Uninjured Limb Research Articles

Increased short interval intracortical inhibition in participants with previous hamstring strain injury.

Cortical mechanisms may contribute to weakness in participants with previous hamstring strain injury. This study aims to examine intra-cortical inhibition (SICI) and corticospinal excitability in previously injured participants. In this cross-sectional study, TMS was used to examine SICI, silent period, silent period: MEP ratios and area under the stimulus response curve in the biceps femoris and medial hamstrings. Comparisons were made between participants with (n = 10) and without (n = 10) previous hamstring strain injury. Motor threshold and isometric knee flexor strength were also compared between participants and the relationship between strength and SICI in control and previously injured participants was examined. Isometric knee flexor strength was lower in previously injured limbs compared with control limbs (mean difference = -41 Nm (-26%) [95% CI = -80 to -2 Nm], p = 0.04, Cohen's d = -1.27) and contralateral uninjured limbs (mean difference = -23 Nm (-17%), [95% CI = -40 to -6 Nm], p = 0.01, Cohen's d = -0.57). Previously injured limbs exhibited smaller responses to paired pulse stimulation (i.e. greater levels of SICI) in the biceps femoris compared with control limbs (mean difference = -19%, [95% CI = -34 to -5%], p = 0.007, Cohen's d = -1.33). Isometric knee flexor strength was associated with the level of SICI recorded in the biceps femoris in previously injured participants (coefficient = 23 Nm [95% CI = 7-40 Nm], adjusted R2 = 0.31, p = 0.01). There were no differences in markers of corticospinal excitability between previously injured and control limbs (all p > 0.24, all Cohen's d < 0.40). Athletes with previous injury in the biceps femoris exhibit increased SICI in this muscle compared with control participants. Increased SICI is related to lower levels of hamstring strength, and rehabilitation programs targeting the removal of intra-cortical inhibition should be considered.

Incidence of and risk factors for pre-operative deep venous thrombosis in geriatric intertrochanteric fracture patients.

The purpose of this prospective study was to investigate the pre-operative incidence of and risk factors for deep venous thrombosis (DVT) in geriatric intertrochanteric fractures to help facilitate the peri-operative management of them. Data of 1515 geriatric intertrochanteric fracture patients were extracted from a prospective intertrochanteric fractures database according to the inclusion criteria and exclusion criteria. The demographics, fracture characteristics, and pre-operative laboratory indicators of patients were evaluated statistically. The incidence of pre-operative DVT was 10.2% (155 in 1360 patients) in the present study. The rates of proximal DVT, distal DVT, and mixed DVT were 18.1% (28 patients), 56.8% (88 patients), and 25.2% (39 patients), respectively. The percentages of DVT developing in the affected limb, uninjured limb, and bilateral limbs were 74.2% (115 in 55 patients), 16.8% (26 in 155 patients), and 9% (14 in 155 patients), respectively. After the multivariable analysis, the time from injury to surgery (TIS) > 4days [odds ratio (OR) = 1.870, p = 0.001], the number of comorbidities > 2 (OR = 2.124, p = 0.014), and albumin (ALB) < 35g/L (OR = 1.516, p = 0.043), etc. were significantly associated with the development of preoperative DVT in geriatric intertrochanteric fracture patients. Although routine anticoagulant therapy was used to prevent the formation of DVT, the incidence of which was still high. Therefore, pre-operative ultrasound of both lower extremities was advised for pre-operatively, especially for patients with delayed surgery, hypoproteinemia, three or more comorbidities, and a D-dimer level > 1.59mg/L.

Contralateral Projection of Anterior Cingulate Cortex Contributes to Mirror-Image Pain.

Long-term limb nerve injury often leads to mirror-image pain (MIP), an abnormal pain sensation in the limb contralateral to the injury. Although it is clear that MIP is mediated in part by central nociception processing, the underlying mechanisms remain poorly understood. The anterior cingulate cortex (ACC) is a key brain region that receives relayed peripheral nociceptive information from the contralateral limb. In this study, we induced MIP in male mice, in which a unilateral chronic constrictive injury of the sciatic nerve (CCI) induced a decreased nociceptive threshold in both hind limbs and an increased number of c-Fos-expressing neurons in the ACC both contralateral and ipsilateral to the injured limb. Using viral-mediated projection mapping, we observed that a portion of ACC neurons formed monosynaptic connections with contralateral ACC neurons. Furthermore, the number of cross-callosal projection ACC neurons that exhibited c-Fos signal was increased in MIP-expressing mice, suggesting enhanced transmission between ACC neurons of the two hemispheres. Moreover, selective inhibition of the cross-callosal projection ACC neurons contralateral to the injured limb normalized the nociceptive sensation of the uninjured limb without affecting the increased nociceptive sensation of the injured limb in CCI mice. In contrast, inhibition of the non-cross-callosal projection ACC neurons contralateral to the injury normalized the nociceptive sensation of the injured limb without affecting the MIP exhibited in the uninjured limb. These results reveal a circuit mechanism, namely, the cross-callosal projection of ACC between two hemispheres, that contributes to MIP and possibly other forms of contralateral migration of pain sensation.SIGNIFICANCE STATEMENT Mirror-image pain (MIP) refers to the increased pain sensitivity of the contralateral body part in patients with chronic pain. This pathology requires central processing, yet the mechanisms are less known. Here, we demonstrate that the cross-callosal projection neurons in the anterior cingulate cortex (ACC) contralateral to the injury contribute to MIP exhibited in the uninjured limb, but do not affect nociceptive sensation of the injured limb. In contrast, the non-cross-callosal projection neurons in the ACC contralateral to the injury contribute to nociceptive sensation of the injured limb, but do not affect MIP exhibited in the uninjured limb. Our study depicts a novel cross-callosal projection of ACC that contributes to MIP, providing a central mechanism for MIP in chronic pain state.

