Patellar Tendon Reconstruction Using Autologous Hamstring Tendons for the Treatment of Extensive Patellar Tendon Ossification

Background

Extensive patellar tendon ossification is very uncommon and requires surgical intervention when ossification significantly affects knee function. While various approaches and grafts are available for reconstructing ruptured patellar tendons, there is a paucity of literature regarding the management of joint ankylosis due to severely ossified patellar tendons.

Case Presentation

This is a case involving an extensively ossified patellar tendon after patellar and tibial tuberosity fracture fixation. Reconstruction of the patellar tendon was performed using ipsilateral semitendinosus and gracilis autografts. At the latest follow‐up of 12 months, the patient achieved knee flexion up to 120° with a slight extension lag and resumed daily activities.

Conclusions

Autograft hamstring reconstruction of the patellar tendon is suitable for extensive heterotopic ossification of the patellar tendon, resulting in significant improvement in postoperative knee function. Similar patients may be referred for this reconstruction technique.

Biomechanics of hamstring tendon, quadriceps tendon, and bone-patellar tendon-bone grafts for anterior cruciate ligament reconstruction: a cadaveric study

PURPOSE

The three most commonly used autografts for anterior cruciate ligament reconstruction (ACL) are: bone-patellar tendon-bone (BTB), hamstring tendons (HT), and quadriceps tendon (QT). A cadaveric study was performed to determine if there were any differences in mechanical and structural properties under biomechanical testing.

METHODS

Twenty-seven graft specimens were harvested from 9 human cadaveric legs. Mean donor age was 75.2 years (range 53-85 years). Twenty-two specimens (8 HT, 7 QT, and 7 BTB) completed cyclic preconditioning from 50 to 800 N for 200 cycles and a load to failure test at an extension rate of 1 mm/s. Structural and mechanical properties of BTB, HT, and QT grafts were compared using a one-way ANOVA and Tukey's honest significant difference.

RESULTS

There was no difference in the ultimate load to failure (N) across all 3 graft types (p = 0.951). Quadriceps tendon demonstrated greater cross-sectional area (mm²) when compared to both HT and BTB (p = 0.001) and was significantly stiffer (N/mm) than HT but not BTB (p = 0.004). Stress (N/mm²) of the HT at ultimate load was greater than QT but not BTB (p = 0.036). Elastic modulus (MPa) of HT was greater than both QT and BTB (p = 0.016).

CONCLUSION

There was no difference in the ultimate load to failure of BTB, HT, and QT grafts harvested from the same specimens. All 3 grafts had similar loads to failure with a significant increase in stiffness when compared to the native ACL. Furthermore, QT demonstrated more favourable structural properties compared to HT and BTB with greater cross-sectional area to both HT and BTB and greater stiffness compared to HT.

Alteration of patellar tendon morphology in patellofemoral instability (trochlear dysplasia)

INTRODUCTION

Trochlear Dysplasia (TD) is a condition that is characterized by the presence of an abnormally shaped trochlear groove, which hinders the patellofemoral joint (PFJ) stability. PFJ stability is determined by static and dynamic structures around the knee joint. We analysed whether the patellar tendon morphology is altered in patients with patellofemoral instability in Trochlear Dysplasia (TD).

MATERIAL AND METHODS

Magnetic Resonance Imaging (MRI) studies for 50 consecutive knees with TD and 50 consecutive knees with normal PFJ morphology were obtained for evaluation. For each MRI study, the cross-sectional area (CSA) of the medial and lateral components of the patellar tendon was measured and used to calculate the cross-sectional area ratio (CSAR) by two readers.

RESULTS

There was a statistically significant difference in the CSAR of the lateral-to-medial components of the patellar tendon between knees with normal PFJ morphology and knees with TD (one way ANOVA, F (4,95) = 7.743, p < 0.001). Pairwise comparisons amongst the Dejour subtypes of TD, revealed a statistically significance difference (p < 0.05) in the CSAR ratio between patients with normal PFJ morphology, and patients with type A (p = 0.007) and type C, TD. There was moderate correlation between the readers on Intraclass Correlation Coefficient (ICC) analysis (ICC- 0.7).

CONCLUSION

Our findings reveals hypertrophy of the medial part of the patellar tendon in patients with PFJ instability and TD. These differences could reflect the dynamic compensatory changes occurring at the PFJ to counteract the laterally directed instability vectors found in this condition.

Morphometric analysis of patella and patellar ligament: a cadaveric study to aid patellar tendon grafts

PURPOSE

Morphometric analysis of the patella and the patellar ligament is crucial in diagnosing and surgical corrections of knee injuries and patellofemoral joint disorders. Dimensions of the patella and the patellar ligament are frequently used in implant design and ACL reconstruction. This study aims to obtain detailed morphometric data on the patellar ligament and its localization based on gross anatomical dissections in the adult cadavers.

