With the aging of society’s population, the incidence of osteoarthritis of the knee is increasing. Artificial knee surface replacement is a procedure that has been gradually developed and popularized in the past 20 years, and is constantly being improved in its development, and has good efficacy for serious knee diseases, especially osteoarthritis. Its advantages are: precise efficacy, reliable results in resolving joint pain and rebuilding limb function, rapid postoperative recovery, and the ability to walk on the ground within a short period of time, which greatly reduces bedtime and postoperative complications in elderly patients. From March 1998 to December 2008, 390 cases of total knee arthroplasty were performed in our hospital with satisfactory clinical results.
1. Clinical data
1.1 General data
There were 390 patients in this group, 186 males and 204 females, aged 58-87 years, average 72.5 years, 156 cases of left knee, 198 cases of right knee, 36 cases of both knees, 267 cases of osteoarthritis, 118 cases of rheumatoid arthritis, and 6 cases of joint tuberculosis or other lesions. There were 96 cases of severe knee inversion, 41 cases of severe knee valgus, 83 cases of severe flexion deformity, and the duration of disease was 9 months-40 years. Stryker and Zemmer posterior stabilized prostheses were used mainly.
1.2 Surgical method
Using a supine position with a median knee incision parapatellar approach, we advocate not cutting the medial head of the quadriceps muscle, which gives good exposure except in particularly obese patients and allows earlier postoperative time to the floor and reduces postoperative knee flexion pain. The operation starts with simple synovial and osteochondral resection and joint release to completely expose the joint surface of the distal femur and proximal tibia, remove the anterior and posterior cruciate ligaments and meniscus, osteotomy of the femur and tibia according to different manufacturers’ instruments, and examination of the patellar surface and thickness to decide whether to perform patellar replacement.
Afterwards, the residual cruciate ligaments, meniscus and bones were removed, a trial mold of the prosthesis was installed to understand whether the force line, joint tightness and patellar distal trajectory of the lower limb were normal, the joint cavity was thoroughly flushed with 0.05% iodine and a large amount of water, antibiotic bone cement was prepared, the tibial and femoral prostheses were installed, and the patellar prosthesis was installed if necessary, the joint cavity was again thoroughly flushed with 0.05% iodine and a large amount of water, and a drainage tube was placed. The joint cavity was thoroughly flushed again with 0.05% iodine and plenty of water, drainage tube was placed for 24-48 hours, and the lower limb was wrapped with elastic bandage. Problems to be noted: a. Intravenous injection of effective antibiotics within half an hour before surgery; b. Intraoperative attention to the correction of the lower limb force line, pay attention to whether the patellar trajectory is normal, whether there is a tendency to dislocation; c. Pay attention to the joint tightness, do not be too loose and not too tight, intraoperative bending and straightening activities of the knee joint can be checked. d. The patella can be replaced or not depending on the situation, but its trajectory must be normal.
2. Results
This group of cases can be out of bed in 5-7 days, fully weight bearing walking under protection, knee mobility up to 90-120°, single joint replacement, bleeding in 150-600ml, stitch removal time in 14-17 days after surgery, knee mobility in extension 0° and flexion 110° or more at discharge, 2 female patients in this group refused to exercise due to fear of pain, knee mobility <90°, later after re One case was diagnosed with delayed infection due to localized fever, fluid accumulation and pain in the medial knee joint 7 months after surgery and was cured by revision. All patients were followed up for a mean time of 6-48 months after surgery and scored according to seven comprehensive scores of joint pain, pressure, swelling, mobility, presence of strangulation and walking function [2], with excellent scores of 0-3, good scores of 4-6, acceptable scores of 7-9 and poor scores of >12. The results of the follow-up are shown in Table 1.
3, Discussion
3.1 Surgical technique and postoperative recovery
The indications for surface knee replacement are severe knee lesions such as advanced osteoarthritis and rheumatoid arthritis, where the patient has relatively severe knee pain, deformation and dysfunction. We should strictly select their indications and careful preoperative physical examination. Practice has proven that: repeated design of the osteotomy angle before surgery, good exposure during surgery, adequate attention to the alignment and force lines of the limb axis, and symmetry and stability testing of the joint gap extension and flexion status after osteotomy are all decisive factors affecting the postoperative recovery.
We should maintain the joint stability and force line through soft tissue release and correct osteotomy angle intraoperatively, and make full use of the specimen for joint movement and stability testing, requiring 3-5° of hyperextension. In the case of lateral stability, it is required to “loosen rather than tighten”, because over-tightening or under-correction of flexion contracture will have a greater impact on the functional training of the joint. Our experience is that whether the flexion and extension can exceed 90° in the first week after surgery, in addition to the patient’s own factors such as fear of pain, low desire for rehabilitation and loss of confidence, the degree of intraoperative release is also an important factor, so the surgical technique is the key to postoperative recovery. At the same time, the patient should overcome the psychological fear of pain and low desire for rehabilitation and establish confidence in good joint function exercise in order to achieve good rehabilitation of the knee joint function.
