Achilles Tendon Resting Angle Relates to Tendon Length and Function

Early Predictors of Recovery From Nonoperatively Treated Achilles Tendon Rupture: 1 Year Follow-Up Study

PURPOSE

To investigate early structural and mechanical predictors of plantarflexor muscle strength and the magnitude of Achilles tendon (AT) nonuniform displacement at 6 and 12 months after AT rupture.

METHODS

Thirty-five participants (28 males and 7 females; mean ± SD age 41.7 ± 11.1 years) were assessed for isometric plantarflexion maximal voluntary contraction (MVC) and AT nonuniformity at 6 and 12 months after rupture. Structural and mechanical AT and plantarflexor muscle properties were measured at 2 months. Limb asymmetry index (LSI) was calculated for all variables. Multiple linear regression was used with the 6 and 12 month MVC LSI and 12 month AT nonuniformity LSI as dependent variables and AT and plantarflexor muscle properties at 2 months as independent variables. The level of pre- and post-injury sports participation was inquired using Tegner score at 2 and 12 months (scale 0-10, 10 = best possible score). Subjective perception of recovery was assessed with Achilles tendon total rupture score (ATRS) at 12 months (scale 0-100, 100=best possible score).

RESULTS

Achilles tendon resting angle (ATRA) symmetry at 2 months predicted MVC symmetry at 6 and 12 months after rupture (β = 2.530, 95% CI 1.041-4.018, adjusted R2 = 0.416, p = 0.002; β = 1.659, 95% CI 0.330-2.988, adjusted R2 = 0.418, p = 0.016, respectively). At 12 months, participants had recovered their pre-injury level of sports participation (Tegner 6 ± 2 points). The median (IQR) ATRS score was 92 (7) points at 12 months.

CONCLUSION

Greater asymmetry of ATRA in the early recovery phase may be a predictor of plantarflexor muscle strength deficits up to 1 year after rupture.

TRIAL REGISTRATION

This research is a part of "nonoperative treatment of Achilles tendon rupture in Central Finland: a prospective cohort study" that has been registered in ClinicalTrials.gov (NCT03704532).

Regional healing trajectory of the patellar tendon after bone-patellar tendon-bone autograft harvest for anterior cruciate ligament reconstruction

Graft site morbidities after bone-patellar tendon-bone (BPTB) autograft harvest for anterior cruciate ligament reconstruction (ACLR) negatively impacts rehabilitation. The purpose of this study was to establish tendon structural properties 1-month after BPTB autograft harvest compared to the uninvolved patellar tendon, and subsequently to quantify the healing trajectory of the patellar tendon over the course of rehabilitation. Patellar tendon morphology (ultrasound) and mechanical properties (continuous shear wave elastography) from 3 regions of the tendon (medial, lateral, central) were measured in 34 participants at 1 month, 3-4 months, and 6-9 months after ACLR. Mixed models were used to compare tendon structure between limbs at 1 month, and quantify healing over 3 timepoints. The involved patellar tendon had increased cross-sectional area and thickness in all regions 1-month after ACLR. Thickness reduced uniformly over time. Possible tendon elongation was observed and remained stable over time. Tendon viscosity was uniform across the three regions in the involved limb while the medial region had higher viscosity in the uninvolved limb, and shear modulus was elevated in all three regions at 1 month. Viscosity and shear modulus in only the central region reduced over time. Statement of Clinical Significance: The entire patellar tendon, and not just the central third, is altered after graft harvest. Tendon structure starts to normalize over time, but alterations remain especially in the central third at the time athletes are returning to sport. Early rehabilitation consisting of tendon loading protocols may be necessary to optimize biologic healing at the graft site tendon.

Minimal effect of scanning parameters on ultrasound shear wave elastography variability in tendons

PURPOSE

Ultrasound shear wave elastography has potential use in assessing tendon tissue; however, reducing measurement variability remains challenging. The primary purpose of this study was to identify the amount of variability accounted for by ultrasound parameter (frequency, harmonics and CrossXBeam) settings on shear wave speed at two testing sites.

METHODS

Shear wave elastography images of the Achilles tendon were obtained from individuals with healthy tendons (n = 28) at two testing sites with standardised image acquisition/postprocessing protocols. Images were acquired at a range of frequencies (7-15 MHz) with CrossXBeam (a filtering technique) and harmonics settings toggled on and off. Variance decomposition analysis was performed to identify the amount of variability in shear wave speed accounted for by scan acquisition settings and testing sites.

RESULTS

Shear wave speed variance was primarily attributed to participants (56.87% of variance; residual error: 35%). All scanning parameters, testing site and interaction terms each accounted for less than 2.5% of the variance. A statistically significant, negative relationship was observed between shear wave speed and image quality (p = 0.001) suggesting poor image quality yields higher shear wave speed estimates.

CONCLUSION

The findings of this study suggest that natural variation in Achilles tendon mechanics between individuals without tendon pathology accounts for most of the shear wave speed variability. Optimising image quality, which may be observed in higher frequencies, should be considered to improve shear wave speed estimation. Clinically, this study highlights the need to take multiple images, maintain consistent ultrasound settings when tracking patient progress over time and use caution when comparing raw values from tendon scans performed in different clinics with shear wave elastography.

LEVEL OF EVIDENCE

Level III.

Feasibility of an early progressive resistance exercise program for acute Achilles tendon rupture

BACKGROUND

Long-term strength deficits are common after Achilles tendon ruptures. Early use of progressive resistance exercises may help reduce strength deficits, but the feasibility of this approach is unknown. The aim was to investigate the feasibility of early progressive resistance exercises regarding patient acceptability and compliance with the intervention.

METHODS

We recruited patients with an acute Achilles tendon rupture treated non-surgically. During 9 weeks of immobilisation with a walking boot, participants attended weekly supervised physiotherapy sessions of progressive resistance exercises and performed home exercises, consisting of isometric ankle plantarflexion, seated heel-rise, and elastic band exercises. Acceptability was evaluated using a 7-point Likert scale (1 = very unacceptable and 7 = very acceptable) with feasibility threshold at 80% of the participants rating ≥ 4. Adherence to the exercises was defined as 80% of the participants performing at least 50% of the home exercises. During the intervention, tendon healing and adverse events were monitored.

RESULTS

Sixteen participants (mean age 46 (range 28-61), male/female = 13/3) completed the intervention. Pre-injury Achilles tendon total rupture score was 98 (SD 8). All participants rated the acceptability of the exercises ≥ 5 (moderate acceptable to very acceptable) at 9- and 13-week follow-up and 9/16 rated 7 points (very acceptable). Participants performed 74% (range 4-117) of the total prescribed home exercises and 15/16 performed > 50%. One participant was not compliant with the home exercises due to feeling uncomfortable performing these independently. There were no re-ruptures, but one case of deep venous thrombosis.

CONCLUSIONS

The early progressive resistance exercise program for treatment of non-surgically treated Achilles tendon rupture was feasible. Future studies should investigate the efficacy of the progressive intervention.

TRIAL REGISTRATION

The study was registered at Clinical Trials (NCT04121377) on 29 September 2019.

CLINICALTRIALS

NCT04121377 .

Differential elongation of the gastrocnemius after Achilles tendon rupture: a novel technique of selective shortening to treat push-off weakness with case series and literature review

PURPOSE

Differential elongation of the gastrocnemius after Achilles tendon rupture (ATR) may compromise the ability of athletes to return to competition. Recognition of this differential elongation of the gastrocnemius relative to the soleus is vital to treat patients with weakness in push-off. This paper describes a novel technique performed for selective shortening of the gastrocnemius to treat push-off weakness.

