Short-term Outcomes After Hip Arthroscopic Surgery in Patients Participating in Formal Physical Therapy Versus a Home Exercise Program: A Prospectively Enrolled Cohort Analysis.

BACKGROUND: Physical therapy is frequently utilized in the postoperative care of femoroacetabular impingement syndrome (FAIS). There has been limited research into the efficacy of a structured home exercise program (HEP) compared with formal physical therapy (FPT) in this patient population. PURPOSE/HYPOTHESIS: The purpose was to evaluate the short-term outcomes of patients utilizing FPT versus an HEP after hip arthroscopic surgery for FAIS. It was hypothesized that both groups would show similar improvements regarding outcome scores, which would improve significantly compared with their preoperative scores. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Patients undergoing hip arthroscopic surgery for FAIS at a single center between October 2020 and October 2021 were prospectively enrolled. Patients were allowed to self-select FPT or an HEP and were administered a survey preoperatively and at 1 month, 3 months, 6 months, and 12 months postoperatively. The survey included the Single Assessment Numeric Evaluation, visual analog scale for pain, 12-item International Hip Outcome Tool, Patient-Reported Outcomes Measurement Information System Physical Function, and patient satisfaction with physical therapy and overall care. Statistical analysis was conducted between the 2 groups and within groups to compare preoperative and postoperative scores. RESULTS: The patients' mean age was 32.6 ± 10.4 years, with 47.2% being female and 57.4% choosing the HEP. At 12 months postoperatively, no significant differences were reported between the FPT and HEP groups regarding the Single Assessment Numeric Evaluation score (P = .795), visual analog scale for pain score (P > .05), Patient-Reported Outcomes Measurement Information System Physical Function T-score (P = .699), 12-item International Hip Outcome Tool score (P = .582), and patient satisfaction (P > .05). Outcome scores at 12 months postoperatively were significantly improved from the preoperative scores across all measures in both groups (P < .001). CONCLUSION: There were no significant differences regarding patient outcomes between FPT and the HEP at 1-year follow-up after hip arthroscopic surgery for FAIS when patients selected their own treatment, with both groups demonstrating significant improvements in their outcome scores from their preoperative values. These findings suggest that a structured HEP may be a viable alternative to FPT after hip arthroscopic surgery in patients who prefer a self-directed rehabilitation program.

Physeal Location on the Distal Femoral Cortical Surface Is Consistently Proximal to Apparent Location on the Perfect Lateral Radiograph: A 3-Dimensional Digitally Reconstructed Radiograph Study.

INTRODUCTION: The perfect knee lateral radiograph visualizes anatomic landmarks on the distal femur for clinical and scientific purposes. However, radiographic imaging is a two-dimensional (2D) representation of a three-dimensional (3D) physis. The aim of this study was to characterize the perceived radiographic projection of the femoral physis using perfect lateral digitally reconstructed radiographs (DRRs) and to evaluate discrepancies from this projection to the physis at the lateral and medial cortices. METHODS: Pediatric patients from a cohort of CT scans were analyzed. Inclusion criteria were an open physis; exclusion criteria were any implant or pathology affecting the physis. CT scans were imported into 3D imaging software and transformed into lateral DRRs and 3D renderings of the femur. The physis was divided into four equal segments, with fiducial markers placed at the "anterior," "midpoint," and "posterior" points. Lines extended from these points in the lateral and medial direction. The vertical distance from these lines, representing the radiographic projection of the physis, was measured relative to the physis at the lateral and medial cortex of the femur on coronal CT slices. RESULTS: Thirty-one patients were included. On the perfect lateral radiograph DRR, the physis on the medial cortex was located proximal to the visualized physis by 6.64 ± 1.74 mm, 11.95 ± 1.67 mm, and 14.30 ± 1.75 mm at the anterior (25%), midpoint (50%), and posterior (75%) locations, respectively. On the lateral side, the physis on the lateral cortex was proximal to the visualized physis by 2.19 ± 1.13 mm, 3.71 ± 1.19 mm, and 6.74 ± 1.25 mm at the anterior, midpoint, and posterior locations, respectively. DISCUSSION: In this cohort of pediatric patients, the location of the cortical physis was, in all areas measured, proximal to the projection of the visualized physis as seen on the perfect knee lateral DRR. The distance from radiographic physis to cortical physis was greater at the medial cortex compared with the lateral cortex. STUDY DESIGN: Descriptive laboratory study. LEVEL OF EVIDENCE: III, observational radiographic anatomic study.

