Early Neuromechanical Outcomes of the Triceps Surae Muscle-Tendon After an Achilles' Tendon Repair

Auditing the Representation of Female Athletes in Sports Medicine Research: Achilles Repair

Background

Establishing evidence-based recommendations specific to female athletes has been overlooked in sports medicine. Achilles tendon rupture is one of the most common musculoskeletal injuries, occurring in 15 to 55 per 100 000 people annually. Differences in injury rates could be due to hormonal effects, as estrogen receptors have been identified in tendons along with decreased tendon strain based on oral contraceptive use. The primary purpose of this study was to audit the representation of female athletes in the literature regarding Achilles repair.

Methods

An electronic search was performed using PubMed to identify articles related to Achilles repair using the protocol by Smith et al. Studies were assessed by population, size, athletic caliber, study impact, research theme, and menstrual status.

Results

Female representation across all studies was 1783 of 10 673 subjects (16.7%). Composition of included studies was predominantly mixed-sex cohorts with 131 of 169 (77.5%) included studies. Within mixed-sex cohort studies, the total representation of female athletes was 1654 of 8792 participants (18.9%). Thirty-two studies were male only, constituting 1540 participants, whereas 3 studies were female only composed of 86 athletes. Importantly, the disparity between male and female representation worsened as the athletic caliber of the study population increased, with 5.0% female representation in studies with professional athletes. No study collected data related to menstrual status and its potential relationship to Achilles rupture or postoperative outcomes.

Conclusion

Mixed-sex cohort studies underrepresented female athletes, and male-only cohort studies were more common than female-only studies. These findings indicate a need for increased representation of female athletes as well as acknowledgment of menstrual status in research related to Achilles repair. Future studies should focus on representation of female athletes and data collection related to sex-specific hormones, hormonal contraceptive use, and menstrual status to improve treatment of Achilles tendon ruptures for female athletes.

Level of Evidence

Level IV, case series.

Shear Wave Tensiometry Can Detect Loading Differences Between Operated and Unaffected Achilles Tendon

BACKGROUND

The clinically relevant healing process of a ruptured and repaired Achilles tendon (AT) can last more than a year. The purpose of this cross-sectional study was to test if shear wave tensiometry is able to detect AT loading changes between a surgically managed AT rupture versus the unaffected contralateral tendon. Our secondary aims were to evaluate differences in mechanical properties when measured with myotonometry and morphological properties of the tendons measured with ultrasonographic imaging.

METHODS

Twenty-one patients with surgically treated AT ruptures were investigated 12-37 months after surgery. Tendon load was measured using a shear wave tensiometer composed of an array of 4 accelerometers fixed on the tendon. Shear wave speed along the Achilles tendon was evaluated at different levels of ankle torque for both the operated and the unaffected side. Mechanical properties of the tendons were evaluated using MyotonPRO and morphological properties using ultrasonographic imaging. Friedman test was used to assess differences in AT wave speed, stiffness, thickness, and cross-sectional area between the operated and the unaffected tendon.

RESULTS

We found a significant shear wave speed difference between sides at every ankle joint torque (P < .05) with a large effect size for the lowest ankle torque and small to medium effect sizes for higher ankle torque. Stiffness, thickness, and cross-sectional area of the operated tendon remained significantly higher compared to the unaffected side.

CONCLUSION

In this cohort, we found that shear wave tensiometry can detect differences between operated and unaffected AT during a standardized loading procedure. The shear wave speed along the operated tendon, as well as the mechanical and morphologic properties, remains higher for 1-3 years after a rupture.

LEVEL OF EVIDENCE

Level III, case-control study.

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.

Muscle-tendon morphomechanical properties of non-surgically treated Achilles tendon 1-year post-rupture

BACKGROUND

Achilles tendon rupture appears to alter stiffness and length of the tendon. These alterations may affect the function of tendon in force transmission and in energy storage and recovery. We studied the mechanical properties of the Achilles' tendon post-rupture and their association with function.

METHODS

Twenty-four (20 males, 4 females) participants (mean age: 43 y, 176 cm, 81 kg) were recruited. Ultrasonography and dynamometry were used to assess the muscle-tendon unit morphological and mechanical properties of non-surgically treated patients 1-year post rupture.

FINDINGS

Injured tendons were longer with difference of 1.8 cm (95%CI: 0.5-1.9 cm; P < 0.001), and thicker by 0.2 mm (0.2-0.3 mm; P < 0.01). Medial gastrocnemius cross-sectional area was 1.0 cm² smaller (0.8-1.1 cm²; P < 0.001), fascicles were 0.6 cm shorter (0.5-0.7 cm; P < 0.001) and pennation angle was 2.5° higher (1.3-3.6°; P < 0.001) when compared to the uninjured limb. We found no differences between injured and uninjured tendon stiffness 1-year post-rupture (mean difference: 29.8 N/mm, -7.7-67.3 N/mm; P = 0.170). The injured tendon showed 1.8 mm (1.2-2.4 mm; P < 0.01) lower elongation during maximal voluntary isometric contractions. Patient-reported functional outcome was related to the tendon resting length (β = 0.68, r(10) = 4.079, P = 0.002). Inter-limb differences in the medial gastrocnemius fascicle length were related to inter-limb differences in maximum contractions (β = 1.17, r(14) = 2.808, P = 0.014).

