Suction Seal Research Articles

Poster 199: The Hip Suction Seal Restoration Using the Circumferential Labral Reconstruction. The Role of The Graft Width

Objectives: Background:Favorable patient-reported outcomes has been reported following circumferential labral reconstruction (CLR);however, there is a paucity on biomechanical data following CLR.Purpose:To evaluate the role of the CLR using iliotibial band (ITB) allograft on the restoration of the distractive stability force (suction seal), and to evaluate whether any correlation existed between ITB allograft width and the distractive stability restoration after CLR.Hypothesis:1) CLR using a wider ITB allograft would restore the distractive stability force to a level comparable to the intact labrum. 2) Wider CLR would achieve significantly superior distractive stability force when compared to CLR using smaller width allograft.Methods:14 fresh-frozen cadaveric hips consisting of hemipelvis and proximal femur with intact labra and without osteoarthritis (Tönnis > 1) were dissected free of all soft tissue including the hip capsule. Each hip underwent two CLR using ITB allograft, width > 6.5mm (7.5-8.0mm) and width <6.5mm (4.5-5.0mm), the order of the reconstruction was assigned in a randomized fashion. Each hemipelvis was potted, placed in the saline bath, and securely fixed to the frame of a hydraulic testing system with the hip being placed in 30° of abduction. A 500N·m compressive load was applied to the acetabulum followed by a distraction at the rate of 5.0mm/s. Force and displacement were recorded throughout the distraction until the suction seal ruptured. Measures were performed in each hip for intact labrum, deficient (excised) labrum, first CLR, and second CLR.Results:The distraction force was comparable between the intact state and the CLR >6.5mm (P = 0.587). Further, the distraction force was comparable between the deficient state and the CLR <6.5mm (P = 0.418). When comparing the CLR <6.5mm and CLR >6.5mm, the distraction force was significantly higher for the latest (P = 0.01). Also, the CLR >6.5mm outperformed the deficient state (P = 0.001). Similarly, the distance to suction seal rupture was comparable between the intact state and the CLR >6.5 mm (P = 0.587), comparable for the deficient state and the CLR < 6.5mm (P = 0.418), significant longer for the CLR >6.5mm when compared to the CLR < 6.5mm and the deficient state (P = 0.01 and P = 0.001, respectively).[MOU1].Conclusions:The allograft width following CLR was found to be correlated with the hip suction seal restoration in a cadaveric model. CLR using an ITB allograft > 6.5mm was found to restore the distractive stability force to values comparable to the native intact labral state. Further, when compared to the CLR using ITB allograft with a width < 6.5mm, the CRL >6.5 mm outperformed by demonstrating significantly superior distractive stability force restoration.Clinical Relevance:The allograft width for CRL was correlated with the hip suction seal effect restoration in a cadaveric model. Although further studies would be required to identify the clinical effects of the CLR allograft width, it seems appropriate to selecting allograft > 6.5mm in the clinical setting.Figure 1.The images corresponded to a right hip following a circumferential labral reconstruction. The tank was clamped to the hydraulic mechanical testing system (MTS). A. The acetabular pot has been secured to the tank and the femoral pot was fastened to the MTS actuator. B. The tank was filled with phosphate-buffered saline solution heated to 37°CFigure 2.This images corresponded to the same right hip. The most antcromedial aspect (AM) and posterolateral (PL) aspect of the acetabulum (A), and the most antcromedial (*) and posterolateral (▲) points of the transverse acetabular ligament have been marked. A. The native labium has been excised, and the anchor drill holes (black arrows) have been made. B. The circumferential labral reconstruction has been performed using an iliotibial band allograft (G). Eleven 2.4mm CinchLock SS PEEK knotlcss anchor with No. 1 ultra-high molecular weight polyethylene suture (Pivot Stryker) were used in this specimen. Femoral head (FH), ligamentous teres (LT)Figure 3.This images corresponded to the same right hip. The most anteromedial aspect (AM) and posterolateral (PL) aspect of the acetabulum (A), and the most anteromedial (*) and posterolateral (▲) points of the transverse acetabular ligament have been marked. A. A circumferential labral reconstruction (CLR) with an iliotibial allograft (G) 36.5mm has been performed. B. A CLR with G <6.5mm its shown. Femoral head (FH), ligamentous teres (LT).Figure 4.

