Structural Properties of the Native Ligamentum Teres

The contribution of the ligamentum teres to the hip fluid seal: A biomechanics study

BACKGROUND

The suction seal of the hip plays an important role in maintaining hip stability; however, the function of the ligamentum teres in maintaining this seal remains poorly understood. This study aimed to evaluate the effectiveness of the hip suction seal in ligamentum teres deficient hips for joint positions occurring during gait.

METHODS

Six fresh-frozen human cadaveric hips were dissected and mounted to an Instron materials test system. Each specimen was analyzed for average peak distraction force, stiffness, and total energy during hip displacement. Testing was performed in the native intact ligamentum teres state and the deficient ligamentum teres state. Specimens were examined in 20° of flexion, neutral, and 10° of extension.

FINDINGS

In the neutral position, the ligamentum teres deficient state displayed a significant decrease in peak distraction force (mean difference: 33.2 N, p < 0.001), average stiffness (mean difference: 63.7 N/mm, p = 0.016), and total energy (mean difference: 82.3 mJ, p = 0.022) compared to the intact controls. In extension, the deficient state exhibited a significant decrease in peak distraction force (mean difference: 42.8 N, p < 0.001) and total energy (mean difference: 72.9 mJ, p = 0.007). In flexion, the deficient state displayed a significant decrease in peak distraction force relative to contols (mean difference: 7.1 N, p = 0.003).

INTERPRETATION

The ligamentum teres plays a significant role in maintaining the suction seal of the hip, with its effect being most prominent when the hip is in neural alignment or in extension. The findings suggest that ligamentum teres deficiency may be a relevant treatment target in the clinical setting.

A guide to facilitate the creation of a femoral tunnel for arthroscopic ligamentum teres reconstruction: a three-dimensional computed tomography study

The ideal femoral tunnel passing through the centre of the femoral neck targeted to the footprint of the ligamentum teres (LT) is established during the LT reconstruction surgery with the free-hand technique. We aimed to quantitatively determine the entry site and define the angular orientation of the ideal femoral tunnel with its relevance to the femoral valgus angle (FVA) and the femoral anteversion angle (FAA) to facilitate the creation of an ideal femoral tunnel during the LT reconstruction surgery. A total of 60 randomly selected CT images were obtained to reconstruct three-dimensional femur models. A virtual reamer representing the ideal femoral tunnel was placed in the femur models. The femur length, FVA, FAA, the femoral tunnel anterior angle, the femoral tunnel superior angle and the skin- and bony-entry sites were measured. The femoral tunnel angular orientation was strongly correlated with the FVA and the FAA. Mathematical formulas were defined by which entry site of the reamer and the anterior and superior angulation of the femoral tunnel could be estimated before the surgery. The mean skin-entry site was 67.3 mm distal and 0.1 mm anterior to the centre of the greater trochanter's superior border. The angular orientation of the femoral tunnel using FVA and FAA can be easily estimated using mathematical formulas before LT reconstruction surgery. The entry site and angular orientation of the femoral tunnel described in this study can be used to reduce dependency on the usage of fluoroscopy and the workload on the surgeon during the LT reconstruction surgery.

Calibration procedure and biomechanical validation of an universal six degree-of-freedom robotic system for hip joint testing

PURPOSE

Among various test methods for different human joints, the use of robot systems has attracted major interest and inherits the potential to become a gold standard in biomechanical testing in the future. A key issue associated with those robot-based platforms is the accurate definition of parameters, e.g., tool center point (TCP), length of tool or anatomical trajectories of movements. These must be precisely correlated to the physiological parameters of the examined joint and its corresponding bones. Exemplified for the human hip joint, we are creating an accurate calibration procedure for a universal testing platform by using a six degree-of-freedom (6 DOF) robot and optical tracking system for recognition of anatomical movements of the bone samples.

METHODS

A six degree-of-freedom robot (TX 200, Stäubli) has been installed and configured. The physiological range of motion of the hip joint composed of a femur and a hemipelvis was recorded with an optical 3D movement and deformation analysis system (ARAMIS, GOM GmbH). The recorded measurements were processed by automatic transformation procedure (created in Delphi software) and evaluated in 3D CAD system.