METHODS

Three patients with differential proximal retraction of the gastrocnemius greater than 20 mm after treatment for ATR with inability to run and jump underwent surgical correction with this novel technique and were followed-up for 2 years. A novel selective shortening of the gastrocnemius with autologous hamstring graft was performed in these patients. The Achilles Tendon Total Rupture Score (ATRS) and American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score were recorded preoperatively and at the final follow-up.

RESULTS

All three patients were able to return to running and jumping at final follow-up. The ATRS improved significantly in the strength, fatigue, running and jumping domains but there appeared to be a less notable improvement in activities of daily living domain. The AOFAS score showed improvement with the greatest margin in the domain of activity limitation.

CONCLUSION

This procedure is the first described selective shortening method of the gastrocnemius tendons after differential elongation following ATR. It is a safe and reliable technique providing improved ATRS and AOFAS scores in three patients who were all able to return to running and jumping sports at 2-year follow-up.

LEVEL OF EVIDENCE

IV.

Correlation between the Coaptation and Regeneration of Tendon Stumps in Endoscopic Assisted Achilles Tendon Rupture Repair

OBJECTIVE

When the endoscopic Achilles tendon repair technique is utilized, direct stitching of the ruptured site is challenging due to the frayed tendon stumps. To explore whether undesirable coaptation of the tendon stumps influences the generation of the tendons.

METHODS

This study is a retrospective analysis of 46 patients who underwent a modified endoscopic Achilles tendon rupture repair from October 2018 to June 2020. Patients were divided into two groups according to the coaptation of tendon stumps on postoperative ultrasonography. Group 1 included 17 cases with undesirable coaptation (<50%), and Group 2 included 29 cases with appropriate coaptation (≥50%). Magnetic resonance imaging (MRI) was obtained postoperatively at 3, 6, and 12 months to evaluate the tendon morphological construction. Clinical evaluations were performed using the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hind foot score, the Achilles Tendon Total Rupture Score (ATRS), muscle power, and the Achilles tendon resting angle at the final follow-up. Complications were also encountered. The Student's t-test and the Mann-Whitney U-test were used to assess differences among both groups.

RESULTS

The mean follow-up time was 37.5 ± 10.6 months in Group 1 and 39.0 ± 11.6 months in Group 2, respectively. The average age in Group 1 is slightly older than in Group 2 (37.3 ± 6.1 vs. 32.7 ± 6.3, p = 0.021). The tendon cross-section areas and thickness increased initially and decreased later on postoperative MRI evaluation. It also showed a significantly higher signal/noise quotient (SNQ) in Group 1 at postoperative 3 months. At postoperative 6 and 12 months, the SNQ between both groups was similar. The AOFAS score (95.9 ± 5.1 vs. 96.2 ± 4.9, p = 0.832), ATRS score (97.0 ± 3.6 vs. 97.7 ± 3.3, p = 0.527), and muscle power (21.38 vs. 24.74, p = 0.287) were not significantly different between both groups. However, the resting angle of Group 1 was significantly larger than that of Group 2 (4.6 ± 2.4 vs. 2.4 ± 2.3, p = 0.004). There was no difference in the complications (p = 0.628).

CONCLUSION

Although complete regeneration can be finally achieved, the early stage of tendon stump regeneration can be prolonged due to undesirable coaptation when endoscopic Achilles tendon repair technique is applied. The prolonged high signal duration on MRI indicates the less-than-ideal regeneration of the tendon, which might lead to elongation of the tendon.

Devices to measure calf raise test outcomes: A narrative review

BACKGROUND

The calf raise test (CRT) is commonly administered without a device in clinics to measure triceps surae muscle function. To standardise and objectively quantify outcomes, researchers use research-grade or customised CRT devices. To incorporate evidence-based practice and apply testing devices effectively in clinics, it is essential to understand their design, applicability, psychometric properties, strengths, and limitations. Therefore, this review identifies, summarises, and critically appraises the CRT devices used in science.

METHODS

Four electronic databases were searched in April 2022. Studies that used devices to measure unilateral CRT outcomes (i.e., number of repetitions, work, height) were included.

RESULTS

Thirty-five studies met inclusion, from which seven CRT devices were identified. Linear encoder (n = 18) was the most commonly used device, followed by laboratory equipment (n = 6) (three-dimensional motion capture and force plate). These measured the three CRT outcomes. Other devices used were electrogoniometer, Häggmark and Liedberg light beam device, Ankle Measure for Endurance and Strength (AMES), Haberometer, and custom-made. Devices were mostly used in healthy populations or Achilles tendon pathologies. AMES, Haberometer, and custom-made devices were the most clinician-friendly, but only quantified repetitions were completed. In late 2022, a computer vision mobile application appeared in the literature and offered clinicians a low-cost, research-grade alternative.

CONCLUSION

This review details seven devices used to measure CRT outcomes. The linear encoder is the most common in research and quantifies all three CRT outcomes. Recent advances in computer-vision provide a low-cost research-grade alternative to clinicians and researchers via a n iOS mobile application.

Achilles tendon gait dynamics after rupture: A three-armed randomized controlled trial comparing an individualized treatment algorithm vs. operative or non-operative treatment

BACKGROUND

Individual treatment selection has been proposed as the key to optimized treatment. The purpose was to investigate if treatment selection using the individualized treatment algorithm Copenhagen Achilles Rupture Treatment Algorithm (CARTA) differs between patients treated as usual regarding gait dynamics and tendon elongation.

METHODS

The patients were randomized to one of three parallel groups: 1) intervention group: participants treated according to CARTA, 2) control group: participants treated non-operatively, 3) control group: participants treated operatively. The primary outcome was ankle peak power during push off during walking at 12 months.

RESULTS

156 patients were assessed for eligibility. 21 were allocated to the intervention group, and 20 and 19 to the control groups. The results indicated no statistically significant differences between the intervention group and the control groups.

CONCLUSIONS

Individualized treatment selection based on CARTA did not demonstrate less affected gait dynamics or less tendon elongation than patients treated as usual.

Morphometric Analysis of Achilles Tendon Structure and Its Significance: A Cadaveric Study

INTRODUCTION

Achilles tendon is crucial for gait, and chronic Achilles tendinopathy can have a substantial impact on an individual's work and active involvement in physical or sports activity, and overall quality of life.

OBJECTIVES

This research was to determine the macroscopic and microscopic anatomy of Achilles tendons in cadavers.

MATERIALS AND METHODS

This experimental study was conducted in the Department of Anatomy, Saveetha Medical College, Thandalam, from March to August 2022. A total of 60 formalin-perfused cadavers (38 males and 22 females) were dissected to study their morphometry (length, width, thickness) and histology. The data was tabulated in MS excel and analyzed statistically using unpaired 't-test and one-way ANOVA in SPSS Software 17.0 (IBM Corp., Armonk, NY).

RESULTS

The mean length of the Achilles tendon was significantly higher in males than in females and similarly, the length on the right side was significantly higher than on the left side (p<0.005). The width and circumference were statistically higher in females than, males whereas, the histological features were similar in both males and females.

CONCLUSION

The better understanding of Achilles tendon morphometry in cadavers always aids in the diagnosis and surgical repair of tendinopathy, rupture, and degenerative change. The knowledge will be helpful for the surgeons during the repair and reconstruction of the injured tendon.