An Increased Allograft Width for Circumferential Labral Reconstruction Better Restores Distractive Stability of the Hip: A Cadaveric Biomechanical Analysis

Background: Questions remain about whether circumferential labral reconstruction (CLR) using an iliotibial band (ITB) allograft can effectively restore the labral suction seal of the hip. Hypotheses: (1) CLR with an ITB allograft >6.5 mm would restore distractive stability force to that of the intact labrum. (2) CLR with an ITB allograft >6.5 mm would achieve significantly superior distractive stability force compared with CLR with an ITB allograft <6.5 mm. Study Design: Controlled laboratory study. Methods: A total of 6 fresh-frozen pelves with attached femurs (n = 12 matched hemipelves) from male donors were procured and dissected free of all soft tissue, including the hip capsule but preserving the native labrum, transverse acetabular ligament, and ligamentum teres. Potted hemipelves were placed in a saline bath and securely fixed to the frame of a hydraulic testing system. A 500-N compressive load was applied, followed by femoral distraction at a rate of 5.0 mm/s until the suction seal ruptured. Force and femoral displacement were continually recorded. Force versus displacement curves were plotted, the maximum force was recorded, and the amount of femoral distraction to rupture the suction seal was determined. After intact testing, the labrum was excised, and specimens were retested using the same protocol. CLR was subsequently performed twice in a randomized fashion using (1) an ITB allograft with a width >6.5 mm (7.5-9.0 mm) and (2) an ITB allograft with a width <6.5 mm (4.5-6.0 mm). Specimens were retested after each CLR procedure. Force (in Newtons) and femoral distraction (in millimeters) required to rupture the suction seal were measured and compared between the 4 testing states (intact, deficient, CLR <6.5 mm, and CLR >6.5 mm) using repeated-measures analysis of variance. Results: On average, intact specimens required 148.4 ± 33.1 N of force to rupture the hip suction seal, which significantly decreased to 44.3 N in the deficient state (P < .001). CLR with ITB allografts <6.5 mm did not improve the maximum force (63 ± 62 N) from the deficient state (P = .42) and remained significantly lower than the intact state (P < .01). CLR with ITB allografts >6.5 mm recorded significantly greater force to rupture the suction seal (135.8 ± 44.6 N) compared with both the deficient and CLR <6.5 mm states (P < .01), with a mean force comparable with the intact labrum (P = .59). The amount of femoral distraction to rupture the suction seal demonstrated similar findings. Conclusion: In a cadaveric model, CLR using ITB allografts >6.5 mm restored the distractive force and distance to the suction seal rupture to values comparable with hips with an intact labrum. CLR using ITB allografts >6.5 mm outperformed CLR with ITB allografts <6.5 mm, demonstrated by a significantly higher force to rupture the suction seal and increased distraction before the rupture. Clinical Relevance: The results of this cadaveric investigation suggest that using wider labral allografts during CLR will provide the distractive force required to rupture the suction seal and immediate postoperative stability of the hip, although further studies are required to determine if these results translate to improved clinical outcomes.

Preoperative Magnetic Resonance Imaging Predicts Intraoperative Labral Width at the 9-O’clock and 12-O’clock Positions in Primary Hip Arthroscopy

PurposeTo determine whether preoperative magnetic resonance imaging (MRI) can reliably predict labral width in primary hip arthroscopy.MethodsPatients who underwent primary hip arthroscopy with labral repair performed by a single surgeon from January 2008 to December 2015 were identified retrospectively from a prospectively collected database. The width of the labrum was measured intraoperatively at the time of surgery. Two orthopaedic surgeons performed labral width measurements on MRI at 3 standardized locations using the clock-face method at 2 time points, 4 weeks apart. Interobserver and intraobserver reliabilities were calculated, and comparisons were performed between intraoperatively measured labral widths and MRI measurements at the 3 positions.ResultsFifty-eight patients who underwent primary hip arthroscopy were enrolled in the study. The average labral width measurements at the 3-, 12-, and 9-o’clock positions were 6.8 mm (standard deviation [SD], 1.1), 6.9 mm (SD, 1.3 mm), and 6.2 mm (SD, 0.9 mm), respectively, on MRI compared with 7.2 mm (SD, 1.5 mm), 7.8 mm (SD, 2.3 mm), and 7.3 mm (SD, 1.6 mm), respectively, when measured intraoperatively. The intraoperative measurements were larger than the MRI measurements at all 3 locations, with significant differences at the 12-o’clock (P = .008) and 9-o’clock (P < .001) positions. The positive predictive value of the MRI measurements was 92% at the 3-o’clock position, 89% at the 12-o’clock position, and 94% at the 9-o’clock position for identifying a labral width of 6 mm or greater.ConclusionsMeasuring labral width on MRI yielded, on average, a value that is smaller than the intraoperatively measured width in primary hip arthroscopy procedures. MRI can predict a labral width of 6 mm or greater in at least 89% of cases, which will assist in operative planning.Clinical RelevanceThe clinical implications of this research include identifying the rare patients in whom more advanced hip arthroscopy procedures may be indicated, such as labral augmentation, in instances of inadequate labral volume that will adequately restore the biomechanics of the suction seal.

