Chondral defects in the knee have cartilage biomechanical differences due to defect size and orientation. This study examines how the tibiofemoral contact pressure is affected by increasing full-thickness chondral defect size on the medial and lateral condyle at full extension. Isolated full-thickness, square chondral defects increasing from 0.09cm. 2. to 1.0cm. 2. were created sequentially on the medial and lateral femoral condyles of six human cadaveric knees with intact ligaments and menisci. Chondral defects were created 1.0cm from the femoral notch posteriorly. The knees were fixed to a uniaxial load frame and loaded from 0N to 600N at full extension. Contact pressures between the femoral and tibial condyles were measured using pressure mapping sensors. The peak contact pressure was defined as the highest value in the 2.54mm. 2. area around the defect. The location of the peak contact pressure was determined relative to the centre of the defect. Peak contact pressure was significantly different between (4.30MPa) 0.09cm. 2. and (6.91MPa) 1.0cm. 2. defects (p=0.04) on the medial condyle. On the lateral condyle, post-hoc analysis showed differences in contact pressures between (3.63MPa) 0.09cm. 2. and (5.81MPa) 1.0cm. 2. defect sizes (p=0.02). The location of the stress point shifted from being posteromedial (67% of knees) to anterolateral (83%) after reaching a 0.49cm. 2. defect size (p < 0.01) in the medial condyle. Conversely, the location of the peak contact pressure point moved from being anterolateral (50%) to a posterolateral (67%) location in defect sizes greater than 0.49cm. 2. (p < 0.01). Changes in contact area redistribution and cartilage stress from 0.49cm. 2. to 1.0cm. 2. impact adjacent cartilage integrity. The location of the maximum stress point also varied with larger defects. This study suggests that size cutoffs exist earlier in the natural history of chondral defects, as small as 0.49cm. 2. , than previously studied, suggesting a lower threshold for intervention

We have performed a prospective, single-surgeon study analysing the histological results of autologous chondrocyte implantation.

Fourteen patients underwent autologous chondrocyte implantation of the knee and were evaluated at one year by clinical assessment and arthroscopy. Standard staining was used to examine the sections. In addition, in situ hybridisation was used to establish type-IIa and type-IIb collagen mRNA expression and immunolocalisation techniques demonstrated the positions of type-II and type-X collagen.

Eight patients regenerated hyaline cartilage and also contained type-X collagen in the deepest layers and type-II collagen in the deep layers. Three demonstrated fibrocartilage and had type-II collagen in the deep layers. In situ hybridisation revealed that all 14 samples had the potential to express both type-IIa and type-IIb collagen.

We have shown that one year after the initial implantation chondrocytes are capable of producing type-II collagen and that they continue to proliferate and mature.

Articular cartilage (AC) and subchondral bone (SB) are intimately intertwined, forming a complex unit called the AC-SB interface. Our recent studies have shown that cartilage and bone marrow are connected by a three-dimensional network of microchannels (i.e. cartilage-bone marrow microchannel connector; CMMC), which differ microarchitecturally in number, size and morphology depending on the maturation stage of the bone and the region of the joint. However, the pathological significance of CMMC is largely unknown. Here, we quantitatively assessed how CMMC microarchitecture relates to cartilage condition and regional differences in early idiopathic osteoarthritis (OA). Two groups of cadaveric female human femoral heads (intact cartilage vs early cartilage lesions) were identified and biopsy-based high-resolution micro-CT imaging was used. Subchondral bone (SB) thickness, CMMC number, maximum and minimum CMMC size, and CMMC morphology were quantified and compared between the two groups. The effect of joint region and cartilage condition on each dependent variable was examined. The number and morphology of CMMCs were influenced by the region of the joint, but not by the cartilage condition. On the other hand, the minimum and maximum CMMC size was modified by both joint location and cartilage condition. The smallest CMMCs were consistently found in the load bearing region (LBR) of the joint. Compared to healthy subjects, the size of the microchannels was increased in early OA, most notably in the non-load bearing region (NLBR) and the peripheral rim (PR) of the femoral head. In addition, subchondral bone thinning was observed in early OA as a localized event associated with areas of partial chondral defect. Our data suggest an enlargement of the SB microchannel network and a collective structural deterioration of the SB in early idiopathic OA

