Custers, Roel J.H.

Background: Increased posterior tibial slope (PTS) has been associated with higher revision rates after anterior cruciate ligament reconstruction (ACLR). Whether the addition of lateral extra-articular tenodesis (LET) mitigates the risk associated with increased PTS is unclear. Purpose: To determine the prevalence of increased PTS (≥12°) in a young high-risk primary ACLR population and evaluate whether LET is associated with lower revision rates in patients with increased PTS. Study Design: Cohort study; Level of evidence, 3. Methods: This study included patients aged ≤25 years undergoing primary ACLR across 3 high-volume centers with ≥2 years between surgery and data collection. PTS was measured on lateral radiographs for medial and lateral plateaus. Primary analyses consisted of 4 prespecified multivariable logistic regression models with different PTS operationalizations as continuous predictors per 1° increase (medial PTS, lateral PTS, the maximum [PTSmax], and the lateral-medial difference), adjusted for patient and surgical covariates including graft type, with surgical center as a fixed effect. Secondary analyses used PTS dichotomized at 12°; revision rates were compared between isolated ACLR and ACLR with LET, with the treatment effect quantified as absolute risk reduction and number needed to treat. Results: A total of 780 patients were included; 84 (10.8%) underwent revision ACLR. Increased PTS (≥12°) was present in 28.2% of patients and more common in those requiring revision (38.6% vs 27.0%; P = .03). In patients with PTSmax ≥12°, revision occurred in 21.0% without LET and 9.2% with LET (absolute risk reduction, 11.8% [95% CI, 2.3%-21.3%]; number needed to treat, 9); in patients with PTSmax <12°, revision occurred in 13.2% without LET and 5.4% with LET (absolute risk reduction, 7.8% [95% CI, 3.0%-12.6%]; number needed to treat, 13). In the 4 prespecified multivariable models with PTS as a continuous predictor, LET was independently associated with substantially lower odds of revision ACLR (odds ratio [OR], 0.37; 95% CI, 0.22-0.62; P < .001). Lateral PTS (OR, 1.09 per 1° increase; 95% CI, 1.00-1.18; P = .04) and PTSmax (OR, 1.09; 95% CI, 1.00-1.19; P = .04) were independently associated with revision ACLR. The lateral-medial PTS difference was not associated with revision ACLR. Conclusion: In a young high-risk primary ACLR population, increased PTS was present in nearly 30% of patients. LET was associated with a lower risk of revision irrespective of PTS, while increased PTS was independently associated with revision ACLR.

Background: Total knee arthroplasty (TKA) is the treatment of choice for end-stage knee osteoarthritis in many patients. In younger patients with predominantly medial compartment disease, high tibial osteotomy (HTO) is performed as a joint-preserving treatment. However, concerns remain regarding potentially compromised outcomes of TKA after previous HTO given the axial deviation, osteotomy site, secondary surgery, previous hardware, and instrumentation. Therefore, this study compared long-term implant survival, revision, and infection rates, and patient-reported outcomes between patients undergoing TKA after HTO and matched TKA-only controls. Methods: Postoperative complications and revision surgeries were prospectively recorded in patients who underwent TKA from 2000 to 2023 at a single academic center. Patients with previous ipsilateral HTO formed the study group and were propensity matched 1:2 to TKA-only patients without a previous osteotomy based on age, sex, and body mass index. Knee Society Scores (KSS) were collected prospectively. Implant survivorship was analyzed using Kaplan-Meier survival curves and Cox proportional hazards models. Results: The study included 134 HTO-TKA and 268 matched TKA-only patients, with a mean follow-up of 10.5 ± 6.4 years (range: 0-24 years) after TKA. Both groups showed significant postoperative improvements in KSS (p < 0.02) with comparable clinical outcomes (HTO-TKA: 79.0 (6.0), TKA-only: 79.0 (11.8)). Revision arthroplasty rates were 5.2% for HTO-TKA and 4.5% for TKA-only (p = 0.69); the mean time to revision was 8.1 ± 8.7 years vs. 4.4 ± 3.5 years, respectively (p = 0.30). Infection rates were 2.2% and 1.1%, respectively (p = 0.74). Conclusions: Revision and infection rates were comparable between HTO-TKA and matched TKA-only patients, with no statistically significant differences. Our findings demonstrate comparable patient-reported outcomes in both groups. These findings indicate that a previous HTO does not adversely affect TKA implant longevity or clinical outcomes when compared with matched primary TKA patients within the US population. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

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.

