Biomechanical evaluation contribution of the acetabular labrum to hip stability

Hip Labral and Capsular Repair Are Unable to Restore Distractive Stability in a Biomechanical Model

PURPOSE

To evaluate the change in hip distractive stability after a capsulotomy, labral tear, and simultaneous repair of both the capsule and the labrum in a biomechanical model.

METHODS

Ten fresh-frozen human cadaveric hips were analyzed using a materials testing system to measure the distractive force and distance required to disrupt the hip suction seal under the following conditions: (1) native intact capsule and labrum, (2) 2- or 4-cm interportal capsulotomy (IPC), (3) labral tear, (4) T extension, (5) labral repair, (6) T extension repair, and (7) IPC repair. Each specimen was retested at 0° of flexion, 45° of flexion, and 45° of flexion with 15° of internal rotation.

RESULTS

A significantly higher distractive force was required to rupture the suction seal in the intact condition compared with IPC (P = .012; 95% confidence interval [CI], 4.9-42.4); IPC and labral tear (P = .002; 95% CI, 11.3-49.4); IPC, labral tear, and T extension (P = .001; 95% CI, 13.9-51.5); IPC, labral repair, and T extension (P < .001; 95% CI, 20.8-49.7); IPC, labral repair, and T extension repair (P = .002; 95% CI, 12.5-52.4); and IPC repair, labral repair, and T extension repair (P = .01; 95% CI, 5.8-46.1). The IPC condition required a higher distractive force in isolation than when combined with a labral tear (P = .14; 95% CI, 1.2-12.0), T extension (P = .005; 95% CI, 2.8-15.3), or labral repair (P = .002; 95% CI, 4.4-18.8).

CONCLUSIONS

The distractive resistance of an intact hip capsule and labrum was not restored once the soft tissues were violated, despite labral repair with a loop technique and capsular repair with interrupted figure-of-8 sutures.

CLINICAL RELEVANCE

Time-zero complete capsular repair with concomitant labral repair may not be adequate to restore distractive hip stability after hip arthroscopy, reinforcing the use of postoperative precautions in the early postoperative period.

The Contribution of Soft Tissue and Bony Stabilizers to the Hip Suction Seal: A Systematic Review of Biomechanical Studies

BACKGROUND

Previous biomechanical studies have identified capsular closure, labral repair or reconstruction, and osteochondroplasty as important surgical interventions to improve hip stability.

PURPOSE

To investigate the outcome metrics used to quantify hip stability and assess and measure the relative contributions of the labrum, capsule, and bone to hip stability through a quantitative analysis.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

PubMed and Embase databases were searched using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies evaluated cadaveric hip biomechanics related to capsular, labral, and bony management during hip arthroscopy. Studies were assessed for distraction force and distance, fluid measures, and contact forces used to quantify the suction seal. Exclusion criteria included open surgery, arthroplasty, reorientation osteotomy, or traumatic dislocation.

RESULTS

A total of 33 biomechanical studies comprising 322 hips that evaluated 1 or more of the following were included: distraction force or distance (24 studies), fluid measures (10 studies), and contact forces (6 studies). Compared with a capsulotomy or capsulectomy, capsular repair or reconstruction demonstrated greater resistance to distraction (standardized mean difference [SMD], 1.13; 95% CI, 0.46-1.80; P = .0009). Compared with a labral tear, a labral repair or reconstruction demonstrated less resistance to distraction (SMD, -0.67; 95% CI, -1.25 to -0.09; P = .02). Compared with a labral debridement, repair or reconstruction demonstrated greater resistance to distraction (SMD, 1.74; 95% CI, 1.23 to 2.26; P < .00001). No quantitative analysis was feasible from studies evaluating the effect of osseous resection due to the heterogeneity in methodology and outcome metrics assessed.

CONCLUSION

Most biomechanical evidence supports capsulotomy repair or reconstruction to improve hip distractive stability at the end of hip arthroscopic surgery. While the repair of a torn labrum does not improve distractive resistance, it is superior to labral debridement in most biomechanical studies.

Acetabular Labral Reconstruction Does Not Demonstrate Superior Biomechanical Properties Compared to Labral Repair or Intact Native Labrum but Is Superior to Labral Excision: A Systematic Review of Cadaveric Studies

PURPOSE

To systematically review and compare biomechanical properties of labral reconstruction to labral repair, intact native labrum, and labral excision in cadaveric studies.

METHODS

A search of the PubMed and Embase databases was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and checklist. Cadaveric studies focused on hip biomechanics related to intact labrum, labral repair, labral reconstruction, labral augmentation, and labral excision were included. Investigated parameters included biomechanical data measures, such as distraction force, distance to suction seal rupture, peak negative pressure, contact area, and fluid efflux. Review articles, duplicates, technique reports, case reports, opinion articles, articles written in a language other than English, clinical studies focusing on patient-reported outcomes, studies performed in animals, and articles with no abstract available were also excluded.

