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Review of acetabular labral tears in dancers.

Much research has been performed in the past decade on the hip, including advancements in the diagnosis and treatment of intra-articular hip conditions. Ganz popularized the term FAI, femoracetabular impingement, and described its effect on labral and chondral health. (1) It is now well known that the labrum can be disturbed by stresses applied to the hip joint, either abruptly or repetitively in the form of microtrauma. Athletes, especially those involved in sports such as hockey and American football, have frequently been found to suffer from hip pain and labral pathology. The high prevalence in these sports has lead to increased research and knowledge of proper treatment, rehabilitation, and the long-term consequences of labral injury, including the potential for progression to hip osteoarthritis.

Anatomy of the Labrum: Review

Kelly and colleagues (2) proposed five causes of labral injury: 1. trauma, 2. femoracetabular impingement, 3. capsular laxity/hip hypermobility, 4. dysplasia, and 5. degeneration. To understand how a labral injury can occur under these various conditions, a basic review of the anatomy and function of the labrum is helpful.

The labrum is a ring of fibrocartilaginous and dense connective tissue attached to the bony rim of the acetabular socket, with a tissue structure similar to the meniscus. (3) It is normally triangular in cross-section and thinner anteriorly, which is thought to predispose this area to injury. Its base is attached to the acetabulum and its apex forms a free edge, which is turned in against the femoral head. (4) An embryological study by Cashin and associates (5) found the collagen fibers of the anterior labrum to be arranged parallel to the labral-chondral junction, while the posterior labrum fibers were perpendicular to the junction. This may contribute to the vulnerability of the anterior aspect.

The hip joint receives innervation from the branches of the lumbosacral plexus at L2 to S1, but predominantly from L3. Therefore, pain produced at the hip may refer to the L3 dermatome at the anterior and medial thigh and distally to the level of the knee. (6) The anterior and superior aspects of the labrum are the most innervated portions and contain free nerve endings and sensory nerve end organs that produce pain, pressure, and deep sensation. (7) These structures may also assist with proprioception. (2)

The vascular supply is provided by the obturator, superior gluteal, and inferior gluteal arteries. The outer one-third of the labrum is vascular, but the inner two-thirds may be avascular. Peterson and coworkers (8) have confirmed that blood vessels enter the labrum from the adjacent joint capsule and are greatest at the peripheral one-third. Tears in these regions may have the potential to heal. Other researchers found no areas of avascularity. (7)

Functions of the Labrum

The physiological functions of the labrum have been found to enhance joint stability, preserve joint congruity, and form a sealing mechanism that reduces and distributes joint compressive forces. (2) The labrum resists lateral and vertical motion of the femoral head within the acetabulum. (7) It aids stability by deepening the acetabulum by up to 21% and increases the surface area of the acetabulum by 28%, thus decreasing contact stress and distributing loads on the femoral head and acetabulum. The sealing mechanism produced by an intact labrum maintains synovial fluid within the articular cartilage, and thus could enhance lubrication mechanisms. (7) Loss of the labral seal has been shown to cause instability of the hip in a cadaver. (9) Labral injury causes a 43% to 60% decrease in the amount of traction force required for joint distraction. (4,9)

Recent studies have shown the importance of the labrum in distributing and diminishing load on the hip joint. A study by Ferguson and colleagues (4) found that following removal of the labrum in a model, contact stresses between the femoral and acetabular cartilage layers were increased by up to 92%. It was also found that the creep consolidation rate (the rate at which the femur and acetabulum approach each other in weightbearing) occurred 42% faster without a labrum. Increased load on the hip joint due to loss of the labrum could potentially lead to degenerative damage to the joint over time. Due to this function of the labrum, new surgical techniques have attempted to repair the labrum when possible to potentially decrease the risk of premature arthrosis. (2)

Neumann and associates (10) used MR arthrography to investigate 100 patients with mechanical symptoms of the hip, such as pain, clicking, locking, and giving way, to rule out labral tear and assess cartilage changes in the femoral head and acetabulum. Labral tears were found in 66 patients and cartilage lesions in 76 patients. Correlation of the grade of cartilage abnormality with the grade of labral tear was found to be statistically significant. Eighty-five percent of the patients with labral tears had concomitant cartilage abnormalities. In 54.5% of the cases with acetabular labral tears, cartilage loss was observed in the same region as the labral tear. The grade and size of cartilage abnormality both correlated significantly with the grade of the labral tear. It was concluded that cartilage loss and labral tears are interrelated and may represent important risk factors that can lead to the development of osteoarthritis. These findings need to be considered when making recommendations for the treatment of labral tears in dancers.

