Complex dynamics of partially freezable confined water revealed by combined experimental and computational studies.

We investigate water dynamics in mesoporous silica across partial crystallization by combining broadband dielectric spectroscopy (BDS), nuclear magnetic resonance (NMR), and molecular dynamics simulations (MDS). Exploiting the fact that not only BDS but also NMR field-cycling relaxometry and stimulated-echo experiments provide access to dynamical susceptibilities in broad frequency and temperature ranges, we study both the fully liquid state above the melting point Tm and the dynamics of coexisting water and ice phases below this temperature. It is found that partial crystallization leads to a change in the temperature dependence of rotational correlation times τ, which occurs in addition to previously reported dynamical crossovers of confined water and depends on the pore diameter. Furthermore, we observe that dynamical susceptibilities of water are strongly asymmetric in the fully liquid state, whereas they are much broader and nearly symmetric in the partially frozen state. Finally, water in the nonfreezable interfacial layer below Tm does not exhibit a much debated dynamical crossover at ∼220 K. We argue that its dynamics is governed by a static energy landscape, which results from the interaction with the bordering silica and ice surfaces and features a Gaussian-like barrier distribution. Consistently, our MDS analysis of the motional mechanism reveals a hopping motion of water in thin interfacial layers. The rotational correlation times of the confined ice phases follow Arrhenius laws. While the values of τ depend on the pore diameter, freezable water in various types of confinements and mixtures shows similar activation energies of Ea ≈ 0.43 eV.

Schatzker IV tibial plateau fractures: are they always unicondylar?

Objective: The objectives of this study were to describe the incidence and morphology of medial tibial plateau fractures that extend into the lateral articular surface and to describe trends in their management. Design: Retrospective. Setting: Level I Urban Trauma Center. Patients: Seventy consecutive patients sustaining OTA/AO 41 B1 and B3 fractures. Intervention: Open reduction internal fixation of medial tibial plateau fractures. Main Outcome Measurements: Incidence of medial tibial plateau fractures that extend into the lateral articular surface. Secondary outcomes include localization of lateral articular surface depression, neurovascular injury, and trends in surgical management. Results: Seventy patients were included with 9 fractures (12.9%) isolated to the medial condyle (MC) and 61 fractures (87.1%) extending to the lateral condyle (LC). Compartment syndrome was present in 2 patients (2.9%), peroneal nerve palsy in 2 (2.9%), and arterial injury in 1 (1.4%). Initial external fixation was used more frequently in the LC group compared with the MC group (P = 0.028). Of the 61 fractures in the LC group, 49 (80.3%) included lateral articular surface depression which localized to the posteromedial quadrant of the lateral articular surface in 36 of 49 fractures (73.5%). Lateral articular surface depression depth ≥10.6 mm was associated with the use of dual incisions (P < 0.001). Conclusions: Schatzker IV fractures frequently extend to the lateral condyle and often present with depression of the posteromedial lateral articular surface. Fractures with lateral articular surface depression depth ≥10.6 mm were more likely to undergo fixation with dual incisions. Level of Evidence: Therapeutic level IV.

Arthroscopic Fractional Lengthening After Total Hip Arthroplasty Results in Improved Patient-Reported Outcomes and Low Rates of Revision Total Hip Arthroplasty.

Purpose: To report the clinical outcomes and reoperation rates of arthroscopic and endoscopic iliopsoas release at short-term follow-up after ipsilateral total hip arthroplasty (THA) at 2 separate medical institutions and to evaluate whether demographic and radiographic parameters are associated with postoperative patient-reported outcomes (PROs). Methods: Patients with iliopsoas tendinitis in the setting of prior THA who underwent arthroscopic iliopsoas fractional lengthening from 1988 to 2023 at 2 academic institutions were reviewed. Patients were included if they had 12 months of follow-up and underwent evaluation of preoperative anterior acetabular component overhang, surgery satisfaction, postoperative subjective hip flexion strength and anterior groin pain improvement, modified Harris Hip Score, Single Assessment Numeric Evaluation score, Tegner activity scale score, visual analog scale (VAS) score, and revision hip arthroplasty. Results: Sixty hips in 58 patients (19 male and 39 female patients) were followed up for a mean of 39.3 months (range, 12.0-105.9 months) postoperatively. Of the patients, 77% reported feeling "much better" or "slightly better," 75% reported improved anterior groin pain, and 60% reported improved subjective hip flexion strength. The surgery satisfaction rating was 7.2 ± 3.3 (scale of 0 to 10). The mean postoperative modified Harris Hip Score, VAS score for pain at rest, VAS score for pain with use, and Single Assessment Numeric Evaluation score were 73.9 ± 19.4, 1.3 ± 2.4, 3.8 ± 2.9, and 71.9 ± 21.9, respectively. Preoperative anterior acetabular component overhang was 3.3 ± 6.5 mm and did not significantly correlate with postoperative PROs (P ≥ .45). The Tegner score improved from 2.5 ± 1.7 preoperatively to 2.9 ± 1.4 postoperatively (P = .0253). Three patients underwent revision arthroplasty at a mean of 25.3 months (range, 11.6-40.4 months) postoperatively, with an acetabular component revision rate of 3.3%. Conclusions: Satisfactory outcomes and low revision arthroplasty rates were observed in patients undergoing arthroscopic iliopsoas lengthening after THA. There was no statistically significant relation between anterior acetabular component overhang and final PROs. Level of Evidence: Level IV, therapeutic case series.

