Autologous osteochondral grafting has demonstrated positive outcomes for treating articular cartilage defects by replacing the damaged region with a cylindrical graft consisting of bone with a layer of cartilage, taken from a non-loadbearing region of the knee. Despite positive clinical use, factors that cause graft subsidence or poor integration are relatively unknown. The aim of this study was to develop finite element (FE) models of osteochondral grafts within a tibiofemoral joint and to investigate parameters affecting osteochondral graft stability. Initial experimental tests on cadaveric femurs were performed to calibrate the bone properties and graft-bone frictional forces for use in corresponding FE models, generated from µCT scan data. The effects of cartilage defects and osteochondral graft repair were measured by examining contact pressure changes using in vitro tests on a single cadaveric human tibiofemoral joint. Six defects were created in the femoral condyles which were subsequently treated with osteochondral autografts or metal pins. Matching µCT scan-based FE models were created, and the contact patches were compared. Sensitivity to graft bone properties was investigated. The bone material properties and graft-bone frictional forces were successfully calibrated from the initial tests with good resulting levels of agreement (CCC=0.87). The tibiofemoral joint experiment provided a range of cases to model. These cases were well captured experimentally and represented accurately in the FE models. Graft properties relative to host bone had large effects on immediate graft stability despite limited changes to resultant cartilage contact pressure. Model confidence was built through extensive validation and sensitivity testing, and demonstrated that specimen-specific properties were required to accurately represent graft behaviour. The results indicate that graft bone properties affect the immediate stability, which is important for the selection of allografts and design of future synthetic grafts. Acknowledgements. Supported by the EPSRC-EP/P001076

Articular cartilage is often damaged, and its treatment is usually performed by surgical operation. Today, tissue engineering offers an alternative treatment option for injuries or diseases with increasing importance. Infrapatellar fat pad (IPFP) is a densely vascularized and innervated extra synovial tissue that fills the anterior knee compartment. Adipose-derived stem cells from infrapatellar fat pad (IPFP-ASCs) have multipotency means that they can differentiate into connective tissue cells and have age-independent differentiation capacity as compared to other stem cells. In this study, the osteochondral tissue construct was designed with different inner pattern due to original osteochondral tissue structure and fabrication of it was carried out by 3D printing. For this purpose, alginate (3% w/v) and carboxymethylcellulose (CMC) (9%w /v) were used as bioink. Also, IPFP-ASCs were isolated with enzymatic degradation. Osteogenic and chondrogenic differentiation of IPFP-ASCs were investigated with Alizarin Red and Alcian Blue staining, respectively. IPFP-ASCs-laden osteochondral graft differentiation will be induced by controlled release of growth factor BMP-2 and TGF-β. Before this step, nanocapsules formation with double emission technique with model protein BSA was carried out with different concentration of PCL (5%,10% and 20%). The morphology and structure of the nanocapsules were determined with scanning electron microscopy (SEM). Also, we successfully designed and printed alginate and CMC based scaffold with 20 layers. Chondrogenic and osteogenic differentiation of IPFP-ASCs with suitable culture conditions was obtained. The isolation of IPFP-ASCs, formation of the nanocapsules, and 3D printing of osteochondral graft were carried out successfully