Does Mobility of the Ankle Joint Depends on Length of the Free Part of the Achilles Tendon?

The aim of our study was to evaluate whether the length of the free part of the Achilles tendon affects the mobility of the ankle joint in active motion without a load, as well as in functional motion with a body-weight load. We examined 36 healthy people, aged 21 to 30 years, and divided them into two groups: 1 (n = 15)—participants with a normal range of dorsiflexion in the ankle joint (20° or more), and 2 (n = 21)—participants with a reduced range of dorsiflexion in the ankle joint (below 20°). The length of the free part of the Achilles tendon was measured using ultrasonography. Ankle joint range of dorsiflexion was assessed, and a weight-bearing lunge test (WBLT) was conducted. Group 1 performed the WBLT better and demonstrated significantly greater Achilles tendon length compared to Group 2. A moderate, significant correlation was observed between ankle joint range of dorsiflexion and Achilles tendon length (r = 0.53, p < 0.05); between WBLT and Achilles tendon length (r = 0.61, p < 0.05); as well as between ankle joint range of dorsiflexion and WBLT (r = 0.63, p < 0.05). Thus, we can suggest that both the length of the tendon (measured by USG) and the ankle range of motion under a body-weight load (measured by WBLT) are good indicators regarding the range of foot dorsiflexion, but only up to specific values (6 cm of tendon length and 11 cm of WBLT reach). Therefore, Achilles tendon length, e.g., after injury and during tendon healing, may be monitored using the method of ultrasound imaging presented in this study.

1.7 cm elongated Achilles tendon did not alter walking gait kinematics 4.5 years after non-surgical treatment

PURPOSE

The aim of the present study was to evaluate Achilles tendon length after non-surgical treatment of acute Achilles tendon rupture (aATR), and to evaluate indirect effects of possible persistent elongation on kinematics.

METHODS

The study was performed as a cross-sectional study based on a population of patients from an RCT regarding non-operative treatment of aATR. Thirty-seven patients out of the 56 in the original RCT participated with at a follow up of 4-5 years after aATR. Primary outcome was Achilles tendon elongation. Additional outcomes were Achilles tendon resting angle (ATRA), calf circumference, passive ankle plantar and dorsiflexion and loading pattern. Foot pressure mapping was performed to measure plantar loading distribution pattern; medial and lateral forefoot peak pressure, heel peak pressure, medial versus lateral loading pattern and timing of heel lift during roll over process. The healthy leg was used as a control.

RESULTS

The injured Achilles tendon was significantly elongated by 1.7 (SD 1.6) cm compared to the non-injured leg. A slight delay of 2.6% (SD 6.0) was measured in heel lift in the injured side compared to the non-injured leg. We found no significant difference in forefoot peak pressure, medial and lateral peak pressure as well as heel peak pressure, and no correlation was found between Achilles tendon length and pressure measurements. Finally, dorsiflexion was 1.9°(SD1.28) larger, ATRA 8.1°(SD6.7) larger, and calf circumference 1.6 cm (SD1.1) lower on the injured leg.

CONCLUSION

The Achilles tendon was 1.7 cm elongated 4.5 years after the initial injury and significant changes in ATRA, calf circumference and passive dorsiflexion was present. Except for a slight delay in heel lift-off, kinematics during walking was symmetrical between injured and healthy leg, even with an elongated tendon on the injured leg. The clinical relevance of the Achilles tendon elongation is uncertain.

LEVEL OF EVIDENCE

II.

CLINICAL TRIALS IDENTIFIER

NCT02760784.

Outcomes of Percutaneous Achilles Repair Compared With Endoscopic Flexor Hallucis Longus Tendon Transfer to Treat Achilles Tendon Ruptures

BACKGROUND

Both percutaneous and endoscopically assisted methods are reported to produce good results in the surgical management of acute Achilles tendon ruptures. The aim of this retrospective study was to compare between a percutaneous method and a recently described isolated endoscopically assisted flexor hallucis longus (FHL) transfer method as surgical means of management in patients with acute Achilles tendon ruptures.

METHODS

One hundred seventeen patients were included in the current study and divided into 2 groups: 59 patients who underwent percutaneous Achilles repair (PAR Group) and 58 patients who underwent isolated endoscopic FHL transfer (FHL Group) were compared. Patients were clinically evaluated using American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Achilles tendon Total Rupture Score (ATRS), and Achilles tendon resting angle (ATRA) measures. In addition, ankle plantarflexion power, FHL dynamometry, Tegner activity levels, and return to previous levels of activity were also documented for all patients.

RESULTS

Nine months after surgery, patients in the FHL transfer group were more likely to be able to return to normal activities (91% vs 73%, P < .01). Thirty months after surgical treatment, we found no difference in ATRS, AOFAS, ATRA, ankle plantarflexion strength, or Tegner activity scores between study groups. Overall complications were reported in 6 patients in the FHL group (10.3%) and in 8 patients in the PAR group (13.6%). No major neurovascular or skin complications were encountered.

CONCLUSION

The current study demonstrated satisfactory and comparable results and complications when comparing isolated endoscopic FHL tendon transfer or percutaneous Achilles tendon repairs in the surgical management of acute Achilles tendon ruptures.

LEVEL OF EVIDENCE

Level III, retrospective controlled trial.

Data driven model of midportion achilles tendinopathy health created with factor analysis

Background

Achilles tendinopathy is a complex injury and the clinical presentation spans multiple different domains: physical and psychological symptoms, lower extremity function and tendon structure. A conceptual model of Achilles tendon health comprising these domains has been proposed in the literature. The aim of the study was to fit a model of Achilles tendinopathy using factor analysis and compare that to the conceptual model. An inclusive approach using a wide range of variables spanning multiple potential domains were included.

Methods

Participants (N = 99) with midportion Achilles tendinopathy were assessed with variables representing symptoms, physical function, tendon structure, metabolic syndrome, and psychologic symptoms. A Kaiser-Mayer-Olkin index was used to determine suitable variables for a subsequent exploratory factor analysis.

Results

A model emerged with an acceptable fit to the data (standardized root mean square of residuals = 0.078). Five uncorrelated factors emerged from the model and were labelled as biopsychosocial, lower extremity function, body size, load tolerance, and tendon structure. The total explained variance was 0.51 with the five factors explaining 0.14, 0.12, 0.10, 0.08, and 0.07 respectively. The results differed from the conceptual model as the factors of psychological variables and metabolic variables did not emerge from the analysis.

Conclusion

A data driven model of Achilles tendon health supports assessment of the clinical presentation over multiple domains. As the factors are uncorrelated, the results of assessment of, for example, tendon structure should not be expected to be associated with lower extremity function or biopsychosocial limitations. The results suggest that the Patient Reported Outcomes Measurement Information System, counter-movement jump height, body mass index, pain with hopping, and the tendon cross-sectional area can evaluate the five factors, respectively.

Trial registration

Registered on clinicaltrials.gov (Medicine NL of. ClinicalTrials.gov [Internet], 2018), ID number NCT03523325.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05702-1.

Neither heel-rise Height (HRH) nor Achilles tendon resting angle (ATRA) show strong correlations to patient limitations and return to previous activities one year after acute Achilles tendon rupture

BACKGROUND

Knowledge is limited about how Achilles tendon elongation following acute Achilles tendon rupture (ATR) affects the ability to return to work and return to sport. This study aimed to examine if the indirect length measures, the heel-rise height (HRH) and the Achilles tendon resting angle (ATRA), correlated with patient limitations and return to previous activities one year after ATR.

