Impact of Joint Laxity and Balance on 2-Year KOOS Outcomes of a Posterior Stabilized Total Knee Arthroplasty.

BACKGROUND

The objective of this study was to determine relationships between intra-operative posterior cruciate ligament (PCL) sacrificing posterior stabilized (PS) total knee arthroplasty (TKA) laxity measurements throughout flexion and patient outcomes at 2-years post-TKA; and to define clinically relevant laxity thresholds to optimize patient outcomes.

METHODS

In a single surgeon study, PCL sacrificing TKA using a robotics assisted platform with a digital joint tensioning device was performed in 115 knees in 115 patients. Final intra-operative joint laxity was recorded, and 2-year Knee Injury and Osteoarthritis Outcome Scores (KOOS) were obtained. A Simulated Annealing optimisation algorithm was used to identify medial and lateral laxity windows which maximized the 2-year KOOS pain score. Wilcox non-parametric tests were used to compare outcomes between groups.

RESULTS

Significant associations were found between intra-operative joint laxity and 2-year KOOS pain outcomes throughout flexion. Clinically relevant laxity windows were defined medially and laterally in mid-flexion and flexion for improved outcomes, whereas only a lateral laxity window could be defined in extension. When all laxity windows were satisfied a 14.5 KOOS point improvement was found (97.2 vs 77.8, p=0.0060) compared to knees which did not satisfy any window. Improvements in Activities of Daily Living (∆8.8, p = 0.0143), Sports (∆22.5, p = 0.0108), and Quality of Life (∆18.7, p = 0.0011) KOOS subscores were also found in knees which satisfied all windows versus 0 - 1 window.

CONCLUSION

Intra-operative joint laxity is associated with post-operative outcomes in a PS knee design, wherein patients balanced within identified laxity targets reported improved outcomes over those that did not. Clinically significant thresholds were defined and were predominately found in mid-flexion and flexion for medial and lateral laxity. When target windows were combined further improved outcomes were identified.

Informations de copyright

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Déclaration de conflit d'intérêts

Amber L. Randall, John M. Keggi, Jan A. Koenig, Jeffrey H. DeClaire, Corey E. Ponder, Jeffrey M. Lawrence, recieved research support from Corin and are paid consultants or on the speakers bureau of Corin. Christopher Plaskos is a paid employee of Corin with Stock/Options. Edgar Wakelin was a paid employee of Corin.