Exploring the associations between skeletal muscle echogenicity and physical function in aging adults: A systematic review with meta-analyses.

BACKGROUND: Assessment and quantification of skeletal muscle within the aging population is vital for diagnosis, treatment, and injury/disease prevention. The clinical availability of assessing muscle quality through diagnostic ultrasound presents an opportunity to be utilized as a screening tool for function-limiting diseases. However, relationships between muscle echogenicity and clinical functional assessments require authoritative analysis. Thus, we aimed to (a) synthesize the literature to assess the relationships between skeletal muscle echogenicity and physical function in older adults (≥60 years), (b) perform pooled analyses of relationships between skeletal muscle echogenicity and physical function, and (c) perform sub-analyses to determine between-muscle relationships. METHODS: CINAHL, Embase, MEDLINE, PubMed, and Web of Science databases were systematically searched to identify articles relating skeletal muscle echogenicity to physical function in older adults. Risk-of-bias assessments were conducted along with funnel plot examination. Meta-analyses with and without sub-analyses for individual muscles were performed utilizing Fisher's Z transformation for the most common measures of physical function. Fisher's Z was back-transformed to Pearson's r for interpretation. RESULTS: Fifty-one articles (n = 5095, female = ∼2759, male = ∼2301, 72.5 ± 5.8 years, mean ± SD (1 study did not provide sex descriptors)) were extracted for review, with previously unpublished data obtained from the authors of 13 studies. The rectus femoris (n = 34) and isometric knee extension strength (n = 22) were the most accessed muscle and physical qualities, respectively. The relationship between quadriceps echogenicity and knee extensor strength was moderate (n = 2924, r = -0.36 (95% confidence interval: -0.38 to -0.32), p < 0.001), with all other meta-analyses (grip strength, walking speed, sit-to-stand, timed up-and-go) resulting in slightly weaker correlations (r:  -0.34 to -0.23, all p < 0.001). Sub-analyses determined minimal differences in predictive ability between muscle groups, although combining muscles (e.g., rectus femoris + vastus lateralis) often resulted in stronger correlations with maximal strength. CONCLUSION: While correlations were modest, the affordable, portable, and noninvasive ultrasonic assessment of muscle quality was a consistent predictor of physical function in older adults. Minimal between-muscle differences suggest that echogenicity estimates of muscle quality are systemic. Therefore, practitioners may be able to scan a single muscle to estimate full-body skeletal muscle quality/composition, while researchers should consider combining multiple muscles to strengthen the model.

Time to Reflect on Return to Sport Timing Following ACL Reconstruction.

The time of return to sport following anterior cruciate ligament (ACL) reconstruction is a commonly discussed topic within clinical settings and the sports medicine literature. Emerging science has demonstrated protective effects of delaying the time of sport clearance on athlete reinjury. Though a single time cutoff is unlikely to be applicable for all athletes, large inconsistencies in the time of return to sport clearance are present in both the literature and within prescribed clinical protocols. A multitude of patient factors, such as perceived function, objective function, confidence, post-operative goals, among others, are vital for how athletes are progressed and released for sport participation. This Current Opinion article is constructed to discuss the time to return to sport after ACL reconstruction-factors that may influence timing decisions, how time is assessed within the scientific literature-and to promote discussion on this common topic within the sports medicine and athletic communities. The aim of the article is not to establish defined clinical time cutoffs for this population.

Influence of interim functional assessments on patient outcomes at the time of return to activity following ACL-reconstruction.

OBJECTIVE: To compare patient outcomes at the time of the return to activity (RTA) progression between those with a prior interim assessment and those without. DESIGN: Retrospective, Cohort Study. SETTING: Controlled Laboratory. PARTICIPANTS: Patients following Anterior Cruciate Ligament Reconstruction (ACLR) were recruited through an ongoing RTA assessment program. Patients were stratified into two testing groups = "Single RTA test": only assessment between 6 and 9 months post-ACLR and "Repeat RTA test": prior assessment performed >2-months before their RTA assessment. Patients were matched based on time post-surgery, age, activity level, and graft type. MAIN OUTCOME MEASURE: Self-reported knee function and isokinetic knee flexor and extensor strength/symmetry were compared between groups. RESULTS: 392 patients were identified. Once matched, 138 patients (21.1 ± 7.0 years, 7.3 ±0 .9 mo post-ACLR) were analyzed. Repeat RTA test patients demonstrated higher measures of self-reported knee function (P = .04) and greater knee flexion strength (P = .006) and symmetry (P = .05). CONCLUSION: Patients with interim functional assessments reported greater self-reported knee function and higher hamstring strength at the time of RTA compared to patients that completed their only assessment within this time point. Early functional assessments may identify individualized deficits that can be addressed while patients are under supervision of rehabilitation specialists.

