Original Research Hip Labral Reconstruction With a Polyurethane Scaffold Restoration of Femoroacetabular Contact Biomechanics Bruno Capurro,*†‡§k PhD, Francisco Reina,§ PhD, Anna Carrera,§ PhD, Joan Carles Monllau,† PhD, Fernando Marqués-López,† PhD, Oliver Marı́n-Peña,k{ PhD, Raúl Torres-Eguı́a,k# MD, and Marc Tey-Pons,†k PhD Investigation performed at the Department of Orthopaedic Surgery and Traumatology, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain Background: Many advances have been made in hip labral repair and reconstruction and in the restoration of the suction seal. Purpose/Hypothesis: The purpose of this study was to evaluate the biomechanical effects of segmental labral reconstruction with a synthetic polyurethane scaffold (PS) in comparison with segmental labrectomy. Our hypothesis was that reconstruction with a icroporous polyurethane implant would normalize joint kinetics of the hip and restore the suction seal. Study Design: Controlled laboratory study. Methods: We used 10 hips from 5 fresh-frozen pelvises with an intact acetabular labrum without osteoarthritis. Using an intra- articular pressure measurement system, the contact area, contact pressure, and peak force were assessed for the following conditions: intact labrum, partial anterosuperior labrectomy, and PS reconstruction. For each condition, all specimens were analyzed in 4 positions (90 of flexion, 90 of flexion and internal rotation, 90 of flexion and external rotation, and 20 of extension) and underwent a labral seal test. The relative change from the intact condition was determined for all conditions and positions. Results: Compared with the intact labrum, labrectomy resulted in a significant decrease in the contact area (P < .001) and a significant increase in the peak force (P < .001) and contact pressure (P < .001) across all positions. Compared with labrectomy, PS reconstruction resulted in a significant increase in the contact area (P < .001) and a significant decrease in the contact pressure (P  .02) and peak force (P < .001) across all positions. Compared with the intact labrum, PS reconstruction restored the contact area and peak force to normal values in all positions (P > .05), whereas the contact pressure was significantly decreased compared with labrectomy (P < .05) but did not return to normal values. The labral seal was lost in all specimens after labrectomy but was restored in 80% of the specimens after PS reconstruction. Conclusion: Femoroacetabular contact biomechanics significantly worsened after partial labrectomy; reconstruction using a PS restored the contact area and peak force to the intact state and improved the contact pressure increases seen after partial lab- rectomy. The contact area and peak force were normalized, and the labral seal was re-established in most cases. Clinical Relevance: This study provides biomechanical evidence for the use of a scaffold for labral reconstruction. Keywords: labral reconstruction; biomechanics; polyurethane scaffold The acetabular labrum plays a crucial role in the stability, attempted with the aim of regaining joint function, decreas- lubrication, and kinematics of the hip joint.2,13,14,16,23,27,29 ing pain, and allowing a return to activities of daily The purpose of hip preservation surgery in the presence of living.2,11,20,22,27,29,43 femoroacetabular abnormalities is to maintain and pre- When labral ruptures occur, the vast majority can be serve the anatomy, correcting morphological alterations addressed with primary repair techniques. With the shift and repairing the labral lesion (when possible instead of in recent decades from debridement to preservation, treat- performing labral debridement). When this repair is not ment methods that are aimed at restoring the negative possible, reconstructing the acetabular labrum should be pressure gradient created by the labral suction seal and improving contact mechanics have become popular.10,13,37 The Orthopaedic Journal of Sports Medicine, 10(9), 23259671221118831 Labral repair has been shown to have better clinical out- DOI: 10.1177/23259671221118831 comes than labrectomy,35 but when repair is not possible, ª The Author(s) 2022 labral reconstruction is indicated.32 Performing allogeneic This open-access article is published and distributed under the Creative Commons Attribution - NonCommercial - No Derivatives License (https://creativecommons.org/ licenses/by-nc-nd/4.0/), which permits the noncommercial use, distribution, and reproduction of the article in any medium, provided the original author and source are credited. You may not alter, transform, or build upon this article without the permission of the Author(s). For article reuse guidelines, please visit SAGE’s website at http://www.sagepub.com/journals-permissions. 