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Compression and Flip Test for Diagnosis of Unstable Acetabular Labral Tears Using a Peripheral Compartment Approach
Technical Note
Compression and Flip Test for Diagnosis of Unstable Acetabular Labral Tears Using a Peripheral Compartment Approach Adinun Apivatgaroon, M.D., and Michael Dienst, M.D.
Abstract: Assessment of integrity of the acetabular labrum is generally done via the central compartment under distraction of the femoral head from the acetabulum. With the technique of raising the extra-articular and peripheral compartment first, there is a need for testing the stability and function of the labrum from the peripheral side in a nondistracted position of the joint. The authors report on the compression and flip test (i.e., the flip test) for the detection of unstable, intrasubstance tears of the labrum or unstable chondrolabral separations. The test can be performed by compressing the labrum with blunt instruments. We grade the labral conditions as follows: grade 0 for firm resistance and elasticity to palpation, grade 1þ as easily compressed by the probe, grade 2þ for eversion of the body of the labrum under compression), and grade 1 for ossified, hard resistance without any elasticity and compressibility. This test can be performed directly after accessing the peripheral compartment through a 2-portal technique without extensive capsular work.
T
he acetabular labrum is a fibrocartilaginous structure with a stable and continuous transition to the adjacent cartilage of the acetabular rim. In the undistracted hip, the labrum lies flush to the femoral head. In this physiological condition, the labrum functions as a seal keeping the fluid within the central compartment of the joint, which is distinguished as one of the most important biomechanical functions of the labrum. This allows for a lubricating effect and better load distribution with decreased peak loads.1 Finite elemental studies have shown that labral excision leads to higher solid-on-solid contact stresses and higher subsurface strains2 leading to possible earlier joint degeneration in the long term.
From the Department of Orthopedics, Faculty of Medicine, Thammasat University (A.A.), Rangsit, Prathumthani, Thailand; and Orthopaedische Chirurgie München (OCM) (M.D.), Munich, Germany. The authors report the following potential conflicts of interest or sources of funding: M.D. receives support from Karl Storz and Medacta. Received May 1, 2016; accepted August 22, 2016. Address correspondence to Adinun Apivatgaroon, M.D., Department of Orthopedics, Faculty of Medicine, Thammasat University, Paholyothin Road, Klong Luang, Rangsit, Prathumthani 12121, Thailand. E-mail: adino_ball@ yahoo.com Ó 2016 by the Arthroscopy Association of North America. Published by Elsevier. All rights reserved. 2212-6287/16376/$36.00 http://dx.doi.org/10.1016/j.eats.2016.08.014
Arthroscopy Techniques, Vol
-,
Several traumatic and predominant atraumatic causes of acetabular labral tears have been noted. Direct repetitive micro-trauma as well as trauma from high-energy injuries such as subluxation and dislocations has been reported.3 More frequent are atraumatic causes that include femoroacetabular impingement and developmental dysplasia of the hip. Depending on the basic and primarily osseous pathology, different patterns of labral damage have been seen. These range from tissue degeneration, calcifications, ossifications, intra- and perilabral cyst formation, intrasubstance tearing, and chondrolabral separations. A precise assessment is mandatory to find the cause of labral damage and to determine adequate treatment for both the underlying disease and the labral damage itself. Unstable tears of the labrum are mainly related to deep chondrolabral separations, of variable lengths and Table 1. Key Points Routinely, integrity of the acetabular labrum is evaluated by inspection and palpation via the central compartment under distraction of the hip. From the peripheral compartment, without distraction of the femoral head from the lunate cartilage, the chondrolabral junction cannot be visualized. The arthroscopic compression and flip test offers a useful arthroscopic technique for indirect evaluation of the acetabular labral tears from the peripheral side in the nondistracted position of the joint.
