Management of Meniscus Pathology with Concomitant Anterior Cruciate Ligament Injury.

PURPOSE OF REVIEW: The purpose of this review is to summarize current clinical knowledge on the prevalence and types of meniscus pathology seen with concomitant anterior cruciate ligament (ACL) injury, as well as surgical techniques, clinical outcomes, and rehabilitation following operative management of these pathologies. RECENT FINDINGS: Meniscus pathology with concomitant ACL injury is relatively common, with reports of meniscus pathology identified in 21-64% of operative ACL injuries. These concomitant injuries have been associated with increased age and body mass index. Lateral meniscus pathology is more common in acute ACL injury, while medial meniscus pathology is more typical in chronic ACL deficiency. Meniscus tear patterns associated with concomitant ACL injury include meniscus root tears, lateral meniscus oblique radial tears of the posterior horn (14%), and ramp lesions of the medial meniscus (8-24%). These meniscal pathologies with concomitant ACL injury are associated with increased rotational laxity and meniscal extrusion. There is a paucity of comparative studies to determine the optimal meniscus repair technique, as well as rehabilitation protocol, depending on specific tear pattern, location, and ACL reconstruction technique. There has been a substantial increase in recent publications demonstrating the importance of meniscus repair at the time of ACL repair or reconstruction to restore knee biomechanics and reduce the risk of progressive osteoarthritic degeneration. Through these studies, there has been a growing understanding of the meniscus tear patterns commonly identified or nearly missed during ACL reconstruction. Surgical management of meniscal pathology with concomitant ACL injury implements the same principles as utilized in the setting of isolated meniscus repair alone: anatomic reduction, biologic preparation and augmentation, and circumferential compression. Advances in repair techniques have demonstrated promising clinical outcomes, and the ability to restore and preserve the meniscus in pathologies previously deemed irreparable. Further research to determine the optimal surgical technique for specific tear patterns, as well as rehabilitation protocols for meniscus pathology with concomitant ACL injury, is warranted.

High incidence of medial meniscus root/radial tears and extrusion in 253 patients with subchondral insufficiency fractures of the knee.

PURPOSE: The demographic and radiological risk factors of subchondral insufficiency fractures of the knee (SIFK) continue to be a subject of debate. The purpose of this study was to associate patient-specific factors with SIFK in a large cohort of patients. METHODS: Inclusion criteria consisted of patients with SIFK as verified on magnetic resonance imaging (MRI). All radiographs and MRIs were reviewed to assess characteristics such as meniscus tear presence and type, subchondral oedema presence and location, location of SIFK, mechanical limb alignment, osteoarthritis as assessed by Kellgren-Lawrence grade and ligamentous injury. A total of 253 patients (253 knees) were included, with 171 being female. The average body mass index (BMI) was 32.1 ± 7.0 kg/m2. RESULTS: SIFK was more common in patients with medial meniscus tears (77.1%, 195/253) rather than tears of the lateral meniscus (14.6%, 37/253) (p < 0.001). Medial meniscus root and radial tears of the posterior horn were present in 71.1% (180/253) of patients. Ninety-one percent (164/180) of medial meniscus posterior root and radial tears had an extrusion ≥3.0 mm. Eighty-one percent (119/147) of patients with SIFK on the medial femoral condyle and 86.8% (105/121) of patients with SIFK on the medial tibial plateau had a medial meniscus tear. Varus knees had a significantly increased rate of SIFK on the medial femoral condyle in comparison to valgus knees (p = 0.016). CONCLUSION: In this large cohort of patients with SIFK, there was a high association with medial meniscus root and radial tears of the posterior horn, meniscus extrusion ≥3.0 mm as well as higher age, female gender and higher BMI. Additionally, there was a particularly strong association of medial compartment SIFK with medial meniscus tears. As SIFK is frequently undiagnosed, identifying patient-specific demographic and radiological risk factors will help achieve a prompt diagnosis. LEVEL OF EVIDENCE: Level IV.

Influence of Concomitant Meniscal Allograft Transplantation on Midterm Outcomes After Osteochondral Allograft Transplantation: A Comparative Matched-Pair Analysis.

