Long-term biomechanical outcomes after Achilles tendon ruptures

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.

Do the heel-rise test and isometric strength improve after Achilles tendon repair using Dresden technique?

BACKGROUND

Achilles' tendon ruptures result in impaired plantar flexion strength and endurance. It is interesting to know the plantar flexion strength, the number of heel-rise repetitions, and the maximal calf circumference following Achilles' tendon ruptures repair.

METHODS

Both the injured and non-injured legs of thirty male patients with Achilles' tendon ruptures treated with the percutaneous Dresden technique were compared with the ankle function of 30 healthy participants. Rehabilitation involved partial weight-bearing for three weeks and then increased to full weight-bearing and ankle exercises.

RESULTS

The injured legs had weaker plantar flexion strength (1.64 ± 0.17 Nm/kg) compared with the non-injured legs (1.91 ± 0.24 Nm/kg; p = 0.002) and the healthy participants' legs (1.93 ± 0.32 Nm/kg; p < 0.001). The non-injured leg had greater ability in doing heel-rise repetitions (39.4 ± 6.1 rep.) compared with the injured legs (37.2 ± 5.7 rep.; p < 0.023) and the healthy participants' legs (31.0 ± 13.0 rep.; p < 0.001).

CONCLUSIONS

The injured leg had not recovered full isometric strength but had improved heel-rise repetition.

Check-rein technique for Achilles tendon elongation following conservative management for acute Achilles tendon ruptures: a two-year prospective clinical study

Background

Following conservative management for acute Achilles tendon (AT) ruptures, the tendon may heal in continuity, and some patients may present with an elongated Achilles tendon–gastrosoleus complex. This study investigated the efficacy and feasibility of a novel minimally invasive technique, which we named “check-rein procedure”, in patients with intact and elongated AT following conservative management for AT ruptures.

Methods

All patients who underwent the check-rein procedure for elongation of the gastrosoleus–AT complex by one experienced surgeon were prospectively enrolled. The AT resting angle (ATRA) and AT rupture score (ATRS) were assessed at baseline and repeated at 2-year follow-up, as were calf circumference and isometric plantarflexion strength of both ankles.

Results

Forty-three patients (43 procedures) were analysed. The mean time elapsed from injury to surgery was 28.7 ± 7.9 weeks. The mean age at surgery was 38.5 ± 5.7 years. At the last follow-up, ATRS, ATRA, isometric strength difference, and calf circumference of the affected side were increased (P < 0.0001). The rate of the return to sport was 98% (42 of 43). No wound complications or rupture were experienced by any patient.

Conclusion

The check-rein technique for AT elongation after conservative management of AT tears is effective and feasible to restore tendon length and calf function. The surgical outcome was influenced by the preoperative performance status, and longer time elapsed from injury to surgery worsens the outcomes.

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.

Open versus minimally-invasive surgery for Achilles tendon rupture: a meta-analysis study

INTRODUCTION

Despite the presence of various different surgical procedures, the preferable technique for repair of acute Achilles tendon ruptures is unknown and, therefore, object of discussions. The purpose of this meta-analysis was to compare clinical outcomes and complication-rates between the minimally invasive and the standard open repair of acute Achilles tendon ruptures.

MATERIALS AND METHODS

This meta-analysis was performed according to the PRISMA guidelines. In September 2019 the main databases were accessed. All clinical trials of evidence level I to III comparing minimally invasive vs. open surgery of Achilles tendon rupture were included in the present study. Only articles reporting quantitative data under the outcomes of interest were included. Missing data under the outcomes of interest warranted the exclusion from the present work. For the statistical analysis we referred to the Review Manager Software Version 5.3. (The Nordic Cochrane Centre, Copenhagen). Continuous data were analysed through the inverse variance method. For the effect estimate the mean difference was used. Dichotomous data were analysed through the Mante-Haenszel method via odd ratio effect measure. The confidence interval was set at 95% in all the comparisons. Values of P < 0.05 were considered statistically significant.

RESULTS

A total of 25 articles were included for meta-analysis. The funnel plot revealed poor data dispersion, attesting to this study a low risk of publication bias. The quality of the methodological assessment was moderate. Data from 2223 (1055 open, 1168 minimally invasive) surgical procedures were extracted. The mean follow-up was of 24.29 ± 22.4 months. The open group reported a lower value of post-operative palpable knot at last follow-up and a lower rate of sural nerve palsy. In the minimally-invasive group a shorter surgery duration and a lower rate of post-operative wound necrosis and reduced risk of wound scarring and adhesions has been evidenced. The minimally-invasive cohort detected the lowest values of superficial and deep infections. In both groups no significant difference was shown in re-rupture rate.

CONCLUSIONS

Compared to the minimally-invasive Achilles tendon reconstruction, the open procedure evidenced a lower rate of sural nerve palsy and postoperative palpable knot, whereas in the minimally-invasive reconstruction group quicker surgery duration, a lower rate of post-operative wound necrosis, superficial and deep infections and less scar tissue adhesions could be observed. No relevant discrepancies were detected among the two techniques in terms of post-operative re-rupture.

