Introduction

Worst Experience: How factors outside your apparent control can delay progress.

Mycoplasma is a genus of the smallest bacteria which, having no cell wall, are resistant to many commonly used antibiotics. Hence it often is present in laboratories and in cell cultures but remains occult. The concern with this is that when mycoplasma infects cells it can alter the metabolism, functioning and gene expression and indeed chromosomal structure of the native cell. Experimental results can then be erroneous leading to poor data (and also lack of reproducibility between centres etc). Other concerning properties are that they are particularly prevalent in cell lines and can remain viable and indeed transfer between samples in liquid nitrogen.

When first embarking on studies on allogenic sources of cells for cartilage repair (umbilical cord-derived mesenchymal stromal cells; UC-MSCs) our laboratory had a bad experience with mycoplasma infections. For a period of months in 2011-12, we were throwing away culture after culture, spending hours every week attempting to decontaminate incubators, flow hoods etc as well as doing several mycoplasma tests (via PCR) on many different cell populations. We appeared to make no headway in obliterating the infection so took advice from a professional mycoplasmology company whose sole function was to test for mycoplasma and offer advice in such situations! We never did get to the root cause of the infection but gradually we reduced the infections to zero. However, it was very costly in terms of manpower, reagents and samples but particularly in terms of staff morale. This was none more so than for an orthopaedic surgeon who was attempting to work fulltime as a surgeon AND do his PhD – which at that time was mainly on UC-MSCs. He would be coming in at 10pm to feed his cells and undertake his ‘research shift’, the fruits of which were more often than not at that stage was being thrown away further down the line. We now maintain regular mycoplasma testing (particularly whenever culturing a cell line) and use some additional precautions, eg a mycoplasma killing agent in waterbaths, greater use of Virkon. So far so good…….

Content

Best Experience: Culmination of Research Efforts Impacting on Patient Care – and James B Richardson!

Thursday 5^th October 2017 will forever be etched in the minds of attendees at the 11^th Oswestry Cartilage Symposium. Professor James Richardson, who gave 20 years of his working life championing and battling to keep autologous chondrocyte implantation (ACI) going, reported at the meeting that the previous day the National Institute of Clinical Excellence (NICE) had announced their approval and evidence-based recommendations for using ACI to treat people with symptomatic articular cartilage defects of the knee (https://www.nice.org.uk/Guidance/TA477). It was a very emotive moment for all concerned, but particularly for James.

Some of the evidence that this decision was based on had come from patients treated by James and others, both in Oswestry and also elsewhere as part of the largest multicentre trial of ACI to date, ACTIVE (Autologous Chondrocyte Transplantation/Implantation Versus Existing treatment) which recruited 390 patients. The conclusion of the University of Warwick study for NICE was that survival analysis suggested that long-term results of cartilage repair are better with ACI than with microfracture (MF). In addition, and importantly, economic modelling suggested that ACI was cost-effective compared with MF across a range of scenarios. The cost-effectiveness analysis for the ACTIVE trial uses EQ-5D-3L (EuroQol-5 Dimensions, three-level version) and at the time of presenting evidence to NICE, data was based on up to 8 years of follow-up. It assumed a cost for cells of £4125, based on in house production costs. The data showed little difference between ACI and MF for the first 4 years but, after that, EQ-5D results were better in the ACI group, with a cost per QALY for ACI compared with MF of around £6000.

There remains a long way to go to make cell therapy more cost-effective (which can be achieved by decreasing cell production costs, eg with an allogeneic cell product, or simplifying the application procedure to an intra-articular injection), and indeed steps are being made along that route. But to know that research and audit of patients treated in our centre has contributed to the approval of ACI by NICE and retain the ability for this treatment to be available on the NHS in the UK is heart-warming for those concerned. Thank goodness Professor Richardson lived to see that day.

Acknowledgments

We are grateful to Versus Arthritis (grant numbers 18480, 19429 and 21156) and the Medical Research Council, UK (grant numbers MR/L0104531/1 and MR/N02706X/1) for funding contributions.

Purpose

Several studies suggest a positive relationship between patient-reported functional outcome and activity levels after knee surgery. However, our patients told us that sometimes a low reported outcome is due to high activity levels earlier, suggesting the relationship varies between patients. 'Affect’, the feeling of emotion, is described in terms of positive and negative and known to influence perceived disease symptoms. This study tested two hypotheses: (1) The relationship between activity level and reported functional outcome varies between patients, and (2) A more positive, or less negative, affect correlates with a more positive relationship between activity and functional outcome.

Methods and Materials

Lysholm score, human activity profile (HAP) and Positive and Negative Affect Schedule (PANAS) were collected from cartilage defect patients at 4 timepoints (baseline and 2, 12 and 15 months post-op). From the HAP, the Average Activity Score (AAS) was calculated. A Positive Affect (PA) and Negative Affect (NA) score were calculated from the PANAS. Linear models were used to determine if the slope between AAS and Lysholm varied significantly between patients. Spearman’s correlation was used to determine if the PA or NA score might explain the variation in slopes.

