1. THE OSTEOARTHRITIC KNEE Carolyn Bonaceto, BSRT(R)(MR) Sr. Manager, Imaging and CAD Manufacturing ConforMIS, Inc. 28 Crosby Drive  |  Bedford, MA  |  01730 Imaging Support - 781.345.9170 (O) 781.345.9111  |  (F) 781.345.0147 Connect @: www.Conformis.com Twitter:       @ConforMIS Facebook:  ConforMIS Page YouTube:    PatientSpecific channel © COPYRIGHT 2013 ConforMIS, Inc.

2. Outline • KNEE ANATOMY • Osseous Structures and Articulations • Internal and External Joint Support • KNEE PATHOLOGY • Osteoarthritis • Cartilage Injuries • IMAGING • CR • CT • CT Arthroscopy • MRI • SURGICAL TREATMENTS • Arthroscopy • Hemi-Arthroplasty • Total Knee Repair • POST SURGICAL FIT ASSESMENT © COPYRIGHT 2013 ConforMIS, Inc.

3. Knee Anatomy • Osseous Structures • Femur- • Longest, largest, strongest skeletal bone • Cylindrical shaft made up of cortical bone and fat filled medullary • Condyles defined by trochlea anteriorly and intercondylar notch posteriorly © COPYRIGHT 2013 ConforMIS, Inc.

4. Knee Anatomy • Osseous Structures • Patella- • Flat triangular sesamoid bone marking the anterior most portion of the knee joint • Thick superior border (base) and pointed inferior border (apex) • Cancellous bone enveloped by the quadriceps tendon © COPYRIGHT 2013 ConforMIS, Inc.

5. Knee Anatomy • Osseous Structures • Tibia- • Large superior portion, head, divided into two distinct portions, the medial and lateral condyles, separated by the tibial spine • Flat superior surface is called the plateau • Articulates with the femoral condyles • Tibial tuberosity found on the anterior portion serves as an articulation point for the patellar ligament • Fibula- • Most slender of the long bones • Articulates anteriorly and laterally with the lateral tibial condyle © COPYRIGHT 2013 ConforMIS, Inc.

6. Knee Anatomy Femoral shaft, distal end Patella Lateral femoral condyle Medial femoral condyle Lateral tibial plateau Medial tibial plateau Head of fibula © COPYRIGHT 2013 ConforMIS, Inc.

7. Knee Anatomy Femoral shaft, distal end Femoral condyles Patella Tibial plateau Tibial Tuberosity Head of fibula © COPYRIGHT 2013 ConforMIS, Inc.

8. Knee Anatomy • Cartilage • Dense connective tissue • Made up of chondrocytes which produce the extracellular matrix of water, collagen, and proteoglycan • Collagen is mostly type II, provides strength and structure • No blood supply, nourishment is supplied by synovial fluid • Thickness • Normally between 2 and 5mm’s • Thickness can be correlated with highest peak pressure areas. The thickest cartilage in the body is found in the patellofemoral joint • Four distinct zones • Superficial zone- highest collagen content which is aligned parallel to the articular surface, lowest concentration of proteoglycan, 10% to 20% of the overall thickness • Transitional zone- 40% to 60% of the overall thickness, collagen organization is random, composed almost exclusively of proteoglycans • Radial zone- distributes load and resists compression with parallel oriented highly organized collagen fibers, and lowest water content • Calcified cartilage zone- contains the tidemark which signals the transition between calcified and uncalcified cartilage © COPYRIGHT 2013 ConforMIS, Inc.

9. Knee Anatomy Articular Cartilage © COPYRIGHT 2013 ConforMIS, Inc.

10. Knee Anatomy • Joint Support • External Support • Fibrous Capsule • Encloses the joint, consists of synovial membrane, thin connective tissue which secretes synovial fluid. This thick, high viscosity fluid helps lubricate the knee and reduce friction. • Extracapsular Ligaments • Anterior - Patella ligament • Lateral – Lateral collateral ligament • Medial – Medial collateral ligament • Posterior- Oblique popliteal ligament and arcuate ligament © COPYRIGHT 2013 ConforMIS, Inc.

