Clinical, histologic, and radiographic outcomes of distal femoral resurfacing with hypothermically stored osteoarticular allografts

Cartilage thickness mismatches in patellar osteochondral allograft transplants affect local cartilage stresses

Osteochondral allograft implantation is a form of cartilage transplant in which a cylindrical graft of cartilage and subchondral bone from a donor is implanted into a patient's prepared articular defect site. No standard exists for matching the cartilage thickness of the donor and recipient. The goal of this study was to use finite element (FE) analysis to identify the effect of cartilage thickness mismatches between donor and recipient cartilage on cartilage stresses in patellar transplants. Two types of FE models were used: patient-specific 3D models and simplified 2D models. 3D models highlighted which geometric features produced high-stress regions in the patellar cartilage and provided ranges for the parameter sweeps that were conducted with 2D models. 2D models revealed that larger thickness mismatches, thicker recipient cartilage, and a donor-to-recipient cartilage thickness ratio (DRCR) < 1 led to higher stresses at the interface between the donor and recipient cartilage. A surface angle between the donor-recipient cartilage interface and cartilage surface normal near the graft boundary increased stresses when DRCR > 1, with the largest increase observed for an angle of 15°. A surface angle decreased stresses when DRCR < 1. Clinical Significance: This study highlights a potential mechanism to explain the high rates of failure of patellar OCAs. Additionally, the relationship between geometric features and stresses explored in this study led to a hypothetical scoring system that indicates which transplanted patellar grafts may have a higher risk of failure.

Osteochondral Allografts in Knee Surgery: Narrative Review of Evidence to Date

Knee articular cartilage defects can result in significant pain and loss of function in active patients. Osteochondral allograft (OCA) transplantation offers a single-stage solution to address large chondral and osteochondral defects by resurfacing focal cartilage defects with mature hyaline cartilage. To date, OCA transplantation of the knee has demonstrated excellent clinical outcomes and long-term survivorship. However, significant variability still exists among clinicians with regard to parameters for graft acceptance, surgical technique, and rehabilitation. Technologies to optimize graft viability during storage, improve osseous integration of the allograft, and shorten recovery timelines after surgery continue to evolve. The purpose of this review is to examine the latest evidence on treatment indications, graft storage and surgical technique, patient outcomes and survivorship, and rehabilitation after surgery.

Rehabilitation Variability Following Osteochondral Autograft and Allograft Transplantation of the Knee

OBJECTIVE

The aim of this study is to assess the variability of postoperative rehabilitation protocols used by orthopedic surgery residency programs for osteochondral autograft transplantation (OAT) and osteochondral allograft transplantation (OCA) of the knee.

DESIGN

Online postoperative OAT and OCA rehabilitation protocols from US orthopedic programs and the scientific literature were reviewed. A custom scoring rubric was developed to analyze each protocol for the presence of discrete rehabilitation modalities and the timing of each intervention.

RESULTS

A total of 16 programs (10.3%) from 155 US academic orthopedic programs published online protocols and a total of 35 protocols were analyzed. Twenty-one protocols (88%) recommended immediate postoperative bracing following OAT and 17 protocols (100%) recommended immediate postoperative bracing following OCA. The average time protocols permitted weight-bearing as tolerated (WBAT) was 5.2 weeks (range = 0-8 weeks) following OAT and 6.2 weeks (range = 0-8 weeks) following OCA. There was considerable variation in the inclusion and timing of strength, proprioception, agility, and pivoting exercises. Following OAT, 2 protocols (8%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks). Following OCA, 1 protocol (6%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks).

CONCLUSION

A minority of US academic orthopedic programs publish OAT and OCA rehabilitation protocols online. Among the protocols currently available, there is significant variability in the inclusion of specific rehabilitation components and timing of many modalities. Evidence-based standardization of elements of postoperative rehabilitation may help improve patient care and subsequent outcomes.

Fresh Osteochondral and Chondral Allograft Preservation and Storage Media: A Systematic Review of the Literature

BACKGROUND

Storage procedures and parameters have a significant influence on the health of fresh osteochondral allograft (OCA) cartilage. To date, there is a lack of agreement on the optimal storage conditions for OCAs.

PURPOSE

To systematically review the literature on (1) experimental designs and reporting of key variables of ex vivo (laboratory) studies, (2) the effects of various storage solutions and conditions on cartilage health ex vivo, and (3) in vivo animal studies and human clinical studies evaluating the effect of fresh OCA storage on osteochondral repair and outcomes.

STUDY DESIGN

Systematic review; Level of evidence, 5.

METHODS

A systematic review was performed using the PubMed, Embase, and Cochrane databases. The inclusion criteria were laboratory studies (ex vivo) reporting cartilage health outcomes after prolonged storage (>3 days) of fresh osteochondral or chondral tissue explants and animal studies (in vivo) reporting outcomes of fresh OCA. The inclusion criteria for clinical studies were studies (>5 patients) that analyzed the relationship of storage time or chondrocyte viability at time of implantation to patient outcomes. Frozen, cryopreserved, decellularized, synthetic, or tissue-engineered grafts were excluded.

RESULTS

A total of 55 peer-reviewed articles met the inclusion criteria. Ex vivo studies reported a spectrum of tissue sources and storage solutions and conditions, although the majority of studies lacked complete reporting of key variables, including storage solution formula and environmental conditions. The effect of various conditions (eg, temperature) and storage solutions on cartilage health were inconsistent. Although 60% of animal models suggest that storage time may influence outcomes and 80% indicate inferior outcomes with frozen OCA as compared with fresh OCA, 75% of clinical studies report no correlation between storage time and outcomes.

CONCLUSION

Given the variability in experimental designs and lack of reporting across studies, it is still not possible to determine optimal storage conditions, although animal studies suggest that storage time and chondrocyte viability influence osteochondral repair outcomes. A list of recommendations was developed to encourage reporting of key variables, such as media formulation, environmental factors, and methodologies used. High-quality clinical data are needed to investigate the effects of storage and graft health on outcomes.

Rehabilitation and Return-to-Play Criteria After Fresh Osteochondral Allograft Transplantation: A Systematic Review

Background:

Fresh osteochondral allograft (OCA) is a treatment option that allows for the transfer of size-matched allograft cartilage and subchondral bone into articular defects of the knee. Although long-term studies show good functional improvement with OCA, there continues to be wide variability and a lack of consensus in terms of postoperative rehabilitation protocols and return to sport.

Purpose:

To systematically review the literature and evaluate the reported rehabilitation protocols after OCA of the knee, including weightbearing and range of motion (ROM) restrictions as well as return-to-play criteria.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

PubMed, EMBASE, Cumulative Index of Nursing Allied Health Literature, SPORTDiscus, and Cochrane databases were searched according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for studies on knee OCA. Studies were included if they reported return-to-play data or postsurgical rehabilitation protocols.

Results:

A total of 62 studies met the inclusion criteria, with a total of 3451 knees in 3355 patients. Concomitant procedures were included in 30 of these studies (48.4%). The most commonly cited rehabilitation protocols included weightbearing restrictions and ROM guidelines in 100% and 90% of studies, respectively. ROM was most commonly initiated within the first postoperative week, with approximately half of studies utilizing continuous passive motion. Progression to weightbearing as tolerated was reported in 60 studies, most commonly at 6 weeks (range, immediately postoperatively to up to 1 year). Of the 62 studies, 37 (59.7%) included an expected timeline for either return to play or return to full activity, most commonly at 6 months (range, 4 months to 1 year). Overall, 13 studies (21.0%) included either objective or subjective criteria to determine return to activity within their rehabilitation protocol.

Conclusion:

There is significant heterogeneity for postoperative rehabilitation guidelines and the return-to-play protocol after OCA of the knee in the literature, as nearly half of the included studies reported use of concomitant procedures. However, current protocols appear to be predominantly time-based without objective criteria or functional assessment. Therefore, the authors recommend the development of objective criteria for patient rehabilitation and return-to-play protocols after OCA of the knee.

Metrics of OsteoChondral Allografts (MOCA) Group Consensus Statements on the Use of Viable Osteochondral Allograft

Background:

Osteochondral allograft (OCA) transplantation has evolved into a first-line treatment for large chondral and osteochondral defects, aided by advancements in storage protocols and a growing body of clinical evidence supporting successful clinical outcomes and long-term survivorship. Despite the body of literature supporting OCAs, there still remains controversy and debate in the surgical application of OCA, especially where high-level evidence is lacking.

Purpose:

To develop consensus among an expert group with extensive clinical and scientific experience in OCA, addressing controversies in the treatment of chondral and osteochondral defects with OCA transplantation.

Study Design:

Consensus statement.

Methods:

A focus group of clinical experts on OCA cartilage restoration participated in a 3-round modified Delphi process to generate a list of statements and establish consensus. Questions and statements were initially developed on specific topics that lack scientific evidence and lead to debate and controversy in the clinical community. In-person discussion occurred where statements were not agreed on after 2 rounds of voting. After final voting, the percentage of agreement and level of consensus were characterized. A systematic literature review was performed, and the level of evidence and grade were established for each statement.

