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Discuss approaches to the knee and Describe in detail TKR

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Discuss approaches to the knee and Describe in detail TKR

  1. 1. DISCUSS APPROACHES TO THE KNEE & DESCRIBE IN DETAIL THE OPERATION OF TKA Dr. Arojuraye S. A (Senior Registrar) National Orthopaedic Hospital, Dala – Kano 5th January, 2018
  2. 2. Outline  Approaches to the Knee  Indications  Positioning  Landmarks  Incision  Dissection  Dangers  Closure  Total Knee Arthroplasty  Indications  Preoperative Evaluation  Operative Techniques  Postoperative Care  Complications  Outcomes  Conclusion
  3. 3. Introduction  The knee is an unconstrained hinge joint  Often described as subcutaneous  Its anteromedial & anterolateral coverings consist:  Largely of fibrous tissue  Patellar retinaculum  Joint capsule  Incisions through these coverings is safe
  4. 4. Introduction…  TKA is currently one of the most successful Orthopedic surgical procedures  Long-term outcomes ranging from 90% to 98%  The success undoubtedly demands compliance with:  Restoration of a correct leg axis  Correct components positioning  Proper ligament balancing  Correct exposure
  5. 5. Approaches to the Knee Joint (Arthroscopy has largely replaced open procedures)  Anteromedial  Para patellar  Subvastus  Anterolateral  Posterolateral  Postero medial  Medial  Transverse  Lateral  Posterior  Extensile approaches  Mc Cannell  Fernandez
  6. 6. Medial Para-patellar Approach (Von Langenbeck) Indications  Total knee arthroplasty  Synovectomy  Medial meniscectomy  Ligament reconstruction  Patellectomy  Drainage of the knee  ORIF of distal femur
  7. 7. Medial Para-patellar Approach  Positioning  Supine  Sand bag  Landmarks  Patella  Patellar ligament  Tibial tubercle
  8. 8. Medial Para-patellar Approach  Incision  Longitudinal straight  7 - 10cm above the patella  Tibial tubercle Many patients who require an open operation on the knee as young adults ultimately come to require TKA and the utility of the anterior midline incision should be remembered!
  9. 9. Medial Para-patellar Approach Superficial Dissection  Medial skin flap exposes  Quadriceps tendon  Medial border of the patella  Patellar tendon  Capsulotomy  This is done leaving a cuff of tissue medial to the patella to facilitate closure
  10. 10. Medial Para-patellar Approach Deep dissection  Patella is dislocated laterally  Rotated 1800  Knee flex (900)
  11. 11. Medial Para-patellar Approach Deep dissection…  In difficult patella eversion  Superior extension  Quadriceps snip  Tubercle osteotomy Avulsion of the patellar tendon is difficult to repair and can be a devastating complication
  12. 12. Medial Para-patellar Approach Dangers  Patellar tendon avulsion  Medial collateral ligament  Infra-patellar branch of saphenous nerve
  13. 13. Subvastus Anteromedial Approach (Southern)  1st described in 1929 (Erkes)  Indications  TKA  Medial unicompartmental knee arthroplasty Because it preserves the entire extensor mechanism's attachment on the patella, the subvastus approach has an anatomic edge on other arthrotomies of the knee joint
  14. 14. Subvastus Anteromedial Approach Position  Supine  Knee flexed to 900 Skin Incision  8cm above the Patella  2cm distal to the tibial tubercle (medial)
  15. 15. Subvastus Anteromedial Approach Superficial dissection  Superficial fascia: incised slightly medial to the patella  Vastus medialis fascia: bluntly dissected down to it insertion.
  16. 16. Subvastus Anteromedial Approach Deep Dissection:  Inferior edge of vastus medialis and adductors are identified  Intermuscular septum is bluntly dissected 10cm proximal to the adductor tubercle
  17. 17. Subvastus Anteromedial Approach Deep Dissection…  Vastus medialis is lifted anteriorly  ‘L’ shaped arthrotomy  Beginning medially through the vastus insertion  along the medial edge of the patella
  18. 18. Subvastus Anteromedial Approach Deep Dissection…  Medial edge of the patella tendon is partially released  Patella is everted laterally with the knee extended
  19. 19. Subvastus Anteromedial Approach Closure  Tension and tie the capsular sutures with the knee in 90 degrees of flexion to avoid overtightening the medial capsule.