METHODS

The study was performed as a registry study in the Danish Achilles tendon Database (DADB). The analyses investigated if HRH (limb symmetry index (LSI)) and relative ATRA one year after rupture, correlated with return to the same type of work, return to the same type of sport and the Achilles tendon total rupture score (ATRS) at the same time point.

RESULTS

477 patients were included in the study. HRH (LSI) showed fair correlation to ATRS (r = 0.35, p < 0.001), poor correlation to same type of work (r = 0.29, p < 0.001) and did not statistically significantly correlate with return to the same type of sport. Relative ATRA showed poor correlation to ATRS (r = 0.09, p = 0.04) and did not correlate statistically significantly with return to same type of work or sport.

CONCLUSIONS

Neither relative ATRA nor HRH (LSI) showed strong correlations to return to work, return sport or ATRS. When comparing the relative ATRA and HRH (LSI), HRH (LSI) seems to be a better outcome in reflecting patient limitations and return to previous activities one year after ATR.

No effects of early functional mobilization on gait patterns after acute Achilles tendon rupture repair

This study aimed to compare recovery of gait patterns in patients treated with early functional mobilization (EFM) or standard treatment (ST) after Achilles tendon rupture repair. Second, this study aimed to explore associations between gait patterns and tendon elongation and calf muscle atrophy, respectively. Forty-seven patients (12 females), mean age 38.7 (7.3) years, were included. Patients were postoperatively randomized to EFM (n = 29), including immediate weightbearing and ankle motion for 6 weeks, or ST (n = 18), with 2 weeks of unloading in a plaster cast followed by 4 weeks of weightbearing in an orthosis. Three-dimensional gait analyses were performed at 8 weeks and 6 months postoperatively to evaluate ankle and knee kinematics and kinetics. Ultrasound imaging was performed to assess tendon length and calf muscle atrophy. At 8 weeks, there were no significant group differences in ankle and knee kinematics and kinetics, while side-to-side differences between injured and uninjured side were present within both groups. At 6 months, the ST group exhibited higher generating ankle power and greater peak moments in ankle and knee compared to the EFM group. In both groups, peak ankle dorsiflexion angle was greater on the injured side compared to the uninjured side. No correlations were found between ankle joint gait deviations and degree of tendon elongation or muscle atrophy. Clinical significance: The accelerated rehabilitation regimen with EFM did not result in a more symmetrical gait pattern. The gait pattern deviations in the ankle joint were not related to the degree of muscle atrophy or tendon elongation.

Patients with chronic Achilles tendon rupture have persistent limitations in patient-reported function and calf muscle function one year after surgical treatment - a case series

Purpose

Evaluate the one-year postoperative outcomes in patients with Chronic Achilles tendon rupture.

Methods

Patients surgically treated for Chronic Achilles tendon rupture (n = 22, 14 males and 8 females, mean age 61 ± 15) were evaluated by Achilles tendon Total Rupture Score, The Physical Activity Scale, The Foot and Ankle Outcome Score, Calf muscle endurance test, counter movement jump, Hopping, ultrasound measurement of tendon length, Achilles Tendon Resting Angle, dorsi flexion range of motion and calf muscle circumference. Muscle function and tendon length outcomes on the injured side were compared with the healthy side.

Results

The patients scored a mean of 62 ± 26 on the Achilles tendon Total Rupture Score. Median scores on the injured compared with the healthy side were lower in heel-rise repetitions (20 vs 24 cm, p = 0.004), hel-rise height (8 vs 10 cm, p < 0.001), heel-rise total work (872 vs 1590 joule, p < 0.001) and hopping ratio (0.37 vs 0.48, p = 0.005). Median calf circumference was smaller (37 vs 38 cm, p = 0.001) and the mean tendon elongation greater on the injured side; Achilles tendon resting angle (55 vs 50°, p < 0.001) and ultrasound (22.4 vs 20.5 cm, p = 0.006).

Conclusions

At one year postoperatively, patients with chronic Achilles tendon rupture reported persistent limitations in subjective foot and ankle function. Heel-rise height and total work as well as hopping ratio were not recovered, and there was an elongation of the injured Achilles tendon compared with the healthy tendon.

Level of evidence

IV

Slowed-Down Rehabilitation Following Percutaneous Repair of Achilles Tendon Rupture

BACKGROUND

Following percutaneous repair of acute Achilles tendon (AT) ruptures, early postoperative weightbearing is advocated; however, it is debatable how aggressive rehabilitation should be. We compared the clinical and functional outcomes in 2 groups of patients who followed either our "traditional" or a "slowed down" rehabilitation after percutaneous surgical repair.

METHODS

Sixty patients were prospectively recruited to a slowed down (29 patients) or a traditional (31 patients) rehabilitation program. Both groups were allowed immediate weightbearing postoperatively; a removable brace with 5 heel wedges was applied at 2 weeks. In the slowed-down group, 1 wedge was removed after 4 weeks. Gradual removal of the boot took place after 4 wedges were kept for 4 weeks. In the traditional group, 1 wedge was removed every 2 weeks, with removal of the boot after 2 wedges had been kept for 2 weeks. The AT Resting Angle (ATRA) evaluated tendon elongation. Patient reported functional outcomes were assessed using the AT Rupture Score (ATRS). Calf circumference difference and the isometric plantarflexion strength of the gastro-soleus complex were evaluated.

RESULTS

At the 12-month follow-up, both ATRA and ATRS were more favorable in the slowed-down group. The isometric strength and the calf circumference were more similar to the contralateral leg in the slowed-down group than in the traditional one.

CONCLUSION

Following percutaneous repair of acute Achilles tendon patients undergoing slowed down rehabilitation performed better than the traditional one. These conclusions must be considered within the limitations of the present study.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Endoscopic Flexor Hallucis Longus Transfer for the Management of Acute Achilles Tendon Ruptures in Professional Soccer Players

BACKGROUND

Acute Achilles tendon ruptures (AATRs) that occur in athletes can be a career-ending injury. The aim of this study was to describe return to play and clinical outcomes of isolated endoscopic flexor hallucis longus (FHL) transfer in active soccer players with AATR.

METHODS

Twenty-seven active male soccer players who underwent endoscopically assisted FHL tendon transfer for acute Achilles tendon ruptures were included in this study. Follow up was 46.2 (±10.9) months after surgery. Return to play criteria and clinical outcome measures were evaluated.

RESULTS

All players returned to playing professional competitive soccer games. Return to active team training was at a mean of 5.8 (±1.1) months postoperatively. However, return to active competitive match play occurred at a mean of 8.3 (±1.4) months. Twenty-two players (82%) were able to return to their preinjury levels and performances and resumed their professional careers at the same soccer club as their preinjury state. One player (3.7%) shifted his career to professional indoor soccer. At 26 months postoperatively, the mean Tegner activity scale score was 9.7 (±0.4), the mean Achilles tendon total rupture score was 99 (±2), and the mean American Orthopaedic Foot & Ankle Society ankle-hindfoot score was 99 (±3). No patients reported any great toe complaints or symptomatic deficits of flexion strength.

CONCLUSION

The current study demonstrated satisfactory and comparable return to play criteria and clinical results with minimal complications when using an advanced endoscopically assisted technique involving FHL tendon transfer to treat acute Achilles tendon ruptures in this specific subset of patient cohort.

LEVEL OF EVIDENCE

Level II, prospective cohort case series study.

