- 全膝关节置换术治疗合并关节外畸形的骨性关节炎
- 作者:刘忠堂|发布时间:2011-11-16|浏览量:697次
Total knee arthroplasty using navigation system for osteoarthritis with extra-articular deformity
The total knee arthroplasty(TKA) is the predominant and efficient treatment for the end-stage destructive arthropathy of knee. It not only relieves pain, but also restores the function efficiently. Intra-operation, the proper alignment of the implanted prosthesis is critical for success of a total knee arthroplasty. Some studies showed that proper axial and rotational alignment is very important for TKA and indicated that malalignment can lead to early loosening, aberrant patellar tracking, and poor functional outcome[1-4]. Conventional mechanical alignment guides of intramedullary-based knee instrumentation systems for TKA indirectly recreate the mechanical axis using the anatomical axis. However, femoral and/or tibial angular deformities, intramedullary sclerosis, or hardware within the femoral make it difficult . The computer-assisted navigation TKA is particular fit for these situations. It directly measure the mechanical axis of lower extremity irrespective of the local landmarks and increase the accuracy of implantation [5,6].上海市第六人民医院骨科刘忠堂
Patients with femoral or tibial extra-articular deformity present a challenge for surgeons because of conventional instrumentation for the proper alignment of the lower extremity being unavailable. The deformal femoral canals can not be used by the conventional instrumentation for recreating a proper mechanical axis. Here, we present a study in which ideal mechanical and prosthetic alignment was obtained by TKA with intra-articular resection of bone and soft-tissue balancing using the computer-assisted navigation system in the patients of femoral and tibial extra-articular deformity.
Materials and Methods
Between January 2006 and December 2009, computer-assisted navigation TKAs were performed on six knees with severe arthritis in six patients, who had an ipsilateral extra-articular deformity. Of the six patients, five got the femoral extra-articular deformity because of malunion of femoral fracture. The other one had congenital defects with the ipsilateral femoral and tibial extra-articular deformity. The patients included two men and four women. The average age of these patients was 69.5 years (range,60?78rears). In all knees, the joint space being losted severely and mechanical axis malalignment were presented on the standing anteroposterior(AP) radiographs and lateral radiographs(fig.). In all cases, the extra-articular femoral deformity was severe enough to prevent to recreate proper alignment of the femur using an intramedullary rod. Standing full-length AP radiographs were obtained both preoperatively and postoperatively on all patients, and the mechanical axis of the lower extremity was measured following the method of Moreland et al [7]. A line was drawn from the center of the femoral head to the center of the knee, which was the mechanical axis of the femur. Another line was drawn from the center of the knee to the center of the ankle, which was the mechanical axis of the femur. The deviation of the lower extremity mechanical axis is based on the angle between these two lines
Surgical technique
A standard medial parapatellar approach was used in all patients. The Stryker Navigation System was used to assist the surgeon for each TKA. The informations were obtained by the computer of the navigation system, including slope of the knee, contour of the distal femur and proximal tibia, femoral rotation, and the center of the hip, knee and ankle, which was utilized to establish the mechanical axis of the lower extremity. The bone cutting based on the mechanical axis with a surface mapping guide of the image-free navigation system. All steps of TKA were performed according to the manufacturer’s guide. Intra-operatively, assessment of range of motion and soft tissue balance was performed. After a satisfactory result was accepted, the final components of the posterior cruciate-substituting Stryker knee were cemented in place. All patients did not perform patellar replacement. After the operation, the drainage was used and was removed in 24 hours. Passive movement was started on the second postoperative day. Early mobilization with full weight bearing with crutches was encouraged according to the patients’ general condition.
All patients were followed up for twelve to twenty-one months. And the involved knees were evaluated by The function scores, Knee Society Scores (KSS)[8], and Arc of knee flexion before the operation and at the latest follow-up.
