Adaptations of ligamentum teres in ischemic necrosis of human femoral head

How Strong Is the Ligamentum Teres of the Hip? A Biomechanical Analysis

BACKGROUND

Intraarticular hip pain represents a substantial clinical challenge, with recent studies implicating lesions in the ligamentum teres as potential contributors. Even more so, damage to the ligamentum teres is particularly prevalent among young patients undergoing joint-preserving interventions. Although several studies have investigated the biomechanical attributes of the ligamentum teres, inconsistencies in reported findings and reliance on cadaveric or animal models have raised concerns regarding the extrapolation of results to clinical practice. Furthermore, there is a lack of research examining ligamentum teres biomechanics specifically within the relevant patient cohort-individuals who benefit from joint-preserving surgical interventions.

QUESTIONS/PURPOSES

We sought (1) to determine the biomechanical properties (ultimate load to failure, tensile strength, stiffness, and elastic modulus) of fresh-frozen ligaments from patients undergoing surgical hip dislocation, and (2) to identify patient-specific factors that are associated with them.

METHODS

This was an institutional review board-approved study on intraoperatively harvested ligamentum teres from 74 consecutive patients undergoing surgical hip dislocation for joint preservation (August 2021 to September 2022). After the exclusion of patients with previous surgery, posttraumatic deformities, avascular necrosis, slipped capital femoral epiphysis, and Perthes disease, 31 ligaments from 31 patients were analyzed. The mean age of the study group was 27 ± 8 years, and 61% (19) of participants were male. The main indication for surgery was femoroacetabular impingement. Standardized AP pelvic and axial radiographs and CT scans were performed in all patients for better radiological description of the population and to identify associated radiological factors. The ligament was thoroughly transected at its origin on the fossa acetabuli and at the insertion area on the fovea capitis and stored at -20°C until utilization. Specimens were mounted to a materials testing machine via custom clamps that minimized slippage and the likelihood of failure at the clamp. Force-displacement and stress-strain curves were generated. Ultimate failure load (N), tensile strength (MPa), stiffness (N/mm), and elastic modulus (MPa) were determined. Using a multivariate regression analysis and a subgroup analysis, we tested demographic, degenerative, and radiographic factors as potential associated factors.

RESULTS

The ligamentum teres demonstrated an ultimate load to failure of 126 ± 92 N, and the tensile strength was 1 ± 1 MPa. The ligaments exhibited a stiffness of 24 ± 15 N/mm and an elastic modulus of 7 ± 5 MPa. After controlling for potential confounding variables like age, fossa/fovea degeneration, and acetabular/femoral morphologies, we found that female sex was an independent factor for higher tensile strength, stiffness, and elastic modulus. Excessive femoral version was independently associated with lower load to failure (HR 122 [95% CI 47 to 197]) and stiffness (HR 15 [95% CI 2 to 27]). Damage to the acetabular fossa was associated with reduced load to failure (HR -93 [95% CI -159 to -27]).

CONCLUSION

Overall, the ligamentum teres is a relatively weak ligament. Sex, degeneration, and excessive femoral version are influencing factors on strength of the ligamentum teres. The ligamentum teres exhibits lower strength compared with other joint-stabilizing ligaments, which calls into question its overall contribution to hip stability.

CLINICAL RELEVANCE

Young patients undergoing hip-preserving surgery are the population at risk for ligamentum teres lesions. Baseline values for load to failure, tensile strength, elastic modulus, and stiffness are needed to better understand those lesions in this cohort of interest.

