ePoster #305 - ISHA Annual Scientific Meeting 2016

Effect Of Capsulotomy On Hip Biomechanics: Should The Capsule Be Repaired After Hip Arthroscopy?

Suenghwan Jo, MD, PhD, Gwangju SOUTH KOREA
Alex Hooke, BA, Rochester, MN UNITED STATES
Kai-Nan An, phD, Rochester, MN UNITED STATES
Rafael J. Sierra, MD, Rochester, MN UNITED STATES
Robert Trousdale

Mayo Clinic, Rochester, MN, UNITED STATES

FDA Status Not Applicable

Summary: This study provides rationale for repairing capsule after excessive capsulotomy involving IFL or ZO is performed.

Background : An anterior capsulotomy during hip arthroscopy is routinely done to improve visualization of the joint and its structures and facilitates intra-articular work and freedom of the instrumentation. It can however, partly or completely disrupt the stabilizing ligaments of the anterior capsule. However, there is a paucity of literature on how the different arthroscopic capsulotomy procedure can influence hip stability.
Hypothesis : The range of motion and femoral head translation will increase with extent of the capsulotomy performed.
Study Design : Controlled laboratory study
Methods : Eight fresh-frozen cadaveric pelvis with no radiographic evidence of dysplasia were utilized in the study. The comparison was made among different capsule conditions utilized in hip arthroscopy with special interest in iliofemoral ligament (IFL) and zona orbicularis (ZO). The following conditions were simulated after soft tissue dissection : 1) intact capsule, 2) interportal capsulotomy, 3) T-capsulotomy, 4) IFL disruption, 5) IFL and ZO disruption. Internal rotation at 3 flexion planes (-10°, 0°, 30°), external rotation at 6 flexion planes (-10°, 0°, 30°, 60°, 90°, 110°) and corresponding femoral head translation were measured after application of 2.5 Nm torque.

Results: A significant increase in external rotation was found after interportal capsulotomy from -10° and up to 60° and after T-capsulotomy from -10° to 110° flexion as compared to an intact capsule. A significant translation was observed only with a T capsulotomy which ranged from 1.9 to 2.3mm across the flexion angles. As compare to conventional interportal capsulotomy, disruption of IFL resulted in significant increase in external rotation in all flexion angles and a significant translation accompanied if the zona orbicular was also disrupted. ZO disruption with presence of partial or complete iliofemoral ligament resection resulted in increase of both external rotation and translation.

Conclusions : Conventional capsulotomy resulted in increase of range of motion and additional transverse incision can lead to significant translation. Partial or complete tear of IFL and ZO can result in further external rotation and translation.