11. Knee Anatomy • Joint Support • Internal Support • Anterior cruciate ligament (ACL) – provides rotation for the joint and prevents displacement anteriorly • Posterior cruciate ligament (PCL)- prevents posterior draw ACL PCL © COPYRIGHT 2013 ConforMIS, Inc.

12. Knee Anatomy • Menisci (from Greek meniskos, “crescent”) • Medial and Lateral • Fibrocartilaginous concave semicircles • Articulates with the tibial plateaus • Provides gliding surface for knee movement and absorbs tension © COPYRIGHT 2013 ConforMIS, Inc.

13. Knee Anatomy • Muscular Support • Extensors • Quadriceps femoris muscle group • Rectus femoris • Vastuslateralis, • Vastusmedialus • Vastusintermedius • Flexors • Hamstring muscle group • Semitendinosus • Semimembranosus • Biceps femoris • Assisting muscles • Gracilis • Sartorius • Popliteus Quadriceps tendon Vastus medialus Cortical bone Cancellous bone Vastus lateralis Sartorius Biceps femoris Semimembranosus © COPYRIGHT 2013 ConforMIS, Inc.

14. Knee Anatomy Medial femoral condyle Lateral femoral condyle Lateral collateral ligament Anterior cruciate ligament Anterior cruciate ligament Head of the fibula Medial compartment Lateral compartment Tibial plateau

15. Knee Anatomy Patellofemoral compartment Quadriceps tendon Posterior cruciate ligament Lateral meniscus Cartilage bone interface Tibial spine Patellar tendon Articular cartilage

16. Diagnostic Imaging • Knee anatomy and pathology is generally demonstrated using: • Routine radiographs, CR/DR • CT with or without arthrogram contrast • MR with or without arthrogram contrast © COPYRIGHT 2013 ConforMIS, Inc.

17. Diagnostic Imaging • Demonstrates • Cartilage loss/Joint space narrowing • Osteophytes/bone spurs • Subchondral cysts • Sclerosis • Bone marrow edema • Traumatic injuries • CR • AP • Lateral • Tangential (sunrise) • Full Leg – used for alignment measurement © COPYRIGHT 2013 ConforMIS, Inc.

18. Diagnostic Imaging • AP - Position central ray at right angles to the joint space with no rotation. The resulting image should demonstrate the epicondyles in profile and the intercondylar eminence of the tibia centered within the intercondylar fossa of the femur • Unacceptable • Acceptable © COPYRIGHT 2013 ConforMIS, Inc.

19. Diagnostic Imaging • Lateral -Position central ray at right angles to the joint space with no rotation of the knee. The resulting image should demonstrate the posterior aspects of the femoral condyles superimposed. • Acceptable • Unacceptable © COPYRIGHT 2013 ConforMIS, Inc.

20. Diagnostic Imaging • CT • Demonstrates • Joint space narrowing • Subchondral cysts • Sclerosis • Osteophyte formations • Reconstructions • Axial • Sagittal • Coronal images • CT Arthrogram • The use of diluted contrast in joint delineates articular cartilage and ligaments • MRI • Used to evaluate soft tissue structures • Grade articular cartilage damage • Evaluate ligaments integrity • Evaluate meniscal tears • *Knee MR protocols vary from site to site and can be dependent on the system used to acquire the images* © COPYRIGHT 2013 ConforMIS, Inc.

21. Knee Pathology • Pathology commonly associated with patients considering a knee implant • Osteoarthritis (OA) – defined as chronic inflammation characterized by degeneration of the joints causing pain, stiffness, and swelling. OA is sometimes referred to as degenerative joint disease (DJD). Radiographically OA can be identified by the presence of osteophytes, bone edema, sclerosis, joint space narrowing and cyst formations. • Osteochondritis Defects (or Dissicans) (OCD) is characterized by cracks that occur in the articular cartilage and the underlying subchondral bone as a result of decreased blood flow. Avascular necrosis (AVN) or bone death as a result of the loss of blood flow leaves the articular cartilage vulnerable. Fragmentation of cartilage and bone, and subsequently loose bodies occur within the joint space, causing pain and additional damage. Radiographicallyloose bodies (bone fragments) can be seen. MR images demonstrate and stage OCD lesions in the cartilage.

