Prevalence of Sonographic Achilles Tendon, Patellar Tendon, and Plantar Fascia Abnormalities in Division I Collegiate Athletes From a Variety of Sports

OBJECTIVE

This study aimed to determine the prevalence of ultrasound abnormalities in the Achilles tendon, patellar tendon, and plantar fascia among a large cohort of collegiate student-athletes.

DESIGN

Observational cross-sectional study.

SETTING

Three Division I institutions.

PARTICIPANTS

243 student-athletes participated in this study. Exclusion criteria included those younger than 18 years or who underwent prior surgery/amputation of structures, including anterior cruciate ligament (ACL) surgeries with patellar tendon grafts.

INTERVENTIONS

Ultrasound examination of the Achilles tendon, patellar tendon, and plantar fascia of each leg was performed. An experienced sonographer reviewed each tendon video in a blinded manner, with a separate experienced sonographer separately reviewing to establish inter-rater reliability.

MAIN OUTCOME MEASURES

The primary outcome measured was the presence of any sonographic abnormality including hypoechogenicity, thickening, or neovascularity.

RESULTS

Ultrasound abnormalities were identified in 10.1%, 37.2%, and 3.9% of all Achilles tendons, patellar tendons, and plantar fasciae, respectively. Abnormalities were significantly associated with the presence of concurrent pain for all structures ( P < 0.01). Specifically, athletes with sonographic abnormalities were approximately 4 times [relative risk (RR) = 4.25; 95% confidence interval (CI), 2.05-8.84], 6 times (RR = 5.69; 95% CI, 2.31-14.00), and 5 times (RR = 5.17; 95% CI, 1.76-15.25) more likely to self-report pain in the Achilles tendon, patellar tendon, and plantar fascia, respectively.

CONCLUSIONS

This multi-institutional study completed at 3 Division I institutions is the largest study of its kind to identify the prevalence of sonographic abnormalities in the Achilles tendon, patellar tendon, and plantar fascia among collegiate student-athletes of various sports.

Medial patellar ligament reconstruction in combination with derotational distal femoral osteotomy for treating recurrent patellar dislocation in the presence of increased femoral anteversion: a systematic review

BACKGROUND

Medial patellar ligament reconstruction (MPFL-R) in combination with derotational distal femoral osteotomy (DDFO) for treating recurrent patellar dislocation (RPD) in the presence of increased femoral anteversion is one of the most commonly used surgical techniques in the current clinical practice. However, there are limited studies on the clinical outcomes of MPFL-R in combination with DDFO to treat RPD in the presence of increased femoral anteversion.

PURPOSE

To study the role of MPFL-R in combination with DDFO in the treatment of RPD in the presence of increased femoral anteversion.

METHODS

A systematic review was performed according to the PRISMA guidelines by searching the Medline, Embase, Web of Science, and Cochrane Library databases through June 1, 2023. Studies of patients who received MPFL-R in combination with DDFO after presenting with RPD and increased femoral anteversion were included. Methodological quality was assessed using the MINORS (Methodological Index for Nonrandomized Studies) score. Each study's basic characteristics, including characteristic information, radiological parameters, surgical techniques, patient-reported outcomes, and complications, were recorded and analyzed.

RESULTS

A total of 6 studies with 231 patients (236 knees) were included. Sample sizes ranged from 12 to 162 patients, and the majority of the patients were female (range, 67-100%). The mean age and follow-up ranges were 18 to 24 years and 16 to 49 months, respectively. The mean femoral anteversion decreased significantly from 34° preoperatively to 12° postoperatively. In studies reporting preoperative and postoperative outcomes, significant improvements were found in the Lysholm score, Kujala score, International Knee Documentation Committee score, and visual analog scale for pain. Postoperative complications were reported in all studies, with an overall reported complication rate of 4.7%, but no redislocations occurred during the follow-up period.

CONCLUSION

For RPD with increased femoral anteversion, MPFL-R in combination with DDFO leads to a good clinical outcome and a low redislocation rate. However, there was no consensus among researchers on the indications for MPFL-R combined with DDFO in the treatment of RPD.

Reconstruction of medial meniscus posterior portion deficiency in pigs with an autologous patellar tendon graft: an experimental study

OBJECTIVE

This study was performed to investigate the effectiveness of two surgical procedures, autologous patellar tendon graft reconstruction and trans-tibial plateau pull-out repair, using a pig model. The primary focus was to assess the repair capability of medial meniscus posterior portion (MMPP) deficiency, the overall structural integrity of the meniscus, and protection of the femoral and tibial cartilage between the two surgical groups. The overall aim was to provide experimental guidelines for clinical research using these findings.

METHODS

Twelve pigs were selected to establish a model of injury to the MMPP 10 mm from the insertion point of the tibial plateau. They were randomly divided into three groups of four animals each: reconstruction (autologous tendon graft reconstruction of the MMPP), pull-out repair (suture repair of the MMPP via a trans-tibial plateau bone tunnel), and control (use of a normal medial meniscus as the negative control). The animals were euthanized 12 weeks postoperatively for evaluation of the meniscus, assessment of tendon bone healing, and gross observation of knee joint cartilage. The tibial and femoral cartilage injuries were evaluated using the International Society for Cartilage Repair (ICRS) grade and Mankin score. Histological and immunohistochemical staining was conducted on the meniscus-tendon junction area, primary meniscus, and tendons. The Ishida score was used to evaluate the regenerated meniscus in the reconstruction group. Magnetic resonance imaging (MRI) was used to evaluate meniscal healing.

RESULTS

All 12 pigs recovered well after surgery; all incisions healed without infection, and no obvious complications occurred. Gross observation revealed superior results in the reconstruction and pull-out repair groups compared with the control group. In the tibial cartilage, the reconstruction group had ICRS grade I injury whereas the pull-out repair and control groups had ICRS grade II and III injury, respectively. The Mankin score was significantly different between the reconstruction and control groups; histological staining showed that the structure of the regenerated meniscus in the reconstruction group was similar to that of the original meniscus. Immunohistochemical staining showed that the degree of type I and II collagen staining was similar between the regenerated meniscus and the original meniscus in the reconstruction group. The Ishida score was not significantly different between the regenerated meniscus and the normal primary meniscus in the reconstruction group. MRI showed that the MMPP in the reconstruction and pull-out repair groups had fully healed, whereas that in the control group had not healed.

CONCLUSION

Autologous patellar tendon graft reconstruction of the MMPP can generate a fibrocartilage-like regenerative meniscus. Both reconstruction and pull-out repair can preserve the structural integrity of the meniscus, promote healing of the MMPP, delay meniscal degeneration, and protect the knee cartilage.

Acute Patellar Tendon Ruptures: An Update on Management

Patellar tendon ruptures can be debilitating injuries. When incomplete, partial tears can be managed nonsurgically with immobilization and progressive rehabilitation. Although complete ruptures remain a relatively uncommon injury, they portend a high level of morbidity. Ruptures typically result from an acute mechanical overload to the extensor mechanism, such as with forced quadriceps contraction and knee flexion. However, chronically degenerated tendons are also predisposed to failure from low-energy injuries. Diagnosis can often be made clinically with recognition of a palpable defect to the tendon, localized patellar tendon tenderness, and inability to actively extend the knee. Diagnosis and surgical planning can be established with radiograph, ultrasonography, or magnetic resonance imaging. Surgical repair is the mainstay of treatment, and there have been many recent advances in repair technique, optimal reconstruction strategies, and supplemental fixation. Time to surgery for complete tears remains the most important prognosticator for success. Direct primary repair can be completed with transosseous tunnels, suture anchor repair, or end-to-end repair. Tendon reconstruction can be achieved with or without mechanical or biologic augments. Rehabilitation programs vary in specifics, but return to sport can be expected by 6 months postoperatively.

MRI of patellar stabilizers: Anatomic visibility, inter-reader reliability, and intra-reader reproducibility of primary and secondary ligament anatomy

OBJECTIVE

To compare MRI features of medial and lateral patellar stabilizers in patients with and without patellar instability.

METHODS

Retrospective study of 196 patients (mean age, 33.1 ± 18.5 years; 119 women) after diagnosis of patellar instability (cohort-1, acute patellar dislocation; cohort-2, chronic patellar maltracking) or no patellar instability (cohort-3, acute ACL rupture; cohort-4, chronic medial meniscus tear). On MRI, four medial and four lateral stabilizers were evaluated for visibility and injury by three readers independently. Inter- and intra-reader agreement was determined.

RESULTS

Medial and lateral patellofemoral ligaments (MPFL and LPFL) were mostly or fully visualized in all cases (100%). Of the secondary patellar stabilizers, the medial patellotibial ligament was mostly or fully visualized in 166 cases (84.7%). Other secondary stabilizers were mostly or fully visualized in only a minority of cases (range, 0.5-32.1%). Injury scores for all four medial stabilizers were higher in patients with acute patellar dislocation than the other 3 cohorts (p < .05). Visibility inter- and intra-reader agreement was good for medial stabilizers (κ 0.61-0.78) and moderate-to-good for lateral stabilizers (κ 0.40-0.72). Injury inter- and intra-reader agreement was moderate-to-excellent for medial stabilizers (κ 0.43-0.90) and poor-to-moderate for lateral stabilizers (κ 0-0.50).