Load-deformation properties of the ligament of the head of femur in situ

The ligament of the head of femur (LHF) or ligamentum teres has been reported to tense during hip adduction and also to provide mechanical stability to the joint. LHF injury is more common in females and also in right hip joints compared with left ones. Although this could be due to leg dominance, pelvic size or muscle strength, there is no study that has looked into these differences. This cadaveric biomechanical study aimed to compare potential differences in the mechanical behavior of the LHF between neutral and 20° adducted hip joints, sex, and sides. Tensile tests of the LHF were performed on 25 hip joints (mean age at death of 85.7 ± 7.5 years; 9 females, 4 males; 13 left, 12 right), positioned either neutrally or in adduction. The maximum force required to rupture the ligament, its strain at failure, tensile strength, linear stiffness, and elastic modulus were obtained and statistically compared between analysis groups. The maximum force the LHF could withstand before rupture averaged 57 ± 37 N, strain at failure of 59 ± 33%, tensile strength of 2.9 ± 1.8 MPa, linear stiffness of 5.4 ± 3.5 N/mm, and elastic modulus of 7.2 ± 3.8 MPa. The LHF length at failure was significantly greater in males compared with females (P = 0.02). Irrespective of joint position, there were no statistical differences in the stress-strain properties of the LHF between females and males, or sides. There may be other anatomical, functional, and demographic factors that could render the ligament tissue vulnerable to injury in these groups. Clin. Anat., 33:705-713, 2020. © 2019 Wiley Periodicals, Inc.

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.

Contribution of the Ligamentum Teres to Hip Stability in the Presence of an Intact Capsule: A Cadaveric Study

PURPOSE

To determine the contribution of the ligamentum teres (LT) to hip stability in the presence of an intact capsule with special attention to the change in range of motion and femoral head translation.

METHODS

Seven fresh-frozen cadaveric pelvises were used. Following visual inspection of the LT at different hip positions, internal rotation angles were measured at 10° of extension and at 0° of flexion, while external rotation was measured at 60°, 90°, and 110° of flexion with different hip abduction angles using electromagnetic motion tracking sensor. Femoral head translations were measured simultaneously. The tests were repeated after resection of the LT. The capsule was left intact for all test conditions. The results were compared between intact and LT resected conditions when torque of 2 and 4 Nm was applied.

RESULTS

Compared with the intact hip, the LT resected hip showed no significant difference when 2 Nm torque was applied in all scenarios. With 4 Nm torque application, significant increase in external rotation was found at 60° and at 90° of flexion (1.7° ± 0.8° and 2.1° ± 1.0°, respectively). Significant difference was also noted at 60°, 90°, and 110° of flexion when the hip was in the adducted position while at 90° in the abducted hip. However, LT resection did not show significant change in internal rotation. There was no significant difference in the translation distance of the femoral head in the intact hip compared with the LT resected hip (0.77-1.11 mm vs 0.79-1.29 mm).

CONCLUSIONS

Our results indicate that within the physiologic range of motion, LT can minimally limit external rotation when the hip is in the flexed position but does not contribute to translation stability.

CLINICAL RELEVANCE

In the hip with intact capsule, LT deficiency can result in a slight increase in range of motion, but its contribution to stability is questionable.

Medial approach open reduction with ligamentum teres partial excision and plication for the management of congenital hip dislocation

Because of the known tendency for early redislocation following open reduction, we developed surgical methods for shortening the ligamentum teres to improve immediate postoperative stability when performing medial approach open reduction (MAOR) for the management of developmental dysplasia of the hip. Between 2004 and 2014, 32 patients with dysplasia of the hip were managed by MAOR with partial excision and plication of ligamentum teres. The patients were followed up for an average of 6.9 years. At the final follow-up, clinical outcomes achieved were categorized as excellent and good in 39 (39/40; 97.5%) hips. At the latest follow-up, 97.5% (39 hips) were classified as good or excellent on the basis of the Severin classification (Severin grade 1 or 2). In conclusion, this series of MAOR, in which ligamentum teres partial excision and plication was utilized, we found stable reduction in all hips. On the basis of these positive results, we recommend this method for children treated with MAOR.

LEVEL OF EVIDENCE

Level IV: case series.

Three-dimensional architecture of the ligamentum teres in the human hip joint

Background

We aimed to investigate the three-dimensional structure of the collagenous fibers of the ligamentum teres (LT) of the human hip and clarify the LT micro-anatomy at the attachment of the femoral head.

Methods

Femoral heads and LT were collected during hip arthroplasty. Specimens were cut into 5-10-mm squares, prepared, developed, and observed under a light microscope. Next, specimens were prepared and examined under a scanning electron microscope (SEM).