Predicting Anterior Cruciate Ligament Reinjury From Return-to-Activity Assessments at 6 Months Postsurgery: A Prospective Cohort Study.

CONTEXT: Return-to-activity (RTA) assessments are commonly administered after anterior cruciate ligament reconstruction (ACLR) to manage the patient's postoperative progressions back to activity. To date, few data are available on the clinical utility of these assessments to predict patient outcomes such as secondary anterior cruciate ligament (ACL) injury once the athlete has returned to activity. OBJECTIVE: To identify the measures of patient function at 6 months post-ACLR that best predict RTA and second ACL injury at a minimum of 2 years after ACLR. DESIGN: Prospective cohort study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 234 patients with primary, unilateral ACLR completed functional assessments at approximately 6 months post-ACLR. Of these, 192 (82.1%) completed follow-up at ≥2 years post-ACLR. MAIN OUTCOME MEASURE(S): The 6-month functional assessments consisted of patient-reported outcomes, isokinetic knee-flexor and -extensor strength, and single-legged hopping. We collected RTA and secondary ACL injury data at ≥2 years after ACLR. RESULTS: Of the patients who were able to RTA (n = 155), 44 (28.4%) had a subsequent ACL injury, 24 (15.5%) to the ipsilateral graft ACL and 20 (12.9%) to the contralateral ACL. A greater proportion of females had a secondary injury to the contralateral ACL (15/24, 62.5%), whereas a greater proportion of males reinjured the ipsilateral ACL graft (15/20, 75.0%; P = .017). Greater knee-extension symmetry at 6 months increased the probability of reinjury (B = 0.016, P = .048). Among patients with RTA at <8 months, every 1% increase in quadriceps strength symmetry at 6 months increased the risk of reinjury by 2.1% (B = 0.021, P = .05). Among patients with RTA at >8 months, every month that RTA was delayed reduced the risk of reinjury by 28.4% (B = -0.284, P = .042). Descriptive statistics of patient function stratified between the early and delayed RTA groups can be found in the Supplemental Table (available online at http://dx.doi.org/10.4085/1062-6050-0407.20.S1). CONCLUSIONS: Patients with more symmetric quadriceps strength at 6 months post-ACLR were more likely to experience another ACL rupture, especially those who returned to sport at <8 months after the index surgery. Clinicians should be cognizant that returning high-functioning patients to activity at <8 months post-ACLR may place them at an increased risk for reinjury.

Utilization of Mid-Thigh Magnetic Resonance Imaging to Predict Lean Body Mass and Knee Extensor Strength in Obese Adults.

Purpose: To train and test a machine learning model to automatically measure mid-thigh muscle cross-sectional area (CSA) to provide rapid estimation of appendicular lean mass (ALM) and predict knee extensor torque of obese adults. Methods: Obese adults [body mass index (BMI) = 30-40 kg/m2, age = 30-50 years] were enrolled for this study. Participants received full-body dual-energy X-ray absorptiometry (DXA), mid-thigh MRI, and completed knee extensor and flexor torque assessments via isokinetic dynamometer. Manual segmentation of mid-thigh CSA was completed for all MRI scans. A convolutional neural network (CNN) was created based on the manual segmentation to develop automated quantification of mid-thigh CSA. Relationships were established between the automated CNN values to the manual CSA segmentation, ALM via DXA, knee extensor, and flexor torque. Results: A total of 47 obese patients were enrolled in this study. Agreement between the CNN-automated measures and manual segmentation of mid-thigh CSA was high (>0.90). Automated measures of mid-thigh CSA were strongly related to the leg lean mass (r = 0.86, p < 0.001) and ALM (r = 0.87, p < 0.001). Additionally, mid-thigh CSA was strongly related to knee extensor strength (r = 0.76, p < 0.001) and moderately related to knee flexor strength (r = 0.48, p = 0.002). Conclusion: CNN-measured mid-thigh CSA was accurate compared to the manual segmented values from the mid-thigh. These values were strongly predictive of clinical measures of ALM and knee extensor torque. Mid-thigh MRI may be utilized to accurately estimate clinical measures of lean mass and function in obese adults.

