Glenohumeral translation after arthroscopic thermal capsuloplasty with a radiofrequency probe

Thermal shrinkage for shoulder instability

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

ELECTRONIC SUPPLEMENTARY MATERIAL

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

Effects of capsular plication and rotator interval closure in simulated multidirectional shoulder instability

BACKGROUND

Arthroscopic treatment of multidirectional shoulder instability with use of capsular plication and rotator interval closure has been shown to be effective in several clinical studies; however, the biomechanical effects of these procedures have not been elucidated. The purpose of this study was to assess biomechanically the effect of arthroscopic capsular plication combined with rotator interval closure on rotational range of motion, humeral head position throughout rotation, and glenohumeral translation.

METHODS

Seven cadaveric shoulders were stretched to 10% beyond the maximum range of motion in 60 degrees and 0 degrees of glenohumeral abduction. Testing was performed for the intact and stretched conditions and following three sequential capsular repairs: anterior plication, posterior plication, and rotator interval closure. Rotational range of motion, humeral head position throughout the range of motion, and glenohumeral translations were measured in both positions.

RESULTS

Stretching increased the total rotational range of motion in 60 degrees and 0 degrees of abduction. After anterior plication alone, total rotation decreased significantly (p < 0.05) in both positions and was restored to the intact state. Total translation with a 20-N load increased significantly in the 60 degrees of abduction position after stretching (p = 0.03). Anterior-posterior translation decreased significantly compared with the stretched state only after all components of the repair were completed in 60 degrees of abduction (p = 0.0003 with a 15-N load and p = 0.0001 with a 20-N load). This decrease was also found to be significantly less than the intact condition (p = 0.008 with a 15-N load and p = 0.001 with a 20-N load). A similar trend in results was found with superior-inferior translations in the 0 degrees of abduction position.

CONCLUSIONS

Capsular plication alone reduces range of motion to the intact state. Reductions in translation, however, may require the addition of rotator interval closure. Changes in translation and rotation after repair are dependent on arm position. In some positions, the addition of rotator interval closure may also result in overtightening.

Electrothermal arthroscopic shoulder capsulorrhaphy: a minimum 2-year follow-up

BACKGROUND

Few studies have documented the outcomes of thermal capsulorrhaphy for shoulder instability.

PURPOSE

To examine prospective evaluate outcomes of the first 100 patients with glenohumeral instability treated with thermal capsulorrhaphy.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 1997 and 1999, 85 of 100 patients treated with thermal capsulorrhaphy for glenohumeral instability were available for review at 2-year minimum follow-up (average, 4 years). Fifty-one patients suffered from anterior instability; 24 had an associated Bankart lesion. Ten patients demonstrated posterior instability; 1 had an associated reverse Bankart lesion. Seventeen patients had multidirectional instability; 8 had an associated Bankart lesion. Seven patients demonstrated anterior and posterior instability without an inferior component; 2 had an associated Bankart lesion. Failures were defined as shoulders requiring revision stabilization (14) or with recurrent instability (18), recalcitrant pain (3), or stiffness (2).

RESULTS

Forty-eight of 85 procedures were successful, and 37 of 85 failed. For patients with anterior instability plus a Bankart lesion, 7 of 24 (26%) had failed results. For those with anterior instability without a Bankart lesion, 10 of 27 (33%) had failed results. The failure rates for posterior, multidirectional instability, and anteroposterior were 60% (6/10), 59% (10/17), and 57% (4/7), respectively. Of the 48 successes, mean preoperative American Shoulder and Elbow Surgeons score improved from 71 to 96 postoperatively, and patient satisfaction was 9.1 on a 10-point scale.

CONCLUSION

Because of the high failure rates, we now augment thermal capsulorrhaphy with capsular plication and/or rotator interval closure in cases of posterior and multidirectional instability and have lengthened the initial immobilization period to improve outcomes. Failure rates for thermal capsulorrhaphy, even with labral repairs, are high especially for shoulders with multidirectional instability and posterior instability. When procedures were successful, however, patients were very satisfied with significant improvements in American Shoulder and Elbow Surgeons scores.

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.

