Cementless, Cruciate-Retaining Primary Total Knee Arthroplasty Using Conventional Instrumentation

Background: Total knee arthroplasty (TKA) is commonly indicated for patients with severe tibiofemoral osteoarthritis in whom nonoperative treatment has failed. TKA is one of the most commonly performed orthopaedic surgical procedures in the United States and is associated with substantial improvements in pain, function, and quality of life 1–3 . The procedure may be performed with cemented, cementless, or hybrid cemented and cementless components 4,5 . Cementless TKA utilizing contemporary implant designs has been demonstrated to have excellent long-term survival and outcomes in patients who are appropriately indicated for this procedure 5–8 . The preference of the senior author is to perform this procedure with use of a cruciate-retaining implant design when feasible, and according to the principles of mechanical alignment to guide osseous resection. It should be noted that nearly all recent studies on outcomes following cementless TKA utilize traditional mechanical alignment 7–9 . Alternative alignment strategies, such as gap balancing and kinematic alignment, have not been as well studied in cementless TKA; however, preliminary short-term studies suggest comparable survivorship with restricted kinematic alignment and gap balancing compared with mechanical alignment in patients undergoing cementless TKA 10,11 . Description: Our preferred surgical technique for cementless TKA begins with the patient in the supine position. A thigh tourniquet is applied, and a valgus post is set at the level of the tourniquet. A flexion pad is also placed at 90°, with a bar at 20°. After sterile skin preparation and draping, a time-out is conducted, and the tourniquet is raised. The surgeon makes a medial parapatellar incision, which begins from 1 cm medial to the medial edge of the patella, extending from the tibial tubercle to 2 fingers above the proximal pole of the patella, using a knife and with the knee at 90° of flexion. Scissors are then used to find the fat above the fascia and dissect distally in the same plane. A knife is used to perform a high vastus-splitting, medial parapatellar arthrotomy. Pickups and scissors are then used to perform a partial medial synovectomy, and electrocautery is used to perform a medial peel. As the procedure progresses further medial, the infrapatellar fat pad is excised, followed by the anterior femoral synovial tissue. The surgeon then cuts through the anterior cruciate ligament footprint and origin with the knee flexed before sawing through the tibial spines to decrease the height of the tibial bone block. To prepare the femur, a step drill is inserted into the femoral canal, and the intramedullary alignment guide is placed with the distal femoral cutting guide set to 5° of valgus. The distal femoral cutting guide is then pressed firmly against the distal femur, making sure that the medial side is touching bone, and threaded pins are inserted in the cutting guide under power. The distal femur is then precisely sectioned with use of an oscillating saw equipped with a 21 mm x 90 mm x 1.27-mm saw blade. The surgeon focuses on initiating the cut at the cortices before proceeding further, to avoid cortical blow-out. The resultant cut is meticulously assessed for uniformity and levelness, employing both the alignment rod and the distal cutting guide for verification. Following this assessment, the pins and guide are removed, and any remaining femoral condylar osteophytes are delicately excised with use of a rongeur. The surgeon uses the femoral sizing guide, measures the size of the femur, and double-checks rotation in preparation for the remaining distal femoral cuts. The holes are then drilled to set the rotation for the 4-in-1 cutting guide. When applying the 4-in-1 cutting guide, care is taken to align the guide with the drilled holes in order to avoid inadvertent malrotation. The secure fixation of the block is ensured through the judicious insertion of 2 threaded pins under power at full speed, followed by a more controlled, slower securing process to avoid stripping the threaded pins. Subsequently, the anterior cut is made with the oscillating saw, again with a focus on initiating the cut at the cortices before proceeding further. The posterior cuts are then made in a controlled manner, employing a gentle bouncing technique to facilitate tactile feedback, and keen attention is given to cutting both the medial and lateral cortices of each of the posterior condyles. The anterior chamfer and posterior chamfer are similarly osteotomized. Subsequently, the 4-in-1 cutting guide is gently removed. To complete this phase of the