Effects of arthroscopic capsular and inferior glenohumeral ligament release on function and stability for patients with frozen shoulder

The inferior glenohumeral ligament (IGHL) plays an important role in maintaining shoulder joint stability. However, no systematic studies on shoulder stability and function of patients with FS after IGHL release exist. This study assessed the functional and clinical outcomes of IGHL release for FS. Forty-seven patients underwent arthroscopic capsule and IGHL release with the same postoperative rehabilitation procedure. Five functional parameters were measured postoperatively at 4, 8, 12 and 28 weeks: the apprehension test result, American Shoulder and Elbow Surgeons Score (ASES), Constant score, visual analog scale (VAS) score and active range of motion (ROM).


Introduction
The main clinical symptom of frozen shoulder (FS) is a painful restriction in both active and passive motion of the shoulder joint in all directions, including flexion, abduction and rotation 1 . Primary FS has high prevalence rate and long duration and can seriously affect the daily life and exercise regimen of patients 2 . FS is mainly associated with hyperthyroidism, hypothyroidism, diabetes, and Dupuytren disease 3 . A large-scale prospective epidemiological study found that 1% of the population has FS, and women aged 40 to 60 years are more vulnerable than other populations 4 . Patients with FS describe the symptoms mainly as pain, which may be severe, not being able to sleep on the affected side, limited active and passive motion, and degenerated function.
The pathogenesis of FS is not clear, and there has been no international standard definition 5 . Although FS is a self-limiting disease, it has a long course and leads to incomplete functional recovery 6 . Recent research has shown that this condition can lead to long-term disabilities 7 . Positive non-surgical and surgical treatment can shorten the course of the disease, accelerate recovery, help regain shoulder joint function and improve the quality of life of patients with FS 8 . Many studies have attempted to determine more effective treatments, but many controversies still exist. At present, there is no consensus for treating FS 9 . The lack of unified standards leads to complicated treatment options. Because FS is a very painful and disabling disease, appropriate treatment is especially important.
In recent years, with the continuous development and promotion of minimally invasive surgical techniques and arthroscopic techniques, the application of arthroscopic techniques to treat FS has gradually received increasing attention 10,11,12 . Shoulder arthroscopy has been widely accepted as a diagnostic and therapeutic tool for shoulder joint disease 12 . At present, many studies report that the main treatment for FS is arthroscopic capsule release, which is a safe and effective method 13,14 . The arthroscopic capsule release techniques are widely used and can be chosen depending on the surgeons' preference. In the past, some studies have noted that the inferior glenohumeral ligament (IGHL) plays an important role in maintaining the stability of the shoulder joint 15,16 .
At present, some senior doctors like to release the IGHL to treat FS, but no systematic literature has reported the effect of this approach on the stability and function of the shoulder joint 11 . The hypothesis of this prospective study is that arthroscopic capsule and IGHL release can improve the prognosis of FS and will not affect shoulder stability or cause dislocations in patients with FS. To prove this hypothesis, patients with FS were followed up for a mean of 28 weeks to further investigate the effect of arthroscopic capsule and IGHL release.

Ethical support
This was a prospective clinical trial study with 47 patients who underwent shoulder arthroscopic capsule and IGHL release performed by a senior doctor between January 2018 and June 2019. The study was approved by the Medical Ethics Committee of the Northern Jiangsu People's Hospital (number 2019029), and all 47 patients signed informed consent forms to participate in this study. The coordinating investigator will report any adverse events to the ethical committee in accordance with the ethical committee adverse events reporting procedures.

Data collection and follow-up
The data were collected at the Northern Jiangsu People's Hospital. A shoulder arthroscopic specialist team evaluated and informed all patients. Postoperative follow-up examinations were scheduled at 4, 8, 12 and 28 weeks at the orthopedics outpatient clinic of the study hospital. Three patients did not go to orthopedic outpatient clinics for review, and they were excluded at 12 weeks. Four patients did not go to orthopedic outpatient clinics for review, and they were excluded at 24 weeks. In total, 40 patients completed the 28-week follow-up, and the data of these patients were applied for statistical analyses and compared with the preoperative data. The experimental process is shown in Fig 1. Among the 40 patients, there were 15 male patients and 25 female patients. There were 23 patients with left shoulder and 17 patients with right shoulder. There were 9 patients with diabetes and 31 patients without diabetes. The ages ranged from 41 to 77 years, and the mean age was 54.95±8.88 years. The course of the disease ranged from 3 to 26 months, and the average disease duration was 7.18±5.98 months.

Inclusion and exclusion criteria
Primary FS is not a definitive diagnostic criterion, and the diagnosis based on a physical examination 17 . All our studies are primary FS. A clinical diagnosis of FS can be made if the patient has painful, limited active and passive motion in at least two motion planes 18 . The inclusion criteria for this study were as follows: (1) restricted passive glenohumeral motion of 100° or less during forward flexion (FF) and 20°or less during external rotation (ER); (2) a history of at least 3 month of pain and stiffness; and (3) a normal radiologic appearance 19 . The exclusion criteria for this study were as follows: (1) acute shoulder injury; (2) combined with cervical spondylosis; (3) history of previous shoulder dislocation; (4) complicated cardiovascular and cerebrovascular diseases, nervous system diseases or blood system diseases; (5) combined with shoulder infections and tumors; (6) large and irreparable rotator cuff tears; and (7) combined with upper limb neuropathy.

