Collagen shortening. An experimental approach with heat

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.

Radiofrequency use on articular cartilage lesions

The incidence of knee arthritis is increasing in our society and presents many dilemmas to the patient and doctor. Recent advances in arthroscopic treatment of arthritis have lead to the development of radiofrequency energy as an adjunctive tool for many arthroscopic procedures. Of great concern is the recent use of radiofrequency energy to treat articular cartilage lesions in the knee.

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.

Thermal modification of the lax anterior cruciate ligament using radiofrequency: efficacy or catastrophe?

Alchemists dream of using energy to turn base metal to gold. "Shrinkers" use energy to transform laxity to stability. While alchemists search for the mechanism to achieve their goal, shrinkers have thermal energy (heat) and scientific ground for their pursuit. Without doubt, application of heat to collagen using radiofrequency (RF) results in tissue shrinkage. However, with regard to thermal shrinkage of a lax anterior cruciate ligament (ACL) or ACL graft, indications and techniques, rehabilitation and outcomes require review. Such is the purpose of this article.

Long-term failure of thermal shrinkage for laxity of the anterior cruciate ligament

BACKGROUND

Appropriate treatment for anterior cruciate ligament laxity, owing to partial tears of the native ligament or lax reconstruction, is unclear. Studies suggest that a significant percentage of these untreated tears may progress to complete tears or the patient may develop additional injuries to the meniscus or articular cartilage. Shrinkage of the ligament or graft using thermal energy has been proposed as a solution for this problem.

PURPOSE

To evaluate the long-term results using thermal energy to shrink laxity of the anterior cruciate ligament.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Nineteen patients with partial tears of the anterior cruciate ligament (n = 14) or stretched anterior cruciate ligament grafts (n = 5) underwent thermal shrinkage treatment. Fourteen were available for follow-up at 1 and 5 years. At 1 year, there were 12 partial tears and 2 grafts available for evaluation. At 5 years, there were 10 partial tears and 4 grafts. Preoperative, postoperative, and intraoperative stability testing was performed using the KT-1000 arthrometer. Clinical results were evaluated using the Cincinnati and Lysholm scoring systems.

RESULTS

Intraoperative shrinkage averaged 2.12 mm (17%, P < .0001). At 1 year, 12 of the 14 patients remained stable (86%) with a negative Lachman test result and mean KT-1000 arthrometer maximum side-to-side score of 1.29 mm (P < .001). The 2 failed shrinkages were partial tears of the native anterior cruciate ligament. For these 12 patients, Cincinnati scores improved from 53 to 89 (P < .0001), and Lysholm scores improved from 55 to 89 (P < .0003). At 5-year follow-up, 11 of 13 patients had gone on to complete failure (85%, P < .002; 8/9 partial tears and 3/4 grafts).

CONCLUSION

Thermal shrinkage provides short-term benefit in the treatment of anterior cruciate ligament laxity but leads to catastrophic failure in the majority of patients at long-term follow-up. We can no longer recommend this procedure for the treatment of anterior cruciate ligament laxity.

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.

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.

Biomechanical properties of heat-treated bone grafts

INTRODUCTION

A possible critical complication associated with banking bone is human immunodeficiency virus (HIV) infection. Recently, since the report of HIV infection in bone allografts from an HIV-seronegative donor, a more reliable method of sterilization for preserved bone graft has become necessary. Heat treatment of banking bone is one of the simple sterilization methods. This method is especially safe and practical for the prevention of HIV infection.

MATERIALS AND METHODS

We previously reported a biological study on heat-treated bone graft. In that study, we showed that revascularization and new bone formation of bone graft after heat treatment at 60 degrees C was nearly the same as that of non-heat-treated bone graft, while at 100 degrees C, revascularization and new bone formation showed a significant delay. This time, we examined the change of mechanical strength of heat-treated bone grafts after transplantation in an experiment. To eliminate the problem of antigenicity of grafted bone, we used autografts, not allografts. Two types of heat-treated autografts were employed: heat-treated at 60 degrees C for 30 min and heat-treated at 100 degrees C for 5 min; as a control, fresh autografts were replaced in the left femur of rabbits. A strength test was performed for both the transplanted bone and the untreated intact right femur with time after transplantation. The strength test consisted of a compression test and torsional test, and the strength was compared between transplanted bone and the untreated intact right femur.