  20. 20. Subvastus Anteromedial Approach Advantages  Good exposure  Less blood loss  Preserves patella blood  Less postop pain  Faster recovery Draw backs  Subvastus haematoma  Stretching of VM  Difficult extension  Obesity  Patella baja
  21. 21. Anterolateral Approach (Kocher’s) Indications  TKA in valgus deformity  Iliotibial band lengthening  Excision of fibular head  To decompress peroneal nerve  Access to lateral femoral condyle  Access to lateral tibial condyle  Lateral meniscectomy
  22. 22. Anterolateral Approach Incision:  7.5cm above the patella  Insertion of the V. lateralis into the Q tendon  Along the lateral border of  Q. tendon  Patella  Patellar tendon  2.5cm distal to the tibial tuberosity
  23. 23. Anterolateral Approach Superficial dissection:  Follows skin incision
  24. 24. Anterolateral Approach Deep dissection  Gentle sharp dissection through the joint capsule  Patella is retracted medially to expose the articular surface
  25. 25. Anterolateral Approach Disadvantages  It is difficult to displace the patella medially  It require longer incision  Require patellar tendon must be freed
  26. 26. Operative Detail Total Knee Arthroplasty (TKA)
  27. 27. Total Knee Arthroplasty Orthopaedic elective surgical procedure where the articular surfaces of the knee ( the femoral condyles & tibial plateau) are replaced  Successful orthopaedic procedures  Longevity  Ability to relieve pain  Attention to technique is of utmost importance in achieving good results
  28. 28. Total Knee Arthroplasty Indications  Severe knee pain  Degenerative osteoarthritis  Post-traumatic osteoarthritis  Rheumatoid arthritis  Post infective (e.g TB)  Severe deformity
  29. 29. Total Knee Arthroplasty Contraindications  Infections (Active / Recent)  Critical arterial damage  Non-functioning extensor mechanism  Severe neurological disorders (relative)  Well functioning arthrodesis  Age (Very young & Very old patients)
  30. 30. TKA (Preoperative Planning)  History  Pain / deformity  Comorbidities  Examination  Alignment  Deformity / Instability  Range of motion  Extensor mechanism function  Distal neurovascular status
  31. 31. TKA (Preoperative Planning)  Plain radiographs  Recent weight bearing  AP, Lateral & Skyline  Long leg alignment view  Other investigations  FBC, ESR, CRP  Urinalysis  FBS  CXR, ECG  Clotting profile
  32. 32. TKA (Preoperative Planning)  Informed consent  Surgery  Anaesthesia  Complications
  33. 33. TKA (Preoperative Planning)  Templating  Surgical plan  Correct technique  Deformities  Implant selection
  34. 34. TKA (Operative Techniques)  Anaesthesia  General  Regional  Prophylactic antibiotics  Positioning  Supine  Thigh support  Foot Bolster
  35. 35. TKA (Operative Techniques)  Pneumatic tourniquet  The limb is prepared  Water-proof drape  Mark with sterile pen  Opsite
  36. 36. TKA (Operative Techniques)  Landmarks  Patella  Patellar ligament  Tibial tubercle  Incision  Longitudinal straight  5 – 10cm ↑ the patella  Tibial tubercle
  37. 37. TKA (Operative Techniques)  Arthrotomy  Dissection  Retropatella fat  Menisci  ACL  PCL  Osteophytes
  38. 38. TKA (Operative Techniques)
  39. 39. TKA (Operative Techniques)  10 goals of surgery  Pain relief  Restoration of function  Longevity of the prosthesis  Immediate technical aims  Anatomical alignment  Good range of motion  Good stability  Ligamentous balancing  Good patella tracking
  40. 40. TKA (Operative Techniques)  Good results  Accurate bone cuts  Equal flexion / extension gaps  Correct soft tissue balancing  Adequate fixation of implants  ↓↓ risk of adverse intraoperative events The surgeon must appreciate that TKA is as much a soft tissue operation as a bony procedure.
  41. 41. TKA (Operative Techniques)
  42. 42. TKA (Operative Techniques) Bone Cut  Femoral Cut  Tibia cut Whether the femoral or tibial cut is made first depends on the surgeon’s preference & type of prosthesis used
  43. 43. TKA (Operative Techniques) Femoral Cut  Knee is flexed & patella everted  Medullary entry  1cm anterior to insertion of PCL  Big drill bit  Insertion of intramedullary rod  Distal femoral cutting jig  Cut set @ 5 – 90 valgus  Match contralateral limb
  44. 44. TKA (Operative Techniques) NOHD-Kano
  45. 45. TKA (Operative Techniques)
  46. 46. TKA (Operative Techniques) Femoral Cut…  The distal cutting jig  Secured with 2 or 3pins It is imperative that the medial & lateral soft tissues are retracted & protected with either Hohmann or Trethowan retractors.
