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Arthroscopic capsular shrinkage of the shoulder for the treatment of patients with multidirectional instability: Minimum 2-year follow-up
Arthroscopic Capsular Shrinkage of the Shoulder for the Treatment of Patients With Multidirectional Instability: Minimum 2-Year Follow-Up Simon P. Frostick, D.M., F.R.C.S., Christos Sinopidis, M.D., Sultan Al Maskari F.R.C.S., Ed.(Tr.&Orth.), Jo Gibson, M.C.S.P., S.R.P., Graham J. Kemp, D.M., M.R.C.Path., and John C. Richmond, M.D.
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. Key Words: Multidirectional—Instability—Bipolar—Capsular—Shrinkage.
M
ultidirectional instability (MDI) of the shoulder is a disabling condition because of resulting pain and restricted activity. Frequently, the condition
From the Department of Musculoskeletal Science, Royal Liverpool University Hospital (S.P.F., C.S., S.A, J.G., G.J.K.), Liverpool, England; and New England Medical Center (J.C.R.), Boston, Massachusetts, U.S.A. Address correspondence and reprint requests to Simon P. Frostick, D.M., F.R.C.S., Professor of Orthopaedics and Head of Department of Musculoskeletal Science, R. L. U. H., Liverpool L69 3GA, England. E-mail: [email protected] © 2003 by the Arthroscopy Association of North America 0749-8063/03/1903-3044$30.00/0 doi:10.1053/jars.2003.50034
is misdiagnosed and treated inappropriately. The treatment of MDI is primarily nonsurgical1 (supervised physiotherapy), with a success rate of 80%. In 1980, Neer and Foster2 were the first to propose the term multidirectional instability. They proposed the anteroinferior capsular shift as the operative procedure of choice to deal with this difficult condition. Since then, many modifications to the original procedure have been proposed.3,4 The anteroinferior capsular shift has a variable failure rate (4% to 39%) in the medium term, and researchers expect the failure rate to increase with longer follow-up.5 More recently, arthroscopic treatment of MDI has become increasingly popular.6 The
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 227-233
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goal of this technique is to reduce capsular redundancy using arthroscopic surgery. This can be achieved either using multiple arthroscopic knots7 with or without suture anchors, known as capsular plication,8 or using arthroscopic capsular shrinkage. The latter technique is based on the application of heat to the joint capsule through laser or radiofrequency devices. Although a number of studies have been performed on animals regarding structural and biomechanical changes of the capsule,9-13 no clinical studies have been performed to justify the use of this method in MDI. In this article, we present the short-term (minimum 2 years) results of a prospective study evaluating the clinical outcome of arthroscopic capsular shrinkage. In this study, we used a bipolar radiofrequency device in patients with MDI for whom a structured rehabilitation program failed. METHODS In this study, 32 patients (33 shoulders) with MDI, in 2 centers, were treated using arthroscopic capsular shrinkage. Patients included 9 women and girls and 23 men and boys with a mean age of 27 years (range, 15 to 49 years). One patient underwent arthroscopic treatment in both shoulders. Of the 32 patients, 29 were actively participating in sports, 7 at a competitive level (3 baseball players, 2 tennis players, 1 ice hockey player, and 1 gymnast). Thirteen patients complained of activity-related pain only; symptoms of instability were the predominant feature in 8 patients; and 11 had equally painful and unstable shoulders. The senior authors (S.P.F, J.C.R.) confirmed the diagnosis of MDI in all patients. A positive sulcus sign associated with pain was present in all patients. Eighteen patients also experienced generalized hyperlaxity as defined by the criteria of Carter and Wilkinson.14 Using the modified Hawkins’s classification,15 we found the direction of instability to be global in 28 patients, posteroinferior in 1 patient, and multidirectional with primary anteroinferior instability in 3 patients. These 3 patients had had documented anterior dislocation. Twelve patients related the onset of symptoms to an episode of trauma; 8 with overuse. The remaining patients did not report any specific episodes of trauma. All patients had undergone a supervised rehabilitation program for at least 6 months before surgery without improvement. Exclusion criteria from this study included known history of neurologic disorders affecting the shoulder (eg, transverse myelitis),
TABLE 1. Parameters of Constant Score Parameter
Points
PAIN None Mild Moderate Severe ROM Forward elevation: 0-30° 31-60° 61-90° 91-120° 121-150° 151-180° Lateral elevation: 0-30° 31-60° 61-90° 91-120° 121-150° 151-180° External rotation: Back of head/elbow forward Back of head/elbow back Top of head/elbow forward Back of head/elbow back Full elevation Internal rotation: Dorsum hand to side of thigh Dorsum hand to buttock Dorsum hand to sacroiliac joint Dorsum hand to waist Dorsum hand to T12 Dorsum hand to interscapular POWER measured in kg ADL Full work Full leisure or sport Undisturbed sleep Positioning: Below waist Waist to xiphoid Xiphoid to neck Neck to top of head Above head
15 15 10 5 0 40 0 2 4 6 8 10 0 2 4 6 8 10 2 4 6 8 10 0 2 4 6 8 10 25 20 4 4 2 2 4 6 8 10
NOTE. Maximum score ⫽ 100 points.
chronic dislocation because of nonadherence, and previous surgery on the same shoulder. This last criterion was because of the resultant alterations in the type and quality of collagen. The Constant functional score16 (Table 1), which incorporates various individual parameters, including pain, activities of daily living (ADL), and range of motion and power, was documented for all patients preoperatively and postoperatively at 6-month intervals.