No
-
(Month), 2016: pp e1-e7
e1
e2
A. APIVATGAROON AND M. DIENST
Fig 1. Compression and flip test of the anterior labrum of the right hip with an arthroscope inserted through the proximal anterolateral portal (PALP) and a hook via the anterior portal (AP). Modified with permission from Dienst M, ed., Hip Arthroscopy, Elsevier Urban & Fischer, Munich 2010.
with potential extension into the labral body. The latter is usually combined with degenerative changes of the labrum. Meanwhile, there are more advanced radiologic techniques such as high-resolution magnetic resonance arthrography for the detection of acetabular tears. Arthroscopic evaluation remains the gold standard for the diagnosis of the type, size, and stability of an acetabular tear. Assessment of the integrity of the acetabular labrum is chiefly done via the central compartment while under distraction of the femoral head from the acetabulum. With the rising of the extraarticular and peripheral compartments (PCs) as the initial technique, there is a need for testing the stability and function of the labrum from the peripheral side in the nondistracted position of the joint. This report presents the compression and flip test (the flip test) of the anterolateral labrum from the PC in the nondistracted position of the femoral head used for the assessment of labral stability (Table 1).
Fig 2. Normal and pathologic conditions (red arrow) of the anterolateral labrum during inspection of the right hip from the proximal anterolateral viewing portal with a 70 arthroscope. (A) Normal labrum; (B) labral hypertrophy; (C) discoloration of the labral base; (D) increased vascular blood filling; (E) labral ossification; (F) labral cyst; (G) cartilage flap interpositioning between the labrum and femoral head (FH). Ó 2016 Michael Dienst. All Rights Reserved.
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
e3
Fig 3. Negative compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope with normal firm and elastic resistance before (A, B) and during compression (C, D). (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
Surgical Technique Patient Positioning and Placement of Portals The patient is placed in the supine position on a traction table (Maquet, Germany), with the use of a large perineal post. The surgical hip is brought into a slight flexion of 10 to 20 and an abduction of 10 . The contralateral hip is placed in a position with abduction of about 20 , neutral rotation, and 0 of flexion. Minimal traction is applied to maintain both legs in a stable position. For access and diagnostic assessment of the PC, the proximal anterolateral portal and anterior portal (AP) are inserted (Fig 1). The proximal anterolateral portal is introduced under fluoroscopic control into the anterior head-neck junction. After insertion of the 70 arthroscope (HPS-Hip Portal System, Karl Storz, Germany), the anterior capsule is viewed for arthroscopic control of the anterior portal placement. The capsular penetration for the AP is at 3 o’clock directly proximal to the zona orbicularis. After
placement of the AP, the hip is flexed to approximately 30 to relax the strong iliofemoral ligament and increase the anterior PC cavity. Depending on the grade of synovitis, capsular thickening, and fibrosis, a variable degree of synovectomy and capsular release is performed to complete assessment of the PC. The authors limit capsular incisions to the portal entry sites and prefer to release the zona orbicularis from anterior to lateral for “ballooning” of the PC.4 Diagnostic Arthroscopy in the PC The diagnostic round of the PC is performed in a standard fashion starting at the anterior and medial neck area then moving to the medial, anterior, and lateral head areas and, finally, to the lateral neck and posterior area.5 For inspection and palpation of the medial, anterior, and lateral labrum, the hip is maintained at about 30 of flexion. The 70 scope is introduced via the proximal anterolateral portal and rotated proximally toward the labrum. Regarding motion analysis and the potential impingement conflict, the hip
e4
A. APIVATGAROON AND M. DIENST
Fig 4. Grade 1þ positive compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope before (A, B) and after compression with the probe with a deep indentation at the base of the labrum (C, D). In this area, the labrum shows red discoloration. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
is moved from full extension to maximum flexion with internal and external rotation. Inspection of the labrum includes assessment of the color, size, shape and global position in relation to the head-neck junction for indicating tissue quality. In this step, we can evaluate the labral conditions such as hypertrophy (sign of developmental dysplasia of the hip), discoloration, increased vascular filling, labral cysts, ossification (sign of pincer femoroacetabular impingement), and chondrolabral lesions (cartilaginous flap) (Fig 2). The Flip Test To assess and palpate for labral tissue quality and stability, a probe (graduated, length of hook 3 mm, diameter 1.5 mm, working length 18 cm) (Karl Storz) is inserted via the AP (Video 1). From this portal, the labrum can be palpated from a position approximately 1 o’clock to 5 o’clock and thus can be checked for tissue resistance, potential focal ossifications or calcifications, and the residual width of the labrum in cases of bony rim apposition or rim osteophytes.