Postless Hip Arthroscopy: A Technical Note on Obtaining Distraction.

Hip arthroscopy techniques continue to evolve. Historically, a post has been used as an aid to establish adequate hip joint distraction. However, this technique is associated with potentially devastating postoperative pudendal nerve injury and other urologic and gynecologic complications. In this article, we present our technique for postless hip arthroscopy.

Correlation of Tibial Tubercle Overgrowth With Increased Posterior Tibial Slope: A Novel Radiographic Assessment.

Background: An elevated posterior tibial slope (PTS) is associated with an increased risk for anterior cruciate ligament and meniscal injury. Recent evidence suggests that the PTS is elevated in patients with Osgood-Schlatter disease. Purpose: To determine whether there is an association between objective measures of anterior tibial tubercle growth and PTS. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 100 radiographs were randomly selected from a sample of patients who had received a lateral knee radiograph that captured at least 15 cm of the tibia distal to the knee joint line at a single institution between December 2020 and March 2022. The PTS was measured, and tibial tubercle growth was quantified with 2 novel measurements. For these measurements, a line was drawn on the radiograph from the most anterosuperior point on the tibia to the point on the anterior cortex of the tibia 10 cm distal from the starting point. The tibial tubercle height (TTH) was measured as the perpendicular distance from this line to the most prominent portion of the anterior tibia. The anterior tibial tubercle angle (TTA) was measured as the angle between the endpoints of the line made previously and the most prominent portion of the tibial tubercle, with a more acute angle indicating a more prominent tibial tubercle. The relationship between TTA, TTH, and PTS was evaluated using a univariate linear regression model. Results: The mean patient age was 33.1 ± 14.1 years. The mean TTA was 158.6°± 4.7°, the mean TTH was 8.8 ± 2.0 mm, and the mean PTS was 9.7°± 2.6°. A significant correlation was found between PTS and TTA (r = -0.46; ß = -0.46; P < .001) as well as TTH (r = 0.43; ß = 0.43; P < .001). Conclusion: Objective measures of anterior tibial tubercle overgrowth correlated with an elevated PTS. Every 2.2° of anterior TTA deviation from the mean and every 2.3 mm in TTH deviation from the mean correlated with a 1° difference in the PTS. This suggests a link between the development of the tibial tubercle and PTS, and it potentially helps to explain why the PTS is elevated in certain patients.

Magnetic Resonance Imaging and Magnetic Resonance Arthrography Are Both Reliable and Similar When Measuring Hip Capsule Thickness in Patients With Femoroacetabular Impingement Syndrome.

Purpose: To propose an accurate method of measuring hip capsular thickness in patients with femoroacetabular impingement syndrome and to compare the reliability of these measurements between magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA). Methods: A previously established database of patients with femoroacetabular impingement syndrome (FAIS) was used to identify candidates with preoperative MRI or MRA from November 2018 to June 2021. Two reviewers independently examined preoperative imaging for 85 patients. Capsular thickness was measured in 12 standardized locations. Intraclass correlation coefficients (ICCs) were calculated using an absolute-agreement, 2-way random-effects model. Using the same method, 30 patients were randomly selected for repeat measurements by 1 reviewer following a washout period. Ten additional patients with preoperative MRI and MRA of the same hip were identified to compare measurements between modalities using paired samples t test. Results: ICCs for measurements on MRIs and MRAs using these proposed measurements to compare inter-rater reliability were 0.981 and 0.985. ICCs calculated using measurements by a single reviewer following a washout period for intrarater reliability were 0.998 and 0.991. When comparing MRI and MRA measurements in the same patient, t test for all pooled measurements found no difference between modality (P = .283), and breakdown of measurements by quadrant found no difference in measurements (P > .05), with the exception of the inferior aspect of the capsule on coronal sequences (P = .023). Conclusions: In patients with FAIS, both MRI and MRA have excellent reliability for quantifying hip capsular thickness. A difference in capsular thickness was found only when comparing MRI and MRA on inferior coronal aspects of the hip capsule, indicating interchangeability of these imaging modalities when measuring the clinically important aspects of the hip capsule. Level of Evidence: Level IV, diagnostic case series.

