Knee extension and flexion muscle power after anterior cruciate ligament reconstruction with patellar tendon graft or hamstring tendons graft: A cross-sectional comparison 3 years post surgery
Hamstring muscles play a major role in knee-joint stabilization after anterior cruciate ligament (ACL) injury. Weakness of the knee extensors after ACL reconstruction with patellar tendon (PT) graft, and in the knee flexors after reconstruction with hamstring tendons (HT) graft has been observed up to 2 years post surgery, but not later. In these studies, isokinetic muscle torque was used. However, muscle power has been suggested to be a more sensitive and sport-specific measures of strength. The aim was to study quadriceps and hamstring muscle power in patients with ACL injury treated with surgical reconstruction with PT or HT grafts at a mean of 3 years after surgery. Twenty subjects with PT and 16 subjects with HT grafts (mean age at follow up 30 years, range 20-39, 25% women), who were all included in a prospective study and followed the same goal-based rehabilitation protocol for at least 4 months, were assessed with reliable, valid, and responsive tests of quadriceps and hamstring muscle power at 3 years (SD 0.9, range 2-5) after surgery. The mean difference between legs (injured minus uninjured), the hamstring to quadriceps (H:Q, hamstring divided by quadriceps) ratio, and the limb symmetry index (LSI, injured leg divided by uninjured and multiplied by 100) value, were used for comparisons between the groups (analysis of variance). The mean difference between the injured and uninjured legs was greater in the HT than in the PT group for knee flexion power (-21.3 vs. 7.7 W, p = 0.001). Patients with HT graft had lower H:Q ratio in the injured leg than the patients with PT graft (0.63 vs. 0.77, p = 0.012). They also had lower LSI for knee flexion power than those in the PT group (88 vs. 106%, p < 0.001). No differences were found between the groups for knee extension power. The lower hamstring muscle power, and the lower hamstring to quadriceps ratio in the HT graft group than in the PT graft group 3 years (range 2-5) after ACL reconstruction, reflect imbalance of knee muscles after reconstruction with HT graft that may have a negative effect on dynamic knee-joint stabilization.
[Show abstract] [Hide abstract] ABSTRACT: Background: Associations between objective and subjective measures of knee function may facilitate rehabilitation in ACL-patients. Aim: The aim of this study is to investigate if a test-battery of functional and/or muscle outcomes are associated with Knee osteoarthritis outcome score (KOOS) subscales (Sport/Rec and QOL) in ACL-reconstructed patients. Methods: 23 hamstring auto-graft ACL-reconstructed men (mean age: 27.2 standard deviation 7.5 years, BMI: 25.4 standard deviation 3.2 time since surgery: 27 standard deviation 7 months) completed KOOS-questionnaire and an objective test-battery: (i) one-leg maximal jump for distance (OLJD), isometric maximal voluntary contraction (MVC) for (ii) knee extensors and (iii) flexors, and (iv) maximal counter movement jump (CMJ). Sagittal kinematic data were recorded during CMJ using a 6-camera Vicon MX system. Multilevel linear regression analysis was used to determine the strength of associations between KOOS parameters (Sport/Rec and QOL) that a priori were defined as dependent variables and 4 models of independent outcomes from the test-battery. Results: Moderate associations between OLJD and Sport/Rec (r(2) = 0.26, p < 0.01) and QOL (r(2) = 0.26, p < 0.01) were observed (Model 1). Adding knee extensor or flexor MVC to the analysis (Model 2) increased the strength of the associations (up to r(2) = 0.53, p < 0.01, and r(2) = 0.31, p = 0.02 for Sport/Rec and QOL, respectively). Adding both knee extensor and knee flexor MVC to the analysis (Model 3) did not improve the regression model and only minor increases were observed when including kinematic data of CMJ (Model 4). Conclusion: Moderate-to-large proportion (31-53%) of the variation in KOOS was explained by OLJD and MVC which may add to design effective future rehabilitation interventions for ACL-patients.0Comments 0Citations
