Restoring tibiofemoral alignment during ACL reconstruction results in better knee biomechanics.

PURPOSE: Anterior cruciate ligament (ACL) reconstruction (ACLR) aims to restore normal knee joint function, stability and biomechanics and in the long term avoid joint degeneration. The purpose of this study is to present the anatomic single bundle (SB) ACLR that emphasizes intraoperative correction of tibiofemoral subluxation that occurs after ACL injury. It was hypothesized that this technique leads to optimal outcomes and better restoration of pathological tibiofemoral joint movement that results from ACL deficiency (ACLD). METHODS: Thirteen men with unilateral ACLD were prospectively evaluated before and at a mean follow-up of 14.9 (SD = 1.8) months after anatomic SB ACLR with bone patellar tendon bone autograft. The anatomic ACLR replicated the native ACL attachment site anatomy and graft orientation. Emphasis was placed on intraoperative correction of tibiofemoral subluxation by reducing anterior tibial translation (ATT) and internal tibial rotation. Function was measured with IKDC, Lysholm and the Tegner activity scale, ATT was measured with the KT-1000 arthrometer and tibial rotation (TR) kinematics were measured with 3Dmotion analysis during a high-demand pivoting task. RESULTS: The results showed significantly higher TR of the ACL-deficient knee when compared to the intact knee prior to surgery (12.2° ± 3.7° and 10.7° ± 2.6° respectively, P = 0.014). Postoperatively, the ACLR knee showed significantly lower TR as compared to the ACL-deficient knee (9.6°±3.1°, P = 0.001) but no difference as compared to the control knee (n.s.). All functional scores were significantly improved and ATT was restored within normal values (P < 0.001). CONCLUSIONS: Intraoperative correction of tibiofemoral subluxation that results after ACL injury is an important step during anatomic SB ACLR. The intraoperative correction of tibiofemoral subluxation along with the replication of native ACL anatomy results in restoration of rotational kinematics of ACLD patients to normal levels that are comparable to the control knee. These results indicate that the reestablishment of tibiofemoral alignment during ACLR may be an important step that facilitates normal knee kinematics postoperatively. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Peroneal electromechanical delay and fatigue in patients with chronic ankle instability.

PURPOSE: The purpose of this study was to investigate the effect of chronic ankle instability (CAI) on electromechanical delay times (EMD) before and after fatigue. Understanding the mechanisms that contribute to CAI is essential for the development of effective rehabilitation programmes. It was hypothesized that patients with CAI will demonstrate prolonged EMD times compared to healthy subjects and that fatigue will cause greater increases in EMD times in the CAI group. METHODS: Twenty-one male volunteers participated in the study providing data on 16 ankles with CAI and 26 with no history of ankle injury. EMD was measured on an isokinetic dynamometer. Measurements were taken with the ankle in neutral (0°) and at 30° of inversion. All subjects followed an isokinetic fatigue protocol until eversion torque fell below 50 % of initial torque for three consecutive repetitions. A 2 × 2 × 2 ANOVA was used to calculate the effect of ankle status (CAI vs. healthy), fatigue, angle (0° vs. 30°) and their interactions on EMD. RESULTS: Fatigue caused a significant increase on EMD [non-fatigued: 122(29)ms vs. fatigue 155(54)ms; p < 0.001]. EMD times were shorter at 30° of inversion compared to neutral [neutral: 145(39)ms vs. 30° of inversion: 132(40)ms, p = 0.015]. An interaction effect for ankle status and angle was found (p = 0.026) with CAI ankles demonstrating longer EMD [CAI: 156(45)ms vs. healthy: 133(40)ms] in neutral but not at 30° of inversion [CAI: 133(46)ms vs. 132(33)ms]. CONCLUSIONS: Patients with CAI had longer EMD times in neutral, but not when the ankle was placed in inversion. This suggests that rehabilitation programmes may be more effective when retraining occurs with the ankle in neutral position. It is likely that low EMD times prevent ankle acceleration at the beginning of the mechanism of injury, but they are less important when the ankle has already inverted at 30°. Both CAI and healthy subjects demonstrated longer EMD after fatigue, emphasizing the importance of proper conditioning in the prevention of delayed peroneal response and subsequent ankle injury. Improving resistance to fatigue of the peroneals may prove to be an effective prevention tool of ankle sprain recurrence in patients with CAI. LEVEL OF EVIDENCE: III.

Effectiveness of aspiration in knee joint effusion management: a prospective randomized controlled study.

