Partial knee resurfacing implants

1. Prof. Vladimir Bobić
MD FRCSEd, Consultant Orthopaedic Knee Surgeon
Chester Knee Clinic at Nuffield Health, The Grosvenor Hospital Chester, United Kingdom
www.kneeclinic.info office@kneeclinic.info @ChesterKnee
Partial Resurfacing Implants
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39th World Congress, Montréal, Canada 10-13 October 2018

2. Relevant Disclosures
Royalties received from Schwartz Biomedical
Paid Consultant for intellectual property
(BioPoly implant and instrument design),
Schwartz Biomedical
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3. Articular Cartilage Repair: Surgical Options
ACI/MACI
BioPoly: Filling the Void?
OATSMicrofracture
Allografts UKR & TKR
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4. Partial Resurfacing Implants
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HemiCAP Knee Implants
No personal surgical experience with Episealer or HemiCAP implants,
therefore this presentation will be limited to BioPoly implants.

5. BioPoly Femoral Resurfacing Implant
Articular Component: Patented Combination UHMWPE + HA
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6. • BioPoly® Material
– “Microcomposite” (UHMWPE and Hyaluronic Acid)
– Hydrophilic (water attracting) polymer
• Hyaluronic Acid within BioPoly®
– Attracts synovial fluid for lubrication
– Allows for articulation with cartilage
• No damage to opposing cartilage surfaces
• No damage to implant surface
• Resurfacing Applications
BioPoly® Technology Overview
Hyaluronic Acid
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7. BioPoly - Deformed shape at 1000N
(note larger area of tibial cartilage engaged in load sharing)
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8. Results in lower opposing cartilage contact pressure
(2.5x body weight load)
BioPoly
Tibial Cartilage
Contact Pressure
Peak = 3.46 MPa
Active Contact Zone
Loaded Area ~ 471
mm2
Metal Implant
Tibial Cartilage
Contact Pressure
Peak = 7.24 MPa
Active Contact Zone
Loaded Area ~ 314 mm2
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9. Current BioPoly® RS Partial Resurfacing
3 Families of Products
BioPoly® RS KNEE
CE Marked
BioPoly® RS PATELLA
CE Marked
BioPoly® RS SHOULDER
CE Marked
Patella
Humeral
head
Distal Femur
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+ BioPoly® RS Femoral Trochlea and Talar Dome in the pipeline

10. ®Confidential
BioPoly RS Knee and Patella System
• CE Marked
• Suitable for cartilage defects in the distal
femur and patella up to 3.1 cm2
• Femoral Condyle and Trochlear Facet
Implants
– Ti64 grit blasted stems. Press fit or cemented
• Patella implants
– All BioPoly construction for cementation
• Simple surgical instrument set and
technique
• Existing reimbursement codes
Femoral Condyles and
Trochlear Facets
Patella
15mm 20mm 15x24mm
15mm/0 15mm/1 20mm/0 20mm/1
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11. Indications : Lesion Characteristics
• Medial or Lateral femoral condyle, NOT tibial condyles
• Focal 2cm2 or (2.4 x 1.5) cm2 ≤3.1cm2 (Entire lesion visualized in static knee through static arthroscope)
• ICRS grade 2, 3, or 4
• Contained ICRS 0/1
• Depth from articular surface < 4mm
• Good subchondral bone (MRI)
X11

12. Contradictions
Lesion characteristics:
• Uncontained
• Very large
• >1 implant required
• Kissing lesion
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13. Contradictions
Other joint pathology
• Malalignment
• Laxity
• Major meniscal deficiency
• Subchondral sclerosis
• Advanced degenerative changes
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BioPoly RS Knee Surgical Technique

15. Race-track BioPoly
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17. Cemented all BioPoly Implant
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18. BioPoly® RS Partial Resurfacing Knee Implantations
6 yrs
700+ cases
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19. Study Investigators and Collaborators:
Prof Vladimir Bobic - Chester Knee Clinic, Chester, UK
Prof Mike McNicholas – Aintree, Liverpool, UK
Mr Dinesh Nathwani - Imperial College, London, UK
Prof Alister Hart - RNOH Stanmore, London, UK
Mr Jonathan Miles - RNOH Stanmore, London, UK
Matt Hill - Schwartz Biomedical, USA
Herb Schwartz - Schwartz Biomedical, USA
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20. Registry Study Design
• Study Type: Post-market registry
• 35 patients & 4 UK Centres
• Control: Historical microfracture outcomes
• Outcome measures: KOOS, VAS, Tegner, SF-36
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Major Inclusion and Exclusion Criteria
Inclusion Criteria Exclusion Criteria
• Age 21 years and older • Body Mass Index (BMI) ≥ 30
• Symptomatic lesions classified as ICRS grade 2, 3, or 4 • Generalized degenerative or autoimmune arthritis
• Lesion size ≤ 3.1cm2 circumscribed by normal or nearly normal
(ICRS grade 0 or 1) cartilage with an overall depth ≤ 4mm
from the articulating surface
• Uncorrected chronic malalignment of the knee*
• Uncorrected ligamentous instability*
• Uncorrected mechanically symptomatic meniscal tear or
total meniscectomy*
• Sufficient subchondral bone quality to support implant • Kissing lesion on tibia
• More than one implant required to accommodate lesion
• Use with opposing articulating tibial components
*Can be corrected during surgery

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22. Registry Study: Preliminary Report
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Registry Study Results

25. Registry Study Results
• Interim results after 2
years indicate:
– Significant improvement in
all clinical outcomes
– One revision (2.9%) due to
subchondral bone disorder
– No differences between
younger and older patients
• Mean Defect size = 2.7cm2
• Over half of patient population (54.3%) failed previous
cartilage repair procedures
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27. Registry Study Results
• BioPoly compared to historical microfracture outcomes
– BioPoly patients on average 7 – 9 years older
• Significantly superior KOOS QoL and Sport after 2 years
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28. Patient Adverse Events
• 1 Wound infection reported after 1/12
– Resolved quickly with medication
• 1 Patient began experiencing pain at 3/12
– Arthroscopy revealed implant intact, and loose
cartilage body as source of pain
– Removal of loose cartilage body resolved
symptoms
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29. Rotation of BioPoly Implant
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30. Failed BioPoly Implant
• Why? No structural or technical problems identified. No infection. Patient selection? Surgical technique?
• Very difficult to remove! Revised successfully with deep subchondral drilling + ChondroTissue patch.
• Possible reasons: inadequate osseous support (previous microfractures + failed MACI = failure of implant
to bone integration). Good subchondral bone is essential.
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31. OrthoBiologics vs Metal and Plastic
Hmmm ... not really. Not so soon, but will happen ... 31

32. Orthopaedics vs OrthoBiologics
The next stage: new developments which may delay or avoid more invasive surgical
treatments. The future of orthopaedics: basically, less carpentry, more biology?
Conclusion: metal and plastic are not the way forward. Partial
resurfacing implants have limited primary indications and can be very
useful as a bail-out option for failed cartilage repair procedures