Primary Hip Arthroscopy is Associated with Earlier Achievement of Substantial Clinical Benefit Compared to Revision Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

PURPOSE: To compare time to achievement of clinically significant outcomes (CSOs) between patients undergoing primary and revision hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS). METHODS: Patients undergoing primary and revision HA for FAIS with complete 6-month, 1-year, and 2-year Hip Outcome Score - Activities of Daily Living (HOS-ADL) and Sport Subscale (HOS-SS) were identified. Revision patients were propensity matched 1:4 to primary HA patients, controlling for age, sex, and body mass index (BMI). Time to achievement of minimal clinically important difference (MCID) and substantial clinical benefit (SCB) were compared alongside cumulative CSO achievement at 6, 12, and 24 months. Hazard ratios (HR) for predictors of earlier CSO achievement were identified with multivariate Cox regressions. RESULTS: Fifty revision HA patients were propensity-matched to 200 primary HA patients of similar age, sex, and BMI. Primary HA patients demonstrated a greater prevalence of regular preoperative physical activity (87% vs. 59%, p<0.001). Primary HA patients showed significantly greater SCB achievement for HOS-ADL at 6, 12, and 24 months (p<0.001) and significantly greater SCB achievement for HOS-SS at 12 and 24 months (p≤0.001) compared to revision HA patients. Primary HA patients achieved SCB for HOS-ADL (p<0.001) and HOS-SS (p=0.015) quicker than revision HA patients. Predictors of earlier CSO achievement included preoperative PRO score (HR: 0.98-1.02, p≤0.007), lower BMI (HR: 0.97, p=0.038), presence of physical activity (HR: 1.51, p=0.038), and absence of revision status (HR: 0.52-0.56, p≤0.019). CONCLUSIONS: Primary HA patients showed a quicker time to SCB achievement for HOS-ADL and HOS-SS compared to revision HA patients. Preoperative PRO score, lower BMI, regular physical activity, and primary HA status predicted earlier CSO achievement. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Treatment of Hip Cartilage Defects in Athletes.

Chondral defects in the athlete's hip are a relatively common occurrence, often presenting with debilitating pain and activity limitation. Preoperative identification of cartilage defects is challenging and there are many different modalities for treatment. Nonsurgical interventions, including activity modification, physical therapy, and injections, play a vital role, especially in less severe cases and as adjuncts to surgical intervention. Treating surgeons must be familiar with the cartilage restoration procedures available, including debridement, microfracture, and various implantation and transplantation options. Safe and effective management of cartilage defects is imperative to an athlete's return to sport. It is also imperative that surgeons are aware of all these various treatment options to determine what modality is best for their patients. This review serves to outline these options, cover the published literature, and provide general guidelines for surgeons when they encounter chondral defects in the office and the operating room.

Open and Endoscopic Gluteus Medius and/or Minimus Repair Achieves Clinical Success Regardless of Tear Grade: High-Grade Fatty Infiltration Portends Worse Outcomes.

