The human arthritic hip joint is a source of mesenchymal stromal cells (MSCs) with extensive multipotent differentiation potential.

BACKGROUND: While multiple in vitro studies examined mesenchymal stromal cells (MSCs) derived from bone marrow or hyaline cartilage, there is little to no data about the presence of MSCs in the joint capsule or the ligamentum capitis femoris (LCF) of the hip joint. Therefore, this in vitro study examined the presence and differentiation potential of MSCs isolated from the bone marrow, arthritic hyaline cartilage, the LCF and full-thickness samples of the anterior joint capsule of the hip joint. METHODS: MSCs were isolated and multiplied in adherent monolayer cell cultures. Osteogenesis and adipogenesis were induced in monolayer cell cultures for 21 days using a differentiation medium containing specific growth factors, while chondrogenesis in the presence of TGF-ß1 was performed using pellet-culture for 27 days. Control cultures were maintained for comparison over the same duration of time. The differentiation process was analyzed using histological and immunohistochemical stainings as well as semiquantitative RT-PCR for measuring the mean expression levels of tissue-specific genes. RESULTS: This in vitro research showed that the isolated cells from all four donor tissues grew plastic-adherent and showed similar adipogenic and osteogenic differentiation capacity as proven by the histological detection of lipid droplets or deposits of extracellular calcium and collagen type I. After 27 days of chondrogenesis proteoglycans accumulated in the differentiated MSC-pellets from all donor tissues. Immunohistochemical staining revealed vast amounts of collagen type II in all differentiated MSC-pellets, except for those from the LCF. Interestingly, all differentiated MSCs still showed a clear increase in mean expression of adipogenic, osteogenic and chondrogenic marker genes. In addition, the examination of an exemplary selected donor sample revealed that cells from all four donor tissues were clearly positive for the surface markers CD44, CD73, CD90 and CD105 by flow cytometric analysis. CONCLUSIONS: This study proved the presence of MSC-like cells in all four examined donor tissues of the hip joint. No significant differences were observed during osteogenic or adipogenic differentiation depending on the source of MSCs used. Further research is necessary to fully determine the tripotent differentiation potential of cells isolated from the LCF and capsule tissue of the hip joint.

Ligamentum Teres Impingement in Valgus Impacted Femoral Neck Fracture: A Case for Hip Arthroscopy.

CASE: Seven years after hip arthroscopy for cam impingement, a 47-year-old female patient suffered a valgus impacted femoral neck fracture of her left hip that was stabilized with cannulated screws. After fracture healing, she experienced persisting sharp groin pain that could be elicited in flexion/internal rotation and extension/adduction. We suspected a ligamentum teres impingement at the border of the acetabular fossa due to a post-traumatic fovea alta and performed an arthroscopic ligament resection. Symptoms completely resolved thereafter. CONCLUSION: Valgus impacted femoral neck fractures with post-traumatic fovea alta may cause painful ligamentum teres impingement that can be treated with arthroscopic resection.

Neurovascular structures of the ligament of the head of femur.

The ligament of the head of femur (LHF), or ligamentum teres, is believed to provide blood supply to the head of femur and mechanical stability to the hip joint. But these functions in the adult are often debated. The existence and distribution of neurovascular structures within the ligament are not widely documented. This study examined the blood vessels and nervous tissue within the LHF to determine whether the ligament may have a vascular and proprioceptive function at the hip joint. Histological sections from the LHF from 10 embalmed hips (six female, four male; mean age 80.4 ± 8.7 years) were cut at three levels: the foveal attachment, mid-length and its base where it attaches to the transverse acetabular ligament. Sections were stained with haematoxylin and eosin to study general tissue architecture or with von Willebrand factor and neurofilament to identify blood vessels and nervous tissue, respectively. The proportion of the ligament's cross-sectional area occupied by blood vessels was expressed as a vascularity index (VI). Nerve endings within the ligament were identified and morphologically classified. Comparisons between the VI at the three levels, or between the tissue layers of the ligament, were made using 95% confidence intervals; statistical significance was set P < 0.05. The ligament tissue comprised three distinct layers: a synovial lining with cuboidal cells, a sub-synovial zone formed of loose connective tissue and the ligament proper composed of dense collagen bundles. Patent blood vessels and nerve fibres were present both in the sub-synovial zone and the ligament proper; Pacinian corpuscles and free nerve endings were found scattered only in the sub-synovial zone. The VI of the ligament proper at the fovea was significantly higher than its middle (P = 0.01) and basal levels (P = 0.04); it was also higher than that of the sub-synovial layer (P = 0.04). The LHF has three histologically distinct zones, and blood vessels and nerves are distributed both in the sub-synovial layer and ligament proper. Higher vascularity within the ligament proper at its foveal insertion suggests a possible nutritive role of the LHF to the adult head of femur. The presence of nerves and nerve receptors indicates the ligament is involved in the perception of pain and proprioception, thereby contributing to mechanical stability of the joint.