Results

Under optical microscope, LT adhered to the artificial cartilage at the attachment of the femoral head. Under SEM, LT comprised parallelly arranged collagenous fibers and the fine collagenous fibrils were twisted. While the central collagenous fibers of the LT at the attachment of the femoral head penetrated the articular cartilage tissue and reached the ring-shaped bone, fibers at the margin traversed and adhered to the cartilage surface.

Conclusion

Articular cartilage and subchondral bone are present at the LT attachment to the femoral head. Although collagenous fibers of the LT show parallel arrangement at the main trunk, they are dispersed at the cartilage surface and not all reach the thin subchondral bone of the femoral head. This could possibly weaken ligament strength at the attachment of the femoral head.

Level of evidence

IV.

Arthroscopic Reconstruction of the Ligamentum Teres: A Guide to Safe Tunnel Placement

PURPOSE

To provide a quantitative guide to tunnel placement concurrently through the femur and acetabulum during a ligamentum teres reconstruction, minimizing the risk of injury to the obturator neurovascular bundle.

METHODS

Nine human cadaveric pelvises, complete with femurs (mean age, 59.6 years; age range, 47-65 years), were studied. Before dissection, a 3-dimensional coordinate-measuring device was used to record the neutral orientation of the femur in the acetabulum. The specimens were then dissected free of all extra-articular soft tissue, except for the ligamentum teres and the obturator neurovascular bundle, and digitized. An anatomic femoral reconstruction tunnel through the femoral neck was simulated and extended along its axis into the acetabulum. The femur was digitally rotated internally from 0° to 30° and externally from 0° to 40°, as well as abducted from 0° to 30° and adducted from 0° to 20°, in increments of 1°. At each position, the location of the simulated acetabular reconstruction tunnel was measured with respect to the obturator bundle and the edge of the acetabular fossa.

RESULTS

The anatomic reconstruction tunnel entered the lateral side of the femur at a mean distance of 7.0 mm distal and 5.8 mm anterior to the center of the vastus ridge. By angling the femur at 15° of internal rotation and 15° of abduction, the obturator neurovascular bundle was avoided in 100% of specimens.

CONCLUSIONS

The most important finding of this study was that a ligamentum teres reconstruction tunnel could be reamed through the femoral neck and safely positioned in the acetabulum by angling the femur at 15° of internal rotation and 15° of abduction.

CLINICAL RELEVANCE

These quantitative descriptions of the ligamentum teres reconstruction tunnels can be used to guide arthroscopic surgical interventions designed to address ligamentum teres pathology.

Microinstability of the hip: a previously unrecognized pathology

BACKGROUND

Hip microinstability is an established diagnosis; however, its occurrence is still debated by many physicians. Diagnosis of hip microinstability is often challenging, due to a lack of specific signs or symptoms, and patients may remain undiagnosed for long periods. This may lead to early manifestation of degenerative joint disease. Consequently, careful patient and family history must be obtained and diagnostic imaging should follow. After a thorough clinical evaluation of the patient with suspected hip microinstability, the physician should focus on how to improve symptoms and functionality in daily and sports activities.

PURPOSE

The purpose of this review article was to give a current update regarding this diagnosis and to provide a complete diagnostic approach in order to effectively treat hip microinstability.

METHODS

We reviewed the literature on the diagnosis, the non-operative and operative indications for the treatment of this complex and often misdiagnosed pathology.

CONCLUSION

Conservative treatment is considered the best initial approach, though, surgical intervention should be considered if symptoms persist or other hip pathology exists. Successful surgical intervention, such as hip arthroscopy, should focus on restoring the normal anatomy of the hip joint in order to regain its functionality. The role of the hip joint capsule has gained particular research interest during the last years, and its repair or reconstruction during hip arthroscopy is considered necessary in order to avoid iatrogenic hip microinstability. Various capsular closure/plication techniques have been developed towards this direction with encouraging results.

LEVEL OF EVIDENCE

V.