  47. 47. TKA (Operative Techniques) Femoral Cut…  Distal femur is then sized  Stylus of the sizer seated on the cortex  Overlying synovium removed  Marker holes are made through the jig  Order of cut  Anterior  Posterior  Anterior Chamfer  Posterior Chamfer  Box cut (post & cam mechanism)
  48. 48. TKA (Operative Techniques) NOHD - Kano
  49. 49. TKA (Operative Techniques) NOHD - Kano
  50. 50. TKA (Operative Techniques) Femoral Cut…  Cutting block is placed  Firm on the cut surface  Slight external rotation (30)  Pegs sitting on the marker holes  Secured with obliquely placed pins  Cutting guide “angel wing”  Avoid notching
  51. 51. TKA (Operative Techniques) Femoral Cut…  Difficulty sitting sizer / cutting block  Remove osteophytes  Adequate meniscal resection  Bone cuts complete  Sufficient soft tissues retraction
  52. 52. TKA (Operative Techniques) Tibial cut  900 to the axis of the tibia (coronal plane)  AP slope of 3° (sagittal plane)
  53. 53. TKA (Operative Techniques) Tibia cut…  In varus knee:  Resect 10 mm from the normal lateral compartment  2 mm from the abnormal medial compartment  In valgus knee:  Resection can be more difficult to estimate  Should extend to the level of the tip of the fibula head
  54. 54. TKA (Operative Techniques) Tibia cut…  Confirm correct height (using Stylus)  Cutting block is fixed with pins  Intramedullary rod removed
  55. 55. TKA (Operative Techniques) Tibia cut…  If extramedullary referencing is used:  Rod in line with tibial crest  Distal tip lie just medial to the centre of the ankle  The tibia is  Externally rotated &  Subluxed anteriorly (To expose entire articular surface)
  56. 56. TKA (Operative Techniques) Tibia cut…
  57. 57. TKA (Operative Techniques) Tibia cut…  After complete tibial resection:  Meniscal remnants are removed  Tibial component is sized  Trial components The tibial component should lie in slight internal rotation on the tibia, with the midpoint of the tibial baseplate being in line with the medial third of the patella tendon to optimize patellofemoral tracking
  58. 58. TKA (Operative Techniques) Flexion / extension gaps The femoral & tibial cuts should be such that the rectangular spaces created are the same in both full extension & 90° of flexion
  59. 59. TKA (Operative Techniques) Common problems  Tight in extension, flexion satisfactory Solution:  Release posterior capsule off femur  Resect the PCL  Increase distal femoral resection (Beware of raising the joint)
  60. 60. TKA (Operative Techniques) Common problems…  Tight in flexion, extension satisfactory Solution:  Increase the anteroposterior tibial slope  Downsize the femoral component (Beware of notching the femur)  Tight in flexion and extension Solution:  Increase tibial resection (Beware of losing too much tibial surface area)
  61. 61. TKA (Operative Techniques) Common problems…  Loose in flexion and extension Solution:  Increase thickness of insert (Beware gross ligamentous instability)
  62. 62. TKA (Operative Techniques) Soft tissue balancing  Scenarios  Varus deformity  Valgus deformity  Fixed flexion deformity Achieving anatomical alignment & equal flexion / extension gaps is a combination of accurate bone cuts and correct soft tissue balancing!
