Iowa State University Capstones, Theses and Creative Components Dissertations

Spring 2021

Acetabular Labral Pathologies and Interventions in Relation to Hip Joint Abnormalities

Natalie Perez

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Recommended Citation Perez, Natalie, "Acetabular Labral Pathologies and Interventions in Relation to Hip Joint Abnormalities" (2021). Creative Components. 781. https://lib.dr.iastate.edu/creativecomponents/781

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Acetabular Labral Pathologies and Interventions in Relation to Hip Joint Abnormalities

Natalie Perez Creative Component Iowa State University – One-year BMS program

Abstract: The hip joint is pivotal for the basis of movement of the lower extremities. However, with increased movement often comes increased risk for injury. One of the most common injuries seen within the hip joint is damage to the acetabular labrum. There are various hip abnormalities that can attribute to these pathologies, but as knowledge of the labrum advances, these pathologies are becoming more commonly seen in athletes who have and isolated traumatic event or repetitive microtraumas to the hip joint seen in movements such as excessive pivoting and hyperextension of the hip. While the pain alone from a labral tear is enough for an individual to seek treatment, labral pathologies that are left untreated are also believed to contribute to the progression of early onset osteoarthritis of the hip joint. As labral pathologies are becoming more abundant in the world of sports medicine, the interventions also continue to evolve to better treat the pathologies.

Introduction Whether it’s stepping out for a big race, running down the field to defend the ball, stepping up to the mound to pitch, or adjusting the body for the perfect pirouette, the hip is the foundation for movement of the lower body. The hip joint is often referred to as a

2 ball and socket joint surrounded by powerful, well-balanced muscles that allow for a wide range of motion while also keeping the lower half of the body stable (1). This wide range of motion, while great for movement, is also the basis for much of the injury that occurs in the lower extremities. The purpose of this review is to look specifically at the acetabular labral ligament and the pathologies that occur due to hip joint abnormalities that hinder one’s ability to compete at the level they once had and effects the ability to perform everyday tasks. The head of the femur makes up the ball portion of the joint, while the cup- shaped acetabulum of the pelvis constitutes the socket. While it is most often referred to as a ball and socket joint, it is better anatomically categorized as a diarthrodial joint meaning it contains a joint cavity, articular cartilage covering joint surfaces, synovial membranes, and is surrounded by a ligamentous capsule (1). Due to the joints unique anatomical structure, diagnostic challenges arise with diagnosing pathological conditions, yet one of the increasingly common pathologies that is being seen more regularly, particularly in athletes, is tears within the acetabular labrum (1-5), and these pathologies are the basis of this review. Within the hip joint, there are various ligaments that aid in the stability of the hip joint while allowing for a wide range of motion. These ligaments can be seen in Figure 1. While tears in the acetabular labrum were previously thought to be uncommon, they are now becoming diagnosed with increasing frequency due to improvements in MRI and arthroscopic surgical techniques (4, 5). While some studies suggest that labral abnormalities are a natural part of the aging process, other studies connect labral tears with joint pathology and pain (3). In a study conducted, it was reported that 93% of cadavers studied (average age of 78 years old) has at least one labral lesion (2). In comparison, a similar study looking at acetabular labral pathologies in a young (average age of 26) asymptomatic population, 38.6% were found to have labral tears (4). In 2009, the prevalence of labral tears in patients with hip or groin pain was reported to be 22- 55% (3), and in 2015, 90% of 300 hip arthroscopic cases were associated with labral tears (15).

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Figure 1. Anatomical features of hip joint. Adapted from orthoinfo.aaos.org/en/diseases-- conditions/femoroacetabular-impingement/ (10)

While interventions of acetabular labral tears have been seen as a controversial topic as the lack of vascularization within the labrum makes one question the ligaments healing abilities, today, treatment is more commonly being sought after as the labrum serves as shock absorber, joint lubricator, pressure distributor, and aids in the overall stability of the hip joint (4, 15). As seen in Figure 2, the acetabular labrum is a ligament that encompasses the outer ridge of the acetabulum with thinner portions in the anterior region and thicker in the posterior region (3). The ligaments circular shape is completed at the inferior portion by the transverse acetabular ligament (2, 3). Due to its all- encompassing shape, the labrum resists lateral and vertical motion of the femoral head and deepens the hip joint by 21%, while increasing the surface area of the acetabulum by 28%. The anterior and superior aspects of the labrum are thought to be the most innervated portions, consisting of free nerve endings and sensory nerve end organs which produce pain, pressure, and deep sensation (3). The vascular supply is provided by the obturator, superior gluteal and inferior gluteal arteries, however, blood supply is believed to be mostly peripheral with the outer one-third of the acetabular labrum being vascular, while the remaining majority is avascular (1,2, 3). Consisting of both fibrocartilage and dense connective tissue that attaches to the bony rim of the

