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Total knee replacement - Dr. Sachin M
- 1. TOTAL KNEE REPLACEMENT MODERATOR:DR. ARIJIT DHAR ASSOCIATE PROFESSOR, DEPT OF ORTHOPAEDICS, SMCH PRESENTED BY: DR. SACHIN. M. 2nd YEAR PGT, DEPT OF ORTHOPAEDICS, SMCH
- 2. INTRODUCTION Types ofknee arthroplasty 1. Total tricompartmental knee arthroplasty 2. Unicompartmental knee arthroplasty 3. Patellofemoral arthroplasty
- 3. TOTAL KNEE ARTHROPLASTY Criticalelements of successful TKR: 1. Anatomy, Biomechanics, Soft – tissue balancing and alignment. 2. Thorough preoperative evaluation 3. Understanding of definitive surgical indications 4. Utilization of meticulous surgical techniques
- 4. BIOMECHANICS Functional anatomy and kinematics Movements of knee joint Flexion axis – helical fashion ◦ Posterior translation of femur - medial condyle by 2mm - lateral condyle by 21mm Screw-home mechanism ◦ Medially based pivoting of the knee explains the ER and IR of tibia during extension and flexion, respectively.
- 5. BIOMECHANICS Functional anatomy andkinematics Kinematic studies of knee ◦ Normal gait: 67o flexion during swing phase ◦ Stair climbing: 83o flexion ◦ Descending stairs: 90o flexion ◦ Rise from a chair: 93o flexion
- 6. BIOMECHANICS – Roleof PCL PCL RETAINING Roll forward position of medial femoral condyle ◦ Limits flexion ◦ Designs evolved from flat articulation to higher constrained anterior aspect Partially released / recessed to allow adequate flexion More symmetric gait Do not tolerate much alteration in the level of joint line PCL SUBSTITUTING Achieves femoral rollback by tibial post & femoral cam which creates stress between them Resultant stress finally transfers to bone – cement interface leading to implant loosening Decreased knee flexion & tendency to lean forward during stair climbing ◦ Inadequate rollback / loss of proprioception
- 7. BIOMECHANICS – Roleof PCL PCL RETAINING Difficult to balance a diseased or contracted PCL in a reproducible fashion – requires accuracy of approx. 1mm Too tight PCL can limit the extent of flexion and lead to increased femoral rollback Higher tibial polyethylene contact stresses – polyethylene wear PCL SUBSTITUTING Balance with mild elevation of the joint line in extension to aid in the balancing of increase in flexion gap that occurs due to PCL sacrifice Patellar clunk syndrome Reliable correction of significant deformities Tibial post is the site of wear – femoral component impinging on the post anteriorly in hyperextension
- 8. BIOMECHANICS Axial alignment ofthe knee Mechanical axis of lower limb Mechanical axis of femur & tibia Anatomic axis of femur & tibia Neutral, varus and valgus alignment Measurement of varus / valgus deformity ◦ Angle formed between the mechanical axes of femur and tibia
- 9. BIOMECHANICS Axial alignment ofthe knee Tibial articular surface – 3o varus Femoral articular surface – 9o valgus Component implantation ◦ Tibial – perpendicular to the mechanical axis of lower limb ◦ Femoral – 5o to 7o valgus to mechanical axis of lower limb
- 10. BIOMECHANICS Rotational alignment ofthe knee Tibial component – perpendicular to mechanical axis Must alter the rotation of the femoral component to create a symmetric flexion space Femoral component is externally rotated on an avg of 30 relative to posterior condylar axis. Other axes: ◦ Epicondylar axis ◦ Anteroposterior axis
- 11. BIOMECHANICS Rotational alignment ofthe knee Techniques to align tibial component rotationally ◦ Align the center of the tibial tray with the junction of medial 1/3rd of the tibial tubercle with the lateral 2/3rd . ◦ Place the knee through a ROM with trial components in place, allowing the tibia to align with the flexion axis of the femur.
- 12. BIOMECHANICS PATELLOFEMORAL JOINT Primaryfunction of patella: increase the lever arm of the extensor mechanism around the knee, improving the efficiency of quadriceps contraction. Patella displaces the force vectors of quadriceps and patellar tendon away from the center of the rotation of the knee.
