Neuromechanical Modulation of the Achilles Tendon During Bilateral Hopping in Patients with Unilateral Achilles Tendon Rupture, Over 1 Year After Surgical Repair

Free tendon grafts for surgical management of chronic tears of the main body of the Achilles tendon: a systematic review

PURPOSE

After four weeks from injury, tears of the Achilles tendon are considered chronic. Their management is challenging, and the use of a graft is suggested when the gap between proximal and distal stumps is greater than 6 cm. The present study systematically reviews the outcome of free tendon grafts in chronic ruptures of the Achilles tendon, evaluating clinical outcomes, complications and return to sport.

METHODS

The present study was conducted according to the PRISMA 2020 guidelines. PubMed, Google Scholar, Embase, and Web of Science databases were accessed in February 2023. All the published clinical studies reporting clinical outcome, return to sport and complications of free tendon grafts used the treatment of chronic rupture of the midportion of the Achilles Tendon were accessed. The mean CMS (Coleman Methodology Score) of 65.7 suggested an overall good quality of the available published articles, attesting to the low risk of bias.

RESULTS

Data from 22 articles (368 patients with a mean age of 47 years) were retrieved. The average time from rupture to surgery was 25.1 week. At last follow-up, the AOFAS (American Orthopaedic Foot and Ankle Surgery) and ATRS (Achilles Tendon Total Rupture Score) scores improved of 33.8 (P = 0.0004), and 45.1 points (P = 0.0001) respectively. Return to activity was reported in 105 patients, and 82 (78.1%) had no activity limitations, while 19 (18.1%) had limited recreational but not daily activity limitations, and 4 (3.8%) reported limitations in daily activities. Return to sport data was reported in six studies, and 45 of 93 (48.4%) patients returned to sport at an average of 22.6 weeks.

CONCLUSION

In chronic tears of the Achilles tendon, with a gap of at least 6 cm, free tendon grafts allow predictable return to sport and acceptable recovery function.

LEVEL OF EVIDENCE

Level IV.

Achilles Tendinopathy Pathogenesis and Management: A Narrative Review

The Achilles tendon is the thickest and strongest tendon of the human body, and it is frequently injured during sports activity. The incidence of Achilles tendon pathologies has increased over recent decades, especially in the last few years, because of increased sports participation among the general population and due to the diffusion of competitive sports at a high level. Tendinopathies are common in athletes and in middle-aged overweight patients. The term "tendinopathy" refers to a condition characterised clinically by pain and swelling, with functional limitations of tendon and nearby structures, and consequently to chronic failure of healing response process. Tendinopathies can produce marked morbidity, and at present, scientifically validated management modalities are limited. Despite the constantly increasing interest and number of studies about Achilles tendinopathy (AT), there is still not a consensual point of view on which is the best treatment, and its management is still controversial. AT can be treated conservatively primarily, with acceptable results and clinical outcomes. When this approach fails, surgery should be considered. Several surgical procedures have been described for both conditions with a relatively high rate of success with few complications and the decision for treatment in patients with AT should be tailored on patient's needs and level of activity. The aim of this article is to give insights about the pathogenesis and most used and recent treatment options for AT.

Case study: The influence of Achilles tendon rupture on knee joint stress during counter-movement jump - Combining musculoskeletal modeling and finite element analysis

BACKGROUND

Presently, the current research concerning Achilles tendon rupture repair (ATR) is predominantly centered on the ankle joint, with a paucity of evidence regarding its impact on the knee joint. ATR has the potential to significantly impede athletic performance and increase tibiofemoral contact forces in athletes. The purpose of this study was to prognosticate the distribution of stress within the knee joint during a countermovement jump through the use of a simulation method that amalgamated a musculoskeletal model of a patient who underwent Achilles tendon rupture repair with a finite element model of the knee joint.

METHODS

A male elite badminton player who had suffered an acute Achilles tendon rupture in his right leg one year prior was selected as our study subject. In order to analyze his biomechanical data, we employed both the OpenSim musculoskeletal model and finite element model to compute various parameters such as joint angles, joint moments, joint contact forces, and the distribution of knee joint stress.

