Patellofemoral kinematic characteristics in anterior cruciate ligament deficiency and reconstruction

Quantitative MRI Analysis of Patellofemoral Joint Cartilage Health 2-Years Postoperative Anterior Cruciate Ligament Reconstruction and Lateral Extra-Articular Tenodesis

BACKGROUND

The addition of an iliotibial band-based lateral extra-articular tenodesis (LET) to anterior cruciate ligament (ACL) reconstruction (ACLR) has been shown to reduce failure rates. However, there are concerns as to the potential overconstraint of tibiofemoral kinematics that may increase the risk of cartilage degradation. To date, no clinical study has investigated the effect of LET on patellofemoral joint articular cartilage health.

HYPOTHESIS

It was hypothesized that at 2 years postoperatively, (1) the addition of LET at the time of ACLR would have no effect on cartilage health on magnetic resonance imaging (MRI), and (2) higher cartilage relaxation values would be associated with worse patient-reported and functional outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A subset of patients from the STABILITY 1 randomized controlled trial were included. All patients underwent primary ACLR with a hamstring autograft. Patients were randomized to either LET augmentation or not. Cartilage status in the patellofemoral joint between the ACLR group and ACLR+LET group was compared using 2-year postoperative quantitative MRI and the ACL osteoarthritis scores of both the surgical and the contralateral nonsurgical knees. Objective functional outcomes and patient-reported outcome measures (PROMs) were attained.

RESULTS

A total of 92 patients (43 patients in the ACLR group; mean age, 18.9 ± 3.2 years; 60.5% female; and 49 patients in the ACLR+LET group; mean age, 18.7 ± 3.2 years, 63.3% female) were included. No significant differences were seen in the mean values (ms) for adjusted T1ρ/T2 relaxation times in the medial patella (47.8/42.2 vs 47.3/43.2), central patella (45.5/42.5 vs 44.1/42.7), lateral patella (48.2/43.5 vs 47.3/43.0), medial trochlea (54.7/50.9 vs 56.4/50.9), central trochlea (53.3/51.1 vs 53.1/52.0), and lateral trochlea (54.9/52.1 vs 53.9/52.6) between the ACLR and ACLR+LET groups. No difference in overall ACL osteoarthritis scores was observed (P = .99). An increase in medial patellar T2 relaxation times was associated with a decreasing International Knee Documentation Committee score (P = .046), Knee injury and Osteoarthritis Outcome Score (KOOS) Symptoms subscale score (P = .01), and total KOOS (P = .01).

CONCLUSION

There was no statistical difference in patellofemoral cartilage health between knees 2 years after primary ACLR with hamstring tendon autograft with or without LET. Statistically significant correlations were found between quantitative MRI relaxation times, functional outcome scores, and PROMs; however, the correlations were weak and the clinical significance is unknown.

REGISTRATION

NCT02018354 (ClinicalTrials.gov identifier).

Characterization of the CT-based risk factors for concomitant patellofemoral instability in patients with anterior cruciate ligament injury

OBJECTIVES

Underestimation of concomitant patellofemoral instability in patients with anterior cruciate ligament (ACL) injury has aroused extensive attention. However, the characteristics of the combined injury is not well recognized. Hence, we aimed to characterize the features of the combined injury, and determine the radiographic risk factors.

METHODS

Fifteen radiological parameters were identified after discussion and pilot-tested. Radiographic measurements were compared using the analysis of variance model with Tukey post hoc analysis. A stepwise binomial logistic regression was performed and a nomogram model combining the significant risk factors was created. The model performance was validated by C-index, calibration plot, and decision curve.