Midterm Outcomes After Hip Labral Augmentation in Revision Hip Arthroscopy

Background: Labral augmentation has emerged as an essential procedure to address a deficient or irreparable labrum while preserving native labral tissue and restoring the hip suction seal mechanism. Purpose: To evaluate midterm outcomes of arthroscopic hip labral augmentation for labral insufficiency after previous hip arthroscopy. Study Design: Case series; Level of evidence, 4. Methods: Patients were identified from a prospectively collected database who underwent arthroscopic hip labral augmentation between January 2011 and January 2017 with a minimum 3-year follow-up. Pre- and postoperative patient-reported outcome scores were compared and included the 12-Item Short Form Health Survey physical and mental component summaries, Western Ontario and McMaster Universities Osteoarthritis Index, modified Harris Hip Score (mHHS), and Hip Outcome Score (HOS) (Activities of Daily Living [ADL] and Sport). Postoperative Tegner Activity Scale and patient satisfaction (1-10) scores were also evaluated. The minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) between the preoperative and minimum 3-year follow-up scores were calculated. Results: A total of 88 patients (39 men, 49 women) underwent revision hip arthroscopy with labral augmentation. The average age was 32.8 ± 11 years. Of these, 77 patients (88%) were available for the minimum 3-year follow-up. The survivorship (absence of conversion to total hip arthroplasty) at 3 years and 5 years was 93% at both time points, with a mean survival time of 8.5 years (95% CI, 8.0-8.9). Eleven patients (14%) required revision arthroscopic surgery for continued pain. Revisions occurred at a mean of 2.6 ± 1.4 years after augmentation. The mean follow-up was 5.2 ± 1.2 years (range, 3-9 years). For patients not requiring subsequent surgery (n = 61), all patient-reported outcome measures significantly improved, which included a 20-point increase in HOS-ADL (MCID, 82%; PASS, 72%) and mHHS (MCID, 78%; PASS, 70%). The median postoperative Tegner score was 4 (range, 1-10). The median postoperative patient satisfaction score was 9 out of 10 (range, 1-10). Conclusion: Arthroscopic hip labral augmentation is a successful treatment option for patients with labral insufficiency after previous hip arthroscopy, demonstrating improved patient-reported outcomes and survivorship of 93% at 3 years and 5 years. This technique provides a valuable labral preservation option when addressing hip labral pathology when viable native labral tissue remains.

Hip Microinstability: Understanding a Newly Defined Hip Pathology in Young Athletes

Microinstability is an increasingly recognized diagnosis in young athletes presenting with hip pain. Causes of microinstability may include abnormality of the hip bony anatomy, acetabular labral tears, joint capsule laxity or injury, and muscle dysfunction. Borderline hip dysplasia is an increasingly recognized factor predisposing to microinstability. The capsuloligamentous structures of the hip, particularly the iliofemoral ligament, provide important restraints to femoral head motion, and iatrogenic defects can predispose patients to instability after surgery. Injury to the acetabular labrum may disrupt its important hip-stabilizing properties including the suction seal and improved acetabular depth. Hip muscle weakness or imbalance may result in increased femoral head motion within the acetabulum. The diagnosis of hip microinstability can be challenging, and the history is often nonspecific. Physical examination maneuvers include the anterior apprehension, prone instability, axial distraction, and abduction-hyperextension-external rotation tests. Radiographic features may include borderline hip dysplasia, femoral head-neck junction cliff sign, and an elevated femoral-epiphyseal acetabular roof index. Magnetic resonance arthrography may demonstrate a capsular defect, capsular thinning, or labral pathology. Diagnostic intra-articular injection of anesthetic can confirm the intra-articular nature of the pathology. Management of hip microinstability focuses on strengthening the dynamic stabilizers of the hip through focused physical therapy. Surgery may be considered in recalcitrant cases where symptoms persist despite optimization of hip stabilizer strength. In such cases, addressing the primary source of instability through labral repair or reconstruction and capsular repair or plication can be considered. In highly selected cases, surgery can result in excellent outcomes.

Circumferential and Segmental Arthroscopic Labral Reconstruction of the Hip Utilizing the Knotless Pull-Through Technique with All-Suture Anchors

Appropriate labral tear management is one of the principal priorities of hip-preservation surgery. The labrum’s role in the stability and biomechanics of the hip and preservation of the suction seal has been thoroughly demonstrated. Favorable patient-reported outcomes with labral reconstruction and, more recently, labral augmentation have shown that these are viable reconstructive procedures in the setting of irreparable labra. A wide variety of grafts have been used for these advanced labral restoration techniques. The present Technical Note will describe a detailed arthroscopic circumferential labral reconstruction using the pull-through technique with knotless all-suture anchors. The benefits of such can be applied to both segmental and circumferential labral reconstruction procedures, as well as labral augmentation, based on the intraoperative findings and preference of the surgeon.