Our objective was to conduct a systematic review and meta-analysis, comparing differences in clinical outcomes between either autologous or synthetic bone grafts in the operative management of tibial plateau fractures: a traumatic pattern of injury, associated with poor long-term functional prognosis. A structured search of MEDLINE, EMBASE, The Bone & Joint and CENTRAL databases from inception until 07/28/2021 was performed. Randomised, controlled, clinical trials that compared autologous and synthetic bone grafts in tibial plateau fractures were included. Preclinical studies, clinical studies in paediatric patients, pathological fractures, fracture non-union or chondral defects were excluded. Outcome data was assessed using the Risk of Bias 2 (ROB2) framework and synthesised in random-effect meta-analysis. Preferred Reported Items for Systematic Review and Meta-Analysis guidance was followed throughout. Six comparable studies involving 352 patients were identified from 3,078 records. Following ROB2 assessment, five studies (337 patients) were eligible for meta-analysis. Within these studies, more complex tibia plateau fracture patterns (Schatzker IV-VI) were predominant. Primary outcomes showed non-significant reductions in articular depression at immediate postoperative (mean difference −0.45mm, p=0.25, 95% confidence interval (95%CI): −1.21-0.31mm, I. 2. =0%) and long-term (>6 months, standard mean difference −0.56, p=0.09, 95%CI: −1.20-0.08, I. 2. =73%) follow-up in synthetic bone grafts. Secondary outcomes included mechanical alignment, limb functionality, defect site pain, occurrence of surgical site infections, secondary surgery, perioperative blood loss, and duration of surgery. Blood loss was lower (90.08ml, p<0.001, 95%CI: 41.49-138.67ml, I. 2. =0%) and surgery was shorter (16.17minutes, p=0.04, 95%CI: 0.39-31.94minutes, I. 2. =63%) in synthetic treatment groups. All other secondary measures were statistically comparable. Our findings supersede previous literature, demonstrating that synthetic bone grafts are non-inferior to autologous bone grafts, despite their perceived disadvantages (e.g. being biologically inert). In conclusion, surgeons should consider synthetic bone grafts when optimising peri-operative patient morbidity, particularly in complex tibial plateau fractures, where this work is most applicable

Abstract. Objectives. The aim of this work was to compare the different techniques and the different fluid permeability of the tissue following each technique through assessing the flow of radiopaque contrast agent using μCT image analysis and 3D modelling. Methods. Donated human tali specimens (n=12) were prepared through creating a 10mm diameter chondral defect in three different regions of each talus. Each region then underwent one of three surgical techniques: 1) Fine wire drilling, 2) Nanofracture or 3) Microfracture, equidistant sites in each defect to ensure even distribution. Each region then had an addition of 0.1 ml radiopaque contrast agent (Omnipaque™ 300), imaged using a clinical μCT scanner (SCANCO Medical AG, 73.6 μm resolution). Each μCT scan was segmented using Slicer 3D software (The Slicer Community, 2023 3D Slicer (5.2.2)). The segmentation package was used to segment the bone and contrast agent regions in each different surgical site of each sample. Each defect site was created into a cylinder and the ratio of segmented pixels of contrast agent against bone. Results. The μCT analysis indicated that across the 12 samples, eight nanofracture regions demonstrated flow of the contrast agent either to the depth of the fracture site or deeper. Some lateral flow was also observed in these sites. eight microfracture regions demonstrated that the flow of the contrast agent was localised to the fracture site and a preferential flow laterally. In only one sample, did a fine wire drilling region demonstrate any fluid flow. In this sample, contrast agent had permeated through the drilling site to the bottom and some sub-site permeation was observed. However, in all samples that showed no permeation of contrast agent through the fracture site, a layer of contrast agent on the chondral surface or minor permeation through to the sub-chondral surface. Segmentation of each sample site showed a significant increase (n=12, p<0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%). Conclusions. Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture appears to allow some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling appears to allow a comparably small amount, if not no fluid flow through the surrounding trabecular tissue. This conclusion is reinforced by previous literature that concluded the damage to the structure of the trabecular tissue is reduced when using nanofracture, compared to the other two techniques. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Abstract. Objectives. Meniscus allograft and synthetic meniscus scaffold (Actifit. ®. ) transplantation have shown promising outcomes for symptoms relief in patients with meniscus deficient knees. Untreated chondral defects can place excessive load onto meniscus transplants and cause early graft failure. We hypothesised that combined ACI and allograft or synthetic meniscus replacement might provide a solution for meniscus deficient individuals with co-existing lesions in cartilage and meniscus. Methods. We retrospectively collected data from 17 patients (16M, 1F, aged 40±9.26) who had ACI and meniscus allograft transplant (MAT), 8 patients (7M, 1F, aged 42±11) who underwent ACI and Actifit. ®. meniscus scaffold replacement. Other baseline data included BMI, pre-operative procedures and cellular transplant data. Patients were assessed by pre-operative, one-year and last follow-up Lysholm score, one-year repair site biopsy, MRI evaluations. Results. In the MAT group, the final post-operative evaluation was 7±4.5 years. The mean pre-operative Lysholm score was 49±17, rose to 66.6±16.4 1 year post-op and dropped to 58±26 at final evaluation. Four of the 17 patients had total knee replacements (TKRs) at average 6.4 years after treatment. In the Actifit. ®. group, the final post-operative assessment was 5.6±2.7years. The pre-operative Lysholm score was 53.7±21.3, increasing to 72.8±15.2 at 1 year and 70.4±27.6 at final clinical follow-up. None of the patients in the Actifit® group had received TKRs. Conclusions. Both MAT and Actifit. ®. groups were effective in improving patients symptoms and knee function according to one-year post-operative assessments. However, the knee function of patients in MAT group dropped at final follow-up, whereas the Actifit® group maintained their knee function. These preliminary findings warrant further investigations, to include more patients and alongside comparisons to ACI alone and allograft/Actifit. ®. alone as comparator groups before accurate conclusions may be drawn on the comparative efficacy of each technique. 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

