Isokinetic Quadriceps Strength Research Articles

Return to Sport Following Anterior Cruciate Ligament Reconstruction: A Scoping Review of Criteria Determining Return to Sport Readiness.

Provide a concise review of currently utilized functional metrics and patient reported outcomes measures (PROMs) determining appropriate return to sport following anterior cruciate ligament reconstruction (ACLR). When determining return to sport following ACLR, a limb symmetry index (LSI) ≥ 90% when compared to the contralateral extremity is the most commonly reported functional metric. LSI is most commonly assessed using isokinetic quadriceps strength, followed by single-leg vertical hop and cross-over hop test. A minimum ACL-Return to Sport Index (ACL-RSI) score of 68.2 was reported, as well as a mean International Knee Documentation Committee (IKDC) score of 88.3%. A minimum Knee Injury and Osteoarthritis Outcome Score-Quality of Life (KOOS-QoL) of 62.5% was reported in a single investigation. There remains limited data on reported metrics guiding return to sport following ACLR. Evaluation of LSI when compared to the contralateral extremity is the most commonly reported functional measure, with ACL-RSI, IKDC and KOOS-QoL also being reported. Further investigations examining return to sport rate and the incidence of recurrent injury, factoring in differences in sex, competition level, and the presence or absence of concomitant meniscal injuries, based on functional metrics and PROMs is warranted to better understand which outcome measures are predictive of successful return to sport following ACLR.

Effect of serum 25-hydroxyvitamin D level on quadriceps strength: a systematic review and meta-analysis

BackgroundVitamin D deficiency has been linked to poor muscle function, cartilage degeneration, and the development of knee osteoarthritis. However, the impact of serum 25-hydroxyvitamin D [25(OH)D] level on quadriceps muscle strength remains inconclusive, largely due to variations in study designs, differences in study populations, and the influence of confounding factors such as co-supplementation with other vitamins. The existing literature presents mixed findings, highlighting the need for a comprehensive evaluation of the available evidence.PurposeThis systematic review and meta-analysis aim to summarise.Study designSystematic review; Level of evidence, 4.MethodsSearches were conducted using Medline (Ovid), Embase (Ovid), CINAHL (EBSCOhost), and SPORTDiscus (EBSCOhost), which aimed to summarise recent (published after 2000 and before March 1st, 2024) studies reporting the effects of serum 25(OH)D levels on quadriceps strength. Appraisal tool for Cross-Sectional Studies (AXIS) for cross-sectional studies and Quality in Prognosis Studies (QUIPS) for longitudinal studies. Results from the AXIS and QUIPS tools were used for GRADE quality assessment. The review was carried out using PRIMSA guidelines and registered in PROSPERO (ID: CRD42022313240).ResultsFour hundred studies were screened and 28 studies with 5752 participants were included. 28 published studies (24 cross-sectional and 4 longitudinal) were identified. Key results supported the significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength at 180°/s in elderly and athletic populations with a correlation coefficient of 0.245 (95%CI: 0.078–0.398, p = 0.004). However, no significant correlation was found with isometric quadriceps strength or isokinetic strength at 60°/s (r = 0.190, p = 0.085). There was only a weak negative correlation with MVC.ConclusionThis review found a statistically significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength. This has important clinical implications, especially in the elderly cohort, with higher 25(OH)D levels being associated with a reduced incidence of falls and fragility fractures.

Association of the COVID-19 Pandemic With Outcomes After Anterior Cruciate Ligament Reconstruction: A Retrospective Comparative Study Examining Changes in Health Care Access, Delivery, and Functional Outcomes.

Structured rehabilitation optimizes outcomes and reduces reinjury risk after anterior cruciate ligament reconstruction (ACLR). The coronavirus 2019 (COVID-19) pandemic interrupted standard rehabilitation, possibly affecting ACLR outcomes. To characterize changes to ACLR functional outcomes related to the COVID-19 pandemic. Cohort study; Level of evidence, 3. Patients who underwent ACLR between June 11, 2019, and March 11, 2020, (postpandemic group) were compared retrospectively with those who underwent ACLR the year before (June 11, 2018, to March 11, 2019). A mixed-effects linear regression model was used to estimate group differences in isokinetic quadriceps testing. A Kaplan-Meier analysis assessed the probability of achieving >90% limb symmetry index (LSI) for isokinetic quadriceps strength at 60 deg/s and passing all return-to-sport functional outcomes at 1 year postoperatively. A total of 176 patients (80 in the control group and 96 in the postpandemic group) were included. The rate of achieving >90% LSI in isokinetic strength at 60 deg/s at 1 year postoperatively was 39% (95% CI, 27%-49%) for the control group versus 22% (95% CI, 13%-30%) for the postpandemic group (P = .01). Similarly, the rate of achieving >90% LSI in all functional tests at 1 year postoperatively was 15% (95% CI, 7%-22%) for the control group versus 7% (95% CI, 2%-12%) for the postpandemic group (P = .04). The number of in-person physical therapy visits per patient was 25.8 ± 6.8 in the control group versus 24.4 ± 7.5 in the postpandemic group (P = .23). Only the postpandemic group accessed physical therapy using remote telemedicine. Each additional telehealth rehabilitation visit was associated with a 1-week delay in achieving >90% LSI in isokinetic quadriceps strength for the postpandemic group. The COVID-19 pandemic was associated with a decrease in lower extremity strength and a lower probability of achieving limb symmetry and passing the criteria for return to sport at 1 year postoperatively. These results were not due to lack of access to physical therapy.