PURPOSE: Knee effusion is a common symptom in various knee disorders of both traumatic and non-traumatic aetiology. Although intra-articular aspiration is a widespread treatment approach, its beneficial effect has not been confirmed by a randomized controlled study. The purpose was to evaluate the effectiveness and safety of joint aspiration in acute knee effusion, in relation to traumatic or non-traumatic aetiology. METHODS: One hundred and sixty-seven consecutive patients with acute knee joint effusion were allocated in a randomized controlled fashion into two groups. In the first group, joint aspiration was performed, while in the second group, no aspiration was performed. Range of motion, pain relief, use of analgesics and oedema were evaluated post management. The Knee Society Score and the International Knee Documentation Committee Subjective Evaluation Form were also obtained. In addition, a subgroup analysis of our results in relation to the presence of trauma or not was performed. RESULTS: Aspiration exhibited a temporary improvement in all clinical parameters evaluated, especially in the post-traumatic effusion. However, this improvement lasted only for the first week, due to the early re-accumulation of the effusion. There was no difference between the different groups regarding the clinical outcome in neither trauma or non-trauma patients at the end of the follow-up period. Aspiration aided in earlier establishment of the diagnosis in the non-trauma cases of effusion. CONCLUSIONS: Aspiration resulted in only temporary improvement of the outcome in the treatment of traumatic or not traumatic knee effusion. Aspiration is suggested in effusions of unknown origin in order to establish the diagnosis and for immediate clinical relief. However, aspiration should be performed with consideration in the presence of trauma.

Management of proximal interphalangeal joint hyperextension injuries: a randomized controlled trial.

PURPOSE: To compare the effectiveness of buddy strapping and aluminum orthosis for treatment of proximal interphalangeal (PIP) joint hyperextension injuries. We also evaluated the effect of age on the outcome by comparing our results in adults and children. METHODS: One hundred twenty-one consecutive patients with a PIP joint hyperextension injury of the index, middle, ring, or little finger and without fracture were evaluated. Patients were randomly assigned into 2 groups. In the first group, treatment included buddy strapping of the injured finger to its neighbor noninjured finger for a week. In the second group, immobilization was secured with an aluminum extension blocking orthosis for a week in 15° flexion. Assessment of motion, edema, pain, and strength were performed weekly for the first month and then at 3, 6, and 12 months after injury. RESULTS: The patients treated with buddy strapping exhibited similar outcomes compared with those treated with aluminum orthoses. In patients with full recovery, buddy strapping allowed earlier recovery of motion and resolution of edema and pain compared with aluminum orthosis immobilization. Furthermore, PIP injuries appear to have better outcomes in children than in adults. CONCLUSIONS: Buddy strapping is easy and effective treatment for PIP joint hyperextension injuries. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

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.

The shape and the thickness of the anterior cruciate ligament along its length in relation to the posterior cruciate ligament: a cadaveric study.

PURPOSE: The purpose of this study was to evaluate the shape of the native anterior cruciate ligament (ACL) along its length in relation to the posterior cruciate ligament (PCL) and compare it with the size of the 3 commonly used autografts (bone-patellar tendon-bone [BPTB], single-bundle hamstring, and double-bundle hamstring). METHODS: With the knee in extension, we filled the intercondylar notch with paraffin, fixing the cruciate ligaments in their natural position, in 8 cadaveric specimens. The ACL-PCL tissue specimen, embedded in paraffin, was removed en bloc. Gross sections were prepared in the coronal plane and were evaluated histologically. The width, thickness, and cross-sectional area of both the ACL and PCL were determined. The dimensions of the semitendinosus tendon (ST), gracilis tendon (GT), and BPTB grafts were measured and compared with those of the native ACL. RESULTS: The PCL occupies the largest part of the intercondylar area, leaving only a small space for the ACL in knee extension. The ACL midsubstance has a width of 5 mm, resembling a band shape. Only before its tibial insertion does the ACL fan out and take the form of its tibial attachment. The BPTB graft has a thickness of 5.8 mm, whereas the ST and GT grafts have a thickness of 6.25 mm and 4.5 mm, respectively, and are comparable to the midsubstance of the ACL but undersized in the tibial insertion (P = .0016 for BPTB graft, P = .002 for ST graft, and P = .0003 for GT graft). A quadruple-looped ST-GT graft, with a diameter of 8 mm, is oversized in the midsubstance (P = .0002) but fits better in the tibial attachment. CONCLUSIONS: The ACL midsubstance has a width of 5 mm, resembling a band shape. Before its tibial insertion, the ACL fans out like a trumpet, taking the form of its wide tibial attachment. CLINICAL RELEVANCE: The dimensions of the native ACL have to be considered in graft selection for anatomic ACL reconstruction.

