Real-time elastography of patellar tendon in patients with auto-graft bone-tendon-bone anterior cruciate ligament reconstruction

Regional Patellar Tendon Strain in the Short- and Long-term After ACL Reconstruction Using Bone-Patellar Tendon-Bone Autograft

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) often involves harvesting a bone-patellar tendon-bone (BPTB) autograft. How graft harvest affects tendon strain across the 3 distinct regions (medial, lateral, and central) is not known.

PURPOSE

To (1) quantify strain in the 3 regions of the patellar tendon during 60% of maximum voluntary isometric contraction (MVIC) in 90° of knee flexion and (2) assess how effort level in 2 different knee joint angles (60° and 90°) impacts strain in the medial and lateral regions of the patellar tendon, in 2 cohorts of patients after ACLR using a BPTB autograft (one group <24 months after surgery and another group ≥24 months after surgery).

STUDY DESIGN

Descriptive laboratory study.

METHODS

Effort levels ranging from 20% to 100% of MVIC were performed at 90° and 60° of knee flexion on an isokinetic dynamometer, with simultaneous ultrasound imaging of tendon length to calculate regional strain. Linear mixed-effects models were used to evaluate regional strain at 60% of MVIC in 90° of knee flexion. The fixed effects of percentage of MVIC, joint angles, and time from surgery groups on patellar tendon strain were evaluated using separate models for the medial and lateral regions.

RESULTS

Fourteen participants in the short-term group (7.5 ± 1.9 months from surgery) and 15 participants in the long-term group (71.5 ± 16.5 months from surgery) were included. At 60% of MVIC in 90° of knee flexion, the short-term group demonstrated lower patellar tendon strain than the long-term group regardless of region (P < .01). The central region also had lower strain than the medial and lateral regions regardless of group (both P < .01). Finally, the rate at which strain increased with increasing effect levels differed between time from surgery groups in both medial and lateral regions.

CONCLUSION

The short-term group had lower strain in all regions of the patellar tendon after ACLR using BPTB autograft. The medial and lateral regions showed varying strain based on time from surgery and effort level. Varying knee joint angles and effort levels for graft site rehabilitation may have to be considered to target specific regions of the patellar tendon.

CLINICAL RELEVANCE

Clinicians should consider the time elapsed since surgery and the manipulation of knee angle as factors that can exert varying levels of strain on different regions of the patellar tendon after ACLR. Accelerating quadriceps strengthening to enhance strain distribution across the patellar tendon to promote tendon healing may be of benefit for optimizing postsurgery rehabilitation.

A Supratuberosity Anterior Closing-Wedge Proximal Tibial Osteotomy Increases Patellar Height: A Simulated Time Zero Uniplanar Radiographic Study

PURPOSE

To simulate the effect of supratuberosity tibial anterior closing-wedge osteotomy (ACWO) in knees with posterior tibial slope (PTS) ≥12° on patellar height when aiming for a target PTS of 5°.

METHODS

The authors retrospectively reviewed true lateral radiographs of the knees of skeletally mature patients scheduled for primary anterior cruciate ligament reconstruction and included all knees with excessive PTS (≥12°). Coordinates of 11 landmarks were digitized to calculate patellar height (Caton-Deschamps index, CDI) and mid-shaft posterior tibial slope (mPTS). The change in patellar height following a simulated supratuberosity ACWO was calculated and compared for knees with patella norma versus alta. A linear univariable regression model predicted the effect of change in mPTS on CDI.

RESULTS

In the final cohort of 83 patients, a simulated supratuberosity ACWO increased CDI from 1.13 (range, 0.73-1.74) to 1.29 (range, 0.84-1.91; P < .001). In 56 patients with patella norma, a simulated supratuberosity ACWO increased CDI from 1.02 (range, 0.73-1.19) to 1.18 (range, 0.84-1.41; P < .001), whereas in patients with patella alta, a simulated supratuberosity ACWO increased CDI from 1.33 (range, 1.20-1.74) to 1.52 (range, 1.36-1.91; P < .001). The linear regression model revealed that a 1° decrease in mPTS increased CDI by 0.02.

CONCLUSIONS

Simulation of a supratuberosity ACWO revealed that the procedure increases patellar height in all knees but did not induce significant differences in patellar height characteristics between knees with patella norma versus alta. A linear regression model revealed that a 1° decrease in mPTS could theoretically increase CDI by 0.02.