Greater heel-rise endurance is related to better gait biomechanics in patients surgically treated for chronic Achilles tendon rupture

PURPOSE

To determine the relationships among calf muscle function, tendon length and gait biomechanics in patients surgically treated for chronic Achilles tendon rupture.

METHODS

Twenty-one patients with chronic Achilles tendon rupture (mean age 62 ± 13 years) were evaluated by heel-rise endurance test, Achilles Tendon Resting Angle (ATRA), ultrasound measurement of tendon length and three-dimensional gait analysis. A bivariate two-sided correlation test was performed on all variables in all patients.

RESULTS

Better performance across all parameters of the heel-rise endurance test correlated with faster walking speed (r = 0.52-0.55), greater peak ankle power (r = 0.56-0.64), shorter stance phase (r = -0.52 to -0.76) and less peak ankle dorsiflexion angle (r = -0.49 to -0.64) during gait. Greater ATRA correlated with longer stance time (r = 0.47), greater peak ankle dorsiflexion angle (r = 0.48), less heel-rise repetitions (r = -0.52) and less heel-rise total work LSI (r = -0.44 to -0.59).

CONCLUSION

Greater calf muscle endurance, especially heel-rise total work, is moderately correlated (r = 0.49-0.76) to better ankle biomechanics during gait in patients surgically treated for CATR. The heel-rise endurance test may be a clinical proxy for power development in the ankle joint during gait.

LEVEL OF EVIDENCE

IV.

Achilles tendon resting angle is able to detect deficits after an Achilles tendon rupture, but it is not a surrogate for direct measurements of tendon elongation, function or symptoms

PURPOSE

The aim of this study was to investigate how the Achilles tendon resting angle (ATRA), an indirect measurement of tendon elongation, correlates with ultrasonography (US) measurements of the Achilles tendon length 6 and 12 months after an acute ATR and relates to other clinical outcome measurements such as heel-rise height, jumping ability and patient-reported outcome measurements (PROMs).

METHODS

Patients were included following acute Achilles tendon rupture (ATR). Achilles tendon length, ATRA, heel-rise height (HRH), drop countermovement jump (Drop CMJ) and PROMs (Achilles tendon total rupture score (ATRS) and physical activity scale (PAS)) were evaluated 6 and 12 months after injury. Achilles tendon length was evaluated using US, while the ATRA was measured with a goniometer.

RESULTS

Sixty patients (13 women, 47 men), mean (SD) age 43 (9) years, with an acute ATR undergoing either surgical (35%) or non-surgical (65%) treatment were evaluated. A negative correlation (r = - 0.356, p = 0.010) between relative ATRA and tendon elongation was seen at 12 months after ATR. There were also significant positive correlations at 6 and 12 months between relative ATRA and HRH (r = 0.330, p = 0.011 and r = 0.379, p = 0.004). There were no correlations between ATRA and ATRS or ATRA and Drop CMJ, at either 6 or 12 months after the injury.

CONCLUSION

In combination with other clinical evaluations such as HRH and US, ATRA could be a clinical tool for indirect measurements of tendon elongation. However, ATRA cannot be recommended as a direct surrogate for US for determining Achilles tendon length.

LEVEL OF EVIDENCE

III.

The reliability, reproducibility and utilization of the radiographic Achilles Tendon Loading Angle in the management of Achilles Tendon rupture

BACKGROUND

During management of Achilles tendon rupture, determination of tendon-end approximation, either clinically or by ultrasound is difficult, following brace application of during loading. The Radiographic Achilles Tendon Loading Angle (RadATLA) is proposed as a method of measuring ankle position whilst loading in a brace during the management of Achilles tendon rupture. This study aims to determine the reliability and reproducibility of the RadATLA.

METHODS

A loaded true lateral ankle radiograph including the fifth metatarsal head was taken when wearing a brace at the 6-week time point in 18 patients (19 ankles). following Achilles tendon repair or reconstruction. The RadATLA was compared with the Tibio-talar angle, other radiographic and clinical measures used to quantify foot and ankle position during the first 6 weeks of early rehabilitation in a resting position and during loading.

RESULTS

The intra-rater reliability of both angles was found to be good (>0.8). The RadATLA was found to have an excellent intra-rater reliability with Intra-class correlation of (ICC) 0.992-0.996 (95%CI 0.889-0.999), standard error of the measurement (SEM) 1.03-3.65 and Minimal Detectable Change (MDC) 2.86-10.12. The inter-rater reliability was good with ICC of 0.798-0.969 (95%CI-0.03 to 0.964), SEM 2.9-7.6, and MDC 8.1-20.9. The RadATLA loaded at 6 weeks in all patients was at mean (SD) (range) 41.9˚ (16.5), (18.5-75.9). There was a significant difference between the patients in the Repair group compared with patients in the Reconstruction group both in RadATLA loaded at 6 weeks: 35.6˚ (11.2), (18.5-56.5) versus 55.5˚ (19), (20-75.9), (p = 0.01). The amount loaded in all patients was at mean (SD) (range) 29.2Kg (17.7), (2-56) and the percentage Body Weight was 30.7% (19), (2.1-63.2). There were no differences between the groups neither in amount loaded nor in percentage Body weight (p = 0.614-0.651).

CONCLUSIONS

The RadATLA is a reliable and reproducible angle and can be used to determine the position of the ankle, when loaded in a brace during rehabilitation following Achilles tendon rupture.

Loss of the knee-ankle coupling and unrecognized elongation in Achilles tendon rupture: effects of differential elongation of the gastrocnemius tendon

PURPOSE

The biarticular anatomy of the gastrocnemii is an important mechanism of knee-ankle coupling and differential elongation may affect this function leading to weakness of the push-off phase during the gait. Achilles tendon ruptures may cause detachment of the gastrocnemius tendon from the soleus aponeurosis with subsequent differential elongation of the individual subtendons. This study investigated the effects of such detachment by investigating tendon fusion levels of the two muscle groups, and the effect of sequential differential elongation of the gastrocnemius on the Achilles tendon resting angle (ATRA) and to the knee-ankle coupling.

METHODS

Conjoined tendon length (CTL) was measured in 23 cadavers. ATRA in knee extension (ATRA 0) and 90-degree knee flexion (ATRA 90) was measured with the gastrocnemius tendons (GT) intact, transected and with the gap reduced in 5-mm increments. In 15 specimens, knee-ankle coupling was examined.

RESULTS

Considerable anatomical variation was present with CTL ranging from 2 to 40% of fibular length. In the intact triceps, surae ATRA 0 differed from ATRA 90 by 6 degrees (p < 0.001). Cutting the gastrocnemius caused an immediate separation of the tendon ends by 19 mm. ATRA 0 and ATRA 90 increased 8 and 4 degrees (p < 0.001), significantly larger increase for ATRA 0 (p < 0.001). Lengthening the gastrocnemius 10 mm altered the coupling point 10 degrees towards dorsiflexion. Transfixing the gastrocnemius at the level of the gap where the Achilles was sectioned, decoupled the knee-ankle coupling in all but two specimens. A moderate correlation between CTL and length of the medial gastrocnemius tendon was found.

CONCLUSIONS

A greater relative ATRA 0 than relative ATRA 90 indicates differential elongation of the gastrocnemius. By elongating the gastrocnemius the knee-ankle coupling point shifts dorsally, and 20 mm elongation completely decouples the knee-ankle coupling. Independent lengthening of the gastrocnemius may explain the loss of power experienced by some patients following acute Achilles tendon rupture despite what would appear to be appropriate approximation of the ruptured tendon ends. Recognizing this occurrence is crucial when treating Achilles tendon ruptures and such patients require surgical correction in order to avoid long-term weakness of push-off strength.