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.

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

PURPOSE: Technological 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. METHODS: High-impact articles that enhanced understanding of ACL injury aetiology, rehabilitation, prevention and adaptations after reconstruction were selected. RESULTS: The 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. CONCLUSION: As 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.

Hamstring-dominant strategy of the bone-patellar tendon-bone graft anterior cruciate ligament-reconstructed leg versus quadriceps-dominant strategy of the contralateral intact leg during high-intensity exercise in male athletes.

PURPOSE: The purpose of this study was to investigate the effect of anterior cruciate ligament (ACL) reconstruction on the quadriceps-dominant strategy as a parameter associated with the neuromuscular control of the knee joint. METHODS: In this study 14 competitive soccer players who had undergone ACL reconstruction with bone-patellar tendon-bone autograft and 14 healthy competitive soccer players performed two 10-minute treadmill runs, 1 at moderate intensity and 1 at high intensity. Electromyographic recordings were acquired by use of a telemetric system at the third, fifth, seventh, and tenth minute of the runs from the vastus lateralis and the biceps femoris bilaterally. The dependent variable examined was the peak electromyographic amplitude during the stance phase. Analyses of variance were used to examine significant main effects and interactions. RESULTS: Vastus lateralis electromyographic activity during high-intensity running increased for both the control leg and intact leg (F = 4.48, P < .01), whereas it remained unchanged for the reconstructed leg (P > .05). Biceps femoris electromyographic activity during high-intensity running increased for the reconstructed leg only compared with both the control leg (F = 3.03, P < .05) and intact leg (F = 3.36, P < .03). CONCLUSIONS: There is no presence of the quadriceps-dominant strategy in ACL-reconstructed athletes during moderate-intensity exercise. During high-intensity exercise, the intact contralateral leg develops the quadriceps-dominant strategy whereas the reconstructed leg does not. The reconstructed leg instead increases biceps femoris activity, developing a "hamstring-dominant" strategy, and this "asymmetry" may theoretically be in favor of the reconstructed knee. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Correlation between anterior cruciate ligament graft obliquity and tibial rotation during dynamic pivoting activities in patients with anatomic anterior cruciate ligament reconstruction: an in vivo examination.

PURPOSE: To investigate the effect of coronal- and sagittal-plane anterior cruciate ligament (ACL) graft obliquity on tibial rotation (TR) range of motion (ROM) during dynamic pivoting activities after ACL reconstruction with bone-patellar tendon-bone (BPTB) autograft. METHODS: We evaluated 19 ACL-reconstructed patients (mean age, 29 years; age range, 18 to 38 years; mean time interval postoperatively, 19.9 months) and 19 matched control subjects (mean age, 30.6 years; age range, 24 to 37 years) using motion analysis during (1) descending a stairway and pivoting and (2) landing from a jump and pivoting. Magnetic resonance imaging was used to measure the coronal and sagittal ACL graft angle. The dependent variables were TR ROM during pivoting and the side-to-side difference (SSD) in TR ROM between the reconstructed knee and the contralateral intact knee. RESULTS: TR ROM of the ACL-reconstructed knee was significantly increased compared with both the contralateral intact knee and the healthy control knee (P < .05). A significant positive correlation was observed between TR ROM and coronal ACL graft angle (r = 0.727, P = .0006 for descending and pivoting; r = 0.795, P = .0001 for landing and pivoting) as well as between SSD of TR ROM and coronal ACL graft angle (r = 0.789, P < .0001 for descending and pivoting; r = 0.799, P < .0001 for landing and pivoting). No correlation was found with the sagittal ACL graft angle. CONCLUSIONS: After ACL reconstruction with a BPTB graft, patients' knees showed higher TR values than their uninjured knees and the knees of uninjured control volunteers during dynamic pivoting activities. The findings of this study show that TR was better restored in ACL-reconstructed patients with a more oblique graft in the coronal plane. A similar relation was not observed for graft orientation in the sagittal plane. Although these data do not imply a cause-and-effect relation between the 2 variables, they may indicate that a more oblique placement of a single BPTB ACL graft in the coronal plane is correlated with better control of TR. LEVEL OF EVIDENCE: Level IV, case series.

Kinematic predictors of subjective outcome after anterior cruciate ligament reconstruction: an in vivo motion analysis study.