BACKGROUND: Osteochondral allograft transplantation (OCAT) is an accepted knee joint-preserving treatment strategy for focal osteochondral lesions that is often conducted in combination with meniscal allograft transplantation (MAT). Despite its frequent and simultaneous utilization, there remains a lack in the literature reporting on outcomes and failure rates after concomitant procedures. PURPOSE: To determine (1) the midterm clinical success rate after OCAT+MAT in comparison with a matched-pair cohort undergoing isolated OCAT, (2) whether patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A single-center matched-pair cohort study was conducted investigating outcomes in patients who underwent OCAT of the medial or lateral femoral condyle with and without MAT between 2004 and 2020. Patients were matched 1:1 by age (±5 years), sex (male or female), body mass index (±5), and grouped Kellgren and Lawrence grade (grades 0-1 or 2-4). The minimum follow-up time was 2 years. Radiographic variables (International Cartilage Regeneration & Joint Preservation Society [ICRS] grade and Kellgren and Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery for graft failure or conversion to total knee arthroplasty. Patient-reported, clinical, and radiographic outcomes were compared between groups. RESULTS: In total, 66 patients (33 treated with isolated OCAT, 33 treated with OCAT+MAT; 57.6% male) with a mean age of 26.3 years (range, 18-62 years) were followed for a mean of 5.6 years (minimum, 2 years; range, 24-218 months). The 2 cohorts showed no difference in Kellgren and Lawrence grade postoperatively (P = .59). There was a significantly higher ICRS grade detected at follow-up in the OCAT+MAT group (2.81 ± 1.10) compared with the OCAT group (2.04 ± 0.96) (P < .05). There were no statistically significant differences between the groups regarding reoperation rate (OCAT: n = 6; OCAT+MAT: n = 13; P = .116), time to reoperation (OCAT: 46.67 ± 47.27 months vs OCAT+MAT: 28.08 ± 30.16 months; P = .061), and failure rate (OCAT: n = 4 [12.1%] vs OCAT+MAT: n = 5 [15.2%]; P = .66). In the OCAT+MAT group, an increase of tibial slope by 1° conferred a 1.65-fold increase in the hazard for failure over decreased slope (hazard ratio, 1.65; 95% CI, 1.10-2.50; P < .05). The overall survival rate was 86% at a mean follow-up of 5.6 years. Patient-reported outcome scores were significantly improved at the final follow-up compared with preoperative status. No significant differences were seen between groups with respect to subjective IKDC, Lysholm, Tegner, and KOOS results, except for the KOOS Symptoms subscale score, which was significantly higher in the OCAT+MAT group than in the OCAT group (mean difference, 14.6; P < .05) and did exceed the minimal clinically important difference threshold of 10.7. CONCLUSION: Midterm results after isolated OCAT and OCAT+MAT show high rates of healing and sustainable subjective improvement of knee function and quality of life. However, it should be noted that the difference in reoperation rate and time to reoperation between the groups is arguably clinically important and that lack of statistical significance may be because of low power. These results imply that isolated OCAT is an efficient joint-preserving treatment that can be combined with MAT in well-selected patients with meniscal insufficiency without negative influence on global clinical outcomes.

Minimum 10-Year Outcomes of Matrix-Induced Autologous Chondrocyte Implantation in the Knee: A Systematic Review.

BACKGROUND: Matrix-induced autologous chondrocyte implantation (MACI) is an established cell-based therapy for the treatment of chondral defects of the knee. As long-term outcomes are now being reported in the literature, it is important to systematically review available evidence to better inform clinical practice. PURPOSE: To report (1) subjective patient-reported outcomes (PROs) and (2) the rate of graft failure, reoperation, and progression to total knee arthroplasty (TKA) after undergoing MACI of the knee at a minimum 10-year follow-up. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A comprehensive search of Ovid MEDLINE and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; Ovid Embase; Ovid Cochrane Central Register of Controlled Trials; Ovid Cochrane Database of Systematic Reviews; and Scopus from 2008 to September 15, 2022, was conducted in the English language. Study eligibility criteria included (1) full-text articles in the English language, (2) patients undergoing a MACI within the knee, (3) clinical outcomes reported, and (4) a minimum 10-year follow-up. RESULTS: In total, 168 patients (99 male, 69 female; mean age, 37 years [range, 15-63 years]; mean body mass index, 26.2 [range, 18.6-39.4]) representing 188 treated chondral defects at a minimum 10-year follow-up after MACI were included in this review. Significant and durable long-term improvements were observed across multiple PRO measures. Follow-up magnetic resonance imaging (MRI), when performed, also demonstrated satisfactory defect fill and an intact graft in the majority of patients. The all-cause reoperation rate was 9.0%, with an overall 7.4% rate of progression to TKA at 10 to 17 years of follow-up. CONCLUSION: At a minimum 10-year follow-up, patients undergoing MACI for knee chondral defects demonstrated significant and durable improvements in PROs, satisfactory defect fill on MRI-based assessment, and low rates of reoperation and TKA. These data support the use of MACI as a long-term treatment of focal cartilage defects of the knee.

Root Repair Has Superior Radiological and Clinical Outcomes Than Partial Meniscectomy and Nonoperative Treatment in the Management of Meniscus Root Tears: A Systematic Review.