Results

Data was collected from 64 patients (40♂, 24♀; mean age 39±10SD). The mean slope of the relationship between AAS and Lysholm was 0.06 (SD: 0.37, range: -1.3 to 0.7). The variation in slope between patients was significant (p=0.005). Baseline PA score correlated positively with individual patient slope (r=0.26, 95%CI 0.01-0.47; p=0.04) and baseline NA score correlated negatively with individual patient slope (r=-0.29, 95%CI -0.04 to -0.50, p=0.02).

Conclusion

Our results support both hypotheses, suggesting that patients with a high positive affect score and low negative affect score are more likely to report improved functional outcome with increased activity levels, and vice versa. This could have implications for the prescription of rehabilitation programmes following surgery.

Purpose

Evidence suggests articular cartilage is capable of natural regeneration in some individuals; despite the oft-stated belief of its inability for self-repair. We have examined repair tissue formed following surgically induced cartilage defects in humans as part of an autologous cell implantation (ACI) procedure.

Methods and Materials

Sixteen patients (12 males, 4 females) had macroscopically healthy cartilage harvested from the trochlea for ACI. The quality of repair was assessed on MRIs taken at 14.7±3.7months and during arthroscopy at 15±3.5 months post-harvest using the Oswestry Arthroscopy Score (O-AS) and the International Cartilage Repair Society Arthroscopy Score (ICRS-AS), maximum scores of 10 and 12 respectively (where higher is better). Core biopsies of the repair tissue were assessed histologically (scored using the ICRSII and OsScore histology scores) and collagen types I, II, III, and VI determined immunohistochemically and compared to healthy cartilage.

Results

The mean O-AS and ICRS-AS of the repaired defects were 7.2±3.2SD and 10.1±3.5SD respectively with a mean defect area fill of 80%±23SD. The quality of the repair tissue formed was variable; hyaline cartilage was present in 50% of the biopsies and was associated with a significantly higher ICRS-AS (median 11 vs 7.5, p=0.05). The OsScore, but not the ICRSII score, correlated significantly with both the O-AS (r=0.49, p=0.05) and ICRS-AS (r=0.52, p=0.04). Collagen type I was detected in 12/14 biopsies, type II in 10/13 biopsies and types III and VI in 15/15 biopsies with variable staining patterns.

Conclusion

These results demonstrate the ability for articular cartilage to heal naturally following an injury, albeit with variable morphologies. The harvest defects may have an advantage in their ability to heal compared to condylar cartilage defects typically found in osteoarthritis, due to the lower loads at their location and macroscopically healthy cartilage having been removed. The mechanism by which this repair process occurs remains unknown and warrants additional studies.

Purpose

Clinicians are given guidance as to appropriate sizes of cartilage defects to treat with cell therapy. However, estimating the size on magnetic resonance imaging (MRI) may differ from ‘real-life’ areas. This study evaluates the accuracy of MRI to predict the size of articular cartilage lesions in the knee and compares against actual defect sizes recorded surgically.

Methods and Materials

This retrospective study included 64 patients (mean age 41.8±9.56 years), who underwent autologous cell implantation (ACI) performed by two different surgeons. Each patient received a pre-operative 3-T MRI at a mean of 6.1±3.0 weeks prior to cell implantation. MRIs were assessed by a single radiologist for the full-thickness defect measurement and the total abnormal defect area that they thought would be debrided. Defects were also measured by the surgeon pre- and post-debridement at arthrotomy at the cell implantation stage for comparison; post-debridement surgical measurements were used as the ‘gold standard’. Measurements were further assessed according to defect location (patella, trochlea, medial or lateral femoral condyle (MFC and LFC)).

Results

Ninety-two cartilage defects were analysed. Defects were significantly smaller pre-debridement (2.42±2.29cm²) than post-debridement (3.96±2.95cm², p=0.0003). The MRI full-thickness defect size was significantly smaller than the pre-debridement size (1.18±1.9cm² vs 2.42±2.29cm² respectively, p=0.0001). In contrast, the MRI total abnormal defect area was not significantly different to the post-debridement defect size (3.11±2.78cm² vs 3.96±2.95cm²), either when assessed collectively or by defect location. Whilst MRI still significantly underestimated pre-debridement defect sizes on the patella and MFC (p=0.024 and p=0.006, respectively), those on the LFC and trochlea were not significantly different.

Conclusion

These results indicate that measuring simply the full-thickness component of a cartilage defect on MRI will significantly underestimate the area to treat for ACI, but evaluating the whole abnormal area will better estimate the actual defect size for treatment. This is critical for surgical planning.