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Journal of Shoulder and Elbow Surgery

Intra-articular injection, subacromial injection, and hydrodilatation for primary frozen shoulder: a randomized clinical trial

      Background

      The aim of this prospective randomized study was to compare the efficacy of 3 injection methods, intra-articular injection, subacromial injection, and hydrodilatation (HD), in the treatment of primary frozen shoulder.

      Methods

      Patients with primary frozen shoulder were randomized to undergo intra-articular injection (n = 29), subacromial injection (n = 29), or HD (n = 28). Evaluations using a visual analog scale for pain, Simple Shoulder Test, Constant score, and passive range of shoulder motion were completed before treatment and 1 month, 3 months, and 6 months after treatment.

      Results

      Among the 3 injection methods for primary frozen shoulder, HD resulted in a greater range of motion in forward flexion and external rotation, a lower visual analog scale score for pain after 1 month, and better outcomes for all functional scores after 1 month and 3 months of follow-up. However, there were no significant differences in any clinical outcomes among the 3 groups in the final follow-up at 6 months.

      Conclusions

      Although HD yielded more rapid improvement, the 3 injection methods for primary frozen shoulder resulted in similar clinical improvement in the final follow-up at 6 months.

      Level of evidence

      Keywords

      Frozen shoulder (adhesive capsulitis) is a common disease that restricts passive and active range of motion (ROM) in the glenohumeral (GH) joint. The concept was initially developed by Codman and Neviaser.
      • Ewald A.
      Adhesive capsulitis: a review.
      Frozen shoulder accounts for approximately 2% to 5% of all cases of shoulder pain.
      • Bridgman J.F.
      Periarthritis of the shoulder and diabetes mellitus.
      • Carette S.
      Adhesive capsulitis—research advances frozen in time?.
      • Tighe C.B.
      • Oakley Jr, W.S.
      The prevalence of a diabetic condition and adhesive capsulitis of the shoulder.
      Frozen shoulder consists of 3 sequential phases or stages: inflammatory, freezing, and thawing. The condition may persist for 1 to 3 years, and it can be self-limited.
      • Grey R.G.
      The natural history of “idiopathic” frozen shoulder.
      Unfortunately, most patients with frozen shoulder reportedly do not regain full ROM irrespective of the treatment modality employed.
      • Dias R.
      • Cutts S.
      • Massoud S.
      Frozen shoulder.
      • Shaffer B.
      • Tibone J.E.
      • Kerlan R.K.
      Frozen shoulder. A long-term follow-up.
      Moreover, despite the availability of various treatments for frozen shoulder, an optimal treatment has not yet been established.
      • Lubiecki M.
      • Carr A.
      Frozen shoulder: past, present, and future.
      The primary treatment methods for frozen shoulder include medication
      • Buchbinder R.
      • Hoving J.L.
      • Green S.
      • Hall S.
      • Forbes A.
      • Nash P.
      Short course prednisolone for adhesive capsulitis (frozen shoulder or stiff painful shoulder): a randomised, double blind, placebo controlled trial.
      and physical rehabilitation.
      • Griggs S.M.
      • Ahn A.
      • Green A.
      Idiopathic adhesive capsulitis. A prospective functional outcome study of nonoperative treatment.
      • Levine W.N.
      • Kashyap C.P.
      • Bak S.F.
      • Ahmad C.S.
      • Blaine T.A.
      • Bigliani L.U.
      Nonoperative management of idiopathic adhesive capsulitis.