  63. 63. TKA (Operative Techniques) Soft tissue releases in deformity correction
  64. 64. TKA (Operative Techniques) Implantation of prosthesis  Knee replacement systems  Cemented  Uncemented  Hybrid design  The polyethylene insert  Modular  Monoblock
  65. 65. TKA (Operative Techniques) Implantation of prosthesis…  Following satisfactory trial  Selected implants are checked & opened  Knee is flexed & patella everted  Knee is washed out thoroughly & dried  Expose bone trabeculae  If sclerotic bone surface  Small drill for multiple key holes To maximize the mechanical fixation of the bone cement
  66. 66. TKA (Operative Techniques) Implantation of prosthesis…  All surgical team change their outer gloves  Cement mixing for components  Simultaneously  Separately Whether the femur or tibial prosthesis implanted first is the surgeon’s preference
  67. 67. TKA (Operative Techniques) Implantation of prosthesis…  Tibia component  Cement applied on to the cut surface  Tibial component positioned  Firmly seated with soft impactor & hammer  Excess cement is removed  Trial insert is applied to tibial baseplate  Femur is lifted up
  68. 68. TKA (Operative Techniques) Implantation of prosthesis…  Femur component  Cement is placed onto the prosthesis  Prosthesis is then positioned  Avoid flexion of the component  Gentle firm impaction  Remove excess cement  Knee is extended & axial compression applied Hyperextension leads to uneven cement pressurization and may cause posterior ‘lift-off’ of the tibial baseplate
  69. 69. TKA (Operative Techniques) Implantation of prosthesis…  Tibia insert  Trial insert is removed  Baseplate inspected  Definitive insert is impacted  Knee is extended
  70. 70. TKA (Operative Techniques) Closure  Cement set  Wash out (pulsed lavage)  Tourniquet removal  Before closure  After closure  Suction drain (lateral gutter)
  71. 71. TKA (Operative Techniques) Closure…  Repair:  Water tight  Good ROM  Normal patella tracking Closure of the knee in flexion ensures that the correct tension is achieved
  72. 72. TKA (Operative Techniques) Closure…  Deep layer  Heavy suture (e.g Vicryl 1)  Continuous suture (quadriceps)  Interrupted suture (parapatella retinaculum)  Continuous suture (medial capsule to patella tendon)  Interrupted sutures (subcutaneous fat)  Skin  Surgical staples  Continuous absorbable subcuticular  Interrupted fine nonabsorbable suture
  73. 73. TKA (Post-operative Care)  Analgesia  Antibiotics  8hrs & 16hrs  DVT prophylaxis  Mechanical  Chemical  Observation  Respiratory  Cardiovascular  Neurovascular
  74. 74. TKA (Post-operative Care)  Removal of tubes  Drains  Epidural catheter  Urinary catheter  Intravenous cannula  Hb concentration  24 – 48 hrs
  75. 75. TKA (Post-operative Care)  Full weight bearing  Active ROM  As soon as possible  Wound inspection  Radiograph  B4 discharge  Skin clips removal: 10 – 14 days
  76. 76. TKA (Post-operative Care)  SOPD:  6 weeks  Follow up:  Serial radiographs  Ideally for life
  77. 77. Complications  Early  Anaesthetic  Bleeding & haematoma  DVT/PE  Infection  Transfusion reaction  Neurovascular injury  Late  Implants failure  Periprosthetic fracture
  78. 78. Conclusion  TKA is currently one of the most successful Orthopedic surgical procedures  (good long-term outcomes: 90% to 98%)  The success of the procedure demands  Restoration of a correct leg axis  Correct positioning of the components  Proper ligament balancing  Correct exposure of the joint
  79. 79. References William MM. Arthroplasty of the knee. In: Frederick MA, Canale ST, Beaty JH. Campbell's Operative Orthopaedics, 13th ed, Elsevier 2017; Chap 7: 396 – 463.  Lee D, Timothy WR. Primary Total Knee Arthroplasty. In: The Stanmore Guide, Operative Orthopaedics; Hodder Arnold 2010; (11): 172 – 182.  Mark WP. Knee. In: Morrey BF, Morrey MC. Master Techniques in Orthopaedic Surgery: Relevant Surgical Exposures 1st ed. Lippincott Williams & Wilkins 2008; 9: 192 – 215.  Stanley H, Piet D, Richard B. The Knee. In: Surgical exposures in Orthopaedics: The anatomic approach, 4th ed. Lippincott Williams & Wilkins 2009; 10: 510 - 584  Morten GT, Henrik H, Kristian SO, Thue Q, Anders T. Indications for knee arthroplasty have remained consistent over time. Dan Med J 2012; 59 (8): A4492  Marco S, Cristina S, Francesco C, Giuseppe P, Massimiliano S. Surgical approaches in total knee arthroplasty. Joints 2013;1(2):34 – 44
  80. 80. many thanks

Notas do Editor

  • Medial skin flap to expose the quadriceps tendon, medial border of the patella & patellar tendon
    Capsulotomy is done leaving a cuff of tissue medial to the patella to facilitate closure. There should be at least a 3 mm cuff of quadriceps tendon left attached to vastus medialis and a cuff of medial retinaculum attached to the patella to allow adequate closure
  • The medial capsule is released subperiosteally off the proximal tibia to gain exposure to the medial compartment. In a varus knee, this dissection should include the deep medial collateral ligament and extend to the posteromedial corner. In a valgus knee this medial release should be minimized to the anteromedial corner in order to gain adequate exposure.
