Status Update: Use of a Subacromial Spacer to Manage a Massive Irreparable Rotator Cuff Tear
Results from Europe have been encouraging, with studies demonstrating improvement in pain, range of motion, and functional scores. Now a multi-center study of this new device is underway in the US, and in this article, a study investigator and his colleague describe the rationale and surgical technique for using a subacromial balloon spacer in patients with large to massive irreparable rotator cuff tears.
J. Gabriel Horneff III, MD, and Joseph A. Abboud, MD
One of the greatest challenges for orthopaedic surgeons and their patients is treatment of a massive irreparable rotator cuff tear. A variety of treatment options have been proposed and implemented, with varying degrees of success. Some of the more common options include:
- Partial rotator cuff repair with biceps tenodesis and tuberoplasty
- Superior capsular reconstruction
- Tendon transfer (eg, latissimus dorsi, lower trapezius)
- Reverse shoulder arthroplasty
Many of these surgical options are technically demanding, while others require significant rehabilitation time after surgery. In addition, some patients are not considered good candidates for many of these surgical options. For these reasons, as well as others, there has been a demand for a relatively simple surgical procedure that can provide relief from the symptoms of a massive rotator cuff repair.
Recently, the use of an inflatable, biodegradable subacromial balloon spacer (InSpace system, OrthoSpace, Caesara, Israel) has been been proposed to restore the biomechanics of a cuff-deficient glenohumeral joint. The device is designed to decrease the friction of the humeral and acromial interface while also depressing the humeral head to a more anatomic position.
Early results from use of the device in Europe have been encouraging, and a multi-center trial aimed at gaining Food and Drug Administration (FDA) approval is currently underway in the United States.
Biomechanics of a Cuff-Deficient Shoulder
Proper biomechanics of the glenohumeral joint is predicated on the function of the rotator cuff. As dynamic stabilizers of the shoulder, the rotator cuff muscles compress the humeral head against the glenoid and act as a fulcrum for upper arm motion. This compression by the rotator cuff muscles allows contraction of the deltoid muscle to elevate the arm.
When the rotator cuff muscles are torn, the axis of rotation is lost and the vector force imparted on the humeral head by the deltoid muscle becomes a superiorly directed shearing force. In large to massive rotator cuff tears, this phenomenon can be appreciated on radiographic imaging, with proximal migration of the humeral head seen with respect to the glenoid.
In its most extreme form, proximal humeral migration can result in the humeral head abutting the undersurface of the acromion, which is insufficient to recreate the lever arm effect of the deltoid. Over time, the constant shearing force across the glenohumeral joint and abrasion underneath the acromion can lead to significant wear commonly seen in cuff tear arthropathy.
Subacromial Balloon Spacer in the Literature
The subacromial balloon spacer has been used in more than 10,000 cases throughout Europe since its introduction in 2010. The biomechanical theory of the balloon is to help restore a smooth coracoacromial arch and reduce rotator cuff contact pressure while preserving arch function. [1-3] The spacer helps to depress the humeral head and reduce subacromial friction, allowing for better shoulder forward elevation and abduction.
The subacromial balloon spacer is made of a translucent biodegradable poly (L-lactide-co-E-caprolactone) polymer. The biodegradable lifespan of the material is about 12 months. Animal studies in rabbits have shown that during the period of degradation, a mature connective tissue forms that can act as a barrier between the humeral head and the acromion long after the spacer is gone.  Why patients experience significant improvement in pain and function after the balloon has degraded is unknown, but early results with this novel approach have been encouraging.
In a prospective study, Senekovic et al  included 20 patients with massive irreparable cuff tears who underwent balloon arthroplasty. Within 6 weeks of surgery, patients demonstrated statistically significant improvement in Constant scores and range of motion (ROM), which continued to improve over the 3-year follow up period.  Activities of daily living (ADLs) showed improvement as early as 3 weeks after surgery and also continued to improve for 3 years.  Subjective pain scores and night pain began to show improvement within 1 week after surgery and progressed for 3 years. 
Senekovic et al  conducted another prospective trial of 21 patients who underwent insertion of the subacromial balloon spacer and were followed for 5 years. Patient outcomes were evaluated using Total Constant Score. Of those who were followed for 5 years, 84.6% showed clinically significant improvement of at least 15 points; 61.5% demonstrated at least a 25-point improvement.  The Total Constant Scores began to show improvement as early as 3 months after surgery, which was sustained by 6 months through to 5 years of follow-up. 
Deranlot et al  reported on 37 patients followed for an average of 33 months and found similar encouraging results. The mean ROM and Constant scores were all significantly improved at the latest follow-up, with shoulder abduction showing the largest increase of 60°.  They also evaluated patients radiographically and found that the mean acromiohumeral interval significantly decreased from 8.2 mm to 6.2 mm, but the impact on functional outcomes seemed negligible. Thirty-two of the 37 patients did not demonstrate any progression of their arthritis on the Hamada radiographic scale. 