Clinical Anatomy of the Ligament of the Head of Femur.

The ligament of the head of femur (LHF) has gained clinical attention recently and is reported to contribute to hip stability. This study explores its morphology and morphometry, information that may help inform surgical decision making. Gross anatomical dissections were undertaken on 229 embalmed hips from European (n = 105) and Thai (n = 124) adult cadavers to examine LHF anatomy. Ligament morphometry was statistically compared at different sites, between sexes and sides. The origin of ligamental arteries and absence of the ligament were documented. The LHF was pyramidal or quadrangular in shape. Sub-synovial fibrous bands originated from the transverse acetabular ligament, edges of the acetabular notch, and acetabular floor; less frequently from the hip joint capsule. Distally, the ligament flattened and converged onto the fovea capitis. The ligament was 22.3 ± 4.4 mm long and was significantly wider (P = 0.001) and thicker (P = 0.0003) at the fovea, compared to its mid-zone. Branches of the obturator artery entered the acetabular foramen inferomedially and penetrated the middle third of the LHF. Blood vessels ran within the LHF and appeared to enter the fovea. The ligament was absent in 2.8% of Thai hips and there were no significant sex or side differences in ligament dimensions. The morphology of the LHF is complex. While individual variation was apparent, blood vessels were seen in the distal ligament. Precise information on LHF morphometry and attachment sites will help inform appropriate graft dimensions and choice of fixation sites necessary for ligament reconstruction. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc. Clin. Anat., 2018. © 2018 Wiley Periodicals, Inc.

The ligamentum teres femoris in orangutans.

OBJECTIVES: It is widely viewed that orangutans lack a ligamentum teres femoris (LTF) inserting on the femoral head because orangutans lack a distinct fovea capitis. Orangutans employ acrobatic quadrumanous clambering that requires a high level of hip joint mobility, and the absence of an LTF is believed to be an adaptation to increase hip mobility. However, there are conflicting reports in the literature about whether there may be a different LTF configuration in orangutans, perhaps with a ligament inserting on the femoral neck instead. Here we perform a dissection-based study of orangutan hip joints, assess the soft tissue and hard tissue correlates of the orangutan LTF, and histologically examination the LTF to evaluate whether it is homologous to that found in other hominoids. MATERIALS AND METHODS: The hip joints from six orangutans were dissected. In the two orangutans with an LTF passing to the femoral head, the LTF was assessed histologically. Skeletonized femora (n=56) in osteological repositories were examined for evidence of a foveal pit. RESULTS: We observed an LTF in two of the three infant orangutans but not in the sub-adult or adult specimens. Histological examination of the infant LTF shows a distinct artery coursing through the LTF to the head of the femur. One percent of orangutan femora present with a foveal scar, but no pit, on the femoral head. DISCUSSION: Despite being absent in adults, the LTF is present in at least some orangutans during infancy. We suggest that the LTF maintains a role in blood supply to the femoral head early in life. Because the LTF can limit hip mobility, this may explain why the LTF may be lost as an orangutan ages and gains locomotor independence. These findings enhance our understanding of orangutan hip morphology and underscore the need for future soft tissue investigations.

