ACL Reconstruction - Hamstring Justification

The most commonly used grafts are patellar tendons and hamstring tendons. Dr. Rogerson believes hamstring tendons are more advantageous for the following reasons:

1. Produces better initial strength and stiffness.
2. Quadruple graft results in larger cross-sectional diameter than bone-patellar-bone.
3. Initial fixation required for daily living activities is exceeded.
4. Anterior knee pain is less.
5. Quadriceps weakness is avoided.
6. Incision is cosmetically better.
7. Morbidity (complications from the graft) is lower.
8. Return to activity time is comparable.

Strength and Stiffness
The advantage to multiple bundle hamstring graft is that it is stronger and stiffer. A multiple bundle hamstring tendon, that is tensioned equally, is 250% the strength of the normal ACL. (Ref: www.isssakos.com)

Some orthopedic surgeons believe stiffness is more significant than strength. Graft failure may be due to graft lengthening or stretching that leads to laxity. Hamstring grafts have a stiffness of 2X the patellar tendon and 3X the normal ACL stiffness. (Ref: www.isssakos.com)

Both hamstring and patellar grafts exceed the normal ACL strength and stiffness therefore should be more resistant to any force that may stretch or/and rupture the new tendon.

Greater cross sectional graft material
As seen in the table below, the cross sectional area of the hamstring graft is larger. The average cross sectional quadruple hamstring graft will measure 7-9mm in diameter.

Initial fixation required for daily living activities is exceeded
Initial fixation for ACL reconstruction is estimated to require 450 N for activities associated with daily living. Dr. Rogerson’s fixation methods of the hamstring exceeds this number. The Mitek RIGIDfix™ femoral fixation resists 623.5 N force and the Mitek Tibial Intrafix Resists 937 N.

Anterior knee pain is less
Pain in the front (anterior) of the knee is a well-known complication associated with patellar tendon ACL reconstruction. It is significantly reduced with the hamstring graft.

Quadriceps weakness
Quadriceps (the muscle in the front of the upper leg) weakness is another significant concern with patellar tendon. Graft techniques have reported that patellar tendons have additional low-velocity knee extensor strength deficit that was not associated with hamstring graft. (Ref: The American Journal of Orthopedics – Nov 2002)

Incision is cosmetically better
The incision for a hamstring tendon is considered to be cosmetically better than the incision for a patellar tendon. The front of the knee is under greater tension and scars more hypertrophically. Also, the front knee patella incision is more visible than the lower anterior medial tibial hamstring incision. (Ref: The American Journal of Orthopedics – Nov 2002)

Morbidity (complications) is lower
Morbidity has been drastically reduced through the use of arthroscopic techniques for both hamstring and patellar tendon ACL reconstruction. The patellar tendon technique, however, has long been associated with considerable morbidity at the donor site. The most serious complication of patellar tendon ACL technique is fracture of the knee cap (patella). The gap in the patellar tendon, resulting from tendon removal, is clinically evident for years after the surgery. Others have shown that closure of the tendon results in the risk of patellar baja. Patellar baja is a shortening of the patellar tendon as it heals, which results in increased pressure on the posterior side of the patella and potentially early arthritis.

Return to activity time is comparable
Physical therapists are reporting a faster, earlier recovery time with hamstring tendon verses patellar tendon techniques. This reduces the rehabilitation time making your return to activity easier. Time to full graft maturation is similar.

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3/1/2006

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