Strength symmetry after autograft anterior cruciate ligament reconstruction.

OBJECTIVE: To compare postoperative isometric quadriceps strength indices (QI%) and hamstring strength limb symmetry indices (HI%) between partial thickness quadriceps tendon (pQT), full thickness quadriceps tendon (fQT), and bone-patellar-tendon bone (BPTB) autograft anterior cruciate ligament reconstruction (ACLR). METHODS: Patients with primary ACLR with pQT, fQT, or BPTB autograft with the documentation of quantitative postoperative strength assessments between 2016 and 2021 were included. Isometric Biodex data, including QI% and HI% (calculated as the percentage of involved to uninvolved limb strength) were collected between 5 and 8 months and between 9 and 15 months postoperatively. RESULTS: In total, 124 and 51 patients had 5-8- and 9-15-month follow-up strength data, respectively. No significant difference was detected between groups for sex. However, patients undergoing fQT were found to be older than those undergoing BPTB (24.6±7 vs 20.2±5; â€‹p = 0.01). There were no significant differences in the number of concomitant meniscus repairs between the groups (pQT vs. fQT vs. BPTB). No significant differences were detected in median (min-max) QI% between pQT, fQT, and BPTB 5-8 months [87 â€‹% (44%-130 â€‹%), 84 â€‹% (44%-110 â€‹%), 82 â€‹% (37%-110 â€‹%) or 9-15 months [89 â€‹% (50%-110 â€‹%), 89 â€‹% (67%-110 â€‹%), and 90 â€‹% (74%-140 â€‹%)] postoperatively. Similarly, no differences were detected in median HI% between the groups 5-8 months or 9-15 months postoperatively. CONCLUSION: The study was unable to detect differences in the recovery of quadriceps strength between patients undergoing ACLR with pQT, fQT, and BPTB autografts at 5-8 months and 9-15-months postoperatively. LEVEL OF EVIDENCE: III.

Near complete quadriceps tendon healing 2 years following harvest in anterior cruciate ligament reconstruction.

PURPOSE: Despite the recent increase in the use of quadriceps tendon (QT) autograft in anterior cruciate ligament reconstruction (ACLR); however, there remains a paucity of literature evaluating the postoperative morphology of the QT. The present study aimed to determine the postoperative morphologic change of the QT at a minimum of 2 years following harvesting during ACLR. METHODS: Patients who underwent ACLR with QT autograft and underwent magnetic resonance imaging (MRI) at a minimum of 2 years following harvesting were retrospectively included in the study. The anterior-to-posterior (A-P) thickness, medial-to-lateral (M-L) width, cross-sectional area (CSA), and signal/noise quotient (SNQ) of the QT were assessed at 5 mm, 15 mm, and 30 mm proximal to the superior pole of the patella on MRI. The CSA was adjusted by the angle between the QT and the plane of the axial cut based on a cosine function (adjusted CSA). The A-P thickness, M-L width, adjusted CSA, and SNQ were compared pre- and postoperatively. In addition, defects or scar tissue formation in the harvest site were investigated on postoperative MRI. RESULTS: Thirty patients were recruited for the study. The mean duration between postoperative MRI and surgery was 2.8 ± 1.1 years. The mean A-P thickness was 10.3% and 11.9% larger postoperatively at 5 mm and 15 mm, respectively. The mean M-L width was 7.3% and 6.5% smaller postoperatively at 5 mm and 15 mm, respectively. There were no significant differences in the adjusted CSA between pre- and post-operative states (275.7 ± 71.6 mm2 vs. 286.7 ± 91.8 mm2, n.s.). There was no significant difference in the postoperative change in the SNQ of the QT at all assessment locations. Defect or scar tissue formation at the harvest site was observed in 4 cases (13.3%), and 5 cases (16.6%), respectively. CONCLUSION: At a minimum of 2 years following QT harvest during ACLR, the QT became slightly thicker and narrower (approximately 11% and 7%, respectively). While the current study demonstrates that QT re-harvesting can be considered due to nearly normalized tendon morphology, future histological and biomechanical studies are required to determine the re-harvesting potential of the QT. LEVEL OF EVIDENCE: IV.

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 (MDC95% ) were calculated. RESULTS: Good to excellent between-day stability were found for viscosity (ICC = 0.905, MDC95%  = 8.3 Pa seconds) and shear modulus (ICC = 0.805, MDC95%  = 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.

Relationships between tendon structure and clinical impairments in patients with patellar tendinopathy.

The clinical relevance of altered tendon structure in patellar tendinopathy is contested since structural change persists after symptom resolution. The purpose of this study was to explore the relationships between tendon structure and clinical impairments in patellar tendinopathy. In this retrospective, secondary analysis of individuals with patellar tendinopathy (n = 41), tendon structure (thickness, cross-sectional area [CSA], shear modulus, and viscosity), symptom severity, lower extremity function (counter-movement jump [CMJ] height), and quadriceps muscle performance (knee extension force and central activation ratio [CAR]) were recorded for the symptomatic limb. Relationships among structure, symptom severity, lower extremity function, and quadriceps muscle performance were examined using sequential regression models. Adjusting for age, sex, body mass index, and pain levels, there were significant positive relationships for thickness (p < 0.001, ß = 0.718) and viscosity (p = 0.006, ß = 0.496) with CMJ height. There were significant negative relationships between CSA with both CMJ height (p = 0.001, ß = -0.538) and CAR (p = 0.04, ß = -0.517). This is the first study to demonstrate relationships between tendon structure and lower extremity function or quadriceps muscle performance in patients with patellar tendinopathy. Clinical significance: Since structural changes persist after symptom resolution, addressing these changes may assist in restoring lower extremity function and quadriceps muscle performance.

