Biomechanical properties of articular cartilage in different regions and sites of the knee joint: acquisition of osteochondral allografts

Osteochondral allograft (OCA) transplantation involves grafting of natural hyaline cartilage and supporting subchondral bone into the cartilage defect area to restore its biomechanical and tissue structure. However, differences in biomechanical properties and donor-host matching may impair the integration of articular cartilage (AC). This study analyzed the biomechanical properties of the AC in different regions of different sites of the knee joint and provided a novel approach to OCA transplantation. Intact stifle joints from skeletally mature pigs were collected from a local abattoir less than 8 h after slaughter. OCAs were collected from different regions of the joints. The patella and the tibial plateau were divided into medial and lateral regions, while the trochlea and femoral condyle were divided into six regions. The OCAs were analyzed and compared for Young's modulus, the compressive modulus, and cartilage thickness. Young's modulus, cartilage thickness, and compressive modulus of OCA were significantly different in different regions of the joints. A negative correlation was observed between Young's modulus and the proportion of the subchondral bone (r =  - 0.4241, P < 0.0001). Cartilage thickness was positively correlated with Young's modulus (r = 0.4473, P < 0.0001) and the compressive modulus (r = 0.3678, P < 0.0001). During OCA transplantation, OCAs should be transplanted in the same regions, or at the closest possible regions to maintain consistency of the biomechanical properties and cartilage thickness of the donor and recipient, to ensure smooth integration with the surrounding tissue. A 7 mm depth achieved a higher Young's modulus, and may represent the ideal length.

Avascular necrosis of the proximal humerus: a novel indication for the use of osteochondral allograft transplantation in the shoulder: Case report

Osteochondral allograft (OCA) transplantation is an increasingly available biologic treatment option for a range of intraarticular aetiologies. To our knowledge, no prior publication has documented the use of this technology to treat a lesion of the proximal humerus secondary to avascular necrosis (AVN). We describe our experience treating a 42-year-old female executive with idiopathic AVN of the proximal humerus with a fresh osteochondral allograft. Computed tomography (CT) at 3 months post-op showed full bony incorporation and a restored native joint contour. Over the initial 7 months post-operatively, she reported continued improvements in pain and function as measured by quick Disabilities of the Arm, Shoulder, and Hand (DASH) scores. She was discharged from physical therapy after 6 months, reporting no rest pain, full active and passive range of motion, and unrestricted occupational and recreational activity.

Allograft reconstruction for humeral head defects in the setting of shoulder instability: a systematic review

Background

Glenohumeral joint instability and dislocation are common orthopedic pathologies that can produce osseous humeral head defects such as Hill-Sachs (HS) or Reverse Hill-Sachs (RHS) lesions. Numerous reconstruction techniques have been reported in the literature, including remplissage, disimpaction, and allograft reconstruction. No group has previously assessed the outcomes of allograft reconstruction for RHS lesions, nor compared the outcomes of allograft reconstruction for HS and RHS lesions. In this study, we aim to provide a comprehensive assessment of osteochondral allograft reconstruction for the distinct pathologies of RHS lesions and HS lesions by comparing postreconstruction patient-reported outcomes, complications, and radiographic assessments for each lesion.

Methods

Using Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic review was performed to identify and include studies that reported patient outcomes after the use of osteochondral allografts in the reconstruction of HS or RHS lesions of the humeral head. A comprehensive search of the Google Scholar, PubMed, and Embase databases was conducted with the key terms "allograft," "Hill-Sachs," and "reverse Hill-Sachs."

Results

Eight studies, with a total of 84 patients, were included for review. Of the 84 allograft-treated patients, there were 44 patients with HS lesions and 40 patients with RHS lesions. The average patient age was 27.3 years for HS lesions and 43.0 years for RHS lesions. Postoperative range of motion and average Constant-Murley score (87.9 for HS and 80.1 for RHS) appeared to be greater for those with HS lesions. In addition, 20.5% of HS patients experienced postoperative complications, whereas 42.5% of RHS patients had postoperative complications (P = .03). HS and RHS patients experienced similar proportions of graft resorption or collapse rate (22.7% for HS and 12.5% for RHS; P = .2).

Conclusion

Patient-reported outcomes indicate that osteochondral allograft reconstruction for large RHS and HS lesions is an acceptable intervention. RHS patients had lower rates of graft resorption and collapse but worse postoperative range of motion and functional outcomes, although these differences were not statistically significant. HS patients experienced significantly fewer complications than those with RHS lesions.

