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Early tensional loading improves mechanical properties of healing Achilles tendons
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February 2014
Early tensional loading improves mechanical properties of healing Achilles tendons
Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:2
Early controlled tension improves the material properties of healing human achilles tendons after ruptures: a randomized trial
Am J Sports Med. 2013 Nov;41(11):2550-7Did you know you're eligible to earn 0.5 CME credits for reading this report? Click Here
Synopsis
35 patients with an acute Achilles tendon rupture were randomized to evaluate the benefits of early tensional loading on the mechanical properties of healing Achilles tendons, when compared to conventional cast treatment. Patients were evaluated over 52 weeks, and the evidence presented in this study indicated that elastic modulus was higher in the tensional loading group at 19 and 52 weeks and no significant differences were apparent between groups concerning the Achilles tendon Total Rupture Score (ATRS) or the heel raise index at 52 weeks. A significant correlation between the modulus at 7 weeks and the heel raise index at 52 weeks was observed and no signs of tendon elongation were noted.
Publication Funding Details
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Funding:
Non-Industry funded
Sponsor:
Swedish Medical Research Council, Linko ping University, The Swedish Center for Sports Medicine Research, and the King Gustav V and Queen Victoria Free Mason Fund
Conflicts:
None disclosed
Was the allocation sequence adequately generated?
Was allocation adequately concealed?
Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?
Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?
Blinding Patients: Was knowledge of the allocated interventions adequately prevented?
Was loss to follow-up (missing outcome data) infrequent?
Are reports of the study free of suggestion of selective outcome reporting?
Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?
Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?
Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?
Yes = 1
Uncertain = 0.5
Not Relevant = 0
No = 0
The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.
4/4
Randomization
3/4
Outcome Measurements
4/4
Inclusion / Exclusion
4/4
Therapy Description
3/4
Statistics
Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65
The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.
Why was this study needed now?
Achilles tendon ruptures result in lengthy periods of immobilization and rehabilitation, and while there is no consensus regarding an optimal method of fixation between operative and nonoperative interventions, a number of animal and clinical studies have demonstrated favorable outcomes associated with early motion and weight bearing. It remains unclear if these effects are caused by mechanical loading of the healing tendon or by motion of the ankle joint that reduced edema and other negative consequences of immobility. This study was consequently needed to investigate the efficacy of controlled tensional loading during the immobilization period in terms of an improvement in the mechanical properties of the healing Achilles tendon.
What was the principal research question?
Does controlled tensional loading during the immobilization improve the mechanical properties of the healing Achilles tendon, as evaluated over 52 weeks?
Study Characteristics
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Population:
35 patients, aged between 18 and 60 years, with an acute Achilles tendon rupture undergoing corrective surgery within 5 days of the injury.
Intervention:
Loading Group: All patients underwent surgery with a single suture and received metal markers in the distal and proximal parts of the tendon. Patients were administered a removable foam walker boot for 5 weeks following 2 weeks of short leg cast application. When administered the foam walker, patients were instructed to use a training pedal twice a day and push the pedal with the aim of completing as many repetitions as possible (limited to 20). Full weight bearing was permitted as tolerated. (n= 18, 13 available at final follow-up; Mean Age: 38.2 years; M/F= 15/3)
Comparison:
Control Group: All patients underwent surgery with a single suture and received metal markers in the distal and proximal parts of the tendon. Patients were administered the short leg cast (foot in equines) for 3.5 weeks, followed by a case in the neutral position for another 3.5 weeks. (n= 17, 16 available at final follow-up; Mean Age: 43.8 years; M/F= 15/2)
Outcomes:
Primary Endpoint: modulus of elasticity calculated using roentgen sterophotogrammetric analysis under different loading conditions and tomography. Clinical outcome was assessed using the Achilles tendon Total Rupture Score (ATRS) and the heel-raise index.
Methods:
RCT: Single-Centered: Nonblinded
Time:
Patients evaluated at 7, 19, and 52 weeks postoperatively
What were the important findings?
- Elastic modulus at 19 and 52 weeks was 35% higher (111 +/- 41 in the loading group vs. 82 +/- 29 in the control; 95% CI: 2 to 69), and 33% higher (355 +/- 116 in the loading group vs. 266 +/- 66 in the control; 95% CI: 7 to 59) in the loading group compared to the control. There were no significant differences between groups for ATRS and heel-raise index at 52 weeks.
- Mean transverse area of every patient doubled between 7 to 19 weeks. At 52 weeks, the area was 30% less than after 19 weeks but still greater than at plaster removal.
- Heel raise index was not significantly different between groups at 52 weeks at about 80% that of the intact side in both groups.
- At 7 weeks, the elastic modulus and the percentage of elongation of all tendons demonstrated a significant correlation with the heel raise index (p= 0.003 and p= 0.03 respectively. There correlations were weaker at 19 weeks (p= 0.08 and p= 0.07 respectively), with no apparent correlation at 52 weeks. Furthermore there was no correlation between the transverse area of the tendon with heel raise index, or between any of the variables for the mechanical properties at 7, 19 or 52 weeks, or the ATRS after 52 weeks.
- No significant difference between groups was apparent in tendon elongation at any time point. 2 outliers (control group) with an elongation of 28 and 31 mm were noted at 52 weeks.
- 1 loading group patient suffered a rerupture after 3 months. 1 patient reported considerable unexplained pain but showed good clinical results after 52 weeks. Another patient was excluded because of 3 of the 4 tantalum beads were placed outside the tendon disallowing elongation measurement. 2 patients in each group exhibited deep vein thrombosis.
What should I remember most?
The elastic modulus was higher in the tensional loading group at 19 and 52 weeks. No significant differences were apparent between groups concerning the Achilles tendon Total Rupture Score (ATRS) or the heel raise index at 52 weeks. A significant correlation between the modulus at 7 weeks and the heel raise index at 52 weeks was observed. No signs of tendon elongation were noted.
How will this affect the care of my patients?
The evidence presented in this study demonstrated that early tensional loading improves the mechanical properties of the healing Achilles tendon. Note that this study was limited by the lack of appropriate blinding. Further research with large samples, patient-important outcome measures, and high methodological quality is needed to validate these findings.
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