Posteromedial varus fatigue fragment (PVFF) in severe varus knee osteoarthritis phenotype: incidence, surgical implications, and management

TL;DR

This study identifies a rare but important bone fragment in severe varus knee osteoarthritis that affects surgical outcomes and requires special attention during knee replacement.

Contribution

The study introduces the Posteromedial Varus Fatigue Fragment (PVFF) as a new, underrecognized lesion in severe varus knee OA.

Findings

PVFF was found in 1.99% of TKA cases, mostly undetected preoperatively.

PVFF cases had severe varus alignment and complete ACL deficiency.

Fragment removal altered gap balancing and implant selection during surgery.

Abstract

Purpose: Severe varus knee osteoarthritis (OA) alters weight-bearing mechanics, leading to progressive stress concentration on the posteromedial tibial plateau. In select cases, this results in the development of a Posteromedial Varus Fatigue Fragment (PVFF), a chronic stress-related fracture that remains ununited and influences knee stability, surgical planning, and implant selection. This study aims to evaluate the incidence, radiographic detectability, and intraoperative significance of PVFF in patients undergoing total knee arthroplasty (TKA). Methods: A retrospective analysis was conducted of 856 consecutive TKA cases performed by a single surgeon. Preoperative radiographs, intraoperative findings, and surgical modifications were assessed to determine the incidence and implications of PVFF. Correlation with varus severity and absence of ACL was done. Results: PVFF was detected intraoperatively in 17 of 856 cases (1.99%), but only 9 (53%) were visible on pre-op imaging.” All PVFF cases exhibited varus alignment exceeding 15° and complete ACL deficiency. Intraoperatively, fragment removal resulted in an increased medial flexion gap, impacting gap balancing and necessitating adjustments in implant selection, including the use of tibial stems or augments in select cases. Conclusion: PVFF is an underrecognized structural lesion for precision in severe varus knee OA, affecting tibial fixation, load distribution, and medial knee stability. Its presence requires careful intraoperative assessment, as fragment removal can alter gap balancing. Improved preoperative recognition and surgical planning are essential to optimize TKA outcomes in patients. Further prospective studies and biomechanical analyses are needed to better understand PVFF’s long-term clinical implications and refine surgical strategies.

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