Research Article: Peak torque angle of anterior cruciate ligament-reconstructed knee flexor muscles in patients with semitendinosus and gracilis autograft is shifted towards extension regardless of the postoperative duration of supervised physiotherapy

Date Published: February 5, 2019

Publisher: Public Library of Science

Author(s): Aleksandra Królikowska, Paweł Reichert, Andrzej Czamara, Katarzyna Krzemińska, Andrea Macaluso.

http://doi.org/10.1371/journal.pone.0211825

Abstract

The observational cohort study investigated whether the flexor muscles peak torque (PT) angle shifting towards extension observed in the involved knee in patients after anterior cruciate ligament reconstruction (ACLR) using semitendinosus and gracilis tendon (STGR) autograft is associated with the postoperative physiotherapy supervision duration.

From 230 ACL-reconstructed males, we identified patients after ACLR utilizing STGR autograft and divided them into those who completed supervised physiotherapy <6 months (Group I; n = 77) and those who completed supervised physiotherapy ≥6 months (Group II; n = 66). The mean follow-up time was 6.84 ± 1.47 months. The ACL-reconstructed patients were compared to 98 controls (Group III). Bilateral knee flexor muscle PT measurements were performed. The relative PT at 180°/s (RPT), PT angle at 180°/s, and range of motion at 180°/s were analysed. The RPT limb symmetry index (LSI) was calculated. Tests for dependent samples, one-way analysis of variance, post hoc test, and linear Pearson’s correlation coefficient (r) calculations were performed. The shift towards extension was noted when comparing the ACL-reconstructed limb to the uninvolved limb (Group I, p ≤ 0.001; Group II, p ≤ 0.001) and to Group III (p ≤ 0.001), but it was not correlated with physiotherapy supervision duration (r = -0.037, p = 0.662). In ACL-reconstructed patients, there was a moderate association of supervision duration and knee flexor LSI (r = 0.587, p < 0.001). The ACL-reconstructed knee flexors PT angle shift towards extension was observed regardless of the duration of postoperative physiotherapy supervision. However, the analysis revealed that the duration of supervised physiotherapy positively influenced the RPT and LSI in patients after the ACLR.

Partial Text

The graft choice options for anterior cruciate ligament (ACL) consist of autogenous, allogenous, and synthetic grafts [1].The ipsilateral bone-patellar tendon-bone or the hamstring tendons are the most common autografts [1]. The hamstring tendons autografts include the quadruple strand semitendinosus (ST) or double strand semitendinosus-gracilis (STGR). However, there have been concerns regarding ACL-reconstructed knee flexor muscles weakness, especially when both ST and GR tendons are harvested [2]. In general, studies assessing the strength of the knee flexor muscles in patients after ACLR using hamstring tendon autografts can be divided into those assessing peak torque (PT) under isokinetic conditions [3–10], the maximal isometric torque under static conditions [6, 10], and studies evaluating maximum standing knee flexion angle [3, 5, 10]. In regards to isokinetic testing, the PT, defined as the single highest torque output produced by a muscle contraction as the limb moves through the range of motion [11], has tended to be the most commonly utilized strength variable in studies evaluating knee flexor strength in patients after ACLR. Nevertheless, the assessment of this parameter may be insufficient, as there are also authors who have observed that the ACL-reconstructed knee flexor PT angle, also called the angle of occurrence referring to the angle at which PT occurs in the ROM, is shifted towards extension in patients after ACLR using a hamstring graft [12]. According to the literature, the knee flexor muscles weakness observed in deeper angles of knee flexion angles may influence performance in sports, in which knee flexion strength is required at deep flexion angles, such as in gymnastics, judo or wrestling [3, 5, 13]. Although no studies have examined the effect of post-harvesting hamstring weakness in the population of athletes practising these particular disciplines, the issue may seem important in making decisions about the type of graft to use.

The main finding of the study was the observation of a shift towards extension of the knee flexor muscle PT angle at 180°/s in males at seven months after ACLR utilizing STGR autograft in the involved limb regardless of the duration of postoperative supervised physiotherapy. The shift towards extension was observed in comparing the ACL-reconstructed limb to the uninvolved limb and in comparing to healthy individuals. The RPT of knee flexor muscles in the involved limb was significantly higher in the group of patients with postoperative physiotherapy supervision duration ≥ 6 months than in patients with supervision duration < 6 months. For the entire sample of ACL-reconstructed patients, there was a significant but small correlation indicating that higher RPT of knee flexor muscles in the involved limb is associated with longer duration of postoperative physiotherapy supervision. Additionally, our analysis revealed that there was a significant moderate association between duration of postoperative physiotherapy supervision and knee flexor muscle LSI. Longer duration of physiotherapy was associated with higher LSI. In patients after ACLR with the use of ipsilateral STGR autograft exercises performed under the direct supervision of a physiotherapist are more effective than exercises performed independently by patients who gave up supervised physiotherapy, and continued the therapeutic procedure in the form of gym-based exercises in terms of the quantitative parameter, which is the PT, nevertheless they do not affect the qualitative parameter which is the angle at which the PT occurs. What’s more, the standard exercises introduced by physiotherapists in patients after ACLR with the use of STGR are insufficient to restore the involved knee flexor muscles PT angle on the level of uninvolved limb and healthy individuals. The knee flexor muscle PT angle shift towards extension at 180°/s in males at seven months after ACLR utilizing STGR ipsilateral autograft was observed in the involved limb regardless of the duration of supervised postoperative physiotherapy. The shift towards extension was observed in comparing the ACL-reconstructed limb to the uninvolved limb and in comparing to the healthy individuals. The knee flexor muscles RPT in the involved limb was significantly higher in the group of patients with postoperative physiotherapy supervision duration ≥ 6 months, than in patients with supervision duration < 6 months. For the entire sample of ACL-reconstructed patients, there was a significant but small positive correlation between the ACL-reconstructed knee flexor muscle RPT and longer duration of supervised postoperative physiotherapy. Additionally, there was a significant moderate association between duration of supervised postoperative physiotherapy and knee flexor muscle LSI. The longer the duration of physiotherapy supervision, the higher the LSI. The present study may justify the superiority of fully supervised postoperative physiotherapy after ACLR over unsupervised therapy in terms of RPT LSI restoration.   Source: http://doi.org/10.1371/journal.pone.0211825

 

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