Computerized tomography scan evaluation after fresh osteochondral allograft transplantation of the knee correlates with clinical outcomes

Purpose

To determine the correlation between the assessment computed tomography osteochondral allograft (ACTOCA) scoring system and clinical outcomes scores. The hypothesis was that the ACTOCA score would show sufficient correlation to support its use in clinical practice.

Methods

We prospectively collected data from all consecutive patients who underwent cartilage restitution with fresh osteochondral allograft (FOCA) transplantation for osteochondral lesions of the knee and had a minimum follow-up of two years. CT scans were performed at three, six and 24 months post-operatively. A musculoskeletal radiologist blinded to the patients’ medical history evaluated the scans using the ACTOCA scoring system. Clinical outcomes collected preoperatively and at three, six and 24 months postoperatively were evaluated using the International Knee Documentation Committee (IKDC), Kujala, the Western Ontario Meniscal Evaluation Tool (WOMET), and the Tegner Activity Scale.

Results

The mean total ACTOCA score showed a statistically significant correlation with the clinical outcome. The correlation was optimal at 24 months. We found a high negative correlation with the IKDC, Kujala and Tegner (− 0.737; − 0.757, and − 0.781 respectively), and a moderate negative correlation with WOMET (− 0.566) (p < 0.001). IKDC, Kujala, WOMET, and Tegner scores showed a significant continuous improvement in all scores (p < 0.001).

Conclusion

The mean total ACTOCA score showed a linear correlation with clinical results in IKDC, Kujala, WOMET, and Tegner scores, being the highest at 24 months post-surgery. This finding supports the use of ACTOCA to standardize CT scan reports following fresh osteochondral allograft transplantation in the knee.

Management of Chondral Defects Associated with Patella Instability

Cartilage defects of the patellofemoral joint are commonly found in association with patellar instability owing to abnormal biomechanics. Strategies to address chondral defects of the patellofemoral joint secondary to instability should first address causes of recurrent instability. Most patellofemoral chondral defects associated with instability are less than 2 cm2 and do not generally require intervention beyond chondroplasty. Larger defects of the patella and/or the trochlea can be repaired with osteochondral or surface cartilage repair.

Osteochondral allograft transplantation for complex distal humeral fractures assisted by 3D computer planning and printing technology: technical note

PURPOSE

The surgical treatment of comminuted distal humeral articular fractures (DHF) is challenging and is jeopardized by the high rate of complications. The study aims to describe the application of osteochondral allograft (OCA) transplantation for the treatment of complex DHF assisted with a 3D printed specific instrumentation.

METHODS

Retrospective study. Inclusion criteria were the presence of an articular multi-fragmented DHF treated with frozen OCA. Clinical, self-reported and radiographic outcomes were collected every 6 months. CT were performed at 2 years FU.

RESULTS

Four patients were included. At a mean follow-up of 37.3 months (24-49) MEPS, DASH and VAS were 90 (80-100), 11.8 (0-25) and 1 (0-3) points, respectively. Not significant complication or reoperation was recorded. Graft healing was observed in 3 cases. In all cases, we observed arthritic progression after 2 years of follow-up.

CONCLUSION

OCA transplantation can be considered a reliable and safe procedure in patients affected by a complex DHF.

LEVEL OF EVIDENCE

Level V. Technical Notes.

Local curvature mismatch may worsen the midterm functional outcomes of osteochondral allograft transplantation

PURPOSE

This study aimed to determine the magnitude of local curvature matching in the sagittal plane between an implanted graft and the condylar region receiving the graft and to analyze its effect on clinical outcomes in patients undergoing osteochondral allograft transplantation (OCA).

METHODS

Patients who underwent knee OCA between 2016 and 2019 without circumferential step-off and were matched with a donor in accordance with the conventional matching process were included. The magnitude of donor-host local curvature matching was measured using postoperative sagittal magnetic resonance imaging data with Syngo (Siemens Medical Solutions, Forchheim, Germany) and GeoGebra (GeoGebra GmbH, Linz, AU) software. In addition to radiological evaluation, ROC analysis was performed to compare the patient-reported outcome measures (PROMs) obtained during the 2-year follow-up period among the patients in the SagA group, who had a graft match in the sagittal plane; SagB group, who had low convexity of the graft in the sagittal plane; and SagC group, who had high convexity of the graft in the sagittal plane in accordance with the determined indices.

