The basic technique of total knee arthroplasty

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Total knee arthroplasty has been carried out in different level hospitals gradually, seems to be a process of follow the prescribed order op

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Total knee arthroplasty has been carried out in different level hospitals gradually, seems to be a process of follow the prescribed order operation, some people think the equipment seems complicated, but there appears not much difficulty. In clinical practice, total knee arthroplasty is the highest risk of surgical operation in the Department of orthopedics, is not easy to achieve the desired effect of surgery, is one of the most easily occurred complications of Department of orthopedics surgery, and once complications will likely cause serious consequences and difficulties.

The total knee replacement surgery in our hospital in recent 10 years has increased year by year, from the past year, only 20 ~ 30 cases, after the establishment of joint surgery, and gradually increased to the recent years in 100 cases, achieved good results.

Total knee surgery involved from anesthesia, disinfection shop towels to soft tissue release, osteotomy and prosthesis selection and installation of various links, and each link will affect the ultimate effect, and curative effect and surgical indications, patient selection, perioperative treatment for the.

Therefore, total knee arthroplasty is essentially a "systems engineering", attaches great importance to the knee joint replacement surgery, do surgery to pay attention to every step and every detail, to fully understand the principle of operation, the implementation of standardized operation is the guarantee of successful operation. We report the results of total knee arthroplasty as follows.

Preoperative antibiotic use:

At half an hour before the use of antibiotics, application of antibiotic prophylaxis for 24~48 hours after operation.

Two, usually using low pressure tourniquet and tourniquet placed on the thigh proximal end. The use of time 1 to 1.5 hours, for ordinary patients with severe deformity, usually the operation could be completed in a tourniquet time. Can choose only in the use of tourniquet placed prosthesis, bone cement at.

Three, disinfection, paving, and aseptic concepts and techniques: infection is a catastrophic complication of total knee replacement, therefore, prevention of infection from every detail is extremely important. Sterile towels, and aseptic operation of the entire operation must be strictly enforced.

(1) with iodine and alcohol strict disinfection of the lower extremities, including the toes

(2) the proximal thigh is tightly closed with surgical incision paper

(3) toe and foot can be covered with gloves, and the whole lower limb is closed with a cut paper

(4) disinfection and spreading must be done with gloves

(5) surgeons usually wear two pairs of gloves

Four, incision and exposure

(1) the median incision of the knee joint was usually from 12 to 15cm, and the skin, the subcutaneous tissue and the deep fascia were incised in the flexion position. The operation experience of more small incision is not recommended.

(2) along the lateral incision into the joint cavity, down along the patellar ligament medial to the medial tibial tuberosity, along the four head part of muscle tendon incision

(3) to clean up and expose the anterior cortex of the femur as the location of the anterior osteotomy.

(4) according to the specific circumstances can remove part of the synovial membrane, osteoarthritis can cut, synovitis of rheumatoid arthritis patients, excision of synovial.

(5) open to the patella, osteophytes, bone rongeur bite hyperplasia dressing patella, cut the patellofemoral ligament and soft tissue between the patellofemoral, fat pad can remove part of the patellar ligament of rear, favorable and revealed the outer edge of tibial plateau.

(6) flexion of the knee, with Hohmann hook insertion medial tibial plateau revealed, medial, along the proximal tibia medial tibial plateau bone separation until close to the inside rear exposed, removing the medial tibial plateau, posterior osteophyte. According to the extent of varus severity, the extent of loosening should be relaxed.

(7) separation along the anterolateral tibial plateau, insert the Hohmann hook, showing the lateral tibial plateau edge separation

(8) after the stable joint resection of anterior cruciate ligament, posterior cruciate ligament and the femoral insertion in the posterior tibial, into the retractor, will push forward the tibia, exposed meniscus removed if the resection difficult may temporarily not cut.

(9) the removal of the femoral and tibial marginal osteophytes, so as not to affect the measurement and osteotomy.

Five. Osteotomy of proximal tibia and distal femur

(1) tibial osteotomy: into the posterior tibial retractor to expose tibial platform into the tibia bone marrow outside osteotomy localizer, pay attention to adjust the posterior tibial slope 3~7 degrees, the rotating platform is backward 0 degrees. Tibial osteotomy plane and vertical axis vertical leg (long axis), can be used leg force line measuring rod to adjust and test the tibial osteotomy plane, the measuring rod distal should point to the neutral position of the foot between the first and second toe or ankle between inside and outside (or slightly inside).

