Improved tibiofemoral contact restoration after transtibial reinsertion of the anterior root of the lateral meniscus compared to in situ repair: a biomechanical study

Abstract

Purpose: To compare biomechanical behaviour of the anterior root of the lateral meniscus (ARLM) after a transtibial repair (TTR) and after an in situ repair (ISR), discussing the reasons for the efficacy of the more advantageous technique.

Methods: Eight cadaveric human knees were tested at flexion angles from 0° to 90° in four conditions of their ARLM: intact, detached, reinserted using TTR, and reinserted using ISR. Specimens were subjected to 1000 N of compression, and the contact area (CA), mean pressure (MP), and peak pressure (PP) on the tibial cartilage were computed. For the TTR, traction force on the sutures was registered.

Results: ARLM detachment significantly altered contact biomechanics, mainly at shallow flexion. After ISR, differences compared to the healthy group persisted (extension, CA 22% smaller (p = 0.012); at 30°, CA 30% smaller (p = 0.012), MP 21%, and PP 32% higher (both p = 0.017); at 60°, CA 28% smaller (p = 0.012), MP 32%, and PP 49% higher (both p = 0.025). With TTR, alterations significantly decreased compared to the injured group, with no statistical differences from the intact ones observed, except for CA at extension (15% decrease, p = 0.012) and at 30° (12% decrease, p = 0.017). The suture tension after TTR, given as mean(SD), was 36.46(11.75)N, 44.32(11.71)N, 40.38(14.93)N, and 43.18(14.89)N for the four tested flexion angles.

Conclusions: Alterations caused by ARLM detachment were partially restored with both ISR and TTR, with TTR showing better results on recovering CA, MP, and PP in the immediate postoperative period. The tensile force was far below the value reported to cause meniscal cut-out in porcine models.

Keywords: Anterior meniscal root avulsion; Biomechanical testing; In situ repair; Transtibial repair.

Fig. 1

Schematics of ARLM repairs: a ISR technique, b TTR technique

Fig. 2

Experimental setup showing the testing machine with a left knee specimen mounted at full extension in the TTR condition. (1) Tibial container; (2) femoral container; (3) load cell; (4) pressure sensor; (5) custom-designed transducer, showing (5a) screw that fixes the transducer to the tibial tunnel, (5b) element to fix the suture threads, and (5c) load cell; (5d) calibrated wheel that displaces the thread fixation element in the direction of the tibial tunnel

Fig. 3

Mean values of the normalised biomechanical parameters for the three altered meniscal conditions at the four knee flexion angles tested, with the vertical line representing the 95% CI interval: a normalised CA, b normalised MP, and c normalised PP at the lateral compartment and d normalised CA, e normalised MP, and f normalised PP at the medial compartment. * represents the significant difference with respect to the intact condition. ◊,represents the significant difference with respect to the injured condition. For the results in the medial compartment, the p value is indicated when detecting a significant difference