Clinical Comparison of Femoral Nerve Versus Adductor Canal Block Following Anterior Ligament Reconstruction

Adequate pain control following anterior cruciate ligament reconstruction (ACL) often
requires a regional nerve block. The femoral nerve block (FNB) has been traditionally
employed. More recently, ultrasound application to regional nerve blocks allows for the use
of alternatives such as the adductor canal block following ACL reconstruction. In 2009,
Manickam et al. were the first to describe the ultrasound guided adductor canal technique for
the purposes of knee joint analgesia. Unlike other traditional techniques that seek to cause
a sensory as well as a motor blockade, the adductor canal block attempts to spare the motor
block of the neighboring distributions in an attempt to offer selective analgesia and
strength preservation. Chisholm et al demonstrated the adductor canal block provides similar
and adequate postoperative analgesia when compared to the FNB, following arthroscopic ACL
reconstruction with patellar tendon autograft. Their study focused on analgesia and did not
evaluate quadriceps function or impact on rehabilitation. Sharma et al drew the first
association between femoral nerve blocks and increased fall risk due to muscle weakness in
total knee arthroplasty population. A randomized, blinded study to compare quadriceps
strength following adductor canal versus FNB was performed by Kwofie et al. They showed that
compared with FNB, adductor canal block results in significant quadriceps motor sparing and
significantly preserved balance. These studies focused on acute muscle weakness after
regional anesthesia and its relation to safety. Quadriceps function is very important in
rehabilitation of ACL reconstruction. Luo et al demonstrated long term deficits related to
FNB. They demonstrated that patients treated with FNB after ACL reconstruction had
significant isokinetic deficits in knee extension and flexion strength at 6 months when
compared with patients who did not receive a nerve block. Patients without a block were 4
times more likely to meet criteria for clearance to return to sports at 6 months. In
addition, Krych et al found significantly inferior quadriceps strength and function at 6
months in FNB group. Based on the available literature, we aim to compare femoral nerve
versus adductor canal block in regards to pain control and muscle strength in ACL
reconstruction patients until return to sport.

Inclusion Criteria:

- Males & Females ages 16-30 yrs

- Undergoing ACL reconstruction by Co-Investigator (Walter Lowe)

- Receiving peri-operative FNB or ACB

Exclusion Criteria:

- Not enrolled within the COFAKS study

- Receiving intrathecal nerve blockade or no blockade