RESULTS

A total of 204 patients (mean [SD] age, 25.1 [6.7] years; 108 [52.9%] male) were included. The final model was updated through regression analysis using 4 parameters as significant risk factors: lateral femoral condyle ratio (OR (95% CI), 1.194 (1.023 to 1.409)), medial anterior tibial subluxation (mATS) (OR (95% CI), 1.234 (1.065 to 1.446)), medial posterior plateau tibial angle (mPPTA) (OR (95% CI), 1.266 (1.088 to 1.500)), and trochlear depth (OR (95% CI), 0.569 (0.397 to 0.784)). C-index for the nomogram was 0.802 (95% CI, 0.731 to 0.873) and was confirmed to be 0.784 through bootstrapping validation. Calibration plot established a good agreement between prediction and observation. Decision curve analysis showed that if threshold probability was over 10%, using the nomogram adds more benefit than either all or none scheme.

CONCLUSIONS

Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are strong adverse predictors of patellofemoral instability in patients with ACL injury.

CLINICAL RELEVANCE

This study characterizes the radiological features of the combined injury. Patellofemoral instability should be noted when treating ACL injuries.

KEY POINTS

• The radiological characteristics of the combined ACL injury and patellofemoral instability is not well recognized. • Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are predominant risk factors for patellofemoral instability in patients with ACL injury. • Patellofemoral instability should be noted when treating ACL injuries.

Persistent underloading of patellofemoral joint following hamstring autograft ACL reconstruction is associated with cartilage health

OBJECTIVE

To determine the longitudinal changes of patellofemoral joint (PFJ) contact pressure following anterior cruciate ligament reconstruction (ACLR). To identify the associations between PFJ contact pressure and cartilage health.

DESIGN

Forty-nine subjects with hamstring autograft ACLR (27 males; age 28.8 [standard deviation, 8.3] years) and 19 controls (12 males; 30.7 [4.6] years) participated. A sagittal plane musculoskeletal model was used to estimate PFJ contact pressure. A combined T1ρ/T2 magnetic resonance sequence was obtained. Assessments were performed preoperatively, at 6 months, 1, 2, and 3 years postoperatively in ACLR subjects and once for controls. Repeated Analysis of Variance (ANOVA) was used to compare peak PFJ contact pressure between ACLR and contralateral knees, and t-tests to compare with control knees. Statistical parametric mapping was used to evaluate the associations between PFJ contact pressure and cartilage relaxation concurrently and longitudinally.

RESULTS

No changes in peak PFJ contact pressure were found within ACLR knees over 3 years (preoperative to 3 years, 0.36 [CI, -0.08, 0.81] MPa), but decreased over time in the contralateral knees (0.75 [0.32, 1.18] MPa). When compared to the controls, ACLR knees exhibited lower PFJ contact pressure at all time points (at baseline, -0.64 [-1.25, -0.03] MPa). Within ACLR knees, lower PFJ contact pressure at 6 months was associated with elevated T2 times (r = -0.47 to -0.49, p = 0.021-0.025).

CONCLUSIONS

Underloading of the PFJ following ACLR persists for up to 3 years and has concurrent and future consequences in cartilage health. The non-surgical knees exhibited normal contact pressure initially but decreased over time achieving limb symmetry.

A combined anterior cruciate ligament/Meniscal injury alters the patellofemoral joint kinematics of anterior cruciate ligament-deficient knees during a single-leg lunge exercise: A cross-sectional study