RESULTS

During the jumping phase, a significantly lower knee extension angle (p < 0.001), ankle dorsiflexion angle (p = 0.002), peak vertical ground reaction force (p < 0.001), and peak tibiofemoral contact force (p = 0.009) were observed on the injured side than on the uninjured side. During the landing phase, the ankle range of motion (ROM) was significantly lower on the injured side than on the uninjured side (p = 0.009), and higher peak vertical ground reaction forces were observed (p = 0.012). Additionally, it is logical that an injured person will put higher load on the uninjured limb, but the finite element analysis indicated that the stresses on the injured side of medial meniscus and medial cartilage were significantly greater than the uninjured side.

CONCLUSIONS

An Achilles tendon rupture can limit ankle range of motion and lead to greater joint stress on the affected area during countermovement jumps, especially during the landing phase. This increased joint stress may also transfer more stress to the soft tissues of the medial knee, thereby increasing the risk of knee injury. It is worth noting that this study only involves the average knee flexion angle and load after ATR in one athlete. Caution should be exercised when applying the conclusions, and in the future, more participants should be recruited to establish personalized knee finite element models to validate the results.

Altered Ankle Muscle Activation at 2-Year Post Achilles Tendon Repair: An Age, Gender, and Activity Level-Matched Comparison With Healthy Subjects

CONTEXT

The study purpose was to compare the ankle muscle activation and dynamic ankle joint stability of subjects who underwent endoscopy-assisted Achilles tendon repair (ATR; at ≥ 2 y postsurgery) with age, gender, and activity level-matched healthy control group subjects.

DESIGN

Prospective, cross-sectional study. All functional tests were performed on the involved ankle of the ATR group, and at the matched side of healthy age, gender, and activity-level control group subjects.

METHODS

Fifteen men in each group were evaluated for medial and lateral gastrocnemius, soleus, tibialis anterior, and peroneus longus muscle activation during modified star excursion balance test and heel-rise test performance. The weight-bearing lunge test (ankle dorsiflexion) and heel-rise test distance (ankle plantar flexion) also determined weight-bearing, active ankle mobility magnitudes. The Achilles Tendon Total Rupture Score and Foot and Ankle Outcome Score provided patient-reported outcome perceptions specific to Achilles tendon rupture and comprehensive foot and ankle symptoms and function, respectively.

RESULTS

Medial (P = .005) and lateral (P = .012) gastrocnemius displayed greater activation amplitudes in the ATR group during the star excursion balance test, and peroneus longus displayed greater activation amplitudes during the heel-rise test (P = .006). The star excursion balance test reach distance was comparable between groups. Active weight-bearing ankle plantar flexion (heel-rise test) and dorsiflexion (weight-bearing lunge test) mobility magnitudes were lower in the ATR group.

CONCLUSIONS

Subjects who underwent endoscopy-assisted percutaneous ATR had reduced active weight-bearing ankle dorsiflexion and plantar flexion mobility magnitudes and greater gastrocnemius and peroneus longus neuromuscular activation when performing the same tasks as healthy control group subjects. As surgical approaches evolve to less invasive, soft tissue preserving methods with less tissue morbidity and faster healing, rehabilitation approaches may likewise need to evolve.

LEVEL OF EVIDENCE

Level III.

Distal overactivation of gastrocnemius medialis in persistent plantarflexion weakness following Achilles tendon repair

Structural alterations of the triceps surae and Achilles tendon (AT) can promote plantarflexion weakness one-year following an AT repair, influencing the activation strategies of the Gastrocnemius Medialis (GM) muscle. However, this is yet to be demonstrated. We aimed to determine whether patients with plantar flexion weakness one-year after AT repair show altered GM spatial activation. In this cross-sectional and case-control study, ten middle-aged men (age 34 ± 7 years old, and 12.9 ± 1.1 months post-surgery) with a high AT total rupture score who attended conventional physiotherapy for six months after surgery, and ten healthy control men (age 28 ± 9 years old), performed maximal and submaximal (40, 60 and 90%) voluntary isometric plantarflexion contractions on a dynamometer. The peak plantar flexor torque was determined by isokinetic dynamometry and the GM neuromuscular activation was measured with a linear surface-electromyography (EMG) array. Overall EMG activation (averaged channels) increased when the muscle contraction levels increased for both groups. EMG spatial analysis in AT repaired group showed an increased activation located distally at 85-99%, 75-97%, and 79-97% of the electrode array length for 40%, 60%, and 90% of the maximal voluntary isometric contractions, respectively. In conclusion, patients with persistent plantar flexion weakness after AT rupture showed higher distal overactivation in GM.