1 2 Capurro et al The Orthopaedic Journal of Sports Medicine labral transplantation can achieve good results, but graft lesion were detected radiographically; however, 4 specimens availability from tissue banks may be limited, and sizing (2 pelvises) presented with severe osteochondral damage on may be challenging particularly when a more severe labral direct inspection and were therefore excluded. rupture than expected is diagnosed intraoperatively. In The cadaveric hips were handled following a previously this situation, autografts can be used from the fascia lata described protocol; however, they were not separated, and or hamstring with satisfactory results.24,28 The use of these the pelvises were kept intact.26,44 Briefly, the specimens autografts requires express authorization from the patient were thawed at room temperature for 12 hours, then care- through informed consent and can also lead to possible fully dissected, and all the muscles and soft tissue were morbidity in the donor area and an increase in surgical systematically eliminated. They were then refrozen to be time.2,7,9 thawed on the day of biomechanical testing. After testing, As an alternative to human tissue usage, biodegradable, the pelvises were frozen a third time using the same proto- synthetic, polyethylene scaffolds were developed more col to preserve them for revalidation if necessary. None of than 15 years ago for restoration of the meniscus in the specimens required a third thawing. the knee, with successful results clinically up to 10 years.3,6,15,41 Owing to the abundant vascular supply Biomechanical Testing in the acetabulum,33 integration of the scaffold can be expected. With the lack of compressive and shear forces found in the knee, comparable or superior results may be obtained when implanted in the hip. There were 3 complete pelvises (6 specimens) used for a The objective of this biomechanical study was to evalu- pilot study to test the calibration and sensor positioning ate the effect of reconstruction of an acetabular labral and to refine the reconstruction technique and biomechan- injury, caused by partial anterosuperior labrectomy, using ical workflow. One pelvis (2 specimens) did not allow for an artificial macroporous polyurethane scaffold (PS). Our correct positioning of the sensor because of the small size hypothesis was that partial anterosuperior labrectomy of the acetabulum. These cases were not included in the would decrease the contact area and increase the contact study. This left 5 pelvises (10 hips) remaining for testing. pressure and peak force compared with the intact acetab- The complete pelvis specimens were fixed in an anatomic ular labrum, while reconstruction with a macroporous PS position on a biomechanical testing bench (Figure 1). This would normalize joint kinetics of the hip and restore the bench allows for angular control in the 3 axes of joint labral seal. mobility. In the absence of servomotors for movement con- trol, maximum mobility for each specimen can be achieved. The design and methodology have been previously METHODS described.21,39 Testing was carried out in 3 different clinical situations Specimens for each specimen: (1) with the acetabular labrum intact, (2) after 3 cm–long anterior labrectomy, and (3) after labral The protocol for this study was approved by the ethics com- reconstruction with a PS. mittee of the local university. A total of 22 consecutively Intact Labrum. Although normally carried out arthros- donated deidentified cadaveric hips (11 complete pelvises copically, for the purposes of this study, we performed an and proximal femurs) were obtained from a voluntary open procedure. Wide 360 capsulotomy was performed on human body donation program of the local university, each specimen to 2 mm of the acetabular rim, and the round which complies with all legal and ethical procedures for ligament was sectioned (Figure 2). Visual inspection con- human donation. firmed the integrity of the acetabular labrum and the state The complete pelvises were subjected to a fluoroscopic of the acetabular cartilage. Capsulotomy was carried out examination to confirm that there were no dysplastic hips, to manipulate the acetabular labrum to insert dynamic femoroacetabular impingement, or impairment of the fem- pressure sensors with a semicircle