Surgical microfracture is considered a first line treatment for talar osteochondral defects. Pain reduction, functional improvement and patient satisfaction are described to be 61–86% in both primary and secondary osteochondral defects. However, limited research is available whether improvement of the surgical technique is possible. We do know that the current rigid awls and drills limit the access to all locations in human joints and increase the risk of heat necrosis of bone. Application of a flexible water jet instrument to drill the microfracture holes can improve the reachability of the defect without inducing thermal damage. The aim of this study is to determine whether water jet drilling is a safe alternative compared to conventional microfracture awls by studying potential side effects and perioperative complications, as well as the quality of cartilage repair tissue in a caprine model. 6 mm diameter talar chondral defects were created bilaterally in 6 goats (12 samples). One defect in each goat was treated with microfracture holes created with conventional awls. The contralateral defect was treated with holes created with 5 second water jet bursts at a pressure of 50 MPa. The pressure was generated with a custom-made setup using an air compressor connected to a 300 litre accumulator that powered an air driven high-pressure pump (P160 Resato, Roden, The Netherlands, . www.resato.com. ). Postoperative complications were recorded. After 24 weeks, analyses were performed using the ICRS macroscopic score and the modified O'Driscoll histological score. Wilcoxon ranked sum tests were used to assess significant differences between the two instrument groups using each goat as its own control (p ≤ 0.05). One postoperative complication was signs of a prolonged wound healing with swelling and reluctance to weight bearing starting two days after surgery on the water jet side. Antibiotics were administered which resolved the symptoms. The median total ICRS score for the tali treated with water jets was 9,5 (range: 6–12) and 9 (range 2–11) for Observer 1 and 2 respectively; and for the tali treated conventionally this was 9,5 (range 5–11) and 9 range (2–10). The median total Modified O'Driscoll score for the tali treated with water jets was 15 (range: 7–17) and 13 (range: 3–20) for Observer 1 and 2 respectively; and for the tali treated conventionally was 13 (range: 11–21) and 15 (range: 9–20). No differences were found in complication rate or repair tissue quality between the two techniques. The results suggest that water jet drilling can be a safe alternative for conventional microfracture treatment. Future research and development will include the design of an arthroscopic prototype of the water jet drill. The focus will be on stability in nozzle positioning and minimized sterile saline consumption to further the decrease the risk of soft tissue damage

