Gap Balancing Sacrifices Joint-Line Maintenance to Improve Gap Symmetry: 5-Year Follow-Up of a Randomized Controlled Trial.

BACKGROUND

Gap balancing (GB) has been noted to sacrifice joint-line maintenance to improve gap symmetry. This study aims to determine whether this change affects function or quality of life in the midterm.

METHODS

A prospective blinded randomized controlled trial was completed with 103 patients randomized to measured resection (n = 52) or GB (n = 51). Primary outcome measured was femoral component rotation. Secondary outcomes measured were joint-line change, gap symmetry, and function and quality-of-life outcomes.

RESULTS

At 5 years, 83 of 103 patients (85%) were assessed. There was no significant difference between groups in terms of functional or quality of life outcomes. A subgroup analysis revealed that there was no significant association between those with asymmetrical flexion and/or extension or medial and/or lateral gaps during knee replacement and subsequent functional outcomes. No significant difference was detected with those with an elevated joint line and postoperative function.

CONCLUSION

In the midterm, the resultant change in joint-line and maintained gap symmetry noted with GB does not result in significant change to function or quality of life.