Effect of Meniscal Treatment on Functional Outcomes 6 Months After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Meniscal injuries are commonly associated with anterior cruciate ligament (ACL) tears. Treatment of meniscal injuries can impart delayed weightbearing and range of motion restrictions, which can affect the rehabilitation protocol. The effect of meniscal treatment and subsequent restrictions on strength recovery after ACL reconstruction is unclear. PURPOSE/HYPOTHESIS: The purpose of this study was to compare strength, jumping performance, and patient-reported outcomes between patients who underwent isolated ACL reconstruction (ACLR) and those who underwent surgical intervention for meniscal pathology at the time of ACLR. Our hypothesis was that patients who underwent concurrent meniscal repair (MR) would have lower strength recovery owing to postoperative restrictions. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients with ACLR were stratified into isolated ACLR, ACLR and meniscectomy (ACLR-MS), or ACLR-MR groups and were compared with healthy controls. The ACLR-MR group was restricted to partial weightbearing and to 90° of knee flexion for the first 6 weeks postoperatively. All participants completed patient-reported outcomes (International Knee Documentation Committee [IKDC] and Knee injury and Osteoarthritis Outcome Score [KOOS]) and underwent bilateral isokinetic and isometric strength tests of the knee extensor and flexor groups as part of a return-to-sports test battery at 5 to 7 months postoperatively. RESULTS: A total of 165 patients with ACLR (50 with isolated ACLR, 44 with ACLR-MS, and 71 with ACLR-MR) and 140 healthy controls were included in the study. Follow-up occurred at a mean of 5.96 ± 0.47 months postoperatively. The control group demonstrated higher subjective knee function, unilateral peak extensor torque, and limb symmetry than did the ACLR-MS and ACLR-MR groups combined (P < .001 for all). There were no differences in IKDC, KOOS subscales, or unilateral or limb symmetry measures of peak knee extensor or flexor torque among the isolated ACLR, ACLR-MS, and ACLR-MR groups. CONCLUSION: Persistent weakness, asymmetry, and reduced subjective outcome scores at 6-month follow-up after ACLR were not influenced by meniscal treatment. These findings suggested that the weightbearing and range of motion restrictions associated with meniscal repair recovery do not result in loss of early strength or worse patient-reported outcomes.

Gaze Accuracy Differences During Single-Leg Balance Following Anterior Cruciate Ligament Reconstruction.

CONTEXT: Individuals following anterior cruciate ligament reconstruction (ACLR) demonstrate altered postural stability and functional movement patterns. It is hypothesized that individuals following ACLR may compensate with sensory adaptations with greater reliance on visual mechanisms during activities. It is unknown if visual compensatory strategies are implemented to maintain postural stability during functional tasks. OBJECTIVE: To examine visual gaze accuracy during a single-leg balance task in individuals following ACLR compared with healthy, active controls. DESIGN: Case control. SETTING: Controlled laboratory. PARTICIPANTS: A total of 20 individuals (10 ACLR and 10 healthy controls) participated in the study. DATA COLLECTION AND ANALYSIS: Visual gaze patterns were obtained during 20-second single-leg balance trials while participants were instructed to look at presented targets. During the Stationary Target Task, the visual target was presented in a central location for the duration of the trial. The Moving Target Task included a visual target that randomly moved to 1 of 9 target locations for a period of 2 seconds. Targets were stratified into superior, middle, and inferior levels for the Moving Target Task. RESULTS: The Stationary Target Task demonstrated no differences in visual error between groups (P = .89). The Moving Target Task demonstrated a significant interaction between group and target level (F2,36 = 3.76, P = .033). Individuals following ACLR demonstrated greater visual error for the superior targets (ACLR = .70 [.44] m, healthy = .41 [.21] m, Cohen d = 0.83 [0.06 to 1.60]) and inferior targets (ACLR = .68 [.25] m, healthy = .33 [.16] m, Cohen d = 1.67 [0.81 to 2.52]). CONCLUSION: Individuals following ACLR demonstrate greater visual error during settings of high or low visual stimuli compared with healthy individuals to maintain single-limb postural stability. This population may rely on visual input to compensate for the somatosensory changes following injury.