Muscle strength after the anterior cruciate ligament reconstruction via contralateral bone-tendon-bone autograft

PurposeThe anterior cruciate ligament (ACL) reconstruction via a contralateral bone-tendon-bone (C-BTB) autograft was introduced to encourage early return to sports. The purpose of this study is to evaluate whether primary contralateral BTB ACL reconstruction can be adapted for early return-to-sports modification by investigating the chronological changes of muscle strength after surgery.MethodsFifteen patients who had underwent C-BTB ACL reconstruction were compared with a matched group of 15 patients of ipsilateral BTB (I-BTB) ACL reconstruction. The clinical outcomes of the time of return-to-sports, Tegner activity scale and the rate of second ACL injuries, the tibial anterior translation measurement, and knee extension and flexion muscle strength were assessed.ResultsWithin 12 months after surgery, 14 of 15 patients from both groups returned to preinjury sports. The median time to return to sports after surgery was 6.5 months in the C-BTB group and 8.0 months in the I-BTB group (p = 0.021). No significant difference was noted with regard to the Tegner activity scale, reinjury rate or mean instrumental anterior tibial translation. The quadriceps muscle strength in the ACL-reconstructed knee compared with the opposite knee in both groups at 5 months after surgery was 120.6% in the C-BTB group and 70.0% in the I-BTB group (p < 0.001). However, the quadriceps muscle strength of the non-reconstructed limb, which instructed the graft harvested knee in the C-BTB and the intact knee in the I-BTB group, compared with that of the preoperative uninjured limb, was 74.5% in the C-BTB group and 118.7% in the I-BTB group (p = 0.0021) 5 months after surgery. Moreover, the quadriceps muscle strength of the reconstructed knee compared with the preoperative normal limb was 88.8% and 81.5% in the C-BTB and I-BTB groups, respectively (p = 0.38).ConclusionsACL reconstruction via the C-BTB autograft indicated better quadriceps muscle strength from early stage after surgery compared with I-BTB ACL reconstruction. However, the ostensible rapid symmetrical muscle strength recovery was attributed to strength deficits compared to the preoperative condition at the donor site limb and ACL-reconstructed limb.Level of evidenceLevel: Level: 4.

Effect of Time on MRI Appearance of Graft After ACL Reconstruction: A Comparison of Autologous Hamstring and Quadriceps Tendon Grafts

Background:After anterior cruciate ligament (ACL) reconstruction (ACLR), changes in the appearance of the ACL graft can be monitored using magnetic resonance imaging (MRI).Purpose:The purpose of this study was to evaluate and compare the MRI signal intensity (SI) of hamstring and quadriceps tendon grafts during the first postoperative year after ACLR. As a secondary aim, the relationship of SI to clinical and anatomic measurements was analyzed.Study Design:Cohort study; Level of evidence, 2.Methods:A total of 78 patients who underwent ACLR with an autologous graft were reviewed; 55 received hamstring grafts and 23 received quadriceps tendon grafts. At 3 and 9 months postoperatively, 3-T MRI was performed using a dedicated knee coil, and the median SI of the intra-articular ACL graft was measured on sagittal-plane images. Postoperative lateral radiographs were analyzed to determine medial and lateral posterior tibial slope (PTS). Side-to-side difference in anterior knee laxity between injured and uninjured limbs was measured at 6 and 12 months postoperatively.Results:The median SI of quadriceps grafts was significantly greater than hamstring grafts at 3 months after ACLR (P = .02). Between 3 and 9 months, the median SI of quadriceps grafts decreased (P < .001), while that of hamstring grafts did not significantly change (P = .55). The lateral PTS was significantly correlated with median SI measurements at 3 and 9 months such that greater lateral PTS values were associated with greater median SI. The side-to-side difference in anterior knee laxity decreased for the quadriceps group (P = .04) between 6 and 12 months but did not change for the hamstring group (P = .88).Conclusion:The median SI of quadriceps grafts significantly decreased on MRI between 3 and 9 months after ACLR, while the median SI of hamstring grafts did not significantly change. The change in MRI appearance of the quadriceps grafts was paralleled by a reduction in anterior knee laxity between 6 and 12 months after surgery. In the absence of standardized imaging techniques and imaging analysis methods, the role of MRI in determining graft maturation, and the implications for progression through rehabilitation to return to sport, remain uncertain.

