Autologous Osteochondral Grafting (OATS) Historical PerspectiveProf Vladimir Bobić, Consultant Orthopaedic Knee Surgeon,

Chester Knee Clinic, Nuffield Health, The Grosvenor Hospital Chester, UKvbobic@kneeclinic.info www.kneeclinic.info @ChesterKnee

ICRS Heritage Summit Celebration of 20 Years of the ICRS

Göteborg, Swerige, 29 June to 1 July 2017

No financial or any other benefits from Arthrex, as inventor of OATS technology

Disclosure:

Celebration of 20 Years of ICRS An Opportunity for Reflective Thoughts:

• My contributions to articular cartilage imaging, repair and rehab and the ICRS which I introduced, presented and worked on for the past 20 years:

• Balanced, non-commercial (often critical) view on autologous osteochondral grafting (OATS Inventor), since 1996.

• Founding member of the ICRS, Fribourg, Switzerland 1997.• Chondral and Subchondral MR imaging (as a founder and a

chair of the ICRS Imaging Committee, Boston 1998).• Perioperative Cartilage Repair Rehabilitation (as a founder

and a chair of the ICRS Rehabilitation Committee), since 2003.• Keen interest on the concept of Osteochondral Unit and the

importance of Subchondral bone, since 2003.• Morphology and Biology Lamina Splendens, since 2015.

The Good and The Bad News About Osteochondral Grafting

Vladimir Bobic, RLBUH Liverpool, UK

Svensk Idrottsmedicinsk Förenings VårmöteGöteborg, Sverige, 10 -12 maj, 2002

How did all this start?

OATS donor sites

• Above the sulcus terminals: good concavity match to the MFC

• Lateral ICN: same as notchplastyand roofplasty area

OATS Concept:• The aim of articular cartilage repair is

restoration of a functional weight-bearing articular surface.

• OAT provides an immediately available firm articulating surface with autologous hyaline cartilage and a firm bone carrier …

• … it delivers the finished product, with all the right autologous ingredients, in the right proportion and sequence,

• The contour of the reconstructed articulating surface can be restored reasonably well,

• Press-fit fixation enables fast rehabilitation.

OATS Indications: the “ideal” chondral lesion is relatively small, full-thickness defect (10 to 15 mm in diameter), without subchondral bone loss. This lesion should be treated early, in an attempt to contain the defect and to repair the lost hyaline cartilage with

hyaline cartilage.

Osteochondral Autograft Transplantation (OATS)

What I did not know (1994 – 1998) is that what matters is not only the (articulating) surface but

also the subchondral bone

However, the concept was inuitively good as it was based on transplantation of the entire autologous osteochondral unit (unlike any other autologous cartilage repair technology),

well before we started talking about subchondral bone

JBJSA March 1974

The Subchondral Unit: A New Frontier

re-drawn from Imhof et al. 1999

Henning Madry, Saarland University, Homburg/Saar, Germany

Imhof H, Breitenseher M, Kainberger F, Rand T, Trattnig S. (1999): Importance of subchondral bone to articular cartilage in health and disease. Top Magn Reson Imaging 10:180–192

OATS Contraindications

• Large and deep osteochondral defects

• Arthritic lesions and DJD• Lesions with areas of

unstable, semidetached surrounding cartilage

• Angular deformities• Untreated instability• Major meniscal deficiency

2002: What have we learnt since 1994?

• Let’s talk about:• Mid- and long-term outcomes• Histology• Cartilage integration• Donor site issues• Biomechanics• Durability and quality of restored

articulatingsurfaces

Trochlear OATS

Uniform, excellent functional outcomes, no pain (9 patients, 4 to 6 years f/u) - the best OATS by far. Why?

RLBUH UK

Makino T et al, Arthroscopy, September 2001, 747-751

Makino T et al, Arthroscopy, September 2001, 747-751

“… However, the histologic examination revealed that the grafted cartilage was not maintained … as normal cartilage. The thickness of the cartilage and the number of cells in the implanted osteochondral grafts were obviously different from those of normal articular cartilage throughout the entire observation periods …”

2 years

donor

recipient

2 years

The same area, after 4 years …

… does not look too good

Deterioration of the recipient cartilage

MFC OAT graft after 3 years

Lane JG et al, Arthroscopy, October 2001, 856 - 863

• The edges of the articular cartilage did not show any incorporation with the host articular cartilage. Full-thickness clefts were present at the junction of the host and recipient articular cartilage and there was no evidence of healing of this cartilaginous junction.• Confocal microscopy: 95% of the cells counted manually in the bone plug transplanted from the trochlea to the medial femoral condyle were viablewhen the animals were killed 3 months after transplantation.• Biomechanical testing has risen the concern of increased subchondral bone density, as a potential factor in the progression of osteoarthritis.

Lane JG et al, Arthroscopy, October 2001, 856 - 863

OAT LFC donor site, a year after harvesting

RLBUH UK

Donor site issues

Ahmad CS et al, Arthroscopy, January 2002, 95 - 98

“ … the tissue obtained from the donor site grossly appeared fibrous and extended well above the margins of adjacent normal cartilage. Histologically, the tissue resembled a transitional tissue predominantly composed of dense fibrous tissue with regions of immature bone and cartilage. In addition, the tissue had material properties different from normal cartilage … “

OATS Problems

It is very important that transplanted cartilage is flush with surrounding cartilage, and that the graft is positioned correctly in all planes.

Correct surgical technique is essential!

Correct Surgical Technique?

MRI: Dr Michael Recht, CCF

(In)correct Surgical Technique!

