ACL Graft: Bone-Patellar Tendon-Bone or "BTB"

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Bone-Patellar Tendon-Bone (aka “BTB”) graft, is a strip of soft tissue removed from the middle part of the patellar tendon – the tendon that connects the patella (knee cap) to the upper tibia (shin bone).  When it is removed, it is harvested with a block or dowel of bone intact on both ends.  One of the bone blocks comes from the lower end of the patella, and the other bone block is from the upper tibia.  When implanted for the ACL, the bone plugs from the graft are seated into the bone sockets in the knee at either side of the reconstructed ligament. 

ADVANTAGES:

  1. It provides bone to bone healing, which theoretically occurs faster than soft tissue to bone healing, so theoretically one can rehabilitate the shoulder more quickly.
  2. Biomechanical studies have shown that the healed BTB graft results in the stiffest construct, and restores the translation and rotation of the knee most closely to ‘normal’.
  3. Most studies show the re-tear rates with BTB are low (generally felt to be lower than re-tears with soft tissue grafts)
  4. It is less ‘controversial’ – in the United States, the BTB is the most commonly-employed graft in the treatment of elite athletes.  If you do happen to re-tear a BTB, few would argue that the surgeon could’ve used a stronger graft.

DISADVANTAGES:

  1. Studies indicate that upwards of 20% of persons will suffer from some degree of ‘anterior knee pain’ after BTB reconstructions (pain at the front of the knee).  Depending on the patient, this can be a mild nuisance, or in some cases disabling enough that kneeling, squatting, running and cutting sports can be difficult.  This risk can probably be minimized if the surgeon is careful about which patients are and are not great candidates for the BTB graft.
  2.  Some studies have indicated that at 10-year follow-up, up to 40% of patients may develop radiographically evident but clinically asymptomatic arthritis of the knee (i.e. Visible on X-rays but the patient has no symptoms). [i]
  3. The complication rate is quite low, but BTBs grafts carry a slight risk of patella fracture, tendon rupture, knee stiffness/knee extension loss, or chronic quadriceps weakness.

The Take Home Message:  For me, the BTB is the “Luxury Sports Car of Grafts” – It’s build for speed and power, it’s sexy, it wins races, but it comes at a potential cost, and it may be more than some people need. I prefer using the BTB graft for my patients who are in the athletic population, unless there are specific patient variables that make me think it is not the best choice or contraindicated. 

[i] Pinchewski, LA, et al. American Journal of Sports Medicine. 2016 Dec;44(12):3083-3094.