RESULTS

Fourteen cadaveric biomechanical studies were included that compared labral reconstruction to labral repair (4 studies), labral reconstruction to labral excision (4 studies); and evaluation of distractive force of the labrum (3 studies), the distance to suction seal rupture (3 studies), fluid dynamics (2 studies), displacement at peak force (1 study), and stability ratio (1 study). Data pooling was not performed because of methodological heterogenicity of the studies. Labral reconstruction did not outperform labral repair in restoring the hip suction seal or any other biomechanical property. Labral repair significantly prevented greater fluid efflux when compared to labral reconstruction. Labral repair and reconstruction improved the distractive stability of the hip fluid seal from the labral tear and labral excision stage, respectively. Furthermore, labral reconstruction demonstrated to have better biomechanical properties than labral excision.

CONCLUSIONS

In cadaveric studies, labral repair or intact native labrum was biomechanically more superior than labral reconstruction; however, labral reconstruction can restore acetabular labral biomechanical properties and was biomechanically superior to labral excision.

CLINICAL RELEVANCE

In cadaveric models, labral repair outperforms segmental labral reconstruction in preserving the hip suction seal; nonetheless, segmental labral reconstruction biomechanically outperforms labral excision at time 0.

Best practice guidelines for clinical and radiological assessment of patients with femoroacetabular impingement. Results from the ISHA International Delphi Consensus Project-Phase 2

In 2018, the International Society for Hip Preservation Surgery (ISHA) initiated a series of Delphi consensus studies to identify the global hip preservation community's current opinion on best practices for different facets of hip preservation surgery. Arthroscopic procedures to treat hip pathologies, such as femoroacetabular impingement syndrome (FAIS) are now established in mainstream orthopaedic practice. This study establishes recommendations for the investigation of patients with suspected FAIS. The investigation has focused on the three phases of the diagnostic process-patient history, physical examination and special investigations. Our expert panel consisted of 174 international orthopaedic surgeons with expertise in hip preservation surgery, thereby making recommendations generalisable across the globe. After three rounds of survey and analysis with 174 participants per round, our study achieved consensus at a minimum agreement threshold of 80.0% on 55 statements pertaining to the assessment of patients with FAIS. We encourage our junior and senior hip arthroscopy colleagues internationally to consider these statements both to standardize the clinical and radiological assessment of patients with FAIS and to aid in the design of future research.

Joint instability in patients with borderline developmental dysplasia of the hip

BACKGROUND

The treatment strategy for developmental dysplasia of the hip is determined based on the lateral center-edge angle. Nonetheless, an evaluation of joint instability may be important in determining the treatment strategy. This study classified the displacement patterns of the femoral head center during hip abduction.

METHODS

Ten patients with borderline developmental dysplasia of the hip, 10 patients with developmental dysplasia of the hip, and 10 patients with normal hips were analyzed. Image matching was performed using X-ray images of hip abduction with a three-dimensional hip model. The displacement of the femoral head center and its trajectory length were measured. A cluster analysis was conducted to classify the displacement pattern of the femoral head center, and trajectory lengths were compared.

FINDINGS

Displacement was classified into three patterns: medialization, hinge abduction, and centering. Patients with borderline developmental hip dysplasia exhibited all three patterns. Almost all patients with developmental dysplasia of the hip showed medialization and hinge abduction, whereas all normal patients had the centering type. The mean trajectory length indices for the medialization and hinge abduction types were significantly longer than those for the centering type (P = 0.01 and P = 0.016, respectively).

INTERPRETATION

Borderline developmental dysplasia of the hip is a heterogeneous condition characterized by varying hip instability levels. Our findings suggest that uniform evaluation based on the lateral center-edge angle is inappropriate and that joint instability must be evaluated in each patient with borderline developmental dysplasia of the hip.

Effects of different pelvic osteotomies on acetabular morphology in developmental dysplasia of hip in children

Developmental dysplasia of hip seriously affects the health of children, and pelvic osteotomy is an important part of surgical treatment. Improving the shape of the acetabulum, preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies. Re-directional osteotomies, reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy. The influence of different pelvic osteotomy on acetabular morphology is different, and the acetabular morphology after osteotomy is closely related to the prognosis of the patients. But there lacks comparison of acetabular morphology between different pelvic osteotomies, on the basis of retrospective analysis and measurable imaging indicators, this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.

The Cartilage Protective Effect of Labrum Reconstruction Using Meniscus Allograft Compared with Labrum Resection in a Porcine Model

PURPOSE

This study aimed to verify the femoral head cartilage protective effect of labral reconstruction in a porcine model.

METHODS

Twelve pigs (24 hips) were divided into 3 groups: labrum defect group, lateral meniscus (LM) allograft group, and LM allograft wrapped with acellular peritoneum matrix (LM-APM) group before undergoing bilateral hip surgery. The pigs were sacrificed at 12 and 24 weeks postoperatively, while the femoral head cartilage was retrieved and then subjected to imaging measurement, macroscopic observations, and biomechanical and histological assessment.

RESULTS

Imaging measurement and macroscopic observations revealed that the defect area of the labrum was filled in LM and LM-APM allograft groups after 24 weeks, whereas the labrum defect remained at 24 weeks in the control group. The femoral head cartilage corresponding to the area of labral resection in the labral defect group had worse macroscopic Osteoarthritis Research Society International (OARSI) scores, uneven and discontinuous cartilage on hematoxylin and eosin (H&E) staining and Safranin O staining, decreased histopathology OARSI Osteoarthritis Cartilage Histopathology Assessment System (OOCHAS) scores, and decreased elastic modulus and hardness at 12 and 24 weeks after surgery compared with the meniscus allograft groups.