PURPOSE: To evaluate minimum 2-year gluteus medius and/or minimus repair clinical success rates stratified by the 3-grade magnetic resonance imaging (MRI)-based classification (MRI grade) and to evaluate clinical success rates by the surgical approach used at each MRI grade and by the Goutallier-Fuchs (GF) classification. METHODS: A retrospective review identified patients who underwent primary endoscopic or open gluteus medius and/or minimus repair from 2012 to 2021 performed by a single surgeon. Preoperative MRI scans were classified using the MRI grade and GF classification. Patient-reported outcomes were collected preoperatively and at minimum 2-year follow-up. Cohort-specific minimal clinically important difference and patient acceptable symptom state achievement was recorded. Rates of clinical success, defined as achievement of the 2-year minimal clinically important difference or patient acceptable symptom state with avoidance of revision surgery, were compared by MRI grade, by surgical approach at each MRI grade, and by GF classification. RESULTS: A total of 112 patients (71 with MRI grade 1, 19 with grade 2, and 22 with grade 3) were included. MRI grade 1 patients underwent endoscopic repair (P < .001) more often than the other groups. The overall clinical success rate was 90%. Clinical success rates by MRI grade were 93% for grade 1, 95% for grade 2, and 77% for grade 3 (P = .087). Clinical success rates by the endoscopic and open surgical approaches used at each MRI grade were 93% versus 90% for grade 1 (P = .543), 91% versus 100% for grade 2 (P > .999), and 60% versus 92% for grade 3 (P = .135). GF grade 1 tears achieved a higher rate of clinical success than GF grade 4 tears (100% vs 71%, P = .030). CONCLUSIONS: Primary repair of gluteus medius and/or minimus tears resulted in clinical success in most patients irrespective of MRI grade and irrespective of the surgical approach used at each MRI grade, yet GF grade 1 tears showed a significantly higher clinical success rate than GF grade 4 tears. LEVEL OF EVIDENCE: Level IV, prognostic retrospective case series.

Association of Patient Satisfaction 2 Years After Hip Arthroscopy for Femoroacetabular Impingement Syndrome With Minimum 10-Year Patient-Reported Outcomes and Survivorship.

BACKGROUND: Previous studies have shown that short-term outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) predict midterm outcomes, but a limited number of studies have evaluated whether short-term outcomes predict long-term outcomes and survivorship. PURPOSE: To evaluate whether achieving clinically significant outcomes at 2 years after hip arthroscopy for FAIS can predict patient-reported outcomes (PROs) and survivorship at 10 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients who underwent primary hip arthroscopy for FAIS between June 2012 and December 2012 with a minimum 10-year follow-up were identified. Using previously established thresholds, we classified patients who achieved the 2-year Patient Acceptable Symptom State (PASS) for the visual analog scale (VAS) for satisfaction as the high satisfaction group and patients who did not as the low satisfaction group. Minimum 10-year PROs were then compared between the groups, including scores for the Hip Outcome Score (HOS)-Activities of Daily Living and -Sports Specific, the modified Harris Hip Score, the VAS for pain, and the VAS for satisfaction. Reoperation-free survivorship was compared. RESULTS: Of 120 eligible consecutive patients, 85 patients were included (70.8% follow-up rate), of whom 61.2% were female. The mean age was 34.0 ± 12.8 years, and the mean body mass index was 25.4 ± 4.6. Of the 85 patients, 29 (34.1%) did not achieve PASS for the VAS for satisfaction at 2 years postoperatively compared with 56 (65.9%) who did. The low satisfaction group had significantly worse acetabular chondral grades at the time of surgery (P = .008). At minimum 10-year follow-up, the high satisfaction group showed significantly better HOS-Activities of Daily Living, HOS-Sports Specific, modified Harris Hip Score, VAS pain, and VAS satisfaction scores (P≤ .031). Compared with the low satisfaction group, the high satisfaction group had a significantly lower rate of secondary surgery (1.8% vs 24.1%, respectively; P = .002). CONCLUSION: Patients who achieved PASS for the VAS for satisfaction at 2 years after hip arthroscopy demonstrated superior minimum 10-year outcomes compared with patients who did not, including greater PRO scores and a higher survivorship rate. The high satisfaction group had lower grade acetabular cartilage damage at the time of surgery compared with those who did not achieve PASS for the VAS for satisfaction at 2 years.

Molecular Dynamics Study of the Green Solvent Polyethylene Glycol with Water Impurities.

