To investigate temporal changes in synovial lymphatic system (SLS) drainage function after Anterior cruciate ligament (ACL) injury, a non-invasive ACL rupture model was used to induce the PTOA phenotype without altering the SLS structure. We have created a non-invasive ACL rupture model in the right knee (single overload impact) of 12- week-old C57bl/6 male mice to mimic the ACL rupture-induced PTOA development. 70 kDa-TxRedDextran were injected into the right knee of the mice at 0, 1, 2, and 4 wks post modeling (n=5/group), and the fluorescence signal distribution and intensity were measured by the IVIS system at 1 and 6 hrs post-injection. After 24 hrs, the drainage lymph nodes and whole knee joint were harvested and subjected to ex vivo IVIS imaging and immunofluorescence detection respectively. Manual ACL rupture was induced by 12N overloaded force and validated by a front drawer test. Intraarticular clearance of TxRed-Dextran detected by the IVIS was significantly reduced at 1, and 2 wks at a level of 43% and 55% respectively but was not significantly different from baseline levels at 4 wks (89%). TxRed-Dextran signal in draining lymph nodes was significantly reduced at 1 week at the level of but not for 2 and 4 wks compared to baseline levels (week 1–29%, week 2–50%, week 4–94%). TxRed-Dextran particle was significantly enriched in the synovium at 1, 2 wks but was not significantly different from baseline levels at 4 wks rupture-post ACL rupture (Particle numbers: Sham Ctrl-34 ±14, week 1, 113 ± 17; week 2, 89 ± 13; week 4, 46 ± 18; mean ± SD). We observed the drainage function of SLS significantly decreased at 1 and 2 wks after the ACL rupture, and was slowly restored at 4 wks post-injury in a non-invasive ACL rupture model. Early impairment of SLS drainage function may lead to accumulation of inflammatory factors and promote PTOA progression.
Injuries to the infra-patella branch of the saphenous nerve on harvesting Bone-Patella Tendon-Bone (BPB) autograft commonly cause anterior knee pain. The purpose of this study is to investigate the possibility of harvesting a good BPB graft without injury to the nerve by using double mini-incision. Twelve adult cadaveric knees, with two vertical incisions of 25mm, one over the inferior pole of the patella, and the other over the tibial tuberosity were prepared. The tibial bone block was harvested, with preservation of the para-tendon, making a subcutaneous tunnel proximally and stripped to dissect the middle 1/3 of the patella tendon. The graft was then detached after harvesting the patella bone block, and examined for size and quality. The knees were finally dissected to check the relationship of the incisions with the infra-patella branch, and see if it was injured. All BPB grafts were found to have good tendon qualities of average 9.5mm in width. The tibial bone plug is of average 25mm in length and 10mm in width, while the patella bone plug is of average 22mm in length & 9mm in width. All 12 knees have 2 infra-patella branches, with the proximal branch running at averaged distance of 23mm distal to the proximal incision, while the distal branch lying at averaged distance of 11mm proximal to the distal incision. 2 out of the 12 distal branches were injured by the distal incision. Double-mini incision allows harvesting of a consistently good quality BPB graft with preservation of the infra-patella branch of the saphenous nerve.
