Adhesive capsulitis (frozen shoulder) is characterized by a gradual increase in stiffness and pain in the shoulder. It is said to be self-limiting over a period of 1–2 years, during which time it can cause considerable disability. Many treatment regimens, including conservative treatment, manipulation under anesthesia, and intra-articular injection, have been used to accelerate recovery and relieve pain associated with frozen shoulder.1,2 Excellent results following distension of the shoulder joint, which can be performed with or without arthrography or steroid injection, have been reported.3,4
Adhesive capsulitis is commonly associated with diabetes mellitus, hyperthyroidism, hypothyroidism, cardiac disease, and pulmonary disease.5 Obesity is commonly defined in terms of body mass index (BMI) and is related to the overproduction of inflammatory cytokines. Currently, there is no study in the literature discussing the relationship between obesity and adhesive capsulitis.
We present a prospective study of a series of patients with frozen shoulders treated using a protocol consisting of self-assisted active range of motion exercise after receiving a single injection of corticosteroid and a local anesthetic in the frozen phase. The purpose of this study was to examine the effects of this protocol on the functional results of primary frozen shoulder, and to compare the outcomes in overweight and normal-weight patients.
Between 2010 and 2012, 79 patients with primary adhesive capsulitis in only one shoulder were enrolled in this study after institutional review board approval. Patients with rotator cuff tear or rheumatic disease, and those who had received a steroid injection or undergone previous shoulder surgery in the affected shoulder were excluded.
All patients received a 3-mL intra-articular injection of corticosteroid (Shincort, 10 mg/mL) mixed with 3 mL of 2% lidocaine (Xylocaine 2%, 20 mg/mL) in the 1st. The mixture was injected into the glenohumeral joint by an experienced orthopedic surgeon. Patients were seated in a chair, and the affected shoulder was bent and adducted. After intra-articular injection at the outpatient department of our institution, these patients participated in a self-assisted exercise program consisting of gentle active-assisted forward flexion, abduction, external rotation, and adduction. The exercises were repeated 15–20 times slowly within 15 minutes at a frequency of four times per day. Additionally, patients were instructed to stretch the shoulder gently against the limits of tolerance, and to avoid strengthening exercises until shoulder pain subsided. We did not specifically prescribe, discourage, or prohibit the use of oral nonsteroidal anti-inflammatory medications. More aggressive treatment (manipulation or capsular release) was not recommended until it was determined that the protocol had failed (the patient was dissatisfied with the outcome) after performing the exercise program for at least 3 months.
Initial evaluation included the recording of a detailed medical history, including the history of the shoulder problem. Subjective patient function and pain were evaluated by determining the Constant score at each follow-up visit. Additional follow-up included patient assessments at 2, 4, and 8 weeks, and 6 months at the outpatient department. The need for continuing compliance with the exercise protocol was strongly reiterated and recommended at each visit.
Demographic data, including age, sex, and presence of diabetes mellitus, were also obtained. BMI was calculated for each patient using the weight in kilograms divided by height in meters squared. For the purposes of statistical analysis, patients were classified as normal weight (BMI < 25 kg/m2) or overweight (BMI ≥ 25 kg/m2). Mean differences between baseline and 8-week scores were compared between the overweight and normal-weight patients. Statistical analysis was performed using paired Student's t test. The p values < 0.05 were considered statistically significant.
Seventy-nine patients completed an after-treatment follow-up of 8 weeks, including physical examination and outcome assessment. Forty-seven patients were classified into the normal weight group, and 32 were deemed overweight. There were 22 (28%) men and 57 (72%) women, with a mean age of 52.3 years (range 42–63 years). There was no significant difference between the ages of the male and female patients between the two groups. The mean duration of shoulder pain was 4.1 months (range 3–6 months).
Baseline demographic data of the two groups were similar with regard to age, sex, presence of diabetes mellitus, and duration of symptoms (Table 1). There was one patient with a thyroid goiter who had normal thyroid function. The percentage of patients with diabetes mellitus was slightly higher in the overweight group than the normal-weight group, but the difference was not significant.
At 8 weeks, there were 55 (69.6%) patients with excellent results, and 16 (7.5%) patients with good results according to the Constant score. Of the patients with 55 excellent results, there were 42 (76.3%) women and 13 (23.7%) men. Eight patients reported poor functional outcome based on the Constant score. These eight patients were deemed as treatment failures, and included five women and three men. Three patients with no improvement after 3 months of treatment were also reported to have poor outcomes. All three patients, including one patient with diabetes mellitus, underwent successful manipulation under anesthesia.