RESULTS

The physiological ranges of motion were reproduced for all degrees of freedom with the six degree-of-freedom robot in adequate accuracy. With the establishment of a special calibration procedure by using a combination of different coordinate systems, we were able to achieve a standard deviation of the TCP depending of the axis between 0.3 and 0.9 mm and for the length of tool between + 0.67 and - 0.40 mm (3D CAD processing) resp. + 0.72 mm to - 0.13 mm (Delphi transformation). The accuracy between the manual and robotic movement of the hip shows an average deviation between - 0.36 and + 3.44 mm for the points on the movement trajectories.

CONCLUSION

A six degree-of-freedom robot is appropriate to reproduce the physiological range of motion of the hip joint. The described calibration procedure is universal and can be used for hip joint biomechanical tests allowing to apply clinically relevant forces and investigate testing stability of reconstructive osteosynthesis implant/endoprosthetic fixations, regardless of the length of the femur, size of the femoral head and acetabulum or whether the entire pelvis or only the hemipelvis will be used.

Criteria for the Operating Room Confirmation of the Diagnosis of Hip Instability: The Results of an International Expert Consensus Conference

PURPOSE

The purpose of this study was to establish an international expert consensus on operating room findings that aid in the diagnosis of hip instability.

METHODS

An expert panel was convened to build an international consensus on the operating room diagnosis/confirmation of hip instability. Seventeen surgeons who have published or lectured nationally or internationally on the topic of hip instability were invited to participate. Fifteen panel members completed a pre-meeting questionnaire and agreed to participate in a 1-day consensus meeting on May 15, 2021. A review of the literature was performed to identify published intraoperative reference criteria used in the diagnosis of hip instability. Studies were included for discussion if they reported and intraoperative findings associated with hip instability. The evidence for and against each criteria was discussed, followed by an anonymous voting process. For consensus, defined a priori, items were included in the final criteria set if at least 80% of experts agreed.

RESULTS

A review of the published literature identified 11 operating room criteria that have been used to facilitate the diagnosis of hip instability. Six additional criteria were proposed by panel members as part of the pre-meeting questionnaire. Consensus agreement was achieved for 8 criteria, namely ease of hip distraction under anesthesia (100.0% agreement), inside-out pattern of chondral damage (100.0% agreement), location of chondral damage on the acetabulum (93.3% agreement), pattern of labral damage (93.3% agreement), anteroinferior labrum chondral damage (86.7% agreement), perifoveal cartilage damage (97.6% agreement), a capsular defect (86.7% agreement), and capsular status (80.0% agreement). Consensus was not achieved for 9 items, namely ligamentum teres tear (66.7% agreement), arthroscopic stability tests (46.7% agreement), persistent distraction after removal of traction (46.7% agreement), findings of examination under anesthesia (46.7% agreement), the femoral head divot sign (40.0% agreement), inferomedial synovitis (26.7% agreement), drive-through sign (26.7% agreement), iliopsoas irritation (26.7% agreement) and ligamentum teres-labral kissing lesion (13.3% agreement). All experts agreed on the final list of 8 criteria items reaching consensus.

CONCLUSION

This expert panel identified 8 criteria that can be used in the operating room to help confirm the diagnosis of hip instability.

LEVEL OF EVIDENCE

Level V expert opinion.

Central acetabular osteophytes (CAO) are more prevalent in the borderline developmental dysplastic hip (BDDH) patients: a propensity-score matched CT study

Background

The acetabular fossa often showing the first signs of degeneration, Central acetabular osteophytes (CAO) have been increasingly recognized during hip arthroscopy. The purpose of this study was to investigate the condition of CAO in BDDH hips and compare cotyloid fossa size between the BDDH and the non-BDDH hips on CT images.

Methods

We performed a retrospective analysis of prospectively collected data of hip CT images of FAI or labral injury patients. A 1:2 propensity-score matched observational study comparing the linear length of cotyloid fossa was analyzed. Cotyloid fossa width (CFW) and cotyloid notch width (CNW) were measured on axial images, cotyloid fossa height (CFH) and cotyloid fossa depth (CFD) were measured on coronal images. Within the CAO patients, we performed central acetabular decompression (CAD) and then observed the morphology change in fossa.

Results

Propensity-score matching yielded 61 BDDH hips and 122 non-BDDH hips. BDDH hips had a higher prevalence of CAO and a decreased linear length of cotyloid fossa (CFW, CFH and CNW). In the BDDH group, 33 hips underwent CAD, postoperative CFW, CFH and CNW were significantly increased (p < .001 for all), and had no statistical difference compared with the non-BDDH hips (p = .193, p = .132, p = .421, respectively).