Stress and strain in the anterior band of the inferior glenohumeral ligament during a simulated clinical examination

The objective of this research was to predict, with a finite-element model, the stress and strain fields in the anterior band of the inferior glenohumeral ligament (AB-IGHL) during application of an anterior load with the humerus abducted. The stress and strain in the AB-IGHL were determined during a simulated simple translation test of a single intact shoulder. A 6-degree-of-freedom magnetic tracking system was used to measure the kinematics of the humerus with respect to the scapula. A clinician applied an anterior load to the humerus until a manual maximum was achieved at 60 degrees of glenohumeral abduction and 0 degrees of flexion/extension and external rotation. For the computational analysis, the experimentally measured joint kinematics were used to prescribe the motion of the humerus with respect to the scapula, whereas the material properties of the AB-IGHL were based on published experimental data. The geometry of the AB-IGHL, humerus, and scapula was acquired by use of a volumetric computed tomography scan, which was used to define the reference configuration of the AB-IGHL. Strains reached 12% along the inferior edge and 15% near the scapular insertion site at the position of maximum anterior translation. During this motion, the AB-IGHL wrapped around the humerus and transferred load to the bone via contact. Predicted values for von Mises stress in the ligament reached 4.3 MPa at the point of contact with the humeral head and 6.4 MPa near the scapular insertion site. A comparison of these results to the literature suggests that the computational approach provided reasonable predictions of fiber strain in the AB-IGHL when specimen-specific geometry and kinematics with average material properties were used. The complex stress and strain distribution throughout the AB-IGHL suggests that the continuous nature of the glenohumeral capsule should be considered in biomechanical analyses. In the future, this combined experimental and computational approach will be used for subject-specific studies of capsular function and could provide quantitative data to help surgeons improve methods for the diagnosis and treatment of glenohumeral instability.

The effects of thermal capsulorrhaphy and rotator interval closure on multidirectional laxity in the glenohumeral joint: a cadaveric biomechanical study

PURPOSE

Arthroscopic rotator interval closure has been advocated to supplement the stabilization provided by thermal capsulorrhaphy for glenohumeral instability. However, no basic science study has examined the separate and combined effects of thermal capsulorrhaphy and rotator interval closure on the multiplane laxity of the glenohumeral joint. The purpose of this study was to measure the effects of isolated and combined thermal capsulorrhaphy and rotator interval closure on anterior, posterior, and inferior glenohumeral joint laxity in a cadaveric model.

TYPE OF STUDY

Anatomic biomechanical study.

METHODS

Ten cadaveric shoulders were fixed to a biomechanical testing apparatus and 5.5 lb (25 N) of force was applied to the humeral head in anterior, posterior, and inferior directions in a random order. Translation was measured in each direction on the untreated specimen (U), after arthroscopic rotator interval closure (R), after thermal capsulorrhaphy (T), and after combined rotator interval closure and thermal capsulorrhaphy (RT) with a transducer attached to a computer via data acquisition software and A/D board. Values for anterior, posterior, and inferior translation were thus obtained for U, R, T, and RT.

RESULTS

Average translations in the anterior direction for the U, R, T, and RT groups were 8.0 +/- 4.4 mm, 6.7 +/- 3.3 mm, 8.5 +/- 3.6 mm, and 7.8 +/- 2.2 mm, respectively. Average translations in the posterior direction were 6.9 +/- 3.3 mm (U), 5.9 +/- 3.4 mm (R), 7.9 +/- 4.7 mm (T), and 6.8 +/- 4.0 mm (RT). Average translations in the inferior plane were 4.9 +/- 4.7 mm (U), 3.6 +/- 3.7 mm (R), 3.7 +/- 3.3 mm (T), and 2.4 +/- 1.6 mm (RT). Rotator interval closure decreased anterior, posterior, and inferior translation by 17%, 15%, and 28%, respectively, versus the untreated subjects. Thermal capsulorrhaphy increased anterior and posterior translation by 5% and 13% and decreased inferior translation by 25% versus untreated subjects. Combined RT decreased anterior, posterior, and inferior translation by 4%, 2%, and 52%, respectively. Statistical analysis revealed that rotator interval closure significantly decreased laxity values in all planes, whereas thermal capsulorrhaphy did not significantly alter laxity values versus untreated subjects.

CONCLUSIONS

Isolated rotator interval closure decreased glenohumeral laxity in all directions tested, particularly inferior translation. Thermal capsulorrhaphy actually increased anterior and posterior translation in these subjects while decreasing inferior translation. We believe the trends seen reflect the clinical efficacy of rotator interval closure in the treatment of multidirectional instability. This procedure has the potential to provide improved stability versus thermal capsulorrhaphy alone, and may be considered as a supplement to or substitute for thermal capsulorrhaphy in patients with multidirectional instability.

CLINICAL RELEVANCE

When treating glenohumeral instability with arthroscopic techniques, rotator interval closure may enhance stability to a greater degree than thermal capsulorrhaphy without its associated risks.