RESULTS

The study included 27 patients who fulfilled the inclusion criteria, and the mean clinical scores of the SagC group were not statistically significantly higher than those of the other groups at any timepoint during the follow-up. The mean Tegner, IKDC, total KOOS and SF-12 physical and mental health scores of the SagC group were lower than those of the other two groups at various follow-up time points, particularly at month 24 (p < 0.05). There were no significant differences between the SagA and SagB groups in the PROMs at any of the follow-up time points (n.s.). The significant differences observed between the SagC group and the other groups in the mean KOOS scores for function in daily living and function in sport and recreation were also observed between the SagA and SagB groups at the follow-ups (p < 0.05).

CONCLUSION

During OCA, a local curvature mismatch between the donor and the host involving large graft convexity may have a negative impact on midterm clinical outcomes. A preoperative analysis of the convexity relationship between the defect site and the graft region in the hemicondylar allograft to be used may enhance donor-host matching. The local analysis method described in the current study may also facilitate graft supply by ensuring donor-host matching without condyle-side and size matching.

LEVEL OF EVIDENCE

III.

Follow up 10 years

BACKGROUND

Osteochondral allografts (OA) kept fresh for a long time, are presented as a viable option for the treatment of large chondral and osteochondral lesions.

GOALS

Chondrocyte viability decreases substantially when allografts are stored for more than 15 days. The objective of this work is to validate the viability and clinical and functional results of OA transplantation stored at 37°C in a cell culture medium, applied in cartilage defects of the knee, defining the means and limits of allograft storage, among 15 and 28 days after extraction.

PATIENTS AND METHOD

This study presents the results of 20 consecutive patients, operated between 2003 and 2019, who underwent a fresh-preserved osteochondral allograft, implanted on cartilage defects of the femoral condyle and patella. The minimum follow-up time was 10 years and the maximum 17. The mean age of the patients was 29 (14-44). The clinical control data were collected using International Knee Documentation Committee (IKDC) (knee-specific), Knee injury and Osteoarthritis Outcome Score (KOOS) protocols. Likewise, the degree of satisfaction was evaluated. Cartilage control was performed using the International Cartilage Repair Society Score (ICRS) and the Oswestry Arthroscopy Score (OAS). Radiological evaluations were performed using MRI and helical CT.

RESULTS

Statistically significant improvements, P<.0001, were observed for the IKDC: 30-65; the 5 components of the KOOS protocol, pain; 66-85; specific symptoms: 72-82; activities of daily living: 74-91; sports and recreational function: 37-70; related to the knee, quality of life: 25-60. Regarding the degree of satisfaction, 89% answered being satisfied or very satisfied. The ICRS and OAS results, all patients went from grade IV to grade I, except for one who is currently in IV. The incorporation of the graft in the recipient area occurred at three months, verified by helical CT and MRI.

CONCLUSION

Osteochondral allograft transplants stored fresh at 37°C are established as a long-term solution for the treatment of localized osteochondral defects in the knee.

A new computed tomography scoring system to assess osteochondral allograft transplantation for the knee: inter-observer and intra-observer agreement

AIM OF THE STUDY

To describe a new semiquantitative computed tomography (CT) scoring system for multi-feature analysis of cartilage defect repair by osteochondral allografts for the knee and to assess its intra-observer and inter-observer variability.

METHOD

A semiquantitative assessment CT osteochondral allograft (ACTOCA) scoring system was designed based on fresh osteochondral allograft transplantations for the knee. The system includes five CT features: density relative to host bone, integration at the host-graft junction, surface percentage with a discernible cleft at the host-graft junction, cystic changes, and intra-articular fragments. Inter-observer variability was calculated by three observers blinded to the patient's medical history and treatment. Intra-observer variability was also determined.

RESULTS

Inter-observer agreement was moderate to substantial for all CT score components and intra-observer agreement was moderate to almost perfect for all CT score components (κ > 0.5, p < 0.05).

CONCLUSION

The ACTOCA score is a reliable tool to evaluate integration of osteochondral allograft transplantations. It provides an accurate evaluation of bone changes and may help to standardize CT scan reports following osteochondral allograft transplantation for the knee.

Cryopreserved, Thin, Laser-Etched Osteochondral Allograft maintains the functional components of articular cartilage after 2 years of storage

BACKGROUND

Despite improvements in treatment options and techniques, articular cartilage repair continues to be a challenge for orthopedic surgeons. This study provides data to support that the 2-year Cryopreserved, Thin, Laser-Etched Osteochondral Allograft (T-LE Allograft) embodies the necessary viable cells, protein signaling, and extracellular matrix (ECM) scaffold found in fresh cartilage in order to facilitate a positive clinical outcome for cartilage defect replacement and repair.