The point prevalence of South African male soccer players' injuries in the Gauteng province.

The ever-evolving game of soccer is a complex physical contact team sport, exposing its participants to injury. To identify the point prevalence of soccer injuries among young amateur, semi-professional, and professional South African male soccer players. The participation of male amateur (n=54), semiprofessional (n=34), and professional (n=57) players provided a cross-sectional overview of the nature of the most predominant types and anatomical sites of injuries affecting soccer players (average age 23.9±4.7 years). All participants completed the Fuller soccer injury questionnaire, ISAK somatotype profiling and knee flexion/extension isokinetic concentric peak torque (Nm) evaluations at 60°/s. Fifty per cent of the players sustained soccer injuries (X 2=0.9). Knee (20%) and ankle (19%) were the most vulnerable sites (X 2=0.00001). Knee-injured players' right quadriceps torque (199±37 vs 223±38 Nm) and percentage right quadriceps torque relative to body mass (286±54 vs 311 ±39%) was significantly weaker than the non-injured players (p<0.01). The injured players' right hamstrings/quadriceps (H/Q) torque ratio further significantly differed from the non-injured players' H/Q torque ratios (79±17 vs 70±9%) (p<0.01). Male soccer players experience neuromusculoskeletal injuries, with their knees and ankles being the most vulnerable. Knee-injured players had weaker quadriceps isokinetic strength than non-injured players.

Assessing the Relationship of Psychological Sport Readiness, Single-leg Vertical Jump, and Non-Sagittal Single-Leg Hops to Quadriceps Strength After Anterior Cruciate Ligament Reconstruction.

Limitations exist with current ACLR functional testing assessments that may be mitigated by including single-leg multi-directional testing. To compare Anterior Cruciate Ligament-Return to Sport after Injury Scale (ACL-RSI) scores, limb symmetry index (LSI) of the single-leg vertical jump (SLVJ), single-leg medial rotation hop (SLMRH), single-leg lateral hop (SLLH), and isokinetic quadriceps strength between participants with an ACLR and healthy controls and assess predictors of quadriceps strength asymmetry. It was hypothesized that ACL-RSI scores and LSIs for all tests would differ between ACLR and healthy control groups and within the ACLR group a strong correlation would exist between all outcome measures and quadriceps strength. Cross-Sectional Study. Twenty-six participants with an ACLR (median 13 months after surgery) and twenty-six matched healthy controls were recruited to participate in this study. Performance was assessed via SLVJ, SLMRH, SLLH, and isokinetic quadriceps strength. Between-group comparisons were made with independent t-tests and Mann-Whitney U test. Within the ACLR group, bivariate correlation and multivariate regression analysis were performed to assess the relationship between the outcome measures and quadriceps strength asymmetry. Significant between-limb differences were only identified in the ACLR group (p< 0.05): SLVJ LSI: 88.5%, SLMRH LSI: 93.6%, SLLH LSI: 92.7%, quadriceps strength LSI 80.9% - 83.9%, which were significantly lower (p <0.05) than the healthy control group. Within the ACLR group, a moderate-strong significant (p < 0.05) correlations existed with quadriceps strength and SLVJ (r=0.44-0.65), SLMRH (r =0.43-0.83), and SLLH (r=0.54-0.63); while ACL-RSI had a weak non-significant (p > 0.05) correlation with quadriceps strength (r= 0.12-0.30). Single-leg multidirectional test LSIs were less in ACLR participants than matched healthy controls and all were directly related to quadriceps strength. Psychological readiness to return to sport was not related to quadriceps strength.

Poster 321: Predictive Value of Functional Assessments During Perioperative Rehabilitation in Anterior Cruciate Ligament Reconstruction (ACLR)