CONCLUSION

This study demonstrated that the LM allograft with or without APM for labral reconstruction had a chondroprotective effect on the femoral head in a porcine model.

Allograft reconstruction of acetabular labrum has comparable outcomes to labral refixation

The acetabular labrum plays an important role in hip stability, intra-articular fluid pressurization and force distribution. For irreparable labral pathology, labral reconstruction is an increasingly adopted technique shown to decrease hip pain and improve function. We evaluated survivorship and clinical outcomes of allograft labral reconstruction using the mini-open anterior surgical approach. Twelve patients who underwent labral reconstruction using a semitendinosus tendon allograft (reconstruction group) were matched 1:3 based on age, gender, body mass index, year of surgery, preoperative Tönnis grade, previous hip surgery, residual hip pathology and extent of acetabular chondral lesion to a control group of 36 patients who underwent direct labral repair with anchors (refixation group). At a minimum follow-up of 2 years, patient-reported outcomes, radiological findings and failure rates were compared. The average age was 31.3 years (±13.6) for reconstruction and 34.7 (±10.2) for refixation. Both groups had similar preoperative symptomatic periods (P = 0.3), prevalence of residual hip pathology (P = 1.0) and prevalence of prior hip surgeries (P = 1.0). both groups had a significant improvement of modified Harris Hip scores and 36-Item Short-Form Health Survey physical scores. There was no statistically significant difference in conversion rates to total hip arthroplasty (25% versus 8.3%, P = 0.2); however, time to conversion was significantly longer in the reconstruction group (3.58 years ±1.04) compared to the refixation group (1.20 years± 0.93; P = 0.04). In conclusion, at a minimum of 2 years of follow-up, mini-open labrum reconstruction for severe insufficiency of acetabular labrum demonstrated comparable improvements in functional outcomes and significantly longer survivorship compared to labral refixation.

Pathways to primate hip function

Understanding how diverse locomotor repertoires evolved in anthropoid primates is key to reconstructing the clade's evolution. Locomotor behaviour is often inferred from proximal femur morphology, yet the relationship of femoral variation to locomotor diversity is poorly understood. Extant acrobatic primates have greater ranges of hip joint mobility-particularly abduction-than those using more stereotyped locomotion, but how bony morphologies of the femur and pelvis interact to produce different locomotor abilities is unknown. We conducted hypothesis-driven path analyses via regularized structural equation modelling (SEM) to determine which morphological traits are the strongest predictors of hip abduction in anthropoid primates. Seven femoral morphological traits and two hip abduction measures were obtained from 25 primate species, split into broad locomotor and taxonomic groups. Through variable selection and fit testing techniques, insignificant predictors were removed to create the most parsimonious final models. Some morphological predictors, such as femur shaft length and neck-shaft angle, were important across models. Different trait combinations best predicted hip abduction by locomotor or taxonomic group, demonstrating group-specific linkages among morphology, mobility and behaviour. Our study illustrates the strength of SEM for identifying biologically important relationships between morphology and performance, which will have future applications for palaeobiological and biomechanical studies.

Previous Arthroscopic Hip Surgery Increases Axial Distractibility Compared to the Native Contralateral Hip and May Suggest Instability

PURPOSE

To compare intraoperative hip joint distractibility between hips that previously underwent arthroscopic surgery and the contralateral hip with no history of surgical manipulation.

METHODS

Patients undergoing revision hip arthroscopy between April 2019 and December 2020, who previously underwent arthroscopic hip surgery for femoroacetabular impingement syndrome, were prospectively enrolled. Exclusion criteria were any contralateral hip surgery. Before instrumentation, fluoroscopic images of both hips were obtained at 25 lbs traction intervals up to 100 lbs. Total joint space was measured at each traction interval. Distraction was calculated as the difference between the baseline joint space and the total joint space at each subsequent traction interval. Wilcoxon signed ranks tests and McNemar tests were used to compare distraction between revision and native contralateral hips.

RESULTS

Forty-seven patients were included. Mean distraction of operative hips was significantly greater than mean distraction of nonoperative hips at traction intervals of 50 lbs (2.13 vs 1.04 mm, P = .002), 75 lbs (6.39 vs 3.70 mm, P < .001), and 100 lbs (8.24 vs 5.39, P < .001). Mean total joint space of operative hips was significantly greater than mean total joint space of nonoperative hips at traction intervals of 50 lbs (6.60 vs 5.39 mm, P < .001), 75 lbs (10.86 vs 8.05 mm, P < .001), and 100 lbs (12.73 vs 9.73, P < .001). A greater percentage of operative hips achieved all distraction thresholds, in 2-mm intervals up to 10-mm, at each traction interval.

CONCLUSIONS

In the majority of patients undergoing revision hip arthroscopy, previous arthroscopic hip surgery increases axial distractibility of the hip joint compared with the native contralateral hip at axial traction forces of 50-100 lbs. Increased axial distractibility following hip arthroscopy may be suggestive of hip instability and can be assessed on a stress examination with the patient under anesthesia.

LEVEL OF EVIDENCE

III, case-control study.