METHODS

Viability testing was performed by digestion of the graft, and cells were counted using a trypan blue assay. Growth factor and ECM protein content was quantified using biochemical assays. A fixation model was introduced to assess tissue outgrowth capability and cellular metabolic activity in vitro. Histological and immunofluorescence staining were employed to confirm tissue architecture, cellular outgrowth, and presence of ECM. The effects of the T-LE Allograft to signal bone marrow-derived mesenchymal stem cell (BM-MSC) migration and chondrogenic differentiation were evaluated using in vitro co-culture assays. Immunogenicity testing was completed using flow cytometry analysis of cells obtained from digested T-LE Allografts and fresh articular cartilage.

RESULTS

Average viability of the T-LE Allograft post-thaw was found to be 94.97 ± 3.38%, compared to 98.83 ± 0.43% for fresh articular cartilage. Explant studies from the in vitro fixation model confirmed the long-term viability and proliferative capacity of these chondrocytes. Growth factor and ECM proteins were quantified for the T-LE Allograft revealing similar profiles to fresh articular cartilage. Cellular signaling of the T-LE Allograft and fresh articular cartilage both exhibited similar outcomes in co-culture for migration and differentiation of BM-MSCs. Flow cytometry testing confirmed the T-LE Allograft is immune-privileged as it is negative for immunogenic markers and positive for chondrogenic markers.

CONCLUSIONS

Using our novel, proprietary cryopreservation method, the T-LE Allograft, retains excellent cellular viability, with native-like growth factor and ECM composition of healthy cartilage after 2 years of storage at - 80 °C. The successful cryopreservation of the T-LE Allograft alleviates the limited availably of conventionally used fresh osteochondral allograft (OCA), by providing a readily available and simple to use allograft solution. The results presented in this paper supports clinical data that the T-LE Allograft can be a successful option for repairing chondral defects.

Current hip cartilage regeneration/repair modalities: a scoping review of biologics and surgery

PURPOSE

The rapidly growing and emerging nature of biologics have made indications for regenerative and reparative hip therapies ever changing, with at times only early-stage evidence for their use. The purpose of this study was to review and summarize the currently available data on the management of hip cartilage injuries and osteoarthritis.

METHODS

A scoping review of the available scientific literature for hip biologics was performed, with available evidence for hyaluronic acid (HA), platelet rich plasma (PRP), stem/stromal cells, microfracture, mosaicplasty, osteochondral allograft, and cell-based therapies investigated.

RESULTS

To date, there exist better guidelines and further consensus concerning knee joint biologic treatments than the hip due to a greater number of studies as well as the more recent emergence of hip preservation approaches. However, increasing evidence is available for the selective implementation of biologics on an individualized basis with attention to lesion size and location.

CONCLUSION

Orthopedic surgeons are at an exciting crossroads in medicine, where hip biologic therapies are evolving and increasingly available. Timetested interventions such as arthroplasty have shown good results and still have a major role to play but newer, regenerative approaches have the potential to effectively delay or reduce the requirement for such invasive procedures.

Outcomes associated with behavioral evaluation and counseling for patients undergoing orthopaedic surgery - A systematic review

Osteochondral allograft transplantation can be an effective way to treat cartilage defects in the knee. The objective of this systematic review was to evaluate available research on the effects of preoperative behavioral evaluation and counseling on the outcomes for patients undergoing orthopaedic surgery with emphasis on osteochondral allograft transplantation in the knee. This systematic review of best current evidence indicates that psychological distress and untreated mental health issues are strongly associated with unfavorable outcomes after treatment of orthopaedic disorders, underscoring the need to incorporate behavioral screening and counseling into a comprehensive patient management protocol that improves outcomes for patients.

Management of the Failed OCD

PURPOSE OF THE REVIEW

Osteochondritis dissecans (OCD) is a pathologic condition of subchondral bone most frequently occurring in the medial femoral condyle of the knee in children and adolescents. Salvage techniques are necessary when either nonoperative or typical operative treatments fail, or the OCD presents in an unsalvageable state. The purpose of this review is to describe the evaluation and management of failed OCDs.