METHODS

The present study consisted of 50 lower limbs from formalin-fixed male adult cadavers aged about 70 years (45-85) belonging to the South Indian population. Total length of the quadriceps tendon, patellar height, patellar ligament height, proximal width, distal width and thickness of the patellar ligament were measured meticulously. Mean, standard deviation, median scores of each parameter were computed for groups using SPSS 16.0. Level of significance was considered as p < 0.05. Wilcoxon signed-rank test was used to compare the various parameters on the right and left limbs. The relationships between all parameters were analyzed using Spearman's rank correlation test.

RESULTS

There was no statistically significant difference in the various measurements of the patella and patellar ligament between the right and left lower limbs. Patellar ligament length showed positive correlation with ligament thickness (r = 0.36; p = 0.078 for right limb and r = 0.33; p = 0.104 for left limb). Proximal width of ligament showed significant positive correlation with distal width (r = 0.41; p = 0.041 for right limb and r = 0.54; p = 0.006 for left limb).

CONCLUSION

This morphometric data and analysis might be fundamental in understanding various knee conditions in situ and necessary to orthopedic surgeons for successful planning and execution for ACL reconstruction using patellar ligament graft and other patellofemoral joint disorders.

LEVEL OF EVIDENCE

I.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part V, knee

Objectives

Interventional procedures around the knee are widely adopted for treating different musculoskeletal conditions. A panel of experts from the Ultrasound and Interventional Subcommittees of the European Society of Musculoskeletal Radiology (ESSR) reviewed the existing literature to assess the evidence on image-guided musculoskeletal interventional procedures around the knee, with the goal of highlighting some controversies associated with these procedures, specifically the role of imaging guidance, as well as the efficacy of the medications routinely injected.

Methods

We report the results of a Delphi-based consensus of 53 experts in musculoskeletal radiology, who reviewed the published literature for evidence on image-guided interventional procedures around the knee to derive a list of pertinent clinical indications.

Results

A list of 10 statements about clinical indications of image-guided procedures around the knee was created by a Delphi-based consensus. Only two of them had the highest level of evidence; all of them received 100% consensus.

Conclusions

Ultrasonography guidance is strongly recommended for intra-articular and patellar tendinopathy procedures to ensure the precision and efficacy of these treatments. Prospective randomized studies remain warranted to better understand the role of imaging guidance and assess some of the medications used for interventional procedures around the knee.

Key Points

• A list of 10 evidence-based statements on clinical indications of image-guided interventional procedures around the knee was produced by an expert panel of the ESSR.

• Strong consensus with 100% agreement was obtained for all statements.

• Two statements reached the highest level of evidence, allowing us to strongly recommend the use of ultrasonography to guide intra-articular and patellar tendon procedures to ensure higher accuracy and efficacy of these treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08258-1.

In vivo stiffness assessment of patellar and quadriceps tendons by strain ultrasound elastography

BACKGROUND:

The patellar and quadriceps tendons are responsible for the extension mechanism of the knee joint and frequently become inflamed during sports. Diagnosis and determination of when an athlete can return to sports following these injuries are usually performed by assessing morphological features and functional outcomes. Nevertheless, mechanical properties are not being assessed.

OBJECTIVE:

To describe the stiffness characteristics of these two tendons over the range of knee flexion and to test the feasibility of using strain ultrasound elastography (SE).

METHODS:

SE with an acoustic coupler as the reference was performed for nine healthy males. Relative stiffness measurements were obtained using the strain ratio (SR = target tissue strain/reference strain) by placing the knee in five different flexion angles. Lower SR indicates higher relative stiffness.

RESULTS:

This study showed reliable measurement with good intra- and inter-rater agreement for SR at 30°. SR of the quadriceps tendon decreases as knee flexion increases, indicating increased relative stiffness. In the patellar tendon, no significant difference was observed between 30° and 60°. Beyond 60°, relative stiffness increased constantly.

CONCLUSIONS:

SE is a reproducible and feasible tool to monitor relative stiffness of the patellar and quadriceps tendons in routine clinical settings.

Inertial flywheel vs heavy slow resistance training among athletes with patellar tendinopathy: A randomised trial

OBJECTIVES

To compare the efficacy of inertial flywheel and heavy slow resistance training in reducing pain and improving function in patellar tendinopathy.

DESIGN

Randomised clinical trial.