How Does Chondrolabral Damage and Labral Repair Influence the Mechanics of the Hip in the Setting of Cam Morphology? A Finite-Element Modeling Study

BACKGROUND

Individuals with cam morphology are prone to chondrolabral injuries that may progress to osteoarthritis. The mechanical factors responsible for the initiation and progression of chondrolabral injuries in these individuals are not well understood. Additionally, although labral repair is commonly performed during surgical correction of cam morphology, the isolated mechanical effect of labral repair on the labrum and surrounding cartilage is unknown.

QUESTION/PURPOSES

Using a volunteer-specific finite-element analysis, we asked: (1) How does cam morphology create a deleterious mechanical environment for articular cartilage (as evaluated by shear stress, tensile strain, contact pressure, and fluid pressure) that could increase the risk of cartilage damage compared with a radiographically normal hip? (2) How does chondrolabral damage, specifically delamination, delamination with rupture of the chondrolabral junction, and the presence of a chondral defect, alter the mechanical environment around the damage? (3) How does labral repair affect the mechanical environment in the context of the aforementioned chondrolabral damage scenarios?

METHODS

The mechanical conditions of a representative hip with normal bony morphology (characterized by an alpha angle of 37°) and one with cam morphology (characterized by an alpha angle of 78°) were evaluated using finite-element models that included volunteer-specific anatomy and kinematics. The bone, cartilage, and labrum geometry for the hip models were collected from two volunteers matched by age (25 years with cam morphology and 23 years with normal morphology), BMI (both 24 kg/m2), and sex (both male). Volunteer-specific kinematics for gait were used to drive the finite-element models in combination with joint reaction forces. Constitutive material models were assigned to the cartilage and labrum, which simulate a physiologically realistic material response, including the time-dependent response from fluid flow through the cartilage, and spatially varied response from collagen fibril reinforcement. For the cam hip, three models were created to represent chondrolabral damage conditions: (1) "delamination," with the acetabular cartilage separated from the bone in one region; (2) "delamination with chondrolabral junction (CLJ) rupture," which includes separation of the cartilage from the labrum tissue; and (3) a full-thickness chondral defect, referred to throughout as "defect," where the acetabular cartilage has degraded so there is a void. Each of the three conditions was modeled with a labral tear and with the labrum repaired. The size and location of the damage conditions simulated in the cartilage and labrum were attained from reported clinical prevalence of the location of these injuries. For each damage condition, the contact area, contact pressure, tensile strain, shear stress, and fluid pressure were predicted during gait and compared.

RESULTS

The cartilage in the hip with cam morphology experienced higher stresses and strains than the normal hip. The peak level of tensile strain (25%) and shear stress (11 MPa) experienced by the cam hip may exceed stable conditions and initiate damage or degradation. The cam hip with simulated damage experienced more evenly distributed contact pressure than the intact cam hip, as well as decreased tensile strain, shear stress, and fluid pressure. The peak levels of tensile strain (15% to 16%) and shear stress (2.5 to 2.7 MPa) for cam hips with simulated damage may be at stable magnitudes. Labral repair only marginally affected the overall stress and strain within the cartilage, but it increased local tensile strain in the cartilage near the chondrolabral junction in the hip with delamination and increased the peak tensile strain and shear stress on the labrum.

CONCLUSION

This finite-element modeling pilot study suggests that cam morphology may predispose hip articular cartilage to injury because of high shear stress; however, the presence of simulated damage distributed the loading more evenly and the magnitude of stress and strain decreased throughout the cartilage. The locations of the peak values also shifted posteriorly. Additionally, in hips with cam morphology, isolated labral repair in the hip with a delamination injury increased localized strain in the cartilage near the chondrolabral junction.

CLINICAL RELEVANCE

In a hip with cam morphology, labral repair alone may not protect the cartilage from damage because of mechanical overload during the low-flexion, weightbearing positions experienced during gait. The predicted findings of redistribution of stress and strain from damage in the cam hip may, in some cases, relieve disposition to damage progression. Additional studies should include volunteers with varied acetabular morphology, such as borderline dysplasia with cam morphology or pincer deformity, to analyze the effect on the conclusions presented in the current study. Further, future studies should evaluate the combined effects of osteochondroplasty and chondrolabral treatment.

Arthroscopic Debridement Versus Refixation of the Acetabular Labrum Associated With Femoroacetabular Impingement: Updated Mean 7-Year Follow-up

BACKGROUND

Short- and midterm follow-up studies suggest that arthroscopic labral refixation/preservation leads to superior outcomes compared with labral excision/debridement.

PURPOSE

To update the previous early (16 months) and midterm (mean, 42 months) follow-up of this cohort, which reported better patient-reported outcome measures and lower failure rates in the repair/refixation group.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The authors identified patients who underwent labral debridement/focal labral excision during a period before the development of labral repair techniques. A consecutive group of patients within the labral debridement group thought to be repairable with the authors' current arthroscopic techniques were compared with a group of consecutive patients who underwent labral repair/refixation. In 46 hips, the labrum was focally excised/debrided consistent with pincer- or combined pincer- and cam-type impingement; in 54 hips, the labrum was repaired/refixed. Subjective outcomes were measured with the modified Harris Hip Score (mHHS), 12-Item Short Form Health Survey (SF-12), and visual analog scale (VAS) for pain preoperatively and postoperatively.

