A new regional anaesthesia approach may help dogs recover more quickly after tibial plateau levelling osteotomy (TPLO) by providing effective pain control while preserving motor function, according to a small case series describing a technique called the Flags Assisted WalKing block for Enhanced recovery after Surgery (FAWKES).
TPLO is one of the most commonly performed orthopaedic procedures in dogs with cranial cruciate ligament rupture. Peripheral nerve blocks, such as the saphenous–sciatic combination, are often used to provide perioperative analgesia. However, these techniques can cause temporary muscle weakness that may delay postoperative mobility.
The FAWKES technique aims to provide analgesia without significant motor blockade, potentially supporting earlier ambulation and smoother recovery.
The study
The report describes three dogs undergoing TPLO surgery: a 2.5-year-old Pit Bull terrier (42.6 kg), a 10-year-old French bulldog (13.4 kg), and an 8-year-old mixed-breed dog (32.6 kg). All were diagnosed with cranial cruciate ligament rupture and classified as American Society of Anesthesiologists (ASA) physical status II.
Each dog received general anaesthesia alongside a multimodal regional anaesthesia protocol consisting of three components:
- the FLAGS (inFiLtrating Around Genicular Structures) block
- a saphenous nerve block
- periarticular knee infiltration
Together, these techniques formed the FAWKES block.
The regional injections used a mixture containing ropivacaine, dexmedetomidine, dexamethasone sodium phosphate and epinephrine. Ultrasound guidance was used to target structures around the femur and proximal tibia, with six injections performed per patient.
The results
Across all three procedures, physiological parameters remained stable during surgery, with no sustained increases in heart rate, respiratory rate or mean arterial pressure greater than 20% above baseline.
Postoperative pain was assessed using the Glasgow Composite Measure Pain Scale–Short Form (CMPS-SF). One hour after surgery, all dogs had pain scores of 1/24.
Early mobility was also observed:
- Two dogs were able to ambulate on the operated limb within one hour of recovery.
- The third dog did not bear weight immediately but retained motor function, including the ability to flex the stifle and lift the limb.
Only one dog required postoperative rescue analgesia, receiving a single intravenous dose of methadone 12 hours after surgery. All dogs resumed eating within 12 hours and were discharged the following day without complications.
The bottom line
This early case series suggests the FAWKES block may provide effective perioperative analgesia for TPLO while preserving motor function, potentially supporting earlier postoperative mobility.
However, controlled clinical trials and further anatomical work are needed before the technique can be widely recommended. The authors emphasise that the findings are preliminary. The case series included only three dogs and lacked a control group.
In addition, the cumulative dose of ropivacaine used exceeded commonly cited doses for locoregional techniques. Although no adverse effects were observed, the authors note that combining this with systemic lidocaine could increase the risk of local anaesthetic toxicity.