Results:

Seventeen statements spanning surgical technique, graft matching, indications, and rehabilitation reached consensus after the final round of voting. Of the 17 statements that reached consensus, 11 received unanimous (100%) agreement, and 6 received strong (80%-99%) agreement.

Conclusion:

The outcomes of this study led to the establishment of consensus statements that provide guidance on surgical and perioperative management of OCAs. The findings also provided insights on topics requiring more research or high-quality studies to further establish consensus and provide stronger evidence.

Evolution of a Novel Tissue Preservation Protocol to Optimize Osteochondral Transplantation Outcomes

OBJECTIVE

Osteochondral allograft transplantation is a procedure to treat focal osteochondral lesions (OCLs), but is limited by tissue availability, the quality of transplanted tissue, and inconsistent storage protocols. The objective of this study was to assess the clinical outcomes of a novel tissue procurement, storage, and quality control protocol in treating OCLs.

DESIGN

Prospective case series. Donor cadaveric tissue was processed, stored, and the tissue quality analyzed using the unique tissue preservation protocol developed at our institution. Advanced cross-sectional imaging was used to size match donor tissue with recipient patients. Osteochondral allografts were transplanted using the Arthrex Allograft OATS. Patients were evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS), and 36-Item Short Form Survey (SF-36) preoperatively and at 1 year and 2 years postoperatively.

RESULTS

Twenty patients (17 knees, 3 shoulders) were included in the study. There was a significant improvement in the following scores: overall WOMAC score, WOMAC function and pain subcategories; KOOS pain, knee-related symptoms, activities of daily living, sports and recreation, and quality of life; SF-36 physical functioning, physical role, pain, and social functioning subcategories; and VAS at all time points postoperatively. There was a significant improvement in WOMAC stiffness at 2 years postoperatively. There were 2 failures, defined by graft subsidence and persistent pain requiring reoperation.

CONCLUSION

The protocol developed at our institution for OAT resulted in significant clinical improvement in patients with OCLs and is an improvement on existing tissue storage techniques.

Assessment of Cell Viability of Fresh Osteochondral Allografts in N-Acetylcysteine-Enriched Medium

OBJECTIVE

The purpose of this study was to evaluate the effect of N-acetylcysteine (NAC)-enriched storage medium on fresh osteochondral viability at 4°C. Our hypothesis was that the cell viability of chondrocytes obtained from human osteochondral tissue and stored at 4°C significantly improves in the presence of NAC.

DESIGN

Controlled laboratory study. For this study, 8 samples of femoral condyle osteochondral tissue were obtained from patients undergoing total knee replacement. The samples were stored at either 4°C in phosphate-buffered saline (PBS) or at 3 different concentrations of NAC (NAC 1, 2, and 5 mM). Cell viability was analyzed at time 0 and 4 weeks by flow cytometry. The results of cell viability (median) were analyzed statistically using analysis of variance and Tukey's post hoc test. P values <0.05 were considered statistically significant.

RESULTS

The viability at time 0 was 95.5% ± 3.7%. At 4 weeks, the cell viability was 56.8% ± 20.1% in the control group (PBS), 83.8% ± 11.9% in the group stored with NAC 1 mM, 73.4% ± 13.6% in the group stored with NAC 2 mM, and 66.4% ± 27.7% in the group stored with NAC 5 mM. A statistically significant difference from the baseline viability (time 0) was observed in the PBS control group (P = 0.0018) but not in the other groups. A statistically significant difference was observed in the NAC 1 mM group compared with the PBS group (P = 0.0255).

CONCLUSION

The use of NAC at 1 mM concentration improves cell viability after 4 weeks of storage in chondrocytes obtained from human osteochondral tissue.

Comparative Effectiveness of Cartilage Repair With Respect to the Minimal Clinically Important Difference

BACKGROUND

Recent studies demonstrated a 5% increase in cartilage repair procedures annually in the United States. There is currently no consensus regarding a superior technique, nor has there been a comprehensive evaluation of postoperative clinical outcomes with respect to a minimal clinically important difference (MCID).

PURPOSE

To determine the proportion of available cartilage repair studies that meet or exceed MCID values for clinical outcomes improvement over short-, mid-, and long-term follow-up.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review was performed via the Medline, Scopus, and Cochrane Library databases. Available studies were included that investigated clinical outcomes for microfracture (MFX), osteoarticular transfer system (OATS), osteochondral allograft transplantation, and autologous chondrocyte implantation/matrix-induced autologous chondrocyte implantation (ACI/MACI) for the treatment of symptomatic knee chondral defects. Cohorts were combined on the basis of surgical intervention by performing a meta-analysis that utilized inverse-variance weighting in a DerSimonian-Laird random effects model. Weighted mean improvements in International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale for pain (VAS pain) scores were calculated from preoperative to short- (1-4 years), mid- (5-9 years), and long-term (≥10 years) postoperative follow-up. Mean values were compared with established MCID values per 2-tailed 1-sample Student t tests.

RESULTS

A total of 89 studies with 3894 unique patients were analyzed after full-text review. MFX met MCID values for all outcome scores at short- and midterm follow-up with the exception of VAS pain in the midterm. OATS met MCID values for all outcome scores at all available time points; however, long-term data were not available for VAS pain. Osteochondral allograft transplantation met MCID values for IKDC at short- and midterm follow-up and for Lysholm at short-term follow-up, although data were not available for other time points or for VAS pain. ACI/MACI met MCID values for all outcome scores (IKDC, Lysholm, and VAS pain) at all time points.

CONCLUSION

In the age of informed consent, it is important to critically evaluate the clinical outcomes and durability of cartilage surgery with respect to well-established standards of clinical improvement. MFX failed to maintain VAS pain improvements above MCID thresholds with follow-up from 5 to 9 years. All cartilage repair procedures met MCID values at short- and midterm follow-up for IKDC and Lysholm scores; ACI/MACI and OATS additionally met MCID values in the long term, demonstrating extended maintenance of clinical benefits for patients undergoing these surgical interventions as compared with MFX.

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.

Decreased Graft Thickness Is Associated With Subchondral Cyst Formation After Osteochondral Allograft Transplantation in the Knee

BACKGROUND

Subchondral changes, specifically cyst formation, are a known finding after osteochondral allograft (OCA) transplantation.

PURPOSE/HYPOTHESIS

The purpose was to determine potential predictive associations between preoperative patient characteristics or OCA morphology and postoperative OCA appearance as assessed by the osteochondral allograft magnetic resonance imaging scoring system (OCAMRISS) at 6-month follow-up. It was hypothesized that preoperative patient factors or OCA morphology is associated with postoperative OCAMRISS scores.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This study evaluated 74 OCAs that were implanted in the femoral condyles of 63 patients for the treatment of symptomatic osteochondral defects in the knee. Postoperative magnetic resonance imaging was obtained at a mean ± SD follow-up of 5.5 ± 1.0 months. A musculoskeletal radiologist scored all grafts according to the OCAMRISS. Point biserial correlation, Mann-Whitney U test, Fisher exact test, and chi-square test were used to distinguish associations between OCAMRISS subscales and age, sex, smoker status, body mass index, previous surgery, concomitant surgery, bone marrow augmentation, graft location, graft size, and bony graft thickness.

RESULTS

OCA bony thickness showed significant correlation with cystic changes at the graft-host junction (P = .019). Grafts with cystic formation were significantly thinner than grafts without cystic changes (P = .008). The odds ratio for grafts with <5-mm bony thickness demonstrating cystic changes was 4.9 (95% CI, 1.5-16.1; P = .009). Bony graft thickness was not associated with graft integration, but 40% of grafts with a bony thickness >9 mm presented with a residual osseous cleft, as opposed to 11.3% of thinner grafts (P = .1). The augmentation with bone marrow aspirate did not affect osseous graft integration or subchondral cystic formation (P = .375 and P = .458, respectively).

CONCLUSION

Osteochondral allograft thickness is associated with subchondral cyst formation at short-term follow-up. Thin grafts demonstrate a substantially increased risk of developing subchondral cysts at the graft-host junction after OCA transplantation. Conversely, thicker grafts may negatively affect osseous graft integration. Hence, surgeons should be aware of the potential pitfalls of transplanting thin or thick grafts regarding cystic formation and delay of osseous integration after cartilage resurfacing.

The Clinical Evidence Behind Biologic Therapies Promoted at Annual Orthopaedic Meetings: A Systematic Review

PURPOSE

The purpose of this study is to systematically evaluate the available clinical data for biologic therapies promoted for articular cartilage defects and osteoarthritis of the knee at the 2016 American Orthopaedic Society for Sports Medicine Meeting (AOSSM) and the 2017 Arthroscopy Association of North America meeting (AANA).