Proximal Overresection During Femoral Osteochondroplasty Negatively Affects the Distractive Stability of the Hip Joint: A Cadaver Study

Background: Contact between the acetabular labrum and articular cartilage of the femoral head creates a suction seal that helps maintain stability of the femoral head in the acetabulum. A femoral osteochodroplasty may occasionally extend proximally into the femoral head, diminishing the articular surface area available for sealing contact. Purpose: To determine whether proximal overresection decreases the rotational and distractive stability of the hip joint. Study Design: Controlled laboratory study. Methods: Six hemipelvises in the following conditions were tested: intact, T-capsulotomy, osteochondroplasty to the physeal scar, and 5- and 10-mm proximal extension. The pelvis was secured to a metal plate, and the femur was potted and attached to a multiaxial hip jig. Specimens were axially distracted using a load from 0 to 150 N. For rotational stability testing, 5 N·m of internal and external torque was applied. Both tests were performed at different angles of flexion (0°, 15°, 30°, 60°, 90°). Displacement and rotation were recorded using a 3-dimensional motion tracking system. Results: The T-capsulotomy decreased the distractive stability of the hip joint. A femoral osteochondroplasty up to the physeal scar did not seem to affect the distractive stability. However, a proximal extension of the resection by 5 and 10 mm increased axial instability at every angle of flexion tested, with the greatest increase observed at larger angles of flexion (P < .01). External rotation increased significantly after T-capsulotomy in smaller angles of flexion (0°, P = .01; 15°, P = .01; 30°, P = .03). Femoral osteochondroplasty did not create further external rotational instability, except when the resection was extended 10 mm proximally and the hip was in 90° of flexion (P = .04). Conclusion: This cadaveric study demonstrated that proximal extension of osteochondroplasty into the femoral head compromises the distractive stability of the hip joint but does not affect hip rotational stability. Clinical Relevance: Clinically, this study highlights the importance of accuracy when performing femoral osteochondroplasty to minimize proximal extension that may increase iatrogenic instability of the hip joint.

Remplissage and Labral Reconstruction Technique Correlated With Dynamic Hip Examination Using the Kite Technique for Restoration of the Suction Seal in Revision Hip Arthroscopy

The hip suction seal plays a key role in distractive stability and maintenance of intra-articular fluid pressure of the hip. Preservation of the suction seal relies on the acetabular labrum and the congruence between the labrum and the femoral head−neck junction. During the treatment of cam-type impingement, iatrogenic over-resection in the femoral head−neck junction or labrum deficiency can cause loss of this suction seal. In this technical note, we describe a remplissage procedure performed in addition to labral reconstruction in a patient with loss of the suction seal due to a dysfunctional labrum and previous over-resection of a cam deformity.

Midterm Outcomes Following Hip Labral Augmentation

Objectives:Arthroscopic hip labral preservation techniques have evolved over the last decade. Arthroscopic hip labral augmentation with iliotibial band (ITB) autograft placed into a labral defect with viable circumferential fibers is a novel treatment option to restore the hip suction seal and improve functionality. The purpose of this study is to determine midterm (3-5 year follow up) outcomes of arthroscopic hip labral augmentation procedure.Methods:Patients who underwent arthroscopic hip labral augmentation from August 2011 to March 2017 were prospectively evaluated. Pre- and post-operative patient reported outcome scores were compared and included SF12 PCS, SF12 MCS, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Modified Harris Hip Score (mHHS), Hip Outcome Score (HOS) (Activities of Daily Living (ADL) and Sport). Post-operative Tegner Activity Scale and patient satisfaction (1 – 10) were also evaluated.Results:One hundred and six patients underwent arthroscopic hip labral augmentation with minimum 3-year follow-up. Mean follow-up was 5-year follow-up (range, 3 to 9.2 years). All patient reported outcomes improved after labral augmentation (SF12 PCS 39±8 vs. 50±10, p>0.01; mHHS 59±15 vs. 79±21, p<0.01; WOMAC 31±16 vs. 16±17, p<0.01; HOS ADL 64±17 vs. 84±21, p<0.01; HOS Sport 41±22 vs. 71±29, p<0.01). Median post-operative Tegner score was 4. Median post-operative patient satisfaction was 9 out of 10 (range, 1-10). In terms of survivorship, 12 patients (11%) required revision surgery and 6 (5.7%) converted to total hip arthroplasty (THA).Conclusions:Arthroscopic hip labral augmentation is a successful treatment option for patients that have viable circumferential fibers present at the time of arthroscopy. This technique continues to show improved patient reported outcomes and is another hip labral preservation technique that may help reestablish the intra-articular fluid suction seal.