Association of Postless Distraction in Hip Arthroscopy With Decreased Postoperative Groin Numbness.

BACKGROUND: Patients undergoing hip arthroscopy performed with perineal post distraction may experience postoperative nerve and soft tissue complications related to the perineal post. PURPOSE: To compare rates of postoperative numbness in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome (FAIS) with postless distraction and perineal post distraction methods. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review of prospectively collected data was performed on patients who underwent hip arthroscopy for FAIS, with postless distraction and perineal post distraction methods. Medical records were reviewed for patient characteristics, radiographic data, and operative data. Traction force data were collected on all patients prospectively using a previously validated method. Data on postoperative numbness (presence/absence and regionality) were collected prospectively at routine postoperative follow-ups (6-week and 3-month postoperative clinic visits). RESULTS: Overall, 195 patients were included, with 94 patients (mean age, 30.4 years) in the postless distraction cohort and 101 patients (mean age, 31.9 years) in the post distraction cohort. The overall numbness rates were 29 of 94 (30.9%) in the postless distraction group and 45 of 101 (44.6%) in the post distraction group (P = .068). Rates of postoperative groin numbness were 1 of 94 (1.1%) in the postless distraction group and 19 of 101 (18.8%) in the post distraction group (P < .001). Multivariate analysis for postoperative groin numbness demonstrated post distraction (odds ratio [OR], 16.5; P = .022) and traction time (OR, 1.7; P = .020) to be statistically significant variables. In subgroup analysis of the post distraction group, traction time (P = .015), but not holding (P = .508) or maximum traction force (P = .665), reached statistical significance in patients who developed postoperative groin numbness. CONCLUSION: Postless distraction hip arthroscopy demonstrated a statistically significantly lower rate of groin numbness rates in comparison with a traditional perineal post distraction method. In the post distraction group, traction time was significantly higher in patients who developed postoperative groin numbness than in those who did not.

Acetabular Labral Reconstruction: Review of Techniques and Outcomes.

PURPOSE OF REVIEW: To analyze advances in labral reconstruction, and to discuss the literature relating to efficacy, outcomes, and technical considerations of labral reconstruction. RECENT FINDINGS: The available evidence suggests that labral reconstruction is a safe and effective procedure that can improve pain and function in patients with severe and/or complex labral tears. The superiority of labral reconstruction over labral repair is uncertain, and it remains unclear what graft type and technique should be used in labral reconstructions. Labral reconstruction assists in restoring the function of the labrum of the hip. It consistently restores stability of the hip joint and demonstrates good clinical outcomes at follow-up. The optimal graft type, technique, and extent are still debated, and more research is needed. Ultimately, despite this uncertainty, labral reconstruction is proving to be a valuable tool for hip preservation specialists.

Postless Hip Distraction Systems Decrease the Amount of Traction Force Needed to Obtain Adequate Hip Distraction Versus a Conventional Post Hip Distractor.

