Sometimes an expensive, painful test is not the answer to accurate diagnosis, and the art of a hands-on physical examination is the answer!
Hip pain affects a large percentage of young, otherwise healthy athletes. Intra-articular (labral) hip pathology is a painful health problem occurring across age, race and ethnic boundaries, affecting 22-55% of athletes with mechanical hip pain. Hip labral pathology is often misdiagnosed, or not diagnosed, leading to significant delays in treatment. In an attempt to improve time to diagnose, in 2003 the Myrick THIRD (The Hip Internal Rotation with Distraction) test was discovered, named, integrated for use in clinical practice. The art of hands-on physical examination discovered a new way to diagnose patients with hip labral tears. Literature called for improvement in hip physical examination techniques. The inclusion of THIRD sought to improve diagnosis and establish treatment plans for patients evaluated for hip pain.
The labrum of the hip is a rim of soft cartilage, similar to the meniscus in the knee. This cartilage surrounds the hip socket, adding stability and protecting the joint surfaces. It is reported that current clinical assessment is able to accurately determine the existence of intra-articular pathology, but poor at determining the source. Hence, there were calls for improvement in the clinical examination techniques for the hip. Until the Myrick THIRD test, no physical examination technique demonstrated high specificity and high sensitivity for detecting this pathology.
Differential diagnosis involving hip pain is extensive, the diagnosis of the specific pathology often difficult. Differentials can include labral tears, chondral defects, impingement, sacroiliitis, stress fractures, lumbar spine issues, and synovitis. Intra-articular pathology, specifically labral hip pathology, is a painful health problem occurring across age, race, and ethnic boundaries and affecting up to 55% of athletes with mechanical hip pain. Females are affected more than males.
Labral tears are commonly screened for with a history and physical examination. The history includes the mechanism of injury if known, and the patient’s activity status and level. The physical examination typically consists of a range of motion, muscle strength testing, and x-ray evaluation with radiographs. If a hip labral tear is suspected, the current standard of care is to send the patient for Magnetic Resonance Imagery (MRI) with an intraarticular joint injection with a dye known as Magnetic Resonance Arthrogram (MRA). Not only is this a painful procedure, but there is also a risk of an allergic reaction to the dye, and exposure of radiation due to the use of fluoroscopy (moving x-ray). MRA is also costly and has a high false-positive rate.
THRID is performed with the patient in a supine position, initially flexing the hip to 90 degrees and slightly adducting approximately 10 degrees. The hip is then internally rotated while applying downward compressive pressure to the joint. The same maneuver is performed again with a slight distraction of the hip. A positive test is defined as a patient experiencing pain with compression and internal rotation, followed by reduced or absent pain with distraction and internal rotation.
THIRD has shown promising results as a diagnostic tool. The intra-articular pathology that occurs during testing that results in the patient feeling pain is the torn labrum being compressed by the femoral head against the acetabulum with flexion to 90 degrees and downward pressure applied. Rotation of the hip internally with downward pressure places a sheer force on the labrum and causes discomfort if pathology is present. Distraction of the hip lifts the femoral head away from the labrum, eliminating the cause of this pain. The labrum is better isolated with this test, as opposed to other hip examination techniques in which the discomfort may be coming from other sources.
