Progressive Late-Onset Genu Recurvatum Post-Total Knee Arthroplasty: Insights from a Spinal Stenosis-Related Case Series.

Objectives: Knee osteoarthritis is common among older individuals, necessitating Total Knee Arthroplasty (TKA) for end-stage cases. The aging population has increased TKA demand, leading to a rise in revision surgeries. Genu recurvatum, a rare complication, often requires surgical intervention, with late-onset cases linked to neuromuscular conditions. This case series focuses on the infrequent occurrence of late-onset genu recurvatum resulting from spinal stenosis in patients without other predisposing conditions.

Methods: A retrospective case series of 10 patients (11 knees) referred between February 2016 and August 2020 due to late recurvatum instability. Exclusion criteria encompassed neuromuscular diseases other than spinal stenosis, prosthetic joint infection, and pre-existing recurvatum deformity. Data, including demographics, medical history, imaging findings, and surgical details, were collected retrospectively. Patient performance was assessed using the Knee Society Score (KSS) at specified postoperative intervals.

Results: The study cohort, exhibiting hyperextension ranging from 11 to 30 degrees, underwent successful revision surgery using rotating hinge knee (RHK) implants after failed conservative measures. Follow-up assessments at 6, 18, and 24 months showed no recurrence of genu recurvatum.

Conclusion: Late-onset genu recurvatum poses a challenge, necessitating surgical intervention. Identifying predisposing factors is crucial, with spinal stenosis emerging as a rare cause. The use of posterior stabilized (PS) implants in primary surgery aligns with higher revision rates, possibly linked to PCL removal. Limited literature explores the spinal-genu recurvatum relationship. A stepwise screening protocol is proposed for high-risk patients, emphasizing history, physical examination, and imaging. Strategic considerations include lower constraining, a tighter extension gap, and potential use of Hinge implants.