Joseph M. Hart

Quadriceps activation following knee injuries: a systematic review.

CONTEXT Arthrogenic muscle inhibition is an important underlying factor in persistent quadriceps muscle weakness after knee injury or surgery. OBJECTIVE To determine the magnitude and prevalence of volitional quadriceps activation deficits after knee injury. DATA SOURCES Web of Science database. STUDY SELECTION Eligible studies involved human participants and measured quadriceps activation using either twitch interpolation or burst superimposition on patients with knee injuries or surgeries such as anterior cruciate ligament deficiency (ACLd), anterior cruciate ligament reconstruction (ACLr), and anterior knee pain (AKP). DATA EXTRACTION Means, measures of variability, and prevalence of quadriceps activation (QA) failure (<95%) were recorded for experiments involving ACLd (10), ACLr (5), and AKP (3). DATA SYNTHESIS A total of 21 data sets from 18 studies were initially identified. Data from 3 studies (1 paper reporting data for both ACLd and ACLr, 1 on AKP, and the postarthroscopy paper) were excluded from the primary analyses because only graphical data were reported. Of the remaining 17 data sets (from 15 studies), weighted mean QA in 352 ACLd patients was 87.3% on the involved side, 89.1% on the uninvolved side, and 91% in control participants. The QA failure prevalence ranged from 0% to 100%. Weighted mean QA in 99 total ACLr patients was 89.2% on the involved side, 84% on the uninvolved side, and 98.5% for the control group, with prevalence ranging from 0% to 71%. Thirty-eight patients with AKP averaged 78.6% on the involved side and 77.7% on the contralateral side. Bilateral QA failure was commonly reported in patients. CONCLUSIONS Quadriceps activation failure is common in patients with ACLd, ACLr, and AKP and is often observed bilaterally.

Neuromuscular consequences of anterior cruciate ligament injury.

The neuromuscular consequences of anterior cruciate ligament (ACL) injury are important considerations because these deficits play a crucial role in a patients recovery following ACL injury or reconstruction. The purpose of this article is to review and synthesize the known neuromuscular consequences of ACL injury and reconstruction. Specifically, changes in somatosensation, muscle activation, muscle strength, atrophy, balance, biomechanics, and patient-oriented outcomes are discussed. Understanding neuromuscular consequences aids in the construction of optimized rehabilitation strategies.

Predictors for Hamstring Graft Diameter in Anterior Cruciate Ligament Reconstruction

Background The ability to accurately predict the diameter of autograft hamstring tendons has implications for graft choice and fixation devices used in anterior cruciate ligament (ACL) reconstruction. Purpose To determine whether simple anthropometric measurements such as height, mass, body mass index (BMI), age, and gender can be used to accurately predict the diameter of hamstring tendons for ACL reconstruction surgery. Study Design Cohort study (prevalence); Level of evidence, 2. Methods The authors conducted medical record reviews and telephone interviews of 106 consecutive patients with ACL reconstruction using quadrupled semitendinosus-gracilis autograft from 2004 to 2006. Data included anthropometric measurements (height, mass, gender, and age at the time of surgery). Hamstring diameter was obtained using cylindrical sizers in 0.5-mm increments and recorded in the patients surgical record. Correlation coefficients (Pearson r) and stepwise, multiple linear regression were used to determine the relationship between the outcome variable (hamstring graft diameter) and the predictor variables (age, gender, height, mass, and BMI). Independent sample t tests were used to compare hamstring graft diameter between genders. Results Hamstring graft diameter was related to height (r = .36, P < .001), mass (r = .25, P = .005), age (r = —.16, P = .05), and gender (r = —.24, P = .006) but was not related to BMI (P > .05). Height was a statistically significant prediction variable (R2 = .13, P < .001). From the current data, a regression equation was calculated that suggested that a patient <147 cm (58 in) tall is likely to have a quadrupled hamstring graft diameter <7 mm in diameter (graft size = 2.4 + 0.03 × height in cm). Women had significantly smaller hamstring graft diameters (7.5 ± 0.7 mm) than did men (7.9 ± 0.9 mm, P = .01). Conclusions Of the parameters studied, height was the best predictor of hamstring tendon diameter, particularly in women.