Clinical and radiographical results of labral reconstruction

Treatment of femoroacetabular impingement (FAI) includes correction of underlying bony deformities. Labrum preservation is recommended whenever possible. In hips, where the labrum is missing or damaged beyond preservation, labral reconstruction is an option to restore labral seal. Between 2008 and 2011, 84 hips underwent treatment for FAI by means of a surgical hip dislocation. In 13 of these hips (11 patients), the severely damaged or missing labrum was reconstructed with ligamentum capitis femoris. Pre- and postoperative radiographic and clinical data were analysed with a mean follow-up of 38 months (range: 19–65 months). Clinical outcome was determined with Oxford hip score (OHS) and overall satisfaction, rest and load pain with a visual analogue scale (VAS; 0–100). Clinical outcome was compared with a control group where labral refixation was performed. Mean OHS improved significantly (P ≤ 0.001) from 29 (SD 8) to 44 (SD 4). Overall satisfaction with the hip increased significantly (P = 0.002) from 44 (SD 35) to 87 (SD 15). Mean VAS for rest pain decreased significantly (P = 0.0004) from 45 (SD 35) to 5 (SD 7) as well as for load pain (P = 0.0007) from 59 (SD 26) to 16 (SD 19). There were no significant differences between the two groups. Reconstruction of the acetabular labrum with ligamentum capitis femoris yields good clinical results. Technical superiority of open labral reconstruction may explain the unexpected, excellent outcome.

Comparison of mechanoreceptor quantities in hip joints of developmental dysplasia of the hip patients with normal hips

BACKGROUND

Joint mechanoreceptors are afferent neural elements involved in pain sensation and tactile sense.

QUESTIONS/PURPOSES

We aimed to detect the free nerve endings (FNE) and other types of mechanoreceptors and to compare their quantities in human hip joint capsule (HJC) and ligamentum capitis femoris (LCF) of babies with developmantal dysplasia of hip (DDH) and intrauterine ex foetuses (control group) to find out whether there is an increase in the amount of mechanoreceptors in hip joint due to the occured anatomical chages.

PATIENTS AND METHODS

We took 15 LCF and HJC biopsies from 15 patients undergoing hip surgery for DDH, and 15 HJC and LCFs from intrauterine ex fetuses. Total of 60 specimens were investigated. The mean age of the babies was 10.3 months (6-18 months) at the time of surgery. Full thickness 1 × 1 cm HJC and LCF portions were taken as biopsy specimens. An immunohistochemical technique was performed for neurogenic protein S-100 and examined under light microscopy.

RESULTS

FNEs were detected in all four different tissues (type IVa). Other types of mechanoreceptors (Type I-II and III) were not detected in any of the specimens. The positive rates of FNE staining in the control group were % 2.60 ± 1.24 for the LCF and % 2.67 ± 1.11 for the HJC respectively and FNE staining in the DDH group were found to be % 2.67 ± 1.11 for the LCF and % 2.73 ± 1.16 for the HJC. We did not find a statistically significant difference in number of FNEs between the specimens of the DDH group and the control group (p>0.05), also there was no statistically significant difference in number of FNEs between the HJC and LCF within each group (p>0.05).

CONCLUSION

Our results suggest that the number of FNEs does not increase in HJC and LCF of DDH patients even though LCF hypertrophy and capsular elongation occurs.

Structural Properties of the Native Ligamentum Teres

Background:

A majority of studies investigating the role of the ligamentum teres (LT) have focused primarily on anatomical and histological descriptions. To date, however, the structural properties of the LT have yet to be fully elucidated.

Purpose:

To investigate the structural properties of the native LT in a human cadaveric model.

Study Design:

Descriptive laboratory study.

Methods:

A total of 12 human cadaveric hemipelvises (mean age, 53.6 years; range, 34-63 years) were dissected free of all extra-articular soft tissues to isolate the LT and its acetabular and femoral attachments. A dynamic tensile testing machine distracted each femur in line with the fibers of the LT at a displacement-controlled rate of 0.5 mm/s. The anatomic dimensions, structural properties, and modes of failure were recorded.

Results:

The LT achieved a mean yield load of 75 N and ultimate failure load of 204 N. The LT had mean lengths of 38.0 and 53.0 mm at its yield and failure points, respectively. The most common (75% of specimens) mechanism of failure was tearing at the fovea capitis. On average, the LT had a linear stiffness of 16 N/mm and elastic modulus of 9.24 MPa. The mean initial length and cross-sectional area were 32 mm and 59 mm², respectively.