Achilles Tendon Ruptures and Repair in Athletes-a Review of Sports-Related Achilles Injuries and Return to Play

PURPOSE OF REVIEW

Achilles tendon ruptures (ATR) are detrimental to sports performance, and optimal treatment strategy and guidelines on return to play (RTP) remain controversial. This current review investigates the recent literature surrounding nonoperative versus operative management of ATR, clinical outcomes, and operative techniques to allow the athlete a successful return to their respective sport.

RECENT FINDINGS

The Achilles tendon (AT) is crucial to the athlete, as it is essential for explosive activities such as running and jumping. Athletes that sustain an ATR play in fewer games and perform at a lower level of play compared to age-matched controls. Recent studies also theorize that ATRs occur due to elongation of the tendon with fatigue failure. Biomechanical studies have focused on comparing modes of fixation under dynamic loading to recreate this mechanism. ATRs can be career-ending injuries. Fortunately, the recent incorporation of early weight-bearing and functional rehabilitation programming for non-operative and operative patients alike proves to be beneficial. Especially for those treated nonoperatively, with the incorporation of functional rehabilitation, the risk of re-rupture among non-operative patients is beginning to approach the historical lower risk of re-rupture observed among patients treated operatively. Despite this progress in decreasing risk of re-rupture particularly among non-operative patients, operative managements are associated with unique benefits that may be of particular interest for athletes and active individuals. Recent studies demonstrate that operative intervention improves strength and functional outcomes with more efficacy compared to nonoperative management with rehabilitation. The current literature supports operative intervention in elite athletes to improve performance and shorten the duration to RTP. However, we acknowledge that surgical intervention does have inherent risks. Ultimately, most if not all young and/or high-level athletes with an ATR benefit from surgical repair, but it is crucial to take a stepwise algorithmic approach and consider other factors, which may lead towards nonoperative intervention. These factors include age, chronicity of injury, gap of ATR, social factors, and medical history amongst others in this review.

Muscle-tendon architecture in Kenyans and Japanese: Potential role of genetic endowment in the success of elite Kenyan endurance runners

AIM

The specificity of muscle-tendon and foot architecture of elite Kenyan middle- and long-distance runners has been found to contribute to their superior running performance. To investigate the respective influence of genetic endowment and training on these characteristics, we compared leg and foot segmental lengths as well as muscle-tendon architecture of Kenyans and Japanese males (i) from infancy to adulthood and (ii) non-athletes versus elite runners.

METHODS

The 676 participants were divided according to their nationality (Kenyans and Japanese), age (nine different age groups for non-athletes) and performance level in middle- and long-distance races (non-athlete, non-elite and elite adult runners). Shank and Achilles tendon (AT) lengths, medial gastrocnemius (MG) fascicle length, pennation angle and muscle thickness, AT moment arm (MA_AT ), and foot lever ratio were measured.

RESULTS

Above 8 years old, Kenyans had a longer shank and AT, shorter fascicle, greater pennation angle, thinner MG muscle as well as longer MA_AT , with lower foot lever ratio than age-matched Japanese. Among adults of different performance levels and independently of the performance level, Kenyans had longer shank, AT and MA_AT , thinner MG muscle thickness, and lower foot lever ratio than Japanese. The decrease in MG fascicle length and increase pennation angle observed for the adult Japanese with the increase in performance level resulted in a lack of difference between elite Kenyans and Japanese.

CONCLUSION

The specificity of muscle-tendon and foot architecture of elite Kenyan runners could result from genetic endowment and contribute to the dominance of Kenyans in middle- and long-distance races.

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.

Neuromechanical activation of triceps surae muscle remains altered at 3.5 years following open surgical repair of acute Achilles tendon rupture

PURPOSE

To assess whether the neuromuscular activation pattern following Achilles tendon rupture and repair may contributes to the observable functional deficits in this severe and increasingly frequent injury.

METHODS

In this study, the neuromuscular activation using surface EMG of n = 52 patients was assessed during a battery of functional performance tasks to assess potential alterations of muscular activation and recruitment. We analyzed the injured leg vs. the contralateral healthy leg at a mean of 3.5 years following open surgical repair. The testing battery included isokinetic strength testing, bipedal and single-legged heel-rise testing as well as gait analysis.

