OBJECTIVETo investigate the method and result of arthroscopic trans-septal approach (ATS).

METHODSTen fresh cadaveric knees were prepared for anatomical study about the posterior septum, and 65 posterior compartment arthroscopy of the knees were performed to view the structure of the posterior septum. The initial diagnosis included: rheumatoid arthritis, pigmented villonodular synovitis, osteoarthritis, loose body or foreign body in the posterior compartment, posterior cruciate ligament (PCL) injury or avulsion fracture, posterior horn tear of meniscus, undiagnosed swollen knee with pain and effusion, osteochondritis dissecans, pyogenic arthritis, gout. From January 2002 to June 2005, 22 cases of ATS were applied. Anterolateral portal was initially created, followed by posterolateral portal under the viewing of arthroscopy which was located at the anterolateral portal. Anteromedial and posteromedial portals were also created using the same technique. Arthroscopy was then transferred to the posteromedial portal, and blade was introduced from the anteromedial portal to gradually remove the synovium covering PCL. Arthroscopy was relocated to the anteromedial portal, Wissinger rod was introduced from the posteromedial portal and pointed to the posterior septum adjacent to the posterior edge of the midportion of PCL. The Wissinger rod was pushed carefully to pierce through the posterior septum under the sight of arthroscopy which was located at the posterolateral portal. ATS was finally created.

RESULTSThe posterior septum was in the middle of posterior compartment of the knee, which was film screen-like at the sagittal plane and sandwich-like at the transverse plane. The synovium covered the posterior septum at arthroscopic inspection. Twenty-two cases of ATS were successfully created, amounting to 34% (22/65) of all cases at the same period which had received the arthroscopy of posterior compartments of the knees. Synovectomy of the posterior compartments of the knees was performed in 7 cases, loose body removal was in 6 cases, PCL reconstruction was in 4 cases, reduction and fixation of PCL avulsion fracture was in 2 cases. Chondroplasty, inflammatory synovectomy, and meniscectomy were performed accordingly in 6 osteoarthritis cases. No vascular or nervous injury was encountered. At an average of 20 months follow-up (range, 4 to 45 months), 9 cases still had mild knee pain or swelling, 2 cases had severe pain and were recommended for total knee replacement, the other 11 cases had no recurrence of knee pain or swelling.

CONCLUSIONSATS has no blind area under arthroscopic vision and facilitate trans-septal operation. It is a safe and effective method to treat the diseases of the posterior compartment of the knee. The direction of inside to outside to create ATS is comparatively reliable, and PCL could be identified as an interior landmark during the passage of Wissinger rod through posterior septum to create ATS.