Objectives: Perioperative rehabilitation is critical to restoring function and preventing reinjury in ACLR patients. Single-leg hop and isokinetic strength testing are commonly utilized by clinicians to assess patient progress. The impact of early stage progress on later stage outcomes is, however, not well understood. This study aimed to identify the effects of early postoperative isokinetic quadriceps strength and single-leg hop performance on functional recovery after primary ACLR, to determine the manner in which changes in these parameters during perioperative rehabilitation relate to fast and successful functional recovery. Methods: Patients having a primary ACLR were consented into a long-term study and were retrospectively reviewed with the following inclusion criteria: ACLR using a contralateral patellar tendon graft with normal extension ROM and stability at 2 months postoperative, per the International Knee Documentation Committee (IKDC) objective form. Patients were excluded with a preoperative modified Tegner level &lt;7. Predictor variables included 180°/second isokinetic quadriceps strength test (preoperative, 2 months, 4 months) and single leg hop for distance (preoperative and 4 months). Strength was assessed using limb symmetry index (LSI) with the ACLR knee strength being divided by the graft donor knee strength, percent of preoperative normal, and percent change over time at each interval, while hop testing was normalized to height. Outcome variables assessed were return to sport (RTS) time in months, return to preoperative modified Tegner level in the first 12 months after surgery (yes/no), and Cincinnati Knee Rating System (CKRS) at 12 months postoperative. Stepwise multiple regression analysis was used to predict RTS time, return to preoperative modified Tegner level, and CKRS based on demographics and objective measures. Results: A total of 1093 patients were eligible for analysis and 607 were used for the RTS model, 724 for the return to preinjury Tegner level model, and 705 for the CKRS model. Mean age for the cohort was 19.6 ± 5.5 years (range, 11.9-39.7) and 52.1% were male. In the model predicting RTS time, the following variables reduced RTS time: female sex, younger age, higher preoperative LSI, higher ACLR knee strength gains from preoperative to 2 month, and higher normalized single leg hop distance. In the model predicting a return to preoperative Tegner level, the following variables increased the likelihood: younger age, lower preoperative Tegner level, lower strength deficits with LSI at 2 months, and higher normalized single leg hop distance. In the model predicting CKRS scores, the following variables increased the score: younger age and higher normalized single leg hop distance. Model statistics can be seen in Table 1. Conclusions: The study found several early rehabilitation performance measures significantly influenced key outcomes. Perioperative rehabilitation should promote early relative gains in quadriceps strength for the ACLR knee, maintaining limb symmTaetry, and maximizing single leg hop distance to encourage faster RTS, higher subjective scores, and improve the likelihood of patients returning to preoperative activity levels. By quantifying the importance and predictiveness of these rehabilitation performance metrics, clinicians may improve their protocols to promote superior outcomes following ACLR.

Poster 342: Return to Sport Rates and Objective Measures after ACL Reconstruction for High Level Basketball Players

Objectives: Return to sports (RTS) decisions for high-level basketball players after an anterior cruciate ligament reconstruction (ACLR) are multifactorial. The literature focuses mainly on sports performance metrics and lacks objective rehabilitation measures. The purpose of this study was to determine objective measure differences following an ACLR between basketball players competing at the college/professional, high school, and recreational levels. Our hypothesis was that basketball players competing at the college/professional level would have superior performance with objective measures following an ACLR, compared to those competing at the high school and recreational levels. Methods: Patients were retrospectively selected based on the following inclusion criteria: ACLR with a contralateral patellar tendon graft (PTG), preoperative activity level of ≥8 on the modified Tegner activity rating scale, ≤25 years old, and reported playing basketball. Exclusions included: revisions, bilateral procedures, or were missing data needed for analysis. Patients were split based on their preoperative activity level (level 8 = recreational, level 9 = high school, level 10 = college/professional). Each patient received a mini open, contralateral PTG utilizing the same surgical methods and followed the same accelerated rehabilitation approach. Postoperative outcome measures included the difference in extension range of motion (ROM) at 2 weeks, difference in flexion ROM at 3 months, percent deficit in isokinetic quadriceps strength and single leg hop for distance at 4 months, and the manual maximum difference on the KT arthrometer at 2 months. Statistical analysis included chi-square and analysis of variance where appropriate. Results: Of the 329 patients, 69 were level 8, 224 were level 9, and 36 were level 10 with mean ages of 19.6, 16.4, and 19.1 years, respectively. The percent of males differed by group with level 8 at 78.3%, level 9 at 29.5%, and level 10 at 27.8% (p &lt; 0.001). The overall rate of return to competitive basketball for the cohort was 96.0%. The rate of return to competitive basketball was not statistically significantly different among the groups with level 10 having the highest rate (97.2%), followed by level 9 (96.4%) and then level 8 (94.2%), p = 0.659. Level 10 athletes had the lowest strength deficit with a mean of 9.3%, compared to 12.5% for level 9, and 15.6% for level 8, p=0.017. Single leg hop deficit was also different among groups with level 10 at 6.9%, level 9 at 6.2%, and level 8 at 10.4%, p &lt; 0.001. Knee ROM and stability were not statistically different among the groups. Conclusions: The rate of return to competitive basketball is the same among all high-level basketball players. Objectively, level 10 athletes had superior strength and single leg hop performance compared to recreational basketball players. Although the return to competitive basketball rate is the same among all groups, recreational basketball players tend to be weaker than college/professional players, therefore, added emphasis on this aspect of their rehabilitation would be beneficial for this population.

Reliability and Validity of Temporal Parameters during the Side Hop Test in Patients after Anterior Cruciate Ligament Reconstruction.