CONCLUSION

The MPFL and LPFL were well visualized on MRI while the secondary stabilizers were less frequently visualized. The secondary stabilizers were more frequently visualized medially than laterally, and patellotibial ligaments were more frequently visualized compared to the other secondary stabilizers. Injury to the medial stabilizers was more common with acute patellar dislocation than with chronic patellar maltracking or other knee injuries.

Examination of knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis

BACKGROUND

Joint moment arm is a major element that determines joint torque. This study aimed to investigate factors associated with knee extensor and valgus moment arms of the patellar tendon in older individuals with and without knee osteoarthritis.

METHODS

Thirty-six participants with knee osteoarthritis (mean age, 78.1 ± 6.0 years) and 43 healthy controls (mean age, 73.0 ± 6.3 years) were analyzed. Magnetic resonance images (MRI) from the knee joint and thigh were acquired using a 3.0 T MRI scanner. The three-dimensional moment arm was defined as the distance between the contact point of the tibiofemoral joint and the patellar tendon line. The three-dimensional moment arm was decomposed into sagittal and coronal components, which were calculated as knee extensor and valgus moment arms, respectively. Quadriceps muscle volume, epicondylar width, bisect offset, Insall-Salvati ratio, and Kellgren-Lawrence grade were assessed. Multiple regression analyses were performed in the healthy control and knee osteoarthritis groups, with knee extensor and valgus moment arms as dependent variables.

FINDINGS

Knee extensor moment arm was significantly associated with epicondylar width and the Insall-Salvati ratio in the healthy control group and with Kellgren-Lawrence grade, epicondylar width, and quadriceps muscle volume in the knee osteoarthritis group. Valgus knee moment arm was significantly associated with bisect offset in both the groups.

INTERPRETATION

Knee size, osteoarthritis severity, and quadriceps muscle volume affect the knee extensor moment arm in knee osteoarthritis, whereas lateral patellar displacement affects the valgus knee moment arms in older individuals with and without knee osteoarthritis.

Comparative analysis of patellar tendon, achilles tendon and plantar fascia structure in indoor and outdoor football players: a novel cross-sectional pilot study

Different sport modalities were associate with tendon adaptation or even tendon disturbances, such as volleyball, soccer or basketball. Purpose: the aim of the present study was to determine de difference between indoor and outdoor football players on patellar tendon (PT), Achilles tendon (AT), plantar fascia (FP) and Hoffa's fat pad thickness assessed with ultrasound imaging (USI). A cross-sectional study was developed with a total sample of 30 soccer players divided in two groups: outdoor group (n = 15) and indoor group (n = 15). The thickness of PT, AT, PF and Hoffa's fat pad has been assessed with USI. Hoffa's fat pad reported significant differences for the left side between groups (P = 0.026). The rest of variables did not show any significant difference (P < 0.05). The ultrasonography assessment of the thickness of the PT, AT and PF did not show differences between outdoor and indoor football players. Hoffa's fat pad resulted showed a significant decrease for outdoor soccer players with respect futsal players. Thus, it can be considered that the load stimuli received in both soccer players were not enough to produce structural adaptations in PT, AT and PF tissues.

A Novel Tendon Injury Model, Induced by Collagenase Administration Combined with a Thermo-Responsive Hydrogel in Rats, Reproduces the Pathogenesis of Human Degenerative Tendinopathy

Patellar tendinopathy is a common clinical problem, but its underlying pathophysiology remains poorly understood, primarily due to the absence of a representative experimental model. The most widely used method to generate such a model is collagenase injection, although this method possesses limitations. We developed an optimized rat model of patellar tendinopathy via the ultrasound-guided injection of collagenase mixed with a thermo-responsive Pluronic hydrogel into the patellar tendon of sixty male Wistar rats. All analyses were carried out at 3, 7, 14, 30, and 60 days post-injury. We confirmed that our rat model reproduced the pathophysiology observed in human patients through analyses of ultrasonography, histology, immunofluorescence, and biomechanical parameters. Tendons that were injured by the injection of the collagenase-Pluronic mixture exhibited a significant increase in the cross-sectional area (p < 0.01), a high degree of tissue disorganization and hypercellularity, significantly strong neovascularization (p < 0.01), important changes in the levels of types I and III collagen expression, and the organization and presence of intra-tendinous calcifications. Decreases in the maximum rupture force and stiffness were also observed. These results demonstrate that our model replicates the key features observed in human patellar tendinopathy. Collagenase is evenly distributed, as the Pluronic hydrogel prevents its leakage and thus, damage to surrounding tissues. Therefore, this model is valuable for testing new treatments for patellar tendinopathy.

Patellar Tendon Adaptations to Downhill Running Training and Their Relationships With Changes in Mechanical Stress and Loading History

ABSTRACT

Bontemps, B, Gruet, M, Louis, J, Owens, DJ, Miríc, S, Vercruyssen, F, and Erskine, RM. Patellar tendon adaptations to downhill running training and their relationships with changes in mechanical stress and loading history. J Strength Cond Res 38(1): 21-29, 2024-It is unclear whether human tendon adapts to moderate-intensity, high-volume long-term eccentric exercise, e.g., downhill running (DR) training. This study aimed to investigate the time course of patellar tendon (PT) adaptation to short-term DR training and to determine whether changes in PT properties were related to changes in mechanical stress or loading history. Twelve untrained, young, healthy adults (5 women and 7 men) took part in 4 weeks' DR training, comprising 10 sessions. Running speed was equivalent to 60-65% V̇O2max, and session duration increased gradually (15-30 minutes) throughout training. Isometric knee extensor maximal voluntary torque (MVT), vastus lateralis (VL) muscle physiological cross-sectional area (PCSA) and volume, and PT CSA, stiffness, and Young's modulus were assessed at weeks 0, 2, and 4 using ultrasound and isokinetic dynamometry. Patellar tendon stiffness (+6.4 ± 7.4%), Young's modulus (+6.9 ± 8.8%), isometric MVT (+7.5 ± 12.3%), VL volume (+6.6 ± 3.2%), and PCSA (+3.8 ± 3.3%) increased after 4 weeks' DR (p < 0.05), with no change in PT CSA. Changes in VL PCSA correlated with changes in PT stiffness (r = 0.70; p = 0.02) and Young's modulus (r = 0.63; p = 0.04) from 0 to 4 weeks, whereas changes in MVT did not correlate with changes in PT stiffness and Young's modulus at any time point (p > 0.05). To conclude, 4 weeks' DR training promoted substantial changes in PT stiffness and Young's modulus that are typically observed after high-intensity, low-volume resistance training. These tendon adaptations seemed to be driven primarily by loading history (represented by VL muscle hypertrophy), whereas increased mechanical stress throughout the training period did not seem to contribute to changes in PT stiffness or Young's modulus.

Personalized tendon loading reduces muscle-tendon imbalances in male adolescent elite athletes

An imbalanced adaptation of muscle strength and tendon stiffness in response to training may increase tendon strain (i.e., the mechanical demand on the tendon) and consequently tendon injury risk. This study investigated if personalized tendon loading inducing tendon strain within the effective range for adaptation (4.5%-6.5%) can reduce musculotendinous imbalances in male adolescent handball athletes (15-16 years). At four measurement time points during a competitive season, we assessed knee extensor muscle strength and patellar tendon mechanical properties using dynamometry and ultrasonography and estimated the tendon's structural integrity with a peak spatial frequency (PSF) analysis of proximal tendon ultrasound scans. A control group (n = 13) followed their usual training routine, an intervention group (n = 13) integrated tendon exercises into their training (3x/week for ~31 weeks) with a personalized intensity corresponding to an average of ~6.2% tendon strain. We found a significant time by group interaction (p < 0.005) for knee extensor muscle strength and normalized patellar tendon stiffness with significant increases over time only in the intervention group (p < 0.001). There were no group differences or time-dependent changes in patellar tendon strain during maximum voluntary contractions or PSF. At the individual level, the intervention group demonstrated lower fluctuations of maximum patellar tendon strain during the season (p = 0.005) and a descriptively lower frequency of athletes with high-level tendon strain (≥9%). The findings suggest that the personalized tendon loading program reduced muscle-tendon imbalances in male adolescent athletes, which may provide new opportunities for tendon injury prevention.

Does the ultrasound imaging predict lower limb tendinopathy in athletes: a systematic review

BACKGROUND

To conduct a systematic review looking into the possibility of US imaging to anticipate and identify future patellar or Achilles tendinopathy symptoms.

METHODS

The studies that were taken into consideration for this review were prospective studies that employed baseline US imaging of the patellar OR Achilles tendons in asymptomatic patients and follow-up measures of pain and/or function. Two impartial reviewers evaluated the study's quality using the Critical Appraisal Skills Programme instrument.

RESULTS

Participants in the included studies in this review came from various sports. The systematic review revealed a link between baseline tendon abnormalities in the US and a higher chance of developing both patellar and Achilles tendinopathy as well as their future occurrence. Nine of the included studies examined the patellar tendon alone, eight the patellar and Achilles tendon together, and four the Achilles tendon exclusively. For both tendons, US administration is done in a largely consistent manner. The tendon abnormalities of tendon thickness, hypoechogenicity and vascularity at baseline were associated with an increased risk of both Achilles and patellar tendinopathy.

CONCLUSIONS

This systematic review shows that abnormal tendon structures seen by US in asymptomatic persons can predict the development of tendinopathy.

