2023 ISAKOS Biennial Congress ePoster
When Is a Loose TKA a Good TKA?
Vasili Karas, BS, Chicago, IL UNITED STATES
Edgar A Wakelin, PhD, Raynham, Massachusetts UNITED STATES
Jeffrey Michael Lawrence, MD, Viroqua, Wisconsin UNITED STATES
John M. Keggi, MD, Middlebury, CT UNITED STATES
Amber L. Randall, MD, Flagstaff, AZ UNITED STATES
Jeffrey H. DeClaire, MD, Rochester, MI UNITED STATES
Jan Albert Koenig, MD, Dix Hills, NEW YORK UNITED STATES
Corey E. Ponder, MD, Edmond, OK UNITED STATES
Christopher Plaskos, PhD, Raynham, MA UNITED STATES
Corin, Raynham, Massachusetts, UNITED STATES
FDA Status Cleared
Summary
This study suggests that individual parameters including demographics as well as the preoperative state of the knee should be considered to optimize pain reduction after TKA.
ePosters will be available shortly before Congress
Abstract
Introduction
The impact of patient specific pre-operative factors on optimal balance in TKA is not well understood. This study investigates the impact of pre-operative patient demographics, KOOS pain and mental-health scores, and intra-operative pre-resection joint laxity on optimal post-operative laxity for improved post-operative pain.
Methods
364 patients were enrolled in a prospective cohort investigation receiving tibia-first robot-assisted posterior-cruciate sacrificing TKA with an ultra-congruent tibial insert and digitally controlled joint tensioner. Medial and lateral gaps were measured throughout flexion: 1) after the tibial resection and before the femoral resection 2) during trialing. Tibial resection and insert thickness were used to calculate joint balance and laxity. Pre-op and 1-year KOOS and PROMIS-10 scores were captured. Demographics included 58% female, 67.1±8.6 years and BMI: 31.1±5.0 kg/m2. The population was subdivided by gender, age, BMI, and PROMS scores. Laxity and balance groups were selected to subdivide the population into approximately equal thirds. Mann-Whitney-U tests were used to compare outcomes of subgroups.
Results
Knees that were found to be looser pre-resection demonstrated improved pain scores with moderate (0-2 mm) post-op laxity as compared to tighter (< 0 mm) post-op knees (Delta = 6.3, p = 0.048). Pre-operatively tight knees however did not show this association. Neutrally balanced knees reported improved pain when a neutral balance or tighter medial compartment was achieved (Delta = 6.3, p = 0.031). Elderly (>75 years) patients reported improved pain scores with looser lateral compartments (Delta = 8.3, p = 0.016).
Conclusions
High preoperative joint laxity, as measured intra-operatively after tibial resection and placement of a digital tensioning device predicts improved outcomes with a more loosely placed TKA. Additionally, elderly patients demonstrate a propensity toward improved outcomes with a more lax lateral total knee. This study suggests that individual parameters including demographics as well as the preoperative state of the knee should be considered to optimize pain reduction after TKA.