Visuomotor therapy modulates corticospinal excitability in patients following anterior cruciate ligament reconstruction: A randomized crossover trial.

BACKGROUND: Corticospinal adaptations have been observed following anterior cruciate ligament reconstruction around the time of returning to activity. These measures have been related to quadriceps strength deficits. Visuomotor therapy, combining motor control tasks with visual biofeedback, has been shown to increase corticospinal excitability. The purpose of this study was to assess the immediate changes of corticospinal excitability following a single session of visuomotor therapy in patients following anterior cruciate ligament reconstruction. METHODS: This was a single blinded, sham-controlled crossover study. Ten patients following ACLR (8 Female, 26.1(6.2) years) completed assessments of quadriceps strength at approximately 4- and 6-months following anterior cruciate ligament reconstruction. At 6-months, quadriceps motor evoked potentials were assessed at 80%, 90%, 100%, 110%, 120%, 130%, 140%, and 150% of the patient's active motor threshold. Patients were randomized to receive a single session of visuomotor therapy(active) or passive motion(sham). Quadriceps motor evoked potentials were reassessed for treatment effect. Following a one-week washout period, all patients received the crossover intervention. FINDINGS: Moderate to large increases in motor response following visuomotor therapy 90%(P = .008, r = 0.60), 110%(P = .038, r = 0.46), 120%(P = .021, r = 0.52), 130%(P = .021, r = 0.52), 140%(P = .008, r = 0.60) and 150%(P = .021, r = 0.52) of the active motor threshold were found. Moderate increases in motor response was observed following the passive motion at 80% of the active motor threshold(P = .028, r = 0.49). INTERPRETATION: A single session of visuomotor therapy was found to increase quadriceps corticospinal motor response greater than the response to sham therapy. Visuomotor therapy is a potential supplement to quadriceps rehabilitation programs when upregulation of corticospinal excitability is indicated.

ISB clinical biomechanics award winner 2019: Knee extensor fatigue resistance in individuals following anterior cruciate ligament reconstruction.

BACKGROUND: Individuals following anterior cruciate ligament reconstruction demonstrate quadriceps weakness throughout the post-operative recovery and at the time of returning to sport. This is often accompanied with patterns of quadriceps fatigue resistance. As such, fatigue may be an identifier of individuals with delayed recovery. The purpose was to assess quadriceps fatigue in anterior cruciate ligament reconstructed patients at the time of return to sport in comparison to healthy controls. METHODS: A total of 215 individuals, 120 following anterior cruciate ligament reconstruction (21.0 (2.9) years, 63 Female, 5.96 (0.48) months post-surgery) and 95 healthy controls (21.5 (8.4) years, 49 Female), participated in this study. All participants completed a 30-s knee extensor maximum voluntary isometric contraction. Knee extensor strength, limb symmetry index, and fatigue (%) were compared between groups. Between-limb fatigue comparisons were made through the Fatigue Index Limb Difference = [(Involved Limb Fatigue Index) - (Uninvolved Limb Fatigue Index)]. FINDINGS: Individuals following anterior cruciate ligament reconstruction (18.7 (10.9)%, -5.6 (11.2)) demonstrated lower values of unilateral fatigue and Fatigue Index Limb Difference compared to healthy participants (22.5 (8.2)%, P = .002; 2.2 (7.9), P < .001). For anterior cruciate ligament reconstructed patients, there was a weak, negative, significant relationship between the involved limb strength and fatigue (r = -0.184, P = .048). There was no relationship between limb symmetry and Fatigue Index Limb Difference (r = 0.137, P = .142). For Healthy individuals, there was a positive, moderate relationship between limb symmetry and Fatigue Index Limb Difference (r = 0.400, P < .001). INTERPRETATION: Individuals following anterior cruciate ligament reconstruction demonstrate fatigue resistance compared to healthy active controls and greater resistance to fatigue in their involved limb compared to their contralateral limb.