Background:. Full thickness cartilage defect of the knee frequently resulted in fibrous tissue formation, and larger lesions often lead to degenerative arthritis of the knee. Many techniques are designed to repair the cartilage defect including chondrocyte transplantation, microfracture and osteochondral graft. Each method has achieved some success but no universal results. Autologus osteochondral graft has gained in clinical popularity because of its technical feasibility and cost effectiveness. Purpose:. The purpose of this retrospective study was to evaluate the medium-term results of autologous osteochondral graft for focal contained articular cartilage defects of the knee in 25 patients with 26 knees with 2- to 7-year follow-up. Patients and Methods:. The cohort consisted of 17 men and 8 women with an average age of 31.3 ± 11.8 (range 20 to 65) years. One patient had bilateral knees. The diagnosis included 9 osteonecrosis, 10 osteochondritis dessicans, and 7 traumatic defects. A 1.0 mm oversized 10 mm long ossteochondral plug was harvested from either from the sulcus terminalis or the intercondylar notch, and implanted into the recipient site The numbers of osteochondral plug ranged from 1 to 3. In larger lesions, osteochondral grafts were implanted in the weight bearing area, and microfracture in non-weight bearing area. Postoperative management included crutch walking with non-weight bearing for 6 weeks, then partial weight bearing for another 6 weeks before full weight bearing. Range of knee motion, quadriceps and hamstring strengthening exercises were encouraged. The evaluations included functional assessment, radiograph of the knee and second look arthroscopy. Results:. At follow-up of 52.9 ± 20.3 (range 25 to 84) months, the results were 50% excellent, 35% good, 11% fair and 4% poor. Overall satisfactory results were noted in 85%. The improvements in pain and function of the knee ranged from 8 to 16 weeks after surgery. There was no correlation of the clinical results with the diagnosis of the lesion. However, the lesion size greater than 500 mm. 2. is associated with failure. Radiographic degenerative changes were noticed in 6 (23%) and 7 (27%) in medial compartment, 5 (19%) and 5 (19%) in lateral compartment, and 1 (4%) and 2 (8%) in the patellofemoral compartment pre- and postoperatively (P > 0.05). Twelve knees underwent a second look arthroscopy. Of the 11 asymptomatic knees, 8 knees with the defect smaller than 500 mm. 2. showed complete bonding of the graft to the adjacent host cartilage, and 3 cases showed minimal fissuring and fibrous tissue formation between graft and host tissue. One symptomatic knee with greater than 500 mm. 2. lesion showed extensive fibrous tissue between the graft and host cartilage. Conclusion:. Autologous osteochondral graft provides good or excellent results in 85% of patients with focal contained chondral and osteochondral defects of the knee. There was no correlation of the clinical results with the nature of the disease and the size of the lesion smaller than 500 mm. 2. Any lesion larger than 500 mm. 2. is prone to poor clinical outcome

Osteochondral (OC) grafting is one available method currently used to repair full thickness cartilage lesions with good results clinically when grafting occurs in patients with specific positive prognostic factors. However, there is poor understanding of the effect of individual patient and surgical factors. With limited tissue availability, development of Finite Element (FE) models taking into account these variations is essential. The aim of this study was to evaluate the effect of altering the material properties of OC grafts and their host environment through computer simulation. A generic FE model (ABAQUS CAE 2017) of a push-out test was developed as a press-fit bone cylinder (graft) sliding inside a bone ring (host tissue). Press-fit fixation was simulated using an interference fit. Overlap between host and graft (0.01mm–0.05mm) and coefficient of friction (0.3–0.7) were varied sequentially. Bone Young's moduli (YM) were varied individually between graft and host within the range of otherwise derived tissue moduli (46MPa, 82MPa, 123MPa). Increasing both overlap and frictional coefficient increased peak dislodging force independently (overlap: 490% & frictional coefficient: 176% across range tested). Increasing bone modulus also increased dislodging force, with host bone modulus (107%, 128%, and 140% increase across range, when Graft YM = 123MPa, 82 MPa, and 46MPa, respectively) having a greater influence than graft modulus (28%, 19% and 10% increase across range, when Host YM = 123 MPa, 82MPa and 46MPa, respectively). As anticipated increasing overlap and friction caused an increase in force necessary to dislodge the graft. Importantly, differentially changing the graft and host material properties changed the dislodging force indicating that difference between graft and host may be an important factor in the success or failure clinically of osteochondral grafting

