Correlation Between Recovery of Triceps Surae Muscle Strength and Level of Activity After Open Repair of Acute Achilles Tendon Rupture

Portable device for measuring isometric plantar-flexion force after open Achilles repair: Retrospective cohort of 30 recreational athletes with one-year minimum follow-up

BACKGROUND

Plantar flexion force in recreational athletes after repair of Achilles tendon tears has rarely been reported, due to the lack of a widely available and fast measurement method. Knowledge of this parameter would allow optimisation of muscular and sports recovery. The main objective of this study was to measure the isometric force of the triceps surae at least 1 year after unilateral Achilles-tendon repair, comparatively to the unaffected side, using a portable device. The secondary objectives were to compare Achilles tendon and calf-muscle trophicity, dorsiflexion, and the single-leg heel-rise test versus the normal side and to assess functional scores at last follow-up.

HYPOTHESES

(i) Plantar flexion force does not differ significantly between the operated and contralateral sides. (ii) Calf-muscle trophicity, dorsiflexion, and the single-leg heel-rise test do not differ significantly between the operated and contralateral sides.

PATIENTS AND METHODS

This single-centre retrospective study included patients aged 18 to 65 years with a history of open repair of an acute unilateral Achilles tear at least 1 year earlier. Plantar flexion force, calf-muscle trophicity, dorsiflexion, and the heel-to-floor distance were measured on both sides and compared. The ATRS, VISA-A score, and EFAS score were determined. All complications were recorded.

RESULTS

The study included 30 patients with a mean follow-up of 20.3 months (range, 12-28 months). The operated side had significantly lower values for isometric triceps surae force, calf circumference, and heel-to-floor distance compared to the contralateral side (p<0.0001). Tendon width was significantly greater on the operated side (p<0.0001). Dorsiflexion did not differ significantly between sides (p=0.106). Mean functional score values were 91.5±6 for the ATRS (maximum, 100), 85±12 for the VISA-A score (maximum, 100), and 19.5±4 for the EFAS score (maximum, 24).

DISCUSSION

Isometric triceps-surae force measured using a portable device at least 1 year after open surgical Achilles-tendon repair was significantly decreased compared to the contralateral side. Calf circumference and heel-to-floor distance were also significantly lower. These data indicate a need for improved monitoring of triceps surae recovery to optimise rehabilitation and sports resumption.

LEVEL OF EVIDENCE

IV, retrospective comparative cohort study.

Reliability and Reference Norms of Single Heel-Rise Test Among Children: A Cross-sectional Study

There is a lack of data regarding the single heel-rise test (SHRT) among children. Hence, we aimed to establish reliability and reference norms of SHRT among children aged 8 to 12 years. About 500 healthy children were randomly selected from the recognized school and community settings. After demographic measurements, SHRT was conducted to evaluate the strength of each plantar flexors. SHRT repetitions were assessed by the same rater on 2 occasions for intrarater (on the same day) and test-retest reliability (on different days) and by 2 raters for inter-rater reliability. Relative reliability was described in terms of the intraclass correlation coefficient (ICC) and Pearson correlation coefficient (r). Absolute reliability was indicated by the standard error of measurement (SEm), minimal detectable change (MDC), and Bland-Altman graph. The mean of the number of repetitions of SHRT was calculated to derive the reference norm of SHRT. The anthropometric parameters were correlated with SHRT for multiple regression analysis. Intrarater, test-retest, and inter-rater reliability of SHRT were, ICC = 0.81, ICC = 0.70, and ICC = 0.57, respectively. The Bland-Altman graph confirmed limits of agreement for intrarater, test-retest, and inter-rater reliability. The reference norm of SHRT is documented to be 20.6 ± 4.8. SEm and MDC are found to be 2 and 3, respectively. Multiple regression analysis predicted a correlation of age, weight, and calf muscle girth with SHRT. SHRT is moderate to good reliable in assessing the strength of plantar flexors. The reference norms of SHRT have been derived for healthy children aged 8 to 12 years.

Morphology of Acute Achilles Tendon Rupture by Intraoperative Evaluation

The purpose of this study was to clarify the morphology of acute Achilles tendon rupture (ATR) according to intraoperative evaluation. The morphology of 220 cases was evaluated retrospectively from intraoperative findings from June 2014 to December 2015. We noted 3 characteristics of rupture. First, we divided the ruptures into complete or partial type. Second, according to the level of rupture, we classified them into muscle-tendon junctional type, mid-substantial type, or calcaneal insertional avulsion type. Lastly, on the basis of the pattern of rupture, we divided them into transverse pattern, double-layer pattern, or Z-shaped pattern. All ruptured tendons were repaired with surgical procedures on the basis of the classification of rupture type or pattern. Of the total of 220 cases, 217 were complete ruptures (98.7%) and 3 partial ruptures (1.3%). Regarding the level of rupture, 5 cases were of the muscle-tendon junctional type (2.3%), 209 cases of the mid-substantial type (95%), and 6 cases of the calcaneal insertional avulsion type (2.7%). In terms of the pattern of rupture, there were 198 cases of the transverse pattern (90%), 10 cases of the double-layer pattern (4.5%), and 12 cases of the Z-shaped pattern (5.5%). There was significant gender difference only in the mid-substantial type. Although the morphology of a typical acute ATR was complete, of mid-substance type, and with transverse pattern, other types of ATR were recognized from the intraoperative investigation.

Plantarflexor fiber and tendon slack length are strong determinates of simulated single-leg heel raise height

Achilles tendon ruptures have been linked with detrimental changes in muscle-tendon structure, which may help explain long-term functional deficits. However, the causal effects of muscle-tendon structure on joint function have not been tested in a controlled setting. Therefore, the purpose of this study was to test the implications of muscle-tendon unit parameters on simulated single-leg heel raise height. We hypothesized that muscle fiber length and resting ankle angle - a clinical surrogate measure of tendon slack length - would predict single-leg heel raise height more strongly than other parameters. To test this hypothesis, we developed a two-part simulation paradigm that recreated clinically relevant muscle-tendon scenarios and then tested these parameters on single-leg heel raise height. We found that longer muscle fibers had the greatest positive effect on single-leg heel raise height. However, tendon slack length, determined by simulating resting ankle angles in a secondary analysis, revealed a stronger negative correlation with heel raise height. Our findings support previous clinical observations that both muscle fascicle length and resting tendon length are important muscle-tendon parameters for patient function. In addition to minimizing tendon elongation following rupture, treatment plans should focus on preserving plantarflexor muscle structure to mitigate functional loses following Achilles tendon ruptures.