Gervasi et al  prospectively examined 15 patients who underwent the procedure to place the subacromial balloon spacer and followed them out for 1 year after surgery. All patients demonstrated improved Constant and American Shoulder and Elbow Society scores beginning at 6 weeks after surgery and sustained for 12 months.  Much like the 5-year study from Senekovic et al,  85% of patients showed a clinically significant improvement of at least 15 points in their Constant score. 
In addition to the improvements in pain and satisfaction seen across these studies, the overall early track record of the safety and efficacy of the subacromial balloon spacer system has demonstrated significant promise. Combining all studies, only 1 patient had a device-related complication: dislocation of the balloon that required balloon replacement. No other patients had device-related complications. [1,4-6]
Three of the 4 studies examined operative time and found that placement of the device ranged from 2 to 30 minutes, with 2 studies stating an average of 10 minutes was required for the procedure. [1,4-6] The learning curve also improved over time, with 2 studies mentioning that subsequent patients in their study required less operative time than the initial patients enrolled. [1,4-6]
The combination of good clinical outcomes and a safe and relatively simple procedural record to date has made the use of the interpositional balloon arthroplasty with a subacromial balloon spacer an attractive option for the patient dealing with a large irreparable rotator cuff tear.
Experience in the United States
An FDA Investigational Device Exemption (IDE) trial of the subacromial balloon spacer is currently underway in the US. Patient inclusion criteria are as follows:
- Age over 18 years
- Massive irreparable superior rotator cuff tear
- Ability to forward elevate the arm to 90°
Patients are excluded from the study if they have significant arthritic changes in the glenohumeral joint, lack an intact subscapularis tendon, or have had shoulder surgery within the past year.
This is a prospective, patient-blinded, pivotal study with enrolled subjects randomized to either receive the subacromial balloon spacer or undergo the best possible rotator cuff repair.
The surgical technique is shown in Video 1 below. The steps in the procedure include the following:
- The patient is offered an interscalene single-shot nerve block for pain control. After placement of the block, the patient is brought to the operating room and positioned in the beach chair position, with the operative extremity prepped and draped in the usual sterile fashion.
- A standard posterosuperior arthroscopic portal is created for placement of the arthroscope. A diagnostic arthroscopy is initially performed to assess the status of the rotator cuff, articular cartilage, and surrounding structures.
- Because the indication for this procedure is massive irreparable rotator cuff tear, the glenohumeral joint space and subacromial space are often contiguous. For the current US IDE, the subscapularis must be intact and there must be no signs of significant arthritic changes on the articular surfaces.
- Once the diagnostic arthroscopy is completed, attention is turned to the subacromial space for preparation of the balloon implantation.
- The arthroscope is redirected to lie adjacent to the undersurface of the acromion. A lateral portal is created under direct visualization for placement of an arthroscopic shaver and electrocautery to remove any soft tissue and debris from the subacromial space.
- Once the space is cleared and good visualization is obtained, an arthroscopic probe is used to measure the size of the deficient cuff space in the anteroposterior position of the acromion and the distance from the greater tuberosity to the superior glenoid rim. The subacromial balloon spacer comes in 3 sizes: small (40 x 50 mm), medium (50 x 60 mm), and large (60 x 70 mm).
- With the use of an arthroscopic switching stick, the arthroscope is placed into the lateral portal for viewing. Prior to insertion of the balloon into the shoulder, the inflating system is prepared. A syringe is filled with sterile saline warmed to about 40° The syringe and extension tubing should be carefully examined prior to inflation and any air bubbles present should be removed.
- The balloon insertion device is then introduced into the posterior portal and positioned over the superior glenoid rim. Once it is in the proper position, the protection sheath is withdrawn to expose the balloon. The syringe of warmed saline is then connected to the insertional handle via an extension tube. As the plunger of the syringe is advanced, the balloon is inflated under visualization. There is a recommended volume of saline to be injected for each balloon size.
- Once the balloon is filled to a satisfactory volume, the red safety button and the green knob are used to seal the balloon prior to removal of the insertional handle. The patient’s arm should be taken through a range of motion after the handle has been removed to ensure that the balloon is stable in its position, without any signs of subluxation. If the balloon is noted to be unstable, it can be replaced prior to portal closure.
- If the balloon is stable in its position, the arthroscope is removed and the portal sites are closed with interrupted non-absorbable suture and dressed with sterile dressings. The patient’s arm is then placed into a sling for comfort and the patient is awoken from anesthesia and discharged to home when stable.
Video 1. Surgical technique for placement of the subacromial balloon spacer. Click the image to start the video.
