Are Knee Biomechanics Different in Those With and Without Patellofemoral Osteoarthritis After Anterior Cruciate Ligament Reconstruction?

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.

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.

Hip-Knee Joint Coordination Patterns are Associated With Patellofemoral Joint Cartilage Composition in Patients With Anterior Cruciate Ligament Reconstruction

Joint coordination variability during walking that is associated with patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction are not well understood. The purpose of this study was to assess between-limb differences in joint coordination variability and to determine the relationship of coordination variability with postoperative patellofemoral joint cartilage composition. Thirty-five patients underwent bilateral gait analysis and a magnetic resonance exam of the reconstructed knee joint at 6 months post anterior cruciate ligament reconstruction. Vector coding was used to assess coordination variability during the early (1%-33%), mid (34%-66%), and late (67%-100%) stance phase. The T1ρ/T2 mapping was used to evaluate the glycosaminoglycan-collagen matrix of the patellar and femoral trochlear cartilage. Compared with the uninjured limb, the reconstructed limb exhibited higher hip sagittal/knee sagittal plane coordination variability during midstance as well as higher knee sagittal/ankle sagittal plane coordination variability during both mid and late stance. The hip sagittal/knee sagittal plane coordination variability during midstance predicted 14.6% of the variance in patellar cartilage T1ρ values within the reconstructed limb. In addition, sex of participants was able to predict 32.4% and 13.7% of the variance in femoral trochlea T1ρ and T2 values, respectively. The study results demonstrate that a multijoint mechanism may be associated with early patellofemoral joint cartilage degeneration at 6 months after anterior cruciate ligament reconstruction.

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.

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%.

Between-Limb Differences in Patellofemoral Joint Forces During Running at 12 to 24 Months After Unilateral Anterior Cruciate Ligament Reconstruction

BACKGROUND

Patellofemoral joint (PFJ) osteoarthritis may occur after anterior cruciate ligament reconstruction (ACLR). The mechanisms underpinning the development of PFJ osteoarthritis are not known but may relate to altered PFJ loading. Few studies have assessed PFJ loads during high-impact tasks, such as running, beyond the acute rehabilitation phase (ie, >12 months) after ACLR.

PURPOSE/HYPOTHESIS

The purpose was to compare between-limb joint angles, joint moments, and PFJ contact force during running in individuals at 12 to 24 months after unilateral ACLR. We hypothesized that peak knee flexion angle, knee extension moment, and PFJ contact force during stance would be lower in the ACLR limb compared with the uninjured limb.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 55 participants (mean ± SD age, 28 ± 7 years), 12 to 24 months after ACLR, ran at a self-selected speed (2.9 ± 0.3 m/s). Measured kinematics and ground-reaction forces were input into musculoskeletal models to calculate joint moments and muscle forces. These values were subsequently input into a PFJ model to calculate contact force peak and impulse. Outcome measures were compared between the ACLR and uninjured limbs.

RESULTS

In the ACLR limb, compared with the uninjured limb, the PFJ contact force displayed a lower peak (ACLR, 6.1 ± 1.3 body weight [BW]; uninjured, 6.7 ± 1.4 BW; P < .001) and impulse (ACLR, 0.72 ± 0.17 BW*seconds [BWs]; uninjured, 0.81 ± 0.17 BWs; P < .001). At the time of the peak PFJ contact force, the knee extension moment was lower in the ACLR limb (ACLR, 14.0 ± 2.4 %BW*height [%BW*HT]; uninjured, 15.5 ± 2.5 %BW*HT; P < .001). The opposite was true for the ankle plantarflexion moment (ACLR, 12.1 ± 2.6 %BW*HT; uninjured, 11.5 ± 2.7 %BW*HT; P = .019) and the hip extension moment (ACLR, 2.3 ± 2.5 %BW*HT; uninjured, 1.6 ± 2.3 %BW*HT; P = .013). The foot-ground center of pressure was located more anteriorly with respect to the ankle joint center (ACLR, 5.8 ± 0.9 %height [%HT]; uninjured, 5.4 ± 1.0 %HT; P = .001). No differences were found for the sagittal plane hip, knee, and ankle angles.