RECENT FINDINGS

Thorough preoperative planning is essential to the treatment of failed OCDs. Radiographs and advanced imaging such as MRI and CT allow for a detailed assessment of subchondral bone and cartilage. Long-leg alignment radiographs are critical to assess for malalignment which may increase the contact forces on the affected condyle. Malalignment can be corrected with hemiepiphysiodesis or an osteotomy depending on the skeletal maturity of the patient. Osteochondral allografts and autologous chondrocyte implantation treat the defect in both bone and cartilage or solely cartilage and have good short to moderate term outcomes, particularly as compared to the inferior outcomes of microfracture of larger OCDs. Osteochondritis dissecans of the knee that fails to heal with initial operative measures can result in a large defect of bone and cartilage in the knee of adolescents. Treatment of the bone and cartilage defect can be accomplished with either osteochondral allograft transplantation or matrix-assisted autologous chondrocyte implantation can be performed with good outcomes. Assessment and correction of lower extremity malalignment is a critical component of treatment. Durable long-term solutions are necessary for the treatment of these difficult lesions.

Fluid imbibition at the bone-cartilage interface is associated with need for early chondroplasty following osteochondral allografting of the knee

PURPOSE

To determine the clinical significance of fluid imbibition at the bone-cartilage interface seen on postoperative MRI scans after osteochondral grafting of chondral lesions of the knee.

METHODS

Retrospective review of patients enrolled in a prospective cartilage repair registry. Included patients underwent osteochondral autografting or allografting of the knee, had minimum one year of clinical follow-up, and underwent at least two postoperative MRI scans. The primary outcome was reoperation for arthroscopic debridement and chondroplasty or graft revision. Secondary outcomes included the radiographic fate of fluid imbibition.

RESULTS

A total of 48 knees in 46 patients were analyzed, with mean 39 months clinical follow-up. Nine patients (19%) had fluid imbibition on at least one postoperative MRI scan, all of whom received allograft. Of these, two (22%) required eventual graft revision, four (45%) underwent arthroscopic chondroplasty but did not require revision, and three (33%) did not require any additional surgery by final follow-up. No demographic or surgical variable was associated with the presence of fluid imbibition. Fluid imbibition was significantly associated with need for chondroplasty (p = 0.05), but not graft revision.

CONCLUSIONS

Fluid imbibition on postoperative MRI following osteochondral allografting of the knee is associated with the need for arthroscopic chondroplasty, but should not be interpreted as a sign of a failing graft.

LEVEL OF EVIDENCE

Level IV, Case Series.

Patellofemoral Cartilage Repair

Purpose of Review

This review provides an overview of well-established and newly developed cartilage repair techniques for cartilage defects in the patellofemoral joint (PFJ). An algorithm will be presented for approaching cartilage defects considering the distinct anatomy of both the patellar and trochlear articular surfaces.

Recent Findings

Recent studies on cartilage repair in the PFJ have demonstrated improved outcomes in an attempt to delay or obviate the need for arthroplasty, and improve symptoms in young patients. While autologous chondrocyte implantation shows good and excellent outcomes for chondral lesions, osteochondral defects are adequately addressed with osteochondral allograft transplantation. In case of patellar malalignment, concomitant tibial tubercle osteotomy can significantly improve outcomes. Particulated cartilage and bone marrow aspirate concentrate are potential new alternative treatments for cartilage repair, currently in early clinical studies.

Summary

Due to the frequency of concomitant anatomic abnormalities in the PFJ, a thorough clinical examination combined with careful indication for each procedure in each individual patient combined with meticulous surgical technique is central to achieve satisfying outcomes. Additional comparative studies of cartilage repair procedures, as well as investigation of newer techniques, are needed.

Large fresh osteochondral allografts for the hip: growing the evidence

INTRODUCTION

Articular cartilage lesions of the hip are difficult to effectively treat. Osteochondral allograft (OCA) transplantation in the knee has been associated with long-term success, but OCA for the hip has not been extensively studied. Here, we present the clinical and radiological outcomes from a cohort of 10 patients treated with fresh OCA transplants for large osteochondral defects of the femoral head and/or acetabulum.

METHODS

10 patients who had undergone osteochondral allograft transplantation of the femoral head and/or acetabulum at our institution between 2013 and 2016 were identified from our Institutional Review Board-approved registry. Hip disability and Osteoarthritis Outcome Score (HOOS) was used to track patient progress.

RESULTS

10 patients with an average clinical follow-up of 1.4 years were included in this study. 4 patients were treated solely with OCA plugs for femoral head defects, while the remaining 6 received femoral OCA plugs and at least 1 concomitant procedure for additional intraarticular pathology. 7 patients (70%) had successful functional outcomes, while 3 (30%) had unsuccessful outcomes and were subsequently converted to total hip arthroplasty (THA) 5 to 29 months after OCA.

CONCLUSIONS

OCA transplantation can be an effective treatment strategy for young, healthy individuals with articular cartilage lesions of the hip. Smoking, avascular necrosis aetiology, acetabular involvement and concomitant procedures may be risk factors for unsuccessful outcomes necessitating salvage with THA. Long-term clinical studies to refine indications and determine functional outcomes and survival rates are warranted.