METHODS

Our sample included all exhibitors at the 2016 AOSSM meeting and 2017 AANA meeting. All biologic products marketed at each conference were identified by reviewing exhibition booths and company websites. A systematic review of the clinical data on each product was then completed using PubMed, EMBASE, and the product's own webpage. All clinical peer-reviewed studies with level I-IV evidence were included in the study. Basic science or preclinical studies were excluded.

RESULTS

There were 16 products promoted for biologic therapy for articular cartilage defects or osteoarthritis of the knee at the AOSSM meeting and 11 products promoted at the AANA meeting. A total of 280 articles detailed clinical findings for the articular cartilage products displayed at AOSSM and AANA. Of the 280, there were 36 level I evidence studies, 37 level II evidence studies, 18 level III evidence studies, and 189 level IV evidence studies. Of these articles, 91% were for 4 products. Of all biologic products promoted at the 2 meetings, 65% did not have any peer-reviewed clinical data supporting their use.

CONCLUSION

Overall, many biologic therapies promoted at leading arthroscopy and sports medicine conferences did not have clinical evidence evaluating their use in the peer-reviewed literature. Although scientific advancement requires new technology, orthopaedic surgeons should be cautious about using biologic therapies in their practice with no proven efficacy. There are likely promising new interventions that, with additional scientific research, will be proven efficacious for our patients.

CLINICAL RELEVANCE

This article gives orthopaedic surgeons a detailed example of some of the biologic treatments being offered on the market for the treatment of knee articular cartilage disease. When patients request these treatments, physicians must be able to explain the data supporting their use.

Clinical Outcomes and Failure Rates of Osteochondral Allograft Transplantation in the Knee: A Systematic Review

BACKGROUND

Cartilage lesions are a significant cause of morbidity and impaired knee function; however, cartilage repair procedures have failed to reproduce native cartilage to date. Thus, osteochondral allograft (OCA) transplantation represents a 1-step procedure to repair large chondral defects without the donor site morbidity of osteochondral autograft transplantation.

PURPOSE

To perform a systematic review of clinical outcomes and failure rates after OCA transplantation in the knee at a minimum mean 2 years' follow-up.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of the literature regarding the existing evidence for clinical outcomes and failure rates of OCA transplantation in the knee joint was performed using the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, and MEDLINE from studies published between 1980 and 2017. Inclusion criteria were as follows: clinical outcomes and failure rates of OCAs for the treatment of chondral defects in the knee joint, English language, mean follow-up of 2 years and minimum follow-up of 18 months, minimum study size of 20 patients, and human studies. The methodological quality of each study was assessed using a modified version of the Coleman methodology score.

RESULTS

The systematic search identified 19 studies with a total of 1036 patients. The mean 5-year survival rate across the studies included in this review was 86.7% (range, 64.1%-100.0%), while the mean 10-year survival rate was 78.7% (range, 39.0%-93.0%). The mean survival rate was 72.8% at 15 years (range, 55.8%-84.0%) and 67.5% at 20 years (range, 66.0%-69.0%). The weighted mean patient age was 31.5 years (range, 10-82 years), and the weighted mean follow-up was 8.7 years (range, 2-32 years). The following outcome measures showed significant improvement from preoperatively to postoperatively: d'Aubigné-Postel, International Knee Documentation Committee, Knee Society function, and Lysholm scores. The weighted mean reoperation rate was 30.2% (range, 0%-63%). The weighted mean failure rate was 18.2% (range, 0%-31%). Of note, revision cases, patellar lesions, and bipolar lesions demonstrated worse survival rates.

CONCLUSION

Improved patient-reported outcomes can be expected after OCA transplantation, with a survival rate of 78.7% at 10 years. Revision cases, patellar lesions, and bipolar lesions were associated with worse survival rates; therefore, utilization of the most appropriate index cartilage restoration procedure and proper patient selection are key to improving results.

Preservation of Knee Articular Cartilage

Hyaline articular cartilage is critical for the normal functioning of the knee joint. Untreated focal cartilage defects have the potential to rapidly progress to diffuse osteoarthritis. Over the last several decades, a variety of interventions aiming at preserving articular cartilage and preventing osteoarthritis have been investigated. Reparative cartilage procedures, such as microfracture, penetrate the subchondral bone plate in effort to fill focal cartilage defects with marrow elements and stimulate fibrocartilaginous repair. In contrast, restorative cartilage procedures aim to replace the defective articular surface with autologous or allogeneic hyaline cartilage. This review focuses on the preservation of articular cartilage, and discusses the current reparative and restorative surgical techniques available for treating focal cartilage defects.

Effects of Proud Large Osteochondral Plugs on Contact Forces and Knee Kinematics: A Robotic Study

BACKGROUND

Osteochondral allograft (OCA) transplantation is used to treat large focal femoral condylar articular cartilage defects. A proud plug could affect graft survival by altering contact forces (CFs) and knee kinematics.

HYPOTHESIS

A proud OCA plug will significantly increase CF and significantly alter knee kinematics throughout controlled knee flexion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human cadaver knees had miniature load cells, each with a 20-mm-diameter cylinder of native bone/cartilage attached at its exact anatomic position, installed in both femoral condyles at standardized locations representative of clinical defects. Spacers were inserted to create proud plug conditions of +0.5, +1.0, and +1.5 mm. CFs and knee kinematics were recorded as a robot flexed the knee continuously from 0° to 50° under 1000 N of tibiofemoral compression.

RESULTS

CFs were increased significantly (vs flush) for all proudness conditions between 0° and 45° of flexion (medial) and 0° to 50° of flexion (lateral). At 20°, the average increases in medial CF for +0.5-mm, +1-mm, and +1.5-mm proudness were +80 N (+36%), +155 N (+70%), and +193 N (+87%), respectively. Corresponding increases with proud lateral plugs were +44 N (+14%), +90 N (+29%), and +118 N (+38%). CF increases for medial plugs at 20° of flexion were significantly greater than those for lateral plugs at all proudness conditions. At 50°, a 1-mm proud lateral plug significantly decreased internal tibial rotation by 15.4° and decreased valgus rotation by 2.5°.

CONCLUSION

A proud medial or lateral plug significantly increased CF between 0° and 45° of flexion. Our results suggest that a medial plug at 20° may be more sensitive to graft incongruity than a lateral plug. The changes in rotational kinematics with proud lateral plugs were attributed to earlier contact between the proud plug's surface and the lateral meniscus, leading to rim impingement with decreased tibial rotation.

CLINICAL RELEVANCE

Increased CF and altered knee kinematics from a proud femoral plug could affect graft viability. Plug proudness of only 0.5 mm produced significant changes in CF and knee kinematics, and the clinically accepted 1-mm tolerance may need to be reexamined in view of our findings.

Effect of Bisphosphonate Pretreatment on Fresh Osteochondral Allografts: Analysis of In Vitro Graft Structure and In Vivo Osseous Incorporation

Fresh allograft transplantation of osteochondral defects restores functional articular cartilage and subchondral bone; however, rapid loss of chondrocyte viability during storage and osteoclast-mediated bone resorption at the graft-host interface after transplantation negatively impact outcomes. The authors present a pilot study evaluating the in vitro and in vivo impact of augmenting storage media with bisphosphonates. Forty cylindrical osteochondral cores were harvested from femoral condyles of human cadaveric specimens and immersed in either standard storage media or storage media supplemented with nitrogenated or non-nitrogenated bisphosphonates. Maintenance of graft structure and chondrocyte viability were assessed at 3 time points. A miniature swine trochlear defect model was used to evaluate the influence of bisphosphonate-augmented storage media on in vivo incorporation of fresh osteochondral tissue, which was quantified via μCT and decalcified histology. In the in vitro study, Safranin-O/Fast Green staining showed that both low- and high-dose nitrogenated-treated grafts retained chondrocyte viability and cartilage matrix for up to 43 days of storage. Allografts stored in nitrogenated-augmented storage media showed both μCT and histologic evidence of enhanced in vivo bony and cartilaginous incorporation in the miniature swine trochlear defect model. Several preclinical studies have shown the potential for enhanced storage of fresh osteochondral allografts via additions of relatively common drugs and biomolecules. This study showed that supplementing standard storage media with nitrogenated bisphosphonates may improve maintenance of chondrocyte viability and graft structure during cold storage as well as enhance in vivo osseous and cartilaginous incorporation of the graft. [Orthopedics: 2018; 41(3):e376-e382.].

Large Osteochondral Allografts of the Knee: Surgical Technique and Indications

Large osteochondral allograft (OCA) transplant has become a valid alternative to restore articular surface in challenging articular lesions in young and active patients, either in primary or in revision procedures. Several studies support the effectiveness and safety of OCA, but costs and graft availability limit their use. The indications are the treatment of symptomatic full-thickness cartilage lesions greater than 3 cm ² , deep lesions with subchondral damage, or revision procedures when a previous treatment has failed. The goal of the transplant is to restore the articular surface with a biological implant, allow return to daily/sports activities, relieve symptoms, and delay knee arthroplasty. Grafts can be fresh, fresh-frozen, or cryopreserved; these different storage procedures significantly affect cell viability, immunogenicity, and duration of the storage. Dowel and shell technique are the two most commonly used procedures for OCA transplantation. While most cartilage lesions can be treated with the dowel technique, large and/or geometrically irregular lesions should be treated with the shell technique. OCA transplantation for the knee has demonstrated reliable mid- to long-term results in terms of graft survival and patient satisfaction. Best results are reported: in unipolar lesions, in patients younger than 30 years, in traumatic lesions and when the treatment is performed within 12 months from the onset of symptoms.