The tissue quality and stability of the labrum is tested with the flip test (Figs 3-6, Video 1). This test can be performed by either an arthroscopic probe or by using the blunt side of a shaver blade (diameter 4.5 mm, working length 180 mm) (Karl Storz). The shaver blade has more stability than the arthroscopic probe and is more resistant to higher torque forces when the soft tissue mantle is thick and rigid. If the normal labrum shows a firm resistance and elasticity to palpation with the probe, the flip test result is graded as 0 or a negative value (Fig 3). The flip test is defined as a single positive (1þ) when the labrum can be easily compressed by the probe (Fig 4). This finding is typically found in limited chondrolabral separations over a length of not more than 2 hours, with or without smaller intrasubstance tears of the acetabular labrum. Central tears are often combined with fatty degeneration of the labral tissue. In those cases, the test can be graded as a positive without deeper chondrolabral separations. If the flip test leads to an eversion of the body of the labrum so that the labral tear margin can be seen
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
e5
Fig 5. Grade 2þ positive compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope before (A, B) and after compression (C, D). With eversion of the labrum, the free edge is raised (large black arrows) and the labral margin of the tear (small black arrows) can be seen. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
without traction, the test is rated as a double positive (2þ) (Fig 5). Frequently, eversion of the labrum is abrupt and noticed as a “flip,” and the eversion and flipping of the labrum correlates with larger chondrolabral separations and a combination with labral intrasubstance tears. Sometimes, the eversion or flipping of the labrum can be accompanied by the dislocation of a labral or hyaline cartilage flap between the labrum and femoral head indicating large undersurface labral tears of larger hyaline cartilage flaps. If the flip test shows a hard resistance without any elasticity and compressibility of the labral tissue, this indicates ossification of that portion of the labrum. This finding is defined as one minus result of the test (1) (Fig 6). When the labrum shows a varying degree ossification ranging from small ossified particles over focal subtotal ossifications to a completely ossified labrum, the most common basic pathology is a femoroacetabular pincer impingement.
Discussion The PC first technique to the hip is gaining more popularity. One of the disadvantages of this approach is that it is impossible to inspect the important chondrolabral junction where most tears of the acetabular labrum and hyaline cartilage damage are localized. For viewing and palpation of the central side of the acetabular rim, traction and arthroscopy of the central compartment are needed.6,7 Arthroscopy of the central compartment under traction with assessment of the chondrolabral junction can be performed when the diagnostics and potential treatment of the PC are completed. However, knowledge of the condition of the acetabular labrum during the diagnostic assessment through the PC is beneficial for different reasons: (1) The pattern of pathologic changes of the labrum is an important piece in the “diagnostic puzzle” in determining the underlying osseous pathology. This has a direct impact on the subsequent
e6
A. APIVATGAROON AND M. DIENST
Fig 6. Grade 1e compression and flip test of the anterolateral labrum of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope. The subtotal, ossified labrum (red arrow) (A), before (B), and after (C) compression. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
arthroscopic treatment. (2) The early knowledge of the need for a repair or reconstruction of the labrum allows timely instrumental preparation and time planning for the anesthetist and for subsequent cases. The flip test allows an assessment of the integrity of the acetabular labrum from the peripheral side without traction. From direct inspection, pathologic changes such as labral hypertrophy, perilabral synovitis, increased blood filling of the vascular plexus on the
peripheral side of the labrum, discoloration from fatty degeneration, perilabral cysts, and total ossification can be seen. The flip test provides important additional information about the quality and stability of the labral tissue. Employing a combination of all findings, the surgeon receives important parameters for identification of the underlying bony deformity and can make an informed choice on which treatment for the acetabular labrum needs to be performed (Table 2).
Table 2. Pearls and Pitfalls
Table 3. Advantages and Risks and Limitations
Pearls
Pitfalls
Inspection of the labrum can be hindered by hypertrophic synovial tissue or perilabral ossifications within the perilabral sulcus. In those cases, synovectomy and removal of ossifications is mandatory before the labrum can be completely inspected and tested.
In revision arthroscopies, identification of the anterolateral labrum can be difficult because of scar formation in the perilabral sulcus and adhesions between the labrum and capsule. Here, the labrum needs to be identified medially at the transition to the transverse ligament and followed anterolaterally.
