Editorial Commentary: The entry point-trochlear groove (EP-TG) angle measures lateralization of the proximal trochlear entry point in patients with patellar instability.

Patellar instability is a complex orthopedic condition, occurring at an incidence of 23.2 per 100,000 person-years, and resulting from a combination of osseous and soft tissue factors. Osseous abnormalities associated with patellar instability include trochlear dysplasia and a lateralized tibial tubercle. Evaluation of these factors includes dysplasia evaluation using the DeJour classification, and the tibial-tubercle-to-trochlear-groove distance (TT-TG) to evaluate relative lateralization of the tibial tubercle. Three-dimensional modeling has advanced the evaluation of complex trochlea geometry and patellar tracking. Evaluation of the TT-TG distance through flexion, dubbed the radial TT-TG (rTT-TG) distance, shows rTT-TG distances are notably larger than traditional TT-TG measurements, with increasing grade of dysplasia associated with a more pronounced difference between measurements. The entry point-trochlear groove (EP-TG) angle may help more accurately describe the morphology of the proximal trochlea and aid in planning or assessing osseous correction with a trochleoplasty. The EP-TG angle may also be of use as a variable to determine when an isolated medial patellofemoral ligament reconstruction (MPFLR) may fail and require osseous correction. A lateralized proximal trochlea entry point is associated with recurrent patellar instability.

Subacromial Balloon Spacer for Irreparable Rotator Cuff Tear Treatment Shows Improved Pain and Strength at 5-Year Follow-Up.

PURPOSE: To report on minimum 5-year outcomes following subacromial balloon spacer implantation (SBSI), in terms of survivorship, pain reduction, functional outcomes, complications, and reoperations. METHODS: Data were prospectively collected and retrospectively analyzed for consecutive patients undergoing SBSI between April 1, 2012, and June 30, 2016. Patients completed preoperative and postoperative follow-up for minimum 5 years on the following patient-reported outcomes (PROs): Constant-Murley Score (CMS), visual analog scale for pain (VAS), strength, and patient satisfaction. Reoperations and complications were recorded. Minimal detectable change (MDC) was calculated and the proportion of patients achieving MDC for CMS and VAS were calculated. RESULTS: During the study period, SBSI was performed in 36 patients. Three patients were deceased within 5 years. Of the remaining 33 patients, follow-up was available on 29 patients (80.6%). Mean age at the time of operation was 72.7 ± 4.5 years, and 69% of the patients were males. Mean follow-up time was 72.5 months. Significant improvements from preoperative to last follow-up were demonstrated in CMS (36.08 vs. 63.88; P < .001), VAS (6.72 vs. 1.68; P < .001), and strength (3.8 vs 5.87 kg; P < .001). These improvements were demonstrated at 3 weeks, 6 months, 12 months, 24 months, and 60 months. Mean patient satisfaction at last follow-up was 8.72. The MDC for both CMS and VAS was achieved by 75.9% (22/29) of patients. Four patients underwent conversion to a reverse total shoulder arthroplasty (RTSA). Complications included one patient with balloon dislocation and one patient with a secondary infection due to urinary tract infection. CONCLUSIONS: Pain reduction and functional improvements are sustained at minimum 5 years after SBSI in patients with irreparable rotator cuff tears. The 5-year conversion rate to an RTSA was 13.79%. LEVEL OF EVIDENCE: Level IV, retrospective case-series.

Staged Hip Arthroscopy with Labral Repair, Femoroplasty, and Capsular Plication Followed by Periacetabular Osteotomy for Hip Dysplasia Results in Improved Outcomes and 100% Survivorship at Minimum 2-Year Follow-Up.

PURPOSE: To assess patient-reported outcomes (PROs), clinically significant outcomes (CSOs), and survivorship following staged hip arthroscopy with labral repair, femoroplasty, and capsular plication followed by periacetabular osteotomy (PAO) for the management of femoroacetabular impingement syndrome (FAIS) and hip dysplasia (lateral center edge angle ≤25°). METHODS: A prospectively maintained database was queried to retrospectively identify patients who underwent staged primary hip arthroscopy and PAO between 1/2018-10/2021 and had a minimum 2-year follow-up. PROs collected included, Hip Outcome Score Activities of Daily Living/Sports Subscale (HOS-ADL/SS), international Hip Outcome Tool-12 item questionnaire (iHOT-12), and Visual Analog Scale for Pain (VAS Pain). CSO achievement for minimal clinical important difference (MCID) and patient acceptable symptom state (PASS) were determined through cohort specific thresholds. Rates of reoperation, including, revision hip arthroscopy and conversion to total hip arthroplasty (THA) were evaluated to determine short-term survivorship. RESULTS: Thirty-nine hips met criteria for inclusion, of which 35 hips had minimum 2-year follow up (89.7% compliance). Mean age was 25±9.1 years and 91.7% of patients were female. Respective pre- and postoperative radiographic outcomes were: Alpha angle 59.8±5.9 to 39.7±2.6°, Tönnis angle 14.6±5.6° to -1.0±2.9°, lateral center-edge angle 16.6±5.5° to 36.6±4.6°, and anterior center-edge angle 15.6±9.1° to 36.1±3.8°, with statistically significant differences pre- to postoperatively for all (P<0.001). Patients demonstrated significant improvement in all PROs pre- to postoperatively (P ≤0.004). MCID and PASS achievement rates for any PRO were 93.9% and 78.8%, respectively. There were no revision hip surgeries or conversion to THA at a mean 2.7±1.0-year follow-up. Four patients (11.1%) underwent hardware removal. One patient (2.8%) experienced a postoperative infection treated with incision and drainage. CONCLUSIONS: Staged hip arthroscopy and PAO for the management of hip dysplasia demonstrated improvement in PROs, high CSO achievement rates, and 100% survivorship at minimum 2-year follow-up.

