Total Knee Replacement/ arthroplasty ppt.pptx

Total Knee arthroplasty
Orthopaedics

1. Topic - Total Knee Arthroplasty Moderator – Dr. Panduranga B V Presenter – Dr. Karthik M V

2. History of Total Knee Arthroplasty 1970s - There were two design theories Recreate the normal knee anatomy and thus recreate normal knee kinematics Making anatomy secondary to function.  This design emphasized knee mechanics over the anatomy. Over past 30 years, the second approach, this mechanics over anatomy, became the predominant method for designing TKA Increasing technologic and technical sophistication, the first design, that of re-creating native anatomy and kinematics, has regained interest

3. 1971 : The first bicompartmental knee arthroplasty without a hinge for stabilization was the Polycentric Knee developed by Dr. Frank Gunston , who had previously studied in Dr. John Charnley's lab. This was the first design that did not attempt to reconstruct the knee as a "hinge" but rather attempted to preserve knee anatomy (kept the cruciate and collateral ligaments). Dr. Frank Gunston

4. 1971 - Dr. John Insall, was working with Dr. Chitranjan Ranawat and Dr. Peter Walker developed their first design was the Duocondylar Knee 1974 : developed the Total Condylar (TC) prosthesis truly the first TKA with reliable and reproducible functional outcomes and long-term survivorship. This was a Cruciate Sacrificing Design John Nevil Insall  (1930–2000) Chitaranjan S Ranawat

5. I ndication of TKR Osteoarthritis Primary (idiopathic) Secondary (RA, Ankylosing Spondylitis, Post traumatic) D eformity of knee F lexion contracture >20 degree S evere varus or valgus Deformity +/- Instability Osteonecrosis with subchondral collapse of femoral condyle Tumours around the knee

6. Cont r aindications of TKR Osteomyelitis of femur/tibia Septic arthritis of knee Rem o te act iv e infection E x t ens o r mecha n is m dysfu n ction Sever e vascu la r disease We l l fu n ctio n in g kne e art h rodes i s (fusio n ) Relativ e co n traindications : Loc a l s k i n con d it i on ( psor i asis) Pas t hist ory of k n e e osteomye l it i s Recurrent UTI

7. P reoperative planning in TKR H istory & Physical Examination C haracteristics of pain L evel of activity, functional limitation P revious treatment C omorbidities A ny active infection A ny neuromuscular condition G ait analysis A ny previous scar P reoperative ROM P reoperative assessment of collateral and cruciate ligaments A ny deformity for preop planning of intra-operative correction A ssessment of hip and ankle joint

8. General wellbeing of the patient Adequate cardiopulmonary reserve to be present to withstand anaesthesia Vascularity of operable limb to be intact Smoking cessation Obesity, HTN, Hypercholesterolemia, Diabetes No cut off for healthy BMI - But higher the BMI - more the complications

9. Blood workup Complete blood count Serum Electrolytes & Renal Function Serum albumin <3.5 mg/dl - reflective of poor nutrition - predictive of poor outcome postoperatively Urine analysis Coagulation profile in patients on anticoagulant drugs Blood sugars with HbA1c and fructosamine - <7.5 favourable

10. Pre op imaging

11. P reoperative templating 1st step- draw mechanical axis C entre of femoral head to centre of talus N eutral axis bisect centre of knee 2nd step- Tibiofemoral angle A ngle between anatomic axis of femur and anatomic axis of tibia N ormal- 7 +/- 1 degree of valgus 3rd step- Hip-knee-ankle angle F emoral resection angle, which is difference between mechanical and anatomical axis of femur 5-7 degree of valgus

12. 4th step- for tibial bone cut P erpendicular to mechanical axis of tibia 5th step- posterior slope angle D raw line over anterior cortex of tibia & second perpendicular line extending to it T hird line drawn to connect articular surface of knee and line A ngle measured between second and third line

13. TKA ALIGNMENT Correct alignment of the TKA implant is critical to restoring function and maximizing longevity. TKA Malalignment is associated with early loosening accelerated poly wear There are two schools of thought regarding the target of TKA implantation: Mechanical Axis Alignment and Kinematic Axis Alignment

14. MECHANICAL ALIGNMENT The goal of TKA alignment is to restore the normal mechanical axis. Both the distal femur and the tibia are cut to be perpendicular to the mechanical axis