PURPOSE: To directly compare hip distraction distance and traction force data for hip arthroscopy performed using a post-basedsystem versus a postless system. METHODS: Adult patients undergoing primary hip arthroscopy for femoroacetabular impingement were prospectively enrolled. Before March 26, 2019, arthroscopy was performed using a post-based system. After this date, the senior author converted to using a postless system. Intraoperative traction force and fluoroscopic distraction distance were measured to calculate hip stiffness coefficients at holding traction (k-hold) and maximal traction (k-max). We used multivariable regression analysis to determine whether postless arthroscopy was predictive of lower stiffness coefficients when controlling for other relevant patient-specific factors. RESULTS: Hip arthroscopy was performed with a post-based system in 105 patients and with a postless system in 51. Mean holding traction force (67.5 ± 14.0 kilograms-force [kgf] vs 55.8 ± 15.3 kgf) and mean maximum traction force (96.0 ± 16.6 kgf vs 69.9 ± 14.1 kgf) were significantly lower in the postless group. On multivariable analysis, postless traction was an independent predictor of decreased k-hold (ß = -31.4; 95% confidence interval, -61.2 to -1.6) and decreased k-max (ß = -90.4; 95% confidence interval, -127.8 to -53.1). Male sex, Beighton score of 0, and poor hamstring flexibility were also predictors of increased k-hold and k-max in the multivariable model. CONCLUSIONS: Postless traction systems decrease the amount of traction force required for adequate hip distraction for both maximal and holding traction forces when compared with post-based systems. Postless traction systems may help further reduce distraction-type neurologic injuries and pain after hip arthroscopy by lowering the traction force required to safely distract the hip. LEVEL OF EVIDENCE: Level III, prospective cohort-historical control comparative study.

The Schöttle Point Is Consistently Located Distal to the Medial Femoral Physis in Pediatric Patients: A Digitally Reconstructed Radiographic Study.

BACKGROUND: Significant controversy surrounds ideal tunnel position for medial patellofemoral ligament (MPFL) reconstruction (MPFLR) in the pediatric setting. The start point for femoral tunnel positioning (the Schöttle point) relative to the distal medial femoral physis is not well defined. Previous studies provide conflicting data regarding position of the MPFL origin and the Schöttle point relative to the distal femoral physis. HYPOTHESIS: The Schöttle point would be consistently distal to the distal medial femoral physis. STUDY DESIGN: Descriptive laboratory study. METHODS: The institutional picture archiving and communication system was queried for computed tomography (CT) imaging studies of pediatric knees. Data were imported to an open-source image computing platform. True lateral digitally reconstructed radiographs and 3-dimensional (3D) renderings were generated, and the Schöttle point was registered in 3D space. Then, 3D distance measurements were obtained from the Schöttle point to the distal medial femoral physis. RESULTS: A total of 49 pediatric knee CT scans were included. Mean age was 13.0 ± 2.3 years. Mean minimum distance from the medial physis to the Schöttle point was 9.9 ± 3.0 mm (range, 3.4-16.1 mm). In 49 of 49 cases (100%), the Schöttle point was distal to the physis. Using a 6-mm reaming diameter would result in 3 of 49 (6%) femurs having violation of the distal medial femoral physis. Moving the start point 3 mm distally would result in 0 of 49 (0%) sustaining physeal injury. CONCLUSION/CLINICAL RELEVANCE: The Schöttle point is consistently distal to the distal medial femoral physis. The mean minimum distance from the Schöttle point to the physis on the medial cortex is 9.9 mm. The Schöttle point provides a safe and reliable radiographic landmark for pediatric MPFLR, although reaming diameter should be considered.

Bone Grafting Technique in Revision ACL Reconstruction: Coring Reamer and Dowel Trick.

One- or two-staged bone grafting is sometimes required for tunnel malposition and/or tunnel widening in revision anterior cruciate ligament (ACL) reconstruction. The aim of this procedure is to restore the correct position of the ACL graft in the revision setting to provide a stable and functional ACL, thereby reproducing normal knee kinematics. We present a technique that allows for a cost-effective, convenient tunnel grafting of a femoral head allograft bone dowel into both femoral and tibial defects in revision ACL reconstruction.

