Knee kinematics and kinetics are associated with early patellofemoral osteoarthritis following anterior cruciate ligament reconstruction

Adiposity and cartilage lesions following ACL reconstruction

OBJECTIVE

To determine if global, central, or peripheral adiposity is associated with prevalent and worsening cartilage lesions following anterior cruciate ligament reconstruction (ACLR).

METHODS

In 107 individuals one-year post-ACLR, adiposity was assessed globally (body mass index), centrally (waist circumference), and peripherally (knee subcutaneous adipose tissue thickness) from magnetic resonance imaging (MRI). Tibiofemoral and patellofemoral cartilage lesions were assessed from knee MRIs at 1- and 5-years post-ACLR. Poisson regression evaluated the relation of adiposity with prevalent and worsening tibiofemoral and patellofemoral cartilage lesions adjusting for age, sex, and activity level.

RESULTS

The prevalence ratios of adiposity with tibiofemoral (presence in 49%) and patellofemoral (44%) cartilage lesions ranged from 0.99 to 1.03. Adiposity was more strongly associated with longitudinal changes in tibiofemoral (worsening in 21%) and patellofemoral (44%) cartilage lesions. One-unit increase in global (kg/m2), central (cm), and peripheral (mm) adiposity was associated with a higher risk of worsening tibiofemoral cartilage lesions by 17% (risk ratios [95% confidence interval (CI)]: 1.17 [1.09 to 1.23]), 5% (1.05 [1.02 to 1.08]), and 9% (1.09 [1.03 to 1.16]), and patellofemoral cartilage lesions by 5% (1.05 [1.00 to 1.12]), 2% (1.02 [1.00 to 1.04]) and 2% (1.02 [1.00 to 1.04]), respectively.

CONCLUSION

Greater adiposity was a risk factor for worsening cartilage lesions up to 5 years post-ACLR. Clinical interventions aimed at mitigating excess adiposity may be beneficial in preventive approaches for early post-traumatic osteoarthritis.

Patellofemoral joint cartilage lesions frequently develop shortly after anterior cruciate ligament reconstruction using hamstring tendon autograft: A systematic review

PURPOSE

This study aimed to investigate the development of patellofemoral joint (PFJ) cartilage lesions following anterior cruciate ligament reconstruction (ACLR) using hamstring tendon (HT) autograft through a systematic review.

METHODS

A comprehensive search was conducted in PubMed, Embase, Cochrane Library and Google Scholar databases to find articles published from database inception until 15 November 2023. The search terms were [('Anterior Cruciate Ligament' [mesh] OR 'anterior cruciate ligament' OR 'ACL') AND 'reconstruction' AND 'cartilage' AND ('second look arthroscopy' OR 'second-look arthroscopy' OR 'MRI' OR 'magnetic resonance imaging')]. Inclusion criteria were studies that reported on the occurrence of PFJ cartilage lesions following ACLR using HT autograft, as determined by second-look arthroscopy or follow-up magnetic resonance imaging (MRI).

RESULTS

Fifteen studies (1084 patients) met the inclusion criteria, with follow-up periods ranging from 1 to 5 years. In the results of second-look arthroscopy, cartilage grade deterioration was observed, ranging from MDs of 0.1 to 2.0 in the patella and from 0 to 1.0 in the trochlea. Follow-up MRI results reported the incidence of PFJ cartilage degeneration with rates ranging from 20% to 44%. Patient-reported outcome measures often showed no significant association with PFJ cartilage lesions. The studies included in this review reported various risk factors for cartilage lesion development.

CONCLUSION

Cartilage lesions in the PFJ, detected using second-look arthroscopy or follow-up MRI, frequently develop shortly after ACLR using HT autograft. At this stage, patients might not show specific symptoms; however, those with risk factors require careful observation and evaluation by clinicians during follow-up.

LEVEL OF EVIDENCE

Level IV.

Effects of higher femoral tunnels on clinical outcomes, MRI, and second-look findings in double-bundle anterior cruciate ligament reconstruction with a minimal 5-year follow-up

BACKGROUND

To perform anatomical anterior cruciate ligament reconstruction (ACLR), tunnels should be placed relatively higher in the femoral anterior cruciate ligament (ACL) footprint based on the findings of direct and indirect femoral insertion. But the clinical results of higher femoral tunnels (HFT) in double-bundle ACLR (DB-ACLR) remain unclear. The purpose was to investigate the clinical results of HFT and lower femoral tunnels (LFT) in DB-ACLR.

METHODS

From September 2014 to February 2016, 83 patients who underwent DB-ACLR and met the inclusion and exclusion criteria were divided into HFT-ACLR (group 1, n = 37) and LFT-ACLR (group 2, n = 46) according to the position of femoral tunnels. Preoperatively and at the final follow-up, clinical scores were evaluated with International Knee Documentation Committee (IKDC), Tegner activity, and Lysholm score. The stability of the knee was evaluated with KT-2000, Lachman test, and pivot-shift test. Cartilage degeneration grades of the International Cartilage Repair Society (ICRS) were evaluated on magnetic resonance imaging (MRI). Graft tension, continuity, and synovialization were evaluated by second-look arthroscopy. Return-to-sports was assessed at the final follow-up.

RESULTS

Significantly better improvement were found for KT-2000, Lachman test, and pivot-shift test postoperatively in group 1 ( P >0.05). Posterolateral bundles (PL) showed significantly better results in second-look arthroscopy regarding graft tension, continuity, and synovialization ( P <0.05), but not in anteromedial bundles in group 1. At the final follow-up, cartilage worsening was observed in groups 1 and 2, but it did not reach a stastistically significant difference ( P >0.05). No statistically significant differences were found in IKDC subjective score, Tegner activity, and Lysholm score between the two groups. Higher return-to-sports rate was found in group 1 with 86.8% (32/37) vs. 65.2% (30/46) in group 2 ( P = 0.027).

CONCLUSION

The HFT-ACLR group showed better stability results, better PL, and higher return-to-sports rate compared to the LFT-ACLR group.

Muscle strength and osteoarthritis of the knee: a systematic review and meta-analysis of longitudinal studies

OBJECTIVE

To evaluate the sex-specific association between low knee extensor and flexor muscle strength and the risk of knee structural worsening.

MATERIALS AND METHODS

Systematic searches in five databases identified longitudinal studies (≥ 1 year follow-up) reporting an association between knee extensor or flexor strength and structural decline in individuals with, or at risk of, knee osteoarthritis. Results were pooled for tibiofemoral and patellofemoral osteoarthritis worsening (and stratified by sex/gender where possible) using a random-effects meta-analysis estimating the risk ratio and 95% confidence interval or a best-evidence synthesis. Risk of bias and overall certainty of evidence were assessed.

RESULTS

Fourteen studies were included with participants (mean age 27-72 years) with osteoarthritis (n = 8), at risk of osteoarthritis (n = 3), or a combination with, or at risk of, osteoarthritis (n = 3). Low knee extensor strength was associated with an increased risk of worsening tibiofemoral (12 studies: RR 1.18, 95% CI 1.04 to 1.35) and patellofemoral osteoarthritis (4 studies: RR 1.62, 95% CI 1.01 to 2.61). Significant associations between low knee extensor strength and worsening tibiofemoral osteoarthritis were observed for women (4 studies: RR 1.25, 95% CI 1.04 to 1.51) but not men (4 studies: RR 1.10, 95% CI 0.87 to 1.39). Low knee flexor strength increased the risk of worsening tibiofemoral osteoarthritis (5 studies: RR 1.16, 95% CI 1.07 to 1.26). Ten studies were high risk of bias, and all estimates were graded as very low certainty of evidence.

CONCLUSION

Low knee extensor and flexor strength increased the risk of worsening tibiofemoral osteoarthritis. Low knee extensor strength increased the risk of worsening patellofemoral osteoarthritis. The relationship between low knee extensor strength and worsening tibiofemoral osteoarthritis may be modified by sex/gender.