RESULTS

The mean age was 34.0 years in the debridement group and 28.3 years in the repair/refixation group, with a mean follow-up of 7.3 years (range, 2-13.6 years). At the mean follow-up of 7.3 years, subjective outcomes were significantly improved (P < .01) for both groups compared with preoperative scores. The mHHS (P = .008), SF-12 score (P = .012), and VAS pain score (P = .002) were all significantly better for the repair/refixation group compared with the debridement group. Although most recent outcomes for both groups fell slightly at the mean follow-up of 7.3 years in comparison with the 16-month and 3.5-year follow-ups, these differences were not significant. However, the failure rate in the debridement group did get significantly worse (P = .014). Good to excellent results were 47.7% in the debridement group and 86.3% in the refixation group (P < .001), and failure rates were 30.4% (debridement) and 13% (refixation) (P = .033). There were 4 revisions in the debridement group and 3 revisions in the refixation group.

CONCLUSION

Longer term, >7-year follow-up comparing focal labral excision/debridement with repair/refixation revealed better patient-reported outcomes and lower failure rates in the labral repair/refixation cohort. Additionally, despite an absolute decrease in patient-related outcome scoring and number of good/excellent results in both groups compared with the 3.5-year report, there was a significantly greater increase in failure rates over time for the excision/debridement group with better maintenance of good to excellent results in the repair/refixation group.

Acetabular labral tears in the adolescent athlete: results of a graduated management protocol from therapy to arthroscopy

This study sought to determine outcomes of a graduated management protocol from therapy to arthroscopy for adolescents presenting with hip pain and an associated acetabular tear. Thirty-seven hips with an MRI confirmed labral tear were prospectively enrolled in a graduated management protocol created for adolescents. The protocol began with activity modification and focused physical therapy. Patients with persistent symptoms were offered an intraarticular corticosteroid injection. Those with continued symptoms were treated with arthroscopic surgery. The modified Harris hip score (mHHS) and nonarthritic hip score (NAHS) were recorded at the initial visit. Patients were contacted by telephone at 1, 2, and 5 years from enrollment for repeat assessment with mHHS and NAHS. At presentation, the mean mHHS and NAHS for the entire cohort was 66.4  ±  11.4 and 70.2  ±  12.6, and these values improved significantly to 89.3  ±  10.6 and 87.0  ±  11.4 at a mean follow-up of 35.7  ±  18.3 months (range 11.7-64.4 months). Forty-two percent of hips were managed with physical therapy and activity modifications alone, 28% of hips progressed to a steroid injection but did not require surgery, and 31% required arthroscopic intervention. Seventy-three percent of hips treated with activity modification alone, 80% treated with an injection, and 82% of hips treated with arthroscopic repair met the minimal clinically significant difference (MCID) (P = 0.859). At an average of 36 months follow-up, the majority (78%) of adolescent patients with an acetabular labral tear will achieve the MCID utilizing a graduated management protocol.

Minimum 2-Year Functional Outcomes of Patients Undergoing Capsular Autograft Hip Labral Reconstruction

BACKGROUND

There is a paucity of literature on arthroscopic capsular autograft labral reconstruction.

PURPOSE

To report midterm functional outcomes for patients undergoing acetabular labral repair with capsular autograft labral reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This is a retrospective case series of prospectively collected data on patients who underwent arthroscopic acetabular labral repair by the senior surgeon between March 2013 and August 2018. The inclusion criteria for this study were adult patients aged 18 years or older who underwent primary hip arthroscopy for arthroscopic capsular autograft labral reconstruction. Exclusion criteria were <2 years of postoperative follow-up, elective disenrollment from study before 2-year follow-up, or repeat ipsilateral hip surgery before 2-year follow-up. Intraoperatively, patients underwent capsular autograft hip labral reconstruction if they were found to have a labrum with hypoplastic tissue (width <5 mm), complex tearing, or frank degeneration of native tissue. Clinical outcome data consisted of patient-reported outcome measures.

RESULTS

A total of 97 hips (94 patients) met the inclusion criteria with a mean final follow-up of 28.2 months (95% CI, 26.0-30.4). Patients had a mean age of 39.0 years (95% CI, 36.8-41.2) with a mean body mass index of 25.8 (95% CI, 24.9-26.7). When compared with baseline (40.4 [95% CI, 36.7-44.2]), the mean international Hip-Outcome Tool-33 (iHOT-33) scores were significantly greater at 3-month (60.9 [95% CI, 56.8-64.9]; P < .001), 6-month (68.8 [95% CI, 64.7-72.9]; P < .001), 12-month (73.2 [95% CI, 68.9-77.5]; P < .001), and final (76.6 [95% CI, 72.4-80.8]; P < .001) follow-up. At 2-year follow-up, 76.3%, 65.5%, and 60.8% of patients' iHOT-33 scores exceeded clinically meaningful outcome thresholds for minimally clinically important difference (MCID), patient-acceptable symptomatic state, and substantial clinical benefit, respectively.

CONCLUSIONS

In this study of 97 hips undergoing arthroscopic labral repair with capsular autograft labral reconstruction, we found favorable outcomes that exceeded the MCID thresholds in the majority of patients at a mean 28.2 months' follow-up. Future studies should compare outcomes between this technique and other methods of autograft and allograft reconstruction to determine differences in patient-reported outcomes, donor-site morbidity, and complications.

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.