Fit to Burst: Toward Noninvasive Estimation of Achilles Tendon Load Using Burst Vibrations

OBJECTIVE

Tendons are essential components of the musculoskeletal system and, as with any mechanical structure, can fail under load. Tendon injuries are common and can be debilitating, and research suggests that a better understanding of their loading conditions could help mitigate injury risk and improve rehabilitation. To that end, we present a novel method of noninvasively assessing parameters related to mechanical load in the Achilles tendon using burst vibrations.

METHODS

These vibrations, produced by a small vibration motor on the skin superficial to the tendon, are sensed by a skin-mounted accelerometer, which measures the tendon's response to burst excitation under varying tensile load. In this study, twelve healthy subjects performed a variety of everyday tasks designed to expose the Achilles tendon to a range of loading conditions. To approximate the vibration motor-tendon system and provide an explanation for observed changes in tendon response, a 2-degree-of-freedom mechanical systems model was developed.

RESULTS

Reliable, characteristic changes in the burst response profile as a function of Achilles tendon tension were observed during all loading tasks. Using a machine learning-based approach, we developed a regression model capable of accurately estimating net ankle moment-which captures general trends in tendon tension-across a range of walking speeds and across subjects (R² = 0.85). Simulated results of the mechanical model accurately recreated behaviors observed in vivo. Finally, preliminary, proof-of-concept results from a fully wearable system demonstrated trends similar to those observed in experiments conducted using benchtop equipment.

CONCLUSION

These findings suggest that an untethered, unobtrusive system can effectively assess tendon loading during activities of daily life.

SIGNIFICANCE

Access to such a system would have broad implications for injury recovery and prevention, athletic training, and the study of human movement.

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.

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.

Strength Measurement After Achilles Tendon Repair

The goal of treatment after Achilles tendon rupture (ATR) is to restore appropriate tension to the tendon, so that normal baseline strength and functional soft-tissue length can be achieved. The assessment of plantarflexion strength has shown widespread variability. The purpose of this study is to document variations in strength assessment after the treatment of ATR in the literature. A comprehensive literature review was performed. In total, 2758 articles were found on Achilles tendon rupture and Achilles tendon strength measurement. The full text of articles including strength as a functional outcome measurement in the abstract were assessed. All objective strength measurements performed were reviewed and recorded for comparison. One-hundred articles were included in our study. In 78 articles, a dynamometer was used to measure strength, whereas in 22 articles, an endurance test (n=14) or formal gait assessment (n=8) was applied. When a dynamometer was used, there was wide variability in the various methods used including the incorporation of both isokinetic (n = 65) and isometric (n = 29) exercises utilizing varying degrees of knee flexion and patient testing position. Furthermore, the number of measurements at certain angular velocities varied. This study illustrates that no general consensus exists regarding an optimal method for measuring strength after ATR. The variability creates difficulty and challenges medical professionals' ability to formulate consistent conclusions when determining functional performance outcomes. A more uniform way of measuring strength after ATR may allow for better comparisons between studies in the literature, potentially leading to a better understanding of strength. Levels of Evidence: Therapeutic, Level II.

Stem Cell Therapy for Tendon Regeneration: Current Status and Future Directions

In adults the healing tendon generates fibrovascular scar tissue and recovers never histologically, mechanically, and functionally which leads to chronic and to degenerative diseases. In this review, the processes and mechanisms of tendon development and fetal regeneration in comparison to adult defect repair and degeneration are discussed in relation to regenerative therapeutic options. We focused on the application of stem cells, growth factors, transcription factors, and gene therapy in tendon injury therapies in order to intervene the scarring process and to induce functional regeneration of the lesioned tissue. Outlines for future therapeutic approaches for tendon injuries will be provided.

Early weight-bearing in nonoperative treatment of acute Achilles tendon rupture did not influence mid-term outcome: a blinded, randomised controlled trial

PURPOSE

Acute Achilles tendon rupture leads to impaired outcome at short term, but little is known concerning medium-term results. The aim of the present study was to investigate the influence of early weight-bearing on clinical outcome 4.5 years after nonoperative treatment of acute Achilles tendon rupture.

METHOD

The study was performed as a medium-term follow-up on patients included in a randomised controlled trial. Both groups were treated with nonoperative management and controlled early motion. The intervention group was allowed full weight-bearing from day 1, and the control group was non-weight-bearing for 6 weeks. 60 patients were randomised 1:1. Of those, 56 were eligible for inclusion in the medium-term follow-up and 37 participated (18 control, 19 intervention). The outcomes were Achilles tendon Total Rupture Score (ATRS) and heel raise work performed at an average of 4.5 years after the initial injury. Statistical analysis was performed using paired t tests and linear regression.

RESULTS

No differences were found between control and intervention groups at 4.5 years. ATRS scores consistently improved in both the intervention and the control groups from 0.5 to 1 year and from 1 to 4.5 years, ending up at 80.5 on average after 4.5 years. Heel raise height kept improving from 0.5 to 4.5 years, reaching a limb symmetry index of 82.4%. The heel raise work improvement from 0.5 to 1 year did not continue. No significant change was found from 1 to 4.5 years, ending at a limb symmetry index of 60%.

CONCLUSION

Early weight-bearing did not influence outcome 4.5 years after nonoperative treatment of acute Achilles tendon rupture. The calf muscle of the injured limb performs 40% less work, when compared to the healthy limb, though lifting height recovers better.

LEVEL OF EVIDENCE

II.

