The long-term efficacy of corticosteroid injection into the acromioclavicular joint using a dynamic fluoroscopic method Bain GI, Van Riet RP, Gooi C, Ashwood N, – Int J Shoulder Surg

Year : 2007  |  Volume : 1  |  Issue : 4  |  Page : 104-107
ORIGINAL ARTICLE The long-term efficacy of corticosteroid injection into the acromioclavicular joint using a dynamic fluoroscopic method Bain GI1, Van Riet RP2, Gooi C3, Ashwood N1 1 University of Adelaide, Royal Adelaide Hospital, North Terrace, 5000 Adelaide; Modbury Public Hospital, Smart Road, 5092 Adelaide, Australia, 2 Modbury Public Hospital, Smart Road, 5092 Adelaide, Australia; University Hospital Antwerp, Belgium, 3 Modbury Public Hospital, Smart Road, 5092 Adelaide, Australia, Correspondence Address:Bain G I196, Melbourne Street, North Adelaide, SA 5006, Australia Source of Support: None, Conflict of Interest: None

Purpose: Accuracy and efficacy of an intra-articular infiltration of corticosteroid and local anesthetic in the symptomatic acromioclavicular joint were studied in 44 patients.
Methods: Accuracy of the infiltration was studied using a blind technique with a dynamic fluoroscopic control.
Results: Accuracy of the blind infiltration technique was only 50% and the dynamic fluoroscopic technique remains our preferred technique in the clinical setting. On average patients reported a 65% decrease in the intensity of the pain following the injection. At an average follow-up of forty-two months, 59% had undergone surgery, 14% of patients reported more than three months of symptoms relief.
Conclusions: Despite the poor long-term results of injecting the acromioclavicular joint, it remains a valuable technique. It has a low cost, minor risks of complications and has high diagnostic value. All but one patients reporting short-term pain relief.
Level of Evidence: Level III, case control study.

Keywords: Acromioclavicular joint, corticosteroids, intra-articular injection

Acromioclavicular joint pathology is common, with primary osteoarthritis as a common cause of symptoms. Non-operative treatment options are limited and most authors recommend an intra-articular injection with corticosteroids. ^[1] However, despite these recommendations, data regarding the long-term efficacy of acromioclavicular injections is poorly understood, with only one published, retrospective study reporting on the outcome of corticosteroid injections in the acromioclavicular joint. ^[2] Only five out of 27 (19%) were considered to have a long-term benefit from the injection. Accuracy of the injection was however not assessed in this study. ^[2] This may however be an important variable as accuracy of injecting the acromioclavicular joint has been shown to be around 66%, with half of these injections also reaching surrounding soft tissues. ^[3] The aim of the current study was to prospectively evaluate the accuracy and long-term efficacy of corticosteroid injections in the acromioclavicular joint.

Patients with shoulder girdle symptoms were examined, using a standard protocol including; range of motion, impingement and rotator cuff strength testing. Specific acromioclavicular joint examination consisted of the cross body adduction test, the O’Brien test for the acromioclavicular joint and palpation of the acromioclavicular joint. Plain radiographs of the shoulder were obtained in all patients. Patients with acromioclavicular joint symptoms were prospectively recruited for the current study during a two-year period. Patients with previous surgery to the shoulder, traumatic dislocation of the acromioclavicular joint or fracture of the clavicle were excluded, as well as patients with a previous adverse reaction to corticosteroids or previous injections in the affected acromioclavicular joint. This resulted in a study group of forty-four patients, thirty-three women and eleven men. Average age at the time of injection was 46 years (range 27 to 68 years). All patients were informed of the nature of the study and consented to the injection.

The patient was placed in a comfortable lying position on an examination bed [Figure – 1]. All injections were performed by the senior author. The distal clavicle and acromion were palpated and the acromioclavicular joint was identified. A standard antiseptic technique was used. The 23G needle was advanced through the skin and held in position when it was believed to be in the acromioclavicular joint. The shoulder was then examined using the fluoroscopic unit and the position of the needle were noted [Figure – 2]. The needle was repositioned under fluoroscopic guidance if necessary [Figure – 3]A and a mixture of 1 ml of corticosteroid and 1 ml of local anesthetic were injected into the joint, using a single syringe. The volume of fluid injected was usually less than 1 ml. Confirmation of the correctness of the anatomic site of the injection was obtained with dynamic fluoroscopic images, which show distension of the joint during injection [Figure – 3]B.

Patients were asked to complete a visual analogue pain score (VAS) prior to the injection and ten minutes after the injection. Patients were also asked to further subjectively quantify pain relief. The pre-injected intensity of pain was said to be 100% and the patients were asked to record a percentage of change in the intensity of the pain at ten minutes following the injection. Timing of pain relief as well as subsequent surgery were recorded at time of follow-up. All patients were seen at six weeks following the injection; further follow-up was performed if needed. Patients were contacted at least two years following the injection for the study presented. Pre- and post-injection pain scores were compared using a one-tailed paired t-test. Significance level was set at P = 0.05. Differences between patients that ultimately required surgery and patients that did not require surgery following the injection were analyzed using a two-tailed t-test. Significance level was again set at P = 0.05.