The subacromial balloon spacer has the advantage of an easy recovery timeline for the patient compared with other surgical procedures currently used to treat massive irreparable rotator cuff tears. Below is our current recommended rehabilitation protocol:
- 0 to 4 weeks: The patient is maintained in a sling for comfort and is non-weight-bearing. The affected arm can be used for light tasks (e.g. eating, writing, hygiene).
- 4 to 8 weeks: The patient is out of the sling completely at this point and can resume activities of daily living. Formal physical therapy begins with Phase 1 and 2 stretching and early strengthening to a limit of 3 pounds.
- 8 to 12 weeks: Physical therapy is advanced to full strengthening, with continued home exercises for stretching.
- 12 weeks: All restrictions are lifted.
A 63-year-old, right-hand dominant male who works as a mason presents with complaints of a painful right shoulder. He states that he was treated 3 years ago for a right shoulder rotator cuff tear through non-operative measures.
Over the past 6 months, he has experienced increasing pain and weakness in the right shoulder, most notably with overhead use. He has also had a significant disruption of sleep. His has received 3 cortisone injections, which have provided minimal relief.
- Atrophy of the supraspinatus fossa
- Active range of motion: Forward elevation: 90°; abduction: 80°; external rotation (0° abduction): 20°; internal rotation (0° abduction): L5 vertebral level
- Passive range of motion: Forward elevation: 160°; abduction: 110°; external rotation (0° abduction): 40°
- Examination maneuvers: Positive Jobe’s test; positive Hawkin’s impingement sign
- Neurovascularly intact throughout upper extremity.
Initial anteroposterior (AP) and axillary view radiographs were obtained (Figure 1).
- AP: Minimal arthritic changes noted at the glenohumeral joint; slight proximal migration of the humeral head in reference to the glenoid
- Axillary: Minimal arthritic changes with well-maintained joint space; humeral head well-centered in reference to the glenoid vault
Figure 1. Preoperative AP (left) and axillary (right) radiographs.
An MRI was done to assess the rotator cuff, given the physical examination findings and the minimal changes see on plain radiography.
- Coronal T2-weighted (Figures 2a): Complete full-thickness tear of the supraspinatus and infraspinatus tendons with retraction medial to the glenoid articular surface; minimal arthritic changes
- Axial T2-weighted (Figures 2b): Intact subscapularis tendon with long head of the biceps tendon within the bicipital groove; atrophic changes noted in the infraspinatus
- Sagittal T1-weighted (Figures 2c): Grade 4 Goutallier changes in the supraspinatus and infraspinatus muscle bellies; subscapularis and teres minor muscle bulk in satisfactory condition.
Figure 2a. Preoperative coronal T2-weighted MRI.
Figure 2b. Preoperative axial T2-weighted MRI.
Figure 2c. Preoperative sagittal T1-weighted MRI.
The patient underwent interpositional balloon arthroplasty with the subacromial balloon spacer, as described in Video 1 above.
- A standard posterior superior arthroscopic portal was established for placement of the arthroscope into the glenohumeral joint.
- An anterior superior instrumentation portal was made under direct visualization.
- Systematic diagnostic evaluation of the glenohumeral joint was performed:
- The subscapularis and long head of the biceps tendons were found to be intact (Figure 3a).
- The rotator cuff demonstrated a full-thickness tear of the entire supraspinatus and infraspinatus tendons with retraction to the glenoid margin (Figure 3b).
- The teres minor tendon was intact.
- There was mild evidence of glenohumeral arthritis (Figure 3c).
- Interpositional balloon arthroplasty with the subacromial balloon spacer was performed.
- Figure 4 shows the patient’s postoperative AP radiograph.
Figure 3a. Arthroscopic view of the subscapularis tendon.
Figure 3b. Arthroscopic view of the full-thickness supraspinatus and infraspinatus tear.
Figure 3c. Arthroscopic view of the glenohumeral articular surfaces.
Figure 4. Postoperative AP radiograph.
- At 1 week after surgery, the patient’s portal incisions were healing well and his pain was minimal. Active range of motion was evaluated and found to be as follows: forward elevation: 170°; abduction: 110°; external rotation (0° abduction): 20°; internal rotation (0° abduction): L1 vertebral level.
- At 2 weeks from surgery, the patient continued to do well and demonstrated good active range of motion. Video 2 shows the clinical examination of patient at the 2-week postoperative visit.
- At 12 weeks, the patient had minimal pain and well-healed incisions. He continued to do well with physical therapy. Active range of motion was found to be as follows: forward elevation: 170°; abduction: 90°; external rotation (0° abduction): 20°; internal rotation (0° abduction): T7 vertebral level.
Video 2. Clinical examination of a patient 2 weeks following surgery to place a subacromial balloon spacer to treat a massive rotator cuff tear. Click the image to start the video.
Summary of Key Points
- Large to massive irreparable rotator cuff tears are a challenging problem to treat especially in the young, active patient population.