Twelve patients with an osteochondral lesion of the talus were treated with local osteochondral autogenous grafting. The graft was harvested locally from the medial or lateral talar articular facet. The procedure was combined with an osteotomy of the anterior tibial plafond modifying the technique of Flick and Gould. The average age of the patients was 41 years (range 19 to 68) with an average duration of symptoms of 90 months (range 3 – 240 months). There were six males and six females with the right talus involved in eight and the left in four patients. Results showed an improvement in the AOFAS score from an average of 69 pre-operatively to 90.2 post-operatively, at an average follow up of 15 months (range 6 to 31 months). The results tended to improve with time and was higher for patients under 40 years of age and in those without pre-existing joint arthritis. All patients were very satisfied with the procedure. Arthroscopy performed in two patients at six and 12 months following surgery showed good graft incorporation. No complications were seen from the donor site or from the osteotomy site on the distal tibia. Our results show that stage III and IV talar lesions can be treated successfully using local autogenous osteochondral graft from the medial or lateral talar articular facet

Introduction Twelve patients with an osteochondral lesion of the talus were treated with excision of the lesions and local osteochondral autogenous grafting. Methods The lesion was accessed through a replaceable bone block removed from the anterior tibial plafond. The graft was harvested from the medial or lateral talar articular facet on the same side of the lesion. The average age of the patients was 41 years and duration of symptoms was 90 months (average). There were six males and six females with the right talus involved in eight and the left in four patients. Graft sizes ranged from four to eight millimetres in diameter. Results There was a significant improvement in the AOFAS score from 64.4 (average) pre-operatively to 90.8 (average post-operatively (p< 0.0001) at follow-up of 25.3 months (average). The AOFAS score was slightly higher in patients under 40 years of age and in those without pre-existing joint arthritis. All patients were very satisfied with the procedure. Arthroscopy performed in two patients at six and 12 months following surgery showed good graft incorporation. No complications occurred at the donor site or the site of the bone block removal on the distal tibia. Conclusions The results showed that stage III and stage IV talar osteochondral lesions can be accessed successfully excising a tibial bone block and using local autogenous osteochondral graft harvested from the ipsilateral talar articular facet. In relation to the conduct of this study, one or more of the authors has received, or is likely to receive direct material benefits

To assess the use of autogenous osteochondral graft fixation (mosaicplasty) in unstable osteochondritis dissecans (OCD) lesions (Clanton type 2 and 3) of the knee. Eleven patients with x-ray and N4R1 confirmed OCD lesion in their femoral condyle, that had remained symptomatic despite adequate conservative treatment, underwent arthroscopic mosaicplasty plug fixation of the lesion. The OCD lesions were all loose at operation and were all fixed rigidly in situ. using a number of autogenous 4. 5min osteochondral plugs harvested from the edge of the trochlear groove. The patients were prospectively assessed both clinically and by MRI scan at 3, 6 and 12 months and then six monthly. Average follow up was 2. 7 years (2 – 4. 1). Prior to operation all patients had joint effusions and were experiencing pain limiting their activities. By 6 months post-operation the IKDC score had returned to normal in all cases and none of the patients had joint effusions or pain. Serial NHU scans documented healing of the osteochondral plugs and a continuous articular cartilage surface layer in all cases by 9 months. Using mosaicplasty plug fixation we were able to obtain healing in all 1 1 unstable OCD lesions. The benefits of this technique are the ability to obtain rigid stabilization of the fragment using multiple plugs, stimulation of the subchondral blood supply and autogenous cancellous bone grafting. We conclude that mosaic-plasty plug fixation of unstable OCD lesions in the knee is a good technique and recommend its use. Eleven patients with an unstable osteochondritis dissecans lesion (OCD) in their femoral condyle underwent in situ arthroscopic osteochondral graft fixation (mosaicplasty) of the lesion using a number of 4. 5min plugs harvested from the trochlear groove. By 6 months follow-up all of the patients were pain free with no joint effusion and by 9 months all had NW evidence of plug healing and continuous articular cartilage coverage. The benefits of this technique are the ability to obtain rigid stabilization, stimulation of the subchondral blood supply and cancellous bone grafting. We conclude that mosaic-plasty fixation of OCD lesions is a useful technique