Two previous studies have been completed and published on Myrick THIRD test (Myrick, 2013 and Myrick 2016). These studies explored the THIRD test and compared it to MRA and hip arthroscopy. In 2011, after IRB approval was obtained, a retrospective chart review was performed from 2006 to 2011. Hip arthroscopy patients were identified, and charts reviewed to determine which had a physical examination, including a documented THIRD test, and Magnetic Resonance Imagery with Arthrogram (MRA). Patients with suspected labral pathology were sent for MRA. The findings of THIRD test, the reading of the MRA by the radiologist, and the findings at the time of arthroscopy were recorded. Subjects were male and female aged 10-40. Operative reports, MRA reports, and THIRD test documentation that used the terminology “findings consistent with a positive or negative hip labral tear” were included. This study was published in 2013 (Myrick and Nissen, 2013). The results were that the correlation between MRA and arthroscopy was nil, r (98) = 0.00 P<.05. In contrast, the correlation between THIRD and arthroscopy was significant r (98) = .66, P<.001. THIRD had a 95% correlation with MRA and 100% correlation with arthroscopic findings, indicating substantial agreement between THIRD and arthroscopy and slight agreement between MRA and arthroscopy. The correlation between MRA and arthroscopy is exactly 0, (1, N= 100) (P<.05), indicating that MRA has a predictive value that is equal to a random guess. In contrast, the correlation between THIRD and arthroscopy is .66 (1 N=100) (42.98, P <.001) indicating that THIRD is a significant predictor of hip tears as diagnosed by arthroscopy.
THIRD outperforms MRA on all measures. The true test of THIRD test and MRA as diagnostic instruments is in how well they were able to identify negative cases. MRA identified 25 negative cases, but only 1 was actually negative based on arthroscopy. The accuracy of identifying negative cases (negative predictive value) was only 4% for MRA. In contrast, THIRD identified 5 negative cases, and 3 were negative based on arthroscopy. The accuracy of identifying negative cases (negative predictive value) was 60% for THIRD, which was 15 times higher than MRA.
In 2012-2013, a multicentered study was performed where certified athletic trainers from 3 different settings were extensively trained and validated. The athletic trainers maintained a record of subjects who presented with hip pain, documenting the findings of THIRD test on physical examination. The athletes shared their MRA study and operative reports with the principal investigator. Agreement between THIRD and MRA to arthroscopic findings were compared, calculations of false positive rates were performed, and internal and external reliability were evaluated. The results demonstrated that of the 43 subjects enrolled, all subjects with reported positive THIRD test results also demonstrated positive arthroscopic findings of hip labral tear. MRA was negative in 4 of the 43 cases. Both internal and external validity were demonstrated. The false rate for THIRD was 0% compared to MRA which was 9%, and this difference was statistically significant (p-.014). This study was published in 2014 (Myrick and Feinn, 2014). The physical exam technique is also published in 2 textbooks, released in 2016 and 2019 (Myrick 2016 and Myrick and Karosas 2019). THIRD has also been presented over 3 dozen times in invited and peer-reviewed presentations nationally and internationally since 2013.
In 2019 a study was presented at the American Orthopedic Society for Sports Medicine (AOSSM) annual meeting titled: Sensitivity of Magnetic Resonance Imagery for Acetabular Labral Pathology in Adolescent and Young Adult Athletes. (Kelly, et al, 2019). This work used Magnetic Resonance Imagery (MRI) without the injection of dye prior to the MRI. Again, an MRA is the gold standard for labral pathology. We will compare both MRI and MRA in our study. Some patient’s will have only MRI completed if they have an allergy to dye, or if the referring provider already requested a study and ordered MRI instead of MRA.
THIRD test has been used and documented in patient charts at Connecticut Children’s for 13 years in orthopedics and sports medicine. In an effort to advance the science, and with the latest presentation at AOSSM, this is a prime time to review the efficacy of THIRD with relationship to MRI and MRA for hip acetabular labral pathology. Given the current knowledge on this subject, and the current care imperative to reduce costs while maintaining quality of health care delivery, evidence that THIRD can reduce the number of both MRI and MRA procedures represents a significant contribution to the literature and patient care.
The motivation to advance the work is multifactorial but includes continuing to assess the technique, adding to the power of previous work with significant amounts of additional data. The researchers plan to apply for funding from the National Association of Orthopedic Nurses (NAON) in 2020 to advance the work. This study will add significantly to the background for that work. One of the co-investigators was awarded the Donahoo Dimon Lectureship for the NAON conference in May 2020 to discuss the topic of THIRD.