Conclusion

BDDH hips had a significantly higher prevalence of CAO than adequate acetabular coverage hips. After the procedure of CAD, BDDH hips were found to have acetabular parameters (CFW, CFH, CNW) and were restored to that of the control hips.

In-line Pullout Strength of 2 Acetabular Fixation Methods for Ligamentum Teres Reconstruction of the Hip: A Cadaveric Study

Background:

Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of LT full-thickness tears, resulting in hip micro- or macroinstability. Graft fixation at the acetabular fossa is critical to achieving the best functional results.

Purpose:

The purpose of this study is to compare the pullout strength of 2 graft fixation methods used for LT reconstruction of the hip.

Study Design:

Controlled laboratory study.

Methods:

In 7 cadaveric specimens, the acetabular socket was prepared after the native LT was transected and the femoral head was removed. Seven separate tibialis anterior grafts were then prepared by suturing a running-locking No. 2 suture on each tail of the graft. Three specimens had fixation of the graft to the acetabulum using an adjustable cortical suspension suture button; the remaining 4 were fixed to the acetabulum using a knotless suture anchor. Specimens were then mounted onto a custom jig within a mechanical test frame to allow for the in-line pull of the graft fixation construct. After a preload of 5 N, each specimen was loaded to failure at 0.5 mm/s. Stiffness and load to failure were measured for each specimen construct.

Results:

Suture button fixation had a higher mean load to failure when compared with the knotless anchor fixation method (mean ± SD, 438.1 ± 114.3 vs 195.9 ± 50.0 N; P = .01). There was no significant difference in mean stiffness between the methods of fixation (24.5 ± 1.4 vs 26.5 ± 5.8 N/mm; P = .6).

Conclusion:

In this cadaveric study, the suture button fixation demonstrated greater load to failure than the knotless anchor fixation.

Clinical Relevance:

Results of this study can guide surgical decision making when selecting an acetabular fixation method for LT reconstruction.

The role and clinical relevance of the ligamentum teres: long-term outcomes after hip arthroscopic surgery of cam-type femoroacetabular impingement

We aimed to compare clinical and radiologic outcomes in patients with cam-type femoroacetabular impingement (FAI), with and without a partial ligamentum teres (LT) tear, who underwent hip arthroscopy (HA) with ≥10 years of follow-up. Among the patients who underwent HA for a cam-type FAI diagnosis with a labral tear, 28 patients (28 hips) with a partial LT tear and 87 patients (99 hips) with an intact LT were assigned to Groups A and B, respectively. All patients underwent partial labral debridement and femoroplasty. Debridement and thermal shrinkage were performed for LT tears. The grade of chondral damage was measured intraoperatively. Clinical items were assessed preoperatively and at the last follow-up. Patients’ satisfaction with the surgery and changes in postoperative sports ability in those who had previously been active in sports were assessed at the last follow-up. The Tönnis grade was assessed preoperatively and at the last follow-up for radiologic evaluation. Chondral damage to the acetabular and femoral head detected intraoperatively was significantly different between the groups (P = 0.005 and P &lt; 0.001). At the last follow-up, Group A patients experienced more difficulty performing sports activities than Group B patients (P = 0.056), and significantly, more Group A patients had stopped exercising despite their active participation in sports preoperatively (P = 0.002). Regarding the Tönnis grade, significant differences were found only at the final follow-up (P = 0.020). Patients with partial LT tear showed a higher grade of chondral damage, experienced decreased exercise capacity and had significantly worsened Tönnis grades, suggesting hip osteoarthritis progression compared to those with an intact LT.

Ligamentum Teres Transfer During Medial Open Reduction in Patients with Developmental Dysplasia of the Hip

BACKGROUND

The ligamentum teres (LT) is believed to have a number of functions, including a role in hip stability, nociception, proprioception, vascular supply to the femoral head, and synovial fluid circulation. The LT is often excised in the process of performing a medial open reduction (MOR) of the hip. We sought to conduct a retrospective review of hips undergoing a MOR for dislocated infantile developmental dysplasia of the hip (DDH) to compare clinical and radiographic outcomes for patients with and without LT reconstruction.

METHODS

We performed a retrospective review of 38 hips treated with MOR with or without LT reconstruction with minimum two-year follow-up. Radiographic outcomes were determined using the Severin score. Information regarding avascular necrosis (AVN), concomitant surgical procedures, repeat dislocation, subsequent surgery, limp, pain, and range of motion symmetry was recorded.