  • The Quadriceps Snip
    In cases where there is excessive tension on the patellar tendon when subluxing or everting the patella, it is useful to perform a proximal quadriceps snip. This approach was introduced by Insall and is particularly useful in knees that are stiff from prior surgery.
    A standard medial parapatellar arthrotomy is done.
    At the proximal portion of the split in the quadriceps the arthrotomy is then extended proximally and laterally across the remaining extensor mechanism and up into the muscle fibers of the vastus lateralis (Fig. 9-6).
    The angle of the cut is the same as the angle of insertion of the vastus lateralis fibers (60 degrees) such that the quadriceps snip can extend itself further into the vastus lateralis if needed.
    Note: The quadriceps snip is quite versatile. The vast majority of difficult total knees and revision total knees can be done with a quadriceps snip coupled with adequate debridement of scar tissue from the lateral gutter and around the patella.
    The arthrotomy can be closed with multiple interrupted sutures and there is no need to alter the patient's weight-bearing status after using the quadriceps snip exposure.
  • The medial collateral ligament (MCL) may be damaged during medial release. The risk of this can be minimized by careful subperiosteal release either
    using a periosteal elevator or coagulating diathermy.
    The patella tendon may be damaged during excision of the fat pad, which can be prevented by always cutting away from the tendon itself. The patella tendon may be avulsed at its insertion to the tibial tubercle during eversion of the patella and flexion of the knee. This is a disastrous complication and can be prevented by extending the deep dissection proximally, dividing any lateral plicae and by performing a lateral parapatella release to allow eversion of the patella. External rotation of the tibia also relaxes the extensor mechanism.
    The major danger in cutting the nerve is the development of a postoperative neuroma. Because the area of anesthesia produced usually is not troublesome, do not repair the nerve if it is cut. Instead, resect it and bury its end in fat to decrease the chances that a painful neuroma will form.
  • Problems with patellar dislocation, subluxation, and osteonecrosis after total knee arthroplasty performed through an anteromedial para-patellar approach led to the rediscovery of the subvastus, or southern, anteromedial approach
  • The subvastus approach, as well as allowing exposure comparable to that obtained through the standard parapatellar approach, seems to be associated with less need to perform a lateral release, less blood loss, less postoperative pain and faster recovery of quadriceps strength, compared with standard arthrotomy.
    Potential drawbacks include the formation of a hematoma below the VMO, excessive stretching of the fibers of the VMO during displacement of the patella
    (making the procedure unsuitable for obese or muscular patients), and difficulty increasing the exposure in situations in which this is necessary.
  • Templating provides the opportunity to consider the surgical plan, correct techniques to address deformities and selection of appropriate implants11.
  • The patient is positioned supine on the operating table with a lateral thigh support and foot bolster, allowing free flexion and extension of
    the knee. Pressure areas should be protected with gel pads. Provided that there are no contraindications (e.g. arterial calcification) a padded
    pneumatic tourniquet is applied around the thigh as proximally as possible and secured. A dose of an appropriate antibiotic is administered intravenously prior to the inflation of the tourniquet. The skin in the area of the incision should be shaved immediately prior to surgery. The limb is exsanguinated and the tourniquet inflated to the desired pressure, with the tourniquet time clearly documented.
  • Classically an anterior longitudinal midline incision is used for TKA. This incision may sacrifice the infrapatellar branch of the saphenous nerve, causing an area of lateral numbness; the patient should be warned about this possibility before the surgery.
  • The retropatellar fat pad may be partially or fully excised if necessary. The visible remnants of the medial and lateral menisci may be resected at this stage and the anterior cruciate ligament (ACL) must be divided and resected. If a posterior cruciate substituting implant is to be used the posterior cruciate
    ligament (PCL) can be resected now by dissecting it from its femoral attachment with diathermy. Osteophytes may be debrided at this stage
  • The primary goals of surgery are pain relief, restoration of function and longevity of the prosthesis. The immediate technical aims of the operation are: anatomical alignment, good range of motion, good stability and ligamentous balancing throughout the range and good patella tracking. Achievement of all these goals can only be accomplished by accurate bone cuts, equal flexion/ extension gaps, correct soft tissue balancing, adequate fixation of implants and by addressing any patellofemoral problems, while minimizing the risk of any adverse intraoperative events. The surgeon must appreciate that a total knee replacement is as much a soft tissue operation as a bony procedure.