22. Osteoarthritis (OA) • Morbidity • Affects as many as 40 million Americans • One of the most common causes of disability due to limitations in joint movement. • By age 40 almost 90% of the American population will have some form of OA in their weight-bearing joints • OA results in 632,000 joint replacements each year • 300,000 TKR surgeries annually in the US for end-stage arthritis of the knee joint. • Causes • Obesity • Genetics • Trauma • Metabolic disorders • Symptoms • Pain • Swelling • Loss of mobility

23. Osteoarthritis Joint space narrowing AP Lateral Tangential View (aka sunrise or merchant view) Osteophyte Osteophyte formation

24. Osteoarthritis Weight bearing AP knees Joint space narrowing Note- Because the image was acquired bilaterally neither knee is demonstrated in a true AP position since the central beam was focused between the knees. Osteophyte

25. Osteoarthritis © COPYRIGHT 2013 ConforMIS, Inc.

26. ICRS Hyaline Cartilage Lesion Classification System • Grade 1- Superficial lesions, cracks, and indentations • Grade 2 - Fraying, lesions extending down to <50% of cartilage depth • Grade 3 - Partial loss of cartilage thickness, cartilage defects extending down to >50% of cartilage depth as well as down to calcified layer • Grade 4 - Complete loss of cartilage thickness, bone only Osteophyte

27. Cartilage LossMR images Grade 3 articular cartilage loss - > 50% Grade 3 articular cartilage loss - >50% Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage © COPYRIGHT 2013 ConforMIS, Inc.

28. Cartilage LossCT Arthrogram images Grade 3 articular cartilage loss - > 50% Grade 3 articular cartilage loss - >50% Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage Grade 4 articular cartilage loss- exposed subchondral bone, complete loss of cartilage © COPYRIGHT 2013 ConforMIS, Inc.

29. Subchondral CystMR images Osteophyte formation Grade 3 articular cartilage loss - > 50% Osteophyte formation Subchondral cyst Subchondral cyst © COPYRIGHT 2013 ConforMIS, Inc.

30. Subchondral CystCT Arthrogram images Osteophyte formation Grade 3 articular cartilage loss - > 50% Osteophyte formation Subchondral cyst Subchondral cyst © COPYRIGHT 2013 ConforMIS, Inc.

31. Sclerosis CR Images Sclerotic changes – increased bone density Sclerotic changes – increased bone density © COPYRIGHT 2013 ConforMIS, Inc.

32. Bone Marrow EdemaMRI Image Bone marrow edema © COPYRIGHT 2013 ConforMIS, Inc.

33. Osteochondritis Defect (OCD) • Injury to the cartilage and underlying bone • Results from interrupted blood flow to the area © COPYRIGHT 2013 ConforMIS, Inc.

34. Osteochondritis Defect (OCD) • StageAppearance on MRI & Stability of lesion • Stage 1-  Articular Cartilage Damage only • Stage 2 - Cartilage injury with underlying fracture     a. Surrounding bony edema     b. Without edema • Stage 3 - Detached but non-displaced fragment • Stage 4 - Detached and displaced fragment © COPYRIGHT 2013 ConforMIS, Inc.

35. OCD-MRI Image Stage II OCD Stage II OCD © COPYRIGHT 2013 ConforMIS, Inc.

36. OCD-MRI Image Stage II OCD Stage III OCD Stage II OCD Stage IV OCD © COPYRIGHT 2013 ConforMIS, Inc.

37. SurgicalTreatments • Approximately 25% of OA patients require surgery • Surgeons- • Seek the least invasive method • Encourage bone preservation • Less bleeding and post surgical pain • Shorter recovery times • Still have bone to work with for potential revisions; Prosthesis failure rate requiring revision is ~1 percent per year © COPYRIGHT 2013 ConforMIS, Inc.

38. Surgical Treatments • Arthroscopy – via a scope inserted through a small incision the surgeon views the joint capsule and can perform small repairs including removal of damaged cartilage and any loose bodies. • Hemi-Arthroplasty– • Uni-compartmental Arthroplasty– this procedure replaces only the damaged area of a single joint compartment with a prosthetic device. • Duo-compartmental Arthroplasty– this procedure replaces only the damaged area of the patella femoral joint and either the medial or the lateral compartment with a prosthetic device. • Osteotomy – a high tibial osteotomy involves removal of a wedge shaped piece of bone that results in realignment allowing the patients weight to be distributed away from the damage compartment. • Total Knee Arthroplasty– involves replacing all joint surfaces © COPYRIGHT 2013 ConforMIS, Inc.