RESULTS

Eighteen hips that underwent MOR with LT reconstruction were compared to 20 hips that underwent MOR without LT reconstruction. Mean follow up for this cohort was 70.1 months (median: 61.8; Range: 24.2 to 182.2 months). The group with LT reconstruction had an 11% rate of AVN, the group without LT reconstruction had a 15% rate of AVN (p=1.0) No hips in either group re-dislocated or had pain at final follow up. Two hips (5%) had a limp at most recent follow up, all were in the group that did not receive a LT reconstruction (p=0.488). Three hips (17%) in the LT reconstruction group and one hip (5%) in the other group had asymmetrical hip range of motion at final follow up (p=0.328).

CONCLUSION

This study offers preliminary data to suggest that ligamentum teres reconstruction is a safe procedure that can minimize the risk for subluxation or re-dislocation that can occur within the post reduction hip spica cast. Although in this study, the patients who did not have LT reconstruction had a similar re-dislocation rate, we believe that ligamentum teres preservation is a useful adjunct to medial open reduction, especially in centers that may only treat occasional cases or have less experience in applying an excellent hip spica cast.Level of Evidence: III.

Hip preservation surgery and the acetabular fossa

As our understanding of hip function and disease improves, it is evident that the acetabular fossa has received little attention, despite it comprising over half of the acetabulum’s surface area and showing the first signs of degeneration. The fossa’s function is expected to be more than augmenting static stability with the ligamentum teres and being a templating landmark in arthroplasty. Indeed, the fossa, which is almost mature at 16 weeks of intrauterine development, plays a key role in hip development, enabling its nutrition through vascularization and synovial fluid, as well as the influx of chondrogenic stem/progenitor cells that build articular cartilage. The pulvinar, a fibrofatty tissue in the fossa, has the same developmental origin as the synovium and articular cartilage and is a biologically active area. Its unique anatomy allows for homogeneous distribution of the axial loads into the joint. It is composed of intra-articular adipose tissue (IAAT), which has adipocytes, fibroblasts, leucocytes, and abundant mast cells, which participate in the inflammatory cascade after an insult to the joint. Hence, the fossa and pulvinar should be considered in decision-making and surgical outcomes in hip preservation surgery, not only for their size, shape, and extent, but also for their biological capacity as a source of cytokines, immune cells, and chondrogenic stem cells.

Cite this article: Bone Joint Res 2020;9(12):857–869.

Arthroscopic Ligamentum Teres Reconstruction: Minimum 2-Year Patient-Reported Outcomes With Subanalysis of Patients With Ehlers-Danlos Syndrome

PURPOSE

To report on minimum 2-year outcomes of patients undergoing arthroscopic ligamentum teres reconstruction (LTR).

METHODS

Our institutional registry was retrospectively reviewed for all patients undergoing LTR between December 2012 and February 2016. LTR was indicated for a fully torn or dysfunctional ligamentum teres with symptomatic multidirectional instability not treatable by osteotomy or capsular plication alone. Demographic data, preoperative clinical and radiographic measures, and intraoperative data were recorded. Patient-reported outcome measures including the modified Harris Hip Score, the Non-Arthritic Hip Score, a visual analog scale score for pain, and patient satisfaction were recorded preoperatively and annually postoperatively. Revision arthroscopies and conversions to total hip arthroplasty were recorded.

RESULTS

Twelve reconstruction procedures were performed in 10 patients during the study period. Minimum 2-year follow-up was available for 9 patients (11 hips). The mean follow-up time was 44.27 months (range, 24-72 months). There were 7 female and 2 male patients, and the mean age was 30.34 years (range, 17.23-43.68 years). Two hips underwent conversion to total hip arthroplasty at a mean of 21.12 months. For the remaining patients, significant improvements were observed in the modified Harris Hip Score (from 44.1 to 71.8), Non-Arthritic Hip Score (from 47.5 to 78.6), and visual analog scale score (from 7.8 to 3.6) (P < .05). The average patient satisfaction rating was 7.88 (range, 4-10). Subanalysis of 5 patients (7 hips) with a diagnosis of Ehlers-Danlos syndrome showed a higher failure rate in this group.

