Comparison of meniscal allograft transplantation techniques using a preclinical canine model

Generating New Meniscus Therapies via Recent Breakthroughs in Development, Model Systems, and Clinical Diagnostics

Over 850,000 surgeries are performed to treat meniscal injuries each year in the United States. Even with repair, patients are likely to develop osteoarthritis (OA) within the next two decades. There is a pressing clinical need to improve meniscal repair procedures to restore tissue function and prevent joint degeneration later in life. Here we present a review of recently published articles (2020-2024) spanning basic science, translational, and clinical studies to highlight new advances in meniscus research across development, animal models, finite element models, and clinical interventions. Key progenitor cell populations and vascularity changes have been identified in human meniscus tissue development, aging, and degeneration with implications for novel tissue repair strategies. The use of animal and finite element models has expanded our understanding of meniscus tissue function and evaluated new therapies in preclinical studies. Further, advances in clinical diagnostics with machine learning models and surgical techniques have shed light on evidence-based practices for improving patient outcomes. We discuss across multiple length scales (micro-, meso-, macro-) the structure-function relationship of the meniscus in development and disease, recent advances in models and tools to study the meniscus, knowledge gaps in the field, persisting challenges in clinical treatments and assessments, and the translation of basic science therapies into the clinic.

A Bedside-to-Bench-to-Bedside Journey to Advance Osteochondral Allograft Transplantation towards Biologic Joint Restoration

More than 70 million adults in the United States are impacted by osteoarthritis (OA). Symptomatic articular cartilage loss that progresses to debilitating OA is being diagnosed more frequently and earlier in life, such that a growing number of active patients are faced with life-altering health care decisions at increasingly younger ages. Joint replacement surgeries, in the form of various artificial arthroplasties, are reliable operations, especially for older (≥65 years), more sedentary patients with end-stage OA, but have major limitations for younger, more active patients. For younger adults and those who wish to remain highly active, artificial arthroplasties are associated with significantly higher levels of pain, complications, morbidity, dysfunction, and likelihood of revision. Unfortunately, non-surgical management strategies and surgical treatment options other than joint replacement are often not indicated and have not proven to be consistently successful for this large and growing population of patients. As such, these patients are often relegated to postpone surgery, take medications including opioids, profoundly alter their lifestyle, and live with pain and disability until artificial arthroplasty is more likely to meet their functional demands without high risk for early revision. As such, our research team set out to develop, test, and validate biologic joint restoration strategies that could provide consistently successful options for young and active patients with joint disorders who were not considered ideal candidates for artificial arthroplasty. In pursuit of this goal, we implemented a targeted bedside-to-bench-to-bedside translational approach to hypothesis-driven studies designed to address this major unmet need in orthopaedics by identifying and overcoming key clinical limitations and obstacles faced by health care teams and patients in realizing optimal outcomes after biologic joint restoration. The objective of this article is to condense more than two decades of rigorous patient-centered research aimed at optimizing osteochondral and meniscus allograft transplantation toward more consistently successful management of complex joint problems in young and active patients.