Conclusion:

The human LT had a mean ultimate failure load of 204 N. Therefore, the results of this investigation, combined with recent biomechanical and outcomes studies, suggest that special consideration should be given to preserving the structural and corresponding biomechanical integrity of the LT during surgical intervention.

Clinical Relevance:

The LT may be more important as a static stabilizer of the hip joint than previously recognized. Further studies are recommended to investigate the appropriate indications to perform surgical repair or reconstruction of the LT for preservation of hip stability and function.

Nonarthritic hip joint pain

The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these clinical practice guidelines is to describe the peer-reviewed literature and make recommendations related to nonarthritic hip joint pain.

Fibromyxoid pseudotumor of the ligamentum teres treated with fresh osteochondral allograft

Intra-articular tumors and tumor-like conditions of the hip are rare. When they occur, they can interrupt normal articular congruency, leading to pain and joint dysfunction. If these conditions result in large osteochondral defects, they pose challenging reconstructive problems in young patients. We describe a case of a 29-year-old man who presented with a 2-year history of right hip pain. Advanced imaging demonstrated an expansile lesion in the region of his ligamentum teres (LT), eroding a significant portion of his femoral head and expanding the cotyloid fossa. He was treated with surgical hip dislocation, excision of the lesion, and femoral head reconstruction with fresh osteochondral (OC) allograft transplantation via press-fit technique. Histologic examination of the mass showed a benign fibromyxoid pseudotumor. Although non-neoplastic masses have been described in almost all organ systems, to our knowledge this is the first description of this entity affecting the native hip joint. It is only the second description of using press-fit OC allografting in the femoral head. This case adds to the body of literature defining symptomatic LT pathology that may benefit from surgical management. It underscores the need to study the ligament further, as the ability to diagnose and treat intra-articular hip pathology has improved with modern imaging and methods of open and arthroscopic hip surgery.

In vivo baseline measurements of hip joint range of motion in suspensory and nonsuspensory anthropoids

Hominoids and atelines are known to use suspensory behaviors and are assumed to possess greater hip joint mobility than nonsuspensory monkeys, particularly for range of abduction. This assumption has greatly influenced how extant and fossil primate hip joint morphology has been interpreted, despite the fact that there are no data available on hip mobility in hominoids or Ateles. This study uses in vivo measurements to test the hypothesis that suspensory anthropoids have significantly greater ranges of hip joint mobility than nonsuspensory anthropoids. Passive hip joint mobility was measured on a large sample of anesthetized captive anthropoids (nonhuman hominids = 43, hylobatids = 6, cercopithecids = 43, Ateles = 6, and Cebus = 6). Angular and linear data were collected using goniometers and tape measures. Range of motion (ROM) data were analyzed for significant differences by locomotor group using ANOVA and phylogenetic regression. The data demonstrate that suspensory anthropoids are capable of significantly greater hip abduction and external rotation. Degree of flexion and internal rotation were not larger in the suspensory primates, indicating that suspension is not associated with a global increase in hip mobility. Future work should consider the role of external rotation in abduction ability, how the physical position of the distal limb segments are influenced by differences in ROM proximally, as well as focus on bony and soft tissue differences that enable or restrict abduction and external rotation at the anthropoid hip joint.

Catastrophic failure of hip arthroscopy due to iatrogenic instability: can partial division of the ligamentum teres and iliofemoral ligament cause subluxation?

Hip arthroscopy is an evolving surgical tool, and with any new procedure, it is important to learn from the complications encountered. A patient with mild hip dysplasia and a symptomatic labral tear underwent uneventful hip arthroscopy and labral repair including partial debridement of a hypertrophied ligamentum teres. Despite preservation of the labrum, no pincer resection, and a modest capsulotomy, 3 months, subluxation and joint space narrowing were noted. One year, end-stage arthritis was present, requiring total hip replacement. Instability after hip arthroscopy is due to a number of factors, including excessive rim trimming, capsulotomy, overzealous labral resection, or inadequate labral repair. This report emphasizes the importance of the ligamentum teres and small disruptions of the capsule in patients with mild dysplasia.

