The Ligamentum Teres Test
A Novel and Effective Test in Diagnosing Tears of the Ligamentum Teres
- John O’Donnell, MBBS, FRACS*,
- Kostas Economopoulos, MD†‡,
- Parminder Singh, MBBS, MRCS, FRCS§,
- Daniel Bates, BSc, BMed‖ and
- Michael Pritchard, MBBS, FRACS¶
+Author Affiliations
- ↵† Kostas Economopoulos, MD, The Orthopedic Clinic Association, 2222 East Highland Avenue, #300, Phoenix, AZ 85016 (e-mail: Kecono13@gmail.com).
Abstract
Background: A ligamentum teres (LT) injury is a common finding at the time of hip arthroscopic surgery in patients with chronic groin and hip pain; however, LT tears have been difficult to identify before surgery. There have been no unique features identified on history assessment, physical examination, or imaging that reliably identify injuries of the LT preoperatively.
Purpose: To report a new clinical examination to assess the presence of an LT tear: the LT test.
Study Design: Cohort study (diagnosis); Level of evidence, 2.
Methods: The study consisted of 75 patients undergoing hip arthroscopic surgery for multiple lesions. Each patient was evaluated by 2 independent examiners using the LT test, leading to a total of 150 tests being performed. The LT test is conducted with the hip flexed at 70° and 30° short of full abduction; the hip is then internally and externally rotated to its limits of motion. Pain on either internal or external rotation is consistent with a positive LT test result. Hip arthroscopic surgery was then performed and all intra-articular abnormalities noted. Arthroscopic images were taken of each LT and examined by a third independent examiner who determined the presence or absence of a tear. Clinical examination findings were compared with the arthroscopic findings to determine the sensitivity, specificity, and positive and negative predictive values. In addition, the presence of intra-articular pathological lesions was compared with the test results to determine if there was a correlation between the presence of an intra-articular pathological abnormality and a positive LT test result.
Results: Of the 150 examinations performed, the test result was positive 55% of the time (77 examinations). The sensitivity and specificity of the test were 90% and 85%, respectively. The positive predictive value was 84%, and the negative predictive value was 91%. The presence of an LT tear, pincer lesion, and labral tear that required repair was associated with a positive LT test result. The κ coefficient for interobserver reliability was .80.
Conclusion: The LT test is an effective way of assessing the presence of LT tears with moderate to high interobserver reliability. In addition to an LT tear, the presence of a pincer lesion or labral tear requiring repair are also associated with a positive LT test result.
Keywords:
Hip arthroscopic surgery for patients suffering from common causes of hip and groin pain, including labral tears, femoroacetabular impingement (FAI), and chondral injuries, is now routine. Often, the combination of history assessment, physical examination, and imaging allows the surgeon to make a diagnosis of the underlying pathological lesion before visualizing the joint arthroscopically. However, certain lesions remain difficult to diagnose preoperatively, and the diagnosis can only be made at the time of arthroscopic surgery. One of the most difficult diagnoses to make preoperatively is a ligamentum teres (LT) injury. Tears of the LT are a common cause of chronic groin and thigh pain and have been identified in 8% to 51% of patients undergoing hip arthroscopic surgery.1,3,10Currently, there is no reliable clinical examination or imaging study to identify tears of this ligament.2,8,9 Even with improved techniques, less than 2% of LT tears are diagnosed on preoperative magnetic resonance imaging (MRI) scans.1 Hip arthroscopic surgery remains the gold standard of assessment for the LT.2,4
In the setting of chronic groin pain but a normal-appearing MRI scan, a test that can detect LT tears would be useful. Patients may suffer unnecessarily for months or years because LT tears are not identified on clinical examination or imaging studies. Surgeons may be reluctant to put a patient through the risks of hip arthroscopic surgery without the intent to treat a specific injury identified on preoperative testing. The development of a test designed to identify LT tears would help the surgeon diagnose isolated tears and allow lesions of the LT to be included in preoperative planning.
A test specifically designed to identify LT injuries stemmed from our intraoperative observations of the LT as the hip was taken through its range of motion during hundreds of hip arthroscopic procedures. The LT test aims to place maximal tension on the ligament while the femoral head and neck are placed into a position that avoids bony and soft tissue impingement. Internal and external rotation of the hip in this position place maximal tension on the ligament and elicit pain in the injured LT. The purpose of our study was to assess the accuracy of the LT test to diagnose LT tears. We hypothesized that this new LT test could accurately predict the presence and absence of LT tears before surgery.