Effects of Autogenous Bone Marrow Aspirate Concentrate on Radiographic Integration of Femoral Condylar Osteochondral Allografts

BACKGROUND

Transplantation of fresh osteochondral allografts (OCAs) is an attractive treatment option for symptomatic articular cartilage lesions in young, healthy patients. Because the lack of OCA bone integration can be a cause of treatment failure, methods for speeding and enhancing OCA bone integration to mitigate this potential complication are highly desirable.

PURPOSE

To determine if autogenous bone marrow aspirate concentrate (BMC) treatment of large femoral condylar OCAs would be associated with superior radiographic OCA bone integration compared with nontreated allografts during the critical first 6 months after surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A review of patients enrolled in a prospective registry who were treated with transplantation of large OCAs to one or both femoral condyles at our institution from March 12, 2013 to March 14, 2016 was performed. Patients were stratified into 2 groups based on BMC treatment versus no BMC treatment; the treatment was nonrandomized and was rooted in a shift in practice and a continuing effort to optimize OCA transplantation at our institution. Patients were excluded if they did not have orthogonal view radiographs performed at 6 weeks, 3 months, and 6 months postoperatively. Each condyle undergoing OCA transplantation was assessed individually by an independent musculoskeletal radiologist, who was blinded to the treatment group and time point. OCAs were assessed with respect to graft integration (0%-100%; 0 = no integration, 100 = complete integration) and degree of sclerosis (0-3; 0 = normal, 1 = mild sclerosis, 2 = moderate sclerosis, and 3 = severe sclerosis) of the graft at each time point.

RESULTS

This study identified 17 condyles in 15 patients who underwent OCA transplantation without BMC and 29 condyles in 22 patients who underwent OCA transplantation with BMC. The BMC group had significantly ( P = .033) higher graft integration scores at 6 weeks, 3 months, and 6 months after surgery. Graft sclerosis was significantly ( P = .017) less in the BMC group at 6 weeks and 3 months, with no significant difference at 6 months after surgery. When combining the groups to examine the influence of smoking on graft integration, nonsmokers had significantly ( P = .007) higher graft integration scores at 6 months.

CONCLUSION

Large femoral condylar OCAs treated with autogenous BMC before implantation showed superior radiographic integration to bone and less sclerosis during the initial 6-month postoperative period. BMC treatment of OCAs may mitigate the failure of OCA bone healing.

Use of Particulated Juvenile Articular Cartilage Allograft for Osteochondral Lesions of the Wrist

BACKGROUND

Articular cartilage injuries are a common injury among young, active patients, and the most appropriate treatment for these injuries remains controversial. A promising new technology in the treatment of high-grade cartilage injuries is particulated juvenile articular cartilage (PJAC) allograft (DeNovo NT, Zimmer, Warsaw, Indiana). This has been shown to be successful in multiple joints including the knee, talus, and elbow. No studies or case reports exist in supporting or discouraging its use in injuries of the wrist, in specific, the scaphoid.

METHODS

The use of PJAC allograft is described for the treatment of an active 21-year-old male with an Outerbridge Grade IV chondral lesion on the proximal pole of his right scaphoid and right distal radius scaphoid facet who had failed conservative management. The patient was followed clinically and radiographically for 21 months.

RESULTS

The patient had return to full sport (jujutsu) and full range-of-motion, both of which represented an improvement from his preoperative exam. Radiographically, the chondral lucency seen had decreased in size and was almost completely absent on radiographs after 21 months.

CONCLUSIONS

The results of this case suggest that PJAC can be used safely and effectively in the wrist thereby potentially broadening the indications for its use.

Rehabilitation and Postoperative Management Practices After Osteochondral Allograft Transplants to the Distal Femur: A Report From the Metrics of Osteochondral Allografts (MOCA) Study Group 2016 Survey

Context:

We present the current spectrum of postoperative management practices for patients receiving distal femur osteochondral allograft (OCA) transplants.

Evidence Acquisition:

The Joint Restoration Foundation database was examined in cooperation with the Metrics of Osteochondral Allografts study group to identify 121 surgeons who had performed at least 1 OCA transplant in the past year; 63% of surgeons responded.

Study Design:

Clinical survey.

Level of Evidence:

Level 3.

Results:

Postoperative weightbearing restrictions ranged from immediate nonweightbearing with full weightbearing by 12 weeks to immediate weightbearing as tolerated. Most surgeons who performed fewer (<10) OCA transplants per year followed the most restrictive protocol, while surgeons who performed more (>20) OCA transplants per year followed the least restrictive protocol. One-third of surgeons with the most restrictive protocol were more likely to change their protocol to be less restrictive over time, while none of those with the least restrictive protocol changed their protocol over time. Fifty-five percent of surgeons permitted return to full activity at 26 weeks, while 27% of surgeons lifted restrictions at 16 weeks.

Conclusion:

Characterization of the spectrum of postoperative management practices after OCA transplantation provides a foundation for future investigations regarding patient outcomes and associated cost to establish best practice guidelines. Fundamentally, surgeons with more experience with this procedure tended to be more aggressive with their postoperative rehabilitation guidelines. Most commonly, rehabilitation provided for some degree of limited weightbearing; however, the spectrum also included immediate full weightbearing practices.

Fresh osteochondral allotransplants: Outcomes, failures and future developments

Osteochondral allografts are used to treat many different conditions as acute traumatic large-sized lesions, degenerative osteoarthritis, osteochondritis dissecans, avascular necrosis or in case of failure of previous procedures particularly in young patients for whom primary prosthesis is not desirable. Fresh allografts present the advantage of having mature viable hyaline cartilage, not causing donor morbidity, allowing the restoration of even large defects in a single surgical session. Conversely, they could account for risks of disease transmission, immunologic reactions, and for limited availability. The present review aimed to analyze published studies of the last decade in which patients received fresh osteochondral allografts by dividing them for knee or ankle regenerative purposes. We wish to report the observed failure rates and particularly to collect any other reported side effect or outcome for identifying major problems and limits linked to the procedure and for delineating possible future researches and approaches. The overall success rates resulted ranging from 5.3% to 48.3% in the ankle at a mean follow up of 3.3 years and from 0% to 85.7% in the knee at a mean follow up of 7.1 years. Among other outcomes, occurrence or progression of arthritis, osteolysis, graft instability, fractures, nonunions, edema and infections were recorded. Overall, the lack of well designed randomized and controlled clinical trials, of immunological determination of the anti-donor antibodies development and of local and systemic biomarkers to detect reaction to the graft seems to be the major drawback. Improvements in these limiting factors might be desirable in order to enhance the clinical scenario of a well-established and successful procedure to give, especially for young patients, a real regeneration of the joint.

Fresh Osteochondral Allograft Transplantation for Fractures of the Knee

Objective The purpose of this study was to evaluate functional outcomes and allograft survivorship among patients with knee fracture who underwent fresh osteochondral allograft (OCA) transplantation as a salvage treatment option. Design Retrospective analysis of prospectively collected data. Setting Department of Orthopaedic Surgery at one hospital. Patients Fresh OCAs were implanted for osteochondral lesions after knee fracture in 24 males and 15 females with an average age of 34 years. Twenty-nine lesions (74%) were tibial plateau fractures, 6 (15%) were femoral condyle fractures, and 4 (10%) were patella fractures. Main Outcome Measurements Clinical evaluation included modified Merle d'Aubigné-Postel (18-point), International Knee Documentation Committee, and Knee Society function scores, and patient satisfaction. Failure of OCA was defined as revision OCA or conversion to total knee arthroplasty (TKA). Results Nineteen of 39 knees (49%) had further surgery. Ten knees (26%) were considered OCA failures (3 OCA revisions, 6 TKA, and 1 patellectomy). Survivorship of the OCA was 82.6% at 5 years and 69.6% at 10 years. Among the 29 knees (74%) that had the OCA still in situ, median follow-up was 6.6 years. Pain and function improved from preoperative to latest follow-up; 83% of patients reported satisfaction with OCA results. Conclusion OCA transplantation is a useful salvage treatment option for osteochondral lesions caused by knee fracture. Although the reoperation rate was high, successful outcome was associated with significant clinical improvement.

Osteochondral allograft

Over the past decade, osteochondral allograft transplantation has soared in popularity. Advances in storage techniques have demonstrated improved chondrocyte viability at longer intervals and allowed for potential of increased graft availability. Recent studies have stratified outcomes according to location and etiology of the chondral or osteochondral defect. Unipolar lesions generally have favorable outcomes with promising 10-year survival rates. Though those undergoing osteochondral allograft transplantation often require reoperation, patient satisfaction remains high.

