Hamstring Harvest for ACL Reconstruction : Wheeless' Textbook of Orthopaedics

- Technique:
- place the leg in a figure of 4 position;
- make a small longitudinal incision opposite the tibial tuberlce, midway between the tubercle and the the posterior edge of the tibia;
- palpate the pes anserinus;
- generally only the gracilis and semitendinosus will be felt, since the sartorius thins out well proximal to its insertion;
- attempt to identify the saphenous nerve;
- make an incision directly over and in line with the gracilis tendon;
- open the tendon sheath and release adhesions and fibrous extensions that attach to the sheath;
    - pes anserinus is exposed through a short verticel incision;
    - semitendinosus and gracilis tendons are harvested proximally w/ appropriately sized tendon stripper; (Brand type tendon stripper);
- residual muscle is removed;
- semiT should be placed in a moistened sponge, but is not be submerged in saline, since this may cause tendon swelling;
- paratenon surrounding the semitendinosus should be preserved;
    - careful to avoid saphenous nerve damage;
          - references:
                - Prevalence of saphenous nerve injury after autogenous hamstring harvest: an anatomic and clinical study of sartorial branch injury.
                - A prospective randomised study of the effect of skin incision angle on infrapatellar neuritis and alaterd skin sensation in anterior cruciate ligament reconstruction with semitenindous/gracilis grafts.

    - preparation of the graft:
          - Twisting and Braiding Reduces the Tensile Strength and Stiffness of Human Hamstring Tendon Grafts Used for ACL Reconstruction.
          - Histological and biomechanical studies of inter-strand healing in four-strand autograft anterior cruciate ligament reconstruction in a rabbit model.

    - fate of the harverst site:
- in report by Eriksson K, et al, authors evaluated fate of the semiT muscle, after ACL reconstruction;
                 - the study included were 16 consecutive patients;
- ACL reconstruction was performed with a quadruple semitendinosus tendon graft using the EndoButton technique;
- of the patients, 75% showed regeneration of their semitendinosus tendons;
- neotendons all inserted below knee joint where they had fused with gracilis tendon to a conjoined tendon inserting in the pes anserinus;
- semitendinosus muscle had a smaller cross-sectional area on the operated side but none showed total atrophy;
- isokinetic strength of the hamstrings and quadriceps was significantly lower in the operated leg than in the nonoperated leg.
- in the report by Ferretti A, et al, the authors describe the histologic course of regenerated tissue simulating the semitendinosus tendon in three patients after anterior cruciate ligament reconstruction with doubled semitendinosus and gracilis tendons;
- specimens were retrieved during revision surgery for removal of tibial hardware at 6, 24, and 27 months, respectively;
- resisted flexion during physical examination in all patients revealed a "string" on the posteromedial aspect of the knee that was quite evident, suggesting the presence of a regenerated semitendinosus tendon;
- well-defined fibrous band was identified about 3 cm proximal and medial to the pes anserinus, reproducing the pathway of the native semitendinosus tendon;
- in both of the specimens retrieved 2 years postoperatively, all of the central, thicker portion of each specimen was occupied by well-oriented tendon-like fibers together with uniformly distributed spindle-shaped cells that had appearance of mature tenocytes arranged in orderly rows;
       - references:
               - Regeneration of the Semitendinosus Tendon after Its Use in Anterior Cruciate Ligament Reconstruction. A Histologic Study of 3 Cases
               - Semitendinosus muscle in anterior cruciate ligament surgery. Morphology and function.
               - Semitendinosus Regrowth. Biochemical, Ultrastructural, and Physiological Characterization of the Regenerate Tendon.