Relationship Between Tears of the Ligamentum Teres and Acetabular Undercoverage: Does Micro-Instability Play a Role?

כותרתRelationship Between Tears of the Ligamentum Teres and Acetabular Undercoverage: Does Micro-Instability Play a Role?
Publication TypeConference Paper
Year of Publication2011
AuthorsMartin DE, Botser I B, Domb BG
Conference NameInternational Society of Hip Arthroscopy (ISHA)
Date Published10/2011
Conference LocationParis, France
Abstract

Summary: This study examined the relationship between ligamentum teres tears and acetabular radiographic architecture on 360 hips. Ligamentum tears were more common in hips with lower lateral center edge angle, higher inclination, and in hips without acetabular retroversion. These results suggest that hips with lesser bony constraint may be more dependent on the ligamentum as a secondary stabilizer.

Objective:

Although the function of the ligamentum teres remains a subject of research, it is thought to play a role in stability of the hip joint. We hypothesized that hips with less inherent bony stability would be more dependent on the ligamentum as a secondary stabilizer, and would be more likely to have ligamentum tears. The purpose of this study was to examine the relationship between ligamentum teres tears and acetabular radiographic architecture.

Methods:

All patients less than 50 years old who underwent hip arthroscopy between June 2009 and February 2011 were prospectively studied. The exclusion criteria were Tonnis arthritic grade >1 and traumatic high-energy mechanisms of injury. Radiographic data were measured preoperatively on an AP pelvis view, including acetabular inclination (AI), lateral center edge angle (LCEA), magnitude of crossover sign, and ischial spine prominence. A stability index (SI) was defined as SI = [LCEA – AI]. Hips were divided into three groups: 1) high stability: SI > 38°; 2) medium stability: 16 < SI <38; and 3) low stability: SI < 16°. The presence of tears of the ligamentum teres was recorded at the time of arthroscopy.

Results:
Of the 360 hips (317 patients) included in the study, 170 (47%) had a partial or full thickness ligamentum tear. Patients with tears were significantly older than patients without tears (p<0.0001), with averages of 35.1 and 29.8 years, respectively. Radiographically, patients with tears had less acetabular retroversion, as reflected by lower ischial spine prominence values and lesser crossover signs (p=0.01 and <0.001, respectively). Intraobserver reliability coefficients were 0.91 and 0.79 for acetabular inclination and center edge angles, respectively. Using the stability index classification, 557 hips (15%) were classified as high stability, 260 (72%) as medium stability, and 45 (13%) as low stability. Low stability hips were 1.74 times more likely to have a ligamentum tear than high stability hips.

Conclusions:
A high prevalence of ligamentum teres tears was observed, likely due to inclusion of all partial thickness tears. Ligamentum tears were more common in hips with lower stability index, and in hips without retroversion. These results suggest that hips with lesser bony constraint may be more dependent on the ligamentum as a secondary stabilizer. Increased loads on the ligamentum in those hips may increase the likelihood of tears. The use of the stability index, along with the observed relationship with tears of the ligementum teres, may provide a basis for further study of the role of micro-instability in the painful hip.

This is the live presentation video from the ISHA 2011 meeting in Paris.