Materials and Methods
A prospective cohort study involving 75 consecutive patients treated over a 2-month period was performed. Informed consent was obtained from each patient to participate in the study, and each patient signed a consent form. Patients were included in the study if they had ≥3 months of hip or groin pain and an indication for hip arthroscopic surgery including labral tears, cam or pincer lesions, chondral damage, loose bodies, or groin pain not responding to nonoperative treatment. Exclusion criteria for the study included patients with contralateral hip pain, multiple joint involvement, back or knee pain, fixed flexion deformity of the hip, a cortisone injection to the hip within 3 months before examination, hip scope not requiring visualization of the central compartment, and failure to consent to participate in the study.
The test was conducted by 2 independent examiners, leading to a total of 150 tests performed. The first test was performed during a preoperative outpatient clinic evaluation. The test was repeated on the day of surgery by a second examiner in the preoperative holding area. Both examiners were blinded to the results of radiographic examination at the time of testing.
At arthroscopic surgery, the LT was recorded as the hip was moved through internal and external rotation. The video was assessed for the presence of pathological abnormalities by a third independent examiner who was blinded to the examination and imaging results. The Gray and Villar5 system for LT tears was used to grade each tear. Figure 1 shows arthroscopic images of each type of tear. The grading system includes grade I tears (Figure 1B), which are complete ruptures of the ligament; grade II tears (Figure 1C), which are partial tears; and grade III tears (Figure 1D), which represent degenerative tears. The presence of other intra-articular lesions such as cam lesions, pincer lesions, labral tears, focal chondral injuries, diffuse arthritis, loose bodies, and synovitis was noted. Patient demographics and other risk factors such as generalized ligamentous laxity were also noted.
Figure 1.
(A) Intraoperative view of a normal ligamentum teres (LT). No tear is present, and all fibers are intact. (B) Intraoperative view of a complete tear of the LT (grade I). (C) Partial tear (grade II) and (D) degenerative tear (grade III).
The LT Test
The LT test is performed with the patient in the supine position and the examiner standing next to the patient on the side of the examined hip. The patient’s knee is flexed to 90° and the hip flexed to 70° without tilting the pelvis (Figure 2). From this position, the hip is then abducted as far as the patient will tolerate. The hip is then adducted until it is 30° short of full abduction (Figure 3). The hip is then fully internally and externally rotated until a firm end point is observed by the examiner (Figure 4). Internal and external rotation are performed in a smooth, steady manner. We attempt to avoid causing undue pain in the patient by not pushing them past their pain tolerance. Pain provocation in either internal or external rotation is considered a positive test result. If pain is produced early in internal or external rotation before reaching a firm end point, then the test result is considered to be positive in that direction. The production of pain should be relieved with rotation in the opposite direction and reproducible with rotation in the direction of pain again.
Figure 2.
The ligamentum teres test being performed in the supine position. The knee is flexed at 90° and the hip fully flexed and then extended to 30°. This typically leaves the hip flexed at 70°.
Figure 3.
The hip is abducted fully and then adducted to 30°, which typically leaves the hip at 30° of abduction.
Figure 4.
The leg is then externally (A) and internally (B) rotated. The presence of pain in either of these positions is consistent with a positive test result.
Surgical Procedure
Surgery was performed with the patient in the lateral position with traction. A diagnostic arthroscopic procedure was performed and intra-articular lesions identified including cam and pincer lesions, labral tears, chondral injuries, and LT injuries. Video of the LT was recorded and saved using arthroscopic equipment as the ligament was taken through internal (Figure 5A) and external rotation (Figure 5B), allowing full visualization of the LT. Tears of the LT were treated with a Dyonics EFLEX radiofrequency ablator (Smith & Nephew, London, United Kingdom). The EFLEX was primarily used through the anterior portal. The EFLEX can be bent by the surgeon to allow it to reach all areas of the LT that require debridement. If a specific area of the LT was very difficult to reach from the anterior portal, a posterolateral portal was created to improve access to the entire LT. Partial tears of the LT were debrided down to stable, normal ligament. Care was taken not to disrupt normal-appearing ligament tissue. Other intra-articular lesions such as labral tears and chondral injuries were treated in a standard fashion. Postoperatively, all patients, regardless of their procedure, were allowed full weightbearing. They began physical therapy after the first postoperative visit at 10 to 14 days. Unrestricted activity was allowed at 6 weeks including running.