Kinematics and the Labrum

As indicated earlier, interest in the acetabular labrum has grown in the medical community, and this has produced substantial kinematic and biomechanical research. Some studies may promote understanding of the role of the labrum in protecting the dancer's hip during dance-specific movement. For example, Crawford and coworkers (9) studied the effects of labral lesions on hip kinematics at the extremes of hip joint motion in cadavers. They found that in hip extension with abduction or external rotation, a common position in ballet, a large strain was placed on the anterior labrum at the acetabular interface where labral lesions commonly occur.

Charbonnier and colleagues (11) studied 11 pairs of female dancers' hips using an optical tracking system to capture motion as the dancers performed six dance movements: left arabesque, left developpe devant, left developpe a la seconde, grand ecart facial, right grand ecart lateral, and grand plie. The resulting computed motions were applied to patient-specific hip joint 3D models based on MR images. While visualizing the dancers' hip joints in motion, abnormal contacts were located between the femur and labrum. The penetration depth of the femoral head into the acetabulum was also computed. To describe the exact location of impingement, the acetabulum was divided into eight sectors (anterior, anterosuperior, superior, posterosuperior, posterior, posteroinferior, inferior, and anteroinferior). These investigators calculated the frequency of impingement and subluxation and computed the penetration depth and amount of subluxation. Finally, they compared their data to magnetic resonance imaging (MRI) findings. The results for each of the dance movements studied were as follows.

In arabesque, no FAI or subluxation was detected, and therefore arabesque was not thought to produce significant stress in the joint. In developpe devant, impingements in the anterior and posterior quadrants were observed for 24% of the dancers' hips. No subluxations were found. Mean penetration depth was 2.5 mm. During developpe a la seconde, impingements were detected in 45% of the dancers' hips. Seventy-eight percent of these contacts were at the superior or posterosuperior quadrant of the acetabular rim. Penetration depths were much greater for developpe a la seconde than in any of the other tested movements, as high as 6.22 mm, and translation distances were great. Subluxations were observed in 25% of the cases and always correlated with an impingement. During grand ecart facial, impingement at the superior or posteriosuperior quadrant was observed in 61% of the dancers' hips. Mean depth of penetration was 3.63 mm. This movement had the highest frequency of subluxation, with 39% of the dancers' hips subluxing, and all subluxations were associated with an impingement. Grand ecart lateral showed the highest frequency of impingement of all movements, with 70% of the dancers' hips showing impingement in the front (flexed) leg. All instances of impingement occurred at the superior or posterosuperior acetabular rim, just as had been found in developpe a la seconde and grand ecart facial. During ecart lateral, the posterior leg held in extension had a frequency of impingement of 22%, and all episodes of impingement were again located in the superior or posterosuperior quadrants. Penetration depth of the posterior leg was relatively low at 1.11 mm. In grand plie, impingements were noted in 44% of the dancers' hips, again in the area of the superior or posterosuperior acetabular rim. Penetration depth was 2.47 mm. Subluxation frequency was 17%, with a mean value of 3.77 mm of translation. Again, all femoracetabular translations were correlated with an impingement.

Based on this research, it appeared that subluxation of the hip occurs frequently during extreme range of motion in dance. This study also demonstrated that all subluxations occurred in conjunction with impingements, and these impingements were located in the superior or posterosuperior quadrant of the acetabulum. This was confirmed on MRI. Four dance movements seemed to produce the most stress on the hip. Grand ecart facial produced the highest frequency of subluxation (39%). The front leg of grand ecart lateral had the highest frequency of femoroacetabular impingement (70%). Developpe a la seconde and grand plie had the highest depth of penetration and the most femoroacetabular translations. These results suggest that to better preserve the hip structures it may be beneficial to limit the number of times a dancer performs these movements during rehearsals and training.