RESULTS

In the compression test, the grafts heat-treated at 60 degrees C showed a strength ratio before transplantation of 97.3%. The strength ratio decreased to 63.5% at 18 weeks after transplantation. Then the strength ratio increased and recovered to 94.5% at 48 weeks after transplantation. However, the grafts heat-treated at 100 degrees C showed unsatisfactory mechanical strength, at 48 weeks the strength ratio was 60.1%, which was significantly lower compared with controls. In the torsional test, the grafts heat-treated at 60 degrees C showed almost the same strength observed in the compression test. However, the grafts heat-treated at 100 degrees C showed unsatisfactory mechanical strength: at 48 weeks, the strength ratio was 57.3%.

CONCLUSION

Therefore, heat treatment at 60 degrees C is a useful sterilization method, not only in biological but also mechanical terms.

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.

Thermal profile of radiofrequency energy in the inferior glenohumeral ligament

PURPOSE

Currently, two different methods of applying radiofrequency (RF) energy (monopolar and bipolar) are available to the surgeon for thermal shortening of the shoulder capsule. The objective of this study was to investigate the temperature changes and the thermal conduction across the human inferior glenohumeral ligament (IGHL) during radiofrequency energy application.

METHODS

Thermistors were secured onto both the intra-articular and extra-articular surfaces of human IGHL. Monopolar RF energy and bipolar RF energy were delivered to the intra-articular surface at the manufacturer's recommended settings. Pre-treatment and post-treatment ligament lengths, widths, heating times, and temperatures were measured and compared.

RESULTS

For the monopolar devices, temperature spikes to 89 degrees C were recorded for the set temperature of 67 degrees C, averaging 77 degrees C +/- 10 degrees C. Temperatures across the ligament averaged 48 degrees C +/- 3 degrees C. For both devices, the IGHL became thicker with higher RF settings. Recorded temperatures decreased as distance increased from the point of application. Maximum temperatures occurred at least 6 to 7 seconds after cessation of energy application.

CONCLUSIONS

The bipolar and monopolar devices had similar conduction times across the ligament, suggesting that this occurs by simple diffusion of heat. Bipolar and monopolar devices were equally efficacious for capsular shrinkage if the extent of the shortening is tightly defined.

CLINICAL RELEVANCE

The thermal probe should not rest in one position for an extended period of time during RF energy application because, as our study showed, the monitoring of temperature or the visualization of tissue change is not efficacious for determining the end point of thermal shrinkage of the shoulder capsule.

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.

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

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

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.

Radiofrequency probe treatment for subfailure ligament injury: a biomechanical study of rabbit ACL

OBJECTIVE

Utilizing a rabbit anterior cruciate ligament model of ligamentous subfailure injury, biomechanical properties of injured ligament treated with radiofrequency energy were evaluated. It was hypothesized that an injured ligament treated with radiofrequency probe would demonstrate restoration of biomechanical properties lost through injury.

BACKGROUND

Radiofrequency probe, thermal treatment has been utilized in the clinical setting to address joint instability caused by ligamentous laxity from injury or repetitive microtrauma. The biomechanical effects of radiofrequency probe thermal treatment on injured ligamentous tissues have not been studied in the laboratory.

DESIGN

Three groups of specimens: Control, Sham, and Treatment, 10 each, were tested under identical conditions.

METHODS

Viscoelastic behavior was analyzed using a relaxation test (6% strain, up to 180 s) performed before injury, after injury, and after injury plus sham or injury plus radiofrequency probe treatment.