ARTHROSCOPIC CAPSULAR SHRINKAGE OF THE SHOULDER Nine patients underwent surgery as outpatients and the rest had an overnight stay in the hospital. Surgery was performed under general anesthesia. Beach chair position with the arm resting on a Mayo table in 30° of abduction or 20° of forward flexion or lateral decubitus position were used, according to the preference of the surgeon. For patients in the lateral position, the arm was positioned in 30° of abduction and 20° of forward flexion, using the minimum weight necessary to suspend the arm. This ranged between 3 and 6 kg, depending on patient size. All patients underwent an examination under anesthesia and routine arthroscopic assessment using a 3-portal technique. After the findings were documented, arthroscopic capsular shrinkage was performed with a bipolar radiofrequency device (Mitek VAPR, Mitek Surgical Products, Westwood, MA). Standard angled side effect and end effect probes were used, with the power set at 30 W (blue pedal). To perform shrinkage, first the posterior capsule was treated (from the 8-o’clock position), then, moving anteriorly, the inferior recess and the anterior capsule to a level just inferior to the subscapularis tendon were treated. Some variations were used, depending on individual patients. When a labral repair was required, first the posterior and inferior capsule were treated with shrinkage, then labral repair was performed, and the anterior capsule was treated last. The probe was applied until visual discoloration and shrinkage occurred, with a continuous paintbrush movement along the fibers of the capsule. Static application of the probe was avoided to prevent thermal damage to the tissues underlying the capsule, especially the axillary nerve.17 The limb was immobilized in a poly-sling for 3 weeks. Patients were discharged the day after surgery with appropriate physiotherapy and exercise instructions. Rehabilitation Program The postoperative rehabilitation program (Table 2) was developed using regular review of current scientific research and ongoing clinical experience. Our guidelines are intended as exactly that, and each patient’s case must be considered independently. The basic principles of the rehabilitation program are to protect the healing of soft tissues, prevent the negative effects of immobilization, re-establish dynamic joint stability, diminish postoperative pain and inflammation, and allow the patient to return to function. All patients undergoing capsular shrinkage also undergo preoperative physiotherapy and should be aware of
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TABLE 2. Rehabilitation Program Preoperative Scapula control program Glenohumeral control exercises Check core stability Submaximal rotator cuff exercises Weeks 3 to 6 Initiation of active/active-assisted mobilization Progress scapular stabilizer program Glenohumeral control exercises Facilitate optimal movement pattern Proprioceptive re-education No combined external rotation/abduction Weeks 6 to 12 Progress dynamic scapula control Functional rehabilitation—emphasis on ‘correct’ movement pattern Combined external rotation/abduction Rotator cuff conditioning Enhance neuromuscular control and endurance
scapula and glenohumeral joint control. Patients should be educated on the importance of the dynamic stabilizers to ensure a successful operative outcome. In the immediate postoperative phase, patients are immobilized in a poly-sling. They are encouraged to continue scapula-control exercises in the neutral and to perform submaximal isometric rotator cuff exercises in a position that minimizes excess stress on the capsule. This helps prevent muscular atrophy and loss of motor control. Patients are evaluated in the clinic 2 weeks after surgery, and if pain is a significant factor or marked restriction of passive range of motion is seen (less than 50%), outpatient physiotherapy is begun. In the absence of these criteria, the patient remains in the sling for a further week. (It is our experience that the rare patients who present with increased pain and grossly restricted passive range of motion are more likely to develop postoperative stiffness if mobilization is not begun.) At 3 weeks after surgery, the patient begins rehabilitation to regain range of motion. The primary emphasis is on active and active-assisted mobilization. However, it is essential in this phase to ensure that the patient has adequate neuro-muscular control and dynamic stability. The rate of progression is determined by the individual patient and ensuring adequate control of pain and inflammation to optimize adherence is important. In some patients, passive mobilization by the physiotherapist is necessary to optimize range of motion recovery; however, in view of the histologic effects of thermal capsular shrinkage, it may be advisable to avoid aggressive mobilization until 6 weeks
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after surgery. Facilitation of good movement control is vital. Once the patient has regained a full functional range of motion and exhibits both good static stability on clinical examination and good dynamic stability, functional re-education can begin. The patient must be re-educated in muscular balance and dynamic control before beginning any sport-specific or repeated overhead activities. Proprioceptive training is an important component of this process. Enhancing endurance and neuromuscular control with more advanced rehabilitation and ensuring that the patient maintains flexibility are necessary for optimal surgical outcome. In our study, postoperative rehabilitation usually lasted 6 months. At this stage, patients were advised to continue their own home exercises indefinitely. Full activities were allowed after 4 months. The patients were strongly advised that long-term success was substantially related to the continuation of the rehabilitation program. Statistical Methods Time-dependent series were analyzed using 1-way analysis of variance (ANOVA). Using the Scheffe multiple comparisons test (Arcus Quickstat 1.1, Research Solutions Cambridge, http://www.camcode.com), the significance of the differences in Constant scores between the preoperative score and the scores at 6, 12, 18, and 24 months were analyzed. Changes in external rotation were calculated using the 1-sample t-test. RESULTS Operative Findings A capacious stretched capsule was noticed at surgery, and an easy drive-through sign was present in all the patients. This was accomplished without traction in the surgical positions described before. The capsule
FIGURE 1. The Constant scores at various assessments intervals for group A. The bars indicate standard deviation.
