What might influence knee function after ACL reconstruction.

Preoperative quadriceps strength is a significant predictor of knee function two years after anterior cruciate ligament reconstruction.

Eitzen I, Holm I, Risberg M. British Journal of Sports Medicine, 2009; 43, 371 – 376.

http://bjsm.bmj.com/content/43/5/371.abstract

ACL rupture is one of the most common athletic injuries and is associated with knee static and dynamic stability deterioration. Although, reconstructive surgery seems to restore static knee stability, dynamic knee function maintains to be decreased for a long period of time following ACL reconstruction. There is an agreement in the literature, that, to improve knee function after ACL surgical treatment, predictive factors need to be determined. Subsequently, based on the findings, optimization of rehabilitation programmes should be implemented.  Sixty patients with BPTB autograft reconstruction were prospectively evaluated with follow – up period of two years. Knee function was assessed with Cincinnati Knee Score.

Results showed that quadriceps muscle strength, meniscus injury and the Short-Form-36 Bodily Pain sub score were identified as significant predictors for knee function assessed from the Cincinnati Knee Score two years after ACL reconstruction. Patients with quadriceps strength deficits larger than 20% had a significantly lower Cincinnati Knee Score 2 year post – surgery. Moreover, quadriceps strength was significantly lower 2 years after reconstruction among those having strength deficits >20% at baseline. Finally, participants with concomitant meniscus lesion at baseline had significantly lower knee scores at 2 years follow – up.

Author’s findings indicated that preoperative quadriceps muscle strength deficits and meniscus

injuries have significant negative consequences for the long term functional outcome after ACL reconstruction. Negative influence of meniscus injury on knee function was most likely due to associated symptoms, such as pain and ROM deficits, which could potentially affect compliance to rehabilitation protocol. Insufficient quadriceps function has been reported to effect from atrophy and activation failure due to permanent shift in muscle activation. As research has previously observed, this neuromuscular deficit seems to be further increased by ACL reconstruction, as quadriceps muscle strength has been reported to be at its lowest level around six months after surgery. Hence, it is crucial to implement appropriate rehabilitation protocols designed to restore quadriceps strength symmetry prior to surgical procedure. This study suggests that it would, most likely, improve knee function post – surgery. From the results obtained, authors recommend that quadriceps strength deficits should be less than 20% in order to prevent long – term consequences.

Apart from the limitations provided by the authors, one of them seems to not be included in the discussion part. BPTB graft could have biased the results, potentially affecting quadriceps muscle strength and influencing knee function, as greater incidence of anterior knee pain has been reported in patients with that type of graft compared to those with ST – GR graft.
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