JOA - 2026-08-12 - Journal Article
Functional Limb Length Preservation and Coronal Alignment Categories in Revision Total Knee Arthroplasty.
Khury F, Ehlers M, Aziz HH, Sarfraz A, Meftah M, Schwarzkopf R
Topics
Key Takeaway
Revision TKA preserved functional limb length in 68.6% (contralateral reference) and 47.1% (pre-rTKA reference) of cases, with coronal alignment preserved in 64.3%; PROM improvements were statistically comparable across all limb-length and alignment categories at one year.
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Summary
This study asked whether functional limb-length and coronal alignment preservation after rTKA correlate with superior PROMs, using pre- and post-rTKA full-length radiographs in 70 patients with KOOS JR, PROMIS Pain Intensity, and Pain Interference as endpoints. Limb-length was preserved (±10 mm) in 68.6% vs. contralateral and 47.1% vs. pre-rTKA baseline; coronal alignment was preserved in 64.3%. PROM improvements did not differ significantly across limb-length or alignment categories (P>0.05), though early MCID achievement favored over-lengthening vs. contralateral and preservation vs. pre-rTKA state, and one-year pain interference MCID was achieved only in the preserved-alignment cohort.
Key Limitation
The heterogeneous revision indications (aseptic loosening, instability, PJI, arthrofibrosis, insert wear) across a small cohort make it impossible to determine whether limb-length or alignment effects are indication-specific.
Original Abstract
BACKGROUND
This study evaluated functional limb-length (LL) and coronal-alignment preservation after revision total knee arthroplasty (rTKA) relative to contralateral and pre-rTKA baselines, examining their association with patient-reported outcome measures (PROMs).
METHODS
We retrospectively reviewed 70 rTKA patients with pre- and post-rTKA full-length radiographs. Functional LL preservation was defined as ± 10 mm of the target. Patient-reported outcomes-including Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) and Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity and Pain Interference-were compared across LL (shortened/preserved/over-lengthened) relative to contralateral/pre-rTKA baselines and coronal alignment (preserved/changed) categories. Indications included aseptic loosening (31.4%), instability (30.0%), arthrofibrosis (14.3%), periprosthetic joint infection (12.9%), and insert wear (11.4%).
RESULTS
The post-rTKA LL was preserved relative to the contralateral LL in 68.6% of the patients and pre-rTKA LL in 47.1%. Coronal alignment was preserved in 64.3%. PROM improvements were comparable across categories (P > 0.05). When referencing the contralateral limb, only the over-lengthened cohort achieved the minimal clinically important difference (MCID) across all PROMs at three months; at one year, all cohorts achieved MCID for KOOS, JR, and pain intensity, but missed the pain interference threshold. When referencing the pre-rTKA state, preserved and over-lengthened cohorts achieved MCID across all PROMs at three months; at one year, all cohorts sustained the MCID across all three outcome domains. The preserved alignment cohort achieved MCID across all PROMs, while the changed alignment cohort missed the threshold for pain interference.
CONCLUSIONS
Revision TKA preserved functional LL and coronal alignment in approximately two-thirds of cases. Although PROMs were comparable among categories, early MCID achievement was associated with over-lengthening relative to the contralateral limb and avoiding shortening relative to the pre-rTKA state. At one year, preserving pre-rTKA coronal alignment provided superior pain interference relief, sustained only when evaluated relative to the pre-rTKA baseline.