Patellofemoral joint loading and early osteoarthritis after ACL reconstruction

Patellofemoral joint (PFJ) osteoarthritis is common following anterior cruciate ligament reconstruction (ACLR) and may be linked with altered joint loading. However, little is known about the cross-sectional and longitudinal relationship between PFJ loading and osteoarthritis post-ACLR. This study tested if altered PFJ loading is associated with prevalent and worsening early PFJ osteoarthritis post-ACLR. Forty-six participants (mean ± 1 SD age 26 ± 5 years) approximately 1-year post-ACLR underwent magnetic resonance imaging (MRI) and biomechanical assessment of their reconstructed knee. Trunk and lower-limb kinematics plus ground reaction forces were recorded during the landing phase of a standardized forward hop. These data were input into a musculoskeletal model to calculate the PFJ contact force. Follow-up MRI was completed on 32 participants at 5-years post-ACLR. Generalized linear models (Poisson regression) assessed the relationship between PFJ loading and prevalent early PFJ osteoarthritis (i.e., presence of a PFJ cartilage lesion at 1-year post-ACLR) and worsening PFJ osteoarthritis (i.e., incident/progressive PFJ cartilage lesion between 1- and 5-years post-ACLR). A lower peak PFJ contact force was associated with prevalent early PFJ osteoarthritis at 1-year post-ACLR (n = 14 [30.4%]; prevalence ratio: 1.37; 95% confidence interval [CI]: 1.02-1.85) and a higher risk of worsening PFJ osteoarthritis between 1- and 5-years post-ACLR (n = 9 [28.1%]; risk ratio: 1.55, 95% CI: 1.13-2.11). Young adults post-ACLR who exhibited lower PFJ loading during hopping were more likely to have early PFJ osteoarthritis at 1-year and worsening PFJ osteoarthritis between 1- and 5-years. Clinical interventions aimed at mitigating osteoarthritis progression may be beneficial for those with signs of lower PFJ loading post-ACLR.

Mechanical Factors Contributing to Altered Knee Extension Moment during Gait after ACL Reconstruction: A Longitudinal Analysis

PURPOSE

This study aimed to comprehensively examine the extent to which knee flexion angle at initial contact, peak knee flexion angle, and vertical ground reaction force (vGRF) contribute to knee extension moments during gait in individuals with anterior cruciate ligament (ACL) reconstruction.

METHODS

Overground gait biomechanics were evaluated in 26 participants with ACL reconstruction at three time points (about 2, 4, and 6 months after the surgery). Knee flexion angle at initial contact, peak knee flexion angle, peak vGRF, and peak knee extension moment were calculated for each limb during the early stance phase of gait for all three time points. A change score from baseline (time point 2 - time point 1 and time point 3 - time point 1) along with limb symmetry values (ACL - non-ACL limb values) was also calculated for these variables. Multiple linear regressions utilizing classical and Bayesian interference methods were used to determine the contribution of knee flexion angle and vGRF to knee extension moment during gait.

RESULTS

Peak knee flexion angle and peak vGRF positively contributed to knee extension moment during gait in both the reconstructed ( R2 = 0.767, P < 0.001) and nonreconstructed limbs ( R2 = 0.815, P < 0.001). Similar results were observed for the symmetry values ( R2 = 0.673, P < 0.001) and change scores ( R2 = 0.731-0.883; all P < 0.001), except that the changes in knee flexion angle at initial contact also contributed to the model using the change scores in the nonreconstructed limb (time point 2 - time point 1: R2 = 0.844, P < 0.001; time point 3 - time point 1: R2 = 0.883, P < 0.001). Bayesian regression evaluating the likelihood of these prediction models showed that there was decisive evidence favoring the alternative model over the null model (all Bayes factors >1000). Standardized β coefficients indicated that changes in knee flexion angle had a greater impact (>2×) on knee extension moments than vGRF at both time points in both limbs ( βvGRF = 0.204-0.309; βkneeflexion = 0.703-0.831).

CONCLUSIONS

The findings indicate that both knee flexion angle and peak vGRF positively contribute to altered knee extension moments during gait, but the contribution of knee flexion angle is much greater than vGRF. Therefore, treatment strategies targeting these variables may improve knee loading after ACL reconstruction.

Push-Off Dynamics Reveal Task-Independent Alterations in Athletes Returning to Sport after ACL Reconstruction

PURPOSE

Athletes with an anterior cruciate ligament (ACL) reconstruction (ACLR) show persisting biomechanical and neuromuscular landing alterations. So far, most research focused on the landing phase of dynamic tasks where most ACL injuries occur. This study will assess whether these landing alterations are also present in the propulsion phase, in an attempt to identify generalized movement alterations.

METHODS

Twenty-one athletes with ACLR (cleared by their surgeon and/or physiotherapist for return-to-sport) and twenty-one controls performed five single-leg hop tasks. Propulsion kinematics, kinetics, and muscle activations were compared between legs and between groups.

RESULTS

Increased hamstrings activation was found during propulsion when comparing the ACLR limb with both the uninjured limb and the controls. In addition, decreased internal knee extension moments were found in the ACLR limb compared with the uninjured limb.

CONCLUSIONS

Athletes with ACLR show task-independent alterations that unload the knee during the propulsion phase of single-leg hopping tasks. If longitudinal data deem these alterations to be maladaptive, more emphasis must be placed on their normalization during the propulsion phase, assuming beneficial carryover effects into the landing phase. Normalizing these patterns during rehabilitation may potentially reduce the risk of long-term complications such as reinjuries and posttraumatic osteoarthritis.

Quadriceps Muscle Action and Association With Knee Joint Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction

Insufficient quadriceps force production and altered knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) may contribute to a heightened risk of osteoarthritis. Quadriceps muscle lengthening dynamics affect force production and knee joint loading; however, no study to our knowledge has quantified in vivo quadriceps dynamics during walking in individuals with ACLR or examined correlations with joint biomechanics. Our purpose was to quantify bilateral vastus lateralis (VL) fascicle length change and the association thereof with gait biomechanics during weight acceptance in individuals with ACLR. The authors hypothesized that ACLR limbs would exhibit more fascicle lengthening than contralateral limbs. The authors also hypothesized that ACLR limbs would exhibit positive correlations between VL fascicle lengthening and knee joint biomechanics during weight acceptance in walking. The authors quantified VL contractile dynamics via cine B-mode ultrasound imaging in 18 individuals with ACLR walking on an instrumented treadmill. In partial support of our hypothesis, ACLR limb VL fascicles activated without length change on average during weight acceptance while fascicle length on the contralateral limb decreased on average. The authors found a positive association between fascicle lengthening and increase in knee extensor moments in both limbs. Our results suggest that examining quadriceps muscle dynamics may elucidate underlying mechanisms relevant to osteoarthritis.

Biomechanical characteristics and muscle function in individuals with patellofemoral osteoarthritis: A systematic review of cross-sectional studies

BACKGROUND

Our objective was to investigate kinematic and kinetic characteristics and changes in muscle function in individuals with patellofemoral osteoarthritis compared to healthy individuals.

METHODS

Searches were performed of the Medline, Embase, Web of Science, The Cochrane Library, LILACS, and SciELO databases until May of 2022 for observational studies comparing individuals with patellofemoral osteoarthritis to a control group. The PRISMA guidelines and recommendations of the Cochrane Collaboration were followed. The GRADE approach was used to analyze and synthesize the level of evidence.

FINDINGS

Fourteen studies were included, involving a total of 594 participants (360 with patellofemoral osteoarthritis and 234 controls). The level of evidence for pelvis, hip adduction and knee abduction angles at 45° of knee flexion during the single-leg squat, and knee flexion angle during the task of walking was very low. Regarding muscle strength, the level of evidence for isometric strength of the hip abductors, extensors and external rotators, and concentric strength of the knee extensors and flexors was very low. It was not possible to synthesize any type of evidence for kinetic, electromyography, or muscle volume variables.

INTERPRETATION

The level of evidence was very low for all synthesized evidence for kinematic and muscle strength variables. However, individuals with patellofemoral osteoarthritis have lower isometric strength of the hip abductor muscles. Further studies with adequate adjustment for confounding factors, such as the non-inclusion of individuals with osteoarthritis in the tibiofemoral compartment concomitant to patellofemoral osteoarthritis, are needed to gain a better understanding of the clinical characteristics of patellofemoral osteoarthritis.

Effects of Male and Female Sex on the Development of Posttraumatic Osteoarthritis in the Porcine Knee After Anterior Cruciate Ligament Surgery

BACKGROUND

Posttraumatic osteoarthritis (PTOA) is a common sequela of anterior cruciate ligament (ACL) injury, even when surgical treatment is selected. The effect of patient sex on cartilage health after ACL injury and surgical treatment has been less studied.