The thickness of the tibial osteotomy in the severe side of the platform (knee varus usually in the medial part of the tibia) cut 1 to 2mm of the plane, or in the light side of wear (knee varus usually in the lateral tibial plateau) osteotomy of 8 ~ 10mm. If there is no obvious internal and external, tibial plateau osteotomy 8 ~ 10mm. The total bone mass is generally in the 8~10mm, generally do not cut, the consequences of multiple cuts, including the reduction of tibial bearing area, osteoporosis, osteotomy line changes, is not conducive to the stability of the prosthesis, long-term survival and mechanical requirements.

In general, the tibial plateau was approximately 3 degrees varus, and most patients showed varus. Therefore, when the vertical tibial long axis osteotomy, most of the medial tibial plateau osteotomy and less lateral osteotomy.

Tibial osteotomy should pay attention to protect the patellar ligament, knee ligament, posterior lateral organization, do not damage the structure by the saw blade. Once the damage is serious. Osteotomy after removal of osteophytes around the platform, further resection of meniscus.

(2) the distal femoral osteotomy: to drill through the femoral medullary cavity, attract the attention of the medullary cavity of adipose tissue, so as not to cause fat embolism. Into the medullary cavity of the positioning rod, the positioning rod to ensure the medullary cavity smoothly into the medullary cavity and is located in the medullary cavity of the central (coronal and sagittal Center), into the distal femoral osteotomy device, to distinguish between left and right side, take 6 ~ 7 degrees valgus angle, 9mm osteotomy (with prosthesis thickness). Fixed osteotome for distal femoral osteotomy.

(3) to detect the clearance of the extension position, and to detect the lower limb force line: the lower limb is placed in the straight position, and the gap measuring block is placed in the extension position.

In the straight position into the minimum thickness of the Spacer (in the Depud product, the fixed platform of the thinnest pad for the 8mm of the knee joint gap requirement is 16mm, that is, Spacer thickness of 16mm, rotating platform 18mm).

Into the Spacer, the initial strength of the rod to measure whether the test platform inside and outside. If there is a varus osteotomy platform, should be properly treated, can be directly used for processing thin films were carefully.

(4) treatment of insufficient knee joint space

In the distal femur and proximal tibia osteotomy, the knee joint gap should be able to achieve the minimum gap thickness, should be placed in the thinnest Spacer, such as not to be put into use the following approach:

(1) if not much difference, between 1 to 2mm, usually in the posterior condylar osteotomy after removal of the posterior and lateral osteophytes, then make proper soft tissue release, clearance can meet the requirements.

(2) according to the specific circumstances, if the osteotomy of the tibia or femur is insufficient, the 2mm. However, it is not possible to obtain the gap requirement by osteotomy, and should be combined with soft tissue release.

(3) if the gap is too narrow, it can not be achieved simply by soft tissue release to achieve the minimum gap requirements, should be considered once again osteotomy, femoral osteotomy should be considered the lateral collateral ligament attachment and joint line up. Tibial plateau osteotomy need to consider the cross-sectional area of the platform and the bone, the platform to the distal osteotomy, bearing cross-sectional area will become smaller, more loose bone, will not be conducive to the placement of tibial prosthesis. Therefore, the osteotomy should be fully taken into account the problems brought about by osteotomy. Osteotomy should be combined with soft tissue release and balance, all osteophyma should fully clean up.

There was no obvious narrowing of the joint space before the operation, and there was no obvious flexion deformity before operation. If the knee joint space is narrow, there are obvious flexion and internal and external deformities, usually more than conventional osteotomy and soft tissue release. Osteotomy and soft tissue release need to step by step, not a step in place".

Six, the size of the femoral prosthesis selection and osteotomy

According to the characteristics and requirements of each company to choose the model, if the measurement is located between the two models, usually choose a small model. If this is the first reference product, smaller models will cut more posterior femoral condyle, may cause relaxation during flexion, but the model is too large to cause flexion, knee tight. How much will affect the posterior condylar osteotomy knee clearance, therefore, in practice should be based on the balance of flexion and extension space size selection decision.

The use of reference guide, should pay attention to when the measurement is located between the size of two types when the choice of possible problems, namely the use of small plate anterior femoral osteotomy may be excessive osteotomy, the anterior cortex injury; and the choice of size, may lead to problems in front of the osteotomy, patellofemoral tight track effect of buckling. When available, large plate positioning, small plate osteotomy, which can take into account the osteotomy before and after the party.

In the understanding of the operation principle, whether before or after the reference is a reference, can be adjusted according to the specific circumstances, the goal is to achieve for patients with femoral prosthesis placement, the front need flat anterior femoral cortex, posterior flexion joint clearance to maintain reasonable (maintenance of femoral condyle after eccentricity).

