2023 ISAKOS Biennial Congress ePoster
Preoperative Medial Laxity in Midflexion and Flexion Correlates with Poorer KOOS-12 Function Scores Prior to TKA
Josh Petterwood, MD, Hobart, Tasmania AUSTRALIA
James Sullivan, MD, Sydney, NSW AUSTRALIA
Simon Coffey, MBBS, FRACS(Orth), Beecroft, NSW AUSTRALIA
Stephen McMahon, FRACS, Melbourne, VIC AUSTRALIA
Edgar A Wakelin, PhD, Raynham, Massachusetts UNITED STATES
Christopher Plaskos, PhD, Raynham, MA UNITED STATES
Alexander Orsi, PhD UNITED STATES
Corin Group, Raynham, MA, UNITED STATES
FDA Status Cleared
Summary
Patients with preoperative medial laxity greater than 7 mm had lower preoperative PROMs scores compared to patients with less than 7 mm of medial laxity.
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Abstract
Introduction
Preoperative ligament laxity can be characterized intraoperatively using digital robotic tensioners. Understanding how preoperative knee joint laxity affects preoperative and early post-operative patient reported outcomes (PROMs) may aid surgeons in tailoring intra-operative balance and laxity to optimize outcomes for specific patients.
This study aims to determine if preoperative ligament laxity is associated with PROMs, and if laxity thresholds impact PROMs during early post-operative recovery.
Methods
161 patients were retrospectively reviewed. BMI was 31±7kg/m2. Mean age was 67±8 years. 69% were female.
Medial and lateral knee joint laxity was measured intraoperatively using a digital robotic ligament tensioning device after a preliminary tibial resection.
Linear regressions between laxity and KOOS12-function were performed in extension (10°), midflexion (45°), and flexion (90°) at preoperative, 6-week, and 3-month time points. Patients were separated into two laxity groups: greater than 7 mm laxity and less than 7 mm laxity. Student’s t-tests determined significant differences between laxity groups for KOOS12-function scores at all time points.
Results
Correlations were found between preoperative KOOS12-function and medial laxity in midflexion (p<0.001) and flexion (p<0.001). Patients with less than 7 mm of medial laxity had greater preoperative KOOS12-function scores compared to patients with greater than 7 mm of medial laxity in extension (47.6±17.9 vs. 35.3±17.8, p<0.05), midflexion (49±17.6 vs. 36±17, p<0.001), and flexion (48.2±18 vs. 37.2±16.9, p<0.01). No differences in KOOS12-function scores were observed between medial laxity groups at 6-weeks or 3-months. All knees had <5 mm of medial laxity postoperatively.
No correlations were found between lateral laxity and KOOS12-function.
Conclusion
Patients with preoperative medial laxity greater than 7 mm had lower preoperative PROMs scores compared to patients with less than 7 mm of medial laxity. No differences in PROMs were observed between laxity groups at 6 weeks or 3 months. Patients with excessive preoperative joint laxity achieve similar PROMs scores to those without excessive laxity after undergoing gap balancing TKA.