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.

The Gut Microbiome and Joint Microbiome Show Alterations in Patients with Knee Osteoarthritis Versus Controls: A Systematic Review.

PURPOSE: To assess the current scientific literature on the microbiome's relationship with knee osteoarthritis (OA), with specific focuses on the gut microbiome-joint axis and joint microbiome-joint axis. METHODS: A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, searching PubMed, Embase, and Cochrane databases for relevant English-language clinical studies on the gut and/or joint microbiomes' association with knee OA in humans. Bias was evaluated using the methodological index for non-randomized studies score. RESULTS: Thirty-five thousand bacterial species comprise the gut microbiome; approximately 90% are members of the phyla Bacteroides and Firmicutes. Symbiosis between the gut microbiome and host under normal physiological conditions positively affects host growth, development, immunity, and longevity. Gut microbiome imbalance can negatively influence various physiological processes, including immune response, inflammation, metabolism, and joint health including development of knee OA. In addition, next generation gene sequencing suggests the presence of microorganisms in the synovial fluid of osteoarthritic knees, and distinct microbiome profiles detected are presumed to play a role in the development of OA. With regard to the gut microbiome, consistent alterations in microbial composition between OA patients and controls are noted, in addition to several associations between certain gut bacteria with OA-related knee pain, patient-reported outcome measure performance, imaging findings, and changes in metabolic and inflammatory pathways. Regarding the joint microbiome, studies revealed increased levels of lipopolysaccharide (LPS) and LPS-binding protein in synovial fluid are associated with activated macrophages, and correlated with worsened osteophyte severity, joint space narrowing, and pain scores in knee OA patients. In addition, studies demonstrated various microbial composition differences in OA patients compared to control, with certain joint microbes directly associated with OA pathogenesis, inflammation, and metabolic dysregulation. CONCLUSIONS: The gut microbiome-joint axis and joint microbiome shows alterations in microbial composition between osteoarthritic patients and controls. These alterations are associated with perturbations of metabolic and inflammatory pathways, imaging findings, osteoarthritis-related pain, and patient reported outcome measure performance. LEVEL OF EVIDENCE: Systematic Review; Level III.

Revision and Primary Meniscal Allograft Transplantations Provide Clinical Benefit at Mid-Term Follow-Up: A Matched-Cohort Analysis of Patient-Reported Outcomes, Reoperations, and Failures.

PURPOSE: To report the mid-term outcomes of patients who underwent revision meniscal allograft transplantation (RMAT) and compare survivorship free from reoperation and failure with a matched cohort of patients who underwent primary meniscal allograft transplantation (PMAT). METHODS: A retrospective review of prospectively collected data identified patients who underwent RMAT and PMAT between 1999 and 2017. A cohort of PMAT patients matched at a ratio of 2:1 with respect to age, body mass index, sex, and concomitant procedures served as the control group. Patient-reported outcome measures (PROMs) at baseline and at a minimum of 5 years postoperatively were collected. PROMs and the achievement of clinically significant outcomes were analyzed within groups. Graft survivorship free from meniscal reoperation and failure (arthroplasty or subsequent RMAT) was compared between cohorts using log-rank testing. RESULTS: During the study period, 22 RMATs were performed in 22 patients. Of these RMAT patients, 16 met the inclusion criteria (73% follow-up rate). The mean age of RMAT patients was 29.7 ± 9.3 years, and the mean follow-up period was 9.9 ± 4.2 years (range, 5.4-16.8 years). There were no differences between the RMAT cohort and the 32 matched PMAT patients with respect to age (P = .292), body mass index (P = .623), sex (P = .537), concomitant procedures (P ≥ .286), or baseline PROMs (P ≥ .066). The patient acceptable symptomatic state was achieved by the RMAT cohort for the subjective International Knee Documentation Committee score (70%), Lysholm score (38%), and Knee Injury and Osteoarthritis Outcome Score subscales (Pain [73%], Symptoms [64%], Sport [45%], Activities of Daily Living [55%], and Quality of Life [36%]). In the RMAT cohort, 5 patients (31%) underwent subsequent reoperation at a mean of 4.7 ± 2.1 years (range, 1.7-6.7 years) and 5 patients met the criteria for failure at a mean of 4.9 ± 2.9 years (range, 1.2-8.4 years). There were no significant differences in survivorship free from reoperation (P = .735) or failure (P = .170) between the RMAT and PMAT cohorts. CONCLUSIONS: At mid-term follow-up, most patients who underwent RMAT achieved the patient acceptable symptomatic state for the subjective International Knee Documentation Committee score and the Knee Injury and Osteoarthritis Outcome Score subscales of Pain, Symptoms, and Activities of Daily Living. Additionally, there were no differences in survival free from meniscal reoperation or failure between the PMAT and RMAT cohorts. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort.