Background: The side hop test (SHT) measures the number of jumps performed over 30 s. Although this measure has demonstrated its value in clinical practice, the temporal parameters of the SHT allow for a deeper analysis of the execution strategy. The aim of this study is to assess the reliability and construct validity of contact time parameters during the SHT recorded by a video analysis system in anterior cruciate ligament reconstructed (ACLR) patients. Methods: We investigated the reliability (intra-rater, standard error of measurement (SEM), and minimum detectable change (MDC)), discriminant validity (operated (OP) versus non-operated (NOP) side), and convergent validity (relationship with strength and psychological readiness) of SHT contact time parameters, number of valid hops and limb symmetry index (LSI) in 38 ACLR patients. Contact time parameters are presented as mean, standard deviation (SD), and coefficient of variation (CV) of contact time. Results: Intra-tester reliability was good to excellent for all contact time parameters. For discriminant validity, the mean and SD contact times of the OP leg were significantly longer than those of the NOP leg, although the difference was smaller than the SEM and MDC values. The number of valid jumps and CV contact time parameters were not significantly different. Isokinetic quadriceps strength (60°/s) was strongly correlated with mean contact time for both legs. However, psychological readiness was not correlated with any of the contact time parameters. Conclusions: Temporal parameters of the SHT measured on video analysis are valid and reliable parameters to assess the performance strategy of the SHT. The results should be interpreted with caution regarding the SEM and MDC values. Further studies are needed to measure criterion validity, inter-rater reliability, and responsiveness.

Effect of open vs. closed kinetic chain exercises in ACL rehabilitation on knee joint pain, laxity, extensor muscles strength, and function: a systematic review with meta-analysis.

PROSPERO [CRD42023475230].

Does It Matter? Isometric or Isokinetic Assessment of Quadriceps Strength Symmetry 9 Months After ACLR in Collegiate Athletes.

Greater quadriceps strength symmetry is associated with better outcomes after anterior cruciate ligament reconstruction (ACLR). Isometric and isokinetic assessments of quadriceps strength inform therapeutic exercise prescription and return-to-sport decisions. It is unclear whether isometric and isokinetic measures provide similar information post-ACLR. Quadriceps strength symmetry is similar between isometric and isokinetic assessments. Isokinetic and isometric strength symmetries have similar associations to functional knee kinetics and self-reported knee function. Cross-sectional study. Level 3. NCAA Division I athletes (N = 35), 8.9 ± 2.5 months post-ACLR completed isometric and isokinetic quadriceps strength assessments, countermovement jumps (CMJs), and treadmill running. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC). Agreement between isometric and isokinetic strength symmetry was assessed using Bland-Altman analysis, with associations to functional knee kinetics and IKDC assessed using Pearson correlations and linear regressions. Mean difference in quadriceps strength symmetry between isokinetic and isometric assessments was 1.0% (95% limits of agreement of -25.1% to 23.0%). Functional knee kinetics during running and CMJ were moderately to strongly associated with isometric strength symmetry (r = 0.64-0.80, P < 0.01) and moderately associated with isokinetic strength symmetry (r = 0.41-0.58, P < 0.01). IKDC scores were weakly to moderately associated with isometric (r = 0.39, P = 0.02) and isokinetic (r = 0.49, P < 0.01) strength symmetry. Isokinetic and isometric assessments of quadriceps strength symmetry in collegiate athletes 9 months post-ACLR demonstrated strong agreement. Quadriceps strength symmetry is associated with functional knee kinetic symmetry post-ACLR. Considerable individual variation suggests mode of contraction should be consistent throughout postoperative assessment. Isometric strength symmetry may be a better indicator of functional knee kinetic symmetry, while isokinetic strength symmetry may be associated more closely with patient-reported outcomes.

No Association Between Injury-Related Fear and Isokinetic Quadriceps Strength in Individuals With a History of Anterior Cruciate Ligament Reconstruction.

Injury-related fear and quadriceps strength are independently associated with secondary anterior cruciate ligament (ACL) injury risk. It is not known whether injury-related fear and quadriceps strength are associated, despite their individual predictive capabilities of secondary ACL injury. The purpose of this study was to examine the association between injury-related fear and quadriceps strength in individuals at least 1year after ACL reconstruction (ACLR). Cross-sectional study. Forty participants between the ages of 18 and 35years at least 1year post unilateral primary ACLR. Participants completed the Tampa Scale of Kinesiophobia-11 (TSK-11) and a standard isokinetic quadriceps strength assessment using the Biodex Isokinetic Dynamometer. Pearson Product-Moment correlations were used to examine the linear association between the TSK-11 scores and peak torque (in nanometers per kilogram) for each limb and between the TSK-11 scores and limb symmetry indices for each limb. Pearson Product-Moment correlation coefficients (r) were interpreted as very high (.90-1.00), high (.70-.90), moderate (.50-.70), low (.30-.50), and no correlation (.00-.30). The average TSK-11 score was 18.2 (5.3), average ACLR peak quadriceps torque was 1.9 (0.50)N·m/kg, average contralateral peak quadriceps torque was 2.3 (0.48)N·m/kg, and average limb symmetry index was 85.3% (12.6%). There was no statistically significant correlation between the TSK-11 and peak quadriceps torque on the ACLR limb (r = .12, P = .46), the TSK-11 and contralateral limb (r = .29, P = .07), or the TSK-11 and limb symmetry index (r = -.18, P = .27). There was no association between kinesiophobia and peak isokinetic quadriceps strength in individuals at least 1year post-ACLR. Both factors, independently, have been shown to influence risk of secondary injury in patients after ACLR.

