Major Shortening of the Patellar Tendon During Septic Two-Stage Knee Arthroplasty Revision Using Static Spacers

Stephanie Kirschbaum; Claude Weynandt; Michael Fuchs; Carsten Perka; Clemens Gwinner

doi:10.1016/j.arth.2022.03.082

Major Shortening of the Patellar Tendon During Septic Two-Stage Knee Arthroplasty Revision Using Static Spacers

J Arthroplasty. 2022 Sep;37(9):1851-1857. doi: 10.1016/j.arth.2022.03.082. Epub 2022 Apr 4.

Authors

Stephanie Kirschbaum¹, Claude Weynandt², Michael Fuchs³, Carsten Perka¹, Clemens Gwinner¹

Affiliations

¹ Charité-University Hospital Berlin, Center for Musculoskeletal Surgery, Berlin, Germany.
² Hospital of Augustinerinnen, Academic Teaching Hospital University Cologne, Köln, Germany.
³ RKU University Department of Orthopaedics, University of Ulm, Ulm, Germany.

PMID: 35381317
DOI: 10.1016/j.arth.2022.03.082

Abstract

Background: Two-stage septic revision knee arthroplasty (TKA) often results in inferior functional outcome after reimplantation, which might be due to impairments of the extensor mechanism. The aim of the current study was to elucidate possible alterations in extensor mechanisms during septic two-stage revision of TKA treated with a static spacer.

Methods: This retrospective study included 87 patients (42 women, 45 men, age 64.5 ± 10.5; range, 29-85 years) undergoing septic two-stage TKA revision using a static spacer. The modified Insall Salvati ratio (mISR) was calculated via calibrated true lateral radiographs by two independent orthopedic surgeons before TKA explantation (G0), 6-8 days after TKA removal (G1), one day before TKA reimplantation (G2) and 6-8 days after TKA reimplantation (G3). Age, sex, body mass index (BMI), index C-reactive protein level, and number of previous surgeries were evaluated to identify the possible correlations.

Results: Overall, mISR significantly decreased within the first 6 days after index surgery from 1.71 ± 0.41 to 1.63 ± 0.41 (G0 versus G1, P < .001) and showed a further decline within the next 6 weeks to 1.54 ± 0.39 (G1 versus G2, P = .002). Conversely, mISR increased after reimplantation of TKA to 1.6 ± 0.43 (G3 versus G2, P = .08), though it did not regain preoperative baseline levels (G0 versus G3, P < .001). The subgroup with mISR decrease ≥10% experienced patellar tendon shortening of 16% between G0 and G1, 19% between G0 and G2 and up to 20% between G0 and G3. There were weak correlations concerning age (r = -0.240, P = .038), preoperative C-reactive protein level (r = 0.239, P = .04) and patellar tendon shortening. Intraclass correlation coefficient (ICC)was 0.88 concerning radiographic measurement.

Conclusion: Septic two-stage TKA revision using static spacers leads to irreversible alterations of the extensor mechanism, specifically a major shortening of the patellar tendon, in one out of 3 patients.

Level of evidence: II.

Keywords: patella infera; patellar tendon shortening; periprosthetic joint infection; septic revision; static spacer; two-stage revision.

MeSH terms

Aged
Arthroplasty, Replacement, Knee* / methods
C-Reactive Protein
Female
Humans
Knee Joint / surgery
Knee Prosthesis*
Male
Middle Aged
Patellar Ligament* / surgery
Range of Motion, Articular
Reoperation / methods
Retrospective Studies

Substances

C-Reactive Protein