Initial Outcomes following Fresh Meniscus Allograft Transplantation in the Knee

Based on recent evidence-based advances in meniscus allograft transplantation (MAT), fresh (viable) meniscus allografts have potential for mitigating key risk factors associated with MAT failure, and preclinical and clinical data have verified the safety of fresh meniscus allografts as well as possible efficacy advantages compared with fresh-frozen meniscus allografts. The objective of this study was to prospectively assess clinical outcomes for the initial cohort of patients undergoing MAT using fresh meniscus allografts at our center. Patients who were prospectively enrolled in a dedicated registry were included for analyses when they had undergone primary MAT using a fresh meniscus allograft for treatment of medial and/or lateral meniscus deficiency with at least 1-year follow-up data recorded. Forty-five patients with a mean final follow-up of 47.8 months (range = 12-90 months) were analyzed. The mean patient age was 30.7 years (range = 15-60 years), mean body mass index (BMI) was 29.7 kg/m2 (range = 19-48 kg/m2), and 14 patients (31%) were females. In total, 28 medial, 13 lateral, and 4 combined medial and lateral MATs with 23 concurrent ligament reconstructions and 2 concurrent osteotomies were included. No local or systemic adverse events or complications related to MAT were reported for any patient in the study. Treatment success rate for all patients combined was 91.1% with three patients requiring MAT revision and one patient requiring arthroplasty. Treatment failures occurred 8 to 34 months after MAT and all involved the medial meniscus. None of the variables assessed were significantly different between treatment success and treatment failure cohorts. Taken together, the data suggest that the use of fresh (viable) meniscus allografts can be considered a safe and effective option for medial and lateral MAT. When transplanted using double bone plug suspensory fixation with meniscotibial ligament reconstruction, fresh MATs were associated with a 91% success rate, absence of local or systemic adverse events or complications, and statistically significant and clinically meaningful improvements in patient-reported measures of pain and function at a mean of 4 years postoperatively.

Prospective Assessment of Outcomes After Femoral Condyle Osteochondral Allograft Transplantation With Concurrent Meniscus Allograft Transplantation

Background

Osteochondral allograft transplantation (OCAT) and meniscus allograft transplantation (MAT) have each become more commonly implemented for the treatment of young to middle-aged patients with complex knee pathology. Evidence regarding tibiofemoral OCAT in the setting of concurrent MAT is limited.

Purpose/Hypothesis

The purpose of this study was to characterize outcomes for femoral condyle OCAT with concurrent MAT (OCAT+MAT) in the ipsilateral compartment of patients after evidence-based shifts in practice. It was hypothesized that OCAT+MAT would be associated with successful outcomes characterized by statistically significant and clinically meaningful improvements in patient-reported outcome measures (PROMs) of knee pain and function in >80% of patients for at least 2 years after transplantation.

Study Design

Case series; Level of evidence, 4.

Methods

With institutional review board approval and documented informed consent, patients who underwent primary OCAT+MAT between 2016 and 2020 and enrolled in a lifelong registry for prospective collection of outcomes after OCAT were included. Patients with minimum 2-year follow-up data regarding complications, failures, adherence, and PROMs were analyzed. Patients who required OCAT and/or MAT revision or conversion to arthroplasty were defined as experiencing treatment failures.

Results

A total of 23 consecutive patients (mean age, 37.1 years; mean body mass index, 28 kg/m2; 14 men) met the inclusion criteria, with a mean follow-up of 51 months (range, 24-86 months). The initial treatment success rate was 78% based on 5 initial treatment failures, and the overall success rate was 83% based on a successful revision OCAT. All failures occurred in the medial compartment. Older patient age (42.2 vs 32.1 years; P = .046) and nonadherence to postoperative restriction and rehabilitation protocols (P = .033; odds ratio, 14) were significant risk factors for treatment failure. All measured PROMs achieved significant improvements (P < .001) and minimum clinically important differences at a minimum of 2 years postoperatively.

Conclusion

OCAT+MAT was associated with successful short- to mid-term outcomes in 83% of cases. Evidence-based shifts in practice were implemented before the enrollment of this patient cohort. Older patients and those who were not adherent to postoperative restriction and rehabilitation protocols had a significantly higher risk for treatment failure and subsequent conversion to arthroplasty.