METHODS

Fourty two participants (1 woman, 41 men) with longstanding (>3 months) patellar tendinopathy were randomised into inertial flywheel resistance (N = 21) or heavy slow resistance (N = 21) group. Both programmes consisted of three supervised inertial flywheel or heavy slow resistance exercise sessions per week in a fitness center during 12 weeks. Primary outcome was pain and function, assessed by the Spanish Victorian Institute of Sport Assessment for Patella (VISA-P) score at 6 and 12 weeks. Secondary outcomes were activity limitation using Patient Specific Functional Scale (PSFS), health status (EuroQol-5D), patient impression of change on pain and function, adherence, adverse events, pain provocation test for the patellar tendon (numerical rating score of pain between 0 and 10), physical test, patellar tendon thickness and doppler signal on ultrasound. Secondary outcomes were taken at 0 and 12 weeks.

RESULTS

Both groups showed significant improvements in VISA-P scores from 0 to 12 weeks but there was not statistically significant between-group difference (P = 0.506). No adverse events or side effects occurred in any of the groups during the intervention period.

CONCLUSIONS

Inertial flywheel resistance three times a week during 12 weeks resulted in similar pain and function benefit at 12 weeks compared with the heavy slow resistance training among people with patellar tendinopathy. Flywheel training is another exercise option for managing people with patellar tendinopathy. CLINICALTRIALS.

GOV REGISTRY

NCT03917849.

Expanded adipose derived mesenchymal stromal cells are effective in treating chronic insertional patellar tendinopathy: clinical and MRI evaluations of a pilot study

Purpose

Effect of ultrasound guided injections of autologous ASCs in chronic recalcitrant patellar tendinopathy.

Methods

Fourteen patients (16 knees, 12/2 males/females) with chronic, recalcitrant (unsuccessfully treated with nonoperative treatments) insertional PT underwent clinical evaluation and magnetic resonance imaging (MRI) before intervention. Stromal vascular fraction cells (SVF) were expanded by in-vitro culture and characterized by flow cytometry. Players were injected with three bi-weekly injections of ASCs followed by physiotherapy. They underwent serial clinical evaluations during a 12-month period with repeated MRI at 6-month post-injection.

Results

Victorian Institute of sports assessment-patellar tendon questionnaire (VISA-P) scores improved from 43.8 ± 4.9 at baseline to 58.1 ± 7.1, 70.3 ± 7.9 and 78.7 ± 7.5 at 3, 6, and12months follow-up, respectively. (p = 0.0004 comparing each variable with the previous one). Mean Visual analogue pain in sports (VAS-sport) score during practice significantly decreased from 7.4 ± 0.5 at baseline to 5.2 ± 1.5 9 (p = 0.0005), 3.3 ± 1.1 (p = 0.0004) and 1.5 ± 0.7 (P = 0.0004) at 3, 6, and 12 months, respectively. Mean Tegner-scores for patients were 8.0 ± 0.8 before injury and 2.3 ± 0.9 before treatment, thereafter, improving to 4.8 ± 0.8 and 7.2 ± 0.7 at 6- and 12- months, respectively (p = 0.0001). MRI assessed tendon width’ did not change over the first 6 months post-intervention. Significant changes were observed for: tendon thickness (12.8 ± 1.1 to 10.9 ± 0.7, P = 0.0001); tear length (9.3 ± 1.3 to 2.3 ± 0.7, P = 0.0001), tear width (6.3 ± 0.8 to 3.4 ± 0.4, P = 0.0001), and tear thickness (4.6 ± 0.4 to 2.6 ± 0., P = 0.0001) at baseline and 6 months, respectively.

Conclusion

Patients with recalcitrant insertional PT showed significant clinical improvement and structural repair at the patellar insertional tendinopathy after injections of autologous ASCs. Results of this study are promising and open a new biological therapeutic modality to treat PT.

Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy

STUDY DESIGN

Case-control.

OBJECTIVE

To examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT.

BACKGROUND

PT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT.

METHODS

11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests.

RESULTS

Patients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (-21.1° ± 5.9° vs. -14.8° ± 5.5°, P = .023) and step down (-15.6° ± 5.5° vs. -9.0° ± 6.0°, P = .017).

CONCLUSIONS

Patients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.

Low surgical routine increases revision rates after quadriceps tendon autograft for anterior cruciate ligament reconstruction: results from the Danish Knee Ligament Reconstruction Registry

PURPOSE

Recent registry data have demonstrated a higher revision rate of quadriceps tendon (QT) graft compared with hamstring tendon (HT) and patellar tendon (PT) grafts. Clinic routines could be an important factor for revision outcomes. The purpose of this study is to use the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates in patients who have undergone ACLR with QT, HT and PT grafts related to individual clinic surgical routine.