Early Pain Catastrophizing Exacerbates Impaired Limb Loading and 6-Minute Walk Test Distance 12Months After Lower Extremity Fracture.

Disability is common after lower extremity fracture (LEF). Although psychosocial factors have been associated with patient-reported outcomes after LEF, they have not been associated with objective measures of function. Aberrant gait patterns are important markers of function, but are poorly defined after LEF. The primary purpose of this study was to explore whether pain catastrophizing and fear of movement 6weeks after surgery were associated with injured limb loading outcomes and 6-minute walk test (6MWT) distance 12months after femur or tibia fracture. The secondary purpose was to determine if limb loading characteristics differed between injured and uninjured limbs. At 6weeks after LEF, patients completed validated measures of pain catastrophizing, fear of movement, and depression. At 12months, patients completed a 6MWT while wearing instrumented insoles that recorded the limb loading outcomes of stance time, impulse, and loading rate. Bivariate correlations assessed how patient and psychosocial characteristics at 6weeks were associated with injured limb loading outcomes and 6MWT distance. Multivariable regression analyses were performed to determine if psychosocial variables were associated with each outcome after controlling for depression and patient demographic and clinical characteristics. Finally, paired t tests compared limb loading outcomes between limbs. Forty-seven participants completed the 6MWT at 12months (65%), and 38 completed the 6MWT with the instrumented insoles. Fear of movement carried a poor relationship (r = 0.11-0.32) and pain catastrophizing a moderate relationship (r = 0.46-0.54) with 12-month outcomes. The regression results indicated that pain catastrophizing continued to be associated with all outcomes. Finally, the injured limb had significantly lower limb loading outcomes than the uninjured limb at 12months (Cohen d = 0.54-0.69). Pain catastrophizing early after LEF was associated with impaired limb loading and 6MWT distance at 12months. Impaired limb loading persists 12months after LEF. Further research is needed to determine whether rehabilitative efforts focused on pain catastrophizing can restore limb loading after LEF.

Excessive anterior tibial translation in the contralateral uninjured limb is significantly associated with ramp lesion in anterior cruciate ligament injury

PurposeThis study aimed to evaluate the excessive anterior tibial translation (ATT) and muscle strength of patients with ramp lesions. We hypothesised that the higher ATT, lower hamstring-to-quadriceps (HQ) ratio, and higher flexion peak torque influenced by semimembranosus would be associated with ramp lesions.MethodsOne hundred and twenty-one patients who underwent anterior cruciate ligament (ACL) reconstruction were retrospectively evaluated. Clinical evaluation included ATT of the contralateral uninjured limb measured using a KT-1000 arthrometer, the knee flexor and extensor muscle strength of the contralateral uninjured limb at 60°/s and 180°/s of an angular velocity measured using an isokinetic dynamometer, and HQ ratio at 60°/s and 180°/s during the preoperative state. Binary stepwise logistic regression analysis was performed to evaluate the risk factors of ramp lesions.ResultsRamp lesions were found in 27 cases of ACL injuries (27/121, 22.3%). Male sex (odds ratio [OR], 2.913; 95% confidence interval [CI], 1.090–7.787; P = 0.033), longer time between injury to surgery (OR, 2.225; 95% CI, 1.074–4.608; P = 0.031), and higher ATT in the contralateral uninjured limb (OR, 1.502; 95% CI, 1.046–2.159; P = 0.028) were indicated as the independent risk factors of the presence of ramp lesion associated with an ACL injury.ConclusionsMale sex, longer period from injury to surgery, and higher ATT in the contralateral uninjured limb were significantly associated with ramp lesion. These findings are advantageous for identifying patients with a greater risk of developing a ramp lesion with an ACL injury in the clinical setting.Level of evidenceLevel IV

Association of Jump-Landing Biomechanics With Tibiofemoral Articular Cartilage Composition 12 Months After ACL Reconstruction.

Background:Excessively high joint loading during dynamic movements may negatively influence articular cartilage health and contribute to the development of posttraumatic osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Little is known regarding the link between aberrant jump-landing biomechanics and articular cartilage health after ACLR.Purpose/Hypothesis:The purpose of this study was to determine the associations between jump-landing biomechanics and tibiofemoral articular cartilage composition measured using T1ρ magnetic resonance imaging (MRI) relaxation times 12 months postoperatively. We hypothesized that individuals who demonstrate alterations in jump-landing biomechanics, commonly observed after ACLR, would have longer T1ρ MRI relaxation times (longer T1ρ relaxation times associated with less proteoglycan density).Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 27 individuals with unilateral ACLR participated in this cross-sectional study. Jump-landing biomechanics (peak vertical ground-reaction force [vGRF], peak internal knee extension moment [KEM], peak internal knee adduction moment [KAM]) and T1ρ MRI were collected 12 months postoperatively. Mean T1ρ relaxation times for the entire weightbearing medial femoral condyle, lateral femoral condyle (global LFC), medial tibial condyle, and lateral tibial condyle (global LTC) were calculated bilaterally. Global regions of interest were further subsectioned into posterior, central, and anterior regions of interest. All T1ρ relaxation times in the ACLR limb were normalized to the uninjured contralateral limb. Linear regressions were used to determine associations between T1ρ relaxation times and biomechanics after accounting for meniscal/chondral injury.Results:Lower ACLR limb KEM was associated with longer T1ρ relaxation times for the global LTC (ΔR 2 = 0.24; P = .02), posterior LTC (ΔR 2 = 0.21; P = .03), and anterior LTC (ΔR 2 = 0.18; P = .04). Greater ACLR limb peak vGRF was associated with longer T1ρ relaxation times for the global LFC (ΔR 2 = 0.20; P = .02) and central LFC (ΔR 2 = 0.15; P = .05). Peak KAM was not associated with T1ρ outcomes.Conclusion:At 12 months postoperatively, lower peak KEM and greater peak vGRF during jump landing were related to longer T1ρ relaxation times, suggesting worse articular cartilage composition.