PURPOSE/HYPOTHESIS

The study objective was to compare the macroscopic cartilage damage that develops after ACL surgery in male and female Yucatan minipigs. It was hypothesized that after ACL surgery, the macroscopic cartilage damage of the tibiofemoral joints from female animals would be greater than that from male animals. Additionally, it was hypothesized that the effect of sex on the macroscopic cartilage damage would depend on surgical treatment.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve-month follow-up data were obtained for 55 adolescent Yucatan minipigs (22 female/33 male) that were randomized to 1 of 3 experimental groups: no treatment (ACL transection [ACLT]), ACL reconstruction, and bridge-enhanced ACL restoration. The Osteoarthritis Research Society International guidelines were used to determine a standardized macroscopic cartilage damage score on 5 surfaces of the knee joint.

RESULTS

Females had significantly worse mean total macroscopic cartilage damage scores on the surgical side (adjusted P value [P adj] = .04) and significantly better scores on the contralateral side (P adj = .01) when compared with males. The trochlear damage scores were also significantly worse in females for surgical limbs (P adj = .009) and significantly better for the contralateral limbs (P adj < .001) when compared with males. Although there were no significant differences in total macroscopic cartilage damage scores between sexes within treatment groups on the surgical limbs (ACLT, P adj = 0.45; ACL reconstruction, P adj = .56; bridge-enhanced ACL restoration, P adj = .23), the mean trochlear scores on the surgical limb of females were significantly worse than those of the males in the ACLT group (P adj = .003).

CONCLUSION

Mean total macroscopic cartilage damage scores of Yucatan minipigs were significantly worse in females than males, regardless of treatment. These differences were predominantly found in the trochlear scores across all treatment groups.

CLINICAL RELEVANCE

These data suggest that patient sex could be more influential in the progression of PTOA than surgical treatment after ACL injury. Identifying factors responsible for this discrepancy may prove valuable to identify targets to slow PTOA progression in male and female ACL-injured populations.

Can Increased Locomotor Task Difficulty Differentiate Knee Muscle Forces After Anterior Cruciate Ligament Reconstruction?

Changes in knee mechanics following anterior cruciate ligament (ACL) reconstruction are known to be magnified during more difficult locomotor tasks, such as when descending stairs. However, it is unclear if increased task difficulty could distinguish differences in forces generated by the muscles surrounding the knee. This study examined how knee muscle forces differ between individuals with ACL reconstruction with different graft types (hamstring tendon and patellar tendon autograft) and "healthy" controls when performing tasks with increasing difficulty. Dynamic simulations were used to identify knee muscle forces in 15 participants when walking overground and descending stairs. The analysis was restricted to the stance phase (foot contact through toe-off), yielding 162 separate simulations of locomotion in increasing difficulty: overground walking, step-to-floor stair descent, and step-to-step stair descent. Results indicated that knee muscle forces were significantly reduced after ACL reconstruction, and stair descent tasks better discriminated changes in the quadriceps and gastrocnemii muscle forces in the reconstructed knees. Changes in quadriceps forces after a patellar tendon graft and changes in gastrocnemii forces after a hamstring tendon graft were only revealed during stair descent. These results emphasize the importance of incorporating sufficiently difficult tasks to detect residual deficits in muscle forces after ACL reconstruction.

Repeatability, reproducibility, and agreement of three methods for finding the mechanical axis of the human tibia

BACKGROUND

Identifying the center of the talocrural joint is crucial in defining the tibia's mechanical axis, which is used in a variety of applications such as a reference for measuring alignment variables following total knee arthroplasty. The objectives of this study were to 1) describe a new method for determining the center of the talocrural joint, 2) determine the repeatability and reproducibility of the new method and two previously described methods for locating the center, 3) determine the limits of agreement between pairs of methods, and 4) determine angular differences in the coronal and sagittal planes between tibial mechanical axes generated by the different methods.

METHODS

The new area centroid method identified the center of the talocrural joint as the centroid of the distal tibia's articular surface. Previously described methods included the diagonal intersection and biplanar methods. For each method, the medial-lateral, anterior-posterior, and proximal-distal coordinates of the talocrural joint center and angular differences between tibial mechanical axes were determined in thirteen 3D full tibia bone models.

RESULTS

For the area centroid method, ICC values indicated excellent repeatability (0.97) and reproducibility (0.92). For the biplanar method, ICC values indicated good repeatability (0.86) and fair reproducibility (0.40). For the diagonal intersection method, ICC values indicated moderate repeatability (0.71) and fair reproducibility (0.46). Limits of agreement were tightest between the area centroid and diagonal intersection methods (± 4.1 mm). Angular differences between tibial mechanical axes were limited to 3°.

CONCLUSION

The area centroid method locates the anatomic center of the talocrural joint, offers better repeatability and reproducibility than existing methods, and is recommended when identifying the tibial mechanical axis.

Knee joint unloading and daily physical activity associate with cartilage T2 relaxation times 1 month after ACL injury

Osteoarthritis (OA) is prevalent after anterior cruciate ligament (ACL) injury, but mechanismsunderlying its development are poorly understood. The purpose of this study was to determine if gait biomechanics and daily physical activity (PA) associate with cartilage T2 relaxation times, a marker of collagen organization and water content, 1 month after ACL injury. Twenty-seven participants (15-35 years old) without chondral lesions completed magnetic resonance imaging, three-dimensional gait analysis, and 1 week of PA accelerometry. Interlimb differences and ratios were calculated for gait biomechanics and T2 relaxation times, respectively. Multiple linear regression models adjusted for age, sex, and concomitant meniscus injury were used to determine the association between gait biomechanics and PA with T2 relaxation times, respectively. Altered knee adduction moment (KAM) impulse, less knee flexion excursion (kEXC) and higher daily step counts accounted for 35.8%-65.8% of T2 relaxation time variation in the weightbearing and posterior cartilage of the medial and lateral compartment (all p ≤ .011). KAM impulse was the strongest factor for T2 relaxation times in all models (all p ≤ .001). Lower KAM impulse associated with longer T2 relaxation times in the injured medial compartment (β = -.720 to -.901) and shorter T2 relaxation in the lateral compartment (β = .713 to .956). At 1 month after ACL injury, altered KAM impulse, less kEXC, and higher PA associated with longer T2 relaxation times, which may indicate poorer cartilage health. Statement of Clinical Significance: Gait biomechanics and daily PA are modifiable targets that may improve cartilage health acutely after ACL injury and slow progression to OA.

Patellofemoral and tibiofemoral joint loading during a single-leg forward hop following ACL reconstruction

Altered biomechanics are frequently observed following anterior cruciate ligament reconstruction (ACLR). Yet, little is known about knee-joint loading, particularly in the patellofemoral-joint, despite patellofemoral-joint osteoarthritis commonly occurring post-ACLR. This study compared knee-joint reaction forces and impulses during the landing phase of a single-leg forward hop in the reconstructed knee of people 12-24 months post-ACLR and uninjured controls. Experimental marker data and ground forces for 66 participants with ACLR (28 ± 6 years, 78 ± 15 kg) and 33 uninjured controls (26 ± 5 years, 70 ± 12 kg) were input into scaled-generic musculoskeletal models to calculate joint angles, joint moments, muscle forces, and the knee-joint reaction forces and impulses. The ACLR group exhibited a lower peak knee flexion angle (mean difference: -6°; 95% confidence interval: [-10°, -2°]), internal knee extension moment (-3.63 [-5.29, -1.97] percentage of body weight × participant height (body weight [BW] × HT), external knee adduction moment (-1.36 [-2.16, -0.56]% BW × HT) and quadriceps force (-2.02 [-2.95, -1.09] BW). The ACLR group also exhibited a lower peak patellofemoral-joint compressive force (-2.24 [-3.31, -1.18] BW), net tibiofemoral-joint compressive force (-0.74 [-1.20, 0.28] BW), and medial compartment force (-0.76 [-1.08, -0.44] BW). Finally, only the impulse of the patellofemoral-joint compressive force was lower in the ACLR group (-0.13 [-0.23, -0.03] body weight-seconds). Lower compressive forces are evident in the patellofemoral- and tibiofemoral-joints of ACLR knees compared to uninjured controls during a single-leg forward hop-landing task. Our findings may have implications for understanding the contributing factors for incidence and progression of knee osteoarthritis after ACLR surgery.

Neuromuscular and biomechanical landing alterations persist in athletes returning to sport after anterior cruciate ligament reconstruction

BACKGROUND

Anterior cruciate ligament reconstructed (ACLR) athletes show increased hamstrings activation and decreased knee flexion moments (KFMs) during single leg landing tasks at time of return-to-sport (RTS). Although these landing alterations seem protective in the short term, they might become undesirable if they persist after RTS. Therefore, the main aim of this study was to investigate whether those landing alterations persist in the months following RTS.