Articular cartilage repair is assumed to improve by covering the cartilage lesion with a biomaterial scaffold tailored to the specific requirements of the weight-bearing joint surface. We have tested the feasibility of a novel composite collagen-polylactide scaffold rhCo-PLA in cartilage repair. To confirm these results and further challenge the scaffold, we tested it in a large porcine cartilage defect. A critical-sized full-thickness chondral defect was made in the medial femoral condyle of 18 domestic pigs. This technically widest possible defect size of 11×17 mm was determined in a pilot test. Five weeks later, the defect was either treated with the novel rhCo-PLA scaffold or left untreated to heal spontaneously. After four months, the medial condyles were evaluated macroscopically using Goebel's score, in which the worst possible result receives a total of 20 points and imaged with µCT to evaluate subchondral bone. Macroscopic score and subchondral bone microstructure were similar in both study groups. The total Goebel score was higher in spontaneous group (9.75±3.9 for spontaneous and 9.1±3.7 for rhCo-PLA, respectively) but differences between individual animals were large. Subchondral bone volume fraction was 48.2±3.6% for rhCo-PLA and 44.2±3.4% for spontaneous. Trabecular thickness was greater in operated joints (207.9±18.8 µm for spontaneous and 242.9±32.9 µm for rhCo-PLA) than in contralateral non-operated joints (193.3±15.1 µm and 213.4±33.2 µm, respectively). These preliminary data demonstrate that individual differences in the macroscopic appearance were large but there were no significant differences between the two study groups in the score or subchondral bone structure

Abstract. Purpose. Stratification is required to ensure that only patients likely to benefit, receive Autologous Chondrocyte Implantation (ACI). At Stage I (SI), healthy cartilage is harvested from the joint and chondrocytes culture expanded before being implanted into a chondral/osteochondral defect at Stage II (SII). In ACI non-responders, there is a marked shift in the profile and abundance of proteins detectable in the synovial fluid (SF) at SII, many being associated with an acute phase response (APR). However, clinical biomarkers are easier to measure in blood than SF, so we have now performed this investigation in plasma. Methods. Isobaric tag for relative and absolute quantitation mass-spectrometry was used to assess the proteome in plasma pooled from ACI responders (mean Lysholm improvement of 33, n=10) or non-responders (mean: −13 points, n=10), collected at SI or SII surgeries. Interactome networks were generated using STRING. Plasma proteome data were compared to matched SF data, previously analysed, to identify any proteins that changed across the fluids. Clusterin concentration was quantitated (ELISA; Biotechne). Results. The most pronounced plasma proteome shift was seen in response to SI surgery in ACI non-responders (50 proteins; ±2.0FC; p<0.05). An interactome network was generated based on these proteins. Functions associated with this network included complement and coagulation cascade (FDR= 5.99×10-. 25. ). Sixteen matched proteins were differentially abundant between SI and SII in both the SF and plasma, 75% of which were APR associated proteins. These included clusterin, which was confirmed by ELISA (p=0.001). Conclusions. Changes in APR signalling between SI and SII surgeries in non-responders to ACI can be identified in plasma and SF. The APR is the body's first systemic response to trauma and surgery. Our data indicate that ACI non-responders may have a greater innate response to initial surgery, which is detectable in both their SF and plasma

Background. Autologous Chondrocyte Implantation (ACI) is frequently used to treat chondral defects in the knee with a good long-term outcome. This is contraindicatd in meniscal deficient knees. Allogenic Menicsal Transplantation (AMT) has been shown to give good symptomatic relief in meniscus deficient knees. However this is contraindicated in advanced cartilage degeneration. We hypothesized that combination of these two might be a solution for bone-on-bone arthritis in young individuals. Methods. We studied a consecutive series of 12 patients who underwent combined ACI and AMT between 1998 and 2005. Pre operative and post operative comparisons of lysholm scores were recorded. Magnetic Resonance Imaging was performed to assess the integration ACI & AMT. Arthroscopy was performed at one year for assessment and obtain biopsy for histological examination. Results. Out of the twelve patients only eleven were included as one had died at three months after surgery. The median pre-operative lysholm score was 45 which rose to 64 at one year. Magnetic Resonance Imaging showed good integration of both ACI and menisci. Most of the patients were able to lead an active lifestyle. Conclusion. The combination of both ACI & AMT could give a good result and defer a total knee replacement in young indi