Accelerated versus Standard Rehabilitation after Meniscus Allograft Transplantation in the Knee

Meniscus allograft transplantation (MAT) is a proven treatment option for patients with symptomatic irreparable meniscus deficiency. When patients are adherent to prescribed postoperative restriction and rehabilitation protocols, outcomes after MAT are considered good to excellent. However, nonadherence to standard protocols is common and can be associated with undesirable outcomes and patient dissatisfaction. Based on demonstrated safety for early weight-bearing following MAT in conjunction with significant advances in graft preservation and surgical techniques, our joint preservation center implemented a shift in practice toward accelerated weight-bearing following MAT and designed this study to test the hypothesis that accelerated rehabilitation would be associated with superior adherence, patient-reported outcomes, and patient satisfaction, without diminishing patient safety, when compared with standard rehabilitation. Patients were included for analyses when they had undergone fresh or fresh-frozen MAT using a double bone plug technique for treatment of medial or lateral meniscus deficiency and had at least 1-year treatment outcomes recorded. The results of this study revealed that patients who were prescribed accelerated rehabilitation after MAT were significantly more adherent than patients who were prescribed standard rehabilitation and reported statistically significant and clinically meaningful improvements in knee pain and function for at least 1-year following MAT, whereas those in the standard cohort did not. While not statistically different, treatment failure rate was lower in the accelerated rehabilitation cohort when compared with the standard rehabilitation cohort (11 vs. 29%). Importantly, initial outcomes for revision MAT were associated with short-term success in all the patients who opted for this option in the study population. These data suggest that accelerated weight-bearing after MAT is safe, promotes patient adherence, and is associated with statistically significant and clinically meaningful improvements in patient-reported knee pain and function at early and mid-term follow-up.

Outcomes following open acetabular labrum reconstruction: Comparing fresh-frozen tendon with fresh meniscus allograft transplantation

Background

Symptomatic acetabular labral insufficiency in young, active patients is often treated with labral repair or reconstruction using fresh-frozen allografts. However, fresh-frozen tendon allografts do not have tissue or material properties that closely mimic acetabular labral fibrocartilage. Recent studies suggest meniscal allografts may be a better biomechanical, geometric, and material alternative for acetabular labrum reconstruction (ALR).

Hypothesis

Patients undergoing open ALR using fresh meniscus allograft transplants (MAT) will have better outcomes than those using fresh-frozen tendon allografts transplants (TAT) when comparing initial treatment success, diagnostic imaging assessments, and patient-reported pain and function scores.

Study design

Cohort Study.

Methods

With IRB approval, patients undergoing ALR with either TAT or MAT were included when initial (>1-year) outcomes data related to treatment success, pain, and function were available. In addition, a subcohort of patients underwent magnetic resonance imaging at least 6-months after surgery to evaluate allograft healing.

Results

Initial success rate, defined as no need for ALR revision or conversion to total hip arthroplasty (THA), was 88.9% for the entire group (n = 27, TAT = 5, MAT = 22) with 1 (20%) patient in the TAT cohort and 2 patients (9.9%) in the MAT cohort undergoing THA. In the MAT cohort, significant improvements were documented for physical function and pain scores at 1 year and final follow-up (FFU)(mean 26.8 months). Improvements in pain and function were noted at 1-year, but not at FFU (mean 59.6 months) in the TAT group. MRIs completed at least 6 months after labrum reconstruction showed improved allograft integrity and integration in the MAT cohort over the TAT cohort.

Conclusion

For acetabular labrum reconstructions, MAT was associated with a higher initial success rate, superior patient reported outcomes, and subjectively better MRI findings when compared to TAT.

Fresh Versus Frozen Meniscal Allograft Transplant: Revisit or Redundant? A Systematic Review

BACKGROUND

Fresh-frozen allografts are the current standard in meniscal allograft transplant (MAT) surgery, due to their availability, ease of preservation, and affordability. However, fresh-frozen grafts are associated with several clinical challenges such as graft shrinkage and extrusion, among many others.

PURPOSE

To present the current knowledge on the use of fresh meniscal allografts, presenting whether benefits associated with fresh grafts provide sufficient evidence to support their use in clinical practice.

STUDY DESIGN

Systematic review; Level of evidence, 5.

METHODS

A comprehensive search was conducted with keywords listed below. After an initial screening on title and abstract, full-text articles were assessed with the inclusion criteria.

