Effects of monopolar radiofrequency energy on ovine joint capsular mechanical properties

Use of a radiofrequency probe for tenoscopic-guided annular ligament desmotomy

REASONS FOR PERFORMING STUDY

Annular ligament desmotomy is commonly performed in horses with chronic tenosynovitis. Previously reported tenoscopic techniques have limitations related to haemorrhage and awkward instrumentation. Radiofrequency (RF) energy affords precision and excellent haemostasis and may be a good alternative to sharp transection of the annular ligament in horses.

OBJECTIVE

To describe a technique for using a RF probe for tenoscopic-guided annular ligament desmotomy and to report the clinical outcome of horses in which it was performed.

METHODS

Cadaver specimens (n = 14) and live horses undergoing unrelated terminal procedures (n = 2) were used to optimise the tenoscopic-guided RF annular ligament desmotomy technique. Records were examined for all horses undergoing annular ligament desmotomy with an RF probe from 2003 to 2008 for which follow-up of >1 year post operatively was available.

RESULTS

The annular ligament was successfully transected in the cadaver and live horse model limbs using 2 different commercially available RF probes. Complete transection was achieved with practice and confirmed on gross dissection. Histopathology did not reveal any collateral damage to surrounding tissue. Follow-up of >1 year was available for 6 of 7 clinical cases. Four of 6 horses returned to work. Owners were satisfied with the outcome in all cases.

CONCLUSIONS

Desmotomy using a RF probe allows precise tissue transection under tenoscopic guidance without damage to surrounding structures or haemorrhage. With experience, it is an easily performed technique. In clinical patients, an acceptable outcome may be expected.

POTENTIAL RELEVANCE

Tenoscopic-guided RF annular ligament desmotomy offers advantages, including reliable haemostasis and precise tissue transection, over previously reported techniques and is a viable surgical alternative for treating horses with annular ligament desmitis and other complex pathology within the tendon sheath.

Histologic evaluation of thermal capsulorrhaphy of human shoulder joint capsule with monopolar radiofrequency energy during short- to long-term follow-up

PURPOSE

The purpose of this study was to evaluate the histologic morphology of human shoulder joint capsule after thermal capsulorrhaphy with monopolar radiofrequency energy (mRFE) during short- to long-term follow-up.

METHODS

This study comprised 27 patients who received an arthroscopic mRFE thermal capsulorrhaphy and 10 patients without mRFE treatment serving as the control group. Biopsy samples from 3 locations (anterior-superior, anterior-inferior, and posterior-medial) of the shoulder joint capsule were harvested from both the mRFE-treated patients and the control patients. The follow-up time for the mRFE treatment ranged from 3.5 to 62 months, which was divided into 3 groups: short, 3.5 to 12 months; medium, 14 to 25 months; and long, 31 to 62 months. The biopsy samples were analyzed via a histologic scoring system, evaluating an intact synovial layer, subsynovial edema, collagen morphology, cellularity, vascularity, and inflammatory cells. Histologic scores among each follow-up group were compared with each other and with those in the control group.

RESULTS

There were no significant differences in the histologic categories of intact synovial layer, subsynovial edema, collagen morphology, and inflammatory cells among the control and mid- and long-term mRFE groups. The short-term mRFE group had greater increased cellularity and vascularity compared with the mid- and long-term groups, which progressively improved toward the appearance in the normal control group with time.

CONCLUSIONS

After mRFE capsulorrhaphy, histologic analysis revealed that the mRFE-treated shoulder joint capsule had almost returned to normal, except for persistent cellularity and increased vascularity, which were present at up to 5 years after this procedure.

LEVEL OF EVIDENCE

Level III, therapeutic case-control study.