RESULTS

After injury the normalized forces in the relaxation test decreased by approximately 50%. The post-treatment relaxation test revealed significant ( P < 0.01 ) restoration of the average relaxation force in the Treatment group to that of the Control group (0.79, SD 0.11 vs. 0.80, SD 0.10). Both of these groups were significantly different from the Sham group (0.44, SD 0.11). Additionally, stretch-to-failure test showed partial restoration of the toe region of the load-deformation curve by the radiofrequency treatment.

CONCLUSIONS

The radiofrequency probe treatment is shown to be an effective mechanism for restoring initial ligament tensile stiffness and viscoelastic characteristics lost by the subfailure injury in vitro.

Shoulder capsule shrinkage and consequences on shoulder movements

A study was designed to find landmarks to avoid restriction of range of motion or insufficient shortening of the ligaments after thermal shoulder capsule shrinkage. In 15 nonembalmed shoulders from cadavers, shrinkage was done in three steps: (1). the middle glenohumeral ligament, (2). the anterior part of the inferior glenohumeral ligament, and (3). the posterior part of the glenohumeral ligament. Before and after each step passive range of motion of the glenohumeral joint was studied. Results indicated that flexion and the external rotation were not affected. External rotation in the scapular plane with 45 degree elevation diminished after shrinkage of the middle glenohumeral ligament. External rotation in full abduction diminished after shrinkage of the anterior part of the inferior glenohumeral ligament. Abduction diminished after shrinkage of the anterior and posterior parts of the inferior glenohumeral ligament. Internal rotation in full abduction was restricted after shrinkage of the posterior part of the inferior glenohumeral ligament. These results show a constant relation between the reduction of a given movement and the shrunken area, by providing useful landmarks to reduce the passive hyperabduction that is constant in anterior shoulder instability and to control the immediate effects on the other ranges of motion. To control the immediate consequences of shrinkage may help avoid excessive restriction of motion or insufficient reduction of capsular redundancy.

Prospective evaluation of thermal capsulorrhaphy for shoulder instability: indications and results, two- to five-year follow-up

BACKGROUND

Thermal shrinkage of capsular tissue has recently been proposed as a means to address the capsular redundancy associated with shoulder instability. Although this procedure has become very popular, minimal peer-reviewed literature is available to justify its widespread use.

PURPOSE

To prospectively evaluate the efficacy of arthroscopic electrothermal capsulorrhaphy for the treatment of shoulder instability.

STUDY DESIGN

This nonrandomized prospective study evaluated the indications and results of thermal capsulorrhaphy in 84 shoulders with an average follow-up of 38 months.

METHODS

Patients were divided into three clinical subgroups: traumatic anterior dislocation (acute or recurrent), recurrent anterior anterior/inferior subluxation without prior dislocation, and multidirectional instability. Patients underwent arthroscopic thermal capsulorrhaphy after initial assessment, radiographs, and failure of a minimum of 3 months of nonoperative rehabilitation.

RESULTS

Outcome measures included pain, recurrent instability, return to work/sports, and the American Shoulder and Elbow Surgeons (ASES) Shoulder Assessment score. Overall results were excellent in 33 participants (39%), satisfactory in 20 (24%), and unsatisfactory in 31 (37%).

CONCLUSIONS

The high rate of unsatisfactory overall results (37%), documented with longer follow-up, is of great concern. The authors conclude that enthusiasm for thermal capsulorrhaphy should be tempered until further studies document its efficacy.

Thermal capsular shrinkage for treatment of multidirectional instability of the shoulder

BACKGROUND

Capsular laxity is the main pathology in patients with multidirectional instability, and thermal shrinkage has been commonly employed to treat this condition. The objective of this study was to evaluate thermal capsular shrinkage as a treatment of multidirectional instability of the shoulder.

METHODS

Nineteen consecutive patients with multidirectional instability were treated with thermal shrinkage. Fifteen patients had involuntary instability, and four had voluntary instability. The predominant direction of the instability was anteroinferior in ten patients and posterior in five; four patients had instability in multiple directions. Patients were followed for a minimum of two years or until surgical failure and recurrence of symptoms. Postoperatively, the patients wore a sling for three weeks, and they were evaluated regularly at three, six, and twelve months. The Western Ontario Shoulder Instability Index as well as subjective and objective evaluations of the patient's function, range of motion, pain, and instability were used as clinical outcome measures.