INTERPRETATION

Longer Achilles tendon resting length was associated with poorer self-evaluated functional outcome. Although the stiffness of non-surgically treated and uninjured tendons was similar 1-year post rupture, plantar flexion strength deficit was still present, possibly due to shorter medial gastrocnemius fascicle length.

Recovery from Achilles Tendon Repair: A Combination of Postsurgery Outcomes and Insufficient Remodeling of Muscle and Tendon

INTRODUCTION

Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle-tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes in MTU properties and strength deficits in ATR patients.

METHODS

Eleven male subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force-length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force-length properties were performed with various iterations of MTU properties found between the unaffected and the affected side.

RESULTS

The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely.

CONCLUSIONS

These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.

Individual variation in Achilles tendon morphology and geometry changes susceptibility to injury

The unique structure of the Achilles tendon, combining three smaller sub-tendons, enhances movement efficiency by allowing individual control from connected muscles. This requires compliant interfaces between sub-tendons, but compliance decreases with age and may account for increased injury frequency. Current understanding of sub-tendon sliding and its role in the whole Achilles tendon function is limited. Here we show changing the degree of sliding greatly affects the tendon mechanical behaviour. Our in vitro testing discovered distinct sub-tendon mechanical properties in keeping with their mechanical demands. In silico study based on measured properties, subject-specific tendon geometry, and modified sliding capacity demonstrated age-related displacement reduction similar to our in vivo ultrasonography measurements. Peak stress magnitude and distribution within the whole Achilles tendon are affected by individual tendon geometries, the sliding capacity between sub-tendons, and different muscle loading conditions. These results suggest clinical possibilities to identify patients at risk and design personalised rehabilitation protocols.

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.

Morphological and functional outcomes of operatively treated Achilles tendon ruptures

Objectives: Achilles tendon rupture leads to functional impairments and these may be underpinned by morphological changes in the muscle-tendon unit. The functional performance of the injured limb will be impaired regardless of time since surgery and these impairments occur alongside changes in muscle-tendon morphology. Methods: Following operative treatment of Achilles tendon rupture and short-term immobilization, 12 patients completed a battery of tests during a single visit to the laboratory (performed an average of 4.4 ± 2.6 years post-surgery). Patients completed the Achilles' tendon rupture score (ATRS), tests of the ankle and hip range of motion (ROM) and ultrasound measurements of muscle-tendon architecture. Data on isokinetic (30°/s, 60°/s) plantar flexion strength, jumping performance and walking-running were also collected on the same visit. Percentage deficits were expressed relative to the non-injured limb and determined for statistical significance (p < 0.05). Relationships between outcome measures and time since surgery were tested using Pearson's correlation coefficients (p < 0.05). Results: The repaired limb showed a shorter muscle fascicle length (12.1-19.6%), increased fascicle pennation (18.0 ± 22.14%) and reduced muscle thickness (9.1-20.1%) in the gastrocnemius and/or soleus along with greater tendon cross-sectional area (46.7 ± 34.47%). Functionally, the repaired limb displayed lower countermovement jump height (-12.6 ± 15.68%) and longer drop jump contact times (5.5 ± 5.7%). Also, the repaired limb showed reduced hip internal-external ROM (6.3 ± 8.2%) but no differences existed between limbs for plantar flexion ROM and strength or gait characteristics. Good ATRS outcomes were reported (mean: 87.9 ± 16.2, range: 43-100) which related to time since surgery (r = 0.79) but individual ATRS items did not correlate with corresponding objective measures. Conclusion: Plantar flexor atrophy following surgically treated Achilles tendon rupture is partially compensated for by remodeling of the fascicles; however, impairments may still persist many years into the postoperative period although these may be more pronounced in high-velocity activities.

Muscle Fascicles Exhibit Limited Passive Elongation Throughout the Rehabilitation of Achilles Tendon Rupture After Percutaneous Repair