RESULTS

During isokinetic testing, we observed a higher activation integral for all triceps surae muscles of the injured side during active dorsiflexion, e.g., eccentric loading on the injured leg, while concentric plantarflexion showed no significant difference. Dynamic heel-rise testing showed a higher activation in concentric and eccentric loading for all posterior muscles on the injured side (not significant); while static heel-rise for 10 sec. revealed a significantly higher activation. Further analysis of frequency of fast Fourier-transformed EMG revealed a significantly higher median frequency in the injured leg. Gait analysis revealed a higher pre-activation of the tibialis anterior before ground contact, while medial and lateral gastrocnemius muscles of the injured leg showed a significantly higher activation during push-off phase.

CONCLUSIONS

The results of this study provide evidence on the neuromuscular changes 3.5 years following open surgical Achilles tendon repair. These complex neuromuscular changes are manifested to produce the maximum force output whilst protecting the previously injured tendon. The observed alterations may be related to an increased recruitment of type II muscle fibers which could make the muscles prone to fatigue.

LEVEL OF EVIDENCE

III.

Achilles Tendon Rupture: Mechanisms of Injury, Principles of Rehabilitation and Return to Play

The Achilles tendon is the thickest, strongest and largest tendon in the human body, but despite its size and tensile strength, it frequently gets injured. Achilles tendon ruptures (ATRs) mainly occur during sports activities, and their incidence has increased over the last few decades. Achilles tendon tears necessitate a prolonged recovery time, sometimes leaving long-term functional limitations. Treatment options include conservative treatment and surgical repair. There is no consensus on which is the best treatment for ATRs, and their management is still controversial. Limited scientific evidence is available for optimized rehabilitation regimen and on the course of recovery after ATRs. Furthermore, there are no universally accepted outcomes regarding the return to play (RTP) process. Therefore, the aim of this narrative review is to give an insight into the mechanism of injuries of an ATR, related principles of rehabilitation, and RTP.

Transmission-Mode Ultrasound for Monitoring the Instantaneous Elastic Modulus of the Achilles Tendon During Unilateral Submaximal Vertical Hopping

Submaximal vertical hopping capitalizes on the strain energy storage-recovery mechanism associated with the stretch-shortening cycle and is emerging as an important component of progressive rehabilitation protocols in Achilles tendon injury and a determinant of readiness to return to sport. This study explored the reliability of transmission mode ultrasound in quantifying the instantaneous modulus of elasticity of human Achilles tendon during repetitive submaximal hopping. A custom-built ultrasound transmission device, consisting of a 1 MHz broadband emitter and four regularly spaced receivers, was used to measure the axial velocity of ultrasound in the Achilles tendon of six healthy young adults (mean ± SD; age 26 ± 5 years; height 1.78 ± 0.11 m; weight 79.8 ± 13.6 kg) during steady-state unilateral hopping (2.5 Hz) on a piezoelectric force plate. Vertical ground reaction force and lower limb joint kinematics were simultaneously recorded. The potential sensitivity of the technique was further explored in subset of healthy participants (n = 3) that hopped at a slower rate (1.8 Hz) and a patient who had undergone Achilles tendon rupture-repair (2.5 Hz). Reliability was estimated using the mean-within subject coefficient of variation calculated at each point during the ground-contact phase of hopping, while cross-correlations were used to explore the coordination between lower limb kinematics ground reaction forces and ultrasound velocity in the Achilles tendon. Axial velocity of ultrasound in the Achilles tendon was highly reproducible during hopping, with the mean within-subject coefficient of variation ranging between 0.1 and 2.0% across participants. Ultrasound velocity decreased immediately following touch down (−19 ± 13 ms^–1), before increasing by 197 ± 81 ms^–1, on average, to peak at 2230 ± 87 ms^–1 at 67 ± 3% of ground contact phase in healthy participants. Cross-correlation analysis revealed that ultrasound velocity in the Achilles tendon during hopping was strongly associated with knee (mean r = 0.98, range 0.95–1.00) rather than ankle (mean r = 0.67, range 0.35–0.79) joint motion. Ultrasound velocity was sensitive to changes in hopping frequency in healthy adults and in the surgically repaired Achilles tendon was characterized by a similar peak velocity (2283 ± 13 ms^–1) but the change in ultrasound velocity (447 ± 21 ms^–1) was approximately two fold that of healthy participants (197 ± 81 ms^–1). Although further research is required, the technique can be used to reliably monitor ultrasound velocity in the Achilles tendon during hopping, can detect changes in the instantaneous elastic modulus of tendon with variation in hopping frequency and tendon pathology and ultimately may provide further insights into the stretch-shortening cycle and aid clinical decision concerning tendon rehabilitation protocols and readiness to return to sport.