CONCLUSION

The ACLR limb experienced lower peak PFJ loads during running, explained by a small anterior shift in the foot-ground center of pressure during stance that offloaded the torque demand away from the ACLR knee.

CLINICAL RELEVANCE

Lower net PFJ loading during running in the ACLR limb more than 12 months after ACLR suggests that underloading might play a role in the onset of PFJ osteoarthritis after ACLR.

Slower Walking Speed Is Related to Early Femoral Trochlear Cartilage Degradation After ACL Reconstruction

Post-traumatic patellofemoral osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR) and early cartilage degradation may be especially common in the femoral trochlear cartilage. Determining the presence of and factors associated with early femoral trochlear cartilage degradation, a precursor to OA, is a critical preliminary step in identifying those at risk for patellofemoral OA development and designing interventions to combat the disease. Early cartilage degradation can be detected using quantitative magnetic resonance imaging measures, such as tissue T₂ relaxation time. The purposes of this study were to (i) compare involved (ACLR) versus uninvolved (contralateral) femoral trochlear cartilage T₂ relaxation times 6 months after ACLR, and (ii) determine the relationship between walking speed and walking mechanics 3 months after ACLR and femoral trochlear cartilage T₂ relaxation times 6 months after ACLR. Twenty-six individuals (age 23 ± 7 years) after primary, unilateral ACLR participated in detailed motion analyses 3.3 ± 0.6 months after ACLR and quantitative magnetic resonance imaging 6.3 ± 0.5 months after ACLR. There were no limb differences in femoral trochlear cartilage T₂ relaxation times. Slower walking speed was related to higher (worse) femoral trochlear cartilage T₂ relaxation times in the involved limb (Pearson's r: -0.583, p = 0.002) and greater interlimb differences in trochlear T₂ relaxation times (Pearson's r: -0.349, p = 0.080). Walking mechanics were weakly related to trochlear T₂ relaxation times. Statement of clinical significance: Slower walking speed was by far the strongest predictor of worse femoral trochlear cartilage health, suggesting slow walking speed may be an early clinical indicator of future patellofemoral OA after ACLR. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:645-652, 2020.

Artificial intelligence and machine learning | applications in musculoskeletal physiotherapy

INTRODUCTION

Artificial intelligence (AI) is a field of mathematical engineering which has potential to enhance healthcare through new care delivery strategies, informed decision making and facilitation of patient engagement. Machine learning (ML) is a form of narrow artificial intelligence which can be used to automate decision making and make predictions based upon patient data.

PURPOSE

This review outlines key applications of supervised and unsupervised machine learning in musculoskeletal medicine; such as diagnostic imaging, patient measurement data, and clinical decision support. The current literature base is examined to identify areas where ML performs equal to or more accurately than human levels.

IMPLICATIONS

Potential is apparent for intelligent machines to enhance various areas of physiotherapy practice through automization of tasks which involve data analysis, classification and prediction. Changes to service provision through applications of ML, should encourage physiotherapists to increase their awareness of and experiences with emerging technologies. Data literacy should be a component of professional development plans to assist physiotherapists in the application of ML and the preparation of information technology systems to use these techniques.

Worsening Knee Osteoarthritis Features on Magnetic Resonance Imaging 1 to 5 Years After Anterior Cruciate Ligament Reconstruction

BACKGROUND

An anterior cruciate ligament (ACL) injury is a well-established risk factor for the long-term development of radiographic osteoarthritis (OA). However, little is known about the early degenerative changes (ie, <5 years after injury) of individual joint features (ie, cartilage, bone marrow), which may be reversible and responsive to interventions.