Association of Cam Deformity on Anteroposterior Pelvic Radiographs and More Severe Chondral Damage in Femoroacetabular Impingement Syndrome.

BACKGROUND: Abnormal proximal femoral morphology in femoroacetabular impingement syndrome (FAIS) identifiable on the anteroposterior (AP) pelvic radiograph has been described as the "pistol grip" deformity. The effect of a superior cam deformity identified on this radiographic view remains unknown. PURPOSES: To assess the relationship between AP cam deformity (AP alpha angle [AP AA] >55°) and cartilage injury; to assess the relationship between AP cam deformity and labral injury; and to determine if patient factors are correlated with cartilage and labral injury. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Patients undergoing osteochondroplasty and labral repair for FAIS with a single surgeon were identified retrospectively. Intraoperative size, location, and severity of cartilage and labral damage were prospectively collected. Chondrolabral and femoral/acetabular cartilage damage were graded with the Beck labral and cartilage injury criteria. Radiographic data included the AP AA, lateral center-edge angle (LCEA), and maximum femoral alpha angle (MF AA). Patients with hip dysplasia (LCEA <18°; LCEA 18°-25° with acetabular index >10°) were excluded. Outcomes were compared across cartilage and labral severity grades. We report odds ratios (ORs) with 95% confidence intervals and P values from multivariable logistic regressions. RESULTS: Of the 158 included hips (154 patients), 69% were female and the mean (± standard deviation [SD]) age was 30.3 ± 9.7 years. Increase in age, increase in body mass index (BMI), and male sex were associated with increasing severity of cartilage and labral injury. More severe cartilage damage was associated with increasing AP AA (P < .001) and MF AA (P < .001). The odds of developing a higher category of cartilage injury severity (grade ≥3) were 119% higher (OR, 2.19 [95% CI, 1.36-3.64]; P = .002) for every SD increase (16.7°) in AP AA, adjusting for age, sex, and BMI. The odds of developing a severe labral injury (grade ≥3) were 118% higher (OR, 2.18 [95% CI 1.17-4.32]; P = .018) for every SD increase (10.5°) in MF AA, adjusting for age, sex, BMI, and AP AA. CONCLUSION: Increasing age and BMI, and male sex are associated with increasing severity of cartilage and labral injury in FAIS. The odds of developing a cartilage injury are significantly higher with independent increases in AP AA and MF AA.

Effect of Perioperative Opioid Use on Patients Undergoing Hip Arthroscopy.

Background: Opioids are commonly used to treat postoperative pain; however, guidelines vary regarding safe opioid use after hip arthroscopy. Purpose/Hypothesis: The purposes were to (1) identify risk factors for persistent opioid use, (2) assess the effect of opioid use on outcomes, and (3) describe common opioid prescribing patterns after hip arthroscopy. It was hypothesized that preoperative opioid use would affect complication rates and result in greater postoperative opioid use. Study Design: Case-control study; Level of evidence 3. Methods: The Utah State All Payer Claims Database was queried for patients who underwent hip arthroscopy between January 2013 and December 2017. Included were patients ≥14 years of age at index surgery with continuous insurance. Patients were separated into acute (<3 months) and chronic (≥3 months) postoperative opioid use groups. Primary outcomes included revision surgery, complications (infection, pulmonary embolism/deep venous thrombosis, death), emergency department (ED) visits, and hospital admissions. Multivariate logistic regression was utilized to identify factors associated with the outcomes. Results: Included were 2835 patients (mean age, 47 years; range, 14-64 years), of whom 2544 were in the acute opioid use and 291 were in the chronic opioid use group. Notably, 91% of the patients in the chronic group took opioid medications preoperatively, and they were more than twice as likely to carry a mental health diagnosis (P < .01). Patients in the acute group had a significantly shorter initial prescription duration, took fewer opioid pills, and had fewer refills than those in the chronic group (P < .01 for all). Patients in the chronic group had a significantly higher risk of postoperative ED visits (odds ratio [OR], 2.76; P = .008), hospital admission (OR, 3.02; P = .002), and additional surgery (P = .003), as well as infection (OR, 2.55; P < .001) and hematoma (OR, 2.43; P = .030). Patients who had used opioids before hip arthroscopy were more likely to need more refills (P < .01). A formal opioid use disorder diagnosis correlated significantly with postoperative hospital admissions (OR, 3.83; P = .044) and revision hip arthroscopy (OR, 4.72; P = .003). Conclusion: Mental health and substance use disorders were more common in patients with chronic postoperative opioid use, and chronic postoperative opioid use was associated with greater likelihood of postoperative complications. Preoperative opioid use was significantly correlated with chronic postoperative opioid use and with increased refill requests after index arthroscopy.