Achilles tendon rupture (ATR) results in long-term functional and structural deficits, characterized by reduced ankle mobility and plantarflexor muscle atrophy. However, it remains unclear how such functional impairments develop after surgical repair. While it is known that this injury negatively affects the tendon’s function, to date, limited work has focused on the short-term effect of ATR on the structure of the muscles in series. The aim of this study was to characterize changes in medial gastrocnemius architecture and its response to passive lengthening during the post-surgical rehabilitative period following ATR. Both injured and contralateral limbs from 10 subjects (1 female, BMI: 27.2 ± 3.9 kg/m²; age: 46 ± 10 years) with acute, unilateral ATR were assessed at 8, 12, and 16 weeks after percutaneous surgical repair. To characterize the component tissues of the muscle-tendon unit, resting medial gastrocnemius muscle thickness, fascicle length, and pennation angle were determined from ultrasound images with the ankle in both maximal plantarflexion and dorsiflexion. The ankle range of motion (ROM) was determined using motion capture; combined ultrasound and motion capture determined the relative displacement of the musculotendinous junction (MTJ) of the AT with the medial gastrocnemius. The ATR-injured gastrocnemius muscle consistently exhibited lower thickness, regardless of time point and ankle angle. Maximal ankle plantarflexion angles and corresponding fascicle lengths were lower on the injured ankle compared to the contralateral throughout rehabilitation. When normalized to the overall ankle ROM, both injured fascicles and MTJ displacement exhibited a comparably lower change in length when the ankle was passively rotated. These results indicate that when both ankles are passively exposed to the same ROM following ATR surgery, both ipsilateral Achilles tendon and gastrocnemius muscle fascicles exhibit limited lengthening compared to the contralateral MTU tissues. This appears to be consistent throughout the rehabilitation of gait, suggesting that current post-operative rehabilitative exercises do not appear to induce muscle adaptations in the affected MTU.

A Pilot Study of Musculoskeletal Abnormalities in Patients in Recovery from a Unilateral Rupture-Repaired Achilles Tendon

The purpose of this study was to compare the inter-limb joint kinematics, joint moments, muscle forces, and joint reaction forces in patients after an Achilles tendon rupture (ATR) via subject-specific musculoskeletal modeling. Six patients recovering from a surgically repaired unilateral ATR were included in this study. The bilateral Achilles tendon (AT) lengths were evaluated using ultrasound imaging. The three-dimensional marker trajectories, ground reaction forces, and surface electromyography (sEMG) were collected on both sides during self-selected speed during walking, jogging and running. Subject-specific musculoskeletal models were developed to compute joint kinematics, joint moments, muscle forces and joint reaction forces. AT lengths were significantly longer in the involved side. The side-to-side triceps surae muscle strength deficits were combined with decreased plantarflexion angles and moments in the injured leg during walking, jogging and running. However, the increased knee extensor femur muscle forces were associated with greater knee extension degrees and moments in the involved limb during all tasks. Greater knee joint moments and joint reaction forces versus decreased ankle joint moments and joint reaction forces in the involved side indicate elevated knee joint loads compared with reduced ankle joint loads that are present during normal activities after an ATR. In the frontal plane, increased subtalar eversion angles and eversion moments in the involved side were demonstrated only during jogging and running, which were regarded as an indicator for greater medial knee joint loading. It seems after an ATR, the elongated AT accompanied by decreased plantarflexion degrees and calf muscle strength deficits indicates ankle joint function impairment in the injured leg. In addition, increased knee extensor muscle strength and knee joint loads may be a possible compensatory mechanism for decreased ankle function. These data suggest patients after an ATR may suffer from increased knee overuse injury risk.

Muscle activation during maximum voluntary contraction and m-wave related in healthy but not in injured conditions: Implications when normalizing electromyography

BACKGROUND

Electromyography signal amplitude is influenced by a variety of factors. Normalization strategies aimed at decreasing signal variability include using peak electromyography signal during a maximum voluntary contraction and peak-to-peak M-wave amplitude. However, whether these normalization methods are comparable has not been investigated in injured populations. This study investigated the relationship between peak signal during maximum voluntary contraction and M-wave amplitude in individuals with a unilateral Achilles tendon rupture. Secondarily, we observed whether the two normalizations strategies would yield similar results when evaluating between limb differences in muscle activity during a jump task.

METHODS

Eleven individuals 1-3 years after a unilateral Achilles tendon rupture were included in this study. Surface electromyography was used on the medial and lateral gastrocnemii bilaterally. Peak maximum voluntary contraction, M-wave amplitude, and electromyography during a jumping task were collected.

FINDINGS

A strong relationship was observed between peak maximum voluntary contraction and M-wave amplitude on the uninjured (r = 0.71-0.88, P < 0.05) but not on the ruptured side (r = 0.41-0.44, P > 0.05). The two normalization techniques did not produce different results when comparing the uninjured and ruptured sides.

INTERPRETATION

The findings of this study suggest that M-wave normalization yields similar results as peak maximum voluntary contraction-normalized electromyography in uninjured conditions. M-wave normalization may be a useful strategy in an injured population where a maximal muscle contraction is unsafe or impaired.

Acute and Long-Term Effects of Mechanotherapy on the Outcome After an Achilles Repair: A Prospective Cohort Study With Historical Controls

OBJECTIVES

To evaluate the effects of vibration on Achilles' tendon microcirculation and characteristics following surgical repair of Achilles' tendon rupture.

DESIGN

Cohort study with historical controls.

SETTING

A university institute.

