Objective:
For evaluating the early midterm results of our patients who underwent total knee replacement allowing for hyperflexion and for identifying the factors affecting the range of flexion in particular.
Methods:
A total of 150 knees of 95 patients who underwent total knee replacement using a high-flexion cruciate retaining insert were evaluated. The patients were followed up for a mean of 8.5 (3.5-11) years. The knee joints were assessed pre- and postoperatively and at the final follow-up using the Knee Society Scoring System and their ranges of motion were recorded. The component survival was also investigated.
Results:
The mean preoperative knee score was 49.1±12.0, the mean functional score was 48.9±14.1 and the mean range of flexion was 119.3±18.9 degrees. The same values of the follow-up improved on 92.9±8.2 (p<0.0001), 90.7±10.6 (p<0.0001) and 128.0±11.5 degrees (p<0.0001), respectively. A moderate correlation was detected between the preoperative and postoperative ranges of flexion (r=0.623, p<0.0001). There was an insert revision of one knee (0.6%) because of early infection. No revision was required owing to aseptic loosening. Analysis using the ROC revealed the probability of postoperative hyperflexion of 130° and above in knees that had a preoperative range of flexion of 115° and above.
Conclusion:
The postoperative range of flexion was found to correlate with the preoperative range of flexion. The results of our study showed that a higher range of flexion is not possible with the solitary use of high-flex Cruciate Retaining insert and the preoperative range of flexion is an important factor in attaining hyperflexion even with the use of such inserts.
Keywords: Cruciate retaining, knee replacement, hyper-flex knee