procedure, a curved osteotome and mallet are employed to delicately extract the resected posterior condyles and remove posterior osteophytes as needed. The concave side of the curved osteotome is used with precision to meticulously trace the contours of the condyles, ensuring a precise result. The surgeon places a bump under the knee and extends it to check the medial collateral ligament, quadriceps tendon, patellar tendon, and posterior cruciate ligament to ensure they are intact. To make the tibial cut, the extramedullary alignment guide is placed, and the height of the slot is set to the level of the subchondral bone, aligning the rotation and coronal axis with the 2nd metatarsal. The tibial slope is also set at this step, with the goal of the resection matching the patient’s native tibial slope. Matching is usually achieved by visual inspection of the trajectory of the cutting jig, although the stylus can also be utilized to confirm the appropriate tibial slope. The tibial cut is then completed with use of an oscillating saw. A single-sided reciprocating saw is then used to cut perpendicular to the plateau in the medial compartment while making sure not to extend the cut into the unresected portion of the intact tibial plateau. After removal of the medial plateau fragment, a lamina spreader is placed in the medial compartment; this process is repeated with a second cut in a similar fashion in the lateral compartment to create a triangular bone block that fully preserves the insertion of the posterior cruciate ligament. The medial and lateral menisci are resected, and the gaps are checked with use of a spacer block and alignment rod. The surgeon then sizes the tibia and uses their index fingers to feel both medially and laterally for overhang. An alternative approach is to fully expose the tibia in flexion and to size the tibia under complete visualization of the tibial margins. The tibial trial is then pinned in place after ensuring appropriate external rotation and optimal tibial coverage without overhang. The femoral and tibial trial components are placed, and the surgeon tests 7 things: (1) overall varus-valgus alignment in full extension; (2) degree of extension (specifically noting any amount of recurvatum or flexion contracture); (3) flexion to gravity; (4) anteroposterior stability in flexion (using manual anterior-posterior translation of the tibia); (5) varus-valgus stability in extension, mid-flexion, and full flexion with use of a manual dynamic varus-valgus stress test; (6) patellar tracking; and (7) component rotation. At this point, if any of the above checkpoints are not within acceptable tolerances, additional ligamentous releases or cuts may be performed. After the surgeon is satisfied with the positioning and stability of the trial components, the tibial preparation is completed by seating the feet of the tibial bushing into the tray and drilling the tibia, then punching out the keel. The pins and the tray are removed, the retractors are taken out, and the knee is extended. The surgeon then performs a pulse lavage of the femur and tibia with normal saline solution. The final components are opened, attached to the inserters, and placed in plastic coverings. The final tibial baseplate is inserted and impacted, followed by the femoral component in a similar fashion. We ensure that no soft tissue is incarcerated under the components after impaction. A trial bearing is placed, and the knee is extended. The joint space is then bathed in approximately 500 mL of sterile 0.35% povidone-iodine solution, followed by pulsatile lavage with 1 L of sterile isotonic sodium chloride solution without antibiotics. Stability is then tested again, testing the (7) checkpoints previously discussed. At this point, the only modification that can be made is an increase or decrease in the polyethylene component. Our belief is that any additional changes that require removal or repositioning of the previously implanted cementless femoral and tibial components warrant modification to the cemented TKA. Once satisfied with the stability of the real implants and the trial tibial articular surface, the final polyethylene component is inserted. Finally, the tourniquet is released. The surgeon then irrigates the wound again and closes the arthrotomy and skin. Our preference is to utilize a knotless barbed suture for the arthrotomy closure, followed by 2-0 Vicryl (Ethicon) for subcutaneous closure and 2-0 monofilament knotless barbed suture for skin closure. Some surgeons may choose to utilize a non-barbed suture; however, the use of a barbed suture has been shown to be faster and equally as effective as a non-barbed suture in a large meta-analysis of patients under