CLINICAL TRIALS IDENTIFIER

NCT02760784.

Alterations in structure of the muscle-tendon unit and gait pattern after percutaneous repair of Achilles tendon rupture with the Dresden instrument

BACKGROUND

Functional deficits after Achilles tendon (AT) ruptures are observed. The relationship between musculotendinous structural alterations and functional outcome is not clear.

METHODS

Kinematic analyses (level walking, stair climbing), patient-reported outcome measures (PROMs), calf atrophy (maximum calf circumference (MCC)), and AT length were evaluated in patients after percutaneous AT repair with the Dresden instrument (n=20min.

FOLLOW-UP

24 months).

RESULTS

Patients achieved good results in PROMs. However, MCC decreased significantly and AT length increased significantly postoperatively. Side-to-side MCC differences over 2cm resulted in significantly lower PROMs. AT lengthening correlated with increased dorsiflexion and decreased plantarflexion.

CONCLUSION

Calf atrophy and AT lengthening after minimally invasive AT repair resulted in inferior ankle kinematics and PROMs.

Non-operative functional treatment for acute Achilles tendon ruptures: The Leicester Achilles Management Protocol (LAMP)

OBJECTIVES

The purpose of this study is to present outcomes and objective measures of assessment for acute Achilles tendon (AT) ruptures treated with an eight-week functional dynamic treatment protocol in a VACOped^® boot with immediate full weight bearing mobilisation, the Leicester Achilles Management Protocol (LAMP).

METHODS

A prospective study of all patients treated with the LAMP with minimum 12-month follow-up was performed. Patients completed the Achilles Tendon Rupture Score (ATRS) and in the latter part of the study, objective measures of the calf muscle girth and heel raise height were obtained.

RESULTS

442 patients were treated with the LAMP. There were nine (2%) re-ruptures in the 442 non-operative treated group of patients throughout the study period. ATRS at twelve months or more were available in 234 patients and objective measures in 77 patients. The mean age was 50 years. The mean ATRS was 75.5 at an average of 23 months post injury. Men had a statistically significant higher ATRS score when compared to women (p < 0.05). There was statistically significant difference in the calf muscle girth and the heel raise height when compared to the uninjured side at 12-months post-injury (p < 0.05). These differences did not correlate with the ATRS (p > 0.05).

CONCLUSIONS

The LAMP is a simple yet effective regime for the non-operative treatment of acute AT ruptures, which can be universally adopted without the need for many resources. Compared to other studies, the overall time in the boot is less with low complication rates and similar patient reported outcomes.

Surveying the management of Achilles tendon ruptures in the Netherlands: lack of consensus and need for treatment guidelines

PURPOSE

This study aimed to describe and analyse usual care of Achilles tendon ruptures (ATRs) by orthopaedic surgeons and trauma surgeons in the Netherlands.

METHODS

A nationwide online survey of ATR management was sent to all consultant orthopaedic and trauma surgeons in the Netherlands, requesting participation of those involved in ATR management. Data on individual characteristics and the entire ATR management (from diagnosis to rehabilitation) were gathered. Consensus was defined as ≥ 70% agreement on an answer.

RESULTS

A total of 91 responses (70 orthopaedic surgeons and 21 trauma surgeons) were analysed. There was consensus on the importance of the physical examination in terms of diagnosis (> 90%) and a lack of consensus on diagnostic imaging (ultrasound/MRI). There was consensus that non-surgical treatment is preferred for sedentary and systemically diseased patients and surgery for patients who are younger and athletic and present with larger tendon gap sizes. There was consensus on most of the non-surgical methods used: initial immobilisation in plaster cast with the foot in equinus position (90%) and its gradual regression (82%) every 2 weeks (85%). Only length of immobilisation lacked consensus. Surgery was generally preferred, but there was a lack of consensus on the entire followed protocol. Orthopaedic and trauma surgeons differed significantly on their surgical (p = 0.001) and suturing techniques (p = 0.002) and methods of postoperative immobilisation (p < 0.001). Orthopaedic surgeons employed open repair and Bunnell sutures more often, whereas trauma surgeons used minimally invasive approaches and bone anchors. Rehabilitation methods and advised time until weight-bearing and return to sport varied. Orthopaedic surgeons advised a significantly longer time until return to sport after both non-surgical treatment (p = 0.001) and surgery (p = 0.002) than trauma surgeons.

CONCLUSION

This is the first study to describe the entire ATR management. The results show a lack of consensus and wide variation in management of ATRs in the Netherlands. This study shows that especially the methods of the perioperative and rehabilitation phases were inconclusive and differed between orthopaedic and trauma surgeons. Further research into optimal ATR management regimens is recommended. In addition, to achieve uniformity in management more multidisciplinary collaboration between Dutch and international surgeons treating ATRs is needed.

LEVEL OF EVIDENCE

Cross-sectional survey, Level V.

Functional outcome and complication rate after percutaneous suture of fresh Achilles tendon ruptures with the Dresden instrument

Background

The aim of this study was to evaluate the outcome of patients with a rupture of the Achilles tendon (ATR) treated percutaneously with the Dresden instrument in the hands of surgeons others than its inventors.