PARTICIPANTS

Participants (N=32), including 19 (16 men, 3 women; median [range] age: 43.0 [25.0-57.0] years) and 13 (10 men, 3 women; 44.00 [29.0-60.0] years) in the vibration (application to the ball of the foot, 30Hz, 2mm amplitude, 4kg pressure, and self-administration) and control groups, respectively, who underwent unilateral Achilles' tendon repairs were recruited.

INTERVENTION

A 4-week vibration intervention in the vibration group.

MAIN OUTCOME MEASUREMENTS

The tendon microcirculation was measured after the first session of vibration. The participants were evaluated repeatedly with bilateral follow-up measurements of tendon stiffness, 3 functional outcome tests, and a questionnaire survey.

RESULTS

Acute effects of the vibration were observed immediately after the 5-minute vibration (P≤.001). Lower total hemoglobin and oxygen saturation were respectively observed (P=.043) in the repaired legs 3 and 6 months postsurgery in the vibration group as compared with the control group. The vibration group also showed greater tendon stiffness, heel raising height and hopping distance 3 or 6 months postoperation in both the repaired and noninjured legs (all P<.05). The microcirculatory characteristics 2 months postoperation were correlated with the outcomes at 6 months postoperation.

CONCLUSIONS

Differences in microcirculatory characteristics and better rehabilitation outcomes were observed in the legs with an Achilles repair that underwent the early vibration intervention.

Muscular Morphomechanical Characteristics After an Achilles Repair

BACKGROUND

The purpose of the study was to compare the morphomechanical and functional characteristics during maximal isometric, concentric, and eccentric contractions in the legs of patients that underwent unilateral Achilles tendon repair with those in their noninjured control legs.

METHODS

Twenty participants (median age = 38.2 years; range, 21.1-57.3 years) who underwent Achilles repair between 3 and 12 months ago were recruited with the following measures: (1) mechanical stiffness of the aponeurosis and (2) electromyography and medial gastrocnemius fascicle angle and length, standing muscle and tendon length, and height of heel rise with isometric contraction.

RESULTS

Compared to the noninjured legs, the repaired legs showed less resting fascicle length, standing muscle length, isometric plantarflexion torque, and heel raise distance ( Ps ranged between .044 and <.001). During the concentric and eccentric phases of the raising and lowering test, the repaired legs demonstrated less fascicle length ( P ≤ .028) but greater tendinous tissue length ( Ps ranged between .084 and <.001) and fascicle angle ( Ps ranged between .247 and .008) and fewer change magnitudes of the fascicle length and tendinous tissue length ( P ≤ .003). The change magnitudes of the morphological characteristics showed correlations with the torque or distance.

CONCLUSION

Selecting the appropriate surgical repair and rehabilitation for Achilles tendon ruptures is recommended for restoring the length and mechanical strength of the muscle-tendon unit of plantar-flexion muscles.

LEVEL OF EVIDENCE

Level III, comparative study.

Can Weakness in End-Range Plantar Flexion After Achilles Tendon Repair Be Prevented?

Background

Disproportionate end-range plantar flexion weakness, decreased passive stiffness, and inability to perform a heel rise on a decline after Achilles tendon repair are thought to reflect increased tendon compliance or tendon lengthening. Since this was first noted, we have performed stronger repairs and avoided stretching into dorsiflexion for the first 12 weeks after surgery.

Hypothesis

Using stronger repairs and avoiding stretching into dorsiflexion would eliminate end-range plantar flexion weakness and normalize passive stiffness.

Study Design

Case series; Level of evidence, 4.

Methods

Achilles repairs with epitendinous augmentation were performed on 18 patients. Plantar flexion torque, dorsiflexion range of motion (ROM), passive joint stiffness, and standing single-legged heel rise on a decline were assessed at 43 ± 24 months after surgery (range, 9 months to 8 years). Maximum isometric plantar flexion torque was measured at 20° and 10° of dorsiflexion, neutral position, and 10° and 20° of plantar flexion. Passive dorsiflexion ROM was measured with a goniometer. Passive joint stiffness was computed from the increase in passive torque from 10° to 20° of dorsiflexion. Tendon thickness was measured by use of digital calipers. Plantar flexion electromyographic (EMG) data were recorded during strength and functional tests. Analysis of variance and chi-square tests were used to assess weakness and function.

Results

Marked weakness was evident on the involved side at 20° of plantar flexion (deficit, 26% ± 18%; P < .001), with no weakness at 20° of dorsiflexion (deficit, 6% ± 17%; P = .390). Dorsiflexion ROM was decreased 5.5° ± 8° (P = .015), and tendon width was 8 ± 3 mm greater on the involved side (P < .001). Passive joint stiffness was similar between the involved and noninvolved sides. Only 2 of 18 patients could perform a decline heel rise on the involved side compared with 18 of 18 on the noninvolved side (P = .01). No difference in EMG amplitude was found between the involved and noninvolved sides during the strength or heel rise tests.