Purpose: We report the results of a prospective consecutive series of 25 patient with non-degenerative chondral lesions treated by mosaicplasty osteochondral grafts. Material and method: The main group was composed of 22 knees, including 16 with osteochonritis dissecans, five with cartilage damage concomitant with chronic anterior laxity, and one with necrosis of the medial condyle. The other lesions involved the talus. Mean patient age was 28 years. Mean follow-up was 13 months (range 1 – 39 months). Among the knee group, 15 patients underwent standard mosaicplasty. The lesion measured 1.96 cm2 on the average. For the other cases, associated procedures included: valgus tibial osteotomy (n=4), anterior ligamentoplasty (n=3). There were few complications except one case of infection. Clinical assessment was based on the new ICRS chart (with an updated IKDC subjective score sheet). The subjective IKDC score was 48.7% preoperatively. Results: Mean coverage of the lesion was 68.5%. Solitary mosaicplasty provided good results. The subjective IKDC score was 67.5% and 77% of the patients experienced little or no pain in their knee. Two-thirds of the patients scored their performance at 8 or more on the 10 point scale. The objective IKDC score gave 11/15 A and 4/15 B. There was one complication related to the donor site causing femoropatellar impingement after harvesting substantial graft material. Recovery was more difficult for patients with associated procedures and results were less satisfactory. All patients underwent an MRI at six months that showed in general a good morphological aspect. Discussion: The technique used is particularly important due to a number of pitfalls and difficulties requiring much surgical skill. While we have found that most associated procedures such as grafting the anterior cruciate ligament are warranted, the appropriateness of an associated osteotomy would be highly debatable. Lesions measuring more than 3 cm2 correspond to the limit of this technique. Conclusion: Mosaicplasty is a reliable method for cartilage repair. Long-term assessment will allow better indications and identification of any iatrogenic factors in order to determine the appropriate place for this technique among the other methods used for cartilage repair

Measurement of precision in positioning multiple autologous osteochondral transplantation in comparison to the conventional free hand technique. The articular surfaces of 6 cadaveric condyles (medial – lateral) were used. The knee was referenced by a navigation system (Praxim). The pins carrying the navigation detectors were positioned to the femur and to the tibia. The grafts were taken from the donor side (measurement I) with the special instrument which carried the navigation detectors. The recipient site was prepared and the donor osteochondral grafts were forwarded to the articular surface (II). The same procedure took place without navigation. The articular surface congruity was measured with the probe (measurement III). The angle of the recipient plug removal (measurement I) with the navigation technique was 3,27° (SD 2,05°; 0°–9°). The conventional technique showed 10,73° (SD 4,96°; 2°–17°). For the recipient plug placement (measurement II) under navigated control a mean angle of 3,6° (SD 1,96°; 1°–9°) was shown, the conventional technique showed results with a mean angle of 10,6° (SD 4,41°; 3°–17°). The mean depth (measurements III) under navigated control was 0,25mm (SD 0,19mm; 0mm–0,6mm). With conventional technique the mean depth was 0,55mm (SD 0,28mm; 0,2mm –1,1mm). The application of navigation showed that complications like diverging of the grafts leading to breakage or loosening as well as depth mismatch which can lead to grafts sitting over or under the articular surface can be avoided providing better results in comparison to the free hand procedure

Background

Based on decellularisation and cleaning processes of trabecular bone and fibrocartilage, an osteochondral allograft has been developed.

Introduction

Articular hyaline cartilage has a unique structural composition that allows it to endure high load, distribute load to bone and enables low friction movement in joints. A novel acellular xenogenic graft is proposed as a biological cartilage replacement, for repair of osteochondral defects. Acellular porcine cartilage has been produced using repeated freeze thaw cycles and washing using hypotonic buffers and sodium dodecyl sulphate solution (SDS; Keir, 2008). DNA content of the acellular matrix was reduced by 93.3% compared to native cartilage as measured by nanodrop spectrophotometry of extracted DNA, with a corresponding reduction in glycosaminoglycan (GAG) content.