Mechanical changes induced by thermal stimulation in collagenous tissue

Radiofrequency thermal stimulation is used as a therapeutic procedure for joint laxity, but its thermal effects are still controversial. Although collagen shrinkage may be expected, this conclusion is empirical and not universally accepted. The purpose of this study was to investigate the mechanical response of collagen to thermal stimulation. A longitudinal cut was made in rabbit Achilles tendons previously marked with monofilament sutures. The distance between the sutures was measured before the cut, just after it was made, and after 8 weeks. The results did not show any shrinkage or significant change in tendon resistance to traction 8 weeks after thermal stimulation; however, comparison with the opposite, normal tendon revealed a statistically significant increase in tendon stiffness.

Monopolar radiofrequency energy application to the dorsal extensor tendon apparatus in a canine model of tendon injury

PURPOSE

To evaluate the use of monopolar radiofrequency energy (MRFE) to shorten stretched dorsal extensor tendon apparatus (DETA) tissues in a canine model.

METHODS

Eleven adult canine forelimbs were used in this in vitro investigation. The DETA tissue was isolated between the metacarpophalangeal and proximal interphalangeal joints in the third and fourth digits of each limb. Isolated tissue was stretched in all but 2 of the digits (control group). After tissue stretching, monopular radiofrequency energy (MRFE) was applied to 18 of the digits at 1 of 3 temperatures: 50 degrees C, 60 degrees C, or 70 degrees C (stretch-treatment group). Two digits were treated identically, but MRFE was not applied (stretch-only group). Tissue length was measured before and after stretching and after treatment. Percent stretch, percent shortening, and percent original length were compared among the 3 stretch-treatment groups. All DETA specimens were examined with light microscopy.

RESULTS

Histologic changes were apparent in the stretch-treatment and stretch-only specimens compared with controls. Percent stretch was not significantly different between groups. Percent shortening and percent original length were significantly lower and higher, respectively, in the 50 degrees C group than in the 60 degrees C and 70 degrees C stretch-treatment groups, which were not significantly different from each other. There was a significant linear correspondence between percent shortening and treatment temperature.

CONCLUSIONS

The application of MRFE at a temperature of 60 degrees C and a power of 10 W appears to shorten stretched DETA tissue to approximately the prestretched length in an in vitro canine model. Further investigation is necessary to determine the effect of treatment on the tissue's mechanical properties.

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.

Thermal effects after anterior cruciate ligament shrinkage using radiofrequency technology: a porcine cadaver study

The effects of thermal energy on an anterior cruciate ligament (ACL) are unknown. This study was undertaken to know the immediate and direct effects of thermocoagulation on normal ACL. Thermocoagulation was generated by monopolar radiofrequency (RF) at 67 degrees C and 40 W of energy and applied with use of a commercial jig in a porcine cadaveric model, and biomechanical and histological changes were evaluated immediately. Thermocoagulation caused significant shrinkage of ACL without immediate effects on ligament biomechanical properties, including stiffness and maximal failure force. However, histological analysis demonstrated a decrease in number of dense elongated cells and blood vessels within the epiligamentous tissue, loss of areolar spaces, decrement in the periodicity of collagen waveform, and shortening and pyknotic nuclear changes of cells within the fascicular region. RF-generated thermocoagulation resulted in ACL shortening with significant changes on histological findings but not on initial biomechanical properties.

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.

Thermal modification of partial tears of the anterior cruciate ligament

PURPOSE

Partial tears of the anterior cruciate ligament (ACL) are common, representing 10% to 28% of all ACL tears. Untreated partial tears of the ACL may go on to complete rupture in up to 42% of cases, and as few as 30% of patients return to their preinjury activity level. The purpose of this study was to evaluate the effectiveness of thermal modification for the treatment of partial tears of the ACL.

TYPE OF STUDY

A prospective, nonrandomized consecutive case series.

METHODS

Thirteen patients with a partial tear of a native ACL were treated with thermal modification of the ACL. All patients had a preoperative office examination significant for an end-point to Lachman examination and pivot-glide. All patients had bilateral preoperative KT-1000 measurements. All tears were confirmed by arthroscopy to constitute a 50% or less loss of structural integrity of the ligament. The ACL underwent thermal modification using the Oratec thermal probe (Oratec Interventions, Menlo Park, CA), and was examined by intraoperative KT-1000 testing. Patients were evaluated postoperatively at 6 weeks, and at 3, 6, 12, and 24 months by office examination and functional outcome scoring.