      However, if these fail, several injection methods, such as intra-articular injection (IAI), subacromial injection (SAI), or injection with hydrodilatation (HD), may be employed effectively
      • Andren L.
      • Lundberg B.J.
      Treatment of rigid shoulders by joint distension during arthrography.
      • Buchbinder R.
      • Green S.
      Effect of arthrographic shoulder joint distension with saline and corticosteroid for adhesive capsulitis.
      • Carette S.
      • Moffet H.
      • Tardif J.
      • Bessette L.
      • Morin F.
      • Fremont P.
      • et al.
      Intraarticular corticosteroids, supervised physiotherapy, or a combination of the two in the treatment of adhesive capsulitis of the shoulder: a placebo-controlled trial.
      • Fareed D.O.
      • Gallivan Jr, W.R.
      Office management of frozen shoulder syndrome. Treatment with hydraulic distension under local anesthesia.
      • Ryans I.
      • Montgomery A.
      • Galway R.
      • Kernohan W.G.
      • McKane R.
      A randomized controlled trial of intra-articular triamcinolone and/or physiotherapy in shoulder capsulitis.
      • Weiss J.J.
      • Ting Y.M.
      Arthrography-assisted intra-articular injection of steroids in treatment of adhesive capsulitis.
      before consideration of more aggressive treatments, such as manipulation under anesthesia
      • Dodenhoff R.M.
      • Levy O.
      • Wilson A.
      • Copeland S.A.
      Manipulation under anesthesia for primary frozen shoulder: effect on early recovery and return to activity.
      • Farrell C.M.
      • Sperling J.W.
      • Cofield R.H.
      Manipulation for frozen shoulder: long-term results.
      or surgical release.
      • Berghs B.M.
      • Sole-Molins X.
      • Bunker T.D.
      Arthroscopic release of adhesive capsulitis.
      • Fernandes M.R.
      Arthroscopic capsular release for refractory shoulder stiffness.
      IAI can decrease pain and thereby help improve ROM of the GH joint in patients with frozen shoulder, but it is technically more difficult to perform than SAI.
      • Carette S.
      • Moffet H.
      • Tardif J.
      • Bessette L.
      • Morin F.
      • Fremont P.
      • et al.
      Intraarticular corticosteroids, supervised physiotherapy, or a combination of the two in the treatment of adhesive capsulitis of the shoulder: a placebo-controlled trial.
      SAI is relatively easy to perform, and it does not require radiologic guidance. HD, or arthrographic distention of the shoulder joint, induces capsular rupture by introducing a fluid into the GH joint, resulting in increased shoulder joint motion. It was introduced as an injection treatment modality for frozen shoulder by Andren and Lundberg.
      • Andren L.
      • Lundberg B.J.
      Treatment of rigid shoulders by joint distension during arthrography.
      It is known to be relatively safe and cost-effective, and it can elicit a rapid and satisfactory outcome.
      • Fareed D.O.
      • Gallivan Jr, W.R.
      Office management of frozen shoulder syndrome. Treatment with hydraulic distension under local anesthesia.
      However, the evidence is insufficient to conclude which injection method is superior among IAI, SAI, and HD for the treatment of frozen shoulder.
      Thus, we designed a prospective, randomized study to compare treatment outcomes using IAI, SAI, and HD in patients with primary frozen shoulder. The aim of this study was to identify which treatment modality is superior in terms of the visual analog scale (VAS) score for pain as well as functional outcomes, including ROM. We hypothesized that HD would provide superior clinical improvement compared with IAI and SAI.