Consensus-based classification system for intra-operative management of labral tears during hip arthroscopy-aggregate recommendations from high-volume hip preservation surgeons.

The purpose of this study was to survey high-volume hip preservation surgeons regarding their perspectives on intra-operative management of labral tears to improve decision-making and produce an effective classification system. A cross-sectional survey of high-volume hip preservation surgeons was conducted in person and anonymously, using a questionnaire that is repeated for indications of labral debridement, repair and reconstruction given the torn labra are stable, unstable, viable or non-viable. Twenty-six high-volume arthroscopic hip surgeons participated in this survey. Provided the labrum was viable (torn tissue that is likely to heal) and stable, labral debridement would be performed by 76.92% of respondents for patients >40 years of age and by >84% of respondents for stable intra-substance labral tears in patients without dysplasia. If the labrum was viable but unstable, labral repair would be performed by >80% of respondents for patients ≤40 years of age and > 80% of respondents if the labral size was >3 mm and located anteriorly. Presence of calcified labra or the Os acetabuli mattered while deciding whether to repair a labrum. In non-viable (torn tissue that is unlikely to heal) and unstable labra, labral reconstruction would be performed by 84.62% of respondents if labral size was <3 mm. The majority of respondents would reconstruct calcified and non-viable, unstable labra that no longer maintained a suction seal. Surgeons performing arthroscopic hip labral treatment may utilize this comprehensive classification system, which takes into consideration patient age, labral characteristics (viability and stability) and bony morphology of the hip joint. When choosing between labral debridement, repair or reconstruction, consensus recommendations from high-volume hip preservation surgeons can enhance decision-making.

Hip Labral Reconstruction with Capsular Autograft Augmentation

Multiple treatment options are available for patients presenting with a torn or deficient acetabular labrum. Biomechanical studies have demonstrated that the acetabular labrum may play a role in decreasing the risk of osteoarthritis and in maintaining long-term hip kinematics and stability. As such, repair or reconstruction of the labrum is often preferred over resection or debridement. In instances of a hypoplastic labrum, labral reconstruction or augmentation may be necessary even in a primary setting. Although reconstruction is a technique that should be in any hip arthroscopist’s toolkit, allografts can be expensive and may not always be available when needed. In this Technical Note, we describe a labral augmentation with capsular autograft that diminishes donor-site morbidity associated with fascia lata autografts. This technique enables incorporation of healthy capsular tissue that allows for the recreation of the suction seal while avoiding some of the technically challenging aspects and costs of the conventional allograft labral reconstruction.

The Effect of Rim Preparation, Labral Augmentation, and Labral Reconstruction on the Suction Seal of the Hip

To evaluate the biomechanical properties of the labral suction seal in the native labrum and after rim preparation, labral augmentation, and labral reconstruction. Eight hemi-pelvises were dissected to the level of labrum and mounted for biomechanical testing. Each specimen was tested in axial distraction starting with the native labrum and then sequentially following rim preparation from 12 to 3 o'clock, labral augmentation, and segmental labral reconstruction using the iliotibial band allograft. In each condition, the specimens were compressed to 250 N and then distracted at 10 mm/s with force and displacement continuously recorded. Each test was repeated 3 times, and the mean peak force, displacement at peak force, and work were calculated. Data were reported as a percentage of the intact values to account for sex and size differences. Statistical testing was performed via a repeated-measures analysis of variance with a post hoc Tukey analysis. Peak loads occurred within 2.21 to 3.11 mm of displacement. The mean peak force, displacement at peak force, and work relative to the intact condition were the following: rim preparation (91.1% ± 8.5%, 94.4% ± 14.3%, 93.4% ± 23.5%, respectively), augmentation (66.1% ± 27.6%, 78.2% ± 16.3%, 55.7% ± 30.7%, respectively), and reconstruction (55.6% ± 25.7%, 64.7% ± 31.4%, 38.7% ± 27.2%, respectively). There was no significant difference in peak force following the rim preparation (P= .807), but peak force was significantly decreased after augmentation and reconstruction (P= .010 and P < .001, respectively). There was no significant difference in displacement at peak force following rim preparation or augmentation (P= .936 and P= .125, respectively), but displacement at peak force was significantly decreased after reconstruction (P= .005). The work from the suction seal was significantly less in both augmentation and reconstruction states compared to the intact labrum (P= .004 and P < .001, respectively) and rim preparation (P= .017 and P < .001, respectively). The results show that the suction seal is not significantly changed following rim preparation. Relative to the rim preparation, labral augmentation may re-create the labral suction seal better than labral reconstruction. This study provides a biomechanical basis for surgical decision making and clinical management of patients with labral tears of the hip.