Active stability of the glenohumeral joint decreases in the apprehension position

BACKGROUND

Muscle forces that compress the glenohumeral joint during mid-ranges of motion may lead to increased translational forces in end-range positions, such as the apprehension position, where symptoms of anterior instability occur.

OBJECTIVE

The objective of this study was to quantify active stability provided by eight shoulder muscles in mid-range and end-range positions through muscle force vector analysis.

METHODS

Lines of action were derived from a geometric model and muscle force magnitudes were estimated with electromyography-based techniques. Resultant muscle force vectors were calculated by summing individual muscle force vectors.

RESULTS

Compared to mid-range positions, lines of action of resultant force vectors were more anteriorly directed in end-range positions compared to 15 degrees of abduction, up to 26 degrees. Consequently, anterior stability was lowest in the apprehension position. The magnitudes of the resultant force vectors were comparable to other studies. Based on a sensitivity analysis, lines of action of resultant force vectors vary up to 6 degrees within the population.

CONCLUSIONS

Data obtained from this model will improve conservative management, post-surgical rehabilitation, and strength training protocols.

Glenohumeral instability and dislocation

Glenohumeral joint instability and dislocations are common diagnoses seen by physicians. There are many different pathologic etiologies for these conditions. A thorough understanding of the history,physical examination, pathoanatomy, and classification systems is required to make an accurate diagnosis. With the appropriate diagnosis, the clinician can choose the correct treatment and improve the patient's outcome.

Immediate effect of thermal capsulorrhaphy on glenohumeral joint mobility

OBJECTIVES

To evaluate the effects of anterior thermal capsulorrhaphy of the glenohumeral joint by monitoring changes of magnitudes of the anterior and posterior displacements of the humeral head and ranges of motion of abduction and rotation in fresh cadaver shoulders.

DESIGN

Single session repeated-measures design.

BACKGROUND

Following thermal shrinkage anterior and posterior displacements of the head of humerus were decreased. However, no studies were focused on the ranges of motion of abduction and rotation of the shoulder joint immediately. The mobility of abduction and rotation are also important indexes for glenohumeral function.

METHODS AND MEASURES

Nine fresh frozen shoulder specimens were used. The dorsal and ventral displacements of humeral head and ranges of motion of abduction and rotation of glenohumeral joint before and after thermal capsulorrhaphy were performed and monitored. Changes after thermal treatment in these linear and angular displacement variables were calculated as outcome measures.

RESULTS

After anterior thermal capsulorrhaphy, significant (P < 0.001) decreases were found in displacements (-1.80 mm in dorsal direction and -1.24 mm in ventral direction), rotation range of motion (-3.93 degrees in lateral rotation and -2.60 degrees in medial rotation), and abduction range of motion (-3.15 degrees ).

CONCLUSIONS

The results from cadaveric experiments showed that anterior thermal capsulorrhaphy immediately reduced the dorsal and ventral displacements and ranges of abduction and rotation of glenohumeral joint by a small amount.

RELEVANCE

Radiofrequency electrosurgical system combined with arthroscopy has the potential to decrease the translations of the humeral head as well as the rotational range of motion of the glenohumeral joint.

Multidirectional kinematics of the glenohumeral joint during simulated simple translation tests: impact on clinical diagnoses

At the end ranges of motion, the glenohumeral capsule limits translation of the humeral head in multiple directions. Since the 6-degree of freedom kinematics of clinical tests are commonly utilized to diagnose shoulder injuries, the objective of this study was to determine the magnitude and repeatability of glenohumeral joint kinematics during a simulated simple anteroposterior translation test in the anterior and posterior directions. A magnetic tracking system was used to determine the kinematics of the humerus with respect to the scapula in eight cadaveric shoulders. At 60 degrees of glenohumeral abduction and 0 degrees of flexion/extension, a clinician applied anterior and posterior loads to the humerus at 0 degrees, 30 degrees, and 60 degrees of external rotation until a manual maximum (simulating a simple translation test) was achieved. Prior to each test, the reference position of the humerus shifted posteriorly 1.8+/-2.0 and 4.1+/-3.8 mm at 30 degrees and 60 degrees of external rotation, respectively. Anterior translation decreased significantly (p < 0.05) from 18.2+/-5.3 mm at 0 degrees of external rotation to 15.5+/-5.1 and 9.9+/-5.5 mm at 30 degrees and 60 degrees, respectively. However, no significant differences were detected between the posterior translations of 13.4+/-6.4, 17.1+/-5.0, and 15.8+/-6.0 mm at 0 degrees, 30 degrees, and 60 degrees of external rotation, respectively. Coupled translations (perpendicular to the direction of loading) at 0 degrees (6.1+/-4.0 and 3.8+/-2.9 mm), 30 degrees (4.7+/-2.7 and 5.9+/-3.1 mm), and 60 degrees (2.3+/-2.3 and 5.0+/-3.5 mm) of external rotation were in the inferior direction in both the anterior and posterior directions, respectively. Based on the data obtained, performing a simulated simple translation test should result in coupled inferior translations and anterior translations that are a function of external rotation. The low standard deviations demonstrate that the observed translations should be repeatable. Furthermore, capsular stretching or injury to the anterior-inferior region of the capsule should be detectable during clinical examination if excessive coupled translations exist or no posterior shift of the reference position with external rotation is noted.