Weaker Quadriceps Muscle Strength With a Quadriceps Tendon Graft Compared With a Patellar or Hamstring Tendon Graft at 7 Months After Anterior Cruciate Ligament Reconstruction

Background: Impaired quadriceps muscle strength after anterior cruciate ligament reconstruction (ACLR) is associated with worse clinical outcomes and a risk of reinjuries. Yet, we know little about quadriceps muscle strength in patients reconstructed with a quadriceps tendon (QT) graft, which is increasing in popularity worldwide. Purpose: To describe and compare isokinetic quadriceps strength in patients undergoing ACLR with a QT, hamstring tendon (HT), or bone–patellar tendon–bone (BPTB) autograft. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We included patients with QT grafts (n = 104) and matched them to patients with HT (n = 104) and BPTB (n = 104) grafts based on age, sex, and associated meniscal surgery. Data were collected through clinical strength testing at a mean of 7 ± 1 months postoperatively. Isokinetic strength was measured at 90 deg/s, and quadriceps strength was expressed as the limb symmetry index (LSI) for peak torque, total work, torque at 30° of knee flexion, and time to peak torque. Results: Patients with QT grafts had the most impaired isokinetic quadriceps strength, with the LSI ranging between 67.5% and 75.1%, followed by those with BPTB grafts (74.4%-81.5%) and HT grafts (84.0%-89.0%). Patients with QT grafts had a significantly lower LSI for all variables compared with patients with HT grafts (mean difference: peak torque: −17.4% [95% CI, −21.7 to −13.2], P < .001; total work: −15.9% [95% CI, −20.6 to −11.1], P < .001; torque at 30° of knee flexion: −8.8% [95% CI, −14.7 to −2.9], P = .001; time to peak torque: −17.7% [95% CI, −25.8 to −9.6], P < .001). Compared with patients with BPTB grafts, patients with QT grafts had a significantly lower LSI for all variables (mean difference: peak torque: −6.9% [95% CI, −11.2 to −2.7], P < .001; total work: −7.7% [95% CI, −12.4 to −2.9], P < .001; torque at 30° of knee flexion: −6.3% [95% CI, −12.2 to −0.5], P = .03; time to peak torque: −8.8% [95% CI, −16.9 to −0.7], P = .03). None of the graft groups reached a mean LSI of >90% for peak torque (QT: 67.5% [95% CI, 64.8-70.1]; HT: 84.9% [95% CI, 82.4-87.4]; BPTB: 74.4% [95% CI, 72.0-76.9]). Conclusion: At 7 months after ACLR, patients with QT grafts had significantly worse isokinetic quadriceps strength than patients with HT and BPTB grafts. None of the 3 graft groups reached a mean LSI of >90% in quadriceps strength.

Comparison of Isokinetic Strength Parameters of Quadriceps in Athletes and Non-Athletes

OBJECTIVE: To compare the quadriceps isokinetic strength parameters of athletes and non-athletes. METHODOLOGY: The cross-sectional study was conducted from July to December 2019 at the Pakistan Sports Board, Islamabad. The sample size was 81, selected through a non-probability convenience sampling technique and calculated by the Rao Soft tool. The 41 participants were in the athletes' group, and 40 were in the non-athletes' group. Individuals with a history of sprain, strain, or fracture in the lower limbs within the last six months were excluded. The self-structured questionnaire includes demographic data, waist-to-hip ratio, thigh circumference, peak torque values and agility t-test score. The isokinetic strength of the right lower limb (RLL) was measured via Biodex system Pro 3. Data was analyzed through SPSS 22, and an independent t-test was applied for analysis between groups. Pearson test was used for the correlation coefficient. RESULTS: Athletes had significantly higher quadriceps muscle strength than non-athletes (p&lt;0.001), indicating the positive impact of regular sports participation and physical training. Quadriceps peak torque positively correlated with thigh circumference (r=0.60, p&lt;0.001), consistent with previous studies. Surprisingly, athletes exhibited a weak to moderate negative correlation between quadriceps peak torque and agility (r=-0.35, p&lt;0.05), suggesting a potential trade-off between muscle mass and agility performance. Increased muscle bulk may compromise speed and flexibility. CONCLUSION: Athletes demonstrated superior quadriceps muscle strength, emphasizing the positive influence of sports involvement and physical training; thigh circumference positively correlated with Quadriceps peak torque, and Agility negatively correlated with quadriceps peak torque. KEYWORDS: Athletes and Non-athletes, Correlation, Isokinetic, Peak torque

Which Tests Predict 6-Month Isokinetic Quadriceps Strength After ACL Reconstruction? An Examination of Isometric Quadriceps Strength and Functional Tests at 3 Months.