Anterior cruciate ligament deficiency (ACLD) is often accompanied by concomitant meniscal tears. The study aimed to assess the kinematic alterations of patellofemoral joint (PFJ) in anterior cruciate ligament deficiency knees with or without meniscal tears during a single-leg lunge. Sixty unilateral anterior cruciate ligament deficiency patients were recruited for the study, including 15 isolated anterior cruciate ligament deficiency patients (group 1), 15 anterior cruciate ligament deficiency patients with medial meniscal tears (group 2), 15 patients with lateral meniscal tears (group 3) and 15 patients with combined medial/lateral meniscal tears (group 4). The patellofemoral joint kinematics were determined by a single fluoroscopic image system. Patellofemoral joint kinematics of contralateral anterior cruciate ligament-intact (ACLI) and anterior cruciate ligament deficiency knees were compared. With or without meniscal tears, anterior cruciate ligament deficiency knees had significantly smaller patellar flexion than the anterior cruciate ligament-intact knees (∼5°–10°; p < 0.05). anterior cruciate ligament deficiency knees had more patellar lateral tilting by approximately 1°–2° than the anterior cruciate ligament-intact knees (p < 0.05) in groups 2, 3, and 4. anterior cruciate ligament deficiency groups with medial meniscal deficiencies showed consistent increased lateral patellar translations (2–4 mm) compared to the anterior cruciate ligament-intact group during a single-leg lunge. The results indicate that meniscal tears alter anterior cruciate ligament deficiency patients’ patellofemoral joint kinematics and the types of the meniscal injuries also affect the patellofemoral joint kinematics. Considering the varying effects of meniscal tears on the patellofemoral joint kinematics, specific treatments for anterior cruciate ligament deficiency patients with meniscal tears should be proposed in some closed kinetic chain (CKC) exercise programs, such as single-leg lunge.

Patellofemoral contact forces after ACL reconstruction: A longitudinal study

Osteoarthritis (OA) development after ACL reconstruction (ACLR) is common. Patellofemoral OA after ACLR is as prevalent as tibiofemoral OA; however, few have explored the mechanisms leading to disease development in this compartment. Biomechanical alterations may be one mechanism responsible for post-traumatic knee OA. Patellofemoral contact forces during dynamic tasks, such as running and single leg hops, have been assessed at return to sport and later time points. The results of these studies, however, contradict each other, are only cross-sectional in nature, and are limited to specific points in time within the movement pattern. The purpose of this study was to assess patellofemoral contact forces 3, 6, and 24 months after ACLR during level walking over the entirety of the movement pattern. Patellofemoral contact forces were calculated after determination of muscle forces from a validated, subject-specific, EMG-driven neuromusculoskeletal model. Statistical parametric mapping was used to compare patellofemoral contact forces between limbs and across time points. Patellofemoral underloading of the involved limb (vs. uninvolved) was present at 3 months (p < 0.001 from 7 to 30% of stance) and 6 months (p = 0.001 from 11 to 23% of stance and p = 0.025 from 27 to 32%) after ACLR but was resolved by 24 months. Both limbs' load increased from 3 to 6 months. The involved limb displayed relatively consistent loads from 6 months onward, while the uninvolved limb's decreased back down towards their 3-month values. Overall, these results suggest that early patellofemoral underloading exists after ACLR and may be leading to patellofemoral OA development.

Longitudinal Changes of Patellar Alignment Before and After Anterior Cruciate Ligament Reconstruction With Hamstring Autograft

BACKGROUND

Evidence has suggested that after anterior cruciate ligament (ACL) reconstruction (ACLR), individuals exhibit patellar malalignment; however, it is unknown if patellar alignment changes over time.

PURPOSE

To examine the longitudinal changes in patellar alignment before, 6 months after, and 3 years after ACLR and to compare these variations, if present, with patellar alignment in controls.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 35 patients who had ACLR using hamstring autograft (19 male; age, 29.9 ± 7.7 years; body mass index, 23.8 ± 2.5) and 20 controls (13 male; age, 30.4 ± 4.8 years; body mass index, 24.3 ± 2.7) participated. All patients underwent bilateral knee magnetic resonance imaging with the knee in extension and 30° of flexion using sagittal T2-weighted, fat-saturated fast spin-echo images to assess patellar alignment in 6 degrees of freedom: anterior-posterior, medial-lateral, and superior-inferior translations; flexion; tilt; and spin. Patients who had ACLR were assessed before (ACL-deficient state) and 6 months and 3 years after ACLR, while control participants were only assessed once. One-way repeated-measures analysis of variance was used to examine patellar alignment across time in the ACLR group. If changes were present, the independent t test was carried out to examine the differences between ACLR knees and control knees.