design (model 4400; oral head (Wiberg angle of 25 -40 , alpha angle <55 ) and Tekscan). The sensors were calibrated according to manu- that there was conservation of the joint space (Tönnis facturer guidelines and attached to the capsule and labrum grade <2). No specimens with a severe osteochondral with 3-point capsular sutures (silk 2/0) (Figure 2), *Address correspondence to Bruno Capurro, PhD, Department of Orthopaedic Surgery and Traumatology, Hospital del Mar, Universitat Autònoma de Barcelona, Passeig Marı́tim de la Barceloneta 25, 08003 Barcelona, Spain (email: doctor.capurro@gmail.com) (Twitter: @DrBrunoCapurro). † Department of Orthopaedic Surgery and Traumatology, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain. ‡ Department of Orthopaedic Surgery and Sport Traumatology, ReSport Clinic, Barcelona, Spain. § NEOMA Research Group, Department of Medical Sciences, Universitat de Girona, Girona, Spain. k GIPCA - Grupo Ibérico de cirugı́a Preservación de Cadera, Spain - Portugal. { Department of Orthopaedic Surgery and Traumatology, Hospital Infanta Leonor, Universidad Complutense de Madrid, Madrid, Spain. # Department of Orthopaedic Surgery and Traumatology, Clı́nica CEMTRO, Madrid, Spain. Final revision submitted May 18, 2022; accepted May 26, 2022. The authors declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto. Ethical approval for this study was obtained from Hospital Universitari de Girona Doctor Josep Trueta (No. 2018/8109/I). The Orthopaedic Journal of Sports Medicine Scaffold Labral Reconstruction 3 achieving a static position during testing and allowing for reproducible measurements.31 A precision dynamometer (Digital Force Gauge SF-500; Beslands) was used to ensure that stable pressure was maintained throughout the study for all specimens (maxi- mum load: 500 N/50 kg; load division value: 0.1 N/0.01 kg; inner sensor accuracy: ±0.5%; operating temperature: –15 to 35  C; transport temperature: 23  to 60  C; relative humidity: 15% to 80%). The peak force, contact pressure, and contact area of the acetabular cartilage were measured after the introduction of the femoral head into the acetabular cavity. The same 4 sequences of movement were reproduced for each speci- men. Dynamic testing began from the anatomic position in extension, neutral rotation, and neutral abduction, and progressive flexion was performed to 90 . The joint was then brought to maximum internal rotation (flexion þ IR), followed by maximum external rotation (flexion þ ER) and back to neutral, finishing with an excursion at 20 of extension. The mean of 3 consecutive examinations Figure 1. Schematic diagram of the bench used to secure the was used for each measurement. Movement was carried out specimens. manually, timing and documenting each position. Through- out the study, a constant compressive force of 50 N was applied with the dynamometer, with a variation of ±5 N. Each cycle lasted 30 seconds (±10%). If greater variations in strength or duration occurred, they were discarded and the cycle repeated. Each test was repeated 3 times, and the mean of the results was used (Figure 3). Labrectomy. After testing with the intact native labrum was completed, the pressure sensor was detached from the capsule, and the capsule was retracted laterally. A longitu- dinal labral cut of 3 cm in length in the anterolateral zone was performed with a No. 10 scalpel, leaving a 2-mm lateral margin for later attachment of the scaffold (Figure 4). The sensor was reattached to the capsule and the specimen repositioned on the bench. Testing was performed with the routine described above. PS Reconstruction. After testing in the labrectomy con- dition, the sensor was removed as described above. Recon- struction was carried out with the insertion of a biodegradable, synthetic PS (Actifit; Orteq). This scaffold is highly porous and composed of aliphatic polyurethane (Figure 5). There were three 5-mm anchors (Wedge Anchor II with No. 2 Force Fiber; Stryker) placed every 7 mm in the middle to secure the implant, and 1 side-to-side suture was used to attach the labral remnant at each end (Figure 6). Because of the quality of the bone for specimen 8, an extra anchor was used in the middle of the scaffold. Testing was completed as described above. Labral Seal Testing The suction seal test37 consisted of a qualitative type of Figure 2. Tekscan sensor’s cotyloid cavity attachment after analysis that was performed with the hip in a neutral ana- joint capsule resection and round ligament sectioning to tomic position. After