METHODS

Sixteen athletes who had an ACLR performed five unilateral landing tasks at three different time points (at RTS, and at 3 and 6 months after RTS) while KFMs and hamstrings activation were recorded. The following clinical parameters were registered: isokinetic strength of quadriceps and hamstrings, ACL return-to-sport after injury scale (ACL-RSI), Tampa scale of kinesiophobia, self-reported instability and single leg hop distance. A one-way repeated measures analysis of variance (ANOVA) was used to assess whether landing deficits changed over time. Additionally, an explorative analysis was performed to assess whether those athletes whose deficits persisted the most could be identified based on baseline clinical parameters.

RESULTS

The ANOVA showed no differences in landing deficits between sessions, indicating persisting reduced KFMs and increased hamstrings activation in the injured leg compared with the contralateral leg. A significant improvement of the quadriceps concentric strength (at 120°/s), ACL-RSI score and jump distance of the single leg hop was found over time.

CONCLUSIONS

Landing alterations were not resolved 6 months after RTS. Additional interventions may be needed to normalize landing alterations prior to return to sport.

Prognostic factors for tibiofemoral and patellofemoral osteoarthritis 32-37 years after anterior cruciate ligament injury managed with early surgical repair or rehabilitation alone

OBJECTIVE

Explore prognostic factors for tibiofemoral (TFJ) and patellofemoral (PFJ) radiographic osteoarthritis (ROA) and 'symptoms plus ROA' (SOA), 32-37 years following anterior cruciate ligament (ACL) injury.

DESIGN

Exploratory analysis, longitudinal cohort.

METHODS

In 1980-1985, 251 patients aged 15-40 years with acute ACL rupture were allocated to early augmented or non-augmented repair (5 ± 4 days post-injury) plus rehabilitation, or rehabilitation alone. 127 of 190 participants who completed follow-up questionnaires were eligible. We classified ROA as TFJ/PFJ K&L Grade ≥2, and SOA as ROA plus pain and/or symptoms. Multivariable age-adjusted logistic regression investigated potential prognostic factors (assessed at 4 ± 1 year follow-up: ACL treatment, isokinetic quadriceps/hamstrings strength, single-leg-hop for distance, knee flexion/extension deficit, knee laxity, Tegner Activity Scale, Lysholm Scale; sex, baseline meniscus status).

RESULTS

127 patients were aged 58 ± 6 years; BMI 27 ± 4 kg/m²; 28% female; 59% had TFJ-ROA, 48% had TFJ-SOA (including n = 9 knee-arthroplasties), 36% had PFJ-ROA; 27% had PFJ-SOA. Baseline meniscus surgery was a prognostic factor for TFJ-ROA (multivariable age-adjusted odds ratio (95% CI): 3.0 (1.2, 7.8)). A single-leg-hop limb symmetry index (LSI) < 90% was a prognostic factor for PFJ-ROA (5.1 (1.4, 18.7)) and PFJ-SOA (4.9 (1.2, 19.7)). Hamstrings strength LSI <90% was a prognostic factor for PFJ-SOA (5.0 (1.3, 19.3)). ACL treatment with rehabilitation-alone was associated with an 80% reduction in the odds of PFJ-SOA (0.2 (0.1-0.7)), compared with early ACL-repair.

CONCLUSIONS

These findings are hypothesis generating, research is needed to determine whether ACL-injured individuals with these characteristics benefit from interventions to prevent or delay the onset of osteoarthritis.

Neither Residual Anterior Knee Laxity Up to 6 mm nor a Pivot Glide Predict Patient-Reported Outcome Scores or Subsequent Knee Surgery Between 2 and 6 Years After ACL Reconstruction

BACKGROUND

A primary goal of anterior cruciate ligament reconstruction (ACLR) is to reduce pathologically increased anterior and rotational laxity of the knee, but the effects of residual laxity on patient-reported outcomes (PROs) after ACLR remain unclear.

HYPOTHESIS

Increased residual laxity at 2 years postoperatively is predictive of a higher risk of subsequent ipsilateral knee surgery and decreases in PRO scores from 2 to 6 years after surgery.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

From a prospective multicenter cohort, 433 patients aged <36 years were identified at a minimum 2 years after primary ACLR. These patients underwent a KT-1000 arthrometer assessment and pivot-shift test and completed PRO assessments with the Knee injury and Osteoarthritis Outcome Score and International Knee Documentation Committee (IKDC) scores. Patients completed the same PROs at 6 years postoperatively, and any subsequent ipsilateral knee procedures during this period were recorded. Subsequent surgery risk and change in PROs from 2 to 6 years postoperatively were compared based on residual side-to-side KT-1000 arthrometer differences (<-1 mm, -1 to 2 mm, 2 to 6 mm, and >6 mm) in laxity at 2 years postoperatively. Multiple linear regression models were built to determine the relationship between 2-year postoperative knee laxity and 2- to 6-year change in PROs while controlling for age, sex, body mass index, smoking status, meniscal and cartilage status, and graft type.

RESULTS

A total of 381 patients (87.9%) were available for follow-up 6 years postoperatively. There were no significant differences in risk of subsequent knee surgery based on residual knee laxity. Patients with a difference >6 mm in side-to-side anterior laxity at 2 years postoperatively were noted to have a larger decrease in PROs from 2 to 6 years postoperatively (P < .05). No significant differences in any PROs were noted among patients with a difference <6 mm in side-to-side anterior laxity or those with pivot glide (IKDC B) versus no pivot shift (IKDC A).

CONCLUSION

The presence of a residual side-to-side KT-1000 arthrometer difference <6 mm or pivot glide at 2 years after ACLR is not associated with an increased risk of subsequent ipsilateral knee surgery or decreased PROs up to 6 years after ACLR. Conversely, patients exhibiting a difference >6 mm in side-to-side anterior laxity were noted to have significantly decreased PROs at 6 years after ACLR.

Early anterior cruciate ligament reconstruction does not affect 5 year change in knee cartilage thickness: secondary analysis of a randomized clinical trial

OBJECTIVE

To compare 5-year change in femorotibial cartilage thickness in 121 young, active adults with an acute anterior cruciate ligament (ACL) tear randomized to a strategy of structured rehabilitation plus early ACL reconstruction (ACLR) or structured rehabilitation plus optional delayed ACLR.

DESIGN

62 patients were randomized to early ACLR, 59 to optional delayed ACLR. Magnetic resonance imaging (MRI) was acquired within 4 weeks of injury, at two- and 5-years follow-up. Main outcome was 5-year change in overall femorotibial cartilage thickness. Secondary outcomes included the location-independent cartilage ChangeScore, summarizing thinning and thickening in 16 femorotibial subregions. An exploratory as-treated comparison was performed additionally.

RESULTS

Baseline and at least one follow-up MRI were available for 117 patients. Over 5 years, a comparable increase in overall femorotibial cartilage thickness was observed for patients randomized to early ACLR (n = 59) and patients randomized to optional delayed ACLR (n = 58, adjusted mean difference: -5 μm, 95% CI: [-118, 108]μm). However, the location-independent cartilage ChangeScore was greater in those treated with early ACLR than in patients treated with optional delayed ACLR (adjusted mean difference: 403 μm [119, 687]μm). As-treated analysis showed no between-group differences for the main outcome, while the location-independent cartilage ChangeScore was greater for patients treated with early (adjusted mean difference: 632 μm [268, 996]μm) or delayed ACLR (adjusted mean difference: 449 μm [108, 791]μm) than for patients treated with rehabilitation alone.

CONCLUSIONS

In young active adults with acute ACL-injury, choice of treatment strategy for the injured ACL did not modify the magnitude of 5-year change in overall femorotibial cartilage thickness.

TRIAL REGISTRATION

ISRCTN84752559.

Patient-Reported Outcomes and Knee Mechanics Correlate With Patellofemoral Deep Cartilage UTE-T2* 2 Years After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Patellofemoral joint degeneration and dysfunction after anterior cruciate ligament reconstruction (ACLR) are increasingly recognized as contributors to poor clinical outcomes.

PURPOSE

To determine if greater deep cartilage matrix disruption at 2 years after ACLR, as assessed by elevated patellofemoral magnetic resonance imaging (MRI) ultrashort echo time-enhanced T2* (UTE-T2*), is correlated with (1) worse patient-reported knee function and pain and (2) gait metrics related to patellofemoral tracking and loading, such as greater external rotation of the tibia at heel strike, reduced knee flexion moment (as a surrogate of quadriceps function), and greater knee flexion angle at heel strike.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

MRI UTE-T2* relaxation times in patellar and trochlear deep cartilage were compared with patient-reported outcomes and ambulatory gait metrics in 60 patients with ACLR at 2 years after reconstruction. ACLR gait metrics were compared with those of 60 uninjured reference patients matched by age, body mass index, and sex. ACLR UTE-T2* values were compared with those of 20 uninjured reference patients.

