The effects of venting and capsulotomy on traction force and hip distraction in hip arthroscopy

Abstract

This study evaluated the effects of venting and capsulotomy on the ratio of normalized distraction distance to traction force, correlating this trend with patient demographic factors. A ratio was chosen to capture the total effect of each intervention on the hip joint. During primary hip arthroscopy, continuous traction force was recorded, and fluoroscopic images were acquired to measure joint distraction before and after the application of traction, venting and interportal capsulotomy. Distraction–traction force ratios were compared using a one-sided paired t-test. A linear regression model was used to determine the relationship between age, sex and body mass index and pre- and post-intervention distraction–traction force ratios. Seventy-two adult patients and 73 hips were included. There was an increase in hip distraction with a decrease in traction force post-venting and capsulotomy (both P’s <0.001). Mean normalized distraction distance increased 1.5% of femoral head size after venting and an additional 2.2% of femoral head size after capsulotomy. Mean traction force decreased 2.2% (14.7 N) after venting and 2.3% (15.3 N) after capsulotomy. Female sex significantly correlated with larger differences in both pre- and post-venting capsulotomy ratios. Venting and capsulotomy both independently improve the ratio of normalized distraction distance to traction force when performed in vivo. However, the effect sizes of each intervention are small and of questionable clinical significance. Specifically, when adequate distraction for safe surgical hip access cannot be obtained despite application of significant traction force, venting and capsulotomy after the application of traction may not afford substantial improvement.

Distraction Gap Needed for Safe Central Compartment Access in Hip Arthroscopy

“…Several in vivo and cadaveric studies have shown that distension of the joint with air or fluid led to a breakage of the vacuum seal between the head and socket, resulting in subsequent improvement of distraction and reduction of the traction force. 3,5,16,17 Byrd et al 3 demonstrated that the distance between the superior weightbearing portion of the acetabulum and the corresponding femoral head (similar to the lateral gap in the current study) significantly increased by a mean of 22% via the addition of fluid distension to pure traction. Dienst et al 5 showed that the distraction distance of the lateral gap after a combination of air distension and traction was 1.45 to 3.07 times greater than that after traction alone in a cadaveric study.…”

“…Another cause leading to the increase of distraction between the preoperative unsterile traction test and the end of arthroscopy is likely the physiologic creep of the soft tissues. This was confirmed by O'Neill et al, 16 who showed that distraction increased over time after application of traction. These findings provide some useful information for hip arthroscopy.…”

“…Joint distension with intra-articular injection of saline or air to break the hip fluid seal can significantly improve the distraction and decrease the traction force. 3,5,16,17 The CC-first technique may be the most popular access technique in hip arthroscopy. The main concern for this technique is the potential risk of iatrogenic damage to the labrum or cartilage during the first portal placement.…”

“…Joint distension with intra-articular injection of saline or air to break the hip fluid seal can significantly improve the distraction and decrease the traction force. 3,5,16,17…”

Editorial Commentary: Hip Primary Labral Repair Versus Reconstruction: Equally Successful Outcomes Can Be Achieved Based on Proper Indications

“…We must translate the bench to the bedside. Surgeons are finally starting to do this: O'Neill et al, 7,8 in 2 separate publications using a proprietary postless hip distraction system, have not only measured the strength of the seal, they have also provided recommendations for decreasing force of distraction. Personally, in my prospective database, I quantitatively measure and record several aspects of the seal and its breakage: after an air arthrogram, the force (Newtons; pounds of force) required to sufficiently distract the hip; the degrees of Trendelenburg of the bed; and the amount of femoral head distraction (millimeters).…”