Patient-Specific Variables Associated with Failure to Achieve Clinically Significant Outcomes After Meniscal Allograft Transplantation at Minimum 5 Year Follow-Up.

PURPOSE: To determine the improvements in patient-reported outcome measures (PROMs) necessary to achieve minimal clinically important difference (MCID), patient-acceptable symptomatic state (PASS), and substantial clinical benefit (SCB) after primary meniscal allograft transplantation (MAT) at a minimum of 5-year follow-up, while identifying variables predictive of achieving clinically significant outcomes (CSOs). METHODS: A retrospective review was performed to identify patients undergoing primary MAT at a single institution from 1999 to 2016. Lysholm, International Knee Documentation Committee (IKDC), and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales were collected before surgery and at a minimum of 5-year follow-up. A distribution-based approach was used to calculate MCID, whereas an anchor-based approach was used to calculate SCB and PASS. Multivariate logistic regression was performed to determine factors associated with CSO achievement. RESULTS: A total of 202 patients undergoing MAT (56% medial, 44% lateral) were included with a mean follow-up of 9.8 ± 4.1 years, age of 29.7 ± 8.5 years, and body mass index (BMI) of 26.5 ± 4.7. Thresholds for achieving MCID, PASS, and SCB, respectively, at a minimum 5-year follow-up for Lysholm (10.3, 74.5, 32.5), IKDC (12.1, 55.6, 29.1), and KOOS subscales questionnaires (Pain [11.0, 70.7, 25.1], Symptoms [11.0, 60.8, 19.6], Activities of Daily Living [10.5, 90.3, 17.9], Sport [16.2, 47.4, 37.5], and Quality of Life [13.6, 40.5, 37.3]) were calculated. Reduced odds of achieving MCID were associated with higher preoperative PROM scores, BMI, patient age, concomitant osteotomy, male sex, and worker's compensation (WC) status. Reduced odds of achieving PASS were associated with lower preoperative PROM scores, higher BMI (particularly ≥30), patient age, and WC status. Reduced odds of achieving SCB were associated with higher preoperative PROM scores and WC status. CONCLUSIONS: This study established the MCID, PASS, and SCB at 5-year minimum follow-up for the Lysholm score, IKDC, and KOOS subscales in patients who underwent MAT. Increased BMI and patient age, male sex, performance of concomitant osteotomy, WC status, and preoperative PROM scores were associated with failure to achieve CSOs after primary MAT at a minimum of 5-year follow-up. LEVEL OF EVIDENCE: Level IV, therapeutic study, retrospective case series.

The meniscotibial ligament role in meniscal extrusion: a systematic review and meta-analysis.

INTRODUCTION: The meniscotibial ligament (MTL) limits extrusion of the medial meniscus (MM). While meniscal extrusion may be detrimental to knee joint biomechanics, the role of the MTL in meniscal extrusion is debatable. We sought to perform a systematic review and meta-analysis to evaluate the role of the MTL and surgical techniques for MTL repair. MATERIALS AND METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines we searched PubMed, Cochrane Library, and Embase for: (("Meniscotibial") OR ("Coronary") OR ("Ramp")) AND ("Extrusion"). After screening and applying eligibility criteria, data were extracted for MTL pathology types ("traumatic" ruptures or "induced" injuries) and meniscal extrusion. A meta-analysis evaluated the mean difference of extrusion between "intact" MTLs (native or repaired) and "injured" MTLs (induced or traumatic). We further performed a subgroup analysis between traumatic and induced MTL lesions. RESULTS: This systematic review included six studies, which all evaluated MM extrusion. There were 74 knees with induced MTL injuries and 19 knees with traumatic MTL ruptures. Study designs were heterogenic and utilized three types of MTL repair procedures. The meta-analysis included 18 human knees and revealed that sectioning the MTL created a 2.92 mm [- 0.18 to 6.03] MM extrusion, while MTL repair decreased MM extrusion by - 2.11 mm [- 3.03 to - 1.21]. CONCLUSIONS: MTL injury may result in approximately 3 mm of MM extrusion, while repair of the MTL can decrease extrusion by 2 mm. Several novel surgical techniques exist to repair the MTL. However, studies reporting clinical outcomes of these various procedures are scarce.

