Total knee arthroplasty is gradually being performed at different levels of hospitals and may seem to be a step-by-step procedural procedure that some people find seemingly complex with many instruments, but others feel as if it is not too difficult. In clinical practice, total knee replacement is one of the riskiest orthopaedic surgeries, one of the least likely to achieve the desired outcome, and one of the most likely to have complications, and when they do occur, they can have serious consequences and be difficult to manage. In the last 10 years, the number of total knee replacement surgeries in our hospital has increased year by year, from 20-30 cases per year in the past, to 100 cases in recent years after the establishment of joint surgery, with good results. Total knee surgery involves various aspects from anesthesia, sterilization and towel laying to soft tissue release, osteotomy, prosthesis selection and installation, and each of these aspects may affect the final outcome, and the surgical outcome is also related to the selection of surgical indications, case selection, and various treatments in the perioperative period. Therefore, total knee replacement surgery is essentially a “systemic project”, and a high degree of attention to every aspect and detail of knee replacement surgery, a full understanding of the principles of surgery, and the standardization of surgery are the guarantees of successful surgery. We report our experience of total knee replacement surgery as follows.
I. Preoperative antibiotic use.
Antibiotics were administered half an hour before opening, and prophylactic antibiotics were applied for 24 to 48 hours after surgery.
II. Upper tourniquet.
Usually a low-pressure tourniquet is used and placed on the proximal end of the thigh for 1 to 1 1/2 hours. For the average patient without severe deformity, the surgery can usually be completed in one tourniquet time. It is also an option to just use a tourniquet when the prosthesis is placed and the bone cement is applied.
III. Sterilization, draping, and aseptic concepts and techniques.
Infection is a catastrophic complication of total knee replacement; therefore, it is extremely important to prevent infection in every detail. Disinfection and spreading of towels, as well as asepsis throughout the procedure, must be strictly enforced.
(1) Strict disinfection of the entire lower extremity, including the toes, with iodine and alcohol.
(2) Close the proximal thigh with a tightly taped surgical incision paper.
(3) Toes and foot can be put in with gloves and the whole lower limb closed with incision paper.
(4) Disinfection and towel laying must be done with gloves.
(5) The operator routinely wears two pairs of gloves.
IV. Incision and exposure.
(1) Take a median knee incision, usually 12-15 cm long, and cut the skin, subcutaneous tissue, and deep fascia with a scalpel in the flexed position, carefully freeing the flap medially and separating it to the parapatellar bone. Small incisions are not recommended for those with little surgical experience.
(2) Incision is made along the parapatellar bone into the joint cavity, downward along the medial patellar ligament to the medial tibial ramus, and upward along the tendinous portion of the quadriceps muscle.
(3) The anterior femoral cortex is cleaned and exposed and used as a locator for anterior osteotomy.
(4) Depending on the specific situation, part of the synovial membrane can be removed; osteoarthritis can be cut sparingly, and rheumatoid arthritis with significant synovial inflammation can be removed.
(5) The patella is turned over, the hyperplasia is removed with a biting forceps, the patella is trimmed, and the soft tissue of the patellofemoral ligament between the patella and femur is cut.
(6) Flex the knee joint, insert the Hohmann pulling hook to reveal the medial tibial plateau, separate the bone along the medial side of the proximal tibia immediately until the medial and posterior aspects of the tibial plateau are revealed, and remove the medial and posterior bony redundancy of the tibial plateau. The extent of release should be selected according to the severity of internal derangement, and the release should be gradual according to the specific severity of internal derangement.
(7) Separate along the anterolateral aspect of the tibial plateau, insert the Hohmann pulling hook, and reveal the lateral edge of the tibial plateau for separation.
(8) Posterior stable joint: remove the anterior cruciate ligament, and the femoral stop of the posterior cruciate ligament, insert the pulling hook posteriorly in the tibia, push the tibia forward, and reveal the meniscus to be removed, or temporarily not if removal is difficult at this point.
(9) Remove the hyperplastic bone at the edge of the femur and tibia to avoid affecting the measurement and osteotomy.