      Methods

       Sample size calculation and patient allocation

      This was a randomized, prospective, controlled study. We conducted this study in accordance with the principles of the Declaration of Helsinki. The reporting of data from this trial complies with the Consolidated Standards of Reporting Trials (CONSORT) statement.
      Sample sizes were calculated to detect a 20% difference among the groups in the VAS score for pain on the basis of the pilot study and previous literature.
      • van der Windt D.A.
      • Koes B.W.
      • Deville W.
      • Boeke A.J.
      • de Jong B.A.
      • Bouter L.M.
      Effectiveness of corticosteroid injections versus physiotherapy for treatment of painful stiff shoulder in primary care: randomised trial.
      A sample size of 30 patients in each group was required for a power of 90% at a type I error level of .05, with an expected dropout rate of 20%.
      A total of 164 consecutive patients with primary frozen shoulder were prospectively enrolled between June 2012 and September 2013. Patients were diagnosed with frozen shoulder if they had limitations of both active and passive shoulder motion and more severe pain at night than during the day and if findings on radiography of their shoulders were normal.
      • Pal B.
      • Anderson J.
      • Dick W.C.
      • Griffiths I.D.
      Limitation of joint mobility and shoulder capsulitis in insulin- and non-insulin-dependent diabetes mellitus.
      Patients were eligible for the study if their shoulder symptoms (pain or discomfort) were present for 6 months to 1 year, if they had a VAS score of <7 of 10 for pain
      • Buchbinder R.
      • Green S.
      Effect of arthrographic shoulder joint distension with saline and corticosteroid for adhesive capsulitis.
      (thus probably in the freezing stage rather than in the inflammatory stage
      • Dias R.
      • Cutts S.
      • Massoud S.
      Frozen shoulder.
      ), and if they remained unresponsive to conservative treatment consisting of medication or physical therapy for at least 6 months. All patients had limited active and passive ROM in at least 2 directions (abduction and forward flexion <100°, external rotation <20°, or internal rotation <L3).
      • Warner J.J.
      Frozen shoulder: diagnosis and management.
      All patients underwent simple radiography and sonography. Patients with secondary causes of frozen shoulder such as rotator cuff tear (n = 32) or calcific tendinitis (n = 9), those with GH arthritis (n = 4), those with a history of surgery on the same shoulder (n = 1), those who received a steroid injection within 6 months before enrollment (n = 23), and those who refused to participate in the study (n = 5) were excluded. No patient had a history of previous shoulder trauma, manipulation under anesthesia, or suprascapular nerve injection, and none had a worker's compensation status. The remaining 90 patients were randomly allocated into the IAI, SAI, or HD group (30 patients in each group). Patients were randomized using a computer-generated block randomization sequence (www.randomizer.org) by an independent researcher, and the group assignment was disclosed to the physician at the time of intended treatment.
      Among these 90 patients, 4 (1 from the IAI group, 1 from the SAI group, and 2 from the HD group) were lost to follow-up. Accordingly, 86 patients (26 men, 60 women; mean age, 54.5 years [standard deviation, 8.3]) with primary frozen shoulder (idiopathic adhesive capsulitis) were ultimately enrolled in this study (Fig. 1). The demographic and clinical data did not differ among the groups (all P < .05), and these data are summarized in Table I. During the study period, all patients underwent conventional conservative treatment, including medication and a home-based physical therapy exercise program. The medication included a nonsteroidal anti-inflammatory drug and muscle relaxant, which were administered for approximately 4 weeks. For physical therapy, active assisted ROM exercise, including stick exercise, was performed for approximately 10 weeks, depending on the recovery of ROM. We employed a 4-quadrant stretching program (passive flexion, horizontal adduction, internal rotation behind the back with the unaffected arm, and external rotation at the side using a stick) to stretch the entire capsule at least 3 times a day (10-15 minutes per session). When ROM had recovered, muscle-strengthening exercise was performed on the scapular stabilizers (such as the lower trapezius and serratus anterior muscles) and rotator cuff using a resistance band at least 3 times a day (10-15 minutes per session).
      Table IPatients' demographic variables by injection group
      VariableIAISAIHDP value
      No.292928
      Age, years53 (8)57 (7)54 (9).137
      Sex (M:F)11:186:239:19.347
      Symptom duration, months9 (6)9 (5)9 (6).903
      Dominant shoulder (yes:no)16:1317:1214:14.806
      Diabetes (yes:no)4:253:265:23.715
      Hypertension (yes:no)7:226:236:22.946
      Heart disease (yes:no)3:261:282:26.587
      Thyroid disease (yes:no)1:281:282:26.748
      Smoking (yes:no)7:224:255:23.595
      Work level (low:medium:high)5:10:146:3:203:6:19.199
      Level of sports activity (high:moderate:low)3:6:203:7:191:4:23.665
      Overhead sports (yes:no)3:265:242:26.476
      IAI, intra-articular injection; SAI, subacromial injection; HD, hydrodilatation.
      Values in parentheses are standard deviations.