Pearls and pitfalls of PROMIS clinically significant outcomes in orthopaedic surgery.

INTRODUCTION: Patient-Reported Outcome Measurement Information System (PROMIS) was developed as a uniform and generalizable PROM system using item response theory and computer adaptive testing. We aimed to assess the utilization of PROMIS for clinically significant outcomes (CSOs) measurements and provide insights into its use in orthopaedic research. MATERIALS AND METHODS: We reviewed PROMIS CSO reports for orthopaedic procedures via PubMed, Cochrane Library, Embase, CINAHL, and Web of Science from inception to 2022, excluding abstracts and missing measurements. Bias was assessed using the Newcastle-Ottawa Scale (NOS) and questionnaire compliance. PROMIS domains, CSO measures, and study populations were described. A meta-analysis compared distribution and anchor-based MCIDs in low-bias (NOS ≥ 7) studies. RESULTS: Overall, 54 publications from 2016 to 2022 were reviewed. PROMIS CSO studies were observational with increasing publication rates. Evidence-level was II in 10/54, bias low in 51/54, and compliance ≥ 86% in 46/54. Most (28/54) analysed lower extremity procedures. PROMIS domains examined Pain Function (PF) in 44/54, Pain Interference (PI) in 36/54, and Depression (D) in 18/54. Minimal clinically important difference (MCID) was reported in 51/54 and calculated based on distribution in 39/51 and anchor in 29/51. Patient acceptable symptom state (PASS), substantial clinical benefit (SCB), and minimal detectable change (MDC) were reported in ≤ 10/54. MCIDs were not significantly greater than MDCs. Anchor-based MCIDs were greater than distribution based MCIDs (standardized mean difference = 0.44, p < 0.001). CONCLUSIONS: PROMIS CSOs are increasingly utilized, especially for lower extremity procedures assessing the PF, PI, and D domains using distribution-based MCID. Using more conservative anchor-based MCIDs and reporting MDCs may strengthen results. Researchers should consider unique pearls and pitfalls when assessing PROMIS CSOs.

Concomitant Meniscotibial Ligament Reconstruction Decreases Meniscal Extrusion Following Medial Meniscus Allograft Transplantation: A Cadaveric Analysis.

PURPOSE: To compare meniscal extrusion (ME) following medial meniscus allograft transplantation (MMAT) with and without meniscotibial ligament reconstruction (MTLR). METHODS: Ten cadaveric knees were size-matched with meniscus allografts. MMAT was performed via bridge-in-slot technique. Specimens were mounted in a testing system and ME was assessed via ultrasound anterior, directly over, and posterior to the medial collateral ligament at the joint line under 4 testing conditions: (1) 0° flexion and 0 newtons (N) of axial load, (2) 0° and 1,000 N, (3) 30° and 0 N, and (4) 30° and 1,000 N. For each condition, "mean total extrusion" was calculated by averaging measurements at each position. Next, MTLR was performed using 2 inside-out sutures through the remnant allograft meniscotibial ligament and secured to the tibia using anchors. The testing protocol was repeated. Differences in ME between MMAT alone versus MMAT + MTLR were examined. Within-group differences between the measurement positions, loading states, and flexion angles also were assessed. RESULTS: "Mean total extrusion" was greater following MMAT alone (2.56 ± 1.23 mm) versus MMAT + MTLR (2.14 ± 1.07 mm; P = .005) in the loaded state at 0° flexion. ME directly over the MCL was greater following MMAT alone (3.51 ± 1.00 mm) compared with MMAT + MTLR (2.93 ± 0.79 mm; P = .054). Posteriorly, in the loaded state at 0°, ME was greater following MMAT alone (2.43 ± 1.10 mm) compared with MMAT + MTLR (1.96 ± 0.99 mm; P = .010). In all conditions, ME was greater in the loaded state versus the unloaded state. CONCLUSIONS: Following MMAT, the addition of MTLR significantly reduced overall ME when compared with isolated MMAT during loading at 0° of flexion in a cadaveric model; given the small absolute values of change in extrusion, clinical significance cannot be gleaned from these findings. CLINICAL RELEVANCE: During medial meniscus allograft transplantation, augmentation with meniscotibial ligament reconstruction may limit meniscal extrusion and improve the biomechanical milieu of the knee joint following transplant.