V. Osteotomy of the proximal tibia and distal femur.
(1) Tibial plateau osteotomy: Extend the pull hook to the posterior of the tibia to reveal the tibial plateau, put in the tibial osteotomy extra-medullary osteotomy positioner, and pay attention to adjust the tibial plateau posteriorly by 3~7 degrees, and rotate the plateau to posteriorly by 0 degrees. The tibial osteotomy plane is perpendicular to the longitudinal axis of the lower leg (long axis), and the tibial plateau osteotomy plane can be adjusted and detected with a calf force line measuring rod, the distal end of which should point between the 1st and 2nd toes or between the inner and outer ankle (or slightly medially) when the foot is in neutral position.
The thickness of the tibial osteotomy is either 1 to 2 mm on the severely worn side of the plateau (usually on the medial side of the tibia in the case of internal knee valgus) or 8 to 10 mm on the lightly worn side (usually on the lateral side of the tibial plateau in the case of internal knee valgus). if there is no significant internal or external valgus, the tibial plateau is osteotomized 8 to 10 mm. the total osteotomy is usually 8 to 10 mm, and generally not more than that. The consequences of more osteotomy include reduction of tibial weight-bearing area, osteoporosis, change of osteotomy line, etc., which is not conducive to prosthetic stability, long-term survival and mechanical requirements.
In general, the tibial plateau has approximately 3 degrees of internal rotation and, in most patients, exhibits internal rotation. Therefore, when osteotomies are performed in the vertical tibial long axis, there are mostly fewer medial osteotomies and more lateral osteotomies of the tibial plateau.
When osteotomizing the tibial plateau, care should be taken to protect the patellar ligament, posterior knee tissue, and lateral collateral ligament from damage to these structures by the saw blade. The consequences of injury are serious. After the osteotomy, the bone around the plateau is removed and the meniscus is further removed.
(2) Distal femoral osteotomy: Open the medullary cavity of the femur with an electric drill, paying attention to attracting the fatty tissue in the medullary cavity so as not to cause fat embolism. The long medullary positioning rod is inserted to ensure that it enters the medullary cavity smoothly and is located in the center of the medullary cavity (the center of the coronal and sagittal planes), and the distal femoral osteotome is placed, with the left and right sides distinguished, and the valgus angle is taken to be 6-7 degrees, and the osteotome is 9 mm (the same as the thickness of the prosthesis). Fix the osteotome for distal femoral osteotomy.
(3) Detection of extension gap and lower limb force line: Place the lower limb in the extension position and put in the extension gap measuring block to detect the extension situation and whether the lower limb force line meets the requirements.
Put in the lowest thickness Spacer in the extension position (in Depud products, the knee gap requirement for the thinnest pad of the fixed platform is 8mm is 16mm, i.e. Spacer thickness is 16mm and rotating platform is 18mm).
The Spacer is placed and the platform is initially tested for internal and external rotation with a force line measuring rod. If there is internal and external turning of the platform osteotomy surface, it should be treated appropriately, which can be done directly by careful thinning with a chainsaw blade.
(4) Treatment of inadequate knee clearance.
After osteotomy of the distal femur and proximal tibia, the knee joint gap should be able to initially reach the minimum gap thickness and the thinnest Spacer should be able to be put in. if it cannot be put in, the following treatment methods are used.
(1) If they are similar, within 1 to 2 mm, the gap can usually be achieved after osteotomy of the posterior femoral condyle, removal of the posterior and lateral growths, and then appropriate soft tissue release.
(2) According to the specific situation, if the tibia or femur is not osteotomized enough during the initial osteotomy, 2mm can be added, but the gap requirement cannot be obtained by osteotomy, and should be combined with soft tissue release.
(3) If the gap is too narrow and the minimum gap requirement cannot be achieved by soft tissue release alone, another osteotomy should be considered, and another osteotomy of the femur should take into account the attachment of the lateral collateral ligament and the upward shift of the joint line. If the tibial plateau is osteotomized again, the cross-sectional area and bone quality of the plateau should be considered. If the plateau is osteotomized distally, the weight-bearing cross-sectional area will become smaller and the bone quality will be more lax, which will be unfavorable to the placement of tibial prosthesis. Therefore, the problems caused by osteotomy should be fully considered when osteotomy is performed again. The osteotomy should be adequately combined with soft tissue release and balancing, and all bone fragments should be adequately cleared.