Gait Adaptations at 8 Years After Reconstruction of Unilateral Isolated and Combined Posterior Cruciate Ligament Injuries

Background: It remains unclear how posterior cruciate ligament (PCL) reconstruction influences long-term lower extremity joint biomechanics. Purpose: To determine whether patients who underwent PCL reconstruction exhibited long-term alterations in lower limb gait mechanics. Study Design: Controlled laboratory study. Methods: A total of 26 patients underwent gait analyses at 8.2 ± 2.6 years after primary unilateral PCL reconstruction. Sex- and age-matched healthy controls were analyzed for comparison. Gait data were collected using motion capture and force plates. Hip, knee, and ankle angles and moments were compared during initial contact, early stance, and late stance for the reconstructed and uninjured contralateral limbs of patients who underwent PCL reconstruction (PCL group) as well as the limbs of healthy control participants (CON group). Results: No side-to-side kinematic differences were noted between the reconstructed and contralateral limbs of the PCL group; some trivial differences were noted in knee and hip moments. However, major differences between the PCL and CON groups occurred at the knee. Reconstructed and contralateral limbs of the PCL group exhibited larger knee flexion angles during initial contact (Δ = 7.0° [P < .001] and Δ = 6.9° [P < .001], respectively), early stance (Δ = 5.8° [P = .003] and Δ = 6.7° [P < .001], respectively), and late stance (Δ = 7.9° [P < .001] and Δ = 8.0° [P < .001], respectively) compared with the CON group. During early stance, contralateral limbs of the PCL group displayed larger knee flexion moments (Δ = 0.20 N·m/kg; P = .014) compared with the CON group, and both reconstructed (Δ = 0.05 N·m/kg; P = .027) and contralateral (Δ = 0.07 N·m/kg; P = .001) limbs of the PCL group exhibited larger knee external rotation moments compared with the CON group. During late stance, reconstructed and contralateral limbs of the PCL group exhibited smaller knee extension moments (Δ = 0.24 N·m/kg [P < .001] and Δ = 0.26 N·m/kg [P < .001], respectively) and knee internal rotation moments (Δ = 0.06 N·m/kg [P < .001] and Δ = 0.06 N·m/kg [P < .001], respectively) compared with the CON group. No discrepancies were observed at the hip; minimal differences were noted in sagittal-plane ankle mechanics. Conclusion: Patients who underwent PCL reconstruction generally exhibited bilateral gait symmetry at 8 years after surgery. However, they exhibited important biomechanical deviations in both knees compared with healthy controls. These modifications likely reflect adaptive gait strategies to protect the PCL after reconstruction. Clinical Relevance: Long-term follow-up analyses of patients who underwent PCL reconstruction should not use the uninjured contralateral limb as a “healthy” reference, as it also exhibits mechanical differences compared with controls. Results could inform the development of neuromuscular and strength training programs targeting the restoration of knee biomechanics similar to healthy controls to prevent early-onset degeneration that is frequently associated with altered biomechanics.

Local (4‐Aminopyridine)‐PLGA‐PEG Treatment Improves Functional Recovery and Muscle Morphology after Traumatic Peripheral Nerve Injury in Mice