Restoration of quadriceps strength after anterior ligament reconstruction (ACLR) is a persistent challenge for patients and clinicians. Inadequate recovery of quadriceps strength has been linked to increase risk of re-injury. Developing methods of early identification of strength deficits is essential to allow clinicians to provide more individualized interventions early in the rehabilitation process. To determine whether 3-month isometric quadriceps strength, the Y-Balance Test (YBT), and the anterior step-down test are predictive of isokinetic quadriceps strength at six months in adolescents after ACLR. Retrospective cohort. Thirty-six adolescent patients with primary ACLR (58% female, 36% with concomitant meniscal repair, age: 15.7 ± 1.6 years). At three months post-operative, isometric quadriceps strength via isokinetic dynamometer, YBT-Lower Quarter, and anterior step-down tests were completed. At six months post-operative, an isokinetic knee strength assessment was completed. Regression analysis was used to evaluate the predictive relationship between 3-month isometric tests and 6-month isokinetic knee extension tests. Three-month post operative isometric quadriceps peak torque predicted isokinetic quadriceps peak torque at 6 months, F(1,34) = 19.61, p <0.001. Three-month isometric quadriceps peak torque accounted for 36.6% of the variance in normalized isokinetic quadriceps peak torque at 6 months with adjusted R2 = 34.7%. Including YBT anterior reach (β = 0.157, p = 0.318) in regression added 1.9% of variance when predicting 6-month isokinetic quadriceps peak torque, F (2,33) = 10.32, p <0.001, R2 = 0.385, ΔR2 = 0.019. At three months post-ACLR, isometric strength testing appears more optimal than other functional tests in predicting isokinetic quadriceps peak torque in later stages of rehabilitation for adolescents. Clinicians should use tests at three months that measure quadriceps strength if aiming to predict isokinetic quadriceps peak torque at six months post-ACLR, rather than using functional tests such as the YBT-LQ or anterior step-down. Level 3.

Quadriceps strength, patellar tendon quality, relative load exposure, and knee symptoms in male athletes before the anterior cruciate ligament reconstruction.

Anterior cruciate ligament (ACL) injuries cause knee instability, knee pain, weight-bearing adjustments, and functional deficits but their association to patellar tendon quality is unknown. Our purpose was to investigate quadriceps strength, patellar tendon quality, relative load exposure, perceived knee stability, knee pain, extension angle, and time from ACL injury; in addition to examining their relative associations. Injured and uninjured legs of 81 male athletes of different sports with a unilateral ACL injury (18-45 years) were examined. Participants reported location and intensity of knee pain and their perceived stability using a numerical rating scale (NRS 0-10). Strength was tested with an isokinetic device. Tendon quality was measured using ultrasound tissue characterization. Means ± standard deviation (SD) of perceived knee stability, knee extension angle, knee pain, isokinetic quadriceps strength in relation to body mass, proportion of echo-types (I-IV), tendon volume, and number of days from ACL injury to assessment are reported. Values of effect sizes (ES) and correlations (rs) were calculated. ACL injured leg demonstrated reduced reported knee stability (6.3 ± 2.5), decreased knee extension angle (-0.7 ± 3.1° vs. -2.7 ± 2.2°; ES = 0.7; P < 0.001), greater knee pain (NRS 3.1 ± 2.2 vs. 0.0 ± 0.1; ES = 2.0; P < 0.001), and 22% lower quadriceps strength (228.0 ± 65.0 vs. 291.2 ± 52.9 Nm/kg: ES = 1.2; P < 0.001) as compared to the uninjured leg. However, patellar tendons in both legs displayed similar quality. Quadriceps strength was associated with stability (rs = -0.54; P < 0.001), pain (rs = -0.47; P < 0.001), extension angle (rs = -0.39; P < 0.001), and relative load exposure (rs = -0.34; P < 0.004). Echo-types distribution was beneficially associated with time from ACL injury (rs range: -0.20/ -0.32; P < 0.05). ACL injured athletes displayed knee pain, extension deficit, and weaker quadriceps in the injured leg. While there were no differences in patellar tendon quality between legs, longer time from ACL injury showed better tendon quality.

The effect of blood flow restriction in low-intensity load exercise on isokinetic strength of the quadriceps muscles in knee osteoarthritis

Link of Video Abstract: https://youtu.be/tduoO-xy3ZE Introduction: Cartilage destruction in knee osteoarthritis (KOA) caused the inflammation process. It makes the patient complain of knee pain, tends to immobilize, and induced neural inhibition (Arthrogenic muscle inhibition) on the quadriceps muscle as a knee stabilator and shock absorbent. These caused quadriceps weakness. The combination of blood flow restriction (BFR) and low-intensity resistance training (LIRT) showed an improvement in isotonic peak torque significantly, but the prescription is varied and limited in Indonesia. Patient and Methods: This was a clinical experimental study with randomized control trial with pre and post-test design. The subjects were 28 KOA patients (50-70 years old). The intervention group (n=14) received a combination of low-load resistance training (30% 1-RM; 75 repetitions) and BFR (50 mmHg). The control group (n=14) received low load resistance training only (30% 1-RM; 75 repetitions). Both groups received training 2 times per week with a Q-bench machine for 6 weeks. Isokinetic peak torque was assessed before and after the training program. Results: There was a significant improvement in isokinetic peak torque before and after the training program in both groups (intervention group p=0.001; control group p=0.000). There was a significant improvement of delta isokinetic peak torque between both groups (p=0.018) and post-test between both groups (p=0.044). The effect size value of the intervention group was 1.22 (very large) and the control group was 0.89 (large). Conclusions: The addition of BFR on LIRT for 6 weeks can improve isokinetic quadriceps strength in patients with knee osteoarthritis

Force plate jump testing metrics are predictive of performance on a multimodal return to sport testing protocol among anterior cruciate ligament reconstruction patients at minimum six-month follow-up.