Polyethylene glycol (PEG) is one of the environmentally benign solvent options for green chemistry. It readily absorbs water when exposed to the atmosphere. The Molecular Dynamics (MD) simulations of PEG200, a commercial mixture of low molecular weight polyethyelene glycol oligomers, as well as di-, tetra-, and hexaethylene glycol are presented to study the effect of added water impurities up to a weight fraction of 0.020, which covers the typical range of water impurities due to water absorption from the atmosphere. Each system was simulated a total of four times using different combinations of two force fields for the water (SPC/E and TIP4P/2005) and two force fields for the PEG and oligomer (OPLS-AA and modified OPLS-AA). The observed trends in the effects of water addition were qualitatively quite robust with respect to these force field combinations and showed that the water does not aggregate but forms hydrogen bonds at most between two water molecules. In general, the added water causes overall either no or very small and nuanced effects in the simulation results. Specifically, the obtained water RDFs are mostly identical regardless of the water content. The added water reduces oligomer hydrogen bonding interactions overall as it competes and forms hydrogen bonds with the oligomers. The loss of intramolecular oligomer hydrogen bonding is in part compensated by oligomers switching from inter- to intramolecular hydrogen bonding. The interplay of the competing hydrogen bonding interactions leads to the presence of shallow extrema with respect to the water weight fraction dependencies for densities, viscosities, and self-diffusion coefficients, in contrast to experimental measurements, which show monotonous dependencies. However, these trends are very small in magnitude and thus confirm the experimentally observed insensitivity of these physical properties to the presence of water impurities.

Primary and Revision Hip Arthroscopy in Borderline Hip Dysplasia Shows Comparable Outcomes at a Minimum 5-Year Follow-Up.

PURPOSE: To compare patient-reported outcomes (PROs), achievement of clinically significant outcomes, and reoperation-free survivorship between primary and revision hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) in propensity-matched borderline hip dysplasia (BHD) patients at a minimum 5-year follow-up. METHODS: Patients with BHD, characterized by a lateral center-edge angle 18° to 25°, who underwent HA for FAIS with capsular repair by a single surgeon between January 2012 and June 2018 with a minimum 5-year follow-up were identified. Cases of revision HA were propensity-matched 1:2 to cases of primary HA, controlling for age, sex, and body mass index. A 1:2 ratio was chosen to maximize the number of included patients. Collected PROs included Hip Outcome Score-Activities of Daily Living and Sport Subscales, International Hip Outcome Score 12, modified Harris Hip Score, and Visual Analog Scale for Pain. Achievement of minimal clinically important difference, patient acceptable symptom state, and substantial clinical benefit for any measured PRO was compared between groups along with reoperation-free survivorship using Kaplan-Meier analysis. RESULTS: Thirty-six revision HA hips (34 patients) were propensity-matched to 72 primary HA hips (70 patients). The groups were similar in age (31.5 ± 10.3 years vs 30.5 ± 11.2, P = .669), sex (69.4% female vs 70.8%, P = .656), and body mass index (25.7 ± 4.0 vs 25.5 ± 3.7, P = .849). The revision group showed a greater prevalence of prolonged preoperative pain (50.0% vs 27.8%, P = .032) compared with the primary group. A significant improvement in all PROs was observed for both groups with comparable PROs preoperatively and at the 5-year follow-up between groups (P ≥ .086). The revision and primary groups showed comparable minimal clinically important difference (95.0% vs 95.7%, P ≥ .999), patient acceptable symptom state (80.0% vs 83.6%, P = .757), and substantial clinical benefit (62.5% vs 70.7%, P = .603) achievement for any PRO. Comparable reoperation-free survivorship was observed (P = .151). CONCLUSIONS: Propensity-matched patients with BHD undergoing primary and revision hip arthroscopy for FAIS achieved similar minimum 5-year PROs, clinically significant outcomes, and reoperation-free survivorship. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.

Structures and Dynamics of Complex Guest Molecules in Confinement, Revealed by Solid-State NMR, Molecular Dynamics, and Calorimetry.

This review gives an overview of current trends in the investigation of confined molecules such as water, small and higher alcohols, carbonic acids, ethylene glycol, and non-ionic surfactants, such as polyethylene glycol or Triton-X, as guest molecules in neat and functionalized mesoporous silica materials employing solid-state NMR spectroscopy, supported by calorimetry and molecular dynamics simulations. The combination of steric interactions, hydrogen bonds, and hydrophobic and hydrophilic interactions results in a fascinating phase behavior in the confinement. Combining solid-state NMR and relaxometry, DNP hyperpolarization, molecular dynamics simulations, and general physicochemical techniques, it is possible to monitor these confined molecules and gain deep insights into this phase behavior and the underlying molecular arrangements. In many cases, the competition between hydrogen bonding and electrostatic interactions between polar and non-polar moieties of the guests and the host leads to the formation of ordered structures, despite the cramped surroundings inside the pores.

