A review of personal experience with articular cartilage and osteochondral repair and imaging. An attempt to explain the lack of correlation between symptoms, clinical findings, arthroscopic findings, biopsy and MR imaging.

2. Correlation of Symptoms, Clinical and
Arthroscopic Findings and Imaging
The bottom line is: nothing correlates!
So, I am done. Thank you.
Mr Vladimir Bobić, MD FRCS Ed, Consultant Orthopaedic Knee Surgeon, Chester Knee Clinic
www.kneeclinic.info office@kneeclinic.info @ChesterKnee
ICRS Focus Meeting
Vienna, Austria, 21 to 22 November 2019
www.slideshare.net/vbobic

3. Great to be back!

4. So, here we go …

5. The entire presentation will be available on: www.slideshare.net/vbobic

7. ACI Biopsy: Don’t Do it!
ACI repair 16/12

8. Why? Well, BME is not necessarily a problem!

10. • VB to Dave Ritchie (DR) email, 2006:
• Subject: SONK and all that jazz (re confusing MRI
appearance of different subchondral events):
• VB: “ There is something there and it seems it’s all
connected. We are probably looking at different stages of the
same thing:
• … it seems that subchondral repair and remodelling are a
common denominator, some of which is successful (traumatic
bone bruising, transient osteoporosis, SONK), partially
successful (persisting bone marrow oedema) or not at all
(progressive chronic bone marrow oedema, subchondral
cysts, AVN, osteonecrosis, and in the end secondary
osteoarthrosis). I don’t know, for some people most of this is
probably at various places on the same timeline, but I am not
sure if that makes sense.”
• DR: “The terminology is a bit confusing … “
• I would like to thank Dr David Ritchie and Dr Carl Winalski for
their unreserved help and patience over many years
(“Vladimir, stop staring at MR images and stick to your day
job.”)
Subchondral Events in a Nutshell:

12. MR Imaging Protocol 1997: Dr David Ritchie, Consultant Musculoskeletal Radiologist, Liverpool (now Glasgow), UK

15. The Game Changer:
The Concept of Osteochondral Functional Unit
Source: Dr Carl Winalski, Boston (now Cleveland), 2003

16. The Structure of Subchondral Bone
Redrawn from: 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
A surprisingly high number of arterial and venous vessels, as well
as nerves, can be seen in the subchondral region sending tiny
branches into the calcified cartilage …

17. MR and Arthroscopic Cartilage Imaging

18. ACL injury + extensive BB (no pain on WB!)
CKC MRI 110206
Gone after 7 months
Traumatic bone bruise = many local microtrabecular fractures

19. MFC ACI, 6/12: “In the medial
compartment, the ACI graft has
been placed over the central
weight-bearing portion of the
medial femoral condyle. Small
cartilage flap at the interface
peripherally in keeping with
minor delamination but
otherwise the graft appears good
with no cartilage overgrowth or
major defects. The
inhomogeneity of the implant
cartilage and mild marrow
oedema-like signal beneath
the graft are expected normal
findings 6 months after the
procedure.”
Unedited MRI report.
Dr David Ritchie, Glasgow, UK
CKC MRI 260906
“Normal” Bone Marrow Oedema 6/12 after MFC ACI
CKC UK

20. Long term ACI FU & MRI and BME
VB: "I know, but for how long?"

22. Shifting Bone Marrow Oedema = Remodelling Overdrive?
Shifting Bone Marrow Oedema is very painful self-contained disorder involving both
femoral condyles. On MRI it exhibits vast marrow oedema and is most likely an event on
the SONK timeline. Gets better (asymptomatic), eventually!