       Clinical variables

      All data were prospectively collected by a clinical researcher (A.-S.C.) who was blinded to the study design. The patients' demographic data and other characteristics, including age, sex, symptom duration, dominant shoulder, underlying disease (diabetes mellitus, hypertension, heart disease, and thyroid disease), and smoking habits, were recorded. The level of sports activity was defined as high (dynamic or contact sports, such as boxing, basketball, rugby, and tennis), medium (static sports, such as yoga and jogging), or low (mild or no sports activity).
      • Chung S.W.
      • Huong C.B.
      • Kim S.H.
      • Oh J.H.
      Shoulder stiffness after rotator cuff repair: risk factors and influence on outcome.
      The work level was defined as high, medium, or low, depending on whether the work involved heavy manual labor, manual labor with less physical activity, or sedentary activity, respectively.
      • Chung S.W.
      • Park J.S.
      • Kim S.H.
      • Shin S.H.
      • Oh J.H.
      Quality of life after arthroscopic rotator cuff repair: evaluation using SF-36 and an analysis of affecting clinical factors.

       Treatment procedure

       IAI group

      For IAI, an anterior approach was used with a 10-mL syringe and 21-gauge needle, and the procedure was performed with the patient in the supine position. Povidone sterilization was performed around the injection site, and the skin was anesthetized with 2% lidocaine before injection, followed by IAI under sonographic guidance. The needle was placed immediately medial to the head of the humerus and approximately 1 cm lateral to the coracoid process, and it was directed posteriorly as well as slightly superiorly and laterally under sonographic guidance. If the needle struck against bone, it was retracted and redirected at a slightly different angle. When resistance was felt on penetrating the joint capsule, aspiration was performed to ensure that the needle was not placed in a blood vessel. Then, a mixture of 1 mL of triamcinolone (40 mg), 4 mL of 2% lidocaine, and 5 mL of normal saline was injected into the GH joint space slowly and with consistent pressure under sonographic guidance. We chose 40 mg of triamcinolone for evaluating the treatment effect on the basis of previous literature.
      • Ryans I.
      • Montgomery A.
      • Galway R.
      • Kernohan W.G.
      • McKane R.
      A randomized controlled trial of intra-articular triamcinolone and/or physiotherapy in shoulder capsulitis.

       SAI group

      For SAI, a posterior approach was used with a 10-mL syringe and 21-gauge needle, as described for the IAI group, and the procedure was performed with the patient in the sitting position with the arm resting comfortably at the side and with the clinician standing behind the patient. After povidone application and skin anesthesia as described for the IAI group, the needle was inserted 2 to 3 cm inferior to the posterolateral corner of the acromion and directed anteriorly in the direction of the coracoid process under sonographic guidance. After verification by aspiration that the needle was not placed in a blood vessel, a mixture of 1 mL of triamcinolone (40 mg), 4 mL of 2% lidocaine, and 5 mL of normal saline, as described for the IAI group, was injected slowly and with consistent pressure under sonographic guidance.

       HD group

      For HD, an anterior approach was used with a 50-mL syringe and 21-gauge needle, and the procedure was performed with the patient in the supine position under overhead fluoroscopy in the operating room. Under fluoroscopy, the GH joint was identified and marked on the skin with a pen. After povidone sterilization, draping, and skin anesthesia, the needle was placed immediately medial to the head of the humerus and approximately 1 cm lateral to the coracoid process, and it was directed posteriorly, slightly superiorly, and laterally, as described for the IAI group. The needle position was verified by fluoroscopy. After aspiration and the injection of 4 mL of contrast medium for joint space confirmation, a mixture of 1 mL of triamcinolone (40 mg), 4 mL of local anesthetic (2% lidocaine), and 40 mL of normal saline was injected into the GH joint slowly and with pressure. When resistance was encountered, the injection was stopped momentarily and then continued. During the injection, the joint was gradually distended, making the axillary and subscapular recesses more visible. The injection was continued until rupture of the capsule occurred. The capsule primarily ruptured in the wall of the subscapular recess or sometimes in the wall of the bicipital or axillary recess.
      • Tveitå E.K.
      • Tariq R.
      • Sesseng S.
      • Juel N.G.
      • Bautz-Holter E.
      Hydrodilatation, corticosteroids and adhesive capsulitis: a randomized controlled trial.
      The capsular rupture appeared as a loss of resistance, with leakage of contrast material on fluoroscopy.
      All patients in the 3 groups received the same nonsteroidal anti-inflammatory drug for pain relief after injection. A stretching exercise program, as described previously, was started from the first day after injection.