Epidemiology

Due to the rigors of dance and the extreme of ranges of motion required, it is not surprising that many dancers complain of hip pain. (12) The literature has shown an incidence of hip pain in dancers as high as 23.5% (compared to 5% to 6% in the general population). (13) Kocher and associates (14) reported that 50% of dancers seen in their clinic over a 3 year period came for assessment and treatment of hip pain, and that 40% of those dancers were found to have a labral tear. In the general population, the prevalence of labral tears in patients presenting with hip pain has been reported to be 22% to 55%. (7)

References in the literature suggest that many patients with labral tears present with abnormal structure or dysplasia that predisposes them to injury of the labrum. (15) This may not be true in the dancer population, according to a study by Duthon and colleagues. (16) Labral tears were identified with MRI in 18 of 20 professional ballet dancers, and only one was found to have Cam-type morphology. It is interesting to note that only 12 of these dancers complained of pain. Another interesting aspect of this study was that all of the labral lesions were found in the superior aspect or posterosuperior aspect of the labrum. Previous research, done on the general population, has overwhelmingly reported lesions in the anterior or anterosuperior labrum. (10) In the study by Kocher and associates, (14) none of the 30 dancers with labral tears had developmental dysplasia of the hip, acetabular dysplasia, or Cam- or Pincer-type FAI. This seems to support the concept that labral tears of the hip in dancers are more the consequence of overuse than any structural limitations.

The incidence of labral tears in general has been found to increase with age. A cadaveric study of 55 hips, average age 78 years, showed that 96% had labrum tears. (17) On the other hand, the dancers studied by Kocher and associates (14) had a mean age of only 20.1 years, with a range of 14 to 38 years. Thus, in this case, age was not a factor in the high number of labral tears found. It may well be that the labral tears noted in the older population demonstrated deterioration of the labrum as a natural consequence of aging, whereas the high incidence of labral tears in dancers, as already indicated, appears to be due to the extreme compression forces placed on the labrum during dance activities, which accelerate deterioration. (14)

Although the professional ballet dancers examined with MRI in the studies reviewed by Duthon and colleagues (16) did not have hip dysplasia, a large number of the general population do. It may reasonably be assumed that persons with dysplasia would not tolerate the stresses placed on the hips by the training required to become a professional ballet dancer and would "self-select out." Nonetheless, dance instructors and medical professionals need to be aware of the increased incidence of labral tear in the presence of morphological irregularity of the hip in the form of Cam-type and Pincer-type impingement. Students presenting with complaints of pain or difficulty with alignment of the pelvis and hips should be referred to a dance medicine specialist for further evaluation. Recommendations can then be made to accommodate structural differences in the training of the recreational studio dancer.

History of Injury, and Reliability of Physical Examination Findings

In determining if a torn labrum is the source of pain, clinicians should start by listening to the dancer's history. The torn labrum often presents as a deep aching-type pain and is located in the anterior groin in as high as 92% of patients with confirmed labral tears. (18) Night pain has also been a frequent complaint. (19) There is often a delay of 2 years or more in seeking care; with dancers care is often sought only after the pain becomes severe enough that it interferes with participation. (7) About 50% of patients with labral tears also describe mechanical symptoms such as clicking, catching, or giving way. (20)

On average, patients with labral tears visit 3.3 medical professionals over a 2-year period before receiving a definitive diagnosis. (19) If clinicians are going to improve this statistic, reliable clinical tests must be determined. Leibold and coworkers (21) systematically reviewed the literature to determine the validity of frequently used diagnostic physical examination tests and to explore whether a cluster of tests might improve accuracy of diagnosis. Their review found that, based on current best evidence, a negative finding for the flexion-adduction-internal rotation test, the flexion-internal rotation test, the impingement provocation test, the flexion-adduction-axial compression test, the Fitzgerald test, or a combination of these tests provides the clinician with the greatest evidence-based confidence that a hip labral lesion is absent. They determined that none of the research they reviewed indicated that any specific test has sufficient specificity to conclude with confidence that a labral lesion is present. There were problems with methodology in some of the studies. One factor that made comparisons difficult was that the studies did not all use the same gold standard for determining the existence of tears. Some studies used the MRA and others arthroscopy. The studies did not always specify what constituted a positive test result, nor did they specifically describe the tests performed. This could cause errors, as examiners may have performed the tests differently.