Results
Preoperative mechanical alignment averaged 10.7°varus (range, 13.2°varus to 8.4°varus). postoperative mechanical alignment averaged 1.2°varus (range, 4.5°varus to 1.5°valgus). The average Knee Society Scores significantly increased from 22.17(range, 0-45) points preoperatively to 83.50(range, 77-94) at the last follow-up( p<0 .05). The average functional scores significantly increased from 49.17(range, 25-75) points preoperatively to 86.67(range, 75-100) points at the last follow-up( p<0 .05). The average arc of knee flexion significantly increased from 85°(range, 70°-110°) preoperatively to 106.67°(range, 95°-120°) at the last follow-up( p<0.05). Postoperatively, the average sagittal alignment of the tibia was 2.7°of posterior slope (range, 1.0°-5.0°posterior slope). In all patients, the balance of the involved knees were excellent. There were no superficial or deep infection in all patients, and wound healing occurred without complications postoperatively. There were no peri-prosthetic fracture or aseptic loosening prothesis occuring during the follow-up. Statistic
Discussion
Patients with severe osteoarthritis were usually treated with total knee arthroplasties for reducing the pain and increasing the knee function. Total knee arthroplasty has become a common treatment for severe osteoarthritis recently. It is sure that proper mechanical alignment and rotational alignment is critical for getting excellent prognosis of the TKA[1-4]. Mechanical alignment of knees beyond 3°varus or valgus results in higher failure rates of TKA[9]. Traditional TKA getting the proper mechanical alignment are based on the guider of intramedullary instrumentation systems using the normal anatomical axis. With the surgical technique development, most studies reported patients who had severe osteoarthritis with intra-articular deformity got the satisfactory outcome using the traditional TKA[10,11]. However, patients with femoral and/or tibial extra-articular deformity creates a changed mechanical alignment and a abnormal anatomical axis leading to make correct component position and mechanical alignment difficult. Thus, it presents a challenge for surgeons because of conventional instrumentation for the proper mechanical alignment of the lower extremity being unavailable. The traditional TKA for treating the osteoarthritis with extra-articular deformity can not get the successful outcome. Staged surgical procedures, including osteotomy of the femur or tibia, followed by the stage of traditional TKA, can be used to recreate right mechanical alignment. But, the benefits of these multiple procedures must be weighed against the increased risk of complications [微软用户1] such as increased infection rate, devitalization of skin, and arthrofibrosis[12]. However, for those cases, TKA with the computer-assisted navigation system can obtain excellent results avoiding the obstacles within one stage only. The computer-assisted navigation system use the center of the femoral head, the knee, and the ankle to calculate the mechanical aligment of the lower extremity. Thus, despite of how what extra-articular deformity[微软用户2] of the femur and/or tibia, the computer-assisted navigation system can help the surgeon figure out the mechanical alignment of the lower extremity perfectly. Based on the mechanical alignment figured out by the computer-assisted navigation system, the surgeon can easily perform intra-articular resection of bone, soft-tissue balancing, and putting the prosthesis in a position consistent with the true with the help of navigation system.
In our study, the data of the function scores, KSS, and Arc of knee flexion confirmed that TKA with the computer-assisted navigation system treating for osteoarthritis with extra-articular deformity resulted in the satisfactory outcome. All patients were satisfactory with the results. The function was improved and the pain was reliefed. The radiography confirmed that ideal mechanical alignment was obtained in each patient postoperatively. In addition, Intra-operatively the mechanical alignment of the lower extremity were figured our and the subsequent steps of the surgery were performed without obstacles with the help of computer-assisted navigation system in all patients. In the literature, any studies showed the advantages of TKA with computer-assisted navigation system, such as resulting in a more ideal mechanical alignment and the outcome[13(1可以引用),14(2可以引用)找]. Moreover, Gregg R. Klein et al[15] reported a study that patients with arthritis of the knee and extra-articular femoral and/or tibial deformity(s), retained hardware, or intramedullary implants underwent TKA using the computer-assisted navigation system, which resulted in the excellent outcome. Another study was reported that TKA with the computer-assisted navigation system were performed on the patients with extra-articular femoral deformity and excellent outcomes were obtained[16].
In conclusion, the computer-assisted navigation system, unlike the traditional instrumentation, can figure out the mechanical alignment of the operative extremity. It is a very efficient and useful tool for accurate recreating mechanical alignment of lower extremities in the face of extra-articular deformity of knees. For these patients, It maybe provides a optimized treatment for improving outcome of TKA.
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