The PASTA Bridge – A Repair Technique for Partial Articular-Sided Rotator Cuff Tears: A Biomechanical Evaluation of Construct Strength

Rotator cuff tears can be classified as full-thickness or partial-thickness; the latter being further divided into the bursal surface, articular-sided, or intratendinous tears. A study analyzing the anatomical distribution of partial tears found that approximately 50% of those at the rotator cuff footprint were articular-sided and predominantly involved the supraspinatus tendon.¹ These partial-thickness articular-sided supraspinatus tendon avulsion tears have been coined “PASTA lesions.” Current treatment recommendations suggest that a debridement, a transtendon technique, or a “takedown” method of completing a partial tear and performing a full-thickness repair be utilized for partial-thickness rotator cuff repairs.

The primary goal of a partial cuff repair is to reestablish the tendon footprint at the humeral head. It has been argued that the “takedown” method alters the normal footprint and presents tension complications that can result in poor outcomes.^2-5 Also, if the full-thickness repair fails, the patient is left with a full-thickness tear that could be more disabling. The trans-tendon technique has proven to be superior in this sense, demonstrating an improvement in both footprint contact and healing potential.^3-5 This article aims to evaluate the biomechanical effectiveness of a new PASTA lesion repair technique, the PASTA Bridge,⁶ when compared with a traditional transtendon suture anchor repair.

MATERIALS AND METHODS

BIOMECHANICAL OPERATIVE TECHNIQUE: PASTA BRIDGE REPAIR

A 17-gauge spinal needle was used to create a puncture in the supraspinatus tendon approximately 7.5 mm anterior to the centerline of the footprint and just medial to the simulated tear line. A 1.1-mm blunt Nitinol wire (Arthrex) was placed over the top of the spinal needle, and the spinal needle was removed. A 2.4-mm portal dilation instrument (Arthrex) was placed over the top of the 1.1 blunt wire (Arthrex) followed by the drill spear for the 2.4-mm BioComposite SutureTak (Arthrex). A pilot hole was created just medial to the simulated tear using the spear and a 1.8-mm drill followed by insertion of a 2.4-mm BioComposite SutureTak (Arthrex). This process was repeated approximately 5 mm posterior to the centerline of the footprint. A strand of suture from each anchor was tied in a manner similar to the “double pulley” method described by Lo and Burkhart.³ The opposing 2 limbs were tensioned to pull the knot taut over the repair site and fixed laterally with a 4.75-mm BioComposite SwiveLock (Arthrex) placed approximately 1 cm lateral to the greater tuberosity.

BIOMECHANICAL OPERATIVE TECHNIQUE: CONTROL (4.5-MM CORKSCREW FT GROUP)

A No. 11 scalpel was used to create a puncture in the tendon for a transtendon approach. A 4.5-mm titanium Corkscrew FT (Arthrex) was placed just medial to the beginning of the simulated tear. The No. 2 FiberWire (Arthrex) was passed anterior and posterior to the hole made for the transtendon approach. A horizontal mattress stitch was tied using a standard 2-handed knot technique.

BIOMECHANICAL ANALYSIS

The proximal humeri with intact supraspinatus tendons were removed from 6 matched pairs of fresh-frozen cadaver shoulders (3 males, 3 females; average age, 49 ± 12 years). The shaft of the humerus was potted in fiberglass resin. For each sample, a partial tear of the supraspinatus tendon was replicated by using a sharp blade to transect 50% of the medial side of the supraspinatus from the tuberosity.^2,5 From each matched pair, 1 humerus was selected to receive a PASTA Bridge repair,⁶ and the contralateral repair was performed using one 4.5-mm titanium Corkscrew FT. Half of the samples of each repair were performed on the right humerus to avoid a mechanical bias. Each repair was performed by the same orthopedic surgeon.

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