Abstract
Rotator cuff repairs have a high failure rate proportional to the tear size. Various techniques have been described to improve the repair strength and failure rate. The described surgical technique uses a biodegradable subacromial balloon-shaped spacer (InSpace; OrthoSpace, Caesarea, Israel) that is implanted arthroscopically to protect our tendon repair. We describe the introduction technique and suggest some hints and tricks. The spacer is placed under direct vision in the subacromial space after the rotator cuff repair is finished. Correct placement is verified by moving the arm freely. The subacromial spacer may help to protect the rotator cuff repair by centering the humeral head and reducing friction between suture knots and the acromion. It may also help to flatten dog-ear formations.
Rotator cuff repairs are of proven clinical benefit to patients and are performed safely during various arthroscopic techniques. However, the larger the tear, the more often the repair fails, leaving the surgeon and patient with a result inferior to the desired result.1
Surgeons seek to diminish failure rates and improve the repair strength. Again, various techniques have been described for these purposes.2
We propose the protection of the rotator cuff repair by the introduction of a biodegradable subacromial spacer (InSpace system; OrthoSpace, Caesarea, Israel). Placement of the spacer between the acromion and the repaired rotator cuff is supposed to permit smooth and frictionless gliding and may help protect the repair, assisting in the restoration of shoulder biomechanics by centering the humeral head and reducing pain.3
The InSpace system is used for the treatment of irreparable massive rotator cuff tears for which it successfully re-establishes the acromiohumeral distance (AHD) and thus centers the humeral head. It has been proved to treat pain and restore range of motion in the long-term.3
Indication
We use the InSpace system for protection of our rotator cuff repair by inserting the spacer after the repair and acromioplasty have been performed. We indicate the use of spacer insertion mainly in repairs of large 2- or 3-tendon superior tears to protect the repaired tendon from subacromial friction. In all our rotator cuff repair cases, we perform an acromioplasty. If, after the acromioplasty, there is an extensive subacromial space, we will insert the spacer to help center the humeral head. In addition, there might be an indication when a repair has created a dog-ear formation that needs to be flattened by the spacer. The spacer insertion neither changes our indications to operate nor changes our techniques for rotator cuff repair.4
Material
The InSpace system is composed of an introducer and a pre-shaped balloon made of poly-L-lactide-co-ɛ-caprolactone, which is a biodegradable polymer material widely used in medical devices and in the pharmaceutical industry. The spacer deflates within the first 3 months after introduction and degrades fully after 1 year.
The spacer is folded into a cylinder-shaped protecting sheath that acts as an insertion tube. It is available in 3 different sizes (Table 1). The spacer is inflated with the recommended amount of physiological solution (e.g., Ringer solution). The device is delivered in a double-sealed package including a humidity indicator.
Table 1.
Balloon Sizes and Inflation Volumes
| Balloon Size | Width, mm | Length, mm | Maximal Inflation Volume, mL | Recommended Final Volume, mL |
|---|---|---|---|---|
| Small | 40 | 50 | 15-17 | 9-11 |
| Medium | 50 | 60 | 22-24 | 14-16 |
| Large | 60 | 70 | 40 | 23-25 |
Surgical Technique
Because the spacer device neither changes our indications to operate nor changes our techniques for rotator cuff repair, neither of these issues will be the subject of this presentation and many of them have been published before.4,5 This article focuses on the placement of the InSpace system on top of a rotator cuff repair (Video 1).
Preparation for the operation, the operating room setup, and the materials and techniques apply as with any regular arthroscopic rotator cuff repair. We always position the patient in the beach-chair position. We do not use any additives such as epinephrine in our irrigation fluid.
The portals that we regularly use include the standard dorsal, lateral, and anterolateral portals. However, we want to emphasize that we set up portals as needed during the operation rather than following a rigid rule. Particularly in large tears, we often use the lateral portal as a camera portal (Figs 1 A and C).
Fig 1.
Operating room setup and spacer introduction. A right shoulder is shown with the patient in the beach-chair position; the arm is under forward traction of 2.5 kg (not shown). (A) The assistant's fingers seal the anterior portals because no trocars are used. From the cannula outflow, the irrigation fluid is drawn to fill a syringe (BD Plastipak). (B) The portal (no trocars are used) is enlarged by passing an open Pean clamp (Landanger) from inside out. (C) The camera is in the lateral portal, and a small joint probe (ConMed Shutt) is inserted through the dorsal portal. The subacromial space size is measured from the anterior tip of the acromion to the interior opening of the posterior portal. (D) The laser marks on the probe are at a 5-mm distance from each other. (E) The surgeon holds the device in his left hand and has already placed the spacer in the subacromial space. The syringe is mounted directly on the introducer handle. (F) The spacer is placed correctly in the middle of the subacromial space under direct arthroscopic control.
