By Katie Bell
Single-leg standing heel-rise test performance one year after Achilles tendon rupture is associated with the long-term recovery of ankle biomechanics, according to research from Gothenburg, Sweden. The findings may have implications for rehabilitation after Achilles injury, particularly with regard to relatively demanding activities such as jumping.
The ankle impairments observed six years after injury in the study could potentially lead to longer-term pathologies, although further research is needed to confirm that, said lead author Annelie Brorsson, PT, MSc, an associate researcher in the Department of Orthopaedics at the University of Gothenburg.
“Theoretically, it is possible that the risk for overload injuries can increase in some individuals due to the asymmetrical loading in ankle and knee joints during more demanding activities,” Brorsson said.
Brorsson and colleagues assessed 38 patients one year after Achilles rupture. In 17, heel-rise height for the injured limb was less than 15% of the unaffected limb; in the other 17, the side-to-side difference was greater than 30%. A mean of six years after injury, the researchers assessed ankle biomechanics, tendon length, calf muscle recovery, and patient-reported outcomes.
Standard motion capture procedures were used to analyze ankle mechanics during walking, jogging, a single-leg countermovement drop jump, and hopping. Kinematic variables included plantar flexion, dorsiflexion, eversion, and abduction; kinetic variables included eccentric and concentric plantar flexion power, peak Achilles tendon force, and Achilles impulse.
Achilles tendon Total Rupture Score (ATRS), Physical Activity Scale, and Foot and Ankle Outcome Score were used to evaluate patient-reported symptoms and physical activity, while ultrasound was used to measure tendon length.
Fifteen patients in the <15% group and 13 patients in the >30% group were included in the final analysis. At long-term follow-up, the >30% group had more deficits in ankle kinetics during all activities than the <15% group, with the respective limb symmetry indices (LSI) ranging from 70% to 149% and 84% to 106%. No between-group differences were found for ankle kinematics.
Additionally, at long-term follow-up the >30% group was less symmetrical than the <15% group for heel-rise height (LSI of 72% vs 95%) and heel-rise work (LSI of 58% vs 91%). LSI for tendon length was also significantly greater for the >30% group (114% vs 106%).
The authors reported correlations between peak ankle abduction and tendon length during walking and jogging, but no correlations between tendon length and any of the kinetic variables. Although a correlation was found between one kinematic variable (peak ankle abduction) and LSI for heel-rise work, several correlations were noted between LSI for heel-rise work and kinetic variables. Additionally, between-limb difference in tendon length was correlated negatively with LSI for heel-rise height. The study found no differences between groups in patient-reported outcomes.
The kinetic differences between groups were most notable during hopping. In addition, the LSI for heel-rise work was correlated with all kinetic variables during hopping, but with only eccentric plantar flexion power during walking. The authors hypothesized that a difference in stretch-recoil cycle between groups might explain this finding.
The authors concluded that minimizing tendon elongation and regaining heel-rise height during rehabilitation after Achilles tendon injury may be important for ankle biomechanics recovery in the long term. The findings were epublished by The American Journal of Sports Medicine in August.
David A Porter, MD, PhD, an orthopedic surgeon at Methodist Sports Medicine in Indianapolis, IN, recommended the use of a rehab program that emphasizes aggressive early weightbearing and early range of motion—practices that were first popularized in Europe but which are becoming more common in the US (see “Battles of Achilles II: How the debate is informing clinical practice,” November 2015, page 20).
“Work hard on isolated, single-leg strengthening. Specifically, work and focus on heel raises in your rehab protocol,” Porter said. “Focus on the biomechanics of walking and running that emphasize midfoot striking to encourage more normal pushoff and improved gastrocnemius-soleus function.”
Brorsson A, Willy RW, Tranberg R, Grävare Silbernagel K. Heel-rise height deficit 1 year after Achilles tendon rupture relates to changes in ankle biomechanics 6 years after injury. Am J Sports Med 2017 Aug 1. [Epub ahead of print]