Franceska Zampeli

Asymmetries in Functional Hop Tests, Lower Extremity Kinematics, and Isokinetic Strength Persist 6 to 9 Months Following Anterior Cruciate Ligament Reconstruction

STUDY DESIGN Within-subject and between-subject cross-sectional study. OBJECTIVES To investigate symmetry in hop-test performance, strength, and lower extremity kinematics 6 to 9 months following anterior cruciate ligament reconstruction (ACLR). BACKGROUND Despite the extensive body of literature involving persons following ACLR, no study has comprehensively evaluated measures of strength, lower extremity kinematics, and functional performance of functional hop tests in this population. METHODS The subjects were 22 men (mean ± SD age, 28.8 ± 11.2 years) who had ACLR using a bone-patellar tendon-bone autograft 6 to 9 (7.01 ± 0.93) months previously and 22 healthy male controls (age, 24.8 ± 9.1 years). Participants completed a self-report questionnaire and underwent isokinetic strength testing and functional and kinematic assessment of the single-, triple-, and crossover-hop tests. Two-way analyses of variance were used to test for differences between the ACLR group and the control group, and between the 2 lower extremities of the ACLR group. RESULTS Compared to the control group, the ACLR group had greater isokinetic knee extension torque deficits at all speeds (P ≤.001) and greater performance asymmetry for all 3 hop tests (P<.001). Compared to the noninvolved lower extremity, the involved lower extremity of the ACLR group exhibited less ankle dorsiflexion and knee flexion in the phases of propulsion (P ≤.014) and landing (P ≤.032). When compared to the control group, the involved lower extremity exhibited less ankle dorsiflexion in the propulsion phase (P<.001) but higher hip flexion in the landing phase (P = .014). CONCLUSION Six to 9 months following ACLR, patients continue to demonstrate functional hop and isokinetic knee extension deficits, as well as kinematic differences, during the propulsion and landing phases of the hop tests.

Lessons learned from the last 20 years of ACL-related in vivo-biomechanics research of the knee joint

PurposeTechnological advances in recent years have allowed the easy and accurate assessment of knee motion during athletic activities. Subsequently, thousands of studies have been published that greatly improved our understanding of the aetiology, surgical reconstruction techniques and prevention of anterior cruciate ligament (ACL) injuries. The purpose of this review is to summarize the evidence from biomechanical studies on ACL-related research.MethodsHigh-impact articles that enhanced understanding of ACL injury aetiology, rehabilitation, prevention and adaptations after reconstruction were selected.ResultsThe importance of restoring internal tibial rotation after ACL reconstruction has emerged in several studies. Criteria-based, individualized rehabilitation protocols have replaced the traditional time-based protocols. Excessive knee valgus, poor trunk control, excessive quadriceps forces and leg asymmetries have been identified as potential high risk biomechanical factors for ACL tear. Injury prevention programmes have emerged as low cost and effective means of preventing ACL injuries, particularly in female athletes.ConclusionAs a result of biomechanical research, clinicians have a better understanding of ACL injury aetiology, prevention and rehabilitation. Athletes exhibiting neuromuscular deficits predisposing them to ACL injury can be identified and enrolled into prevention programmes. Clinicians should assess ACL-reconstructed patients for excessive internal tibial rotation that may lead to poor outcomes.Level of evidenceIII.

Effects of knee bracing on tibial rotation during high loading activities in anterior cruciate ligament-reconstructed knees.

