Strength and Regrowth of Hamstring Tendons After Hamstring Autograft Anterior Cruciate Ligament Reconstruction

Congenital bilateral absence of the semimembranosus muscles

Variations of the anatomy of the hamstring muscle complex are uncommon. In particular, absence of some or all of the hamstring muscles is rarely described in the literature. This report presents a case of absent semimembranosus musculature detected incidentally on knee magnetic resonance imaging (MRI), then found to be bilateral on MRI of both thighs performed shortly thereafter. Imaging also demonstrated atypical morphologies of the semitendinosus and biceps femoris muscles in both thighs.

Role of gracilis harvesting in four-strand hamstring tendon anterior cruciate ligament reconstruction: a double-blinded prospective randomized clinical trial

PURPOSE

Weakness in knee flexion following anterior cruciate ligament (ACL) reconstruction is one of the key issues in the treatment of an ACL tear. The purpose of this study was to examine and compare clinical outcome measures of ACL reconstruction using semitendinosus autograft (ST) versus semitendinosus + gracilis (ST/G) reconstructive techniques.

METHODS

In a double-blind randomized clinical study, 19 patients with an ACL tear underwent either ST (59) or ST/G (61) and observed for 1 year. Both patients and the final examiner were unaware as to the type of graft received. Patients were evaluated according to subjective criteria, functional assessment tests, knee isometric torques, knee laxity using KT-2000 and knee range of motion.

RESULTS

The study included 21 (17.6 %) female and 99 (82.4 %) male patients with a mean age of 29.9 ± 7.8 in the ST group and 32.4 ± 6.3 in the ST/G group. There were no significant differences found in surgical complications; IKD; Knee injury and Osteoarthritis Outcome Score; Lysholm; strength of the knee isometric flexors; and flexion and extension loss between the two groups. At the final visit, 86.9 % of ST group and 89.6 % of ST/G group had side-to-side difference of laxity <3 mm (n.s.).

CONCLUSIONS

Since anterior cruciate ligament reconstruction using quadrupled ST is more technically demanding than doubled STG and with there being no difference in outcomes and complications, no compulsory advice should be made on the former technique. However, gracilis harvesting may not be necessary based on the function and strength of the knee.

LEVEL OF EVIDENCE

Randomized controlled trial, Level I.

Tendon and fascial structure contributions to knee muscle excursions and knee joint displacement

BACKGROUND

Semitendinosus and gracilis muscles whose tendons are used in surgical reconstruction of the anterior cruciate ligament maintain their contractile ability, and a limited decrease of hamstring muscles force is observed postoperatively despite important changes. The goal was to quantify the influence of the myofascial structures on excursions and moment arms of knee muscles to attempt explaining the above-mentioned post-surgical observations.

METHODS

Hamstring harvesting procedures were performed by a senior orthopaedic surgeon on seven lower limbs from fresh-frozen specimens. Femoro-tibial kinematics and tendons excursion were simultaneously recorded at each steps of the surgery.

FINDINGS

No significant difference was demonstrated for excursions and moment arms after tenotomies and gracilis tendon harvesting (P≥0.05). The first significant semitendinosus excursion (P<1.17×10(-4)) and moment arm (P<6.88×10(-5)) decrease was observed after semitendinosus tendon harvesting (46% of the initial excursion).

INTERPRETATION

Gracilis and semitendinosus myofascial pathway is crucial for force transmission towards the knee joint.