       Outcome evaluation

      Clinical symptoms were evaluated at 4 time points for all patients: before treatment and 1 month, 3 months, and 6 months after treatment. We set 6 months as the final follow-up evaluation period because this period should be adequate to assess the result of the injection treatments and to decide on a subsequent treatment plan for a frozen shoulder. The clinical outcome was evaluated using the VAS score for pain (range, 0-10, with 10 indicating the worst pain), Simple Shoulder Test (SST), Constant score, and passive shoulder ROM.
      Passive shoulder ROM was measured using a goniometer by a clinical researcher (A.-S.C.) who was blinded to the study. Forward elevation was measured in degrees between the arm and thorax in the scapular plane. External rotation at the side was measured in degrees between the thorax and forearm, with the arm held in an adducted position at 90° of elbow flexion. Internal rotation at the back was measured by the vertebral level reached with the tip of the thumb and numbered serially 1 to 12 for the first to twelfth thoracic vertebrae, 13 to 17 for the first to fifth lumbar vertebrae, and 18 for any level below the sacral region.
      • Oh J.H.
      • Kim S.H.
      • Lee H.K.
      • Jo K.H.
      • Bin S.W.
      • Gong H.S.
      Moderate preoperative shoulder stiffness does not alter the clinical outcome of rotator cuff repair with arthroscopic release and manipulation.

       Statistical analysis

      Statistical analysis was performed using SPSS 22.0 software (IBM, Armonk, NY, USA). Repeated-measures 1-way analysis of variance and post hoc Scheffé multiple comparison tests were used to identify significant differences in continuous variables among the groups; the χ 2 or Fisher exact test was used to identify any significant differences in categorical variables. Before the analysis of variance test, the Kolmogorov-Smirnov test for normality and Levene test for homogeneity of variances were performed, and the assumption of normality and homogeneity of variances was fulfilled, all with P values > .05. The primary end point was the VAS score for pain, and the secondary end points were clinical scores and shoulder ROM. Values of P < .05 were considered statistically significant.