was found to be of increased volume in all patients. Although this finding is well known in patients with MDI, and studies have been performed to assess the reduction of capsular volume before and after inferior capsular shift,18 there is no objective way to assess the capsular volume arthroscopically. Therefore, this finding was based on the experience of the senior authors. Eight patients had additional labral pathology. The details of this group are presented separately. The follow-up period for both groups was from 24 to 33 months (mean 26 months). Patients With No Labral Pathology Group A consisted of patients with no labral pathology. This group included 24 patients (25 shoulders) who had MDI with no other pathology. Constant Score: Patients showed an increase in the mean Constant score from 58.6 points preoperatively (range, 34 to 82; standard error [SE], 2.4) to 81.0 points at 2 years (range, 55 to 100; SE, 2.1) (Fig 1). ANOVA showed significant time dependence of the Constant scores. As can be seen in Table 3, the mean differences between the preoperative scores and those at 6, 12, 18, and 24 months (Fig 2) were highly
TABLE 3. Summary of Statistical Analysis of the Difference in Constant Scores Between the Preoperative Score and the Various Assessments Intervals for Group A Assessment Interval
Mean Constant Score (range)
Mean Difference (⫾ SE)
P Value
95% Confidence Interval
Preo score 6 mo 12 mo 18 mo 24 mo
58.6 (34-82) 76.1 (54-90) 76.1 (58-95) 76.8 (54-100) 81.0 (55-100)
11.6 (2.1) 17.6 (2.3) 18.2 (2.3) 22.5 (2.2)
.0049 ⬍.0001 ⬍.0001 ⬍.0001
2.4 to 20.7 8.4 to 26.7 9.1 to 27.4 13.4 to 31.6
Significance Significant Significant Significant Significant
ARTHROSCOPIC CAPSULAR SHRINKAGE OF THE SHOULDER
FIGURE 2. The mean difference in Constant scores between various assessment intervals and preoperative score for group A. Bars show standard deviation for mean difference.
significant (variance ratio, F ⫽ 17.9; P ⬍ .0001). The progress of the individual components of the Constant score for this group is shown in Fig 3. It seems that pain, power, and ADLs follow similar recovery patterns, whereas range of motion seems to follow a different course. This may be a reflection of the fact that the most prominent symptom in MDI patients is pain, which would have a limiting effect on power and ADL. External Rotation: This was assessed separately only twice, preoperatively and at 2 years after surgery. The mean difference between the 2 assessments was ⫺1.2, which is not significant (P ⬎ .68). Patient Satisfaction: Fourteen patients (58%) were satisfied with their result. Six (25%) were satisfied with the symptomatic improvement but believed that their expectations from the procedure were not entirely fulfilled. Four (17%) did not believe that the procedure provided benefit. However, none of these believed that they were worse off as a result of the surgery. Failure of Surgery: Three patients in group A experienced recurrence of instability with either a positive sulcus sign or drawer tests. One of these patients also experienced pain recurrence. Additionally, one of these patients underwent additional arthroscopic shrinkage of the posterior capsule that was omitted in the primary procedure. The other 2 patients refused further surgery.
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remaining 4, the onset was related with overuse. Four patients showed signs of increased laxity affecting the contralateral asymptomatic shoulder. The direction of the instability was global in 6 patients and multidirectional with primary anteroinferior direction in 2. Six Bankart and 2 SLAP lesions were found at surgery. As well as capsular shrinkage, arthroscopic repair with suture anchors was performed in 7 lesions and debridement was performed in 1 SLAP lesion. Constant Score: The average preoperative Constant score was 73.4. At 6 months, this had deteriorated to 72.1, but it showed gradual improvement thereafter to a mean Constant score of 91.4 at 2 years. Using the Scheffe multiple comparisons test, no statistically significant difference was found in the scores. However, this group is too small to draw any statistically valid conclusions. All 8 patients were satisfied with the procedure. This group did not include any treatment failures. Complications Two patients developed adhesive capsulitis (1 from group A and 1 from group B). The patient from group A was treated with physiotherapy alone, and the other (group B) required arthroscopic release of the coracohumeral ligament. Both patients regained full range of motion at 2 years but had to alter their sporting activities. No infections, wound healing problems, or neurologic or vascular complications were seen. Particularly, no deficit in the axillary nerve function was found.
Patients With MDI and Labral Pathology Labral pathology was found in 8 patients, 6 men and 2 women. Two of these patients had experienced a documented anterior dislocation of the shoulder in the past, 2 had no history of trauma, and in the
FIGURE 3. The various components of the Constant score at various assessment intervals for group A.