Technical Pearls for Arthroscopic Labral Augmentation of the Hip

Our recent understanding of the importance of the acetabular labral suction seal has placed preserving labral integrity as a guiding principle in hip preservation surgery. In cases with a hypoplastic labrum and intact chondrolabral junction, labral augmentation presents as a viable alternative and an often preferred treatment option over labral reconstruction. At this time, there are few studies that have described the technical pearls of performing labral augmentation of the hip. In this technique guide, we describe, in detail, the kite technique for the introduction, control, and acetabular fixation of a hip labral augmentation graft. Comparable to flying a kite with 2 fly lines and to the previously described kite technique for hip labral reconstruction, the kite technique for labral augmentation is based on the principle that the use of 2 control sutures in a pulley system creates an efficient method to accurately and reproducibly facilitate graft passage and fixation during arthroscopic labral augmentation procedures.

Surgical Treatment of Labral Tears: Debridement, Repair, and Reconstruction.

Advances in hip preservation surgery have to lead to increased utilization of hip arthroscopy. With this, there has also been a growth in the understanding of various hip conditions, therefore, leading to an increase in hip conditions amenable to arthroscopic intervention. The acetabular hip labrum has been at the forefront of arthroscopic advances in the hip. The labrum is important for hip stability, provision of the suction seal, and joint proprioception. Given the labrum's central role in hip biomechanics, there is increasing emphasis on labral preservation in the form of debridement and repair. In revision settings, advanced techniques such as labral augmentation and reconstruction may play a role in the management of labral pathology. Appropriate management of the hip labrum at the time of surgery can be an important mediator of the outcome. As such, an understanding of the evolving evidence base and surgical indications and techniques are integral to the treatment and management of labral pathology.

Arthroscopic Labral Repair of the Hip Using a Self-Grasping Suture-Passing Device: Maintaining the Chondrolabral Junction

In the setting of femoroacetabular impingement, the acetabular labrum may be torn or pathologic, and it must be surgically repaired to restore the native suction seal and hip function. However, the current methods of arthroscopic suture passage commonly result in some degree of disruption of the chondrolabral junction, with penetration and shuttling of the repair sutures. Novel instrumentation and surgical techniques have aimed to repair the acetabular labrum with decreased violation of the intrasubstance fibers to provide anatomic eversion/inversion of the labrum to restore the suction seal. In this Technical Note, we describe a method of suture passage through the use of a self-grasping suture-passing device that allows for anatomic labral repair while maintaining the chondrolabral junction as well as minimizing iatrogenic damage the labrum intrasubstance fibers.

The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability

Background: The acetabular labrum has been found to provide a significant contribution to the distractive stability of the hip. However, the influence of labral height on hip suction seal biomechanics is not known. Hypothesis: The smaller height of acetabular labrum is associated with decreased distractive stability. Study Design: Descriptive laboratory study. Methods: A total of 23 fresh-frozen cadaveric hemipelvises were used in this study. Hips with acetabular dysplasia or femoroacetabular impingement–related bony morphologic features, intra-articular pathology, or no measurable suction seal were excluded. Before testing, each specimen’s hip capsule was removed, a pressure sensor was placed intra-articularly, and the hip was fixed in a heated saline bath. Labral size was measured by use of a digital caliper. Maximum distraction force, distance to suction seal rupture, and peak negative pressure were recorded while the hip underwent distraction at a rate of 0.5 mm/s. Correlations between factors were analyzed using the Spearman rho, and differences between groups were detected using Mann-Whitney U test. Results: Of 23 hips, 12 satisfied inclusion criteria. The maximum distraction force and peak negative pressure were significantly correlated (R = −0.83; P = .001). Labral height was largely correlated with all suction seal parameters (maximum distraction force, R = 0.69, P = .013; distance to suction seal rupture, R = 0.55, P = .063; peak negative pressure, R = −0.62, P = .031). Labral height less than 6 mm was observed in 5 hips, with a mean height of 6.48 mm (SD, 2.65 mm; range, 2.62-11.90 mm; 95% CI, 4.80-8.17 mm). Compared with the 7 hips with larger labra (>6 mm), the hips with smaller labra had significantly shorter distance to suction seal rupture (median, 2.3 vs 7.2 mm; P = .010) and significantly decreased peak negative pressure (median, −59.3 vs −66.9 kPa; P = .048). Conclusion: Smaller height (<6 mm) of the acetabular labrum was significantly associated with decreased distance to suction seal rupture and decreased peak negative pressure. A new strategy to increase the size of the labrum, such as labral augmentation, could be justified for patients with smaller labra in order to optimize the hip suction seal. Clinical Relevance: The height of the acetabular labrum is correlated with hip suction seal biomechanics. Further studies are required to identify the clinical effects of labral height on hip stability.