RESULTS

KT-1000 arthrometer testing revealed a mean side-to-side difference of 4.35 mm preoperatively (SD = 1.1 mm). At the most recent follow-up, averaging 23 months (range, 18 to 28 months), 10 patients had a negative Lachman examination and no pivot-shift. Two patients had persistent grade II Lachman and complaints of giving way 3 months postoperative. Both patients underwent ACL reconstruction. One patient was lost to follow-up. Of the remaining 10 patients, all patients achieved full extension, and the average flexion range of motion was 131 degrees (SD = 5.6). Compared with the preoperative KT-1000 arthrometer testing, the most recent evaluation revealed a decrease in mean side-to-side difference to 1.9 mm (SD = 1.5 mm). At most recent follow-up, the mean Lysholm score was 96.3 (SD = 4.4), the mean Tegner score was 6.1 (SD = 1.2), and the mean Cincinnati score was 94 (SD = 3.0).

CONCLUSIONS

With cautious application, thermal modification may be a viable treatment option for partial tears of the ACL in a select subset of patients. Further investigation is necessary to determine the long-term effectiveness of this procedure.

LEVEL OF EVIDENCE

Level IV, Therapeutic Case Series Study (no or historical control group).

Radiofrequency ablation in osteoid osteoma of the finger

The occurrence of osteoid osteomas of the hand is rare and their treatment usually is surgical. A 26-year-old man with an osteoid osteoma in the proximal phalanx of the right middle finger was treated with percutaneous radiofrequency ablation. Two years later he remains free of pain and finger function is normal.

Effects of Radiofrequency Energy on Human Chondromalacic Cartilage: An Assessment of Insulation Material Properties

The objective of this study was to establish guidelines for the selection of an insulation material used to surround the electrode of radiofrequency energy (RFE) probes used for thermal chondroplasty. These guidelines were established by identifying which insulation materials resulted in the least amount of chondrocyte death while smoothing the surface of chondromalacic cartilage. RFE causes electrolyte oscillation and molecular friction in the tissue to heat it and subsequently smooth the surface. Material properties investigated included the coefficient of thermal expansion (CTE), thermal conductivity (TC), and volume resistivity (VR). Fresh human chondromalacic cartilage samples of Outerbridge grades II and III were obtained from patients undergoing total knee arthroplasty. Stiffness measurements were taken pretreatment and posttreatment. RFE was applied to a 1-cm2 area for 15 s in a paintbrush treatment pattern. The insulation materials evaluated included Macor (decrease CTE, decrease TC, increase VR; in relation to CTE = 10 x 10(-6)/degrees C at 20 degrees C, TC = 3 W/mK, VR=1 x 10(14) ohm x cm), zirconia toughened alumina (ZTA) and 99.5% alumina (decrease CTE, increase TC, increase VR), aluminum nitride (decrease CTE, increase TC, decrease VR), Teflon (PTFE) (increase CTE, decrease TC, increase VR), partially stabilized zirconia (YTZP) (decrease CTE, decrease TC, decrease VR), and Ultem (increase CTE, decrease TC, decrease VR). There were no significant differences between pretreatment and posttreatment stiffness of the cartilage for any material investigated. Subjectively scored scanning electron microscopy (SEM) images revealed that the surfaces of all samples treated with RFE were relatively smooth with melted fronds. Prototype probes made with Macor, 99.5% alumina, and ZTA had TC < or = 30 W/mol x K and resulted in a mean of 35% less cell death (176+/-56 microm, 130+/-48 microm, and 114+/-33 microm, respectively) than aluminum nitride, PTFE, and YTZP (246+/-68 microm, 231+/-108 microm, and 195+/-89 microm, respectively). Macor, 99.5% alumina, and ZTA prototype probes all had VR > or = 1 x 10(14) ohm x cm and resulted in a mean 37% less cell death than aluminum nitride or YTZP. There was no apparent relationship between CTE and the depth of chondrocyte death.