Characteristics of L-PRP preparations for treating Achilles tendon rupture within the PATH-2 study

Platelet-rich plasma (PRP) is an autologous preparation that has been claimed to improve healing and mechanobiological properties of tendons both in vitro and in vivo. In this sub-study from the PATH-2 (PRP in Achilles Tendon Healing-2) trial, we report the cellular and growth factor content and quality of the Leukocyte-rich PRP (L-PRP) (N = 103) prepared using a standardized commercial preparation method across 19 different UK centers. Baseline whole blood cell counts (red cells, leukocyte and platelets) demonstrated that the two groups were well-matched. L-PRP analysis gave a mean platelet count of 852.6 x 10⁹/L (SD 438.96), a mean leukocyte cell count of 15.13 x 10⁹/L (SD 10.28) and a mean red blood cell count of 0.91 x 10¹²/L (SD 1.49). The activation status of the L-PRP gave either low or high expression levels of the degranulation marker CD62p before and after ex-vivo platelet activation respectively. TGF-β, VEGF, PDGF, IGF and FGFb mean concentrations were 131.92 ng/ml, 0.98 ng/ml, 55.34 ng/ml, 78.2 ng/ml and 111.0 pg/ml respectively with expected correlations with both platelet and leukocyte counts. While PATH-2 results demonstrated that there was no evidence L-PRP is effective for improving clinical outcomes at 24 weeks after Achilles tendon rupture, our findings support that the majority of L-PRP properties were within the method specification and performance.

Impact of seated and standing positions on triceps surae muscle activation in unilateral Achilles tendon rupture

Heel-rises are commonly used in the rehabilitation of individuals following Achilles tendon rupture, however, the impact of tendon elongation on triceps surae activation in seated versus standing positions has not been investigated. The purpose of this study was to investigate changes in triceps surae activation during seated compared to standing heel-rises in individuals with Achilles tendon rupture and its relationship to tendon elongation. Ten individuals with a history of Achilles tendon rupture were included in this study. Muscle activity using electromyography was examined during a heel-rise task in seated (unilateral) and standing (bilateral) positions. Soleus activity was not significantly different between sitting and standing on both the ruptured and uninjured side. On the ruptured, side there were no differences in medial or lateral gastrocnemius activity between sitting and standing; however, on the uninjured side medial and lateral gastrocnemius activity was lower in sitting compared to standing. The results of this study suggest that neuromuscular changes in triceps surae activation occur following Achilles tendon rupture. The seated heel-rise position can be used to strengthen all muscles of the triceps surae and is useful when the patient is unable to perform a standing heel-rise.

Achilles tendon cross-sectional area at 12 weeks post-rupture relates to 1-year heel-rise height

PURPOSE

Achilles tendon rupture leads to long-term plantar flexor deficits, but some patients recover functional performance better than others. Early indicators of tendon healing could be helpful in establishing patient prognosis and making individualized decisions regarding rehabilitation progression. The purpose of this study was to investigate relationships between early tendon morphology and mechanical properties to long-term heel-rise and jumping function in individuals after Achilles tendon rupture.

METHODS

Individuals after Achilles tendon rupture were assessed at 4, 8, 12, 24, and 52 weeks post-injury. Tendon cross-sectional area, length, and mechanical properties were measured using ultrasound. Heel-rise and jump tests were performed at 24 and 52 weeks. Correlation and regression analysis were used to identify relationships between tendon structural variables in the first 12 weeks to functional outcomes at 52 weeks, and determine whether the addition of tendon structural characteristics at 24 weeks strengthened relationships between functional performance at 24 and 52 weeks. Functional outcomes of individuals with < 3 cm of elongation were compared to those with > 3 cm of elongation using a Mann-Whitney U test.