CONCLUSIONS

Although LTRs are indicated and performed only in a select group of patients, the procedure can provide meaningful improvement in patient-reported outcomes, pain reduction, and patient satisfaction. However, most patients undergoing LTR at present have underlying factors that significantly mitigate their prognosis, such as Ehlers-Danlos syndrome or failed previous surgery. Because these patients represent a subset of patients with complex hip pathologies in whom treatment is difficult, the expectations of surgery should be set accordingly.

LEVEL OF EVIDENCE

Level IV, therapeutic study, case series.

Hip Joint Capsular Anatomy, Mechanics, and Surgical Management

➤Hip joint capsular ligaments (iliofemoral, ischiofemoral, and pubofemoral) play a predominant role in functional mobility and joint stability. ➤The zona orbicularis resists joint distraction (during neutral positions), and its aperture mechanism stabilizes the hip from adverse edge-loading (during extreme hip flexion-extension). ➤To preserve joint function and stability, it is important to minimize capsulotomy size and avoid disrupting the zona orbicularis, preserve the femoral head size and neck length, and only repair when or as necessary without altering capsular tensions. ➤It is not fully understood what the role of capsular tightness is in patients who have cam femoroacetabular impingement and if partial capsular release could be beneficial and/or therapeutic. ➤During arthroplasty surgery, a femoral head implant that is nearly equivalent to the native head size with an optimal neck-length offset can optimize capsular tension and decrease dislocation risk where an intact posterior hip capsule plays a critical role in maintaining hip stability.

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.

CLINICAL RELEVANCE of the LIGAMENTUM TERES: A LITERATURE REVIEW

Background

The ligamentum teres (LT) continues to be a structure of debate and interest. Previously thought of as a vestigial structure, an awareness of LT pathology and its potential importance has increased with the expansion of hip arthroscopy.

Purpose

To provide a comprehensive literature synthesis on the LT and provide clinicians with the most current research regarding the LT and its anatomical features, functional relevance, prevalence of injury, risk factors for injury, clinical presentation, and treatment for pathology.

Methods

A systematic literature search was conducted using Medline/PubMed, CINAHL/EBSCO, and Cochrane/Wiley databases/platforms using the following search terms: ligament, ligament teres, hip, femur, femoral head, round ligament.

Results

This search yielded 1284 articles of which 44 met the inclusion/exclusion criteria and contributed to this manuscript. Information on the LT was summarized into the following areas: anatomy, function, injury prevalence, risk factors, mechanism of injury, duration of symptoms, clinical presentation (symptoms, range of motion, functional limitations, special testing), imaging, and treatment.

Conclusions

The results of this review supported the following: 1) the LT has a function in restraining hip rotation range of motion; 2) the prevalence of LT pathology in any given population may be largely dependent on the severity of bony deformity (either femoroacetabular impingement(FAI) or dyplasia) and activity level; 3) older age and acetabular bony deformity (either FAI or dyplasia) are risk factors for generalized LT pathology; 4) unique signs and symptoms are difficult to identify because LT pathology rarely occurs in isolation and is likely the end-stage consequence of other hip pathology; 5) the presence of LT pathology may negatively affect an individual's ability to function; and 6) surgical debridement is recommend for pain relief of partial LT tears with reconstruction possible for complete LT tears when complaints of instability are noted.

Level of Evidence

3.

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 Cliff Sign: A New Radiographic Sign of Hip Instability

Background:

The preoperative diagnosis of hip microinstability is challenging. Although physical examination maneuvers and magnetic resonance imaging findings associated with microinstability have been described, there are limited reports of radiographic features. In patients with microinstability, we observed a high incidence of a steep drop-off on the lateral edge of the femoral head, which we have named the “cliff sign.”

Purpose:

(1) To determine the relationship of the cliff sign and associated measurements with intraoperative microinstability and (2) to determine the interobserver reliability of these measurements.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

A total of 115 consecutive patients who underwent hip arthroscopy were identified. Patients with prior hip surgery, Legg-Calve-Perthes disease, fractures, pigmented villonodular synovitis, or synovial chondromatosis were excluded, resulting in the inclusion of 96 patients in the study. A perfect circle around the femoral head was created on anteroposterior pelvis radiographs. If the lateral femoral head did not completely fill the perfect circle, it was considered a positive cliff sign. Five additional measurements relating to the cliff sign were calculated. The diagnosis of microinstability was made intraoperatively by the (1) amount of traction required to distract the hip, (2) lack of hip reduction after initial traction release following joint venting, or (3) intraoperative findings consistent with hip microinstability. Continuous variables were analyzed through use of unpaired t tests and discrete variables with Fisher exact tests. Interobserver reliability (n = 3) was determined for each measurement.