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 (β = 0.27; P = .05), whereas bilateral treatment predicted worse outcomes (β = –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.

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.

Background: Long-term clinical evaluation of patient outcomes can steer treatment choices and further research for cartilage repair. Using mesenchymal stromal cells (MSCs) as signaling cells instead of stem cells is a novel approach in the field. Purpose: To report the 5-year follow-up of safety, clinical efficacy, and durability after treatment of symptomatic cartilage defects in the knee with allogenic MSCs mixed with recycled autologous chondrons in first-in-human study of 1-stage cartilage repair. Study Design: Case series; Level of evidence, 4. Methods: This study is an investigator-driven study aiming at the feasibility and safety of this innovative cartilage repair procedure. Between 2013 and 2014, a total of 35 patients (mean ± SD age, 36 ± 8 years) were treated with a 1-stage cartilage repair procedure called IMPACT (Instant MSC Product Accompanying Autologous Chondron Transplantation) for a symptomatic cartilage defect on the femoral condyle or trochlear groove. Subsequent follow-up after initial publication was performed annually using online patient-reported outcome measures with a mean follow-up of 61 months (range, 56-71 months). Patient-reported outcome measures included the KOOS (Knee injury and Osteoarthritis Outcome Score), visual analog scale for pain, and EuroQol–5 Dimensions. All clinical data and serious adverse events, including additional treatment received after IMPACT, were recorded. A failure of IMPACT was defined as a chondral defect of at least 20% of the index lesion with a need for a reintervention including a surgical procedure or an intra-articular injection. Results: Using allogenic MSCs, no signs of a foreign body response or serious adverse reactions were recorded after 5 years. The majority of patients showed statistically significant and clinically relevant improvement in the KOOS and all its subscales from baseline to 60 months: overall, 57.9 ± 16.3 to 78.9 ± 17.7 ( P < .001); Pain, 62.3 ± 18.9 to 79.9 ± 20.0 ( P = .03); Function, 61.6 ± 16.5 to 79.4 ± 17.3 ( P = .01); Activities of Daily Living, 69.0 ± 19.0 to 89.9 ± 14.9 ( P < .001); Sports and Recreation, 32.3 ± 22.6 to 57.5 ± 30.0 ( P = .02); and Quality of Life, 25.9 ± 12.9 to 55.8 ± 26.8 ( P < .001). The visual analog scale score for pain improved significantly from baseline (45.3 ± 23.6) to 60 months (15.4 ± 13.4) ( P < .001). Five cases required reintervention. Conclusion: This is the first study showing the midterm safety and efficacy of the proof of concept that allogenic MSCs augment 1-stage articular cartilage repair. The absence of serious adverse events and the clinical outcome support the longevity of this unique concept. These data support MSC-augmented chondron transplantation (IMPACT) as a safe 1-stage surgical solution that is considerably more cost-effective and a logistically advantageous alternative to conventional 2-stage cell-based therapy for articular chondral defects in the knee.

Objective: To investigate the preclinical feasibility of using bio-airbrush technology for the fully arthroscopic treatment of cartilage defects with a combination of cells and biomaterials. Design: A combination of in vitro , ex vivo , and cadaveric in situ experiments was performed, to evaluate the preclinical feasibility of using bio-airbrush technology for cartilage repair. Cartilage matrix production after airbrushing cells was evaluated. Subsequently, the influence of different spray parameters on successful defect fill was studied. Finally, the surgical feasibility of using bio-airbrush technology was evaluated in situ in cadaveric knees. Results: The most important findings of the presented study are that the matrix producing capacity of the cells was not hampered by airbrushing, air pressure and defect location were important parameters to consider, and using the bio-airbrush was found to be surgically feasible in a CO 2 -insufflated arthroscopic procedure in cadaveric knees. Conclusions: Bio-airbrush using CO 2 arthroscopy would facilitate fully arthroscopic application of (cell laden) two-component in situ gelating biomaterials to cartilage defects, as a treatment for cartilage repair. This would shift the conventional procedures, which are commonly performed using a (mini-)arthrotomy, toward arthroscopy. Impact Statement This study shows that a bio-airbrush can be a clinically feasible instrument for the use in cell transplantations to repair knee cartilage defects. This technology would enable a shift from cartilage repair procedures, which are mostly performed using an arthrotomy, toward a fully arthoscopic approach. In addition, the technology presented could possibly be translated to other fields of research where controlled in situ deposition of cells is required, such as treatment of burn wounds/ulcers/others. Our research has shown that the use of an airbrush is safe, without harming cell viability and performance.

