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Open transfer of the pectoralis minor through a deltopectoral approach has been described to treat irreparable tears of the upper two-thirds of the subscapularis. We present a less invasive arthroscopic-assisted technique for this transfer. Atraumatic dissection of the pectoralis minor and harvesting of the tendon with a bone chip from the coracoid process allow strong fixation with a double-button device on the lesser tuberosity. This arthroscopic technique allows assessment and treatment of associated intra- or extra-articular lesions and represents a promising option for the management of irreparable tears of the subscapularis.
Technique Video
See video under supplementary data.
Subscapularis (SSC) tendon tears are disabling lesions that lead to pain and loss of function.
A comparative study on the biomechanical and histological properties of bone-to-bone, bone-to-tendon, and tendon-to-tendon healing: An Achilles tendon-calcaneus model in goats.
However, in the case of an irreparable tear, when the tendon is retracted to the level of the glenoid, with grade III or IV fatty infiltration, tendon repair is no longer an option,
Transfer of the clavicular or sternocostal portion of the pectoralis major muscle for irreparable tears of the subscapularis. Technique and clinical results.
Transfer of the clavicular or sternocostal portion of the pectoralis major muscle for irreparable tears of the subscapularis. Technique and clinical results.
Transfer of the clavicular or sternocostal portion of the pectoralis major muscle for irreparable tears of the subscapularis. Technique and clinical results.
Transfer of the Pm is an invasive procedure that involves extensive dissection. This transfer, relying on tendon-to-bone healing, was described in 1997 by Wirth and Rockwood,
showing improvements in active forward flexion (50°) and the Constant score (41 points) without excessively limiting external rotation. This technique involves harvesting the Pm with a bone chip from the coracoid process, and it is suitable for that 41% of patients with an isolated SSC tear presenting with a grade III lesion according to the series and classification of Lafosse et al.
The purpose of this Technical Note is to describe an arthroscopic-assisted method to transfer the Pm with a bone chip from the coracoid process for the treatment of irreparable tears of the SSC (Video 1).
Surgical Technique
Patient Positioning, Diagnostic Arthroscopy, and Portal Placement
The patient is positioned in the beach-chair position with no traction on the upper limb to easily mobilize the humerus as needed during the procedure. The arthroscope is initially introduced through the standard posterior portal. A diagnostic examination with special emphasis on the anterosuperior cuff and long head of the biceps is performed to confirm the presence of an irreparable tear of the SSC tendon. Then, 3 anterior portals are used consecutively: anteroinferior (AI) portal, anterolateral portal, and superior coracoid expanded portal (SCEP) (Fig 1).
Fig 1Right shoulder portals: standard posterior portal; anterolateral portal, 2 cm distal to anterolateral corner of acromion; anteroinferior portal, 2 cm distal to coracoid tip and just lateral to conjoint tendon; and superior coracoid expanded portal, just above coracoid process.
While the arthroscope is positioned in the posterior portal, a radiofrequency ablation device (VAPR; DePuy Mitek, Raynham, MA) is inserted through the AI portal and the rotator interval is dissected. The coracohumeral ligament, middle glenohumeral ligament, long head of the biceps, and anterior capsule are all excised, and the coracoid process, conjoint tendon (CT), and coracoacromial ligament are all dissected and identified (Fig 2).
Fig 2Intra-articular view of right shoulder in beach-chair position through posterior portal. (CAL, coracoacromial ligament; CP, coracoid process; CT, conjoint tendon; G, glenoid; HH, humeral head.)
The arthroscope is then removed from the posterior portal and inserted into the anterolateral portal with the radiofrequency ablation device still in the AI portal. After identification of the lateral aspect of the coracoid, CT, and coracoacromial ligament, progressive dissection is performed over the coracoid until the insertion of the Pm, at the medial aspect of the coracoid, is observed while care is taken to preserve these structures (Fig 3).
Fig 3Extra-articular view of right shoulder in beach-chair position through anterolateral portal. (CAL, coracoacromial ligament; CP, coracoid process; CT, conjoint tendon; Pm, pectoralis minor.)