4 acetabulum, the labrum is most often seen as a triangular shape, yet other variants such as round, irregular, and flattened have been noted in individuals with hip pain (3).

Figure 2. Animation of acetabular labrum within the acetabulum of pelvis. Adapted from Lewis and Sahrmann (2006).

Etiology Historically, acetabular labral pathologies were associated with structural abnormalities of the hip or high impact trauma, however, it is now proposed that there are at least five etiologies of labral tears: trauma, capsular laxity, dysplasia, degeneration, and femoroacetabular impingement. (1, 3, 14, 15). While labral injury can often occur due to an isolated traumatic event, it is more commonly associated with a gradual onset due to repetitive microtrauma due to repetitive forces into the connective tissue of the hip joint (5, 6). Isolated types of trauma are often seen in athletes with hip dislocations and acetabular fractures as this increases the susceptibility for hip labral tears (7). These individuals tend to have labral lesions in the posterior region of the labra, yet the magnitude of force will be the true determinant of whether the tear is initiated on the articular or acetabular side of the hip joint (7). Studies have shown that the hip hyperextension inherent in the stance of running leads to subtle instability and

5 increasing stress at the cartilage-labral junction (6). As this motion is repetitively performed during certain athletic activities the pattern of repeated hip hyperextension has been implicated as a mechanism of a torn labrum (6). Additionally, athletic activities that involve repetitive pivoting motions on a loaded femur, and excessive external rotation such as in soccer, hockey, golf, and ballet, have been associated with labral abnormalities as the repetitive motion causes microtrauma (3, 7). Capsular laxity or hypermobility of the hip has also been identified as a source of labral pathologies as excessive repetitive rotation places increased stress on the capsular tissue resulting in hip instability and increased pressure on the anterior superior labrum (4). Similarly, as seen in Figure 3, hip dysplasia results in inadequate containment of the femoral head within the acetabulum and often results in decreased joint surface area which causes increased stress on the acetabulum and labrum (2, 7). Pathologies of the acetabular labra due to dysplasia most often occur anteriorly but there have been studies linking posterior tears to hip dysplasia as well (7).

Figure 3. Adapted from Lewis and Sahrmann (2006). Frontal views of a normal hip (left) and a dysplastic hip (right). 1. Center-edge angle or angle of Wiberg. Normally 30° to 40°, this angle represents the degree of femoral head coverage in the frontal plane. An angle of less than 30° is a characteristic sign of hip dysplasia. 2. Angle of inclination. This angle, between the femoral neck and the shaft of the femur, is normally 125°. In hips with dysplasia, it is most commonly increased but can also be decreased. 3. Head offset. This offset represents the perpendicular distance between the femoral head and the shaft. This distance often is decreased with dysplasia.

Acetabular labral pathologies may also be associated with other intraarticular disorders such as degenerative diseases. Degenerative tears are seen with erosive

6 changes in the acetabulum, femoral head or both due to diseases such as Legg-Clave Perthes diseases, chronic slipped capital femoral epiphysis, femoral head anteversion, coxa vara, and extreme cases of coxa valga (2, 5, 7). Nevertheless, one of the most investigated sources of hip pain and labral tears is associated with femoroacetabular impingement (FAI) as FAI leads to limited hip range of motion. (3-9). FAI occurs due to femoral and/or acetabular abnormal morphologies leading to excess contact between the femoral head-neck junction and the acetabular rim (3, 5, 7, 14). Femoral abnormalities lead to cam-type impingement while abnormal acetabular morphology causes pincer type impingement as seen in Figure 4 (5, 14). Many individuals have a combination of both types of impingement in which case the FAI is diagnosed as a mixed. Having only one, cam or pincer impingements, is not unheard of but is far less common (8).