Advantages Allows assessment of the condition and stability of the acetabular labrum from the peripheral compartment without traction Helps provide information about the labral pathologies and reminds operators to be more careful during the assessment of the central compartment. Is fast and easy, without the need of an extensive capsular release and without risks of cartilage and labral damage Risks and limitations Additional assessment of the central aspect (chondrolabral junction) under traction is recommended False positive test results in a degenerative and hypertrophic labrum False negative test results in small chondrolabral separations
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
However, there are limitations of the test and the assessment of the labrum from the peripheral side. Generally, the labrum appears more stable in the nondistracted position because of the support of the femoral head on its central surface. Thus, if chondrolabral separations are small, the flip test can result in a false negative. However, such a finding may indicate that repair of the labrum is not necessary. On the other hand, the flip test may show a false positive for a labral tear. From the authors’ experience, such a false positive result is limited for 1þ tests and likely impossible for 2þ tests. In 1þ tests, a deep indentation into the labral tissue may be caused by the significant tissue degeneration that is frequently found in residual dysplasia of the hip with labral hypertrophy (Table 3). The flip test of the acetabular labrum during arthroscopy of the PC in the nondistracted position provides important information on the condition of the labrum. Further studies are needed to compare these results with those of inspection and palpation via the central compartment.
e7
References 1. Ferguson SJ, Bryant JT, Ganz R, Ito K. The acetabular labrum seal: A poroelastic finite element model. Clin Biomech 2000;15:463-468. 2. Ferguson SJ, Bryant JT, Ganz R, Ito K. The influence of the acetabular labrum on hip joint cartilage consolidation: A poroelastic finite element model. J Biomech 2000;33:953-960. 3. Philippon MJ, Martin RR, Kelly BT. A classification system for labral tears of the hip. Arthroscopy 2005;21:e36 (suppl, abstr). 4. Dienst M, Kusma M, Steimer O, Holzhoffer P, Kohn D. Arthroscopic resection of the cam deformity of femoroacetabular impingement. Oper Orthop Traumatol 2010;22: 29-43 [in German]. 5. Dienst M, Goedde S, Seil R, Hammer D, Kohn D. Hip arthroscopy without traction: In vivo anatomy of the peripheral hip joint cavity. Arthroscopy 2001;17:924-931. 6. Dienst M, Seil R, Kohn D. Safe arthroscopic access to the central compartment of the hip joint. Arthroscopy 2005;21: 1510-1514. 7. Papavasiliou AV, Bardakos NV. Complications of arthroscopic surgery of the hip. Bone Joint Res 2012;1:131-144.
Compression and Flip Test for Diagnosis of Unstable Acetabular Labral Tears Using a Peripheral Compartment Approach Adinun Apivatgaroon, M.D., and Michael Dienst, M.D.
Abstract: Assessment of integrity of the acetabular labrum is generally done via the central compartment under distraction of the femoral head from the acetabulum. With the technique of raising the extra-articular and peripheral compartment first, there is a need for testing the stability and function of the labrum from the peripheral side in a nondistracted position of the joint. The authors report on the compression and flip test (i.e., the flip test) for the detection of unstable, intrasubstance tears of the labrum or unstable chondrolabral separations. The test can be performed by compressing the labrum with blunt instruments. We grade the labral conditions as follows: grade 0 for firm resistance and elasticity to palpation, grade 1þ as easily compressed by the probe, grade 2þ for eversion of the body of the labrum under compression), and grade 1 for ossified, hard resistance without any elasticity and compressibility. This test can be performed directly after accessing the peripheral compartment through a 2-portal technique without extensive capsular work.
T
he acetabular labrum is a fibrocartilaginous structure with a stable and continuous transition to the adjacent cartilage of the acetabular rim. In the undistracted hip, the labrum lies flush to the femoral head. In this physiological condition, the labrum functions as a seal keeping the fluid within the central compartment of the joint, which is distinguished as one of the most important biomechanical functions of the labrum. This allows for a lubricating effect and better load distribution with decreased peak loads.1 Finite elemental studies have shown that labral excision leads to higher solid-on-solid contact stresses and higher subsurface strains2 leading to possible earlier joint degeneration in the long term.