Force plate-based jump testing may serve as a potential alternative to traditional return to sport (RTS) testing batteries. The purpose of our study was to identify force plate jump metrics that were predictive of RTS test findings in patients who were at least six months postoperative following anterior cruciate ligament reconstruction (ACLR). We conducted a cross-sectional study of patients who underwent ACLR at our center and were at least six months postoperative. Subjects completed a multimodal Institutional RTS (IRTS) testing battery which included range of motion (ROM) testing and isokinetic quadriceps strength testing. Subjects also completed a countermovement jump testing protocol on a commercially-available force plate. Jump metrics predictive of IRTS test findings were identified using multivariable linear and logistic regression with stepwise selection. Model significance was assessed at α=0.002. Sixteen patients (7M, 9F) were enrolled in our study with median age of 29 years (range 20-47). Relative concentric impulse was positively predictive of knee flexion active ROM (β=7.07, P=0.01) and passive ROM (β=9.79, P=0.003). Maximum power was positively predictive of quadriceps strength at 60 deg/s (β=3.27, P<0.001) and 180 deg/s (β=2.46, P<0.001). Center-of-pressure (COP) shift acceleration along the force plate X-axis was negatively predictive of Bunkie lateral test score (β=-945, P<0.001) and medial test score (β=-839, P=0.03). Force plate-derived vertical jump testing metrics are predictive of certain components of a multimodal RTS physical assessment for ACLR patients, including knee flexion ROM, quadriceps strength on isokinetic testing, and Bunkie Test performance.

Poster 346: Revision Anterior Cruciate Ligament Reconstruction with an All-Soft Tissue Quadriceps Tendon Autograft Produces Similar Outcomes to Index Surgery

Objectives: Anterior cruciate ligament reconstruction (ACLR) using all-soft tissue quadriceps tendon (QT) autograft has not yet been studied as a viable revision option in the pediatric population. This study aimed to compare short- to mid-term outcomes between patients undergoing revision ACLR and primary ACLR using all-soft tissue QT autograft. Methods: A retrospective review of prospectively collected data included patients aged 8-18 years old who underwent revision ACLR using an all-soft tissue QT autograft over a ten-year period (2011-2021). One-to-two matching by age and gender was performed to select a control group of patients who underwent primary ACLR utilizing all-soft tissue QT autograft during the same period. All procedures were performed by a single surgeon using a minimally invasive graft harvest technique and suspensory fixation. Subjective assessment of knee function was obtained pre- and postoperatively with the International Knee Documentation Committee (IKDC) survey. Postoperative knee laxity was measured with a KT1000 arthrometer at 6 weeks, 3 months, and 6 months. Isokinetic quadriceps strength at 60° and 180° was collected at 6 months and 12 months. Complications, including hematomas, infections, graft failures, and the need for subsequent surgery were recorded. To determine clinical significance ( p≤0.05), outcomes were compared using two-sided Student t-tests and Pearson’s chi-squared tests. Results: Thirty-nine patients underwent revision ALCR (59% female; 15.67±1.6 years old; BMI 23.7±4.6) and 78 underwent primary ACLR (59% female; 15.73±1.46 years old; BMI 23.5±3.9) with all-soft tissue QT autograft ( p=1.00 for gender; p=0.83 for age; p=0.82 for BMI). Length of follow up was 20.9 months (revision) and 23.4 months (primary) ( p=0.543). Mean IKDC scores improved significantly in both groups (Revision: 59.17±16.4 vs. 85.87±10.57, p&lt;0.001; Index: 55.85±16.8 vs. 88.38±14.2 p&lt;0.001). Mean time to postoperative IKDC for revision and primary ACLR was 14.67±5.7 months and 15.22±6.5 months, respectively ( p=0.865). There were no significant differences in mean pre- or postoperative IKDC scores between the index and revision groups (Table 1, p&gt;0.05). However, postoperative knee laxity was significantly greater after revision surgery at 6 weeks ( p=0.006) and 6 months ( p=0.009) (Table1). Contrarily, patients undergoing primary surgery had a greater isokinetic quadriceps strength deficit during both time points at 60° and 180°, which was statistically significant at full extension at 12 months postoperatively ( p&lt;0.039) (Table 1). Finally, although patients undergoing revision surgery exhibited fewer complications, this difference was not statistically significant (Table 2). Conclusions: Patient reported outcomes after ACLR revision surgery using all-soft tissue QT autograft in the paediatric population is equivocal to those undergoing primary reconstruction. Despite minor differences in the progression of postoperative isokinetic strength and knee laxity, a history of previously failed ACLR does not seem to portend inferior outcomes or increased risk for complications in pediatric patients undergoing revision surgery with all-soft tissue QT autograft. [Table: see text][Table: see text]

Poster 293: Relationship between patellar tendon length and surgical treatment for patellar tendinosis