RESULTS

Nine patients had recurrence of the instability at an average of nine months (range, seven to fourteen months) following the surgical procedure. Four patients had sensory dysesthesias in the axillary nerve distribution, and one of them had deltoid weakness. All neurological symptoms resolved within nine months. The surgical procedure failed in the five patients with predominantly posterior instability. It failed in only two of the ten patients with predominantly anteroinferior instability, and overall this group had objective improvement.

CONCLUSIONS

Thermal capsular shrinkage used to treat multidirectional instability had a substantial failure rate with associated postoperative complications, including recurrence of instability (nine of the nineteen patients), stiffness (five patients), and neurological symptoms (four patients).

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.

Effect of an aqueous extract of Phaseolus vulgaris on the properties of tail tendon collagen of rats with streptozotocin-induced diabetes

Changes in the structural and functional properties of collagen caused by advanced glycation might be of importance for the etiology of late complications in diabetes. The present study was undertaken to investigate the influence of oral administration of aqueous pod extract (200 mg/kg body weight) of Phaseolus vulgaris, an indigenous plant used in Ayurvedic Medicine in India, on collagen content and characteristics in the tail tendon of streptozotocin-diabetic rats. In diabetic rats, collagen content (117.01 6.84 mg/100 mg tissue) as well as its degree of cross-linking was increased, as shown by increased extent of glycation (21.70 0.90 g glucose/mg collagen), collagen-linked fluorescence (52.8 3.0 AU/ mol hydroxyproline), shrinkage temperature (71.50 2.50 C) and decreased acid (1.878 0.062 mg hydroxyproline/100 mg tissue) and pepsin solubility (1.77 0.080 mg hydroxyproline/100 mg tissue). The alpha/ ratio of acid- (1.69) and pepsin-soluble (2.00) collagen was significantly decreased in streptozotocin-diabetic rats. Administration of P. vulgaris for 45 days to streptozotocin-diabetic rats significantly reduced the accumulation and cross-linking of collagen. The effect of P. vulgaris was compared with that of glibenclamide, a reference drug administered to streptozotocin-diabetic rats at the dose of 600 g/kg body weight for 45 days by gavage. The effects of P. vulgaris (collagen content, 64.18 1.97; extent of glycation, 12.00 0.53; collagen-linked fluorescence, 33.6 1.9; shrinkage temperature, 57.0 1.0; extent of cross-linking - acid-soluble collagen, 2.572 0.080, and pepsin-soluble collagen, 2.28 0.112) were comparable with those of glibenclamide (collagen content, 71.5 2.04; extent of glycation, 13.00 0.60; collagen-linked fluorescence, 38.9 2.0; shrinkage temperature, 59.0 1.5; extent of cross-linking - acid-soluble collagen, 2.463 0.078, and pepsin-soluble collagen, 2.17 0.104). In conclusion, administration of P. vulgaris pods had a positive influence on the content of collagen and its properties in streptozotocin-diabetic rats.

Effect of heating on pulmonary veins: how to avoid pulmonary vein stenosis

INTRODUCTION

The success of radiofrequency energy catheter ablation for the treatment of patients with paroxysmal or chronic atrial fibrillation has been complicated by postablation development of pulmonary vein (PV) stenosis. The acute effect of heat on PV structure has not been well characterized. The aim of this study was to characterize the effects of hyperthermic exposure on PVs and to determine the critical temperature at which PV stenosis would be observed.