capsulotomy, a section of the round remove the femoral head. Articular cartilage (crescent shape) ligament of the femoral head was rearticulated, and an (a); acetabular labrum (b); distally sectioned round ligament axial distraction force was applied according to Suppauk- (c); acetabular fossa (d); transverse ligament (e); and ischial sorn et al37 and rated qualitatively to see if the seal was tuberosity (f). The numbers show the distribution in zones maintained. Losing the seal or vacuum results in a negative according to the clockface position. sealing pressure that produces an audible sound and 4 Capurro et al The Orthopaedic Journal of Sports Medicine Figure 3. Cycle performed on a biomechanical bench with a 50-N dynamometer fixed intramedullary in the distal femur with K-wire to manipulate rotations: (A) 90 of flexion, (B) 90 of flexion plus maximum internal rotation (arrow), (C) 90 of flexion plus maximum external rotation (arrow), and (D) 20 of extension (arrow). Figure 4. Anterosuperior labrectomy of 3 cm performed on a Figure 5. Macroporous polyurethane implant (Actifit). right hip, with resected labrum (a) and native labrum (b). The number represents the 12-o’clock position. specimen in 3 predetermined clinical situations. When measuring the contact area, normalization of the values dislocation of the hip. If the seal is not maintained, no resis- was necessary, as each hip was of a different size and adap- tance to the distracting force is perceived, nor is the sound tation of the sensor may have been influenced by that dif- heard. This test was performed on all specimens to determine ference. This was achieved by dividing the raw data for if it was present in the intact labrum, after labrectomy, and each value of stage 1 (intact labrum). again after reconstruction with the PS. All labral seal tests PS values were normalized to analyze differences in the were performed by the same investigator (B.C.). peak force, contact area, and contact pressure and were compared with the intact state using measurements from Statistical Analysis the 4 different positions (90 of flexion in neutral, flexion þ IR, flexion þ ER, and 20 of extension). Because multiple We measured quantitative variables: maximum pressure measurements were taken per specimen, normalized determined by the peak force and contact area on the ace- values were modeled using repeated-measures analysis of tabular surface. These 2 parameters were measured in each variance to account for potential correlations within each The Orthopaedic Journal of Sports Medicine Scaffold Labral Reconstruction 5 Figure 6. (A) Reconstruction with a polyurethane implant (specimen 4, left hip) using 3 anchors and 2 side-to-side translabral sutures. (B) Superior and side view of the sensor position fixed with silk sutures. Sup, superior; Med, medial; Lat, lateral, Inf, inferior. specimen. The least squares means and 95% CIs are reconstruction was compared with labrectomy, the reported, along with a P value that reflects the test: H0: values were significantly increased in all positions mean ¼ 1 versus H1: mean 6¼ 1. Statistical significance was (P < .001). set at P < .05 with an alpha error of .05 and an effect size of 0.8. Statistical analyses were performed using SAS Contact Pressure (Version 9.4; SAS Institute). To assess each specific area of the acetabular surface, an The contact pressure increased significantly after partial analysis of the data was carried out for each of the 4 posi- labrectomy compared with the intact labrum in all posi- tions. The peak force, contact area, and contact pressure on tions (P < .001 for all). In flexion, it increased 1.28% (95% the acetabular surface were compared in the following CI, 1.19-1.38); in flexion þ IR, 1.28% (95% CI, 1.19-1.38); in situations: (1) intact labrum versus labrectomy, (2) intact flexion þ ER, 1.32% (95% CI, 1.23-1.42); and in extension, labrum versus PS-reconstructed labrum, and (3) labrect- 1.28% (95% CI, 1.19-1.38). omy versus PS-reconstructed labrum. The relative change Compared with the partial labrectomy state, PS recon- from the intact condition (value of 1) was determined for all struction significantly decreased the contact pressure, but conditions and positions. the values still remained significantly higher than the intact state in all positions (flexion: 11% increase [95% CI, 1.05-1.17]; P ¼ .003) (flexion þ IR: 8% [95% CI, 1.03-1.13]; RESULTS P ¼ .008) (flexion þ ER: 11% [95% CI, 1.04-1.16]; P ¼ .0004) (extension: 12% [95% CI, 1.03-1.21]; P ¼ .02). Figure 7 Contact Area represents