UPDATING ON DIAGNOSIS AND TREATMENT OF CHONDRAL LESION OF THE KNEE

The treatment of chondral knee injuries remains a challenge for the orthopedic surgeon, mainly owing to the characteristics of the cartilage tissue, which promote low potential for regeneration. Chondral lesions can be caused by metabolic stimulation, or by genetic, vascular and traumatic events, and are classified according to the size and thickness of the affected cartilage. Clinical diagnosis can be difficult, especially due to insidious symptoms. Additional tests, as Magnetic Resonance Imaging (MRI), may be needed. The treatment of these lesions usually starts with non-operative management. Surgery should be reserved for patients with detached chondral fragments, blocked range of motion, or the failure of non-operative treatment. The surgical techniques used for the treatment of partial thickness defects are Debridement and Ablation. These techniques aim to improve symptoms, since they do not restore normal structure and function of the cartilage. For full-thickness defects (osteochondral lesion), available treatments are Abrasion, Drilling, Microfracture, Osteochondral Autologous and Allogeneic Transplantation, and biological techniques such as the use of Autologous Chondrocyte Transplantation, Minced Cartilage and stem cells.

Why Do Osteochondral Allografts Survive? Comparative Analysis of Cartilage Biochemical Properties Unveils a Molecular Basis for Durability

BACKGROUND

Transplantation of osteochondral allografts (OCAs) freshly preserved for ≥30 days has proven to be a reliable technique for cartilage resurfacing. However, the prolonged storage of allografts comes at the expense of chondrocyte viability, which declines precipitously after 14 days under refrigeration. Despite this, radiographic data indicate that most allograft cartilage remains stable for years after implantation. The apparent durability of partially devitalized cartilage begs the question of how the extracellular matrix is maintained.

HYPOTHESIS

Compared with patients' defect cartilage, replacement OCAs freshly preserved for 36 days on average contain significantly lower levels of cartilage matrix-destructive metalloproteinases, which may contribute to the long-term stability of implanted grafts.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Chondrocyte density was determined by the cell yield from digested cartilage and by double-strand DNA content quantified with PicoGreen assay. Chondrocyte viability was estimated by staining enzymatically isolated chondrocytes with calcein AM and ethidium homodimer-2. Cartilage proteoglycan (PG) content was analyzed with dimethylmethylene blue assay. The in vitro 48-hour release of PG-depleting metalloproteinases including matrix metalloproteinase (MMP)-1, -3, -13, and ADAMTS-5 from cartilage was examined with Western blotting. The data were compared between diseased cartilage from patients and samples from matched grafts. The relative amount of MMP-3 to its endogenous inhibitor, tissue inhibitor of MMP-1 (TIMP-1), was also determined with Western blotting.

RESULTS

Chondrocyte density decreased linearly with allograft storage time and declined by an average of 43%. PG content decreased while the percentage of nonviable chondrocytes increased with storage time, with the former showing less linearity. However, PG content remained in the normal range and was significantly higher than that in patients' defect cartilage. Correspondingly, significantly less PG-depleting metalloproteinases and a much lower MMP-3/TIMP-1 ratio were detected in allograft cartilage than in patients' diseased cartilage.

CONCLUSION

These findings indicated that, at the time of implantation, fresh-preserved OCAs contained significantly lower levels of PG-depleting metalloproteinases compared with patients' defect cartilage, which might contribute to their long-term stability in vivo.

CLINICAL RELEVANCE

The comparatively low expression of cartilage-dissolving metalloproteinases in human OCAs freshly preserved over 30 days offers support to the long-term durability of implanted grafts. Based on study data that showed similarity in the response to inflammatory cytokines between patients' cartilage and OCA cartilage, strategies that can alleviate inflammation may provide extra benefit for the survival of implanted grafts. In terms of the practice of graft preservation, agents that can keep balance between the ATP supply and demand or stabilize the cell membrane or inhibit the activation of metalloproteinases may significantly improve cell viability in fresh-preserved OCAs with a storage time longer than 5 weeks.

Knee salvage procedures: The indications, techniques and outcomes of large osteochondral allografts

The overall incidence of osteochondral defect in the general population is estimated to be 15 to 30 per 100000 people. These lesions can become symptomatic causing pain, swelling and decreased function of the knee, and may eventually progress to osteoarthritis. In the young and active population, partial or total knee arthroplasty (TKA) is rarely the treatment of choice due to risk of early failure. Osteochondral allograft transplantation has been demonstrated to be a safe and effective treatment of large osteochondral and chondral defects of the knee in appropriately selected patients. The treatment reduces pain, improves function and is a viable limb salvage procedure for patients, especially young and active patients for whom TKA is not recommended. Either large dowels generated with commercially available equipment or free hand shell allografts can be implanted in more posterior lesions. Current recommendations for fresh allografts stored at 4C advise implantation within 21-28 d of procurement for optimum chondrocyte viability, following screening and testing protocols. Higher rates of successful allograft transplantation are observed in younger patients, unipolar lesions, normal or corrected malalignment, and defects that are treated within 12 mo of symptom onset. Patients with bipolar lesions, uncorrectable malalignment, advanced osteoarthritis, and those over 40 tend to have less favourable outcomes.

Fresh osteochondral allograft transplantation for isolated patellar cartilage injury

BACKGROUND

The treatment of patellofemoral cartilage injuries can be challenging. Osteochondral allograft (OCA) transplantation has been used as a treatment option for a range of cartilage disorders.

PURPOSE

To evaluate functional outcomes and survivorship of the grafts among patients who underwent OCA for patellar cartilage injuries.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

An institutional review board-approved OCA database was used to identify 27 patients (28 knees) who underwent isolated OCA transplantation of the patella between 1983 and 2010. All patients had a minimum 2-year follow-up. The mean age of the patients was 33.7 years (range, 14-64 years); 54% were female. Twenty-six (92.9%) knees had previous surgery (mean, 3.2 procedures; range, 1-10 procedures). The mean allograft area was 10.1 cm(2) (range, 4.0-18.0 cm(2)). Patients returned for clinical evaluation or were contacted via telephone for follow-up. The number and type of reoperations were assessed. Any reoperation resulting in removal of the allograft was considered a failure of the OCA transplantation. Patients were evaluated pre- and postoperatively using the modified Merle d'Aubigné-Postel (18-point) scale, the International Knee Documentation Committee (IKDC) pain, function, and total scores, and the Knee Society function (KS-F) score. Patient satisfaction was assessed at latest follow-up.

RESULTS

Seventeen of the 28 knees (60.7%) had further surgery after the OCA transplantation; 8 of the 28 knees (28.6%) were considered OCA failures (4 conversions to total knee arthroplasty, 2 conversions to patellofemoral knee arthroplasty, 1 revision OCA, 1 patellectomy). Patellar allografting survivorship was 78.1% at 5 and 10 years and 55.8% at 15 years. Among the 20 knees (71.4%) with grafts in situ, the mean follow-up duration was 9.7 years (range, 1.8-30.1 years). Pain and function improved from the preoperative visit to latest follow-up, and 89% of patients were extremely satisfied or satisfied with the results of the OCA transplantation.

CONCLUSION

OCA transplantation was successful as a salvage treatment procedure for cartilage injuries of the patella.

Cartilage restoration of the hip using fresh osteochondral allograft

Cartilage defects of the hip cause significant pain and may lead to arthritic changes that necessitate hip replacement. We propose the use of fresh osteochondral allografts as an option for the treatment of such defects in young patients. Here we present the results of fresh osteochondral allografts for cartilage defects in 17 patients in a prospective study. The underlying diagnoses for the cartilage defects were osteochondritis dissecans in eight and avascular necrosis in six. Two had Legg-Calve-Perthes and one a femoral head fracture. Pre-operatively, an MRI was used to determine the size of the cartilage defect and the femoral head diameter. All patients underwent surgical hip dislocation with a trochanteric slide osteotomy for placement of the allograft. The mean age at surgery was 25.9 years (17 to 44) and mean follow-up was 41.6 months (3 to 74). The mean Harris hip score was significantly better after surgery (p < 0.01) and 13 patients had fair to good outcomes. One patient required a repeat allograft, one patient underwent hip replacement and two patients are awaiting hip replacement. Fresh osteochondral allograft is a reasonable treatment option for hip cartilage defects in young patients.

Cite this article: Bone Joint J 2014;96-B(11 Supple A):11–16.

Osteochondral allograft transplantation of the knee in the pediatric and adolescent population

BACKGROUND

Multiple studies in adults have shown that osteochondral allograft transplantation is an effective treatment option for large chondral and osteochondral defects of the knee. Limited outcome data are available on osteochondral allografts in the pediatric and adolescent patient populations.