CLINICAL RELEVANCE

If preoperative planning indicates that supratuberosity ACWO would increase patellar height from norma (CDI <1.2) to alta (CDI ≥1.2), the surgeon could consider a trans- or infra-tuberosity ACWO, which is less likely to increase patellar height.

Evaluation of the knee joint with ultrasound and magnetic resonance imaging

The knee joint relies on a combination of deep and superficial structures for stability and function. Both ultrasound and high-resolution magnetic resonance imaging are extremely useful in evaluating these structures and associated pathology. This article reviews a combination of critical anatomic structures, joint abnormalities, and pathologic conditions at the knee joint, while highlighting the merits, limitations, and pitfalls of the two imaging modalities. A clear appreciation of each method paired with its relative strengths will aid in expediting diagnosis and appropriate treatment for a wide range of knee joint conditions.

Reliability of Continuous Shear Wave Elastography in the Pathological Patellar Tendon

OBJECTIVES

Patellar tendon injuries occur via various mechanisms such as overuse, or due to surgical graft harvest for anterior cruciate ligament reconstruction (ACLR). Quantified patellar tendon stiffness after injury may help guide clinical care. Continuous shear wave elastography (cSWE) allows for the assessment of viscosity and shear modulus in tendons. The reliability of the measure, however, has not been established in the patellar tendon. The purpose of this study was to investigate the interrater reliability, intrarater reliability, and between-day stability of cSWE in both healthy and pathological patellar tendons.

METHODS

Participants with patellar tendinopathy (n = 13), history of ACLR using bone-patellar tendon-bone autograft (n = 9), and with no history of patellar tendon injury (n = 13) were recruited. cSWE was performed 4 times by multiple raters over 2 days. Intraclass correlations (ICC) and minimum detectable change (MDC_95% ) were calculated.

RESULTS

Good to excellent between-day stability were found for viscosity (ICC = 0.905, MDC_95%  = 8.3 Pa seconds) and shear modulus (ICC = 0.805, MDC_95%  = 27.4 kPa). The interrater reliability measures, however, were not as reliable (ICC = 0.591 and 0.532).

CONCLUSIONS

cSWE is a reliable assessment tool for quantifying patellar tendon viscoelastic properties over time. It is recommended, however, that a single rater performs the measure as the interrater reliability was less than ideal.

Bone-Patellar Tendon-Bone Autograft Harvest Prolongs Extensor Latency during Gait 2 yr after ACLR

PURPOSE

Bone-patellar tendon-bone (BPTB) graft harvest for anterior cruciate ligament reconstruction alters patellar tendon properties, which inflict poor quadriceps neuromuscular function. BPTB autografts are associated with higher rates of posttraumatic osteoarthritis, which in turn is associated with pathological gait. The purpose of this study was to investigate the latency between the time of peak quadriceps activity and the peak knee flexion moment during gait, between those with BPTB grafts ( n = 23) and other graft types (hamstring autograft or allografts, n = 54), 5 ± 2 months and 2 yr (25 ± 3 months) after anterior cruciate ligament reconstruction. We hypothesized that longer latencies would be observed in the BPTB graft group in the involved limb. We expected latencies to shorten over time.

METHODS

Knee moments and quadriceps EMG were collected during gait, and vastus medialis, vastus lateralis, rectus femoris (RF), and quadriceps latencies were calculated. Linear mixed-effects models were used to compare latencies between graft types and over the two time points.

RESULTS

The main effects of graft type were observed for vastus medialis ( P = 0.005) and quadriceps ( P = 0.033) latencies with the BPTB graft group demonstrating longer latencies. No main effects of graft type were observed for vastus lateralis ( P = 0.051) and RF ( P = 0.080) latencies. Main effects of time were observed for RF latency ( P = 0.022).

CONCLUSIONS

Our hypothesis that the BPTB graft group would demonstrate longer extensor latency was supported. Contrary to our second hypothesis, however, latency only improved in RF and regardless of graft type, indicating that neuromuscular deficits associated with BPTB grafts may persist 2 yr after surgery. Persistent deficits may be mediated by changes in the patellar tendon's mechanical properties. Graft-specific rehabilitation may be warranted to address the long-term neuromechanical deficits that are present after BPTB graft harvest.

