Clinical outcomes and complications of the indirect modified arthroscopic posterior transseptal approach at a minimum 2-year follow-up

BACKGROUND: The arthroscopic posterior transseptal approach (TSA) allows improved visualization of the posterior compartment of the knee joint. However, it can be associated with increased risks particularly regarding potential injury to the neurovascular bundle or postoperative scarring, which may contribute to extension deficits of the knee joint. We hypothesized that the modified TSA does not increase the risk of postoperative extension deficit or neurovascular complications while providing safe access to the posterior compartment. METHODS: This retrospective cohort study analyzed prospectively collected data from patients who underwent arthroscopic knee surgery via TSA between 01/2018 and 02/2024. The primary outcome measure was the occurrence of perioperative complications. The secondary outcome measures were postoperative complications, postoperative range of motion compared with the contralateral (control) knee, and functional outcomes measured by the subjective International Knee Documentation Committee (IKDC) score and Tegner score. RESULTS: A total of 82 patients were eligible for the study. No perioperative complications were observed. 48 patients (10 females, 38 males; mean age, 37.8 ± 13.5 years) completed follow-up and were available for secondary outcome analysis at a mean follow-up of 45.9 ± 20.7 months. Indications for the TSA included posterior and/or posterolateral knee instability (n = 36), chronic knee dislocation (n = 8), posterior compartment synovectomy for tenosynovial giant cell tumors (n = 2), posterior meniscal pathology (n = 3), and posterior cruciate ligament cysts (n = 2). Patient-reported outcomes were good (IKDC 77.9 ± 17.4; Tegner 4.5 ± 1.7). There were no relevant side-to-side (SSD) differences in knee extension (mean SSD = 0.39, p = 0.098). CONCLUSIONS: The indirect posterior transseptal approach is a safe arthroscopic technique that can be associated with moderate clinical outcomes depending on the underlying pathology. The modified TSA appears to be safe when performed by experienced surgeons and was not associated with neurovascular complications in this cohort.