For example, when employing the impingement test, some examiners performed internal rotation prior to flexing and adducting the hip, while others reversed that sequence. It is unknown if this variation in testing is clinically significant. The impingement test, also known as the flexion-adduction-internal rotation (FAIR) test was used in seven of the studies reported on by Leibold and coworkers. (21) It is well described by Burnett and colleagues. (19) With the patient supine, the examiner passively flexes the hip to 90[degrees] and adducts and then internally rotates the hip. Pain in the groin region is considered a positive test. The premise of this test is that flexing and adducting the hip in this position puts the femoral head in close approximation with the acetabular rim. Internal rotation of the hip produces a shear force on the labrum. The Fitzgerald test is used to determine if the patient has an anterior or posterior labral tear. To test for an anterior tear, the hip is passively taken into flexion, external rotation, and full abduction, after which it is extended, internally rotated, and adducted. A positive test elicits complaints of pain. To test for posterior tears, the hip is passively taken into full flexion, adduction, and internal rotation, followed by extension, abduction, and external rotation. Production of pain is considered a positive test. Martin and associates (18) performed a study to examine which clinical tests were most frequently used by hip specialists when examining an adult hip. They found that 70% of these specialists utilized the flexion-adduction-internal rotation impingement test. These investigators recommended that a standardized examination protocol for the hip be developed and followed to provide a uniform evaluation process and facilitate future multi-center clinical studies. (18) Without such research, it is difficult to determine which patients with labral tears will benefit most from conservative treatment or surgical management.

Diagnostic Testing

To treat patients with labral tears effectively, the underlying cause of the injury, as well as the condition of the chondral cartilage, must be identified. Diagnostic arthroscopy has been found to be the most definitive means of diagnosing labral tears of the hip and is considered the gold standard to which other means of diagnosis are compared. However, it is expensive and invasive; thus, there continues to be research into the performance of other tests. There is also interest in better diagnosing early degeneration of the hip cartilage and chondral damage, conditions that are frequently found in patients with labral tears. Each available diagnostic technology has its strengths and weaknesses and will be further analyzed.

Radiography

The first radiologic investigation will ideally be plain x-ray. The labrum is not visible, but x-rays are needed to rule out other diagnoses. It has been well documented that approximately 90% of all patients with labral pathology have associated bony abnormalities. (22) Patients with hip pain should undergo antero-posterior (AP) pelvis, lateral, and false-profile views. (23) A standing AP may accentuate evidence of mild dysplasia. In pincer impingement, the femoral neck abuts against a retroverted or deep acetabulum, causing compression of the hip labrum and subluxation of the joint. (24) Pincer lesions can be detected on standardized anteroposterior pelvis x-ray by cross-over, ischial spine, and posterior wall signs for acetabular retroversion. A cross-over sign is positive when the anterior acetabular wall is more lateral than the posterior wall in the proximal acetabulum. Retroversion is determined by calculating the amount of overlap of the anterior acetabular rim. The posterior wall sign is considered positive if the posterior wall of the acetabulum is more medial than the center of the femoral head. This indicates under-coverage at the posterior wall.

In patients with Cam impingement, the femoral head-neck junction is forced into the acetabulum and causes displacement of the labrum, eventual labral tearing, and detachment of the cartilage. X-rays will often show a lack of sphericity of the femoral head. Correction of the anatomical variations may be recommended if return to previous activities is desired. X-ray may also show bony lesions, loose bodies, or moderate to severe degenerative changes. Radiographs cannot detect early chondral degeneration. In a study by Byrd and Jones, (25) radiographs were helpful in differential diagnosis of only 10% of the patients with intra-articular lesions. Other investigators have also reported poor diagnostic value of early degenerative changes in the hip with radiograph. However, given the high prevalence of bony abnormality in the general population, radiographs are still needed to determine if anatomy, combined with a patient's activity, may predispose them to injury.

Magnetic Resonance Imaging

Standard MRI has not been shown to be reliable in the diagnosis of labral tears. When compared to arthroscopy for diagnosis, standard MRI produces both false-positive results and an underestimation of labral pathology. Additionally, it has been reported to have only a 30% sensitivity and a 36% accuracy rate. (26) Standard MRI has also shown a sensitivity of only 22% in detection of cartilage delamination. (27) However, new protocols and high resolution MRI may prove more capable. (23)