Conclusion

The use of stronger repair techniques and attempts to limit tendon elongation by avoiding dorsiflexion stretching did not eliminate weakness in end-range plantar flexion. EMG data confirmed that end-range weakness was not due to neural inhibition. Physiological changes that alter the force transmission capability of the healing tendon may be responsible for this continued impairment. This weakness has implications for high-demand jumping and sprinting after Achilles tendon repair.

Short-term functional assessment of gait, plantarflexor strength, and tendon properties after Achilles tendon rupture

BACKGROUND

Although early functional rehabilitation (EFR) has been suggested to yield rapid functional recovery after Achilles tendon rupture (ATR) compared to conventional rehabilitation (CR), most quantitative assessments occur long after rehabilitation has been completed. Few data exist regarding the short-term functional gains during the healing period post-ATR. It remains unclear if EFR allows for an objectively faster return to function. The aim of this study was to examine EFR's effect on gait, plantarflexor strength, and tendon properties in early post-operative follow-ups.

METHODS

Fourteen patients received either EFR (n = 6) or CR (n = 8) after percutaneous ATR repair. Functional gait analysis, maximal voluntary isometric contractions (MVICs), and Achilles tendon properties were assessed at 8 and 12 weeks post-op.

RESULTS

Comparison of EFR against CR yielded no statistically significant differences in ankle kinematics or kinetics, Achilles tendon properties or MVICs on the injured (INJ) ankle at either time point. During gait, only CR patients demonstrated significantly lower plantarflexion moments on INJ at 8 weeks (0.817 ± 0.151 N·m/kg vs. 1.172 ± 0.177 N·m/kg, p = 0.002). All patients exhibited deficits in plantarflexor moment at 8 weeks and eversion moment at 12 weeks on INJ during gait that had effect sizes of note when compared to CON.

SIGNIFICANCE

ATR patients, regardless of rehabilitation, exhibit deficits in gait, AT properties, and single-limb strength at 8 weeks. Though AT properties and single-limb plantarflexor isometric strength remain at a deficit at 12 weeks, bipedal plantarflexion moments are comparable between INJ and CON. Though effect size calculations suggested clinically significant differences, clear benefits of EFR compared to CR were not found.

Individuals Post Achilles Tendon Rupture Exhibit Asymmetrical Knee and Ankle Kinetics and Loading Rates During a Drop Countermovement Jump

Study Design Cross-sectional laboratory study. Background Asymmetrical knee loading during jogging and hopping has been reported in individuals who have ruptured their Achilles tendon. No studies have examined knee loads in individuals post Achilles tendon rupture during high-demand tasks, such as single-limb landings. Objectives We sought to determine whether individuals post Achilles tendon rupture demonstrated asymmetrical knee loads and impact forces during drop countermovement jumps (CMJs). Methods Achilles tendon length and the single-leg heel-rise test for endurance were assessed in 34 individuals (31 male) 6.1 ± 2.0 years post Achilles tendon rupture. Movement patterns were assessed during a drop CMJ. Data were analyzed via repeated-measures analyses of variance, with comparisons between limbs and prior treatment history (surgery versus nonsurgery). Results An 8.6% longer Achilles tendon (P<.001) was found in the involved limb. During the single-leg heel-rise test, the involved limb demonstrated 22.4% less endurance and 14.6% lower heel-rise height (all, P<.001). During the landing phase of the drop CMJ, the involved limb exhibited 39.6% greater loading rate (P<.001), 16.8% greater eccentric knee power (P = .048), but 21.6% lower eccentric ankle power (P<.001). During the take-off phase, the involved limb exhibited 12.1% lower jump height and 19.9% lower concentric ankle power (both, P<.001). Conclusion Elevated eccentric knee joint power and higher loading rates during a drop CMJ in individuals who experienced Achilles tendon rupture several years earlier may be a compensation pattern for reduced plantar flexor function. This movement pattern may place individuals who have had an Achilles tendon rupture at greater risk for knee injuries. J Orthop Sports Phys Ther 2018;48(1):34-43. Epub 26 Oct 2017. doi:10.2519/jospt.2018.7684.

Clinical failure after Dresden repair of mid-substance Achilles tendon rupture: human cadaveric testing

PURPOSE

The purpose of this study was to describe the angle of clinical failure during cyclical mobilization exercises in the Achilles tendon of human cadaveric specimens that were repaired using the Dresden technique and FiberWire^® No. 2. The secondary aim was to identify the secure limit of mobilization, the type of failure, and the type of apposition.

METHODS

The lower limbs of eight males (mean age: 60.3 ± 6.3 years) were repaired with the Dresden technique following complete, percutaneous mid-substance Achilles tendon rupture. A basal tension of 10 N at 30° of plantarflexion was placed on each specimen. The angle of the ankle during clinical failure (tendon ends separation >5 mm) was then tested via cyclical exercises (i.e. 100 cycles between 30° and 15° of plantarflexion; 100 cycles between 15° of plantarflexion and 0°; 100 cycles between 0° and 15° of dorsiflexion; and 100 cycles between 15° of dorsiflexion and full dorsiflexion). Clinical failure was determined using the Laplacian edge detection filter, and the angle of clinical failure was obtained using a rotatory potentiometer aligned in relation to the intermalleolar axis of each foot specimen. The type of failure (knot, tendon, or suture) and apposition (termino-terminal or non-termino-terminal) were determined. Descriptive statistics were used to obtain the mean; standard deviation; 95 % confidence interval; 1st, 25th, 50th, 75th, and 100th percentiles; and the standard error of the mean for angle data. Proportions were used to describe the type of failure and apposition.

