Relationships among hip instability, iliofemoral ligament, and pain in patients with developmental dysplasia of the hip

BACKGROUND

To evaluate the relationships among hip instability, pain, and morphology of the iliofemoral ligament (ILFL) in patients with developmental dysplasia of the hip (DDH) using ultrasonography (US).

METHODS

We reviewed 86 patients (109 hips) with DDH (Group D), 40 patients (46 hips) with borderline hip dysplasia (BDDH) (Group B) and 20 patients (23 hips) without hip pain and bony abnormality (control group). Group D was classified into three subgroups-the severe (group SP), moderate (group MP), and none/mild (group NMP) hip pain groups-using the visual analogue scale (VAS). For evaluating hip instability and ILFL morphology, the distance between the anterior edge of the anterior inferior iliac spine (AIIS) and the horizontal line to the femoral head, and ILFL thickness were measured using US. The difference between the distance in the neutral position and Patrick position was calculated and defined as the femoral head translation distance (FTD).

RESULTS

FTD and ILFL thickness in group D were significantly larger than those in the control group and group B (P < 0.05). There was a significant positive correlation between FTD and ILFL thickness in three groups (r = 0.57, P < 0.05; r = 0.55, P < 0.05; r = 0.62, P < 0.05, respectively). FTD and ILFL thickness in group SP were significantly larger than those in group NMP (P < 0.05). FTD and ILFL thickness in group D had significantly negative correlations with the lateral center edge (r = -0.54, P < 0.05; r = -0.40, P < 0.05, respectively) and vertical-center-anterior angle (r = -0.51, P < 0.05; r = -0.43, P < 0.05, respectively).

CONCLUSIONS

Acetabular bony deficiency, especially in the anterior and lateral region can result in antero-posterior hip instability, leading to thickened ILFL and hip pain, even in patients with BDDH. These findings may facilitate our understanding and treatment of patients with DDH. When hip instability is suspected, hip US examination may help confirm the diagnosis and assist in providing objective clinical diagnostic evidence.

The anterior hip capsule is thinner in dysplastic hips: a study comparing different young adult hip patients

PURPOSE

To investigate the thickness and intra-substance change of anterior capsule of the hip joint, and compare the difference of the capsular features in patients with different statuses of hip stability.

METHODS

A retrospective study was performed to review a hip preservation database. Using the lateral center edge angle(LCEA), patients with borderline dysplasia of the hip (BDH) of 20° ≤ LCEA ≤ 25°, femoracetabular impingement(FAI) with LCEA > 30° and dysplasia of the hip (DH) of LCEA < 20° were enrolled and stratified into different treatment groups. The patients' imaging was reviewed by two experienced musculoskeletal radiologists who were blinded to clinical outcomes. Thickness and intra-substance change of the anterior hip capsule was measured on the sagittal oblique sequences of MRI. A surgeon measured the thickness of the anterior hip capsule during arthroscopy. The capsular thickness and intra-substance change were compared among different groups.

RESULTS

Thirty patients (17 women and 13 men) enrolled in each group (FAI, BDH, and DH) matched by sex and ages were evaluated. There were no significant differences in terms of age, sex, BMI, Alpha angle, and Tönnis grade among all three groups. The mean thickness of the anterior capsule in the DH group was 3.2 ± 0.5 mm, which was significantly thinner than that in the BDH and FAI groups (4.5 ± 0.8 mm and 4.7 ± 0.6 mm), and there was no significant difference in capsular thickness between the BDH and FAI groups. The Median of anterior capsule thickness via arthroscopic measuring was 6 mm and 7 mm in the BDH and FAI groups respectively, which has no statistical difference. The intra-substance change of the anterior capsule shows a significant difference among the three groups, and a higher incidence of delamination of the capsule was found in DH groups (p < 0.001).

CONCLUSIONS

Patients with hip dysplasia have a significantly reduced capsular thickness on MRI and delaminated anterior joint capsule, which could be a sequence of instability. The clinical relevance of this study is that capsular thickness and intra-substance changes of the anterior capsule vary which could alter capsular management strategies.

LEVEL OF EVIDENCE

Level III of evidence, DIAGNOSTIC STUDIES, No consistently applied reference standard.

Clinical anatomy of the musculoskeletal system in the hip region

Although the hip joint is regarded as inherently stable, hip pain and injuries caused by traumatic/non-traumatic hip instability are relatively common in active individuals. A comprehensive understanding of hip anatomy may provide better insight into the relationships between hip stability and clinical problems. In this review, we present our recent findings on the hip morphological characteristics, especially focusing on the intramuscular tendon of the gluteus medius tendon and its insertion sites, hip capsular attachment on the anterosuperior region of the acetabular margin, and composition of the iliofemoral ligament. We further discussed the hip stabilization mechanism based on these findings. The characteristics of the gluteus medius tendon suggest that even a single muscle has multiple functional subunits within the muscle. In addition, the characteristics of the hip capsular attachment suggest that the width of the capsular attachment is wider than previously reported, and its wide area shows adaptive morphology to mechanical stress, such as bony impression and distribution of the fibrocartilage. The composition of the iliofemoral ligament and its relation to periarticular structures suggest that some ligaments should be defined based on the pericapsular structures, such as the joint capsule, tendon, and aponeurosis, and also have the ability to dynamically coordinate joint stability. These anatomical perspectives provide a better understanding of the hip stabilization mechanism, and a biomechanical study or an in vivo imaging study, considering these perspectives, is expected in the future.