METHODS

Data on primary ACLRs entered in the DKRR from 2012 through 2019 were analysed since QT graft usage started in 2012. Revision rates for QT, HT and PT grafts were compared according to clinic activity (0-100 and > 100 procedures). Revision rates for the three autograft cohorts are presented, as well as adjusted revision hazard rates. Instrumented knee stability and pivot-shift tests were performed at a one-year follow-up.

RESULT

QT revision rate (6.4%) for low-activity clinics was higher than for high-activity clinics (2.9%) (p = 0.003). The adjusted revision hazard ratio for low-activity clinics was 2.3 (p = 0.01). QT autograft was associated with statistically significant, increased side-to-side laxity at follow-up (1.4 mm) compared with HT and PT autografts (1.0 mm) (p < 0.01), as well as an increased positive pivot-shift rate.

CONCLUSION

QT autografts for ACLR were associated with higher revision rates in clinics with lower than 100 procedures performed from 2012 to 2019. QT graft usage is not associated with a high revision rate when routinely performed. Learning curve is an important factor when introducing QT ACLR.

LEVEL OF EVIDENCE

Level III.

Biomechanical, biochemical, and near infrared spectral data of bovine knee ligaments and patellar tendon

Knee joint ligaments and patellar tendon are rope-like tissues that enable the proper function of the knee by connecting the bones that form the joint. A better understanding of ligament structure-function relationships is needed to develop objective and reliable diagnostic methods for ligaments. Recently, arthroscopic near infrared spectroscopy (NIR) has shown the potential to quantitatively evaluate the health of the cartilages and menisci of the knee. In this dataset, we present a unique combination of NIR spectral data, biomechanical properties, and biochemical composition of bovine primary knee ligaments and patellar tendon (10 knees, 50 tissue samples). NIR spectral data were measured at 5 locations in each sample, biomechanical properties were obtained with tensile testing, and biochemical composition was quantified using colorimetric biochemical methods. The data can be reused for investigations of structure-function relationships of knee ligaments and patellar tendon, for the development of NIR spectroscopic methods to quantify the health of these tissues, and to develop new computational models to describe ligament and tendon biomechanics.

Reliability of Sonoelastography Measurements of Lower Limb Tendon Properties: A Systematic Review

This study investigated the reliability of sonoelastography techniques in quantifying lower limb tendon elasticity. A literature search was conducted using PubMed, Web of Science and CINAHL. The quality of the selected papers was evaluated using the Guidelines for Reporting Reliability and Agreement Studies and the Quality Appraisal Tool for Studies of Diagnostic Reliability checklist. Reliability values were extracted and synthesized. Twenty-four studies were included and were divided by the two main technologies used: strain and shear-wave elastography. The overall methodological quality was questionable; all studies were at risk of bias. Highly variable results ranging from poor to excellent reliability were found for both technologies and for all tendons considered. Intra-rater reliability of strain elastography on the Achilles tendon and shear-wave elastography on the patellar and quadriceps tendon was adequate. Inter-rater, inter-session and inter-machine reliability was insufficient. Caution should be used when interpreting results from sonoelastography studies measuring lower limb tendon elasticity.

Moment arm of the knee-extensor mechanism measured in vivo across a range of daily activities

We measured the moment arm of the knee-extensor mechanism as ten healthy young individuals performed six functional activities: level walking, downhill walking, stair ascent, stair descent, open-chain (non-weight-bearing) knee flexion, and open-chain knee extension. The moment arm of the knee-extensor mechanism was described by the moment arm of the patellar-tendon force, which acts to rotate the tibia about the instantaneous axis of rotation (screw axis) of the knee. A mobile biplane X-ray imaging system enabled simultaneous measurements of the three-dimensional movements of the femur, tibia and patella during each activity, from which the position and orientation of the screw axis and the patellar-tendon moment arm (PTMA) were determined. Mean PTMA across all activities and all participants remained nearly constant (~46 mm) from 0° to 70° of knee flexion and decreased by no more than 20% at higher flexion angles. The magnitude of the PTMA varied more substantially across individuals than across activities, indicating that the moment arm is more heavily influenced by differences in knee-joint geometry than muscle loading. Hence, PTMA measurements obtained for a given activity performed by one individual may be used with good confidence to describe the PTMA for any other activity performed by the same individual. Caution is advised when using PTMA measurements obtained from one individual to describe the moment arm in another individual even once the data are normalized by knee bone size, as the PTMA varied by as much as 13% from the mean across individuals.