Immediate Effects of Transcutaneous Electrical Nerve Stimulation and Focal Knee Joint Cooling on Quadriceps Activation

PURPOSE To determine whether transcutaneous electrical nerve stimulation (TENS) and focal knee joint cooling will affect the quadriceps central activation ratio (CAR) in patients with tibiofemoral osteoarthritis. METHODS Thirty-three participants with diagnosed tibiofemoral osteoarthritis were randomly allocated to the 45-min TENS treatment (six males and four females, 56 +/- 10.1 yr, 174.11 +/- 10.78 cm, 89.34 +/- 21.3 kg), the 20-min focal knee joint cooling treatment (six males and five females, 58 +/- 8.4 yr, 176.41 +/- 8.29 cm, 83.18 +/- 17.97 kg), or the control group (five males and seven females, 54 +/- 9.9 yr, 166.37 +/- 13.07 cm, 92.14 +/- 25.37 kg). Volitional quadriceps activation, maximal voluntary isometric contraction, and subjective pain measurements were conducted at baseline and at 20, 30, and 45 min. The 20-min focal knee joint cooling intervention consisted of two 1.5-L ice bags to the anterior and posterior aspects of the knee. The TENS group received 45 min of a sensory, biphasic square wave stimulation (150-mus phase duration and 150 pps) from four 2 x 2-inch electrodes positioned around the patella. RESULTS : TENS resulted in a significantly higher percent change in CAR scores compared with control at 20 min (6.4 +/- 4.8 vs -3.5 +/- 8, P = 0.006), 30 min (9.7 +/- 10.16 vs -1 +/- 7.9, P = 0.025), and 45 min (11.25 +/- 6.96 vs 0.81 +/- 9.4, P = 0.029). Focal knee joint cooling resulted in significantly higher percent change scores compared with the control group at 20 min (5.75 +/- 7.25 vs -3.5 +/- 8, P = 0.009) and trended to be higher at 45 min (9.06 +/- 9.63 vs 0.81 +/- 9.4, P = 0.098). No significant differences in percent change for CAR were found between the TENS and the focal knee joint cooling group. CONCLUSIONS Both TENS and focal knee joint cooling increased the quadriceps CAR immediately after application in participants with tibiofemoral osteoarthritis.

Sagittal plane knee joint moments following anterior cruciate ligament injury and reconstruction: A systematic review

BACKGROUND Gait adaptations in persons with anterior cruciate ligament (ACL) injuries have been debated. Many studies examine high speed, 3-dimensional video gait analysis to compare knee joint torques during simulated activities of daily living. METHODS We performed a systematic review of the literature for published clinical papers that reported sagittal plane knee joint kinetics in ACL deficient or reconstructed individuals. We calculated weighted effect sizes (Cohens d) to evaluate the magnitude of differences between the injured limb and the contralateral limb and healthy, uninjured limbs in control subjects. FINDINGS Ten published papers reported kinetic data in ACL deficient subjects while walking for comparisons to the contralateral side (weighted average d=-0.83, range: -3.21, 1.07), and to healthy control knees (weighted average d=-1.0, range: -3.36, 0.17); four papers reported data during jogging compared to the contralateral side (weighted average d=-0.94, range: -4.15, 0.17), and to controls (weighted average d=-1.42, range: -3.83,-0.2). Four papers reported data for ACL-reconstructed patients compared to healthy controls during walking (weighted average d=-0.94, range: -0.4, -1.77) and jogging (weighted average d=-1.18). INTERPRETATION Effect sizes comparing knee joint moments in injured vs. healthy control subjects appear to be slightly higher while jogging than walking, and higher in ACL-deficient patients compared to reconstructions. However, magnitudes are all large. Few studies report stair climbing. Consequently, it is difficult to make inferences with confidence during these tasks.