PURPOSE

To describe a 28-year experience with osteochondral allograft transplantation in patients younger than 18 years with a focus on subjective outcome measures, return to activities, and allograft survivorship.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 39 patients (43 knees) underwent fresh osteochondral allograft transplantation for treatment of chondral and osteochondral lesions. Twenty-six male and 17 female knees with a mean age of 16.4 years (range, 11.0-17.9 years) at index surgery were followed-up at a mean of 8.4 years (range, 1.7-27.1 years). Thirty-four knees (79%) had at least 1 previous surgery. The most common underlying causes of the lesions were osteochondritis dissecans (61%), avascular necrosis (16%), and traumatic chondral injury (14%). Mean allograft size was 8.4 cm(2). The most common allograft location was the medial femoral condyle (41.9%), followed by the lateral femoral condyle (35%). Each patient was evaluated with the International Knee Documentation Committee pain, function, and total scores; a modified Merle d'Aubigné-Postel (18-point) scale; and Knee Society function score. Failure was defined as revision osteochondral allograft or conversion to arthroplasty.

RESULTS

Five knees experienced clinical failure at a median of 2.7 years (range, 1.0-14.7 years). Four failures were salvaged successfully with another osteochondral allograft transplant. One patient underwent prosthetic arthroplasty 8.6 years after revision allograft. Graft survivorship was 90% at 10 years. Of the knees whose grafts were in situ at latest follow-up, 88% were rated good/excellent (18-point scale). The mean International Knee Documentation Committee scores improved from 42 preoperatively to 75 postoperatively, and the Knee Society function score improved from 69 to 89 (both P < .05). Eighty-nine percent of patients reported "extremely satisfied" or "satisfied."

CONCLUSION

With 88% good/excellent results and 80% salvage rate of clinical failures with an additional allograft, osteochondral allograft transplantation is a useful treatment option in pediatric and adolescent patients.

Development of a Comprehensive Osteochondral Allograft MRI Scoring System (OCAMRISS) with Histopathologic, Micro-Computed Tomography, and Biomechanical Validation

OBJECTIVE

To describe and apply a semi-quantitative MRI scoring system for multi-feature analysis of cartilage defect repair in the knee by osteochondral allografts, and to correlate this scoring system with histopathologic, micro-computed tomography (μCT), and biomechanical reference standards using a goat repair model.

DESIGN

Fourteen adult goats had two osteochondral allografts implanted into each knee: one in the medial femoral condyle (MFC) and one in the lateral trochlea (LT). At 12 months, goats were euthanized and MRI was performed. Two blinded radiologists independently rated nine primary features for each graft, including cartilage signal, fill, edge integration, surface congruity, calcified cartilage integrity, subchondral bone plate congruity, subchondral bone marrow signal, osseous integration, and presence of cystic changes. Four ancillary features of the joint were also evaluated, including opposing cartilage, meniscal tears, synovitis, and fat-pad scarring. Comparison was made with histological and μCT reference standards as well as biomechanical measures. Interobserver agreement and agreement with reference standards was assessed. Cohen's kappa, Spearman's correlation, and Kruskal-Wallis tests were used as appropriate.

RESULTS

There was substantial agreement (κ>0.6, p<0.001) for each MRI feature and with comparison against reference standards, except for cartilage edge integration (κ=0.6). There was a strong positive correlation between MRI and reference standard scores (ρ=0.86, p<0.01). OCAMRISS was sensitive to differences in outcomes between the types of allografts.

CONCLUSIONS

We have described a comprehensive MRI scoring system for osteochondral allografts and have validated this scoring system with histopathologic and μCT reference standards as well as biomechanical indentation testing.

Continuous passive motion following cartilage surgery: does a common protocol exist?

Continuous passive motion (CPM) devices have the potential to improve the histological content as well as the rate and volume of chondrogenesis in repair tissue following chondral injury. However, clinical evidence is lacking to support broad implementation of CPM following cartilage restoration procedures. We searched PubMed, CINAHL, SPORTDiscus, and Cochrane for such terms as knee, continuous passive motion, CPM, ACI, ACT, autologous chondrocyte implantation, autologous chondrocyte transplantation, microfracture, marrow-stimulation technique, mosaicplasty, osteochondral autograft, and osteochondral allograft. Inclusion criteria were all English-language studies of human subjects, evidence levels I to IV, reporting the use of CPM following cartilage repair or restoration surgery in the knee. One hundred and seven studies met inclusion criteria. Sixty-three studies reported the use of CPM following autologous chondrocyte implantation; 28 reported the use of CPM following microfracture; 13 reported the use of CPM following osteochondral autograft; and 15 reported the use of CPM following osteochondral allograft (several studies reported > 1 type of cartilage procedure, which explains why the sum of all studies reporting a particular procedure [119] is greater than the number of studies included in the review [107]). Of the 5723 patients included, 60.8% were treated with autologous chondrocyte implantation, 23.1% were treated with microfracture, 6.4% were treated with osteochondral autograft, and 9.7% were treated with osteochondral allograft. Of the 6612 total defects, 5043 (76.3%) were tibiofemoral and 1569 (23.7%) were patellofemoral. Most reports of CPM use after cartilage restoration procedures did not include specific information on how it was implemented. Overall, the description of CPM protocols in published knee articular cartilage surgery studies was disappointing. The majority of studies did not describe common variables such as the duration of CPM therapy, the initiation of CPM therapy, and the initial range of motion used. The most commonly prescribed parameters within a CPM regimen are initiated on the first postoperative day, with an initial range-of-motion of 0 to 30 degrees and a frequency of 1 cycle per minute, and for 6 to 8 hours daily over 6 weeks. The lack of consistent standardized reporting of postoperative CPM protocols provides an impetus to researchers and clinicians to more clearly define and describe their use following knee articular surgery.

Allogenous bone with collagen for repair of deep osteochondral defects

BACKGROUND

A scaffold for treatment of deep osteochondral defects should be stable, integrate well, and provide a surface for chondrocytes. To meet these demands, a biphasic scaffold of allogenous sterilized bone with a collagen surface was developed. Integration was tested in the sheep model.

MATERIAL AND METHODS

Cartilage chips were taken from the nonweight-bearing area of the left knee of 12 sheep and cultured. After 4 wk a second procedure followed and defects of 9.4-mm diameter at the weight-bearing area of the medial femoral condyle of the right knee were created. The sterilized scaffold was inserted and the cultured autologous chondrocytes were dripped onto the surface. After 6 wk, 3 mo, and 6 mo the animals were sacrificed; the explanted femoral condyles were evaluated macroscopically and using histologic, immunohistochemical, and electronmicroscopic methods.

RESULTS

After 6 wk the level of the surface was well preserved, after 3 mo parts of the scaffold were sintered but after 6 mo the surface was continuous. Full integration of the allogenous bone could be observed after 6 mo. The surface of the scaffold after 6 wk consisted of bone, but after 3 mo some chondrocytes and after 6 mo a continuous chondral layer could be detected.

CONCLUSIONS

The biphasic scaffold of allogenous bone and collagen proved to be stable and sufficiently integrated in the short- and midterm interval. Whether the chondrocytes on the surface had been derived from implanted chondrocytes or the scaffold with its surface was sufficiently chondroconductive must be answered in further investigations.

Fresh-stored osteochondral allografts for the treatment of femoral head defects: surgical technique and preliminary results

PURPOSE

The purpose of this study was to present the preliminary clinical and radiographic outcomes of the treatment of femoral head osteochondral defects in eight consecutive symptomatic patients with fresh-stored osteochondral allografts via a trochanteric osteotomy.

METHODS

This study included all consecutive patients treated in our department between 2008 and 2010 for worsening pain and mechanical symptoms of femoral head osteochondral defects. Each patient had preoperative routine hip radiographs and a preoperative magnetic resonance imaging study that determined and recorded the defect size and femoral head diameters. Allograft donors were identified through the Multiple Organ Retrieval and Exchange program (Ontario, Canada).

RESULTS

The osteochondral defects were secondary to osteochondritis dissecans in four patients, avascular necrosis in three and femoral head fracture without dislocation in one. The patients' average age at surgery was 23.7 (range 17-42), and the average follow-up was 41 months (range 24-54). Follow-up included clinical and radiographic examinations at standard intervals. The average Harris hip scores improved from 57.7 (range 50-65) points preoperatively to 83.9 (range 72-94) points at latest follow-up. Five patients had good-to-excellent clinical outcomes, and one had a fair outcome. One patient was converted to a total hip arthroplasty due to progression of arthritis. Another patient's graft subsided and he underwent a successful repeat transplantation. An additional patient required the removal of the screws transfixing her trochanter due to persistent irritation.

CONCLUSIONS

These findings indicate that fresh-stored osteochondral allograft transplantation using a trochanteric slide and surgical dislocation is a viable treatment option for femoral head defects in young patients.

Outcomes of osteochondral allograft transplantation in the knee

PURPOSE

The objectives of this study were (1) to conduct a systematic review of clinical outcomes after osteochondral allograft transplantation in the knee and (2) to identify patient-, defect-, and graft-specific prognostic factors.