      Results

      At the initial presentation, no intergroup differences were observed in the VAS score, SST, Constant score, and any ROM measure among the 3 groups. Each group displayed significant improvements from baseline to 6 months of follow-up (all P < .001). Every patient in each group was satisfied with his or her results at 6 months, and no patients required an additional treatment, such as manipulation or capsular release.
      The VAS score for pain after 1 month of follow-up was significantly improved in the HD group compared with the IAI group (P = .035). However, at 3 and 6 months of follow-up, there were no statistically significant differences among the groups in the VAS score for pain (Table II).
      Table IIClinical scores by injection method
      VariableVAS score for painSimple Shoulder TestConstant score
      IAISAIHDIAISAIHDIAISAIHD
      Preinjection5.6 (2.1)5.4 (2.6)5.8 (1.5)3.2 (1.8)3.2 (2.9)3.2 (2.2)58.6 (17.1)54.8 (17.1)57.4 (20.0)
      1 month4.6 (1.1)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      4.2 (1.7)3.6 (1.3)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      6.0 (2.5)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      6.1 (2.6)
      Statistically significant difference (P < .05) between the HD group and SAI group.
      7.8 (2.0)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      67.4 (19.8)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      64.2 (23.3)78.1 (16.8)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      3 months4.4 (1.5)4.2 (1.8)3.4 (1.4)6.8 (1.6)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      6.0 (3.4)
      Statistically significant difference (P < .05) between the HD group and SAI group.
      8.7 (3.4)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      73.7 (18.1)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      64.8 (16.4)77.3 (18.1)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      6 months1.9 (1.1)2.8 (1.6)2.1 (1.3)9.1 (1.2)8.3 (2.8)8.9 (1.2)80.1 (14.2)77.1 (17.6)85.1 (11.2)
      IAI, intra-articular injection; SAI, subacromial injection; HD, hydrodilatation.
      Values in parentheses are standard deviations.
      The HD group showed a significantly lower VAS score for pain than the IAI group (P = .035) only at 1 month, a higher Simple Shoulder Test score than both the IAI group (P = .02 at 1 month and P = .05 at 3 months) and SAI group (P = .04 at 1 month and P = .004 at 3 months), and a higher Constant score than the IAI group (P = .039 at 1 month and P = .032 at 3 months). No differences between groups were found at 6 months.
      * Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      For functional scores, at 1 month, the HD group exhibited a significant improvement in the SST compared with the IAI and SAI groups (P = .02 and .04, respectively) and a significant improvement in the Constant score compared with the SAI group (P = .039). At 3 months, the HD group had a significantly improved SST compared with the IAI and SAI groups (P = .05 and .004, respectively) and a significantly improved Constant score compared with the SAI group (P = .032). However, at 6 months, there were no significant differences in the SST or Constant score among the groups (all P > .05).
      For ROM, at 1 month, the HD group experienced greater improvement in forward flexion (P = .009 and .007, respectively) and external rotation (P = .005 and .005, respectively) than the IAI and SAI groups (Table III). However, at 3 and 6 months, there were no significant differences among the groups in any ROM measure.
      Table IIIRange of shoulder motion by 3 injection methods
      VariableForward flexionExternal rotationInternal rotation
      IAISAIHDIAISAIHDIAISAIHD
      Preinjection (affected/unaffected)103 (24)/174 (6)105 (16)/173 (6)107 (20)/174 (6)18 (8)/71 (6)20 (8)/70 (6)19 (10)/70 (6)15 (4)/7 (2)16 (4)/8 (1)16 (2)/8 (1)
      1 month133 (24)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      132 (15)
      Statistically significant difference (P < .05) between the HD group and SAI group.
      148 (13)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      28 (8)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      30 (8)
      Statistically significant difference (P < .05) between the HD group and SAI group.
      36 (9)
      Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      11 (4)12 (4)13 (2)
      3 months143 (18)148 (13)152 (12)38 (8)40 (8)41 (7)10 (3)11 (3)11 (2)
      6 months148 (15)152 (11)156 (10)43 (10)46 (8)44 (8)10 (3)10 (4)11 (3)
      IAI, intra-articular injection; SAI, subacromial injection; HD, hydrodilatation.
      Values in parentheses are standard deviations.
      Unaffected: normal contralateral shoulder.
      The HD group had a greater degree of forward flexion than the IAI and SAI groups (P = .009 and .007, respectively) and greater external rotation than the IAI and SAI groups (P = .005 and .005, respectively) only at 1 month; however, there were no significant differences between groups in all ROMs after 3 months.
      * Statistically significant difference (P < .05) between the HD group and IAI group.
      Statistically significant difference (P < .05) between the HD group and SAI group.
      No patients exhibited steroid injection–related major complications, such as joint infection, permanent neurogenic symptoms, or steroid-induced arthritis. Several mild adverse effects were reported. Two patients in the IAI group and 1 patient in the SAI group complained of temporary mild dizziness and nausea after the injection. One patient in the HD group reported transient loss of sensation and motor control in the injected arm for a few hours after the injection, but these symptoms recovered without sequelae. One other patient in the HD group reported transient hypotensive syncope immediately after the injection, but the patient fully recovered after several minutes.