Magnetic Resonance Arthrography

Direct magnetic resonance arthrography (MRA) involves injection of the hip joint with diluted gadolinium in saline. It has shown more accuracy in detecting labral tears than standard MRI, with reported sensitivities ranging from 57% to 91%. (25) It therefore has come to be used more commonly than MRI for initial diagnosis. Chan and associates (28) found a sensitivity of 100% and accuracy of 94% for MRA as compared to arthroscopy for the diagnosis of labral tears. They also found MRA to have a sensitivity of 100% and an accuracy of 96% in radial reformatted MRA mapping of the tear location. This information is important, as knowing the exact location of a lesion may be significant during rehabilitation of a dancer. Magnetic resonance arthrography has also recently been reported as having a sensitivity of 79% and a specificity of 77% in the detection of articular cartilage pathology when compared to findings at open hip surgery. (10) A study by Zaragoza and coworkers (29) found the sensitivity of MRA detection of cartilage delamination confirmed at surgery to be 97% and the specificity to be 84%. The positive and negative predictive values of the MRA findings were 90% and 94%, respectively. The presence of cartilage delamination is the early stage of articular cartilage degeneration. Therefore, direct MRA has proven to be an excellent positive predictor in diagnosing acetabular labral tears and articular cartilage abnormalities.

Indirect magnetic resonance arthrography has recently been found by Zlatkin and colleagues (30) to show significant potential in the assessment of labral lesions. With indirect MRA, the patient is given intravenous (IV) gadolinium contrast medium and thus does not require fluoroscopy or an intra-articular injection but still has improved contrast resolution compared to standard MRI. After receiving the IV of gadolinium, the patient is required to exercise for 15 minutes. In the Zlatkin study, 14 patients underwent standard MRI, indirect MRA, and then arthroscopy. The researchers looked at the accuracy of detection of labral tears and also chondral lesions. Thirteen of the 14 patients had labral tears found by arthroscopy. All 13 of these labral tears were identified on indirect MRA (100% accuracy). Of these 13 patients, 11 (85%) also had tears identified on standard MRI. The tears were more prominently visualized when enhanced, however. The extent and character of the lesions found in the gadolinium-enhanced images correlated more closely with those identified by arthroscopy than by standard MRI. Therefore, indirect MRA may be a useful tool in diagnosing labral tears.

Biochemical Imaging

New biochemical imaging technologies are emerging that may lead to detection of changes in the articular cartilage even before labral tear or demyelination occurs. A form of indirect MRA, delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), has demonstrated excellent accuracy in detecting early chondral degeneration. It can detect biochemical changes even before morphologic changes occur by capturing alterations in the cartilage matrix. This may prove useful in screening dancers and athletes when pain first presents, or even sooner for prevention. It may help determine how many hours of exposure are appropriate before subtle changes in chondral surfaces occur. (31) This technology is not yet widely available.

Intra-Articular Injection

Some physicians have advocated the use of intra-articular injection to assist in diagnosis of intra-articular pathology. This may provide useful information when pain persists although MRA was negative. Byrd and Jones reported that a positive response to an intra-articular injection of anesthetic was a 90% reliable indicator of intra-articular abnormality. (32) Philippon and coworkers also advocate use of a lidocaine injection to assist with diagnosis. (33) They report having their athletes perform a series of functional tests before and after injection and comparing the scores on those tests. They found that athletes who scored higher after injection had a very high incidence of intra-articular pathology.

Ultrasound

The diagnostic validity of musculoskeletal ultrasound compared to MRA was investigated by Troelsen and associates. (34) Their study group consisted of 18 patients with a median age of 43 years. Acetabular labral tears were identified in 17 of the 18 hips on MRA. Ultrasound also visualized labral tears in 17 of 18 hips. Of these, 16 were confirmed on MRA. One was false-positive and another was found to be false-negative. Thus, ultrasound in labral tear diagnostics was found to have a sensitivity and positive predictive value of 94%. This study showed higher diagnostic ability than studies previously done on the accuracy of ultrasound of the hip, perhaps indicating that a learning curve exists. Findings were not verified by hip arthroscopy, but these preliminary results are encouraging. As expertise grows in the area of diagnostic musculoskeletal ultrasound of the hip more data will become available.