PURPOSE: To compile and analyze structural and clinical outcomes after meniscus root tear treatment as currently described in the literature. METHODS: A review was conducted to identify studies published since 2011 on efficacy of repair, meniscectomy, and nonoperative management in the treatment of meniscus root tears. Patient cohorts were grouped into treatment categories, with medial and lateral root tears analyzed separately; data were collected on patient demographics, structural outcomes including joint space width, degree of medial meniscal extrusion, progression to total knee arthroplasty, and patient-reported outcome measures. Risk of bias was assessed using the MINORS (methodological index for non-randomized studies) criteria. Heterogeneity was measured using the I-statistic, and outcomes were summarized using forest plots without pooled means. RESULTS: The 56 included studies comprised a total of 3,191 patients. Mean age among the included studies ranged from 24.6 to 65.6 years, whereas mean follow-up ranged from 12 to 125.9 months. Heterogeneity analysis identified significant differences between studies. Change in joint space width ranged from -2.4 to -0.6 mm (i.e., decreased space) after meniscectomy (n = 186) and -0.9 to -0.1 mm after root repair (n = 209); change in medial meniscal extrusion ranged from -0.6 to 6.5 mm after root repair (n = 521) and 0.2 to 4.2 mm after meniscectomy (n = 66); and event rate for total knee arthroplasty ranged from 0.00 to 0.22 after root repair (n = 205), 0.35 to 0.60 after meniscectomy (n = 53), and 0.27 to 0.35 after nonoperative treatment (n = 93). Root repair produced the greatest numerical increase in International Knee Documentation Committee and Lysholm scores of the 3 treatment arms. In addition, root repair improvements in Knee Injury and Osteoarthritis Outcome Score Pain (range: 22-32), Sports and Recreational Activities (range: 23-36), Quality of Life (range: 22-42), and Symptoms subscales (range: 10-19), in studies with low risk of bias. CONCLUSIONS: The literature reporting on the treatment of meniscus root tears is heterogenous and largely limited to Level III and IV studies. Current evidence suggests root repair may be the most effective treatment strategy in lessening joint space narrowing of the knee and producing improvements in patient-reported outcomes. LEVEL OF EVIDENCE: Level IV, systematic review of Level II-IV studies.

Cellular Enhancement of Frozen Meniscus Allograft Combining Native Meniscus and Mesenchymal Stromal Cell Injections.

OBJECTIVE: This proof-of-concept study investigated an improved cell-based injection therapy combining mesenchymal stem cells (MSCs) and meniscus cells (MCs) to support superior meniscus allograft repopulation and early revival compared to injecting MSCs alone. DESIGN: In this controlled laboratory study, frozen meniscus allograft samples were injected vertically with a cell suspension containing different ratios of MSCs and MCs or control (lactated ringers) and cultured for 28 days. Samples were analyzed weekly for cell viability, migration, and metabolism using histological and biochemical assays. Tissue medium was analyzed for matrix metalloproteinase (MMP) expression using zymography. RESULTS: Cellular repopulation of frozen allografts injected with different cell suspensions was validated by immunohistochemistry. Significant higher DNA content was evidenced in grafts treated with suspensions of MCs or MC:MSC (1:4 ratio). Cell metabolic activity was significantly different between all treated groups and control group after 1 week. Allografts injected with MCs showed significantly more cell proliferation than injections with MSCs. MMP2 activity was detected in medium of all grafts cellularized with MCs with or without MSCs. Scanning electron microscopy (SEM) analysis showed resolution of the needle puncture, but not in the control group. Cell labeling of MCs upon injection of mixed MC:MSC suspensions revealed a gradual increase in the cell ratio. CONCLUSIONS: The findings of this study establish that injection of MCs with or without MSCs enhances the cellularity of meniscus allograft to support early graft revival and remodeling.

Osteochondritis Dissecans of the Knee Associated With Mechanical Overload.

BACKGROUND: Osteochondritis dissecans (OCD) of the knee is a rare but potentially incapacitating disorder in which subchondral bone detaches, leading to an osteochondral fragment that can become unstable and progress into a loose body. The exact cause is unknown, although several biological and mechanical factors have been described. PURPOSE: To provide insight into epidemiological data of a large cohort of patients affected by OCD of the knee and to identify potential factors contributing to the cause of this disorder. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 236 patients (259 knees) affected by OCD were included in our Knee Registry (2005-2022) and retrospectively analyzed. Patient characteristics were extracted from the medical records. Location and International Cartilage Regeneration & Joint Preservation Society grade (1-4) of OCD were assessed using magnetic resonance imaging. If available, a full-leg standing radiograph was used to assess alignment. Additionally, a statistical scoring system for instability risk was created. RESULTS: A total of 263 OCD lesions were identified in 259 knees, 66.2% on the medial femoral condyle (MFC), 26.6% on the lateral femoral condyle (LFC), 3.8% on the trochlea, 2.7% on the patella, and 0.8% on the lateral tibia plateau. Male patients made up 57.6% of the sample, which had a mean age of 21.8 years. A very high percentage of patients (77.1%; n = 182) practiced sports, of whom 67.6% (n = 123) were engaged in high-impact sports. The location of the OCD lesions and the leg alignment (n = 110) were significantly correlated: MFC lesions were associated with more varus than valgus alignment (47.5% vs 11.3%) and patients with LFC lesions had more valgus than varus alignment (46.7% vs 20.0%; P = .002). Based on age, smoking, sports activity, and preceding trauma, a multivariable scoring system (0-11 points) was created. An increased risk of lesion instability was associated with an increased score: 29.0% at 0 points and 97.0% at 11 points. CONCLUSION: This study provides detailed epidemiological data for 236 patients affected by OCD of the knee. Older age, smoking, inactivity, and preceding trauma were predictive for instability of OCD lesions. There was an association between OCD of the MFC and varus malalignment and between OCD of the LFC and valgus malalignment. This finding, in combination with the high percentage of patients practicing high-impact sports, suggests an important role for mechanical overload in the pathogenesis of OCD.

Survivorship of 157 Arthroscopic Meniscal Allograft Transplants Using Bone Fixation at a Mean of 7 Years and Prognostic Factors Analysis.