- Interpositional balloon arthroplasty with the subacromial balloon spacer is designed to help recreate the normal biomechanics of the cuff-deficient shoulder by depressing the humeral head and allowing for decreased friction at the humeral to acromial interface.
- Early results out of Europe have demonstrated significant improvement in patients with regard to pain, range of motion, and functional scores.
- The procedure takes an average of 10 minutes to perform in the operating room. Relatively few device-related complications have been reported.
- The subacromial balloon spacer is made of biodegradable polymer that degrades about 12 months after placement.
- Postoperative rehabilitation is relatively easy for patients, with progression from light activity with the affected shoulder to improved strengthening with no restrictions on use of the affected shoulder within 12 weeks.
J. Gabriel Horneff III, MD, is an Assistant Professor of Orthopaedic Surgery at the Sidney Kimmel School of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, and a shoulder and elbow surgeon with The Rothman Institute, Philadelphia, Pennsylvania. Joseph A. Abboud, MD, is Professor of Orthopaedic Surgery at the Sidney Kimmel School of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, and a shoulder and elbow surgeon and Senior Vice President at The Rothman Institute, Philadelphia, Pennsylvania.
Dr. Horneff has has disclosed that he has received payment as a speaker for DJO. Dr. Abboud has disclosed that he is an investigator for the OrthoSpace InSpace FDA IDE trial in the US. In addition, he has disclosed that he receives research support from DePuy, Zimmer, Tornier, Integra, DJO, the US Department of Defense, and OrthoSpace; is a paid consultant for Tornier, Cayenne, DJO, and Globus; receives royalties from Wolters Kluwer Health – Lippincott Williams & Wilkins, Cayenne, DJO, and Globus; has stock options in Mininvasive and Aevumed; and is on the scientific advisory board of Mininvasive.
- Senekovic V, Poberaj B, Kovacic L, Mikek M, Adar E, Dekel A. Prospective clinical study of a novel biodegradable sub-acromial spacer in treatment of massive irreparable rotator cuff tears. Eur J Orthop Surg Traumatol. 2013 Apr; 23(3): 311-6.
Clinical relevance: This study was the first prospective series to report patient outcomes in patients who received the subacromial balloon spacer. The authors of this study examined patient outcomes as they related to pain, range of motion, and Constant scores.
- Gervasi E, Cautero E, Dekel A. Fluoroscopy-guided implantation of subacromial “biodegradable spacer” using local anesthesia in patients with irreparable rotator cuff tear. Arthrosc Tech. 2014 Jul 21; 3(4): e455-8.
Clinical relevance: This technique paper describes the surgical approach to the placement of the subacromial balloon spacer.
- Savarese E, Romeo R. New solution for massive, irreparable rotator cuff tears: the subacromial “biodegradable spacer.” Arthrosc Tech. 2012 May 4; 1(1): e69-74.
Clinical relevance: This paper was the first to describe the technique for placing the subacromial balloon spacer.
- Senekovic V, Poberaj B, Kovacic L, Mikek M, Adar E, Markovitz E, Maman E, Dekel A. The biodegradable spacer as a novel treatment modality for massive rotator cuff tears: a prospective study with 5-year follow-up. Arch Orthop Trauma Surg. 2017 Jan; 137(1):95-103.
Clinical relevance: The authors of the first reported outcome study examining the use of the subacromial balloon spacer in patients followed up their initial study with this prospective series that included 5-year outcomes. This study again demonstrated improvement in patients with regard to pain, range of motion, and outcome Constant scores. These significant improvements were maintained at 5 years out from surgery.
- Deranlot J, Herisson O, Nourissat G, Zbili D, Werthel JD, Vigan M, Bruchou F. Arthroscopic subacromial spacer implantation in patients with massive irreparable rotator cuff tears: clinical and radiographic results in 39 retrospective cases. Arthroscopy. 2017 Sep; 33(9):1639-44.
Clinical relevance: Like the prior studies by Senekovic et al, this study also demonstrated good clinical outcomes in patients 1 year out from placement of the subacromial balloon spacer. In addition, the authors of this study examined the radiologic outcomes of patients and found that the progression of arthritis was uncommon amongst treated patients. The acromiohumeral interval did show a decrease over time, but did not appear to affect clinical outcomes.
- Gervasi E, Maman E, Dekel A, Cautero E. Fluoroscopy-guided biodegradable spacer implantation using local anesthesia: safety and efficacy study in patients with massive rotator cuff tears. Musculoskelet Surg. 2016 Dec; 100 (Suppl 1): 19-24.
Clinical relevance: Including some of the authors of the studies by Senedovic et al, this paper demonstrated improved Constant scores in patients following placement of the subacromial balloon spacer, with the large majority of patients (85%) having at least 15 points increased in their scores.