Short-to Mid-Term Survivorship of a Patient-specific Unicompartmental Knee Arthroplasty Implant Cast from a Three-Dimensional Printed Mold.

The purpose of this study was to determine early survivorship and complication rates associated with the implantation of a new patient-specific unicompartmental knee implant cast from a three-dimensional (3D) printed mold, introduced in 2012. We retrospectively reviewed 92 consecutive patients who underwent unicompartmental knee arthroplasty (UKA) with a patient-specific implant cast from a 3D printed mold between September 2012 and October 2015. The early results of a patient-specific UKA implant were favorable in our cohort, with survivorship free from reoperation of 97% at an average 4.5 years follow-up. Future studies are necessary to investigate the long-term performance of this implant. Survivorship of a patient-specific unicompartmental knee arthroplasty implant cast from a 3D printed mold.

Etiology of Cartilage Lesions Does Not Affect Clinical Outcomes of Patellofemoral Autologous Chondrocyte Implantation.

OBJECTIVE: To determine the relationship between cartilage lesion etiology and clinical outcomes after second-generation autologous chondrocyte implantation (ACI) in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up. METHODS: A retrospective review of all patients that underwent ACI in the PFJ by a single surgeon was performed. Seventy-two patients with a mean follow-up of 4.2 ± 2.0 years were enrolled in this study and were stratified into 3 groups based on the etiology of PFJ cartilage lesions: patellar dislocation (group 1; n = 23); nontraumatic lesions, including chondromalacia, osteochondritis dissecans, and degenerative defects (group 2; n = 28); and other posttraumatic lesions besides patellar dislocations (group 3; n = 21). Patient's mean age was 29.6 ± 8.7 years. Patients in group 1 were significantly younger (25.4 ± 7.9 years) than group 2 (31.7 ± 9.6 years; P = 0.025) and group 3 (31.5 ± 6.6 years; P = 0.05). Body mass index averaged 26.2 ± 4.3 kg/m2, with a significant difference between group 1 (24.4 ± 3.2 kg/m2) and group 3 (28.7 ± 4.5 kg/m2; P = 0.005). A clinical comparison was established between groups based on patient-reported outcome measures (PROMs) and failure rates. RESULTS: Neither pre- nor postoperative PROMs differed between groups (P > 0.05). No difference was seen in survivorship between groups (95.7% vs. 82.2% vs. 90.5%, P > 0.05). CONCLUSION: Cartilage lesion etiology did not influence clinical outcome in this retrospective study after second generation ACI in the PFJ. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

The Minimal Clinically Important Difference and Substantial Clinical Benefit in the Patient-Reported Outcome Measures of Patients Undergoing Osteochondral Allograft Transplantation in the Knee.

OBJECTIVE: Little is known regarding the minimal clinically important difference (MCID) and substantial clinical benefit (SCB) with regard to the Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Lysholm score, and Short Form 12 (SF-12) score of patients who undergo osteochondral allograft transplantation (OCA). We aimed to determine the MCID and SCB associated with those patient-reported outcome measures (PROMs) after OCA. DESIGN: We analyzed the data of 86 consecutive patients who underwent OCA and who completed satisfaction surveys at a minimum of 1 year postoperatively and had at least one repeated PROM. MCID was determined using an anchor-based method: the optimal cutoff point for receiver operative characteristic (ROC) curves. If an anchor-based method was inapplicable, distribution-based methods were employed. SCB was determined using ROC curve analysis. RESULTS: Based on the ROC curve analysis, MCID was 16.7 for KOOS pain, 25 for KOOS sports/recreation, and 9.8 for IKDC. SCB was 27.7 for KOOS pain, 10.7 for KOOS symptom, 30 for KOOS sports/recreation, 31.3 for KOOS quality of life, 26.9 for IKDC, 25 for Lysholm, and 12.1 for SF-12 physical component summary. No significant association was noted between SCB achievement and the baseline patient factors and baseline PROMs. CONCLUSION: We demonstrated the MCIDs and SCBs of several PROMs in patients undergoing OCA. These results will aid the interpretation of the effect of treatment and clinical trial settings. Moreover, the SCBs will help surgeons in the counseling of patients, where patients expect optimal results rather than minimal improvement.

