Abstract
Primary Total Knee Arthroplasty (TKA) is considered to be one of the most successful orthopedic surgical interventions performed. Long-term results have been generally excellent, with 10–15 year survival rates as high as 90–95% reported, few complications, and reoperations occurring in approximately one percent of patients per year. One of the most important outcome measures of TKA is the range of motion. It has been demonstrated that a 67° of knee flexion is needed for the swing phase of the gait, 83° to climb stairs, 90° to descend stairs, and 93° to rise from chair.
This is a prospective study of 50 patients who underwent Total Knee Arthroplasty at Dayanand Medical College & Hospital, Ludhiana between March 2008 & April 2009. Patients with a primary diagnosis of osteoarthritis, rheumatoid arthritis, or traumatic arthritis in which Natural Knee II implant (Zimmer) was used were included in the study. Absolute exclusion criteria were infection, sepsis, osteomyelitis, revision of a previous total knee replacement or deformities of the hip and spine. Preoperative demographic data, including sex, age at surgery, side affected, body mass index, primary diagnosis, tibio-femoral angle, knee score and functional score, and preoperative passive ROM were obtained. Patients underwent a medial parapatellar approach, with cement used to fix both the femoral and tibial components. Patellar resurfacing was not performed. Following surgery, patients underwent physical therapy at home or in a physiotherapy center, as appropriate. ROM and flexion were calculated at three and six months postoperatively.
54% of the patients were of age 60–75 years and 70% of them were females. 92% patients suffered from osteoarthritis. 80% patients had a BMI of <30 points. 63.46% patients had a preoperative knee flexion of <90°. The average preoperative knee flexion improved from 94.94° to 107.21° at 3 months and 112.12° at 6 months postoperatively (p-value=0.000056). The average preoperative knee flexion in patients with preoperative knee flexion <90°, 90°–110° and >110° changed from 88.33°-106.36°-108.73°, 102.67°-108.33°-114° and 120.50°-110°-117.50° at 3 months and 6 months respectively. The average preoperative knee score was 46.55 and functional score was 50.30, which improved to 95.62 (p-value=0.000015) and 75.60 (p-value=0.000213) respectively.
Postoperative ROM is a function of many factors, with preoperative ROM being one of the most important. The knee ROM tends to regress towards a mean with excellent preoperative ROM loosing and poor preoperative ROM improving. Several factors related to surgical techniques have been found to be important. These include the tightness of the retained posterior cruciate ligament, the elevation of the joint line, increased patellar thickness, and a trapezoidal flexion gap. Vigorous rehabilitation after surgery appears useful, while continuous passive motion has not been found to be effective. Obesity and previous surgery are poor prognostic factors. In general, the clinical results of TKA were satisfactory in terms of pain relief and overall function. It was found that measurement of preoperative flexion gives the surgeon a good parameter for predicting flexion after arthroplasty.