Preoperative photographs of the joint space without significant narrowing and no significant flexion deformity on preoperative physical examination usually make it easy to achieve the gap requirements usually with conventional osteotomies. If there is significant narrowing of the knee joint space with significant flexion and valgus deformity, more osteotomy and soft tissue release is usually required than conventional. Both osteotomy and soft tissue release need to be gradual and not “one step at a time”.
VI. Selection of femoral prosthesis size and osteotomy.
According to the characteristics and requirements of each company’s product measurement to choose the model, if the measurement is located between the two models, usually choose the smaller model. In the case of front-referenced products, a small model will cut the posterior femoral condyle more, possibly causing laxity in flexion, but a large model is not conducive to flexion activities, causing flexion of the knee too tight. How much the posterior condylar osteotomy will affect the flexion gap, therefore, in practice, the choice of model size should be decided according to the balance of flexion and extension gap.
When using the posterior reference guide, attention should be paid to the problems that may arise when the measurement is located between the two models, i.e., when using the small osteotomy plate, there may be too much osteotomy in front of the femur, which may damage the anterior bone cortex; and when choosing the large one, there is a possibility that the osteotomy in front is not enough, which may cause the patellofemoral track to be too tight and affect flexion. In this case, a large guide plate can be used for positioning and a small guide plate for osteotomy, which can take into account the increased osteotomy volume of the anterior and posterior sides.
Once the surgical principles are understood, both anterior and posterior references can be adjusted to the specific situation, with the goal of obtaining a prosthesis that fits the patient’s femur, with a flat anterior femoral cortex anteriorly and a reasonable flexion gap (maintaining the eccentric distance of the posterior femoral condyle) posteriorly.
In femoral prosthesis placement, attention also needs to be paid to the external rotation of the prosthesis, which can be handled using the methods already set by the company (usually 3 degrees of external rotation based on the posterior femoral condyle, such as the prosthesis self-contained, or 3 degrees of external rotation of the osteotomy plate positioning, etc.). In complex cases, a combination of the anterior-posterior femoral condyle axis (Whiteside line), the internal and external epicondyle axis, the posterior femoral condyle line, and the gap method can be applied for evaluation. Especially when there is a localized bone defect in the posterior condyle, it is obviously not reasonable to use the posterior condyle method, and other methods of assessment are needed at this time.
VII. Osteotomy and testing of other surfaces of the femur, treatment of the intercondyles.
The other surfaces of the femur are osteotomized in accordance with the osteotomy plate, with attention to the osteotomy of 3 degrees of external rotation of the femur. Usually, the osteotomy of 3 degrees of external rotation can be achieved by following the relevant requirements of the company, and the posterior condyle of the femur is cleaned after the osteotomy to remove the free body and bone redundancy located in the posterior condyle. The corresponding Spacer is placed in the flexion position and tested for compliance with the product requirements. The corresponding joint gaps in extension and flexion should be obtained. If the flexion gap is tight the posterior femoral soft tissue can be released appropriately.
After osteotomy of the posterior femoral condyle and all facets, the knee gap is quite clearly and adequately revealed, allowing further removal of the meniscus and posterior cruciate ligament, removal of the bony tuberosity, and further soft tissue release depending on the specific contracture.
Adjustments can be made accordingly to the loosening and tightening in flexion and extension, including appropriate osteotomy of the femur or tibia, appropriate further release, and selection of polyethylene spacers of different thicknesses. The goal is to obtain a prosthesis that can be fully extended after implantation, can be flexed over 120 degrees in its natural state, and will not be too tight or too loose in both extension and flexion.
VIII. Testing of the trial mold, testing and treatment of the gap, testing and treatment of internal and external rotation.
Punch in the femoral trial mold, put the tibial trial mold in and test the following.
(1) Whether the flexion and extension joint gaps are appropriate.
(2) Whether the knee joint can be fully extended and slightly hyperextended.
(3) Test joint stability: test bilateral lateral collateral ligament tension and balance; medial and lateral knee tension should be balanced after placement of the prosthetic specimen, with no excessive tension or laxity on one side.
(4) Placement of the tibial trial mold with a mechanical test rod to test the lower extremity force line and whether there is still internal and external rotation.
(5) The degree of flexion in the natural state.