Fatigue-induced Alterations of the Patellar Tendon in Elite Sprint Track Cyclists

This study aims to investigate morphological and mechanical properties and echogenicity of the patellar tendon (PT) after acute fatigue-induced alterations in sprint track cyclists. Fourteen elite track cyclists participated in this study. The exercise protocol consisted of three maximal start accelerations (over a distance of 62.5 m), one maximal start acceleration (at both 125 m and 250 m), and sprints from the standing start. Immediately after testing all measurements, PT stiffness and thickness were set at 5-10-15-20 mm distal from the apex of the patella and 5-10 mm proximal to the tibial tuberosity. CSA was set at proximal, middle, and distal, while echogenicity was at proximal and distal points. The results showed significant increases in PT stiffness at all reference points after start acceleration (p<0.001). PT thickness showed similar results for stiffness, except for location placed at TT-5 (p<0.001). CSA increased significantly in proximal, middle, and distal regions (p<0.001), while echogenicity of the tendon increased in proximal and distal regions (p<0.001) after start acceleration. Regional-dependent alterations of PT thickness and stiffness may be related to anatomical and physiological mechanisms due to acute isometric contraction in the initial phase of standing start. Tendon echogenicity might be also useful in monitoring tendon mechanical properties and defining acute fatigue-induced changes.

Reliability of a special device for measuring the cross-sectional area of the patellar tendon by ultrasonography

The objective of this study was to evaluate the intra- and inter-rater reliability and agreement between conditions with and without a special device (SD) in the evaluation of the patellar tendon (PT) cross-sectional area (CSA). Forty trained adult volunteers participated in the study. With the knee positioned at 90°, the ultrasound probe was placed in the transverse plane at 25, 50, and 75% of the PT length. Two raters and one analyzer obtained the images. We use a two-way ANOVA with a significance level of α = 0.05. No significant differences were found between raters or conditions. Intra-rater reliability ranged from moderate to good. Inter-rater reliability without the SD ranged from low to good, improving from moderate to good when the SD was used. Evaluation of the PT ends showed a lower coefficient of variation with the SD. We observed a moderate correlation at the ends and a strong correlation in the middle between conditions. The mean difference in the three positions is small (~ 0.013 cm2/ ~ 1.7%) with an upper limit of 43.2% and a lower limit of 32.5%. Therefore, we conclude that the use of the SD can be employed for evaluating the PT ends, while for the central region, it becomes optional.

Effect of sex on muscle-tendon imbalances and tendon micromorphology in adolescent athletes-A longitudinal consideration

Imbalances between muscle strength and tendon stiffness may cause high-level tendon strain during maximum effort muscle contractions and lead to tendon structural impairments and an increased risk for tendinopathy in adolescent athletes. However, it remains unclear whether the development of musculotendinous imbalances is influenced by sex. At four measurement time points during a competitive season, we measured quadriceps femoris muscle strength and patellar tendon mechanical properties in 15 female (14.3 ± 0.7 years) and 13 male (16.0 ± 0.6 years) elite handball players of similar maturity using dynamometry and ultrasonography. To estimate the tendon's structural integrity, the peak spatial frequency (PSF) of proximal tendon ultrasound scans was determined. Females demonstrated significantly lower muscle strength (p < 0.001) and patellar tendon stiffness (p < 0.001) than males with no significant changes over time (p > 0.05). Tendon strain during isometric maximum voluntary contractions and PSF neither differed between sexes nor changed significantly over time (p > 0.05). We found lower fluctuations in muscle strength (p < 0.001) in females during the season but no differences in the fluctuations of tendon strain, stiffness, and PSF (p > 0.05). Descriptively, there was a similar frequency (~40%) of athletes with high-level tendon strain (>9%) in both sexes. These findings suggest that the lower strength capacity of female athletes is paralleled by lower tendon stiffness. Thereby, muscle-tendon imbalances occur to a similar extent in both sexes leading to increased strain levels during the season, which indicates the need for specific tendon training.

Surgical treatment of chronic proximal patellar tendon tears grades 3 and 4 using augmentation with quadriceps tendon-bone graft

BACKGROUND

Chronic proximal patellar tendinosis with partial tendon tears represents a multifactorial overuse injury. Several surgical techniques have been described with various outcomes and the return to sports may fail.

HYPOTHESIS

Reconstruction of the proximal patellar tendon with augmentation using a quadriceps tendon-bone (QTB) graft improves knee function in patients presenting with proximal patellar tendinosis and partial tendon tears.

METHODS

Forty-seven patients (32 males, 15 females) with chronic proximal patellar tendinosis and tendon tears grade 3 and 4 were treated between 1992 and 2018. Patients were evaluated retrospectively using the Popkin-Golman (PG) MRI grading system and the removed tendon parts. The Tegner Activity Scale (TAS) and the Numerical Rating Scale (NRS) for pain were used as outcome measures before surgery and at follow up. Complete data were available in 100% of cases at 6 months follow up, and fifteen of them at later follow up.

RESULTS

The average follow up was 1.5 years (range, 0.5-16). The TAS improved from a mean preoperative score of 3.7 to a mean postoperative score of 9.1. The median NRS status decreased from an average of 6.4 to 1.1. Two patients needed additional arthroscopic scar tissue removal.

CONCLUSION

Reconstruction of proximal patellar tendon tears grades 3 and 4 with augmentation using a QTB graft is a valuable surgical salvage procedure in chronic cases. It improves knee function and yields good to excellent results in most cases including high level athletes. The use of MRI with the PG classification of tendon tears is highly recommended.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Patellar Tilt and Patellar Tendon-Trochlear Groove Angle Present the Optimum Magnetic Resonance Imaging Diagnostic Reliability for Patients With Patellar Instability

PURPOSE

To describe, in controls and in a population with patellar instability, magnetic resonance imaging values of measurements representing major associated factors for patellar instability (patellar height, trochlear dysplasia, and extensor mechanism alignment), as well as their cutoff values.

METHODS

In total, 323 knee magnetic resonance imaging scans, 142 with patellar instability and 181 controls without patellofemoral complaints (anterior cruciate, medial collateral ligament, meniscus ruptures or normal) were evaluated. Means, normality values in the control population, ideal cutoff values through receiver operating characteristic curves analysis, and interobserver reliability (intraclass correlation coefficient) were described for a series of measurements.

RESULTS

All measurements were statistically different in control and instability patients, except for the patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance. The interobserver intraclass correlation coefficient was good or excellent (above 0.75) only for the patellotrochlear index, patellar tendon-trochlear groove (PTTG) angle, and patellar tilt. The optimal cutoff value for each measurement was: PTTG angle ≥25.3o with sensitivity (S) of 70% and specificity (E) of 89%, patellar tilt ≥16o (S: 69% and E: 84%), trochlear sulcus angle ≥153o (S: 75% and E: 76%), Carrillon ≤12.8o (S: 62% and E: 87%), PTTG distance ≥11mm (S: 71% and E: 78%), Caton-Deschamps index ≥1.23 (S: 72% and E: 76%) and trochlear bump ≥3.95 mm (S: 76% and E: 65%).

CONCLUSIONS

Caton-Deschamps index (≥1.23), trochlear sulcus angle (≥153o), ventral prominence of the trochlea (≥3.95 mm), PTTG distance (≥11 mm), PTTG angle (≥25.3o), Carrillon angle (≤12.8o), and patellar tilt (≥16o) presented better diagnostic performance for patellar instability. Patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance were not related to patellar instability. The interobserver reliability of the factors related to patellar instability was excellent only for the PTTG angle and lateral patellar tilt.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Evaluation of Anatomical Variations with Morphological Measurements and Their Relationship to Meniscal Injury and Ligament Damage

The purpose of this study was to reveal the anatomical risk factors for anterior and posterior cruciate ligament (ACL and PCL) injuries and menisci injury. We aim to investigate whether there are significant relationships between tibial tubercle-trochlear groove (TT-TG) distance, patella angle, trochlear sulcus angle (TSA), trochlear groove depth (TGD), medial and lateral trochlea length (MT and LT), MT/LT ratio, lateral patellar tilt angle (LPTA), patella-patellar tendon angle (P-PTA), quadriceps-patellar tendon angle (QPA), Insall-Salvati index (ISI), medial and lateral trochlear inclination (MTI and LTI) measurements and important common pathologies such as ACL, PCL, medial and lateral meniscal injuries (MM and LM), peripatellar fat pad edema, chondromalacia, and effusion. Thus, the mechanisms of injury will be better understood by revealing important anatomical variations for meniscus and ligament damage. Three hundred eighty patients with knee magnetic resonance imaging examination were included in this study. Our patients who underwent knee magnetic resonance imaging were divided into groups according to the presence of MM tear, LM tear, ACL tear, PCL tear, peripatellar fat pad edema, chondromalacia and effusion. TT-TG distance, patella angle, TSA, TGD, MT, LT, MT/LT ratio, LPTA, P-PTA, QPA, ISI, MTI, and LTI were measured. In patients with ACL tear, age, LT, ML/LT ratio, and QPA measurements were found to be significantly higher. There was no significant difference between the participants' LPTA value and the presence of ACL tear, MM and LM injury. MT and ML/LT ratio were found to be significantly lower in the group with MM tear (p <0.001). The TT-TG distance was found to be significantly lower in the group with LM tear. Increased age, LT, ML/LT ratio, and QPA are predisposed risk for ACL tear. Decreased MT and ML/LT ratio are among the risk factors for MM tear. The anatomical variations are associated with ligament and meniscal injury.