PURPOSE

To describe early degenerative changes between 1 and 5 years after ACL reconstruction (ACLR) on magnetic resonance imaging (MRI) and explore participant characteristics associated with these changes.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Seventy-eight participants (48 men; median age, 32 years; median body mass index [BMI], 26 kg/m²) underwent 3.0-T MRI at 1 and 5 years after primary hamstring autograft ACLR. Early tibiofemoral and patellofemoral OA features were assessed with the MRI Osteoarthritis Knee Score. The primary outcome was worsening (ie, incident or progressive) cartilage defects, bone marrow lesions (BMLs), osteophytes, and meniscal lesions. Logistic regression with generalized estimating equations evaluated participant characteristics associated with worsening features.

RESULTS

Worsening of cartilage defects in any compartment occurred in 40 (51%) participants. Specifically, worsening in the patellofemoral and medial and lateral tibiofemoral compartments was present in 34 (44%), 8 (10%), and 10 (13%) participants, respectively. Worsening patellofemoral and medial and lateral tibiofemoral BMLs (14 [18%], 5 [6%], and 10 [13%], respectively) and osteophytes (7 [9%], 8 [10%], and 6 [8%], respectively) were less prevalent, while 17 (22%) displayed deteriorating meniscal lesions. Worsening of at least 1 MRI-detected OA feature, in either the patellofemoral or tibiofemoral compartment, occurred in 53 (68%) participants. Radiographic OA in any compartment was evident in 5 (6%) and 16 (21%) participants at 1 and 5 years, respectively. A high BMI (>25 kg/m²) was consistently associated with elevated odds (between 2- and 5-fold) of worsening patellofemoral and tibiofemoral OA features.

CONCLUSION

High rates of degenerative changes occur in the first 5 years after ACLR, particularly the development and progression of patellofemoral cartilage defects. Older patients with a higher BMI may be at particular risk and should be educated about this risk.

Lateral displacement, sulcus angle and trochlear angle are associated with early patellofemoral osteoarthritis following anterior cruciate ligament reconstruction

PURPOSE

Patellofemoral osteoarthritis (PFOA) occurs in approximately half of anterior cruciate ligament (ACL)-injured knees within 10-15 years of trauma. Risk factors for post-traumatic PFOA are poorly understood. Patellofemoral alignment and trochlear morphology may be associated with PFOA following ACL reconstruction (ACLR), and understanding these relationships, particularly early in the post-surgical time period, may guide effective early intervention strategies. In this study, patellofemoral alignment and trochlear morphology were investigated in relation to radiographic features of early PFOA 1-year post-ACLR.

METHODS

Participants (aged 18-50 years) had undergone ACLR approximately 1 year prior to being assessed. Early PFOA was defined as presence of a definite patellofemoral osteophyte on lateral or skyline radiograph. Sagittal and axial plane alignment and trochlear morphology were estimated using MRI. Using logistic regression, the relationship between alignment or morphology and presence of osteophytes was evaluated.

RESULTS

Of 111 participants [age 30 ± 8.5; 41 (37%) women], 19 (17%) had definite osteophytes, only two of whom had had patellofemoral chondral lesions noted intra-operatively. One measure of patellar alignment (bisect offset OR 1.1 [95% confidence interval 1.0, 1.2]) and two measures of trochlear morphology (sulcus angle OR 1.1 [1.0, 1.2], trochlear angle OR 1.2 [1.0, 1.5]) were associated with patellofemoral osteophytes.

CONCLUSIONS

Patellofemoral malalignment and/or altered trochlear morphology were associated with PFOA 1 year following ACLR compared to individuals post-ACLR without these features. Clarifying the role of alignment and morphology in post-traumatic PFOA may contribute to improving early intervention strategies aimed at secondary prevention.

LEVEL OF EVIDENCE

IV.