Figure 4. Comparison of a normal hip to hip joint with cam and pincer type FAI’s and the combined effects of both FAI types. Adapted from https://www.cnos.net/resources/femoroacetabular-impingement- fai (13).

Both forms of FAI have been found to result in different patterns of articular cartilage damage (5, 14). Cam impingements have been found to cause damage to the anterosuperior acetabular cartilage, yet the labrum in most cases remains untouched (3). However, repetitive compression due to repeated movements leads to new formation in the anterior and superior portions of the femoral neck, further enhancing compression and reducing the head-neck angle leading to further complications (8, 11).

7 In pincer impingements, the acetabular labrum is crushed between the acetabular rim and the femoral neck, causing degeneration and bony apposition of the adjacent rim (3). FAI is often diagnosed through the use of the angle of the head and neck of the femur as it enters the acetabulum, better known as the alpha angle and can be seen in Figure 5 (8, 11). An alpha angle greater than 55-60° has been linked to cam type FAI as studies show that the increasing angle causes increased damage to the hip cartilage and labrum (5, 8, 11).

Figure 5. Alpha angle of a normal spherical femoral head as it enters the acetabulum (A) compared to the alpha angle of a femur indicating cam femoroacetabular impingement (B). Adapted from WE Van Spil, et al. (2015).

In addition, new studies suggest that iliopsoas impingement may be a newly identified cause of labral pathologies. Anatomy of the iliopsoas muscle group, composed of the psoas major and iliacus muscles, can be seen in Figure 6. It is believed that because the tendon of the iliopsoas makes an obtuse angle around the iliopectineal eminence and femoral head, maximal pressure of the psoas tendon occurs over the femoral head and overshadows the iliopectineal eminence during hip extension. This raises the possibility that the pressure and friction exerted on the femoral head and anterior labrum during hip motion may lead to an anterior labral injury (9).

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Figure 6. Anatomy of iliopsoas muscle group composed of the psoas major and the iliacus muscles as they insert onto the lesser trochanter of the femur. Adapted from https://somaticmovementcenter.com/psoas-muscle-release-tight-psoas-muscle/ (12).

Diagnosis More than 90% of patients diagnosed with acetabular labral tears complain of anterior-medial groin pain and thus is often used as the basis for diagnosis (3, 5). For most, pain is exacerbated by walking, pivoting, prolonged sitting, and impact activities such as running, and many patients describe increased pain at night (5). While there are various methods of testing for labral pathologies upon initial exams, there is limited evidence to support that these methods are highly accurate (4). Nevertheless, the scour, flexion, abduction, and external rotation, better known as FABER, and impingement tests are often used in clinic as a foundation before moving towards the next steps of diagnosis (4, 5). The scour test consists of the examiner passively moving the patient’s lower extremity through an arc of motions including hip flexion, extension, adduction, abduction, internal and external rotation while applying a compressive force on to the joint. The FABER test is conducted by the examiner passively positioning the testing limb in the position of hip flexion, abduction, and external rotation and the distance from the knee to the table the patient is laying is compared to that of the unaffected side to examine discrepancies. Lastly, the impingement test requires the examiner to passively move the patient’s lower extremity into a position of hip flexion, adduction, and internal rotation (5). Positive findings in all three of the exams are indicated by decreased motion and pain in the hip and groin area with movement. Upon

9 positive findings within the physical examination, diagnostic imaging is often used to further conclude the diagnosis of acetabular labral pathologies. Computed tomography scans have been identified as unreliable in the detection of labral tears, and MRI’s alone have been shown to have inadequate results for visualizing the acetabular labrum. MRA or magnetic resonance arthrography has been shown to produce the best results as the intraarticular infusion of gadolinium is required to obtain the detail necessary to study the labrum (1, 2, 3, 15). This procedure relies on capsular distension in order to fully outline the labrum with contrast and fill any tears that may be present (3). Positive indications of labral pathologies on an MRA include contrast extending into the labra or acetabular-labra interface, blunted appearance, and displacement from underlying bone (2, 3). Nevertheless, MRA may be less effective in identifying posterior labral tears when compared to the sensitivity of detection of anterior labral tears (7). In this case, a diagnostic-image-guided intra-articular hip injection may also be helpful in the diagnosis (3). Treatment Treatment generally begins conservatively with the reduce of weight bearing on the injured hip, nonsteroidal anti-inflammatory drugs, and physical therapy. While the reduction of weight bearing and NSAID’s have been associated with reduction in overall pain, long term use of these treatments was unsuccessful (3). However, the use of physical therapy has been controversial as studies have concluded that there are no significant benefits of the treatment as the lack of vascularization to the acetabular labrum would prevent the ligament from healing (2, 14). Validity is of question with these experiments however, as patient compliance and patient capabilities need to be taken into account as not all patients follow their treatment plans nor have the capabilities to do so by themselves. Certain researchers believe that manual procedures aimed at restoring range of motion will increase the rate of nutrient flow and will promote the possibility of labral healing (2, 3, 14). These studies believe that appropriate intervention should focus on the reduction of anteriorly directed forces on the hip joint by taking into account the patterns of recruitment of muscles that control hip motion (2, 14). It is believed that this can be done by correcting movement patterns during exercise and by instruction in the avoidance of pivoting motions in which the acetabulum rotates on the