RESULTS

In the knee-extended condition, greater patellar lateral displacement was observed at the ACL-deficient state and 6 months after ACLR compared with 3 years after ACLR within the ACLR group (P < .001 and P = .043, respectively) and compared with the control group (P = .001 and P = .039, respectively). Greater patellar lateral tilt was observed at the ACL-deficient state compared with 3 years after ACLR (P = .003) and compared with the control group (P = .018). In the knee-flexed condition, greater anterior displacement was observed at the ACL-deficient state compared with 3 years after ACLR (P = .001) and compared with the control group (P = .011), and it was also observed at 6 months after ACLR compared with the control group (P = .019). Less lateral spin was observed at the ACL-deficient state (P = .042) and 6 months after ACLR (P = .004) compared with 3 years after ACLR and compared with the control group (P = .004 for both). No patellar alignment measures in the ACLR knees at 3 years were significantly different from those of the controls.

CONCLUSION

Patellar malalignment in individuals before and after ACLR subjected to longitudinal changes, and the differences in alignment between ACLR and controls diminished over 3 years.

In vivo Compositional Changes in the Articular Cartilage of the Patellofemoral Joint following Anterior Cruciate Ligament Reconstruction

OBJECTIVE

To compare T1ρ relaxation times of the medial and lateral regions of the patella and femoral trochlea at 6 and 12 months post-anterior cruciate ligament reconstruction (ACLR) on the ACLR and contralateral limb. Greater T1ρ relaxation times are associated with a lesser proteoglycan density of articular cartilage.

METHODS

Twenty individuals (11 males, 9 females; age=22±3.9yrs; mass=76.11±13.48kg; height=178.32±12.32) who underwent a previous unilateral ACLR using a patellar tendon autograft. Magnetic resonance images from both limbs were acquired at 6 and 12 months post-ACLR. Voxel by voxel T1ρ relaxation times were calculated using a five-image sequence. The medial and lateral regions of the femoral trochlea and patellar articular cartilage were manually segmented on both limbs. Separate limb (ACLR and contralateral limb) by time (6-months and 12-months) ANOVAs were performed for each region (P<0.05).

RESULTS

For the medial patella and lateral trochlea, T1ρ relaxation times increased in both limbs between 6 and 12-months post-ACLR (medial patella: P=0.012; lateral trochlea: P=0.043). For the lateral patella, T1ρ relaxation times were significantly greater on the contralateral limb compared to the ACLR limb (P=0.001). The T1ρ relaxation times of the medial trochlea on the ACLR limb were significantly greater at 6 (P=0.005) and 12-months (P<0.001) compared to the contralateral limb. T1ρ relaxation times of the medial trochlea significantly increased from 6 to 12-months on the ACLR limb (P=0.003).

CONCLUSION

Changes in T1ρ relaxation times occur within the first 12 months following ACLR in specific regions of the patellofemoral joint on the ACLR and contralateral limb.

An Anatomical-Based Subject-Specific Model of In-Vivo Knee Joint 3D Kinematics From Medical Imaging

Biomechanical models of the knee joint allow the development of accurate procedures as well as novel devices to restore the joint natural motion. They are also used within musculoskeletal models to perform clinical gait analysis on patients. Among relevant knee models in the literature, the anatomy-based spatial parallel mechanisms represent the joint motion using rigid links for the ligaments’ isometric fibres and point contacts for the articular surfaces. To customize analyses, therapies and devices, there is the need to define subject-specific models, but relevant procedures and their accuracy are still questioned. A procedure is here proposed and validated to define a customized knee model based on a spatial parallel mechanism. Computed tomography, magnetic resonance and 3D-video-fluoroscopy were performed on a healthy volunteer to define the personalized model geometry. The model was then validated by comparing the measured and the replicated joint motion. The model showed mean absolute difference and standard deviations in translations and rotations, respectively of 0.98 ± 0.40 mm and 0.68 ± 0.29 ° for the tibia–femur motion, and of 0.77 ± 0.15 mm and 2.09 ± 0.69 ° for the patella–femur motion. These results show that accurate personalized spatial models of knee kinematics can be obtained from in-vivo imaging.