METHODS AND RESULTS

The main PVs of acutely explanted canine hearts were identified, isolated, and dissected from the left atria. Measurements of the diameter of 3-mm PV rings were obtained at baseline and after hyperthermic exposure at 60 degrees C, 65 degrees C, 70 degrees C, and 80 degrees C. Mechanical behavior of PVs was studied by examining the stress-strain relationship of each PV specimen after heat exposure at different temperature settings. Twenty-eight PVs samples from 15 dogs (1-3 PVs/dog) were obtained and had a mean circumference of 8.7 +/- 2.3 mm at baseline. After heating to 60 degrees C, 65 degrees C, 70 degrees C, and 80 degrees C, the mean PV circumference was 9.2 +/- 2.3 mm (P = NS vs baseline), 6.8 +/- 2.3 mm (P < 0.0001), 4.2 +/- 1.5 mm (P < 0.0001), and 4.2 +/- 0.8 mm (P < 0.0001), respectively. The stress-strain curves of PV specimens were shifted to the left upon exposure to higher temperatures, indicating loss of compliance of PVs due to heat exposure. Histology showed loss of typical collagen matrix above 60 degrees C.

CONCLUSION

Significant acute heat-induced contraction of PVs at zero-tension state was observed between 60 degrees C and 65 degrees C. This change was associated with collagen denaturation.

Glenohumeral joint translation after arthroscopic thermal capsuloplasty of the rotator interval

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

Modulatory effect of Coccinia indica on aortic collagen in streptozotocin-induced diabetic rats

1. The effects of Coccinia indica, an indigenous plant used in Ayurvedic medicine in India, on aortic collagen content and its characteristics were assessed in streptozotocin (STZ) diabetic rats. 2. Rats were made diabetic with a single intraperitoneal injection of STZ (45 mg/kg). Blood glucose, hydroxyproline, collagen, extent of glycation, collagen-linked fluorescence, soluble pattern of pepsin-soluble collagen, shrinkage temperature, alpha/beta ratio of type I collagen and type I/type III collagen ratio were determined in rats treated with C. indica leaf extract (CLEt; 200 mg/kg for 45 days using an oral intragastric tube). 3. In diabetic rats, the collagen content, as well as the degree of cross-linking, was increased, as evidenced by increased shrinkage temperature and decreased pepsin solubility. The alpha/beta ratio of type I collagen and the type I/type III collagen ratio of pepsin-soluble collagen were significantly decreased in STZ diabetic rats. 4. In conclusion, administration of CLEt for 45 days to STZ diabetic rats significantly reduced the accumulation and cross-linking of collagen. The effects of C. indica (collagen content 23.87 +/- 1.52 mg/100 mg tissue (t value = 6.80), extent of cross-linking 0.893 +/- 0.072 mg hydroxyproline/100 mg tissue (t value = 9.0)) were comparable with those of glibenclamide (collagen content 26.18 +/- 1.65 mg/100 mg tissue (t value = 4.58), extent of cross-linking 0.787 +/- 0.057 mg hydroxyproline/100 mg tissue (t value = 7.1)), a reference drug.

Arthroscopic capsular shrinkage of the shoulder for the treatment of patients with multidirectional instability: Minimum 2-year follow-up

PURPOSE

The study goal was to evaluate the arthroscopic treatment of patients with multidirectional instability of the shoulder (MDI). MDI is a disabling condition as a result of pain and restriction of activity. The treatment of MDI is primarily nonsurgical (supervised physiotherapy).

TYPE OF STUDY

Prospective cohort study.

METHODS

Arthroscopic capsular shrinkage, using a bipolar radiofrequency system, was performed in 32 patients (33 shoulders). The mean age was 27 years (range, 15 to 49). The Constant score was used for assessment preoperatively and at 6-month intervals. In 8 patients, labral lesions were revealed at arthroscopy and were addressed using arthroscopic methods.

RESULTS

The follow-up was from 24 to 33 months (26 mean). Patients without labral pathology (group A) and patients with labral lesions (group B) are discussed separately. Group A showed an increase in the mean Constant score at 6 months, but the scores reached a plateau after 6 months. Statistical analysis using 1-way analysis of variance (ANOVA) showed that the mean difference between the preoperative Constant score and the score at latest follow-up was statistically significant (P <.0001; 95% confidence interval, 13.4 to 31.6; standard error, 2.2). The rate of failure or complication was 16%. Three patients experienced recurrence of instability and another developed adhesive capsulitis. Overall, patient satisfaction was 83%. Group B showed an improvement in the Constant scores, and all 8 patients were satisfied. No clinical recurrence of the instability was seen in this group. However, 1 patient developed adhesive capsulitis. This group is too small to draw any statistically valid conclusions.