Outcomes of Flexibility Sport Athletes With Borderline Hip Dysplasia After Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Analysis at Minimum 2-Year Follow-up.

BACKGROUND: Hip arthroscopy has proved successful in treating femoroacetabular impingement syndrome (FAIS) in patients with and without borderline hip dysplasia (BHD). Despite a high prevalence of BHD in patients who participate in sports with high flexibility requirements, a paucity of literature evaluates the efficacy of hip arthroscopy in treating FAIS in flexibility sport athletes with BHD. PURPOSE: To compare minimum 2-year patient-reported outcomes (PROs) and achievement of clinically significant outcomes in flexibility sport athletes with BHD undergoing primary hip arthroscopy for FAIS with capsular plication with results in flexibility sport athletes without dysplasia. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Data were prospectively collected for patients undergoing primary hip arthroscopy for FAIS with BHD, defined as a lateral center-edge angle of 18° to 25°, who reported participation in a sport with a high flexibility requirement, including dance, gymnastics, figure skating, yoga, cheerleading, and martial arts, according to previous literature. These patients were matched 1:2 to flexibility sport athletes without dysplasia, controlling for age, sex, and body mass index. Preoperative and minimum 2-year postoperative PROs were collected and compared between groups. Cohort-specific minimal clinically important difference and patient acceptable symptom state achievement was compared between groups. RESULTS: In total, 52 flexibility sport athletes with BHD were matched to 104 flexibility sport athletes without BHD. Both groups showed similar sport participation (P = .874) and a similar level of competition (P = .877). Preoperative lateral center-edge angle (22.2°± 1.6° vs 31.5°± 3.9°; P < .001) and Tönnis angle (10.9°± 3.7° vs 5.8°± 4.4°; P < .001) differed between groups. Capsular plication was performed in all cases. Both groups achieved significant improvement in all PROs (P < .001) with no differences in postoperative PROs between groups (P≥ .147). High minimal clinically important difference (BHD group: 95.7%; control group: 94.8%) and patient acceptable symptom state (BHD group: 71.7%; control group: 72.2%) achievement for any PRO was observed with no differences between groups (P≥ .835). CONCLUSION: Flexibility sport athletes with BHD achieved similar outcomes as those of flexibility sport athletes without BHD after hip arthroscopy for FAIS with capsular plication.

Hip Arthroscopy Patients With Lower Back Pain Show Delayed Clinical Improvement and Inferior Time-Dependent Survivorship: A Propensity Matched Study at Mid-Term Follow-Up.

PURPOSE: To evaluate patient-reported outcomes (PROs) and survivorship at mid-term follow-up after hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) in patients with and without preoperative lower back pain (LBP). METHODS: Patients with self-endorsed preoperative LBP who underwent HA for FAIS with mid-term follow-up were identified and propensity matched 1:1 to patients without back pain by age, sex, and body mass index (BMI). PROs collected preoperatively and at postoperative years 1, 2, and 5 included Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Hip Outcome Score-Sports Subscale (HOS-SS), 12-item International Hip Outcome Tool (iHOT-12), modified Harris Hip Score (mHHS), and Visual Analog Scale (VAS) for Pain. Achievement of minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were compared. Survivorship was compared with Kaplan-Meier analysis. RESULTS: In total, 119 patients with LBP were matched to 119 patients without LBP. Group demographic factors were as follows: age (37.4 ± 11.9 vs 37.6 ± 12.6 years, P = .880), sex (64.4% vs 67.7% female, P = .796), and BMI (25.3 ± 5.1 vs 25.3 ± 5.4, P = .930). Average follow-up duration was 6.0 ± 1.9 years. LBP patients showed similar preoperative PROs, yet lower 1-year scores for all PROs (P ≤ .044). At final follow-up, similar PROs were shown between groups (P ≥ .196). LBP and non-LBP patients had similar MCID achievement for HOS-ADL (59.3% vs 63.1%, P = .640), HOS-SS (73.9% vs 70.8%, P = .710), mHHS (66.7% vs 73.4%, P = .544), iHOT-12 (85.1% vs 79.4%, P = .500), and VAS Pain (75.6% vs 69.9%, P = .490). Groups also had similar PASS achievement for HOS-ADL (63.5% vs 61.3%, P = .777), HOS-SS (57.0% vs 62.5%, P = .461), mHHS (81.9% vs 79.1%, P = .692), iHOT-12 (54.6% vs 61.2%, P = .570), and VAS Pain (51.0% vs 55.4%, P = .570). Additionally, achievement of MCID ≥ 1 PRO (P ≥ .490) and PASS ≥ 1 PRO (P ≥ .370) was similar across groups. Conversion to total hip arthroplasty occurred in 3.4% of hips with LBP and 0.8% of hips without LBP (P = .370). Back pain patients demonstrated inferior time-dependent survivorship compared with patients without back pain on Kaplan-Meier survival analysis (P = .023). CONCLUSIONS: Patients undergoing primary hip arthroscopy for FAIS with LBP achieve comparable PROs and clinically significant outcomes to patients without back pain at mid-term, despite lower 1-year PRO scores. LBP patients show inferior reoperation-free time-dependent survivorship compared with those without LBP. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.

