Aims. To systematically review the predominant complication rates and changes to patient-reported outcome measures (PROMs) following osteochondral allograft (OCA) transplantation for shoulder instability. Methods. This systematic review, following PRISMA guidelines and registered in PROSPERO, involved a comprehensive literature search using PubMed, Embase, Web of Science, and Scopus. Key search terms included “allograft”, “shoulder”, “humerus”, and “glenoid”. The review encompassed 37 studies with 456 patients, focusing on primary outcomes like failure rates and secondary outcomes such as PROMs and functional test results. Results. A meta-analysis of primary outcomes across 17 studies revealed a dislocation rate of 5.1% and an increase in reoperation rates from 9.3% to 13.7% post-publication bias adjustment. There was also a noted rise in conversion to total shoulder arthroplasty and incidence of osteoarthritis/osteonecrosis over longer follow-up periods. Patient-reported outcomes and functional tests generally showed improvement, albeit with notable variability across studies. A concerning observation was the consistent presence of allograft resorption, with rates ranging from 33% to 80%. Comparative studies highlighted similar efficacy between distal tibial allografts and Latarjet procedures in most respects, with some differences in specific tests. Conclusion. OCA transplantation presents a promising treatment option for shoulder instability, effectively addressing both glenoid and humeral head defects with favourable patient-reported outcomes. These findings advocate for the inclusion of OCA transplantation in treatment protocols for shoulder instability, while also emphasizing the need for further high-quality, long-term research to better understand the procedure’s efficacy profile. Cite this article: Bone Jt Open 2024;5(7):570–580

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

Large cartilage lesions in younger patients can be treated by fresh osteochondral allograft transplantation, a surgical technique that relies on stable initial fixation and a minimum chondrocyte viability of 70% in the donor tissue to be successful. The Missouri Osteochondral Allograft Preservation System (MOPS) may extend the time when stored osteochondral tissues remain viable. This study aimed to provide an independent evaluation of MOPS storage by evaluating chondrocyte viability, chondrocyte metabolism, and the cartilage extracellular matrix using an ovine model. Femoral condyles from twelve female Arcott sheep (6 years, 70 ± 15 kg) were assigned to storage times of 0 (control), 14, 28, or 56 days. Sheep were assigned to standard of care [SOC, Lactated Ringer's solution, cefazolin (1 g/L), bacitracin (50,000 U/L), 4°C storage] or MOPS [proprietary media, 22-25°C storage]. Samples underwent weekly media changes. Chondrocyte viability was assessed using Calcein AM/Ethidium Homodimer and reported as percent live cells and viable cell density (VCD). Metabolism was evaluated with the Alamar blue assay and reported as Relative Fluorescent Units (RFU)/mg. Electromechanical properties were measured with the Arthro-BST, a device used to non-destructively compress cartilage and calculate a quantitative parameter (QP) that is inversely proportional to stiffness. Proteoglycan content was quantified using the dimethylmethylene blue assay of digested cartilage and distribution visualized by Safranin-O/Fast Green staining of histological sections. A two-way ANOVA and Tukey's post hoc were performed. Compared to controls, MOPS samples had fewer live cells (p=0.0002) and lower VCD (p=0.0004) after 56 days of storage, while SOC samples had fewer live cells (p=0.0004, 28 days; p=0.0002, 56 days) and lower VCD (p=0.0002, 28 days; p=0.0001, 56 days) after both 28 and 56 days (Table 1). At 14 days, the percentage of viable cells in SOC samples were statistically the same as controls but VCD was lower (p=0.0197). Cell metabolism in MOPS samples remained the same over the study duration but SOC had lower RFU/mg after 28 (p=0.0005) and 56 (p=0.0001) days in storage compared to controls. These data show that MOPS maintained viability up to 28 days yet metabolism was sustained for 56 days, suggesting that the conditions provided by MOPS storage allowed fewer cells to achieve the same metabolic levels as fresh cartilage. Electromechanical QP measurements revealed no differences between storage methods at any individual time point. QP data could not be used to interpret changes over time because a mix of medial and lateral condyles were used and they have intrinsically different properties. Proteoglycan content in MOPS samples remained the same over time but SOC was significantly lower after 56 days (p=0.0086) compared to controls. Safranin-O/Fast Green showed proteoglycan diminished gradually beginning at the articular surface and progressing towards bone in SOC samples, while MOPS maintained proteoglycan over the study duration (Figure 1). MOPS exhibited superior viability, metabolic activity and proteoglycan retention compared to SOC, but did not maintain viability for 56 days. Elucidating the effects of prolonged MOPS storage on cartilage properties supports efforts to increase the supply of fresh osteochondral allografts for clinical use. For any figures or tables, please contact the authors directly