Sub-elite Football Players With Hip-Related Groin Pain and a Positive Flexion, Adduction, and Internal Rotation Test Exhibit Distinct Biomechanical Differences Compared With the Asymptomatic Side

Background Hip-related groin pain is common in sub-elite football players and may be associated with altered hip biomechanics. Objectives To compare the hip biomechanics, bony hip morphology associated with femoroacetabular impingement (FAI) syndrome, and hip strength and range of motion (ROM) between the symptomatic and asymptomatic limbs of sub-elite football players with unilateral hip-related groin pain and a positive flexion, adduction, and internal rotation (FADIR) test. Methods Fifteen sub-elite football (soccer) players with unilateral hip-related groin pain and a positive FADIR test were recruited for this observational cross-sectional study. Three-dimensional motion analysis and ground reaction force data were recorded for walking and a single-leg drop-jump (SLDJ) task. Participants also underwent a standard anterior-posterior hip radiograph and hip strength and ROM assessment. Between-limb differences were assessed using paired t tests or Wilcoxon signed-rank tests. Results The symptomatic limb displayed a smaller peak hip extension angle (P = .01) and a lower peak hip adduction moment (P = .03) compared with the asymptomatic limb during the stance phase of walking. Additionally, during the SLDJ, the symptomatic limb demonstrated less total sagittal plane ROM (P = .04). The symptomatic limb also demonstrated less external rotation ROM (P = .03). However, no differences were found between limbs for bony hip morphology associated with FAI syndrome or hip strength. Conclusion This study found between-limb asymmetries in low- and high-impact functional tasks, such as walking and an SLDJ, in football players with unilateral hip-related groin pain. Despite unilateral pain, bony morphology associated with FAI syndrome did not differ between limbs. J Orthop Sports Phys Ther 2018;48(7):584-593. Epub 8 May 2018. doi:10.2519/jospt.2018.7910.

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.

The effects of dry needling and radial extracorporeal shockwave therapy on latent trigger point sensitivity in the quadriceps: A randomised control pilot study

OBJECTIVES

Latent myofascial trigger points (TrP) can alter joint kinematics, reduce strength and alter activation patterns, affecting athletic performance. TrP sensitivity can be measured with the pressure pain threshold (PPT). Dry needling (DN) has been used to treat latent TrPs, but may cause post-needling soreness. Radial extracorporeal shockwave therapy (rESWT) could be used as an alternative to DN during heavy training or competition.

METHODS

After baseline measures, 21 recreational athletes were split into three groups: DN, rESWT or control group, and were treated for three sessions in one week. Follow-up outcome sessions were conducted two to four and seven days after the last treatment. TrP sensitivity was measured using the PPT.

RESULTS

There was a groupXtime interaction for the PPT (p < 0.05). After a decrease in PPT during treating, there was a significant increase (p < 0.05) in PPT for the DN group (12.92%). The rESWT group also significantly (p < 0.05) increased (13.26%), but did not show any post-treatment soreness during the treatment phase. There was no difference in the PPT in the control group during any session.

CONCLUSION

DN is effective for increasing PPT of latent TrPs, but can be associated with post-treatment soreness. rESWT is as effective, but without the post-treatment soreness. Future studies should include treating multiple TrPs in the lower kinetic chain as well as measuring muscle activation and joint function. Furthermore, consideration for the current training load and up-coming competition is needed. Optimum timing and longer follow-up periods of such interventions should be explored.

LEVEL OF EVIDENCE

2b.

SUMMARY

Treating latent TrPs in the lower kinetic chain may improve muscle activation. Unlike DN, rESWT does not cause post- treatment soreness. Consideration of training load and up-coming competition is needed to deliver the optimum treatment strategy for athletes with latent TrPs.

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.

International patellofemoral osteoarthritis consortium: Consensus statement on the diagnosis, burden, outcome measures, prognosis, risk factors and treatment

OBJECTIVE

To present the current status of knowledge in the field of patellofemoral (PF) osteoarthritis (OA) and formulate a research agenda in order to guide future research on this topic.

DESIGN

A 1-day meeting was organized with the aim to bring together international experts in the field to discuss the current state of knowledge on PF OA. Experts from multiple disciplines were invited based on their scientific publications in the field of PF OA and interest in the subject. Topics discussed include the diagnosis, impact, prognosis, and treatment of PF OA.