Isocentric reattachment of ligamentum teres: a porcine study

BACKGROUND

Recent reports reveal interest in the mechanical importance of ligamentum teres (LT) in hip dislocation. In the previously established procedure of anteroinferior acetabular LT reattachment in developmental dysplasia of the hip, the LT functions as a check-rein, showing promising results. However, this position of reattachment could potentially limit motion. The purpose of this study was to evaluate the feasibility of an isocentric point for reattachment of the LT and to study its impact on hip function using a young porcine model.

METHODS

Pelvic specimens with intact anatomy were obtained from 6 skeletally immature pigs (12 hips). Through a careful anteromedial capsulotomy, the LT was detached from its acetabular insertion then reattached to 1 of 2 positions: (1) anteroinferior lip of the acetabulum; (2) proposed isocentric position. Intra-articular stress distribution was measured through a complete range of motion with a prescale Fuji pressure film. Tension was then applied to the LT and the stresses were recorded again. In addition, radioopaque solution was injected into the substance of the LT, then floroscopy tracked the LT location initially and after the 2 reattachment positions through a full hip range of motion.

RESULTS

Reattachment of the LT at an isocentric point is feasible in a pig model. With careful physiologic tensioning of this reattachment, hip can maintain full motion with no excessive pressure areas created within the joint. On the contrary, the initial technique of anteroinferior extra-articular attachment limits external rotation and extremes of abduction. We found this LT tracking technique (with radioopaque dye injection) to be reliable and reproducible.

CONCLUSIONS

The isocentric reattachment of the LT is feasible in this pig model and serves as a natural check-rein to dislocation without limiting joint motion or causing abnormal cartilage pressures.

CLINICAL RELEVANCE

Isocentric LT reattachment may provide a method for improving stability of open reductions when treating children with such conditions.

Emerging topics on the hip: ligamentum teres and hip microinstability

Microinstability and ligament teres lesions are emergent topics on the hip pathology. These entities are an increasingly recognized cause of persistent hip pain and should be considered in the differential diagnosis of the patient with hip pain. Conventional (non-arthrographic) CT and MR have a very limited role in the evaluation of these entities. CTa and MRa have emerged as the modalities of choice for pre-operative imaging of ligamentum teres injuries and microinstability. To date, pre-operative imaging detection of these pathologies is not widespread but with appropriate imaging and a high index of suspicion, preoperative detection should improve. This article discusses current concepts regarding anatomy, biomechanics, clinical findings, diagnosis and treatment of ligament teres lesions and microinstability.

Tears of the ligamentum teres: prevalence in hip arthroscopy using 2 classification systems

BACKGROUND

The ligamentum teres (LT) anatomy has been known for many years. While its functionality remains debatable, it is well recognized that the LT can be a source of pain in the hip joint. In 1997, a landmark publication by Gray and Villar established a classification for LT tears and increased the awareness of LT disorders. However, the incidence of LT tears and the various tear types is unknown.

PURPOSE

The authors report the prevalence of LT tears in a population of patients who underwent hip arthroscopy, using both the Gray and Villar classification and a new descriptive classification.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between February 2008 and January 2011, 616 hip arthroscopies were performed by the senior author. After excluding revision surgeries, a total of 558 surgeries (502 patients) were included in the study. Data were collected regarding patients' demographics, mechanism of injury, range of motion, magnetic resonance results, and intraoperative findings. Preoperative hip-specific questionnaire scores and pain level were recorded as well. Ligamentum teres tears were classified according to Gray and Villar's classification, and were also categorized using a descriptive grading system as follows: 0, no tear; 1, <50% tear; 2, >50% tear; or 3, 100% tear.

RESULTS

A total of 284 (51%) of the 558 surgeries in this cohort revealed LT tears. According to the descriptive grading system, 22% were grade 1, 24% were grade 2, and 5% were grade 3. According to the Gray and Villar classification 3.7% had full rupture, 43% had a partial tear, and 4.5% had a degenerative tear. Patients with LT tears were significantly older and had worse preoperative functional scores; they did, however, have a greater range of motion. Intraoperatively, an association with larger labral tear size and acetabular chondral damage was found. Magnetic resonance arthrography was found to have low accuracy and sensitivity in detection of LT tears. No correlation to the pain level was found.