BACKGROUND: Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration & Joint Preservation Society (ICRS) grade. PURPOSE: To determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (ICRS grade and Kellgren-Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs) (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale [VAS] score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty. Anatomic failure was considered a tear covering >20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed using the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure. RESULTS: A total of 157 knees met inclusion criteria. After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as having experienced anatomic failure, and 13 (8.3%) patients experienced subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (hazard ratio [HR], 4.55; 95% CI, 1.46-14.17; P = .009) and anatomic (HR, 3.05; 95% CI, 1.34-6.92; P = .008) failure. Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR, 3.41; 95% CI, 1.05-11.01; P = .04) and anatomic (HR, 3.04; 95% CI, 1.31-7.11; P = .01) failure. High-grade cartilage damage preoperatively (HR, 10.67; 95% CI, 1.037-109.768; P = .046), patient age >25 years (HR, 5.44; 95% CI, 0.120-246.070; P = .384), and a body mass index >30 (HR, 2.24; 95% CI, 0.748-6.705; P = .149) were associated with subjective failure. PROMs including KOOS and IKDC were significantly improved at final follow-up compared with preoperative scores across all measurements (P < .005). CONCLUSION: MAT showed good to excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent OCA transplantation are at a higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest that MAT has a lasting beneficial effect both in isolation and in complex cases with ≥1 concurrent procedures.

Comparison of Failure Rates at Long-term Follow-up Between MPFL Repair and Reconstruction for Recurrent Lateral Patellar Instability.

Background: The medial patellofemoral ligament (MPFL) is the primary soft tissue restraint to lateral patellar translation and is often disrupted by lateral patellar dislocation. Surgical management for recurrent patellar instability focuses on restoring the MPFL function with repair or reconstruction techniques. Recent studies have favored reconstruction over repair; however, long-term comparative studies are limited. Purpose: To compare long-term clinical outcomes, complications, and recurrence rates of isolated MPFL reconstruction and MPFL repair for recurrent lateral patellar instability. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 55 patients (n = 58 knees) with recurrent lateral patellar instability were treated between 2005 and 2012 with either MPFL repair or MPFL reconstruction. The exclusion criteria were previous or concomitant tibial tubercle osteotomy or trochleoplasty and follow-up of <8 years. Pre- and postoperative descriptive, surgical, imaging, and clinical data were recorded for each patient. Results: MPFL repair was performed on 26 patients (n = 29 knees; 14 women, 15 men), with a mean age of 18.4 years. MPFL reconstruction was performed on 29 patients (n = 29 knees; 18 women, 11 men), with a mean age of 18.2 years. At a mean follow-up of 12 years (range, 8.3-18.9 years), the reconstruction group had a significantly lower rate of recurrent dislocation compared with the repair group (14% vs 41%; P = .019). There were no differences in the number of preoperative dislocations or tibial tubercle-trochlear groove distance. The reconstruction group had significantly more time from initial injury to surgery compared with the repair group (median, 1460 days vs 627 days; P = .007). There were no differences in postoperative Tegner, Lysholm, or Kujala scores at the final follow-up. In addition, no statistically significant differences were detected in return to sport (RTS) rates (repair [81%] vs reconstruction [75%]; P = .610) or reoperation rates for recurrent instability (repair [21%] vs reconstruction [7%]; P = .13). Conclusion: MPFL repair resulted in a nearly 3-fold higher rate of recurrent patellar dislocation (41% vs 14%) at the long-term follow-up compared with MPFL reconstruction. Given this disparate rate, the authors recommend MPFL reconstruction over repair because of the lower failure rate and similar, if not superior, clinical outcomes and RTS.

Gelatin-tyramine addition and low hydrogel density improves cell attachment, migration, and metabolic activity in vitro and tissue response in vivo in enzymatically crosslinkable dextran-hyaluronic acid hydrogels.

Hydrogels are receiving increasing attention for their use in 3D cell culture, tissue engineering, and bioprinting applications. Each application places specific mechanical and biological demands on these hydrogels. We developed a hydrogel toolbox based on enzymatically crosslinkable polysaccharides via tyramine (TA) moieties, allowing for rapid and tunable crosslinking with well-defined stiffness and high cell viability. Including gelatin modified with TA moieties (Gel-TA) improved the hydrogels' biological properties; 3 T3 fibroblasts and HUVECs attached to and proliferated on the enriched hydrogels at minute Gel-TA concentrations, in contrast to bare or unmodified gelatin-enriched hydrogels. Moreover, we were able to switch HUVECs from a quiescent to a migratory phenotype simply by altering the ligand concentration, demonstrating the potential to easily control cell fate. In encapsulation studies, Gel-TA significantly improved the metabolic activity of 3 T3 fibroblasts in soft hydrogels. Furthermore, we showed rapid migration and network formation in Gel-TA enriched hydrogels in contrast to a non-migratory behavior in non-enriched polysaccharide hydrogels. Finally, low hydrogel density significantly improves tissue response in vivo with large infiltration and low fibrotic reaction. Further development by adding ECM proteins, peptides, and growth factor adhesion sites will lead to a toolbox for hydrogels tailored toward their desired application.

Differences in Trampoline-Related Knee Injuries Between Children and Adults: A Cross-Sectional Study.