The Hip Suction Seal, Part II: The Effect of Rim Trimming, Chondrolabral Junction Separation, and Labral Repair/Refixation on Hip Distractive Stability

Background: The acetabular labrum contains free nerve endings, and an unstable labrum can result in increased femoral head movement during hip motion. This can be caused by chondrolabral junction (CLJ) separation, especially in association with pincer-type femoroacetabular impingement, and may contribute to hip pain. Hypothesis: Rim resection alone has no effect on suction seal biomechanics. Further, separation of the CLJ changes hip suction seal biomechanics when compared with those of the native state, whereas repair and refixation with suture anchors restore these biomechanical parameters. Study Design: Controlled laboratory study. Methods: A total of 12 fresh-frozen human cadaveric hips were used in this study. Hips were mounted in a saline bath on a dynamic tensile testing machine and were distracted at a rate of 0.5 mm/s from neutral position. A total of 3 parameters (force, displacement, and intra-articular pressure) were measured throughout testing. Before testing, hips were randomly allocated to 1 of 2 groups: 1 that included the CLJ separation (CLJ Cut group) and 1 that did not (CLJ Intact group). Hips were tested in the following states: (1) native, (2) rim trimming, (3) separated CLJ (CLJ Cut group only), and (4) labral repair/refixation. For each group a linear mixed-effects model was used to compare biomechanical parameters between states. Results: Rim trimming did not affect any suction seal parameters relative to those of the native state. In the CLJ Cut group, no significant difference in distance to break the suction seal was observed for any states compared with that of the native state. In the CLJ Intact group, the distance to break the suction seal was significantly shorter in the labral refixation state (1.8 mm) than the native state (5.6 mm; P = .002). The maximum distraction force (62.1 ± 54.1 N) and the peak negative pressure (−36.6 ± 24.2 kPa) of the labral repair/refixation state were significantly lower than those of the native state in both groups (93.4 ± 41.7 N, P = .01; –60.7 ± 20.4 kPa, P = .02). Conclusion: Rim trimming did not change the biomechanical properties of the labral suction seal. Labral refixation resulted in a shorter distance to break the labral suction seal. This indicates that labral mobility is reduced by the labral refixation procedure, which could be beneficial in postoperative pain relief and labral healing. Clinical Relevance: The labral refixation reduced labral mobility, which could be beneficial for both pain relief and labral healing to the acetabulum after pincer-type femoroacetabular impingement resection.

Biomechanical Characteristics of Labral Augmentation Versus Labral Reconstruction in a Hip Cadaver Model

Objectives:An integral component of hip stability is the negative pressure gradient created by the labral suction seal. No prior studies have quantitatively compared the integrity of the suction seal under normal, pathologic, and surgical conditions. The purpose of this study was to evaluate the biomechanical properties of the labral suction seal in the following four scenarios: intact labrum, labral tear, labral augmentation, and labral reconstruction.Methods:Eight fresh-frozen hemi-pelvises without osteoarthritis and with an intact labrum were dissected to the level of labrum and mounted for biomechanical testing. Each specimen was evaluated sequentially under four testing conditions: intact labrum, labral tear, labral augmentation, and labral reconstruction. Following testing of the intact labrum, the specimens were manipulated to create a labral tear from 12- to 3-o’clock. Labral augmentation was then performed with bone anchors and iliotibial band graft after debridement of only the peripheral half of the labral tear. Labral reconstruction was performed last with bone anchors and iliotibial band graft after removing the entire labral tear. In each condition the specimens were placed in the test machine to undergo pure distraction of the joint. First, the femur was compressed with 250 N of force and then distracted at 10 mm/s with force and displacement continuously recorded until the suction seal was disrupted. In each specimen, the tests were repeated for a total of three tests in each of the four conditions, and the average peak force was calculated. Data was normalized to the intact peak force for each specimen to account for gender and size differences. Statistical testing was performed via a repeated measures ANOVA with a post hoc Bonferroni correction for pairwise analysis.Results:Peak loads occurred early in displacement. The average peak force values (mean ± standard deviation) were as follows: intact (137.2 ± 40.7), labral tear (126.3 ± 43.5), labral augmentation (94.7 ± 59.7), labral reconstruction (78.9 ± 51.2). The average normalized peak force values relative to the intact condition were as follows: labral tear (91.1 ± 8.5), augmentation (66.1 ± 27.6), and reconstruction (55.6 ± 25.7). There was no statistically significant difference in peak force relative to the intact labrum for the labral tear (p = 0.34). Relative to the labral tear, there was no significant difference in peak force for the augmentation (p = 0.12), but there was a significant decrease in peak force for the reconstruction (p = 0.03).Conclusion:This model provides a new means of quantitatively evaluating the labral suction seal under various normal, pathologic, and surgical conditions. The results show that relative to the labral tear condition, labral augmentation may recreate the labral suction seal better than labral reconstruction. Clinically, these findings suggest augmentation may improve hip stability over labral reconstruction.Figure 1.