  • In the vast majority of cases, the bony cuts can be made in the conventional manner with the use of standard instrumentation. Whether the femoral
    or tibial cut is made first depends on the surgeon’s preference and type of prosthesis used
  • Femoral preparation is undertaken with the knee flexed and the patella everted. A large drill bit is used to create entry point in the distal femoral canal at a point approximately 1 cm anterior to the insertion of the PCL within the trochlear notch. The entry point can be slightly widened with a rotational movement of the drill. The intramedullary rod should be inserted into the canal with care, especially if a previous total hip replacement has been performed. The distal femoral cutting jig is positioned over the rod and adjusted so that the distal cut is set at a 5–9° valgus angle to the appropriate side of the knee to be replaced. Ideally, this should be chosen to match the anatomical axis of the contralateral limb, if normal. The distal cutting jig is secured with two or three pins which should be fully inserted to ensure that the saw is not hampered and to allow the saw blade to make ample excursion to complete the cut
  • Open the femoral canal with the 9.5mm
    Intramedullary Drill. The drill has a 12mm step to
    open the entry point further. If desired, use the
    drill to open the tibial canal at this step.
    2 Use the Quick Connect T-Handle to insert
    the 8mm Intramedullary Rod into the
    femoral canal.
    3 Slide the Distal Femoral Cutting Block assembly
    over the Intramedullary Rod until the Valgus
    Alignment Guide touches at least one of the
    distal femoral condyles.
    4 Orient the rotation of the assembly neutral to
    either the A-P or Epicondylar Axis. If desired,
    pin through the Valgus Alignment Guide with a
    Headed Bone Spike.
    5 Use Trocar Pins to secure the Distal Femoral
    Cutting Block to the anterior femur through the
    two holes marked “0”. It is advised to pre-drill
    the holes to prevent liftoff of the assembly.
    6 Again, verify that the Valgus Alignment
    Guide is touching at least one of the distal
    femoral condyles.
  • Femoral preparation is undertaken with the knee flexed and the patella everted. A large drill bit is used to create entry point in the distal femoral canal at a point approximately 1 cm anterior to the insertion of the PCL within the trochlear notch. The entry point can be slightly widened with a rotational movement of the drill. The intramedullary rod should be inserted into the canal with care, especially if a previous total hip replacement has been performed. The distal femoral cutting jig is positioned over the rod and adjusted so that the distal cut is set at a 5–9° valgus angle to the appropriate side of the knee to be replaced (Fig. 11.3). Ideally, this should be chosen to match the anatomical axis of the contralateral limb, if normal. The distal cutting jig is secured with two or three pins which should be fully inserted to ensure that the saw is not hampered and to allow the saw blade to make ample excursion to complete the cut
  • The distal femur must then be sized to enable placement of the appropriate cutting block. Sizing jigs generally work on an anterior or posterior referencing system, using either the anterior distal femoral cortex or the posterior femoral condyles as the baseline, measuring the amount of anteroposterior resection required accordingly.
    The typical sizing jig has an anterior stylus that must be seated down onto the anterior cortex, and it may be necessary to remove the overlying synovium in order to ensure that the component is not oversized. When the desired size is estimated, marker holes are made on the distal femur through the appropriate holes on the jig, to enable positioning of the distal femoral cutting block.
  • The cutting block of the estimated size is placed onto the cut surface of the distal femur, with pegs sitting into the previously drilled marker holes. In order to avoid notching of the distal femur during cutting, a cutting guide, commonly referred to as an ‘angel wing’, can be placed through the chosen cutting slot to estimate the exit point of the anterior cut.
    The cutting block is firmly impacted until seated flat onto the cut surface of the distal femur and secured with obliquely placed pins.
  • If there is any difficulty in seating either the sizing jig or cutting block, the surgeon must check that all osteophytes are removed, that there is adequate meniscal resection, that the bone cuts are complete and that the soft tissues are retracted sufficiently.
  • The tibial cut should be made perpendicular to the axis of the tibia in the coronal plane with an anteroposterior slope of approximately 3° in the sagittal plane (Fig. 11.5). If intramedullary referencing is used, the entry point should be made with a drill at the centre point of the tibia.