Femoral interference screw insertion significantly increases graft tension in medial patellofemoral ligament reconstruction.

PURPOSE: This study aimed to quantify the effect of interference screw insertion on MPFL graft tension when securing the femoral attachment after patellar fixation. It was hypothesized that interference screw insertion significantly increases graft tension. METHODS: Ten fresh frozen human cadaveric femurs were utilized to compare graft tension at three different preloading conditions (2 N, 5 N, 10 N) using a tensile testing machine (Admet Inc., Norwood, MA). Each preloading condition was analyzed with varying graft sizes (5-8 mm), tunnel diameters (7-9 mm), and interference screw sizes (7-9 mm). Non-parametric statistical analysis was utilized to compare testing conditions among each other. RESULTS: Graft tension significantly increased after interference screw insertion by 100% to 552%, with 2 N preload showing the greatest increase (p < 0.001). Grafts with a larger diameter (7-8 mm) had a significantly greater increase in tension than smaller grafts (5-6 mm), regardless of preloading conditions (p < 0.001). Interference screw size had no influence on graft tension (n.s.). A graft-tunnel interference (tunnel diameter-graft diameter) fit of 0 mm and 1 mm significantly increased graft tension for each preloading condition when compared to a slightly looser fit of ≥ 2 mm (p < 0.05). CONCLUSION: Femoral interference screw insertion significantly increases graft tension in MPFL reconstruction even in low preloading conditions, with graft size and graft-tunnel interference fit having a considerably effect on graft tension. Surgeons should be aware of the inadvertent increases in graft tension even in low preloading conditions to mitigate the risk of graft overtensioning.

The Effect of Mechanical Leg Alignment on Cartilage Restoration With and Without Concomitant High Tibial Osteotomy.

PURPOSE: To assess graft survivorship in patients who underwent autologous chondrocyte implantation (ACI) or osteochondral allograft transplantation (OCA) for the treatment of focal full-thickness cartilage lesions on the medial femoral condyle with and without concomitant high tibial osteotomy (HTO), depending on the preoperative lower-extremity alignment. A secondary purpose was to retrospectively evaluate associated factors for ACI and OCA graft failures. METHODS: A total of 168 patients who underwent cartilage repair with ACI or OCA with or without HTO for focal chondral defects on the medial femoral condyle by a single surgeon between March 2007 and February 2018 were included. Clinical notes, operative reports, and radiographic imaging were reviewed for each patient. Detailed Kaplan-Meier analyses were performed based on patient's mechanical axis alignment. In a subanalysis, failures and nonfailures in patients treated with ACI or OCA were comparatively evaluated. RESULTS: In ACI, neutral mechanical alignment resulted in a significantly longer graft survival compared with slight valgus alignment (P = .003 and P = .05, respectively). No significant differences in survivorship were seen based on mechanical axis alignment in OCA patients (P > .05). Patients who were considered failures after ACI presented significantly more often with valgus alignment (P = .002), whereas failures in the OCA group were more often female and smokers (P = .025; P = .034). CONCLUSIONS: In summary, the results of this study suggest that neutral mechanical axis alignment, regardless if physiologic or through HTO, improves survivorship in patients undergoing medial compartment ACI. Neutral alignment also showed a trend towards improved survivorship in patients after OCA, but this did not reach statistical significance. LEVEL OF EVIDENCE: Case-Series; Level of evidence, 4.

Prior Surgery Negatively Affects Cell Culture Identity in Patients Undergoing Autologous Chondrocyte Implantation.