a 3-dimensional visualization of the results. In comparison with the intact labrum, labrectomy resulted When comparing the contact pressure of PS reconstruction in a significant decrease in the contact area. In flexion, it with labrectomy, all P values were statistically significant decreased to 82% of normal values (95% CI, 0.77-0.87), in for all positions (P ¼ .02). flexion þ IR to 83% (95% CI, 0.78-0.88), in flexion þ ER to 83% (95% CI, 0.78-0.88), and in extension to 82% (95% CI, Peak Force 0.76-0.86) (P < .001 for all). After labrectomy, which decreased the contact area, PS When comparing the intact labrum with partial labrect- reconstruction restored the contact area to more than 96% omy, the peak force increased significantly in all positions: of the intact labrum in all positions (P > .05), with no sta- 27% (95% CI, 1.19-1.35) in flexion, 25% (95% CI, 1.17-1.33) tistically significant differences found between PS and in flexion þ IR, 22% (95% CI, 1.14-1.29) in flexion þ ER, and native values. In flexion, the contact area was restored to 26% (95% CI, 1.19-1.34) in extension (P < .001 for all). 96% (95% CI, 0.93-1.00; P ¼ .061), in flexion þ IR to 98% When comparing the peak force between the intact (95% CI, 0.94-1.01; P ¼ .187), in flexion þ ER to 98% (95% labrum and PS reconstruction, we observed a recovery of CI, 0.94-1.02; P ¼ .243), and in extension to 97% (95% CI, more than 95% of the peak force, with no statistically 0.93-1.00; P ¼ .076). When the contact area of PS significant differences found. In flexion, the peak force 6 Capurro et al The Orthopaedic Journal of Sports Medicine Figure 7. A 3-dimensional (3D) visualization of contact pressure across all positions. Interpretation of a Tekscan software image, scaled from blue to red, where the areas of least pressure are dark blue and of the highest pressure are red. ER, external rotation; IR, internal rotation. decreased to 5% above normal values (95% CI, 0.99-1.11; restored joint kinematics to that of the intact labrum, P ¼ .07) from the labrectomy state; in flexion þ IR, it restoring the contact area and peak force back to normal decreased to 3% (95% CI, 0.99-1.07; P ¼ .20), in flexion þ and improving the contact pressure closer to normal than ER to 2% (95% CI, 0.99-1.05; P ¼ .26), and in extension to the partial labrectomy state. Labral reconstruction with a 4% (95% CI, 1.00-1.08; P ¼ .07). When comparing the peak PS restored the labral seal in the majority of cases. force of PS reconstruction with labrectomy, the differences In anatomic studies, the acetabular labrum increased the were statistically significant for all positions (P < .001). contact area of the cotyloid cavity by 28%.38 This increases In summary, reconstruction with a synthetic PS signifi- congruence and joint stability, allowing the correct distri- cantly increased the contact area (P < .001) and signifi- bution of loads while reducing contact pressure and stress cantly decreased both the contact pressure (P  .02) and in the joint cartilage.5 In all measurements made in this peak force (P < .001) compared with the effects caused by biomechanical study, partial anterosuperior labrectomy partial labrectomy, bringing the alteration in joint kinemat- decreased the contact area from normal, on average, to ics closer to the intact condition. Box plots for all procedures 82%. It is interesting to note that despite being partial ante- and conditions can be found in Figure 8. rosuperior labrectomy of 3 cm, it produced a decrease in the contact area similar to that of total labrectomy that was Labral Seal reported in a previous study.39 PS reconstruction managed to increase the contact area after labrectomy by normaliz- The labral seal was preserved in 100% of the intact labrum ing that parameter relative to the intact labrum. Our specimens but was lost in 100% of cases after labrectomy. results showed that reconstruction with a PS re- The seal was restored in 80% of the specimens after PS established the contact area and normalized intra- reconstruction. articular stress, which was consistent with the cadaveric study by Philippon et al,29 demonstrating that labral recon- DISCUSSION struction produced improvements in the hip joint’s contact area and contact pressure compared with labral resection. The most important finding of this study was that partial One of the main functions of the labrum is to distribute reconstruction of the labrum with a macroporous PS pressures in the femoroacetabular joint.25 In vivo and in The Orthopaedic Journal of Sports Medicine