Excessive radiofrequency application: effects on capsular tissue in an animal model

Capsular attenuation has been seen after thermal capsulorrhaphy surgery. The purpose of this study was to evaluate the mechanical, histologic, and morphologic effects on capsular tissue after cumulative applications of radiofrequency energy. Ovine patellofemoral capsular tissue was treated with 1, 2, 4, or 8 applications of bipolar radiofrequency energy and then analyzed. No acute capsular ablation or destruction was seen grossly, even in the 8-application group. No definitive visual clues that excessive radiofrequency energy had been applied were seen. There was significant shrinkage and loss of tensile stiffness for all thermal application groups. Given the small sample sizes, post-application failure load, percent relaxation, and stiffness were not observed to be significantly different among the groups. Cumulative applications produced minimal further tissue shrinkage but were accompanied by larger, though not statistically significant, mechanical property losses and increased depth of tissue penetration. These findings suggest that there is no benefit to repeated applications of radiofrequency energy to capsular tissue.

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.

Comparative effects of monopolar radiofrequency energy and conservative management of mechanical properties of elongated lateral collateral ligament in rabbits: an experimental study

OBJECTIVE

We examined the biomechanical effects of shrinkage in elongated rabbit lateral collateral ligament.

DESIGN

This study was designed in an attempt to evaluate the energy effects of monopolar radiofrequency on strained but not ruptured ligaments.

BACKGROUND

In treatment of ligament injuries difficulty in reducing increased laxity after trauma and recurrence of instability are important factors for failure.

METHODS

Ligament elongation and laxity were achieved in operating room by applying varus stress for multiple times. In Group C ( n = 8 ), elongated lateral collateral ligaments were treated only with above-knee cast, while in Group S ( n = 8 ), they were treated with shrinkage and above-knee casts. The un-operated sides were labeled as control groups. At the 12th week after surgery the animals were sacrificed and hind limbs were disarticulated. Removing the other soft tissues around knee, only lateral collateral ligaments were left intact. Biomechanical analyses of the effects of two different treatment methods were compared by performing a pulling-out test.

RESULTS

Considering maximum load and stiffness, conservatively treated ligaments were stronger and stiffer than shrunken ligaments ( P < 0.05 ).

CONCLUSION

Biomechanical values were altered by both treatment methods. Reflecting an alteration in intra-molecular structure, the main alteration was the decrease of strength in shrunken ligaments. In ligament injuries, we concluded shrinkage not to be superior to conservative treatment.

Electrothermal capsulorrhaphy in glenohumeral instability without Bankart tear

PURPOSE

The purpose of this study is to review the clinical results of electrothermal capsulorrhaphy (ETC) performed on 23 patients for the treatment of glenohumeral instability at an minimum follow-up of 2 years.

TYPE OF STUDY

Retrospective case series.

METHODS

Twenty-six patients with symptomatic unidirectional or multidirectional glenohumeral instability without Bankart tear were treated with ETC using a radiofrequency probe. No labral repairs were performed. A standard postoperative rehabilitation protocol was followed. Patients were evaluated with respect to motion, direction of instability, need for repeat surgery, return to overhand sports, and symptoms of pain and instability using various scores.

RESULTS

Twenty-three patients were available for follow-up evaluation at an average of 30 months. The overall average ASES and Rowe scores were 84.2 and 79.3, respectively. Recurrent instability requiring an open stabilization procedure occurred in 4 patients (17%), 2 with anterior and 2 with multidirectional instability. Seven of 14 overhead athletes (50%) reported inability to return to their previous level. According to Rowe scores, overall results were 11 excellent, 5 good, 4 fair, and 3 poor. No postoperative nerve complications occurred.

CONCLUSIONS

The ETC procedure was safely performed to treat glenohumeral instability without Bankart lesions. The recurrence rate is similar to that for other arthroscopic procedures but higher than for open surgery. In the absence of Bankart tear, patients with multidirectional instability and overhand athletes may require something other than an isolated ETC procedure to address instability. Long-term results of ETC are needed to better define its surgical indications.