A case report of multi-ligaments injury of the ACL-MCL-PT combined with an occult fracture of the posterolateral tibial plateau

The anterior cruciate ligament and medial collateral ligament are important static stabilizers of the knee. The patellar tendon is part of the knee extensor mechanism. The injury simultaneously involving these three structures is very rare. This paper reports a case with simultaneous ipsilateral rupture of the anterior cruciate ligament, medial collateral ligament, patellar tendon, and an occult compression fracture of the posterolateral tibial plateau. This injury pattern has not been reported in literature yet. The injury mechanism was hypothesized as a sudden anterior translation and valgus of the proximal tibia when the knee was in high flexion, followed by an eccentric quadriceps' contracture. In the followed management, ruptured medial collateral ligament and patellar tendon were sutured with augment, while the torn anterior cruciate ligament and fracture were treated conservatively. The outcome of the treatment was satisfactory, and no complication was observed. To this combined injury, a comprehensive consideration, including physical examination, multiple imaging examinations, and analysis of injury mechanism, is essential for a full diagnosis and treatment decision. Especially, computed tomography may help to identify an occult or non-displaced fracture, which would be easily misdiagnosed when nothing unusual was found in routine X-rays. In the treatment, it is suggested to perform a selective or step-by-step repair to the damaged structures, rather than an immediate total repair after injury.

Successful mid- to long-term outcome after reconstruction of the extensor apparatus using proximal tibia-patellar tendon composite allograft

PURPOSE

The purpose of the study was to assess the outcomes of extensor mechanism reconstruction with proximal tibia-patellar tendon composite allograft.

METHODS

24 consecutive patients treated with allograft-prosthetic composite for proximal tibia tumour resection and a conventional total knee arthroplasty were included. Extensor mechanism reconstruction was performed with a proximal tibia-patellar tendon composite allograft and the suture of the donor tendon to the remnant native patellar tendon. Function was evaluated by the Musculoskeletal Tumor Society score (MSTS) and range of motion. Western Ontario and MacMaster University (WOMAC) and visual analogue scale for pain also were used.

RESULTS

After a mean follow-up of 11.7 (range 3-15) years, mean MSTS score was 22.4 (range 20-30), mean flexion was 94.0° (range 84°-110°), and mean extension lag was 7.2° (range 0°-18°). The mean VAS-pain was 4.3 (range 2-6), and WOMAC score was 72.4 (range 58-100). There was no failure of the reconstructed extensor mechanism.

CONCLUSION

Patellar tendon reconstruction with allogeneic tissue from the proximal tibia allograft sutured to the recipient's remnant patellar tendon provides the mechanical support needed for healing of the reconstructed extensor mechanism with a substantial functional benefit to stabilize active knee extension and successful reconstruction survival at long-term.

LEVEL OF EVIDENCE

III.

Sonographic and radiographic evaluation of the extensor tendons in early postoperative period after total knee arthroplasty

OBJECTIVE

To prospectively assess the early changes in the quadriceps and patellar tendons before and after total knee arthroplasty using ultrasound, shear wave elastography, and X-rays.

MATERIALS AND METHODS

Radiographs, ultrasound, and shear wave elastography were performed on 23 patients (16 women; aged 51-85, mean 66 ± 9 years) before and after surgery at 6 weeks and on 11 patients at 3 months. Patellar position and patellar tendon lengths were evaluated by radiography; joint effusion or synovitis, quadriceps and patellar tendon lengths, and thicknesses, echogenicity, vascularity, and stiffness were assessed with ultrasound and shear wave elastography.

RESULTS

In the early postoperative period, 87% of the patients had joint effusion, and 43% had signs of synovitis. There was a significant thickening of the quadriceps tendon in 51.5% (p < .0001) and of the patellar tendon in 93.8% (p < .0001) of patients with a significant shortening of the patellar tendon in 7.8% (p < .0001). A hypoechoic defect on the medial aspect of the quadriceps tendon was found in 87% of the patients. There was a significant increase in Young's modulus in the quadriceps tendon (p = .0006) but not in the patellar tendon.

CONCLUSION

The following should not be considered to be pathological findings at early postoperative imaging: joint effusion, synovitis, increasing of stiffness and thickening of quadriceps tendons by more than 50%, thickening of patellar tendon by more than 90%, focal defect through the medial aspect of the quadriceps tendon, and shortening of the patellar tendon by 8%.

Staged patellar tendon reconstruction using doubled bone-patellar tendon-bone allograft for infected patellar tendon rupture: a rare case report of three years follow-up

BACKGROUND

Patellar tendon rupture is a relatively rare injury that usually requires surgical treatment. The optimal therapeutic strategy is still controversial, especially when either concomitant patellar tendon infection or soft tissue infection surrounds the patellar tendon. Until recently, most reported reconstruction methods are extensive and difficult to apply because of the poor condition of the soft tissue surrounding the patellar tendon.