(6) Preliminary understanding of the sliding trajectory of the patella at the femoral condyle.
(7) Determine the rotational position of the tibial prosthesis in the platform.
IX. Selection of tibial prosthesis size and treatment of tibial prosthesis platform.
The tibial prosthesis model is selected with reference to the size of the tibial platform, in principle, is to choose the tibial prosthesis model covering the largest tibial platform, preferably the same as the femur model, many companies’ products can choose a model larger or smaller than the femoral prosthesis model. In accordance with the requirements of each company’s tibial prosthesis processing platform, tibial prosthesis medial, anterior side can not exceed the bony edge of the tibia.
X. Patella treatment.
Normal patella morphology and no obvious wear can eliminate the need for patella replacement. Removal of the peripatellar bone growth.
Requirements and conditions for patellar replacement.
(1) Patella thickness of 12 cm after osteotomy.
(2) No greater than the thickness of the original patella after placement of the thinnest patellar prosthesis.
(3) No patellar fracture should occur.
Patella replacement is required.
(1) Measure the thickness of the patella.
(2) Select the appropriate amount of osteotomy according to the thickness and patella size, preserving at least 12 mm of thickness.
(3) Treat the osteotomy surface.
(4) Place the patella centrally, or medially.
XI. Retesting.
Place the trial mold of femur, tibia and patella into position and test again for flexion and extension, internal and external rotation looseness, lower extremity force lines and patellar trajectory. If the patella has a tendency to dislocate laterally during flexion, the lateral patellar support band can be appropriately loosened, which is conducive to improving the patello-femoral glide trajectory.
XII. Flushing and fitting of prosthetic products.
A large amount of sterile water rinsing, preferably with pulse rinsing, absorbing water to keep the bone dry, knee flexion position, fully reveal the tibial plateau with a pull hook, place the tibial and femoral prosthesis with bone cement, and make sure to fully reveal the tibial plateau and distal femur before formal placement.
Before the cement has cured, the liner is placed into the tibial prosthesis, the joint is repositioned, and the joint is placed in the straightened or hyperextended position.
The cement is typically cured in 12 minutes, the exposed cement is removed, the tibial prosthesis is exposed, and a liner of appropriate thickness is selected and driven into the tibial prosthesis. Test for no loosening.
XIII. Irrigation, hemostasis, suturing, drainage, and dressing.
Rinse with plenty of water and put tourniquet to stop bleeding of small vessels with active bleeding. Put drainage tube and close by level. In addition, some people put tourniquets only after all of them are closed and bandaged. Some people do not put drainage tubes. Each surgeon chooses according to his or her experience, with the goal of not interfering with wound healing, not increasing the complication rate, and not interfering with functional recovery. The skin fusion must be meticulously sutured to the subcutaneous tissue with good skin alignment. Finally, the knee joint is wrapped with a thick cotton pad with pressure, preferably with an elastic bandage from the calf to the thigh.
XIV. Precautions.
(1) Strict sterilization and towel laying, strict aseptic concept and technique.
(2) Appropriate, reasonable and correct soft tissue release and balance, with gradual release.
(3) Reasonable osteotomy, the amount of osteotomy should be measured with a thin steel blade before each osteotomy; increasing the amount of osteotomy should not be used as a substitute for proper soft tissue release.
(4) Correctly judging the flexion-extension gap and the stability of the joint.
(5) Emphasize strict asepsis and minimally invasive concepts (non-small incisions), protect the skin, subcutaneous tissue, and periprosthetic soft tissues, and avoid overstretching and roughly damaging the soft tissues.
(6) Refrain from excessive damage to soft tissues and loosening of soft tissues.
(7) Protect the collateral and patellar ligaments at all times during surgery, avoid tearing the patellar ligament when externalizing the patella and exposing the posterior aspect of the tibial plateau; do not damage the collateral ligaments when performing femoral and tibial osteotomies with a chainsaw.
(8) When operating on the posterior aspect of the knee, pay attention to the posterior vessels and nerves, and do not cut or cauterize them too deeply with the knife and electrokinetic coagulation.
(9) Intraoperatively, pay attention to the medullary cavity to aspirate the bone marrow in the medullary cavity, reduce the intramedullary pressure, and avoid fat embolism.