From the Department of Orthopedics, Faculty of Medicine, Thammasat University (A.A.), Rangsit, Prathumthani, Thailand; and Orthopaedische Chirurgie München (OCM) (M.D.), Munich, Germany. The authors report the following potential conflicts of interest or sources of funding: M.D. receives support from Karl Storz and Medacta. Received May 1, 2016; accepted August 22, 2016. Address correspondence to Adinun Apivatgaroon, M.D., Department of Orthopedics, Faculty of Medicine, Thammasat University, Paholyothin Road, Klong Luang, Rangsit, Prathumthani 12121, Thailand. E-mail: adino_ball@ yahoo.com Ó 2016 by the Arthroscopy Association of North America. Published by Elsevier. All rights reserved. 2212-6287/16376/$36.00 http://dx.doi.org/10.1016/j.eats.2016.08.014
Arthroscopy Techniques, Vol
-,
Several traumatic and predominant atraumatic causes of acetabular labral tears have been noted. Direct repetitive micro-trauma as well as trauma from high-energy injuries such as subluxation and dislocations has been reported.3 More frequent are atraumatic causes that include femoroacetabular impingement and developmental dysplasia of the hip. Depending on the basic and primarily osseous pathology, different patterns of labral damage have been seen. These range from tissue degeneration, calcifications, ossifications, intra- and perilabral cyst formation, intrasubstance tearing, and chondrolabral separations. A precise assessment is mandatory to find the cause of labral damage and to determine adequate treatment for both the underlying disease and the labral damage itself. Unstable tears of the labrum are mainly related to deep chondrolabral separations, of variable lengths and Table 1. Key Points Routinely, integrity of the acetabular labrum is evaluated by inspection and palpation via the central compartment under distraction of the hip. From the peripheral compartment, without distraction of the femoral head from the lunate cartilage, the chondrolabral junction cannot be visualized. The arthroscopic compression and flip test offers a useful arthroscopic technique for indirect evaluation of the acetabular labral tears from the peripheral side in the nondistracted position of the joint.
No
-
(Month), 2016: pp e1-e7
e1
e2
A. APIVATGAROON AND M. DIENST
Fig 1. Compression and flip test of the anterior labrum of the right hip with an arthroscope inserted through the proximal anterolateral portal (PALP) and a hook via the anterior portal (AP). Modified with permission from Dienst M, ed., Hip Arthroscopy, Elsevier Urban & Fischer, Munich 2010.
with potential extension into the labral body. The latter is usually combined with degenerative changes of the labrum. Meanwhile, there are more advanced radiologic techniques such as high-resolution magnetic resonance arthrography for the detection of acetabular tears. Arthroscopic evaluation remains the gold standard for the diagnosis of the type, size, and stability of an acetabular tear. Assessment of the integrity of the acetabular labrum is chiefly done via the central compartment while under distraction of the femoral head from the acetabulum. With the rising of the extraarticular and peripheral compartments (PCs) as the initial technique, there is a need for testing the stability and function of the labrum from the peripheral side in the nondistracted position of the joint. This report presents the compression and flip test (the flip test) of the anterolateral labrum from the PC in the nondistracted position of the femoral head used for the assessment of labral stability (Table 1).
Fig 2. Normal and pathologic conditions (red arrow) of the anterolateral labrum during inspection of the right hip from the proximal anterolateral viewing portal with a 70 arthroscope. (A) Normal labrum; (B) labral hypertrophy; (C) discoloration of the labral base; (D) increased vascular blood filling; (E) labral ossification; (F) labral cyst; (G) cartilage flap interpositioning between the labrum and femoral head (FH). Ó 2016 Michael Dienst. All Rights Reserved.