Anterior cruciate ligament rupture after thermal treatment in a canine model

BACKGROUND

The use of radiofrequency energy to treat damaged anterior cruciate ligaments is gaining popularity. However, complete rupture of the ligament after treatment has been reported.

PURPOSE

To evaluate the effect of thermal energy applied arthroscopically to normal, intact anterior cruciate ligaments in mature dogs.

STUDY DESIGN

Controlled laboratory study.

METHODS

Monopolar radiofrequency energy was applied to the normal anterior cruciate ligament of 1 knee in 18 dogs. The contralateral anterior cruciate ligament (also normal) was sham treated. Force-plate gait analysis was performed preoperatively and at 4, 8, 12, 16, 26, and 36 weeks after surgery. Anterior cruciate ligament rupture was detected by a sudden onset of nonweightbearing and a positive drawer sign.

RESULTS

All treated ligaments ruptured approximately 55 days after surgery (mean, 55 days; standard error, 1.6).

CONCLUSIONS

Although monopolar radiofrequency energy may have some potential in the treatment of lax anterior cruciate ligaments, in the application described here the result was a highly predictable deterioration and rupture of all treated anterior cruciate ligaments.

CLINICAL RELEVANCE

On the basis of these findings, we strongly recommend that strict selection and application criteria be used when considering use of this modality on anterior cruciate ligaments that are stretched or partially disrupted, or both. Use of this modality should be followed by adherence to a highly conservative rehabilitation protocol.

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.

A prospective multisite study of radiofrequency bipolar energy for treatment of genuine stress incontinence

STUDY OBJECTIVE

To assess the efficacy of radiofrequency electrothermal energy to treat genuine stress incontinence (GSI).

DESIGN

Multicenter, prospective, single-arm, longitudinal study (Canadian Task Force classification II-1).

SETTING

Six North American university-affiliated and private clinic sites.

PATIENTS

Ninety-four women undergoing laparoscopic treatment for GSI.

INTERVENTION

Radiofrequency bipolar treatment of paravaginal tissue to induce tissue shrinkage causing bladder neck elevation.

MEASUREMENTS AND MAIN RESULTS

Patients underwent complete urogynecologic evaluations, with urodynamic testing, including Valsalva leak point pressure, to confirm the diagnosis of GSI. Paravaginal tissue was treated lateral from the urethra and bladder neck out to the arcus white line, with bipolar electrothermal energy to shrink bladder-supporting connective tissue. Treatment resulted in 30% shrinkage in paravaginal endopelvic fascia surface area by direct measurement. At 1 year the objective cure rate was 79% by urodynamic testing, improvement in quality of life by questionnaire was 81%, decrease in leaking episodes and pad use was significant (p <0.001), and patient satisfaction was 83%. Complications (7%) were secondary to laparoscopy. There were no injuries from the radiofrequency probe.

CONCLUSION

Radiofrequency bipolar electrothermal energy appears to be a safe an efficient means of treating mild to moderate GSI. It results in shrinkage and elevation of paravaginal connective tissue, stabilizing the urethra and bladder neck, thereby restoring continence. Long-term follow-up is necessary.

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.

Electrothermal chondroplasty--monopolar

Despite the lack of clinical studies, monopolar RF energy is currently used for the treatment of grade 2, 3, and 4 chondromalacia. Basic science studies have confirmed that monopolar RF can mechanically debride the articular surface by smoothing, potentially reducing further delamination. However, a zone of thermal injury in the areas of treatment has been observed with loss of chondrocyte viability. Therefore, further use of this procedure lies in the surgeon's understanding of the potential deleterious effects of temperature on chondrocyte viability and the limitations of alternate treatment options. Monopolar RF energy is a potential alternative to other cartilage removal or smoothing techniques, but more science is needed to define optimal parameters for thermal chondroplasty. Great care is currently proposed in the selection of operative parameters by clinicians when using monopolar RF chondroplasty until safety and efficacy are confirmed.