Proximal Over-Resection During Femoral Osteochondroplasty Negatively Affects the Distractive Stability of the Hip Joint

Objectives:Hip microinstability is an increasingly recognized source of hip pain and disability. Femoral osteochondroplasty is usually performed with direct visualization through the arthroscope, assisted with repeated fluoroscopic view for orientation and feedback. However, a two-dimensional representation of a three dimensional structure can be misleading compromising the precision of the planned osteochondroplasty. Sometimes the resection can extend proximally into the Femoral Head (FH) diminishing the surface area of the articular cartilage available to be in contact with the labrum, in order to create the suction effect (suction seal) that maintains the stability of the femoral head in the acetabulum. The purpose of the study is to evaluate the role of proximal over-resection of femoral osteochondroplasty in the rotational and distractive stability of the hip joint. We hypothesis that proximal over resection will result in decrease stability, specially at higher degrees of flexion and internal rotation where the contact between labrum and articular cartilage will be lost, and breaking the suction seal.Methods:Six hemi-pelvises were repeatedly tested in the following five conditions: (a) intact, (b) T-capsulotomy, (c) Osteochondroplasty to the level of the physeal scar, followed by a (d) 5mm and (e) 10mm proximal extension of the resection. The pelvis was secured to a metal plate and the distal portion of the femur was potted and attached to a multi-axial hip jig. (Fig.1) Specimens were axially distracted with a load from 0-150N followed by 5Nm of internal and external torque at 0 o, 15 o, 30 o, 60 o, 90o of flexion while the resultant displacement/rotation was recorded using a 3D motion tracking system. Repeated measures ANOVA was used with statistical significance set at p<0.05.Results:Proximal extension of the resection by 5mm and 10mm increased axial instability (decreased force required for hip distraction) at every angle of flexion tested, with the greatest increase observed at higher angles of flexion (60 deg and 90 deg), p<0.05. T-capsulotomy alone increased both internal and external rotation at all angles of flexion, p<0.05. (Fig. 2) Subsequent resection and extension of the resection did not significantly increase rotational instability compared to the capsulotomy state.Conclusion:Extending the osteochondroplasty proximally into the femoral head compromised the distractive stability of the hip joint. It is important to be precise when performing femoral osteochondroplasty to minimize proximal extension that can lead to iatrogenic instability of the hip joint and poor postoperative outcomes.Figure 1.Figure 2.

Comparison of Suction Seal and Contact Pressures Between 270° Labral Reconstruction, Labral Repair, and the Intact Labrum

To biomechanically compare the suction seal, contact area, contact pressures, and peak forces of the intact native labrum, torn labrum, 12- to 3-o'clock labral repair, and 270° labral reconstruction in the hip. A cadaveric study was performed using 8 fresh-frozen hemipelvises with intact labra and without osteoarthritis. Intra-articular pressure maps were produced for each specimen using an electromechanical testing system under the following conditions: (1) intact labrum, (2) labral tear, (3) labral repair between the 12- and 3-o'clock positions, and (4)270° labral reconstruction using iliotibial band allograft. Specimens were examined in neutral position, 20° of extension, and 60° of flexion. In each condition, contact pressure, contact area, and peak force were obtained. Repeated-measures analysis of variance was used to identify differences in biomechanical parameters among the 3 conditions. Qualitative differences in suction seal were compared between labral repair and labral reconstruction using the Fisher exact test. Repeated-measures analysis of variance for contact area in neutral position, extension, and flexion showed statistically significant differences between the normalized study states (P < .05). Post hoc analysis showed significantly larger contact areas measured in labral repair specimens than in labral reconstruction specimens in the extension and flexion positions. Region-of-interest analysis for the normalized contact area in the extension and flexion positions, as well as normalized contact pressures in neutral position, showed statistically significant differences between the labral states (P < .05). Finally, 8 labral repairs (100%) versus only 1 labral reconstruction (12.5%) retained the manually tested suction seal (P < .001). In this invitro biomechanical model, 270° labral reconstruction resulted in decreased intra-articular contact area and loss of suction seal when compared with labral repair. Clinically, labral reconstruction may not restore the biomechanical characteristics of the native labrum as compared with labral repair. Labral reconstruction may result in lower intra-articular hip contact area and loss of suction seal, affecting the native biomechanical function of the acetabular labrum. Further biomechanical studies and clinical studies are necessary to determine whether there are any long-term consequences of 270° labral reconstruction.