CONCLUSION

Ligamentum teres tears had a higher prevalence in this study than was published in the past, most probably attributable to a lower threshold used in defining a tear. The incidence is defined both using the Gray and Villar classification, as well as a new descriptive classification system that categorizes the LT according to amount of tearing.

Hip instability

Understanding of the etiology and pathology of hip instability has increased in recent years as new information has emerged regarding the disease processes of the hip. Hip instability, heretofore considered uncommon in clinical practice, is increasingly recognized as a pathologic entity. Instability may be classified as traumatic or atraumatic, and diagnosis is made based on patient history, physical examination, and imaging studies. Plain radiography, MRI, MRI arthrography, and hip instability tests (eg, posterior impingement, dial) can be used to confirm the presence of instability. Nonsurgical management options include physical therapy and protected weight bearing. Surgical intervention, whether arthroscopic or open, is required for large acetabular fractures and refractory instability. Knowledge of the etiology and evolving research of hip instability is essential to understand the spectrum of hip disease.

The ligamentum teres of the adult hip

Advances in hip arthroscopy have renewed interest in the ligamentum teres. Considered by many to be a developmental vestige, it is now recognised as a significant potential source of pain and mechanical symptoms arising from the hip joint. Despite improvements in imaging, arthroscopy remains the optimum method of diagnosing lesions of the ligamentum teres. Several biological or mechanical roles have been proposed for the ligament. Unless these are disproved, the use of surgical procedures that sacrifice the ligamentum teres, as in surgical dislocation of the hip, should be carefully considered. This paper provides an update on the development, structure and function of the ligamentum teres, and discusses associated clinical implications.

Ligamentum teres maintenance and transfer as a stabilizer in open reduction for pediatric hip dislocation: surgical technique and early clinical results

PURPOSE

The ligamentum teres has primarily been considered as an obstruction to reduction in children with developmental dislocation of the hip (DDH). In the early surgical descriptions of both the medial (Ludloff) approach and the anterior (Salter) approach to the hip, it was generally accepted that the ligamentum teres was an obstruction to reduction and was excised (similar to the discarding of menisci for knee surgery in our orthopedic history). Because of the known propensity for early re-dislocation following open reduction, we developed surgical methods for maintaining the ligamentum teres when performing open reduction for hip dislocation in young children. This study presents the surgical methods developed for ligament maintenance and transfer, and analyzes the early clinical and radiographic results in a study group.

METHODS

The techniques for open reduction by both the medial Ludloff approach and the anterior open reduction were developed and refined. Twenty-one children (23 hips) had ligamentum teres shortening and transfer performed as part of either a medial Ludloff or anterior open reduction for hip dislocation. Complete pre-operative and post-operative clinical and radiographic analysis was performed.

RESULTS

All patients had stable hips at follow-up. The transferred ligamentum teres appeared to provide additional stability to prevent repeat dislocation. We noted no apparent loss of hip motion or other adverse events. One patient had avascular necrosis (AVN).

CONCLUSIONS

In this series of 23 hips, in which ligamentum teres transfer/tenodesis was utilized, we found no residual subluxation or dislocation in either the medial Ludloff or the anterior open reduction groups. Based on these early positive results, we recommend the method for children treated with the Ludloff open reduction procedure. Although we have less experience with it, the technique presented for ligamentum maintenance and transfer in anterior open reduction may provide similar added stability. This is an early follow-up study, and long-term follow-up will be required to confirm the ultimate femoral head and acetabular development.