23. Transient Osteoporosis – Extreme Bone Remodeling?
• The aetiology of TO and TRMO remains unclear:
• One of the likely explanations for the pathogenesis of TO is perhaps
that proposed by Frost and others.
• He stated that under noxious tissue stimuli, the ordinary biological
processes, including blood flow, cell metabolism and turnover and
also tissue modelling and remodelling, might be greatly
accelerated, called the Regional Acceleratory Phenomenon
(RAP). In his opinion a prolonged or exaggerated RAP in which a
large number of bone turnover foci are activated, is the cause of
TO.
• It has been hypothesized that symptoms may be related to bone
marrow edema demonstrated at MRI and to a transitory regional
arterial hyperflow observed at the early scintigraphic analysis. Bone
tissue micro damage is the most frequent noxious stimulus that
provokes RAP and bone tissue micro fracture is the main
consequence.
• Several elements support this hypothesis. The repeatedly observed
histological findings in patients with TO showing mild inflammatory
changes and osteoporosis, associated with an elevated bone
turnover with increased bone resorption and reactive bone
formation are a good description of ongoing TRMO.

24. Post-arthroscopy Osteonecrosis
• Ahlback et al first described
spontaneous osteonecrosis of the
knee as a distinct clinical entity in
1968.
• Osteonecrosis of the knee has also
been described as a postsurgical
complication following
arthroscopic meniscectomy
(Muscolo et al., Prues-Latour et
al.) and following
radiofrequency-assisted
arthroscopic treatments,
mainly in 50+ age groups.
• The pathophysiology of
osteonecrosis following these
arthroscopic procedures is not
fully understood (vascular
isufficiency, trabecular
microfractures?), or, more likely,
a consequence of pre-
arthrosopy osteopoenia and
altered focal biomechanics
(bone density should be
looked into).
CKC UK

25. Post-arthroscopy BME
CKC UK 2018

26. Spontaneous BME + Insufficiency Fracture

27. Insufficiency Fracture and BME - Things get better, given time!
CKC UK

28. Progressive Osteonecrosis with
Residual Insufficiency Fracture

29. Symptomatic (Treatable?) Subchondral Cyst

30. Subchondral Cysts Are Not Good But Do not Need Treatment

31. Symptomatic Treatable MTC BME (with intraosseous BMAC)

32. Intraosseous Injection of Autologous Bone Marrow

33. Persistent Symptomatic Bone Marrow Oedema
Do you really have to treat painful bone marrow
oedema? Think twice!
Do not treat MR images - treat the patient,
holistically!
Take time: wait, review, repeat the scan …
If you decide to treat “symptomatic bone marrow
oedema”, discuss everything with the patient and
document everything.
Do not use bone substitutes, use autologous bone
marrow.
Do not restrict WB and ROM!

34. Insufficiency Fracture:
relatively asymptomatic, getting better slowly …

35. SONK Before and After Subchondral Decompression
• 15/12/08: subarticular
insufficiency fracture and slight
flattening of the MFC and prominent
subarticular marrow oedema more
marked on the femoral side. Since
04/04/08, significant deterioration
in the medial compartment with
SONK-like process, progressive
degenerative changes …
• 11/09/09: Comparison is made with
the previous scan 15/12/2008. In
the medial compartment,
following the subchondral
decompression, there is now
evidence of articular
irregularity, deficiency and
thinning of articular cartilage,
slight increase in the
subarticular marrow oedema
and early subarticular cyst
formation in the outer aspect of
the MFC …
• “The road to Hell is paved with
good intentions”
CKC UK

36. Symptomatic Medial OA + BME: PT Declined UKR or HTO

37. Asymptomatic Medial OA + BME 1 Year After OATS + SCD + ABM

38. Correlation of Symptoms, Clinical and
Arthroscopic Findings and Imaging
The bottom line is: nothing correlates!
Well, not entirely true!
MR imaging is always useful, if used properly, in
conjunction with detailed patient’s history,
symptoms, clinical and surgical findings.

39. Thank You for Your Attention
Everything We Know About
Articular Cartilage
A Lot More We do Not Know About
Subchondral Bone and
Osteochondral Unit
(Known and Unknown Unknowns)
vbobic@me.com