Citations

Meniscal injuries have posed a challenging problem for many years, especially considering that historically the meniscus was considered to be a structure with no important role in the knee joint. This led to earlier treatments aiming at the removal of the entire structure in a procedure known as a meniscectomy. However, with the current understanding of the function and roles of the meniscus, meniscectomy has been identified to accelerate joint degradation significantly and is no longer a preferred treatment option in meniscal tears. Current therapies are now focused to regenerate, repair, or replace the injured meniscus to restore its native function. Repairs have improved in technique and materials over time, with various implant devices being utilized and developed. More recently, strategies have applied stem cells, tissue engineering, and their combination to potentiate healing to achieve superior quality repair tissue and retard the joint degeneration associated with an injured or inadequately functioning meniscus. Accordingly, the purpose of this current review is to summarize the current available pre-clinical and clinical literature using stem cells and tissue engineering for meniscal repair and regeneration.

AbstractFailed multiligament knee reconstruction is a challenging problem due to recurrent pathologic laxity that is often associated with limb malalignment, meniscus deficiency, articular cartilage insufficiency, decreased motion, compromised bone stock, and a paucity of graft sources. Revision surgical indications and techniques require a comprehensive evaluation of the patient, injury and treatment factors along with a focused physical examination and advanced imaging. A stepwise treatment approach can be effective in the evaluation of revision surgery and also in setting realistic patient goals.

Objective. Osteochondral allograft (OCA) transplantation has demonstrated good long-term outcomes in treatment of cartilage defects. Viability, a key factor in clinical success, decreases with peri-implantation storage at 4°C during pathogen testing, matching logistics, and transportation. Modern, physiologic storage conditions may improve viability and enhance outcomes. Design. Osteochondral specimens from total knee arthroplasty patients (6 males, 5 females, age 56.4 ± 2.2 years) were stored in media and incubated at normoxia (21% O 2 ) at 22°C or 37°C, and hypoxia (2% O 2 ) at 37°C. Histology, live-dead staining, and quantitative polymerase chain reaction (qPCR) was performed 24 hours after harvest and following 7 days of incubation. Tissue architecture, cell viability, and gene expression were analyzed. Results. No significant viability or gene expression deterioration of cartilage was observed 1-week postincubation at 37°C, with or without hypoxia. Baseline viable cell density (VCD) was 94.0% ± 2.7% at day 1. At day 7, VCD was 95.1% (37°C) with normoxic storage and 92.2% (37°C) with hypoxic storage ( P ≥ 0.27). Day 7 VCD (22°C) incubation was significantly lower than both the baseline and 37°C storage values (65.6%; P < 0.01). COL1A1, COL1A2, and ACAN qPCR expression was unchanged from baseline ( P < 0.05) for all storage conditions at day 7, while CD163 expression, indicative of inflammatory macrophages and monocytes, was significantly lower in the 37°C groups ( P < 0.01). Conclusion. Physiologic storage at 37°C demonstrates improved chondrocyte viability and metabolism, and maintained collagen expression compared with storage at 22°C. These novel findings guide development of a method to optimize short-term fresh OCA storage, which may lead to improved clinical results.

Background: The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC. Purpose: To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC. Study Design: Descriptive laboratory study. Methods: A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors. Results: Strain responses during simulated landing tasks for the ACL ( P ≥ .545) and MCL ( P ≥ .489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL ( P < .001) and MCL ( P < .001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC. Conclusion: Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture. Clinical Relevance: Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

Background: There are limited data comparing the outcomes of similarly matched patients with a medial meniscus posterior root tear (MMPRT) treated with nonoperative management, partial meniscectomy, or repair. Purpose/Hypothesis: The purpose was to compare treatment failure, clinical outcome scores, and radiographic findings for a matched cohort of patients who underwent either nonoperative management, partial meniscectomy, or transtibial pull-through repair for an MMPRT. We hypothesized that patients who underwent meniscus root repair will have lower rates of progression to arthroplasty than patients who were treated with nonoperative management or partial meniscectomy. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent transtibial medial meniscus posterior horn root repair were matched by meniscal laterality, age, sex, and Kellgren-Lawrence (K-L) grades to patients treated nonoperatively or with a partial meniscectomy. Progression to arthroplasty rates, International Knee Documentation Committee and Tegner scores, and radiographic outcomes were analyzed between groups. Results: Forty-five patients were included in this study (15 nonoperative, 15 partial meniscectomy, 15 root repair). Progression to arthroplasty demonstrated significant differences among treatment groups at a mean of 74 months (nonoperative, 4/15; partial meniscectomy, 9/15; meniscal repair, 0/15; P = .0003). The meniscus root repair group had significantly less arthritic progression, as measured by change in K-L grade from pre- to postoperatively (nonoperative, 1.0; partial meniscectomy, 1.1; meniscal repair, 0.1; P = .001). Conclusion: Meniscus root repair leads to significantly less arthritis progression and subsequent knee arthroplasty compared with nonoperative management and partial meniscectomy in a matched cohort based on patient characteristics.

