Partial medial meniscectomy leads to altered walking mechanics two years after anterior cruciate ligament reconstruction: Meniscal repair does not

Abstract

Background: Partial meniscectomy dramatically increases the risk for post-traumatic, tibiofemoral osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Concomitant medial meniscus surgery influences walking biomechanics (e.g., medial tibiofemoral joint loading) early after ACLR; whether medial meniscus surgery continues to influence walking biomechanics two years after ACLR is unknown.

Research question: Does medial meniscus treatment at the time of ACLR influence walking biomechanics two years after surgery?

Methods: This is a secondary analysis of prospectively collected data from a clinical trial (NCT01773317). Fifty-six athletes (age 24 ± 8 years) with operative reports, two-year biomechanical analyses, and no second injury prior to two-year testing participated after primary ACLR. Participants were classified by concomitant medial meniscal status: no medial meniscus involvement (n = 36), partial medial meniscectomy (n = 9), and medial meniscus repair (n = 11). Participants underwent biomechanical analyses during over-ground walking including surface electromyography; a validated musculoskeletal model estimated medial compartment tibiofemoral contact forces. Gait variables were analyzed using 3 × 2 ANOVAs with group (medial meniscus treatment) and limb (involved versus uninvolved) comparisons.

Results: There was a main effect of group (p = .039) for peak knee flexion angle (PKFA). Participants after partial medial meniscectomy walked with clinically meaningfully smaller PKFAs in both the involved and uninvolved limbs compared to the no medial meniscus involvement group (group mean difference [95%CI]; involved: -4.9°[-8.7°, -1.0°], p = .015; uninvolved: -3.9°[-7.6°, -0.3°], p = .035) and medial meniscus repair group (involved: -5.2°[-9.9°, -0.6°], p = .029; uninvolved: -4.7°[-9.0°, -0.3°], p = .038). The partial medial meniscectomy group walked with higher involved versus uninvolved limb medial tibiofemoral contact forces (0.45 body weights, 95% CI: -0.01, 0.91 BW, p = 0.053) and truncated sagittal plane knee excursions, which were not present in the other two groups.

Significance: Aberrant gait biomechanics may concentrate high forces in the antero-medial tibiofemoral cartilage among patients two years after ACLR plus partial medial meniscectomy, perhaps explaining the higher osteoarthritis rates and offering an opportunity for targeted interventions.

Level of evidence: Level III.

Keywords: Anterior cruciate ligament reconstruction; Gait biomechanics; Meniscus; Partial meniscectomy; Rehabilitation.

Figure 1.

There was a main effect of group (p=.039), with the partial medial meniscectomy group walking with smaller PKFAs. (See Table 2a-b for post-hoc comparisons.)

Figure 2.

There was a main effect of limb (p=0.001) for knee flexion excursion during weight acceptance, however this relationship was moderated by QI and no interlimb difference in any group exceeded the minimal clinically important difference (MCID) value of 3°[29].

Figure 3.

There was a main effect of limb (p<0.001) for knee extension excursion during mid-stance, however this relationship was moderated by QI and only the interlimb difference (4.2° less excursion in the involved limb) in the partial medial meniscectomy group was clinically meaningful[29].

Figure 4.

There tended to be an interaction effect (p=.084) characterized by meaningfully[6] higher involved limb peak medial compartment contact forces in the partial meniscectomy patients but not in the other groups. (Note: there were 7 subjects for which data could not be modeled.)