Influence of simulated hip muscle weakness on hip joint forces during deep squatting

This study aimed to determine the effects of simulated hip muscle weakness on changes in hip joint forces during deep squat motion. Ten healthy individuals performed squat motion at three different positions (0° foot angle [N-squat], 10° toe-in [IN-squat], and 30° toe-out [OUT-squat]). A scaled musculoskeletal model for each participant was used to calculate the muscle and hip joint forces. For each hip muscle, models of full strength, mild muscle weakness (15% decrease), and severe muscle weakness (30% decrease) were created. The muscles affecting the hip joint forces were identified, and the rate of change in the joint forces was compared among the three squat conditions. The anterior hip joint force was increased in the muscle weakness models of the inferior gluteus maximus (iGlutMax) and iGlutMax+deep external rotator (ExtRot) muscles. With 30% muscle weakness of these muscles, statistically significant differences in the rate of increase in the anterior joint force were observed in the following order: IN-squat (iGlutMax, 29.5%; iGlutMax+ExtRot, 41.4%), N-squat (iGlutMax, 18.3%; iGlutMax+ExtRot, 27.8%), and OUT-squat (iGlutMax, 5.6%; iGlutMax+ExtRot, 9.3%). OUT-squat may be recommended to minimize the increase in hip joint forces if accompanied by hip muscle weakness.

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.

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.

Outcomes After Arthroscopic Hip Labral Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

The acetabular labrum is critical to maintenance of hip stability and has been found to play a key role in preservation of the hip fluid seal. For irreparable labral damage, arthroscopic labral reconstruction is an evolving technique that has been shown to decrease hip pain and restore function.

PURPOSE

To provide a comprehensive review of current literature for arthroscopic hip labral reconstruction, with a focus on determining if outcomes differ between autograft or allograft tissue.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

PubMed and Scopus online databases were searched with the key terms "hip,""labrum,""reconstruction," and "graft" in varying combinations. Procedures performed, complications, failures, and functional outcome measures were included in this analysis. The inverse variance method was used to calculate pooled estimates and 95% CIs.

RESULTS

Eight studies with 537 hips were included. Mean age was 37.4 years (95% CI, 34.5-40.4 years), and mean follow-up time was 29 months (95% CI, 26-33 months). Survivorship after autograft reconstruction ranged from 75.7% to 100%, as compared with 86.3% to 90.0% in the allograft cohort. In the autograft cohort, failures included 0% to 13.2% conversion to total hip arthroplasty and 0% to 11.0% revision hip arthroscopy. Failures in the allograft cohort included 0% to 12.9% total hip arthroplasty conversion, 0% to 10.0% revision arthroscopy, and 0% to 0.8% open revision surgery. Based on 6 studies, the modified Harris Hip Score improved by a mean 29.0 points after labral reconstruction (P < .0001).

CONCLUSION

Arthroscopic hip labral reconstruction results in clinically significant improvements in patient-reported outcomes. Our analysis indicates that there are no significant differences in outcomes based on graft type alone. A number of factors may determine graft choice, including patient preference, surgeon experience, operative time, morbidity, and cost. Proper patient selection based on age and severity of degenerative joint disease will also optimize outcomes after labral reconstruction.

Best practice guidelines for arthroscopic intervention in femoroacetabular impingement syndrome: results from an International Delphi Consensus Project-Phase 1

Arthroscopic procedures to treat hip pathologies such as femoroacetabular impingement (FAI) syndrome are now established in mainstream orthopaedic practice. Surgical techniques, rehabilitation protocols and outcomes are widely published. However, consensus on standards of practice remains to be determined. The International Hip Preservation Society (ISHA) has undertaken a research study to identify current areas of consensus across the global hip preservation community. The study focussed on consensus statements on the operative steps in the arthroscopic treatment of FAI syndrome. The study methodology was an online Delphi consensus method to collect aggregate opinions from hip preservation surgeons worldwide. Phase 1 of the planned three-phase study is presented here—focusing on consensus statements on the operative steps in the arthroscopic treatment of FAI syndrome. Ninety-nine statements achieved >80% consensus from a panel of 165 surgeons from six continents. This study is the first to evaluate global consensus on the arthroscopic treatment of FAI syndrome, as well as highlighting areas of contention and avenues for future research.

Patient-Specific Parameters Associated With Traction in Primary and Revision Hip Arthroscopic Surgery

Background:

Distraction of the hip joint is a necessary step during hip arthroscopic surgery. The force of traction needed to distract the hip is not routinely measured, and little is known about which patient factors may influence this force.

Purpose:

To quantify the force of traction required for adequate distraction of the hip during arthroscopic surgery and explore the relationship between hip joint stiffness and patient-specific demographics, flexibility, and anatomy.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 101 patients (61 female) undergoing primary hip arthroscopic surgery were prospectively enrolled. A load cell attached to the traction boot continuously measured traction force. Fluoroscopic images were obtained before and after traction to measure joint displacement. The stiffness coefficient was calculated as the force of traction divided by joint displacement. Relationships between the stiffness coefficient and patient demographics and clinical parameters were investigated using a univariable regression model. The regression analysis was repeated separately by patient sex. Variables significant at P < .05 were included in a multivariable regression model.

