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.