Hamstring Graft Size Prediction A Prospective Clinical Evaluation

Background Recently we retrospectively collected clinical data to predict hamstring graft diameter. Prospective data collection will improve and further define prediction of hamstring graft size. Hypothesis Clinical anthropometric data can be used to predict hamstring graft size. Study Design Cohort study (prevalence); Level of evidence, 1. Methods Fifty consecutive patients with anterior cruciate ligament deficiency scheduled for reconstruction using hamstring autograft were prospectively evaluated. Preoperatively we recorded height, weight, body mass index, age, gender, leg length, thigh length, shank length, bilateral thigh circumference, and Tegner score. Intraoperative measurements of both the gracilis and semitendinosus tendons were made, including absolute length before fashioning the graft and final diameter of the quadrupled graft using sizing tubes calibrated to 0.5 mm. Bivariate correlation coefficients (Pearson r) were calculated to identify relationships among clinical data and intraoperatively measured hamstring graft length and diameter. Results Strongest correlations for graft lengths were height and leg length measurements. Shorter persons with shorter leg, thigh, and shank lengths tended to have shorter gracilis and semitendinosus grafts. Likewise, the strongest correlations for graft diameter were weight and thigh circumference. Self-reported activity level and age did not correlate. Gender comparison revealed that women who were shorter, lighter, and had smaller body mass indices were more likely to have smaller graft diameters and shorter graft lengths. Conclusion Patients weighing less than 50 kg, less than 140 cm in height, with less than 37 cm thigh circumference, and with body mass index less than 18 should be considered at high risk for having a quadrupled hamstring graft diameter less than 7 mm. When separated by gender, small graft diameters are most likely in older, short, female subjects with small thigh circumferences or young, skinny, male subjects with small thigh circumferences and low body mass index. Common clinical measurements can be used for preoperative identification of patients at risk for insufficient graft tissue and would be useful for patient counseling and alternative graft source planning.

Anatomic Femoral Tunnel Drilling in Anterior Cruciate Ligament Reconstruction Use of an Accessory Medial Portal Versus Traditional Transtibial Drilling

Background: During anatomic anterior cruciate ligament (ACL) reconstruction, we have found that the femoral footprint can best be visualized from the anteromedial portal. Independent femoral tunnel drilling can then be performed through an accessory medial portal, medial and inferior to the standard anteromedial portal. Purpose: To compare the accuracy of independent femoral tunnel placement relative to the ACL footprint using an accessory medial portal versus tunnel placement with a traditional transtibial technique. Study Design: Controlled laboratory study. Methods: Ten matched pairs of cadaveric knees were randomized such that within each pair, one knee underwent arthroscopic transtibial (TT) drilling, and the other underwent drilling through an accessory medial portal (AM). All knees underwent computed tomography (CT) both preoperatively and postoperatively with a technique optimized for ligament evaluation (80 keV with maximum mAs). Computed tomography was performed with a dual-energy scanner. Commercially available third-party software was used to fuse the preoperative and postoperative CT scans, allowing anatomic comparison of the ACL footprint to the drilled tunnel. The ACL footprint was marked in consensus by an orthopaedic surgeon and a musculoskeletal radiologist and then compared with the tunnel aperture after drilling. The percentage of tunnel aperture contained within the native footprint as well as the distance from the center of the tunnel aperture to the center of the footprint was measured. Results: The AM technique placed 97.7% ± 5% of the tunnel within the native femoral footprint, significantly more than 61.2% ± 24% for the TT technique (P = .001). The AM technique placed the center of the femoral tunnel 3.6 ± 1.2 mm from the center of the native footprint, significantly closer than 6.0 ± 1.9 mm for the TT technique (P = .003). Conclusion: This study demonstrates that use of an accessory medial portal will facilitate more accurate placement of the femoral tunnel in the native ACL femoral footprint. Clinical Relevance: More accurate placement of the femoral tunnel in the native ACL femoral footprint should improve the ability to achieve more anatomic positioning of the ACL graft.

Effects of Transcutaneous Electrical Nerve Stimulation and Therapeutic Exercise on Quadriceps Activation in People With Tibiofemoral Osteoarthritis

STUDY DESIGN Blinded, randomized controlled trial. OBJECTIVES To determine if the combination of transcutaneous electrical nerve stimulation (TENS) set to a sensory level and therapeutic exercise would be more effective than the combination of placebo TENS and therapeutic exercises or therapeutic exercises only to increase quadriceps activation in individuals with tibiofemoral osteoarthritis. BACKGROUND Quadriceps activation deficits are common in those with tibiofemoral osteoarthritis, and TENS has been reported to immediately increase quadriceps activation. Yet the long-term benefits of TENS for motor neuron activation have yet to be determined. METHODS Thirty-six individuals with radiographically assessed tibiofemoral osteoarthritis were randomly assigned to the TENS and exercise, placebo and exercise, and exercise only groups. All participants completed a supervised 4-week lower extremity exercise program. TENS and placebo TENS were worn throughout the therapeutic exercise sessions, as well as during daily activities. Our primary outcome measures, quadriceps central activation ratio, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were evaluated at baseline and at 2 weeks and 4 weeks of the intervention. RESULTS Quadriceps activation was significantly higher in the TENS with exercise group compared to the exercise only group at 2 weeks (0.94 ± 0.04 versus 0.82 ± 0.12, P<.05) and the placebo and exercise group at 4 weeks (0.94 ± 0.06 versus 0.81 ± 0.15, P<.05). WOMAC scores improved in all 3 groups over time, with no significant differences among groups. CONCLUSION This study provides evidence that TENS applied in conjunction with therapeutic exercise and daily activities increases quadriceps activation in patients with tibiofemoral osteoarthritis and, while function improved for all participants, effects were greatest in the group treated with a combination of TENS and therapeutic exercises. LEVEL OF EVIDENCE Therapy, level 1b-.