Autologous osteochondral cylinder transfer is a treatment option for small articular defects, especially those arising from trauma or osteochondritis dissecans. There are concerns about graft integration and the nature of tissue forming the cartilage-cartilage bridge. Chondrocyte viability at graft and recipient edges is thought to be an important determinant of quality of repair. The aim was to evaluate cell viability at the graft edge from ex vivo human femoral condyles, after harvest using conventional technique. With ethical approval and patient consent, fresh human tissue was obtained at total knee arthroplasty. Osteochondral plugs were harvested using the commercially available Acufex 4.5mm diameter mosaicplasty osteotome from regions of the lateral femoral condyle (anterior cut) that were macroscopically non-degenerate and microscopically non-fibrillated. Plugs were assessed for chondrocyte viability at the graft edge using confocal laser scanning microscopy (CLSM), fluorescent indicators and image analysis. The central portions of the plugs remained healthy, with > 99% cell viability (n=5). However, there was substantial marginal cell death, of thickness 382 ± 68.2 microm in the superficial zone (SZ). Demi-plugs were created by splitting the mosaicplasty explants with a fresh No. 11 scalpel blade. The margin of SZ cell death was 390.3 ± 18.8 microm at the curved edge of the Acufex, significantly (Mann-Whitney; P= 0.0286; n =4) greater than that at the scalpel cut (34.8 ± 3.2 microm). Findings were similar when the cartilage was breached but the bone left intact. In time-course experiments, the SZ marginal zone of cell death after Acufex harvest showed no increase over the time period 15 minutes to 2 hours. Mathematical modelling of the mosaicplasty surface shows that cell death of this magnitude results in a disturbing 33% of the superficial graft area being non-viable. In conclusion, mosaicplasty, though capable of transposing viable hyaline cartilage, is associated with an extensive margin of cell death that is likely to compromise lateral integration. There would appear to be considerable scope for improvement of osteochondral transplant techniques which may improve graft-recipient healing and clinical outcomes.

The clinical success of osteochondral autografts is heavily reliant on their mechanical stability, as grafts which protrude above or subside below the native cartilage can have a negative effect on the tribological properties of the joint [1]. Furthermore, high insertion forces have previously been shown to reduce chondrocyte viability [2]. Commercial grafting kits may include a dilation tool to increase the diameter of the recipient site prior to insertion. The aim of this study was to evaluate the influence of dilation on the primary stability of autografts. Six human cadaveric femurs were studied. For each femur, four 8.5 × 8mm autografts were harvested from the trochlear groove and implanted into the femoral condyles using a Smith & Nephew Osteochondral grafting kit. Two grafts were implanted into dilated recipient sites (n=12) and two were implanted with no dilation (n=12). Insertion force was measured by partially inserting the graft and applying a load at a rate of 1 mm/min, until the graft was flush with the surrounding cartilage. Push-in force was measured by applying the same load, until the graft had subsided 4mm below congruency. Significance was taken as (p<0.05). Average maximum insertion force of dilated grafts was significantly lower (p<0.001) than their non-dilated equivalent [28.2N & 176.7N respectively]. There was no significant difference between average maximum push-in force between the dilated and non-dilated groups [1062.8N & 1204.2N respectively]. This study demonstrated that significantly less force is required to insert dilated autografts, potentially minimising loss of chondrocyte viability. However, once inserted, the force required to displace the grafts below congruency remained similar, indicating a similar degree of graft stability between both groups

Aims: In recent years more and more studies tried to evaluate possible inßuences of different growth factors on hyaline cartilage regeneration. In a rabbit model, HGF (hepatocyte growth factor) was proven to increase the amount of hyaline-like chondrocytes in a mixed þbrocartilaginous regenerate of small defects. The present study was undertaken to evaluate, whether intraarticular administration of hepatocyte growth factor inßuences the ingrowth of osteochondral grafts in a sheep model. Methods: Both knee joints of a sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral compartment. The sheeps were divided into two groups. In one group hepatocyte growth factor was administered by intraarticular injections given three times a week for four weeks. The control group received isotonic sodium chloride injections. The animals were sacriþced after three months and the received knee joints were evaluated histologically. Results: Histological evaluation showed that the autologous osteochondral grafts were healed in at the level of the subchondral bone. A healing or ingrowth at the level of the cartilage could not be observed. Anyway, histological evaluation of the transplanted grafts according to Mankin showed, that the cartilage of the HGF group showed less signs of degeneration than the control group. In the HGF group less cloning of chondrocytes and less irregularities of the articular surface were observed. Conclusion: In conclusion, HGF positively inßuenced the structure of the transplanted osteochondral graft, but could not diminish the þssures in the marginal zone of the grafts