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S. P. FROSTICK ET AL. DISCUSSION
Capsular shrinkage is purely the result of application of heat on collagen.9 The molecular mechanism is unknown, but collagen denaturation is the main ultrastructural change.10 The temperature at which significant shrinkage occurs is 65°C or greater. The amount of shrinkage achieved is time- and energy-transfer– dependent. The tissue stiffness is significantly decreased at 2 weeks after surgery but returns to normal levels between 6 and 12 weeks.19 Therefore, immobilization in a sling for 3 weeks after surgery is required. During the postoperative period, the capsular collagen remodels.20 Capsular shrinkage is used to address capsular laxity during arthroscopic stabilization of the shoulder.21 Labral lesions discovered during arthroscopy should be treated arthroscopically even in patients with no history of previous frank dislocation. A surgeon should undertake capsular shrinkage only if he is familiar with arthroscopic stabilization of the shoulder. Group A Our study showed a highly statistically significant improvement in the mean Constant score for patients in the first 6 months. Thereafter, the rate of improvement tends to plateau. Four patients showed a decline in the Constant score at 6 months; however, they showed gradual improvement with rehabilitation. The main reason for their lower scores is restricted range of motion. Intensive rehabilitation is mandatory for a successful outcome. Looking at the components of the Constant score individually over 2 years, pain improvement seemed to be followed by improvement in power and ADL. The range of motion followed a separate course. External rotation was not changed significantly. The short-term (2-year) failure rate for patients with MDI without a labral lesion (12%) in this study compares favorably with figures reported for open capsular shift. Pollock et al.4 reported a 4% failure rate after open inferior capsular shift with an average follow-up of 61 months. When pain is considered as an outcome measure, the figure then increased to 33%. In this group, the overall failure and complication rate is 16%. However, this reflects the steep learning curve required to master the technique and judgment on the extent of shrinkage required. Overall patient satisfaction was 83%. Even patients who had to alter their activities stated that they would have the procedure again should their original symptoms recur.
Group B We included 8 patients in the study because they fulfilled the criteria for multidirectional instability2; all of them had a positive sulcus sign that was reproducing their symptoms, and they were subluxating in all 3 directions (anterior, posterior, and inferior). Our findings regarding the presence of labral lesions in patients with MDI correlate with previous studies.2,4 However, we present them separately to isolate the effect of the shrinkage. Although Constant scores improved for all patients and all patients were satisfied, with no clinical recurrence of the instability, this group is too small to draw any statistically valid conclusions. Arthroscopic capsular shrinkage has all the attractions of minimally invasive surgery, namely, small incisions, less soft tissue damage, shorter hospital stay, and faster rehabilitation. We must, however, state that it is not entirely free of complications. Marked stiffness can occur in some patients (2° adhesive capsulitis). The axillary nerve is also at risk of electrothermal damage when the inferior capsule is treated. Electrical activity changes have been documented through surface electrodes when the inferior part of the capsule is shrinking.22 However, it should be stressed that the use of a bipolar system has not been associated with any reported axillary nerve damage. Capsular disruption has also been reported after shrinkage,23 especially during the early postoperative period when the biomechanical properties of the collagen are altered.19 To prevent this complication, the rehabilitation program should be balanced, protecting healing soft tissues and preventing the negative effects of immobilization. In conclusion, the early results are encouraging. Adequate physiotherapy remains the treatment of choice for MDI. Only patients who do not show response (20% of our patients) after at least 6 months of appropriate rehabilitation require surgical treatment. The physiotherapist’s role in arthroscopic capsular shrinkage is critical to a successful outcome. Patient selection is equally important. Patient expectations and the need for adherence with the rehabilitation regimen must be fully discussed before surgery. Continued long-term follow-up of this relatively new technique is required to determine whether and how the failure rate increases at longer time intervals. REFERENCES 1. Gibson JC, Frostick SP. Efficacy of a muscle imbalance program in the treatment of multidirectional instability of the
ARTHROSCOPIC CAPSULAR SHRINKAGE OF THE SHOULDER
2. 3.
4.
5. 6. 7.
8. 9. 10.
11. 12.