Background: Little is known about the specific risk of knee injuries due to trampoline accidents in adults compared with children. Purpose: To investigate the differences in trampoline-related knee injuries between children and adults and identify risk factors and protective strategies to reduce injury incidence. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Data on 229 consecutive patients treated for trampoline-related knee injuries in a single institution were prospectively collected, analyzed, and included. Risk factors, injury patterns, and clinical treatments were compared between skeletally immature and skeletally mature patients. Logistic regression was used to determine the odds ratios for specific risk factors for trampoline-related injuries-including body mass index (BMI), trauma mechanism, patient age, and accident location. Results: A total of 229 patients met the inclusion criteria; 118 (52%) patients (women, 54.2%; mean age, 8.5 ± 4.1 years) were skeletally immature at the time of injury, and 111 (48%) patients (women, 72%; mean age, 31.9 ± 13.1 years) had closed physes on initial presentation and were classified as skeletally mature. A total of 63 patients (28%) required surgical treatment for their knee injury. Overall, 50 anterior cruciate ligament (ACL) tears, 46 fractures, 39 meniscal tears, 31 ligamentous tears other than ACL, 22 patellar dislocations, and 38 soft tissue injuries, such as lacerations, were recorded. Skeletally mature patients had 7.8 times higher odds (95% CI, 1.6-46.8; P < .05) and 19.1 increased odds (95% CI, 5.5-74.9; P < .05) of an ACL tear or another ligamentous tear, respectively, compared with skeletally immature patients. Patients who described instability and giving way of the knee as relevant trauma mechanisms had odds of 3.11 (95% CI, 0.9-14.8; P < .05) of an ACL tear compared with other trauma mechanisms. Meniscal tears were observed more frequently in the skeletally mature cohort (P < .05). An elevated BMI was associated with a significantly higher relative risk of an ACL tear, a ligamentous tear other than the ACL, and an injury requiring surgery. A third of surgically treated patients were subject to a delayed diagnosis. Conclusion: Adults had a significantly increased risk of ligamentous and meniscal tears and required operative intervention more often than skeletally immature individuals. Elevated BMI, age, and instability events in terms of trauma mechanism conveyed an increased risk of structural damage to the knee.

Effect of Autologous Conditioned Plasma Injections in Patients With Knee Osteoarthritis.

Background: Autologous conditioned plasma (ACP) is a commercially available platelet concentrate with promising results from clinical trials. Purpose: To evaluate the clinical outcome after 3 consecutive injections of ACP in patients with knee osteoarthritis (OA) and study the influence of ACP composition and different patient factors as predictors of treatment effect. Study Design: Case series; Level of evidence, 4. Methods: This prospective case series included 260 patients (307 knees) who received ACP treatment for knee OA. The mean patient age was 51 ± 10 years. Improvement up to 12 months' follow-up was measured using the Knee injury and Osteoarthritis Outcome Score (KOOS). ACP composition was analyzed in 100 patients. The predictive value of age, sex, history of knee trauma, Kellgren-Lawrence OA grade, body mass index, and ACP composition was evaluated using generalized estimating equations. Results: The mean overall KOOS improved from 38 ± 14 at baseline to 45 ± 18 at 3 months, 45 ± 18 at 6 months, and 43 ± 18 at 12 months (all P < .05); 40% of patients achieved an improvement above the minimal clinically important difference (MCID) of 8 after 6 months and 33% after 12 months. The variation in ACP composition did not correlate with KOOS (P > .05). Older age led to a greater clinical benefit (ß = 0.27; P = .05), whereas bilateral treatment predicted worse outcomes (ß = -5.6; P < .05). Conclusion: The improvement in KOOS after treatment with ACP did not reach the MCID in most study patients. Older age was a predictor for better outcomes. The composition of ACP varied between patients but did not predict outcomes within the evaluated range. The study findings show the limited benefit of ACP treatment for knee OA and call for caution with routine use in clinical practice.

Meniscal Extrusion: Diagnosis, Etiology, and Treatment Options.

PURPOSE OF REVIEW: The concept of meniscal extrusion has recently been recognized as a hallmark of meniscus dysfunction. This review examines contemporary literature regarding the pathophysiology, classification, diagnosis, treatment, and future directions for investigation regarding meniscus extrusion. RECENT FINDINGS: Meniscus extrusion, defined as >3 mm of radial displacement of the meniscus, leads to altered knee biomechanics and accelerated knee joint degeneration. Meniscus extrusion has been associated with degenerative joint disease, posterior root and radial meniscal tears, and acute trauma. Meniscus centralization and meniscotibial ligament repair have been proposed as techniques to address meniscal extrusion with promising biomechanical, animal model, and early clinical reports. Further studies on the epidemiology of meniscus extrusion and associated long-term nonoperative outcomes will help to elucidate its role in meniscus dysfunction and resultant arthritic development. Understanding and appreciation for the anatomic attachments of the meniscus will help to inform future repair techniques. Long-term reporting on the clinical outcomes of meniscus centralization techniques will yield insights into the clinical significance of meniscus extrusion correction.

Predicting the Risk of Posttraumatic Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Machine Learning Time-to-Event Analysis.