Anatomic evaluation of the insertional footprints of the iliofemoral and ischiofemoral ligaments: a cadaveric study

Background

An understanding of the insertional footprints of the capsular ligaments of the hip is important for preserving hip function and stability given the increasing number of minimally invasive hip surgeries being performed under a limited surgical view. However, it is difficult to detect these ligaments intraoperatively and many surgeons may not fully appreciate their complex anatomy. The aims of this study were to quantify the proximal and distal footprints of the iliofemoral ligament (ILFL) and ischiofemoral ligament (ISFL) and to estimate the location of the corresponding osseous landmarks on the proximal femur, which can be detected easily during surgery.

Methods

Twelve hip joints from Japanese fresh frozen cadavers were used. All muscle, fascia, nerve tissue, and vessels were removed to expose the intact capsular ligaments of the hip. The length and width of the proximal and distal footprints of the ILFL and ISFL were measured and their relationship to osseous structures was evaluated, including the intertrochanteric line, femoral neck, and lesser trochanter.

Results

The mean length of the distal medial arm of the ILFL footprint was 17.9 mm and the mean width was 9.0 mm. The mean length of the distal lateral arm of the ILFL footprint was 23.0 mm and the mean width was 9.7 mm. For the footprint of the medial arm, the insertion was in the distal third of the intertrochanteric line and that of the lateral arm was in the proximal 42% of this line. The mean distance from the lesser trochanter to the footprint of the medial arm was 24.6 mm. The mean length of the distal ISFL footprint was 11.3 mm and the mean width was 6.9 mm. The footprint of the distal ISFL was located forward of the femoral neck axis in all specimens.

Conclusions

Understanding the size and location of each capsular ligament footprint in relation to an osseous landmark may help surgeons to manage the hip capsule intraoperatively even under a narrow surgical view. The findings of this study underscore the importance of recognizing that the distal ISFL footprint is located relatively forward and very close to the distal lateral arm footprint.

New classification focusing on the relationship between the attachment of the iliofemoral ligament and the course of the fracture line for intertrochanteric fractures

PURPOSE

There are various types of intertrochanteric fractures that are unstable pertrochanteric fractures of the hip. The aim of this study was to develop a systematic and comprehensive classification of intertrochanteric fractures.

MATERIALS AND METHODS

This study enrolled 74 patients with intertrochanteric fractures treated by us between 2012 and 2015. The fractures were classified using 3D-CT images taken immediately after the fractures occurred based on the course of the lateral fracture line (LFL) that extends through the lateral femoral cortex distal to the vastus ridge of the greater trochanter in the intertrochanteric area. Furthermore, the presence or absence of additional typical fractures was also studied. Then, 4 orthopedic specialists examined the 3D-CT images of 20 patients randomly selected from the 74 patients to evaluate both the inter-rater and intra-rater agreement levels.

RESULTS

Intertrochanteric fractures were classified into three types according to the LFL patterns. Type I (41.9%), the Lateral Wall Pattern, has a LFL that extends towards the lateral fiber bundle attachment area of the iliofemoral ligament. Type II (24.3%), the Transverse Pattern, has a LFL that extends towards the medial bundle attachment area. Type III (33.8%), the Reverse Oblique Pattern, has a LFL that extends between the lateral and medial fiber bundle area of the iliofemoral ligament. Each type showed characteristic displacement and was associated with various combinations of typical fractures (fracture across the intertrochanteric line, posteromedial fragment, including the lesser trochanter, posterolateral fragment posterior to the femoral greater trochanter, and banana-shaped big fragment, including both the greater trochanter and the lesser trochanter). The mean κ values for the interobserver and intraobserver agreement levels were 0.77 (0.70-0.85) and 0.76 (0.70-0.85), respectively, which were considered substantial agreement levels.

CONCLUSION

We believe our new classification is a useful communication tool for medical professionals in the diagnosis of fractures.

Capsular Management in Hip Arthroscopy

The hip capsule is a highly complex anatomic structure, which influences normal hip motion and biomechanics. A dynamic stabilizing capsular contribution exists in the iliocapsularis and gluteus minimus, among other musculotendinous structures crossing the joint. Variable types and sizes of capsulotomy are necessary to sufficiently visualize and address the bony and soft tissue pathologic source of symptoms. Unrepaired capsulotomies may leave the hip significantly unstable to variable degrees. Capsular closure is a necessary part of a comprehensive arthroscopic hip preservation procedure. Greater titration of the degree of plication may be performed for patients with risk factors for postoperative instability.