Background: While a large volume of literature has focused on risk factors for anterior shoulder instability, the rates of recurrence are inconsistent and require additional population-based epidemiologic data. Purpose/Hypothesis: The purpose was to report the effect of patient age on the number of instability events before physician consultation, rate of surgical stabilization, recurrent instability, and progression to osteoarthritis in patients <40 years old with anterior shoulder instability, utilizing an established US geographic population. We hypothesized that younger patients would be more likely to experience multiple episodes of instability before evaluation, undergo surgery, and experience recurrent instability after surgical intervention. Study Design: Descriptive epidemiologic study. Methods: An established geographic database of more than 500,000 patients was used to identify patients <40 years of age with anterior shoulder instability between 1994 and 2016. Medical records were reviewed to obtain patient characteristics, history, imaging, surgical details, and outcomes. Patients were divided into 5 groups based on age (≤15, 16-20, 21-25, 26-30, and 31-40 years) at initial instability. Comparative analysis was performed to identify differences between groups. Results: The study population consisted of 654 patients with a mean follow-up of 11.1 years (range, 2.0-25.2 years). This resulted in 118 patients (18%) ≤15 years of age at initial instability; 250 (38%), 16 to 20 years; 110 (17%), 21 to 25 years; 80 (12%), 26 to 30 years; and 96 (15%), 31 to 40 years. Of patients ≤15 years old at initial instability 47% had 3+ instability events, compared with 12% of patients aged 31 to 40 years ( P < .001). At 10 years of follow-up, patients ≤15 and 16 to 20 years old demonstrated the highest recurrent instability rates of 38.8% and 47.1% after nonoperative management, respectively. Patients 16 to 20 years old demonstrated the highest rates of both surgical intervention (40.4%) and recurrence after surgery (24.8%). Patients 31 to 40 years of age were significantly more likely to develop clinically symptomatic osteoarthritis (15.6%) than all other age groups. Conclusion: In a US epidemiologic population of patients <40 years old, the rate of recurrent anterior shoulder instability was roughly one-third after initial physician consultation. Younger patients, particularly those ≤15 and 16 to 20 years of age, were more likely to have experienced multiple instability events at the time of initial evaluation, require surgery, and experience recurrent instability compared with older patients. For every year of decrease in age at initial instability, the risk of recurrent instability or surgical intervention after physician consultation increased by 4.1% and 2.8%, respectively.

Objective This study aims to (1) determine and validate living cartilage allograft transplantation as a novel source for viable osteochondral allograft (OCA) tissues and (2) perform histologic and viability comparisons of living donor cartilage tissues to currently available clinical-grade standard processed grafts. Design Using healthy cartilage from well-preserved contralateral compartments in 27 patients undergoing total knee arthroplasty (TKA) and 10 clinical-grade OCA specimens obtained immediately following operative implantation, standard and living donor OCA quality was evaluated at the time of harvest and following up to 3 weeks of storage on the basis of macroscopic International Cartilage Repair Society grade, histology, and viability. Results Osteochondral samples demonstrated a consistent decrease in viability and histologic quality over the first 3 weeks of storage at 37°C, supporting the utility of an OCA paradigm shift toward early implantation, as was the clinical standard up until recent adoption of transplantation at 14 to 35 days following donor procurement. Samples from the 10 clinical-grade OCAs, implanted at an average of 23 days following graft harvest demonstrated a mean viable cell density of 45.6% at implantation, significantly lower ( P < 0.01) than the 93.6% viability observed in living donor allograft tissues. Conclusions Osteochondral tissue viability and histologic quality progressively decreases with ex vivo storage, even when kept at physiologic temperatures. Currently available clinical OCAs are stored for 2 to 5 weeks prior to implantation and demonstrate inferior viability to that of fresh osteochondral tissues that can be made available through the use of a living donor cartilage program.