RESULTS

Higher trochlear UTE-T2* values were associated with worse Knee injury and Osteoarthritis Outcome Scores (KOOS) Sport/Recreation subscale scores (rho = -0.32; P = .015), and showed a trend for association with worse KOOS Pain subscale scores (rho = -0.26; P = .045). At 2 years after ACLR, greater external rotation of the tibia at heel strike was associated with higher patellar UTE-T2* values (R = 0.40; P = .002); greater knee flexion angle at heel strike was associated with higher trochlear UTE-T2* values (rho = 0.39; P = .002); and greater knee flexion moment showed a trend for association with higher trochlear UTE-T2* values (rho = 0.30; P = .019). Patellar cartilage UTE-T2* values, knee flexion angle at heel strike, and external rotation of the tibia at heel strike were all elevated in ACLR knees as compared with reference knees (P = .029, .001, and .044, respectively).

CONCLUSION

Patellofemoral deep cartilage matrix disruption, as assessed by MRI UTE-T2*, was associated with reduced sports and recreational function and with gait metrics reflective of altered patellofemoral loading. As such, the findings provide new mechanistic information important to improving clinical outcomes related to patellofemoral dysfunction after ACLR.

Young athletes after ACL reconstruction with asymmetric quadriceps strength at the time of return-to-sport clearance demonstrate drop-landing asymmetries two years later

BACKGROUND

Quadriceps strength asymmetry at the time of return-to-sport (RTS) after anterior cruciate ligament reconstruction (ACLR) contributes to altered landing mechanics. However, the impact of RTS quadriceps strength on longitudinal alterations in landing mechanics, a risk factor for poor knee joint health over time, is not understood. The purpose of this study was to test the hypothesis that young athletes with quadriceps strength asymmetry at the time of RTS clearance after ACLR would demonstrate asymmetric landing mechanics 2 years later compared to those without quadriceps strength asymmetry.

METHODS

We followed 57 young athletes (age at RTS = 17.6 ± 3.0 years; 77% females) with primary, unilateral ACLR for 2 years following RTS clearance. At RTS, we measured isometric quadriceps strength bilaterally and calculated limb-symmetry indices [LSI = (involved/uninvolved)×100%]. Using RTS quadriceps LSI, we divided participants into High-Quadriceps (HQ; LSI ≥ 90%) and Low-Quadriceps (LQ; LSI < 85%) groups. Two years later, we assessed landing mechanics during a drop-vertical jump (DVJ) task using three-dimensional motion analysis. We compared involved/uninvolved limb values and LSI between the HQ and LQ groups using Mann-Whitney U tests.

RESULTS

The LQ group (n = 26) demonstrated greater asymmetry (lower LSI) during landing at 2 years post-RTS for knee flexion excursion (p = 0.016) and peak vertical ground reaction force (p = 0.006) compared to the HQ group (n = 28). There were no group differences in uninvolved or involved limb values for all variables (all p > 0.093).

CONCLUSION

Young athletes after ACLR with quadriceps strength asymmetry at the time of RTS favored the uninvolved limb during DVJ landing 2 years later. These landing asymmetries may relate to long-term knee joint health after ACLR.

Is patellofemoral pain preventable? A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To evaluate the effectiveness of interventions to reduce the risk of incident patellofemoral pain.

DESIGN

Systematic review and meta-analysis, with strength of evidence evaluated separately for each intervention type.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials evaluating the effectiveness of interventions to reduce patellofemoral pain risk compared with a control/non-exposed group.

RESULTS

Thirteen trials of mostly military recruits and young athletes analysed six different interventions. There was low certainty evidence from two trials (227 participants) that patellofemoral braces worn during physical activity (compared with no brace) effectively reduced the risk of patellofemoral pain (risk ratio (RR) 0.40, 95% CI 0.22 to 0.73; I2=24.0%). There was low certainty evidence from one trial (320 participants) that running technique retraining to (run softer) reduced patellofemoral pain risk (RR 0.21, 95% CI 0.07 to 0.60). There was low certainty evidence from four trials (3364 participants) that multicomponent (strengthening/neuromuscular) exercise programmes did not significantly reduce the risk of patellofemoral pain (RR 0.49, 95% CI 0.18 to 1.36; I2=64.9%), although broad CIs may reflect exercise dose variations among studies. There was very low certainty evidence from four trials (2314 participants) that foot orthoses (compared with flat inserts/no orthosis) did not significantly reduce the risk of patellofemoral pain (RR 0.63, 95% CI 0.35 to 1.13; I2=0.0%). Static stretching and a running programme that progressed intensity (compared with volume) did not significantly influence patellofemoral pain risk (single studies).

CONCLUSION

There is low-level evidence that patellofemoral braces and running technique retraining can reduce the risk of patellofemoral pain by 60%-79%.

Muscular Coordination of Single-Leg Hop Landing in Uninjured and Anterior Cruciate Ligament-Reconstructed Individuals

This study compared lower-limb muscle function, defined as the contributions of muscles to center-of-mass support and braking, during a single-leg hopping task in anterior cruciate ligament-reconstructed (ACLR) individuals and uninjured controls. In total, 65 ACLR individuals and 32 controls underwent a standardized anticipated single-leg forward hop. Kinematics and ground reaction force data were input into musculoskeletal models to calculate muscle forces and to quantify muscle function by decomposing the vertical (support) and fore-aft (braking) ground reaction force components into contributions by individual lower-limb muscles. Four major muscles, the vasti, soleus, gluteus medius, and gluteus maximus, were primarily involved in support and braking in both ACLR and uninjured groups. However, although the ACLR group demonstrated lower peak forces for these muscles (all Ps < .001, except gluteus maximus, P = .767), magnitude differences in these muscles' contributions to support and braking were not significant. ACLR individuals demonstrated higher erector spinae (P = .012) and hamstrings forces (P = .085) to maintain a straighter, stiffer landing posture with more forward lumbar flexion. This altered landing posture may have enabled the ACLR group to achieve similar muscle function to controls, despite muscle force deficits. Our findings may benefit rehabilitation and the development of interventions to enable faster and safer return to sport.

Poor functional performance 1 year after ACL reconstruction increases the risk of early osteoarthritis progression

Background

Not meeting functional performance criteria increases reinjury risk after ACL reconstruction (ACLR), but the implications for osteoarthritis are not well known.

Objective

To determine if poor functional performance post-ACLR is associated with risk of worsening early osteoarthritis features, knee symptoms, function and quality of life (QoL).

Methods

Seventy-eight participants (48 men) aged 28±15 years completed a functional performance test battery (three hop tests, one-leg-rise) 1 year post-ACLR. Poor functional performance was defined as <90% limb symmetry index (LSI) on each test. At 1 and 5 years, MRI, Knee injury Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) subjective form were completed. Primary outcomes were: (i) worsening patellofemoral and tibiofemoral MRI-osteoarthritis features (cartilage, bone marrow lesions (BMLs) and meniscus) and (ii) change in KOOS and IKDC scores, between 1 and 5 years.

Results

Only 14 (18%) passed (≥90% LSI on all tests) the functional test battery. Poor functional performance on the battery (all four tests <90% LSI) 1 year post-ACLR was associated with 3.66 times (95% CI 1.12 to 12.01) greater risk of worsening patellofemoral BMLs. A triple-crossover hop <90% LSI was associated with 2.09 (95% CI 1.15 to 3.81) times greater risk of worsening patellofemoral cartilage. There was generally no association between functional performance and tibiofemoral MRI-osteoarthritis features, or KOOS/IKDC scores.

Conclusion

Only one in five participants met common functional performance criteria (≥90% LSI all four tests) 1 year post-ACLR. Poor function on all four tests was associated with a 3.66 times increased risk of worsening patellofemoral BMLs, and generally not associated with decline in self-reported outcomes.

Tendon regeneration and muscle hypotrophy after isolated Gracilis tendon harvesting - a pilot study

Purpose

The gracilis tendon (GT) is a commonly used autologous graft in Orthopaedic surgery. The majority of information on knee function and outcomes after hamstring harvest is related to both semitendinosus and GT harvest. Little is known regarding isolated harvest of a GT. It was hypothesized that isolated GT harvest would lead to altered gait patterns (e.g. augmented anterior-posterior translation or rotation in the tibiofemoral joint) and consequently a higher prevalence of cartilage lesions and meniscal tears in knees.