Results:

Overall, 89% (39/44) of patients with microinstability had a cliff sign, compared with 27% of patients (14/52) without instability (P < .0001). Conversely, 74% of patients with a cliff sign had microinstability, while only 12% of patients without a cliff sign had instability (P < .0001). In women younger than 32 years with a cliff sign, 100% (20/20) were diagnosed with instability. No differences were found in any of the 5 additional measurements. Excellent interobserver reliability was found for the presence of a cliff sign and the cliff angle measurement.

Conclusion:

We have identified a radiographic finding, the cliff sign, that is associated with the intraoperative diagnosis of hip microinstability and has excellent interobserver reliability. Results showed that 100% of young women with a cliff sign had intraoperative microinstability. The cliff sign may be useful in the preoperative diagnosis of hip microinstability.

Current concepts in revision hip arthroscopy

Hip arthroscopy is an evolving procedure and its indications have expanded. The number of patients undergoing this procedure has increased significantly as well as the number of surgeons being trained. This has resulted in a notable increase in post-operative complication rates creating the need to develop advanced hip arthroscopic techniques. Revision hip arthroscopy is often complex and many factors should be considered to achieve a satisfactory clinical outcome. Careful pre-operative planning and agreement of expectations between the physician and patient regarding the procedure are important. This review describes several advanced treatment options that are used mainly in revision or complex primary hip arthroscopy cases. Labral reconstruction or augmentation technique is used in cases of severely deficient acetabular labral tissue to restore the fluid seal mechanism. In cases of symptomatic (often post-operative) adhesion formation, a spacer between the labrum and the joint capsule is useful for pain relief and prevention of future adhesions. Large defects of the capsule due to previous unrepaired capsulotomy or any other cause can be addressed with the capsular reconstruction technique. Ligamentum teres reconstruction using an anterior tibialis allograft is indicated in patients with hip instability and persistent pain after previous debridement or with complete tears of this structure. The senior author's treatment of choice in cases of previous over-resection of CAM impingement is the remplissage technique to restore the bony defect of the femoral head-neck junction and preserve the joint seal.

Arthroscopy After Traumatic Hip Dislocation: A Systematic Review of Intra-articular Findings, Correlation With Magnetic Resonance Imaging and Computed Tomography, Treatments, and Outcomes

PURPOSE

To describe the literature concerning patient demographic characteristics and intra-articular injury seen at arthroscopy after traumatic hip dislocation, describe the reported computed tomography (CT) and magnetic resonance findings with arthroscopic correlation, and describe the reported arthroscopic treatments performed with complications and outcomes.

METHODS

A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines for assessment of arthroscopy after hip dislocation. Three databases were searched, and study screening and data abstraction were performed in duplicate.

RESULTS

Thirty-one heterogeneous case series and case reports were included in the analysis from the initial search yielding 780 results, including reports of 151 patients who underwent arthroscopy after traumatic hip dislocation. A wide spectrum of intra-articular injury was reported, with a high prevalence of labral tears, intra-articular bodies, ligamentum teres injuries, and chondral damage. CT had a sensitivity of 87.3% for detecting intra-articular fragments; however, 43.3% of patients who had a preoperative CT scan with negative findings for intra-articular fragments did show fragments at arthroscopy. Magnetic resonance had a sensitivity of 95.0% for detecting labral tears. There were no major complications directly attributed to arthroscopic surgery. A total of 75 of 151 patients were followed up for a median of 2 years after surgery, with osteoarthritis reported in 4.0% and avascular necrosis in 2.7%.

CONCLUSIONS

In patients with traumatic hip dislocation, heterogeneously reported previously published cases show that arthroscopy reveals a broad spectrum of intra-articular damage amenable to arthroscopic intervention. CT is not sensitive in the detection of intra-articular bodies in all cases. Although no serious periprocedural adverse events were reported, only 49.7% of patients had reported follow-up data, and further prospective studies would be necessary to show the safety and efficacy of arthroscopy in comparison with conventional treatment algorithms of hip dislocation.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Editorial Commentary: Arthroscopic Hip Ligamentum Teres Reconstruction-Reality or Mythology?