Pain-guided activity modification during treatment for patellar tendinopathy: a feasibility and pilot randomized clinical trial.

BACKGROUND: Activity modification is a key component of patellar tendinopathy treatment but there is a lack of evidence guiding activity modification prescription. Use of activity modification in treatment studies has varied widely and the impact of those recommendations has not been directly investigated or compared. The purpose of this study was to assess (1) the feasibility of using pain-guided activity modification during treatment for patellar tendinopathy and (2) if our outcome measures are responsive to changes in tendon health over the course of treatment. METHODS: This was an unblinded, randomized two-arm pilot and feasibility study randomized clinical trial with parallel assignment, conducted in Newark, DE. Individuals between the ages of 16 and 40 years old with patellar tendinopathy were included. Participants were randomly assigned to a pain-guided activity (PGA) or pain-free activity (PFA) group using a spreadsheet-based randomization scheme. All participants received standardized treatment using a modified version of the heavy-slow resistance protocol 3×/week for 12 weeks. For the first 6 weeks, the PGA group used the Pain-Monitoring Model to guide activity outside of treatment and the PFA group was restricted from running, jumping, or activities that provoked their patellar tendon pain. Feasibility outcomes included recruitment, enrollment, randomization, compliance, and retention percentages. Clinical evaluations were conducted at baseline, 6, and 12 weeks to assess symptom severity, psychological factors, tendon morphology and mechanical properties, lower extremity function, and quadriceps muscle performance. RESULTS: In a ~ 13-month period, 108 individuals were screened, 47/108 (43.5%) were eligible for participation, and 15/47 (32.0%) of those were enrolled (9 PGA, 6 PFA). The recruitment rate was 1.15 participants/month. The mean ± SD compliance with treatment was PGA: 86.1 ± 13.0% and PFA: 67.1 ± 30.7%. There was one missed evaluation session and two adverse events, which were not due to study interventions. Changes exceeding the smallest detectable change were observed for at least one outcome in each domain of tendon health. CONCLUSIONS: Use of pain-guided activity modification during exercise therapy for patellar tendinopathy was found to be feasible, and the proposed outcome measures appropriate. Computer-based allocation concealment, blinding of evaluators, and greater recruitment of high-level athletes should be implemented in future trials. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03694730 . Registered 3rd of October, 2018.

Relationship between mechanical properties (shear modulus and viscosity), age, and sex in uninjured Achilles tendons.

Tendon mechanical properties have been proposed as a biomarker of tendon health to track response to injury and treatment. Prior to utilizing these properties in an injured population, it is critical to understand how these are influenced by age and sex in an uninjured population. A retrospective analysis was conducted of 118 uninjured Achilles tendons to evaluate the relationship between tendon mechanical properties, age and sex. Mechanical properties (shear modulus and viscosity) were assessed using continuous shear wave elastography. A moderator regression analysis was completed to examine the relationship between tendon mechanical properties, age and sex, after adjusting for body mass index and physical activity level. There was an interaction between age and sex for shear modulus (p=0.049, R2 change=0.034). Females had a negative relationship between age and shear modulus (p=0.030, ß=-0.350) but no relationship was observed for males (p=0.78, ß=0.031). A positive relationship was found between age and viscosity (p=0.034, ß=0.214). Increased viscosity was related to increased age with no difference between sexes. The effect of aging on shear modulus differed between men and women and may help explain sex specific injury risks and their differing response to mechanical load.

Modifiable risk factors for patellar tendinopathy in athletes: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis identifying (1) potential modifiable risk factors and (2) associated modifiable factors for patellar tendinopathy in athletes. DESIGN: A systematic review and meta-analysis was conducted. Risk of bias was assessed using the Newcastle-Ottawa Scale and grouped based on study design. Meta-analytic statistics were performed for items reported by five or more studies. A strength of evidence rating is provided for items not appropriate for meta-analysis. DATA SOURCES: PubMed, Web of Science, Scopus and Cinahl were searched on 14 November 2017. ELIGIBILITY CRITERIA: Quantitative, original research reporting potential modifiable risk factors or associated factors, comparing athletes with patellar tendinopathy with a group without the injury. RESULTS: 862 records were screened and 31 articles were included (6 prospective, 25 cross-sectional). There was a lack of strong evidence for any potential modifiable risk factor or associated factors. There was limited or conflicting evidence that decreased ankle dorsiflexion range of motion, decreased posterior thigh and quadriceps flexibility, greater volume of jump training, more volleyball sets played per week, greater countermovement jump (CMJ) height and greater activity volume are potential modifiable risk factors. Meta-analysis supported greater activity volume (Cohen's d=0.22, 95% CI 0.06 to 0.39, p=0.008), higher body weight (0.36, 0.17 to 0.55, p<0.001) and greater CMJ height (0.31, 0.07 to 0.56, p=0.01) as associated modifiable factors. CONCLUSIONS: There is a lack of strong evidence for any potential modifiable risk factors or associated factors. Factors with lower levels of support may be of interest in designing prevention programmes but require further research in high-quality, prospective studies.