Methods

GT harvesting was performed on patients with chronic acromioclavicular joint instability without previous knee injuries or surgeries. MRI of both knees and thighs were performed. Knee MRI were evaluated using the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Inter- and intraobserver reliabilities, cross-sectional areas of different muscles, fatty infiltration of the gracilis muscle (GM) and GT regeneration were evaluated. The contralateral limb served as reference. The observers were blinded towards the identity of the patients and the operatively treated side.

Results

After a mean time of 44 months after surgery testing was performed on 12 patients. No significant side-to-side differences were found using WORMS, although there was a trend towards increased cartilage lesions after GT harvest (median healthy knee 4.8 and GT harvested knee 7.8 p = 0.086). Inter- and intraobserver repeatability was high with 0.899 (95% confidence interval (CI) 0.708–0.960) and 0.988 (95% CI 0.973–0.995), respectively. A significant hypotrophy of the GM with a mean decrease of 25.3%, 18.4% and 16.9% occurred at 25% (p = 0.016), 50% (p = 0.007) and 75% (p = 0.002) of the length of the femur from distal. No compensatory hypertrophy of other thigh muscles or increased fatty infiltration of the GM was found. Tendon regeneration took place in eight out of 12 patients. In case of regeneration, the regenerated tendon inserted in a more proximal place.

Conclusion

Isolated harvest of the GT for shoulder procedures did not affect knee MRI significantly indicating therefore in general suitable graft utilization for surgeries outside of the knee. GT regenerated in most patients with just a more proximal insertion and a hypotrophy of the muscle belly.

Associations between isometric quadriceps strength characteristics, knee flexion angles, and knee extension moments during single leg step down and landing tasks after anterior cruciate ligament reconstruction

BACKGROUND

It is unclear of how peak knee extension torque and early rate of torque development outcomes are related to lower extremity loading and sagittal plane movement in activities of daily living and landing tasks despite consistent deficits after anterior cruciate ligament reconstruction. The purpose of this cross-section study is to assess the ability of quadriceps strength characteristics to predict movement patterns during a step down and single leg drop crossover hopping tasks.

METHODS

Fifty-two individuals with a unilateral history of anterior cruciate ligament reconstruction completed three trials of the step down and crossover hopping tasks on their involved limb. Participants completed three isometric knee extension contractions at 90° knee flexion with visual feedback to assess peak knee extension torque and rate of torque development during the first 0-100 ms and 100-200 ms of the contraction.

FINDINGS

Peak knee extension torque explained the greatest variance in peak knee extension moment (R² = 40.4%, p < 0.001) and knee flexion angle (R² = 46.7%, p < 0.001) during the crossover hop landing. Rate of torque development (0-100 ms) was the only predictor of knee flexion angle (R² = 19.8%, p = 0.01) at initial contact during the crossover hopping landing. Rate of torque development (100-200 ms) explained 17.6% of the variance in peak knee extension moment during the step down (p = .03).

INTERPRETATION

Peak knee extension torque and early rate of torque development outcomes demonstrate limited relationships between movement of activities of daily living and sport-specific tasks. These limitations should be considered when interpreting the results of isometric strength testing in a clinical setting.

Change in Drop-Landing Mechanics Over 2 Years in Young Athletes After Anterior Cruciate Ligament Reconstruction

BACKGROUND

While between-limb landing asymmetries after anterior cruciate ligament reconstruction (ACLR) are linked with poor function and risk of additional injury, it is not currently understood how landing symmetry changes over time after ACLR.

PURPOSE/HYPOTHESIS

The purpose was to investigate how double-legged drop vertical jump (DVJ) landing and single-legged drop-landing symmetry changed from the time of return-to-sport (RTS) clearance to 2 years later in a prospective cohort of young athletes after ACLR. It was hypothesized that double-legged DVJ landing and single-legged drop-landing symmetry would improve from the time of RTS to 2 years later.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The authors followed 64 young athletes with primary, unilateral ACLR for 2 years after RTS clearance. At the time of RTS and 2 years later, between-limb symmetry values for biomechanical variables of interest (VOIs) were calculated with 3-dimensional motion analysis during double-legged DVJ and single-legged drop-landing tasks. VOIs included knee flexion excursion, peak internal knee extension moment, peak vertical ground-reaction force, and peak trunk flexion (for single-legged task only). Symmetry values and proportions of participants meeting 90% symmetry cutoffs were compared between time points.

RESULTS

For double-legged DVJ landing, symmetry values for all VOIs and the proportions meeting 90% cutoffs for peak internal knee extension moment and peak vertical ground-reaction force were higher at 2 years after RTS as compared with RTS. For single-legged drop-landing, symmetry values were higher for knee flexion excursion and lower for peak trunk flexion at 2 years after RTS as compared with RTS, but the proportions meeting 90% cutoffs for all VOIs did not differ between time points.

CONCLUSION

Double-legged DVJ landing symmetry improved across VOIs over the 2 years after RTS following ACLR, while single-legged drop-landing did not improve as consistently. The implications of longitudinal landing asymmetry after ACLR should be further studied.

Gait Classification Using Mahalanobis–Taguchi System for Health Monitoring Systems Following Anterior Cruciate Ligament Reconstruction

In this paper, a gait patterns classification system is proposed, which is based on Mahalanobis–Taguchi System (MTS). The classification of gait patterns is necessary in order to ascertain the rehab outcome among anterior cruciate ligament reconstruction (ACLR) patients. (1) Background: One of the most critical discussion about when ACLR patients should return to work (RTW). The objective was to use Mahalanobis distance (MD) to classify between the gait patterns of the control and ACLR groups, while the Taguchi Method (TM) was employed to choose the useful features. Moreover, MD was also utilised to ascertain whether the ACLR group approaching RTW. The combination of these two methods is called as Mahalanobis-Taguchi System (MTS). (2) Methods: This study compared the gait of 15 control subjects to a group of 10 subjects with laboratory. Later, the data were analysed using MTS. The analysis was based on 11 spatiotemporal parameters. (3) Results: The results showed that gait deviations can be identified successfully, while the ACLR can be classified with higher precision by MTS. The MDs of the healthy group ranged from 0.560 to 1.180, while the MDs of the ACLR group ranged from 2.308 to 1509.811. Out of the 11 spatiotemporal parameters analysed, only eight parameters were considered as useful features. (4) Conclusions: These results indicate that MTS can effectively detect the ACLR recovery progress with reduced number of useful features. MTS enabled doctors or physiotherapists to provide a clinical assessment of their patients with more objective way.

Anterior and Rotational Knee Laxity Does Not Affect Patient-Reported Knee Function 2 Years After Anterior Cruciate Ligament Reconstruction

BACKGROUND

While a primary goal of anterior cruciate ligament (ACL) reconstruction is to reduce pathologically increased anterior and rotational knee laxity, the relationship between knee laxity after ACL reconstruction and patient-reported knee function remains unclear.

HYPOTHESIS

There would be no significant correlation between the degree of residual anterior and rotational knee laxity and patient-reported outcomes (PROs) 2 years after primary ACL reconstruction.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

From a prospective multicenter nested cohort of patients, 433 patients younger than 36 years of age injured in sports with no history of concomitant ligament surgery, revision ACL surgery, or surgery of the contralateral knee were identified and evaluated at a minimum 2 years after primary ACL reconstruction. Each patient underwent Lachman and pivot-shift evaluation as well as a KT-1000 arthrometer assessment along with Knee injury and Osteoarthritis Outcome Score and subjective International Knee Documentation Committee (IKDC) scores. A proportional odds logistic regression model was used to predict each 2-year PRO score, controlling for preoperative score, age, sex, body mass index, smoking, Marx activity score, education, subsequent surgery, meniscal and cartilage status, graft type, and range of motion asymmetry. Measures of knee laxity were independently added to each model to determine correlation with PROs.

RESULTS

Side-to-side manual Lachman differences were IKDC A in 246 (57%) patients, IKDC B in 183 (42%) patients, and IKDC C in 4 (<1%) patients. Pivot-shift was classified as IKDC A in 209 (48%) patients, IKDC B in 183 (42%) patients, and IKDC C in 11 (2.5%) patients. The mean side-to-side KT-1000 difference was 2.0 ± 2.6 mm. No significant correlations were noted between pivot-shift or anterior tibial translation as assessed by Lachman or KT-1000 and any PRO. All predicted differences in PROs based on IKDC A versus B pivot-shift and anterior tibial translation were less than 4 points.

