Lumbar Plexus Block Versus Quadratus Lumborum Block for Primary Anterior Total Hip Arthroplasty: A Non-inferiority Trial

In an attempt to accelerate recovery many orthopedic surgeons have opted to utilize a direct anterior approach (DAA) as opposed to the more traditional posterolateral approach (PLA) in regards to total hip arthroplasty (THA). The DAA technique involves dissection of muscular planes for insertion of components resulting in less tissue damage as compared to PLA. Traditionally the study team has performed Lumbar Plexus blocks (LPB) to provide post-operative analgesia for total hip arthroplasty. This technique works well for the traditionally performed PLA in that the hip joint and incision site are within the analgesic distribution of the LPB. Conversely, the DAA utilizes an anterior incision that overlies the L1 and L2 dermatomes as opposed to the lower lumbar dermatomes of the PLA incision. When performing LPB it has been the study team's clinical experience that it is rare to achieve analgesia in the proximal distribution of the lumbar plexus resulting in apparent sparing of the L1 and L2 nerve root distributions. The quadratus lumborum block (QLB) is a newer regional analgesic technique that may be as effective as LPB at providing pain control following DAA hip arthroplasty. The QLB is thought to provide analgesia by blocking both the lateral and anterior cutaneous branches of T7 through L4. This degree of dermatomal coverage suggests that QLB could be an efficacious alternative to LPB for DAA hip arthroplasty. It is hypothesized that the QLB will provide equivalent analgesia when compared to the LPB as determined by a comparison of verbal reported pain scores.