Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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The Bio-Tenodesis Screw System

We perform all arthroscopic shoulder procedures in the lateral decubitis position under general anesthesia. Five to 10 pounds of balanced suspension are used with the arm in 20 degrees to 30 degrees of abduction and 20 degrees of forward flexion (Star Sleeve Traction System, Arthrex, Inc., Naples, FL). Diagnostic glenohumeral arthroscopy is performed through a standard posterior portal with an arthroscopic pump maintaining pressure at 60 mmHg.

An anterosuperolateral portal is created using a spinal needle to localize the portal site. A cannula is inserted above the biceps at the superior edge of the safe zone bordered by the biceps superiorly, subscapularis tendon inferiorly and the glenoid medially. The biceps/labrum complex and the LHB are assessed. A complete assessment of the biceps tendon is performed by pulling the intertubecular portion of the biceps tendon intra-articularly and assessing the amount of degeneration, partial tearing, and instability.

The technique described by Lo and Burkhart  utilizes a Bio-Tenodesis Screw system (Arthrex, Inc., Naples, FL), which uses a uniquely designed driver for inserting an interference screw. The cannulated driver is specially designed with a reverse threaded sleeve and thumb piece on the driver shaft.

The pitch of the threads on the sleeve are equal and opposite in direction to the pitch of the threads on the Bio-Tenodesis screw. This design allows the biceps tendon to be maintained at the bottom of the bone socket under tension as the Bio-Tenodesis screw is advanced in the bone socket by the hex-driver and by the reverse threaded pitch of the thumb sleeve. Fixation is achieved using a bio-absorbable PLLA (poly-L-lactic acid) cannulated screw. These BioTenodesis interference screws are available in three diameters (7 to 9 mm) and are 23 mm in length.

After completion of diagnostic arthroscopy, any tendon degeneration is debrided. If a concomitant rotator cuff tear is present, a lateral portal is established directly through the defect created by the torn rotator cuff.

Two racking stitches are placed into the biceps tendon. Sutures are placed approximately 1 to 1.5 cm distal to the biceps origin from the superior labrum and are then retrieved through the lateral or anterosuperolateral portal.The racking sutures tightly grip the degenerative biceps tendon. The biceps tendon is then severed from the superior labrum using electrocautery or arthroscopic scissors.

The tendon is then exteriorized extra-corporeally through the anterosuperolateral portal. Flexion of the elbow allows a greater length of tendon to be pulled through the skin. The diameter of the tendon is then measured using the slotted measuring plate on the BioTenodesis driver.

Typically the tendon measures approximately 8 mm in men and 7 mm in women. If the tendon will not fit easily through the 8 mm hole, the end of the tendon is tapered such that it will fit through the 8 mm slotted measuring plate. It is important that the tendon fit rather easily through the plate, as this will make insertion into the bone socket much easier later in the case. A Krakow whip stitch is placed in the tendon such that the suture ends exit the superior surface of the tendon 5 mm from its free end and then the racking sutures are removed.

Next, a bone socket is created in the greater tuberosity, approximately 5 mm posterolateral to the top of the bicipital groove. A 2.4 mm guide wire is initially placed and is then over-reamed with a cannulated headed reamer (Arthrex Inc; Naples, FL). The bone socket is reamed to the size of biceps tendon previously measured (usually 7 or 8 mm in diameter) and to a depth of 25 mm to accommodate a screw length of 23 mm.

If there is not an associated rotator cuff tear involving the supraspinatus tendon, the bone socket should be drilled at the top of the bicipital groove. After the biceps tenodesis portion of the procedure, two or four suture tails (depending on the technique) will be exiting the BioTenodesis screw construct.The whip-stitch sutures are then passed through a loop of suture at the end of the cannulated driver.

The driver tip is advanced to the end of the tendon (on its superior surface). In this position, the biceps tendon can be manipulated and controlled by the cannulated driver tip. Alternatively, the whip-stitch sutures can be threaded through the cannulated driver. This has the advantage of making manipulation of the biceps tendon easier and has become our preferred method. The disadvantage is that only two suture strands (rather than four) will protrude from the BioTenodesis screw.

The driver tip is used to push the biceps tendon down to the base of the previously drilled bone socket. A BioTenodesis screw (the same size as the drilled socket) is then advanced by turning the driver handle while holding the thumb plate that is attached to the reverse threaded sleeve. This allows the screw to be advanced while the tendon is maintained in a stationary position at the base of the bone socket.

This assures an adequate bone-tendon-screw interface within the bone socke and eliminates the need for transosseous drilling. We prefer to avoid transosseous drilling  to eliminate any potential risk to the axillary nerve. The two or four sutures exiting the BioTenodesis screw should be used in place of a suture anchor to augment the rotator cuff repair or can simply be cut if no cuff tear is present.

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