CONCLUSION

Neither the presence of IKDC A versus B pivot-shift nor increased anterior tibial translation of up to 6 mm is associated with clinically relevant decreases in PROs 2 years after ACL reconstruction.

Loss of patellofemoral cartilage thickness over 5 years following ACL injury depends on the initial treatment strategy: results from the KANON trial

OBJECTIVES

To evaluate changes in patellofemoral cartilage thickness over 5 years after anterior cruciate ligament (ACL) injury and to determine the impact of treatment strategy.

METHODS

121 adults (ages 18-35 years, 26% women) had an ACL injury and participated in the KANON randomised controlled trial. Of those, 117 had available MRIs at baseline (<4 weeks post-ACL rupture) and at least one follow-up measurement (2, 5 years). Patellofemoral cartilage thickness was analysed by manual segmentation (blinded to acquisition order). Patellar, trochlear and total patellofemoral cartilage thickness changes were compared between as-randomised (rehabilitation+early ACL reconstruction (ACLR) (n=59) vs rehabilitation+optional delayed ACLR (n=58)) and as-treated groups (rehabilitation+early ACLR (n=59) vs rehabilitation +delayed ACLR (n=29) vs rehabilitation alone (n=29)).

RESULTS

Patellofemoral cartilage thickness decreased -58 µm (95% CI -104 to -11 µm) over 5 years post-ACL rupture, with the greatest loss observed in trochlea during the first 2 years. Participants randomised to rehabilitation+early ACLR had significantly greater loss of patellar cartilage thickness compared with participants randomised to rehabilitation+optional delayed ACLR over the first 2 years (-25 µm (-52, 1 µm) vs +14 µm (-6 to 34 µm), p=0.02) as well as over 5 years (-36 µm (-78 to 5 µm) vs +18 µm (-7, 42 µm), p=0.02). There were no statistically significant differences in patellofemoral cartilage thickness changes between as-treated groups.

CONCLUSION

Patellofemoral (particularly trochlear) cartilage thickness loss was observed in young adults following acute ACL rupture. Early ACLR was associated with greater patellofemoral (particularly patellar) cartilage thickness loss over 5 years compared with optional delayed ACLR, indicating that early surgical intervention may be associated with greater short-term structural patellofemoral cartilage deterioration compared with optional delayed surgery.

TRIAL REGISTRATION NUMBER

ISRCTN84752559; Post-results.

Greater knee flexion excursion/moment in hopping is associated with better knee function following anterior cruciate ligament reconstruction

PURPOSE

Individuals with impaired knee function after anterior cruciate ligament reconstruction (ACLR) may be at greater risk of developing knee osteoarthritis related to abnormal knee joint movement and loading. The aim of this study was to assess the association between knee biomechanics and knee laxity during hopping and clinically assessed knee function (i.e., patient-reported knee function and hop tests) following ACLR.

METHODS

Sixty-six participants (23 women, mean age 28 ± 6 years, mean 18 ± 3 months following ACLR) completed a standardized single-leg hopping task. Three-dimensional movement analysis was used to assess knee flexion excursion and body weight/height normalized knee flexion moments during landing for the involved limb. Anterior-posterior knee laxity was assessed with a KT-1000 knee arthrometer. Participants then completed a patient-reported knee function questionnaire and three separate hop tests (% of uninvolved limb) and were divided into poor and satisfactory knee function groups (satisfactory: ≥85% patient-reported knee function and ≥ 85% hop test symmetry). Associations between knee function and hop biomechanics/knee laxity were assessed using logistic regression and interquartile range scaled odds ratios (OR^IQR).

RESULTS

Greater knee flexion excursion (OR^IQR 2.9, 95%CI 1.1-7.8), greater knee flexion moment (OR^IQR 4.9, 95%CI 1.6-14.3) and lesser knee laxity (OR^IQR 4.7, 95%CI 1.5-14.9) were significantly associated with greater odds of having satisfactory knee function (≥ 85% patient-reported knee function and ≥ 85% hop test symmetry).

CONCLUSION

Greater knee flexion excursion/moment during hop-landing and lesser knee laxity is associated with better patient-reported knee function and single-leg hop test performance following ACLR. Patients with lower levels of knee function following ACLR demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis. Therefore, interventions aimed at improving hop landing biomechanics in people with poor knee function are likely required.

LEVEL OF EVIDENCE

III, Cross-sectional study.

Does patellar alignment or trochlear morphology predict worsening of patellofemoral disease within the first 5 years after anterior cruciate ligament reconstruction?

PURPOSE

We described patellofemoral alignment and trochlear morphology at one and five years after anterior cruciate ligament reconstruction (ACLR), and evaluated the associations between alignment and trochlear morphology (at one year) and worsening patellofemoral osteoarthritis (OA) features by five years. We also evaluated the associations between alignment and morphology to self-reported pain and function (Knee injury and Osteoarthritis Outcome Score, KOOS) at five years.

MATERIALS AND METHODS

In this longitudinal observational study, we followed 73 participants (mean age 29[9] years, 40% women) from one- to five-years after ACLR. Using MRI, we measured alignment and morphology, and scored cartilage and bone marrow lesions at both time points. We used mixed effects and linear regression models to achieve our stated aims.

RESULTS

Greater lateral patella displacement increased risk of cartilage worsening (Odds Ratio [95% CI]: 1.09 [1.01, 1.16]); while less lateral tilt (0.91 [0.83, 0.99]) and greater trochlear angle (0.88 [0.77, 1.00]) were protective. Greater medial trochlear inclination increased risk of bone marrow lesion worsening (1.12 [1.04, 1.19]); while greater trochlear angle was protective (0.80 [0.67, 0.96]). Greater lateral displacement was associated with worse self-reported KOOS sport and recreation scores (β [95% CI]: -11.0 [-20.9, -1.2]) and quality of life scores (-10.5 [-20.4, -0.7]).

CONCLUSIONS

Lateral displacement, lateral tilt, and morphology at 1 year post-ACLR altered the risk of worsening patellofemoral OA features four years later. Lateral displacement was the only measure associated with worse self-reported symptoms at five years. These findings may lead to novel treatment strategies for secondary prevention after ACLR.

Prevalence and Predictors of Patellofemoral Osteoarthritis after Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft

Background

The present study aimed to evaluate the prevalence of patellofemoral osteoarthritis (PFOA) and identify the factors that affect PFOA development after single-bundle anterior cruciate ligament (ACL) reconstruction with hamstring autograft. We hypothesized that detecting these factors could be helpful in establishment of a rehabilitation strategy to focus on the modifiable factors.

Methods

Of the 324 patients who underwent primary ACL reconstruction between January 2010 and June 2013, 92 patients who were available for follow-up for a minimum of 36 months after the surgery and underwent second-look arthroscopy were enrolled. Subjective assessments and clinical outcome evaluation were conducted. Arthroscopic cartilage evaluation was done using the Outerbridge classification. Univariable and multivariable logistic regression analyses were used.

Results

Ninety-two patients were evaluated at an average of 38.9 ± 5.4 months of follow-up. PFOA above grade 2 was observed in 19 patients (20.7%) at the second-look arthroscopy. Of them, three patients with pre-existing PFOA (3.3%) showed progression of the Outerbridge grade, and 16 (17.4%) had newly developed PFOA. According to the multivariable logistic regression analysis, isokinetic extensor deficit at 60°/sec at the last follow-up (odds ratio [OR], 2.193; 95% confidence interval [CI], 1.081 to 12.439; p = 0.031), age at primary surgery (OR, 1.118; 95% CI, 1.019 to 1.227; p = 0.018), and concurrent meniscectomy at primary surgery (OR, 0.091; 95% CI, 1.012 to 1.177; p = 0.023) were the significant predictors of PFOA development.

Conclusions

Significant predictors of PFOA after ACL reconstruction with hamstring autograft were decreased quadriceps strength at last follow-up, increased age, and concurrent meniscectomy at primary surgery. Quadriceps weakness as a modifiable factor should be considered in the establishment of a rehabilitation strategy to prevent PFOA after ACL reconstruction, especially in older age.

Poor knee function after ACL reconstruction is associated with attenuated landing force and knee flexion moment during running

PURPOSE

Poor knee function after anterior cruciate ligament reconstruction (ACLR) may increase the risk of future knee symptoms and knee osteoarthritis via abnormal knee joint loading patterns, particularly during high-impact activity. This study aimed to assess the relationship between poor self-reported or clinically measured knee function and knee moments/vertical ground reaction force (vGRF) in individuals following ACLR.