BACKGROUND: There is a significant long-term risk of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR). Elucidating the risk factors and successfully identifying at-risk patients is challenging. PURPOSE/HYPOTHESIS: The purpose of this study was to produce machine learning survival models that can identify (1) patients at risk of symptomatic PTOA and (2) patients who are at risk of undergoing total knee arthroplasty (TKA) after ACLR. It was hypothesized that these models would outperform traditional Kaplan-Meier estimators. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A geographic database was used to identify patients undergoing ACLR between 1990 and 2016 with a minimum 7.5-year follow-up. Models were used to analyze various factors to predict the rate and time to (1) symptomatic osteoarthritis and (2) TKA using random survival forest (RSF) algorithms. Performance was measured using out-of-bag (OOB) c-statistic, calibration, and Brier score. The predictive performances of the RSF models were compared with Kaplan-Meier estimators. Model interpretability was enhanced utilizing global variable importance and partial dependence curves. RESULTS: A total of 974 patients with ACLR and a minimum follow-up of 7.5 years were included; among these, 215 (22.1%) developed symptomatic osteoarthritis, and 25 (2.6%) progressed to TKA. The RSF algorithms achieved acceptable good to excellent predictive performance for symptomatic arthritis (OOB c-statistic, 0.75; Brier score, 0.128) and progression to TKA (OOB c-statistic, 0.89; Brier score, 0.026), respectively. Significant predictors of symptomatic PTOA included increased pain scores, older age, increased body mass index, increased time to ACLR, total number of arthroscopic surgeries before the diagnosis of arthritis, positive pivot-shift test after reconstruction, concomitant chondral injury, secondary meniscal tear, early (<250 days) or delayed (>500 days) return to sports or activity, and use of allograft. Significant predictors for TKA included older age, increased pain scores, total number of arthroscopic surgeries, high-demand activity/occupation, hypermobility, higher body mass index, systemic inflammatory disease, increased time to surgery, early (<250 days) or delayed (>500 days) return to sports or activity, and midsubstance tears. The Brier score over time revealed that RSF models outperformed traditional Kaplan-Meier estimators. CONCLUSION: Machine learning survival models were used to reliably identify patients at risk of developing symptomatic PTOA, and these models consistently outperformed traditional Kaplan-Meier estimators. Strong predictors for the development of PTOA after ACLR included increased pain scores at injury and postoperative visit, older age at injury, total number of arthroscopic procedures, positive postoperative pivot-shift test, and secondary meniscal tear.

Medial Patellofemoral Ligament Reconstruction Using Allografts in Skeletally Immature Patients.

BACKGROUND: Patellar instability has the highest incidence in adolescents aged between 14 and 18 years. The unique relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis in skeletally immature patients warrants precisely positioned MPFL graft insertion. A paucity of data are available evaluating the results of MPFL reconstruction using allograft tendon before skeletal maturity. PURPOSES: (1) To assess the results of MPFL reconstruction using allograft tendon in skeletally immature patients by analyzing redislocation and reoperation rates, radiological outcomes, and patient-reported outcomes and (2) to determine whether epidemiological, intraoperative, or radiographic factors influence recurrent instability and clinical outcomes. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Prospectively collected data were retrospectively analyzed for 69 skeletally immature patients who experienced a first-time or recurrent lateral patellar dislocation and were treated with anatomic MPFL reconstruction. Inclusion criteria were MPFL reconstruction using allograft and the availability of preoperative magnetic resonance imaging scans in the presence of open or partially open physes. Patients with <2 years of follow-up and patients with previous surgeries on the same knee were excluded from the study. Preoperative radiographic imaging was reviewed and analyzed. Trochlear dysplasia, tibial tubercle-trochlear groove distance, and patellar height were evaluated. Descriptive data, concomitant injuries, surgical procedure details, complications, and postoperative history were assessed via review of medical records and patient charts. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively, including Kujala score, Lysholm score, and Tegner activity score. Return-to-sports rate was assessed. The influence of epidemiological, intraoperative, and radiographic parameters on the redislocation rates and clinical outcomes was assessed using a multiple linear regression model. RESULTS: A total of 79 physeal-sparing MPFL reconstructions (69 patients) met the inclusion criteria. The mean age of the patient cohort was 14.7 ± 1.8 years (range, 8.5-16.9 years). Within the mean follow-up time of 37.9 ± 12.1 months (range, 24-85 months after surgery, there were 12 patients with clinical failures resulting in reoperation. Eleven patients experienced a redislocation of the patella, and 1 patient sustained a transverse noncontact patellar fracture 6 months after index surgery that required operative fixation. No injuries to the distal femoral physes were clinically observed. At the final follow-up, patients had a mean Lysholm score (1-100) of 96.5 ± 6.7, a mean Kujala score (1-100) of 96.5 ± 7.4, and a mean Tegner Activity Scale score (1-10) of 4.9 ± 1.3. Patellar height and trochlear dysplasia did not influence redislocation or clinical scores. In total, 57 of the 63 patients (90.5%) who were engaged in sports before injury returned to the same or higher level of competition. In a subgroup analysis of patients who underwent isolated MPFL reconstruction (n = 44) without concomitant procedures, 9 patients (20.5%) experienced failure and had a redislocation. A univariate analysis of hazards for failure based on patient-specific variables was carried out. A body mass index ≥30 conveyed a hazard ratio of 2.51 (95% CI, 0.63-10.1; P = .19), and the tibial tubercle-trochlear groove distance by increments of 1 mm was associated with a hazard ratio of 2.02 (95% CI, 0.51-8.11; P = .32). CONCLUSION: Physeal-sparing anatomic reconstruction of the MPFL using an allograft tendon in skeletally immature patients was a safe and effective treatment for patellar instability, regardless of patellar height and trochlear dysplasia. Failure rates decreased when the MPFL reconstruction was performed concomitantly with a tibial tubercle osteotomy.