The effects of initial graft tension on femorotibial relationship following anatomical rectangular tunnel anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft

BACKGROUND

The purpose of this study was to elucidate the effects of the difference of initial graft tension on the femorotibial relationship on an axial plane and its chronological change following anatomical anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 63 patients who underwent anatomical ACL reconstruction were included in this study. The graft was fixed at full knee extension with manual maximum (higher graft tension; group H) and 80 N (lower graft tension; group L) pulls in 31 and 32 patients, respectively. The femorotibial positional relationship in axial computed tomography at 1 week and 1 year postoperatively were retrospectively evaluated. The side-to-side differences (SSDs) and the amount of changes of SSDs over 1 year were compared between groups.

RESULTS

The SSDs of the external rotational angle of the tibia in group H were significantly larger than those in group L at postoperative 1 week (2.7 ± 3.9° vs. 0.3 ± 3.3°; P < 0.01). The amount of internal rotational changes of SSDs of the internal-external rotational angles over 1 year in group H was significantly larger than that in group L (-3.6 ± 3.9° vs. - 0.3 ± 2.7°; P < 0.01). No significant differences were observed on the anterior-posterior translation distance and medial-lateral shift distance.

CONCLUSION

The application of higher initial graft tension resulted in excessive external rotation of the tibia to the femur at 1 week postoperatively in anatomical ACL reconstruction, and the excessive early external tibial rotation had resolved over 1 year.

Concurrent validity and intrarater reliability of two ultrasound-based methods for assessing patellar tendon stiffness

Introduction

Assessment of tendon stiffness in vivo traditionally involves maximal muscle contractions, which can be challenging in pain populations. Alternative methods are suggested, although the clinimetric properties are sparse. This study investigated the concurrent validity and the intrarater reliability of two ultrasound-based methods for assessing patellar tendon stiffness.

Methods

Patellar tendon stiffness was assessed in 17 healthy adults with (a) the dynamometer and B-mode ultrasonography method (DBUS) and (b) the strain elastography method. Correlations between the two methods were analysed using Kendall’s Tau-b. The relative reliability of both methods was evaluated using intraclass correlation coefficient (ICC). The absolute reliability was presented by Bland–Altman plots, standard error of measurement (SEM) and minimum detectable change (MDC).

Results

No correlation was found between the two methods, irrespective of reference tissue in strain elastography (Kendall’s Tau-b Hoffa = –0.01 (p = 1.00), Kendall’s Tau-b subcutis = 0.04 (p = 0.87)). Tracking of the tendon elongation in the DBUS method had good to excellent relative reliability (ICC = 0.95 (95% confidence interval – CI: 0.85–0.98)) and high absolute reliability (SEM = 0.04 mm (1%), MDC = 0.11 mm (3%)). The strain elastography method had good to excellent relative reliability, regardless of reference tissue (ICC Hoffa = 0.95 (95% CI: 0.86–0.98), ICC subcutis = 0.94 (95% CI: 0.82–0.98)), but low absolute reliability (SEM Hoffa = 0.06 (20%), MDC Hoffa = 0.18 (60%), SEM subcutis = 0.12 (41%), MDC subcutis = 0.32 (110%)).

Conclusions

No concurrent validity existed for DBUS and strain elastography, suggesting that the two methods measure different tendon properties. The overall reliability for the DBUS method was high, but the absolute reliability was low for strain elastography stiffness ratios. Therefore, the strain elastography method may not be recommended for tracking differences in patellar tendon stiffness in healthy adults.

Evaluation of patellar tendon with shear wave elastography after anterior cruciate ligament reconstruction using hamstring tendons

Objectives

This study aims to evaluate the characteristics of patellar tendons (PTs) of patients who underwent anterior cruciate ligament reconstruction (ACLR) with hamstring tendon autograft using shear wave elastography (SWE).

Patients and methods

This prospective study was conducted between August 2017 and February 2018. We performed brightness mode (B-mode) ultrasound and SWE on 21 patients (20 males, 1 female; mean age 32 years; range, 19 to 42 years) who underwent ACLR with a single-bundle transtibial technique using quadruple hamstring autografts and 14 healthy controls (13 males, 1 female; mean age 35 years; range, 25 to 47 years). Length and thickness of the PT were evaluated with B-mode ultrasound, while elasticity values were evaluated with SWE in the patient and control groups.