In the femoral prosthesis placement, also need to pay attention to external rotation prosthesis placement, can use the company has set a good manner (usually in the posterior femoral condyle based external rotation of 3 degrees, such as prosthesis with external rotation osteotomy or plate location 3 degrees etc.). In complex cases, can before and after application of femoral condylar axis (Whiteside line), transepicondylar axis, comprehensive evaluation method, line clearance of condyle femur after. Especially when there is a local bone defect in the posterior condyle, it is unreasonable to use the posterior condylar method.

Seven, the other side of the femur osteotomy and testing, treatment of intercondylar.

In accordance with the osteotomy plate femoral osteotomy and other surfaces, pay attention to 3 degrees external rotation osteotomy of femur, usually in accordance with the relevant requirements of the company's osteotomy can reach 3 degrees of external rotation osteotomy, osteotomy after posterior femoral condyle to clean up, removal of loose bodies located in the posterior condylar and osteophyte. Place the appropriate Spacer in the flexion position to test whether the product meets the requirements of the product. The corresponding joint space should be obtained with extension and flexion. If the flexion space is tight, the soft tissue of the posterior femur can be loosened.

The posterior condylar surface and various osteotomy, joint space is clear and fully exposed, can further resection of meniscus, posterior cruciate ligament, removal of osteophytes, and soft tissue release further according to the specific situation of contracture.

It can be adjusted according to the elastic position of the flexion and extension, including the appropriate osteotomy of the femur or tibia, the appropriate further release, the choice of different thickness of polyethylene gasket, etc.. The goal is to obtain the implant should be reached completely straight, can be in the natural state of more than 120 degrees flexion extension and flexion, are not too tight or too loose.

Eight, test mode test, clearance test and treatment, internal and external test and treatment

Into the femur test mode, put the tibia test mode, test the following:

(1) whether the flexion and extension joint gap is appropriate;

(2) whether or not the knee joint can be completely extended and slightly stretched;

(3) to test the stability of the joint: to test the tension and balance of the bilateral collateral ligaments, and to maintain the balance between the internal and external tension of the knee;

(4) put the mechanical test bar into the tibia test mode and test the lower limb force line;

(5) degree of buckling under natural conditions;

(6) to understand the sliding trajectory of patella in the femoral condyle

(7) determine the position of the tibial prosthesis on the platform

Nine, the choice of tibial prosthesis size and treatment of tibial prosthesis platform

Selection of tibial prosthesis type tibial plateau according to the size of the principle is the choice of tibial prosthesis type tibial plateau covering the largest, and the best femoral model is consistent, many of the company's products can choose a larger size than the size of femoral prosthesis or smaller type. The company processing platform in accordance with the requirements of tibial prosthesis, tibial medial anterior tibial bone edge can not exceed.

Ten, patella treatment

The patella was normal, with no obvious wear and tear, and the patella could not be replaced. Osteophyte removal of patella hyperplasia.

Patella replacement requirements and conditions: (1) the thickness of the patella after the osteotomy to have the thickness of 12cm; (2) the thinnest patellar implant is not greater than the thickness of the original patella; (3) can not occur patellar fracture.

Need to replace the patella: (1) to measure the thickness of the patella; (2) according to the thickness and the size of the patella to select the appropriate cut bone mass, at least to retain the thickness of 12mm. (3) the osteotomy surface. (4) place the center of the patella, or place it inside.

Eleven, test again:

The femur, tibia and patella were placed in the position of the test, and then test the flexion and extension, internal and external rotation tightness, the lower limb force line and patellar trajectory. If the patella tend to lateral dislocation in buckling, can the proper release of lateral patella retinaculum, improve patella - femoral trochlear trajectory.

Twelve, wash and install prosthesis products

A lot of sterile water, the best use of pulse rinse, drain water, keep the bone dry, knee flexion, to expose the retractor tibial plateau, with bone cement placed the tibial and femoral components, in the official placed before you expose the tibial plateau and the distal femur.

Before the bone cement was not cured, the liner was put into the tibial prosthesis and the joint was reset.

In 12 minutes, the bone cement was used to remove the exposed bone cement, to expose the tibial prosthesis, to select the appropriate thickness of the lining, and to penetrate into the tibial prosthesis. No loose test.

Thirteen, flushing, hemostasis, suture, drainage, dressing.

A lot of water, put a tourniquet on small vascular hemostasis of active bleeding. Drainage tube, according to the level. In addition, there are people all meet together, after tourniquet bandage. No drainage tube. Each doctor according to their own experience to choose, the goal is not to affect wound healing, does not increase the incidence of complications, does not affect the functional rehabilitation. The skin must be carefully stitched together subcutaneous tissue, the skin is good. Finally, the thick cotton pad pressure bandage knee joint, preferably from the calf to the thigh with elastic bandage.