METHODS

Following context-setting presentations, an interactive discussion was held in order to achieve consensus on the PF OA topics of interest: (1) diagnosis and definition; (2) burden; (3) outcome measures; (4) prognosis; (5) risk factors, and (6) treatment. Groups of meeting attendees reviewed the literature on these topics and narratively summarized the current state of knowledge, and each group formulated research agenda items relevant to the specific topics of interest. Each consortium member consequently ranked the importance of all items on a 0-10 Numerical Rating Scale (NRS) (10 = extremely important, to 0 = not at all important).

RESULTS

After ranking all formulated items on importance, 6 of the 28 research agenda items formulated received an average of 7.5 points on the NRS. The most highly ranked items covered the fields of treatment, diagnosis, and definition of PF OA.

CONCLUSIONS

We recommend to develop clear clinical criteria for PF OA and to reach consensus on the definition of PF OA by both radiographs and MRI. Additionally, more understanding is necessary to be able to distinguish PF symptoms from those arising from the tibiofemoral joint. More insight is needed on effective treatment strategies for PF OA; specifically, tailoring nonpharmacological treatments to individuals with PF OA, and determining whether isolated PF OA requires different treatment strategies than combined PF and tibiofemoral OA.

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.

MRI observations of patellar tendon length change after ACL reconstruction with hamstring autografts

The post-operative patellar tendon length was studied to evaluate the possible tendon length change after anterior cruciate ligament (ACL) reconstruction with hamstring autografts. The Insall-Salvati index, modified Insall-Salvati index, curved modified Insall-Salvati index and Caton-Deschamps index were observed by MRI during a follow-up period of 12 weeks on 20 ACL reconstructed knees. The results showed no patellar baja or alta pre-existed on those ACL injured patients. After a follow-up period of 12 weeks, no patellar tendon length change was observed. It is suggested that the change of patella was not the primary reason that may contribute to the premature patellofemoral joint osteoarthritis after ACL reconstruction.

Quantitative analysis of T2 relaxation times of the patellofemoral joint cartilage 3 years after anterior cruciate ligament reconstruction

Objective

To evaluate patient-specific patellofemoral joint (PFJ) cartilage 3 years postoperatively using T2 mapping magnetic resonance imaging and the uninjured contralateral side as control.

Hypothesis

The cartilage of the PFJ in the anterior cruciate ligament (ACL) reconstructed knees would show increased T2 values compared to the uninjured contralateral knees at 3-year follow-up, and the femoral (trochlear) cartilage would be more susceptible than the patella in degeneration in ACL-reconstructed knees.

Methods

Ten patients with clinically successful ACL-reconstructed knees were prospectively enrolled 3 years postoperatively. Sagittal images of both knees were obtained using T2 mapping. Cartilage over the medial, central, and lateral regions of the trochlea and patella was divided into superficial and deep regions. Average T2 values of the cartilage at each region of interest of the ACL-reconstructed and uninjured contralateral knees were compared for each individual patient.

Results

Overall, the T2 values at the superficial layers of the medial and central trochlear cartilage of the ACL-reconstructed knees were significantly higher than those of the uninjured contralateral knees by 4.23 ± 9.09 milliseconds (8.9%; p = 0.043) and 5.94 ± 8.12 milliseconds (10.9%; p = 0.019), respectively. No significant difference was found in other cartilage areas of the trochlea and patella. In individual patient analysis, increased T2 values of ACL-reconstructed knees were found in all 10 patients in at least one superficial region and eight patients in at least one deep region of the trochlear cartilage, five patients in at least one superficial region, and eight patients in at least one deep region of the patellar cartilage.

Conclusion

Despite a clinically satisfactory ACL reconstruction (with negative anteroposterior drawer and pivot shift tests), all patients showed at least one region with increased T2 value of the PFJ cartilage 3 years after ACL reconstruction, especially at the medial compartment of the trochlear cartilage.

The Translational Potential of this Article

Little data has been reported on PFJ cartilage condition after ACL reconstruction. This study could help develop noninvasive diagnostic methods for detection of early PFJ cartilage degeneration after ACL reconstruction.

