Hip Joint Venting Decreases the Traction Force Required to Access the Central Compartment During Hip Arthroscopy

PURPOSE: To investigate the effect of hip joint venting on the magnitude of traction force required to arthroscopically access the central compartment of the hip. METHODS: Patients who underwent hip arthroscopy for femoroacetabular impingement syndrome prospectively underwent an intraoperative traction protocol. Joint space was measured on fluoroscopic images obtained at 50 and 100 lbs of axial traction in the prevented and vented state, and joint space values were normalized to millimetric values using preoperative anteroposterior pelvis radiographs. Venting was performed by inserting a large gauge spinal needle into the hip joint through the hip capsule and removing the stylet. Joint space differences were compared with paired t-tests, Wilcoxon signed-rank tests, and McNemar tests. RESULTS: Fifty hips in 46 patients were included. Mean joint space before venting was 7.4 ± 2.6 mm and 13.3 ± 2.8 mm at 50 and 100 lbs of traction, respectively. Mean joint space after venting was 13.9 ± 2.3 mm and 15.5 ± 2.4 mm at 50 and 100 lbs of traction, respectively. Mean differences in joint space at 50 and 100 lbs were 6.5 mm (P < .001) and 2.2 mm (P < .001), respectively. Mean joint space at 50 lbs in the vented state was significantly greater than in the pre-vented state at 100 lbs (13.9 mm vs. 13.3 mm; P = .002). The increase in joint space between 50 and 100 lbs of traction was significantly greater in the prevented state than in the vented state (5.9 mm vs 1.6 mm; P = .021). CONCLUSIONS: Venting the hip reduces the traction force necessary to arthroscopically visualize and instrument the central compartment of the hip by at least 50%. Further, residual negative pressurization of the hip joint remains after breaking the labral suction seal and venting effectively eliminates this phenomenon to aid in hip joint distraction at lower traction force. LEVEL OF EVIDENCE: Level IV, case series.