Defining Clinically Significant Outcomes Following Superior Capsular Reconstruction With Acellular Dermal Allograft.

PURPOSE: To define clinically significant outcomes (CSO) thresholds for minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptomatic state (PASS) in patients undergoing superior capsular reconstruction (SCR) with an acellular dermal allograft. We also evaluated patient-specific variables predictive of achieving CSO thresholds. METHODS: The American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Single Assessment Numeric Evaluation (SANE), and subjective Constant-Murley (Constant) scores were collected preoperatively and at the most recent follow up for patients undergoing SCR from 2010 to 2019. A distribution-based approach was used to calculate MCID, and an anchor-based approach was used to calculate SCB and PASS. Logistic regression was used to determine factors associated with CSO achievement. RESULTS: Fifty-eight patients were identified (n = 39 males; n = 19 females) with a mean age of 53.4 ± 14.1 years at surgery and an average follow-up of 23 months. The MCID, SCB, and PASS were 11.2, 18.02, and 68.82 for ASES, 14.5, 23.13, and 69.9 for SANE, and 3.6, 10, and 18 for Constant, respectively. Subscapularis tear, female sex, and workers compensation (WC) status reduced odds of achieving MCID. Reduced odds of achieving Constant SCB were associated with older age, female sex, and WC status, while concomitant distal clavicle excision during SCR and lower preoperative ASES increased odds of achieving ASES SCB. Reduced odds for achieving ASES PASS were associated with female sex and WC status, while reduced odds for achieving SANE PASS were associated with subscapularis tearing preoperatively. CONCLUSION: On the basis of calculated values for MCID, SCB, and PASS, subscapularis tearing, WC status, age, and sex are associated with failure to achieve clinically significant outcomes following SCR. Concomitant distal clavicle excision during SCR and lower preoperative ASES was predictive for achievement of MCID and SCB. By defining the thresholds and variables predictive of achieving CSOs following SCR, surgeons may better counsel patients prior to SCR. LEVEL OF EVIDENCE: Level IV, case series.

Do Outcomes of Meniscal Allograft Transplantation Differ Based on Age and Sex? A Comparative Group Analysis.

PURPOSE: To analyze the effect of patient age, sex, and associated preoperative factors on patient-reported outcome (PRO) measures and graft survival following primary meniscal allograft transplantation (MAT). METHODS: A prospectively collected database was retrospectively reviewed to identify patients who underwent primary MAT with a minimum of 2 years of follow up between 1999 and 2017. Demographic, intraoperative, and postoperative outcome data were collected for each patient. Postoperative outcomes were stratified based on age and sex, and comparative statistical analysis was performed between sexes, both >40 and <40. RESULTS: A total of 238 patients underwent primary MAT during the study period, of which 212 patients (mean age, 28.5 ± 9.0 years; range, 15.01-53.67 years) met the inclusion criteria with a mean follow-up of 5.1 ± 3.4 years (range 2.0-15.9 years). At final follow-up, patients ≥40 and <40 years of age demonstrated statistically significant improvements in nearly all PRO scores (P < .05 for both groups). There were no significant differences between either group for achievement of minimal clinically important difference for International Knee Documentation Committee (P = .48) or Knee Injury and Osteoarthritis Outcome Score symptoms (P = .76). Because of insufficient numbers, a statistically significant difference could not be demonstrated in reoperation rate (≥40: 1.49 ± 1.77 years, <40: 1.87 ± 1.98 years, P = .591), failure rate (≥40: 7/32 [21.9%], <40: 19/180 [10.6%], P = .072), or complication rate (≥40: 2/32 [6.3%], <40: 12/180 [6.7%], P = .930) based on age. Both sexes showed a significant improvement in PROs, whereas female patients were more likely to undergo revision surgery (P = .033), with no significant differences based on time to reoperation, failure, or complication rates. CONCLUSIONS: PROs similarly improved following MAT in both patients aged ≥40 and those <40 at final follow-up with no significant differences in minimal clinically important difference achievement rate, complication rate, reoperation rate, time to reoperation, or failure rate between groups. Female patients may be more likely to undergo revision surgery after MAT. LEVEL OF EVIDENCE: III; therapeutic retrospective comparison study.

Individualized tibial tubercle-trochlear groove distance-to-patellar length ratio (TT-TG/PL) is a more reliable measurement than TT-TG alone for evaluating patellar instability.