Materials and methods

118 patients (FU rate: 77.1%) with an acute ATR treated with the Dresden instrument were retrospectively evaluated. The following data were evaluated: pain intensity, functional limitation, Hannover score, Achilles tendon total rupture score (ATRS), AOFAS ankle-hindfoot score, Tegner activity score, complications, maximum calf circumference (MCC) on both sides, and the Matles test for tendon lengthening. The effect of the time point of the surgery after trauma was examined.

Results

Hannover scores and ATRSs were good; AOFAS scores were excellent. Almost all patients returned to sporting activities postoperatively, and 66.1% were able to return to their previous level. The Tegner activity score revealed a slight posttraumatic decrease (p = 0.009) in the level of physical activity overall (pre-injury: 5.37 ± 0.15; postoperatively: 4.77 ± 0.15). The re-rupture rate was 2%. No sural nerve lesions and no infections were reported. Even after 3 years, there was still a difference in MCC that was correlated with inferior clinical score and AT lengthening. Patients treated within the first 2 days after ATR showed inferior clinical outcomes in terms of AOFAS score, ATRS, and functional limitations.

Conclusions

Percutaneous ATR suture with the Dresden instrument is a safe and reliable method. Low complication and re-rupture rates, good clinical results, and a high rate of return to play support this fact. The time point of the operation may influence the outcome.

The Ruptured Achilles Tendon Elongates for 6 Months After Surgical Repair Regardless of Early or Late Weightbearing in Combination With Ankle Mobilization: A Randomized Clinical Trial

BACKGROUND

Treatment strategies for Achilles tendon rupture vary considerably, and clinical outcome may depend on the magnitude of tendon elongation after surgical repair. The aim of this project was to examine whether tendon elongation, mechanical properties, and functional outcomes during rehabilitation of surgically repaired acute Achilles tendon ruptures were influenced by different rehabilitation regimens during the early postsurgical period.

HYPOTHESIS

Restricted early weightbearing that permits only limited motion about the ankle in the early phase of tendon healing limits tendon elongation and improves functional outcome.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

75 consecutive patients with an acute Achilles tendon rupture were included. They underwent surgical repair, and tantalum beads were placed in the distal and proximal parts of the tendon; thereafter, the patients were randomized into 3 groups. The first group was completely restricted from weightbearing until week 7. The second group was completely restricted from weightbearing until week 7 but performed ankle joint mobilization exercises. The first and second groups were allowed full weightbearing after week 8. The third group was allowed partial weightbearing from day 1 and full weightbearing from week 5. All patients received the same instructions in home exercise guidelines starting from week 9.

RESULTS

The rehabilitation regimen in the initial 8 weeks did not significantly influence any of the measured outcomes including tendon elongation. Achilles tendon elongation and tendon compliance continued for up to 6 months after surgery, and muscle strength, muscle endurance, and patient-reported functional scores did not reach normal values at 12 months.

CONCLUSION

Differences in rehabilitation loading pattern in the initial 8 weeks after the repair of an Achilles tendon rupture did not measurably alter the outcome. The time to recover full function after an Achilles tendon rupture is at least 12 months. Registration: NCT02422004 ( ClinicalTrials.gov identifier).

Outcome after operative treatment for chronic versus acute Achilles tendon rupture - A comparative analysis

BACKGROUND

This study compared outcomes after treatment of acute Achilles tendon (AT) rupture via percutaneous suturing, with those after chronic AT rupture treated via open reconstruction.

METHODS

This retrospective study included 30 patients who underwent either percutaneous suturing for acute AT rupture (group AR, n=16) or open reconstruction for chronic AT rupture (group CR, n=14). Function was evaluated by calf muscle circumference, and endurance through isokinetic measurement and single-leg heel-rise test. Score evaluation included AT Total Rupture Score, Victorian Institute of Sports Assessment-Achilles questionnaire, and visual analogue scale pain score. Postoperative tendon thickness was measured using ultrasonography and MRI.

RESULTS

Follow-up was conducted 4.97±1.79 years postoperatively. The groups were similar in age and body mass index. There was no significant difference between groups in calf circumference, isokinetic measurement, heel-rise test, and score evaluation. There was significantly less mediolateral tendon thickening in group AR compared with group CR on ultrasonography (p=0.01) and MRI (p=0.001).

CONCLUSIONS

Open reconstruction for chronic AT rupture may result in comparable clinical and functional outcomes, but a thicker tendon compared with percutaneous suturing after acute AT rupture.

Functional Outcome of Acute Achilles Tendon Rupture With and Without Operative Treatment Using Identical Functional Bracing Protocol

BACKGROUND

The purpose of this study was to compare the functional results of operative and nonoperative treatment of acute Achilles tendon rupture using an identical rehabilitation program of functional bracing.

METHODS

Over a 10-year period, 200 patients (99 operative, 101 nonoperative) aged between 18 and 65 years were treated at our institution's physiotherapy department after acute Achilles tendon rupture. There were 132 patients (62 operative, 70 nonoperative) available for a minimum 2-year follow-up (average 6.5 years; range, 2-13 years). Functional outcome was assessed using the Achilles tendon total rupture score (ATRS).