Once the insertion of the Pm is identified, the SCEP is established and dissection is continued through this access. The anterior border of the Pm is dissected and is isolated from the CT by releasing any expansion between the 2 tendons (Fig 4). During this step, the musculocutaneous nerve is located and is released if its branch going to the CT is thought to be in the way of the transfer. The posterior border of the Pm is then identified and carefully dissected with only coagulation until visualization of the brachial plexus.
Fig 4Extra-articular view of right shoulder in beach-chair position through anterolateral portal. The interval (I) between the pectoralis minor (Pm) and conjoint tendon (CT) is shown. (CP, coracoid process.)
The SCEP is enlarged to 20 mm to allow the introduction of a 10-mm chisel that is used to perform an osteotomy of the medial wall of the coracoid process with the Pm tendon (Fig 5). Special care must be taken to prevent lesions to the brachial plexus during this step.
Fig 5Extra-articular view of right shoulder in beach-chair position through anterolateral portal. The pectoralis minor (Pm) is detached with a coracoid process (CP) bone chip. (I, interval.)
Once full mobilization of the bone chip with the Pm is possible, the bone chip is exteriorized through the SCEP with a retriever and sutured to a double-button device (ZipTight Fixation System for AC Joint Repair; Biomet, Warsaw, IN) so that the round button is fixed on the cortical side of the chip and the rest of the system (suture loop and small button) remains on the cancellous side of the bone chip (Fig 6). To accomplish this, a transosseous suture forming a closing loop is made through the chip with a No. 2 high-strength nonabsorbable suture (MaxBraid; Biomet) with a small needle. Once this step is completed, the tendon is reinserted into the shoulder.
Fig 6View of right shoulder in beach-chair position. Straight button (SB), suture loop (SL), round button (RB), and transosseous sutures (TS). It should be noted that the round button is attached to the cortical side of the bone chip, whereas the rest of the system is on the cancellous side of the bone chip.
Preparation of Lesser Tuberosity and Fixation of Pm
The footprint of the SSC is prepared with an arthroscopic burr (4.0-mm Formula burr; Stryker, Kalamazoo, MI) through the AI portal, creating a concave zone matching the shape of the bone chip. This preparation needs to be thorough to ensure good bone-to-bone contact and to avoid anterior impingement between the round button and the CT during internal rotation.
An eyelet drill pin is introduced through the AI portal and positioned at the center of the footprint preparation from anterior to posterior (this entry point can be translated superiorly at the superior part of the lesser tuberosity in cases of anterosuperior cuff tears) (Fig 7). Then, the pin is drilled across the humeral head, through the posterior humeral cortex, while care is taken to exit higher than 4.5 cm distal to the posterolateral angle of the acromion to avoid any injury to the axillary nerve. The drill pin is retrieved posteriorly through a small skin incision.
Fig 7View of right shoulder in beach-chair position through anterolateral portal. The eyelet guide is in the center of the subscapularis footprint preparation through the anteroinferior portal.
A 4.5-mm cannulated drill bit is passed over the pin to make a bone tunnel until crossing the posterior cortex. Care must be taken to maintain the drill pin in place during this step.
The sutures exiting from the coracoid bone chip are retrieved through the AI portal passing underneath the coracoid process and posterior to the CT (Fig 8) and are loaded in the eyelet of the drill pin and retrieved posteriorly by pulling the pin. The sutures are then carefully pulled to apply the straight button over the humeral posterior cortex. Once this is performed, the traction sutures of the ToggleLoc are pulled alternately until good compression of the bone chip on the lesser tuberosity is achieved under arthroscopic control. With the transfer in place, passive internal and external rotation is performed to check for any anterior impingement between the implant and the CT (Fig 9, Table 1).
Fig 8Extra-articular view of right shoulder in beach-chair position through anterolateral portal. The implant's free sutures (FS) are being pulled below the coracoid process (CP) through the anteroinferior portal. (CT, conjoint tendon.)