METHODS

We searched PubMed, Medline, EMBASE, and the Cochrane Central Register of Controlled Trials. Studies that evaluated clinical outcomes in adult patients after osteochondral allograft transplantation for chondral defects in the knee were included. Pooled analyses for pertinent continuous and dichotomous variables were performed where appropriate.

RESULTS

There were 19 eligible studies resulting in a total of 644 knees with a mean follow-up of 58 months (range, 19 to 120 months). The overall follow-up rate was 93% (595 of 644). The mean age was 37 years (range, 20 to 62 years), and 303 patients (63%) were men. The methods of procurement and storage time included fresh (61%), prolonged fresh (24%), and fresh frozen (15%). With regard to etiology, the most common indications for transplantation included post-traumatic (38%), osteochondritis dissecans (30%), osteonecrosis from all causes (12%), and idiopathic (11%). Forty-six percent of patients had concomitant procedures, and the mean defect size across studies was 6.3 cm(2). The overall satisfaction rate was 86%. Sixty-five percent of patients (72 of 110) showed little to no arthritis at final follow-up. The reported short-term complication rate was 2.4%, and the overall failure rate was 18%. Heterogeneity in functional outcome measures precluded a meta-analysis; a qualitative synthesis allowed for the identification of several positive and negative prognostic factors.

CONCLUSIONS

Osteochondral allograft transplantation for focal and diffuse (single-compartment) chondral defects results in predictably favorable outcomes and high satisfaction rates at intermediate follow-up. Patients with osteochondritis dissecans and traumatic and idiopathic etiologies have more favorable outcomes, as do younger patients with unipolar lesions and short symptom duration. Future studies should include comparative control groups and use established outcome instruments that will allow for pooling of data across studies.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Fresh osteochondral allograft is a suitable alternative for wide cartilage defect in the knee

INTRODUCTION

There are several surgical options to restore a wide osteochondral defect in the knee. Fresh osteochondral allografts are usually considered a poor alternative due to their difficulties in surgical application. The aim of this work is first to present our experience including the surgical technique and the functional results of patients receiving fresh osteochondral allograft to restore major knee lesions, then, to compare our results with other results presented in literature.

METHODS

Between 2006 and 2011, we treated 11 patients with osteochondral lesion of the knee (Outerbridge IV°). The average lesion size was 10.3 cm(2) (range 3-20 cm(2)). The average age was 34 years (range 18-66). Patients were followed from 12 to 55 months (average of 26.5) through clinical examination, X-ray film and MRI every 3 months for the first year, then every 6 months.

RESULTS

The treatment was successful in 10 patients showing pain regression and mean IKDC subjective score improvements from 27.3 to 58.7. The IKDC objective score also improved of at least one class for each patient except the who failed. The radiographs show good osteointegration in all cases but one.

CONCLUSIONS

Fresh allograft is an effective therapy for osteochondral defects repair because it allows functional recovery in a considerable number of patients. This technique obtains better results in lesion smaller than 8 cm(2). However larger lesion show good results.

LEVEL OF EVIDENCE

Therapeutic study, Level IV.

Do fresh osteochondral allografts successfully treat femoral condyle lesions?

BACKGROUND

Fresh osteochondral allograft transplantation is an increasingly common treatment option for chondral and osteochondral lesions in the knee, but the long-term outcome is unknown.

QUESTIONS/PURPOSES

We determined (1) pain and function, (2) frequency and types of reoperations, (3) survivorship at a median of 13.5 years, and (4) predictors of osteochondral allograft failure in the distal femur.

METHODS

We evaluated 122 patients (129 knees) who underwent osteochondral allograft transplantation of the femoral condyle. Mean age was 33 years and 53% were male. Clinical evaluation included the modified Merle d'Aubigné-Postel (18-point), IKDC, and Knee Society function (KS-F) scores. We defined graft failure as revision osteochondral allografting or conversion to arthroplasty. We determined whether patient characteristics or attributes of the graft influenced failure. Minimum followup was 2.4 years (median, 13.5 years); 91% had more than 10 years of followup.

RESULTS

Mean modified Merle d'Aubigné-Postel score improved from 12.1 to 16, mean IKDC pain score from 7.0 to 3.8, mean IKDC function score from 3.4 to 7.2, and mean KS-F score from 65.6 to 82.5. Sixty-one knees (47%) underwent reoperations. Thirty-one knees (24%) failed at a mean of 7.2 years. Survivorship was 82% at 10 years, 74% at 15 years, and 66% at 20 years. Age of more than 30 years at time of surgery and having two or more previous surgeries for the operated knee were associated with allograft failure.

CONCLUSIONS

Followup of femoral condyle osteochondral allografting demonstrated durable improvement in pain and function, with graft survivorship of 82% at 10 years.

Biphasic scaffolds for repair of deep osteochondral defects in a sheep model

BACKGROUND

To oppose the disadvantages of autologous osteochondral transplantation in the treatment of deep osteochondral defects such as donor site morbidity, size limitation, and insufficient chondral integration, we developed two biphasic scaffolds of either hydroxylapatite/collagen (scaffold A) or allogenous sterilized bone/collagen (scaffold B) and tested their integration in a sheep model.

METHODS

We collected chondral biopsies from 12 sheep for the isolation of chondroblasts and cultured them for 4 wk. We created defects at the femoral condyle and implanted either scaffold A or B with chondrocytes or cell free. After 6 wk, animals were euthanized, we explanted the condyles, and evaluated them using histological, immunohistochemical, molecular biological, and histomorphometrical methods.

RESULTS

Specimens with scaffold A showed severe lowering of the surface, and the defect size was larger than for scaffold B. We found more immune-competent cells around scaffold A. Chondrocytes were scarcely detected on the surface of both scaffolds. Histomorphometry of the interface between scaffold and recipient showed no significant difference regarding tissue of chondral, osseous, fibrous or implant origin or tartrate-resistant acid phosphatase-positive cells. Real-time reverse transcriptase-polymerase chain reaction analysis revealed significant up-regulation for collagen II and SOX-9 messenger ribonucleic acid expression on the surface of scaffold B compared with scaffold A.

CONCLUSIONS

Scaffold B proved to be stable and sufficiently integrated in the short term compared with scaffold A. More extensive evaluations with scaffold B appear to be expedient.

Treatment of articular cartilage defects in the goat with frozen versus fresh osteochondral allografts: effects on cartilage stiffness, zonal composition, and structure at six months

BACKGROUND

Understanding the effectiveness of frozen as compared with fresh osteochondral allografts at six months after surgery and the resultant consequences of traditional freezing may facilitate in vivo maintenance of cartilage integrity. Our hypothesis was that the state of the allograft at implantation affects its performance after six months in vivo.

METHODS

The effect of frozen as compared with fresh storage on in vivo allograft performance was determined for osteochondral allografts that were transplanted into seven recipient goats and analyzed at six months. Allograft performance was assessed by examining osteochondral structure (cartilage thickness, fill, surface location, surface degeneration, and bone-cartilage interface location), zonal cartilage composition (cellularity, matrix content), and cartilage biomechanical function (stiffness). Relationships between cartilage stiffness or cartilage composition and surface degeneration were assessed with use of linear regression.

RESULTS

Fresh allografts maintained cartilage load-bearing function, while also maintaining zonal organization of cartilage cellularity and matrix content, compared with frozen allografts. Overall, allograft performance was similar between fresh allografts and nonoperative controls. However, cartilage stiffness was approximately 80% lower (95% confidence interval [CI], 73% to 87%) in the frozen allografts than in the nonoperative controls or fresh allografts. Concomitantly, in frozen allografts, matrix content and cellularity were approximately 55% (95% CI, 22% to 92%) and approximately 96% (95% CI, 94% to 99%) lower, respectively, than those in the nonoperative controls and fresh allografts. Cartilage stiffness correlated positively with cartilage cellularity and matrix content, and negatively with surface degeneration.

CONCLUSIONS

Maintenance of cartilage load-bearing function in allografts is associated with zonal maintenance of cartilage cellularity and matrix content. In this animal model, frozen allografts displayed signs of failure at six months, with cartilage softening, loss of cells and matrix, and/or graft subsidence, supporting the importance of maintaining cell viability during allograft storage and suggesting that outcomes at six months may be indicative of long-term (dys)function.

CLINICAL RELEVANCE

Fresh versus frozen allografts represent the "best versus worst" conditions with respect to chondrocyte viability, but "difficult versus simple" with respect to acquisition and distribution. The outcomes described from these two conditions expand the current understanding of in vivo cartilage remodeling and describe structural properties (initial graft subsidence), which may have implications for impending graft failure.

The use of osteochondral allografts in the management of cartilage defects

Large symptomatic osteochondral defects in a young active population represent a therapeutic challenge for orthopedic surgeons, since standard interventions such as debridement, microfracture and autologous osteochondral transfer are not suitable for the treatment of these larger lesions. Fresh osteochondral allograft transplantation provides a surgical option for these challenging defects, both as a primary procedure and for salvage of prior failed treatment attempts. This article reviews the basic science, indications, technique, and evidence for osteochondral allograft transplantation in the knee.