  • The intramedullary rod should be inserted comfortably into the tibial canal and the cutting block adjusted in a varus knee to allow resection of approximately 10 mm from the more normal lateral compartment and approximately 2 mm
    In a valgus knee the amount of tibial resection can be more difficult to estimate, but should generally extend to the level of the tip of the fibula head on
    the lateral side
  • When at the correct height, as confirmed with a stylus passed through the slot on the tibial cutting block and onto the tibial plateau, the cutting block can then be fixed with pins, advanced closer to the tibial surface, locked in place and the intramedullary rod removed
  • If extramedullary referencing alone is used, the rod should be in line with the anterior tibial spine and the distal tip of the rod should lie just medial to the centre of the ankle joint (as this is where the mechanical axis of the limb passes). Using anatomical landmarks in the foot, such as the second metatarsal, is less reliable as rotation can occur within the hindfoot and midfoot. With extramedullary referencing, the anteroposterior slope of the tibial cut can be introduced either by use of an angled cutting block or by adjustment of the extramedullary jig itself. If the femoral cuts have already been made, the tibia can be externally rotated and subluxed anteriorly to allow exposure of the entire articular surface of the tibia
  • After the tibial resection is complete, the remaining meniscal remnants can be excised and the tibial component is sized and, following a trial of the components, the tibia can be prepared to accept the stem or keel of the prosthesis. The tibial component should lie in slight internal rotation on the tibia, with the midpoint of the tibial baseplate being in line with the medial third of the patella tendon to optimize patellofemoral tracking .
  • Flexion/extension gaps
    The femoral and tibial cuts should be made such
    that the rectangular spaces created are the same in
    both full extension and 90° of flexion
  • The most common problems are:
    • Tight in extension, flexion satisfactory
    – Solution: increase distal femoral resection. Release posterior capsule off femur. Recess or resect the PCL. Beware of raising the joint line with excessive distal femoral resection.
    • Tight in flexion, extension satisfactory
    – Solution: downsize the femoral component by re-cutting the distal femur (beware of notching the femur when downsizing implants). Increase the anteroposterior tibial slope.
    • Tight in flexion and extension
    – Solution: increase tibial resection. Beware of losing too much tibial surface area.
    • Loose in flexion and extension
    – Solution: increase thickness of insert. Beware gross ligamentous instability.
  • Implantation of prosthesis
    Condylar knee replacement systems can be
    cemented, uncemented or a hybrid design that
    usually has a cemented tibial component and an
    uncemented femur. Uncemented implants now
    often have a hydroxyapatite coating. The
    polyethylene insert can either be modular or
    monoblock (all polyethylene or metal backed),
    and can be of fixed or mobile bearing design.
  • Following satisfactory trials, the selected components are checked by the surgeon and opened. The knee is flexed and the patella everted allowing the tibia to be subluxed anteriorly, with a Hohmann retractor or similar, and the prepared surface of the tibia exposed medially and lateral with spiked retractors. The knee is washed out thoroughly with normal saline pulsed lavage in order to expose the bone trabeculae and maximize the mechanical fixation of the cement. If sclerotic bone surfaces are present, a small drill can be used to make multiple small ‘key holes’. When intramedullary referencing has been used, many surgeons insert a bone block into the medullary canal to reduce blood loss. The knee should be thoroughly dried with suction and swabs. The cement can then be mixed and the whole surgical team should change the outer layer of gloves. In most situations, cementing of both components can be performed simultaneously, but on occasions it may be desirable to perform cementing of the components separately with different mixes of cement.
  • Cement can be applied onto the tibial surface either via a gun with short nozzle or with a spatula. The tibial component is positioned in the correct orientation and firmly seated with a soft impactor and hammer. Excess cement is removed. A trial insert is then applied to the tibial baseplate and the femur lifted up. Cement can be applied to both the exposed distal femur and implant, but as
    it is difficult to remove cement from the posterior
    aspect of the knee following implantation, in this
    region it is preferable to place the cement onto
    the prosthesis rather than onto bone. The femoral
    component must be positioned carefully in
    relation to the distal femur; in particular flexion of
    the femoral component should be avoided. The
    femoral component must be firmly impacted
    and any excess cement should be removed.
    The knee is then fully extended and axial
    compression applied (note: hyperextension leads
    to uneven cement pressurization and may cause
    posterior ‘lift-off’ of the tibial baseplate). If the
    patella is resurfaced the orientation should be
    checked and once positioned, the patella is
    compressed and held with a clamp. The knee can
    then be flexed again and any further cement
    extruded can be removed quickly. The knee is
    then extended and further axial compression
    applied. The trial insert is removed and the
    baseplate inspected to ensure that there is no
    cement or soft tissue present which may impede
    the insert. The definitive insert can then be
    positioned correctly and impacted fully using the
    appropriate instrumentation.