Internal Fixation of Unstable Osteochondritis Dissecans of the Knee: Long-term Outcomes in Skeletally Immature and Mature Patients.

BACKGROUND: Osteochondritis dissecans (OCD) is a disorder originating in the subchondral bone, leading to focal lesions with risk of fragmentation and secondary damage of the articular cartilage. It remains controversial if surgical treatment of such lesions is equally successful in skeletally immature and mature patients. PURPOSE: To determine (1) the long-term clinical success rate after internal fixation of unstable OCD in skeletally immature and mature patients based on physeal status, (2) if patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A multicenter retrospective cohort study was conducted investigating skeletally immature and mature patients treated for unstable OCD lesions of the knee between 2000 and 2015. The healing rate was assessed by radiological imaging and clinical follow-up. Failure was defined as any definitive reoperation for the initially treated OCD lesion. RESULTS: A total of 81 patients met inclusion criteria, including 25 skeletally immature patients and 56 patients with closed physes at the time of surgery. After a mean follow-up time of 11.3 ± 4 years, 58 (71.6%) patients had healed lesions, whereas the lesions failed to heal in 23 (28.4%) patients. No significant difference in risk of failure was observed based on physeal maturation status (hazard ratio, 0.78; 95% CI, 0.33-1.84; P = .56). Lateral versus medial condylar lesion location conferred an increased risk of failure (P < .05) for both skeletally immature and mature patients. Multivariate analysis of skeletal maturity status showed that a lateral femoral condylar location was an independent risk factor for failure (hazard ratio, 0.22; 95% CI, 0.1-0.5; P < .05). The mean patient-reported outcome scores (International Knee Documentation Committee [IKDC] score and Knee injury and Osteoarthritis Outcome Score [KOOS]) increased significantly after surgery and remained high at the final follow-up (P < .05). The final scores (mean ± SD) at a mean follow-up of 135.8 months (range, 80-249 months) were IKDC, 86.6 ± 16.7; KOOS Pain, 88.7 ± 18.1; KOOS Symptoms, 89.3 ± 12.6; KOOS Activities of Daily Living, 89.3 ± 21.6; KOOS Sport and Recreation, 79.8 ± 26.3; and KOOS Quality of Life, 76.7 ± 26.3. CONCLUSION: The long-term results after internal fixation of OCD fragments show high rates of healing and sustainable subjective improvement of knee function and quality of life. A healing rate of 72% was noted at a mean follow-up of 11.3 years. The stage of skeletal maturity had no significant influence on the rate of failure. Lateral femoral condylar lesion location is an independent risk factor for failure in skeletally mature and immature patients.

Grooveplasty Compared With Trochleoplasty for the Treatment of Trochlear Dysplasia in the Setting of Patellar Instability.

Purpose: To compare the clinical efficacy in the resolution of patellar instability, patient-reported outcomes (PROs), and complication and reoperation rates between patients who underwent grooveplasty (proximal trochleoplasty) and patients who underwent trochleoplasty as part of a combined patellofemoral stabilization procedure. Methods: A retrospective chart review was performed to identify a cohort of patients who underwent grooveplasty and a cohort who underwent trochleoplasty at the time of patellar stabilization. Complications, reoperations, and PRO scores (Tegner, Kujala, and International Knee Documentation Committee scores) were collected at final follow-up. The Kruskal-Wallis test and Fisher exact test were performed when appropriate, and P < .05 was considered significant. Results: Overall, 17 grooveplasty patients (18 knees) and 15 trochleoplasty patients (15 knees) were included. Seventy-nine percent of patients were female, and the average follow-up period was 3.9 years. The mean age at first dislocation was 11.8 years overall; most patients (65%) had more than 10 lifetime instability events and 76% of patients underwent prior knee-stabilizing procedures. Trochlear dysplasia (Dejour classification) was similar between cohorts. Patients who underwent grooveplasty had a higher activity level (P = .007) and a higher degree of patellar facet chondromalacia (P = .008) at baseline. At final follow-up, no patients had recurrent symptomatic instability after grooveplasty compared with 5 patients in the trochleoplasty cohort (P = .013). There were no differences in postoperative International Knee Documentation Committee scores (P = .870), Kujala scores (P = .059), or Tegner scores (P = .052). Additionally, there were no differences in complication rates (17% in grooveplasty cohort vs 13% in trochleoplasty cohort, P > .999) or reoperation rates (22% vs 13%, P = .665). Conclusions: Proximal trochlear reshaping and removal of the supratrochlear spur (grooveplasty) in patients with severe trochlear dysplasia may offer an alternative strategy to complete trochleoplasty for the treatment of trochlear dysplasia in complex cases of patellofemoral instability. Grooveplasty patients showed less recurrent instability and similar PROs and reoperation rates compared with trochleoplasty patients. Level of Evidence: Level III, retrospective comparative study.

