الفهرس 
Discussion.Only 14 pages are availabe for public view
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Abstract
MIS surgery (minimally invasive) is different from the Mini-Incision surgery. The aim of minimally invasive surgery is to decrease the violation on the patients’ tissues, to enhance and fasten the recovery, and lastly, cosmetics if the procedure itself will not be compromised.
TKA is a procedure that changed the quality of life of many people around the world. When uncomplicated, Excellent results are achieved whatever the approach. That is evidenced in the results of most ,if not all, the recent studies. Also, evidenced by the rising number of patients undergoing the operation year after year.
MIS TKA has the same principles. Violation of the extensor mechanism is avoided or at least minimized. This was the problem that has no solution to mange via the standard parapatellar approach that invaded the quadriceps tendon.
Subvastus (Southern) approach was developed to solve this problem through retraction of the whole extensor mechanism laterally without violation to the extensor mechanism. This way , patellar tracking also is not affected. This approach can not act as the main working horse in TKA as found not suitable for many , if not most, of patients. It suits only slim patients without deformities. It is technically demanding as well requiring smaller instruments and retractors in most of cases. Also, neurovascular compromise of the vastus medialis muscle was reported.
A compromise between the Subvastus approach and the standard medial parapatellar approach is the midvastus approach. It has the merits of being less in violation of the extensor mechanism, less need to lateral retinacular release, not dependent on special instrumentation, and possible to perform on larger scale of patients. Still not suitable for revision cases and cases with severe deformities. We conclude that the approach is less invasive rather than minimally invasive.
Other minimally- invasive approach are purely mini-incision (cosmetic) and dependent basically on instruments that allow work from small medial or lateral approach.
Another surgical issue was addressed which is the benefit from avoiding patellar retraction. In our case series, lateral retraction of the patella was done. It was found easily facilitated after removing the osteophytes from the distal femur and the under surface of the patella.
Our aim of the study was to assess the functional results of MIS TKA done through the mid-vastus approach without patellar eversion. Prospective study of 29 primary TKAs were done in the Suez Canal university hospital and Ismailia health insurance complex between May 2008 and June 2010. The mean age of patients was 57 years (50-71). PCL- substituting surface arthroplasty by ( NexGen LPS ) prosthesis was done for all patients. The patient were followed clinically and radiologically for a period of one year.
The functional results of our patients were assessed by the knee society score and the knee function score. Results showed statistically significant increase in all parameters of both scores. The knee society score increased from 47.1 points to 86.72 points (p- value< 0.001) . And the knee function score increased from 37.07 points to 57.24 points postoperatively (p- value< 0.001). Those results were found comparable to the results of the studies done on the same approach with similar methodology. We can claim success of the procedure evidence by this statistically significant results. Also, by the fact that 3 patients undergone second stage TKA of the other knee and included in our series.
The overall risk of complications in our series was 13.8% . That is not a high percentage if we put in mind that one the patient included has superficial wound infection and delayed healing 3.4% . This patient was the first of our series. She was the only patient in our series that was treated for rheumatoid arthritis. That complication was treated and the patient undergone arthroplasty for the other knee 6 months later. Other 2 patients (6.8%) had femoral notching, the first one was early in the series and she was satisfied about the result of the operation. A year later, she had second stage arthroplasty of the other knee. The second one was also satisfied with his knee with excellent knee score. The serious complication we met in our case series was deep infection in one case 3.4%, this patient was revised after using a temporary antibiotic spacer for 6 months. Except for this patient, we found no case with DVT or lucent line in the x-ray. No lateral retinacular release was needed in all the 29 cases.
The overall results did not differ too much from the results of patients by using the standard approach. But , we can support the benefits of the midvastus approach on the short term and recovery basis. The patients shows faster recovery, faster return to SLR within the first week postoperative, and the hospital stay for all patients was short (4days, 1 preoperative, 2 postoperative)
Finally, we recommend the approach for all patients (except with revision cases and severe deformities) only if the surgeon is familiar to the approach. We can recommend the medial parapatellar classic approach for older patients with sedentary life style. In those patients with pain relief more important than function, It will not differ too much if one of the approaches is used. But, if we still use the medial parapatellar approach, we should try to use the smallest incision as much as possible without eversion of the patella. The surgeon preference of the technique stay the most important factor as the long term results of both of approaches are not different.