Articular defects in the knee can be managed by surface treatments, cartilage cell transplantation, periosteal grafts, osteochondral autografts, and osteochondral allografts. The factors, which determine the most appropriate treatment, are the size of the defect, and the associated bone loss. If there is an associated deformity, all of the aforementioned techniques would be combined with osteotomy. Chondral defects with no significant bone involvement can be managed arthroscopically by surface treatments like debridement and drilling, abrasion arthroplasty, and microfracture. Chondral defects can also be managed arthroscopically by osteochondral autografts (mosaicplasty) or by cartilage cell transplant or periosteal grafts, both of which are done by open surgery. The arthroscopic surface treatments are best reserved for small defects but cell transplantation and mosaicplasty have been used for defects up to 2 cm in diameter. Periosteal grafting can be used for large defects affecting an entire condyle, but clinical experience with this procedure is limited and it is still considered experimental. Articular defects that involve bone can to some degree be treated by mosaicplasty if the bone defect is contained and less than 1 cm in depth. Larger osteochondral defects are managed by osteochondral allografts (uncontained defects greater than 3 cm in diameter and greater than 1 cm in depth). The disadvantage of osteochondral allografting is that it requires an open procedure and there is the potential for disease transmission. The author has published a series of 126 knees in 123 patients with major post-traumatic osteochondral defects treated by allografts. At an average follow-up of 7.5 years the success rate was 85%. Retrieval studies have confirmed hyaline cartilage. In a recent study of 40 patients with femoral condylar grafts for trauma or osteochondritis dissecans, at an average follow-up of 11 years, the survivorship was 80%

Abstract. Background. Osteochondral allograft (OCA) transplantation is a clinically and cost-effective option for symptomatic cartilage defects. In 2017 we initiated a program for OCA transplantation for complex chondral and osteochondral defects as a UK tertiary referral centre. Aim. To characterise the complications, re-operation rate, graft survivorship and clinical outcomes of knee OCA transplantation. Methodology. Analysis of a prospectively maintained database of patients treated with primary OCA transplantation from 2017 to 2021 with a minimum of one-year follow-up. Patient reported outcome measures (PROMs), complications, re-operations and failures were evaluated. Results. 37 patients with 37 knee OCA procedures were included (mean age 31.6 years [16–49 years]). Mean BMI 26.6 kg/m2 (19.1–35.9 kg/m2). The mean chondral defect size was 3cm2 (1.2–7.3 cm2). Mean duration of follow-up was 3.1 years (1–5.3 years). 16 patients underwent meniscal allograft transplantation (MAT), 6 underwent osteotomy and 4 underwent ligament reconstruction as concurrent procedures. Significant improvements in mean PROMs were noted at 12 months. 16 patients had reoperations of which 5 had more than one surgery. Of these patients 6 were related to OCA (mainly debridement and revision OCA in one patient), and the remainder were related to additional procedures including removal of plate in 2 patients. The overall failure rate was 1 in 37 patients (3%). Conclusions. Early experience of OCA as a treatment option for complex chondral and osteochondral lesions in the knee shows satisfactory results. The reoperation rate is high but at mean follow-up of 3.1 years the survival rate was 97%

