Kinematic factors associated with anterior knee pain during common aggravating activities: a systematic review

Males with patellofemoral pain have altered movements during step-down and single-leg squatting tasks compared to asymptomatic males: A cross-sectional study

Background and Aims

Patellofemoral pain (PFP) is common in males, causing reduced physical activity and chronic pain. One proposed cause of PFP is aberrant biomechanics during tasks loading the patellofemoral joint. Consistent evidence exists for females with PFP, but it is uncertain if males with PFP have altered biomechanics. This study investigated the kinematics of males with PFP compared to pain-free males during forward step-down (StDn) and single-leg squat (SLSq).

Methods

A cross-sectional study including 40 males aged 20-39 years (28.28 ± 5.46) was conducted (20 PFP, 20 pain-free). Participants performed StDn and SLSq while motion was captured with a video-based motion capture system (Motion Analysis Corporation). Triplanar peak angles and angular ranges of motion (ROM) of the trunk, pelvis, and weight-bearing hip, knee, and ankle were dependent variables. Mixed-model ANOVA tests were used to determine the presence of significant interactions and main effects of group and task.

Results

Males with PFP had significantly lower peak knee adduction angles compared to pain-free males (p = 0.01). Significant group x task interactions were found for hip and pelvis ROM (p < 0.05). PFP participants had increased hip and pelvis ROM during StDn in the frontal and transverse planes but reduced or nearly equal ROM for these variables during SLSq. Peak hip adduction, hip internal rotation, contralateral pelvic drop and anterior tilt, trunk flexion, and ankle dorsiflexion were greater during StDn compared to SLSq (p < 0.05). ROM of the hip, pelvis, trunk, and ankle were greater during StDn compared to SLSq (p < 0.05).

Conclusion

Males with PFP had reduced peak knee adduction angles in StDn and SLSq. Males with PFP demonstrated increased hip and pelvis ROM during StDn versus SLSq, particularly in the frontal and transverse planes. Clinicians should consider StDn as a clinical test since aberrant movement may be easier to detect than in SLSq.

Assessing biomechanics and associated factors in individuals with patellofemoral pain in a clinical setting: A qualitative study based on interviews with expert clinicians

OBJECTIVES

To explore the perspectives of ten clinicians from different medical disciplines with experience in managing PFP on how to conduct biomechanical assessments in individuals with PFP in a clinical setting.

METHODS

An explorative qualitative design was used to explore the perspectives of ten clinicians with at least five years of experience managing patients with patellofemoral pain. A series of semi-structured interviews were done over Zoom video chat. The participants were from six different medical disciplines (physiotherapy, biokinetics, podiatry, sport science, sports medicine, orthopaedic surgery). Data was analysed thematically.

RESULTS

Four main themes emerged from the data. These were: 1) biomechanical contributing factors that clinicians routinely screen for in patients with PFP; 2) relevant functional activities for biomechanical screening in patients with PFP; 3) conducting gait analysis assessments in a clinical setting; and 4) challenges of biomechanical assessment in patients with PFP. The clinicians expressed conflicting opinions on the usefulness of clinical gait analysis. The clinicians questioned the clinical applicability of some of the biomechanical factors identified as important in the evidence.

CONCLUSIONS

It is important for clinicians to include the biomechanical assessment of functional activities linked to pain when managing patients with PFP. However, some of the biomechanical factors identified in the evidence are too difficult to observe without 3D movement analysis equipment and should not be considered clinically relevant. Expert clinical opinion is important to provide contextual information when addressing biomechanics in individuals with PFP.

Concurrent validity and within-session reliability of gait kinematics measured using an inertial motion capture system with repeated calibration

INTRODUCTION

Wearable inertial measurement units (IMUs) enable gait analysis in the clinic, but require calibrations that may affect subsequent gait measurements. This study assessed concurrent validity and within-session reliability of gait kinematics measured by a frequently calibrated IMU-based system. Calibration pose accuracy and intra-rater repeatability, and IMU orientation tracking accuracy, were additionally quantified.

METHODS

Calibration poses and gait were recorded in 15 women using IMUs and optical motion capture (OMC) (reference standard) simultaneously. Participants performed six consecutive trials: each comprising a calibration pose and a walk. IMU tracking was assessed separately (once-off) using technical static and dynamic tests. Differences of > 5° constituted clinical significance.