- 13. BIOMECHANICS PATELLOFEMORAL JOINT Varyingextensor lever arm ◦ Function of trochlear geometry ◦ Varying PF contact areas ◦ Varying center of rotation of knee Patellofemoral stability ◦ Articular surface geometry ◦ Soft tissue restraints Q – angle ◦ Quads v/s Vastus medialis obliquus ◦ Larger Q – angle: increased tendency for lateral patellar subluxation
- 14. BIOMECHANICS PATELLOFEMORAL JOINT Variationsin the area of contact between the patella and the trochlea of the femur IR of tibia over femur during knee flexion ◦ Centralizes the tibial tubercle / diminishes the Q – angle
- 15. INDICATIONS Primary objectives ◦ Torelieve pain ◦ To provide better ROM and stability ◦ To correct deformity Rheumatoid arthritis including JRA Osteoarthritis – primary or post-traumatic Failure of previous HTO Chondrocalcinosis and pseudogout in an elderly patient
- 16. CONTRAINDICATIONS Absolute ◦ Recent/ current knee sepsis ◦ Remote source of ongoing sepsis ◦ Discontinuity / severe dysfunction of extensor mechanism ◦ Genu recurvatum secondary to neuromuscular weakness ◦ Painless, well – functioning knee arthrodesis Relative ◦ OA of ipsilateral hip ◦ PVD ◦ Dermatological like psoriasis, fungal infections etc ◦ Neuropathic arthropathy ◦ Obesity BMI > 50 ◦ Recurrent UTI ◦ H/O osteomyelitis in the proximity of knee
- 17. PREOPERATIVE EVALUATION Investigations ◦Radiographs Anteroposterior, lateral view of knee Skyline view of patella A long – leg standing anteroposterior radiograph ◦ Routine preoperative blood investigations ◦ Blood C/S, Urine RE and C/S ◦ ECG, Chest radiograph – cardiopulmonary consultation ◦ Coagulation studies ◦ Peripheral vascular status – Vascular surgeon consultation ◦ Medical comorbidities – medical clearance ◦ Dental / Dermatological interventions, if needed.
- 18. PREOPERATIVE EVALUATION Specialconsiderations: ◦ Low vitamin D level ◦ Low albumin <3.5gm/dL ◦ Neutropenia: lymphocyte count < 1200 cells/mL ◦ Metabolic syndrome ◦ Type II diabetes mellitus – HbA1c ◦ Smoking cessation ◦ BMI >50 or <20
- 19. SURGICAL PROCEDURE Beforeconsidering a patient for TKR ◦ Rule out other causes of knee pain ◦ Correlation between clinical findings and radiographs ◦ All available conservative management should be exhausted Other causes of knee pain ◦ Spinal radicular pain ◦ Referred pain from ipsilateral hip ◦ PVD ◦ Meniscal pathology ◦ Bursitis of the knee Conservative treatment ◦ Physical therapy ◦ Anti-inflammatory drugs ◦ Intra-articular injections ◦ Activity modifications
- 20. APPROACH Skin incision:Anterior midline ◦ Made with knee in flexion ◦ Long enough to avoid skin tension while using retractors Retinacular incision ◦ Standard medial parapatellar approach Subperiosteal elevation of anteromedial capsule and deep portion of medial collateral ligament Extend knee, evert patella, release lateral patellofemoral plicae
- 21. (I) Paramedian Retinacularincision(II) Subperiosteal elevation of capsule and MCL (III) Release of Lateral PF plicae
- 22. APPROACH Flex kneeagain, remove ACL and anterior horns of the menisci and the osteophytes. ◦ Posterior horns are excised after making bone cuts ◦ PCL can be excised now or later along with box cut made in distal femur Externally rotate & subluxate the tibia - relaxes extensor mechanism, decreases chance of patellar tendon avulsion & improves exposure Excise infrapatellar fat pad & retract everted extensor mechanism to expose lateral tibial plateau
- 23. APPROACH - Others •SUBVASTUS APPROACH • MID-VASTUS APPROACH
- 24. BONE PREPARATION FORTKR Distal femoral cut – 5o to 7o valgus to mechanical axis ◦ Amount of bone removed = size of the femoral component ◦ If flexion contracture +, additional resection can be done but avoid joint line elevation over 4mm ◦ PCL substituting – additional 2mm resection, to balance the increase in flexion gap ◦ Posterior referencing – measures the thickness of the posterior condylar resection ◦ PCL retaining – anterior & posterior chamfer cuts ◦ PCL substituting – remove the bone for intercondylar box
- 25. BONE PREPARATION FORTKR Femoral component rotation alignment ◦ Transepicondylar axis – parallel ◦ Anteroposterior axis – perpendicular ◦ Posterior condylar axis – 3o external rotation ◦ Cut surface of proximal tibia – Gap technique Proximal tibial cut ◦ Perpendicular to mechanical axis of the tibia with posterior slope of 3o ◦ Amount of tibial resection depends on reference side of joint Unaffected – 8 to 10mm; affected side – 2mm or less
- 27. GAP TECHNIQUE Firstremove all the osteophytes Flexion gap ≈ Extension gap Extension gap < Flexion gap ◦ Remove more bone from distal femoral cut surface or release the posterior capsule from distal femur Extension gap > Flexion gap ◦ Remove bone from posterior femoral condyles by making cuts for next available smaller femoral component ◦ Should be done with anterior referencing so that the posterior condyles are shortened & anterior cortex is not notched
- 28. INTRAMEDULLARY AND EXTRAMEDULLARY ALIGNMENTINSTRUMENTATION IM alignment – crucial on the femoral side of TKR ◦ Entry portal – a few millimeters medial to the midline, anterior to the origin of PCL ◦ EM alignment – severe lateral femoral bowing, femoral malunion, stenosis from a previous #, hardware in the IM canal of ipsilateral femur Tibial IM alignment – Fat embolism Other alignment techniques ◦ Computer assisted alignment ◦ Custom cutting blocks – MRI / CT based
- 30. POSTERIOR STABILIZED TKRIN A VARUS KNEE Remove all osteophytes on the femur and tibia PCL should be resected before balancing Tight flexion and extension gaps: release sMCL subperiosteally off the proximal tibia but do not completely release it off the tibia Tight extension gap medially: release POL subperiosteally, semimembranosus and posteromedial capsule Tight flexion gap: anterior aspect of sMCL & the pes anserinus If the entire soft tissue sleeve is released & the medial gap is still tight – advance the LCL.