Scaffold Labral Reconstruction 7 Figure 8. Box plots showing the distribution of (A) contact area, (B) contact pressure, and (C) peak force by procedure and position compared with normal (1.0). Lab, labrectomy; Nor, normal; PS, polyurethane scaffold. vitro biomechanical studies have shown that the intact improve the distracting stability of the hip fluid seal. Ejnis- labrum allows direct pressure loads from solid-to-solid and man et al12 demonstrated that incorporation of the allograft interstitial fluid to be evenly distributed within the femoro- and maintenance of the suction seal in the joint were acetabular joint.14 This is corroborated by the results of this obtained. To analyze this scenario in depth, Suppauksorn study, which showed that the intra-articular contact pres- et al37 compared the results of primary labral repair of an sure increased significantly after partial anterosuperior anterosuperior lesion and 270 allograft reconstruction in 8 labrectomy compared with the intact labrum and that the cadaveric specimens. They found that when reconstruction contact pressure decreased significantly with PS recon- was performed at 270 , there was a decrease in the intra- struction. Although reconstruction decreased the contact articular contact area and a greater loss of the labral seal pressure, it did not return to normal values of the intact compared with labral repair. With the “suction seal test” labrum. that they described, 100% of the specimens with labral There is a relationship between increased stress forces repair recovered the seal compared with only 22.5% with and damage to the chondral surface, which has been 270 reconstruction. Our results using the same labral seal described as an independent risk factor of osteoarthritis.17 test showed that the labral seal after wide capsulotomy was Areas of cartilage exposed to higher loads may have an maintained in 100% of the intact labrum specimens, that increased risk of damage and a reduced ability to effectively 100% of specimens after partial labrectomy lost their labral distribute loads during movement.18 Shi et al34 reported seal, but that it was re-established in 80% of specimens that labral reconstruction with an autograft in a porcine after reconstruction with the PS. Unlike the study of Sup- model provides benefits in terms of reducing the develop- pauksorn et al, our study analyzed reconstruction after 3- ment of osteoarthritis compared with labral resection. They cm partial anterosuperior labrectomy, not total labrectomy concluded that the development of osteoarthritis can be after 270 reconstruction. This could explain the difference attenuated by labral reconstruction, contributing to homeo- between our 80% recovery of the seal and their 22.5% rate stasis of the hip joint. 34 In this study, the peak force with reconstruction at 270 . Based on these results, it could increased significantly after partial labrectomy but be suggested that it is better to perform partial reconstruc- decreased significantly after reconstruction with the PS to tion rather than 270 reconstruction to recover the labral approximately 95% of normal values. While not normaliz- seal function. ing the contact pressure to the intact state, if it manages to restore the peak force close to normal, a decrease in ele- Limitations vated tissue deformation and shear forces that produce fibrillation and chondral delamination could occur,4 which There are limitations to our study. Although the initial may attenuate the progression of osteoarthritis. sample size was 22 specimens, only 10 specimens were The positions of 90 of flexion, 20 of extension, and max- included in the biomechanical study. This was a relative imum internal and external rotation at 90 of flexion were limitation, as most sample sizes in biomechanical cadaveric chosen with the aim of analyzing whether joint kinetics studies are 5 to 10 specimens.1,36,37,39 The Tekscan sensors could be reconstructed throughout the cone of circumduc- utilized in this study were specifically designed for use in tion of the enarthrosis.19 In the range of motion that we the hip. They are arranged in a semicircle and connected by studied, reconstruction with a PS after labrectomy normal- USB to a computer. Their 5 connectors are approximately ized the contact area, contact pressure, and peak force. We 1 cm wide and are separated by 1.5 cm. This requires wide also observed that labral reconstruction restored joint capsulotomy with a section of the ligamentum teres to be kinetics in internal and external rotation