10 femur when under load (2). However as noted above, unless these changes are continued through the patient’s own doing, the pain will often reoccur in patients upon returning to normal activities (2, 3). While multiple studies have discussed the benefits and disadvantages in using physical therapy for treatment after the onset of hip and groin pain, few have discussed the use of these techniques for prophylactic care in athletes. The question arises of possibilities in training proper alignment of the hip joint with the goal of reducing anteriorly directed forces on the hip. Studies discuss the importance of focusing on strengthening muscles that are often inhibited, assessing foot motion, and analyzing gait to be main points of retraining when in physical therapy (2, 14), but possibilities potentially lie within using these interventions in training rather than after the injury has already occurred. For example, it has been found the primary muscles contributing to anterior hip joint force are the gluteus medius, iliacus and, psoas muscles (6). In addressing muscle group activation with the goal of decreasing anterior pelvic tilt to lessen the force on the anterior hip, possibilities potentially lie within the recruitment of muscles which would counteract the forces of the gluteus medius, iliacus and psoas muscles such as the increased activation of the gluteus maximus and hamstring muscles.

Surgical Intervention When conservative treatment is found to be unsuccessful, surgical intervention is often sought after once the source of pain has been specifically located to the intraarticular region of the hip (3, 15, 16). Much like physical therapy, surgery has been a contentious topic as the healing capabilities of the acetabular labrum were still of question due to lack of blood flow to the ligament (2, 3). In the past, the most common repair was done through excision or debridement of the torn labral tissue by arthroscopy through a lateral or modified supine approach (2, 3, 15). The overall goal was to preserve healthy labral tissue in order to maintain the acetabular labrums role as a joint stabilizer (2, 15, 16). This procedure, often referred to as a hip arthroscope, allows for visualization of the related intraarticular structures such as articular cartilage and ligamentum teres which can also be related to hip pain and can be used to aid in further

11 diagnoses (1, 3, 15, 16). Today, labral preserving treatments have evolved to include the repair and the reconstruction of the acetabular labrum (17). The labral repair technique involves the same process of the debridement of torn labral but has since been enhanced with repair of the labrum by placement of bioabsorbable suture anchors in the acetabulum to support stabilization (15-17). Studies show that due to the increased vascularization in the periphery of the labrum, peripheral repairs are the most successful (15). Even more recently, labral reconstruction, which studies have shown to be the most successful treatment, fixes a labral graft around the entire acetabular rim to reconstruct the labrum using a freeze dried or frozen iliotibial band allograft (17). Corrections to fix FAI when necessary were also performed alongside the repairs and reconstruction (17). Without repair of the acetabular labrum, it is believed that the articular cartilage of the acetabulum must withstand significantly increased pressure, and a compromise of this system could lead to early joint deterioration (3). This joint deterioration can also be linked to early onset hip osteoarthritis and is a possible outcome of acetabular labral pathologies that are not corrected (5, 16). However, some researchers have concluded that the removal of the labrum entirely may not increase pressure or load on the acetabulum and thus, has also been seen as a successful method for pain relief (15). This method is uncommon however, as most still believe that the excision of the ligament could predispose the hip to premature osteoarthritis (15,) therefore, the evolution of management of labral tears is assumed to continue to progress from debridement to further repairs (16). In summary, the acetabular labrum is a fundamental component of the ball and socket joint that is the hip as it functions to lubricate the joint, distribute pressure, and aid in stability. As the prevalence in labral pathologies increases, the evolution of surgical treatment also progresses as it is still believed that the labral pathologies may lead to further hip pathologies down the line and thus the need for treatment is of importance. However, while many studies focus on the treatment of labral pathologies, there isn’t much evidence to support prophylactic treatment of labral tears and would pose as an interesting area of research.