Summary. Nasal Chondrocytes are safe and feasible for tissue engineering approaches in articular cartilage repair. Introduction. As compared to articular chondrocytes (AC), nasal septum chondrocytes (NC) proliferate faster and have a higher and more reproducible capacity to generate hyaline-like cartilaginous tissues. Moreover, the use of NC would allow reducing the morbidity associated with the harvesting of cartilage biopsy from the patient. The objective of the present study was to demonstrate safety and feasibility in the use of tissue engineered cartilage graft based on autologous nasal chondrocytes for the repair of articular defect in goats. Methods. Isolated autologous NC and AC from 6 goats were expanded and GFP-labelled before seeding 4×10. 4. cells/cm. 2. on a type I/III collagen membrane (Chondro-Gide®, Geistlich). After 2 weeks of chondrogenic differentiation 2 NC- and 2 AC-based grafts were implanted into chondral defects (6mm diameter) of the same posterior stifle joint. Repair tissue was harvested after 3 or 6 months and the decalcified samples evaluated according to O'Driscoll. Furthermore, samples from the surrounding fat pad, ligament, synovium, tendon and patellar cartilage were harvested and isolated cells tested for GFP-positivity after expansion using FACS. Results. No surgical complication or signs of inflammation occurred in any of the animals. GFP-positive cells were detectable in the repair tissue, indicating the contribution of the implanted cells to the newly formed cartilage. The O'Driscoll score of the repair tissue increased from 8.6 and 7.6 after 3 months to 14.1 and 12.4 after 6 months for nasal and articular grafts, respectively. Surrounding tissues showed no or very low (fat pad 0–0.36%) migration of the grafted cells. Conclusion. Our results demonstrate the use of NC as safe and feasible for tissue engineering approaches in articular cartilage repair. The repair tissue-quality generated by NC-grafts was demonstrated to be at least comparable to that of AC-grafts, thus opening the way for clinical test of a novel therapeutic strategy

Background. Autologous Chondrocyte Implantation (ACI) is a procedure which is gaining acceptance for the treatment of cartilage defects in the knee with good results and a long term durable outcome. Its use in other joints has been limited, mainly to the ankle. We aimed to assess the outcome of ACI in the treatment of chondral and osteochondral defects in the hip. Methods. Fifteen patients underwent ACI for chondral or osteochondral defects in the femoral head with a follow up of upto 8 years (mean of 2 years) in our institution with a mean age of 37 years at the time of operation. Pre-operatively hip function was assessed by using the Harris Hip Score and MRI. Post-operatively these were repeated at 1 year and hip scores repeated annually. Failure was defined as a second ACI to the operated lesion or a conversion to a hip resurfacing or replacement. Results. The mean pre-op Harris Hip Score (HHS) was 55 which increased to 63 at 1 year and 70 at the latest follow up. Patients who underwent ACI for cartilage defects secondary to trauma (four) were better with a mean HHS of 69 at a mean follow up of 3.5 years. Six patients underwent THR at a mean of 32 months and were classed as failures. Five patients had evidence of avascular necrosis (AVN) of the femoral head post operatively of which four AVN pre-op. Conclusion. These early results suggest that ACI could be a viable option for the treatment of isolated chondral defects in the hip. The presence of AVN or bone cysts pre-op may be a predictor of failure