The Effect of Specific Bioactive Collagen Peptides on Tendon Remodeling during 15 wk of Lower Body Resistance Training

PURPOSE

Collagen peptide supplementation has been reported to enhance synthesis rates or growth in a range of musculoskeletal tissues and could enhance tendinous tissue adaptations to resistance training (RT). This double-blind placebo-controlled study aimed to determine if tendinous tissue adaptations, size (patellar tendon cross-sectional area (CSA) and vastus lateralis (VL) aponeurosis area), and mechanical properties (patellar tendon), after 15 wk of RT, could be augmented with collagen peptide (CP) versus placebo (PLA) supplementation.

METHODS

Young healthy recreationally active men were randomized to consume either 15 g of CP ( n = 19) or PLA ( n = 20) once every day during a standardized program of lower-body RT (3 times a week). Measurements pre- and post-RT included patellar tendon CSA and VL aponeurosis area (via magnetic resonance imaging), and patellar tendon mechanical properties during isometric knee extension ramp contractions.

RESULTS

No between-group differences were detected for any of the tendinous tissue adaptations to RT (ANOVA group-time, 0.365 ≤ P ≤ 0.877). There were within-group increases in VL aponeurosis area (CP, +10.0%; PLA, +9.4%), patellar tendon stiffness (CP, +17.3%; PLA, +20.9%) and Young's modulus (CP, +17.8%; PLA, +20.6%) in both groups (paired t -tests (all), P ≤ 0.007). There were also within-group decreases in patellar tendon elongation (CP, -10.8%; PLA, -9.6%) and strain (CP, -10.6%; PLA, -8.9%) in both groups (paired t -tests (all), P ≤ 0.006). Although no within-group changes in patellar tendon CSA (mean or regional) occurred for CP or PLA, a modest overall time effect ( n = 39) was observed for mean (+1.4%) and proximal region (+2.4%) patellar tendon CSA (ANOVA, 0.017 ≤ P ≤ 0.048).

CONCLUSIONS

In conclusion, CP supplementation did not enhance RT-induced tendinous tissue remodeling (either size or mechanical properties) compared with PLA within a population of healthy young men.

Anisotropy and reproducibility of ultrasound shear wave elastography in patella tendons with and without tendinopathy

PURPOSE

Ultrasound shear wave elastography (SWE) is a tool that can be utilized to assess biomechanical properties of tendons. Anisotropy, an ultrasound imaging artifact has been commonly cited as a potential source of error in the accuracy and reproducibility of SWE. The aim of the study was to assess reproducibility in performing SWE of patella tendons and differences in SWE and anisotropy between normal patella tendons and patellar tendinopathy.

METHODS

After obtaining the Institutional Review Board approval and written informed consent, we prospectively measured the shear wave velocity (SWV) of patella tendons with and without tendinopathy in 25 volunteers. SWVs were measured in three anatomic planes: longitudinal, perpendicular transverse, and tilted transverse with the probe tilted 15-30° from the perpendicular transverse plane by three operators with varied levels of experience. Anisotropy coefficient (A) was calculated by formula of A = (SWVLongitudinal - SWVTransverse) / SWVTransverse.

RESULTS

Differences in SWV and anisotropy coefficient between normal tendons and tendons with tendinopathy were significant (p < 0.05). The intra- and inter-observer reproducibility in performing SWE were moderate to good (intraclass correlation coefficient: 0.81-0.95). The mean difference of 95% Bland-Altman limits of agreement for measuring tendon SWV ranged -0.08 to 0.41 (upper 0.08 to 1.14, lower -1.22 to -0.22) between senior and junior operators.

CONCLUSION

The results of this study suggest that SWE and anisotropy coefficient are feasible tools to differentiate patellar tendinopathy from normal patella tendons. The reproducibility of performing SWE of patella tendons is moderate to good.

Challenging the assumption of uniformity in patellar tendon structure: Regional patellar tendon morphology and mechanical properties in vivo

Patellar tendons are assumed to be uniform in morphology and mechanical properties despite a higher prevalence of tendinopathies observed in the medial region. The purpose of this study was to compare the thickness, length, viscosity, and shear modulus of the medial, central, and lateral regions of healthy patellar tendons of young males and females in vivo. B-mode ultrasound and continuous shear wave elastography were performed on 35 patellar tendons (17 females, 18 males) over three regions of interest. A linear mixed-effects model (α = 0.05) was used to determine differences between the three regions and sexes followed by pairwise comparisons for significant findings. The lateral region (mean [95% confidence interval] = 0.34 [0.31-0.37] cm) was thinner compared with the medial (0.41 [0.39-0.44] cm, p < 0.001), and central (0.41 [0.39-0.44] cm, p < 0.001) regions regardless of sex. Viscosity was lower in the lateral (19.8 [16.9-22.7] Pa-s) versus medial region (27.4 [24.7-30.2] Pa-s, p = 0.001). Length had a region-by-sex interaction (p = 0.003) characterized by a longer lateral (4.83 [4.54-5.13] cm) versus medial (4.42 [4.12-4.72] cm) region in males (p < 0.001), but not females (p = 0.992). Shear modulus was uniform between regions and sexes. The thinner, and less viscous lateral patellar tendon may reflect the lower load the tendon experiences explaining the differences in regional prevalence of developing tendon pathology. Statement of Clinical Significance: Healthy patellar tendons are not uniform in morphology or mechanical properties. Considering regional tendon properties may help guide targeted interventions for patellar tendon pathologies.

AN INTRATENDINOUS GANGLION CYST OF THE PATELLAR TENDON: A RARE CAUSE OF ANTERIOR KNEE PAIN

Ganglion cysts in the knee region can manifest as anterior knee pain. Unlike synovial cysts, these lesions lack synovial epithelial lining and occur secondary to mucoid degeneration of connective tissue because, often in response to chronic irritation and repetitive traumas. However, an intratendinous location is a rare finding. In the knee region, infrapatellar fat pad, the alar folds, and the anterior cruciate ligament are recognized to degenerate into ganglion. There are few case reports describing an involvement of the patellar tendon. We present the clinical case of a 72 years old male patient suffering from anterior knee pain attributed to an intratendinous ganglion cyst of the patellar tendon, obviously after a single traumatic event. After aspiration of the ganglion cyst the patient reported no complaints, and there has been no recurrence during the latest follow-up examination.

Delaminated Patellar Tendon Rupture in a Pediatric Patient: A Case Report

CASE

We present a 12-year-old boy with partial delamination of the patellar tendon in the coronal plane and bipolar avulsion fracture of the tibial tubercle and patella after a planting injury while skateboarding. Pediatric patellar tendon rupture with associated bipolar avulsion fractures is rare. Furthermore, to the best of our knowledge, a delamination injury pattern of the patellar tendon has not been described.

CONCLUSION

This type of extensor mechanism injury has not been reported in the literature. Repair with Krackow sutures and suture-bone tunnel technique, with consideration of the proximal tibial physis, is a safe and effective way to fix this unique pathology.

Reconstruction of medial patellofemoral ligament with adductor magnus tendon for recurrent patellar dislocation in children: a retrospective comparative cohort study

BACKGROUND

The purpose of current retrospective study was to explore the outcomes of using the adductor magnus tendon to reconstruct the medial patellofemoral ligament in the treatment of recurrent patellar dislocation in children.

METHOD

Thirty-two children with recurrent patellar dislocation were selected. Sixteen cases in the conservative group, seven males and nine females, with an average age of 11.81 ± 1.28 years; sixteen cases in the surgical group, eight males and eight females, with an average age of 11.56 ± 1.15 years. All patients had no surgery history. The IS index (> 1.2), Q angle (> 20°) and tibial tubercle-femoral trochlear groove (TT-TG) distance (> 20 mm) were measured by X-ray and MRI. The conservative group was treated with closed reduction and a brace, and the surgical group received surgical treatment. Two years after surgery, congruence angle (CA) (- 6° to 6°) and lateral patellofemoral angle (LPFA) (7.7°-18.7°) were measured by X-ray image and all children were evaluated based on Kujala and Lysholm scores. The re-dislocation rate was recorded. Analysis was performed by t test and chi-square with the statistical SPSS software. P < 0.05 was considered a statistically significant difference. Furthermore, we measured the length (mm) of the adductor tendon and MPFL in three knee cadaveric specimens, and also observed the positional relationship between the two structures.

RESULT

There were no significant differences in sex, age, injury site between groups (P > 0.05). Patients in the two groups were followed up for 2 years in average. Among the 16 cases in the conservative group, 7 cases (43.75%) had recurrence of patellar dislocation, while none of recurrence in the surgical group (P < 0.05). The Lysholm score of the surgical group (94.63 ± 8.99) was significantly better than that of the conservative group (79.31 ± 18.90), and the Kujala score of the surgery group (95.25 ± 10.32) was also significantly better than that of the conservative group (77.06° ± 14.34°) (P < 0.05). The CA and LPFA of the two groups of patients after treatment were significantly recovered. The CA (- 5.81° ± 7.90°) in the surgical group was significantly better than that in the conservative group (20.94° ± 8.21°), and the LPFA (6.44° ± 3.22°) was also significantly better than that in the conservative group (- 9.18 ± 11.08), and the difference is statistically significant (P < 0.05). We found it through autopsy that adductor magnus tendon was 124.33 ± 1.53 mm long, MPFL was 48.67 ± 2.08 mm, and the femoral insertion of the adductor magnus tendon was adjacent to the MPFL femoral insertion.