The ligamentum teres (LT) is perceived to contribute to hip stability and proprioception. LT incompetence can lead to pain and instability, which may play a role in chondral damage. Hip arthroscopy plays a role in diagnosing and treating LT tears. Reconstruction of the LT is feasible, but careful attention needs to be paid to tunnel positioning, graft material, graft length, and fixation methods. An anatomic femoral tunnel should exit at the fovea capitis on the femoral side, whereas the location for safe placement of the acetabular attachment is thought to be in the posteroinferior part of the cotyloid fossa. On the basis of a recent study, optimization of the acetabular tunnel can potentially be achieved by drilling from the femoral tunnel aided by 15° of abduction and 15° of internal rotation. The femoral neck-shaft angle and femoral anteversion must be factored in while planning the entry point of the femoral tunnel, and this may vary based on the amount of femoral head distraction during hip arthroscopy.

The role of the ligamentum teres in the adult hip: redundant or relevant? A review

The ligamentum teres (LT) has traditionally been described as a redundant structure with no contribution to hip biomechanics or function. There has been renewed interest in the LT as a source of hip pathology due to the high prevalence of LT pathology observed at the time of hip arthroscopy. The LT acts a secondary stabilizer to supplement the work of the capsular ligaments and works in a sling-like manner to prevent subluxation of the hip at the extremes of motion. The presence of free nerve endings within the LT indicates a definite role in pain generation, with the LT undergoing various mechanical and histological adaptations to hip pathology.

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.

A Technique for Arthroscopic-Assisted Ligamentum Teres Augmentation Using a Suture Tape Augmentation

Ligamentum teres (LT) tears are a pathologic condition being identified at increasing frequency because of growing use of hip arthroscopy. The exact role of the LT is not well understood, but it has been shown in recent biomechanical studies to contribute to hip stability. Patients with hip pain, instability, and/or mechanical symptoms with advanced imaging findings showing LT pathology may benefit from an LT augmentation. We present an arthroscopic-assisted LT augmentation technique, which can be performed as an isolated procedure or in conjunction with an arthroscopic labral repair and/or debridement, chondroplasty, and femoroplasty.

A novel and simple classification for ligamentum teres pathology based on joint hypermobility

Ligamentum teres (LT) pathology (including synovitis, partial and complete tears) is common at the time of hip arthroscopy with a reported prevalence of 51–90%. Currently, there are four published classifications of LT injuries and tears. The majority focuses on differentiating partial from full thickness tears, whereas a more recently published classification also incorporates the presumed underlying mechanism of pathology. A recent review of the current classification systems found that all are deficient for lack of inclusion of what constitutes a normal ligament, lack of inclusion of synovitis as a source of pathology and lack of inclusion of hypermobility as part of the treatment algorithm. Also, the two most commonly used classification systems have only fair inter-observer reliability. Recent work has found that underlying joint hypermobility plays an important role in LT pathology and that the addition of capsular plication/suture at the time of surgery for LT pathology improves outcomes and reduces re-tear rates. In order to address these problems which have been identified with the currently available classification systems, we propose a novel and simple classification for LT pathology based on underlying joint hypermobility [as assessed by the Beighton test score (BTS)]. LT pathology is used to divide all patients into four types: 0 normal (which includes minor fraying), 1 synovitis (which would also include minor fraying), 2 partial tear and 3 complete tear. Further, all types are subdivided into two groups: Group A patients have no clinical evidence of joint hypermobility (BTS < 3), whereas Group B patients do have clinical evidence of joint hypermobility (BTS ≥ 4). On the basis of this classification system and the available literature, we have also developed a treatment algorithm for LT pathology.

Do Ligamentum Teres Tears Portend Inferior Outcomes in Patients With Borderline Dysplasia Undergoing Hip Arthroscopic Surgery? A Match-Controlled Study With a Minimum 2-Year Follow-up

BACKGROUND

Arthroscopic surgery in borderline dysplastic hips remains controversial, but the role of the ligamentum teres (LT) has not been studied in this setting.