Figure 5.
Arthroscopic view of the ligamentum teres being evaluated with the hip in (A) internal and (B) external rotation.
Statistical Analysis
Sensitivity, specificity, and positive and negative predictive values were used to assess the ability of the LT test in identifying LT tears. The χ2 test was used to determine if the categorical data affected the results of the LT test. The Mann-Whitney U test was used to determine if numerical data such as height and weight affected the results of the LT test. The κ coefficient was calculated to determine interobserver variation between the 2 independent examiners.
Results
The study consisted of 46 men and 29 women with a mean age of 34.2 years (range, 16-54 years) (Table 1). There was a significantly higher proportion of men than women in the study (P = .01). Of the 75 patients, 35 (46% ) had LT tears confirmed at the time of surgery. There was 1 grade I tear (3%), 20 grade II tears (57%), and 14 grade III tears (40%) (Table 2). The test result was positive in 77 of the 150 examinations performed (55%) (Table 3). The specificity of the test was 85%, and sensitivity was 90%. The positive and negative predictive values were 84% and 91%, respectively (Table 4). Factors associated with a positive LT test result included the presence of an LT tear (P < .001), presence of a pincer lesion (P = .01), and presence of a labral tear requiring repair (P = .01). The presence of a cam lesion or a cartilage injury requiring microfracture was not associated with a positive LT test result (Table 5). In the study, there were 3 isolated LT tears. In these isolated tears, the LT test result was positive in all 3 patients. The κ coefficient for interobserver reliability was .80.
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Table 1
Patient Demographics (N = 75)a
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Table 2
Types of LT Tearsa
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Table 3
Comparison of LT Test Results With Surgical Findingsa
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Table 4
Overall Results of Ligamentum Teres Testa
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Table 5
Intra-articular Pathological Findingsa
Discussion
We present a novel test to identify the presence of LT tears in patients with groin and buttock pain. The test showed a strong ability to identify when LT tears were present, with an overall sensitivity of 90%. The goal of the LT test is to function as a screen for LT tears, and sensitivity establishes a test’s ability to function as a screening tool. An examination with over 90% effectiveness in recognizing the presence of tears is helpful in a setting where no other screening examination exists and current diagnostic examinations miss the injury a majority of the time. We chose to evaluate the test in all patients with hip, groin, or buttock pain, and most had known intra-articular lesions. We expected the specificity to be lower because of the high percentage of associated injuries in the patient population. However, we found the test to have a specificity of 85%. The main reason for this unexpectedly high specificity may be the high prevalence of LT tears found in the study. We did find that in addition to an LT tear, the presence of a pincer lesion and a labral tear requiring repair was significantly associated with a positive LT test result. Although the test attempts to remove signs of impingement, associated pincer impingement and tears of the labrum may cause pain during the examination, leading to a false-positive finding. We found that the presence of a cam lesion and associated focal cartilage injuries, diffuse osteoarthritis of the hip, and synovitis were not associated with a significant increase in false-positive findings. These findings show that the LT test is an effective examination in determining the presence and absence of LT tears even in the setting of other intra-articular injuries. This is very helpful because most LT tears do not occur in isolation. We did have 3 patients with isolated LT tears, and the LT test result was positive in all these patients. The presence of a partial or degenerative tear did not affect the efficacy of the test in identifying LT tears. There was no significant difference in the test identifying LT tears between these 2 groups. One patient in the study had a complete rupture of the LT. The LT test result was found to be negative by both examiners in this patient with a grade I tear. The negative test result in the setting of a complete rupture is understandable because the pain generators in LT tears are the torn LT fibers and the added stress on the intact fibers. With no intact fibers, the pain generator is absent, and the patient does not experience pain during the examination. We also showed good interobserver reliability between the examiners with a κ value of .80. The LT test is relatively simple to perform, and the results are reproducible. The test can also be performed rapidly and easily integrated into a clinician’s hip examination to screen for LT tears.