PURPOSE To test whether knee bracing restores normal rotational knee kinematics in anterior cruciate ligament (ACL)-reconstructed knees during high-demand, athletic activities. METHODS Twenty male patients who had undergone unilateral ACL reconstruction with a bone-patellar tendon-bone autograft were assessed in vivo. The mean time from surgery to data collection was 26 months (range, 25 to 28 months). An 8-camera optoelectronic system was used to collect kinematic data while each patient performed 2 demanding tasks: (1) immediate pivoting after descending from a stair and (2) immediate pivoting after landing from a platform. Each task was performed under 3 conditions for the reconstructed knee: (1) wearing a prophylactic brace (braced condition), (2) wearing a patellofemoral brace (sleeved condition), and (3) without a brace (non-braced condition). As a control group, patients with intact ACLs were tested without any bracing. This study protocol was identical to the protocol of a previous study that investigated the effect of bracing on ACL-deficient athletes. RESULTS For both tasks, the range of motion of tibial rotation was significantly lower in the intact knee compared with all 3 conditions of the ACL-reconstructed knee (P ≤ .014). Placing a brace or a sleeve on the ACL-reconstructed knee resulted in lower rotation than the non-braced condition (P ≤ .022), whereas no significant differences were found between the sleeved and the braced conditions (P ≥ .110). CONCLUSIONS Bracing limited the excessive tibial rotation in ACL-reconstructed knees during pivoting that occurs under high-demand activities. However, full restoration to normative values was not achieved. Thereby, braces have the potential to decrease rotational knee instability that still remains after ACL reconstruction.

Stride-to-stride variability is altered during backward walking in anterior cruciate ligament deficient patients

BACKGROUND Recently backward walking is used by physical therapists to strengthen the hamstring muscles and thus improve the function of the knee joint of anterior cruciate ligament deficient patients. The aim of this study was to examine the stride-to-stride variability of anterior cruciate ligament deficient patients during backward walking. The variation of how a motor behavior emerges in time is best captured by tools derived from nonlinear dynamics, for which the temporal sequence in a series of values is the facet of interest. METHODS Fifteen patients with unilateral anterior cruciate ligament deficiency and eleven healthy controls walked backwards at their self-selected speed on a treadmill while three-dimensional knee kinematics were collected (100 Hz). A nonlinear measure, the largest Lyapunov Exponent was calculated from the resulted knee joint flexion-extension data of both groups to assess the stride-to-stride variability. FINDINGS Both knees of the deficient patients exhibited significantly lower Lyapunov Exponent values as compared to the healthy control group revealing more rigid movement pattern. The intact knee of the deficient patients showed significantly lower Lyapunov Exponent values as compared to the deficient knee. INTERPRETATION Anterior cruciate ligament (ACL) deficiency leads to loss of optimal variability regardless of the walking direction (forwards in previous studies or backwards here) as compared to healthy individuals. This could imply diminished functional responsiveness to the environmental demands for both knees of ACL deficient patients which could result in the knees being more susceptible to injury.

Electromechanical Delay of the Knee Flexor Muscles After Harvesting the Hamstrings for Anterior Cruciate Ligament Reconstruction

OBJECTIVE To investigate if harvesting of semitendinosus (ST) and gracilis for anterior cruciate ligament (ACL) reconstruction will have an effect in coordinative firing pattern of the hamstrings under fatigue. We hypothesized that fatigue will increase the electromechanical delay (EMD) of the hamstrings on the harvested site and impair the synchronization between the medial and lateral hamstrings, in terms of muscle activity onsets. DESIGN Prospective nonrandomized study. SETTING Institutional. PATIENTS Twelve ACL reconstructed patients with hamstrings, 2 years postoperatively. INTERVENTIONS The patients performed a fatigue protocol with 25 continuous maximal isometric voluntary contractions of 8-second duration with 2-second intervals. MAIN OUTCOME MEASURES The electromyography activity of biceps femoris (BF) and ST was recorded bilaterally and simultaneously with the torque measurements. The dependent variable examined was the EMD difference between BF and ST (muscle activation pattern). RESULTS The fatigue protocol caused significant differences for the EMD values for both the intact and the reconstructed leg, demonstrating the influence of fatigue in EMD. However, the synchronization pattern between the medial and lateral hamstrings did not change significantly throughout the fatiguing protocol, revealing a balanced effect of fatigue. CONCLUSIONS Although the EMD of ST and BF was significantly increased due to fatigue, as expected, their synchronization pattern as identified by the difference in their EMDs remained the same. Thus, the reconstructed knee responded in a balanced manner and the hamstrings firing pattern remained the same, despite the intervention to the ST tendon.Objective:To investigate if harvesting of semitendinosus (ST) and gracilis for anterior cruciate ligament (ACL) reconstruction will have an effect in coordinative firing pattern of the hamstrings under fatigue. We hypothesized that fatigue will increase the electromechanical delay (EMD) of the hamstrings on the harvested site and impair the synchronization between the medial and lateral hamstrings, in terms of muscle activity onsets. Design:Prospective nonrandomized study. Setting:Institutional. Patients:Twelve ACL reconstructed patients with hamstrings, 2 years postoperatively. Interventions:The patients performed a fatigue protocol with 25 continuous maximal isometric voluntary contractions of 8-second duration with 2-second intervals. Main Outcome Measures:The electromyography activity of biceps femoris (BF) and ST was recorded bilaterally and simultaneously with the torque measurements. The dependent variable examined was the EMD difference between BF and ST (muscle activation pattern). Results:The fatigue protocol caused significant differences for the EMD values for both the intact and the reconstructed leg, demonstrating the influence of fatigue in EMD. However, the synchronization pattern between the medial and lateral hamstrings did not change significantly throughout the fatiguing protocol, revealing a balanced effect of fatigue. Conclusions:Although the EMD of ST and BF was significantly increased due to fatigue, as expected, their synchronization pattern as identified by the difference in their EMDs remained the same. Thus, the reconstructed knee responded in a balanced manner and the hamstrings firing pattern remained the same, despite the intervention to the ST tendon.