PURPOSE: The purpose of this study was to test whether rotational knee kinematics during dynamic pivoting activities are predictive of subjective functional outcome (IKDC, Lysholm), objective laxity scores (KT max), and activity levels (Tegner) in patients after anterior cruciate ligament reconstruction (ACLR). METHODS: Thirty-one patients with single-bundle ACLR were evaluated prospectively with 3D-motion analysis during (1) descending a stairway and pivoting and (2) landing from a jump and pivoting. The side-to-side difference of tibial rotation range of motion (SSDTR) between the ACLR and the contralateral intact knee was calculated for the pivoting phase of each task. Linear regression models were applied with SSDTR, for each task predictors of the subjective IKDC score, Lysholm score, anterior tibial translation, and Tegner activity level. RESULTS: SSDTR for descending and landing were predictive of the IKDC subjective score (R(2) = 0.46, p < 0.001 and R(2) = 0.40, p < 0.001, respectively) with "medium" effect sizes and of the Lysholm score (R(2) = 0.13, p < 0.05 and R(2) = 0.09, n.s.) with "small" to "none" effect sizes. SSDTR was not predictive of anterior translation or Tegner activity level (n.s.). CONCLUSIONS: Restoring rotational kinematics during dynamic pivoting activities after ACLR is predictive of functional outcome. The ability of the athlete after ACLR to control tibial rotation during pivoting activities may be predictive of functional outcome. LEVEL OF EVIDENCE: Case series study. Level IV.

Effect of laterality and fatigue in peroneal electromechanical delay.

INTRODUCTION: Extremity dominance is one of the intrinsic factors that have been identified for ankle sprains. Electromechanical delay (EMD) is an integral part of the peroneal motor response and, therefore, substantial in preventing ankle sprains. This study aimed to investigate the effect of laterality on EMD times before and after fatigue. METHODS: Fifteen healthy male volunteers participated in the study. Measurements were taken with the ankle in a neutral (0°) position, and all subjects followed an isokinetic fatigue protocol. Repeated ANOVA was used for statistical analysis, and the α level was set a priori at p ≤ 0.05. RESULTS: No significant difference was noted in EMD times between the dominant and non-dominant legs of the volunteers (p = 0.940). Fatigue caused a significant increase in EMD by 10-15 ms (p = 0.003), while the leg × fatigue interaction was not significant (p = 0.893). CONCLUSIONS: In a non-injured athlete, both ankles seem to be under the same protection of the reactive response of the peroneal muscles. Therefore, athletes should be aware that both their extremities are equally exposed to the danger of an ankle injury. Also, fatigued ankles demonstrate longer EMD times, implying that improving resistance to fatigue may add another layer of protection that has the potential to prevent ankle sprain recurrence.

Higher Infection Rate after ACL Reconstruction with Hamstrings Tendon Autografts Compared with Bone Patellar Bone Tendon Autografts: A Review.

Infection after anterior cruciate ligament reconstruction is a rare but devastating complication resulting in a deleterious impact on knee function as well as an increased related cost for treatment and rehabilitation for the patients. There are conflicting reports regarding the rate of infection between bone patellar tendon bone (BPTB) and hamstrings tendon (HT) autografts for anterior cruciate ligament reconstruction. Therefore, we performed this review to summarize all the available data regarding the risk of infection after ACL reconstruction, to provide insight on the infection risk between BPTB and HT autografts, and to discuss current recommendations for the diagnosis and treatment of these infections. The incidence and risk of infection after ACL reconstruction with HT graft is higher compared with BPTB grafts. The most commonly subacute and late infections, quadruple type, need for cannulated instruments for harvesting, size and shape and fixation of the extra-tunnel material of the HT are important risk factors for infection. Combined antibiotics administration and adequate arthroscopic lavage and debridement are the optimal treatments for ACL reconstruction infection. Early diagnosis and treatment is the most important predictor for graft retention, which accounts more commonly for BPTB grafts. The treating physicians should be aware of the higher incidence of infection after ACL reconstruction with HT graft, as well as for the need for a high clinical suspicion for early diagnosis of the infection. These will increase the possibility of eradication of the infection and retention of the graft.

Knee flexor muscle responses under fatigue after harvesting the hamstrings for anterior cruciate ligament reconstruction. [corrected].

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.

Malalignment and cartilage lesions in the patellofemoral joint treated with autologous chondrocyte implantation.

