative evaluation using a modified American Orthopedic Foot and Ankle Society's ankle scoring system was performed on 4 patients treated with the procedure. Patients were then contacted for a 6-month follow-up evaluation using the same scale. The mean preoperative score was 26 of 60 and the mean postoperative score was 51 of 60, a mean 25-point improvement. All 4 rated their satisfaction with the surgery as good or excellent and 3 of 4 stated they would have the surgery again if necessary. The thermal-assisted capsular shift procedure showed good to excellent early results in this small study group and offers the foot and ankle surgeon a minimally invasive surgical alternative for treatment of lateral ankle ligament 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.

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.

Electrothermal assisted shoulder capsulorraphy--monopolar

Monopolar electrothermal stabilization of the shoulder shows considerable promise as a treatment alternative in athletes and patients with recurrent instability. Range of motion is preserved, recovery is faster than with open procedures, there is little disruption or alteration of inherent anatomy, and, most importantly, results at 2 years appear comparable to other surgical procedures in high-demand populations. The procedure is technically easy to perform, and the complication rate is low. Success depends on surgeon's understanding of the applications of RF energy, the use of proper surgical technique, careful patient selection, attention to the rehabilitation program, and the patient's compliance with postoperative protocol. Long-term follow-up is necessary to determine if results for this procedure deteriorate over time, especially in patients with multidirectional instability.

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.

Complications of thermal energy in knee surgery--Part II

With the theoretical and reported complications of thermal energy use in the knee, an analysis of potential risks and benefits should be done on a case-by-case basis. Many of the basic science studies may not be directly applicable to clinical practice because they use normal (i.e., not diseased) tissues in animal models. Clinical studies are also dependent on surgical technique and equipment settings. With the benefits listed previously, however, it is likely that thermal energy will continue to play an important role in arthroscopic orthopedic surgery, and there are studies that strongly support its safety and efficacy. Janecki performed a retrospective review of 504 laser chondroplasties to determine safe parameters for Ho:YAG laser use in the knee [10]. In their series, they found an 88% patient satisfaction rate, no significant changes in the articular cartilage lesions in the failure group who underwent repeat arthroscopy, and no new cases of osteonecrosis. They concluded that the Ho:YAG laser was safe and recommended energy settings of less than or equal to 1 joule when performing chondroplasties, noncontact and tangential delivery of the laser beam, and maximizing laser spot size as methods for further decreasing complication rates. We agree with the above recommendations and with using the minimal power settings required to afford the desired surgical result. More studies are required to fully define the indications and consequences of thermal energy use in the knee.

Shoulder proprioception and function following thermal capsulorraphy

PURPOSE

Because monopolar radiofrequency energy has a denaturing effect on the glenohumeral joint capsule during thermal capsulorraphy, we hypothesized that thermal treatment would have a deleterious effect on the mechanoreceptors present within the capsule, thereby affecting proprioception and function. The purpose of this study was to evaluate proprioception and function following thermal capsulorraphy.

TYPE OF STUDY

Case series.

METHODS

Twenty subjects (13 male, 7 female) diagnosed with unilateral anterior, anteroinferior, or multidirectional glenohumeral instability with no significant concomitant pathologies, were treated with monopolar radiofrequency thermal capsulorraphy by one surgeon. Capsular redundancy was the primary diagnosis in all subjects. Subjects were bilaterally tested retrospectively 6 to 24 months (11.90 +/- 5.65 months) following surgery. Each subject's ability to actively reproduce joint positions (ARJP) and reproduce paths of motion (PMR) was measured with an electromagnetic motion analysis system. Both passive reproduction of joint positions (PRJP) and threshold to detect passive motion (TTDPM) were measured using a proprioception testing device. Function was quantified with the Shoulder Rating Questionnaire (SRQ). Proprioception data were analyzed with separate repeated measures ANOVA (P <.05).

RESULTS

Statistical analysis revealed a significant ARJP difference between the involved and uninvolved limb (P =.005) indicating that reproduction error was less with the involved limb compared to the uninvolved limb. No significant interactions were present for TTDPM, PRJP, or PMR. The SRQ indicates that the subjects returned to near normal function (91.86/100 +/- 5.38 points) at the time of testing.

CONCLUSIONS

The results from this study do not support our hypothesis of proprioception and functional deficits following thermal treatment. Normalized proprioception following thermal capsulorraphy may have resulted from the healing effects of thermal treated ligament, as reported in the literature, as well as facilitation of other mechanoreceptors present in adjacent tissue about the shoulder joint during rehabilitation. The results of this study indicate that no appreciative deleterious effects exist with proprioception and function following treatment of shoulder instability with thermal capsulorraphy.

Histologic evaluation of the shoulder capsule in normal shoulders, unstable shoulders, and after failed thermal capsulorrhaphy

BACKGROUND

Attenuation of the shoulder capsule has been noted during revision surgery for failed thermal capsulorrhaphy.

HYPOTHESIS

The attenuated capsule seen in patients who have undergone failed thermal capsulorrhaphy will show histologic characteristics distinguishing it from the capsule of normal shoulders and dislocating shoulders.

STUDY DESIGN

Case control study.

METHODS

The shoulder capsules were studied in 12 patients with traumatic anterior instability and in 7 patients who experienced recurrent instability after a thermal capsulorrhaphy. The capsules of six fresh-frozen cadavers with no shoulder lesions were used as controls.

RESULTS

Among patients who had a history of traumatic instability, a denuded synovial layer was present in 58%, subsynovial edema in 58%, increased cellularity in 25%, and increased vascularity in 83%. At the time of surgery, five of seven shoulders in the failed thermal capsulorrhaphy group (71%) were subjectively felt to be thin and attenuated. Denuded synovium was found in 100% of these patients, subsynovial edema in 43%, and changes in the collagen layer in 100%. Changes in the collagen layer in these patients included a "hyalinization" appearance in five cases (71%), increased collagen fibrosis in two cases (29%), and increased cellularity in two cases (29%).

CONCLUSIONS

There was no one characteristic observable on histologic evaluation that would explain the attenuation of the capsule in cases of failed thermal treatment. Morphologic collagen structure can be histologically abnormal for up to 16 months after thermal capsulorrhaphy.

Thermal capsulorrhaphy treatment of shoulder instability: basic science

Thermal capsulorrhaphy is a new treatment modality for shoulder instability, where the joint capsular tissue is heated and reduced in length by laser or radiofrequency energy to regain joint stability. Experimental studies have shown that (1) joint capsular tissue can be modified significantly (shortened) by thermal energy at the temperature range of 70 degrees to 80 degrees C; (2) thermal energy causes immediate deleterious effects such as loss of the mechanical properties, collagen denaturation, and cell necrosis; (3) thermally treated tissue is repaired actively by a residual population of fibroblasts and vascular cells, with concomitant improvement of mechanical properties; (4) the shrunken tissue stretches with time if the tissue is subjected to physiologic loading immediately after surgery; and (5) leaving viable tissue between treated regions significantly improves the healing process. Therefore, the application of thermal energy to achieve joint stability relies on an initial effect (shrinkage), and to a great extent the tissue's healing response to regain the tissue's mechanical properties. Particularly, induction of active repair and joint capsular thickening with tissue remodeling regulated by functional demand seem to be essential factors for a successful outcome. Thermal treatment causes an initial deleterious effect on the tissue's properties, and overtreatment can lead to severe immediate and permanent tissue damage. In addition, scientific data of newly developed devices are limited, and the information from manufacturers often is unreliable and misleading. Carefully controlled long-term clinical and scientific studies should be done to additionally clarify the advantages and disadvantages of this technique.

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.