CONCLUSION

Reconstruction of Medial patellofemoral ligament with the adductor magnus tendon, fixing with PEEK suture anchors on the patellar side, can achieve satisfactory results in the treatment of children with recurrent patellar dislocation. Compared with conservative treatment, the rate of recurrence is lower and the stability of the patella is better.

Acute Irreducible Rotational Patellar Dislocation with Patellar Tendon Rupture: A Case Report

CASE

In this report, we present a case of acute patellar dislocation with both vertical and longitudinal rotation of the patella. As a result of rotation in the longitudinal axis, the articular surface of the patella faced outward, and the dorsal surface faced the femoral condyle. The patient underwent open reduction. One year after open reduction and soft-tissue repair, the patient had acceptable knee function and no knee pain.

CONCLUSION

This case shows how similar cases may be treated with an open reduction to properly address the patellar dislocation.

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.

Proximal patellar tendon abnormalities on ultrasound can develop in male adolescent basketball players: A longitudinal study

INTRODUCTION

Adolescent patellar tendinopathy is reported but the pubertal-stage of onset of abnormal tendon structure has not been investigated with grayscale ultrasound.

AIMS

To investigate abnormal tendon structure using grayscale ultrasound and its association with pubertal-stage and pain.

METHODS

Forty-three male basketball players aged 13.7 years (SD 1.0) had patellar tendon ultrasound scans every 6 months for 2.5 years. Pubertal-stage (peak height velocity) was calculated using the Mirwauld equation. Tendon thickness, hypoechogenicity and pain during single leg decline squat (SLDS) were recorded. Tendons were classified: hypoechoic, normal or immature.

RESULTS

Two tendons were hypoechoic at baseline. Six developed hypoechogenicity over 2.5 years (eight tendons [9%], six participants [14%]), all in peri and post-PHV players. Twenty-six tendons (17 participants) were classified as immature during the study. Hypoechoic tendons were thicker (5.3 mm SD 1.2) than normal (3.9 mm SD 0.7) tendons (p < 0.001). There was no difference in the proportion of participants reporting pain during SLDS in the hypoechoic (N = 3) and normal (N = 11) groups (p = 0.33), or in hypoechoic tendon thickness between those reporting pain (6.5 mm, SD 1.7) or not (5.2 mm, SD 0.9, p = 0.17).

DISCUSSION

This study using grayscale ultrasound found that basketball players with hypoechogenicity were peri or post-PHV. Abnormal structure was not always associated with pain.

Infrared Thermography, Intratendon Vascular Resistance, and Echotexture in Athletes with Patellar Tendinopathy: A Cross-Sectional Study

Ultrasonographic signs of tendinopathies are an increase in thickness, loss of alignment in collagen fibers and the presence of neovascularization. Nevertheless, analysis of intratendinous vascular resistance (IVR) can be more useful for understanding the physiological state of the tissue. To show thermal, echotextural, and Doppler signal differences in athletes with patellar tendinopathy and controls. Twenty-six athletes with patellar tendinopathy (PT) participants (30.1 years; SD = 9.0 years) and 27 asymptomatic athletes (23.3 years; SD = 5.38 years) were evaluated with thermographic and Doppler ultrasonography (DS). Area of Doppler signals (DS), echotextural parameters (echointensity and echovariation) and IVR were determined by image analysis. The statistical analysis was performed by Bayesian methods and the results were showed by Bayes Factor (BF10: probability of alternative hypothesis over null hypothesis), and Credibility intervals (CrI) of the effect. The absolute differences of temperature (TD) were clearly greater (BF10 = 19) in the tendinopathy group (patients) than in controls. Regarding temperature differences between the affected and healthy limb, strong evidence was found (BF₁₀ = 14) for a higher temperature (effect = 0.53°C; 95% CrI = 0.15°C-0.95°C) and very strong for reduced IVR compared (BF₁₀ = 71) (effect = -0.67; 95% CrI = -1.10 to 0.25). The differences in area of DS (BF₁₀ = 266) and EV (BF₁₀ = 266) were higher in tendinopathy group. TD showed a moderate positive correlation with VISA-P scores (tau-B = .29; 95% CrI = .04-.51) and strong correlation with IVR (r = -.553; 95%CrI = -.75 to .18). Athletes with patellar tendinopathy showed a more pronounced thermal difference, a larger area of Doppler signal, a lower IVR and a moderately higher echovariaton than controls. The correlation between temperature changes and IVR might be related with the coexistence of degenerative and inflammatory process in PT.

Tendon appearance at imaging may be altered, but it may not indicate pathology

Both in tendon repair following a tear and in tendinopathy, recovery from pain and restoration of (acceptable) function does not go hand in hand with the appearance of the affected tendon at imaging. The tendon may remain altered for a long while and possibly forever, indicating a possible dissociation between morphology and symptoms. The predictive value of asymptomatic abnormal findings remains limited, and interventions in such instances are inappropriate and not supported by current evidence. Once an initial imaging investigation has depicted the condition of the tendon, additional imaging investigations are unlikely to provide further information or change prognosis in patients in whom abnormalities compatible with a diagnosis of tendinopathy have been identified by either ultrasonography or MRI. Patient education and close clinical monitoring are recommended. This is applicable to the patellar tendon, Achilles tendon, rotator cuff, for both tendon repair and tendinopathy. Given the modest risk of sonographic abnormalities to develop in symptomatic tendinopathy, planning and trying to implement any form of intervention may not be warranted. The current evidence mostly arises from low-quality studies, with heterogeneous risk factors and populations, and caution must be maintained when interpreting the significance of such incidental findings in athletes.

B-Mode Ultrasonography Is a Reliable and Valid Alternative to Magnetic Resonance Imaging for Measuring Patellar Tendon Cross-Sectional Area

This study investigated the validity and reliability of measuring patellar tendon (PT) cross-sectional area (CSA) using magnetic resonance imaging (MRI) and ultrasound (US) imaging. Nineteen healthy participants (10 women, 9 men) participated in three imaging sessions of the PT, once via MRI and twice via US, with image acquisition conducted by two raters, one experienced (rater 2) and one inexperienced (rater 1). All PT segmentations were analyzed by both raters. The validity of US-derived estimates of PT CSA against MRI estimates was analyzed using linear regression. Within-day reliability of US and MRI measurements and between-day reliability of US measurements were quantified using typical error (TE) and intra-class correlation coefficients (ICC_3,1). There was good agreement between US- and MRI-derived estimations of PT CSA (standard errors of the estimate of 3.3 mm² for rater 1 and 2.6 mm² for rater 2; Pearson's r = 0.97 and 0.98 for raters 1 and 2, respectively). Within-session reliability for estimations of total PT CSA from US and MRI were excellent (ICC_3,1 >0.95, coefficient of variation [CV] <4.1%, TE = 1.3-3.6 mm². Between-day reliability for US was excellent (ICC_3,1 >0.97, CV <2.7%, TE = 1.6-2.3 mm²), with little difference between raters. These findings suggest that MRI and US both provide reliable estimates of PT CSA and that US can provide a valid measure of PT CSA.

Sonographic Screening of Distance Runners for the Development of Future Achilles and Patellar Tendon Pain

OBJECTIVE

The 2 primary aims of this study were to identify ultrasonographic tendon abnormalities in asymptomatic runners and to examine the likelihood of developing pain in runners with ultrasound abnormalities compared with those without abnormalities.

DESIGN

Longitudinal, prospective cohort study.

SETTING

2019 Salt Lake City Marathon.

PARTICIPANTS

Recreational half-marathon and full-marathon runners.

ASSESSMENT OF RISK FACTORS

The Achilles and patellar tendons of asymptomatic runners were examined with ultrasound imaging before a running event. Runners were monitored for self-reported outcomes of pain in the examined tendons at 1, 3, 6, and 12 months after the event.

MAIN OUTCOME MEASURES

Development of pain based on the presence of asymptomatic tendon abnormalities.

RESULTS

One hundred thirty-eight runners (36.2 ± 12.0 years, 49.3% men, and 31.2% full-marathon runners) were included. Ultrasound abnormalities of the Achilles and patellar tendons were identified in 24.6% and 39.1% of the runners before the race, respectively. Ultrasound abnormalities were significantly associated with approximately a 3-fold increase [hazard ratio (HR) = 2.55, P = 0.004] in the hazard of developing pain in the Achilles tendon and patellar tendon (HR = 1.67, P = 0.042) over the year after the race. Positive and negative predictive values of developing pain over the year were 34.1% and 87.2%, respectively, for abnormal findings in the Achilles tendon, and 22.9% and 85.0%, respectively, for the patellar tendon.

CONCLUSIONS

The presence of ultrasonographic abnormalities is associated with increased development of pain in the Achilles and patellar tendons within 1 year of a marathon or half marathon.

Shear-Wave Elastography of Patellar Ligament and Achilles Tendon in Semiprofessional Athletes: Comparing With Nonexercising Individuals

OBJECTIVES

To compare semiprofessional athletes and nonexercising individuals in terms of p-SWE properties of the patellar ligament and the Achilles tendon.

METHODS

This case-control study was conducted in University of Health Sciences, Haseki Education and Research Hospital. A total of 58 individuals, with 29 in each group (according to power analysis), were included in the study. All relevant findings, including demographic characteristics, body mass index (BMI), and exercise (km run per week, km/w) were recorded. The MyLab 9 (Esaote, Genova, Italy) device was used for SWE. The QElaXto-p-SWE software was utilized for P-SWE interpretation and analyses.