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
e3
Fig 3. Negative compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope with normal firm and elastic resistance before (A, B) and during compression (C, D). (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
Surgical Technique Patient Positioning and Placement of Portals The patient is placed in the supine position on a traction table (Maquet, Germany), with the use of a large perineal post. The surgical hip is brought into a slight flexion of 10 to 20 and an abduction of 10 . The contralateral hip is placed in a position with abduction of about 20 , neutral rotation, and 0 of flexion. Minimal traction is applied to maintain both legs in a stable position. For access and diagnostic assessment of the PC, the proximal anterolateral portal and anterior portal (AP) are inserted (Fig 1). The proximal anterolateral portal is introduced under fluoroscopic control into the anterior head-neck junction. After insertion of the 70 arthroscope (HPS-Hip Portal System, Karl Storz, Germany), the anterior capsule is viewed for arthroscopic control of the anterior portal placement. The capsular penetration for the AP is at 3 o’clock directly proximal to the zona orbicularis. After
placement of the AP, the hip is flexed to approximately 30 to relax the strong iliofemoral ligament and increase the anterior PC cavity. Depending on the grade of synovitis, capsular thickening, and fibrosis, a variable degree of synovectomy and capsular release is performed to complete assessment of the PC. The authors limit capsular incisions to the portal entry sites and prefer to release the zona orbicularis from anterior to lateral for “ballooning” of the PC.4 Diagnostic Arthroscopy in the PC The diagnostic round of the PC is performed in a standard fashion starting at the anterior and medial neck area then moving to the medial, anterior, and lateral head areas and, finally, to the lateral neck and posterior area.5 For inspection and palpation of the medial, anterior, and lateral labrum, the hip is maintained at about 30 of flexion. The 70 scope is introduced via the proximal anterolateral portal and rotated proximally toward the labrum. Regarding motion analysis and the potential impingement conflict, the hip
e4
A. APIVATGAROON AND M. DIENST
Fig 4. Grade 1þ positive compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope before (A, B) and after compression with the probe with a deep indentation at the base of the labrum (C, D). In this area, the labrum shows red discoloration. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
is moved from full extension to maximum flexion with internal and external rotation. Inspection of the labrum includes assessment of the color, size, shape and global position in relation to the head-neck junction for indicating tissue quality. In this step, we can evaluate the labral conditions such as hypertrophy (sign of developmental dysplasia of the hip), discoloration, increased vascular filling, labral cysts, ossification (sign of pincer femoroacetabular impingement), and chondrolabral lesions (cartilaginous flap) (Fig 2). The Flip Test To assess and palpate for labral tissue quality and stability, a probe (graduated, length of hook 3 mm, diameter 1.5 mm, working length 18 cm) (Karl Storz) is inserted via the AP (Video 1). From this portal, the labrum can be palpated from a position approximately 1 o’clock to 5 o’clock and thus can be checked for tissue resistance, potential focal ossifications or calcifications, and the residual width of the labrum in cases of bony rim apposition or rim osteophytes.
The tissue quality and stability of the labrum is tested with the flip test (Figs 3-6, Video 1). This test can be performed by either an arthroscopic probe or by using the blunt side of a shaver blade (diameter 4.5 mm, working length 180 mm) (Karl Storz). The shaver blade has more stability than the arthroscopic probe and is more resistant to higher torque forces when the soft tissue mantle is thick and rigid. If the normal labrum shows a firm resistance and elasticity to palpation with the probe, the flip test result is graded as 0 or a negative value (Fig 3). The flip test is defined as a single positive (1þ) when the labrum can be easily compressed by the probe (Fig 4). This finding is typically found in limited chondrolabral separations over a length of not more than 2 hours, with or without smaller intrasubstance tears of the acetabular labrum. Central tears are often combined with fatty degeneration of the labral tissue. In those cases, the test can be graded as a positive without deeper chondrolabral separations. If the flip test leads to an eversion of the body of the labrum so that the labral tear margin can be seen
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
e5
Fig 5. Grade 2þ positive compression and flip test of the anterolateral labrum (red arrow) of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope before (A, B) and after compression (C, D). With eversion of the labrum, the free edge is raised (large black arrows) and the labral margin of the tear (small black arrows) can be seen. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
without traction, the test is rated as a double positive (2þ) (Fig 5). Frequently, eversion of the labrum is abrupt and noticed as a “flip,” and the eversion and flipping of the labrum correlates with larger chondrolabral separations and a combination with labral intrasubstance tears. Sometimes, the eversion or flipping of the labrum can be accompanied by the dislocation of a labral or hyaline cartilage flap between the labrum and femoral head indicating large undersurface labral tears of larger hyaline cartilage flaps. If the flip test shows a hard resistance without any elasticity and compressibility of the labral tissue, this indicates ossification of that portion of the labrum. This finding is defined as one minus result of the test (1) (Fig 6). When the labrum shows a varying degree ossification ranging from small ossified particles over focal subtotal ossifications to a completely ossified labrum, the most common basic pathology is a femoroacetabular pincer impingement.
