[Influence of preoperative range of motion on the early clinical outcome of total knee arthroplasty].

OBJECTIVE: To retrospectively analyze the influence of preoperative range of motion (ROM) and maximal flexion degree on the early clinical outcome of total knee arthroplasty (TKA).

METHODS: From January 2000 to December 2003, 97 knees of 65 patients that were underwent total knee arthroplasty with Scorpio posterior-stabilized knee prosthesis were reviewed. There were 55 osteoarthritis patients (81 knees), and 10 rheumatoid arthritis (16 knees). Thirty-three patients were underwent unilateral TKA, 32 patients were underwent bilateral TKA. According to the preoperative ROM of knee, these patients were divided into two groups, one <or= 90 degrees (range, 5 degrees - 90 degrees ) and the other > 90 degrees (range, 95 degrees - 140 degrees ). Finally the clinical outcomes of two groups (include ROM, maximal flexion degree, KSS score and function score) were evaluated. Three days later after operation, continuous passive motion (CPM) and active functional exercise of the knee were begun, and the wound healed well in all patients. All these operations were primary total knee arthroplasty.

RESULTS: The patients were followed up for average 2 years 5 months (range, 10 months to 3 years 8 months). The average ROM of knee was improved to 101.6 degrees (range, 40 degrees - 140 degrees ) after operation from 84.2 degrees (range, 5 degrees - 140 degrees ) before operation (P = 0.000); the average maximal flexion degree was decreased from 103.5 degrees (range, 25 degrees - 140 degrees ) before operation to 101.6 degrees (range, 40 degrees - 140 degrees ) after operation (P = 0.439); KSS of knee joint was improved to 78.8 points after operation (range, 50 - 95 points) from 19.5 points (-24 - 62 points) before operation (P = 0.000). There was statistically difference between the clinical outcomes (ROM, maximal flexion degree, KSS score and function score) in the two groups before and after operation. Those knees with good preoperative ROM tend to lose flexion, while those with poor preoperative ROM gain flexion after TKA. No revision and deep infection happened.

CONCLUSIONS: TKA is a complex operation, the clinical outcome of TKA is mainly determined by the good operation skill, abundant clinical experience and the familiarity with the prosthesis of the surgeon. At the same conditions such as same surgeon, same prosthesis and same physical therapy, preoperative range of motion of knee influence on the early clinical outcome of total knee arthroplasty, knees that have good preoperative ROM have better clinical outcomes postoperatively than those with poor preoperative ROM.