Quadriceps Strength Is Influenced by Skeletal Maturity in Adolescents Recovering From Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament injuries and anterior cruciate ligament reconstructions (ACLRs) are common, especially in adolescent patients. Recovery of strength, jumping performance, and perceived/subjective function are often used to make a return to sports decisions after injury. It is unknown how skeletal maturity may influence strength recovery after ACLR. The purpose of this study was to compare the strength and patient-reported outcomes in adolescent ACLR patients with and without open distal femur and proximal tibia physes. METHODS: One hundred seventeen consecutive patients under the age of 18 were referred for routine strength and subjective outcomes evaluation following ACLR, 100 were included in the final analyses after excluding those with prior injuries, those tested outside for 4 to 12 month postoperative window, and those with incomplete clinical data. All study patients completed patient-reported outcomes, and underwent isometric and isokinetic testing of knee extensor and flexor strength to calculate normalized peak torque and limb symmetry. Statistical analyses were performed on all outcomes data using a 2×2 (physeal status: open, closed; and sex: male, female) with analysis of covariance where age and preoperative activity level were used as covariates. RESULTS: A significant interaction between sex and physeal status for isokinetic knee extension peak torque and isometric knee extension peak torque, and limb symmetry index was found. This indicated that males with open physes were stronger and more symmetric than males with closed physes and females with open physes at ~6 months post-ACLR. There were no differences between sexes for patients with closed physes. No interactions were observed for flexion strength. Male patients and patients with open physes had higher perceived knee function compared with their corresponding counterparts. CONCLUSIONS: After ACLR, adolescent patients with open physes had higher quadriceps strength compared with patients with closed physes. Overall, those skeletally less mature patients actually fared better on the functional strength tests, suggesting that functional recovery is not hindered by the presence of an incompletely closed physis. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

The Affect of Patient Sex and Graft Type on Postoperative Functional Outcomes After Primary ACL Reconstruction.

BACKGROUND: Graft choice in anterior cruciate ligament reconstruction (ACLR) and postoperative rehabilitation may affect strength recovery differently in men than women and therefore affect a timely and successful return to sport. PURPOSE: To compare knee extensor and flexor strength between men and women who underwent isolated ACLR with either patellar tendon or hamstring tendon (HST) autografts. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 166 patients (87 women, 79 men) with primary unilateral and uncomplicated ACLRs were recruited for participation. A total of 100 patients had bone-patellar tendon-bone (BPTB) autografts and 66 had HST autografts. At 6 months postoperatively, all patients completed the Tegner activity scale and International Knee Documentation Committee Subjective Knee Evaluation as well as underwent bilateral isokinetic (90 deg/s) tests of the knee extensor and flexor groups. Outcomes were recorded in a single session as part of a return-to-sport test battery. Surgical notes were obtained to determine the type of autograft and nerve block used at the time of ACLR. RESULTS: There was a significant sex × graft type interaction for mass-normalized knee flexor torque (P = .017). Female patients with an HST graft had a significantly lower knee flexor torque compared with female patients with a BPTB graft (0.592 ± 0.49 N·m/kg vs 0.910 ± 0.24 N·m/kg; Cohen d [95% CI] = 0.91 [0.45, 1.36]). They also had a significantly lower knee flexor torque when compared with male patients with an HST graft (0.592 ± 0.49 N·m/kg vs 0.937 ± 0.35 N·m/kg; Cohen d [95% CI]= 0.88 [0.45, 1.31]). There were significant main effects for graft type with knee flexion (P = .001) and extension (P = .008) symmetry. Patients with a BPTB graft demonstrated lower knee extensor symmetry (65.7% ± 17.0%) and greater knee flexor symmetry (98.7% ± 18.0%) compared with patients with an HST graft (extension: 77.1% ± 32%, Cohen d [95% CI] = 0.47 [0.16, 0.79]; flexion: 82.9% ± 33.3%, Cohen d [95% CI] = 0.63 [0.31, 0.95]). We also observed a significant main effect for sex (P = .028) and graft type (P = .048) for mass-normalized knee extensor strength. Female participants and patients of either sex with BPTB grafts had lower knee extensor strength compared with male participants and patients with HST grafts, respectively. CONCLUSION: At approximately 6 months after ACLR, female patients reconstructed with HST autografts demonstrated weaker HST strength compared with female patients with a BPTB autograft. There were no differences in HST strength between graft types in male patients. Female patients appear to be recovering HST strength differently than male patients when using an HST autograft. These findings may have implications in surgical planning, postoperative rehabilitation, and return-to-sport decision making.