RESULTS

With the numbers available, no significant difference could be detected in ATRS between operative (mean 84.8, median 90) and nonoperative groups (mean 85.3, median 91; P = 0.55). No significant difference could be detected in ATRS between male and female patients however treated ( P = 0.30) or between patients younger and older than 40 years at time of injury ( P = 0.68). There was no correlation between ATRS score and age at injury in all patients (ρ = -0.0168, P = 0.85). In male patients, there was a weak trend with older patients at follow-up having better scores (ρ = 0.21, P = 0.069). However, among female patients, there was a significant negative correlation between ATRS scores and increasing age (ρ = -0.29, P = 0.03). Logistic regression analysis failed to show any significant effect of age at rupture, gender, or mode of treatment on ATRS.

CONCLUSIONS

This study showed no significant difference detectable in ATRS between operative and nonoperative patients in the treatment of acute Achilles tendon ruptures using an identical rehabilitation program with functional bracing.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

5-year results of the 1.5cm incision Achilles tendon repair

BACKGROUND

To study a hypothesis that the cost-effective 1.5cm medial incision Achilles tendon repair technique will provide good functional outcomes which are maintained for over 5 years.

METHOD

Prospective study of 12 consecutive cases with a minimal 5-year follow-up were recruited from April 2008 to November 2010. Cases whom were mentally incompetent or those which required concomitant procedures were excluded. Outcomes measures included the numeric pain rating scale, motor power strength, range of motion, functional scoring using the AOFAS hindfoot score and patient's self-assessment using the Foot and Ankle Outcome Score (FAOS).

RESULT

No re-ruptures or sural nerve injured were identified after a minimal 5-year follow-up. Pain was minimal at 0.5/10, calf power was 5/5 and ankle range was good (plantarflexion: 38°/dorsiflexion: 21°). The AOFAS hindfoot score was 97.4 and all 5 sub-categories of the Foot and Ankle Outcome Score (FAOS) were good.

CONCLUSION

The 1.5cm medial incision repair of the Achilles tendon is an economically sound surgical technique, with minimal complications, which gives good medium length functional outcomes.

LEVEL OF EVIDENCE

IV.

Tendon Length, Calf Muscle Atrophy, and Strength Deficit After Acute Achilles Tendon Rupture: Long-Term Follow-up of Patients in a Previous Study

BACKGROUND

In this prospective study, we used magnetic resonance imaging (MRI) to assess long-term Achilles tendon length, calf muscle volume, and muscle fatty degeneration after surgery for acute Achilles tendon rupture.

METHODS

From 1998 to 2001, 60 patients at our center underwent surgery for acute Achilles tendon rupture followed by early functional postoperative rehabilitation. Fifty-five patients were reexamined after a minimum duration of follow-up of 13 years (mean, 14 years), and 52 of them were included in the present study. Outcome measures included Achilles tendon length, calf muscle volume, and fatty degeneration measured with MRI of both the affected and the uninjured leg. The isokinetic plantar flexion strength of both calves was measured and was correlated with the structural findings.

RESULTS

The Achilles tendon was, on average, 12 mm (95% confidence interval [CI] = 8.6 to 15.6 mm; p < 0.001) longer (6% longer) in the affected leg than in the uninjured leg. The mean volumes of the soleus and medial and lateral gastrocnemius muscles were 63 cm (13%; p < 0.001), 30 cm (13%; p < 0.001), and 16 cm (11%; p < 0.001) lower in the affected leg than in the uninjured leg, whereas the mean volume of the flexor hallucis longus (FHL) was 5 cm (5%; p = 0.002) greater in the affected leg, indicating FHL compensatory hypertrophy. The median plantar flexion strength for the whole range of motion ranged from 12% to 18% less than that on the uninjured side. Finally, the side-to-side difference in Achilles tendon length correlated substantially with the strength deficit (ρ = 0.51, p < 0.001) and with medial gastrocnemius (ρ = 0.46, p = 0.001) and soleus (ρ = 0.42, p = 0.002) muscle atrophy.

CONCLUSIONS

Increased Achilles tendon length is associated with smaller calf muscle volumes and persistent plantar flexion strength deficits after surgical repair of Achilles tendon rupture. Strength deficits and muscle volume deficits are partly compensated for by FHL hypertrophy, but 11% to 13% deficits in soleus and gastrocnemius muscle volumes and 12% to 18% deficits in plantar flexion strength persist even after long-term follow-up.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical Head-to-Head Comparison of 2 Sutures and the Giftbox Versus Bunnell Techniques for Midsubstance Achilles Tendon Ruptures

Background:

Acute midsubstance Achilles tendon ruptures are a common orthopaedic problem for which the optimal repair technique and suture type remain controversial. Head-to-head comparisons of current fixation constructs are needed to establish which stitch/suture combination is most biomechanically favorable.

Hypothesis:

Of the tested fixation constructs, Giftbox repairs with Fiberwire will exhibit superior stiffness and strength during biomechanical testing.

Study Design:

Controlled laboratory study.

Methods:

Two biomechanical trials were performed, isolating stitch technique and suture type, respectively. In trial 1, 12 transected fresh-frozen cadaveric Achilles tendon pairs were randomized to receive either the Giftbox-modified Krackow or the Bunnell stitch with No. 2 Fiberwire suture. Each repair underwent cyclic loading, oscillating between 10 and 100 N at 2 Hz for 1000 cycles, with repair gapping measured at 500 and 1000 cycles. Load-to-failure testing was then performed, and clinical and catastrophic failure values were recorded. In trial 2, 10 additional paired cadaveric Achilles tendons were randomized to receive a Giftbox repair with either No. 2 Fiberwire or No. 2 Ultrabraid. Testing and data collections protocols in trial 2 replicated those used in trial 1.