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.

The effect of variation in definition on the diagnosis of multidirectional instability of the shoulder

BACKGROUND

There currently is a wide variation in the definition of multidirectional instability of the shoulder in the literature. The purpose of this study was to determine if these variations influence the distribution of the diagnoses in a cohort of patients with shoulder instability.

METHODS

A cohort of 168 patients who underwent shoulder surgery for instability of any type was studied. Statistical analysis was performed in two steps. First, the instability of the shoulder in each patient was classified with the use of four existing systems, and the number of patients classified as having multidirectional instability was compared among the classification systems. Second, the definition of multidirectional instability was modified so that the result of laxity testing was the criterion for making the diagnosis, and the changes in the distribution of patients with a diagnosis of multidirectional instability were analyzed.

RESULTS

Classification with the four existing systems resulted in significant differences in the number of patients diagnosed as having multidirectional instability, with two (1.2%), seven (4.2%), thirteen (7.7%), and fourteen patients (8.3%) so diagnosed (p < 0.05). Modification of the definition of multidirectional instability so that it was based on laxity testing resulted in a wide variation in the number of patients diagnosed as having multidirectional instability; these numbers ranged from fourteen (8.3%) to 139 (82.7%) (p < 0.05).

CONCLUSIONS

This study demonstrated that variations in the criteria used for the diagnosis of multidirectional instability significantly affect the distribution of patients with that diagnosis. The use of laxity testing tends to result in an overestimation of the number of patients with this condition. This observation is important because the results of studies may vary if patients with traumatic instability are considered to have multidirectional instability on the basis of laxity testing. Investigators studying patients with multidirectional instability should carefully define the inclusion criteria that they used.

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.

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

STUDY DESIGN

Descriptive postoperative follow-up research.

OBJECTIVES

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

BACKGROUND

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

METHODS AND MEASURES

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

RESULTS

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

CONCLUSIONS

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

Glenohumeral joint translation after arthroscopic thermal capsuloplasty of the posterior capsule

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

Glenohumeral joint translation after arthroscopic thermal capsuloplasty of the rotator interval

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

Shoulder proprioception and function following thermal capsulorraphy

PURPOSE

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

TYPE OF STUDY

Case series.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Open surgical repair restores joint forces that resist glenohumeral dislocation

Traumatic anterior shoulder instability is a clinical problem often observed in athletes participating in overhead activities. The standard treatment for this condition is surgical repair, which may be accomplished by an open or arthroscopic procedure. The current authors assessed the strength of open repair, by comparing glenohumeral joint forces in intact specimens with specimens with anterior dislocation and open repair. Eighteen shoulders from cadavers were tested on a custom shoulder dislocation device with simulated muscle forces. Bankart lesions were repaired using a three-suture anchor technique combined with capsular advancement. Capsular failures were addressed by sharp dissection of the labrum from bone, then repaired as above, and the experiment was repeated. One-way analysis of variance was used for analyses. All specimens dislocated anteroinferiorly, eight dislocated by bony Bankart failure, and 10 dislocated by capsular failure. Maximum joint compression force for the initial dislocation was 760 +/- 79 N for the specimens with Bankart failures and 690 +/- 59 N for the specimens with capsular failures. The maximum joint compression force for dislocation after repair measured 541 +/- 50 N for the specimens with Bankart failures and 536 +/- 46 N for the specimens with capsular failures. The forces after repair were normalized with respect to the intact shoulders. For specimens with Bankart failures, joint compression and pectoralis major forces were 72% and 62%, respectively, and 79% and 61% for specimens with capsular failures. A three-dimensional digitizing system confirmed restoration of glenohumeral position. These results support clinical data, showing that open Bankart repair adequately restores the static restraints of the glenohumeral joint that resist anteroinferior dislocation.

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

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