Anterior knee pain following anterior cruciate ligament reconstruction does not increase the risk of patellofemoral osteoarthritis at 15- and 20-year follow-ups

OBJECTIVE

To prospectively evaluate the relationship between the presence or persistence of anterior knee pain (AKP) during the first 2-years following anterior cruciate ligament reconstruction (ACLR) and patellofemoral osteoarthritis (PFOA) at 15- and 20-years.

DESIGN

This study was ancillary to a long-term prospective cohort study of 221 participants following bone-patellar-tendon-bone ACLR. AKP was assessed at 1- and 2-years post-ACLR using part of the Cincinnati knee score with an additional pain location question (persistence defined as presence at both follow-ups). Radiographic PFOA (definite patellofemoral osteophyte) and symptomatic PFOA (patellofemoral osteophyte, with knee pain during past 4 weeks) was assessed at 15- and 20-years follow-up. We used generalized linear models with Poisson regression to assess the relationship between AKP and PFOA.

RESULTS

Of the 181 participants (82%) who were assessed at 15-years post-ACLR (age 39 ± 9 years; 42% female), 36 (24%) and 33 (22%) had AKP at 1- and 2-years, respectively, while 14 (8%) reported persistent AKP. Radiographic and symptomatic PFOA was observed at 15-years in 130 (72%) and 70 (39%) participants, respectively, and at 20-years in 115 (80%) and 60 (42%) participants, respectively. Neither the presence nor persistence of AKP at 1- and/or 2-years post-ACLR was associated with significantly higher risk of radiographic or symptomatic PFOA at 15- or 20-years (risk ratios <2.1).

CONCLUSIONS

Although AKP and PFOA were prevalent, AKP does not appear to be associated with long-term PFOA following ACLR.

Associations between patellofemoral joint cartilage T1ρ and T2 and knee flexion moment and impulse during gait in individuals with and without patellofemoral joint osteoarthritis

OBJECTIVE

This study aimed to investigate the associations between patellofemoral cartilage T1ρ and T2 relaxation times and knee flexion moment (KFM) and KFM impulse during gait.

METHOD

Knee magnetic resonance (MR) images were obtained from 99 subjects with and without patellofemoral joint (PFJ) osteoarthritis (OA), using fast spin-echo, T1ρ and T2 relaxation time sequences. Patellar and trochlear cartilage relaxation times were computed for the whole cartilage, and superficial and deep layers (laminar analysis). Subjects also underwent three-dimensional (3D) gait analysis. Peak KFM and KFM impulse were calculated during the stance phase. Linear regressions were used to examine whether cartilage relaxation times were associated with knee kinetics during walking while adjusting age, sex, body mass index (BMI) and walking speed.

RESULTS

Higher peak KFM and KFM impulse were significantly related to higher T1ρ and T2 relaxation times of the trochlear and patellar cartilage, with standardized regression coefficients ranging from 0.21 to 0.28. Laminar analysis showed that overall the superficial layer of patellofemoral cartilage showed stronger associations with knee kinetics. Subgroup analysis revealed that in subjects with PFJ OA, every standard deviation change in knee kinetics was related to greater increases in PFJ cartilage T1ρ and T2 (standardized coefficients: 0.29 to 0.41). Conversely, in subjects without OA, weaker relationships were observed between knee kinetics and PFJ cartilage T1ρ and T2.

CONCLUSIONS

Our findings suggest that increased peak KFM and KFM impulse were related to worse cartilage health at the PFJ. This association is more prominent in superficial layer cartilage and cartilage with morphological lesions.

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

OBJECTIVE

Patellofemoral osteoarthritis (PFOA) commonly occurs following anterior cruciate ligament reconstruction (ACLR). Our study aimed to compare knee kinematics and kinetics during a hop-landing task between individuals with and without early PFOA post-ACLR.

