Lower Extremity Muscle Strength After Anterior Cruciate Ligament Injury and Reconstruction

Abstract

Arbor. Dr Thomas is now with the Department of Kinesiology, University of Toledo, OH.Context: Quadriceps and hamstrings weakness occurs frequently after anterior cruciate ligament (ACL) injury and reconstruction. Evidence suggests that knee injury may precipitate hip and ankle muscle weakness, but few data support this contention after ACL injury and reconstruction.Objective: To determine if hip, knee, and ankle muscle weakness present after ACL injury and after rehabilitation for ACL reconstruction.Design: Case-control study. Setting: University research laboratory.Patients or Other Participants: Fifteen individuals with ACL injury (8 males, 7 females; age ¼ 20.27 6 5.38 years, height ¼ 1.75 6 0.10 m, mass ¼ 74.39 6 13.26 kg) and 15 control individuals (7 men, 8 women; age ¼ 24.73 6 3.37 years, height ¼ 1.75 6 0.09 m, mass ¼ 73.25 6 13.48 kg).Intervention(s): Bilateral concentric strength was assessed at 608/s on an isokinetic dynamometer. The participants with ACL injury were tested preoperatively and 6 months postoperatively. Control participants were tested on 1 occasion.Main Outcome Measures: Hip-flexor, -extensor, -abductor, and -adductor; knee-extensor and -flexor; and ankle-plantarflexor and -dorsiflexor strength (Nm/kg).Results: The ACL-injured participants demonstrated greater hip-extensor (percentage difference ¼ 19.7, F 1,14 ¼ 7.28, P ¼ .02) and -adductor (percentage difference ¼ 16.3, F 1,14 ¼ 6.15, P ¼ .03) weakness preoperatively than postoperatively, regardless of limb, and greater postoperative hip-adductor strength (percentage difference ¼ 29.0, F 1,28 ¼ 10.66, P ¼ .003) than control participants. Knee-extensor and -flexor strength were lower in the injured than in the uninjured limb preoperatively and postoperatively (extensor percentage difference ¼ 34.6 preoperatively and 32.6 postoperatively, t 14 range ¼À4.59 to À4.23, P .001; flexor percentage difference ¼ 30.6 preoperatively and 10.6 postoperatively, t 14 range ¼ À6.05 to À3.24, P , .05) with greater knee-flexor (percentage difference ¼ 25.3, t 14 ¼À4.65, P , .001) weakness preoperatively in the injured limb of ACLinjured participants. The ACL-injured participants had less injured limb knee-extensor (percentage difference ¼ 32.0, t 28 ¼ À2.84, P ¼ .008) and -flexor (percentage difference ¼ 24.0, t 28 ¼ À2.44, P ¼ .02) strength preoperatively but not postoperatively (extensor: t 28 ¼ À1.79, P ¼ .08; flexor: t 28 ¼ 0.57, P ¼ .58) than control participants. Ankle-plantar-flexor weakness was greater preoperatively than postoperatively in the ACL-injured limb (percentage difference ¼ 31.9, t 14 ¼ À3.20, P ¼ .006).Conclusions: The ACL-injured participants presented with hip-extensor, -adductor, and ankle-plantar-flexor weakness that appeared to be countered during postoperative rehabilitation. Our results confirmed previous findings suggesting greater knee-extensor and -flexor weakness postoperatively in the injured limb than the uninjured limb. The knee extensors and flexors are important dynamic stabilizers; weakness in these muscles could i...

Return to play following ACL reconstruction: a systematic review about strength deficits

“…The present systematic review revealed that some recent studies reported deficits in hip strength after ACL reconstruction [18,26,36,43,62,74]. These findings may also have relevance regarding the re-rupture rate.…”

“…These articles are summarized in Table 1. Four articles with a follow-up between 6 and 24 months show postoperative reduction of hip extension strength [18,26,36,74]. One study showed that the ratio of hip and knee extensors was significantly greater after ACL reconstruction 1 3 with a significant negative correlation between the hip extensor:knee extensor torque ratios and maximal anterior tibia shear [62].…”

“…One study also found that plantar-flexor weakness was greater preoperatively than postoperatively in the ACLinjured limb (31.9 %) [74].…”

“…Weak hip abductors and external rotators may cause an internal rotation of the femur which may lead to a dynamic valgus of the knee. All the studies identified for this systematic review used isokinetic tests for the evaluation of hip muscle strength [18,26,36,43,62,74]. However, to analyze the dynamic valgus position, functional tests have to be enforced.…”

Quadriceps Strength and Endurance After Posterior Cruciate Ligament Tears Versus Matched Group With Anterior Cruciate Ligament Tears

“…[3][4][5] These situations are thought to be due to a compensating mechanism to prevent anterior subluxation of the tibia, [6][7][8] which can be painful and potentially detrimental to injured knees with ACL tears. 9,10 Theoretically, the reverse situation (increased quadriceps and decreased hamstring muscle strength) could be expected in patients with posterior cruciate ligament (PCL) tears to lessen the posterior subluxation of the tibia. It remains unclear, however, whether the strength of the quadriceps and hamstring increases or decreases after tears of the PCL.…”