Suspension button constructs restores posterior knee laxity
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Dislocated tibial avulsions of the posterior cruciate ligament (PCL) require surgical intervention. Several arthroscopic strategies are options to fix the fragment and restore posterior laxity, including two types of suspension button devices: adjustable (self-locking) and rigid knotted systems. The hypothesis was that a rigid knotted button construct has superior biomechanical properties regarding laxity restoration compared with an adjustable system. Both techniques were compared with standard screw fixation and the native PCL.

60 porcine knees were dissected. The constructs were tested for elongation, stiffness, yield force, load to failure force, and failure mode in a material testing machine. Group N (native, intact PCL) was used as a control group. In group DB (Dogbone™), TR (Tightrope™), and S (screw), a standardized block osteotomy with the osteotomized fragment attached to the PCL was set. The DB and TR groups simulated using a suspension button system with either a rigid knotted (DB) or adjustable system - TR. These groups were compared to a screw technique (S) simulating antegrade screw fixation from posterior.

--Comparing the different techniques (DB, TR, S), no significant elongation was detected; all techniques achieved a sufficient posterior laxity restoration.

--Significant elongation in the DB and TR group was detected compared with the native PCL (N).

--In contrast, screw fixation did not lead to significant elongation.

--The stiffness, yield load, and load to failure force did not differ significantly between the techniques.

--None of the techniques reached the same level of yield load and load to failure force as the intact state.

Conclusively, arthroscopic suspension button techniques restores posterior laxity enough and achieves power comparable to open antegrade screw fixation.