RESULTS

A total of 78 studies matched the inclusion criteria. Literature and preclinical studies indicated that fresh meniscal allografts are beneficial for maintaining mechanical properties, graft ultrastructure, and matrix metabolism due to the presence of viable cells. Therefore, fresh allografts may address common complications associated with fresh-frozen MAT. To overcome challenges associated with both fresh-frozen and fresh allografts, a group has studied treating fresh-frozen allografts with a cell-based injection therapy.

CONCLUSION

Fresh meniscal allografts pose several challenges including limited availability, demanding preservation procedures, and high costs. Although the role of viable cells within meniscal allografts remains controversial, these cells may be vital for maintaining tissue properties.

Meniscus Allograft Transplantation With Bone Plugs Using Knotless All-Suture Anchors and Cortical Button Suspensory Fixation

Meniscus allograft transplantation can be successful for treatment of meniscal deficiency using a number of transplant techniques. In this Technical Note, we describe a double bone plug medial meniscus allograft transplantation technique that uses knotless all-suture anchors with cortical-button suspensory fixation. This technique maintains the reported advantages for bone-plug fixation while mitigating the risk for meniscal root damage, facilitating easier bone plug insertion and seating, expanding tensioning capabilities, and preventing soft-tissue irritation from suture knot stacks.

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

INTRODUCTION

The meniscotibial ligament (MTL) limits extrusion of the medial meniscus (MM). While meniscal extrusion may be detrimental to knee joint biomechanics, the role of the MTL in meniscal extrusion is debatable. We sought to perform a systematic review and meta-analysis to evaluate the role of the MTL and surgical techniques for MTL repair.

MATERIALS AND METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines we searched PubMed, Cochrane Library, and Embase for: (("Meniscotibial") OR ("Coronary") OR ("Ramp")) AND ("Extrusion"). After screening and applying eligibility criteria, data were extracted for MTL pathology types ("traumatic" ruptures or "induced" injuries) and meniscal extrusion. A meta-analysis evaluated the mean difference of extrusion between "intact" MTLs (native or repaired) and "injured" MTLs (induced or traumatic). We further performed a subgroup analysis between traumatic and induced MTL lesions.

RESULTS

This systematic review included six studies, which all evaluated MM extrusion. There were 74 knees with induced MTL injuries and 19 knees with traumatic MTL ruptures. Study designs were heterogenic and utilized three types of MTL repair procedures. The meta-analysis included 18 human knees and revealed that sectioning the MTL created a 2.92 mm [- 0.18 to 6.03] MM extrusion, while MTL repair decreased MM extrusion by - 2.11 mm [- 3.03 to - 1.21].

CONCLUSIONS

MTL injury may result in approximately 3 mm of MM extrusion, while repair of the MTL can decrease extrusion by 2 mm. Several novel surgical techniques exist to repair the MTL. However, studies reporting clinical outcomes of these various procedures are scarce.

Serial ultrasonographic imaging can predict failure after meniscus allograft transplantation

Introduction

Treatment monitoring after meniscus allograft transplantation (MAT) is challenging. Ultrasonographic (US) imaging has been proposed as a modality that may allow for treatment monitoring after MAT, but has yet to be clinically validated for this purpose. The objective of this study was to assess the capabilities for serial US imaging during the first year after surgery to predict short-term MAT failure.

Methods

Patients who had undergone Meniscus-only or Meniscus-Tibia MAT for treatment of medial or lateral meniscus deficiency were prospectively evaluated by US imaging at various time points after transplantation. Each meniscus was evaluated for abnormalities in echogenicity, shape, associated effusion, extrusion and extrusion with weightbearing (WB).