RESULTS

The mean age was 47.21 ± 12.16 years (range 22-70). Weight (P = .001) and BMI (P < .001) values were significantly higher in the nonathlete group than in the athlete group. There were no significant differences between groups in terms of age, gender, and height. Median SWE values of bilateral patellar ligaments (P < .001 and P < .001) and bilateral Achilles tendons (P < .001 and P < .001) were significantly higher in the athlete group than in the nonathlete group.

CONCLUSIONS

We revealed normal p-SWE characteristics for the patellar ligament and Achilles tendon, which are frequently injured in athletes. These scores are important in early detection and follow-up of injuries in athletes.

Ultrasound imaging of patellar tendon thickness in elite sprint track cyclists and elite soccer players: An intra-rater and inter-rater reliability study

The goal of our study was to investigate the relative and absolute intra-rater and inter-rater reliability of ultrasound assessment of patellar tendon (PT) thickness assessed over four locations, in track cyclists and soccer players. Fifteen male elite track cyclists and 15 male elite soccer players participated. Tendon thickness was measured over 4 locations placed at 5-10-15-20 mm inferior to the apex of the patella by two experienced examiners. Each examiner took two US images for the test measurements with a 10-min rest period. After a 30-min period, the subjects underwent a retest measurements that were also repeated 1-week after. A two-way analysis of variance revealed a significant group x location interaction on PT thickness for Examiner 1 (p = .001, η² = .81) and Examiner 2 (p = 0.001, η² = 0.78). Intra-rater reliability ranged from good to excellent (ICC_2,k ≥ 0.75), whereas inter-rater reliability was good (ICC_2,k ≥ 0.75) in both groups. Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT (corresponding to 15 and 20 mm) can be considered the most reliable spot to measure PT thickness. The PT thickness was larger among track cyclists than soccer players, with larger differences over the distal location (15 mm). Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT corresponding to 15 mm and 20 mm can be considered the most reliable area to measure PT thickness.

[Measurement of external deviation angle of patellar tendon and its application on diagnosis of recurrent patellar dislocation]

OBJECTIVE

To compare computed tomography (CT) measurement results of external deviation angle of patellar tendon and tibia tubercle-trochlea groove (TT-TG), as well as the diagnostic ability and pathology in recurrent patellar dislocation threshold.

METHODS

From January 2015 to March 2020, 46 patients with recurrent patella dislocation and 112 patients with non-patella dislocation were retrospectively analyzed. Forty-six patients with recurrent patella dislocation were divived into 2 groups according to TT-TG value, 11 patients with patellar dislocation with TT-TG≥20 mm(group A), including 7 males and 4 females, aged from 16 to 27 years old with an average of(21.00±3.98) years old; 35 patients with patellar dislocation with TT-TG<20 mm(group B), including 14 males and 21 females, aged from 16 to 37 years old with an average of(22.83±6.09) years old. While 112 patients with non-patella dislocation(group C) included 63 males and 49 females, aged 16 to 36 years old with an average of(22.87±5.69) years old. The measurement data of external deviation angle of patellar tendon and TT-TG value among three groups were compared. Spearman analysis was used to analyze correlation among them. Intraclass correlation coefficient (ICC) was used to determine repeatability within group. Receiver operating characteristic (ROC) area under the curve was used to evaluate diagnostic ability of parameters, and calculate osteotomy parameters of external deviation angle of patellar tendon, as well as external deviation angle of patellar tendon and TT-TG value in the diagnosis of recurrent patella diagnostic parameters of dislocation.

RESULTS

External deviation angle of patellar tendon in group A, B and C was (22.04±3.09)°, (17.20±4.43)°and (10.22±3.45)° respectively;while TT-TG value was(21.15±0.71) mm, (15.97±2.69) mm and (11.12±3.77) mm, there were significance among three groups (P<0.01), and had difference between group A and B(P<0.01). There was strong positive correlation between external deviation angle of patellar tendon and TT-TG value (r=0.735, P<0.000 1). The intra-group ICC value(0.980, 0.982) of external deviation angle of patellar tendon in group A and B have better repeatability than TT-TG value (0.594, 0.775). The external deviation angle of patellar tendon in group C(0.956) and repeatability of TT-TG value(0.906) was very good. In the diagnosis of recurrent patellar dislocation, the area under ROC curve of external deviation angle of patellar tendon (0.916) was greater than TT-TG value(0.886), and diagnostic parameters were 13.84°and 14.69 mm, respectively;in tibial osteotomy, the area under ROC curve of external deviation angle of patellar tendon was 0.821, and osteotomy parameter was 20.15°.

CONCLUSION

CT imaging could reliably measure external deviation angle of patellar tendon.There is a strong positive correlation between external deviation angle of patellar tendon and value of TT-TG, which could be used to determine pathological state of recurrent patellar dislocation, and external deviation angle of patellar tendon is superior to the TT-TG value in the diagnosis of recurrent patellar dislocation. The external deviation angle of patellar tendon could also be used to guide the formulation of the tibial osteotomy plan for recurrent patellar dislocation.

[Quantitative analysis of patellar tendon elasticity of amateur marathon runners after a competition based on shear wave elastography]

Objective: To analyze the changes of patellar tendon elasticity quantitatively of amateur marathon runners by shear wave elastography (SWE) in a half marathon. Methods: A total of 47 amateur marathon runners (31 males and 16 females, aged from 20 to 44 years) were enrolled as the marathon group, and divided into dominant side (47 patellar tendons) and non-dominant side (47 patellar tendons). Grey-scale ultrasound and SWE were performed on the bilateral patellar tendons before and after the half marathon within 2 h and after a period of 1 week. Thirty healthy volunteers (18 males and 12 females, aged from 22 to 39 years) were enrolled as the control group, the SWE-values derived from the patellar tendon were collected and analyzed. Multivariate logistic regression was performed to analyze the relationship between the changes of SWE-values and running age as well as weekly amount of running. Results: None of any runners showed knee pain and sports injury during the test. The dominant side had a higher SWE-values than non-dominant side in marathon group before running [(55.1±15.7) kPa vs (43.8±15.9) kPa, P<0.05]. The marathon group had higher SWE-values than the control group both in dominant side [(55.1±15.7) kPa vs (18.5±3.7) kPa] and non-dominant side [(43.8±15.9) kPa vs (17.4±3.2) kPa], respectively, before running (P<0.05). The SWE-values increased significantly both in dominant side [(80.2±23.2) kPa vs (55.1±15.7) kPa] and non-dominant side [(76.5±26.6) kPa vs (43.8±15.9) kPa] 2 h after running in marathon group. After a week, the SWE-values were not statistically different from those before running (P>0.05). Multivariate logistic regression showed that running age and weekly amount of running were related factors leading to the increase of SWE-values after running. Conclusions: The patellar tendon of amateur marathon runners has higher SWE-values. SWE can dynamically evaluate the changes of patellar tendon during exercise and is helpful for runners in scientific training and avoiding sports injury.

Near infrared spectroscopic evaluation of biochemical and crimp properties of knee joint ligaments and patellar tendon

Knee ligaments and tendons play an important role in stabilizing and controlling the motions of the knee. Injuries to the ligaments can lead to abnormal mechanical loading of the other supporting tissues (e.g., cartilage and meniscus) and even osteoarthritis. While the condition of knee ligaments can be examined during arthroscopic repair procedures, the arthroscopic evaluation suffers from subjectivity and poor repeatability. Near infrared spectroscopy (NIRS) is capable of non-destructively quantifying the composition and structure of collagen-rich connective tissues, such as articular cartilage and meniscus. Despite the similarities, NIRS-based evaluation of ligament composition has not been previously attempted. In this study, ligaments and patellar tendon of ten bovine stifle joints were measured with NIRS, followed by chemical and histological reference analysis. The relationship between the reference properties of the tissue and NIR spectra was investigated using partial least squares regression. NIRS was found to be sensitive towards the water (R2_CV = .65) and collagen (R2_CV = .57) contents, while elastin, proteoglycans, and the internal crimp structure remained undetectable. As collagen largely determines the mechanical response of ligaments, we conclude that NIRS demonstrates potential for quantitative evaluation of knee ligaments.

Reliability of a New Semi-automatic Image Analysis Method for Evaluating the Doppler Signal and Intratendinous Vascular Resistance in Patellar Tendinopathy

The aim of this study was to determine the intra- and inter-rater reliability of a new semi-automatic image analysis method for quantification of the shape of the Doppler signal and the intratendinous vascular resistance in patellar tendinopathy. Thirty athletes (27.4 y, standard deviation = 8.57 y) with patellar intratendinous vascularity were included in a cross-sectional study (42 tendons analyzed). The intratendinous blood flow was assessed with power Doppler and ImageJ (Version 1.50b, National Institutes of Health, Bethesda, MD, USA) quantification software over a manually selected region of interest. Two blinded observers performed the analysis of the Doppler signal (vascular resistance) and shape descriptors (number of signals, pixel intensity, area, perimeter, major diameter, minor diameter, circularity and solidity). The intraclass correlation coefficient (ICC) was calculated, and the Bland-Altman mean of differences (MoD) and 95% limits of agreement (LoA) were determined. Also, small real differences (SRDs) and the standard error of measurement (SEM) were calculated. Intra-rater reliability was at a maximum for area (ICC = 0.999, 95% confidence interval [CI] = 0.998-0.999) and at a minimum for solidity (ICC = 0.782, 95% CI: 0.682-0.853). The MoD and 95% LoA were very low, and the relative SRD and SEM were below 5.3% and 2%, respectively. The inter-rater reliability was the maximum for area (ICC = 0.993, 95% CI = 0.989-0.996) and the minimum for circularity (ICC = 0.73; 95% CI=0.611-0.817). The MoD and 95% LoA were low, with the SRD and SEM below 6% and 2.2%. The proposed quantitative method for studying the intratendinous Doppler signal in the patellar tendon is reliable and reproducible.