BACKGROUND: Recently, a cell identity assay has been introduced to evaluate the identity of cultured chondrocytes before autologous chondrocyte implantation (ACI), which was shown to be associated with graft survival after ACI. PURPOSE: To identify the influence of several patient- and lesion-specific factors on cell identity and viability assays. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 187 patients with second-generation ACI were included in this study. Patient and lesion characteristics, cell viability, cell identity, and biopsy specimen weight were recorded for each patient. A binomial logistic regression model was utilized to determine patient-specific predictive factors for cell product quality. RESULTS: The implanted ACI cell products showed a cell viability of 93% ± 2.4% (mean ± SD; range, 84-98) with an identity score of 5.8 ± 2.1 (range, -0.08 to 9.46). Patients with multiple previous surgical procedures on the index knee had significantly lower cell identity scores when compared with patients without previous surgery (odds ratio = 0.31; 95% CI, 0.16-0.59; P < .001). Patients without surgical history had significantly higher cell identity scores than patients with 1 and ≥2 previous surgical procedures on the index knee (6.32 vs 5.32 vs 5.05; P = .006 and P < .001, respectively). Cell viability was not predicted by any preoperative variable (P > .05). Cell identity and viability were not associated with each other or with biopsy specimen weight (P > .05). CONCLUSION: Cartilage biopsy specimens from patients with ≥1 previous surgical procedures resulted in implants with lower cell identity scores when compared with patients without previous operations. None of the other patient- or lesion-specific factors were correlated, specifically biopsy specimen weight.

Bone-Plug Versus Soft Tissue Fixation of Medial Meniscal Allograft Transplants: A Biomechanical Study.

BACKGROUND: It is controversial whether soft tissue fixation only and bone-plug techniques for medial meniscal allograft transplantation provide equivalent fixation and restoration of load distribution. Prior studies on this topic did not re-create the clinical situation with use of size-, side-, and compartment-matched meniscal transplants. HYPOTHESIS: Both techniques will provide equivalent fixation of the meniscal transplant and restore load distribution and contact pressures similar to those of the native knee. STUDY DESIGN: Controlled laboratory study. METHODS: Nine fresh-frozen human cadaveric knees underwent mean contact pressure, mean contact area, and peak contact pressure evaluation in 4 medial meniscal testing conditions (native, total meniscectomy, bone-plug fixation, and soft tissue fixation) at 3 flexion angles (0°, 30°, and 60°) using Tekscan sensors under a 700-N axial load. RESULTS: Medial meniscectomy resulted in significantly decreased contact area and increased contact pressure compared with the native condition at all flexion angles (P < .0001). Compared with the native state, soft tissue fixation demonstrated significantly higher mean contact pressure and lower mean contact area at 0° and 30° of flexion (P < .05), while bone-plug fixation showed no significant difference. There was no significant difference in peak contact pressure between study conditions. CONCLUSION: Total medial meniscectomy leads to significantly worsened load distribution within the knee. Medial meniscal allograft transplantation can restore load parameters close to those of the native condition. The bone-plug technique demonstrated improved tibiofemoral contact pressures compared with soft tissue fixation. CLINICAL RELEVANCE: Medial meniscal allograft transplantation with bone-plug fixation is a viable option to restore biomechanics in patients with meniscal deficiency.

Increased Chondrocytic Gene Expression Is Associated With Improved Repair Tissue Quality and Graft Survival in Patients After Autologous Chondrocyte Implantation.

BACKGROUND: Assays to quantitate the quality of autologous chondrocyte implants have recently become available. However, the correlation of the assay score with radiological and clinical outcomes has not been established. PURPOSE/HYPOTHESIS: The purpose was to assess the influence of cell identity (chondrocyte/synoviocyte gene expression ratio) and viability on patient-reported outcome measures, graft survival, and repair tissue quality. It was hypothesized that greater cell product quality as assessed through an identity assay and cell viability is associated with superior outcomes after autologous chondrocyte implantation (ACI) for symptomatic cartilage defects. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Seventy-nine patients with a minimum follow-up of 2 years were included in this study. Of these, 67 patients were available for imaging assessment utilizing the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scoring system. Patients were assigned to groups either below or above the cohort's mean based on their individual cell identity score and viability percentage. RESULTS: Patients were predominantly female (57.7%) with a mean age of 30.0 ± 9.3 years. No differences were seen between Knee injury and Osteoarthritis Outcome Score, Lysholm, Tegner, or International Knee Documentation Committee Subjective Knee Evaluation Form within the viability and cell identity groups at a final follow-up of 3.8 ± 1.4 years after ACI (P > .05). In a subset of patients, the mean MOCART score was 68.3 ± 15.6 at an average magnetic resonance imaging follow-up of 17.7 ± 9.56 months. Low cell identity was significantly associated with the degree of defect filling (P = .025), integration of border zone (P = .01), effusion (P = .024), and ACI graft failure (P = .002). Patients with above-average cell identity scores had a significantly higher survival rate at 5-year follow-up compared with patients with below-average scores (95.8% vs 64.7%; P = .013). Cell viability did not influence MOCART subscales or graft failure (all P > .05). Cell viability and identity showed no significant correlation with each other (r = -0.045; P = .694). CONCLUSION: Cell identity was significantly correlated with structural repair quality and graft survival after second-generation ACI for symptomatic chondral lesions in the knee. While improved imaging outcome and higher graft survivorship were associated with a higher individual cell identity score indicating a higher chondrocyte/synoviocyte gene expression ratio in the final cell product, clinical outcome did not correlate with the identity score.