The Achilles Tendon Length Measure and the Achilles Tendon Resting Angle show acceptable construct validity using the Copenhagen Achilles Length Measure as gold standard

BACKGROUND

Elongation of the Achilles tendon after rupture is a frequent complication. The Achilles Tendon Length Measure (ATLM) and the Achilles Tendon Resting Angle (ATRA) are indirect length measures using the resting angle of the ankle. Copenhagen Achilles Length Measure (CALM) is a direct ultrasound measure. The purpose of this study was to examine the construct validity of ATLM and ATRA using CALM as gold standard.

METHODS

As the three measurements measure slightly different constructs and have different scales a direct comparison was not possible. Instead a mixed linear regression model was performed investigating the three models: CALM-ATRA, CALMATLM and ATRA-ATLM.

RESULTS

130 patients were available for analysis. All three regression models demonstrated a statistically significant (p < 0.01) linear relationship and acceptable certainty of the estimates.

CONCLUSION

ATRA and ATLM were found to have acceptable construct validity when using CALM as gold standard for assessing tendon elongation after an Achilles tendon rupture.

Endoscopic Flexor Hallucis Longus Transfer for the Management of Acute Achilles Tendon Ruptures: A Prospective Case Series Report With a Minimum of 18 Months' Follow-Up

Acute Achilles tendon rupture can be treated either surgically or nonsurgically. The flexor hallucis longus (FHL) has been used successfully in patients with large chronic Achilles tendon defects. The aim of this study was to describe the clinical outcomes of isolated endoscopic FHL transfer in patients with acute Achilles tendon ruptures at a minimum follow-up of 18 months. Fifty-six male patients with an average age of 36.3 years who underwent endoscopic FHL transfer as a treatment for acute Achilles tendon ruptures were included. Follow-up was for a mean (± standard deviation) of 27.5 ± 7.29 months. At 18 months postoperatively, the Achilles tendon total rupture score mean was 95 ± 4.26, and the American Orthopaedic Foot and Ankle Society score was a mean of 96.4 ± 4.31. The median value for FHL tendon dynamometry on the surgical side was 95.72 (range 70.1 to 142), and 100.7 (range 68 to 161) for the nonoperated side. Mean ankle plantarflexion strength at 18 months was 19.19 ± 2.55 kg • m compared with the uninjured side of 19.27 ± 2.16 kg • m. Relative Achilles tendon resting angle showed a mean of -0.25° ± 2.43°. Magnetic resonance imaging performed at a minimum of 18 months postoperatively showed a homogeneous continuous Achilles tendon signal for 43 patients and heterogeneous signal intensity in 13 patients (23.21%). No patients reported any great toe complaints or symptomatic deficits of flexion strength. No neurovascular or skin complications were encountered. The current study demonstrated satisfactory and comparable results with minimal complications when using the endoscopic FHL tendon transfer in surgical management of acute Achilles tendon ruptures, compared with the currently used methods.

Early functional rehabilitation compared with traditional immobilization for acute Achilles tendon ruptures : a meta-analysis

AIMS

The aim of this meta-analysis was to assess the prognosis after early functional rehabilitation or traditional immobilization in patients who underwent operative or nonoperative treatment for rupture of the Achilles tendon.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library were searched for randomized controlled trials (RCTs) from their inception to 3 June 2020, using keywords related to rupture of the Achilles tendon and rehabilitation. Data extraction was undertaken by independent reviewers and subgroup analyses were performed based on the form of treatment. Risk ratios (RRs) and weighted mean differences (WMDs) (with 95% confidence intervals (CIs)) were used as summary association measures.

RESULTS

We included 19 trials with a total of 1,758 patients. There was no difference between the re-rupture rate (RR 0.84 (95% CI 0.56 to 1.28); p = 0.423), time to return to work (WMD -1.29 (95% CI -2.63 to 0.05); p = 0.060), and sporting activity (WMD -1.50 (95% CI -4.36 to 1.37); p = 0.306) between the early functional rehabilitation and the traditional immobilization treatment strategies. Early rehabilitation up to 12 weeks yielded significantly better Achilles tendon Total Rupture Scores ((ATRS) WMD 5.11 (95% CI 2.10 to 8.12); p < 0.001). Patients who underwent functional rehabilitation had significantly lower limb symmetry index of heel-rise work ((HRW) WMD -4.19 (95% CI -8.20 to 0.17); p = 0.041) at one year.

CONCLUSION

Early functional rehabilitation is safe and provides better early function and the same functional outcome in the longer term. Cite this article: Bone Joint J 2021;103-B(6):1021-1030.

No clinically relevant difference between operative and non-operative treatment in tendon elongation measured with the Achilles tendon resting angle (ATRA) 1 year after acute Achilles tendon rupture

PURPOSE

Studies have shown that elongation of the injured Achilles tendon after acute Achilles tendon rupture (ATR) is negatively associated with clinical outcomes. The difference between operative and non-operative treatment on the length of the Achilles tendon is only sparsely investigated. The aim of the study was to investigate if the operative and non-operative treatment of ATR had different effects on tendon elongation.

METHODS

The study was performed as a registry study in the Danish Achilles tendon database (DADB). The primary outcome of the study was an indirect measure of Achilles tendon length: the Achilles tendon resting angle (ATRA) at 1-year follow-up. The variable of interest was treatment (operative or non-operative).

RESULTS

From August 2015 to January 2019, 438 patients (154 operatively treated and 284 non-operatively treated) were registered with full baseline data and had their ATRA correctly registered at 1-year follow-up in DADB. The analysis did not show a clinically relevant nor statistically significant difference in ATRA between operative and non-operatively treated patients at 1-year follow-up (mean difference - 1.2°; 95% CI - 2.5; 0.1; n.s) after adjustment for potential confounders.

CONCLUSION

There were neither clinically relevant nor statistically significant differences in terms of the ATRA at 1-year follow-up between the operative and non-operatively treated patients. This finding suggests that operative treatment does not lead to a clinically relevant reduction in tendon elongation compared to non-operative treatment and it should therefore not be used as an argument in the choice of treatment.

LEVEL OF EVIDENCE

Level III.

Achilles tendon elongation after acute rupture: is it a problem? A systematic review

PURPOSE

Rupture of the Achilles tendon (AT) is a common injury. Strength deficits may persist over the long term, possibly owing to elongation of the tendon or inferior mechanical properties. This study aimed to provide a systematic review of the literature on the prevalence and consequences of tendon elongation in patients after acute AT rupture treatment. It was hypothesized that an elongated tendon would be associated with a worse clinical outcome.

METHODS

The databases for MEDLINE, CENTRAL and Web of Science were searched. Clinical studies related to AT rupture reporting tendon elongation and clinical or functional outcomes, with a minimum follow-up of 6 months, were eligible for inclusion. Only studies testing for statistical correlations (SCs) between AT elongation and other outcomes were eligible, with the exception of biomechanical studies in which statistically significant AT elongation was found to be a generalized finding in the study group. For these studies to be eligible, the study group had to be compared with a healthy control group, or the injured limb compared with the uninjured limb, regarding biomechanical parameters.

RESULTS

Twenty-eight papers were selected for inclusion. Mean AT elongation measured with imaging techniques ranged from 0.15 to 3.1 cm (n = 17). Ten studies investigated SCs with Patient Reported Outcome Measures (PROMs), in which two found SCs with tendon elongation. Five studies reported strength and power evaluations and their correlation with AT elongation, with two having found SCs between decreased strength and tendon elongation. In ten studies reporting data on biomechanical tests, nine found influence of tendon elongation. In this group, four out of five studies found SCs with biomechanical parameters.