RESULTS

The main results were a mean angle of clinical failure equal to 12.5° of plantarflexion, a limit of mobilization equal to 14.0° of plantarflexion, tendon failure type, and non-termino-terminal apposition in all specimens.

CONCLUSIONS

While the mean angle of clinical failure in human cadaveric models was 12.5° of plantarflexion, after 14.0° of plantarflexion, the percutaneous Dresden technique was found insecure for cyclical mobilization exercises, with a 5 % range of error. These findings are clinically relevant as they provide mechanical limits for diminishing the risk of Achilles lengthening during immediate rehabilitation.

Elevated Knee Joint Kinetics and Reduced Ankle Kinetics Are Present During Jogging and Hopping After Achilles Tendon Ruptures

BACKGROUND

Deficits in plantarflexor function are common after an Achilles tendon rupture. These deficits may result in an altered distribution of joint loads during lower extremity tasks.

HYPOTHESIS

We hypothesized that, regardless of treatment, the Achilles tendon-ruptured limb would exhibit deficits in ankle kinematics and joint power while exhibiting elevated knee joint power and patellofemoral joint loads during walking, jogging, and hopping. We further hypothesized that this loading pattern would be most evident during jogging and hopping.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-four participants (17 participants treated surgically, 17 treated nonsurgically) were tested at a mean 6.1 ± 2.0 years after an Achilles tendon rupture. Lower extremity kinematics and kinetics were assessed while participants completed walking, jogging, and single-legged hopping trials. Patellofemoral joint stress was calculated via a musculoskeletal model. Data were analyzed via mixed-model repeated analyses of variance (α = .05) and the limb symmetry index (LSI).

RESULTS

No differences ( P ≥ .05) were found between the surgical and nonsurgical groups. In both groups, large side-to-side deficits in the plantarflexion angle at toeoff (LSI: 53.5%-73.9%) were noted during walking, jogging, and hopping in the involved limb. Side-to-side deficits in the angular velocity were only present during jogging (LSI: 93.5%) and hopping (LSI: 92.5%). This pattern was accompanied by large deficits in eccentric (LSI: 80.8%-94.7%) and concentric (LSI: 82.2%-84.7%) ankle joint powers in the involved limb during all tasks. Interestingly, only jogging and hopping demonstrated greater knee joint loads when compared with the uninvolved limb. Concentric knee power was greater during jogging (LSI: 117.2%) and hopping (LSI: 115.9%) compared with the uninvolved limb. Similarly, peak patellofemoral joint stress was greater in the involved limb during jogging (LSI: 107.5%) and hopping (LSI: 107.1%), while only hopping had a greater loading rate of patellofemoral joint stress (LSI: 110.9%).

CONCLUSION

Considerable side-to-side deficits in plantarflexor function were observed during walking, jogging, and hopping in patients after an Achilles tendon rupture. As a possible compensation, increased knee joint loads were present but only during jogging and hopping.

CLINICAL RELEVANCE

These data suggest that after an Achilles tendon rupture, patients may be susceptible to greater mechanical loading of the knee during sporting tasks, regardless of surgical or nonsurgical treatment.

Morphomechanical alterations in the medial gastrocnemius muscle in patients with a repaired Achilles tendon: Associations with outcome measures

BACKGROUND

Functional deficits are found in ankles that have sustained an Achilles rupture. This study sought to evaluate and compare the morphomechanical characteristics of the medial gastrocnemius muscle in the legs of participants within six months of a unilateral Achilles repair to determine any correlations between those characteristics and objective outcomes and self-reported functional levels.

METHODS

Fifteen participants were assessed via measurements of muscle morphologies (fascicle length, pennation angle, and muscle thickness) in a resting state, the mechanical properties of the proximal aponeurosis of the medial gastrocnemius muscle, the pennation angle during ramping maximal voluntary isometric contractions (MVIC), the heel raise test, and the Taiwan Chinese version of the Lower Extremity Functional Scale (LEFS-TC) questionnaire. Findings Compared with the non-injured legs, the repaired legs showed a lower muscle fascicle length (mean 4.4 vs. 5.0cm) and thickness (1.7 vs. 1.9cm), lower stiffness of the GM tendon and aponeurosis (174.1 vs. 375.6N/mm), and a greater GM pennation angle (31.2 vs. 28.9°) during 90% MVIC (all p≤0.05). Correlations were found between the morphomechanical results and maximal heel raise heights or the LEFS-TC score, and between the symmetry ratios of the fascicle lengths and the LEFS-TC score. Interpretation There are decreases in fascicle length, muscle thickness and mechanical properties in the medial gastrocnemius muscles of the participants within the first six months after an Achilles repair. These morphomechanical alterations demonstrate associations with functional levels in the lower extremities and indicated the need for early mobilization of the calf muscles after the repair.