Fluoroscopy showed that the initial position of the needle was correct in twenty-two out of forty-four (50%) patients. Distension of the joint showed a correct position of the needle in all patients at the time of injection.

Average pre-injection pain score was six, ranging from two to nine (SD = 2). Average post-injection pain score was two, ranging from zero to nine (SD = 2). This difference was significant ( P < 0.001). Forty-one of forty-four (93%) patients had a decrease in VAS score at ten minutes following the injection. Average decrease in VAS score following the injection was three, ranging from an increase in pain from two to five in one patient, to a decrease in pain from nine to zero in another. According to the VAS scores, two patients had a transient increase in pain following the injection. The recorded percentage of pain relief was on average 65%, ranging from 0 to 100% (SD = 26%).

Average follow-up was forty-two months (range 29 to 52 months). At an average of five months following the injection (range 1 to 30 months) twenty-six patients had undergone surgery to the shoulder. The average period of pain relief in this group, available in twenty patients, was seventeen days, ranging from three hours to ninety days.No surgical procedure was done in sixteen patients at the time of final follow-up. Three patients were lost to long-term follow-up in this group. The average duration of pain relief was 19 months, ranging from transient increase in pain, to pain relief up to five years following the index injection.

The period of pain relief was significantly different between the patients who ultimately had surgery and those who did not. ( P < 0.001). No difference was found between these groups in VAS scores before the injection ( P = 0.80), VAS scores ten minutes following the injection ( P = 0.67) or decrease of pain following the injection ( P = 0.77).

Due to the variations found in the morphology of the acromioclavicular joint, ^[4] this is one of the most difficult joints to inject. In a cadaveric study, dye was injected into the acromioclavicular joint. Subsequent dissection showed the presence of dye in the acromioclavicular joint in 66%. However, dye was also found in the surrounding tissues, indicating a less than perfect placement of the needle, in half of these. ^[3] We report a similar accuracy of injection into the AC joint if this were to be performed by palpation alone.

In the authors’ study, the needle was repositioned under fluoroscopy to ensure that all patients received an accurate injection into the AC joint. Distension of the joint during the injection of fluid as seen on dynamic fluoroscopic imaging is a useful technique to confirm correct positioning of the needle and continues to be used routinely in our practice. Accuracy of the injection in the current study was 100%, but would have been 50% without dynamic fluoroscopic control. Median distance between the needle tip and the acromioclavicular joint was estimated to be around 1 mm. A major factor influencing accuracy of needle position was obesity. Difficulties placing the needle were also encountered in one patient with a webbed neck, where the needle was initially positioned 7 mm from the acromioclavicular joint.

The use of corticosteroids in the shoulder and acromioclavicular joint is considered standard practice. Several authors have stated that conservative treatment is often successful in the treatment of osteoarthritis in the acromioclavicular joint. ^{[5],[6],[7],[8],[9]} Interestingly, most of these papers deal with the operative resection of the distal clavicle, without showing specific data from conservative treatment.

No data is available in the current literature regarding the natural course of acromioclavicular pathology. The figures presented in this study are similar to the 19% successful long-term results reported in the only paper on this subject to date. ^[2] In the current study, six out of forty-four patients (14%) had more than three months relief following the injection and nineteen of forty-four patients (43%) did not require surgery, at least to the time of follow-up. In contrast, none of the patients that subsequently required surgery, reported more than three months pain relief.

We did not encounter any complications relating to the injection and injection of the acromioclavicular joint did not complicate the subsequent surgical intervention in any of the patients in the group studied.

Accuracy of injections in the acromioclavicular joint is low, however it can be greatly improved using dynamic fluoroscopy. Other imaging techniques, such as ultrasound guided injection, ^[10] may also improve accuracy but this has thus far not been shown to be the case for shoulder ^[11] and was not part of the study presented. The injection of corticosteroids and local anaesthetic in the acromioclavicular joint serves two purposes. It acts as an important diagnostic tool, as the majority of patients will have at least short-term pain relief. In 14% of patients, more than three months of improvement from the moment of the intra-articular injection was recorded. Although this percentage does not seem high, its combination with low cost of treatment, low incidence of complications and high diagnostic value, the intra-articular injection of corticosteroid combined with a local anaesthetic remains a valid conservative option in the treatment of isolated acromioclavicular pathology. From the data presented, patients can be informed that surgery may be avoided in 43% of patients, while more than three months pain relief may only be expected in as little as 14%.

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[Figure – 1], [Figure – 2], [Figure – 3]