The Influence of Perioperative Nerve Block on Strength and Functional Return to Sports After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Patients often have quadriceps or hamstring weakness after anterior cruciate ligament reconstruction (ACLR), despite postoperative physical therapy regimens; however, little evidence exists connecting nerve blocks and ACLR outcomes. PURPOSE: To compare muscle strength at return to play in patients who received a nerve block with ACLR and determine whether a specific block type affected subjective knee function. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Patients were recruited 5 to 7 months after primary, isolated ACLR and completed bilateral isokinetic strength tests of the knee extensor/flexor groups as a single-session return-to-sport test. Subjective outcomes were assessed with the International Knee Documentation Committee (IKDC) score. Strength was expressed as torque normalized to mass (N·m/kg) and limb symmetry index as involved/uninvolved torque. Chart review was used to determine the type of nerve block and graft used. Nerve block types were classified as knee extensor motor (femoral nerve), knee flexor motor (sciatic nerve), or isolated sensory (adductor canal block/saphenous nerve). A 1-way analysis of covariance controlling for graft type was used. RESULTS: A total of 169 patients were included. Graft type distribution consisted of 102 (60.4%) ipsilateral bone-patellar tendon-bone (BTB) and 67 (39.6%) ipsilateral hamstring tendon. Nerve block type distribution consisted of 38 (22.5%) femoral, 25 (14.8%) saphenous, 45 (26.6%) femoral and sciatic, and 61 (36.1%) saphenous and sciatic. No significant difference was found in knee extensor strength (P = .113) or symmetry (P = .860) between patients with knee extensor motor blocks (1.57 ± 0.45 N·m/kg; 70.1% ± 15.3%) and those without (1.47 ± 0.47 N·m/kg; 69.6% ± 18.8%). A significant difference was found between patients with knee flexor motor blocks (0.83 ± 0.26 N·m/kg) and those without (0.92 ± 0.27 N·m/kg) for normalized knee flexor strength (P = .21) but not knee flexor symmetry (P = .592). Controlling for graft type, there were no differences in subjective knee function (IKDC score) between all nerve block groups (P = .57). CONCLUSION: Our data showed that use of a sciatic nerve block with ACLR in patients with hamstring and BTB grafts influences persistent knee flexor strength deficits at time of return to sports. Although the cause of postoperative muscular weakness is multifactorial, this study adds to the growing body of evidence suggesting that perioperative nerve blocks affect muscle strength and functional rehabilitation after ACLR.

Post-traumatic osteoarthritis diagnosed within 5 years following ACL reconstruction.

PURPOSE: The purpose was to calculate the incidence of osteoarthritis in individuals following Anterior Cruciate Ligament Reconstruction (ACLR) in a large, national database and to examine the risk factors associated with OA development. METHODS: A commercially available insurance database was queried to identify new diagnoses of knee OA in patients with ACLR. The cumulative incidence of knee OA diagnoses in patients after ACLR was calculated and stratified by time from reconstruction. Odds ratios were calculated using logistic regression to describe factors associated with a new OA diagnosis including age, sex, BMI, meniscus involvement, osteochondral graft use, and tobacco use. RESULTS: A total of 10,565 patients with ACLR were identified that did not have an existing diagnosis of OA, 517 of which had a documented new diagnosis of knee OA 5 years after ACL reconstruction. When stratified by follow-up time points, the incidence of a new OA diagnosis within 6 months was 2.3%; within a 1-year follow-up was 4.1%; within 2 years, follow-up was 6.2%, within 3 years, follow-up was 8.4%; within 4 years, follow-up was 10.4%; and within 5 years, follow-up was 12.3%. Risk factors for new OA diagnoses were age (OR 2.44, P < 0.001), sex (OR 1.2, P = 0.002), obesity (OR 1.4, P < 0.001), tobacco use (OR = 1.3, P = 0.001), and meniscal involvement (OR 1.2, P = 0.005). CONCLUSION: Approximately 12% of patients presenting within 5 years following ACLR are diagnosed with OA. Demographic factors associated with an increased risk of a diagnosis of PTOA within 5 years after ACLR are age, sex, BMI, tobacco use, and concomitant meniscal surgery. Clinicians should be cognizant of these risk factors to develop risk profiles in patients with the common goal to achieve optimal long-term outcomes after ACLR. LEVEL OF EVIDENCE: III.