Biomechanics of osteochondral impact with cushioning and graft Insertion: Cartilage damage is correlated with delivered energy

Articular cartilage is susceptible to impact injury. Impact may occur during events ranging from trauma to surgical insertion of an OsteoChondral Graft (OCG) into an OsteoChondral Recipient site (OCR). To evaluate energy density as a mediator of cartilage damage, a specialized drop tower apparatus was used to impact adult bovine samples while measuring contact force, cartilage surface displacement, and OCG advancement. When a single impact was applied to an isolated (non-inserted) OCG, force and surface displacement each rose monotonically and then declined. In each of five sequential impacts of increasing magnitude, applied to insert an OCG into an OCR, force rose rapidly to an initial peak, with minimal OCG advancement, and then to a second prolonged peak, with distinctive oscillations. Energy delivered to cartilage was confirmed to be higher with larger drop height and mass, and found to be lower with an interposed cushion or OCG insertion into an OCR. For both single and multiple impacts, the total energy density delivered to the articular cartilage correlated to damage, quantified as total crack length. The corresponding fracture toughness of the articular cartilage was 12.0 mJ/mm². Thus, the biomechanics of OCG insertion exhibits distinctive features compared to OCG impact without insertion, with energy delivery to the articular cartilage being a factor highly correlated with damage.

Osteochondral Lesions of the Talus Treatment With Fresh Frozen Allograft

INTRODUCTION

Symptomatic talar osteochondral lesions are about 50% refractory to conservative treatment requiring a surgical solution. In the case of large chronic lesions, the use of bone graft taken from tissue bank is an alternative that enables to fill the defect without causing donor site morbidity.

MATERIAL AND METHODS

Eight patients treated with talar osteochondral allograft in lesions greater than 20mm in diameter were analyzed - 4 males and 4 females aging 39.5 years old on average. Evaluation was performed according to AOFAS scale and VAS as well as incorporation and continuation evaluations according to CT and MRI studies. A follow-up of 46.8 months on average was done.

RESULTS

A 34.6-point improvement on average according to AOFAS. A 6.7-point pain improvement on average according to VAS. Incorporation in 100% of the cases. Two cases showed partial resorption and one case showed peri-graft lysis less than 30%. There was no collapse.

CONCLUSIONS

Fresh frozen osteochondral allografts are a viable alternative when treating large osteochondral lesions, thereby avoiding morbidity of autologous donor areas or arthrodesis procedures.

Restorative Tissue Transplantation Options for Osteochondral Lesions of the Talus: A Review

Symptomatic osteochondral lesions of the talus remain a challenging problem due to inability for cartilage lesions to heal. Numerous treatment options exist, including nonoperative management, marrow stimulating techniques, and autograft-allograft. Arthroscopic marrow stimulation forms fibrocartilage that has been shown to be biomechanically weaker than hyaline cartilage. Restorative tissue transplantation options are being used more for larger and cystic lesions. Newer biologics and particulated juvenile cartilage are currently under investigation for possible clinical efficacy. This article provides an evidenced-based summary of available literature on the use of biologics for treatment of osteochondral lesions of the talus.

Lactated Ringer-based storage solutions are equally well suited for the storage of fresh osteochondral allografts as cell culture medium-based storage solutions

BACKGROUND

Due to the rising interest in Europe to treat large cartilage defects with osteochondrale allografts, research aims to find a suitable solution for long-term storage of osteochondral allografts. This is further encouraged by the fact that legal restrictions currently limit the use of the ingredients from animal or human sources that are being used in other regions of the world (e.g. in the USA). Therefore, the aim of this study was A) to analyze if a Lactated Ringer (LR) based solution is as efficient as a Dulbecco modified Eagle's minimal essential medium (DMEM) in maintaining chondrocyte viability and B) at which storage temperature (4°C vs. 37°C) chondrocyte survival of the osteochondral allograft is optimally sustained.

METHODS

300 cartilage grafts were collected from knees of ten one year-old Black Head German Sheep. The grafts were stored in four different storage solutions (one of them DMEM-based, the other three based on Lactated Ringer Solution), at two different temperatures (4 and 37°C) for 14 and 56days. At both points in time, chondrocyte survival as well as death rate, Glycosaminoglycan (GAG) content, and Hydroxyproline (HP) concentration were measured and compared between the grafts stored in the different solutions and at the different temperatures.