Medial Gastrocnemius Myotendinous Junction Displacement and Plantar-Flexion Strength in Patients Treated With Immediate Rehabilitation After Achilles Tendon Repair

CONTEXT

Pathologic plantar flexion frequently occurs after operative repair of the Achilles tendon (AT) because of immobilization and non-weight bearing in the first weeks of traditional rehabilitation. Novel rehabilitation strategies that apply mobilization and weight bearing have been proposed, but their effects on medial gastrocnemius myotendinous junction displacement (MJD) and isometric plantar-flexion strength (PFS) are unknown.

OBJECTIVE

To compare the effects of 12 weeks of immediate versus traditional rehabilitation on MJD and PFS in patients with percutaneous AT repair and to compare AT rupture scores (ATRSs) during follow-up.

DESIGN

Controlled laboratory study.

SETTING

Human performance laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 26 amateur soccer players (age = 42.3 ± 9.7 years, body mass index = 29.5 ± 3.9 kg/m²) with percutaneous AT repair.

INTERVENTION(S)

Athletes were randomly divided into 2 groups: an immediate group, given physical therapy from day 1 to day 84, and a traditional group, given physical therapy from day 29 to day 84. We used repeated-measures analysis of variance to compare the data.

MAIN OUTCOME MEASURE(S)

We measured MJD and PFS at days 28 (fourth week), 56 (eighth week), and 84 (12th week) after AT repair.

RESULTS

After 12 weeks of rehabilitation, we observed a large clinically meaningful effect and statistical difference between groups. At day 28, the immediate group showed higher values for PFS (P = .002), MJD (P = .02), and ATRS (P = .002) than the traditional group. At day 56, the immediate group presented higher values for MJD (P = .02) and ATRS (P = .009). At day 84, the immediate group registered more MJD (P = .001).

CONCLUSIONS

Compared with traditional rehabilitation, 12 weeks of immediate rehabilitation after percutaneous AT repair resulted in better MJD, PFS, and ATRS after 4 weeks; better MJD and ATRS after 8 weeks; and better MJD after 12 weeks.

Characteristics of Intratendinous Microcirculation Shortly After an Achilles Rupture and Subsequent Treatment Outcomes

BACKGROUND

Early microcirculatory responses after experimental tenotomy are critical to the healing of tendons and their ultimate tensile strength. The effects of changes in microcirculation on the outcomes of tendon healing, however, have not been determined.

OBJECTIVES

To assess microcirculation values in injured Achilles tendons in the first 3 months after surgical repair and to correlate the inter-limb microcirculatory changes with functional outcomes at 3 and 6 months after surgery.

DESIGN

Case-control study.

SETTING

A university sports physiotherapy laboratory.

PARTICIPANTS

Thirteen subjects (median age: 45 years; range: 34.8-51.9 years) with a repaired Achilles tendon were recruited.

METHODS OR INTERVENTION

Surgical repair.

MAIN OUTCOME MEASUREMENTS

Measurements were obtained at 1, 2, 3, and 6 months after surgery. Bilateral measurements of tendon microcirculation (total hemoglobin [THb] and oxygen saturation [StO₂]) were recorded at the first 3 time points, whereas outcome measures of a Taiwan Chinese version of the Victorian Institute of Sport Assessment Scale-Achilles questionnaire, one-leg hopping distance, the star excursion balance test, and the heel raise index were conducted at the third and fourth time points. Correlations between the inter-limb microcirculatory changes, eg, between the measurements at 2 months and 1 month (2-1) after surgery, at 3 months and 2 months (3-2) after surgery, and at 3 months and 1 month (3-1) after surgery, and the outcome measures were investigated.

RESULTS

Compared with the noninjured tendons, the repaired Achilles demonstrated greater THb (at 1, 2, and 3 months; P = .017, .008, and .012 respectively) and StO₂ (at 3 months; P = .017). Furthermore, the THb2-1 and THb3-2, StO₂ 2-1, and StO₂ 3-2 showed correlations with the heel raise index, differences in the star excursion balance test and one-leg hopping distance between the noninjured leg and injured leg, and Taiwan Chinese version of the Victorian Institute of Sport Assessment Scale-Achilles questionnaire scores (rho -0.921 to 0.855).

CONCLUSIONS

Changes in the inter-limb microcirculation shortly after Achilles repair were correlated with subsequent symptoms and functional symmetry.

LEVEL OF EVIDENCE

III.

Prospective randomized clinical trial of aggressive rehabilitation after acute Achilles tendon ruptures repaired with Dresden technique

BACKGROUND

Rupture of the Achilles tendon is a common injury during working years. Aggressive rehabilitation may provide better outcomes, but also a greater chance of re-rupture.