shoulder. Proceedings of the 7th International Congress on Surgery of the Shoulder, Sydney, Australia, October 1998. Neer CS II, Foster CR. Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder: A preliminary report. J Bone Joint Surg Am 1980;62:897-908. Steinbeck J, Jerosch J. Surgery for atraumatic antero-inferior shoulder instability: A modified capsular shift evaluated in 20 patients followed for 3 years. Acta Orthop Scand 1997;68:447450. Pollock RG, Owens JM, Flatow EL, Bigliani LU. Operative results of the inferior capsular shift procedure for multidirectional instability of the shoulder. J Bone Joint Surg Am 2000; 82:919-928. Hawkins RJ, Abrams JS, Schutte J. Multidirectional instability of the shoulder: An approach to diagnosis. Orthop Trans 1987;11:246. Anderson K, McCarty EC, Warren RF. Thermal capsulorrhaphy: Where are we today? Sports Med Arthrosc Rev 1999;7: 1017-1027. McIntyre LF, Caspari RB, Savoie FH III. The arthroscopic treatment of multidirectional shoulder instability: Two-year results of a multiple suture technique. Arthroscopy 1997;13: 418-425. Wolf EM, Eakin CL. Arthroscopic capsular plication for posterior shoulder instability. Arthroscopy 1998;14:153-163. Obrzut BS, Hecht P, Hayashi K, et al. The effect of radiofrequency energy on the length and temperature properties of the glenohumeral joint capsule. Arthroscopy 1998;14:395-400. Naseef GS III, Foster TE, Trauner K, et al. The thermal properties of bovine joint capsule. The basic science of laserand radiofrequency-induced capsular shrinkage. Am J Sports Med 1997;25:670-674. Vangsness CT, Mitchel III, Nimni M, et al. Collagen shortening: An experimental approach with heat. Clin Orthop 1997; 337:267-271. Hayashi K, Markel MD, Thabit III, et al. The effect of non-
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ablative laser energy on joint capsular properties. Am J Sports Med 1995;23:482-487. Selecky MT, Vangsness CT, Liao WL, et al. The effects of laser-induced collagen shortening on the biomechanical properties of the inferior glenohumeral ligament complex. Am J Sports Med 1999;27:168-172. Carter C, Wilkinson J. Persistent joint laxity and congenital dislocation of the hip. J Bone Joint Surg Br 1964;46:40-45. Mallon WJ, Speer KP. Multidirectional instability: Current concepts. J Shoulder Elbow Surg 1995;4:54-64. Constant CR, Murley AHG. A clinical method of functional assessment of the shoulder. Clin Orthop 1987;214:160-164. Uno A, Bain GI, Mehta JA. Arthroscopic relationship of the axillary nerve to the shoulder joint capsule: An anatomic study. J Shoulder Elbow Surg 1999;8:226-230. Lubowitz J, Bartolozzi A, Rubinstein D, et al: How much does inferior capsular shift reduce shoulder volume? Clin Orthop 1996;328:86-90. Hecht P, Hayashi K, Lu Y, et al. An in vivo mechanical, morphological, and biomechanical study using an ovine model. Am J Sports Med 1999;27:761-771. Hayashi K, Massa KL, Thabit III, et al. Histologic evaluation of the glenohumeral joint capsule after the laser-assisted capsular shift procedure for glenohumeral instability. Am J Sports Med 1999;27:162-167. Hawkins RJ. Anterior shoulder instability plus thermal shrinkage capsulorrhaphy with without Bankart lesion: The role of rehabilitation and immobilization. Presented at the 67th Annual Meeting of the American Academy of Orthopaedic Surgeons, Orlando, FL, March 2000 (abstr). Hughes PJ, Hoad-Reddick A, Hovey C, et al. Does radiofrequency capsular shrinkage compromise axillary nerve function. Proceedings of the 8th International Congress on Surgery of the Shoulder, Cape Town, South Africa, April 2001. Rath E, Richmond JC. Capsular disruption as a complication of thermal alteration of the glenohumeral capsule. Arthroscopy 2001;17:E10.
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. Key Words: Multidirectional—Instability—Bipolar—Capsular—Shrinkage.
M
ultidirectional instability (MDI) of the shoulder is a disabling condition because of resulting pain and restricted activity. Frequently, the condition
From the Department of Musculoskeletal Science, Royal Liverpool University Hospital (S.P.F., C.S., S.A, J.G., G.J.K.), Liverpool, England; and New England Medical Center (J.C.R.), Boston, Massachusetts, U.S.A. Address correspondence and reprint requests to Simon P. Frostick, D.M., F.R.C.S., Professor of Orthopaedics and Head of Department of Musculoskeletal Science, R. L. U. H., Liverpool L69 3GA, England. E-mail: [email protected] © 2003 by the Arthroscopy Association of North America 0749-8063/03/1903-3044$30.00/0 doi:10.1053/jars.2003.50034
is misdiagnosed and treated inappropriately. The treatment of MDI is primarily nonsurgical1 (supervised physiotherapy), with a success rate of 80%. In 1980, Neer and Foster2 were the first to propose the term multidirectional instability. They proposed the anteroinferior capsular shift as the operative procedure of choice to deal with this difficult condition. Since then, many modifications to the original procedure have been proposed.3,4 The anteroinferior capsular shift has a variable failure rate (4% to 39%) in the medium term, and researchers expect the failure rate to increase with longer follow-up.5 More recently, arthroscopic treatment of MDI has become increasingly popular.6 The