15. KINEMATIC ALIGNMENT Some surgeons think that mechanical axis is important, but restoring anatomic alignment around the knee is more important. They believe that all of the non-anatomic cuts made to the femur and tibia have a cumulatively detrimental impact on postop TKA function. Therefore, they cut the femur in 9° valgus and the tibia in 3° varus to re-establish the normal joint line

16. Classification of TKR designs

17. U nconstrained knee (cr design) Knee resurfacing while preserving Ligaments INDICATIONS: A rthritis with minimal bone loss, minimal soft tissue laxity, and an intact PCL V arus deformity < 10 degrees V algus deformity < 15 degrees

18. U nconstrained knee (cr design) A dvantages I ncreased quadriceps muscle strength P reserved femoral bone stock I mproved stair climbing D isadvantages R isk of post operative PCL rupture

19. S emiconstrained knee (P S design) INDICATIONS: Previous patellectomy    I nflammatory arthritis D eficient or absent PCL

20. S emiconstrained knee (P S design) A dvantages E asy soft tissue balancing N o need to correct contracted PCL S uitable after patellectomy and for PCL deficient knee Can be d one in different types of knee deformities D isadvantages R isk of CAM-POST impingement or dislocation I ncreased constraints in varus or valgus direction compared to CR knee design T ibial post polyethylene wear from CAM-POST mechanism R isk of Patellar Clunk Syndrome

21. RADIOGRAPH CR – No visualisation of the box PS – Outline of the cam can be visualised

22. C onstrained knee (varus-valgus constrained design) INDICATIONS: LCL attenuation or deficiency MCL attenuation or deficiency F lexion gap laxity M oderate bone loss in the setting of neuropathic arthropathy

23. C onstrained knee (varus-valgus constrained design) A dvantages C oronal stability in severe coronal plane deformity D isadvantages D ecreased femoral bone stock H igh rate of aseptic loosening from increased constraint R isk of tibial post polyethylene wear &/or fracture from CAM-POST mechanism

24. H ighly constrained knee (rotating hinge design) INDICATIONS: Global ligamentous deficiency H yperextension instability R esection for tumor Massive bone loss in the setting of a neuropathic joint 

25. H ighly constrained knee (rotating hinge design) A dvantages R eserved for complex knee instability U sed in cases with gaps greater than largest available polyethylene liner &/or for substantial bone loss D isadvantages H igh rate of aseptic loosening from increased constraint S ubstantial loss of bone stock

26. Components of a modern TKR Femoral component Tibial base plate Polyethylene spacer Patella button Augments

27. S urgical principles of TKR G oal : to restore normal mechanics with a well fixed stable prosthesis A chieved by bony resection and soft tissue balancing P rinciples of TKR R estoration of neutral mechanical axis P reservation of joint line R estoration of coronal and sagittal balance R estoration of patellar tracking R estoration of posterior tibial slope

28. TKA SURGICAL APPROACH

29. Medial Parapatellar -   The goal standard for TKA arthrotomy, initially credited to von Langenbeck . Start midline over knee 2 finger-breadths above patella to 1 cm below tibial tubercle.   The VMO is detached from its insertion into the quad tendon, leaving a cuff of tendon (~5 mm) attached to the VMO proximally and a cuff of tendon attached to the medial edge of the patella distally to facilitate repair at closure.  The patella is either dislocated or dislocated + everted.  There is no definitive evidence to suggest that one technique leads to delayed recovery. 

30. Subvastus approach This approach is promoted as an “extensor-mechanism preserving” arthrotomy by staying below the VMO, avoiding an incision into the quad tendon Improves postop quad recovery and reduces pain Increases complications due to the reduced visualization of the knee Midvastus approach type of compromise between the parapatellar and subvastus, as it violates less of the quad tendon, yet provides improved visualization to the subvastus. 