      Discussion

      The aim of this prospective randomized comparative trial was to evaluate whether 1 of the 3 injection methods for primary frozen shoulder was superior to the others. Steroid injection for the treatment of frozen shoulder has been widely used as a safe and effective treatment modality for pain relief.
      • Ryans I.
      • Montgomery A.
      • Galway R.
      • Kernohan W.G.
      • McKane R.
      A randomized controlled trial of intra-articular triamcinolone and/or physiotherapy in shoulder capsulitis.
      • Weiss J.J.
      • Ting Y.M.
      Arthrography-assisted intra-articular injection of steroids in treatment of adhesive capsulitis.
      It may be used when medication or physical therapy exercise fails to relieve the symptoms of frozen shoulder before consideration of more traumatic or invasive treatments, such as manipulation under anesthesia or surgical capsular release.
      • Fernandes M.R.
      Arthroscopic capsular release for refractory shoulder stiffness.
      Three injection methods, namely, IAI, SAI, and HD, have been widely performed in outpatient clinics.
      • Griggs S.M.
      • Ahn A.
      • Green A.
      Idiopathic adhesive capsulitis. A prospective functional outcome study of nonoperative treatment.
      • Watson L.
      • Bialocerkowski A.
      • Dalziel R.
      • Balster S.
      • Burke F.
      • Finch C.
      Hydrodilatation (distension arthrography): a long-term clinical outcome series.
      The effects of IAI and SAI were not significantly different in this study, consistent with previous studies.
      • Oh J.H.
      • Oh C.H.
      • Choi J.A.
      • Kim S.H.
      • Kim J.H.
      • Yoon J.P.
      Comparison of glenohumeral and subacromial steroid injection in primary frozen shoulder: a prospective, randomized short-term comparison study.
      • Rizk T.E.
      • Pinals R.S.
      • Talaiver A.S.
      Corticosteroid injections in adhesive capsulitis: investigation of their value and site.
      In a study by Rizk et al,
      • Rizk T.E.
      • Pinals R.S.
      • Talaiver A.S.
      Corticosteroid injections in adhesive capsulitis: investigation of their value and site.
      48 patients who experienced frozen shoulder for <6 months were randomly assigned to receive weekly shoulder injections into the subacromial bursa or GH joint, but no significant difference in outcome was found. In addition, Oh et al
      • Oh J.H.
      • Oh C.H.
      • Choi J.A.
      • Kim S.H.
      • Kim J.H.
      • Yoon J.P.
      Comparison of glenohumeral and subacromial steroid injection in primary frozen shoulder: a prospective, randomized short-term comparison study.
      demonstrated that IAI offered no advantage over SAI in patients with primary frozen shoulder. Our results were similar. However, in this study, the HD group had better outcomes in terms of the VAS score for pain and ROM up to 1 month and functional scores up to 3 months.
      Previous studies reported that HD is relatively safe and cost-effective and that it provides direct results.
      • Fareed D.O.
      • Gallivan Jr, W.R.
      Office management of frozen shoulder syndrome. Treatment with hydraulic distension under local anesthesia.
      • Watson L.
      • Bialocerkowski A.
      • Dalziel R.
      • Balster S.
      • Burke F.
      • Finch C.
      Hydrodilatation (distension arthrography): a long-term clinical outcome series.
      Although numerous case series have reported favorable results for arthrographic shoulder joint distention, most have included corticosteroids; therefore, it may not be possible to directly attribute the effect to joint distention alone.
      • Jacobs L.G.
      • Barton M.A.
      • Wallace W.A.
      • Ferrousis J.
      • Dunn N.A.
      • Bossingham D.H.
      Intra-articular distension and steroids in the management of capsulitis of the shoulder.
      The efficacy of HD is believed to be attributable to the combination of injected steroids and capsular distention or rupture, and better outcomes may naturally be expected in the HD group. In this study, we found superior results in the HD group compared with those in the IAI and SAI groups in the early postinjection period, but the difference disappeared at the later follow-up period of 6 months. We believe that the combined effect of capsular distention or rupture in the HD group could lead to favorable results in the early period, but this is not maintained at later periods. Steroid injection alone without HD, into either the intra-articular or subacromial space, may be sufficient to guarantee results comparable to those by injection plus HD 3 months after injection, if appropriate physical therapy exercise is continued. Therefore, clinicians may choose any of the 3 injection methods according to their preference, equipment availability, and patient request. However, we cannot ignore the non-negligible benefit of HD treatment in this study (ie, its rapid treatment effect). Thus, HD would be the most appropriate treatment, especially for patients who expect a quick recovery.