RESULTS

Concurrent validity for gait revealed clinically significant between-system differences for sagittal angles (root-mean-square error [RMSE] 6.7°-15.0°; bias -9.3°-3.0°) and hip rotation (RMSE 7.9°; bias -4.2°). After removing modelling offsets, differences for all angles (except hip rotation) were < 5°. Gait curves correlated highly between systems (r > 0.8), except hip rotation, pelvic tilt and -obliquity. Within-session reliability of IMU-measured gait angles was clinically acceptable (standard error of measurement [SEM] < 5°). Calibration poses were repeatable (SEM 0.3°-2.2°). Pose accuracy revealed mean absolute differences (MAD) < 5° for all angles except sagittal ankle, hip and pelvis. IMU tracking accuracy demonstrated RMSE ≤ 2.0°.

CONCLUSION

A frequently calibrated IMU system provides reliable gait measurements; comparing highly to OMC after removing modelling differences. Calibration poses can be implemented accurately for most angles and consistently. IMU-measured gait data are clinically useful and comparable within participants, but should not be compared to OMC-measured data.

"Dynamic knee valgus" - Are we measuring what we think we're measuring? An evaluation of static and functional knee calibration methods for application in gait and clinical screening tests of the overhead squat and hurdle step

BACKGROUND

"Dynamic knee valgus" has been identified as a risk factor for significant knee injuries, however, the limits and sources of error associated with existing 3D motion analysis methods have not been well established.

RESEARCH QUESTION

What effect does the use of differing static and functional knee axis orientation methods have on the observed knee angle outputs for the activities of gait, overhead squatting and a hurdle step?

METHODS

A pre-existing dataset collected from one season (September 2015-May 2016) as part of a prospective observational longitudinal study was used. A secondary analysis of data for 24 male footballers, from a single British University football team, was conducted in order to evaluate the effect of static (conventional gait model) and dynamic (constrained and unconstrained mDynaKAD) methods on knee joint kinematics for flexion-extension and valgus-varus angles.

RESULTS

No single calibration method consistently achieved both the highest flexion and lowest valgus angle for all tests. The constrained and unconstrained mDynaKAD methods achieved superior alignment of the knee medio-lateral axis compared to the conventional gait model, when the movement activity served as its own calibration. The largest mean difference between methods for sagittal and coronal plane kinematics was less than 4° and 14° respectively. Cross-talk could not account for all variation within the results, highlighting that soft tissue artefact, associated with larger muscle volumes and movements, can influence kinematics results.

SIGNIFICANCE

When considering the trade-off between achieving maximum flexion and minimal valgus angle, the results indicate that the mDynaKAD methods performed best when the selected movement activity served as its own calibration method for all activities. Clinical decision making processes obtained through use of these methods should be considered in light of the model errors associated with cross-talk and effect of soft tissue artefact.

The effect of an individualised functional retraining intervention on pain, function and biomechanics in participants with patellofemoral pain: a series of n of 1 trial

[Purpose] To determine the effect of an individualised functional retraining intervention on pain, function, kinematics and self-reported recovery in participants with PFP. [Participants and Methods] Thirty-one participants with unilateral PFP between the ages of 14–40 were included. Data collection and treatment sessions were conducted at the Tygerberg 3D Motion Analysis Laboratory and Physiotherapy Clinic at the University of Stellenbosch Medical School in Cape Town, South Africa. Participants underwent motion analysis testing pre- and post-intervention and attended physiotherapy weekly for a 6-week individualised intervention. [Results] Thirty of the thirty-one participants (96.8%) demonstrated improved pain levels (NPRS) post intervention. Participants demonstrated a statistically significant improvement in function (AKPS) immediately post intervention and continued to improve with greater functional scores at 6-month follow up. Fifteen participants (48.4%) rated themselves as fully recovered on a 7-point Likert scale at 6-month follow up. Nineteen of the 31 participants (61.3%) demonstrated a clinically significant improvement in their priority kinematic outcome post intervention. [Conclusion] Individualised functional retraining may improve pain, function, kinematics and long-term recovery in participants with PFP presenting with kinematic contributing factors. Clinicians need to be educated on common biomechanical contributing factors and how to tailor treatment accordingly.