Results

Data from 31 patients with a mean follow-up of 32 ± 16 (range, 12-55) months were analysed. MAT failure occurred in 6 patients (19.4%) at a median time point of 20 (range, 14-28) months with 4 (12.9%) converted to total knee arthroplasty. US imaging was effective for assessing MAT extrusion and imaging with WB demonstrated dynamic changes in MAT extrusion. US characteristics that were significantly associated with higher likelihood for MAT failure included abnormal echogenicity, localised effusion, extrusion with WB at 6 months, and localised effusion and extrusion with WB at 1 year.

Conclusions

US assessments of meniscus allografts at 6 months after transplantation can effectively determine risk for short-term failure. Abnormal meniscus echogenicity, persistent localised effusion and extrusion with weightbearing were associated with 8-15 times higher odds for failure, which occurred at a median of 20 months post-transplantation.

Initial Outcomes After Unicompartmental Tibiofemoral Bipolar Osteochondral and Meniscal Allograft Transplantation in the Knee Using MOPS-Preserved Fresh (Viable) Tissues

BACKGROUND

Unicompartmental tibiofemoral bipolar osteochondral allograft transplantation (OCAT) with meniscal allograft transplantation (MAT) has not historically been associated with consistently successful outcomes for treatment of knee articular cartilage defects with meniscal deficiency.

HYPOTHESIS

Primary OCAT and MAT using fresh tissues will be associated with successful short-term outcomes based on statistically significant and clinically meaningful improvements in pain and function in the majority of patients.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients were prospectively enrolled into a registry for outcomes after OCAT and MAT. Patients included those who underwent primary OCAT and MAT using Missouri Osteochondral Preservation System (MOPS)-preserved allografts for treatment of large bipolar tibiofemoral articular cartilage defects with meniscal deficiency and had a minimum of 2-year follow-up data.

RESULTS

A total of 76 patients (n = 52 male; 68%) met inclusion criteria (mean follow-up, 52 months). The mean age was 41.1 years (range, 15-69 years), and the mean body mass index was 28.9 (range, 17-46); 48 patients underwent another OCAT in addition to the unicompartmental bipolar tibiofemoral OCAT and MAT; 23 patients (30.3%) were documented to be nonadherent to the prescribed postoperative restriction and rehabilitation protocol. The initial success rate (>2 years) was 77.6%, with 8 patients (10.5%) undergoing revision and 9 (11.8%) converting to arthroplasty. Variables associated with an increased risk for treatment failure (revision or arthroplasty) included ipsilateral osteotomy (P = .046; odds ratio [OR] = 3.3), ipsilateral concurrent procedure (P = .0057; OR = 5.5), and nonadherence (P = .0009; OR = 7.2). None of the patients undergoing revision surgery required arthroplasty at the time of data analysis such that the overall success rate for primary and revision unicompartmental bipolar OCA plus MAT was 88.2%. There were statistically significant (P < .0001) and clinically important improvements for all patient-reported outcomes at each annual follow-up time point.

CONCLUSION

Unicompartmental tibiofemoral bipolar OCAT and MAT can result in successful short-term outcomes (2-6 years) and satisfaction in the majority of patients (78%). Primary MOPS-preserved OCAT with MAT for treatment of femoral condyle and tibial plateau articular cartilage defects with concurrent meniscal deficiency was associated with statistically significant and clinically meaningful improvements in patient-reported measures of pain and function.

Treatment-Monitoring Capabilities of Serum and Urine Biomarkers for Meniscal Allograft Transplantation in a Preclinical Canine Model

BACKGROUND

Meniscal allograft transplantation (MAT) has been developed as a treatment for meniscal deficiency. Despite promising outcomes, there are no real-time methods to evaluate graft survivorship and predict functional outcomes.