CONCLUSIONS

The early results are encouraging. Postoperative physiotherapy is of paramount importance. Continued long-term follow-up of this relatively new technique is required to determine the failure rate increase that is likely to occur at longer time intervals.

Monopolar thermal treatment of symptomatic anterior cruciate ligament instability

Patients with anterior cruciate ligament instability resulting from incomplete tears or elongation in continuity without ligament detachment historically have been treated conservatively or by graft replacement. The literature is sparse regarding alternative treatments. The current study presents experience using monopolar thermal repair on 28 consecutive knees with partial anterior cruciate ligament tears all symptomatically unstable. All lesions were less than 6 months old (average, 77 days; range, 7-180 days) and with a difference of 6 mm or more (average, 9 mm; range, 6-13 mm) when comparing both knees using KT-1000 evaluation. Incomplete tears of the anterior cruciate ligament were seen at arthroscopic evaluation. The rehabilitation protocol included use of a brace for at least 6 weeks and progressive weightbearing. A 2-year minimum followup (range, 24-35 months) was done in all patients following the International Knee Documentation Committee guidelines. The overall outcome was normal or nearly normal in 96% of the patients. One failure occurred at 8 weeks. Twenty-six knees had a KT-1000 difference between 0 and 2 mm (average, 1.9 mm). Because thermal application causes death to some of the cells directly treated, it should be taken into account in selection and application. Immediately after thermal use, the anterior cruciate ligament, although thicker and tighter, is at first weaker than normal. Rehabilitation and compliance are critical during early ligament healing. This procedure seems to be a reasonable alternative to anterior cruciate ligament grafting in selected patients.

Radiofrequency treatment weakens the fatigue characteristics of rabbit anterior cruciate ligament

OBJECTIVE

To evaluate the radiofrequency treatment applied to an intact anterior cruciate ligament, and to quantify the mechanical effects of controlled cyclic loading (simulating activities of daily living) post-treatment.

DESIGN

An in vitro radiofrequency energy application to the rabbit anterior cruciate ligament and cyclic loading of the treated ligament.

BACKGROUND

Effect of cyclic loading on the radiofrequency treated ligament in a controlled environment is not known.

METHODS

In the treatment group radiofrequency treatment was applied to an intact ligament and then the ligament was cyclically loaded for 3000 cycles, and stretched-to-failure. Control group was similar to treatment, except that the radiofrequency treatment was not applied. The cyclic loading (approximately 6% tensile strain) was kept below the injury threshold of the rabbit anterior cruciate ligament and was designed to simulate loading post-treatment. A relaxation test (5% constant strain for 180 s) was used to compare the results at different steps in the experiment; within each group and between the two groups.

RESULTS

Relaxation force increased in the treatment group (average 108% of intact, P<0.05), but decreased after the cyclic loading (average 71% of intact, P<0.05). There were significant differences in the force-deformation-failure curves between the treatment and control groups: average treated ligament failed at 59% and 57% of the control values respectively for the deformation and force (P<0.05).

CONCLUSIONS

Using radiofrequency treatment makes rabbit anterior cruciate ligament weaker following cyclic loading.

RELEVANCE

The radiofrequency treatment weakens the anterior cruciate ligament, and therefore, it perhaps should be protected until healing and adaptation restore its full strength.

Laser capsulorrhaphy for multidirectional instability of the shoulder. An outcomes study and proposed classification system

BACKGROUND

Clinical data on the efficacy of laser capsulorrhaphy for the treatment of multidirectional instability of the shoulder are limited.

HYPOTHESIS

The diagnosis of multidirectional instability includes a spectrum of pathologic symptoms that warrants subclassification; laser capsulorrhaphy alone is not uniformly effective for all subtypes.

STUDY DESIGN

Retrospective review of prospectively collected data.