Functional assessments
All of the patients were evaluated before and after surgery by the two professional orthopedists together completed a questionnaire with each patient about his or her subjective and objective symptoms. The primary outcome was the American Shoulder and Elbow Surgeons Score (ASES) score (scale 0-100, with higher scores indicating better outcomes and fewer symptoms). The secondary outcome was the Constant score criteria, which mainly accounts for subjective symptoms and the objective performance of the patients (scale 0-100, with higher scores indicating better outcomes and fewer symptoms). The third outcome was the visual analog scale (VAS) score for pain (range 0-10, 0 means no pain, and 10 means terrible pain). The fourth outcome was the active range of motion (ROM) 20 ; the ROM includes FF and abduction (ABD), which were measured with a universal goniometer.
The hand-behind-the-back method was used to measure internal rotation (IR). The hand-over-the-head method was used to measure ER.
At 12 and 24 weeks, the apprehension test of the shoulder primarily checks for a possible torn labrum or anterior instability problems and was mainly applied to detect the stability of the arthroscopic capsule and IGHL release in the shoulder joint.

Surgical procedures
The patients who participated in this study all underwent the same surgical treatment. The affected shoulder was marked while the patient was under general anesthesia, and the patient was placed in the lateral position ( Fig. 2A). Then, the affected shoulder joint was sterilized, and the area was draped (Fig. 2B). The surgeon first closed the manipulate to release the shoulder joint on the affected side. The affected shoulder was passively flexed and abducted to the maximum possible extent. Next, passive ER and IR were performed at 0° of ABD or 90° of ABD.
A 30° arthroscope (Smith & Nephew, America) traversed a standard posterior portal between the head of the humerus and the biceps tendon. An anterior-superior portal was made just below the long head of the biceps tendon and positioned with a puncture needle under direct vision with the arthroscope (Fig. 3A). A radiofrequency probe was used to first release the rotator interval, then the superior capsule. At the same time, the superior glenohumeral ligament was dissected (Fig. 3B). The anterior capsular and middle glenohumeral ligaments of the affected shoulder were dissected through a rotator interval with a radiofrequency probe (Fig. 3C). Then, the inferior capsular and anterior IGHL were dissected with the radiofrequency probe along the margin of the glenoid as far inferiorly as possible (Fig. 3D). To avoid surgically damaging the axillary nerve, a radiofrequency probe was inserted in the anterior-superior portal to dissect the inferior aspect of the capsule away from the axillary nerve. Finally, the residual posterior IGHL was dissected through the posterior portal.

Postoperative rehabilitation
All patients followed the same rehabilitation program at least once a day starting on postoperative day one; the program comprised shoulder ROM exercises, and exercises to strengthen the shoulder muscles were started as soon as the postoperative pain and active shoulder motion allowed. The patients were informed to perform each rehabilitation exercise twice a day. In weeks 1 to 4, the rehabilitation exercises included passive FF and ABD with the patient in a supine position and passive ER and IR with the support of the unaffected side at 0° of ABD.
The patients were also encouraged to use the affected arm in activities of daily living. In weeks 5 to 8, the affected shoulder joint gradually recovered the active ROM, and the patients actively increased the ROM of the affected shoulder joint. In weeks 9 to 12, exercises to strengthen the shoulder muscles of the affected side were performed. In weeks 13 to 28, the patients independently performed these exercises at home. Statistics SPSS 20 software for Windows (SPSS Inc., Chicago, IL, USA) was used to record the data and for the statistical analyses. The data of the various measurements are presented as the means±standard deviations (SDs). Student's t-test was used to compare the 28-week follow-up data with the preoperative data. A p value <0.05 was considered statistically significant.

Apprehension test of the shoulder
In this prospective study, 40 patients had negative apprehension tests at finally  Preoperatively, no patients were able to perform full elevation of the arm or place the dorsum of their hands between their shoulder blades, showing limited ROMs.
However, at the 28-week follow-up, 95% of the patients were observed to be able to perform full elevation, and 97.5% of the patients could place the dorsum of their hands between their shoulder blades (Table 3). Some doctors have released the IGHL to improve the function of the FS but did not analyze whether this release would affect the function and stability of the shoulder joint 11 . We need to find a new procedure to quickly treat FS for patients early recover function. In our study, we mainly investigated the effect of IGHL release on function and stability in patients with FS. or apprehension. This indicated that IGHL release had no effect on the stability of the shoulder joint with FS. Why does the IGHL release procedure in the arthroscopic rotator cuff repair cannot cause instability of the patients with FS? Here set a reasonable inference that although patients going through the IGHL release, the adhesion reaction is still in proceed, which may cause the reconstruction of the ligament and capsule 28 . Therefore, it is not easy to cause instability.
According to some studies, the postoperative rehabilitation program may affect the prognosis of patients with FS 29 . A recent randomized controlled trial with level 1 evidence reported that a group exercise class provided superior outcomes in relieving the signs and symptoms of FS compared to other methods 22 . All patients in our study followed the same postoperative rehabilitation procedure, and we cannot conclude whether an accelerated rehabilitation procedure would affect recovering postoperative shoulder function.

Acknowledgements
This study was approved by the Medical Ethics Committee of the Northern Jiangsu People's Hospital

Funding
No funding was received.

Availability of data and materials
The datasets generated and/or analyzed during the current study are not publicly available due the protection of the privacy of subjects involved and ongoing research but are available from the corresponding author on reasonable request.

Author's contributions
Zhang Y conceived of the study and contributed to the critical revision of the article for important intellectual content. Cao SC drafted the manuscript and evaluated the data and performed statistical expertise and evaluated the data including collected and assembled the data. The Fei WY and Wang JC read and approved the final manuscript.

Ethics approval and consent to participate
The study was approved by the Medical Ethics Committee of the Northern Jiangsu People's Hospital (number 2019029). All patients provided informed consent to participate in this study.  Figure 1 The experimental process.

Figure 2
The affected shoulder was marked while the patient was under general anesthesia, and the p Figure 3 An anterior-superior portal was made just below the long head of the biceps tendon and posi