RESULTS

Independent of the storage solutions tested, chondrocyte survival rates were higher when stored at 4°C compared to storage at 37°C both after short-term (14days) and long-term storage (56days). At no point in time did the DMEM-based solution show a superior chondrocyte survival compared to lactated Ringer based solution. GAG and HP content were comparable across all time points, temperatures and solutions.

CONCLUSION

LR based solutions that contain only substances that are approved in Germany may be just as efficient for storing grafts as the USA DMEM-based solution gold standard. Moreover, in the present experiment storage of osteochondral allografts at 4°C was superior to storage at 37°C.

Bipolar fresh total osteochondral allograft in the ankle: Is it a successful long-term solution?

INTRODUCTION

Severe post-traumatic ankle arthritis poses a reconstructive challenge in young and active patients. Although technically demanding and despite unsolved immunological issues, bipolar fresh total osteochondral allograft (BFTOA) represent an intriguing option to arthrodesis and prosthetic replacement. The purpose of this paper is to evaluate the outcomes of a series of 48 ankle BFTOA at 10 years follow up and to investigate the rate of survival long term.

METHODS

58 patients underwent BFTOA, of these 48 were available for follow up. The allograft was prepared with the help of specifically designed jigs and the surgery was performed using either a lateral or a direct anterior approach. Patients were evaluated clinically and radiographically preoperatively, and at a mean 121±18months of follow-up.

RESULTS

The AOFAS score improved from 31±11 pre operatively, to 65±25 at the last (p<0.0005). Fourteen failures occurred, with 70.8% allograft rate of survival. All the surviving allografts showed a reduction of the ankle joint movement, still associated with a satisfactory clinical result.

CONCLUSION

The use of BFTOA represents an intriguing option to arthrodesis or arthroplasty. A satisfactory clinical result associated to a good movement of the transplanted joint is to be expected up to short-mid-term, overtime. Long term, the range of motion (ROM) is progressively decreased up to spontaneous arthrodesis in some cases, still the joint results pain free and patient's perception is of a well functioning ankle. A deeper knowledge of the immunological behavior of transplanted cartilage is needed in order to improve the durability of this fascinating technique.

Two-stage late reconstruction with a fresh large osteochondral shell allograft transplantation (FLOCSAT) for a large ostechondral defect in a non-union after a lateral tibia plateau fracture 2-year follow up

This is the description of a 58-year-old female patient presenting 8 months after a horse riding accident with significant pain and inability to walk independently. Imaging revealed a large osseous defect of the lateral tibia plateau which was not united posteriorly. The patient refused knee replacement and we developed a patient specific two-step procedure for her. Step 1: Filling of the defect with a large cortico-cancellous autograft from the posterior iliac crest; step 2: Transplantation of a fresh large osteochondral shell allograft (FLOCSAT). The postoperative protocol included continuous passive motion (CPM), partial weight bearing for three months, and physiotherapy. Based on the concept of immuno-privileged cartilage tissue, the patient did not get any immuno-suppressive therapy. Pain-, activity of daily living, Lysholm and Tegner scores were evaluated before defect filling surgery with autograft, before allograft transplantation, and at 12 and 24 months after allograft transplantation. There were no complications. Radiographic analyses with plain films and CT scans revealed solid osseous integration within 3 month. The patient regained excellent functionality in both, activities of daily living and sports (back to horse riding, trampolin jumping). Knee arthroscopy after 1year showed excellent condition of the lateral meniscus and the cartilage of the lateral tibia plateau. Chimerism/DNA analysis of a cartilage biopsy showed, that at 1year 32% of the donor cells have been already replaced by the patient's own cells. To our knowledge, this is the first case of a patient who sustained such a large defect during a tibia plateau fracture, and got successfully treated with a fresh large osteochondral shell allograft transplantation in a two-step procedure.

The effects of low-dose radiotherapy on fresh osteochondral allografts: An experimental study in rabbits

Objective

The aim of this study was to investigate the effects of low-dose fractionated radiotherapy on cartilage degeneration after distal femoral fresh massive osteochondral allograft transplantation.

Methods

Twenty-four New Zealand White rabbits were divided into three groups of 8 rabbits each. All rabbits underwent distal femoral medial condyle fresh massive osteochondral allograft transplantation from California rabbits. The group 1 underwent transplantation without any preliminary process. The group 2 underwent fractionated local radiotherapy of 100 cGy for five days starting on the transplantation day. The group 3 included the rabbits to which the grafts transplanted after radiating in vitro by a single dose radiation of 1500 cGy. The hosts were sacrificed twelve weeks later. Anteroposterior and lateral radiographs were taken. Synovial tissue, cartilaginous tissue, and subchondral bone were assessed histopathologically.