METHODS

Twenty-five shoulders in 21 patients were treated with laser capsulorrhaphy for multidirectional instability. Functional outcomes at a mean duration of 32 months' follow-up (range, 24 to 48 months) were recorded.

RESULTS

Instability recurred in 60% of patients with congenital multidirectional instability, 17% of patients with acquired multidirectional instability, and 33% of patients with posttraumatic multidirectional instability (overall recurrence rate, 40%). Generalized ligamentous laxity was a risk factor for recurrence. Patient satisfaction rates were 40%, 83%, and 22% for the congenital, acquired, and posttraumatic subgroups. Reasons for dissatisfaction included recurrent instability, persistent pain, and inability to return to athletic activity at desired capacity. The overall mean postoperative Simple Shoulder Test score was 84%. The mean postoperative numeric rating score for pain was 3.3 (10-point scale).

CONCLUSIONS

Laser capsulorrhaphy may be effective for patients with acquired multidirectional instability secondary to repetitive microtrauma but is less predictable in the other subgroups.

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.

Anterior cruciate ligament thermal shrinkage

Heat has been used as a therapeutic form of treatment in the field of medicine since ancient times. Electrothermal energy delivered by radiofrequency has the advantages of being able to be used by even the casual arthroscopist and being relatively inexpensive. One of the expanded uses is treating ligament laxity, including the anterior cruciate.

The basic science of thermally assisted chondroplasty

Thermal chondroplasty provides a visually enticing effect on articular cartilage, but the long-term effects of thermal modification and injury to articular cartilage must be understood before the technology is applied to cartilage and chondrocytes in a clinical setting.

Thermal treatment of anterior cruciate ligament injury and laxity with its imaging characteristics

The use of radiofrequency or laser to treat lax anterior cruciate ligaments is at its infancy. The imaging results of such treated ligaments using MRI are undocumented in the literature. This article reviews the basic science behind thermal treatment of ligaments and previously published and unpublished data on this therapy and its imaging implications.

Shoulder instability: management and rehabilitation

Shoulder dislocation and subluxation occurs frequently in athletes with peaks in the second and sixth decades. The majority (98%) of traumatic dislocations are in the anterior direction. The most frequent complication of shoulder dislocation is recurrence, a complication that occurs much more frequently in the adolescent population. The static (predominantly capsuloligamentous and labral) and dynamic (neuromuscular) restraints to shoulder instability are now well defined. Rehabilitation aims to enhance the dynamic muscular and proprioceptive restraints to shoulder instability. This paper reviews the nonoperative treatment and the postoperative management of patients with various classifications of shoulder instability.

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-assisted capsular modification for functional ankle instability

Chronic symptoms following lateral ankle sprain occasionally requires surgical intervention. Many options are available including thermal assisted capsular modification. The authors review the history of thermal modification of tissues, the indication for use in the ankle and report their experience with a consecutive case series over a one year period.

The unstable shoulder in the adolescent athlete

Shoulder dislocation and subluxation occur frequently in athletes, with peaks in the second and sixth decades. The majority of traumatic dislocations are in the anterior direction. The most frequent complication of shoulder dislocation is recurrence--a complication that occurs much more often in the adolescent population. The dynamic (muscular) and static (predominantly capsuloligamentous and labral) restraints to shoulder instability are now well defined. Recent surgical procedures for shoulder instability have become less interventional and have focused on restoring disrupted static restraints. The aim of rehabilitation is to enhance the dynamic muscular and proprioceptive restraints to shoulder instability.

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.