Six-Month Outcomes Correlate With 10-Year Outcomes After Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

PURPOSE: To identify whether 6-month outcomes after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) correlate with outcomes at minimum 10-year follow-up. METHODS: Patients who underwent primary hip arthroscopy for FAIS from 2012 to 2013 were reviewed and included if they had 6-month and minimum 10-year follow-up. Patient-reported outcome (PRO) measures included the Hip Outcome Score Activities of Daily Living (HOS-ADL) subscale, Hip Outcome Score Sports-Specific (HOS-SS) subscale, modified Harris Hip Score (mHHS), visual analog scale (VAS) for pain, and VAS for satisfaction. We compared 6-month and 10-year outcome scores and analyzed the relations between 6-month and 1-, 2-, 5-, and 10-year outcome scores using Pearson correlation coefficients (r). Six-month scores and clinically significant outcome achievement were then compared with 10-year clinically significant outcome achievement and reoperations, including revision hip arthroscopy and conversion to total hip arthroplasty (THA), using logistic regressions and the Fisher exact test. RESULTS: This study included 60 patients (60.0% female sex; mean age, 36.0 ± 12.2 years). The mHHS, VAS pain score, and VAS satisfaction score significantly improved from 6-month to 10-year follow-up (P ≤ .021), whereas the HOS-ADL and HOS-SS did not (P ≥ .072). There were significant correlations between 6-month and 10-year scores for the HOS-ADL (r = 0.505), HOS-SS (r = 0.592), and mHHS (r = 0.362) (P ≤ .022 for all), as well as significant correlations between 6-month and 1-, 2-, and 5-year scores (P ≤ .014 for all). The 6-month HOS-ADL, HOS-SS, and mHHS were all significantly associated with their respective 10-year achievement of the patient acceptable symptom state (PASS) (P ≤ .044). Furthermore, 6-month HOS-ADL and mHHS were significantly associated with THA conversion (P ≤ .041). Comparable 6-month and 10-year achievement of the minimal clinically important difference (96.5% vs 97.8%, P > .999) and PASS (85.2% vs 87.5%, P > .999) for any PRO was observed. CONCLUSIONS: After hip arthroscopy for FAIS, patients' 6-month HOS-ADL and mHHS were significantly associated with their 10-year PROs, PASS achievement, and THA conversion, although correlation strengths decreased with increasing time from surgery. LEVEL OF EVIDENCE: Level IV, case series.

Elastin-Like Peptide as a Model for Disordered Proteins: Diffusion Behaviour in Self-Crowding Conditions.

Despite the current high interest, there is limited information on diffusion data for intrinsically disordered proteins (IDPs). This study investigates the effect of crowding on the diffusion behaviour of an elastin-like peptide (ELP), by combined pulse field gradient (PFG) and static field gradient (SFG) NMR techniques. We interpret our findings in terms of highly dynamic chain assemblies with weak interactions, resulting in ELP diffusion that is primarily governed by the viscous flow of the solvent. The diffusion behaviour of the peptide appears to resemble that of globular proteins rather than flexible linear polymers over a wide concentration range.

Gluteus Repair Yields Satisfactory Clinically Significant Outcome Achievement by 1 Year in Mostly Partial-Thickness Tears With Preoperative Hip Abduction Weakness Associated With Delayed Achievement.