RESULTS

Twenty-two participants [mean (SD) age = 40 (11) years, 17 male] were included. Tendon cross-sectional area at 12 weeks was the strongest predictor of heel-rise height (R² = 0.280, p = 0.014) and work symmetry (R² = 0.316, p = 0.008) at 52 weeks. Jumping performance at 52 weeks was not significantly related to any of the tendon structural measures in the first 12 weeks. Performance of all functional tasks at 24 weeks was positively related to performance on the same task at 52 weeks (r = 0.456-0.708, p < 0.05). The addition of tendon cross-sectional area improved the model for height LSI (R² = 0.519, p = 0.001). Tendon elongation > 3 cm significantly reduced jumping symmetry (p < 0.05).

CONCLUSION

Tendon cross-sectional area and excessive elongation related to plantar flexor performance on functional testing after Achilles tendon rupture. Once an individual is able to perform function-based testing, tendon structural measures may inform long-term prognosis. Ultrasound-based measures of tendon structure early in recovery seem to relate to later performance on functional testing. Clinically, assessing tendon structure has the potential to be used as a biomarker of tendon healing early in recovery and better predict patients at risk of negative functional outcome.

LEVEL OF EVIDENCE

II.

Tendon morphology and mechanical properties assessed by ultrasound show change early in recovery and potential prognostic ability for 6-month outcomes

PURPOSE

Optimizing tendon structural recovery during the first 12 weeks after Achilles tendon rupture is a prime target to improve patient outcomes, but a comprehensive understanding of biomarkers is needed to track early healing. The purpose of this study was to observe healing of tendon structure over time using ultrasound-based, tendon-specific measures and to identify relationships between tendon structural characteristics and clinical measures of gait and strength.

METHODS

Twenty-seven participants (21 males, mean (SD) age 39 (11) years) were assessed at 4, 8, 12, and 24 weeks after injury or surgery using ultrasound imaging techniques. Gait analysis and strength testing were added at the later time points.

RESULTS

Ruptured tendons had significantly lower dynamic shear modulus (p < 0.001), greater tendon cross-sectional area (p < 0.001), and greater length (p < 0.001) than the uninjured side. Dynamic shear modulus, cross-sectional area, and length were found to increase over time (p < 0.01). Tendon structure at 4 weeks post-injury [cross-sectional area symmetry (r = 0.737, p = 0.002) and dynamic shear modulus (r = 0.518, p = 0.040)] related to stance phase walking symmetry at 24 weeks.

CONCLUSIONS

Tendon structure assessed by ultrasound imaging changes over the first 24 weeks of healing after Achilles tendon rupture, suggesting it could be used as a biomarker to track tendon healing early in recovery. Additionally, tendon structure within the first 12 weeks relates to later walking gait and heel-rise symmetry, which may indicate that tendon structure could have prognostic value in the care of these patients. This study's clinical relevance is in its support for using ultrasound imaging to assess early patient healing and prognosticate later patient outcomes after Achilles tendon rupture.

LEVEL OF EVIDENCE

Level 2, prospective cohort prognostic study.

Lower extremity work along with triceps surae structure and activation is altered with jumping after Achilles tendon repair

Achilles tendon rupture leads to long term plantar flexor deficits. The purpose of this study was to describe changes in jumping biomechanics along with triceps surae structure and activation in individuals after Achilles repair. Eleven individuals 1-3 years following Achilles repair and 10 healthy controls were included. Kinetics and kinematics, analyzed using a constituent lower extremity work (CLEW) approach, and muscle activity using surface electromyography (EMG) were collected during a unilateral hopping task. Triceps surae myotendinous structure was assessed using ultrasound imaging. There were no differences in jump height, absolute limb work, or cost of transport between groups. During takeoff, the knee did more (p < 0.001) and ankle did less concentric work (p < 0.001), and lateral gastrocnemius rate of rise was higher (p = 0.02) on the ruptured side. During landing, the knee did more eccentric work (p = 0.033) and lateral gastrocnemius (p = 0.003) and soleus (p = 0.02) activation amplitude prior to landing was higher on the ruptured side. Individuals after Achilles tendon repair shift work toward the knee and alter muscle recruitment. Differences in lateral gastrocnemius activity may indicate that it is well-situated to generate power during takeoff and assist in landing with the soleus. The lack of change in muscle activity and decreased cross sectional area of the medial gastrocnemius may suggest that this muscle atrophies and does not accommodate to the hopping task. Clinical Significance: Proximal lower extremity strengthening along with emphasizing medial gastrocnemius and soleus activation during the recovery of patients with Achilles tendon repair may be rehabilitative targets for improved jumping performance. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Heel-Rise Height Deficit 1 Year After Achilles Tendon Rupture Relates to Changes in Ankle Biomechanics 6 Years After Injury

BACKGROUND

It is unknown whether the height of a heel-rise performed in the single-leg standing heel-rise test 1 year after an Achilles tendon rupture (ATR) correlates with ankle biomechanics during walking, jogging, and jumping in the long-term.