      A few studies compared the effect of HD with steroid injection, but the findings were controversial.
      • Gam A.N.
      • Schydlowsky P.
      • Rossel I.
      • Remvig L.
      • Jensen E.M.
      Treatment of “frozen shoulder” with distension and glucorticoid compared with glucorticoid alone. A randomised controlled trial.
      • Tveitå E.K.
      • Tariq R.
      • Sesseng S.
      • Juel N.G.
      • Bautz-Holter E.
      Hydrodilatation, corticosteroids and adhesive capsulitis: a randomized controlled trial.
      Tveitå et al
      • Tveitå E.K.
      • Tariq R.
      • Sesseng S.
      • Juel N.G.
      • Bautz-Holter E.
      Hydrodilatation, corticosteroids and adhesive capsulitis: a randomized controlled trial.
      did not observe any important treatment effects of HD compared with those of steroid injection alone. However, Gam et al
      • Gam A.N.
      • Schydlowsky P.
      • Rossel I.
      • Remvig L.
      • Jensen E.M.
      Treatment of “frozen shoulder” with distension and glucorticoid compared with glucorticoid alone. A randomised controlled trial.
      reported an increase in shoulder ROM in the HD group compared with the findings in the steroid injection group, which is consistent with our results. We believe this difference may in part be attributable to the number of injections or the stage of frozen shoulder. In contrast to previous studies,
      • Gam A.N.
      • Schydlowsky P.
      • Rossel I.
      • Remvig L.
      • Jensen E.M.
      Treatment of “frozen shoulder” with distension and glucorticoid compared with glucorticoid alone. A randomised controlled trial.
      • Tveitå E.K.
      • Tariq R.
      • Sesseng S.
      • Juel N.G.
      • Bautz-Holter E.
      Hydrodilatation, corticosteroids and adhesive capsulitis: a randomized controlled trial.
      injection was performed only once in all groups. The additional effect of HD may be easier to identify in patients who were injected once rather than in those who received repeated injections, in whom the cumulative effects of steroids may make the difference unclear. Furthermore, the possible mislabeling of different stages of frozen shoulder may affect the results, with no difference in outcomes. In the early inflammatory phase, steroid injection would be more effective, and patients may be unable to tolerate capsular dilatation, with a resultant insufficient injection volume; by contrast, HD is believed to be more effective in the frozen phase than in an earlier phase.
      • Andren L.
      • Lundberg B.J.
      Treatment of rigid shoulders by joint distension during arthrography.
      • Buchbinder R.
      • Green S.
      Effect of arthrographic shoulder joint distension with saline and corticosteroid for adhesive capsulitis.
      We included patients with shoulder symptoms for more than 6 months and with a VAS score for pain of <7 of 10
      • Buchbinder R.
      • Green S.
      Effect of arthrographic shoulder joint distension with saline and corticosteroid for adhesive capsulitis.
      to make the groups more homogeneous by excluding patients in the inflammatory phase, thereby increasing comparability.
      Several limitations should be noted in interpreting our findings. First, patients were not blinded to the injection methods, which could have biased the results. Some patients may have had the biased impression that HD is a better treatment method. Second, we used different imaging guidance methods; specifically, IAI and SAI were guided by sonography, whereas HD was guided by an image intensifier and radiopaque contrast material. Third, the volume of injected saline during HD was not consistent because the injection was continued until rupture of the capsule occurred. Fourth, although all participants were instructed to perform a home-based physical therapy exercise program, compliance was not verified individually. Fifth, although the diagnosis of primary frozen shoulder was based on physical examination, radiographs, and ultrasonography, those with labral lesions or small rotator cuff tears could have been missed. These lesions can lead to secondary frozen shoulder, but we did not perform magnetic resonance imaging to confirm its appearance. Sixth, although there was no statistical difference in the incidence of underlying disease among the groups, systemic diseases such as diabetes and hypothyroidism may have affected the treatment results for frozen shoulder. Finally, although we tried to include patients with the same stage of frozen shoulder, the individual natural history of frozen shoulder may have varied.

      Conclusion

      Among the 3 injection methods of IAI, SAI, and HD for primary frozen shoulder, HD led to better pain scores and ROM at 1 month and better functional scores at 1 month and 3 months. However, the 3 injection methods provided similar clinical outcomes at the final follow-up of 6 months with the numbers available.

      Disclaimer

      The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

      Acknowledgment

      We thank Ae-Sun Chang (A.-S.C.) for the support in data collection.

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