Bidirectional-Ligament

Treatment For
Bidirectional Ligament Instability.

ELBOW ANATOMY AND BIOMECHANICS

LIGAMENT RECONSTRUCTION DESIGN

IMPLANTATION

INDICATIONS

Treatment for bilateral elbow ligament insufficiency after contracture release or interposition arthroplasty remains challenging.

Bidirectional Ligament Reconstruction Tray Components:

Large Cylindrical Ligament Retention Device.

Splined Nut Is Advanced On Transulnar Bolt To Compress Aggressively Teethed Plates.

Splined Nut Driver Allows Transulnar Bolt To Recede Into Driver As Nut Is Advanced.

Currently Practiced Ligament Reconstruction Technique:

A box loop ligament reconstruction is currently performed to treat bilateral ligament instability. This procedure requires a long ligament graft. Parallel drill holes are made in the humerus and ulna. The ligament graft is pulled through the humerus and ulna from medial to lateral and then through the adjacent bone tunnels in the reverse direction. Two grafts in each tunnel creates friction and makes equal tensioning difficult leading to varus and valgus forces. Substantial graft is wasted as ligament within the humerus and ulna does not contribute biomechanically once healing has occurred.

Design goals:

The development of the cylindrical ligament retention device (CLRD) originated as an effort to improve on the aforementioned box ligament approach. In particular, the focus was to minimize the waste of graft material and improve the ability to tension the ligament limbs in a symmetrical manner.

We aimed to stabilize the elbow while minimizing the length of ligament graft material that would be wasted by residing within bone.

Currently, if the ligament reconstruction requires additional stability, a non hinged or a hinged external fixator is employed but these large structures have a risk of pin tract infection.

Another current option for stabilizing the elbow is an internal joint stabilizer that represents an effective mechanical device but needs to be removed in a separate procedure once the ligaments have healed.

Another design goal was to stabilize the elbow without using a mechanically hinged external or internal fixator.

The third design goal was to create an implant that does not need to be removed at a later time.

Simultaneous ligament reconstruction features:

The KTE Simultaneous Ligament Reconstruction Kit accomplishes these design goals.

Assembly includes two tensioning plates, two trans-ulnar bolts and two nuts.

Tensioning plate is made of ASTM F-136 Titanium alloy.

Trans-ulnar bolts are machined from ASTM F-136 Titanium alloy.

Cylindrical Ligament Reconstuction Device prevents graft from being wasted.

Smooth opening allows graft to slide, which equalizes tension.

The plates have the ability to conform to the topography of the ulna due to custom designed mating surfaces.

Implantation steps.

Lateral decubitus position. A paratricipital approach is used and both collateral ligaments are released.

A perforated instrument tray contains all of the instruments that are required for implantation. Small holes along the bottom and sides allow for immediate cleaning and drying of instruments and equipment. The tray includes a raised section to prevent instrument movement and is practical to store, clean and use in any type of operating room.

Identifying the centerline of ulnohumeral rotation allows placement of an isometric graft. After the collateral ligaments are reflected, bony landmarks are used to place two K-Wires.

Step 1: Drill two K-wires into the medial and lateral epicondyle using bone landmarks .
Step 2: Use drill guide to place another parallel K-wire that is proximal and posterior to the original K-wire.
Step 3: Remove the initial K-wires.
Step 4: Drill holes using cannulated drill bit through the medial and lateral epicondyle. The drill is used to connect the two openings and allow for passage of the CLRD.
Step 5. Pass the grafts through the CLRD eyelets.
Step 6. The grafts are now in an isometric location where they will heal to bone.

The ligament graft is placed through one hole of the Cylindrical Ligament Reconstruction Device .

PDS #2 (Ethicon, Johnson & Johnson, NJ) suture can be used to augment the ligament reconstruction if the graft is not considered strong enough. Each PDS #2 adds 109 N of additional strength.

The drill hole in the humerus allows easy passage for the CLRD.

The CLRD is pushed to the other side to allow for second ligament graft to be passed through eyelet.

The tendon graft is retrieved from the other side of the distal humerus.

Once the second tendon is secured, the CLRD is pulled back to lie within the confines of the outside of the distal humerus.

Because the CLRD slides within the bone, equal tension can be imparted to the graft when medial and lateral force is applied.

Accurate transulnar bolt placement requires the use of a drill guide, which assists in positioning the drill holes 9 mm away from the subcutaneous border. The drill guide has a small central hole that is used for the placement of a K-wire. The supinator crest can be used as a landmark or the K-wire can be positioned so as to go through the insertion of the LUCL, which is 24.4 mm (95% CI, 22.7-26.1) distal to the radiocapitellar joint line (Berholdt 2020).

Each side is tensioned with 40 N of force.

Tension is applied to the tendon grafts while a counterforce is applied to the olecranon to securely seat the elbow. 80 N in total represents a substantial sub maximal pull. A study has demonstrated that a maximal pull by an orthopaedic resident averages 99 N.

The screws are then tightened by hand while the tension is maintained. Tightening the screws exerts a compressive force between the ulna and the plate. Substantial compression allows for secure healing of the ligament to the bone. When absorbable suture augmentation is used, the suture ends are tied over the dorsal aspect of the elbow. The elbow is now stable and the construct does not need to be removed. A hinged brace should be all you need to protect the reconstruction.