Many factors have been reported to affect the functional survival of OCA transplants, including chondrocyte viability at time of transplantation, rate and extent of allograft bone integration, transplantation techniques, and postoperative rehabilitation protocols and adherence. The objective of this study was to determine the optimal subchondral bone drilling technique by evaluating the effects of hole diameter on the material properties of OCAs while also considering total surface area for potential biologic benefits for cell and vascular ingrowth. Using allograft tissues that would be otherwise discarded in combination with deidentified diagnostic imaging (MRI and CT), a model of a large shell osteochondral allograft was recreated using LS-PrePost and FEBio based on clinically relevant elastic material properties for cortical bone, trabecular bone, cartilage, and hole ingrowth tissue. The 0.8 mesh size model consisted of 4 mm trabecular bone, 4 mm cortical bone, and 3 mm cartilage sections that summed to a cross-sectional area of 1600 mm2 (40 mm x 40 mm). Holes were modeled to be 4mm deep in relation to clinical practice where holes are drilled from the deep margin of subchondral trabecular bone to the cortical subchondral bone plate. To test the biomechanic variations between drill hole sizes, models with hole sizes pertinent to standard-of-care commercially available orthopaedic drill sizes of 1.1mm, 2.4 mm, or 4.0 mm holes were loaded across the top surface over a one second duration and evaluated for effective stress, effective strain, 1st principal strain, and 3rd principal strain in compressive conditions. Results measured effective stress and strain and 1st and 3rd principal strain increased with hole depth. The results of the present FEA modeling study indicate that the larger 4.0 mm diameter holes were associated with greater stresses and strains within OCA shell graft, which may render the allograft at higher risk for mechanical failure. Based on these initial results, the smaller diameter 2.4 mm and 1.1 mm holes will be further investigated to determine optimal number, configuration, and depth of subchondral drilling for OCA preparation for transplantation

Aims. The aim of this study was to report the outcome of femoral condylar fresh osteochondral allografts (FOCA) with concomitant realignment osteotomy with a focus on graft survivorship, complications, reoperation, and function. Patients and Methods. We identified 60 patients (16 women, 44 men) who underwent unipolar femoral condylar FOCA with concomitant realignment between 1972 and 2012. The mean age of the patients was 28.9 years (10 to 62) and the mean follow-up was 11.4 years (2 to 35). Failure was defined as conversion to total knee arthroplasty, revision allograft, or graft removal. Clinical outcome was evaluated using the modified Hospital for Special Surgery (mHSS) score. Results. A total of 14 grafts (23.3%) failed at a mean of 8.6 years (1.4 to 20.1). Graft survivorship was 87.3% (95% confidence interval (CI) 79.0 to 96.6), 85.0% (95% CI 75.8 to 95.3), 74.8% (95% CI 62.2 to 90.0), 65.2% (95% CI 49.9 to 85.2), and 59.8% (95% CI 43.5 to 82.1) at five, ten, 15, 20, and 25 years, respectively. A total of 23 patients (38.3%) developed complications, and 26 (43.3%) had a further operation. Persistent postoperative malalignment occurred more frequently in failed grafts (28.6% vs 4.3%; p = 0.023), and was a risk factor for graft failure (hazard ratio 6.55; 95% CI 1.61 27.71; p = 0.009). The mean mHSS score improved from 74.1 (40 to 91) preoperatively to 89.0 (66 to 100) at final follow-up (p < 0.001). Conclusion. Femoral condylar FOCA with concomitant realignment osteotomy provides excellent long-term graft survival and reliable functional improvement. Persistent malalignment may increase the risk for graft failure