  • Cement can be applied onto the tibial surface either via a gun with short nozzle or with a spatula. The tibial component is positioned in the correct orientation and firmly seated with a soft impactor and hammer. Excess cement is removed. A trial insert is then applied to the tibial baseplate and the femur lifted up. Cement can be applied to both the exposed distal femur and implant, but as it is difficult to remove cement from the posterior aspect of the knee following implantation, in this region it is preferable to place the cement onto the prosthesis rather than onto bone. The femoral component must be positioned carefully in relation to the distal femur; in particular flexion of the femoral component should be avoided. The femoral component must be firmly impacted and any excess cement should be removed. The knee is then fully extended and axial compression applied (note: hyperextension leads
    to uneven cement pressurization and may cause posterior ‘lift-off’ of the tibial baseplate). If the patella is resurfaced the orientation should be checked and once positioned, the patella is compressed and held with a clamp. The knee can then be flexed again and any further cement extruded can be removed quickly. The knee is then extended and further axial compression applied. The trial insert is removed and the baseplate inspected to ensure that there is no
    cement or soft tissue present which may impede the insert. The definitive insert can then be positioned correctly and impacted fully using the appropriate instrumentation.
  • Once the cement has set, the knee can be washed out again with pulsed lavage. Some surgeons prefer to deflate the tourniquet and gain haemostasis prior to closure. However, most surgeons favour closure of the knee over a reinfusion drain and application of a pressure bandage prior to deflating the tourniquet. If a drain is used, placing the drain in the lateral gutter reduces the chance of stitching the drain in when closing the medial parapatella retinaculum.
    The tourniquet is released after the prosthesis is implanted, the knee is packed with moist sponges, and pressure is applied. Hemostasis is obtained by sequentially removing the sponges from the lateral and medial sides of the knee, looking specifically for bleeding from the geniculate arteries. Many surgeons preferred releasing tourniquet after wound closure and bandaging. This is because neither blood loss nor the frequency of wound complications has been found increased with tourniquet release after bandage application when compared with tourniquet release and hemostasis before wound closure.
  • The actual closure technique varies with surgical preference but it is important that the repair is watertight and that range of motion is maintained with no patella maltracking. Closure of the knee in flexion ensures that the correct tension is achieved. The deep layer is closed with a heavy suture (e.g. no. 1 Vicryl), by means of a continuous repair of the quadriceps tendon, interrupted repair of the parapatellar retinaculum and continuous repair of the medial capsule to patella tendon. The deep fascia can be closed as a separate layer if desired or the subcutaneous fat
    can be opposed with deep interrupted sutures.
    The deep dermal layer is closed with a continuous
    absorbable suture to allow tension-free closure of
    the skin with surgical staples or a continuous
    absorbable subcuticular suture. A sterile occlusive
    dressing and a padded compression bandage is
    applied and the drain secured with adhesive tape.
  • The actual closure technique varies with surgical preference but it is important that the repair is watertight and that range of motion is maintained with no patella maltracking. Closure of the knee in flexion ensures that the correct tension is achieved. The deep layer is closed with a heavy suture (e.g. no. 1 Vicryl), by means of a continuous repair of the quadriceps tendon, interrupted repair of the parapatellar retinaculum and continuous repair of the medial capsule to patella tendon. The deep fascia can be closed as a separate layer if desired or the subcutaneous fat can be opposed with deep interrupted sutures. The deep dermal layer is closed with a continuous absorbable suture to allow tension-free closure of the skin with surgical staples or a continuous
    absorbable subcuticular suture. A sterile occlusive dressing and a padded compression bandage is applied and the drain secured with adhesive tape.
  • Regular neurovascular, cardiovascular and respiratory observations are mandatory. Urine output, temperature and drainage should also be monitored. Adequate analgesia should be administered. Mechanical and, if indicated, chemical thromboprophylactic measures are taken. Two further doses of prophylactic antibiotics are administered at 8 hours and 16 hours after surgery. The use of a reinfusion drain allows for autologous blood transfusion.
    Haemoglobin levels should be checked 24–48 hours after the procedure. Any drains, urinary catheters, epidural lines and intravenous cannulae should be removed as soon as appropriate to avoid unnecessary portals of infection. Pressure dressings should be reduced and ice applied. Full weightbearing and active range of motion exercises should be commenced as soon as possible. The wound should be inspected and check radiographs performed prior to discharge. The patient must be declared safe for discharge and for routine cases should be able to straight leg raise and flex the knee from 0° to 90°.
    Skin clips should be removed 10–14 days after surgery and an outpatient appointment should be arranged approximately 6 weeks post operatively.
    Ideally, patients undergoing total knee arthroplasty should be followed up for life with serial radiographs, but in reality this is rarely possible.

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