The use of thermal energy in ankle instability

With appropriate indications, ankle arthroscopy can be of significant benefit to both the patient and physician. The additional use of thermal energy significantly enhances surgical techniques. Midterm follow-up of thermal treatment of ankle instability demonstrates excellent patient satisfaction, with preserved stability, good overall function, and return to sports. Further long-term follow-up studies will continue to provide us with data that will help guide the expansion of uses of thermal energy about the ankle in a safe and efficacious manner.

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 to treat shoulder instability

The contemporary therapeutic approach of glenohumeral instability is directed at the restoration of anatomy. Thermal capsular modification to treat shoulder instability is a relatively recent modality. Early successful clinical applications have led to a wide use of this low demanding technique. Currently, however, the indications for thermal capsulorrhaphy are defined poorly, clinical outcome has not been shown to be superior to conventional stabilization procedures, and long-term effects on joint biology and mechanics are not known. Based on a critical review of the literature and personal clinical experience, the authors conclude that additional experimental and clinical investigations are necessary to add this procedure to the accepted modalities applied for the treatment of shoulder instability.

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.

Monopolar radiofrequency energy for arthroscopic treatment of shoulder instability in the athlete

Monopolar radiofrequency energy is increasingly being used in the treatment of shoulder instability. Basic science studies and early clinical results have shown that application of thermal energy can result in successful shrinkage of the shoulder capsule. This procedure is useful in treating certain traumatic and recurrent instability conditions of the shoulder especially in the athlete where range of motion is preserved, recovery is faster than with open procedures, and there, is little disruption or alteration of inherent anatomy. The procedure is technically easy to perform, and the complication rate is low. Success, however, depends on proper patient selection, attention to the rehabilitation program, and patient compliance. Long-term follow-up will be necessary to determine if results for this procedure will deteriorate over time, especially in patients with multidirectional instability.

The effects of monopolar radiofrequency energy on intact and lacerated ovine menisci

PURPOSE

To evaluate the effect of monopolar radiofrequency energy (RFE) on intact and lacerated meniscal tissue.

TYPE OF STUDY

In vitro study. Application of monopolar RFE to soft tissue for treatment of various musculoskeletal disorders has been explored recently, although its effect on meniscal tissue has not been critically evaluated. Monopolar RFE denatures and fuses collagen. Given that menisci are composed primarily of type I collagen, we proposed that RFE could be applied to meniscal tears with minimal effect on healthy meniscal tissue.

METHODS

Adult sheep menisci were given 1 of 2 treatments (65 degrees C, 15 W or 75 degrees C, 10 W) with a monopolar RFE generator. Specimens were processed for scanning electron microscopy (SEM), transmission electron microscopy (TEM), light microscopy, and confocal laser microscopy. A computer-based area-determination program was used to calculate the treated area in confocal laser images.

RESULTS

SEM changes in treated tissue consisted of surface smoothing with collagen fibril fusion. Changes apparent with TEM included tissue homogenization with loss of cross-striations and fusion of collagen fibrils. Histologic changes consisted of fusion and loss of collagen fiber individualization, pyknosis of fibrochondrocyte nuclei, and loss of lacunae surrounding fibrochondrocytes. There were clear demarcations between treated and untreated tissue with both treatments. There were no discernible differences between treatment groups on SEM, TEM, or histologic examination. Confocal laser microscopic evaluations showed distinct treatment areas. The mean area affected ranged from 6.6% for 65 degrees C, 15 W to 8.8% for 75 degrees C, 10 W.

CONCLUSIONS

The primary effects of monopolar RFE treatment of menisci in this study were consistent with thermal tissue damage limited to the treatment area. Monopolar RFE treatment of a meniscal laceration may stabilize the tear by fusing collagenous tissue in the surrounding area and prevent propagation along tissue lines. This study presents preliminary in vitro results. Further studies are necessary before clinical applications can be recommended.