CASE PRESENTATION

A 19-year-old male patient presented to our clinic three weeks following a motorcycle accident. There was a 5 x 4 cm sized skin defect with soft tissue infection below the inferior pole of patella. We performed a staged patellar tendon reconstruction using a doubled bone-patellar tendon-bone allograft (BPTB) to the infected patellar tendon rupture, following local random fasciocutaneous flap and split-thickness skin graft. Three months following surgery, the patient was able to perform an active knee motion with no extension lag and excellent clinical functional result.

DISCUSSION AND CONCLUSIONS

Our technique introduced in this specific case is a relatively simple method to reconstruct chronic patellar tendon defects with limited incision exposing only the patellar tendon areas. We expect it can be less invasively performed on patients who have a soft tissue problem and cannot have extensive surgery.

UTE T2* mapping of tendinopathic patellar tendons: an MRI reproducibility study

BACKGROUND

There is currently a lack of imaging modalities that can be used as a sensitive measure in tendinopathy. Recent findings suggest the applicability of ultra-short echo time (UTE) magnetic resonance imaging (MRI) T2* mapping in tendons, but the reproducibility remains unknown.

PURPOSE

To evaluate test-retest reproducibility of UTE MRI T2* mapping of tendinopathic patellar tendons and to evaluate the intra- and inter-observer reproducibility of the measurement.

MATERIAL AND METHODS

Fifteen patients with chronic patellar tendinopathy were evaluated with UTE MRI twice in a 3.0-T scanner on the same day. Manual segmentation of the patellar tendon was performed by two blinded investigators and automated T2*map reconstruction was performed in custom-made software.

RESULTS

There was a significant and numerically small difference in test-retest T2* values (T2*mean_diff = 0.06 ± 0.07 ms ≈ 3.7%; P = 0.006) with an ICC = 0.91 (95% confidence interval [CI] 0.58-0.98; typical error of 3.0%). The intra- and inter-observer reproducibility showed no significant bias (P = 0.493 and P = 0.052), and generally substantial reproducibility was demonstrated for T2* (intra-observer ICC = 0.99; 95% CI 0.98-1.00 and inter-observer ICC = 0.99; 95% CI 0.96-1.00, and typical error 1.3% and 1.3%, respectively).

CONCLUSION

These data demonstrate a small bias between repeated measurements for UTE T2*, but with a very low associated mean difference (3.7%) between the two tests. The high ICC values and low typical error % demonstrate reproducibility of repeated T2*-mapping sessions. Further, the method showed substantial intra- and inter-observer reproducibility for T2* values proving feasibility for use of UTE T2* mapping in research and clinical practice.

Dynamic changes in the infrapatellar knee structures with quadriceps muscle contraction. An in vivo study

OBJECTIVE

To determine the effect of knee flexion and submaximal isometric quadriceps muscle (Q) contraction on the patellar tendon (PT), the infrapatellar fat pad (IPFP), and the deep infrapatellar bursa (IPB) from extension to full flexion.

METHODS

In Study 1, the dominant knee of seven healthy subjects was studied in full extension and at 60° flexion during relaxation and Q contraction. Each knee was inspected and palpated, the transverse infrapatellar diameter was measured by plicometry, and measurements of the anteroposterior (AP) thickness of the IPFP were made by ultrasound (US). In Study 2, the dominant knee of seven healthy subjects was studied by US in full flexion, and then, at 15° decrements, down to 60° flexion during relaxation and Q contraction. Both studies had IRB approval. Results were analyzed with the Wilcoxon test and descriptive statistics.

RESULTS

In Study 1, Q contraction caused straightening of the patellar tendon (PT), a statistically significant widening of the IPFP by plicometry, and an increased AP thickness of the IPFP by US, in both knee positions. In Study 2, in full knee flexion, the PT contacted the tibial cortex in all seven subjects. Upon increasing extension, the PT-tibial cortex contact was lost in all subjects nearing 90° flexion. The contraction of the Q made the concave PT straight, grew the width of the underlying IPFP, and the apron of the IPFP moved distally within the IPB in all knee positions. A small amount of bursal fluid was present in all seven subjects.

CONCLUSION

Q contraction makes the IPFP bulge anteriorly, on both sides of the PT, and distally into the IPB, with possible biomechanical implications. In full knee flexion, the PT contacted the tibia, confirming a fulcrum at this site.