Fig 9(A) Extra-articular view of right shoulder in beach-chair position through anterolateral portal. The pectoralis minor (Pm) transfer is in place after closing the implant's suture loop. (B) Intra-articular view of right shoulder through posterior portal. The correct positioning of the transfer is checked. One should note the relation between the conjoint tendon (CT), pectoralis minor (Pm), and subscapularis (SSC) remnant. (CP, coracoid process; G, glenoid; HH, humeral head.)
Partial repair of the subscapularis should be performed before the transfer.
The surgeon should use a sharp chisel when performing the osteotomy to avoid fractures.
The entire insertion of the tendon should be harvested.
Thorough preparation of the footprint should be performed, matching the shape of the bone chip.
Pitfalls
Failing to achieve complete visualization of the pectoralis minor insertion may lead to brachial plexus injury while harvesting.
A posterior drill pin exit that is too low may lead to axillary nerve injury.
If the traction sutures are not symmetrical and not pulled in an alternating manner when closing the system, internal loops may be created, leading to later loosening.
The technique is only applicable to skillful surgeons.
Despite advancement in treatments for rotator cuff tears and cuff tear arthropathy, management of irreparable anterosuperior cuff tears in younger patients remains challenging. Transfer of the Pm is a promising procedure that can restore a functional and pain-free shoulder in this group of young patients with Lafosse grade III tears of the SSC or Collin type A lesions, as shown by Paladini et al.
Lafosse grades IV and V are contraindications for this procedure.
Because of its anatomic situation and function, the Pm represents a good candidate to restore internal rotation because it has the following:
•
A better vector of action in comparison with transfer of the pectoralis major (Fig 10)
Fig 10Situation of pectoralis minor versus pectoralis major in chest wall. One should note that the pectoralis minor origin is posterior with respect to the pectoralis major; thus the traction vector is closer to that of the subscapularis.
No excessive muscle tension after the transfer is in place
•
Minimal exposure and tissue damage
Arthroscopic assistance makes it a less invasive procedure with a shorter recovery time. In addition, it has been proved that surgical repair around tendon insertions between homogeneous tissues (bone to bone) shows better mechanical and histologic healing properties than between heterogeneous tissues (bone-to-tendon healing)
A comparative study on the biomechanical and histological properties of bone-to-bone, bone-to-tendon, and tendon-to-tendon healing: An Achilles tendon-calcaneus model in goats.
; therefore, the success rate of the procedure could be enhanced by the use of bone-to-bone fixation (Table 2). In conclusion, we believe that arthroscopic-assisted Pm transfer combined with strong bone-to-bone fixation to the lesser tuberosity represents a promising option for the management of irreparable superior tears of the SSC; nevertheless, extensive knowledge of the anatomy of this particular region is advised to avoid injury to the musculocutaneous and axillary nerves during dissection.
Table 2Advantages and Disadvantages
Advantages
Minimally invasive arthroscopic procedure
Harvest of entire insertion of tendon with bone chip to avoid muscle wasting and to improve healing process
Strong bone-to-bone fixation
Arthroscopic assessment and treatment of associated lesions
Easy conversion to open surgery if needed
Disadvantages
Risk of lesions to brachial plexus and musculocutaneous nerve during dissection
Technically demanding: perfect knowledge of anatomy of nerves of shoulder is mandatory
Arthroscopic-assisted pectoralis minor tendon transfer in a right shoulder with a previous attempt at subscapularis repair. The patient is placed in the beach-chair position without arm traction.
A comparative study on the biomechanical and histological properties of bone-to-bone, bone-to-tendon, and tendon-to-tendon healing: An Achilles tendon-calcaneus model in goats.
Transfer of the clavicular or sternocostal portion of the pectoralis major muscle for irreparable tears of the subscapularis. Technique and clinical results.
The authors report the following potential conflict of interest or source of funding: M.C. receives support from FH Orthopedics, Biomet, Arthrex. Paid for meeting expenses in past. P.V. receives support from Arthrex, Biomet, FH Orthopedics. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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