PURPOSE: To evaluate the intra/inter-rater and diagnostic reliability of the sagittal plane adjusted patellar instability ratios (PIRs) compared to tibial tubercle-trochlear groove (TT-TG) distance alone while employing a matched case-control analysis for age and sex to minimize a potential confounding effect. METHODS: A retrospective case-control study was performed of all knee MRI studies of patients diagnosed with patellar instability, between 2005 and 2020 at a regional tertiary medical centre. Using a 1:1 case-control matching of sex and age at the time of the diagnosis, one control subject was assigned to each case of patellar instability. Measurements of TT-TG distance, sagittal patellar length (PL), sagittal patellar tendon length (PTL), TT-TG/PL ratio, and TT-TG/PTL ratio were conducted. Two orthopaedic surgery residents and a senior musculoskeletal radiologist were assigned to assess the intra- and inter-rater reliability. Inter-class coefficients were calculated (ICC). The receiver operating characteristic (ROC) curve and area under curve (AUC) for each parameter were compared to evaluate for diagnostic reliability. Odds ratios (OR) and their 95% confidence intervals (CI) were calculated and a multivariable logistic regression model was performed to control for possible confounders. RESULTS: The study included 324 individuals (162 case-control matched pairs). In terms of intra- and inter-rater reliability, TT-TG/PL and TT-TG/PTL ratios showed an excellent correlation within and between readers (TT-TG/PL; intra-rater ICC 0.94 and inter-rater ICC 0.92, TT-TG/PTL; intra-rater ICC 0.91 and inter-rater ICC 0.88). The ROC curve showed a slightly greater AUC of the TT-TG/PL ratio compared to TT-TG distance alone (0.75 vs 0.73, p < 0.001). When applying the pathologic cutoff of TT-TG ≥ 20 mm and TT-TG/PL ≥ 0.5; the calculated odds ratios for the above cutoff were as follows; TT-TG distance alone had an OR of 14 (95% CI 1.8-106.5, p = 0.011) and OR for TT-TG/PL ratio was 23 (95% CI 3.1-170.3, p = 0.002). In the multivariable analysis, while controlling for height and weight, only the association between TT-TG/PL ratio and patellar dislocation remained statistically significant with an adjusted OR of 2.7 (CI 1.3-5.4, p = 0.006), compared to TTTG distance alone (OR = 1.9, n.s.). CONCLUSIONS: Patellar instability ratios are significantly more reliable compared to TT-TG distance alone for the evaluation of patellar instability. Patellar instability ratios present superior diagnostic reliability, sensitivity and specificity, and intra\inter rater reliability. Thus, patellar instability ratios could function as a valuable diagnostic tool for the evaluation of patellar instability. LEVEL OF EVIDENCE: III.

The impact of body mass index on the accuracy of the physical examination of the knee.

PURPOSE: Obesity is a worldwide pandemic; however, no adaptations were made to the physical examination of obese patient's knees. The accuracy of the physical examination is critical for correct assessment and selection of treatment. We aimed to assess whether body mass index (BMI) affects the sensitivity and specificity of common provocative knee tests. METHODS: We studied 210 patients who underwent knee arthroscopy to treat anterior cruciate ligament (ACL) and meniscal pathologies. BMI and the knee's physical examination were documented pre-operatively. Sensitivity, specificity, and accuracy of ACL and meniscal provocative tests in relation to BMI were evaluated using arthroscopy as a gold standard. RESULTS: The Anterior Drawer, Lachman, and Pivot-Shift tests for ACL tears were significantly less accurate and sensitive, yet more specific, in obese patients when compared to normal and overweight patients. The McMurray, Apley Grind, and Thessaly tests for medial meniscus tears showed greater sensitivity, but lower specificity, in patients with increased BMI. Above normal BMIs, independently of age and gender, were significantly associated with higher odds for positive ACL tests. CONCLUSION: Tests for ACL tears are less sensitive in obese patients and alternatives to the classic tests should be considered. Medial meniscus tests tend to be more sensitive and less specific in patients with greater BMIs. Their results should be carefully interpreted due to possible false positives. The physician should take into consideration the impact of patient BMI on the accuracy of their physical examination of the knee to optimize treatment decision-making.

Meniscal extrusion under increasing varus in stress patients with a medial meniscus posterior root-tear.

Posterior root-tear of the medial meniscus and accompanied meniscal extrusion can lead to functional loss of the meniscus. The aim of this study is to assess medial meniscus extrusion at increasing varus forces utilizing magnetic resonance imaging (MRI), in order to evaluate the contribution of the adduction moment of the knee during gait. We prospectively enrolled 19 patients (38 knees). Patients underwent gait analysis testing to calculate adduction moment, followed by an MRI at rest and with increasing varus forces according to the patient's specific adduction moment. Meniscal extrusion and root gap at increasing varus forces were measured and compared. Functional outcomes and their association to meniscal extrusion was analyzed. We found the average meniscal extrusion at rest, 100% and 150% applied varus force for the control group to be 1.7mm, 1.7mm and 1.9mm, respectively; and for the index group average meniscal extrusion was 5.3mm, 6.4mm and 6.8mm, respectively. Meniscal extrusion increase from rest to 100% varus force was significantly higher in the index group (p=0.0002). Further meniscal extrusion and root gap increase from 100% varus force to 150% varus force did not show a statistically significant difference (p=0.39). The association between greater increase of meniscal extrusion with varus force and WOMAC scores was not statistically significant. In conclusion this study defines the contribution of the varus force component of the adduction moment to meniscal extrusion, in patients with a medial meniscus posterior root-tear.