The outcomes of various operative methods for osteochondritis dissecans of the femoral condyles were reviewed, and choice of these operative methods were discussed. Twenty-four cases (19 males and 5 females) which underwent operative treatments were reviewed. The operative methods included drilling, repositioning and fixation of the osteochodral fragment, and bone graft or osteochondral graft. The minimum follow-up period was two years. The medial femoral condyle was involved in 17 cases, and the lateral, in seven. Lateral discoid meniscus or meniscal injury was combined in all the 7 cases in the lateral. The operative methods were decided from the condition of the cartilage. Drilling was performed in cases with no or minimal cartilage damages (10 cases). Repositioning (if required) and fixation of the fragment using absorbable pins was carried out in cases with a partial or total fragmentation (7 cases). Bone graft or osteochondral graft was performed when the original site was already degenerated (7 cases). Partial meniscectomy was added when the meniscal injury was combined. In patients who received drilling, the lesion healed radiographically in all the cases and they complained of no or minimal symptoms. In patients who received the fragment fixation, re-union of the fragment was observed in 71% and the clinical outcomes were satisfactory in most of the cases. In patients who received bone graft or osteochondral graft, although union of the graft was observed in all the cases radiographically, 71% of the patients complained of residual pain. From the results, drilling is sufficient if the cartilage surface is not damaged. When the fragmentation occurred already, the fragment should be repositioned and fixed to the original site before degenerated, as its clinical symptoms were much better than those with bone graft or osteochondral graft

Shoulder arthritis in the young adult is a deceptive title. The literature is filled with articles that separate outcomes based on an arbitrary age threshold and attempt to provide recommendations for management and even potential criteria for implanting one strategy over another using age as the primary determinant. However, under the age of 50, as few as one out of five patients will have arthritis that can be accurately classified as osteoarthritis. Other conditions such as post-traumatic arthritis, post-surgical arthritis including capsulorrhaphy arthropathy, and rheumatoid arthritis create a mosaic of pathologic bone and soft tissue changes in our younger patients that distort the conclusions regarding “shoulder arthritis” in the young adult. In addition, we are now seeing more patients with unique conditions that are still poorly understood, including arthritis of the pharmacologically performance-enhanced shoulder. Early arthritis in the young adult is often recognised at the time of arthroscopic surgery performed for other preoperative indications. Palliative treatment is the first option, which equals “debridement.” If the procedure fails to resolve the symptoms, and the symptoms can be localised to an intra-articular source, then additional treatment options may include a variety of cartilage restoration procedures that have been developed primarily for the knee and then subsequently used in the shoulder, including microfracture, and osteochondral grafting. The results of these treatments have been rarely reported with only case series and expert opinion to support their use. When arthritis is moderate or severe in young adults, non-arthroplasty interventions have included arthroscopic capsular release, debridement, acromioplasty, distal clavicle resection, microfracture, osteophyte debridement, axillary nerve neurolysis, and bicep tenotomy or tenodesis, or some combination of these techniques. Again, the literature is very limited, with most case series less than 5 years of follow-up. The results are typically acceptable for pain relief, some functional improvement, but not restoration to completely normal function from the patient's perspective. Attempts to resurface the arthritic joint have resulted in limited benefits over a short period of time in most studies. While a few remarkable procedures have provided reasonable outcomes, they are typically in the hands of the developer of the procedure and subsequently, other surgeons fail to achieve the same results. This has been the case with fascia lata grafting of the glenoid, dermal allografts, meniscal allografts, and even biologic resurfacing with large osteochondral grafts for osteoarthritis. Most surgical interventions that show high value in terms of improvement in quality of life require 10-year follow-up. It is unlikely that any of these arthroscopic procedures or resurfacing procedures will provide outcomes that would be valuable in terms of population healthcare; they are currently used on an individual basis to try to delay progression to arthroplasty, with surgeon bias based on personal experience, training, or expert opinion. Arthroplasty in the young adult remains controversial. Without question, study after study supports total shoulder arthroplasty over hemiarthroplasty once the decision has been made that joint replacement is the only remaining option