Results:

In trial 1, the Bunnell group had 2 failures during cyclic loading while the Giftbox had no failures. The mean tendon gapping after cyclic loading was significantly lower in the Giftbox repairs (0.13 vs 2.29 mm, P = .02). Giftbox repairs were significantly stiffer than Bunnell (47.5 vs 38.7 N/mm, P = .019) and showed more tendon elongation (5.9 ± 0.8 vs 4.5 ± 1.0 mm, P = .012) after 1000 cycles. Mean clinical load to failure was significantly higher for Giftbox repairs (373 vs 285 N, P = .02), while no significant difference in catastrophic load to failure was observed (mean, 379 vs 336 N; P = .61). In trial 2, there were no failures during cyclic loading. The Giftbox + Fiberwire repairs recorded higher clinical load-to-failure values compared with Giftbox + Ultrabraid (mean, 361 vs 239 N; P = .005). No other biomechanical differences were observed in trial 2.

Conclusion:

Simulated early rehabilitation biomechanical testing showed that Giftbox-modified Krackow Achilles repair technique with Fiberwire suture was stronger and more resistant to gap formation at the repair site than combinations that incorporated the Bunnell stitch or Ultrabraid suture.

Clinical Relevance:

A more in-depth understanding of the biomechanical properties of the Giftbox repair will help inform surgical decision making because stronger repairs are less likely to fail during accelerated postoperative rehabilitation.

Mechanical, histological, and functional properties remain inferior in conservatively treated Achilles tendons in rodents: Long term evaluation

Conservative treatment (non-operative) of Achilles tendon ruptures is suggested to produce equivalent capacity for return to function; however, long term results and the role of return to activity (RTA) for this treatment paradigm remain unclear. Therefore, the objective of this study was to evaluate the long term response of conservatively treated Achilles tendons in rodents with varied RTA. Sprague Dawley rats (n=32) received unilateral blunt transection of the Achilles tendon followed by randomization into groups that returned to activity after 1-week (RTA1) or 3-weeks (RTA3) of limb casting in plantarflexion, before being euthanized at 16-weeks post-injury. Uninjured age-matched control animals were used as a control group (n=10). Limb function, passive joint mechanics, tendon properties (mechanical, histological), and muscle properties (histological, immunohistochemical) were evaluated. Results showed that although hindlimb ground reaction forces and range of motion returned to baseline levels by 16-weeks post-injury regardless of RTA, ankle joint stiffness remained altered. RTA1 and RTA3 groups both exhibited no differences in fatigue properties; however, the secant modulus, hysteresis, and laxity were inferior compared to uninjured age-matched control tendons. Despite these changes, tendons 16-weeks post-injury achieved secant stiffness levels of uninjured tendons. RTA1 and RTA3 groups had no differences in histological properties, but had higher cell numbers compared to control tendons. No changes in gastrocnemius fiber size or type in the superficial or deep regions were detected, except for type 2x fiber fraction. Together, this work highlights RTA-dependent deficits in limb function and tissue-level properties in long-term Achilles tendon and muscle healing.

Soleus Atrophy Is Common After the Nonsurgical Treatment of Acute Achilles Tendon Ruptures: A Randomized Clinical Trial Comparing Surgical and Nonsurgical Functional Treatments

BACKGROUND

It remains controversial whether nonsurgical or surgical treatment provides better calf muscle strength recovery after an acute Achilles tendon rupture (ATR). Recent evidence has suggested that surgery might surpass nonsurgical treatment in restoring strength after an ATR.

PURPOSE

To assess whether magnetic resonance imaging (MRI) findings could explain calf muscle strength deficits and the difference between nonsurgical and surgical treatments in restoring calf muscle strength.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

From 2009 to 2013, 60 patients with acute ATRs were randomized to surgery or nonsurgical treatment with an identical rehabilitation protocol. The primary outcome measure was the volume of calf muscles assessed using MRI at 3 and 18 months. The secondary outcome measures included fatty degeneration of the calf muscles and length of the affected Achilles tendon. Additionally, isokinetic plantarflexion strength was measured in both legs.

RESULTS

At 3 months, the study groups showed no differences in muscle volumes or fatty degeneration. However, at 18 months, the mean differences between affected and healthy soleus muscle volumes were 83.2 cm³ (17.7%) after surgery and 115.5 cm³ (24.8%) after nonsurgical treatment (difference between means, 33.1 cm³; 95% CI, 1.3-65.0; P = .042). The study groups were not substantially different in the volumes or fatty degeneration of other muscles. From 3 to 18 months, compensatory hypertrophy was detected in the flexor hallucis longus (FHL) and deep flexors in both groups. In the nonsurgical treatment group, the mean difference between affected and healthy FHL muscle volumes was -9.3 cm³ (12%) and in the surgical treatment group was -8.4 cm³ (10%) ( P ≤ .001). At 18 months, Achilles tendons were, on average, 19 mm longer in patients treated nonsurgically compared with patients treated surgically ( P < .001). At 18 months, surgically treated patients demonstrated 10% to 18% greater strength results ( P = .037). Calf muscle isokinetic strength deficits for the entire range of ankle motion correlated with soleus atrophy (ρ = 0.449-0.611; P < .001).