[SEPTIC KNEE - DIAGNOSIS AND TREATMENT].

INTRODUCTION: Acute septic arthritis of the knee joint is an orthopedic emergency, potentially devastating, which can lead to high morbidity and may even be life-threatening. While any synovial joint can be infected, the knee is the most often affected joint and is involved in about 50 % of the cases. The infection is usually caused by a gram-positive bacteria. The diagnosis is made by synovial fluid aspiration, microbiological analysis and hematological investigations of inflammatory measures. Treatment requires emergency irrigation and debridement of the joint, and intravenous antibiotics. Surgical debridement can be performed either arthroscopically or via open arthrotomy. In recent years, arthroscopic treatment demonstrated more favorable outcomes with better functional outcomes, shorter operative time and hospital stays.

Platelet-Rich Plasma Combined With Hyaluronic Acid Improves Pain and Function Compared With Hyaluronic Acid Alone in Knee Osteoarthritis: A Systematic Review and Meta-analysis.

PURPOSE: To evaluate the efficacy of platelet-rich plasma (PRP) combined with hyaluronic acid (HA) injections versus HA injections alone for the management of knee osteoarthritis (OA). METHODS: This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eligible randomized-controlled trials and observational studies directly comparing combined PRP-HA injections with HA injections alone were identified through a search of PubMed, Scopus, and Cochrane Central databases from inception to May 2020. A random effects model meta-analysis was conducted and the I2 statistic was used to assess for heterogeneity. RESULTS: Four studies comprising 377 patients (PRP-HA: 193, HA: 184) with knee OA ranging from I-IV Kellgren-Lawrence grading scale were included. The final follow-up was 12 months in 3 studies and 6 months in 1 study. Patients who received PRP combined with HA had significantly greater improvements compared with those injected with HA alone in terms of visual analog scale scores at 3-month (standardized mean difference [SMD] 1.13; 95% confidence interval [CI] 0.56-1.70; I2 = 56.7%; P < .001), 6-month (SMD 1.08; 95% CI 0.54-1.62; I2 = 67.9%; P < .001), and 12-month (SMD 1.13; 95% CI 0.74-1.52; I2 = 0.0%; P < .001) and 12-month Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical functioning (SMD 0.91; 95% CI 0.65-1.17; I2 = 0.0%; P < .001) and 12-month WOMAC stiffness (SMD 1.09; 95% CI 0.80-1.38; I2 = 0.0%; P < .001) scores. No difference was identified in terms of 12-month WOMAC pain score (SMD 0.36; 95% CI -0.19 to 0.91; I2 = 74.1%; P = .195). CONCLUSIONS: Symptomatic patients with knee OA who were injected with a combination of PRP and HA demonstrated greater improvement in pain and function compared with patients who received HA injections only, as assessed by 3-, 6-, and 12-month visual analog scale scores and 12-month WOMAC physical function and stiffness scores. This study provides encouraging evidence for the use of the combined PRP-HA injections in the management of symptomatic patients with knee OA. LEVEL OF EVIDENCE: III (meta-analysis of randomized and non-randomized comparative trials).

Clinically Significant Outcomes Following the Treatment of Focal Cartilage Defects of the Knee With Microfracture Augmentation Using Cartilage Allograft Extracellular Matrix: A Multicenter Prospective Study.

PURPOSE: To determine the short-term outcomes following microfracture augmented with cartilage allograft extracellular matrix for the treatment of symptomatic focal cartilage defects of the adult knee. METHODS: Forty-eight patients enrolled by 8 surgeons from 8 separate institutions were included in this study. Patients underwent microfracture augmented by cartilage allograft extracellular matrix (BioCartilage; Arthrex, Naples, FL) and were followed at designated time points (3, 6, 12, and 24 months) to assess patient-reported outcomes (PROs), clinically significant outcomes (CSOs), and failure and complication rates. Magnetic resonance imaging (MRI) was offered at 2 years postoperatively regardless of symptomatology, and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score was documented. RESULTS: PRO compliance was 81.3% at 6 months, 72.9% at 12 months, and 47.9% at 2 years. All joint-specific and function-related PROs significantly improved compared to baseline at 3, 6, 12, 18, and 24 months of follow-up (P < .01), apart from Marx activity scale, which demonstrated a significant decline in postoperative scores at 2 years (P = .034). The percentage of patients achieving CSOs (as defined for microfracture) at 2 years was 90% for minimal clinically important difference and 85% for patient acceptable symptomatic state. Patient factors including age, sex, body mass index, symptoms duration, smoking, presence of a meniscal tear, lesion size, and location were not associated with CSO achievement at 2 years. One patient (2.1%) failed treatment 9.5 months postoperatively due to graft delamination and required a reoperation consisting of arthroscopic debridement. One complication (2.1%) consisting of complaints of clicking, grinding, and crepitus 15 months following the index procedure was reported. Two-year postoperative MRI demonstrated a mean 40.5 ± 22.9 MOCART 2.0 score. CONCLUSIONS: In this preliminary study, we found cartilage allograft extracellular matrix to be associated with improvement in functional outcomes, high rates of CSO achievement, and low failure and complication rates at 2-year follow-up. LEVEL OF EVIDENCE: Level III, prospective multicenter cohort study.