- "The KOOS survey has been validated  and contains five separate subscales; (i) Pain, (ii) Other Symptoms, (iii) Function in daily living (ADL), (iv) Function in Sport and Recreation (Sport/Rec), and (v) joint related Quality of Life (QOL)  . Sport/Rec and QOL were the only KOOS subscales that were analyzed in the present study, since these two subscales are most dominantly affected by ACL-injury   and also are the subscales most frequently studied in the research setting  . Prior to testing patients performed a standardized warm-up program consisting of two repetitions of 10 toe rises, 10 bilateral squats, 10 unilateral squats (for each leg) and two to three submaximal vertical jumps (Countermovement jumps: CMJ). "
[Show abstract] [Hide abstract] ABSTRACT: Background Despite its apparent functional importance, there is a general lack of data regarding the time-related changes in explosive strength and the corresponding side-to-side asymmetries in individuals recovering from an ACL reconstruction (ACLR). The present study was designed to assess changes in the maximum and explosive strength of the quadriceps and hamstrings muscle in athletes recovering from an ACLR. Methods Twenty male athletes with an ACL injury completed a standard isometric testing protocol pre-ACLR, 4 and 6 months post-ACLR. In addition to the maximum strength (Fmax), the explosive strength of quadriceps and hamstrings was assessed through 4 variables derived from the slope of the force-time curves over various time intervals (RFDmax, RFD50, RFD150 and RFD250). Side-to-side asymmetries were calculated relative to post-ACLR measures of the uninvolved leg (“standard” asymmetries), and relative to pre-ACLR value of the uninvolved leg (“real” asymmetries). Results Pre-ACLR asymmetries in quadriceps RFD (average 26%) were already larger than in Fmax (14%) (p < 0.05). Six months post-ACLR real asymmetries in RFD variables (33-39%) were larger than the corresponding standard asymmetries (26-28%; p < 0.01). Average asymmetries in hamstrings RFD and Fmax were 10%, 25% and 15% for pre-ACLR and two post-ACLR sessions, respectively (all p > 0.05). Conclusions In addition to the maximum strength, the indices of explosive strength should also be included in monitoring recovery of muscle function following an ACLR. Furthermore, pre-injury/reconstruction values should be used for the post-ACLR side-to-side comparisons, providing a more valid criterion regarding the muscle recovery and readiness for a return to sports.0Comments 9Citations
- "The lowest strength values were recorded 4 months post-ACL, whereas at 6 months post-ACLR the maximum strength nearly recovered to the pre-ACLR level. These findings are generally in line with the previous studies [7,32,48]. The loss in quadriceps explosive strength was accompanied by a minor reduction of explosive strength in the hamstrings of the involved leg, as well as in the quadriceps of the uninvolved leg. "
[Show abstract] [Hide abstract] ABSTRACT: The anterior cruciate ligament injury is one of the most common injuries in athletes. A limited range of motion, abnormal gait mechanics, quadriceps and hamstring muscles strength loss, and very often a decreased return to pre-injury levels of activity are concomitant to ligament reconstruction. Tremendous efforts have been made over the past two decades toward an accelerated rehabilitation in order to minimize the functional and mechanical knee instability as well as quadriceps and hamstring muscles strength loss. Various strength test protocols have been employed to determine the magnitude of reduction in muscle strength, and to provide criteria for an athlete's progression through the phases of recovery. However, since it is only the open kinetic chain feature that enables specific quantification of strength deficits in isolated muscles, this manuscript will focus on the methods for strength assessment which utilize unilateral OKC movements. By summarizing the principles and methods for strength assessment (isokinetic, isometric and isoinertial), we aimed at providing a comprehensive understanding of the current state of research that could guide the clinicians in conducting reasoned interventions.0Comments 3Citations
- "There is a lack of literature regarding the use of isoinertial tests for strength assessment in ACLR subjects. Only a few studies have explored isoinertial strength assessment following the ACLR (Ageberg, Roos, Silbernagel, Thomee, & Roos, 2009; Ageberg, Thomee, Neeter, Silbernagel, & Roos, 2008; Neeter, et al., 2006; Thomee, et al., 2012). This group of authors applied the same isoinertial testing battery (seated leg extension and flexion, and leg press) in order to investigate the differences in quadriceps and hamstrings power between the contralateral limbs (seeTable 1 for more details). "