- 31. POSTERIOR CRUCIATE RETAININGTKR IN A VARUS KNEE Release of sMCL – should be carried out up to 6cm distal to the joint line to effectively balance the gap If posterior drawer maneuver indicates that PCL is not functioning ◦ Consider conversion to an anterior – lipped deep – dish insert if available with the implant system being used ◦ Conversion to posterior stabilized implant
- 32. VALGUS DEFORMITY CORRECTION Remove all the osteophytes Order of release of lateral soft tissue depends on the flexion and extension gaps If both are tight – release LCL off the lateral epicondyle, sparing the insertion of popliteus tendon If only extension gap is tight – release IT band by Z – lengthening / pie crusting of the band 2cm above the joint line and check for biceps aponeurosis involvement If small correction is needed – release posterolateral corner before release of LCL
- 33. VALGUS DEFORMITY CORRECTION Release of popliteus tendon - increases flexion gap more than extension gap Release posterior capsule off the lateral femoral condyle & lateral head of gastrocnemius Advancement of MCL PIE CRUSTING TECHNIQUE: to release soft tissue tension by making multiple stab incisions Valgus + flexion contracture : causes peroneal nerve palsy after acute correction of these deformities
- 35. FLEXION CONTRACTURE CORRECTION Remove all osteophytes from posterior femoral condyle Strip the adherent posterior capsule proximally off the femur Release the tendinous origin of gastrocnemius, if needed Alternatively, posterior capsule release off the proximal tibia can be considered Increase distal femoral cut in intervals of 2mm to maximum of 4mm over the native joint line Constrained condylar type or hinge type of implants
- 36. CORRECTION OF RECURVATUM Due to neuromuscular weakness ◦ Hinged implant with an extension stop may be needed to compensate for the loss of muscle power Recurvatum without neuromuscular weakness ◦ Move the joint line distally and use a small femoral component with anterior referencing
- 37. PCL BALANCING Accuratebalancing of PCL is optimal for functioning and longevity of a PCL retaining prosthesis Partial release / recession of the PCL from the superior surface of the bone island of the tibia With difficult PCL balancing or with PCL incompetence because of complete release – sacrifice PCL and convert it into PCL substituting implant
- 38. MANAGEMENT OF BONEDEFICIENCY Causes: Arthritic angular deformity, condylar hypoplasia, osteonecrosis, trauma, previous TKR/HTO Rand classification ◦ Type I: focal metaphyseal defect, intact cortical rim ◦ Type II: extensive metaphyseal defect, intact cortical rim ◦ Type III: combined metaphyseal & cortical defects Small defects: cement filling, impacted CBG Larger non-contained defects ◦ Structural bone grafts ◦ Screws within cement ◦ Porous metal augments & cones
- 39. MANAGEMENT OF BONEDEFICIENCY Technique of Windsor et al
- 40. PATELLOFEMRAL TRACKING Factorsincreasing Q – angle ◦ Internal rotation of tibial component ◦ Internal rotation/medial translation of femoral component ◦ Anterior displacement of patella during knee motion – oversized femoral component / under resection of the patella NO THUMB TEST for patellar tracking ◦ Minimal / no pressure applied to the lateral side of the patella during knee ROM Lateral patellar retinacular release ◦ Interruption of superior genicular artery – devascularization of patella
- 42. COMPONENT IMPLANTATION Avoidhyperextension of the knee after removal of trial components – injury to posterior neurovascular structures PMMA cement is used Components can be implanted one after the other or all together at a time Remove excess cement from the periphery of the component ◦ Apply small amount of cement to posterior femoral bone surface & on the posterior condyles of the femoral implant ◦ Search for any bony or cement debris before the implantation of tibial polyethylene articular surface