The PCL Index Is Correlated With the Control of Rotational Kinematics That Is Achieved After Anatomic Anterior Cruciate Ligament Reconstruction

Background: The posterior cruciate ligament (PCL) index quantifies the curvature of the PCL seen on magnetic resonance imaging (MRI) that is caused by a change in tibiofemoral alignment in the anterior cruciate ligament (ACL)–deficient knee. It has been proposed that the PCL index may be useful in assessing the success of ACL reconstruction (ACLR). Hypothesis/Purpose: The purpose of this study was to test if the PCL index is predictive of in vivo rotational kinematics and joint laxity measures in knees of patients after single-bundle ACLR. The hypothesis was that the PCL index is predictive of rotational knee kinematics and objective laxity scores. Study Design: Controlled laboratory study. Methods: At a mean of 18.1 months postoperatively, the PCL index was defined on MRI in 16 patients prospectively followed up after anatomic single-bundle ACLR and in 16 matched controls. The patients were evaluated with 3-dimensional motion analysis during (1) descending and pivoting as well as (2) landing and pivoting tasks. The side-to-side difference in tibial rotation range of motion between the reconstructed knee and the contralateral intact knee was calculated. The side-to-side difference in anterior tibial translation was measured with a KT-1000 arthrometer. Linear regression models were used with the PCL index as a predictor of the side-to-side difference in tibial rotation for each task and the side-to-side difference in anterior tibial translation. Results: The PCL index of the reconstructed knees was significantly lower compared with that of the control knees (P < .001). The index was predictive of the side-to-side difference in tibial rotation during both tasks (R2 = 0.472 and 0.477, P = .003), with a lower index being indicative of increased rotational laxity. It was not predictive of anterior tibial translation (at 134 N: R2 = 0.13, P = .17; at maximum force: R2 = 0.009, P = .726). Conclusion: The PCL index after anatomic single-bundle ACLR using a bone–patellar tendon–bone graft is predictive of rotational kinematics during in vivo dynamic pivoting activities. The results show that the PCL index is correlated with the postoperative ability to control rotational kinematics of the knee joint. Clinical Relevance: This study provides evidence regarding the interplay between restoration of the native ACL’s anatomy and the PCL’s appearance and suggests that the effective restoration of tibiofemoral alignment after ACLR that is reflected in the PCL index translates into better functional outcomes as measured by tibial rotation during pivoting activities.

The effect of knee braces on tibial rotation in anterior cruciate ligament-deficient knees during high-demand athletic activities.