Results

The mean SWE value of the patient group on the operated side was 25.30 (min-max=16.60-46.20) and on the non-operated side 23.20 (min-max=12.40-44). There were no statistically significant differences regarding PT elasticity, thickness, or length between the groups (p>0.05).

Conclusion

There were no differences regarding elasticity, length, or thickness between the operated and healthy knees detected with SWE. Upcoming research should focus on tendon biopsy and biochemical analyses for the identification of possible intrastructural changes of the tendon due to collagen synthesis after ACLR with hamstring autograft.

Ultrasonic strain elastography for detecting abnormalities in the supraspinatus tendon: an intra- and inter-rater reliability study

OBJECTIVES

The reliability of ultrasonic strain elastography (SEL) used to detect abnormalities in the supraspinatus tendon is unclear. Thus, the aim of this study was to investigate the reliability of SEL in the supraspinatus tendon.

DESIGN

An intra-rater and inter-rater reliability study.

SETTING

A single-centre study conducted at the University of Southern Denmark.

PARTICIPANTS

Twenty participants with shoulder pain and MRI-verified supraspinatus tendinosis and 20 asymptomatic participants (no MRI).

PRIMARY AND SECONDARY OUTCOME MEASURES

Raw values (RAW) and ratios (deltoid muscle (DELT) and gel pad (GEL) as reference tissues) were calculated and mean values of measurements from three regions of the supraspinatus tendon were reported. Colour scale ratings and number of yellow/red lesions from the three areas were also included.

RESULTS

Intra-rater reliability showed intraclass correlation coefficients (ICCs) for RAW, DELT and GEL: 0.97 (minimal detectable change (MDC): 0.28 (6.36% of the mean)), 0.89 (MDC: 2.91 (20.37%)) and 0.73 (MDC: 1.61 (58.82%)), respectively. The ICCs for inter-rater reliability were 0.89 (MDC: 0.47 (10.53%)), 0.78 (MDC: 3.69 (25.51%)) and 0.70 (MDC: 1.75 (62.63%)), respectively.For colour scale ratings, intra-rater reliability (linear weighted kappa) ranged from 0.76 to 0.79, with the inter-rater reliability from 0.71 to 0.81. For the number of lesions, intra-rater reliability ranged from 0.40 to 0.82 and inter-rater reliability from 0.24 to 0.67.

CONCLUSIONS

Intra-rater and inter-rater reliability were excellent for raw values and for ratios with deltoid muscle as the reference tissue, and good for ratios with gel pad as the reference tissue. The reliability of colour scale ratings was substantial-to-almost perfect, and for the number of lesions fair-to-almost perfect.Although high reliability was found, validity and responsiveness of these elastographic methods needs further investigation.

ETHICS APPROVAL

The study protocol was approved by the Ethics Committee for the Region of South Denmark (S-20160115) and reported to the Danish Data Protection Agency (2014-41-3266).

Shear wave elastography of the healing human patellar tendon following ACL reconstruction

PURPOSE

Anterior cruciate ligament (ACL) ruptures are common and are frequently reconstructed using a patellar tendon (PT) autograft. Unfortunately, the time course of PT healing after ACL reconstruction is not particularly well understood. Thus, the primary objective of this study was to use shear wave elastography (SWE) to evaluate the extent to which shear wave speed (SWS) is associated with time after ACL reconstruction.

METHODS

Longitudinal SWE images were acquired from lateral, central, and medial regions of the PT from two groups: 30 patients who had undergone ACL reconstruction with a PT autograft within the preceding 40 months, and 30 age-matched asymptomatic control subjects. SWE images were acquired at 20° and 90° of passive flexion from both knees. In each subject group, statistical analyses assessed changes in mean SWS with time post-surgery, as well as differences in mean SWS between PT regions and limbs.

RESULTS

In the ACL reconstruction patients, mean SWS increased with time post-surgery in the lateral region of the involved knee (p = 0.025) and decreased with time post-surgery in the central region of the contralateral knee (p = 0.022).

CONCLUSION

The findings suggest that there is an association between the mechanical properties of the PT and time post-surgery in both the involved and contralateral limbs after ACL reconstruction. These changes are likely due to maturation of the donor site tissue and changes in gait/loading patterns following ACL rupture and reconstruction.

LEVEL OF EVIDENCE

Level II - Prospective Cohort.