39. SurgicalTreatments “The success of primary TKR in most patients is strongly supported by more than 20 years of followup data. There appears to be rapid and substantial improvement in the patient's pain, functional status, and overall health-related quality of life in about 90 percent of patients; about 85 percent of patients are satisfied with the results of surgery.” -NIH Consensus Statement on Total Knee Replacement © COPYRIGHT 2013 ConforMIS, Inc.

40. Surgical Treatments ConforMIS iUni® is a Uni-Compartmental Device ConforMIS iDuo® is a Bi-Compartmental Device ConforMIS iTotal® is a Total Knee Device © COPYRIGHT 2013 ConforMIS, Inc.

41. ConforMIS CT Order Form © COPYRIGHT 2013 ConforMIS, Inc.

42. ConforMIS CT Protocol • Immobilize the patient and remind them of the importance of holding still for the exam. • The patients toes should be straight up. • Do not place a pillow or bolster under the affected knee so that alignment between the hip, knee and ankle is maintained. • If the patient has an implant in the opposite knee please bend that knee out of the way so that the artifact does not run through the joint space of the knee of interest. • Slice positioning is critical. Please review the guides for examples of proper positioning. • Always check all series to verify that your scan meets coverage requirements and that there are no motion artifacts. © COPYRIGHT 2013 ConforMIS, Inc.

43. ConforMIS CT Protocol © COPYRIGHT 2013 ConforMIS, Inc.

44. Post Surgical Radiographic Assessment • Routine CR images are acquired as part of a clinical assessment of patients post knee arthroplastyto evaluate for common post operative complications that can cause pain and the need for revision surgeries. • Assess for fit – overhang or underhang of either component can lead to post–op pain • Alignment – one of the goals of PKR or TKR is to restore mechanical alignment • Loosening – Failure of PKR and TKR can be associated with component loosening • Osteolysis – bone reabsorption can occur in the area of the prosthetic • Wear – can occur in some of the components of the prosthetic © COPYRIGHT 2013 ConforMIS, Inc.

45. Post Surgical Radiographic Assessment • Proper positioning is critical- unless directed to do so by your radiologists or the orthopedic surgeon avoid bilateral images. The central beam should be directed at the knee joint • Weight bearing full leg –assess for alignment and leg length • AP and Lateral – assess for component position and fit • Tangential (aka sunrise or merchant view) – demonstrates the PF joint © COPYRIGHT 2013 ConforMIS, Inc.

46. Post Surgical Radiographic Assessment AP Poor positioning Acceptable positioning © COPYRIGHT 2013 ConforMIS, Inc.

47. Post Surgical Radiographic Assessment Lateral Poor positioning Acceptable positioning © COPYRIGHT 2013 ConforMIS, Inc.

48. Post Surgical Radiographic Assessment Tangential Poor positioning Acceptable positioning © COPYRIGHT 2013 ConforMIS, Inc.

49. Post Test • The Patella is cancellous bone surrounded by the _____________ • Lateral collateral ligament • Medial collateral ligament • Patella tendon • Quadriceps tendon • Normal knee cartilage is between ________ thick • 2 and 5mm’s • 1 and 3mm’s • 6 and 7mm’s • None of the above © COPYRIGHT 2013 ConforMIS, Inc.

50. Post Test • Cartilage is dense connective tissue that is ___________ • Made up of chondrocytes which produce the extracellular matrix of water, collagen, and proteoglycan • Collagen which is mostly type II, providing strength and structure • Has no blood supply, nourishment is supplied by synovial fluid • All of the above • The following statement is true regarding diagnostic imaging of the knee. • Joint space narrowing can only be identified on CT images • CT arthrography will not help in the evaluation of articular cartilage loss • CR images can demonstrate osteophyte formations • MR images will not demonstrate soft tissue structures © COPYRIGHT 2013 ConforMIS, Inc.