Discussion The PC first technique to the hip is gaining more popularity. One of the disadvantages of this approach is that it is impossible to inspect the important chondrolabral junction where most tears of the acetabular labrum and hyaline cartilage damage are localized. For viewing and palpation of the central side of the acetabular rim, traction and arthroscopy of the central compartment are needed.6,7 Arthroscopy of the central compartment under traction with assessment of the chondrolabral junction can be performed when the diagnostics and potential treatment of the PC are completed. However, knowledge of the condition of the acetabular labrum during the diagnostic assessment through the PC is beneficial for different reasons: (1) The pattern of pathologic changes of the labrum is an important piece in the “diagnostic puzzle” in determining the underlying osseous pathology. This has a direct impact on the subsequent
e6
A. APIVATGAROON AND M. DIENST
Fig 6. Grade 1e compression and flip test of the anterolateral labrum of a right hip from the proximal anterolateral viewing portal using a 70 arthroscope. The subtotal, ossified labrum (red arrow) (A), before (B), and after (C) compression. (FH, femoral head.) Ó 2016 Michael Dienst. All Rights Reserved.
arthroscopic treatment. (2) The early knowledge of the need for a repair or reconstruction of the labrum allows timely instrumental preparation and time planning for the anesthetist and for subsequent cases. The flip test allows an assessment of the integrity of the acetabular labrum from the peripheral side without traction. From direct inspection, pathologic changes such as labral hypertrophy, perilabral synovitis, increased blood filling of the vascular plexus on the
peripheral side of the labrum, discoloration from fatty degeneration, perilabral cysts, and total ossification can be seen. The flip test provides important additional information about the quality and stability of the labral tissue. Employing a combination of all findings, the surgeon receives important parameters for identification of the underlying bony deformity and can make an informed choice on which treatment for the acetabular labrum needs to be performed (Table 2).
Table 2. Pearls and Pitfalls
Table 3. Advantages and Risks and Limitations
Pearls
Pitfalls
Inspection of the labrum can be hindered by hypertrophic synovial tissue or perilabral ossifications within the perilabral sulcus. In those cases, synovectomy and removal of ossifications is mandatory before the labrum can be completely inspected and tested.
In revision arthroscopies, identification of the anterolateral labrum can be difficult because of scar formation in the perilabral sulcus and adhesions between the labrum and capsule. Here, the labrum needs to be identified medially at the transition to the transverse ligament and followed anterolaterally.
Advantages Allows assessment of the condition and stability of the acetabular labrum from the peripheral compartment without traction Helps provide information about the labral pathologies and reminds operators to be more careful during the assessment of the central compartment. Is fast and easy, without the need of an extensive capsular release and without risks of cartilage and labral damage Risks and limitations Additional assessment of the central aspect (chondrolabral junction) under traction is recommended False positive test results in a degenerative and hypertrophic labrum False negative test results in small chondrolabral separations
THE FLIP TEST FOR DIAGNOSIS OF UNSTABLE ACETABULAR LABRAL TEARS
However, there are limitations of the test and the assessment of the labrum from the peripheral side. Generally, the labrum appears more stable in the nondistracted position because of the support of the femoral head on its central surface. Thus, if chondrolabral separations are small, the flip test can result in a false negative. However, such a finding may indicate that repair of the labrum is not necessary. On the other hand, the flip test may show a false positive for a labral tear. From the authors’ experience, such a false positive result is limited for 1þ tests and likely impossible for 2þ tests. In 1þ tests, a deep indentation into the labral tissue may be caused by the significant tissue degeneration that is frequently found in residual dysplasia of the hip with labral hypertrophy (Table 3). The flip test of the acetabular labrum during arthroscopy of the PC in the nondistracted position provides important information on the condition of the labrum. Further studies are needed to compare these results with those of inspection and palpation via the central compartment.
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