XV. Treatment of common problems.
(1) Knee inversion deformity: pay special attention to the removal of bony redundancy from the medial tibial plateau by loosening the soft tissue on the medial side of the tibia to reach the medial side and the lateral posterior side. The loosening is done close to the medial tibial cortical bone.
2, Knee flexion deformity: After osteotomy of the posterior femoral condyle, the posterior free body and bone redundancy should be thoroughly removed and the soft tissue of the posterior femur should be loosened with an arc-shaped bone knife.
3, Knee stiffness deformity: the incision is made in the quadriceps muscle to make an auxiliary incision if necessary, which is conducive to patellar flip or retraction. The peripatellar soft tissues are loosened, and then loosened again after osteotomy.
XVI. The most troublesome, embarrassing and difficult problems in knee arthroplasty (to avoid serious complications)
1. Patellar ligament tear: In severe flexion inversion deformity and severe narrowing of the knee gap, the patella is difficult to reveal externally and there is a risk of patellar ligament tear during difficult operation. Avoid violent strain on the patella. In order to reduce the pulling force on the patellar ligament, the patella may not be turned during surgery to reveal the tibial plateau, or auxiliary incisions and osteotomies may be used.
2, rupture of the medial collateral ligament: damage to the lateral collateral ligament when the bone is not tightened during release, or when the meniscus is removed medially, it is important to remember to avoid damage to the medial collateral ligament at all times.
3.Fracture, osteoporosis of the affected limb, caused by rough operation.
4.When installing the prosthesis product with bone cement, it is difficult to put in the prosthesis due to insufficient loosening, small gap, insufficient exposure, and insufficient experience, and the bone cement is facing the time of imminent curing. Therefore, the tibial, femoral and patellar prostheses must be placed within a seven-minute period of 3 to 10 minutes of mixing after the bone cement is added to the monobloc. If necessary, 2 packs of bone cement can be used and installed in separate sessions. This is to avoid fumbling the placement of the prosthesis.
For beginners who do not have many cases of artificial knees, frequent tests should be performed during the procedure to understand the effect of osteotomy and release and to know if the prosthesis is in place to minimize unnecessary errors.
The efficacy of total knee replacement surgery is also related to the selection of surgical indications, proper preoperative management, and postoperative rehabilitation, including potential foci of infection, control of diabetes mellitus, management of corticosteroid users, skin disease, and vascular lesions, all of which should be treated appropriately, of which surgical technique and surgical procedure management are only components. Therefore, performing a total knee replacement with good outcomes requires comprehensive knowledge and attention across the board, not just surgical technique.
We must also pay great attention to the problem of infection in total knee replacement, which is a catastrophic complication that must be given high priority. Preventing infection in total knee replacement involves various details and aspects of the perioperative period, including.
(1) Preoperative assessment of the patient’s physical condition, fitness, immunity and susceptibility factors and their management accordingly.
(2) Assessment of local skin and soft tissue conditions.
(3) Rational application of prophylactic antibiotics (preoperative, intraoperative and postoperative)
(4) Aseptic techniques for the entire procedure
(5) surgical techniques to reduce trauma
(6) proper incisional reunion
(7) proper drainage and correct postoperative wound management.
(8) Proper functional rehabilitation, including perioperative pain management and progressive individualized functional exercise.
(9) Complication prevention, including infection prevention, VTE prevention, etc.
XVII. Complications, problems, and revisions that we encountered.
(1) Infection: a relatively common complication of knee replacement, often requiring revision once it occurs.
2. Unsatisfactory postoperative joint function, mainly due to inability to fully straighten and poor flexion range, mainly related to the primary lesion, but also to the surgical technique.
3. Knee inversion or knee valgus still remains.
4. There is also postoperative knee pain, which has many complex causes.
In conclusion, total knee replacement is not always a difficult and complicated surgery, but every aspect and detail of the surgery is closely related to the efficacy and complications, and every aspect and detail is also closely related to the basic techniques of surgery at the same time, including aseptic technique, minimally invasive technique, relaxation technique, soft tissue balancing technique, and revealing technique. Neglecting the details of them may affect the efficacy and even cause serious complications. Therefore, care, care, and care should be taken for each case of total knee replacement.