HYPOTHESIS

Assessment of serum and urine biomarkers could be used to develop biomarker panels-prognostic (1- and 3-month postsurgical time points) and diagnostic (6-month time point)-based on strong associations with clinically relevant outcome metrics obtained 6 months after surgery.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twelve adult purpose-bred research hounds were included and underwent medial meniscal release to induce meniscal deficiency. Three months after meniscal release surgery, medial menisci were replaced with fresh-frozen meniscus (n = 4), fresh meniscus (n = 4), or fresh meniscotibial osteochondral allograft (n = 4) such that a spectrum of pain and functional outcomes could be anticipated. Serum and urine from all dogs were collected preoperatively and at 1, 3, and 6 months after MAT surgery. Dogs were assessed for pain-related and functional outcomes at the same time points. To develop a prognostic panel of biomarkers, biomarker data from the 1- and 3-month post-MAT surgery time points were used to model 6-month clinical outcomes. A diagnostic panel of biomarkers was developed using data from the 6-month post-MAT surgery to model 6-month clinical outcomes. Primary outcomes for pain and function were visual analog scale (VAS) and operated limb percentage total pressure index (%TPI), respectively. Using random subject effects, linear mixed models were used to develop prognostic biomarker panels, and linear fixed-effect models were used to develop diagnostic biomarker panels, with variance explained for each panel reported (R²) along with individual biomarker relationships.

RESULTS

Across prognostic biomarker panels, a panel including serum IL-6, IL-8, IL-10, and IL-18 was fit for the primary functional outcome, operated limb %TPI (R² = 0.450), whereas a panel including serum CTX-II and OPG was fit for the primary pain-related outcome, VAS (R² = 0.516). Across diagnostic biomarker panels, a panel including serum MMP-1 and MMP-3 and urine PINP and TIMP-1 was fit for %TPI (R² = 0.863). Separately, a panel including urine CTX-I, CTX-II, IL-8, MMP-2, and TIMP-1 was fit as diagnostic biomarkers for the VAS for pain (R² = 0.438).

CONCLUSION

Biomarker panels of selected serum and/or urine proteins can model clinically relevant metrics for function and pain in a preclinical model of MAT.

CLINICAL RELEVANCE

Biomarker panels could be used to provide real-time diagnostic and prognostic data regarding outcomes after MAT.

Biologic Joint Restoration: A Translational Research Success Story

Treatment options that result in consistently successful outcomes for young and active patients with joint disorders are needed. This article summarizes two decades of rigorous research using a bedside-to-bench- to-bedside translational approach based on the One Health - One Medicine concept that culminated in successful clinical use of biologic joint restoration options for treatment of knee, hip, ankle, and shoulder problems in this growing patient population.

Outcomes Associated With Osteochondral Allograft Transplantation in Dogs

The purpose of this study was to retrospectively characterize outcomes and complications associated with osteochondral allograft transplantation for treating chondral and osteochondral lesions in a group of client-owned dogs with naturally-occurring disease. Records were reviewed for information on signalment, treated joint, underlying pathology (e.g., osteochondritis dissecans; OCD), and type, size, and number of grafts used. Complications were classified as “trivial” if no treatment was provided, “non-surgical” if non-surgical treatment were needed, “minor surgical” if a minor surgical procedure such as pin removal were needed but the graft survived and function was acceptable, or “major” if the graft failed and revision surgery were needed. Outcomes were classified as unacceptable, acceptable, or full function. Thirty-five joints in 33 dogs were treated including nine stifles with lateral femoral condyle (LFC) OCD and 10 stifles with medial femoral condyle (MFC) OCD treated with osteochondral cylinders or “plugs.” There were 16 “complex” procedures of the shoulder, elbow, hip, stifle, and tarsus using custom-cut grafts. In total there were eight trivial complications, one non-surgical complication, two minor surgical complications, and five major complications for a total of 16/35 cases with complications. Accordingly, there were five cases with unacceptable outcomes, all of whom had major complications while the other 30 cases had successful outcomes. Of the 30 cases with successful outcomes, 15 had full function and 15 had acceptable function. Based on these subjective outcome assessments, it appears osteochondral allograft transplantation is a viable treatment option in dogs with focal or complex cartilage defects. However, no conclusions can be made regarding the inferiority or superiority of allograft transplantation in comparison to other treatment options based upon these data.