The mechanical properties of the ligamentum teres: a pilot study to assess its potential for improving stability in children's hip surgery

The anatomic and histological characteristics of the ligamentum teres and its vascular contributions to the femoral head have been well described. The function of the ligamentum teres remains poorly understood. Although excision is the current standard in treating complete developmental hip dysplasia, we developed an interest in maintaining, shortening, and reattaching the ligament to assure early postoperative stability in developmental hip dysplasia. To analyze its potential for providing hip joint stability, we investigated the biomechanical properties of the ligamentum teres in an in vitro porcine model. Six immature porcine hips were dissected, with the proximal femur and acetabular anatomy kept intact, isolating the ligamentum teres. Specimens were loaded in tension using custom fixation rigs at 0.5 mm/s in line with the fibers. Data for displacement and force were collected and sampled at 10 Hz for duration of each test. The ligamentum teres failed in a stepwise fashion. The mean ultimate load to failure was 882 +/- 168 N. Mean stiffness and failure stress were calculated as 86 +/- 25 N/mm and 10 +/- 2 MPa, respectively. The biomechanical function of the ligamentum teres is not inconsequential. We found the ultimate load of the ligamentum teres in the porcine model to be similar to those reported for the human anterior cruciate ligament. The strength of the ligamentum teres may confirm its potential for providing early stability in childhood hip reconstructions. In the setting of dysplasia, the preservation and the transfer of the ligamentum teres to augment stability should be considered as an adjunct to open reduction.

Hip arthroscopy: current indications, treatment options, and management issues

The management of hip injuries in athletes has evolved significantly in the past few years with the advancement of arthroscopic techniques. The application of minimally invasive surgical techniques has facilitated relatively rapid returns to sporting activity in both recreational and elite athletes. Recent advancements in both hip arthroscopy and magnetic resonance imaging have elucidated several sources of intraarticular abnormalities that result in chronic and disabling hip symptoms. Many of these conditions were previously unrecognized and, thus, left untreated. Current indications for hip arthroscopy include the presence of symptomatic acetabular labral tears, hip capsule laxity and instability, chondral lesions, osteochondritis dissecans, ligamentum teres injuries, snapping hip syndrome, iliopsoas bursitis, and loose bodies (for example, synovial chondromatosis). Less common indications include management of osteonecrosis of the femoral head, bony impingment, synovial abnormalities, crystalline hip arthropathy (gout and pseudogout), infection, and posttraumatic intraarticular debris. In rare cases, hip arthroscopy can be used to temporize the symptoms of mild-to-moderate hip osteoarthritis with associated mechanical symptoms. This article discusses the current clinical and radiographic methods to detect early hip joint disease and the current indications and surgical techniques of hip arthroscopy.

Injury to the ligamentum teres. Mechanism, findings, and results of treatment

In this article we discuss the role of the ligamentum teres in relation to the hip joint. The anatomy of the ligamentum teres is used to help with an understanding of the mechanism of the ligament's actions. This action and the modes of injury to the ligament are explored. We describe a simple classification system for injuries to the ligamentum teres, such that Group I are complete tears to the ligament; Group II are partial tears; and Group III are degenerative tears. As more experience is gained with the diagnosis and treatment of injuries to this integral structure, the clearer will be our understanding of the role of the ligamentum teres in the hip joint.

Porcine anterior cruciate ligament fibroblasts are similar to cells derived from the ligamentum teres, another non-healing intra-articular ligament

Porcine ligament fibroblasts were cultured from the anterior cruciate (ACL), medial collateral (MCL), and ligamentum teres (LT). There were no apparent differences in confluent cellular morphology among the ligament cell types as evaluated by phase contrast microscopy. The proliferation rate of MCL cells from 24-120 h was significantly higher (p < 0.05) than that of cells from either the LT or the ACL. MCL cells produced more collagen and less non-collagenous protein than the LT and ACL as determined by [3H]proline incorporation. This resulted in MCL cells producing a higher percentage (37%, p < 0.05) of collagen relative to total protein than either the ACL (28%) or the LT (32%). The MCL cells produced a significantly higher percentage (34.7%, p < 0.05) of type-III collagen relative to total type-I and III collagen than either the ACL (29.2%) or the LT (29.5%). The LT and MCL cells had similar and significantly greater coverage of in vitro wounds than the ACL. This study provides the first in vitro study of the LT and demonstrates that fibroblasts from the LT and ACL, two ligaments that heal poorly, have similar in vitro characteristics, with the exception of wound healing.