The ability to visualize the LT arthroscopically has increased awareness of the ligament as a possible source of hip and groin pain, and the development of an LT tear grading system by Gray and Villar5 in 1997 further increased the interest in LT tears. No specific test has been available to accurately make the diagnosis of LT tears. Currently, magnetic resonance arthrography is the best available test to evaluate hips for LT tears.2,4 However, MRI and magnetic resonance arthrography have a poor record of identifying LT tears.1,2,9 The lack of reliable testing was highlighted by Byrd and Jones,2 who in a cohort of 23 LT tears found only 2 of 23 tears before surgery, even with significant advanced radiological studies including 20 noncontrast MRI, 7 contrast MRI, 7 computed tomography, and 3 radionucleotide scans of the hip. Botser et al1 showed that MRI had less than 2% sensitivity in identifying LT tears, while Rao et al9 identified only 4% of LT tears preoperatively using MRI. Diagnosis of an LT tear is difficult even with advanced imaging. We found our test to be robust, even in the setting of associated pathological disorders such as cartilage injuries and synovitis. The development of an effective screening examination to identify LT tears is helpful in evaluating patients with chronic groin pain in which determining the source of their pain is difficult.
The treatment of LT tears with surgical debridement has shown good results in the literature.3,6,9 Improvement in pain and modified Harris hip scores in patients with LT tears who have undergone debridement of the tear has been reported. The prevalence of LT tears ranges in the literature from 8% to 51%.1,3,10 We found an LT tear in 46.7% of our cases in this series. In most studies, LT tears are identified at the time of surgery when other intra-articular disorders are being treated such as labral tears and chondral injuries.2 Patients with an isolated LT tear may suffer months to years with chronic groin pain, but MRI and other diagnostic testing findings will be normal or equivocal. The lack of preoperative findings in these patients creates a dilemma for the surgeon in what approach to take with the patient. A surgeon may hesitate to perform diagnostic hip arthroscopic surgery on a patient with pain but no other objective findings. The LT test offers an objective examination of LT tears, giving the surgeon more confidence in proceeding with surgical intervention for the patient’s hip and groin pain.
The development of the LT test followed our observation of the LT during hip arthroscopic surgery that internal and external rotation of the hip while at 30° to 60° of abduction placed the bundles of the ligament in tension. Biomechanical studies confirmed these findings using string models.7 The study demonstrated that the LT becomes maximally tight at 90° of hip flexion and 90° of external rotation while the capsular ligaments become lax in this position. We took these findings and developed the LT test with the aim of centering the femoral head in the acetabulum while avoiding soft tissue and bony impingement. To perform the test correctly, no bony or soft tissue impingement between the femoral head-neck junction and the acetabular rim should be present. This is achieved by placing the hip in a position that is short of full flexion and full abduction. This position minimizes FAI and accounts for variation in femoral head-neck junctions and acetabular anteversion and retroversion. As the hip is passively moved through a full range of internal and external rotation, further tension is placed on the ligament bundles. The increased tension on the damaged bundles elicits pain and a positive test result. The examination places the hip in a position that attempts to remove as many confounding variables as possible. Unfortunately, the position does not allow us to remove the effects of labral tears and pincer lesions. In the setting of a positive LT test result, the presence of these 2 diagnoses must be closely considered.
The study is limited by our inability to compare the results of the LT test to other tests used to evaluate LT tears because no other tests specific for LT tears exist. Another limitation to the study is the lack of a control group of patients who were without groin or hip pain. However, the only way to confirm the presence or lack of LT tears would be by hip arthroscopic surgery. It would be highly unlikely that a patient without hip or groin pain would agree to a diagnostic hip arthroscopic procedure.
Conclusion
The LT test is a reliable clinical examination to assess the presence of a torn LT. It is useful in aiding the diagnosis of chronic groin pain in patients with an otherwise normal hip MRI scan. Patients with a positive LT test result must be closely examined for the presence of pincer morphological characteristics or a significant labral tear. The LT test is a useful addition to the examination of the painful hip and groin.
Footnotes
- The authors declared that they have no conflicts of interest in the authorship and publication of this contribution.
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