Results:

The instantaneous peak force averaged 80 ± 18 kilogram-force (kgf), after which the force required to maintain distraction decreased to 57 ± 13 kgf. In univariable regression analysis, patient sex, alpha angle, hamstring flexibility, and Beighton hypermobility score were each correlated to stiffness. However, patient sex was the only significant variable in the multivariable regression model. Intrasex analysis demonstrated that increased hamstring flexibility correlated with decreased final holding stiffness in male patients and that higher Beighton scores correlated with decreased maximal stiffness in female patients.

Conclusion:

Male patients undergoing primary arthroscopic surgery have greater stiffness to hip distraction during arthroscopic surgery compared with female patients. In male patients, stiffness increased with decreasing hamstring flexibility. In female patients, increased Beighton scores corresponded to decreased stiffness. The presence of a labral tear was not correlated with stiffness to distraction. These data may be used to identify patients in whom a specific focus on capsular repair and/or plication may be warranted.

Arthroscopic labral reconstruction using fascia lata allograft: shuttle technique and minimum two-year results

The purpose of this study was to describe the shuttle technique of acetabular labral reconstruction using allograft fascia lata and report minimum two-year clinical outcomes in a prospective patient cohort. We present a shuttle technique to introduce and fixate the allograft, by which the need to fix the free end of the graft from inside the joint is avoided. Between October 2010 and March 2014, 693 hip arthroscopic surgeries were performed by the senior author. Of these 693 patients, 34 patients underwent a labral reconstruction procedure using allograft fascia lata and the shuttle technique and met inclusion criteria. Outcome measures were collected at minimum two years postoperatively. 91.2% (31) of reconstruction patients were available for follow-up at minimum two years after surgery with 12.9% (4) of these patients converting to total hip arthroplasty at average time 27.9 months post-surgery. For the remaining reconstruction patients, mean mHHS increased from 64.0 preoperatively to 84.6 postoperatively (P = 0.0015), SF-12 Physical from 38.9 to 49.0 (P = 0.0004), SF-12 Mental from 49.5 to 55.6 (P = 0.0095), iHOT-12 from 36.4 to 68.1 (P = 0.0017), HOS-ADL from 62.6 to 81.6 (P = 0.0032) and HOS-SS from 32.9 to 65.7 (P < 0.0001). Arthroscopic acetabular labral reconstruction using fascia lata allograft and a shuttle technique appears to be an effective procedure for the treatment of labral pathology through minimum two-year follow-up. While it is difficult to discern the direct influence of the labral reconstructive procedure given the treatment of often concomitant intra-articular pathology, this patient cohort has fared similarly to other cohorts of labral reconstruction patients. No major adverse events are reported.

Acetabular labrum of hip joint in osteoarthritis: A qualitative original study and short review of the literature

PURPOSE

Histological architecture of normal acetabular labrum regarding free nerve endings (FNEs) and mechanoreceptors (MRs) has been satisfactorily described in the literature. However, the presence of FNEs and MRs in acetabular labrum of hip joint has been analyzed only once in patients with osteoarthritis (OA). Aim of this article is to report histological distribution pattern of FNEs and MRs in acetabular labrum of patients with severe OA, at the same time conducting a comparison with normal acetabular labrum described in the literature.

METHODS

Seven patients with severe hip OA were enrolled in this study. Patient selection was assisted by the utilization of specific clinical scales delineated by the American College of Rheumatology. After successful total hip arthroplasty, tissue samples of acetabular labra of seven patients were histologically processed and stained with the gold standard chloride method, which was subsequently examined under a compound microscope.

RESULTS

FNEs and MRs constituted the major histological structures. Identified MRs included Pacini corpuscles, Ruffini corpuscles, and Golgi-Mazzoni corpuscles. The presence of FNEs was predominant in the middle part of the acetabular labrum, featuring a remarkable decrease in peripheral parts. In contrast, MRs were detected basically in peripheral parts and less in the middle part.

CONCLUSIONS

Differentiation of the distribution pattern of MRs and FNEs in acetabular labrum of hip joint is remarkable between normal patients and patients with severe OA. The abundance of FNEs in the middle part of the pathologic labrum is mainly responsible for the observed discrimination. A "conversion" of MRs to FNEs may occur during OA progression, modulating therefore this pattern as well as the upcoming clinical manifestations.

Labral cuff refixation in the hip: rationale and operative technique for preserving the chondrolabral interface for labral repair: a case series

Arthroscopic labral 'takedown' and refixation is utilized to permit adequate visualization and resection of the acetabular rim deformity, in patients with pincer or mixed femoroacetabular impingement. Deficiencies exist in present techniques, which include disruption of vital anatomical support and vascular structures to the labrum and chondrolabral junction, drill or anchor articular penetration risk, bunching, elevation and instability of the labrum. A new operative technique is described which preserves the important chondrolabral interface, accurately restoring the 'flap seal' of the acetabular labrum while minimizing vascular disruption and reducing the risk of drill and anchor penetration. A prospective series of 123 consecutive cases of pincer or mixed femoroacetabular impingement, treated with arthroscopic labral cuff refixation and preservation of the chondrolabral interface, is reported; operative technique and 2-year outcomes are presented.

Normal microscopic architecture of acetabular labrum of hip joint: a qualitative original study with clinical aspects

Background

Normal histologic architecture of acetabular labrum, regarding presence of Free Nerve Endings (FNEs) and Nerve End Organs (NEOs) has been four times described. Nevertheless, elderly cadaveric specimens and individuals were recruited, leading to considerably high unreliability probability due to microscopic degenerative alterations. Aim of this paper is to analyze distribution pattern of FNEs and NEOs in acetabular labra of healthy middle-aged individuals, configuring thus more reliably acetabular labrum microscopic profile.