Abstract Meniscus tears are commonly encountered in the clinical and operative setting and vary in presentation, including bucket‐handle, radial, and horizontal cleavage tears. Historically, tears were treated with benign neglect or partial meniscectomy. However, a great deal of subsequent research has highlighted the biomechanical consequences of tears and meniscectomy, including increased peak local contact forces, progressive postmeniscectomy arthritis, and subsequent arthroplasty. With the advent and evolution of repair devices, increasing attention is being turned to the ideal restorative treatment of meniscus tears. Successful meniscus repair is centered about the ABCs of repair: Anatomic reduction, Biologic preparation and augmentation, and Circumferential compression. Recent advances in repair techniques have included microfracture of the intercondylar notch to provide healing factors and marrow cells for augmented healing, all‐inside suture devices enabling the reduction and fixation tears without the need for additional assistants and the morbidity of inside‐out exposure, and circumferential compression combined with clot augmentation to reduce and fix horizontal cleavage tears and recreate biomechanics to within 15% of baseline contact forces. Clinical outcomes of meniscus repair using modern techniques have been promising, with reapproximation of native joint biomechanics, substantial improvements in patient subjective outcome scores, and satisfactory reoperation rates. With implementation of the ABCs of meniscus repair as well as the continued expansion of the orthopedic surgeons' meniscus repair toolbox, restoration and preservation of the meniscus are increasingly possible across the spectrum of tear types.

Background: It is unclear whether chondral fragments without bone have the potential to heal after fixation. Controversy exists and opinions differ regarding the optimal treatment of chondral defects after pure chondral fracture. Purpose: To determine clinical and radiographic outcomes after internal fixation of traumatic chondral fragments repaired to bone in the knee. Study Design: Case series; Level of evidence, 4. Methods: A retrospective clinical and radiographic evaluation of 10 male patients with a mean age of 14.6 years (range, 10-25 years) at the time of surgery was performed. Eight of 10 patients were skeletally immature. Patients were selected by operating surgeons per the presence of a large displaced pure chondral fragment on magnetic resonance imaging and confirmed on intraoperative inspection. All patients had a diagnosed traumatic displaced pure chondral fracture of the knee (without bone) and underwent internal fixation with minimum 1-year follow-up. Validated patient-reported and surgeon-measured outcomes were collected pre- and postoperatively. All patients were evaluated at a mean 56 months postoperatively. Results: At surgery, the mean defect size that was primarily repaired with the displaced chondral fragment was 1.9 × 2.0 cm. With minimum 1-year follow-up, there were no clinical failures. All 8 patients who had subsequent magnetic resonance imaging follow-up had radiographic evidence of complete healing of the chondral fragment back to bone. At a mean follow-up of 56 months (range, 13-171 months; median, 36 months), patients had a mean International Knee Documentation Committee score of 94.74 (range, 87.4-100), a mean Marx Activity Scale score of 14.4 (range, 8-16), and a mean Tegner Activity Scale score of 7 (range, 5-9). At final follow-up, all patients except 1 returned to sports. Conclusion: The treatment of large traumatic chondral fragments is controversial. In this select series of 10 young patients who underwent primary repair with internal fixation, there were no failures clinically. Patients demonstrated excellent short-term clinical and radiographic results after fixation of these relatively large chondral fragments in the knee.

Objective To report radiographic and magnetic resonance imaging findings, patient-reported outcomes, and complications and/or reoperations following nonarthroplasty surgical intervention for focal glenohumeral cartilage defects. Design A literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Patients were included if they possessed a chondral defect of the humeral head, glenoid, or both, which had been treated with a joint preserving nonarthroplasty procedure. Risk of bias assessment was performed using the Methodological Index for Non-Randomized Studies scoring system. Study demographics, surgical technique, imaging findings, patient-reported outcomes, complications, failures, and reoperations were collected. Results Fourteen studies with 98 patients (100 shoulders) met the inclusion criteria. Patient ages ranged from 7 to 74 years. The nonarthroplasty surgical techniques utilized included microfracture (67 shoulders), osteochondral transplantation (28 shoulders), chondrocyte transplantation (4 shoulders), and internal fixation (1 shoulder). The rates of radiographic union and progression of osteoarthritis ranged between 90% to 100% and 57% to 100%, respectively. Visual analog scores ranged from 0 to 1.9 at final follow-up. Mean postoperative ASES (American Shoulder and Elbow Surgeons) shoulder scores ranged from 75.8-100. Mean postoperative CSS (Constant Shoulder Score) scores ranged from 83.3-94. Mean postoperative SSV (Subjective Shoulder Value) ranged from 70% to 99%. Failure and reoperation rates ranged between 0% to 35% and 0% to 30%, respectively, with the most common reoperation being conversion to prosthetic arthroplasty. Conclusions In this systematic review, nonarthroplasty surgical techniques demonstrated acceptable rates of radiographic healing, improved patient reported outcomes, minimal complications, and low rates of failure or reoperation. Joint preserving techniques are likely viable options to prolong function of the native shoulder and provide short- to midterm pain relief in young and highly active patients. Level of Evidence Level IV.