Effect of Autogenous Bone Marrow Aspirate Treatment on Magnetic Resonance Imaging Integration of Osteochondral Allografts in the Knee: A Matched Comparative Imaging Analysis.

PURPOSE: To accurately evaluate the effects of bone marrow aspirate (BMA) augmentation on osteochondral allograft (OCA) integration on early postoperative magnetic resonance imaging (MRI) using the comprehensive Osteochondral Allograft MRI Scoring System (OCAMRISS). METHODS: This imaging study compared patients who underwent OCA transplantation with and without BMA augmentation for the treatment of focal osteochondral defects in the knee performed by a single surgeon between July 2013 and July 2017. Patients were excluded if they underwent implantation of premade plugs, had an overlapping OCA configuration ("snowman" technique), or did not undergo MRI at 6 months postoperatively. Patients were matched by lesion location, lesion size, age, and body mass index, as well as whether they underwent previous surgical procedures. Data were analyzed using descriptive statistics, Spearman correlation, the independent t test, the Mann-Whitney U test, and the χ2 test. RESULTS: A total of 58 patients (29 per group) were included in this study, with an average age of 36.4 ± 10.1 years and mean body mass index of 28.6 ± 5.1. The mean size of the analyzed OCA plugs was 3.3 ± 1 cm2. At an average imaging follow-up of 5.6 ± 1 months, 86.2% of the grafts had achieved osseous integration at the graft-host junction and 75.9% did not show any cystic changes in the subchondral bone. No difference in any OCAMRISS subscale was seen comparing OCAs with and without BMA augmentation (P > .05). Specifically, osseous integration and subchondral cyst formation were comparable between groups (P = .128 and P = .539, respectively). CONCLUSIONS: OCAs showed excellent osseous integration at the graft-host junction on 6-month postoperative MRI. The treatment of OCAs with autogenous BMA did not result in superior imaging outcomes when analyzed using the OCAMRISS. LEVEL OF EVIDENCE: Level III, case-control study.

Open Meniscal Allograft Transplantation With Transosseous Suture Fixation of the Meniscal Body Significantly Decreases Meniscal Extrusion Rate Compared With Arthroscopic Technique.

PURPOSE: To assess and compare meniscal extrusion rates after lateral "bridge-in-slot" meniscal allograft transplantation (MAT) with arthroscopic versus open insertion. METHODS: In this review of prospectively collected data, we analyzed data from patients who underwent arthroscopic or open lateral MAT. Patients who underwent concomitant distal femoral osteotomy, for whom 1-year postoperative magnetic resonance imaging was unavailable, or who underwent open lateral MAT without the use of transosseous sutures were excluded. Meniscal extrusion in the included patients was assessed by 2 independent examiners by measuring the absolute value and the relative percentage of extrusion on 1.5-T magnetic resonance images at 1-year follow-up. The number of MATs with radial displacement larger or smaller than 3 mm was determined. RESULTS: A total of 20 patients met the inclusion criteria, of whom 10 underwent arthroscopic and 10 underwent open lateral MAT. No statistically significant differences were found in baseline demographic data. Absolute meniscal extrusion was similar between the groups (P = .091). A significantly larger relative percentage of extrusion (arthroscopic MAT, 31 ± 27 mm; open MAT, 10 ± 29 mm; 95% confidence interval, -0.4 to -0.02 mm; P = .03) and a significantly higher extrusion rate were found in patients treated with arthroscopic MAT than in those treated with open MAT (>3 mm in 5 patients [50%] with arthroscopic MAT and 0 patients with open MAT, P = .01). CONCLUSIONS: This study identified similar absolute extrusion and significantly lower postoperative lateral meniscal extrusion rates after open MAT compared with arthroscopic MAT. Transosseous fixation of the meniscal body appears protective against meniscal extrusion after MAT. LEVEL OF EVIDENCE: Level III, case-control study.