31. TKA BONE CUTS

32. TIBIAL CUT The tibial cut is aimed at 0 degrees (perpendicular to the mechanical axis) Most important bone cut in TKA because it affects both the Flexion and Extension gap Foundation upon which you build the TKA

33. Pr o xima l t ib i al bone cut Ex t r ame d u l aary c u t t ing gu i de R esecte d tibi al bone

34. DISTAL FEMORAL CUT Distal Femur Cut affects 3 things: Mechanical Alignment Extension gap Joint Line Height

35. Mechanical Alignment

36. Extension Gap

37. Joint Line -   The femoral implant of every company... the depth of the distal femur is 9 mm Therefore, the target depth for the distal femoral cut is 9 mm.  You will take 9 mm of bone and replace it with 9 mm of metal

38. Dis t al f e moral cut I nt r amed ul l ary j i g in desi r e d v algus a ngle F emo r al cu ttin g guide Dista l f emo r al cut

39.  ANTERIOR & POSTERIOR FEMORAL CUTS Before making these cuts, the Implant Size must be determined with a sizing guide The anterior femur cut, the posterior femur cut, the anterior chamfer cut, and the posterior chamfer cuts are all made through the appropriately-named "4-in-1 cutting guide"

40. Rotation Native knee, the posterior femoral condyles are not equal size and therefore a line across them is not parallel to the tibial cut, rather they are in 3° of valgus Cannot place a flat jig under the posterior femoral condyles to obtain a neutral rotation  Instead, you can take a jig that has 3 ° of external rotation to obtain posterior femoral condyles to obtain a neutral rotation.

41. An t ero- p ost er i or fe moral cu t s T r a n s -epic ond y lar axis F emo r al sizin g j ig

42. Headles s p i n s i n 3º external rota t ion Ange l s w ing to es t ima t e level of cut

43. Anteri o r fem oral cut Po s t er i o r condyl ar cuts

44. Posterior Referencing jig is rigid in its position from the posterior femoral condyles This distance is strictly 9 mm, so you will cut 9 mm off the posterior femoral condyles regardless of the jig size that you use The benefit of this technique is that you recreate the normal Posterior Condyle Offset - directly related to the arc of motion

45. Anterior Referencing The benefit of this technique is that your anterior depth will be great (no notching, no overstuffing).

46. PATELLAR RESURFACING Standard thickness of the Patellar Button is 9 mm Measure the depth of the native patella, subtract 9 mm, and then set the patellar cutting guide to that number

47. GAP BALANCE - SOFT TISSUE TENSION

48. The balance of a gap is measured with a spacer block.   A balanced knee has equal sized Flexion and Extension gaps .  A balanced knee has rectangular Flexion and Extension gaps. In the perfect world, you cut the femur, you cut the tibia and the result is a perfect rectangle for the Flexion and Extension Gap.   But in reality, trapezoidal flexion and extension gaps occur despite perfect bone cuts because of soft tissue imbalance.

49. A Varus Deformity (90% of cases) causes the lateral ligaments to stretch & medial ligaments become tight and stiff The standard approach of Soft Tissue Balancing is to achieve equal medial and lateral tension at 0° and 90°.   These two reference points (0° & 90°) are used

50.  A tight flexion gap and a loose extension gap - we can only focus on increasing the flexion gap - -> cut more posterior femoral condyle. A tight extension gap and a loose flexion gap - we can only focus on increasing the extension gap - - > cut more distal femoral condyle or release posterior capsule

51. PATELLAR TRACKING The normal Q angle is about 14° in men, 17° in women.

52. MANAGEMENT OF BONE DEFICIENCY Small defects ( <5mm) typically are filled with cement. Contained defects can be filled with impacted cancellous bone graft. Rand classified these defects into three types: Type I: focal metaphyseal defect, intact cortical rim Type II: extensive metaphyseal defect, intact cortical rim Type III: combined metaphyseal and cortical defect

53. What to look in a case of TKR? AP Rule out iatrogenic fractures Primary/Revision – Stem and augments Axis of limb Overhanging of components Level of joint line Equal gaps LATERAL Design of femoral component Cement Notching Shenton line – Posterior condylar offset Overhanging of components Posterior tibial slope

54. Complications DVT and THROMBOEMBOLISM INFECTION PATELLOFEMORAL :- INSTABILITY PATELLAR FRACTURE PATELLAR CLUNK SYNDROME ENTENSOR MECHANISM RUPTURE NEUROVASCULAR :- ARTERIAL COMPROMISE (VERY RARE) PERONEAL NERVE PALSY(1-2%) PERIPROSTHETIC FRACTURES

55. DVT AND THROMBOEMBOLISM One of the most significant complication is development of DVT and resulting in life-threatening PE Risk factors >40 years E strogen use CVA, HTN, DM and MI P rolonged immobilisation P revious thromboembolism O besity S moking

56. DVT AND THROMBOEMBOLISM Prophylaxis: Mechanical: compression stockings Pharmacological Low dose warfarin LMWH Factor Xa inhibitor: Rivaroxaban, Apixaban, Edoxaban High dose Aspirin

57. INFECTION Most dreaded complication(2-3%) Risk factors S kin ulceration, previous knee surgery Associated UTI Steroid use CKD, DM M alignancy P soriasis.