12 As the prevalence of labral pathologies continues to increase, it may be of importance to look at how to decrease the prevalence of the injury rather than solely focusing on the treatment and repair of tears in the acetabular labrum. While surgery is a valid and appropriate solution in many cases, it is still causing extra physiological stress to the body as all forms of surgery put the patient at risk for complications not only during surgery, but also further along in the future. These risks could possibly be minimized by approaching labral complications from the side of prophylactic care prior to injury rather than treatment after injury.

Works Cited

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13 6. Lewis, C., Sahrmann, S., & Moran, D. (2010). Effect of hip angle on anterior hip joint force during gait. Gait & posture, 32 4, 603-7 . 7. McCarthy, J., MD, Noble, P., PhD, Aluisio, F., MD, Schuck, M., MD, Wright, J., MD, & Lee, J. (2003). Anatomy, Pathologic Features, and Treatment of Acetabular Labral Tears. Clinical Orthopedics and Related Research, 406, 38-47. doi:10.1097/01/blo.0000043042.84315.17 8. Kultur, T., & Inal, M. (2020). Evaluation of Hip Angles with Magnetic resonance imaging in femoroacetabular impingement syndrome. Journal of Health Sciences Medicine, 3(3), 225-230. doi:10.32322/jhsm.690880 9. Domb, B. G., MD, Schidle, M. K., MD, McArthur, B., MD, Voos, J. E., MD, Magennis, E. M., BA, & Kelly, B. T., MD. (2011). Iliopsoas Impingement: A Newly Identified Cause of Labral Pathology in the Hip. Hospital for Special Surgery, 7, 145-150. doi:10.1007/s11420-011-9198-z 10. “Femoroacetabular Impingement - OrthoInfo - AAOS.” OrthoInfo, American Academy of Orthopaedic Surgeons, orthoinfo.aaos.org/en/diseases-- conditions/femoroacetabular-impingement/. 11. Van Spil, W., Agricola, R., Drossaers-Bakker, K., Weinas, H., & Lafeber, F. (2015). Associations of markers of matrix metabolism, inflammation markers, and adipokines with superior cam deformity of the hip and their relation with future hip osteoarthritis. Osteoarthritis Research Society International, 23, 1897-1905. 12. “Why You Can't Release Your Tight Psoas Muscle with Stretching.” Somatic Movement Center, 24 Feb. 2021, somaticmovementcenter.com/psoas-muscle- release-tight-psoas-muscle/. 13. “Femoroacetabular Impingement (FAI) Diagnosis.” CNOS, PC, 29 Mar. 2020, www.cnos.net/resources/femoroacetabular-impingement-fai. 14. Yazbek, P. M., PT, Ovanessian, V., PT, MS, Martin, R. L., PT, PhD, & Fukuda, T. Y., PT, PhD. (2011). Nonsurgical Treatment of Acetabular Labrum Tears: A Case Series. Journal of Orthopedic and Sports Physical Therapy, 41(5), 346-353. 15. Kelly, B. T., MD, Weiland, D. E., MD, Schnker, M. L., BS, & Philippon, M. J., MD. (2005). Arthroscopic Labral Repair in the Hip: Surgical Technique and Review of the Literature. The Journal of Arthroscopic and Related Surgery, 21(12), 1496- 1504. doi:10.1016/j.artho.2005.08.013 16. Murphy, K. P., MD, Ross, A. E., MD, Javernick, M. A., MD, & Lehman, R. A., Jr., MD. (2006). Repair of the Adult Acetabular Labrum. The Journal of Arthroscopic and Related Surgery, 22(5), 567-570. doi:10.1016/j.arthro.2005.07.033 17. White, B. J., MD, Patterson, J., BS, RN, & Herzog, M. M., MPH. (2018). Bilateral Hip Arthroscopy: Direct Comparison of Primary Acetabular Labral Repair and Primary Acetabular Labral Reconstruction. The Journal of Arthroscopic and Related Surgery, 34(2), 433-440. doi:10.1016/j.arthro.2017.08.240

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