Mental Health Has No Predictive Association With Self-Assessed Knee Outcome Scores in Patients After Osteochondral Allograft Transplantation of the Knee.

BACKGROUND: Patient-reported outcome (PRO) measures are progressively utilized as evaluation tools in preoperative and postoperative assessments in orthopaedic practice. Identifying the potential utility of psychosocial factors to predict patient-reported pain and functional outcomes is of increasing interest to determine which patients will derive the greatest benefit from surgical treatment. PURPOSE/HYPOTHESIS: The purpose of this study was to determine potential predictive associations between the preoperative 12-Item Short Form Health Survey Mental Component Summary (SF-12 MCS) score, patient characteristics or osteochondral allograft (OCA) morphology, and PROs in patients who underwent OCA transplantation. We hypothesized that poor preoperative mental health is associated with diminished PROs at final follow-up. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 67 patients with a mean follow-up of 2.7 ± 1.0 years (range, 2-6 years) with complete preoperative and at least 24-month postoperative SF-12 MCS, Knee injury and Osteoarthritis Outcome Score (KOOS), Tegner, Lysholm, and International Knee Documentation Committee (IKDC) scores were included in this study. Pearson correlation coefficients and linear regression models were used to distinguish associations between age, sex, smoking status, body mass index, workers' compensation, previous surgery, concomitant surgery, number of grafts, defect location, total graft size, SF-12 MCS score, and postoperative PRO scores as well as their improvement from baseline (delta). RESULTS: The SF-12 MCS showed significant correlation with the KOOS Activities of Daily Living subscale (P = .015), KOOS Sport/Recreation subscale (P = .024), and IKDC (P = .039). In the multivariable linear regression models, the SF-12 MCS had no predictive association with any PRO measure. Patient sex contributed significantly to the final regression models of the KOOS Sport/Recreation (P = .042), Tegner score (P = .024), and Lysholm score (P = .031). The SF-12 MCS showed no bivariate correlation with changes in any PRO score (delta) (P > .05). CONCLUSION: Preoperative mental health status did not predict perceived functional outcomes as assessed by PRO measures at final follow-up. Female sex was negatively correlated with KOOS Sport/Recreation, Tegner, and Lysholm scores.

Patellofemoral Cartilage Repair.

PURPOSE OF REVIEW: This review provides an overview of well-established and newly developed cartilage repair techniques for cartilage defects in the patellofemoral joint (PFJ). An algorithm will be presented for approaching cartilage defects considering the distinct anatomy of both the patellar and trochlear articular surfaces. RECENT FINDINGS: Recent studies on cartilage repair in the PFJ have demonstrated improved outcomes in an attempt to delay or obviate the need for arthroplasty, and improve symptoms in young patients. While autologous chondrocyte implantation shows good and excellent outcomes for chondral lesions, osteochondral defects are adequately addressed with osteochondral allograft transplantation. In case of patellar malalignment, concomitant tibial tubercle osteotomy can significantly improve outcomes. Particulated cartilage and bone marrow aspirate concentrate are potential new alternative treatments for cartilage repair, currently in early clinical studies. Due to the frequency of concomitant anatomic abnormalities in the PFJ, a thorough clinical examination combined with careful indication for each procedure in each individual patient combined with meticulous surgical technique is central to achieve satisfying outcomes. Additional comparative studies of cartilage repair procedures, as well as investigation of newer techniques, are needed.