58. treatment IV antibiotic D ebridement with prosthesis retention ( with Polyethylene exchange) R esection arthroplasty K nee arthrodesis O ne-stage or two-stage reimplantation A mputation.

59. Patellofemoral instability EXTENSOR MECHANISM IMBALANCE L ateral retinaculum is tight :- Lateral release indicated Medial retinacular laxity :- C losing retinacular-capsular layer with knee in 90 degrees of flexion to ensure proper medial tensioning SUBOPTIMALLY POSITIONED FEMORAL, OR TIBIAL COMPONENTS Ti bial component in an internally rotated position increases the Q angle -- lateral subluxation. I nternal rotation and medial translation of femoral component move trochlea more medial relative to extensor mechanism leading to lateral subluxation.

60. Patellofemoral instability PATELLAR SUBLUXATION C omponents should be inspected for malposition If positioned appropriately, surgical efforts to improve patellar tracking should proceed in a step- wise fashion. Lateral retinacular release -- proximal realignment -- Distal realignment procedures, such as tibial tubercle osteotomy

61. PATELLAR FRACTURE RISK FACTORS E xcessive resection V ascular compromise ( lateral release) P atellar mal tracking (component malposition) E xcessive joint line elevation knee flexion of more than 115 degrees Thermal necrosis ( PMMA polymerization) Revision TKA. TREATMENT Not as like normal patella fracture Operative- non union and hardware failure Non operative if no extensor lag and no loosening of the patellar component from a large fracture fragment ( both displaced and undisplaced )

62. Patellar clunk syndrome A ssociated with PS TKR Fi brous nodule on posterior surface of quadriceps tendon just above superior pole of patella E ntrapped in intercondylar notch of femoral prosthesis - “clunk” at 30 to 45 degrees of knee flexion as knee is actively extended.

63. Patellar clunk syndrome 2 causes: Proximal placement of patellar button-overhangs the cut surface of the patella -- impinge on the quadriceps tendon--fibrous tissue proliferation Femoral component design -Early PS components with a relatively high, sharp femoral sulcus -impinge on quadriceps tendon Treatment: A rthroscopic debridement Arthrotomy and nodule excision P atellar components revision ( malposition)

64. Q UADRICEPS TENDON RUPTURE PATELLAR TENDON RUPTURE R elated to lateral release in part because of vascular compromise of the tendon and possibly extension of the release anteriorly that weakens the tendon. Nonoperative - partial tears. Surgical repair - complete tear A ssociated with previous knee surgery, knee manipulation, and distal realignment procedures of the extensor mechanism. D irect repair-augmentation with hamstring tendons or synthetic ligament substitutes

65. Neurovascular complications R are (0.03% -0.2% )with 25% resulting in amputation. Circulatory status before surgery TKA without a tourniquet with significant vascular disease Peroneal nerve palsy Primarily with correction of long-standing combined fixed valgus and flexion deformities

66. Periprosthetic fracture femur Supracondylar fractures of femur . Risk factors : A nterior femoral notching, O steoporosis RA S teroid Female R evision arthroplasty A nterior femoral flange of condylar-type - stress riser at its proximal junction with the relatively weak supracondylar bone. Rorabeck , Angliss, and Lewis classification Type I: undisplaced fracture, prosthesis stable Type II: displaced fracture, prosthesis stable Type III: unstable prosthesis with or without fracture displacement

67. Periprosthetic fracture O perative : ORIF using plates and screws or DFN

68. Periprosthetic fracture tibia Felix and Stuart classification L ocation, implant stability, and timing (intraoperative versus postoperative) Fractures with loose implants - R evision, bone grafting, and stemmed implants Nondisplaced, stable with well-fixed implants-Nonoperatively D isplaced fractures with well-fixed implants are treated with internal fixation.

69. Reference’s Campbell’s Operative Orthopaedics – 14 th Edition Insall & Scott Surgery of Knee – 6 th Edition Turek’s Orthopaedics – 6 th Edition Hip & Knee Book – Online website Current techniques in TKA – G S Sawhney

70. THANK YOU