Traumatic peripheral nerve injury (TPNI) represents a major medical problem resulting in loss of both motor and sensory function, and in severe cases, permanent disability. Inadequate axonal regeneration and delayed muscle reinnervation contribute to muscle atrophy and poor functional recovery. To date, there is no effective pharmacologic treatment which can promote neuromuscular outcomes after TPNI. In repurposing studies, we have shown that daily systemic 4-aminopyridine (4-AP), an FDA-approved potassium channel blocker for multiple sclerosis, enhances functional recovery, improves myelination, and attenuates muscle atrophy after TPNI. However, 4-AP at higher doses cause adverse effects such as seizures. Thus, we sought to develop a novel locally injectable formulation of 4-AP which could be administered to a nerve injury site and deliver 4-AP at a sustained rate for several weeks. We developed (4-AP)-Poly(lactide-co-glycolide)-b-Poly(ethylene glycol)-b-Poly(lactide-co-glycolide) (PLGA-PEG-PLGA), consisting of two FDA-approved, biodegradable, and biocompatible hydrogels. It is unknown whether this locally injectable formulation of 4-AP would have an impact on TPNI-induced functional recovery, as well as on muscle atrophy. In this study, an established mouse model of right sciatic nerve crush injury was used and mice received one of 4 treatments: (4-AP)-PLGA-PEG, PLGA-PEG vehicle, systemic 4-AP, or saline control (n = 5/group). Functional recovery was assessed using sciatic function index, grip strength, and von Frey filament testing. At post-injury day 28, gastrocnemius (GN) and tibialis anterior (TA) muscles were harvested from both injured (innervated by crushed nerve) and uninjured (contralateral healthy) hind limbs for histomorphological analysis. Our results show that a single local administration of (4-AP)-PLGA-PEG remarkably enhanced motor and sensory functional recovery on post-sciatic nerve crush injury days 1, 3, 7, 14, and 21. Histomorphometric analysis of the muscles revealed that (4-AP)-PLGA-PEG treatment significantly increased right TA cross-sectional area (CSA) (1488.2 µm2 vs. 438.4 µm2, p<0.01) and minimum Feret's diameter (MFD) (53.9 µm vs. 30.3 µm, p<0.01) compared with the other groups. Similarly, (4-AP)-PLGA-PEG treatment significantly increased right GN CSA (1213.8 µm2 vs. 471.9 µm2, p<0.001) and MFD (48.5 µm vs. 32.6 µm, p<0.01) compared with the other groups. These preliminary findings on global functional and muscle fiber morphological parameters demonstrate that (4-AP)-PLGA-PEG can be used locally for neuromuscular outcomes after TPNI. Further cellular, molecular, and biochemical studies will define the mechanistic insights for this promising long-acting local therapeutic agent in TPNI.

The Impact of Hypercholesterolemia on Tendon Injury Repair

Background Hypercholesterolemia is a condition characterized by high blood cholesterol levels and is associated with tendon xanthomas (cholesterol deposits found on superficial tendons). Lipid accumulation in the tendon's extracellular spaces1 may disrupt the parallel organization of collagen substructures within the tendon, and negatively affect its mechano-sensing and mechanical properties, which may lead to injury. We hypothesized that tendon strength and metabolism would be inferior in a high cholesterol environment and attenuate the tendon's ability to repair after injury. Methods 50 Sprague-Dawley (SD, control) and 50 apolipoprotein E knock-out rats (ApoE, Envigo, IL, USA) rats bred in-house were subject to a unilateral patellar tendon (PT) injury at 12 weeks of age; the uninjured limb served as a control. Animals were euthanased at 3, 14 or 42 days post-injury, time-points chosen to represent tendon inflammatory, reparative and remodelling repair phases, respectively. Animals were randomly assigned for investigating gene expression (SD/ApoE per timepoint n=4/4), tissue histology (n=6/6), biomechanical testing (n=10/10; 14 and 42 days only). Equal male/female ratios were used where possible (total SD M23/F27, ApoE M23/F26). Results ApoE total cholesterol was over double that of SD rats (mean 2.12 vs 0.99 mg/ml, p<0.001). Despite this, there was little histological evidence of lipid content (Oil Red-O staining) in tendons of either group, and no apparent differences in tendon mechanical or material properties (Fig. 1). However, there were differences in gene expression (Fig. 2). ApoE rats demonstrated significantly greater COX2 expression than SD; other inflammatory markers (TGFβ, IL-1, IL-6) did not differ between groups. COL1A1, SCX, LOXα were significantly upregulated 14 days post injury in SD compared to ApoE. A greater COL3A1 response was also observed in ApoE compared to SD rats. Discussion We found differences in injury repair at the cellular level, using an ApoE high cholesterol model. There was little evidence of lipid accumulation at the tissue level, therefore the PT may have been a poor choice for an injury study in this instance and it is not surprising that biomechanical differences were not found. Moreover, ApoE rats were recently found to demonstrate only modest early atherosclerotic characteristics2, thus the young age of our cohort may be a primary factor in the lack of physical evidence of lipid accumulation. Nonetheless, our results indicate that even with a mild phenotype, high cholesterol significantly modulates tendon inflammatory and healing cellular activity, as indicated by altered mRNA levels, which may contribute to the known consequences of tendon cholesterol on tendons in humans. References 1Grewal et al. 2014. Accumulation of oxidized LDL in the tendon tissues of C57BL/6 or apolipoprotein E knock-out mice that consume a high fat diet: potential impact on tendon health. PLoS One 9(12): e114214. 2Rune et al., 2018. Long-term Western diet fed apolipoprotein E-deficient rats exhibit only modest early atherosclerotic characteristics. Sci Rep 8(1): 5416.

Large Individual Bilateral Differences in Tibial Torsion Impact Accurate Contralateral Templating and the Evaluation of Rotational Malalignment.