Post-Traumatic Osteoarthritis Assessment in Emerging and Advanced Pre-Clinical Meniscus Repair Strategies: A Review

Surgical repair of meniscus injury is intended to help alleviate pain, prevent further exacerbation of the injury, restore normal knee function, and inhibit the accelerated development of post-traumatic osteoarthritis (PTOA). Meniscus injuries that are treated poorly or left untreated are reported to significantly increase the risk of PTOA in patients. Current surgical approaches for the treatment of meniscus injuries do not eliminate the risk of accelerated PTOA development. Through recent efforts by scientists to develop innovative and more effective meniscus repair strategies, the use of biologics, allografts, and scaffolds have come into the forefront in pre-clinical investigations. However, gauging the extent to which these (and other) approaches inhibit the development of PTOA in the knee joint is often overlooked, yet an important consideration for determining the overall efficacy of potential treatments. In this review, we catalog recent advancements in pre-clinical therapies for meniscus injuries and discuss the assessment methodologies that are used for gauging the success of these treatments based on their effect on PTOA severity. Methodologies include histopathological evaluation of cartilage, radiographic evaluation of the knee, analysis of knee function, and quantification of OA predictive biomarkers. Lastly, we analyze the prevalence of these methodologies using a systemic PubMed® search for original scientific journal articles published in the last 3-years. We indexed 37 meniscus repair/replacement studies conducted in live animal models. Overall, our findings show that approximately 75% of these studies have performed at least one assessment for PTOA following meniscus injury repair. Out of this, 84% studies have reported an improvement in PTOA resulting from treatment.

Fresh Osteochondral Allograft Transplants in the Knee: Bipolar and Beyond

Knee patients who have sustained chondral and osteochondral lesions suffer from debilitating pain, which can ultimately lead to posttraumatic osteoarthritis and whole-joint disease. Older, nonactive patients are traditionally steered toward total knee arthroplasty (TKA), but younger, active patients are not good candidates for TKA based on implant longevity, complications, morbidity, and risk for revision, such that treatment strategies at restoring missing hyaline cartilage and bone are highly desired for this patient population. Over the past four decades, fresh osteochondral allograft (OCA) transplantation has been developed as a treatment method for large (> 2.5 cm²) focal full-thickness articular cartilage lesions. This article documents our own institutional OCA journey since 2016 through enhanced graft preservation techniques (the Missouri Osteochondral Preservation System, or MOPS), technical improvements in surgical techniques, use of bone marrow aspirate concentrate, bioabsorbable pins and nails, and prescribed and monitored patient-specific rehabilitation protocols. Further follow-up with documentation of long-term outcomes will provide insight for continued optimization for future applications for OCA transplantation, potentially including a broader spectrum of patients appropriate for this treatment. Ongoing translational research is necessary to blaze the trail in further optimizing this treatment option for patients.

Isolation and Characterization of Multipotent Canine Urine-Derived Stem Cells

Current cell-based therapies on musculoskeletal tissue regeneration were mostly determined in rodent models. However, a direct translation of those promising cell-based therapies to humans exists a significant hurdle. For solving this problem, canine has been developed as a new large animal model to bridge the gap from rodents to humans. In this study, we reported the isolation and characterization of urine-derived stem cells (USCs) from mature healthy beagle dogs. The isolated cells showed fibroblast-like morphology and had good clonogenicity and proliferation. Meanwhile, these cells positively expressed multiple markers of MSCs (CD29, CD44, CD90, and CD73), but negatively expressed for hematopoietic antigens (CD11b, CD34, and CD45). Additionally, after induction culturing, the isolated cells can be differentiated into osteogenic, adipogenic, chondrogenic, and tenogenic lineages. The successful isolation and verification of USCs from canine were useful for studying cell-based therapies and developing new treatments for musculoskeletal injuries using the preclinical canine model.