Treatment Outcomes

One of the difficulties in determining efficacy of treatment for labral tears is that researchers have used different measures to assess outcomes. As the number of labral tears identified and treated increases, a reliable patient-reported outcome (PRO) measure is needed to evaluate efficacy and patient-reported quality of life changes. If this tool is to be used with dancers, it must take into consideration the extremes of range of motion used and the lengthy hours of participation required of this population. Most of the PRO measures previously used for hip patients were developed for and tested on older patients with osteoarthritis. As we increasingly intervene earlier in cases of hip pathology, a PRO instrument for younger, more active, non-arthritic patients is needed. The modified Harris Hip Score (MHHS), (14,35) Hip Outcome Score (HOS), (36) and Non-Arthritic Hip Score (NAHS) (37) have been used to report patient outcomes in the FAI, post-arthroscopy, and hip labral tear populations. An extensive analysis of the HOS was performed by Martin and Phillipon to evaluate its use in labral tear and hip arthroscopy patients. (36) While the HOS involves running, pivoting, and squatting, neither it nor any of the other PRO tools take into account the extreme ranges of motion repetitively required in dance. However, this range of motion is encompassed by a question on the HOS questionnaire regarding the ability to perform activity with normal technique. The HOS also includes a question about the amount of time a patient is able to participate in his or her desired sport.

One study showed the NAHS to be reliable and valid in a younger, nonarthritic population. (38) This PRO tool does include questions on activities of daily living (ADLs) and running, but none that would encompass the extreme motions of the hip in dance. The MHHS is used in many postoperative studies to assess efficacy and patient outcomes. This test was modified from the original Harris Hip Score that was developed for use with patients after total hip arthroplasty by removing the sections dealing with range of motion and deformity. It includes areas for patients to report on their gait abilities and light ADLs but nothing regarding pivoting, landing from jumps, running, or extremes of range of motion. Kocher and colleagues (14) devised a dance questionnaire that they used as a PRO tool in their study of outcomes after arthroscopic debridement of hip labral tears in 30 dancers. This questionnaire took into consideration how many hours of dance per week patients were performing pre- and postoperatively and included a question on the ability to perform rond de jambe en l'air, which would account for the extreme range of motion required by dancers of most genres. No studies were found in the literature regarding testing of this questionnaire. Lodhia and associates (39) performed a study looking at available PRO measures and justification for their use in the young non-arthritic hip patient population. It was determined that, on the basis of the current literature, the HOS has the largest amount of evidence to supports its use.

Surgical Techniques

Patients with confirmed labral tear and pain that persists after activity modification and a physical therapy trial may consider surgical correction. Surgical techniques available include open as well as arthroscopic interventions. Ganz described an open technique that involves trochanteric osteotomy and surgical dislocation of the hip for indications that include anterior impingement and femoral head asphericity. (40) Surgical correction of labral tears in dancers, however, has most often consisted of arthroscopic labral debridement. Debridement of labral tears through arthroscopy has been reported by Byrd and Jones (35) to have successful outcomes in 83% of patients without arthritis at a follow-up of 10 years. These outcomes were determined by use of the MHHS test. Kocher and colleagues (14) studied 30 dancers who had undergone arthroscopic labral debridement. It was revealed that 73% of these dancers were able to return to dance, albeit at fewer hours than were performed preoperatively. Eighty-nine percent of the dancers reported that they were able to perform a rond de jambe en l'air. This study also utilized the MHHS to collect outcome data, as well as a questionnaire especially designed for dancers. Return to high-level dance activity after labral debridement is possible, but can take over a year, according to these investigators.

It is now established that an association exists between acetabular labral tears and the early onset of osteoarthritis. (41) Therefore, much of the recent literature regarding arthroscopy has promoted preservation of hip anatomy and repair of the labrum with correction of any morphological abnormality. Labral repair is considered when the injured area is found to have the ability to heal. A surgeon experienced in arthroscopy of the hip should perform the repair, as proper technique is important in achieving fixation and restoring labral function.

Larson and Giveans (42) conducted a study to evaluate outcomes of labral debridement versus labral refixation. The subjects all had labral pathology caused by pincer-type or combined pincer- and cam-type FAI. Outcomes were measured with the MHHS. The principal findings of this study were that labral refixation resulted in better MHHSs, a greater percentage of good to excellent outcomes, and a trend toward fewer progressive degenerative changes at an early follow-up of one year.