The goal of this study was to identify the effect of mismatches in the subchondral bone surface at the native:graft interface on cartilage tissue deformation in human patellar osteochondral allografts (OCA). Hypothesis: large mismatches in the subchondral bone surface will result in higher stresses in the overlying and surrounding cartilage, potentially increasing the risk of graft failure. Nano-CT scans of ten 16mm diameter cadaveric patellar OCA transplants were used to develop simplified and 3D finite element (FE) models to quantify the effect of mismatches in the subchondral bone surface. The simplified model consisted of a cylindrical plug with a 16 mm diameter (graft) and a washer with a 16 mm inner diameter and 36 mm outer diameter (surrounding native cartilage). The thickness of the graft cartilage was varied from 0.33x the thickness of native cartilage (proud graft subchondral bone) to 3x the thickness of native cartilage (sunken graft subchondral bone; Fig. 1). The thickness of the native cartilage was set to 2 mm. The surface of the cartilage in the graft was matched to the surrounding native cartilage. A 1 MPa pressure was applied to the fixed patellar cartilage surface. Scans were segmented using Dragonfly and meshed using HyperMesh. FE simulations were conducted in Abaqus 2019. The simplified model demonstrated that a high stress region occurred in the cartilage at the sharp bony edge between the graft and native subchondral bone, localized to the region with thinner cartilage. A 20% increase in applied pressure occurs up to 50μm away from the graft edge (primarily in the graft cartilage) for grafts with proud subchondral bone but varies little based on the graft cartilage thickness. For grafts with sunken subchondral bone, the size of the high stress region decreases as the difference between graft cartilage and native cartilage thickness decreases (Fig. 2-4), with a 200 μm high stress region occurring when graft cartilage was 3x thicker than native cartilage (i.e., greater graft cartilage thickness produces larger areas of stress in the surrounding native cartilage). The 3D models reproduced the key features demonstrated in the simplified model. Larger differences between native and graft cartilage thickness cause larger high stress regions. Differences between the 3D and simplified models are caused by heterogeneous cartilage surface curvature and thickness. Simplified and 3D FE analysis confirmed our hypothesis that greater cartilage thickness mismatches resulted in higher cartilage stresses for sunken subchondral bone. Unexpectedly, cartilage stresses were independent of the cartilage thickness mismatch for proud subchondral bone. These FE findings did not account for tissue remodeling, patient variability in tissue mechanical properties, or complex tissue loading. In vivo experiments with full-thickness strain measurements should be conducted to confirm these findings. Mismatches in the subchondral bone can therefore produce stress increases large enough to cause local chondrocyte death near the subchondral surface. These stress increases can be reduced by (a) reducing the difference in thickness between graft and native cartilage or (b) using a graft with cartilage that is thinner than the native cartilage. For any figures or tables, please contact the authors directly

There is more than one option for proximal humerus reconstruction after oncological resection but we believe osteochondral allografts provide a good biological solution for these defects. We report three cases with different histological diagnoses and different results following such reconstruction. The aim is to highlight the advantages and disadvantages of this surgical procedure. The first case report concerns a 15-year-old boy (M.P.) with Ewing’s sarcoma of the proximal humerus. The gleno-humeral articulation and most of the rotator cuff were not involved by the disease. An allograft was used for the reconstruction after satisfactory resection. This allowed good restoration of the function quickly. At 12 months there was a fatigue fracture in the allograft, which required revision with a modular prosthesis. In another patient, a young woman (E.C.), a proximal humeral defect was reconstructed following resection of a benign lesion, fibrous dysplasia. She does not have complete restoration of function but there are no complications at 3 year follow up. The last case is a 49-year-old woman (M.M.), who had osteochondral allograft reconstruction of the proximal humerus after resection of a completely destroyed head by a giant cell tumour. She had good initial results but required revision surgery with Kuntscher nail and vancomycin was added to the cement due to infection. The biological articular reconstruction after oncological wide resection allows good functional results when rotator cuff tendons are available and allografts permit a good and fitting reinsertion. The reported early restoration of function in the young boy (case 1) has to be considered in the stress-fracture genesis. The authors consider that the lack of motion in case 2 was due to a non-aggressive and careful rehabilitation: a quite poor functional result to avoid complications. The case 3 failure is due to an infection, one of most frequent complications in allograft implants. The choice of using an osteochondral allograft must be considered as a useful alternative with prosthetic replacements