Osteochondral Allograft Transplantation of the Knee in Adolescent Patients and the Effect of Physeal Closure.

PURPOSE: The primary aim was to compare osteochondral allograft (OCA) transplantation outcomes between adolescent patients aged 16 years or younger and those older than 16 years. A secondary aim was to analyze the association between physeal closure status and outcomes. METHODS: Consecutive patients aged 18 years or younger who underwent OCA transplantation with a minimum 2-year follow-up were identified from a prospectively collected database. Patients were divided into 2 groups: those aged 16 years or younger (group 1) and those aged 17 to 18 years (group 2). Outcomes included patient-reported outcomes (PROs), complications, reoperations, and cartilage revision surgery. Outcomes were compared between groups, and physeal status was analyzed as a prognostic indicator. RESULTS: A total of 36 patients met the inclusion criteria: 18 in group 1 and 18 in group 2. There were no significant differences between the groups in terms of demographic characteristics, prior surgical procedures, and surgical details, including concomitant procedures. The mean overall follow-up period was 4.6 ± 2.5 years (range, 2-10.3 years), with no significant difference between the groups (P = .21). There were 10 reoperations (28.8%), 4 in group 1 and 6 in group 2 (P = .47). The overall time to reoperation was 2.8 years and did not significantly differ between groups (P = .75). The failure rate was 5.6%, with 1 patient in each group undergoing either graft debridement or revision OCA transplantation. All PROs were significantly improved postoperatively (P < .05), except for the Western Ontario and McMaster Universities Arthritis Index stiffness score (P = .28) and the Short Form 12 mental score (P = .19). There were no significant between-group differences in terms of PROs. Patients with closed physes had a significantly greater increase in most PROs compared with patients with open physes (P < .05). CONCLUSIONS: OCA transplantation in adolescents results in significant PRO score improvement and a low failure rate, albeit reoperations are not uncommon. Patients with closed physes show greater PRO score improvement than those with open physes. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Patient Factors Associated With Clinical Failure Following Arthroscopic Superior Capsular Reconstruction.

PURPOSE: To identify demographic, clinical, and radiographic factors associated with failure after superior capsular reconstruction (SCR). METHODS: Prospectively collected data were analyzed from patients who underwent SCR using a decellularized dermal allograft for an irreparable rotator cuff tear. Demographic characteristics, radiographic findings, concomitant procedures, and patient-reported outcomes (PROs) were recorded. Failure was defined by ≥1 of the following criteria: (1) conversion to reverse total shoulder arthroplasty (RTSA), (2) a decrease in 1-year postoperative shoulder-specific PROs compared with preoperative scores, or (3) patient reports at final follow-up that the shoulder was in a worse condition than before surgery. Preoperative variables were compared between patients meeting the criteria for clinical failure and those who did not. RESULTS: Fifty-four patients (mean age 56.3 ± 5.8 years, range 45 to 70) who underwent SCR, with minimum 1-year follow-up, were included in the analysis. Mean follow-up after surgery was 24 months (range 12 to 53). Eleven patients (20.4%) met criteria for clinical failure. Of the 11, 8 reported decreased American Shoulder and Elbow Surgeons (ASES) or Constant scores or indicated that the operative shoulder was in a worse condition than before surgery. Three patients underwent RTSA in the 6 to 12 months after SCR. Female sex and the presence of a subscapularis tear were associated with failure (P = .023 and P = .029, respectively). A trend toward greater body mass index (BMI), lower preoperative forward flexion, and lower preoperative acromiohumeral distance (AHD) was found in patients with clinical failure (P = .075, P = .088, and P = .081, respectively). No other variable included in the analysis was significantly associated with failure. CONCLUSION: The proportions of female patients and those with subscapularis tear were greater among patients with clinical failure after SCR. Greater BMI, lower preoperative forward flexion, and lower preoperative AHD trended toward association with clinical failure of SCR. LEVEL OF EVIDENCE: 4, case series.