CONCLUSION

Fair evidence of the influence of tendon elongation in biomechanical parameters was found. In a general population, evidence of a detrimental effect of tendon elongation on PROMs or functional strength at follow-up was not found in this review.

LEVEL OF EVIDENCE

Level IV.

No difference in strength and clinical outcome between early and late repair after Achilles tendon rupture

PURPOSE

This retrospective study aimed to determine the patient-reported and functional outcome of patients with delayed presentation, who had received no treatment until 14 days following injury of Achilles tendon rupture repaired with minimally invasive surgery and were compared with a group of sex- and age-matched patients presenting acutely. Based on the outcomes following delayed presentation reported in the literature, it was hypothesized that outcomes would be inferior for self-reported outcome, tendon elongation, heel-rise performance, ability to return to play, and complication rates than for acutely managed patients.

METHODS

Repair was performed through an incision large enough to permit mobilisation of the tendon ends, core suture repair consisting of a modified Bunnell suture proximally and a Kessler suture distally and circumferential running suture augmentation.

RESULTS

Nine patients presented 21.8 (14.9) days (range 14-42 days) after rupture. The rate of delayed presentation was estimated to be 1 in 10. At 12 months following repair, patients with delayed treatment had median (range) ATRS score of 90 (69-99) compared with 94 (75-100) in patients treated acutely presenting 0.66 (1.7) (0-5) days. There were no significant differences between groups: ATRA [mean (SD) delayed: - 6.9° (5.5), acute: - 6° (4.7)], heel-rise height index [delayed: 79% (20), acute: 74% (14)], or heel-rise repetition index [delayed: 77% (20), acute: 71% (20)]. In the delayed presentation group, two patients had wound infection and one iatrogenic sural nerve injury.

CONCLUSIONS

Patients presenting more than 2 weeks after Achilles tendon rupture may be successfully treated with minimally invasive repair.

LEVEL OF EVIDENCE

III.

Age and Tightness of Repair Are Predictors of Heel-Rise Height After Achilles Tendon Rupture

Background:

Achilles tendon rupture leads to weakness of ankle plantarflexion. Treatment of Achilles tendon rupture should aim to restore function while minimizing weakness and complications of management.

Purpose:

To determine the influence of factors (age, sex, body mass index [BMI], weight, time from injury to operative repair, and tightness of repair) in the initial surgical management of patients after an acute Achilles tendon rupture on 12-month functional outcome assessment after percutaneous and minimally invasive repair.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

From May 2012 to January 2018, patients sustaining an Achilles tendon rupture receiving operative repair were prospectively evaluated. Tightness of repair was quantified using the intraoperative Achilles tendon resting angle (ATRA). Heel-rise height index (HRHI) was used as the primary 12-month outcome variable. Secondary outcome measures included Achilles tendon total rupture score (ATRS) and Tegner score. Stepwise multiple regression was used to create a model to predict 12-month HRHI.

Results:

A total of 122 patients met the inclusion criteria for data analysis (mean ± SD age, 44.1 ± 10.8 years; 78% male; mean ± SD BMI, 28.1 ± 4.3 kg/m²). The elapsed time to surgery was 6.5 ± 4.0 days. At 12-month follow-up, patients had an HRHI of 82% ± 16% and performed 82% ± 17% of repetitions compared with the noninjured side. Participants had a mean ATRS of 87 ± 15 and a median Tegner score of 5 (range, 1-9), with a reduction in Tegner score of 2 from preinjury levels. The relative ATRA at 12 months was –4.8° ± 3.9°. Multiple regression identified younger age (B = ±0.006; P < .001) and greater intraoperative ATRA (B = 0.005; P = .053) as predictors of more symmetrical 12-month HRHI (R² = 0.19; P < .001; n = 120).

Conclusion:

Age was found to be the strongest predictor of outcome after Achilles tendon rupture. The most important modifiable risk factor was the tightness of repair. It is recommended that repair be performed as tight as possible to optimize heel-rise height 1 year after Achilles tendon rupture and possibly to reduce tendon elongation.

Relationship of Postoperative Achilles Tendon Elongation With Plantarflexion Strength Following Surgical Repair

BACKGROUND

Little data exist regarding the adverse effects of Achilles tendon (AT) elongation after rupture repair on plantarflexion strength. This study aimed to investigate the effect of AT elongation measured using AT resting angle (ATRA) on the plantarflexion strength in patients with surgically treated acute AT rupture.

METHODS

A retrospective chart review was performed on 40 patients (15 female and 25 female) who underwent open operative repair due to an acute AT rupture. At the final follow-up, AT elongation was assessed using ATRA. Plantarflexion strength (peak torques and angle-specific torques) was measured using an isokinetic dynamometer. All variables were obtained from the operated and unoperated contralateral ankles of the patients.

RESULTS

The mean ATRA was greater in the operated ankles (mean, 57 degrees; range, 39-71 degrees) compared with the unoperated ones (mean, 52 degrees; range, 36-66 degrees; P = .009). Except the plantarflexion torque at 20 degrees of plantarflexion (P = .246), all the other angle-specific torques were lower in the operated ankles (P < .05). Peak flexion torque at 30 degrees/s was lower in the operated ankle (P = .002). A negative correlation was found between operated/unoperated (O/N) ATRA and O/N plantarflexion torque ratios at 0 degrees (r = -0.404; P = .01), 10 degrees (r = -0.399; P= .011), and 20 degrees (r = -0.387; P = .014).

CONCLUSION

Postoperative AT elongation measured using ATRA may have a deleterious effect on the plantarflexion strength in patients with surgically treated acute AT rupture.

LEVEL OF EVIDENCE

Level IV, case series.

Reliability of the Copenhagen Achilles length measure (CALM) on patients with an Achilles tendon rupture

PURPOSE

The primary objective was to examine the reliability of the Copenhagen Achilles length measure (CALM) in patients with an Achilles tendon rupture and secondary to examine the reliability of Achilles tendon resting angle (ATRA) and Achilles tendon length measure (ATLM).

METHOD

The study was executed as a cross-sectional study on two different groups: one focused on CALM and the other on ATRA/ATLM. CALM was performed on 56 patients at four timepoints during the first year after injury, whereas ATRA/ATLM were carried out on 28 patients. Intra- and inter-rater reliabilities were determined using the intra-class correlation coefficient (ICC), the standard error of the measurement (SEM), and the minimal detectable change (MDC).

RESULTS

For CALM, all measurements, both for injured and non-injured sides as well as for elongation, indicated excellent relative reliability (ICC ≥ 0.75). During the four timepoints, the inter-rater absolute reliability had an SEM that ranged between 0.3 and 0.8 cm (1-4 SEM%) for injured and non-injured sides and 0.3-0.6 cm (18-29 SEM%) for elongation. On an individual level, the inter-rater absolute reliability had an MDC ranging between 0.8 and 2.2 cm (4-11 MDC%) for injured and non-injured sides and 0.8-1.7 cm (47-81 MDC%) for elongation. In the case of ATRA, relative reliability was excellent (ICC ≥ 0.75), and for ATLM, it was fair to excellent (ICC 0.58-0.79). ATRA presented a lower measurement error than ATLM.

CONCLUSION

Copenhagen Achilles length measure showed excellent relative reliability, but had a significant measurement error at four timepoints the first year following an Achilles tendon rupture.