3.2 Management of knee deformity
In cases of knee deformity, attention should be paid to distinguish whether the deformity is caused by a bone defect or by a compound cause such as ligamentous laxity. Most knee deformities are multiplanar, so attention must be paid to the correction of the full-length force line of the lower extremity during surgery, and compensatory osteotomy of the femur should be considered if necessary, along with the use of a stemmed prosthesis. If compensatory tibial osteotomy alone is used, attention must be paid to the balance of the medial and lateral collateral ligaments of the knee. If the deformity is caused by ligamentous laxity, consider performing a release of the collateral ligaments. For triplanar deformities, attention must be paid to the mechanical axis for deviation, paying particular attention to the effect of hip and ankle deformities on knee dynamics. If necessary, the femoral prosthesis can be externally rotated to address the poor alignment caused by partial mechanical axis offset.
Among the deformities caused by osteoarthritis, flexion deformity and internal and external knee valgus are common. Flexion contracture can occur alone or in combination with internal and external valgus deformity. Moderate flexion deformity can be relieved by careful removal of the bony tuberosity at the posterior border of the femur and the proximal femoral joint capsule. If the flexion deformity is severe (greater than 25°), safe stripping of the posterior joint capsule and the gastrocnemius muscle at the beginning of the distal femur is required, or a plate-like The posterior tibiofemoral gap is propped open with a pulling hook and the joint capsule is severed transversely. Special care should be taken to protect the common peroneal nerve when releasing severe flexion contracture deformities. In cases of internal and external derangement with flexion greater than 45°, extensive release and a restrictive prosthesis are required. Internal and external knee deformities are often associated with medial and lateral bone defects, contractures of the medial and lateral collateral ligaments, and pulling of the external and medial soft tissues.
The purpose of surgery is not only to correct the mechanical axis, but also to balance the medial and lateral soft tissues. In some cases of severe rheumatoid arthritis, often with significant bone destruction, bone cement replacement, bone grafting, and special prosthetic spacer supplementation may be given as appropriate. Individual cases of knee instability and severe damage may be considered for hinged total knee arthroplasty.
3.3 Management of patella and patellar dislocation
Preoperatively and intraoperatively, due consideration should be given to the degree of patellofemoral pathology and the trajectory of patellofemoral activity to decide whether to replace the patella. If the patellofemoral lesion is not serious, generally only the peripatellar bone and synovial membrane are removed and the patellar rim is repaired without patellar replacement, which not only makes the operation convenient, but also eliminates the source of postoperative pain and provides better postoperative results. In cases of preoperative patellar subluxation and subluxation with mild patellar cartilage degeneration, the trajectory of the patella can be restored during knee extension and flexion by repeatedly observing the trajectory of patellar activity and by doing lateral soft tissue release and external displacement of the femoral prosthesis.
In the process of patellar replacement, there are four principles: prefer thin to thick (do not exceed the original thickness), prefer small to large (do not exceed the range of the original patellar bed), prefer inward to outward (in case of incomplete coverage, it should be placed toward the medial edge), and prefer upward to downward (to avoid downward displacement of the patellar center).
3.4 Perioperative management
Close observation of the condition is needed after artificial joint replacement, especially vital sign monitoring. For some patients with rheumatoid arthritis who have been taking hormones for a long time, atrophy of the adrenal cortex may occur, and hormone protection is still continued intraoperatively and gradually reduced after surgery. Pain is a common postoperative symptom, especially during functional exercise, so postoperative analgesic pumps can be used routinely to facilitate patients’ early postoperative rehabilitation exercise.
In elderly and frail patients with combined underlying diseases, adequate preoperative preparation, consultation with relevant departments if necessary, and prevention and treatment of underlying diseases are equally important for surgery. The perioperative use of warfarin, rapid coagulation avoidance and elastic bandage, lower extremity CPM machine exercise and early postoperative activity are very effective measures for the prevention of lower extremity deep vein embolism, but when applying anticoagulant drugs, attention should be paid to the patient’s bleeding tendency and regular rechecking of blood coagulation.
Deep vein embolism and bleeding due to anticoagulation have not been found in this group of cases. In addition, the use of intraoperative bone cement with antibiotics, the application of broad-spectrum antibiotics during the perioperative period, strict intraoperative aseptic operation, and repeated flushing with 0.05% iodophor and water are also important measures to prevent infection. Except for one case of delayed, insidious infection, which was later cured by revision, no significant infection occurred in this group.
3.5 Early functional recovery exercise
After arthroplasty, the main content of early functional recovery exercise is knee mobility and quadriceps and N-flexor muscle strength enhancement exercise. In addition to restoring knee function, the purpose of knee mobility exercises is to pull contracted tissues, avoid adhesions, promote blood circulation in the lower limbs, and prevent deep vein thrombosis and embolism. The CPM machine should be used as soon as possible after surgery and adjusted for whether the knee is preoperatively deformed or flexed. The initial range of motion with the CPM machine is 0-45° and is increased by 10-15° twice daily for at least 1 hour each time, starting on the first postoperative day, requiring extension and flexion of 120° or more in 7-10 days, and gradually increasing walking function after 5-7 days on the ground.
For some patients with long-term knee lesions causing lower limb muscle strength loss, postoperative exercises such as assisted active exercise, active exercise, and active exercise against resistance can be gradually performed to enhance muscle strength, and generally after 3-6 months of functional rehabilitation exercises, this group of patients can take care of themselves or resume work, or even participate in moderate physical labor.