Radiofrequency electrothermal shrinkage of the anterior cruciate ligament

The efficacy of electrothermal collagen shrinkage in the treatment of patients with anterior cruciate ligament laxity was evaluated. Eighteen patients who had continuity of the anterior cruciate ligament but had symptomatic laxity were treated with arthroscopic electrothermal shrinkage of the anterior cruciate ligament using a monopolar radiofrequency probe. The mean length of follow-up in patients whose stability was maintained was 20.5 months. Seven of the patients had undergone previous reconstruction, four with patellar tendon graft and three with quadrupled hamstring tendon graft. Laxity was chronic in nine patients and acute in nine. The KT-1000 arthrometer results at 1 month postoperatively revealed decreased anterior excursion, with an average side-to-side difference of 1.9 mm. However, 11 patients had a failed result at an average 4.0 months. Of the seven patients with successful results, six had native ligaments and had been treated for acute laxity and one had a patellar tendon graft and had been treated for chronic laxity. Even with the short-term follow-up in our study, it is evident that thermal shrinkage using radiofrequency technology has limited application for patients with anterior cruciate ligament laxity. Although it may be useful in treating patients with an acutely injured native anterior cruciate ligament, further study is needed to see if the ligament stretches out over time or is at increased risk of reinjury.

Advances in the management of traumatic anterior and atraumatic multidirectional shoulder instability

Dislocation of the shoulder is a common and often disabling injury to an athlete. Most shoulder dislocations are traumatic in origin, occur in the anterior direction and result in stretching and detachment of the anterior capsule and labrum. The most frequent adverse sequel of shoulder dislocation is recurrence--an event that occurs most commonly in active individuals and less frequently with age. In the past, many operative procedures failed to address the anatomical disruptions of shoulder instability. Recently, an enhanced understanding of shoulder instability pathoanatomy and significant technological advances have resulted in surgical procedures for shoulder instability that are less interventional and have focused on restoring disrupted static constraints.

Creep behavior of a rabbit model of ligament laxity after electrothermal shrinkage in vivo

Deformation of capsular tissue under constant load (creep) may lead to recurrent laxity after thermal shrinkage for shoulder instability. We investigated the effects of thermal shrinkage in a rabbit model in which the tibial insertion of the medial collateral ligament was elevated and shifted toward the joint line to create abnormal laxity. On the right side, radiofrequency electrothermal energy was applied to the shifted ligament, while the left side served as a control. Length, laxity, mass, cross-sectional area, water content, and creep behavior of the ligament were assessed at 0 (N = 8), 3 (N = 7), and 12 (N = 6) weeks postoperatively. Laxity was reduced with thermal treatment (0.65 +/- 0.31 compared with 3.33 +/- 0.25 mm). After 3 weeks, ligament mass, area, and water content were significantly increased in the thermally treated group compared with the untreated controls. At 12 weeks, cyclic creep strain remained greater than that in controls (1.25% +/- 0.65% compared with 0.93% +/- 0.22%). Although thermal shrinkage reduced laxity, there was increased potential to creep and failure at low physiologic stresses. These findings suggest that loading of thermally treated tissues should be carefully controlled during the early phase of rehabilitation after surgery.

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

STUDY DESIGN

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

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

Transscleral laser thermotherapy of hamster Greene melanoma: inducing tumour necrosis without scleral damage

The feasibility of using transscleral thermotherapy (TSTT) to induce necrosis of choroidal melanoma without causing damage to the sclera was investigated. Fifty-two subcutaneously implanted hamster melanomas covered by human donor sclera were irradiated for 1 min with an 810 nm laser using a 3 mm spot diameter, with and without cooling of the scleral surface. Immediately after irradiation the temperature of the scleral surface was measured with an infrared camera. Irradiation at 2000 mW, without cooling of the sclera, resulted in tumour necrosis to a mean depth of 4.4 mm and a mean diameter of 5.5 mm, without causing damage to the scleral collagen; the surface temperature of the sclera was 44.5 degrees C, and the estimated temperature at the sclera-tumour interface was 60.1 degrees C. There was a sharp demarcation between the viable and the necrotic part of the tumour. TSTT at 2500 mW, without cooling of the sclera, caused maximal tumour necrosis to a mean depth of 5.2 mm and a mean diameter of 5.9 mm; the scleral layers adjacent to the tumour had an estimated temperature of 67.6 degrees C and showed signs of damage in 14% of the experiments. Cooling of the sclera resulted in less thermal damage to the sclera but also less tumour necrosis. Results indicate that TSTT has potential in the treatment of choroidal melanoma.

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.