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp 227-233
227
228
S. P. FROSTICK ET AL.
goal of this technique is to reduce capsular redundancy using arthroscopic surgery. This can be achieved either using multiple arthroscopic knots7 with or without suture anchors, known as capsular plication,8 or using arthroscopic capsular shrinkage. The latter technique is based on the application of heat to the joint capsule through laser or radiofrequency devices. Although a number of studies have been performed on animals regarding structural and biomechanical changes of the capsule,9-13 no clinical studies have been performed to justify the use of this method in MDI. In this article, we present the short-term (minimum 2 years) results of a prospective study evaluating the clinical outcome of arthroscopic capsular shrinkage. In this study, we used a bipolar radiofrequency device in patients with MDI for whom a structured rehabilitation program failed. METHODS In this study, 32 patients (33 shoulders) with MDI, in 2 centers, were treated using arthroscopic capsular shrinkage. Patients included 9 women and girls and 23 men and boys with a mean age of 27 years (range, 15 to 49 years). One patient underwent arthroscopic treatment in both shoulders. Of the 32 patients, 29 were actively participating in sports, 7 at a competitive level (3 baseball players, 2 tennis players, 1 ice hockey player, and 1 gymnast). Thirteen patients complained of activity-related pain only; symptoms of instability were the predominant feature in 8 patients; and 11 had equally painful and unstable shoulders. The senior authors (S.P.F, J.C.R.) confirmed the diagnosis of MDI in all patients. A positive sulcus sign associated with pain was present in all patients. Eighteen patients also experienced generalized hyperlaxity as defined by the criteria of Carter and Wilkinson.14 Using the modified Hawkins’s classification,15 we found the direction of instability to be global in 28 patients, posteroinferior in 1 patient, and multidirectional with primary anteroinferior instability in 3 patients. These 3 patients had had documented anterior dislocation. Twelve patients related the onset of symptoms to an episode of trauma; 8 with overuse. The remaining patients did not report any specific episodes of trauma. All patients had undergone a supervised rehabilitation program for at least 6 months before surgery without improvement. Exclusion criteria from this study included known history of neurologic disorders affecting the shoulder (eg, transverse myelitis),
TABLE 1. Parameters of Constant Score Parameter
Points
PAIN None Mild Moderate Severe ROM Forward elevation: 0-30° 31-60° 61-90° 91-120° 121-150° 151-180° Lateral elevation: 0-30° 31-60° 61-90° 91-120° 121-150° 151-180° External rotation: Back of head/elbow forward Back of head/elbow back Top of head/elbow forward Back of head/elbow back Full elevation Internal rotation: Dorsum hand to side of thigh Dorsum hand to buttock Dorsum hand to sacroiliac joint Dorsum hand to waist Dorsum hand to T12 Dorsum hand to interscapular POWER measured in kg ADL Full work Full leisure or sport Undisturbed sleep Positioning: Below waist Waist to xiphoid Xiphoid to neck Neck to top of head Above head
15 15 10 5 0 40 0 2 4 6 8 10 0 2 4 6 8 10 2 4 6 8 10 0 2 4 6 8 10 25 20 4 4 2 2 4 6 8 10
NOTE. Maximum score ⫽ 100 points.
chronic dislocation because of nonadherence, and previous surgery on the same shoulder. This last criterion was because of the resultant alterations in the type and quality of collagen. The Constant functional score16 (Table 1), which incorporates various individual parameters, including pain, activities of daily living (ADL), and range of motion and power, was documented for all patients preoperatively and postoperatively at 6-month intervals.
ARTHROSCOPIC CAPSULAR SHRINKAGE OF THE SHOULDER Nine patients underwent surgery as outpatients and the rest had an overnight stay in the hospital. Surgery was performed under general anesthesia. Beach chair position with the arm resting on a Mayo table in 30° of abduction or 20° of forward flexion or lateral decubitus position were used, according to the preference of the surgeon. For patients in the lateral position, the arm was positioned in 30° of abduction and 20° of forward flexion, using the minimum weight necessary to suspend the arm. This ranged between 3 and 6 kg, depending on patient size. All patients underwent an examination under anesthesia and routine arthroscopic assessment using a 3-portal technique. After the findings were documented, arthroscopic capsular shrinkage was performed with a bipolar radiofrequency device (Mitek VAPR, Mitek Surgical Products, Westwood, MA). Standard angled side effect and end effect probes were used, with the power set at 30 W (blue pedal). To perform shrinkage, first the posterior capsule was treated (from the 8-o’clock position), then, moving anteriorly, the inferior recess and the anterior capsule to a level just inferior to the subscapularis tendon were treated. Some variations were used, depending on individual patients. When a labral repair was required, first the posterior and inferior capsule were treated with shrinkage, then labral repair was performed, and the anterior capsule was treated last. The probe was applied until visual discoloration and shrinkage occurred, with a continuous paintbrush movement along the fibers of the capsule. Static application of the probe was avoided to prevent thermal damage to the tissues underlying the capsule, especially the axillary nerve.17 The limb was immobilized in a poly-sling for 3 weeks. Patients were discharged the day after surgery with appropriate physiotherapy and exercise instructions. Rehabilitation Program The postoperative rehabilitation program (Table 2) was developed using regular review of current scientific research and ongoing clinical experience. Our guidelines are intended as exactly that, and each patient’s case must be considered independently. The basic principles of the rehabilitation program are to protect the healing of soft tissues, prevent the negative effects of immobilization, re-establish dynamic joint stability, diminish postoperative pain and inflammation, and allow the patient to return to function. All patients undergoing capsular shrinkage also undergo preoperative physiotherapy and should be aware of
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TABLE 2. Rehabilitation Program Preoperative Scapula control program Glenohumeral control exercises Check core stability Submaximal rotator cuff exercises Weeks 3 to 6 Initiation of active/active-assisted mobilization Progress scapular stabilizer program Glenohumeral control exercises Facilitate optimal movement pattern Proprioceptive re-education No combined external rotation/abduction Weeks 6 to 12 Progress dynamic scapula control Functional rehabilitation—emphasis on ‘correct’ movement pattern Combined external rotation/abduction Rotator cuff conditioning Enhance neuromuscular control and endurance