DESIGN

Forty-five individuals (mean ± SD 26 ± 5 years) 1-2 years post-ACLR underwent 3T isotropic MRI scans and 3D biomechanical assessment of a standardised forward hop task. Knee kinematics (initial contact, peak, excursion) in all three planes and sagittal plane kinetics (peak) were compared between 15 participants with early PFOA (MRI-defined patellofemoral cartilage lesion) and 30 participants with no PFOA (absence of patellofemoral cartilage lesion on MRI) using analysis of covariance (ANCOVA), adjusted for age, BMI, sex and the presence of early tibiofemoral OA.

RESULTS

Compared to participants without PFOA, those with early PFOA exhibited smaller peak knee flexion angles (mean difference, 95% confidence interval [CI]: -5.2°, -9.9 to -0.4; P = 0.035) and moments (-4.2 Nm/kg.m, -7.8 to -0.6; P = 0.024), and greater knee internal rotation excursion (5.3°, 2.0 to 8.6; P = 0.002).

CONCLUSIONS

Individuals with early PFOA within the first 2-years following ACLR exhibit distinct kinematic and kinetic features during a high-load landing task. These findings provide new information regarding common post-ACLR biomechanical patterns and PFOA. Since management strategies, such as altering knee load, are more effective during the early stages of disease, this knowledge will help to inform clinical management of early PFOA post-ACLR.

Immediate Effects of a Brace on Gait Biomechanics for Predominant Lateral Knee Osteoarthritis and Valgus Malalignment After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Lateral knee osteoarthritis is notably common after anterior cruciate ligament reconstruction (ACLR). While valgus bracing has been investigated as an intervention for medial knee osteoarthritis (OA), little is known about the effectiveness of varus bracing for lateral knee OA after ACLR.

PURPOSE

To determine the immediate effects of a varus unloader knee brace on gait biomechanics in people with lateral knee OA and valgus malalignment after ACLR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nineteen participants who had undergone primary ACLR 5 to 20 years previously and had symptomatic and radiographic lateral knee OA as well as valgus malalignment were included. Three-dimensional gait analyses were conducted during walking under 3 test conditions: (1) no brace, (2) unadjusted brace (sagittal plane support with neutral frontal plane adjustment), and (3) adjusted brace (sagittal plane support with varus adjustment). Knee, pelvis, hip, and ankle kinematics and moments data were statistically analyzed using repeated-measures analysis of variance (α = 0.05).

RESULTS

Compared with walking with no brace, the adjusted brace significantly increased peak knee flexion angle (mean difference [95% CI]: 3.2° [1.3° to 5.0°]) and adduction angle (1.7° [0.8° to 2.6°]) and reduced peak internal rotation angle (-3.0° [-4.0° to -2.0°]). Significant increases in peak knee flexion moment (0.14 N·m/kg [0.06 to 0.20 N·m/kg]), adduction moment (0.10 N·m/kg [0.07 to 0.14 N·m/kg]), and external rotation moment (0.01 N·m/kg [0.00 to 0.02 N·m/kg]) were observed with the adjusted brace. The adjusted brace also reduced peak hip adduction angle (-1.29° [-2.12 to -0.47]) and increased peak hip adduction (0.17 N·m/kg [0.04 to 0.31 N·m/kg]) and external rotation moments (0.09 N·m/kg [0.03 to 0.14 N·m/kg]). There were no significant differences between the adjusted and unadjusted brace conditions, except for knee internal rotation angle, where the adjusted brace produced significantly greater reductions relative to the unadjusted brace (-1.46° [-1.98 to -0.95]).

CONCLUSION

Irrespective of frontal plane adjustment, the varus unloader brace produced immediate modulations in sagittal, frontal, and transverse plane joint angles and moments in younger individuals with lateral knee OA and valgus malalignment after ACLR.

CLINICAL RELEVANCE

The varus unloader brace may have the potential to mitigate abnormal knee joint mechanics associated with the development and progression of lateral knee OA after ACLR.

Patellofemoral Osteoarthritis: Are We Missing an Important Source of Symptoms After Anterior Cruciate Ligament Reconstruction?