Fresh osteochondral allografts were used to repair post-traumatic osteoarticular defects in 92 knees. At the time of grafting, varus or valgus deformities were corrected by upper tibial or supracondylar femoral osteotomies. A survivorship analysis was performed in which failure was defined as the need for a revision operation or the persistence of the pre-operative symptoms. There was a 75% success rate at five years, 64% at ten years and 63% at 14 years. The failure rate was higher for bipolar grafts than for unipolar and the results in patients over the age of 60 years were poor. The outcome did not depend on the sex of the patient and the results of allografts in the medial and lateral compartments of the knee were similar. Careful patient selection, correction of joint malalignment by osteotomy, and rigid fixation of the graft are all mandatory requirements for success. We recommend this method for the treatment of post-traumatic osteochondral defects in the knees of relatively young and active patients

Chondral defects on the patella are a difficult problem in the young active patient and there is no consensus on how to treat these injuries. Fresh osteochondral allografts are a valid option for the treatment of full-thickness osteochondral defects and can be used to restore joint function and reduce pain. The primary purpose of this study was to investigate the clinical and subjective outcomes of a series of patients following fresh osteochondral allograft transplantation for isolated chondral defects of the patella. A series of 5 patients underwent surgery using an open approach for graft transplantation. A strict protocol for the allograft tissue was followed. Transplant recipients must be aged <60, have a full-thickness, isolated chondral lesion and have failed previous traditional treatments. The fresh allografts are hypothermically stored at 4°C in X-VIVO10 media for up to 30 days to maintain cartilage viability. Pre- and post-operative clinical measures including knee stability, range of motion, and quadriceps girth were completed. Post-operative plain radiographs were completed including weight-bearing AP, lateral and skyline views. Patient-centred outcome measures including the Knee Osteoarthritis Outcome Score (KOOS) and the Knee Society Score (KSS) were gathered a minimum of 1-year post-operative. Descriptive and demographic data were collected for all patients. A paired t-test was employed to determine the difference between the pre-operative and post-operative outcomes. All patients were female, with a mean age of 27.4 (SD 3.65). Knee ligament stability was similar pre- and post-operatively. Knee ROM assessment of flexion and extension demonstrated a less than 10° increase from pre to post-operative. Quadriceps girth measurements demonstrated a mean change of 0.5 cm from pre- to post-operative for the surgical limb. Post-operative radiographs demonstrated incorporation of the graft in 4/5 cases within 6-months of surgery. One patient developed fragmentation of the graft after 18-months, and one patient had a subsequent trochleoplasty for persistent pain. The mean KOOS domain scores demonstrated significant improvement (p<0.05) as follows: Symptoms pre-op = 28.57, post-op = 55; Pain pre-op 28.89, post-op = 57.22; ADLs pre-op = 48.92, post-op = 66.18; Sports/Recreation pre-op = 6, post-op = 32; and QoL pre-op = 12.5, post-op = 42.5. Mean pre-op surgical versus non-surgical limb KSS scores were 107.4 and 179 respectively. The mean post-op surgical versus non-surgical limb KSS scores were 166 and 200. Isolated chondral defects of the patella can cause substantial pain, reduced function, and can be challenging to address surgically. This series of 5 cases demonstrated improved function, KOOS and KSS for 4/5 patients. To our knowledge this is a novel biological procedural technique for this problem, which has shown promising results making it a viable treatment option for young active patients with osteochondral defects of the patella

In this study, we aimed to investigate tibiofemoral and allograft loading parameters after OCA transplantation using tibial plateau shell grafts to characterize the clinically relevant biomechanics that may influence joint kinematics and OCA osseointegration after transplantation. The study was designed to test the hypothesis that there are significant changes in joint loading after tibial plateau OCA transplantation that may require unique post-operative rehabilitation regimens in patients to restore balance in the knee joint.