scapula and glenohumeral joint control. Patients should be educated on the importance of the dynamic stabilizers to ensure a successful operative outcome. In the immediate postoperative phase, patients are immobilized in a poly-sling. They are encouraged to continue scapula-control exercises in the neutral and to perform submaximal isometric rotator cuff exercises in a position that minimizes excess stress on the capsule. This helps prevent muscular atrophy and loss of motor control. Patients are evaluated in the clinic 2 weeks after surgery, and if pain is a significant factor or marked restriction of passive range of motion is seen (less than 50%), outpatient physiotherapy is begun. In the absence of these criteria, the patient remains in the sling for a further week. (It is our experience that the rare patients who present with increased pain and grossly restricted passive range of motion are more likely to develop postoperative stiffness if mobilization is not begun.) At 3 weeks after surgery, the patient begins rehabilitation to regain range of motion. The primary emphasis is on active and active-assisted mobilization. However, it is essential in this phase to ensure that the patient has adequate neuro-muscular control and dynamic stability. The rate of progression is determined by the individual patient and ensuring adequate control of pain and inflammation to optimize adherence is important. In some patients, passive mobilization by the physiotherapist is necessary to optimize range of motion recovery; however, in view of the histologic effects of thermal capsular shrinkage, it may be advisable to avoid aggressive mobilization until 6 weeks
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after surgery. Facilitation of good movement control is vital. Once the patient has regained a full functional range of motion and exhibits both good static stability on clinical examination and good dynamic stability, functional re-education can begin. The patient must be re-educated in muscular balance and dynamic control before beginning any sport-specific or repeated overhead activities. Proprioceptive training is an important component of this process. Enhancing endurance and neuromuscular control with more advanced rehabilitation and ensuring that the patient maintains flexibility are necessary for optimal surgical outcome. In our study, postoperative rehabilitation usually lasted 6 months. At this stage, patients were advised to continue their own home exercises indefinitely. Full activities were allowed after 4 months. The patients were strongly advised that long-term success was substantially related to the continuation of the rehabilitation program. Statistical Methods Time-dependent series were analyzed using 1-way analysis of variance (ANOVA). Using the Scheffe multiple comparisons test (Arcus Quickstat 1.1, Research Solutions Cambridge, http://www.camcode.com), the significance of the differences in Constant scores between the preoperative score and the scores at 6, 12, 18, and 24 months were analyzed. Changes in external rotation were calculated using the 1-sample t-test. RESULTS Operative Findings A capacious stretched capsule was noticed at surgery, and an easy drive-through sign was present in all the patients. This was accomplished without traction in the surgical positions described before. The capsule
FIGURE 1. The Constant scores at various assessments intervals for group A. The bars indicate standard deviation.
was found to be of increased volume in all patients. Although this finding is well known in patients with MDI, and studies have been performed to assess the reduction of capsular volume before and after inferior capsular shift,18 there is no objective way to assess the capsular volume arthroscopically. Therefore, this finding was based on the experience of the senior authors. Eight patients had additional labral pathology. The details of this group are presented separately. The follow-up period for both groups was from 24 to 33 months (mean 26 months). Patients With No Labral Pathology Group A consisted of patients with no labral pathology. This group included 24 patients (25 shoulders) who had MDI with no other pathology. Constant Score: Patients showed an increase in the mean Constant score from 58.6 points preoperatively (range, 34 to 82; standard error [SE], 2.4) to 81.0 points at 2 years (range, 55 to 100; SE, 2.1) (Fig 1). ANOVA showed significant time dependence of the Constant scores. As can be seen in Table 3, the mean differences between the preoperative scores and those at 6, 12, 18, and 24 months (Fig 2) were highly
TABLE 3. Summary of Statistical Analysis of the Difference in Constant Scores Between the Preoperative Score and the Various Assessments Intervals for Group A Assessment Interval
Mean Constant Score (range)
Mean Difference (⫾ SE)
P Value
95% Confidence Interval
Preo score 6 mo 12 mo 18 mo 24 mo
58.6 (34-82) 76.1 (54-90) 76.1 (58-95) 76.8 (54-100) 81.0 (55-100)
11.6 (2.1) 17.6 (2.3) 18.2 (2.3) 22.5 (2.2)
.0049 ⬍.0001 ⬍.0001 ⬍.0001
2.4 to 20.7 8.4 to 26.7 9.1 to 27.4 13.4 to 31.6
Significance Significant Significant Significant Significant
ARTHROSCOPIC CAPSULAR SHRINKAGE OF THE SHOULDER
FIGURE 2. The mean difference in Constant scores between various assessment intervals and preoperative score for group A. Bars show standard deviation for mean difference.
significant (variance ratio, F ⫽ 17.9; P ⬍ .0001). The progress of the individual components of the Constant score for this group is shown in Fig 3. It seems that pain, power, and ADLs follow similar recovery patterns, whereas range of motion seems to follow a different course. This may be a reflection of the fact that the most prominent symptom in MDI patients is pain, which would have a limiting effect on power and ADL. External Rotation: This was assessed separately only twice, preoperatively and at 2 years after surgery. The mean difference between the 2 assessments was ⫺1.2, which is not significant (P ⬎ .68). Patient Satisfaction: Fourteen patients (58%) were satisfied with their result. Six (25%) were satisfied with the symptomatic improvement but believed that their expectations from the procedure were not entirely fulfilled. Four (17%) did not believe that the procedure provided benefit. However, none of these believed that they were worse off as a result of the surgery. Failure of Surgery: Three patients in group A experienced recurrence of instability with either a positive sulcus sign or drawer tests. One of these patients also experienced pain recurrence. Additionally, one of these patients underwent additional arthroscopic shrinkage of the posterior capsule that was omitted in the primary procedure. The other 2 patients refused further surgery.