Osteochondral allografts (frozen uncontrolled, or cryo-protected with dimethyl sulfoxide) were transplanted into medial femoral condyles of eighteen sheep. Cores from the ipsilateral graft site served as autografts for the contralateral limb. Analysis of graft and host cancellous bone microarchitecture by μCT at three months post transplant demonstrated no significant differences among the treatment groups. Dramatic bone resorption at the graft–host interface, however, occurred in up to 1/3 of condyles from all treatment groups, including fresh autografts suggesting that factors other than donor source or tissue storage played an important role in the bone incorporation of osteochondral grafts. The purpose of this study was to study the effect of different freezing protocols on periarticular cancellous bone architecture after osteochondral allograft transplantation. There were no significant differences in graft or host cancellous bone architecture among the groups (autografts, frozen allografts, cryopreserved allografts). Dramatic resorption of graft bone in condyles from all treatment groups suggested that factors other than donor source or tissue storage played important roles during incorporation of osteochondral grafts. Graft positioning, graft orientation, and recipient bed necrosis may play significant roles during incorporation of osteochondral graft bone. Osteochondral allografts (10 mm diameter) were transplanted into medial femoral condyles of eighteen skeletally mature Suffolk ewes. Allografts were frozen (–80°C) without cryoprotectant (FROZ) or treated with dimethyl sulfoxide (cryoprotectant) and frozen (–80°C at 1°C · min. −1. ) (CRYO). Osteochondral cores removed from ipsilateral graft sites served as fresh autografts (AUTO) for the contralateral medial femoral condyles. Condyles were harvested at three months and scanned (micro computed tomography –μCT). Three dimensional μCT data of graft and host cancellous bone regions were analyzed for bone volume fraction, trabecular thickness, bone surface–volume ratio, and trabecular anisotropy. No morphological differences were found among treatment groups. Excessive bone resorption of graft and interface precluded analysis of some samples from each group (ALLO — 2/9, CRYO — 3/9, AUTO — 6/18). Dramatic bone loss did not correlate with poor graft orientation, placement, infection, or recipient–bed necrosis, but a combination of these factors may contribute to excessive cancellous bone resorption in osteochondral grafts. Funding: Medical Research Council of Canada, Canadian Institutes of Health Research, No commercial funding. Please contact author for figures and/or diagrams

Introduction and Objectives: Osteochondral lesions of the talus are difficult to treat due to difficult access, vascularisation, and because the head of the talus is a region with significant mechanical load. Among the therapeutic options for osteochondral lesions of the head of the talus, we present a treatment alternative using mosaicplasty with an autologous osteochondral graft taken from the knee. Materials and Methods: We have treated 8 patients affected with osteochondral lesions of the head of the talus (7 medial and 1 lateral) of greater than 7mm diameter, younger than 45 years of age, and with no instability of the ligament. The talus was approached in all cases by means of osteotomy of the malleolus. Osteocartilaginous cores were collected from the ipsilateral lateral condyle of the ipsilateral knee with minimal arthrotomy. Rehabilitation began between days 3 and 5 with no weight bearing before the 6th week. Results were measured by means of CTscan, MRI, and pathology, and clinically using the Maryland scale. Results: All patients presented with evidence of osteointegration of the osteochondral graft. All were classified as excellent or good on the Maryland scale. Functional results were good with flexion and extension movements of the ankle practically symmetrical with the healthy limb. There were no complications in the donor site or infections. None of the patients has required repeat treatment except in the cases in which material for osteosynthesis was removed from the malleolus. Discussion and Conclusions: We believe that in view of the results of mosaicplasty with an autologous osteochondral graft taken from the knee, this provides a new therapeutic approach to treatment of grade III and IV osteochondral lesions of the talus. The most significant advantages of this technique include the repair of articular cartilage with type II collagen and an earlier discharge time due to osseous integration. The most important disadvantages were potential morbidity associated with the donor site and the technical difficulty in achieving convexity