PURPOSE

To explore the differences in ankle biomechanics, tendon length, calf muscle recovery, and patient-reported outcomes at a mean of 6 years after ATR between 2 groups that, at 1-year follow-up, had less than 15% versus greater than 30% differences in heel-rise height.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Seventeen patients with less than 15% (<15% group) and 17 patients with greater than 30% (>30% group) side-to-side difference in heel-rise height at 1 year after ATR were evaluated at a mean (SD) 6.1 (2.0) years after their ATR. Ankle kinematics and kinetics were sampled via standard motion capture procedures during walking, jogging, and jumping. Patient-reported outcome was evaluated with Achilles tendon Total Rupture Score (ATRS), Physical Activity Scale (PAS), and Foot and Ankle Outcome Score (FAOS). Tendon length was evaluated by ultrasonography. The Limb Symmetry Index (LSI = [Injured Side ÷ Healthy Side] × 100) was calculated for side differences.

RESULTS

The >30% group had significantly more deficits in ankle kinetics during all activities compared with patients in the <15% group at a mean of 6 years after ATR (LSI, 70%-149% and 84%-106%, respectively; P = .010-.024). The >30% group, compared with the <15% group, also had significantly lower values in heel-rise height (LSI, 72% and 95%, respectively; P < .001) and heel-rise work (LSI, 58% and 91%, respectively; P < .001) and significantly larger side-to-side difference in tendon length (114% and 106%, respectively; P = .012). Achilles tendon length correlated with ankle kinematic variables ( r = 0.38-0.44; P = .015-.027) whereas heel-rise work correlated with kinetic variables ( r = -0.57 to 0.56; P = .001-.047). LSI tendon length correlated negatively with LSI heel-rise height ( r = -0.41; P = .018). No differences were found between groups in patient-reported outcome ( P = .143-.852).

CONCLUSION

Height obtained during the single-leg standing heel-rise test performed 1 year after ATR related to the long-term ability to regain normal ankle biomechanics. Minimizing tendon elongation and regaining heel-rise height may be important for the long-term recovery of ankle biomechanics, particularly during more demanding activities such as jumping.

Effect of position, time in the season, and playing surface on Achilles tendon ruptures in NFL games: a 2009-10 to 2016-17 review

OBJECTIVES

Achilles tendon (AT) ruptures are a potentially career-altering and ending injury. Achilles tendon ruptures have a below average return-to-play rate compared to other common orthopaedic procedures for National Football League (NFL) players. The objective of this study was to monitor the incidence and injury rates (IR) of AT ruptures that occurred during the regular season in order to evaluate the influence of player position, time of injury, and playing surface on rupture rates.

METHODS

A thorough online review was completed to identify published injury reports and public information regarding AT ruptures sustained during regular season and post-season games in the National Football League (NFL) during the 2009-10 to 2016-17 seasons. Team schedules, player position details and stadium information was used to determine period of the season of injury and playing surface. IRs were calculated per 100 team games (TG). Injury rate ratios (IRR) were utilized to compare IRs.

RESULTS

During eight monitored seasons, there were 44 AT ruptures in NFL games. A majority of AT ruptures were sustained in the first eight games of the regular season (n = 32, 72.7%). There was a significant rate difference for the first and second four-game segments of the regular season compared to the last two four-game segments of the regular season. Defensive players suffered a majority of AT ruptures (n = 32, 72.7%). The IR on grass was 1.00 per 100 TG compared to 1.08 per 100 TG on artificial turf (IRR: 0.93, p = .80).

CONCLUSION

A significant increase in AT ruptures occurred in the first and second four game segments of the regular season compared to the last two-four game segments of the regular season. Defensive players suffered a majority of AT ruptures compared to offensive or specialist players. There was no difference between AT rupture rates and playing surface in games.