To determine individual bilateral differences (IBDs) in tibial torsion in a diverse population. Computed tomography scans of uninjured bilateral tibiae were used to determine tibial torsion and IBDs in torsion using 4 measurement methods. Age, sex, and self-identified race/ethnicity were also recorded for each subject. Mean tibial torsion and IBDs in torsion were compared in the overall cohort and when stratified by sex and race/ethnicity. Simple and multiple linear regression models were used to correlate demographic variables with tibial torsion and IBDs in torsion. One hundred ninety-five patients were evaluated. The mean tibial torsion was 27.5 ± 8.3 degrees (range -3 to 47.5 degrees). The mean IBD in torsion was 5.3 ± 4.0 degrees (range 0-23.5 degrees, P < 0.001). 12.3% of patients had IBDs in torsion of ≥10 degrees. In the regression analysis, patients who identified as White had greater average torsion by 4.4 degrees compared with Hispanic/Latinx patients (P = 0.001), whereas age and sex were not significantly associated with absolute torsion. Demographics were not associated with significant differences in IBDs in torsion. Tibial torsion varies considerably and individual side-to-side differences are common. Race/ethnicity was associated with differences in the magnitude of tibial torsion, but no factors were associated with bilateral differences in torsion. The results of this study may be clinically significant in the context of using the uninjured contralateral limb to help establish rotational alignment during medullary nail stabilization of diaphyseal tibia fractures. In addition, these findings should be considered in the evaluation of tibia rotational malalignment. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Changes in Infrapatellar Fat Pad Volume 6 to 12 Months After Anterior Cruciate Ligament Reconstruction and Associations With Patient-Reported Knee Function.

Hypertrophy of the infrapatellar fat pad (IFP) in idiopathic knee osteoarthritis has been linked to deleterious synovial changes and joint pain related to mechanical tissue impingement. Yet little is known regarding the IFP's volumetric changes after anterior cruciate ligament reconstruction (ACLR). To examine changes in IFP volume between 6 and 12 months after ACLR and determine associations between patient-reported outcomes and IFP volume at each time point as well as the volume change over time. In a subset of individuals, we examined interlimb IFP volume differences 12 months post-ACLR. Prospective cohort study. Laboratory. We studied 26 participants (13 women, 13 men, age = 21.88 ± 3.58 years, body mass index = 23.82 ± 2.21 kg/m2) for our primary aims and 13 of those participants (8 women, 5 men, age = 21.15 ± 3.85 years, body mass index = 23.01 ± 2.01 kg/m2) for our exploratory aim. Using magnetic resonance imaging, we evaluated the IFP volume change between 6 and 12 months post-ACLR in the ACLR limb and between-limbs differences at 12 months in a subset of participants. International Knee Documentation Committee subjective knee evaluation (IKDC) scores were collected at 6-month and 12-month follow-ups, and associations between IFP volume and patient-reported outcomes were determined. The IFP volume in the ACLR limb increased from 6 months (19.67 ± 6.30 cm3) to 12 months (21.26 ± 6.91 cm3) post-ACLR. Greater increases of IFP volume between 6 and 12 months were significantly associated with better 6-month IKDC scores (r = .44, P = .03). The IFP volume was greater in the uninjured limb (22.71 ± 7.87 cm3) than in the ACLR limb (20.75 ± 9.03 cm3) 12 months post-ACLR. The IFP volume increased between 6 and 12 months post-ACLR; however, the IFP volume of the ACLR limb remained smaller than that of the uninjured limb at 12 months. In addition, those with better knee function 6 months post-ACLR demonstrated greater increases in IFP volume between 6 and 12 months post-ACLR. This suggests that greater IFP volumes may play a role in long-term joint health after ACLR.

A longitudinal investigation of landing biomechanics following anterior cruciate ligament reconstruction

ObjectiveAbnormal movement patterns have been shown during landing in patients who have undergone anterior cruciate ligament (ACL) reconstruction surgery. The purpose of this study was to investigate landing biomechanics over time in this patient group to determine whether asymmetry between limbs reduced with time and after a return to physical activity. DesignProspective longitudinal study. SettingBiomechanics laboratory. ParticipantsFourteen patients who had undergone ACL reconstruction surgery. Main outcome measureSingle limb landing assessments were made at two time points; within the first year (mean of 10 months) and at 3 years (after patients had returned to sport) following ACL reconstruction. Three-dimensional motion analysis was used to record kinematic and kinetic variables, which were compared across time and limb using ANOVA models. ResultsMost biomechanical variables showed little change over time except for the external knee adduction moment at the operated knee, which increased (effect size d = 0.5), but remained less than the contralateral side. In the sagittal plane, asymmetrical landing patterns were seen at both assessments. Patients landed with reduced knee flexion angles (effect size range 0.76–0.9) and moments (effect size range 0.56–0.9) compared to the uninjured limb and made compensations for this by increasing the hip flexion moment (effect size range d = 0.6–0.75). ConclusionsAsymmetrical landing biomechanics persisted at three years after ACL reconstruction in athletes who returned to sporting activity. Long term implications of controlling the landing by increasing the hip moment are unknown and require further investigation.

