Paper #71 - ISHA Annual Scientific Meeting 2016

A Prospective Study Exploring the Relationship Between Hip Capsular Thickness and Joint Hypermobility: Forewarned is Forearmed

Brian Devitt, MD, FRCS, Melbourne, Victoria AUSTRALIA

Hip Arthroscopy Australia, Melbourne, Victoria, AUSTRALIA

FDA Status Not Applicable

Summary: This study revealed a direct relationship between joint hypermobility and capsular thickness, which has important clinical implications in terms of planning capsular management based on a simple preoperative examination.

Introduction & aims
Hip microinstability is increasingly being recognized as a potential cause of pain and disability. The pathomechanism is not clearly defined but is thought to involve anatomical abnormalities, repetitive forces across the hip and, importantly, ligamentous laxity. The aim of this study was to explore the relationship between joint hypermobility and hip capsular thickness measured intra-operatively.

A prospective study was performed on 100 consecutive patients undergoing a primary hip arthroscopy for the treatment of hip pain. A Beighton test score (BTS) was performed prior to each procedure - The maximum score was 9, and a score of 4 or greater was defined as hypermobility. At surgery, the capsular thickness at the level of the anterior portal, corresponding to the location of the iliofemoral ligament, was measured using a calibrated arthroscopic probe. The surgical findings and intervention carried out was recorded. The centre edge angle (CEA) was recorded on AP radiographs in all cases.

52 females and 48 males were included in the study. The average age was 26 years (range: 18 – 40 years). There were 51 right and 49 left hips. Measurement of the hip capsule ranged from 2.5 mm to 17.5 mm. The average hip capsule thickness was statistically greater in men than women, 10 mm and 7.5 mm respectively (P= 0.03). The average BTS for men and women were 1 and 4 respectively – elbow and knee hyperextension were most commonly identified in women. A statistically significant correlation was found between a BTS = 4 and a capsular thickness of < 7.5 mm. The most common condition identified in patients with a BTS of = 4 was a partial tear of the ligamentum teres. No relationship was found between the CEA and the BTS or the capsular thickness.

The main finding of this study was that the measurement of joint hypermobility correlated closely with hip capsule thickness. A BTS of = 4 was associated with a capsular thickness of < 7.5 mm. The clinical implications of this relate to the capsular management options one may choose based on a simple preoperative examination.