Fresh-frozen cadaveric knees (n=6) were thawed and mounted onto a 6 DOF KUKA robot. Specimens were size matched to +2 mm for the medial-to-lateral width of the medial tibial hemiplateaus. Three specimens served as allograft recipient knees and three served as donor knees. Recipient knees were first tested in their native state and then tested with size-matched medial tibial hemiplateau shell grafts (n=3) prepared from the donor knees using custom-cut tab-in-slot and subchondral drilling techniques. Tekscan sensors were placed in the joint spaces to evaluate the loading conditions under 90N biaxial loading at full extension of the knee before and after graft placement. The I-Scan system used in conjunction analyzed the total force, pressure distribution, peak pressure, and center of force within the joint space.

Data demonstrated significant difference (p<0.05) in joint space loading after graft implantation compared to controls in both lateral and medial tibial plateaus. The I-Scan pressure mapping system displayed changes in femoral condylar contact points as well.

The results demonstrated that joint space loading was significantly different (p<0.05) between all preoperative and postoperative cadaveric specimens. Despite the best efforts to size match grafts, slight differences in the host's joint geometry resulted in shifts of contact areas between the tibial plateau and femoral condyle therefore causing either an increase or decrease in pressure measured by the sensor. This concludes that accuracy in graft size matching is extremely important to restoring close to normal loading across the joint and this can be further ensured through postoperative care customized to the patient after OCA surgery.

An osteochondral defect greater than 3cm in diameter and 1cm in depth is best managed by an osteochondral allograft. If there is an associated knee deformity, then an osteotomy is performed. In our series of osteochondral allografts for large post-traumatic knee defects realignment osteotomy is performed about 60% of the time in order to off-load the transplant. To correct varus we realign the proximal tibia with an opening wedge osteotomy. To correct valgus, we realign the distal femur with a closing wedge osteotomy. Our results with osteochondral allografts for the large osteochondral defects of the knee both femur and tibia, have been excellent in 85% of patients at an average follow-up of 10 years. The Kaplan-Meier survivorship at 15 years is 72%. At an average follow-up of 22 years in 58 patients with distal femoral osteochondral allograft, 13 have been revised (22%). The 15-year survivorship was 84%. Retrieval studies of 24 fresh osteochondral grafts obtained at graft revision or conversion total knee replacement at an average of 12 years (5 – 25) revealed the following. In the areas where the graft was still intact, the cartilage was of normal thickness and architecture. Matrix staining was normal except in the superficial and upper mid zones. Chondrocytes were mostly viable but there was chondrocyte clusters and loss of chondrocyte polarity. Host bone had extended to the calcified cartilage but variable remnants of dead bone surrounded by live bone persisted. With a stable osseous base the hyaline cartilage portion of the graft can survive for up to 25 years

An osteochondral defect greater than 3cm in diameter and 1cm in depth is best managed by an osteochondral allograft. If there is an associated knee deformity, then an osteotomy was performed. In our series of osteochondral allografts for large post-traumatic knee defects, realignment osteotomy is performed about 60% of the time in order to off load the transplant. To correct varus we realign the proximal tibia with an opening wedge osteotomy. To correct valgus, we realign the distal femur with a closing wedge osteotomy. Our results with osteochondral allografts for the large osteochondral defects of the knee both femur and tibia, have been excellent in 85% of patients at an average follow-up of 10 years. The Kaplan-Meier survivorship at 15 years is 72%. At an average follow-up of 22 years in 58 patients with distal femoral osteochondral allograft, 13 have been revised (22%). The 15-year survivorship was 84%. Retrieval studies of 24 fresh osteochondral grafts obtained at graft revision or conversion to total knee replacement at an average of 12 years (5 – 25) revealed the following. In the areas where the graft was still intact, the cartilage was of normal thickness and architecture. Matrix staining was normal except in the superficial and upper mid-zones. Chondrocytes were mostly viable but there was chondrocyte clusters and loss of chondrocyte polarity. Host bone had extended to the calcified cartilage but variable remnants of dead bone surrounded by live bone persisted. With a stable osseous base the hyaline cartilage portion of the graft can survive for up to 25 years