CONCLUSION

Treating ATRs nonsurgically with a functional rehabilitation protocol resulted in greater soleus muscle atrophy compared with surgical treatment. The mean Achilles tendon length was 19 mm longer after nonsurgical treatment than after the surgical treatment of ATRs. These structural changes partly explained the 10% to 18% greater calf muscle strength observed in patients treated with surgery compared with those treated nonsurgically. Registration: NCT02012803 ( ClinicalTrials.gov identifier).

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.

Functional outcomes of conservatively managed acute ruptures of the Achilles tendon

AIMS

This prospective cohort study aims to determine if the size of the tendon gap following acute rupture of the Achilles tendon shows an association with the functional outcome following non-operative treatment.

PATIENTS AND METHODS

All patients presenting within two weeks of an acute unilateral rupture of the Achilles tendon between July 2012 and July 2015 were considered for the study. In total, 38 patients (nine female, 29 male, mean age 52 years; 29 to 78) completed the study. Dynamic ultrasound examination was performed to confirm the diagnosis and measure the gap between ruptured tendon ends. Outcome was assessed using dynamometric testing of plantarflexion and the Achilles tendon Total Rupture score (ATRS) six months after the completion of a rehabilitation programme.

RESULTS

Patients with a gap ≥ 10 mm with the ankle in the neutral position had significantly greater peak torque deficit than those with gaps < 10 mm (mean 23.3%; 7% to 52% vs 14.3%; 0% to 47%, p = 0.023). However, there was no difference in ATRS between the two groups (mean score 87.2; 74 to 100 vs 87.4; 68 to 97, p = 0.467). There was no significant correlation between gap size and torque deficit (τ = 0.103), suggesting a non-linear relationship. There was also no significant correlation between ATRS and peak torque deficit (τ = -0.305).

CONCLUSION

This is the first study to identify an association between tendon gap and functional outcome in acute rupture of the Achilles tendon. We have identified 10 mm as a gap size at which deficits in plantarflexion strength become significantly greater, however, the precise relationship between gap size and plantarflexion strength remains unclear. Large, multicentre studies will be needed to clarify this relationship and identify population subgroups in whom deficits in peak torque are reflected in patient-reported outcome measures. Cite this article: Bone Joint J 2017;99-B:87-93.

Outcome evaluation after Achilles tendon ruptures. A review of the literature

The optimal treatment and the best rehabilitation protocol after an acute Achilles tendon rupture (ATR) remain a matter of controversy in orthopaedic and sports medicine. The use of validated injury-specific outcome instruments is the only way to clarify these issues, in order to ensure that patients receive the best possible treatment. This article describes the most commonly reported outcome measures used to assess patients treated for ATR. On the basis of the available evidence, the Achilles tendon Total Rupture Score (ATRS) is the most appropriate outcome measure for evaluating the management of acute ATR.

Augmented Compared with Nonaugmented Surgical Repair After Total Achilles Rupture: Results of a Prospective Randomized Trial with Thirteen or More Years of Follow-up

BACKGROUND

This prospective randomized trial with a mean fourteen-year follow-up compared simple end-to-end repair with fascial flap-augmented repair for acute Achilles tendon ruptures.

METHODS

From 1998 to 2001, sixty patients with acute Achilles tendon rupture were randomized to receive simple end-to-end repair or augmented repair; both groups were treated with postoperative bracing allowing free active plantar flexion. After a follow-up of thirteen years or more, fifty-five patients (twenty-eight in the nonaugmented-repair group and twenty-seven in the augmented-repair group) were reexamined. Outcome measures included the Leppilahti Achilles tendon score, isokinetic plantar flexion strength (peak torque and the work-displacement deficit at 10° intervals over the ankle range of motion), tendon elongation, and the RAND 36-item health survey.

RESULTS

After a mean of fourteen years of follow-up, the mean Leppilahti score was 87.1 points for the nonaugmented repairs and 91.5 points for the augmented repairs, with a mean difference of 4.3 points (95% confidence interval [CI], -0.1 to 8.8 points). The surgical technique did not have an impact on strength parameters, with a mean peak torque of 112.6 Nm after the nonaugmented repairs and 107.3 Nm after the augmented repairs (mean difference, 5.3 Nm [95% CI, -22.2 to 11.6 Nm]) and a median work-displacement deficit of 6.7% to 20.3% after the nonaugmented repairs and 12.8% to 18.0% after the augmented repairs (p = 0.9). Strength did not significantly change between the twelve-month and fourteen-year follow-up examinations. At a mean of fourteen years, the injured side showed a 12.2% to 18.0% median work-displacement deficit compared with the unaffected side (p < 0.001). RAND-36 scores indicated no between-group difference in health domains.

CONCLUSIONS

Augmented repair of total Achilles tendon ruptures provided no advantage over simple end-to-end repair. Achilles tendon ruptures result in a permanent calf muscle strength deficit, but its clinical relevance remains unclear.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Early functional treatment versus cast immobilization in tension after achilles rupture repair: results of a prospective randomized trial with 10 or more years of follow-up

BACKGROUND

There are no long-term prospective controlled trials comparing postoperative regimens after Achilles tendon rupture repair.