PURPOSE: To define the time to achievement of clinically significant outcomes (CSOs) after primary gluteus medius and/or minimus (GM) repair and to identify factors associated with delayed CSO achievement. METHODS: Patients who underwent primary GM repair between January 2012 and June 2021 with complete preoperative, 6-month, 1-year, and 2-year Hip Outcome Score-Activities of Daily Living (HOS-ADL) were retrospectively identified. Cohort-specific minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were calculated. The time to achievement of MCID and PASS was analyzed using Kaplan-Meier survival analysis. Median time to MCID and PASS achievement was recorded. Multivariate stepwise Cox regressions were used to identify factors associated with delayed CSO achievement. RESULTS: Fifty GM repairs were identified (age 59.4 ± 9.7 years, body mass index 27.9 ± 6.2, 94% female). Tears were grade 1 in 39 cases, grade 2 in 7 cases, and grade 3 in 4 cases. Endoscopic repair was performed in 35 cases, and open repair was performed in 15 cases. Labral debridement and repair were each performed in 15 cases. Median time to CSO achievement was 5.7 months for MCID and 11.0 months for PASS. The 2-year cumulative probability of MCID and PASS achievement was 92.7% and 66.7%, respectively. Preoperative hip abduction weakness on physical examination was associated with delayed achievement of MCID (hazard ratio 2.27, confidence interval 1.067-7.41, P = .039) and PASS (hazard ratio 3.89, confidence interval 1.341-11.283, P = .012). CONCLUSIONS: This study demonstrated that in patients undergoing repair of primarily grade 1 GM tears, most achieved MCID by 6 months, and more than one half achieved PASS by 12 months. Preoperative hip abduction weakness on physical examination was associated with delayed CSO achievement. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Cartilage Defects Are Negatively Associated With Long-Term Hip Survivorship Following Contemporary Hip Arthroscopy for Femoroacetabular Impingement Syndrome: A Propensity-Matched Analysis at Minimum 10-Year Follow-Up.

PURPOSE: To identify the timing and risk factors associated with secondary surgery following primary hip arthroscopy for femoroacetabular impingement syndrome (FAIS) at 10-year minimum follow-up. METHODS: A prospectively collected clinical repository was evaluated for cases of primary hip arthroscopy for FAIS between January 2012 and February 2013 with minimum 10-year follow-up. Patients who underwent secondary surgery were propensity matched 1:4 to patients who did not undergo secondary surgery, controlling for age, sex, and body mass index (BMI). The groups were compared on demographics, radiographs, intraoperative findings, operative procedures, and patient-reported outcomes. A Kaplan-Meier survivorship curve was generated. Among the reoperation-free survivors, minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) achievement were recorded for Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Specific (HOS-SS) subscales, modified Harris Hip Score (mHHS), 12-item international Hip Outcome Tool (iHOT-12), and Visual Analog Scale for Pain (VAS Pain). RESULTS: Twenty-four reoperation patients (67% female; age 40.1 ± 14.3 years; BMI 27.2 ± 5.5) were matched to 96 reoperation-free patients (62% female; age 37.0 ± 10.8 years; BMI 25.2 ± 4.7, P ≥ .111). Mean follow-up was 10.3 ± 0.2 years. No preoperative demographic differences were found between groups. The reoperation group showed more high-grade cartilage defects on the acetabulum and femoral head (33% vs 8%, P = .004; 29% vs 7%, P = .007). A bimodal distribution of time to reoperation was evidenced independent of the secondary surgery performed. Among the reoperation-free survivors, MCID and PASS achievement was as follows: HOS-ADL (69.1%, 62.1%), HOS-SS (69.9%, 74.4%), mHHS (73.3%, 58.1%), iHOT-12 (n/a, 63.8%), and VAS-Pain (80.2%, 62.6%). CONCLUSIONS: Patients requiring reoperation following primary hip arthroscopy for FAIS demonstrated more severe cartilage defects and a bimodal distribution of time to reoperation. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.

The Promising 2-Year Performance of the Patient-Reported Outcomes Measurement Information System in Primary Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

