Resorbable transcondylar system for femoral fixation during LCA reconstruction

The product Created by: ST: Dr. Daniel J. McKernan, Toledo, Ohio, USA BTB: Dr. Paul H. Marks, Toronto, Ontario, CAN

The “Cross Pin” Bone-Tendon-Bone Soft-Tissue 2.7 mm Bone-Tendon-Bone 42 mm 3.3 mm Soft-Tissue 42 mm Material: PLA, Polilactic Acid Reabsorption: 2-4 years Idrolysis (CO2 + H2O)

The instruments Soft Tissue

The instruments Bone-Tendon-Bone

The sterile kit Two pins One interlocking trocar Two sleeves

The sterile kit

Surgical technique Soft Tissue and Bone Tendon Bone Femoral half tunnel: 25-30 mm depth Tibial tunnel

Surgical technique Harvest the Semitendinosus and Gracilis tendons

Surgical technique Fold the two grafts over a strong suture (Ethibond #4 or 5)

Surgical technique Whip stitch (Ethibond #2) the looped-over part of the graft as shown: it is important to create a secure and compact bundle

Surgical technique Mark the graft at 30 mm for later reference when placing it into the femoral half-tunnel

Surgical technique Choose the femoral rod of the same diameter of the tunnel Attach it to the guide frame

Surgical technique Insert the guide (attached to the appropriate size femoral rod) into the femoral tunnel until it touches the end

Surgical technique Assemble the sleeve over an interlocking trocar: note that the trocar is much longer then the sleeve interlocking trocar sleeve

Surgical technique Note how the trocar blocks itself: the sleeve-trocar assembly can rotate together

Surgical technique Drill the sleeve-trocar assembly through the two holes of the guide into the lateral side of the femur

Surgical technique Remove the guide frame from the knee, leaving only the two sleeves in the lateral aspect of the femur.

Surgical technique Note that a lot of saline solution comes out: this shows the right placement of the sleeves.

Surgical technique To verify furthermore the right placement of the two sleeves, use the scope and a trocar.

Surgical technique Pull the graft into the tunnel using a guide wire

Surgical technique During the graft placement, the saline outflow stops: this shows that the graft has filled the tunnel

Surgical technique Insert the RIGIDfix cross pins into the sleeves using the stepped pin insertion rod and mallet.

Surgical technique During the pin insertion the surgeon feels the press-fit sensation: the pin crosses through the soft tissue fibers and presses them towards the tunnel surface.

Surgical technique Remove the sleeves. The graft is now fixed in the femoral tunnel by two parallel absorbable pins.

Surgical technique Pay attention to remove the sleeves: pull it with the removal-tool in the straight direction, without twisting or bending.

Surgical technique Bone Tendon Bone Graft the central third from the patellar tendon Place one drill hole in the femoral plug for application of a stay suture

Surgical technique Bone Tendon Bone Assemble the sleeve over an interlocking trocar: note that the trocar is about so long as the sleeve interlocking trocar sleeve

Surgical technique Bone Tendon Bone Pull the graft is inside the half tunnel Drill the longer trocar through the femoral sleeves in order to create the holes on the bone plug

SUMMARIZING Femoral half tunnel: 25-30 mm lenght Place the guide/femoral rod into the femoral half tunnel Soft Tissue Bone Tendon Bone Drill the two sleeves into the lateral side of the femur Drill the two sleeves into the lateral side of the femur Pull the graft in place Pull the graft in place Insert the cross pins Drill the bone plug Insert the cross pins

The PRESS-FIT

In the ST technique: there is “press-fit” not “hanging on”!

there is “press-fit” not “hanging on”! In the ST technique: there is “press-fit” not “hanging on”! 7 mm 7 mm 3.3 mm 10.3 mm 3.3 mm 10.3 mm 7 mm

The dimensions of femoral rod and B-T-B pins 5.8 mm 9 mm 10.3 mm 16.5 mm 17.8 mm 19.8 mm 30 mm 30 mm 25 mm N.B.: 2.7 mm is the diameter of Bone Tendon Bone pins

Technical data for ST Ultimate load R = 623 N Stiffness K = 60 N/mm

Technical data for BTB Ultimate load R = 424 N Stiffness K = 74 N/mm

Cyclic loading tests Cyclic loading Average migration 1,4 mm Load n = 1000 cicles 150 N 10 N Time Average migration 1,4 mm

Orientation tests The ST tendons are whipstitched at the looped end, forming a tight bundle that is “press-fit” placed into the femoral tunnel. This allows RIGIDfix absorbable pins to cross the graft in any plane and provide rigid fixation.