Anterior cruciate ligament (ACL) rupture is a well-established risk factor for knee osteoarthritis (OA). Fifty to ninety percent of individuals will develop radiographic tibiofemoral OA within a decade after ACL injury and anterior cruciate ligament reconstruction (ACLR). Although less well recognized, radiographic patellofemoral OA is present in approximately 50% of individuals at more than 10 years after ACLR. This early-onset OA and its associated pain and functional limitations pose a particular challenge to younger adults with OA compared to an older OA population. Targeted interventions need to be developed to reduce the burden of early-onset OA following ACLR. Emerging evidence suggests that such interventions should target both the patellofemoral and tibiofemoral joints.

Three-dimensional hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgum

BACKGROUND

Dynamic knee valgus in females has been associated with various knee pathologies. Abnormal 3D hip and knee kinematics contribute prominently to this presentation, and these may become more aberrant with more demanding tasks. Underlying genu valgus may also accentuate such kinematics, but this effect has never been tested. Therefore, the purpose of this study was to compare 3D hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgus malalignment. We expected abnormal kinematics to become more evident in the valgus subjects as task demands increased.

METHODS

Eighteen healthy females with genu valgum and 18 female controls with normal alignment underwent 3D motion analysis while performing walking, running, and single-limb drop-landing trials. Sagittal, frontal, and transverse plane hip and knee kinematics were compared between groups across tasks using analyses of variance and between-group effect sizes.

FINDINGS

Group differences did not generally increase with higher forces. The valgus females demonstrated decreased hip flexion (ES=0.72-0.88) and increased knee abduction (ES=0.87-1.47) across the tasks. During running and single-limb drop landing, they showed increased knee external rotation (ES=0.69-0.73). Finally, during walking, the valgus females showed increased hip adduction (ES=0.69).

INTERPRETATION

These results suggest that females with genu valgus alignment utilize aberrant hip and knee mechanics previously associated with dynamic valgus in the literature, but that these pathomechanics do not generally worsen with rising task demands. Healthy females that present with genu valgus may be natively at elevated risk for knee pathology.

Early knee osteoarthritis is evident one year following anterior cruciate ligament reconstruction: a magnetic resonance imaging evaluation

OBJECTIVE

To determine the prevalence and factors associated with knee osteoarthritis (OA) defined by magnetic resonance imaging (MRI) and specific OA features on MRI 1 year after anterior cruciate ligament reconstruction (ACLR).

METHODS

Isotropic 3.0T MRI scans were obtained for 111 participants (71 men; mean ± SD age 30 ± 8 years) 1 year after ACLR as well as for 20 age-, sex-, and activity level-matched uninjured controls. The MRI OA Knee Score was used to score specific OA features. MRI-defined tibiofemoral and patellofemoral OA was evaluated based on published criteria. Logistic regression identified factors associated with MRI-defined OA and specific OA features after ACLR.

RESULTS

Following ACLR, medial and lateral tibiofemoral OA on MRI was observed in 7 participants (6%) and 12 participants (11%), respectively, while 19 participants (17%) had patellofemoral OA on MRI. The femoral trochlea was the region most affected by bone marrow lesions (19% of participants), cartilage lesions (31% of participants), and osteophytes (37% of participants). Meniscectomy at the time of ACLR (odds ratio 6.8 [95% confidence interval 2.0-23.3]) and body mass index (BMI) >25 kg/m(2) (odds ratio 3.0 [95% confidence interval 1.3-6.9]) predicted MRI-defined tibiofemoral OA and osteophytes, respectively. Men had higher odds of patellofemoral osteophytes (odds ratio 6.3 [95% confidence interval 2.4-16.2]). No uninjured controls had tibiofemoral or patellofemoral OA on MRI, and specific OA features were uncommon.

CONCLUSION

OA 1 year following ACLR was more common than previously recognized, while being absent in uninjured control knees. The patellofemoral compartment seems to be at particular risk for early OA after ACLR, especially in men. The association with meniscectomy and BMI demonstrates the construct validity of MRI criteria.