Objectives: Patellar tendinitis is a relatively common overuse injury that typically resolves with rehabilitation alone, however if it progresses to recalcitrant patellar tendinosis (RPT), surgical intervention is typically recommended. Patella alta, which has commonly been shown to lead to patellar dislocations, has recently shown to be related to patellar tendinitis. However, the relationship between patella alta and patellar tendinosis severe enough to warrant surgical intervention is unknown. The purpose of this study was to determine the association between patellar tendon length and surgical treatment for RPT. Methods: A cohort of 45 patients who were scheduled for surgery due to RPT, planning to receive a partial patellar tendinectomy, were retrospectively reviewed. A group of patients consented into a different study, planning to have an anterior cruciate ligament reconstruction (ACLR), were used as a control group. Exclusion criteria for the control group included previous patellar tendinosis. For both groups, the patellar tendon was measured preoperatively on a lateral radiograph with the knee in 60° of flexion, from the distal aspect of the inferior pole of the patella to the insertion site on the tibial tubercle. Other variables assessed were primary sport played and preoperative noninvolved quadriceps strength, measured isokinetically and normalized to body weight. The RPT patients were matched to the ACLR patients based on sex, height, and weight, leaving 45 patients in each group. Results: Mean age for the ACLR group was 26.0 ± 10.6 years and 25.1 ± 10.6 years for the RPT group. The groups had similar mean height (ACLR 70.2”, RPT 70.9”) and weight (ACLR 183.0 lbs, RPT 179.0 lbs), along with identical sex distribution with both having 71% males. Patients in the RPT group had statistically significantly longer patellar tendon lengths at 57.6 ± 7.4 mm compared to the ACLR group at 46.1 ± 7.5 mm, p&lt;.001. The most frequent sports played for those in the RPT group were basketball (38%) and volleyball (22%); whereas for the ACLR group, it was basketball (22%) and football (20%). Those in the RPT group were not found to have a statistically significantly higher distribution of any individual sport played, however when the jumping sports of basketball and volleyball were combined, the RPT group showed a statistically significantly higher distribution of patients playing these sports compared to the ACLR group (60% vs 31%, p=.006). Isokinetic quadriceps strength failed to show a statistically significant difference between groups, p=.358. Conclusions: After taking into account sex, height, and weight, patients scheduled for surgery due to RPT had longer patellar tendons compared to those without a history of patellar tendinosis. Patients with RPT are also more likely to play jumping sports compared to those who sustained an ACL tear. Those with longer than normal patellar tendons who are diagnosed with patellar tendinitis, before it progresses to RPT, should consider rehabilitation and tailor their workload to avoid symptom progression and ultimately surgery.

Interlimb Asymmetry in Knee Extension Moment During Double-Leg Squatting Is Associated With Persistent Quadriceps Weakness After ACL Reconstruction

Background: Although double-leg squatting is less dynamic and places less demand on the quadriceps compared with landing tasks, the relationship between double-leg squatting biomechanics and persistent quadriceps weakness after anterior cruciate ligament reconstruction (ACLR) is unknown. Purpose: To clarify the relationships between asymmetries in quadriceps strength and lower limb biomechanics during double-leg squatting &gt;1 year after ACLR. Study Design: Controlled laboratory study. Methods: A total of 26 participants (5.5 ± 3.8 years after ACLR) were enrolled. The limb symmetry index (LSI) of isokinetic quadriceps strength was used to divide participants into the high-quadriceps (HQ) group (LSI ≥90%; n = 18) and the low-quadriceps (LQ) group (LSI &lt;90%; n = 8). The knee, hip, and ankle extension moment (relative to body weight and support moment [sum of knee, hip, and ankle moments]) and vertical ground-reaction force during double-leg squatting were analyzed using 3-dimensional motion analysis. The association of quadriceps strength and biomechanical variables was tested using 2-way analysis of variance and univariate regression analysis. Results: A significant group-by-limb interaction was found for the peak knee extension moment and the ratios of knee and hip extension moment to support moment ( P &lt; .001, P = .015 and P &lt; .001, respectively). The LQ group showed a significantly smaller peak knee extension moment and knee to support moment ratio but a larger hip to support moment ratio in the involved limb than in the uninvolved limb (95% CIs: knee extension moment, −0.273 to −0.088 N·m/kg; knee to support moment ratio, −10.7% to −2.2%; hip to support moment ratio, 3.2% to 8.5%). No interlimb difference was found for the HQ group. The LSI of quadriceps strength was significantly associated with the LSI of peak knee extension moment ( R 2 = 0.183), knee to support moment ratio ( R 2 = 0.256), and hip to support moment ratio ( R 2 = 0.233). The mean maximum isokinetic quadriceps strength and peak knee extension moment during squatting on the involved limb of the LQ group were 2.40 ± 0.39 and 0.90 ± 0.16 N·m/kg, respectively. Conclusion: Asymmetrical biomechanics during double-leg squatting was associated with persistent quadriceps weakness after ACLR. The LQ group had reduced knee extensor moment on the involved side during squatting despite loading at approximately half the maximum strength. Clinical Relevance: Quadriceps strengthening exercises, together with interventions to improve neuromuscular control, may reduce asymmetrical biomechanics during double-leg squatting.