Femoral neck shaft angle is not correlated with femoral version: A retrospective study of computed tomography scans.

BACKGROUND: An understanding of femoral anteversion and neck-shaft angle (NSA) is essential to deliver optimal orthopaedic surgical care. Despite the importance, there is little research examining the relationship between femoral anteversion and the NSA in an adult population. This study sought to determine if there is a correlation between femoral neck shaft angle and version in skeletally mature adults using computed tomography (CT) scanograms. METHODS: Between January 2010 and June 2017, all skeletally mature patients who had received a CT scanogram of the lower extremity were reviewed. Exclusion criteria included: (1) radiographic evidence of osteoarthritis, (2) history of hip, femur, or knee surgery or trauma, (3) and anatomic abnormalities of the proximal femur including prior slipped capital femoral epiphysis or Legg-Calvé-Perthes disease. Both femoral version and NSA were measured by a musculoskeletal fellowship trained radiologist using CT scanograms. Correlation between femoral version and NSA was determined using coefficient of determination (R2) and Pearson correlation coefficient (r) for the group as a whole and for each sex. RESULTS: There was no statistical correlation between femoral version and NSA for either the entire cohort or for each sex. For the entire cohort, R2 = 0.0016 and r was 0.04 (p=0.45), for females, R2 = 0.0005 and r was 0.0224 (p=0.72), and for males, R2 = 0.0342 and r was 0.185 (p=0.07). CONCLUSION: There was no correlation between femoral version and NSA. This finding is beneficial for surgeons to understand the proximal femoral anatomy. Patients with an increased femoral NSA should not be assumed to have increased femoral anteversion. LEVEL OF EVIDENCE: Level III, Retrospective Cohort Study.

Dynamic Assessment of Femoroacetabular Impingement Syndrome Hips.

PURPOSE: The purpose of our study was to compare lower extremity rotational kinematics and kinetics (angles, torques, and powers) and hip muscle electromyography (EMG) activity between cam-type femoroacetabular impingement syndrome (FAIS) and age- and sex-matched controls during walking, fast walking, stair ascent, stair descent, and sit-to-stand. METHODS: This study included 10 males with unilateral FAIS and 10 control males with no FAIS. We measured kinematics, kinetics, and electromyographic signals during stair ascent/descent, sit-to-stand, self-selected walk, and fast walk. Peak signal differences between groups were compared with independent t-tests with statistical significance when P < .05. RESULTS: FAIS hips showed significant differences compared to controls, including increased hip flexion during walking (+4.9°, P = .048) and stair ascent (+7.8°, P =.003); diminished trunk rotation during stair ascent (-3.4°; P = .015), increased knee flexion during self-selected walking (+5.1°, P = .009), stair ascent (+7.4°, P = .001), and descent (+5.3°, P = .038); and increased knee valgus during fast walking (+4.7°, P = .038). gMed and MedHam showed significantly decreased activation in FAIS during walking (gMed: -12.9%, P = .002; MedHam: -7.4%, P = .028) and stair ascent (gMed: -16.7%, P = .036; MedHam: -13.0%, P = .041); decreased gMed activation during sit-to-stand (-8.8%, P = .004) and decreased MedHam activation during stair descent (-8.0%, P = .039). CONCLUSIONS: Three-dimensional motion analysis and EMG evaluation of functional kinematics and kinetics in subjects with symptomatic unilateral cam-type FAIS across a spectrum of provocative tasks demonstrated significant differences compared to controls in hip flexion, trunk rotation, knee flexion, and valgus. FAIS hips had significantly decreased gMed and MedHam activity. These findings may explain altered torso-pelvic, hip, and knee mechanics in FAIS patients and suggest that evaluation of FAIS should include the patient's hip, knee, and torso-pelvic relationships and muscle function. CLINICAL RELEVANCE: The clinical and functional manifestation of FAIS hip pathomechanics is not entirely understood, and previous literature to date has not clearly described the alterations in gait and functional movements seen in patients with cam-type FAIS. The current study used 3D motion analysis and EMG evaluation of functional kinematics and kinetics to identify a number of differences between FAIS and control hips, which help us better understand the lower extremity kinematics and kinetics and muscle activation in FAIS.