Effect of Knee Angle and Quadriceps Muscle Force on Shear-Wave Elastography Measurements at the Patellar Tendon

Shear-wave elastography (SWE) is a non-invasive imaging technique that provides estimates of tissue stiffness via shear-wave speed measurements. No standardized protocol currently exists for SWE of the patellar tendon, which may be influenced by knee angle and quadriceps muscle force. In this study, the reliability of SWE in cadaveric patellar tendons was examined at three knee angles (0°, 30° and 60°) and three quadriceps muscle forces (0, 50 and 100 N). Shear-wave speed was significantly higher at a knee angle of 60° than at 0° or 30° (increases of 7% and 9%, respectively), and when the quadriceps muscle force was greater than or equal to 50 N (increase of 15%). SWE of the patellar tendon displayed excellent repeatability regardless of knee angle as long as no quadriceps force was generated (intra-class correlation coefficient ≥0.91). This research illustrates the importance of controlling knee angle and quadriceps force for consistency and comparison of SWE results.

Bone-Patellar Tendon-Bone Autograft Thickness Is a Risk Factor for Graft Failure. A Case-Control Analysis

BACKGROUND

Graft failure following anterior cruciate ligament reconstruction (ACLR) is a devastating complication. Risk factors such as patient characteristics and tunnel positions are well described. The relationship between graft dimension and failure rates has been investigated mainly in soft tissue grafts. Less studied are the effects of patella tendon (PT) dimensions on the risk of graft failure following patella tendon autograft (PTA) reconstructions.

PURPOSE

The purpose of the current study was to investigate if patellar tendon thickness measured on preoperative magnetic resonance imaging (MRI) predicts failure after ACLR using PTA.

METHODS

This was an institutional review board approved, single-center, retrospective case-control study comparing patients' preoperative patellar tendon thickness between July 2005 and January 2017. Sixteen patients (mean age 21.2 ± 5.0 years) with PTA failure requiring revision surgery were identified and compared to 34 control patients who had undergone primary ACLR with PTA without failure with a minimum of 2-years follow-up. Patients with failure were matched at approximately 1:2 based on age, sex, height, weight, associated meniscus injury, and associated meniscal surgery. Patellar tendon dimensions were measured at the inferior pole of the patella (IPP), tibial tubercle insertion (TT), and longitudinal midpoint (MP) on preoperative axial and sagittal cut MRIs. Interclass correlation coefficeint (ICC) and Bland-Altman analyses were evaluated to determine inter-observer reliability. The two cohorts were compared using independent samples t-tests and analysis of variance.

RESULTS

All ACLR failures occurred after a non-contact, pivot type injury. There were no significant differences in age, sex, height, weight, meniscal injury, or meniscal surgery between the two groups. Mean time between primary ACLR and revision was 2.6 ± 2.6 years and mean follow-up time was 3.1 ± 1.0 years in the control group. Patellar tendon length and width were not significantly different between the two groups. The average thickness at both the inferior pole and longitudinal midpoint was significantly higher in the failure group compared to controls (IPP: 5.04 ± 1.1 mm versus 4.33 ± 0.7 mm, p = 0.01; MP: 4.60 ± 0.7 mm versus 4.22 ± 0.5 mm, p = 0.03). Additionally, ICC was high across all measurements, with all values > 0.978. Similarly, all values demonstrated bias of less than ± 0.05.

CONCLUSION

Patella tendon autograft anterior cruciate ligament reconstruction failures had significantly thicker patellar tendons at the inferior pole and longitudinal midpoint of the patella tendon.

Influence of Bias in the Assessment of Patellar Tendon Stiffness: A Systematic Review and Meta-analysis

The aim of the present study was to provide a systematic review and meta-analysis of the main biases in practical applications of the different types of elastography in assessment of the stiffness of healthy patellar tendons. A literature search on four databases (Scopus, Web of Science, Pubmed and SportDiscus) was conducted on March 25, 2020. After analysis of 1,052 resultant articles, studies were included if they met two inclusion criteria: (1) studies were observational or randomized controlled trials; (2) studies included outcomes of patellar tendon stiffness. Twenty-one studies met the inclusion criteria and were included in this meta-analysis. Four meta-analyses were performed with respect to assessment procedure and participant characteristics. This meta-analysis found a low effect of examined portion of patellar tendon (standardized mean difference [SMD] = 0.27, 95% confidence interval [CI]: 0.01-0.54, n = 379, Z = 2.01, p = 0.04) and a high effect of knee flexion angle during assessment (SMD = -2.12; 95% CI: -2.67 to -1.58, n = 97, Z = 7.68, p < 0.01) in stiffness outcomes. The risk of bias was generally low, but the heterogenicity of the results downgraded the level of evidence. There is evidence in the elastography assessment of patellar tendon suggesting that the knee position and patellar tendon portion evaluated influence stiffness outcomes for patellar tendon in healthy volunteers.

Substantiating the Use of Ultrasound Tissue Characterization in the Analysis of Tendon Structure: A Systematic Review

OBJECTIVE

To determine the role of ultrasound tissue characterization (UTC) in predicting, diagnosing, and monitoring tendon structure and/or tendinopathy. In addition, this study aims to provide recommendations for standardized methodology of UTC administration and analysis.

DATA SOURCE

The PubMed, Embase, and Web of Science databases were searched (up to September 2018). All scientific literature concerning the use of UTC in assessing tendons was collected. The initial search resulted in a total of 1972 hits, and after screening by eligibility criteria, 27 articles were included.

RESULTS

In total, 18 investigating the Achilles tendon, 5 the patellar tendon, and 4 both Achilles and patellar tendons were included. The methods of UTC administration and analysis differed and were not uniform. The studies showed that the use of UTC to predict Achilles tendinopathy (AT) is inconclusive, but that a higher amount of tendon disorganization increases the risk of developing patellar tendinopathy (PT). In terms of diagnosis, UTC might provide additional information in AT cases. In addition, promising results were found for the use of UTC in both AT and PT in monitoring the effect of load or treatment on tendon structure.

CONCLUSION

More research regarding the use of UTC in predicting tendon pathology is required. Ultrasound tissue characterization seems useful as an adjunct diagnostic modality because it can be used to differentiate symptomatic from asymptomatic tendons. In addition, UTC is a promising device to be used to monitor changes in tendon structure in response to load or treatment. Moreover, we provide recommendations of a standardized protocol concerning the methods of UTC measurement and analysis.

Posterior Tibial Slope in Patients Undergoing Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft: Analysis of Subsequent ACL Graft Tear or Contralateral ACL Tear

BACKGROUND

Reports on greater posterior tibial slope (PTS) and its relationship to subsequent anterior cruciate ligament (ACL) injury show conflicting results; it has not been studied much in patients after ACL reconstruction with patellar tendon autograft (PTG).

HYPOTHESIS

Patients who suffered a subsequent ACL injury would have a larger PTS than patients who did not suffer a subsequent injury after primary or revision ACL reconstruction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients received primary (n = 2439) or revision (n = 324) ACL reconstruction with PTG and were followed prospectively to determine the rate of graft tear and contralateral ACL tear. The PTS was measured preoperatively on digital lateral view radiographs. Intersecting lines were drawn along the medial tibial plateau and posterior tibia; the value of the acute angle at the lines' intersection was then subtracted from 90° to obtain the PTS. This procedure was completed by a clinical assistant with an intrarater reliability of 0.89. Chi-square analysis and t tests were used to determine the differences between rate of tears and measurements between groups. A threshold of PTS ≥10° was used for analysis.

RESULTS

The mean follow-up time was 11.6 ± 4.0 years. After primary surgery, the mean PTS in patients with graft tears was 5.4°± 3.1° versus 4.8°± 2.9° for patients without a tear (P = .041). The mean PTS was 4.9°± 3.4° for patients with contralateral tears (not statistically significantly different than the no-tear group; P = .80). Furthermore, patients with primary reconstruction with PTS ≥10° had a statistically significantly higher rate of graft tear (9.7%) than patients with PTS ≤9° (4.8%) (P = .003), but not a higher rate of contralateral tear. Among patients undergoing revision surgery, there were no statistically significant differences between the graft tear, contralateral tear, and no-tear groups with relation to PTS ≥10°.

CONCLUSION

After primary ACL reconstruction, patients with PTS >10° had a higher rate of subsequent graft tear but not a higher rate of contralateral tear. With revision surgery, there was no significant association between PTS and the rate of subsequent tear. Therefore, caution should be exercised when considering more radical interventions, such as osteotomy, to prevent retear in patients with high PTS.