How Much Time Is Needed Between Serial "Return to Play" Assessments to Achieve Clinically Important Strength Gains in Patients Recovering From Anterior Cruciate Ligament Reconstruction?

BACKGROUND: Pass rates for return-to-play evaluations are alarmingly low for patients after anterior cruciate ligament reconstruction (ACLR). Since timing of return to play is a complicated decision, it is important that patients be given optimal time to realize meaningful improvements in strength that warrant additional testing. PURPOSE: To (1) compare outcomes among patients assessed at different time points after ACLR, (2) determine strength gains indicative of improvements in subjective function, and (3) determine the amount of time necessary to achieve meaningful strength gains. STUDY DESIGN: Cross-sectional/case-control study; Level of evidence, 3. METHODS: A total of 293 patients participated in the study after ACLR (mean ± SD, 23.2 ± 10.1 years old; n = 142 female participants; 6.4 ± 0.9 months after ACLR). Participants were stratified on the month of their evaluation after ACLR: 5 to 6 months (n = 122), 6 to 7 months (n = 102), 7 to 8 months (n = 43), and 8 to 9 months (n = 26). The International Knee Documentation Committee (IKDC) subjective form and knee extensor and flexor torque and symmetry, as assessed through an isokinetic dynamometer, were compared among groups. Forty patients (20 female participants, 20.4 ± 7.1 years old) were referred for subsequent testing (2.14 ± 0.78 months after initial visit). Subjective improvement between visits was defined as a ≥9-point change of the IKDC score. Thresholds of knee extensor torque and symmetry indicative of subjective improvement and the time between assessments needed to achieve these strength improvements were determined. RESULTS: Patients between 5 and 6 months (IKDC, 79.7; interquartile range [IQR], 70.1-88.5) had lower subjective function compared to patients between 6 and 7 months (IKDC, 83.9; IQR, 74.5-92.0; P = .019) and 8 and 9 months after ACLR (IKDC, 89.1; IQR 75.8-92.3; P = .026). Patients between 5 and 6 months (1.41 N·m/kg; IQR, 1.16-1.73 N·m/kg]) had lower knee extensor torque compared to patients 6 and 7 months (1.59 N·m/kg; IQR, 1.23-1.95 N·m/kg; P = .013) and 7 and 8 months after ACLR (1.62 N·m/kg; IQR, 1.30-1.86 N·m/kg; P = .046). Patients between 5 and 6 months (66.4%; IQR, 54.2-78.6) had lower symmetry compared to patients between 6 and 7 months (71.8%; IQR,61.1-82.9; P = .019) and 8 and 9 months afterACLR (75.2%; IQR, 66.6-87.7; P = .014). Of the 40 patients that completed follow-up assessments, an increase in knee extensor torque of 0.22 N·m/kg and symmetry of 5.75% discriminated patients that achieved subjective improvement. A period of 1.97 months between assessments discriminated those that achieved the established symmetry threshold. CONCLUSION: Patients demonstrate increasing subjective and quadriceps function when tested at later time points from surgery; however, the observed values are low, suggesting that at 9 months patients are demonstrating deficits that may be improving. Approximately 2 months is needed to observe clinically meaningful improvements.

Measures of Agility and Single-Legged Balance as Clinical Assessments in Patients With Anterior Cruciate Ligament Reconstruction and Healthy Individuals.

CONTEXT: Current clinical assessments used for patients with anterior cruciate ligament reconstruction (ACLR) may not enable clinicians to properly identify functional deficits that have been found in laboratory studies. Establishing muscular-function assessments, through agility and balance tasks, that can properly differentiate individuals with ACLR from healthy, active individuals may permit clinicians to detect deficits that increase the risk for poor outcomes. OBJECTIVE: To compare lower extremity agility and balance between patients with ACLR and participants serving as healthy controls. DESIGN: Case-control study. SETTING: Controlled laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 47 volunteers in 2 groups, ACLR (9 males, 11 females; age = 23.28 ± 5.61 years, height = 173.52 ± 8.89 cm, mass = 70.67 ± 8.89 kg) and control (13 males, 12 females; age = 23.00 ± 6.44, height = 172.50 ± 9.24, mass = 69.81 ± 10.87 kg). MAIN OUTCOME MEASURE(S): Participants performed 3 timed agility tasks: Agility T Test, 17-hop test, and mat-hopping test. Balance was assessed in single-legged (SL) stance in 3 positions (straight knee, bent knee, squat) on 2 surfaces (firm, foam) with the participants' eyes open or closed for 10-second trials. Agility tasks were measured for time to completion. Eyes-open balance tasks were measured using center-of-pressure average velocity, and eyes-closed balance tasks were measured using the Balance Error Scoring System. RESULTS: For the Agility T Test, the ACLR group had slower times than the control group (P = .05). Times on the Agility T Test demonstrated moderate to strong positive relationships for unipedal measures of agility. The ACLR group had greater center-of-pressure average velocity in the SL bent-knee position than the control group. No differences were found between groups for the SL straight-knee and SL-squat balance tasks (P > .05). No differences in errors were present between groups for the eyes-closed balance tasks (P > .05). CONCLUSIONS: The ACLR group demonstrated slower bipedal agility times and decreased postural stability when assessed in an SL bent-knee position compared with the control group.