Purpose: To test the technical aspects and feasibility of seeding a combination of meniscus cells isolated from a rapid digestion protocol and mesenchymal stromal cells (MSCs) (20:80 ratio) into a meniscus scaffold for the development of a one-stage arthroscopic procedure for meniscus regeneration. Methods: A cadaveric study was performed using nine fresh frozen human cadaveric knee joints. Two different arthroscopic cell-seeding methods were applied to the Collagen Meniscus Implant (CMI ® ) as carrier scaffold: either (1) seeding before arthroscopic surgical implantation of the scaffold or (2) after implantation of the scaffold. The cells were injected inside the scaffold, using fast green-stained fibrin glue as carrier, to macroscopically visualize the amount of fibrin glue. Macroscopic pictures and confocal microscopy analyses were used to determine cell distribution and viability. In addition, the DNA content in the cell-seeded scaffold was determined. In addition, different concentrations of Liberase were examined to find the optimal concentration for rapid digestion of meniscus tissue. Results: Macroscopically, seeding before implantation showed a better distribution of fast green-stained fibrin glue carrier than seeding the scaffold before surgical implantation. In addition, it resulted in significantly more cells and a better cell distribution compared with seeding the scaffold after arthroscopic implantation. Both seeding methods did not affect cell viability. After rapid digestion, 0.0125% Liberase resulted in the highest cell isolation efficiency. Conclusions: This study demonstrates that living human meniscus cells can be isolated efficiently, combined with MSCs in 20:80 ratio, and uniformly delivered into a currently available meniscus scaffold. This scaffold can then be arthroscopically implanted, creating a one-stage solution for partial meniscal deficiency. Impact Statement Meniscus injury remains the most common indication for orthopedic surgery, but loss of functioning meniscus tissue is strongly correlated with development of early osteoarthritis. However, current clinical options for tissue engineering of the meniscus are limited. This study demonstrates the feasibility of combining human meniscus cells with mesenchymal stromal cells to enhance a meniscus scaffold for meniscus regeneration in a one-stage solution for partial meniscal deficiency.

Background: Osteochondritis dissecans (OCD) is a disorder of unknown origin that can affect knees in skeletally mature and immature patients. Surgical management is an important cornerstone of treatment for unstable OCD lesions. Purpose: To determine the (1) healing rate after internal fixation of unstable OCD between skeletally immature and mature knees, (2) risk factors for failure, and (3) patient-reported outcomes among healed patients. Study Design: Cohort study; Level of evidence, 3. Methods: A multicenter retrospective cohort study was conducted with patients who underwent internal fixation of unstable knee OCD lesions from 2000 to 2015. Skeletal immaturity was defined as open or partially open physes. Healing was assessed through clinical findings and imaging. Definitive reoperation for the same OCD lesion was classified as failure. Results: Among 87 patients included, 66 (76%) had healed lesions at ≥2 years postoperatively, while 21 (24%) failed. Skeletal maturity made no significant difference in failure rate (risk ratio, 0.68; 95% CI, 0.29-1.72; P = .40). For skeletally immature patients, lateral versus medial condylar location conferred an increased hazard of 18.2 (95% CI, 1.76-188.07; P < .01). Multivariate analysis factoring in skeletal maturity showed that lateral condylar location was an independent risk factor for failure (hazard ratio, 4.25; 95% CI, 1.47-19.85; P < .01). Mean patient-reported outcome scores (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]) increased significantly after surgery, except the KOOS symptoms score for the skeletally mature group. Final scores (mean ± SD) were as follows at a mean follow-up of 60 months (range, 24-166): IKDC, 83.5 ± 20.2; KOOS pain, 89.7 ± 14.1; KOOS symptoms, 87.4 ± 18.4; KOOS activities of daily living, 93.9 ± 12.7; KOOS sports, 80.7 ± 25.9; KOOS quality of life, 78.9 ± 23.1. Conclusion: Skeletally immature and mature patients heal at comparable rates after internal fixation of OCD lesions, resulting in functional and subjective improvement. Lateral femoral condylar lesion location is an independent risk factor for failure.