Lower limb joint position sense and prospective hamstring injury

BackgroundThe hamstrings remain the most injured muscle group within the Australian Football League (AFL). ObjectiveTo investigate preseason measures of hip and knee joint position sense (JPS) and prospective hamstring injury in AFL players. DesignProspective cohort study. MethodsA total of 116 AFL players were recruited for this study. JPS was assessed with 3-D sensors using mono-articular hip (45° flexion and 0°) and knee (90° and 45° flexion) joint reproduction tests conducted in the preseason. Hamstring injury data were collected prospectively in the following AFL season. Wilcoxon-signed rank tests were used to assess between the subsequently injured and uninjured limbs. Mann-Whitney U tests were used to assess between group differences and odds ratio (OR) were used to predict players at risk of hamstring injury. ResultsEight players with JPS data sustained a season hamstring injury and 108 players did not. JPS was not significantly different between the subsequently injured and uninjured limbs (all P values > 0.05). No significant differences for any JPS measure were found between the subsequently injured and uninjured players (all p's > 0.05). ORs did not achieve significance for AE (2.7, p = 0.21) or for RMSE (OR = 1.9, p = 0.44). ConclusionLower limb JPS measures were not predictive of hamstring injury in AFL players.

Leg length discrepancy, overgrowth, and associated risk factors after a pediatric tibial shaft fracture

BackgroundThis study was performed to investigate leg length discrepancy (LLD), overgrowth, and associated risk factors after pediatric tibial shaft fractures.Materials and methodsThis study included 103 patients younger than 14 years of age (mean age 7.1 years; 75 boys, 28 girls) with unilateral tibial shaft fracture and a minimum follow-up of 24 months. LLD was calculated as the difference between the lengths of the injured and uninjured limbs. Overgrowth was calculated by adding the fracture site shortening from the LLD. Risk factors were assessed in patients with LLD < 1 cm and ≥ 1 cm and overgrowth < 1 cm and ≥ 1 cm.ResultsCasting and titanium elastic nailing (TEN) were performed on 64 and 39 patients, respectively. The mean LLD and overgrowth were 5.6 and 6.4 mm, respectively. There were significant differences in sex (p = 0.018), age (p = 0.041), fibular involvement (p = 0.005), injury mechanism (p = 0.006), and treatment methods (p < 0.001) between patients with LLDs < 1 cm and ≥ 1 cm. There were significant differences in sex (p = 0.029), fibular involvement (p = 0.002), injury mechanism (p = 0.008), and treatment methods (p < 0.001) between patients with overgrowth < 1 cm and ≥ 1 cm. Sex and treatment methods were risk factors associated with LLD ≥ 1 cm and overgrowth ≥ 1 cm following pediatric tibial shaft fracture. The boys had a 7.4-fold higher risk of LLD ≥ 1 cm and 5.4-fold higher risk of overgrowth ≥ 1 cm than the girls. Patients who underwent TEN had a 4.3-fold higher risk of LLD ≥ 1 cm and 4.8-fold higher risk of overgrowth ≥ 1 cm than those treated by casting.ConclusionsPatients undergoing TEN showed greater LLD and overgrowth than those undergoing casting, with boys showing greater LLD and overgrowth than girls. Surgeons should consider the possibility of LLD and overgrowth after pediatric tibial shaft fractures, especially when performing TEN for boys.Level of evidenceLevel III

Utilizing a contralateral hamstring autograft facilitates earlier isokinetic and isometric strength recovery after anterior cruciate ligament reconstruction: a randomised controlled trial

PurposeTo compare muscle strength and patient reported outcomes following ACLR using a semitendinosus (ST) graft from the ipsilateral (IL) leg compared to a graft from the contralateral (CL) leg.MethodsOne-hundred and forty patients with an ACL injury were randomized to IL or CL ACLR. Patients were assessed at 6, 12 and 24 months with isokinetic and isometric muscle strength measured using Biodex. Patient-reported outcomes and manual stability measurements were also recorded.ResultsPatient-related outcomes improved over time for both groups with no significant differences between groups at any time point. No differences between groups in objective knee assessment scores or rerupture rates were found. The IL group was significantly weaker in knee flexion strength at all time points compared to the CL group, additionally the IL group did not recover flexor strength within 2 years.ConclusionThis study demonstrated that utilizing an ST graft harvested from the uninjured limb for ACLR facilitates early isokinetic and isometric strength recovery, with no significant adverse outcomes demonstrated in other measurements and therefore be performed to reduce the risk of long-term strength deficits in the injured legLevel of evidenceII.

Can Biomechanical Testing After Anterior Cruciate Ligament Reconstruction Identify Athletes at Risk for Subsequent ACL Injury to the Contralateral Uninjured Limb?

