Flexor Digitorum Longus Tendon Repair in Mice

At 10–12 weeks of age mice underwent complete transection and repair of the flexor digitorum longus (FDL) tendon in the right hind-paw as previously described^{39 (link), 45 (link)}. Briefly, mice were anesthetized with Ketamine (60 mg/kg) and Xylazine (4 mg/kg). A pre-surgical dose of Buprenorphine (0.05 mg/kg) was administered followed by further analgesia every 12-hours after surgery as needed. Following preparation of the surgical site, the FDL was surgically transected in the transverse plane at the myotendinous junction in the calf to protect the repair site from high strains. The skin was closed with a single 5-0 suture. A 1-2 cm incision was then made on the posterior surface of the hindpaw, soft tissue was retracted to identify the FDL, and the FDL was completely transected using micro-scissors. Following transection the FDL was repaired using 8-0 nylon sutures (Ethicon, Somerville, NJ) in a modified Kessler pattern. The skin was closed with 5-0 suture. The animals were allowed unrestricted weight-bearing and movement, and had ad-libitum access to food and water.