When we perform a rotator cuff repair, we regularly perform biceps tenotomy or tenodesis, subacromial bursectomy, and acromioplasty. We address the acromioclavicular joint as indicated by the preoperative clinical findings.
The placement of the InSpace system begins on completion of the aforementioned steps. In addition to the device, a 20-mL syringe (BD Plastipak; BD Medical, Le Pont-de-Claix, France) and a measurement device—for example, a joint probe (ConMed Shutt Small Joint Probe; Linvatec, Rungis, France)—are needed. We fill the syringe with irrigation fluid drawn from the trocar. Because we have the camera in the lateral portal and the spacer is introduced through the posterior portal, the measurement of the subacromial space size is also performed through the posterior portal. The palpating hook is introduced so that it reaches from dorsal to anterior just to the end of the acromion bone (where the acromioclavicular ligament begins). The distance from the anterior edge of the acromion to the interior opening of the posterior portal is read on the laser marks of the hook (Figs 1 C and D). The corresponding size is chosen as shown in Table 1.
When one is unpacking the first sealed envelope, there is a humidity indicator that must be checked. The device comes as 1 piece mounted on the introducer handle and folded inside the protecting sheath. The filled syringe is connected to the end of the device handle (Figs 1E and 2A).
Fig 2.
Balloon placement and testing. A right shoulder is shown with the patient in the beach-chair position and traction of 2.5 kg, with arthroscopic views of rotator cuff repair (single-row repair using 2 anchors) from laterally. (A) The folded spacer is introduced through the posterior portal and placed in the middle of the subacromial space. The placement is controlled under direct arthroscopic vision. One should note that (B) the folded spacer is placed medially to the suture and (C) the spacer—even when inflated—does not overlap the lateral border of the supraspinatus footprint. (A) Only when the placement is satisfactory is the protecting sleeve pulled back, and (B) the spacer is inflated with the correct amount of irrigation fluid (Table 1). After the handle has been deployed, the arm is moved in (D) abduction and (E) external rotation to ascertain unrestrained mobility. While the arm is moved, the arthroscope checks that there is no spacer dislocation and there is frictionless mobility.
The standard protocol is to use the lateral portal to introduce the device. We perform the introduction through the posterior portal using the lateral portal for the camera (Fig 1E). The protector sleeve is relatively thin. The surgeon must be cautious not to fold or damage it when passing it through the portal. The skin incision must measure about 1 cm. The soft-tissue passage should be enlarged by passing an open Pean clamp (Landanger, Chaumont, France) from inside out (Fig 1B). The device is placed under direct vision in the middle of the subacromial space (Fig 2B). Normally, the spacer rests completely underneath the acromion and does not overlap it laterally or anteriorly. The medial row of the rotator cuff repair may be covered or slightly not covered by the spacer when the arm is in an adduction position (Fig 2C).
Because a cuff repair has taken place and thus the tendon fills up some of the subacromial space, the minimal recommended amount of solution (Table 1) is inflated to avoid overstuffing the subacromial space. Unfolding of the spacer and its correct placement can be controlled under direct vision. Even direct contact with the camera and the trocar does not harm the spacer. The red safety button is unlocked, and the spacer balloon is sealed and deployed in 1 single movement by turning the green knob half a circle clockwise. The introducer is withdrawn. The camera remains inside the subacromial space.
The placement of the spacer and its remaining in position should be controlled by moving the arm in a full range of motion while having the spacer in direct vision (Figs 2 D and E). If correct placement is confirmed and the spacer does not interfere with arm mobility, the camera is withdrawn and the wounds are closed.
There is no particular postoperative treatment related to the spacer. An abduction splint, immobilization, and physiotherapy are prescribed only according to the repair performed (Table 2).
Table 2.