Background: Athletes are twice as likely to rupture the anterior cruciate ligament (ACL) on their healthy contralateral knee than the reconstructed graft after ACL reconstruction (ACLR). Although physical testing is commonly used after ACLR to assess injury risk to the operated knee, strength, jump, and change-of-direction performance and biomechanical measures have not been examined in those who go on to experience a contralateral ACL injury, to identify factors that may be associated with injury risk. Purpose: To prospectively examine differences in biomechanical and clinical performance measures in male athletes 9 months after ACLR between those who ruptured their previously uninjured contralateral ACL and those who did not at 2-year follow-up and to examine the ability of these differences to predict contralateral ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: A cohort of male athletes returning to level 1 sports after ACLR (N = 1045) underwent isokinetic strength testing and 3-dimensional biomechanical analysis of jump and change-of-direction tests 9 months after surgery. Participants were followed up at 2 years regarding return to play or at second ACL injury. Between-group differences were analyzed in patient-reported outcomes, performance measures, and 3-dimensional biomechanics for the contralateral limb and asymmetry. Logistic regression was applied to determine the ability of identified differences to predict contralateral ACL injury. Results: Of the cohort, 993 had follow-up at 2 years (95%), with 67 experiencing a contralateral ACL injury and 38 an ipsilateral injury. Male athletes who had a contralateral ACL injury had lower quadriceps strength and biomechanical differences on the contralateral limb during double- and single-leg drop jump tests as compared with those who did not experience an injury. Differences were related primarily to deficits in sagittal plane mechanics and plyometric ability on the contralateral side. These variables could explain group membership with fair to good ability (area under the curve, 0.74-0.80). Patient-reported outcomes, limb symmetry of clinical performance measures, and biomechanical measures in change-of-direction tasks did not differentiate those at risk for contralateral injury. Conclusion: This study highlights the importance of sagittal plane control during drop jump tasks and the limited utility of limb symmetry in performance and biomechanical measures when assessing future contralateral ACL injury risk in male athletes. Targeting the identified differences in quadriceps strength and plyometric ability during late-stage rehabilitation and testing may reduce ACL injury risk in healthy limbs in male athletes playing level 1 sports. Clinical Relevance: This study highlights the importance of assessing the contralateral limb after ACLR and identifies biomechanical differences, particularly in the sagittal plane in drop jump tasks, that may be associated with injury to this limb. These factors could be targeted during assessment and rehabilitation with additional quadriceps strengthening and plyometric exercises after ACLR to potentially reduce the high risk of injury to the previously healthy knee. Registration: NCT02771548 (ClinicalTrials.gov identifier).

Non-uniform displacement within ruptured Achilles tendon during isometric contraction.

The purpose of this study was investigate tendon displacement patterns in non-surgically treated patients 14months after acute Achilles tendon rupture (ATR) and to classify patients into groups based on their Achilles tendon (AT) displacement patterns. Twenty patients were tested. Sagittal images of AT were acquired using B-mode ultrasonography during ramp contractions at a torque level corresponding to 30% of the maximal isometric plantarflexion torque of the uninjured limb. A speckle tracking algorithm was used to track proximal-distal movement of the tendon tissue at 6 antero-posterior locations. Two-way repeated measures ANOVA for peak tendon displacement was performed. K-means clustering was used to classify patients according to AT displacement patterns. The difference in peak relative displacement across locations was larger in the uninjured (1.29±0.87mm) than the injured limb (0.69±0.68mm), with a mean difference (95% CI) of 0.60mm (0.14-1.05mm, P<.001) between limbs. For the uninjured limb, cluster analysis formed 3 groups, while 2 groups were formed for the injured limb. The three distinct patterns of AT displacement during isometric plantarflexion in the uninjured limb may arise from subject-specific anatomical variations of AT sub-tendons, while the two patterns in the injured limb may reflect differential recovery after ATR with non-surgical treatment. Subject-specific tendon characteristics are a vital determinant of stress distribution across the tendon. Changes in stress distribution may lead to variation in the location and magnitude of peak displacement within the free AT. Quantifying internal tendon displacement patterns after ATR provides new insights into AT recovery.

HAMSTRING MUSCLE ARCHITECTURE AND VISCOELASTIC PROPERTIES: RELIABILITY AND RETROSPECTIVE COMPARISON BETWEEN PREVIOUSLY INJURED AND UNINJURED ATHLETES

The architecture of the biceps femoris (BF) and stiffness of the hamstrings have been found to be associated with injury risk. However, less is known about the architecture of the equally voluminous semitendinosus (ST) and viscoelastic properties of both muscles in individuals with a prior injury. Methods: BF and ST of 15 athletes (previously injured, [Formula: see text]; control, [Formula: see text]) were assessed using ultrasonography and myotonometry. Mean architecture (muscle thickness (MT), pennation angle (PA) and fascicle length (FL)) and viscoelastic measures (stiffness, oscillation frequency and decrement) were compared between the previously injured and contralateral uninjured limb, and between the previously injured and control limbs (mean of both limbs of the control group). Control group participants returned for a duplicate measurement. Findings: Both muscles exhibited high reliability between sessions (intraclass correlation coefficient [Formula: see text]) for architecture. BF PA was larger in the previously injured than both uninjured [Formula: see text] and control [Formula: see text]. BF fascicles were shorter in the previously injured limb compared to the uninjured [Formula: see text] and control [Formula: see text]. BF was stiffer in the previously injured compared to uninjured [Formula: see text]. ST architecture and viscoelasticity were similar across limbs. Conclusion: A prior hamstring strain injury is associated with a stiffer BF characterized by larger PAs and shorter fascicles.