HYPOTHESIS

Borderline dysplastic patients with LT tears have worse short-term outcomes than those without LT tears.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data were prospectively collected on patients who underwent arthroscopic surgery between February 2008 and April 2014. The inclusion criteria were borderline dysplasia (lateral center-edge angle [LCEA], 18°-25°) and labral tears; arthroscopic treatments including labral preservation and capsular plication; and preoperative patient-reported outcome scores including the modified Harris Hip Score (mHHS), Non-Arthritic Hip Score (NAHS), Hip Outcome Score-Sport-Specific Subscale, and visual analog scale for pain. Patients were excluded for preoperative Tönnis osteoarthritis grade >0, workers' compensation claims, previous ipsilateral hip surgery and conditions, or frank dysplasia (LCEA <18°). Patients with LT tears were pair-matched to patients without tears for sex, age at surgery ±10 years, body mass index (<30 kg/m² vs ≥30 kg/m²), labral treatment type, and microfracture.

RESULTS

Of 68 eligible patients, 63 (93%) had a minimum 2-year follow-up, and 30 (48%) had LT tears. Twenty patients in each group were pair-matched. The mean follow-up time was 54.3 months (range, 24.2-83.8 months) for the LT tear group and 38.6 months (range, 24.6-70.6 months) for the control group ( P = .002). Ninety percent were female. There were no significant differences regarding demographics or intra-operative procedures. The LT tear group trended toward lower postoperative mHHS ( P = .09) and NAHS ( P = .09) values. Mean satisfaction was 8.1 for the LT tear group and 7.9 for the control group. Preoperative and follow-up scores were not significantly different between the groups. The LT tear group had 5 revisions, with 1 revision in the control group. Three patients (15%) in the LT tear group underwent total hip arthroplasty (THA); no patients in the control group required THA.

CONCLUSION

In borderline dysplastic patients undergoing hip arthroscopic surgery with labral treatment and capsular plication, LT tears may indicate advanced instability and portend slightly inferior outcomes when compared with a match-controlled group. Borderline dysplastic patients with LT tears may have increased propensities toward revision arthroscopic surgery and conversion to THA. LT tears in these patients may warrant consideration for additional procedures including periacetabular osteotomy and LT reconstruction.

Ligamentum teres tendinopathy and tears

BACKGROUND

The ligamentum teres (LT) consists of two bands that originate on the ischial and pubic sides of the acetabular notch and insert on the fovea capitis of the femoral head. Recent studies have established the LT as an important hip stabilizer in a squatting position, particularly in patients with osseous instability.

PURPOSE

This review aims to concisely present the literature on LT tendinopathy and tears in order to guide health care professionals in the appropriate diagnosis and treatment of these disorders.

METHODS

We reviewed the literature on the diagnosis and surgical management of ligamentum teres tendinopathy and tears.

CONCLUSIONS

The ligamentum teres is an important stabilizer to the hip joint, particularly with hip flexion and external rotation. Older age and acetabular bony pathomorphology are two of the known risk factors for LT tears. Symptoms of LT tendinopathy are largely non-specific, mimicking a wide range of other hip disorders including impingement and instability. Debridement of LT tears or reactive tissue has been reported with good outcomes, with more recent studies describing reconstruction of a completely torn, nonfunctional, or absent LT using various graft sources including synthetic grafts, autografts, and allografts.

LEVEL OF EVIDENCE

II.

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.

Microinstability of the hip: A review

With the development of conservative hip surgery techniques, new entities such as microinstability have been identified. Microinstability is a painful supra-physiological mobility of the hip. It results from the association of architectural and functional abnormalities impairing joint stability. These risk factors concern hip joint bone architecture or peri-articular soft tissues. Bone abnormalities are identified on hip assessment parameters. Soft tissues also play a key role in the static and dynamic stability of the hip: the joint capsule, labrum, ligamentum teres and adjacent myotendinous structures affect joint coaptation; any abnormality or iatrogenic lesion concerning these structures may constitute a risk factor for microinstability. Diagnosis is based on interview, clinical examination and imaging. Findings of labral lesions or femoro-acetabular impingement do not rule out microinstability; they may be associated. Treatment is based first on physiotherapy for muscle reinforcement to improve joint coaptation. In case of failure, arthroscopic surgery is indicated for femoro-acetabular impingement and capsular plicature which is being evaluated. Periacetabular osteotomy or shelf acetabuloplasty may be indicated, according to the severity of joint bone architecture abnormality. Microinstability is a multifactorial entity. Lesions induced by microinstability may in turn become risk factors for aggravation. Diagnosis and indications for surgery are thus difficult to establish. Only full clinical examination and exhaustive imaging assessment allow microinstability and associated lesions to be identified.