The parameters to be considered in the selection of a cartilage repair strategy are: the diameter of the chondral defect; the depth of the bone defect; the location of the defect (weight bearing); alignment. A chondral defect less than 3 cm in diameter can be managed by surface treatment such as microfracture, autologous chondrocyte transplantation, mosaicplasty, or periosteal grafting. An osteochondral defect less than 3 cm in diameter and less than 1 cm in depth can be managed by autologous chondrocyte transplantation, mosaicplasty or periosteal grafting. An osteochondral defect greater than 3 cm in diameter and 1 cm in depth is best managed by an osteochondral allograft. If there is an associated knee deformity, then an osteotomy should also be performed with all of the aforementioned procedures. In our series of osteochondral allografts for large post-traumatic knee defects realignment osteotomy is performed about 60% of the time in order to off load the transplant. To correct varus we realign the proximal tibia with an opening wedge osteotomy. To correct valgus, we realign the distal femur with a closing wedge osteotomy. Our results with osteochondral allografts for the large osteochondral defects of the knee have been excellent in 85% of patients at an average follow-up of 10 years. The Kaplan-Meier survivorship at 15 years is 72%. At an average follow-up of 22 years in 58 patients with distal femoral osteochondral allograft, 13 have been revised (22%). The 15-year survivorship was 84%. The results for the hip are early. To date we have performed this procedure on 16 patients. Surgical dislocation of the hip is carried out via a trochanteric osteotomy and the defect defined and trephined out. A press-fit fresh osteochondral allograft is inserted using the trephine technique. We have published our early results on a series of 8 patients with 5 good to excellent results, 1 fair result and 2 failures

Background. Based on decellularisation and cleaning processes of trabecular bone and fibrocartilage, an osteochondral allograft has been developed. Material. The chemical process, established thanks to bone and fibrocartilage data, included an efficient viroinactivation step. The raw material was a tibial plateau collected during knee arthroplasty, cut in cylinders strictly selected (>2mm cartilage height and total height between 10 and 16mm). The grafts were freeze-dried and gamma sterilised. Methods. Decellularisation and structure integrity were validated based on histological analysis, before and after treatment. Mesenchymal Stem Cells (MSC) proliferation in contact with the graft was evaluated to validate the biocompatibility. Biomechanics of the cartilage was studied to determine the compressive resistance before and after treatment. Proof of concept has been completed on femoral condyles in a rabbit model: osteochondral allografts of rabbit were prepared from femoral condyles, processed like human allografts and implanted in 6 femoral condyle defects of 4mm diameter and compared to 3 sham-operated sites. Rabbits were sacrificed at 12 weeks. Macroscopic evaluation and histological stainings were carried out to determine bone and cartilage reconstruction. Results. The stainings of processed grafts showed decellularisation, cleaning of bone, porosity of cartilage tissue, decrease in the aggrecan rate and preservation of type II collagen. MSC proliferated inside the trabecular bone and spread at the surface of the cartilage tissue after 3 weeks. Compressive resistance of cartilage before and after processing was similar to literature. Osteochondral rabbit defects were filled with bone and cartilage tissue, with total integration of bone and cartilage repair observed in two ways: cells spreading from lateral cartilage and MSC diffusing from subchondral plate. Conclusions. The decellularised biocompatible osteochondral allograft enhanced cartilage repair in an animal model. Two clinical trials are ongoing in talus and knee osteochondral lesions

Background. An osteochondral defect in the knees of young active patients represents a treatment challenge to the orthopaedic surgeon. Early studies with allogenic cartilage transplantation showed this tissue to be immunologically privileged, showed fresh grafts to maintain hyaline cartilage, and surviving chondrocytes several years after implantation. Methods. Between January 1978 and October 1995 we enrolled 63 patients in a prospective non-randomised study of fresh osteochondral allografts for post-traumatic distal femur defects in our institute. Five international patients who were lost to follow-up were excluded from this study. The indications for the procedure were: patients younger than 50 years of age having unipolar post-traumatic defects, or osteochondritis dissecans larger than three cm in diameter and one cm in depth. Results. Fifty-eight patients, ages 11-48 (mean 28) were followed for 15-32 years (mean 21.8 years). Thirteen of the 58 grafts have subsequently required further surgery, with three having graft removal and ten converted to total knee arthroplasty. Three patients died during the study due to unrelated causes and are included in the survivorship curve. Kaplan-Meier survivorship analysis showed: 91%, 84%, 69%, and 59% graft survival at 10, 15, 20, and 25 years, respectively. Patients with surviving grafts had good function, with a mean modified Hospital for Special Surgery score of an average 86 at 20 years or more following the allograft transplantation surgery. Late osteoarthritic degeneration as was seen on radiographs was associated with lower Hospital for Special Surgery scores representing patients with poorer clinical outcome. Conclusion. The authors confirm the value of fresh osteochondral allograft as a long term solution for articular defect in the knees of young patients. We recommend the use of fresh osteochondral allograft for treatment of large osteochondral defects in the distal femur of young and active patients