at 90 . able to insert and fix the sensor in the required position, Biomechanical cadaveric studies have shown that simu- which may affect the study in terms of the distribution of lated labral injury or resection conditions decrease the loads and the subjectivity of the suction seal test. However, pressurization of intra-articular fluid29 and decrease dis- this was not considered a significant limitation, as we com- traction resistance27 but that repair and reconstruction pared 3 clinical conditions with the same instability that is 8 Capurro et al The Orthopaedic Journal of Sports Medicine produced by total capsulotomy. The hip joint is a system 5. Buckwalter JA, Mankin HJ, Grodzinsky AJ. Articular cartilage and that requires the capsule to maintain joint liquid. Despite osteoarthritis. Instr Course Lect. 2005;54:465-480. 6. Condello V, Dei Giudici L, Perdisa F, et al. Polyurethane scaffold having lubricated the cartilage with saline and cadaveric implants for partial meniscus lesions: delayed intervention leads to fat, it may not have remained in the same condition as an inferior outcome. Knee Surg Sports Traumatol Arthrosc. 2021; normal. Pressures measured in the study may differ from 29(1):109-116. those measured in a surgical setting, making the raw value 7. Cooper JD, Dekker TJ, Ruzbarsky JJ, et al. Autograft versus allograft: of the data not transferable. However, this bias is under- the evidence in hip labral reconstruction and augmentation. Am J stood in all cadaveric biomechanical studies with a similar Sports Med. 2021;49(13):3575-3581. study protocol.21,27,29,37,40 The biomechanical bench used in 8. de Caro F, Perdisa F, Dhollander A, Verdonk R, Verdonk P. Meniscus scaffolds for partial meniscus defects. Clin Sports Med. 2020;39(1): this study permitted the specimens to be placed in an ana- 83-92. tomic position and allowed for unlimited hip range of 9. DeFroda SF, Kester BS, Clapp IM, Newhouse AC, Nho SJ. Arthro- motion, with analog control of all angles of motion. The scopic treatment of femoroacetabular impingement using labral angular measurements were made on that bench with a reconstruction with capsular autograft. Arthrosc Tech. 2021;10(10): visual analog system; however, angular measurements can e2375-e2381. sustain a bias. A goal in this study was to standardize range 10. Dwyer MK, Jones HL, Field RE, McCarthy JC, Noble PC. Femoroace- of motion for each specimen, limiting the differences among tabular impingement negates the acetabular labral seal during pivot- ing maneuvers but not gait. Clin Orthop Relat Res. 2015;473(2): the specimens. Finally, the PS used in this study was devel- 602-607. oped for meniscal replacement in the knee but was adapted 11. Ejinsman L, Philippon MJ. Arthroscopic labral reconstruction in the to the hip. Although there are clinical and histological stud- hip using iliotibial band autograft. Oper Tech Sports Med. 2011;19(2): ies of this implant that show that it integrates well in the 134-139. knee and no inflammatory response has been reported up to 12. Ejnisman L, Philippon MJ, Lertwanich P. Acetabular labral tears: diag- 10 years,8,30,41,42 it is largely unknown how this implant nosis, repair, and a method for labral reconstruction. Clin Sports Med. 2011;30(2):317-329. will act in the hip. We are limited, at present, by the study 13. Ferguson SJ, Bryant JT, Ganz R, Ito K. An in vitro investigation of the of Tey-Pons et al,39,40 who observed good clinical outcomes acetabular labral seal in hip joint mechanics. J Biomech. 2003;36(2): at 4 years’ follow-up and no progression to osteoarthritis 171-178. using the same scaffold as in this study. 14. 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(8):953-960. CONCLUSION 15. Figueroa D, Figueroa F, Calvo R, Gomez C, Vaisman A. Meniscal polyurethane scaffold plus cartilage repair in post meniscectomy syn- The biomechanical effects of a synthetic PS for labral recon- drome patients without malalignment improves clinical outcomes at struction are described for the first time. Femoroacetabular mid-term follow-up. J Clin Orthop Trauma. 2020;15:16-21. 16. Greaves LL, Gilbart MK, Yung AC, Kozlowski P, Wilson DR. Effect of contact biomechanics significantly worsened after partial acetabular labral tears, repair and resection on hip cartilage strain: a labrectomy; reconstruction with a PS restored the contact 7T MR study. J Biomech. 2010;43(5):858-863. area and peak force to the intact state and improved the 17. Hadley NA, Brown TD, Weinstein SL. 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