MRI: Dr Michael Recht, CCF

OAT MFC recipient site, a year after implantation

• A study done by K Burns (SLC, University of Utah) demonstrates that positioning the graft flush or slightly proud approximates normal articular pressures most closely …

• … and that placing the graft even 1 mm recessed was no different than having a defect in terms of articular contact pressure.

• This study emphasizes the importance of obtaining congruity between the transplanted cartilage surface and the surrounding, recipient articular cartilage.

Correct OATS Surgical Technique

MFC 10 mm autograft after 5 years

RLBUH UK

OAT Complications

• Mainly consequences of technical (surgical) errors:

• failure to extract the graft,

• graft damage and fracture,

• donor site deformation,• graft harvested and

inserted at an inappropriate angle

• loose bodies• haemarthrosis• donor site pain

OAT MRI Evaluation

RLBUH UK

OAT MRI Evaluation

1 year 1 year

RLBUH UK

Original OCD lesion

Failed graft after one year

Arthroscopy, October 2000, E16

OAT Problems• Problems with large defects: limited availability

of autologous grafts, donor site morbidity, the lack of chondral integration.

• Technical (spatial) problems with harvesting and positioning of multiple, relatively long grafts, needed to cover a large and deep defect.

• Multiple graft transfer is technically difficult for most surgeons, which has resulted in a high incidence of intra-operative complications and poor outcomes.

• A potential for significant donor-site problem with multiple graft harvesting, including chondral degeneration, local AVN and condylar fractures.

ICRS Gothenburg, Sweden, April 2000

The lack of graft integration and degeneration of surrounding cartilage

MARIARC MRI, UK (1997)

The orange pixels correspond to normal T2 values for bone. The blue and purple pixels are anomalous: the T2 relaxation times are elevated because the tissue is "wetter" than normal (the fluid interface between recipient and donor bone).

OATS MRI analysis (1997!)

Recipient-donor cartilage integration

Makino T et al, Arthroscopy, September 2001, 747-751

Recipient-donor cartilage integration

The dead spaces between grafts: does the cobblestone appearance really matter? It certainly does not help the graft integration.

MFC OAT after 4 years

Deterioration of the recipient cartilage

CKC GNH UKRLBUH UK

Lateral Femoral Trochlea: a reliable source of good cancellous bone and bone marrow, even in advanced OA

CKC UK

MFC AVN

An alternative approach to the treatment of femoral and tibial Osteonecrosis, Chronic SONK and Secondary OA:

• The knee is often not too bad (all 3 compartments) or it is too early for a partial or a full knee replacement.

• Classic Microfracture and Core Decompression are probably not deep enough.

• Looking at most MRIs it seems that we need to reach at least 15 to 20 mm deep into subchondral bone, which is where any cylindrical osteochondral harvesters are very handy.

• Effectively, this is a combination of OAT and deep core (subchondral) decompression, with a hand driven K-wire, through the bottom of the recipient socket, with

• a mixture of autologous blood + bone marrow injected into the recipient socket,

• and capped with 10 mm OATS plug, which was soaked in the same mixture of bone marrow and blood.

• This “integrated” subchondral repair concept makes sense, it gives most people quick and durable pain relief and better knee function, but it is based on huge assumptions.

• The main question is weather unprocessed (and not concentrated) autologous bone marrow, is powerful enough biologically?

CKC UK

SONK: sudden onset, severe knee pain

MRI: “In the outer weight-bearing portion of the medial femoral condyle, there is an osteochondral lesion (22mm ant-post x 10mm med-lat x 2mm deep), with fluid at the interface with parent bone, mild reactive marrow oedema and a cortical break peripherally in keeping with instability. Degenerative changes in the medial compartment with spontaneous osteonecrosis of the medial femoral condyle (SONK) and unstable fragment.”

David Ritchie, Glasgow CKC MRI 060506

FU MRI: “In the medial compartment, the graft over the central weight-bearing portion of the medial femoral condyle has incorporated with adjacent bone and the overlying articular cartilage is flush with adjacent native cartilage. A small focus of marrow oedema is noted directly beneath the graft but overall there has been a reduction in marrow oedema around the graft. A small trace of subcortical fluid in the peripheral portion of the medial femoral condyle is similar to the pre-operative scan - presumably not included in the repair.”

Dr David Ritchie, Glasgow CKC MRI 030307

OATS: Conclusion

• Surgical technique is critically important.• Large OCD-type defects are just not doable (single

large OAT allograft is more appropriate).• Unknown long-term fate of multiple donor sites.• The quality and durability of the restored articular

surface is questionable.• Visible secondary changes in the recipient bone and

articular cartilage, often after two or more years, are a source of further concern.

• OAT is today’s yesterday’s technology, it is far from perfect, but it is still as good as cartilage autologous osteochondral repair gets.

• However, patient long term satisfaction and functional outcomes remain very high, especially with OATS + Deep Drilling + IBMA.

• Indications, indications and indications!

• Mainly because we still do not seem to understand complex biological and mechanical interaction of articulating surface and subchondral bone.

• This is probably the reason why all mainstream cartilage repair technologies suffer from two major problems:

• insufficient peripheral chondral integration (biomechanical problem?) • insufficient longitudinal subchondral integration (nutritional and biomechanical problem?).

• We may have to accept that this is as good as it gets, at this point in time.

• However, finding a biological solution for cartilage regeneration is one of the fastest growing areas of research and development in orthopaedics and regenerative medicine in general.

So, Why is Cartilage Repair Still a Problem?

Thank you

OATS was a stepping stone … but the future of cartilage repair is in less carpentry and a lot more biology