Summary. The findings demonstrate that culture expanded human mesenchymal stem cells (MSCs) incorporated and proliferated in clinically relevant cell scaffolds better than freshly isolated bone marrow mononucleated cells (MNCs); in fact, only in MSC cultures were cells present for longer term chondrogenic inductions. Introduction. The treatment of chondral defects poses a significant clinical problem and a variety of cell sources and techniques have been studied and practiced to regenerate cartilage. Preclinical and clinical evidence suggests that MSCs can help regenerate cartilage when transplanted into cartilage lesions. However, the uptake of MSCs for cell therapies is limited due to the need for their culture expansion to generate subsequent numbers for transplantation. An alternative is to use minimally manipulated MNCs, which avoids the costs and regulatory implications of culture expansion and would enable the treatment of cartilage defects in a one-step procedure. Therefore, this study has focused on comparing these two cell types within three different scaffolds that can currently be used as cell delivery systems. Methods. Culture expanded human MSCs and MNCs freshly isolated from bone marrow were seeded at a density of 50,000 cells in 3mm. 2. scaffolds of Chondro-Gide® (type I/III collagen), Alpha Chondro Shield® (polyglycolic acid) and Hyalofast™ (hyaluronic acid). The cell-seeded scaffolds were incubated for 2 hours to permit initial cell adhesion and then treated with or without chondrogenic inducers (100nM dexamethasone, 10ng/ml TGF-β1, 37.5µg/ml ascorbic acid and ITS-X in DMEM/10% serum) for 28 days at 37°C. The Cell incorporation, growth and viability was assessed using Live/Dead staining and confocal microscopy, along with histological stains of the sectioned scaffolds. Proteoglycan synthesis was measured using DMMB assay of glycosaminoglycan (GAG) into the harvested culture medium. Results. MSCs adhered to the scaffolds to a much greater extent than the MNCs. In fact, the low number of MNCs initially incorporated into the scaffolds diminished over time such that no viable MNCs were seen during long term cultures and in all cases. MSCs incorporated into the Chondro-Gide® scaffold better than into the Alpha Chondro Shield® or Hyalofast™, and during long term cultures the MSCs in Chondro-Gide® proliferated to become significantly greater in number than those in the other two scaffolds. There was no clear matrix deposition. However, the MSCs in Hyalofast™ were rounded in shape, which is consistent with the morphology of chondrocytes, in the presence of chondrogenic inducers only. Furthermore, a significantly greater level of GAG was detected in the medium harvested from Chondro-Gide® and Hyalofast™ cultures under chondrogenic conditions compared with non chondrogenic conditions. Discussion/Conclusion. This study has shown that human MSCs incorporated, adhered and proliferated better in clinically utilised cell scaffolds compared to MNCs, enabling the induction of chondrogenesis in the longer term. Freshly isolated MNCs from bone marrow contain only 0.01–0.001% of MSCs in addition to non-adherent cell types, e.g. hematopoietic cells, which may account for their low cellular incorporation and decreased cell proliferation in the scaffolds. This outcome for MNCs may be improved using prospective MSC isolation techniques, where in vivo studies are also required to properly examine the chondrogenic potential. Nonetheless, our initial work suggests that culture expanded MSCs are a better option than minimally manipulated cells for cartilage repair

Objectives

In this study, we compared the pain behaviour and osteoarthritis (OA) progression between anterior cruciate ligament transection (ACLT) and osteochondral injury in surgically-induced OA rat models.

The treatment of osteochondral lesions and osteoarthritis remains an ongoing clinical challenge in orthopaedics. This review examines the current research in the fields of cartilage regeneration, osteochondral defect treatment, and biological joint resurfacing, and reports on the results of clinical and pre-clinical studies. We also report on novel treatment strategies and discuss their potential promise or pitfalls. Current focus involves the use of a scaffold providing mechanical support with the addition of chondrocytes or mesenchymal stem cells (MSCs), or the use of cell homing to differentiate the organism’s own endogenous cell sources into cartilage. This method is usually performed with scaffolds that have been coated with a chemotactic agent or with structures that support the sustained release of growth factors or other chondroinductive agents. We also discuss unique methods and designs for cell homing and scaffold production, and improvements in biological joint resurfacing. There have been a number of exciting new studies and techniques developed that aim to repair or restore osteochondral lesions and to treat larger defects or the entire articular surface. The concept of a biological total joint replacement appears to have much potential.

Cite this article: Bone Joint Res 2013;2:193–9.

Objectives

The aim of this study was to investigate the effect of granulocyte-colony stimulating factor (G-CSF) on mesenchymal stem cell (MSC) proliferation in vitro and to determine whether pre-microfracture systemic administration of G-CSF (a bone marrow stimulant) could improve the quality of repaired tissue of a full-thickness cartilage defect in a rabbit model.