Materials and methods

Six patients with middle age 52 ± 2.5 years were enrolled in this study. Injury of acetabular labrum and normal hip radiograph were present in all cases. Patients were all subjected to successful hip hemi-arthroplasty and derived acetabular labra were subsequently histologically processed and observed under a compound microscope.

Results

FNEs and NEOs were detected in all specimens. All types of NEOs were identified, including Paccini, Golgi-Mazzoni, Ruffini and Krause corpuscles. FNEs and NEOs were both in ventral part and in chondral side of labrum predominantly detected.

Conclusion

FNEs and NEOs presence was greater in ventral side of labrum, being thus in partial agreement with previous studies results. Further study is required, in order to elucidate the exact acetabular labrum normal microscopic anatomy.

Level of evidence

IV.

Microinstability of the hip: A review

With the development of conservative hip surgery techniques, new entities such as microinstability have been identified. Microinstability is a painful supra-physiological mobility of the hip. It results from the association of architectural and functional abnormalities impairing joint stability. These risk factors concern hip joint bone architecture or peri-articular soft tissues. Bone abnormalities are identified on hip assessment parameters. Soft tissues also play a key role in the static and dynamic stability of the hip: the joint capsule, labrum, ligamentum teres and adjacent myotendinous structures affect joint coaptation; any abnormality or iatrogenic lesion concerning these structures may constitute a risk factor for microinstability. Diagnosis is based on interview, clinical examination and imaging. Findings of labral lesions or femoro-acetabular impingement do not rule out microinstability; they may be associated. Treatment is based first on physiotherapy for muscle reinforcement to improve joint coaptation. In case of failure, arthroscopic surgery is indicated for femoro-acetabular impingement and capsular plicature which is being evaluated. Periacetabular osteotomy or shelf acetabuloplasty may be indicated, according to the severity of joint bone architecture abnormality. Microinstability is a multifactorial entity. Lesions induced by microinstability may in turn become risk factors for aggravation. Diagnosis and indications for surgery are thus difficult to establish. Only full clinical examination and exhaustive imaging assessment allow microinstability and associated lesions to be identified.

Acetabular Labral Reconstruction With Autologous Tendon Tissue in a Porcine Model: In Vivo Histological Assessment and Gene Expression Analysis of the Healing Tissue

BACKGROUND

Acetabular labral reconstruction with autologous tendons is the preferred method for treating a severely damaged labrum. However, the healing process of implants remains unknown. Similar to the human acetabular labrum, the porcine acetabular labrum is a fibrocartilage-like tissue.

PURPOSE

This study aimed to characterize the histological healing process and gene expression profile of implants in a porcine model of acetabular labral reconstruction.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eighteen pigs were included in this study. The pigs underwent unilateral acetabular labral reconstruction. A 1.0 cm-long defect was made at the site of the anterior (cranial) dorsal labrum, which was repaired using an autologous mesogluteus tendon. The pigs were sacrificed at 12 and 24 weeks postoperatively. The implants were subjected to histological assessment and gene expression analysis. The cell phenotype of the implants was visualized using paraffin-embedded sections.

RESULTS

Macroscopic observations revealed that at 12 weeks, 8 of 9 implants partially filled the labral defect; by contrast, at 24 weeks, 6 of 9 implants fully filled and 3 implants partially filled the labral defects. Oval- or round-shaped fibrochondrocytes were found in the implants at 12 and 24 weeks. The matrix staining results showed that proteoglycan and collagen types 1 and 2 were more evident in the implants at 24 weeks than at 12 weeks. Gene expression analysis results revealed that COL2A1 and COL3A1 were expressed by the implants to a higher extent at 24 weeks than at 12 weeks; COL2A1 and COL3A1 were also expressed to a higher extent in the implants than in the native tendon.

CONCLUSION

On the basis of the results of histological assessment and gene expression analysis, autologous tendon tissue for acetabular labral reconstruction can fully or partially fill labral defects and converts to fibrocartilage, which is rich in proteoglycan and collagen types 1 and 2, at 24 weeks in a porcine model.

CLINICAL RELEVANCE

Autologous tendon tissue can be considered as a viable option for acetabular labral reconstruction.

New perspectives on femoroacetabular impingement syndrome

Femoroacetabular impingement (FAI) is characterized by an abnormality in the shape of the femoral head-neck or acetabulum that results in impingement between these two structures. Arthroscopic treatment has become the preferred method of management of FAI owing to its minimally invasive approach. Surgical correction involves resection of impinging osseous structures as well as concurrent management of the associated chondral and labral pathology. Research from the past 5 years has shown that repair of the labrum results in a better anatomic correction and improved outcomes compared with labral debridement. Research is underway to improve cartilage assessment by using innovative imaging techniques and biochemical tests to inform predictions of prognosis. Several ongoing randomized controlled trials, including the Femoroacetabular Impingement Trial (FAIT) and the Femoroacetabular Impingement Randomized Controlled Trial (FIRST), will provide critical information regarding the diagnosis, management and prognosis of patients undergoing arthroscopic management of FAI.