- 43. WOUND CLOSURE Achievehemostasis Closure with suction drains – need blood transfusion Closure without drains – need frequent reinforcement of dressing Closure with knee flexed beyond 90o ◦ No part of the closure limits flexion Close subcutaneous tissue and skin with knee flexed 30o to 40o ◦ Aids in skin flap alignment
- 44. POSTOPERATIVE MANAGEMENT Painmanagement – COX 2 inhibitors, insitu epidural catheters, intra-articular anaesthetic injection. Compressive dressing to decrease bleeding Use knee immobilizer during ambulation till quadriceps strength is adequate to ensure stability Physical therapy ◦ Passive knee extension – place patient’s foot on a pillow ◦ Dangle the legs over the side of the bed to improve flexion ◦ ROM exercises +/- continuous passive motion machine ◦ Lower extremity muscle strengthening ◦ Gait training ◦ Instructions on performing basic daily activities
- 45. POSTOPERATIVE MANAGEMENT RanawatOrthopaedic Center (ROC) cocktail Medication Strength / Dose Amount First Injection Bupivacaine Morphine sulphate Epinephrine (1:1000) Methylprednisolone acetate Cefuroxime Sodium chloride 0.5% (200-400mg) 8mg 300ug 40mg 750mg 0.9% 24cc 0.8cc 0.3cc 1cc 10cc(reconstituted in NS) 22cc Second injection Bupivacaine Sodium chloride 0.5% 0.9% 20cc 20cc
- 46.
- 47. THROMBOEMBOLISM DVT –Pulmonary embolism Overall prevalence – 40% to 80% Proximal thrombi(above popliteal vein) 9% to 20% Thrombi in calf veins – 40% to 60% Asymptomatic PE – 10% to 20% Symptomatic PE – 0.5% to 3% Mortality rate – 2% Venography and Duplex sonography DVT prophylaxis ◦ Compression stockings; foot pumps ◦ Low dose warfarin, LMWH, Fondaparinux, aspirin
- 48. INFECTION Prevalence –1.5% cases within 2years of TKR Measures to avoid infection ◦ Minimize ingress and egress of OR personnel ◦ Filtered vertical laminar flow OR ◦ Body exhaust suits ◦ Prophylactic antibiotics ◦ Ultraviolet light Most common organism – Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus species ◦ 1st generation cephalosporins - Cefazolin
- 49. INFECTION Clinical features:signs of inflammation, painful ROM, prolonged wound drainage CRP is a reliable marker Radiographic changes ◦ Bone resorption at the bone – cement interface ◦ Cyst formation ◦ Periosteal new bone formation Nuclear medicine scans – Tc Aspiration: TC >2500 cells/cumm, PMNs > 60% Treatment options: antibiotic suppression, debridement with prosthesis retention, resection arthroplasty, knee arthrodesis, 1 or 2 stage reimplantation and amputation
- 50. PATELLOFEMORAL COMPLICATIONS Patellofemoralinstability Patellar fracture Patellar component failure / loosening Patellar clunk syndrome Extensor mechanism rupture
- 52. NEUROVASCULAR COMPLICATIONS Arterialcompromise – 0.03% to 0.2% ◦ 25% cases require amputation ◦ Assess circulatory status of limb and take vascular surgical consultation, if necessary. Peroneal nerve palsy - <1% to nearly 2% ◦ Occurs with correction of combined fixed valgus & flexion deformities (Rheumatoid arthritis) ◦ Release dressing completely & flex the knee
- 53. PERIPROSTHETIC FRACTURES Supracondylarfracture: 0.3% to 2% ◦ Risk factors: anterior femoral notching, osteoporosis, RA, steroid use, females, revision arthroplasty, neurologic disorders. ◦ Fixation: ORIF with blade plates, condylar screw plates, buttress plates + grafts / Rush pins under fluoroscopic guidance / locked supracondylar IM nail. ◦ Roreback, Angliss & Lewis classification Type I: Undisplaced #, stable prosthesis Type II: Displaced #, stable prosthesis Type III: Unstable prosthesis +/- fracture displacement
- 56. PERIPROSTHETIC FRACTURES Tibialfractures ◦ # with loose implant: revision, bone grafting, stemmed implants. ◦ Stable implant + Undisplaced #: Non-operative ◦ Stable implant + Displaced #: ORIF
- 57. RESULTS OF PRIMARYTKA Functional outcome ◦ Knee Society Scoring System, 2011 ◦ The Lower Extremity Activity Score (LEAS) ◦ Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) Radiological outcome ◦ Total Knee Arthroplasty Radiographic Evaluation and Scoring System, 1989
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