Results

Nonunion was present in three cases of group 2 and one of group 3 in which cartilage degeneration was more severe. Synovial hypertrophy and pannus formation were more obvious in non-radiated rabbits. Hypocellularity and necrosis of the subchondral bone were rare in group 2. More cartilage tissue impairment was present in group 3 compared to group 1.

Conclusion

In osteochondral massive allograft transplantations, the immune reaction of the host could be precluded with radiotherapy, and the side-effects can be prevented by low-dose fractionated regimen. The total dose of fractionated radiotherapy for an immune suppression should be adjusted not to damage the cartilage tissue, but to avoid articular degeneration in the long term.

Cartilage storage at 4 °C with regular culture medium replacement benefits chondrocyte viability of osteochondral grafts in vitro

Maintenance of articular cartilage allografts in culture media is a common method of tissue storage; however, the technical parameters of graft storage remain controversial. In this study, we examined the optimal temperature and culture medium exchange rate for the storage of osteochondral allografts in vitro. Cylindrical osteochondral grafts (n = 120), harvested from the talar joint surface of ten Boer goats, were randomly classified into four groups and stored under the following conditions: Group A1 was maintained at 4 °C in culture medium that was refreshed every 2 days; Group A2 was maintained at 4 °C in the same culture medium, without refreshing; Group B1, was maintained at 37 °C in culture medium that was refreshed every 2 days; Group B2, was maintained at 37 °C in the same culture medium, without refreshing. Chondrocyte viability in the grafts was determined by ethidium bromide/fluorescein diacetate staining on days 7, 21, and 35. Proteoglycan content was measured by Safranin-O staining. Group A1 exhibited the highest chondrocyte survival rates of 90.88 %, 88.31 % and 78.69 % on days 7, 21, and 35, respectively. Safranin O staining revealed no significant differences between groups on days 21 and 35. These results suggest that storage of osteochondral grafts at 4 °C with regular culture medium replacement should be highly suitable for clinical application.

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.

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.

Management of patellofemoral chondral injuries

Treatment of patellofemoral chondral defects is fraught with difficulty because of the generally inferior outcomes and significant biomechanical complexity of the joint. Noyes and Barber-Westin38 performed a systematic review of large (>4 cm2) patellofemoral ACI (11 studies), PFA (5 studies), and osteochondral allografting (2 studies) in patients younger than 50 years. Respectively, failures or poor outcomes were noted in 8% to 60% after ACI, 22% after PFA, and 53% after osteochondral allograft treatment. As noted in the outcome reviews earlier, unacceptable complication and reoperation rates were reported from all 3 procedures, and it was concluded that each operation had unpredictable results for this patient demographic. This study highlights the importance of strict indications and working to address all concomitant diseases to decrease revision rate. Outcomes are most predictable in young patients with low BMI and unipolar defects lower than 4 cm2.

Salvage techniques in osteochondritis dissecans

The central objective in the treatment of any osteochondritis dissecans lesion is to preserve the native articular cartilage and bone. Unfortunately, there are those cases that either fail to heal despite appropriate treatment or present in such a deteriorated state that primary fixation is not possible. This situation is generally determined by the condition of the progeny fragment. Primary fixation may not be the most viable option. In the case of an unsalvageable fragment, the surgeon is faced with several options, which are discussed in this article.

Use of large osteochondral allografts in reconstruction of traumatic uncontained distal femoral defects

Large osteoarticular injuries with subchondral bone loss involving the knee in young active patients often result in significant morbidity and loss of normal joint function. A review of the current literature reveals that multiple surgical management options are currently employed, however there is no consensus on standard of care. Osteochondral allografting provides an attractive alternative treatment option for the repair of large articular defects of the knee.

METHODS

In this article we present the case of a young male who suffered traumatic intraarticular bone loss secondary to a grade IIIA distal femoral fracture and subsequently underwent reconstruction of his medial femoral condyle using a fresh-frozen osteochondral allograft.

RESULTS

We present the radiographic and functional outcome of this patient at two years post-operative. The range of motion of the knee was 0-130° and the patient's post-operative functional outcome was evaluated using the Knee injury and Osteoarthritis Outcome Score (KOOS), which was 76%.

CONCLUSIONS

While further research is required, the results of our case study concur with the current body of literature supporting the use of fresh-frozen osteochondral allograft as a reconstructive option for treating large traumatic intraarticular lesions involving the distal femur.