Hints and Tricks
| Preparation |
| We do not use a connection tube between the syringe and device because it makes the mounting more unstable. |
| Portals |
| If the camera is already placed in the lateral portal, measurement in the anteroposterior direction starts from the anterior edge of the acromion to the posterior portal. The spacer size is chosen accordingly. |
| Spacer introduction from the posterior portal is perfectly possible. |
| Size |
| If the subacromial space size is between 2 spacer sizes, the smaller implant size is chosen to avoid overfilling the subacromial space. |
| Placement |
| The protection sleeve must not be withdrawn before the spacer is placed in its correct position because the balloon will then unfold and be difficult to place. |
| Unfolding of spacer |
| If the spacer does not unfold fully, the maximal recommended volume of liquid should be injected until it is fully unfolded and then the surplus amount of liquid should be allowed to drain back into the syringe before the spacer is deployed. |
| Troubleshooting |
| We have not encountered any intraoperative problems with the device other than the sleeve being slightly bent or folded during introduction. This bending/folding never interfered with the correct placement of the spacer. A large enough introduction portal avoids such bending/folding. |
| Spacer dislocation may occur after placement. If it occurs during the operation, the spacer should be removed. |
If the spacer dislocates after the operation (1 case in our series), it usually does so toward the subcoracoid space. It may be seen as a subcutaneous tumor in the anterior part of the shoulder. The treatment depends on the patient's symptoms:
|
Discussion
The AHD plays a role in rotator cuff pathology as an indicator of the severity of tendon retraction and fatty degeneration. An AHD of less than 6 mm indicates an irreparable tear.6 In addition, the AHD plays a role in subacromial impingement, leading to superior rotator cuff tears.7
Increasing the AHD by introducing a spacer into the subacromial space changes neither the shoulder anatomy nor the deltoid force vector that causes upward migration of the humeral head.8 One of the advantages of the spacer may be that it reduces friction between the repaired tendon and the acromion. Thus the spacer may mechanically protect the tendon repair by eliminating subacromial impingement. Moreover, because the upward motion of the humeral head is cushioned by the spacer, it may help tendon healing because less supraspinatus downward force is needed to center the humeral head during abduction. This may improve the long-term results of rotator cuff repairs, especially in large tears. There is a concern that the spacer may decrease the blood supply to the repaired cuff, but we have not found any clinical evidence of this potential risk. However, there may be a limitation to spacer introduction in cases with a very narrow subacromial space. Overstuffing the subacromial space may apply too much pressure to the repaired tendon or even depress the humeral head excessively. To avoid this, we recommend using the proper spacer size and not overfilling it beyond the recommended volume (Table 1).
The InSpace subacromial spacer has been proved to be effective in long-term pain reduction and arm mobility restoration in irreparable rotator cuff tears. We use it to protect our rotator cuff repairs. The insertion over a repair is similar to the insertion without a repair, it is easy to perform, and it does not significantly prolong the total operative time. Using our surgical technique, we have shown that spacer introduction through the posterior portal is possible and easy.
Footnotes
The authors report the following potential conflict of interest or source of funding: C.R. receives support from DePuy Mitek. Consultancy. L.L. receives support from the following: Devices for surgical procedures were provided by OrthoSpace to the institution free of charge. OrthoSpace consultant and member of company Scientific Advisory Team. Consultancy fee is based on future stock options. Holds stock options of OrthoSpace.
Supplementary Data
Examples of subacromial spacer introduction in a case with a small supraspinatus tear undergoing arthroscopic repair and the result after insertion in a case undergoing a larger repair. In the first part of the video, a small supraspinatus tear is shown, for which a single-row 1-anchor repair was performed. The operating room setup includes placing the patient in the beach-chair position; the portals used are the posterior, anterolateral, and lateral portals. Acromioplasty has been performed but is not shown in the video. The camera switches to the lateral portal as we start to measure the subacromial space length with a palpation hook. The dorsal portal is enlarged with a clamp. The device is unpacked and prepared with a 20-mL syringe filled with irrigation fluid drawn directly from the trocar. The syringe is mounted on the back of the device handle. The spacer is introduced through the dorsal portal and placed under direct vision. The sleeve is retracted, and the spacer is filled with the correct amount of irrigation fluid so that it unfolds. The spacer is now deployed from the handle by turning the green knob clockwise. The handle is withdrawn, and the spacer positioning is checked by moving the without restriction. The spacer does not dislocate. A second, much larger tear and repair are shown, and the similar placement of the spacer and the result are presented.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Examples of subacromial spacer introduction in a case with a small supraspinatus tear undergoing arthroscopic repair and the result after insertion in a case undergoing a larger repair. In the first part of the video, a small supraspinatus tear is shown, for which a single-row 1-anchor repair was performed. The operating room setup includes placing the patient in the beach-chair position; the portals used are the posterior, anterolateral, and lateral portals. Acromioplasty has been performed but is not shown in the video. The camera switches to the lateral portal as we start to measure the subacromial space length with a palpation hook. The dorsal portal is enlarged with a clamp. The device is unpacked and prepared with a 20-mL syringe filled with irrigation fluid drawn directly from the trocar. The syringe is mounted on the back of the device handle. The spacer is introduced through the dorsal portal and placed under direct vision. The sleeve is retracted, and the spacer is filled with the correct amount of irrigation fluid so that it unfolds. The spacer is now deployed from the handle by turning the green knob clockwise. The handle is withdrawn, and the spacer positioning is checked by moving the without restriction. The spacer does not dislocate. A second, much larger tear and repair are shown, and the similar placement of the spacer and the result are presented.