Autograft type affects muscle strength and hop performance after ACL reconstruction. A randomised controlled trial comparing patellar tendon and hamstring tendon autografts with standard or accelerated rehabilitation

PURPOSE

To evaluate and compare changes in quadriceps and hamstring strength and single-leg-hop (SLH) test performance over the first 24 postoperative months in patients who underwent anterior cruciate ligament reconstruction (ACLR) with bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) autografts and followed either a standard or an accelerated rehabilitation protocol.

METHODS

A total of 160 patients undergoing ACLR were randomised in four groups depending on the graft that was used and the rehabilitation protocol (40 BPTB/standard rehab, 40 BPTB/accelerated rehab, 40 HT/standard rehab, 40 HT/accelerated rehab). Isokinetic concentric quadriceps and hamstring strength at 90°/s and the SLH test performance were assessed preoperatively and 4,6,8,12 and 24 months postoperatively. The results were reported as the limb symmetry index (LSI) at the same time point. Linear mixed models were used to compare the groups at the different time points.

RESULTS

An average quadriceps strength LSI of 78.4% was found preoperatively. After ACLR, the LSI first decreased at 4 months and then increased from 6 to 24 months, reaching an overall value of 92.7% at the latest follow-up. The BPTB group showed a significantly decreased LSI at 4, 6, 8 and 12 months compared with the HT group. No significant differences between the graft groups were found at 24 months. An average hamstring strength LSI of 84.6% was found preoperatively. After ACLR, the LSI increased from 4 to 24 months in the BTPB group. In the HT group, the LSI first decreased at 4 months and then increased from 6 to 24 months. An LSI of 97.1% and 89.1% was found at the latest follow-up for the BPTB and the HT group, respectively. The HT group showed a significantly decreased LSI at all follow-ups compared with the BPTB group. An average SLH test LSI of 81% was found preoperatively. After ACLR, the LSI increased from 4 to 24 months, reaching 97.6% overall at the latest follow-up. The BPTB group showed a significantly decreased LSI only at 4 months postoperatively compared with the HT group. No significant differences in any of the three tests were found between the standard and accelerated rehabilitation groups for either of the graft groups at any time point.

CONCLUSION

Muscle strength and SLH test performance recovered progressively after ACLR overall, but they did not all fully recover, as the injured leg performed on average less than 100% compared with the uninjured leg even 24 months postoperatively. After ACLR, inferior quadriceps strength and a poorer SLH test performance were found at 4, 6, 8 and 12 months and at 4 months, respectively, for the BTPB group compared with the HT group. Persistent, inferior hamstring strength was found at all postoperative follow-ups in the HT group. Rehabilitation, standard or accelerated, had no significant impact on the recovery of muscle strength and SLH test performance after ACLR in any of the graft groups.

LEVEL OF EVIDENCE

Level I.

Tibial tuberosity avulsion-fracture associated with complete distal rupture of the patellar tendon: A case report and review of literature

BACKGROUND

Few cases of avulsion fractures of the tibial tuberosity with simultaneous rupture of the patellar tendon have been reported in the literature. Therefore, its mechanism and incidence have not been determined conclusively. This type of fracture is considered a serious injury that requires prompt diagnosis and early surgical repair. There is no therapeutic algorithm or standard method of treatment due to the infrequency of the injury. In this case report, we conducted an exhaustive review and synthesis of the existing literature including all previously reported cases.

CASE SUMMARY

We present a 16-year-old male soccer player with a case of a tibial tuberosity fracture with distal avulsion of the patellar tendon 5 d prior to surgical treatment. The patient presented with a loss of the extensor mechanism of the knee, edema, the inability to walk, and pain. X-rays showed a high patella and a 180-degree avulsion of the tibial tuberosity. The diagnosis was confirmed by magnetic resonance imaging and computed tomography. The patient underwent open reduction and internal fixation of the fracture with a cannulated screw and washer as well as patellar tendon repair with two metallic anchors. The rehabilitation protocol consisted of initial immobilization in extension followed by passive mobility and muscle strengthening exercises. The patient demonstrated excellent postoperative outcomes and returned to regular activity without complications.

CONCLUSION

This case presentation and literature review comprise the most relevant clinical, radiographic, and treatment details described in the international literature to date, providing the reader with an overview of this rare condition.

Effects of football versus aerobic exercise training on muscle architecture in healthy men adults: a study protocol of a two-armed randomized controlled trial

BACKGROUND

Sports and exercise training can attenuate age-related declines in physical function. As people age, they suffer a progressive deterioration of overall muscle structure and function, such as muscle diameter, strength, mass, and power. Therefore, supporting older adults-aged 50 years and above-to continue being physically active is a very important factor. Several forms of exercise (strength, agility, endurance, balance, and flexibility) are recommended. In this regard, football has been repeatedly shown to be an integrative approach to promote measures of strength, endurance, and agility. However, there has been no previous randomized controlled trial that comparatively investigates the effects of football training versus traditional aerobic exercise training on muscle architecture and patella tendon properties in healthy community dwellers. The study protocol is designed to examine whether football differentially affects muscle thickness, muscle length, fascicle length, pennation angle, patella tendon length, and thickness compared to a workload matched traditional aerobic exercise training regimen.