BACKGROUND: Minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) thresholds have been previously defined for the Patient-Reported Outcomes Measurement Information System (PROMIS) at 1-year follow-up in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome; however, the MCID and PASS thresholds are yet to be defined for the PROMIS at 2-year follow-up. PURPOSE: (1) To establish MCID and PASS thresholds for the PROMIS Pain Interference (PROMIS-PI) and PROMIS Physical Function (PROMIS-PF) at 2-year follow-up and (2) to correlate PROMIS scores with hip-specific patient-reported outcome measure (PROM) scores. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Patients undergoing primary hip arthroscopy for femoroacetabular impingement syndrome between August and November 2020 with preoperative and minimum 2-year postoperative data were identified. Collected scores included those for the PROMIS-PI, PROMIS-PF, Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SS), International Hip Outcome Tool-12 (iHOT-12), and visual analog scale (VAS) for pain. MCID thresholds were calculated using the distribution-based method and PASS thresholds using the anchor-based method. Pearson correlation coefficients were used to compare scores between PROMs. RESULTS: A total of 65 patients met the criteria for inclusion (72.3% female; mean age, 36.9 ± 13.5 years; mean body mass index, 26.2 ± 6.0). The mean follow-up was 25.3 ± 3.3 months. Significant preoperative to postoperative improvements were observed for all PROMs (P < .001). MCID thresholds and achievement rates were as follows: HOS-ADL, 10.1 and 75%, respectively; HOS-SS, 13.8 and 79%, respectively; iHOT-12, 14.0 and 67%, respectively; VAS pain, -13.8 and 78%, respectively; PROMIS-PI, -4.7 and 65%, respectively; and PROMIS-PF, 5.8 and 60%, respectively. PASS thresholds and achievement rates were as follows: HOS-ADL, 78.7 and 67%, respectively; HOS-SS, 76.4 and 62%, respectively; iHOT-12, 67.4 and 60%, respectively; VAS pain, 25.5 and 61%, respectively; PROMIS-PI, 57.0 and 65%, respectively; and PROMIS-PF, 45.6 and 58%, respectively. PROMIS-PI scores correlated most strongly with HOS-ADL (r = -0.836), HOS-SS (r = -0.767), and iHOT-12 (r = -0.719) scores and exhibited at least moderate correlations (r≥-0.595) with the other PROM scores. PROMIS-PF demonstrated moderate correlations with all the other PROM scores (r≥-0.586). Strong correlations were seen between the hip-specific PROM scores (r≥-0.745). CONCLUSION: This study defined 2-year MCID and PASS thresholds for the PROMIS-PI and PROMIS-PF and demonstrated moderate to strong correlations between PROMIS scores and hip-specific PROM scores.

Ice-Water Equilibrium in Nanoscale Confinement.

We show that 2D ^{2}H NMR spectra enable valuable insights into the nature of an ice-water equilibrium in nanoscale confinement, which extends over a broad temperature range. In particular, 2D ^{2}H NMR line-shape analysis allows us to determine the timescale on which the coexisting ice and water phases exchange molecules. For D_{2}O in a silica nanopore with a diameter of 5.4 nm, we find that the residence time of a water molecule in either phase is characterized by an NMR exchange time of τ_{X}=5.7 ms at 220 K. Thus, the ice-water equilibrium is highly dynamic, which is an important aspect for an understanding of deeply cooled confined and, possibly, bulk waters.

Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework.

Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts. We report on the synthesis and postsynthetic sulfonation of an aromatic framework (SPAF-2) with a 3D-interconnected nanoporosity and varying sulfonation degrees. Water adsorption produces the system SPAF-2H20. It features proton exchange capacities up to 6 mequiv g-1 and exceptional proton conductivities of about 1 S cm-1. Two contributions are essential for the highly efficient transport. First, the nanometer-sized pores link the charge transport to the diffusion of adsorbed water molecules, which is almost as fast as bulk water. Second, continuous exchange between interface-bound and mobile species enhances the conductivities at elevated temperatures. SPAF-2H20 showcases how to tailor nanostructured electrolyte-host systems with liquid-like conductivities.

Transport Mechanism in Nafion Revealed by Detailed Comparison of 1H and 17O Nuclear Magnetic Resonance Diffusion Coefficients.

We use 1H and 17O NMR static field gradient diffusometry to measure self-diffusion coefficients of protons (DH) and oxygens (DO) in Nafion 212 with various hydration levels (λ = 4-18). For all samples and both nuclei, we obtain activation energies (Ea) of ≈0.19 eV. Analyzing the hydration-level dependence of DH and DO, we find DO/DH ≈ 1 at λ ≈ 18, resembling the situation in bulk water, while oxygen diffusion becomes faster than proton diffusion when the water content is decreased, leading to DO/DH ≈ 1.2 at λ ≈ 4. A comparison with literature data for acidic bulk solutions implies that faster oxygen than proton diffusion results from the existence of the polymer framework. To rationalize the observed ratios DO/DH ≥ 1, we consider a bimodal dynamical model in which the interactions of H+(H2O)m ions with neighboring SO3- groups lead to slower water dynamics in the vicinity of the polymer framework than in the center of the water nanochannels.