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remaining 4, the onset was related with overuse. Four patients showed signs of increased laxity affecting the contralateral asymptomatic shoulder. The direction of the instability was global in 6 patients and multidirectional with primary anteroinferior direction in 2. Six Bankart and 2 SLAP lesions were found at surgery. As well as capsular shrinkage, arthroscopic repair with suture anchors was performed in 7 lesions and debridement was performed in 1 SLAP lesion. Constant Score: The average preoperative Constant score was 73.4. At 6 months, this had deteriorated to 72.1, but it showed gradual improvement thereafter to a mean Constant score of 91.4 at 2 years. Using the Scheffe multiple comparisons test, no statistically significant difference was found in the scores. However, this group is too small to draw any statistically valid conclusions. All 8 patients were satisfied with the procedure. This group did not include any treatment failures. Complications Two patients developed adhesive capsulitis (1 from group A and 1 from group B). The patient from group A was treated with physiotherapy alone, and the other (group B) required arthroscopic release of the coracohumeral ligament. Both patients regained full range of motion at 2 years but had to alter their sporting activities. No infections, wound healing problems, or neurologic or vascular complications were seen. Particularly, no deficit in the axillary nerve function was found.
Patients With MDI and Labral Pathology Labral pathology was found in 8 patients, 6 men and 2 women. Two of these patients had experienced a documented anterior dislocation of the shoulder in the past, 2 had no history of trauma, and in the
FIGURE 3. The various components of the Constant score at various assessment intervals for group A.
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S. P. FROSTICK ET AL. DISCUSSION
Capsular shrinkage is purely the result of application of heat on collagen.9 The molecular mechanism is unknown, but collagen denaturation is the main ultrastructural change.10 The temperature at which significant shrinkage occurs is 65°C or greater. The amount of shrinkage achieved is time- and energy-transfer– dependent. The tissue stiffness is significantly decreased at 2 weeks after surgery but returns to normal levels between 6 and 12 weeks.19 Therefore, immobilization in a sling for 3 weeks after surgery is required. During the postoperative period, the capsular collagen remodels.20 Capsular shrinkage is used to address capsular laxity during arthroscopic stabilization of the shoulder.21 Labral lesions discovered during arthroscopy should be treated arthroscopically even in patients with no history of previous frank dislocation. A surgeon should undertake capsular shrinkage only if he is familiar with arthroscopic stabilization of the shoulder. Group A Our study showed a highly statistically significant improvement in the mean Constant score for patients in the first 6 months. Thereafter, the rate of improvement tends to plateau. Four patients showed a decline in the Constant score at 6 months; however, they showed gradual improvement with rehabilitation. The main reason for their lower scores is restricted range of motion. Intensive rehabilitation is mandatory for a successful outcome. Looking at the components of the Constant score individually over 2 years, pain improvement seemed to be followed by improvement in power and ADL. The range of motion followed a separate course. External rotation was not changed significantly. The short-term (2-year) failure rate for patients with MDI without a labral lesion (12%) in this study compares favorably with figures reported for open capsular shift. Pollock et al.4 reported a 4% failure rate after open inferior capsular shift with an average follow-up of 61 months. When pain is considered as an outcome measure, the figure then increased to 33%. In this group, the overall failure and complication rate is 16%. However, this reflects the steep learning curve required to master the technique and judgment on the extent of shrinkage required. Overall patient satisfaction was 83%. Even patients who had to alter their activities stated that they would have the procedure again should their original symptoms recur.
Group B We included 8 patients in the study because they fulfilled the criteria for multidirectional instability2; all of them had a positive sulcus sign that was reproducing their symptoms, and they were subluxating in all 3 directions (anterior, posterior, and inferior). Our findings regarding the presence of labral lesions in patients with MDI correlate with previous studies.2,4 However, we present them separately to isolate the effect of the shrinkage. Although Constant scores improved for all patients and all patients were satisfied, with no clinical recurrence of the instability, this group is too small to draw any statistically valid conclusions. Arthroscopic capsular shrinkage has all the attractions of minimally invasive surgery, namely, small incisions, less soft tissue damage, shorter hospital stay, and faster rehabilitation. We must, however, state that it is not entirely free of complications. Marked stiffness can occur in some patients (2° adhesive capsulitis). The axillary nerve is also at risk of electrothermal damage when the inferior capsule is treated. Electrical activity changes have been documented through surface electrodes when the inferior part of the capsule is shrinking.22 However, it should be stressed that the use of a bipolar system has not been associated with any reported axillary nerve damage. Capsular disruption has also been reported after shrinkage,23 especially during the early postoperative period when the biomechanical properties of the collagen are altered.19 To prevent this complication, the rehabilitation program should be balanced, protecting healing soft tissues and preventing the negative effects of immobilization. In conclusion, the early results are encouraging. Adequate physiotherapy remains the treatment of choice for MDI. Only patients who do not show response (20% of our patients) after at least 6 months of appropriate rehabilitation require surgical treatment. The physiotherapist’s role in arthroscopic capsular shrinkage is critical to a successful outcome. Patient selection is equally important. Patient expectations and the need for adherence with the rehabilitation regimen must be fully discussed before surgery. Continued long-term follow-up of this relatively new technique is required to determine whether and how the failure rate increases at longer time intervals. REFERENCES 1. Gibson JC, Frostick SP. Efficacy of a muscle imbalance program in the treatment of multidirectional instability of the
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