Purpose: To evaluate repair of articular cartilage. Methods: Ten cases of ten knees (6 males and 4 females) were evaluated in the current study. Seven knees treated by osteochondral graft including six receiving mosaic plasty and one receiving Pasteurization. Four knees treated by periosteal graft. One knee received both mosaicplasty and periosteal graft. Mean patient age at surgery was 31 years old. Eight knees underwent follow-up MRI, 6 knees underwent follow-up arthroscopy, and 4 knees underwent needle biopsy after informed consent was obtained. The mean period from the surgery to final follow-up was 21 months. The mean period from surgery to follow-up arthroscopy was 10 months. Results: Seven cases of osteochondral graft presented good regeneration of articular surface by MRI and arthroscopic examination. Two knees receiving mosaic plasty demonstrated regeneration of hyaline cartilage even between the gaps in mosaicplasty. However, the structure of hyaline cartilage differed from that of normal cartilage. Pasteurization in one case also demonstrated good regeneration of hyaline cartilage. One knee treated by periosteal graft demonstrated regeneration of hyaline cartilage. However, the graft area in another such knee was covered by fibrous tissue. One periosteal graft became detached 14 days after surgery. There were no cases showing ossification after periosteal graft. Conclusion: Periosteal graft could cover a wide defect of articular surface. However, induction of cartilage was not good. Osteochondral graft is a sure method of repairing hyaline cartilage where there is a small defect in the articular surface. Our results from needle biopsy demonstrated hyaline cartilage in the gaps among mosaicplasty areas, but the structure of hyaline cartilage was not good. There is a risk of re-degeneration due to the poor structure of hyaline cartilage. Careful observation is needed in both periosteal graft and mosaic plasty cases

Abstract. Objectives. Osteochondral grafting (OCG) is one treatment strategy for osteoarthritis with good clinical results. Decellularised tissues provide a promising alternative to standard autografts or allografts. This study aimed to compare the stability of traditional OCG and decellularised scaffolds upon initial implantation. Methods. Host cubes (N=16) were extracted from porcine femoral condyles around an artificial defect hole. Grafts (N=11) were harvested from the trochlear groove; porcine decellularized osteochondral scaffold (N=5) were prepared. Each host was secured in fixtures and submerged in PBS at 37 ºC. Each graft or scaffold was press fit into one of the hosts, then pushed in for 5 mm, using an indenter (Instron3365) and pushed out in the opposite direction for 10 mm. Parameters analysed were the force required to initiate movement (Dislodging Force) and the maximum force (Max Force). Results. The Dislodging Force of grafts (mean ± std. dev) was 133±15 N for the push in test and 109±11 N for the push out test. This was significantly higher than values for scaffolds: IN 24±1 N and OUT 26±5 N. The Max Force were also larger in the grafts than the scaffolds: IN 152±16 N vs. 41±4 N and OUT 118±14 N vs. 33±3 N. Conclusions. The force required to dislodge a graft or scaffold from a host environment was similar for the push in test and the push out test, suggesting it is a good measure of initial stability. Upon initial implantation, the decellularised scaffolds were easier to dislodge than the OCG. Previously, the decellularisation process was found to soften bone, relative stiffness may thus be an important consideration in graft fixation. A greater press fit may be necessary for decellularised scaffolds in order to achieve the same level of graft stability as natural OCG when used in vivo. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project