PURPOSE: The aim of our current study is to present the 12.6 years' follow-up results in patients with cartilage lesions of the patellofemoral joint, treated with autologous chondrocyte implantation (ACI) with the use of periosteum. METHODS: Ninety-two patients having patella or trochlea lesion participated in this study. Lysholm and Tegner questionnaires were completed 12.6 years (SD 2.3 years) after the surgery. The patients were asked whether they feel better, worse or had not experienced any difference compared to previous years and whether they would undergo the operation again. Complications or subsequent surgeries were also assessed. RESULTS: Median Tegner score was three, improved by one level compared with preoperative values (P = 0.02). Median Lysholm score was 70, improved by nine points (n.s.). Seventy-two percent of the patients were better or unchanged while 93% would undergo the operation again. Patients with no kissing lesions appeared to have a better prognosis. Patients with malalignment or instability that had undergone a realignment procedure had comparable outcomes to the patients that did not need any additional surgery. Realignment procedures increased the incidence of serious complications but they were associated with decreased incidence of periosteal hypertrophy. No association was found between the age of the patients at the time of the ACI or the size per lesion and any of the clinical outcomes. CONCLUSION: ACI provides a satisfactory outcome for the treatment of cartilage lesions of the patellofemoral joint, even for the cases with concomitant patellar instability. It seems that correcting the coexisting background factors with realignment, stabilizing or unloading procedures, along with the treatment of cartilage lesions, is improving the clinical outcomes over time and decreases the incidence of periosteal hypertrophies although increasing the incidence of serious complications. Our study reveals the good results and the high level of patients' activities (as shown by Tegner score), were preserved 12.6 years after the implantation, in both isolated trochlea and patella lesions and also in multiple and in kissing lesions where an intervention could be considered as a salvage procedure.

New insights into anterior cruciate ligament deficiency and reconstruction through the assessment of knee kinematic variability in terms of nonlinear dynamics.

PURPOSE: Injuries to the anterior cruciate ligament (ACL) occur frequently, particularly in young adult athletes, and represent the majority of the lesions of knee ligaments. Recent investigations suggest that the assessment of kinematic variability using measures of nonlinear dynamics can provide with important insights with respect to physiological and pathological states. The purpose of the present article was to critically review and synthesize the literature addressing ACL deficiency and reconstruction from a nonlinear dynamics standpoint. METHODS: A literature search was carried out in the main medical databases for studies published between 1990 and 2010. RESULTS: Seven studies investigated knee kinematic variability in ACL patients. Results provided support for the theory of "optimal movement variability". Practically, loss below optimal variability is associated with a more rigid and very repeatable movement pattern, as observed in the ACL-deficient knee. This is a state of low complexity and high predictability. On the other hand, increase beyond optimal variability is associated with a noisy and irregular movement pattern, as found in the ACL-reconstructed knee, regardless of which type of graft is used. This is a state of low complexity and low predictability. In both cases, the loss of optimal variability and the associated high complexity lead to an incapacity to respond appropriately to the environmental demands, thus providing an explanation for vulnerability to pathological changes following injury. CONCLUSION: Subtle fluctuations that appear in knee kinematic patterns provide invaluable insight into the health of the neuromuscular function after ACL rupture and reconstruction. It is thus critical to explore them in longitudinal studies and utilize nonlinear measures as an important component of post-reconstruction medical assessment. LEVEL OF EVIDENCE: II.

Knee braces can decrease tibial rotation during pivoting that occurs in high demanding activities.

PURPOSE: The purpose of this study was to investigate whether knee braces could effectively decrease tibial rotation during high demanding activities. METHODS: Using an in vivo three-dimensional kinematic analysis, 21 physically active, healthy, male subjects were evaluated. Each subject performed two tasks that were used extensively in the literature because they combine 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 under three conditions: (A) wearing a prophylactic brace (braced), (B) wearing a patellofemoral brace (sleeved), and (C) unbraced condition. RESULTS: In the first task, tibial rotation during the pivoting phase was significantly decreased in the braced condition as compared to the sleeved condition (P = 0.019) and the non-braced condition (P = 0.002). In the second task, the same variable was significantly decreased in the braced condition as compared to the sleeved (P = 0.001) and the unbraced condition (P < 0.001). The sleeved condition also produced significantly decreased tibial rotation with respect to the unbraced condition (P = 0.021). CONCLUSIONS: Bracing decreased tibial rotation in activities where increased translational and rotational forces were applied. Because knee braces decreased tibial rotation, they can possibly be used with ACL-reconstructed and ACL-deficient patients to prevent such problems. LEVEL OF EVIDENCE: Case-control study, Level III.