Labral repair requires a lengthier rehabilitation and a period of limited weightbearing, as does correction of structural bony abnormalities such as FAI cam- or pincer-type impingement. When FAI is present, osteoplasty may be required to avoid reoccurrence. If an anatomical abnormality is found to be the cause of the labral damage, correction of this irregularity is recommended to prevent reoccurrence. Although few cases of cam- or pincer-type impingement or dysplasia have been noted in pre-professional or professional dancers, recreational dancers may have an incidence rate similar to that of non-dancers. Many of these abnormalities can now also be corrected with arthroscopy. Matsuda and associates (43) reported that according to a comprehensive literature review performed in 2010, arthroscopic surgery for FAI had outcomes equal to or better than open dislocation or mini-open methods, with a lower rate of major complications. Dancers may be hesitant to undergo these procedures due to the increased length of time for return to dance activities and the chance that the repair may fail and eventually require debridement. However, medical professionals must inform the dancer of the risk of accelerated degeneration of the joint when the labrum is debrided. Only with a good understanding of the potential risks and benefits of each procedure can dancers make an informed decision based on their individual circumstances.

Philippon and coworkers (44) reported performing arthroscopic labral reconstruction rather than debridement or repair on certain patients who were found not to be candidates for these procedures. These investigators performed 95 repairs on patients with labral deficiency or advanced labral degeneration using an iliotibial band autograft. The MHHS was used to measure outcomes. The mean MHHS improved from 62 to 85, indicating good outcomes at a mean follow-up of 18 months.

Patients with labral damage may also present with chondral damage. If chondral injury is so extensive as to be down to the bone, the microfracture technique may be used to stimulate healing. This technique, previously used in the knee, is becoming increasingly popular for the hip. Microfracture involves the use of an arthroscopic awl to make multiple holes in the exposed subchondral bone plate. As many holes as possible are created, leaving about 3 to 4 mm between holes. This then produces a clot, which if treated properly with nonweightbearing status and continuous use of a passive motion device, can become fibrocartilage. Unfortunately, for patients undergoing arthroscopy with chondral damage, the prognosis is worse than for those with only labral damage. As many as 30% eventually require a total hip arthroplasty.

Ilizaliturri, in a comprehensive literature review, (45) found that the most common complication from arthroscopic surgery was neuropraxia. These neuropraxias all spontaneously resolved. Most are secondary to traction forces or compression generated by positioning during the procedure, and account for less than 1.5% of total cases.

Conclusion

The treatment of labral pathology in the dancer continues to evolve. Since the last literature review published in this journal, (46) the thinking regarding the assessment and treatment of the dancer's painful hip has been advanced by a variety of studies. This new review establishes that certain historical factors are proving helpful in pointing toward labral pathology as the etiology of hip dysfunction. New technology using motion capture studies and 3D analysis is giving clinicians more information regarding the dynamic demands of extreme motion at the hip joint. It has also indicated that the physical examination can be focused in ways that identify more precisely the cause of the dancer's complaints. Plain x-ray will be helpful in determining osteology. The MR arthogram currently is the most widely used radiographic technique to define labral pathology. However, ultrasound holds considerable promise based on initial data. The surgical management of symptomatic labral pathology continues to evolve. The long-term follow-up of various procedures, utilizing a consistent and appropriate patient-reported outcome tool, will undoubtedly help to clarify further optimal surgical interventions. For example, the long-term outcomes for dancers who have undergone labral repair versus labral debridement are not yet known. In the future, evidence gathered regarding the incidence of re-injury and comparative analysis of subsequent joint health in both surgical populations should provide us with information to assist in making recommendations to dancers. Finally, rehabilitation of the surgically treated labral hip varies by institution. No long-term studies of efficacy for rehabilitation strategies post-operatively or conservative care of labral tears have been published in the peer-reviewed literature to our knowledge. Therefore, this is an important field for further study to optimize the care of dances.

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Ruth Kern-Scott, P.T., M.S.S., is at Great Plains Therapy, Vermillion, South Dakota. Judith R. Peterson, M.D., is a Clinical Associate Professor in the Department of Neurosciences, Sanford School of Medicine, University of South Dakota, Sioux Falls, South Dakota. Patrick Morgan, M.D., is an Assistant Professor in the Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota.

Correspondence: Ruth Kern-Scott, P.T., M.S.S., Great Plains Therapy, 1407 East Cherry Street, Vermillion, South Dakota 57069; rscott.gpt1@yahoo.com.
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Author:Kern-Scott, Ruth; Peterson, Judith R.; Morgan, Patrick
Publication:Journal of Dance Medicine & Science
Date:Oct 1, 2011
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