Hamstring versus Bone-Patellar Tendon-Bone (BPTB) Grafts

Graft Strength

Although there is some debate, it appears that a graft retains only about half its initial strength in long-term follow-up [1]. Therefore an initial graft needs to be significantly stronger than the native ACL in order to produce an ultimate strength at least as strong (or stronger) than the original ACL. Based on a classic paper by Noyes, et al [2], we can estimate that the standard 10mm BPTP graft is initially about 110% as strong as the ACL at implantation. Thus after losing half of its strength its final strength is thought to be only about 55% that of the original ACL strength. The 2 strand semitendinosus (ST) and 2 strand gracilis (Gr) (2ST/2Gr) should be 238% as strong as native ACL, so that its ultimate strength will be about 119% of the original ACL. A 4 strand ST (4ST) is estimated at 280% as strong as the original ACL so its ultimate strength is about 140% of native ACL. . Thus the Hamstring graft is more than twice as strong as the BPTB graft .


Although complications can occur with any surgery, there are several specific problems that are seen more commonly in BPTB grafts than in hamstring grafts.

  • From Donor Site: BPTB harvest results in a low but definite incidence (about 1%) of patellar tendon rupture and patellar fracture (such as occurred in Carolina Panthers kicker Alan Casay and all star football player Jerry Rice) after reconstruction. This usually necessitates another operation for correction. Hamstring harvest on the other hand has no significant donor site problems.
  • Knee Stiffness: BPTB is associated with a higher rate of post-operative knee stiffness than HS grafts
  • Kneeling Pain: much higher with BPTB (54%) than HS (20%) [3].
  • Quadriceps Weakness: much higher with BPTB than HS
  • Hamstring Weakness: Some studies have shown no weakness after HS grafting, some have shown slight weakness. No functional problems have been reported.

Knee Stability

The primary goal of ACL reconstruction is restoration of knee stability. Dr Prodromos has performed a comprehensive review of all studies of stability after ACL reconstruction from 1990- 2004 published in the world’s English language literature [4]. The results of this meta-analysis showed that knees reconstructed with 4 strand Hamstring grafts had a 77% normal rate and a 4.4% abnormal rate. The BPTB graft group has a 66% normal rate and 5.9% abnormal rate. Additionally, the subgroup that used 4HS and an Endobutton on the femur and second-generation fixation method (not buttons or simple staples) on the tibia had the highest stability rates of all knees. This group has a normal rate of 80% and an abnormal rate of 1.7%.

In our practice, we reviewed 153 patients who had 4HS grafts with Endobutton femoral fixation and whipstitch/screw tibial fixation at 2 to 8 years after reconstruction [5]. We had no graft failures or ruptures. 96.9% of patients had a KT-1000 side-to-side difference of less than 3. These stability levels are the highest reported anywhere in the literature.


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