Relationships between Quadriceps Tendon Elasticity and Knee Flexion Angle in Young Healthy Adults

Background and objectives: Although tendon elasticity by elastography is useful for diagnosing tendon disorders and planning rehabilitation regimens of the tendon, there are few reports on the quadriceps tendon. Moreover, relationships between the quadriceps tendon elasticity and knee angle have not been investigated. The purpose of this study was to clarify the relationship between quadriceps tendon elasticity and knee flexion angle in young healthy adults using elastography, and to investigate the difference in elasticity by sex and leg dominance. Materials and Methods: A total of 40 knees in 20 young healthy adults were included in this study (age: 25.5 (23.3⁻27.5) years). At knee flexion of 30°, 60°, and 90°, quadriceps tendon elasticity was measured using ShearWave™ Elastography during the ultrasound examination. Results: There were significant differences in the elasticity between all angles (p < 0.001). Elasticity was increased more at 60° than at 30° and at 90° than at 60°. Elasticity in men was higher than that in women at 60° (p = 0.029). There were no differences (p = 0.798) in elasticity at each angle between the dominant and non-dominant legs. Conclusions: The quadriceps tendon elasticity increased according to the knee flexion angle in young healthy adults. Moreover, elasticity was affected by sex, but not by leg dominance. Clinically, in a rehabilitation regimen, attention should be paid to exercises that could increase stiffness accompanying flexion of the knee to avoid further tendon damage as risk management in the acute phase.

Real-time sonoelastography: principles and clinical applications in tendon disorders. A systematic review

Background

Sonoelastography (SE) is a new ultrasound-based method adopted in an increased number of scientific reports to analyse normal and pathological tendons. The aim of this study is to provide a systematic overview of clinical applications of SE in normal and pathological tendons.

Methods

A systematic research of PubMed, Ovid, and Cochrane Library electronic databases was performed according to PRISMA guideline. Two Authors searched and evaluated the articles independently; a third Author was involved to solve any disagreement. The Oxford Level of Evidence (LoE) was used to assess each article.

Results

There is an increasing interest in the application of SE in the evaluation of healthy and diseased tendons. Many different tendons are amenable for SE evaluation, such as the Achilles and patellar tendons, rotator cuff, common extensor tendons, quadriceps tendon, and the plantar fascia.

Conclusion

SE appears to be a very useful diagnostic tool, in particular in tendon pathology. This is a dynamic examination, provides an immediate evaluation of the tissue elasticity, and may be useful in recognizing tendon abnormalities and in implementing the information available with conventional US.

Level of evidence

IV.

Effects of initial graft tension on femoral tunnel widening after anatomic anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft

INTRODUCTION

The effects of initial graft tension upon tunnel widening (TW) following anatomic anterior cruciate ligament (ACL) reconstruction have not been elucidated. The purpose of this study was to retrospectively investigate the effect of two different graft-tensioning protocols upon femoral TW following anatomic ACL reconstruction using a bone-patellar tendon-bone (BPTB) graft and a three-dimensional (3D) computed tomography (CT) model.

METHODS

Forty-three patients who underwent isolated ACL reconstruction using BPTB grafts were included in this study. In 18 out of the 43 patients, the graft was fixed at full knee extension with manual maximum pull (Group H). These patients were compared with 25 patients in whom the BPTB graft was fixed at full knee extension with 80-N pull (Group L). Tunnel aperture area was measured using 3D CT 1 week and 1 year postoperatively, thus enabling us to calculate the percentage change in the area of femoral tunnel aperture. Clinical assessment was performed 1 year postoperatively, corresponding to the time period of CT assessment, and involved the evaluation of Lysholm score, anterior knee stability using a KneeLax3 arthrometer, and the pivot-shift test.

RESULTS

When measured at 1 year postoperatively, the mean area of the femoral tunnel aperture had increased by 78.6 ± 36.8% in Group H when compared with at 1 week postoperatively, whereas that of Group L had increased by 27.7 ± 32.3%. Furthermore, TW (%) in Group H was significantly greater than that of Group L (P < 0.001). No significant differences were detected between the two groups with regard to any of the clinical outcomes evaluated.

CONCLUSION

High levels of initial graft tension resulted in greater TW of the femoral tunnel aperture following anatomical ACL reconstruction using BPTB grafts. However, such levels of graft tension did not affect clinical outcome.

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.