LEVEL OF EVIDENCE

II.

Muscle structure governs joint function: linking natural variation in medial gastrocnemius structure with isokinetic plantar flexor function

Despite the robust findings linking plantar flexor muscle structure to gross function within athletes, the elderly and patients following Achilles tendon ruptures, the link between natural variation in plantar flexor structure and function in healthy adults is unclear. In this study, we determined the relationship between medial gastrocnemius structure and peak torque and total work about the ankle during maximal effort contractions. We measured resting fascicle length and pennation angle using ultrasound in healthy adults (N=12). Subjects performed maximal effort isometric and isokinetic contractions on a dynamometer. We found that longer fascicles were positively correlated with higher peak torque and total work (R²>0.41, P<0.013) across all isokinetic velocities, ranging from slow (30°/s) to fast (210°/s) contractions. Higher pennation angles were negatively correlated with peak torque and total work (R²>0.296, P<0.067). These correlations were not significant in isometric conditions. We further explored this relationship using a simple computational model to simulate isokinetic contractions. These simulations confirmed that longer fascicle lengths generate more joint torque and work throughout a greater range of motion. This study provides evidence that ankle function is strongly influenced by muscle structure in healthy adults.

Summary: Using ultrasound measurements of muscle structure and dynamometer measurements of ankle function, we found that longer muscle fascicles positively correlated with increased ankle kinetics.

Medial gastrocnemius muscle remodeling correlates with reduced plantarflexor kinetics 14 weeks following Achilles tendon rupture

Deficits in plantarflexor kinetics are associated with poor outcomes in patients following Achilles tendon rupture. In this longitudinal study, we analyzed the fascicle length and pennation angle of the medial gastrocnemius muscle and the length of the Achilles tendon using ultrasound imaging. To determine the relationship between muscle remodeling and deficits in plantarflexor kinetics measured at 14 wk after injury, we correlated the reduction in fascicle length and increase in pennation angle with peak torque measured during isometric and isokinetic plantarflexor contractions. We found that the medial gastrocnemius underwent an immediate change in structure, characterized by decreased length and increased pennation of the muscle fascicles. This decrease in fascicle length was coupled with an increase in tendon length. These changes in muscle-tendon structure persisted throughout the first 14 wk following rupture. Deficits in peak plantarflexor torque were moderately correlated with decreased fascicle length at 120 degrees per second (R² = 0.424, P = 0.057) and strongly correlated with decreased fascicle length at 210 degrees per second (R² = 0.737, P = 0.003). However, increases in pennation angle did not explain functional deficits. These findings suggest that muscle-tendon structure is detrimentally affected following Achilles tendon rupture. Plantarflexor power deficits are positively correlated with the magnitude of reductions in fascicle length. Preserving muscle structure following Achilles tendon rupture should be a clinical priority to maintain plantarflexor kinetics.NEW & NOTEWORTHY In our study, we found that when the Achilles tendon ruptures due to excessive biomechanical loading, the neighboring skeletal muscle undergoes rapid changes in its configuration. The magnitude of this muscle remodeling explains the amount of ankle power loss demonstrated by these patients once their Achilles tendons are fully healed. These findings highlight the interconnected relationship between muscle and tendon. Isolated injuries to the tendon stimulate detrimental changes to the muscle, thereby limiting joint-level function.

Gastrocnemius fascicles are shorter and more pennate throughout the first month following acute Achilles tendon rupture

The purpose of this study was to characterize the short-term effects of Achilles tendon ruptures on medial gastrocnemius. We hypothesized that the fascicles of the medial gastrocnemius muscle of the injured Achilles tendon would be shorter and more pennate immediately following the injury and would persist throughout 4 weeks post-injury. B-mode longitudinal ultrasound images of the medial gastrocnemius were acquired in 10 adults who suffered acute Achilles tendon ruptures and were treated non-operatively. Ultrasound images were acquired during the initial clinical visit following injury as well as 2 and 4 weeks following this initial clinical visit. Resting muscle structure was characterized by measuring fascicle length, pennation angle, muscle thickness, and muscle echo intensity in both the injured and contralateral (control) limbs. Fascicle length was 15% shorter (P < 0.001) and pennation angle was 21% greater (P < 0.001) in the injured muscle compared to the uninjured (control) muscle at the presentation of injury (week 0). These differences in fascicle length persisted through 4 weeks after injury (P < 0.002) and pennation angle returned to pre-injury levels. Muscle thickness changes were not detected at any of the post-injury visits (difference < 4%, P > 0.026). Echo intensity of the injured limb was 8% lower at the presentation of the injury but was not different compared to the contralateral muscle at 2 and 4 weeks post-injury. Our results suggest that Achilles tendon ruptures elicit rapid changes in the configuration of the medial gastrocnemius, which may explain long-term functional deficits.

Plantarflexor fiber and tendon slack length are strong determinates of simulated single-leg heel raise height

Achilles tendon ruptures have been linked with detrimental changes in muscle-tendon structure, which may help explain long-term functional deficits. However, the causal effects of muscle-tendon structure on joint function have not been tested in a controlled setting. Therefore, the purpose of this study was to test the implications of muscle-tendon unit parameters on simulated single-leg heel raise height. We hypothesized that muscle fiber length and resting ankle angle - a clinical surrogate measure of tendon slack length - would predict single-leg heel raise height more strongly than other parameters. To test this hypothesis, we developed a two-part simulation paradigm that recreated clinically relevant muscle-tendon scenarios and then tested these parameters on single-leg heel raise height. We found that longer muscle fibers had the greatest positive effect on single-leg heel raise height. However, tendon slack length, determined by simulating resting ankle angles in a secondary analysis, revealed a stronger negative correlation with heel raise height. Our findings support previous clinical observations that both muscle fascicle length and resting tendon length are important muscle-tendon parameters for patient function. In addition to minimizing tendon elongation following rupture, treatment plans should focus on preserving plantarflexor muscle structure to mitigate functional loses following Achilles tendon ruptures.

Plantarflexor metabolics are sensitive to resting ankle angle and optimal fiber length in computational simulations of gait

BACKGROUND

Plantarflexor structure is an important predictor of function in healthy, athletic, and some patient populations. Computational simulations are powerful tools capable of testing the isolated effects of muscle-tendon structure on gait function.

RESEARCH QUESTION

The purpose of this study was to characterize the sensitivity of plantarflexor muscle function based on muscle-tendon unit (MTU) parameters. We hypothesized that plantarflexor metabolics and shortening dynamics would be sensitive to MTU parameters.

METHODS

Stance phase of gait was simulated using a musculoskeletal model and computed muscle control algorithm. Optimal muscle fiber length, resting ankle angle, and tendon stiffness parameters were systematically changed to test these effects on plantarflexor metabolics, activation, and power. Dorsiflexor metabolics were also measured to determine the impact of the action of the antagonist muscle group.

RESULTS AND SIGNIFICANCE

Plantarflexor metabolic demands were 1.5 and 2.7 times more sensitive to optimal fiber length and resting ankle angle, respectively, compared to the effect of tendon stiffness. Increased resting ankle plantarflexion induced a large passive plantarflexion moment during early stance, which required non-physiologic dorsiflexor contractions. Conversely, longer optimal fiber and more neutral resting ankle angles increased the shortening demands of the plantarflexors. These findings highlight the importance of carefully selecting MTU parameters when modeling gait with musculoskeletal models, especially in pathologic or high-performance athlete populations.