The in vivo performance of osteochondral allografts in the goat is diminished with extended storage and decreased cartilage cellularity

BACKGROUND

Currently, osteochondral allografts (OCA) are typically used after 4°C storage for prolonged durations (15-43 days), which compromises chondrocyte viability, especially at the articular surface. The long-term in vivo performance of these fresh-stored allografts, in association with variable cellularity, is unknown.

PURPOSE

To determine the effect of 4°C storage duration (14, 28 days) versus the best (fresh) and worst (frozen) conditions of chondrocyte viability on structure, composition, and function of cartilage in the goat and the association of retrieved chondrocyte cellularity with those tissue properties.

STUDY DESIGN

Controlled laboratory study.

METHODS

The effect of allograft storage on in vivo repair outcomes was determined for OCA transplanted into 15 recipient goats and analyzed at 12 months. Repair outcomes were assessed by examining cartilage structure (gross, histopathology), composition (cellularity by depth, matrix fixed charge), and biomechanical function (stiffness). Relationships between cellularity and structural scores, matrix fixed charge, and stiffness were assessed by linear regression.

RESULTS

Repair outcomes in 4°C-stored OCA were similar after 14 and 28 days of storage, and both were inferior to fresh OCA and were accompanied by diminished cellularity at the surface, matrix fixed charge, and histopathological structure. Overall, cellularity by depth and matrix fixed charge in cartilage of fresh OCA were similar to nonoperated controls. However, cellularity at the articular surface and matrix fixed charge in 4°C-stored OCA were lower than fresh, by ~55% (95% confidence interval [CI], 32%-76%) and ~20% (CI, 9%-30%), respectively. In frozen OCA, cellularity and matrix fixed charge were lower than 4°C-stored OCA, by ~93% (CI, 88%-99%) and ~22% (CI, 10%-35%), respectively. Cellularity correlated negatively with cartilage health indices, including structural scores, and positively with matrix fixed charge and stiffness.

CONCLUSION

Reduced cellularity at the articular surface, resulting from 4°C storage, was associated with variable long-term outcomes versus consistently good repair by fresh allografts. Cellularity at the articular surface was an important index of biological performance.

CLINICAL RELEVANCE

Normal chondrocyte density in vivo, especially in the superficial region of cartilage, is important for maintaining long-term cartilage function and matrix content. In human cartilage, containing cells at ~3 to 5 times lower density than goat, repair outcomes may be related to absolute minimum number of cells rather than density.

Management of articular cartilage defects of the knee

Articular cartilage injuries of the knee present a difficult clinical dilemma and their treatment is controversial. Hyaline articular cartilage is an avascular, low-friction, and wear-resistant weightbearing surface that has limited capacity for self-repair. The optimal treatment for cartilage lesions has yet to be established. Various treatment methods are employed to reestablish a stable cartilage surface, including microfracture, autologous and allograft osteochondral transplantation, autologous chondrocyte implantation, matrix-associated chondrocyte implantation, and scaffold-assisted methods. Treatment algorithms help to guide physicians' decision making in the care of these injuries. In this article, results from outcomes studies as well as prospective randomized clinical trials comparing treatment methods are reviewed, and current practice guidelines are summarized.

Clinical cartilage restoration: evolution and overview

BACKGROUND

Clinical cartilage restoration is evolving, with established and emerging technologies. Randomized, prospective studies with adequate power comparing the myriad of surgical techniques used to treat chondral injuries are still lacking and it remains a challenge for the surgeon treating patients to make evidence-based decisions.

QUESTIONS/PURPOSES

We reviewed the history of the major cartilage repair/restorative procedures, indications for currently available repair/restorative procedures, and postoperative management.

METHODS

We performed searches using MEDLINE and cartilage-specific key words to identify all English-language literature. Articles were selected based on their contributions to our current understanding of the basic science and clinical treatment of articular cartilage lesions or historical importance. We then selected 77 articles, two of which are articles of historical importance.

RESULTS

Current cartilage restorative techniques include débridement, microfracture, osteochondral fragment repair, osteochondral allograft, osteochondral autograft, and autologous chondrocyte transplantation. Pending techniques include two-staged cell-based therapies integrated into a variety of scaffolds, single-stage cell-based therapy, and augmentation of marrow stimulation, each with suggested indications including lesion size, location, and activity demands of the patient. The literature demonstrates variable improvements in pain and function contingent upon multiple variables including indications and application.

CONCLUSIONS

For the patient with symptomatic chondral injury, numerous techniques are available to the surgeon to relieve pain and improve function. Until rigorous clinical trials (prospective, adequately powered, randomized control) are available, treatment decisions should be guided by expert extrapolation of the available literature based in historically sound principles.

Treatment of focal osteochondral defects of the acetabulum with osteochondral allograft transplantation

To our knowledge, treatment of focal osteochondral defects of the acetabulum with osteochondral allograft transplantation has not been described. As with osteochondral lesions of other weight-bearing surfaces, these defects may lead to disabling pain and early degenerative changes. In older patients who fail nonoperative treatment, hip arthroplasty is a reliable option to obtain pain relief and restore function. However, in young and active patients, it may be advantageous to restore joint congruity biologically. The clinical success of osteochondral allograft transplantation in the femoral condyles has been well-documented, with over 25 years of experience. We propose similar treatment principles in the hip joint.This article presents the cases of a 24-year-old woman (patient 1) and a 32-year-old man (patient 2) with hip pain and dysfunction secondary to a focal osteochondral defect of the acetabulum. Both were treated with osteochondral allograft transplantation to the defect using a dowel technique. A magnetic resonance image at 18 months in both cases demonstrated incorporation of the allograft bone into the host acetabulum. At 24 months in patient 1 and 42 months in patient 2, radiographs showed no progressive osteoarthritis. Both patients' Hip Outcome Scores were 100 points each.Osteochondral allografts allow large areas to be resurfaced without donor site morbidity, and these grafts provide an immediate functional joint surface. Although it has not been proven in terms of long-term follow-up, we believe that osteochondral allograft transplantation for focal osteochondral defects of the acetabulum in young, active patients is a feasible option to restore joint congruity.

Scanty integration of osteochondral allografts cryopreserved at low temperatures with dimethyl sulfoxide

PURPOSE

To compare the integration of osteochondral allografts cryopreserved at different temperatures and different concentrations of dimethyl sulfoxide in an in vivo sheep animal model.

METHODS

Thirty-six adult sheep were randomly allocated to 6 groups of allograft osteochondral transplantation. Six osteochondral cylinders were stored for 6 weeks at -80°C; 6 at -80°C with 10% dimethyl sulfoxide (DMSO); 6 at -80°C with 10% DMSO for 90 min; 6 at -186°C; 6 at -186°C with 10% DMSO; 6 at -186°C for 90 min. After transplantation, all animals were euthanized at 6 months. Harvested specimens underwent gross morphologic and histologic evaluation.

RESULTS

We found no statistically significant differences when comparing the gross cartilage morphology and histopathologic scores of each group. The Mankin and OARSI scores and the modified Wakitani and OARSI scores showed a good correlation grade. The Mankin and modified Wakitani scores showed a fair correlation grade.

CONCLUSION

The cryopreservation protocols adopted in the present study provided scanty integration in an in vivo sheep model of osteochondral allograft transplantation. Therefore, their use in the clinical practice is discouraged.

The use of the Tegner Activity Scale for articular cartilage repair of the knee: a systematic review

PURPOSE

The Tegner Activity Scale (TAS) was developed in 1984 and has been widely used in studies on knee populations. The primary objective of this study was to undertake a systematic review on the use of the TAS for articular cartilage repair (ACR) of the knee.

METHODS

A systematic review was conducted using electronic databases (MEDLINE, CINAHL, SPORTDiscus™, NHS Evidence, ISI Web of Knowledge, AMED, BNI, PEDro and The Cochrane Collaboration of Systematic Reviews) and reference lists from extracted articles. Studies were selected that were published between 1984 and 2009 in which the TAS was reported for patients who had undergone ACR of the knee.

RESULTS

The search strategy identified 442 citations of which 34 articles met the inclusion criteria. There was a large degree of study heterogeneity especially regarding data reporting a wide variation in the number of participants (range 5-137), participant age (range 12-76 years), follow-up time (range 3-120 months) and male-to-female participant ratio. Where pre- to postoperative TAS change was analysed, 88% of studies demonstrated a significant improvement in postoperative TAS scores.

CONCLUSIONS

In general, TAS data were inconsistently reported and methodological detail was often lacking. Caution is advised in the interpretation of TAS scores following ACR of the knee where there are large ranges in postoperative follow-up times, mixed gender cohorts and wide ranges in participant ages. TAS data should be presented and analysed fully and ideally in a standardised fashion to facilitate the comparison of outcomes between studies.