Corticospinal excitability can discriminate quadriceps strength indicative of knee function after ACL-reconstruction.

PURPOSE: To investigate relationships between quadriceps strength and neural activity, and to establish a clinical threshold of corticospinal excitability able to discriminate between patients with quadriceps strength indicative of satisfactory and unsatisfactory knee function after ACLR. METHODS: A total of 29 patients following primary, unilateral ACL-reconstruction (11 female, 23.2 ± 8.1 years of age, 7.3 ± 2.5 months since surgery) participated. Subjective knee function was quantified using the International Knee Documentation Committee (IKDC) subjective evaluation. Peak isokinetic knee extensor torque was assessed at 90°/s. Quadriceps corticospinal excitability was quantified via active motor threshold (AMT, %2-Tesla) using transcranial magnetic stimulation during a 5% maximal voluntary isometric contraction of the quadriceps. Pearson's r correlations were used to assess the relationship between peak knee extensor torque and AMT. Receiver operating characteristic (ROC) curves were used to establish a threshold of (a) mass-normalized peak knee extensor torque to discriminate satisfactory knee function (IKDC ≥ 75.9%), and (b) AMT to discriminate quadriceps strength indicative of satisfactory knee function. Likelihood ratios (LR) and the magnitude of change in pre-post-test probability were calculated for each threshold. RESULTS: Active motor threshold was negatively correlated with mass-normalized peak knee extensor torque (r = -0.503, P = 0.005). Knee extensor torque ≥1.23 Nm/kg was an excellent discriminator of satisfactory knee function (AUC = 0.890, P = 0.002; (+)LR = 9.56). An AMT ≤50.5% was an excellent discriminator of quadriceps strength indicative of satisfactory knee function following ACLR (AUC = 0.839, P = 0.005; (+)LR = 23.75). CONCLUSION: Lower corticospinal excitability was associated with lower quadriceps strength. An AMT above 50.5% was found to decrease the probability of having satisfactory knee strength by over 62%.

ACL reconstructed individuals do not demonstrate deficits in postural control as measured by single-leg balance.

BACKGROUND: Following anterior cruciate ligament reconstruction (ACLR), patients undergo a battery of performance assessments to determine progression of return to sport activity. Rates of reinjury following ACLR are high, indicating that current assessments may not accurately identify deficits at the time point of return to sport progression. RESEARCH QUESTION: To assess single-leg postural control in ACLR patients around the time point of return to sport progression and their relationships to subjective function. STUDY DESIGN: Descriptive Laboratory Study. METHODS: 198 individuals (108 ACLR, 90 healthy) participated. All ACLR participants were at the time point of return to play progression. Postural stability was quantified by center of pressure (COP) average velocity measured through a straight-knee single-leg balance assessment for 10-seconds with the participant's eyes closed. Subjective knee function was measured from the International Knee Documentation Committee (IKDC) Subjective Knee Form and the Knee Osteoarthritis Outcome Score (KOOS) subscales. RESULTS: No significant differences existed between COP average velocity between limbs (uninvolved, involved) or groups (ACLR, Healthy). As a secondary aim, no significant relationships existed between measures of subjective knee function and postural stability. SIGNIFICANCE: Individuals following ACLR demonstrate similar patterns of postural stability as healthy individuals in a straight knee single leg balance task. Single-leg balance in a straight knee position may not be sensitive enough to detect impairments and does not predict subjective function in ACLR patients at the time of return to sport progression.