Effects of Eccentric Single-Leg Decline Squat Exercise on the Morphological and Structural Properties of the Vastus Lateralis and Patellar Tendon

The purpose was to examine the effect of 6-week eccentric single-leg decline squat (SLDSe) training with two technical execution times (3 s or 6 s) on changes related to the structural properties of the vastus lateralis (VL) and patellar tendon (PT). Thirty-six physical active volunteers were randomly divided into three groups: control group (CG, n = 13, age = 20.8 ± 1.9 years, no intervention program), experimental group 1 (EG1, n = 11, age = 21.6 ± 2.5 years, execution time = 6 s) and experimental group 2 (EG2, n = 12, 21.1 ± 1.2 years, execution time = 3 s). Participants completed a 6-week SLDSe training program (80% of 1-RM) three days a week. The structural characteristics of the VL and the PT were measured with ultrasonography before and after 6-week SLDSe training and after 6 weeks of de-training. Our results indicate that EG1 increased ≈21.8% the thickness of the PT and EG2 increased ≈15.7% the thickness of the VL after the 6-week intervention program. EG1 and EG2 showed greater values (p < 0.05) of lean mass and lower values (p < 0.05) of fat percentage on the thigh after the intervention program. In conclusion, the SLDSe training carried out with the execution time of 6 s had greater effects on the structural and elastic properties of the PT, and the exercise with the execution time of 3 s caused greater structural adaptations in the VL musculature.

Reduced Levels of Aligned Fibrillar Structure Are Not Associated With Achilles and Patellar Tendon Symptoms

OBJECTIVE

To investigate whether the mean cross-sectional area (mCSA) of aligned fibrillar structure (AFS) was associated with the presence and severity of symptoms.

DESIGN

Prospective cohort study.

PARTICIPANTS

One hundred seventy-five elite male Australian football players completed monthly Oslo Sports Trauma Research Center overuse injury questionnaires for both the Achilles and patellar tendon over the season to ascertain the presence and severity of symptoms. At the start of the preseason, participants underwent ultrasound tissue characterization (UTC) imaging of the Achilles and patellar tendon.

MAIN OUTCOME MEASURES

Images were classified as normal or abnormal based on gray-scale ultrasound. Based on UTC quantification, the mCSA of AFS was compared between those with and without current symptoms.

RESULTS

No difference in the mCSA of AFS was observed between those with or without tendon symptoms (P < 0.05). Similar to previous findings, 80% to 92% of abnormal tendons had similar amounts of mCSA of AFS compared with normal tendon. If reduced mCSA of AFS was present, it was not associated with the presence or severity of symptoms.

CONCLUSIONS

The prevalence, development, or severity of symptoms was not associated with decreased levels of AFS in the Achilles or patellar tendon. This suggests that a lack of structural integrity is not linked to symptoms and questions the rationale behind regenerative medicine. Most tendons are able to compensate for areas of disorganization and maintain tissue homeostasis.

Effects of morphological changes in the patellar tendon on the development of anterior knee pain after intramedullary nailing for tibial shaft fractures: A retrospective comparative study

OBJECTIVE

This study aimed to investigate the effects of morphological changes of the patellar tendon (length, width, and thickness) on the development of anterior knee pain (AKP) after intramedullary nailing (IMN) of tibial shaft fractures.

METHODS

A total of 39 patients, treated by IMN using the transpatellar approach for tibial shaft fractures, were retrospectively reviewed and included in the study. The patients were then divided into 2 groups based on the presence of AKP: group A, patients who developed AKP (9 men, 9 women; mean age=35.39±9.32 years), and group B, patients without AKP (13 men, 8 women; mean age=41.38±14.78 years). To assess the morphological changes in the patellar tendon, magnetic resonance imaging was performed on the operated and unoperated, contralateral knees of the patients. The patellar tendon index (PTI) was calculated using the length, width, and thickness of the patellar tendon, and a set of variables was established to be a proportion of the measurements of the operated knees to those of the unoperated ones (operated/healthy PTI ratio). PTI ratios were compared between both the groups. Furthermore, the morphological features of the patellar tendon, including the length, width, and thickness, were examined within the groups as independent variables. To assess pain intensity in group A, a 10-cm visual analogue scale (VAS) was used. To evaluate functional status, the Lysholm knee scoring system was used.

RESULTS

The PTI ratio was significantly higher in group A (1.37±0.12) than in group B (1.03±0.08) (p<0.001). In group A, the mean VAS score was 5.35±1.11, and a moderate linear correlation was found between PTI ratios and VAS scores (r=0.494, p=0.044). The mean Lysholm score was significantly lower in group A (80.17±3.05) than in group B (89.76±3.05) (p<0.001). In group A, the width and thickness of the patellar tendon were found to be significantly different between the operated and unoperated knees (p=0.024 and p=0.002, respectively). In group B, there was no difference between the operated and unoperated knees in terms of the 3 measurements (length, width, and thickness) (p=0.762, p=0.753, and p=0.118, respectively).

CONCLUSION

Evidence from this study revealed that morphological changes occurring in the patellar tendon after IMN for tibial shaft fractures using a transpatellar approach may have a significant role in the development of AKP. The increase in the tendon width and thickness may be the cause of pain and insufficient knee function in such patients.

LEVEL OF EVIDENCE

Level III, Therapeutic study.

Radiographic evaluation of patellar tendon length following corrective surgical procedures for medial patellar luxation in dogs

Objective

To quantify changes in the patellar tendon length following surgical correction of medial patellar luxation in dogs and evaluate potential risk factors associated with patellar tendon elongation.

Study design

Retrospective case series (n = 50).

Methods

Dogs that underwent surgery for medial patellar luxation correction and had 2–3 months follow up were included. Digital radiographs were utilized to quantify the patellar tendon length to patellar length ratio at various follow-up points. Odds ratio comparisons between potential risk factors associated with changes in patellar tendon length were performed.

Results

Post-operative patellar tendon lengthening of ≥ 5% was observed in 20% of stifles and post-operative patellar tendon shortening of ≥ 5% was observed in 22% of stifles at the 2–3 month follow up period. The risk factors including age, body weight, trochleoplasty and grade of medial patellar luxation were not significantly associated with risk of patellar tendon elongation. Patellar tendon lengthening was not associated with recurrence of luxation.

Conclusion

Patellar tendon lengthening and shortening can be observed in dogs following common medial patellar luxation corrective procedures in the short term follow up period. Patellar tendon lengthening does not appear to be associated with age, weight, trochleoplasty, grade of luxation, or risk of luxation recurrence.

The effects of growth on structural properties of the Achilles and Patellar tendons: A cross-sectional study

The purpose of this study was to investigate the structural properties (length and cross-sectional area) of both the Patellar and Achilles tendons at around adolescent growth spurt. One hundred-twenty children and adolescents participated in this study. Based on estimated age at peak height velocity, the participants were separated into three groups (before takeoff of adolescent growth spurt group, from takeoff of adolescent growth spurt until peak height velocity group and after peak height velocity group). An ultrasonography technique was used to determine structural properties of the Patellar and Achilles tendons. Significant group difference was observed in tendon length for the Patellar and Achilles tendons among groups. However, there were no significant differences in the ratio of the Patellar tendon to upper leg length and the ratio of the Achilles tendon to lower leg length among groups. The cross-sectional area of all regions for the Patellar and Achilles tendons in adolescents with after takeoff adolescent growth spurt group was greater than those of before takeoff adolescent growth spurt group. These results indicate that the cross-sectional area of both the Patellar and Achilles tendons increase with takeoff of adolescent growth spurt and tendons lengthen without the changes in the ratio of tendon length to bone length. In addition, the increases in the cross-sectional area of both the Patellar and Achilles tendons occur in whole regions but not specific regions.

Intermachine Variation of Ultrasound Strain Elastographic Measures of the Quadriceps and Patellar Tendons in Healthy Participants: Implications for Clinical Practice

OBJECTIVES

To evaluate intermachine variation and compare intraoperator and interoperator agreement and repeatability characteristics of 2 ultrasound (US) systems for measurements of quadriceps and patellar tendons by strain elastography (SE).

METHODS

Forty tendons from 20 healthy participants were investigated by operators with different experience (operator 1, 12 years of US experience and >50 SE examinations; operator 2, no US experience and 1 day of SE training). Repeated measures were performed on GE Healthcare (Waukesha, WI) and Esaote (Genoa, Italy) US systems. The percentage of agreement, Cohen κ, intraclass correlation coefficient, and correlation tests assessed agreement, repeatability, and associations of SE measures. A paired t test and Wilcoxon signed rank test assessed differences in SE measures.

RESULTS

The study participants included 5 male and 15 female volunteers (mean [range] age, 29.3 [21-39] years). Better agreement and repeatability characteristics were observed for the patellar compared to the quadriceps tendon and the color score (CS) method over the elasticity ratio (ER). Intraoperator agreement was better for the experienced operator. Intraoperator repeatability was achieved in 55% of ER (intraclass correlation coefficient, 0.40-0.91; P < .05) and 77% to 85% (κ = -0.25-1) of CS measures. Interoperator repeatability was achieved in 35% (t/z, -2.93-7.94; P < .001-.048) of all ER measures. No significant differences in proximal (z, -0.13- -0.78) and distal patellar (z, -1.52-2.26; P > .5) patellar ER measures were observed. Seventy-four percent to 75% mean agreement (κ = 0-0.5) for CS measures comparable across both US systems was observed. Intermachine ER associations were poor (r = -0.39-0.13; P > .05), whereas greater than 70% agreement (κ = -0.87-0.53) for the CS was achieved.

CONCLUSIONS

The reproducibility of knee tendon SE measurements is influenced by the operator experience, US system, and tendon site.