At 8 weeks, the mean Constant score increased from 35.4 to 74.6 in the normal-weight group, and from 32.0 to 47.6 in the overweight group. It was noted that there was a significant difference between the Constant score in the normal weight and overweight groups (Table 2). In the eight poor outcomes at 8 weeks, the demographic variables were analyzed for any association with subjective dissatisfaction, and the eventual need for manipulation under anesthesia. Treatment failure and the need for manipulation were not associated with age, sex, duration of symptoms, or the presence of diabetes mellitus. In the eight failed patients, the mean BMI was 27.8 kg/m2 (range, 24.0–32.3 kg/m2). Satisfaction with the outcomes then was determined by questioning the patients. Four of the eight patients (50%) were satisfied with the improvement in pain, and one was considered to be unchanged.
In this study, we prospectively evaluated the functional outcomes of patients with primary adhesive capsulitis who were treated with active range of motion exercise after a single intra-articular injection of steroid and lidocaine. The vast majority of patients were treated successfully, with an excellent Constant score at 8 weeks postinjection. This prospective study provided data that enabled us to analyze the reduction in patient pain and improvement in function, and also observe the relationship, if any, between the effectiveness of treatment and patient factors.
Steroid injection in the glenohumeral joint is one of the most well known treatments for frozen shoulder. Moreover, there are numerous reports in the literature that a single injection can be effective to address this problem.6 When compared with an ultrasound-guided injection procedure, the improvement in pain intensity, range of motion, and shoulder function score with the use of a blind technique was significantly reduced by the second week. However, no further significant differences in improvement were observed beyond the 3rd week.7 Subacromial injection is an alternative modality; however, injection at the glenohumeral joint typically leads to earlier pain relief.8
Oral or intra-articular corticosteroid treatment may be of limited, short-term benefit in adhesive capsulitis.2,9,10 The distension effect may result in a longer and gradual relief of pain, which is attained despite unchanged rigidity.11 To date, there is no consensus regarding the necessity of capsular rupture or volume that is sufficient for this distension effect.12 Furthermore, in one study, there was no significant difference in outcome between the high-(triamcinolone acetonide, 40 mg) and low-dose (20 mg) corticosteroid groups, indicating the preferred use of a lower dose at the initial stage.13 Combined with range of motion exercise, it is effective and faster in improving shoulder pain and disability in primary adhesive capsulitis.14 It is important to continue arthrographic capsular distension in order to achieve maximum improvement in range of motion. In our study, patients were instructed to actively stretch against the limits before any assistance. There are advantages to both active and passive range of motion, as demonstrated by the fact that both conventional physiotherapy and continuous passive range of motion brought statistically significant improvement in pain and function.15
In this prospective study, we found that the treatment protocol resulted in significant improvement in the Constant score in most patients, regardless of age, sex, or presence of diabetes mellitus. There may be a different mechanism in diabetic patients, and poorer response over the long term was noted.4,16 However, we assume that steroid and lidocaine provide an anti-inflammatory and analgesic effect with distention of the contracted capsule. Active range of motion exercise further helps maintain the improved range of motion, shortens the natural course of the disease process, and improves function at 8 weeks in normal-weight patients. The regimen is also relatively easy for patients to perform when provided with clear instruction.
There is a trend toward comparatively worse results in men, but not in patients with coronary artery disease or hypothyroidism.17 There is no previous study examining the effect of obesity on the treatment of primary adhesive capsulitis. Our data suggest that being overweight (BMI ≥ 25 kg/m2) resulted in a significantly lower improvement in the Constant score, when treated with active range of motion exercise after intra-articular injection. One potential explanation for this finding is the more severe inflammation in obese patients, which is also the possible pathophysiology in obese patients with psoriasis18: the higher the soft tissue pressure, the higher the dosage and volume necessary to achieve capsular extension, and the poorer the compliance with rehabilitation exercise.
For those without range of motion improvement during our study, questionnaire responses still indicated that most of the patients were satisfied with the extent of their pain improvement. Further studies with appropriate controls are needed to confirm the exact mechanism influencing the outcome in overweight patients.
On the basis of the findings of our study, we recommend that normal-weight patients with primary adhesive capsulitis should be treated with active range of motion exercise after intra-articular injection of corticosteroid and lidocaine. The active range of motion exercise should be continued for at least 8 weeks before more aggressive or invasive management is considered. Our experience indicated that a significant improvement in the Constant score should be expected at 8 weeks.
This study has some limitations. First, the procedure was led by a single senior surgeon whose results may not be applicable to the wider orthopedic community. Second, there was only one method of management, which was assessed without randomization or blinding. Finally, the active range of motion exercise regimen may differ in patients, even provided with clear instructions.
In conclusion, active range of motion exercise after a single intra-articular injection of corticosteroid and lidocaine improved pain and functional outcome at 8 weeks in normal-weight (BMI < 25 kg/m2) patients with primary adhesive capsulitis. Manipulation under anesthesia or other aggressive treatment may be considered a priority in overweight patients.
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