We compared the quality of debridement of chondral lesions performed by four arthroscopic (SH, shaver; CU, curette; SHCU, shaver and curette; BP, bipolar electrodes) and one open technique (OPEN, scalpel and curette) which are used prior to autologous chondrocyte implantation (ACI). The ex vivo simulation of all five techniques was carried out on six juvenile equine stifle joints. The OPEN, SH and SHCU techniques were tested on knees harvested from six adult human cadavers.

The most vertical walls with the least adjacent damage to cartilage were obtained with the OPEN technique. The CU and SHCU methods gave inferior, but still acceptable results whereas the SH technique alone resulted in a crater-like defect and the BP method undermined the cartilage wall. The subchondral bone was severely violated in all the equine samples which might have been peculiar to this model. The predominant depth of the debridement in the adult human samples was at the level of the calcified cartilage. Some minor penetrations of the subchondral end-plate were induced regardless of the instrumentation used.

Our study suggests that not all routine arthroscopic instruments are suitable for the preparation of a defect for ACI. We have shown that the preferred debridement technique is either open or arthroscopically-assisted manual curettage. The use of juvenile equine stifles was not appropriate for the study of the cartilage-subchondral bone interface.

Osteoarthritis (OA) is an important cause of pain, disability and economic loss in humans, and is similarly important in the horse. Recent knowledge on post-traumatic OA has suggested opportunities for early intervention, but it is difficult to identify the appropriate time of these interventions. The horse provides two useful mechanisms to answer these questions: 1) extensive experience with clinical OA in horses; and 2) use of a consistently predictable model of OA that can help study early pathobiological events, define targets for therapeutic intervention and then test these putative therapies. This paper summarises the syndromes of clinical OA in horses including pathogenesis, diagnosis and treatment, and details controlled studies of various treatment options using an equine model of clinical OA.

The weight-bearing status of articular cartilage has been shown to affect its biochemical composition. We have investigated the topographical variation of sulphated glycosaminoglycan (GAG) relative to the DNA content of the chondrocyte in human distal femoral articular cartilage.

Paired specimens of distal femoral articular cartilage, from weight-bearing and non-weight-bearing regions, were obtained from 13 patients undergoing above-knee amputation. After papain enzyme digestion, spectrophotometric GAG and fluorometric DNA assays assessed the biochemical composition of the samples. The results were analysed using a paired t-test.

Although there were no significant differences in cell density between the regions, the weight-bearing areas showed a significantly higher concentration of GAG relative to DNA when compared with non-weight-bearing areas (p = 0.02).

We conclude that chondrocytes are sensitive to their mechanical environment, and that local loading conditions influence the metabolism of the cells and hence the biochemical structure of the tissue.

Perilesional changes of chronic focal osteochondral defects were assessed in the knees of 23 sheep. An osteochondral defect was created in the main load-bearing region of the medial condyle of the knees in a controlled, standardised manner. The perilesional cartilage was evaluated macroscopically and biopsies were taken at the time of production of the defect (T0), during a second operation one month later (T1), and after killing animals at three (T3; n = 8), four (T4; n = 8), and seven (T7; n = 8) months. All the samples were histologically assessed by the International Cartilage Repair Society grading system and Mankin histological scores. Biopsies were taken from human patients (n = 10) with chronic articular cartilage lesions and compared with the ovine specimens. The ovine perilesional cartilage presented with macroscopic and histological signs of degeneration. At T1 the International Cartilage Repair Society ‘Subchondral Bone’ score decreased from a mean of 3.0 (sd 0) to a mean of 1.9 (sd 0.3) and the ‘Matrix’ score from a mean of 3.0 (sd 0) to a mean of 2.5 (sd 0.5). This progressed further at T3, with the International Cartilage Repair Society ‘Surface’ grading, the ‘Matrix’ grading, ‘Cell Distribution’ and ‘Cell Viability’ grading further decreasing and the Mankin score rising from a mean of 1.3 (sd 1.4) to a mean of 5.1 (sd 1.6). Human biopsies achieved Mankin grading of a mean of 4.2 (sd 1.6) and were comparable with the ovine histology at T1 and T3.

The perilesional cartilage in the animal model became chronic at one month and its histological appearance may be considered comparable with that seen in human osteochondral defects after trauma.