METHODS

The study sample consists of 60 untrained but healthy men (50-60 years old), who will be randomly assigned (strata: age, activate) to two groups: football group (n = 30) and aerobic group (n = 30). The intervention will take place within 12 consecutive weeks, two times a week for 60 min each session. The football group will perform recreational football training as a large-sided game, whereas the aerobic group undergoes a running exercise. Both groups have the same external workload ranging between moderate and high exercise intensity. The outcome measure will be collected before and after the intervention period.

DISCUSSION

Findings of this study will provide insight into the effects of 24 sessions of both football and aerobic training program on the selected groups of men adults, including detecting their effects on the thigh muscle architecture.

TRIAL REGISTRATION

DRKS-German Clinical Trials Register, DRKS00020536 . Registered on 30 January 2020.

Fiber splay precludes the direct identification of ligament material properties: Implications for ACL graft selection

Anterior cruciate ligament (ACL) injuries typically require surgical reconstruction to restore adequate knee stability. The middle third of an injured patient's patellar tendon (PT) is a commonly used graft for ACL reconstruction. However, many clinicians and researchers question whether it is the best option, as several studies have suggested that it is a stiffer material than the ACL. Still, there is little to no consensus on even the most basic material property of ligaments/tendons: the tangent modulus in the fiber direction, or slope of the linear portion of the uniaxial stress-strain curve. In this study, we investigate the effect of fiber splay (the tendency of collagen fibers to spread out near the enthesis) on the apparent tangent modulus. Using a simplified theoretical model, we establish a quantity we call the splay ratio, which describes the relationship between splay geometry and the apparent tangent modulus. We then more rigorously investigate the effect of the splay ratio on the apparent tangent modulus of the ovine PT and anteromedial and posterolateral regions of the ACL using experimental and computational methods. Both approaches confirmed that splay geometry significantly affects the apparent material behavior. Because true material properties are independent of geometry, we conclude that the macroscopic response of ligaments and tendons is not sufficient for the characterization of their material properties, but rather is reflective of both material and structural properties. We further conclude that the PT is probably not a stiffer material than ACL, but that the PT graft is likely a stiffer structure than either ACL region.

Risk of overconstraining femorotibial rotation after anatomical ACL reconstruction using bone patella tendon bone autograft

INTRODUCTION

Numerous studies have focused on the anteroposterior stability after anterior cruciate ligament (ACL) reconstruction, with less emphasis on rotational stability. It has been hypothesized that bone patella tendon bone (BTB) autograft for ACL reconstruction restores knee rotation closely to normal due to its comparable fiber orientation to the native ACL.

MATERIALS AND METHODS

Twenty patients with unilateral ACL rupture and an uninjured contralateral knee were included in this study. The ACL was reconstructed using the medial third of the patellar tendon. Tunnel placement was controlled by fluoroscopy. Implant-free press-fit graft fixation was used on both femoral and tibial side. Bone blocks were carefully placed to restore fiber orientation of both the anteromedial and posterolateral bundle, similar to the native ACL. Rotatory laxity of both knees was measured at 0° and 25° of flexion pre- and post-surgery, using an active opto-electronical motion-analysis system (LUKOTRONIC AS 100^®). All measurements were performed under general anesthesia during surgery.

RESULTS

Knee rotation was reduced significantly in both 0°and 25° of flexion following ACL reconstruction (p < 0.001). The side to side difference (SSD) of the rotatory laxity in extension was greater in the ACL-deficient knee (14.9° ± 8.9°), but decreased significantly after ACL reconstruction (- 5.9° ± 7.7°, minus value means less than in the uninjured knee). There was a similar finding at 25° of knee flexion where greater rotation of the ACL-deficient knee (5.7° ± 10.3°) prior to surgery changed to lower degree of rotation after surgery (- 11.3° ± 8.4°) in comparison to the uninjured knee.

CONCLUSIONS

ACL reconstruction with a BTB graft in anatomical position using press-fit implant-free fixation is able to restore rotatory knee stability close to the intact contralateral knee. Despite the fact that the BTB graft offers fiber orientation close to the natural ACL, the surgeon should be aware of the potential risk of over-constraining the knee in terms of rotation.

LEVEL OF EVIDENCE

II.