Use of MR arthrography in detecting tears of the ligamentum teres with arthroscopic correlation.

OBJECTIVE: To demonstrate the normal appearance of the ligamentum teres on MR arthrography (MRA) and evaluate the accuracy of MRA in detecting ligamentum teres tears with arthroscopic correlation. MATERIALS AND METHODS: Institutional Review Board approval was obtained with a waiver for informed consent because of the retrospective study design. A total of 165 cases in 159 patients (111 females, 48 males; mean age 41 ± 12 years) who underwent both MRA and hip arthroscopy were evaluated for appearance of the ligamentum teres, including the size, number of bundles, and ligamentum teres tears. Marrow edema of the fovea capitis adjacent to the ligamentum teres insertion and the presence of hip plicae were also recorded. RESULTS: The mean thickness and length of the ligamentum teres were 3.5 ± 1.5 mm and 25.2 ± 3.8 mm, respectively. Sensitivity, specificity, positive and negative predictive value, and accuracy of MRA for the detection of ligamentum teres tears were 78, 97, 74, 97, and 95%, respectively. CONCLUSION: MRA is an accurate method to evaluate the normal morphology and to detect tears of the ligamentum teres.

Histological and molecular characterization of the femoral attachment of the human ligamentum capitis femoris.

The ligamentum capitis femoris (LCF) has increased in clinical significance through the development of hip arthroscopy. The histological pathologies and molecular composition of the femoral attachment of the LCF and the degeneration caused by LCF disruption were investigated in the human hip joint. Twenty-four LCFs were retrieved at surgery for femoral neck fracture (age range: 63-87 years). In the "intact" (i.e., intact throughout its length, n = 12) group, the attachment consisted of rich fibrocartilage. Fibrocartilage cells were present in the midsubstance. In contrast, the construction of the attachment in the "disrupted" (i.e., ligament no longer attached to the femoral head, n = 12) group had disappeared. The attachment in the disrupted group was not labeled for type II collagen or aggrecan, while that in the intact group was labeled for types I, II and III collagen, chondroitin 4-sulfate, chondroitin 6-sulfate, aggrecan, and versican. The percentage of single-stranded DNA-positive chondrocytes was significantly higher in the disrupted group than in the intact group. We conclude that the femoral attachment of the LCF has a characteristic fibrocartilaginous structure that is likely to adjust to the mechanical load, and suggest that its degeneration is advanced by disruption and should be regarded as a clinical pathology.

The ligamentum capitis femoris: anatomic, magnetic resonance and computed tomography study.

The objective of the study was to describe the normal anatomy of the ligamentum capitis femoris and to determine the neurovascular structures potentially at risk during its reconstruction. Ten cadaveric specimens of the ligamentum capitis femoris (LCF) were dissected and photographed. Magnetic resonance (MR) and Computed tomography (CT) arthrography evaluation of the anatomy of the LCF in 30 hips were performed to measure length of the ligament and to study the proximity of neurovascular structures. The anatomical study showed that the LCF has a pyramidal structure and a banded appearance. The thickness of the medial wall of the acetabulum 3 mm superior to the inferior acetabular boundary was found to be 6.7 mm (4-9 mm) at point 1 (anterior), 4.1 mm (3-7 mm) at point 2 (central), and 6.5 mm (4-9 mm) at point 3 (posterior). Central anchors or screws were found to lie within 1.7 cm (1.6-1.9 cm) of the external iliac vein and artery. Angulation of anchors in the anterior and posterior columns in the axial plane with respect to acetabular fossa floor (the Optimal Angulation Angle or OAA), is safer (0 to 45º the safest optimal angles). The sagittal angulation created by the safe pathway in the anterior and posterior columns with respect to the plane of the facies lunata in this area was also measured and termed the Optimal Angle of Penetration (OAP) with normal values being: 110º (102-123º) for the posterior column and 90º (85-94º) for the anterior column. Our results suggest that reconstruction of the LCF can be safely performed if these guidelines are followed.