Objective:To examine if bracing can restrict tibial rotation in anterior cruciate ligament (ACL)-deficient patients during high loading activities. Design:Repeated measures. Kinematic data were collected with an 8-camera Vicon system while each patient performed 2 tasks that are known to cause increased rotational and translational loads on the knee: (1) descending from a stair and subsequent pivoting, and (2) landing from a platform and subsequent pivoting. The tasks were repeated under 3 brace conditions for the ACL-deficient knee: (1) wearing a prophylactic brace (braced condition), (2) wearing a patellofemoral brace (sleeved condition), and (3) without brace (unbraced condition). Setting:Biomechanical laboratory study. Patients:Twenty-one male subjects with a confirmed unilateral ACL rupture were assessed in vivo. Main Outcome Measures:Tibial internal rotation. Two repeated measures ANOVAs tested for differences in tibial internal rotation among the 3 conditions of the ACL-deficient knee and the unbraced condition of the intact knee. Results:In both tasks, tibial rotation was significantly lower in the intact knee compared with all 3 conditions of the ACL-deficient knee (P ⩽ 0.031). Bracing the ACL-deficient knee resulted in lower rotation than the unbraced (P ⩽ 0.001) and sleeved (P ⩽ 0.033) conditions. The sleeved condition resulted in lower tibial rotation in the drop landing and pivoting task compared with the unbraced condition (P = 0.019) but not in the stair descending and pivoting task (P = 0.256). Conclusions:Bracing decreased the excessive tibial rotation in ACL-deficient patients during high-demand activities but failed to fully restore normative values. If knee braces can enhance rotational knee stability in ACL-deficient patients, then they could possibly play an important role in preventing further knee pathology in such patients.

139 – Motion Analysis in Anterior Cruciate Ligament Deficient and Reconstructed Knees

The objective measurement of knee motion during functional activities with 3D motion analysis has provided great insights into the restoration of knee biomechanics after ACL reconstructions and any remaining deficits. Several studies have documented that ACL reconstruction reduces but does not restore excessive internal knee rotation. This finding may provide a biomechanical rationale for the increased rate of knee osteoarthritis among athletes who had an ACL tear. More recent, anatomic ACL reconstruction techniques may ameliorate this problem and lead to better long-term outcomes.

Modified Chevron osteotomy for hallux valgus deformity in female athletes. A 2-year follow-up study

BACKGROUND Hallux valgus is an increasingly common deformity in young female athletes that constricts their daily athletic activities and influences foot cosmesis. The aim of this study was to evaluate the outcome of modified Chevron osteotomy for hallux valgus deformity in this specific population. METHODS Forty-two cases of modified Chevron osteotomies were carried out in 33 patients with mild to moderate hallux valgus deformity. Each participant was evaluated for AOFAS score, pain, range of motion, cosmetic and radiological outcome. RESULTS Mean AOFAS score improved to 96.3 (p<0.001) while the mean range of motion of the metatarsophalangeal joint was maintained (p=0.138). The cosmetic result was excellent/good in 40 cases (95%). Mean metatarsophalangeal and intermetatarsal angles were decreased from 29.8° and 14.2° preoperatively to 12.2° and 8.1° postoperatively (p<0.001 and p<0.036), respectively. CONCLUSIONS Modified Chevron osteotomy could offer substantial correction of hallux valgus deformity in young female athletes, with excellent clinical outcome.

11 – Nonoperative Management of Anterior Cruciate Ligament Deficient Patients

Injury to the Anterior Cruciate Ligament (ACL) constitutes one of the most common and debilitating athletic injuries. Rupture of the ACL leads to knee instability, altered kinematic and kinetic behavior of the lower limbs, reduced sport participation, as well as development of early knee osteoarthritis. The optimal treatment for the torn depends on several factors, such as patient’s sex, BMI, knee laxity, lifestyle and goals. Comparing surgical to conservative treatment of ACL tears, there is limited evidence suggesting that the outcomes are not different overall. The goals of the conservative treatment to ACL tears consist of gaining good functional stability, optimizing the functional level, and minimizing the risk for re-injury. Interventions during the initial phase focus on range of motion, pain management, normal ambulation, and preventing muscle atrophy; while in later phases they aim to increase strength and endurance. In the return-to-play phase they focus on neuromuscular optimization of knee function and sports-specific activities.