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.

Enhancing chondrogenic potential via mesenchymal stem cell sheet multilayering.

Advanced tissue engineering approaches for direct articular cartilage replacement in vivo employ mesenchymal stem cell (MSC) sources, exploiting innate chondrogenic potential to fabricate hyaline-like constructs in vitro within three-dimensional (3D) culture conditions. Cell sheet technology represents one such advanced 3D scaffold-free cell culture platform, and previous work has shown that 3D MSC sheets are capable of in vitro hyaline-like chondrogenic differentiation. The present study aims to build upon this understanding and elucidate the effects of an established cell sheet manipulation technique, cell sheet multilayering, on fabrication of MSC-derived hyaline-like cartilage 3D layered constructs in vitro. To achieve this goal, multilayered MSC sheets are prepared and assessed for structural and biochemical transitions throughout chondrogenesis. Results support MSC multilayering as a means of increasing construct thickness and 3D cellular interactions related to in vitro chondrogenesis, including N-cadherin, connexin 43, and integrin ß-1. Data indicate that increasing construct thickness from 14 µm (1-layer construct) to 25 µm (2-layer construct) increases these cellular interactions and subsequent in vitro MSC chondrogenesis. However, a clear initial thickness threshold (33 µm - 3-layer construct) is evident that decreases the rate and extent of in vitro chondrogenesis, specifically chondrogenic gene expressions (Sox9, aggrecan, type II collagen) and sulfated proteoglycan accumulation in deposited extracellular matrix (ECM). Together, these data support the utility of cell sheet multilayering as a platform for tailoring construct thickness and subsequent MSC chondrogenesis for future articular cartilage regeneration applications.

Safety and efficacy of human juvenile chondrocyte-derived cell sheets for osteochondral defect treatment.

Knee cartilage does not regenerate spontaneously after injury, and a gold standard regenerative treatment algorithm has not been established. This study demonstrates preclinical safety and efficacy of scaffold-free, human juvenile cartilage-derived-chondrocyte (JCC) sheets produced from routine surgical discards using thermo-responsive cultureware. JCCs exhibit stable and high growth potential in vitro over passage 10, supporting possibilities for scale-up to mass production for commercialization. JCC sheets contain highly viable, densely packed cells, show no anchorage-independent cell growth, express mesenchymal surface markers, and lack MHC II expression. In nude rat focal osteochondral defect models, stable neocartilage formation was observed at 4 weeks by JCC sheet transplantation without abnormal tissue growth over 24 weeks in contrast to the nontreatment group showing no spontaneous cartilage repair. Regenerated cartilage was safranin-O positive, contained type II collagen, aggrecan, and human vimentin, and lacked type I collagen, indicating that the hyaline-like neocartilage formed originates from transplanted JCC sheets rather than host-derived cells. This study demonstrates the safety of JCC sheets and stable hyaline cartilage formation with engineered JCC sheets utilizing a sustainable tissue supply. Cost-benefit and scaling issues for sheet fabrication and use support feasibility of this JCC sheet strategy in clinical cartilage repair.