Fourteen, matters needing attention:

(1) strict disinfection and spreading, strict aseptic concept and technology;

(2) proper, reasonable and correct soft tissue release and balance should be gradual;

(3) the osteotomy should be reasonable, and the number of the osteotomy should be measured with a thin steel sheet before each osteotomy;

(4) to judge the stability of flexion and extension space and joint;

(5) emphasize strict aseptic operation and minimally invasive concept (non small incision), to protect the skin, subcutaneous tissue, soft tissue around the knee, to avoid excessive traction, rough damage to soft tissue;

(6) do not damage the soft tissue and soft tissue;

(7) any time during the operation to protect the collateral ligament, to avoid tearing the patellar ligament, patellar eversion revealed tibial plateau; the femoral and tibial osteotomy with lateral collateral ligament injury is not.

(8) in the posterior part of the knee, attention should be paid to the blood vessels and nerves in the rear, which should not be cut or burned by the use of a knife or electric knife.

(9) the medullary cavity suck the marrow in surgery, reduce intramedullary pressure, avoid fat embolism.

Fifteen, dealing with common problems

1 knee varus: pay special attention to the removal of the medial tibial plateau osteophyma, soft tissue release reached inside and side behind the medial tibia. Close to the medial cortex of the tibia.

2: flexion deformity of knee posterior condylar osteotomy after complete removal of the rear of the free body and osteophytes, with curved bone knife loosening of femoral posterior soft tissue.

3 stiff knee deformity: incision in the stock of the four muscles when necessary to do auxiliary incision, is conducive to the patella flip or pull open. Loosen the soft tissue around the knee, and then release it again.

Sixteen, the knee joint replacement in the most troublesome, most embarrassing, the most difficult to deal with the problem (to avoid serious complications)

1 ligament tearing: in severe flexion and knee varus gap stenosis, patella to valgus revealed difficulties in the operation there is a possibility of patellar ligament tear. Avoid violent pull patella. In order to reduce the tension of the patellar ligament, the surgical exposure of tibial plateau can not turn the patella, or the use of auxiliary incision, osteotomy and other measures.

2 medial collateral ligament rupture: in the loose when not close to the bone, or the medial meniscectomy, the injured side of the collateral ligament, at any time to remember to avoid the injury of the medial collateral ligament.

3 fractures, limb osteoporosis, rough operation caused by.

4 when the bone cement is used to install the product, it is difficult to put into the prosthesis because of the loose solution, the small gap, the lack of experience and so on. Therefore, seven minutes after the bone cement is added to the monomer, stirring for 3 minutes to 10 minutes, the tibia, femur and patella prosthesis must be placed. If necessary, 2 packs of bone cement can be installed separately. In order to avoid the rush to make the prosthesis is not in place.

For the purposes of artificial knee joint with the number of beginners, should always be tested during the operation, understand the osteotomy and release effect, understand the prosthesis is in accordance with the requirements, try to reduce unnecessary mistakes.

Effect of total knee replacement surgery and surgical indications, correct preoperative treatment, postoperative rehabilitation and so on, including potential infection, diabetes control, patients taking corticosteroids, treatment of skin disease and vascular disease shall be given reasonable treatment, surgical techniques and surgical treatment is just one part of the process. Therefore, the implementation of total knee arthroplasty to achieve a good effect requires comprehensive knowledge, comprehensive attention, not just the surgical technique.

We also have to pay great attention to the infection of total knee arthroplasty, which is a catastrophic complication, we must attach great importance to. Total knee replacement surgery to prevent infection related to perioperative with every detail, including: (1) preoperative patients physical condition, physical fitness, immunity and predisposing factors were evaluated and treated accordingly; (2) to assess local skin and soft tissue conditions; (3) the reasonable application of preventive antibiotics (preoperative, intraoperative and postoperative); (4) the whole process of aseptic technique; (5) reduce the surgical trauma and technology; (6) the right incision on; (7) reasonable drainage and correct postoperative wound treatment; (8) the functional rehabilitation of the right, including pain management Wai during the operation of individual exercise step by step; (9) the prevention of complications, including infection prevention, prevention of VTE.

Seventeen, we encountered complications, problems, and overhaul

1 infection: relatively common complications of knee replacement, often need to be revised.

2 postoperative joint function is not satisfactory, the main performance is not completely straight, the flexion range is not good, mainly with the primary lesions, but also related to the surgical technique.

3 remain genu varus or valgus knee.

4 knee pain after the operation, there are many reasons, very complex.

In short, total knee arthroplasty is difficult complex surgery, but the surgery every link, every detail is closely related to the efficacy and complications, and details of each link and also the basic techniques and surgery are closely related, including aseptic technique, minimally invasive technique, release technology, soft tissue balance technology, exposure technology etc.. Ignore the details, may affect the efficacy, and even cause serious complications. Therefore, care should be taken for each case of total knee arthroplasty.

 

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