Voluntary Quadriceps Activation Deficits in Patients with Tibiofemoral Osteoarthritis: A Meta-Analysis

The objective of this study was to assess the magnitude of quadriceps activation deficits in the involved extremity and contralateral extremity of patients with knee joint osteoarthritis (OA), as well as matched controls. An exhaustive search of the literature was performed using Web of Science between 1970 and February 24, 2010, using the search terms “osteoarthritis” AND “quadriceps activation” OR “quadriceps inhibition” and cross‐referencing pertinent articles. Studies written in English reporting quadriceps activation means and standard deviations in patients with tibiofemoral OA via a method using an exogenous electrical stimulation were evaluated for methodological quality and were included for data analysis. Fourteen individual studies met the criteria for inclusion into data analysis. The number of participants and mean activation levels were used to calculate weighted means for the involved limb (14 studies), the contralateral limb (from a subset of 6 studies), and an involved limb subset from only the studies evaluating the contralateral limb and population of control subjects (5 studies). Weighted means from the involved limb (82.2; 95% CI = 81.4‐83.3%), contralateral limb (81.7; 80.1‐83.3%), and involved limb subset (76.8; 74.8‐78.8%) groups were found to have lower volitional quadriceps activation compared with the control groups (90; 88.9‐91.7%). Although the weighted involved limb mean was not different from that of the contralateral limb, the mean and 95% confidence intervals for the involved limb subset were lower than that of the contralateral limb group, suggesting that the involved limb had less volitional activation within OA subjects. This provides evidence that bilateral quadriceps volitional activation deficits are present in persons with knee OA.

A Comparison of 2 Drilling Techniques on the Femoral Tunnel for Anterior Cruciate Ligament Reconstruction

PURPOSE This cadaveric study was undertaken to characterize the femoral tunnel geometry resulting from commonly used drilling techniques in anterior cruciate ligament reconstruction. METHODS We randomized 10 matched-pair cadaveric knees (20 knees) into 2 groups with right and left matched pairs from each cadaver. Of the knees, 10 underwent transtibial femoral tunnel drilling from a far-medial starting point on the tibia (group 1) and 10 had the femoral tunnel drilled from a medial arthroscopic portal (group 2). The dimensions and size of the apertures, the volume and length of the tunnels, and the distance of the tunnels from the posterior wall and articular surface were measured by computed tomography. RESULTS The mean femoral tunnel length was 29.7 mm in group 1 and 15.7 mm in group 2. The mean volume for each tunnel was 2,401 mm(3) in group 1 and 2,071 mm(3) in group 2. The intra-articular aperture area was 94.6 mm(2) in group 1 and 98.6 mm(2) in group 2. In group 2 the intra-articular shape was more elliptical than in group 1, with the long axis averaging 13.5 ± 1.3 mm (P = .004) and short axis averaging 9.7 ± 1.0 mm (P = .002); in group 2 the long axis averaged 12.5 ± 1.7 and short axis averaged 10.3 ± 0.7 (P = .002). Group 2 was closer to the posterior wall and articular surface (6.9 ± 0.6 mm and 9.4 ± 0.6 mm, respectively) than group 1 (10.8 ± 1.0 mm and 11.8 ± 1.9 mm, respectively). CONCLUSIONS We determined the length and volume of the femoral tunnel to be shorter and smaller, respectively, with a medial arthroscopic portal. In addition, the aperture shape was more of an ellipse with a medial arthroscopic portal. The medial arthroscopic portal also created a femoral tunnel that was closer to the posterior wall and articular surface of the femur. CLINICAL RELEVANCE Improved characterization of osseous tunnels with 3-dimensional figures will allow for improved matching of graft and incorporation.