OBJECTIVE

To determine if aggressive rehabilitation has better clinical outcomes for Achilles tendon function, Triceps surae function, one-leg heel rise capacity and lower complication rate during twelve weeks after percutaneous Achilles tendon repair compared to conventional rehabilitation.

DESIGN

Randomized controlled trial.

METHOD

Thirty-nine patients were prospectively randomized. The aggressive group (n=20, 41.4 ± 8.3 years) received rehabilitation from the first day after surgery. The conventional group (n=19, 41.7 ± 10.7 years) rested for 28 days, before rehabilitation started. The statistical parameters were the Achilles tendon rupture score (ATRS), verbal pain scale, time to return to work, pain medication consumption, Achilles tendon strength, dorsiflexion range of motion (RoM), injured-leg calf circumference, calf circumference difference, one-leg heel rise repetition and difference, re-rupture rate, strength deficit rate, and other complication rates. Mixed-ANOVA and Bonferroni's post hoc test were performed for multiple comparisons. Student's t-test was performed for parameters measured on the 12th week.

RESULTS

The aggressive group with respect to the conventional group had a higher ATRS; lower verbal pain score; lower pain medication consumption; early return to work; higher Achilles tendon strength; higher one-leg heel rise repetitions; and lower one-leg heel rise difference. The re-rupture rate was 5% and 5%, the strength deficit rate was 42% and 5%, and other complications rate was 11% and 15% in the conventional and aggressive group, respectively.

CONCLUSION

Patients with Dresden repair and aggressive rehabilitation have better clinical outcomes, Achilles tendon function and one-leg heel rise capacity without increasing the postoperative complications rate after 12 weeks compared to rehabilitation with immobilization and non-weight-bearing during the first 28 days after surgery.

Neuromechanical characteristics in the knees of patients who had primary conservative treatment for a torn cruciate ligament and reconstruction afterward

BACKGROUND/PURPOSE

To compare the neuromechanical characteristics and subjective outcomes for knees of patients with a cruciate ligament tear and reconstruction with those for knees of controls at three time intervals, and to determine correlations between the characteristics and subjective outcomes.

METHODS

Ten participants with a cruciate ligament tear and at least a 12-week conservative treatment prior to ligament reconstruction were prospectively measured prior to and 3 months and 6 months after surgery. Ten healthy individuals were recruited as controls. Questionnaire surveys regarding the injured knee were conducted, as were bilateral measurements of root mean square electromyography (EMG), the rate of EMG rise, the median frequency in the vastus medialis of the quadriceps muscles and antagonist coactivation from the semitendinosus muscle, and force capacities, including peak torque, rate of force development, and total works of the knee extension. Correlations between the EMG variables (of the vastus medialis and semitendinosus) and the force capacities, and between the EMG variables and the knee injury and osteoarthritis outcome scores (KOOS), and between force capacities and the KOOS were assessed in the participants with a ligament reconstruction.

RESULTS

Pre- and postoperative results of EMG variable and force capacities were lower in both knees of the experimental group participants than in the control group participants (all p < 0.05). Correlations between EMG and force capacities, and between these parameters and the KOOS were found.

CONCLUSION

There were bilateral neuromechanical defects in the knees of the participants who had undergone conservative treatment as well as reconstruction after a cruciate ligament tear.

Increased patellar tendon microcirculation and reduction of tendon stiffness following knee extension eccentric exercises

STUDY DESIGN

Controlled laboratory study.

OBJECTIVES

To measure and compare patellar tendon stiffness and microcirculation in college tennis players and nonathletic students when performing eccentric knee extension exercises that do and do not reduce tendon stiffness.

BACKGROUND

Previous studies suggest that tendon microcirculation response during exercises may vary based on the tendon's plastic properties. Methods The study included 3 groups of college-age male students: tennis players who performed 4 sets of either 40 (n = 12) or 80 (n = 13) repetitions of eccentric knee extension exercise and nonathletic students (n = 14) who performed 4 sets of 40 repetitions. Tendon stiffness was measured before and after exercise completion. Changes in total hemoglobin and oxygen saturation (OSat) were analyzed while performing the 4 sets. Comparisons were made within and between the groups. The level of association between tendon microcirculation and stiffness reduction was assessed.

RESULTS

The 2 groups (player/4 × 80 and student/4 × 40) exhibiting patellar tendon stiffness reductions (P<.008) showed higher total hemoglobin and OSat levels, above the pre-exercise levels, in the fourth set compared to the first set of exercises (P<.004). The tennis players who performed 4 sets of 40 repetitions exhibited higher OSat levels in the fourth set than in the first set (P = .004) but had no reduction in tendon stiffness. Changes in OSat levels in the fourth set were correlated with patellar tendon stiffness reductions (r = -0.381, P = .02).

CONCLUSION

We conclude that there was increased patellar tendon microcirculation after performing knee extension eccentric exercises that resulted in a reduction in tendon stiffness.