PURPOSE

To compare ≥10-year outcomes of 2 postoperative regimens after Achilles tendon rupture repair: early weightbearing with early mobilization versus early weightbearing with early immobilization in tension.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 50 patients with acute Achilles tendon ruptures were randomized postoperatively to receive either early movement of the ankle between neutral and plantar flexion in a brace for 6 weeks (group 1) or Achilles tendon immobilization in tension using a below-knee cast with the ankle in a neutral position for 6 weeks (group 2). Patients were assessed at 3, 6, and 14 months and 11 years postoperatively.

RESULTS

There were 37 patients (74%) evaluated at a mean (±SD) of 11.0 ± 0.9 years. The mean Leppilahti score was 92.9 ± 5.6 in group 1 and 93.6 ± 7.2 in group 2 (P = .68). The mean isokinetic plantar flexion peak torque deficits or average work deficits in plantar flexion showed no differences between the groups with any angular velocity. Isokinetic strength changed minimally between 1 and 11 years compared with the unaffected ankle, but a mean deficit of 5% in peak torque and mean deficit of 8% in average work were still present after 11 years. On the contrary, isometric plantar flexion strength recovered significantly, with only a 2.4% difference at 11-year follow-up.

CONCLUSION

After the 11-year follow-up, early mobilization and immobilization in tension after Achilles rupture repair resulted in similar clinical outcomes and isokinetic strengths. Regardless of patient satisfaction with the operative treatment, calf muscle strength did not recover normally even at 11-year follow-up.

The Achilles tendon resting angle as an indirect measure of Achilles tendon length following rupture, repair, and rehabilitation

Background

Rupture of the Achilles tendon may result in reduced functional activity and reduced plantar flexion strength. These changes may arise from elongation of the Achilles tendon. An observational study was performed to quantify the Achilles tendon resting angle (ATRA) in patients following Achilles tendon rupture, surgical repair, and rehabilitation, respectively.

Methods

Between May 2012 and January 2013, 26 consecutive patients (17 men), with a mean (standard deviation, SD) age of 42 (8) years were included and evaluated following injury, repair, and at 6 weeks, 3 months, 6 months, 9 months, and 12 months, respectively (rehabilitation period). The outcome was measured using the ATRA, Achilles tendon total rupture score (ATRS), and heel-rise test.

Results

Following rupture, the mean (SD) absolute ATRA was 55 (8)° for the injured side compared with 43 (7)° (p < 0.001) for the noninjured side. Immediately after repair, the angle reduced to 37 (9)° (p < 0.001). The difference between the injured and noninjured sides, the relative ATRA, was −12.5 (4.3)° following injury; this was reduced to 7 (7.9)° following surgery (p < 0.001). During initial rehabilitation, at the 6-week time point, the relative ATRA was 2.6 (6.2)° (p = 0.04) and at 3 months it was −6.5 (6.5)° (p < 0.001). After the 3-month time point, there were no significant changes in the resting angle. The ATRS improved significantly (p < 0.001) during each period up to 9 months following surgery, where a score of 85 (10)° was reported. The heel-rise limb symmetry index was 66 (22)% at 9 months and 82 (14)% at 12 months. At 3 months and 6 months, the absolute ATRA correlated with the ATRS (r = 0.63, p = 0.001, N = 26 and r = 0.46, p = 0.027, N = 23, respectively). At 12 months, the absolute ATRA correlated with the heel-rise height (r = −0.63, p = 0.002, N = 22).

Conclusion

The ATRA increases following injury, is reduced by surgery, and then increases again during initial rehabilitation. The angle also correlates with patient-reported symptoms early in the rehabilitation phase and with heel-rise height after 1 year. The ATRA might be considered a simple and effective means to evaluate Achilles tendon function 1 year after the rupture.

Transcription factor Mohawk controls tenogenic differentiation of bone marrow mesenchymal stem cells in vitro and in vivo

Mohawk homeobox (MKX) has been demonstrated as a tendon/ligament specific transcription factor. The aim of this study was to investigate the role of MKX in ligament/tenogenic differentiation of bone marrow derived mesenchymal stem cells (BMMSCs). Human BMMSCs were treated with 50 ng/ml BMP-12 or transduced with MKX or scleraxis (SCX) adenoviral vector. Gene expression analysis was performed by quantitative reverse transcribed polymerase chain reaction (qRT-PCR). Rat BMMSCs were seeded in a collagen scaffold and transplanted into a rat Achilles tendon defect model. Tenogenesis related gene expressions and histological features were analyzed. BMP-12 induced tenogenesis in BMMSCs as indicated by increased COL1a1, TNXB, DCN and SCX mRNA, and MKX expression increased simultaneously. Rat BMMSCs enhanced defect repair and were still detectable 3 weeks after transplantation. Increased expressions of COL1a1, TNC and TNMD in vivo were also correlated with upregulated MKX. Adenoviral MKX promoted expression of COL1a1, TNXB, and TNMD in BMMSCs. This study demonstrated that MKX gene expression is enhanced during the tenogenic differentiation of BMMSCs in vitro and in vivo, and the adenoviral overexpression of MKX increases tendon extracellular matrix gene expression and protein production. Thus, MKX is a key factor for tenogenic differentiation of MSCs.