Risk factors for secondary meniscus tears can be accurately predicted through machine learning, creating a resource for patient education and intervention.

PURPOSE: This study sought to develop and internally validate a machine learning model to identify risk factors and quantify overall risk of secondary meniscus injury in a longitudinal cohort after primary ACL reconstruction (ACLR). METHODS: Patients with new ACL injury between 1990 and 2016 with minimum 2-year follow-up were identified. Records were extensively reviewed to extract demographic, treatment, and diagnosis of new meniscus injury following ACLR. Four candidate machine learning algorithms were evaluated to predict secondary meniscus tears. Performance was assessed through discrimination using area under the receiver operating characteristics curve (AUROC), calibration, and decision curve analysis; interpretability was enhanced utilizing global variable importance plots and partial dependence curves. RESULTS: A total of 1187 patients underwent ACLR; 139 (11.7%) experienced a secondary meniscus tear at a mean time of 65 months post-op. The best performing model for predicting secondary meniscus tear was the random forest (AUROC = 0.790, 95% CI: 0.785-0.795; calibration intercept = 0.006, 95% CI: 0.005-0.007, calibration slope = 0.961 95% CI: 0.956-0.965, Brier's score = 0.10 95% CI: 0.09-0.12), and all four machine learning algorithms outperformed traditional logistic regression. The following risk factors were identified: shorter time to return to sport (RTS), lower VAS at injury, increased time from injury to surgery, older age at injury, and proximal ACL tear. CONCLUSION: Machine learning models outperformed traditional prediction models and identified multiple risk factors for secondary meniscus tears after ACLR. Following careful external validation, these models can be deployed to provide real-time quantifiable risk for counseling and timely intervention to help guide patient expectations and possibly improve clinical outcomes. LEVEL OF EVIDENCE: III.

Regulatory and Ethical Aspects of Orthobiologic Therapies.

Orthobiologic therapies show significant promise to improve outcomes for patients with musculoskeletal pathology. There are considerable research efforts to develop strategies that seek to modulate the biological environment to promote tissue regeneration and healing and/or provide symptomatic relief. However, the regulatory pathways overseeing the clinical translation of these therapies are complex, with considerable worldwide variation. The introduction of novel biologic treatments into clinical practice raises several ethical dilemmas. In this review, we describe the process for seeking approval for biologic therapies in the United States, Europe, and Japan. We highlight a number of ethical issues raised by the clinical translation of these treatments, including the design of clinical trials, monitoring outcomes, biobanking, "off-label" use, engagement with the public, marketing of unproven therapies, and scientific integrity.

Successful Fixation of Traumatic Articular Cartilage-Only Fragments in the Juvenile and Adolescent Knee: A Case Series.

Background: Some surgeons are now considering fixation of traumatic chondral-only fragments in juvenile knees, but few data remain to guide treatment. Purpose: To determine if surgical fixation of chondral-only fragments in the juvenile knee results in an adequate healing response with successful imaging and clinical outcomes. Study Design: Case series; Level of evidence, 4. Methods: Data were collected on 16 skeletally immature patients treated with fixation of chondral-only fragments with a minimum 1-year follow-up. Patients were selected by the operating surgeons based on the quality and size of the chondral fragment. Demographic data, lesion characteristics, surgical procedure details, complications, and postoperative imaging were assessed. Validated outcome measures were collected pre- and postoperatively and included the following scores: International Knee Documentation Committee (IKDC), Marx Activity Scale, Knee injury and Osteoarthritis Outcome Score (KOOS), Hospital for Special Surgery Pediatric Functional Activity-Brief Scale (HSS Pedi-FABS), Patient-Reported Outcomes Measurement Information System (PROMIS)-Physical Health and PROMIS-Psychological Health, and Tegner. Results: The mean age of our patient cohort was 14.9 years. The mean size of the repaired defects measured 3.2 cm2. Injury sites included the patella (n = 1), medial femoral condyle (n = 3), trochlea (n = 4), and lateral femoral condyle (n = 8). Within the mean follow-up time of 42.3 months (range, 15-145), there was 1 clinical failure with loosening of the chondral fragment and the need for reoperation. At a mean follow-up of 3.5 years, the mean (interquartile range) patient-reported outcome scores were as follows: IKDC, 95.2 (94.3-100); Marx Activity Scale, 11.5 (11.5-16); KOOS, 95.81 (93.5-95.81); HSS Pedi-FABS, 16.94 (11.5-26); PROMIS-Physical Health, 93.75% (90%-100%); PROMIS-Psychological Health, 90% (88.75%-100%); and Tegner, 5.69 (4.75-7). All patients who were engaged in sports before injury returned to the same or higher level of competition with the exception of 1 patient. Conclusion: Primary repair of chondral-only injuries with internal fixation can be a successful treatment option in selected patients. Clinical and imaging results at final follow-up suggest that reintegration of the cartilage fragment is achievable and leads to excellent clinical function and a high return-to-sports rate.