Tibial Spine Repair in the Pediatric Population: Outcomes and Subsequent Injury Rates.

PURPOSE: To evaluate short- to mid-term outcomes after arthroscopic operative fixation of tibial spine fractures in pediatric patients, to determine the incidence of further ipsilateral and contralateral knee injuries, and to describe associated meniscal pathology and intraoperative findings at the time of tibial spine repair. METHODS: All patients under age 18 with a tibial spine fracture treated arthroscopically at 1 institution by 2 surgeons from 2008 through 2019 were identified by Current Procedural Terminology codes. Patients at least 1 year from their date of surgery were contacted to complete a questionnaire, which included the International Knee Documentation Committee (IKDC) form. Questions pertained to knee function, pain, and further injury or surgery on either knee. Patient charts, preoperative imaging, and operative reports were reviewed to determine demographic information, tibial spine fracture type, concomitant injuries, and intraoperative details. RESULTS: Sixty-six of 97 eligible patients (68%) completed questionnaires. Average age at initial surgery was 10.7 years (range, 4-17). Mean follow-up was 5.8 years (range, 1.0-11.9). Average IKDC score at follow-up was 91.4 (range, 62.1-100). Patients reported their knee as 92% of "normal" (range, 40-100). Thirty-five (53%) currently participate in sport; 6 (9%) remain limited because of instability and residual pain. Regarding pain on a visual analog scale, 94%, 95%, and 83% of patients reported less than a 3 at rest, with daily activity, and with sport, respectively. Seven patients (11%) had subsequent ACL rupture. Six patients (9%) underwent ACL reconstruction 3.1 years (range, 0.9-7) after initial repair. Fourteen patients (21%) required at least 1 additional procedure. Regarding the contralateral knee, there were no ACL or tibial spine injuries. Sixty-one (92%) patients were both satisfied and would definitely undergo the procedure again. CONCLUSIONS: Although many pediatric patients demonstrate excellent results after tibial spine repair at mean 5.8 years follow-up, 10.6% sustained an ipsilateral ACL rupture, and 21% required an additional procedure. No patient had a contralateral tibial spine or ACL injury. This is helpful when counseling patients regarding injury risk when returning to activity after tibial spine repair. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Trends in Articular Cartilage Tissue Engineering: 3D Mesenchymal Stem Cell Sheets as Candidates for Engineered Hyaline-Like Cartilage.

Articular cartilage defects represent an inciting factor for future osteoarthritis (OA) and degenerative joint disease progression. Despite multiple clinically available therapies that succeed in providing short term pain reduction and restoration of limited mobility, current treatments do not reliably regenerate native hyaline cartilage or halt cartilage degeneration at these defect sites. Novel therapeutics aimed at addressing limitations of current clinical cartilage regeneration therapies increasingly focus on allogeneic cells, specifically mesenchymal stem cells (MSCs), as potent, banked, and available cell sources that express chondrogenic lineage commitment capabilities. Innovative tissue engineering approaches employing allogeneic MSCs aim to develop three-dimensional (3D), chondrogenically differentiated constructs for direct and immediate replacement of hyaline cartilage, improve local site tissue integration, and optimize treatment outcomes. Among emerging tissue engineering technologies, advancements in cell sheet tissue engineering offer promising capabilities for achieving both in vitro hyaline-like differentiation and effective transplantation, based on controlled 3D cellular interactions and retained cellular adhesion molecules. This review focuses on 3D MSC-based tissue engineering approaches for fabricating "ready-to-use" hyaline-like cartilage constructs for future rapid in vivo regenerative cartilage therapies. We highlight current approaches and future directions regarding development of MSC-derived cartilage therapies, emphasizing cell sheet tissue engineering, with specific focus on regulating 3D cellular interactions for controlled chondrogenic differentiation and post-differentiation transplantation capabilities.