Purpose: Fresh osteochondral allograft (FOCA) transplantation has been an effective treatment option with promising long-term clinical outcomes for focal post-traumatic or intra-articular lesions in the knee for young, active individuals. The goal of this study was to assess the osteochondral allograft to characterize the histopathologic features of early and late graft failure, as well as prolonged graft survival. Method: We examined histological features of thirtyfive fresh osteochondral allograft specimens retrieved at the time of subsequent graft revision, osteotomies or total knee arthroplasty. Results: The graft survival time in our samples ranged from one to twenty-five years based on their time to reoperation. Histological features of early graft failures were lack of chondrocyte viability, loss of matrix cationic staining, and features of mechanical instability. Histological features of late graft failures were fracture through the graft, active and incomplete remodelling of the graft bone by the host bone, and resorption of the graft tissue by synovial inflammatory activity at graft edges. Histological features associated with long-term allograft survival included viable chondrocytes, functional preservation of matrix, and complete replacement of the graft bone with the host bone. These long-term histological findings correlate clinically with excellent Oxford Knee Scores (mean 17.5) in age-matched cohorts with allograft transplants surviving 20 (mean 20.9) years or longer. Conclusion: Given chondrocyte viability, long-term allograft survival depends on graft stability by rigid fixation of host bone to graft bone. With the stable osseous graft base, the hyaline cartilage portion of the allograft can survive and function for 25 years or more

Introduction. Young, high-demand patients with large post-traumatic tibial osteochondral defects are difficult to treat. Fresh osteochondral allografting is a joint-preserving treatment option that is well-established for such defects. Our objectives were to investigate the long-term graft survivorships, functional outcomes and associated complications for this technique. Methods. We prospectively recruited patients who had received fresh osteochondral allografts for post-traumatic tibial plateau defects over 3cm in diameter and 1cm in depth with a minimum of 5 years follow-up. The grafts were retrieved within 24 hours, stored in cefalozolin/bacitracin solution at 4°C, non-irradiated and used within 72 hours. Tissue matching was not performed but joints were matched for size and morphology. Realignment osteotomies were performed for malaligned limbs. The Modified Hospital for Knee Surgery Scoring System (MHKSS) was used for functional outcome measure. Kaplan-Meier survivorship analysis was performed with conversion to TKR as end point for graft failure. Results. Of 132 patients identified, 14 were lost to follow-up and 37 had less than 5 years follow-up, leaving 81 patients. There were 29 conversions to TKR at a mean of 12 (3-23) years post-operatively. The remaining 52 patients had a mean MHKSS score of 83 (49-100) with a mean follow-up of 11.7 (5-34) years. The Kaplan-Meier graft survivorships were 94% at 5 years (SE 2.7), 83% at 10 years (SE 4.6), 62% at 15 years (SE 7.4) and 45% at 20 years (SE 8.5). Associated complications included infection (1.2%) treated by 2-stage TKR, graft collapse (8.6%) treated by TKR, osteotomy and conservatively and knee pain relieved by hardware removal (7.4%). Conclusion. Fresh osteochondral allograft is a successful treatment option for large post-traumatic tibial osteochondral defects in young patients, with satisfactory long term survivorships and functional outcomes with acceptable complication rates