The influence of graft choice on isokinetic muscle strength 4-24 months after anterior cruciate ligament reconstruction.

PURPOSE: Regaining adequate strength of the quadriceps and hamstrings after anterior cruciate ligament (ACL) reconstruction is important for maximizing functional performance. However, the outcome of muscle strength after either BPTB or hamstrings autograft is unclear given the plethora of published studies that report post-operative muscle strength. The purpose of this study was to systematically compare the muscle strength of patients who have undergone ACL reconstruction using either Bone Patellar Tendon Bone (BPTB) or Hamstrings (HST) autograft. METHODS: The databases of MEDLINE, Cinahal and EMBASE were systematically searched for articles that report muscle strength outcome following ACL reconstruction. The quality of the studies was evaluated and a meta-analysis of the muscle strength outcomes was conducted on reported data. RESULTS: Fourteen studies were included in this systematic review: eight Randomized Control Studies (RCT) and six non-Randomized Control Studies (non-RCT). A meta-analysis was performed involving eight of the included studies (4 RCTs & 3 non-RCTs). At 60°/s and 180°/s, patients with BPTB graft showed a greater deficit in extensor muscle strength and lower deficit in flexor muscle strength compared with patients with HST. CONCLUSION: This systematic review of Level III evidence showed that isokinetic muscle strength deficits following ACL reconstruction are associated with the location of the donor site. These deficits appear to be unresolved up to 2 years after ACL reconstruction. LEVEL OF EVIDENCE: III.

Velocity at lactate threshold and running economy must also be considered along with maximal oxygen uptake when testing elite soccer players during preseason.

Maximal oxygen uptake (VO2max) has been traditionally used to explain physiologic differences among soccer teams of different ranking. However, other endurance markers may have greater discriminatory ability. The purpose of this study was to examine whether velocity at lactate threshold and running economy can be used to better discriminate endurance characteristics of soccer teams of different levels along with VO2max during preseason testing. One hundred twenty-nine professional Greek soccer players participating in the top 3 divisions underwent an incremental treadmill test to exhaustion using expired gas analysis and simultaneous blood lactate measurements. Velocity at lactate threshold was determined using the Dmax method, and running economy was measured at 12 km·h⁻¹. Analyses of variation were used to compare for differences between divisions. Velocity at lactate threshold was the only variable that was statistically different between any 2 divisions. In every comparison, the higher division had the higher velocity at lactate threshold. The VO2 was statistically different only between the top 2 divisions. Running economy was statistically different between divisions with similar VO2, with better running economy for the higher division in each comparison. These results indicate that velocity at lactate threshold can be used to better discriminate endurance characteristics of soccer teams of different level along with VO2max during preseason testing. Running economy may reveal differences between teams with similar VO2max.

Cadaveric study of anterior cruciate ligament failure patterns under uniaxial tension along the ligament.

PURPOSE: The purpose of our study was to clarify the events that take place during anterior cruciate ligament (ACL) failure, focusing on the behavior of the ACL as a composition of multiple fibers, during uniaxial tension along the ligament. METHODS: Ten fresh-frozen human cadaveric knee specimens were fixed in an Instron machine (Instron, Norwood, MA), and load was applied parallel to the ACL axis. Two cameras were used to detect the failure mode of the ACL and its different groups of fibers. The distinct bundles of fibers were marked in each specimen before testing. The macroscopic findings during the experiment were used for comparison with the biomechanical results. RESULTS: The ACL showed a non-monotonic response during testing. The load-elongation curve showed a plateau or a second peak after the initial drop in load. Macroscopically, some fibers were failing initially, whereas the intact fibers had a remaining load potential. In our setting, 3 different failure patterns were recognized, specifically, a midsubstance tear of the anteromedial or the posterolateral bundle with a subsequent failure of the intact bundle or an initial avulsion of the anteromedial attachment. Analysis of the video frames showed a direct connection between the failure patterns in the load-elongation curves and the macroscopic sequence of events during ACL failure. CONCLUSIONS: The ACL ligament acts as a multifiber construction. In our setting, rupture follows 3 specific patterns where a complete or partial tear of the fiber bundles occurs first and the remaining intact fiber bundles have a potential load resistance. CLINICAL RELEVANCE: Our study allows a better understanding of the mechanical properties of the ACL. An update on the biomechanics of ACL failure during uniaxial tension after the "double-bundle revolution" could provide data helpful for ACL reconstruction.