METHODS

61 participants (mean 16.5 ± 3 months following ACLR, 23 women) completed a patient-reported knee function questionnaire and three hop tests (% of uninvolved limb). Participants were divided into satisfactory and poor knee function groups (poor < 85% patient-reported knee function and/or < 85% hop test symmetry). The knee biomechanics of both groups were assessed with three-dimensional motion analysis during the stance phase of overland running at self-selected speeds, and the association between knee function and knee moments was assessed using analysis of covariance with running speed as a covariate.

RESULTS

Participants with poor knee function (n = 30) ran with significantly smaller peak knee flexion moments (moderate effect size 0.7, p = 0.03) and significantly smaller peak vGRFs (large effect size 1.0, p = 0.002) compared to those with satisfactory knee function (n = 31). No significant differences were observed for knee adduction and knee external rotation moments or knee kinematics.

CONCLUSION

Individuals following ACLR with poor self-reported knee function and/or hop test performance demonstrate knee moments during running that may be associated with lower knee joint contact forces. These findings provide greater understanding of the relationship between knee biomechanics during running and clinical assessments of knee function.

LEVEL OF EVIDENCE

III. Cross-sectional study.

Hip joint biomechanics in those with and without post-traumatic knee osteoarthritis after anterior cruciate ligament injury

BACKGROUND

Anterior cruciate ligament injury results in altered kinematics and kinetics in the knee and hip joints that persist despite surgical reconstruction and rehabilitation. Abnormal movement patterns and a history of osteoarthritis are risk factors for articular cartilage degeneration in additional joints. The purpose of this study was to determine if hip joint biomechanics early after anterior cruciate ligament injury and reconstruction differ between patients with and without post-traumatic knee osteoarthritis 5years after reconstruction. The study's rationale was that individuals who develop knee osteoarthritis after anterior cruciate ligament injury may also demonstrate large alterations in hip joint biomechanics.

METHODS

Nineteen athletes with anterior cruciate ligament injury completed standard gait analysis before (baseline) and after (post-training) extended pre-operative rehabilitation and at 6months, 1year, and 2years after reconstruction. Weightbearing knee radiographs were completed 5years after reconstruction to identify medial compartment osteoarthritis.

FINDINGS

Five of 19 patients had knee osteoarthritis at 5years after anterior cruciate ligament reconstruction. Patients with knee osteoarthritis at 5years walked with smaller sagittal plane hip angles (P: 0.043) and lower sagittal (P: 0.021) and frontal plane (P: 0.042) external hip moments in the injured limb before and after reconstruction compared to those without knee osteoarthritis.

INTERPRETATION

The current findings suggest hip joint biomechanics may be altered in patients who develop post-traumatic knee osteoarthritis. Further study is needed to confirm whether the risk of non-traumatic hip pathology is increased after anterior cruciate ligament injury and if hip joint biomechanics influence its development.

Patellofemoral Joint Loads During Running at the Time of Return to Sport in Elite Athletes With ACL Reconstruction

BACKGROUND

Patellofemoral joint pain and degeneration are common in patients who undergo anterior cruciate ligament reconstruction (ACLR). The presence of patellofemoral joint pain significantly affects the patient's ability to continue sport participation and may even affect participation in activities of daily living. The mechanisms behind patellofemoral joint pain and degeneration are unclear, but previous research has identified altered patellofemoral joint loading in individuals with patellofemoral joint pain when running. It is unclear whether this process occurs after ACLR.

PURPOSE

To assess the patellofemoral joint stresses during running in ACLR knees and compare the findings to the noninjured knee and matched control knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-four elite sports practitioners who had undergone ACLR and 34 age- and sex-matched controls participated in the study. The participants' running gait was assessed via 3D motion capture, and knee loads and forces were calculated by use of inverse dynamics.

RESULTS

A significance difference was found in knee extensor moment, knee flexion angles, patellofemoral contact force (about 23% greater), and patellofemoral contact pressure (about 27% greater) between the ACLR and the noninjured limb ( P ≤ .04) and between the ACLR and the control limb ( P ≤ .04); no significant differences were found between the noninjured and control limbs ( P ≥ .44).

CONCLUSION

Significantly greater levels of patellofemoral joint stress and load were found in the ACLR knee compared with the noninjured and control knees.

CLINICAL RELEVANCE

Altered levels of patellofemoral stress in the ACLR knee during running may predispose individuals to patellofemoral joint pain.

Accelerated Return to Sport After Anterior Cruciate Ligament Reconstruction and Early Knee Osteoarthritis Features at 1 Year: An Exploratory Study

BACKGROUND

A timely return to competitive sport is a primary goal of anterior cruciate ligament reconstruction (ACLR). It is not known whether an accelerated return to sport increases the risk of early-onset knee osteoarthritis (KOA).

OBJECTIVE

To determine whether an accelerated return to sport post-ACLR (ie, <10 months) is associated with increased odds of early KOA features on magnetic resonance imaging (MRI) 1 year after surgery and to evaluate the relationship between an accelerated return to sport and early KOA features stratified by type of ACL injury (isolated or concurrent chondral/meniscal injury) and lower limb function (good or poor).

DESIGN

Cross-sectional study.

SETTING

Private radiology clinic and university laboratory.

PARTICIPANTS

A total of 111 participants (71 male; mean age 30 ± 8 years) 1-year post-ACLR.

METHODS

Participants completed a self-report questionnaire regarding postoperative return-to-sport data (specific sport, postoperative month first returned), and isotropic 3-T MRI scans were obtained.

OUTCOME MEASURES

Early KOA features (bone marrow, cartilage and meniscal lesions, and osteophytes) assessed with the MRI OA Knee Score. Logistic regression analyses evaluated the odds of early KOA features with an accelerated return to sport (<10 months post-ACLR versus ≥10 months or no return to sport) in the total cohort and stratified by type of ACL injury and lower limb function.

RESULTS

Forty-six (41%) participants returned to competitive sport <10 months post-ACLR. An early return to sport was associated with significantly increased odds of bone marrow lesions (odds ratio [OR] 2.7, 95% confidence interval [CI] 1.3-6.0) but not cartilage (OR 1.2, 95% CI 0.5-2.6) or meniscal lesions (OR 0.8, 95% CI 0.4-1.8) or osteophytes (OR 0.6, 95% CI 0.3-1.4). In those with poor lower limb function, early return to sport exacerbated the odds of bone marrow lesions (OR 4.6, 95% CI 1.6-13.5), whereas stratified analyses for type of ACL injury did not reach statistical significance.

CONCLUSION

An accelerated return to sport, particularly in the presence of poor lower limb function, may be implicated in posttraumatic KOA development.

LEVEL OF EVIDENCE

IV.

Bracing of the Reconstructed and Osteoarthritic Knee during High Dynamic Load Tasks

PURPOSE

Lateral compartment osteoarthritis accompanied by abnormal knee biomechanics is frequently reported in individuals with knee osteoarthritis after anterior cruciate ligament reconstruction (ACLR). The aim of this study was to evaluate changes in knee biomechanics produced by an adjusted and unadjusted varus knee brace during high dynamic loading activities in individuals with lateral knee osteoarthritis after ACLR and valgus malalignment.

METHODS

Nineteen participants who had undergone ACLR 5 to 20 yr previously and had symptomatic and radiographic lateral knee osteoarthritis with valgus malalignment were assessed. Quantitative motion analysis experiments were conducted during hopping, stair ascent, and descent under three test conditions: (i) no brace, (ii) unadjusted brace with sagittal plane support and neutral frontal plane alignment, and (iii) adjusted brace with sagittal plane support and varus realignment (valgus to neutral). Sagittal, frontal, and transverse plane knee kinematics, external joint moment, and angular impulse data were calculated.

RESULTS

Relative to an unbraced knee, braced conditions significantly increased knee flexion and adduction angles during hopping (P = 0.003 and P = 0.005; respectively), stair ascent (P = 0.003 and P < 0.001, respectively), and descent (P = 0.009 and P < 0.001, respectively). In addition, the brace conditions increased knee flexion (P < 0.001) and adduction (P = 0.001) angular impulses and knee stiffness (P < 0.001) during hopping, as well as increased knee adduction moments during stair ascent (P = 0.008) and flexion moments during stair descent (P = 0.006). There were no significant differences between the adjusted and the unadjusted brace conditions (P > 0.05).

CONCLUSION

A knee brace, with or without varus alignment, can modulate knee kinematics and external joint moments during hopping, stairs ascent, and descent in individuals with predominant lateral knee osteoarthritis after ACLR. Longer-term use of a brace may have implications in slowing osteoarthritis progression.