Soleus subtendon elongation is reduced by individual suturing of Achilles subtendons after rupture

PURPOSE: The primary aim was to evaluate if individual suturing of the gastrocnemius and soleus parts of the ruptured Achilles tendon could reestablish their length 1 week post-surgery compared to previously published results using a standard operative technique. We hypothesised that this new suturing technique would reduce the soleus subtendon length by 50% compared to the standard technique 1 week after surgery (primary endpoint). Secondary aims included soleus and gastrocnemius subtendon lengths at 26 weeks. METHODS: The ambi-directional design included a retrospective part using a standard Kessler repair of the tendon as a single structure (n = 24) and a prospective part using a novel surgery that sutured the soleus and gastrocnemius subtendons separately (n = 23). One and 26 weeks after surgery, both groups underwent 3D MRI to determine the length of the soleus and gastrocnemius subtendons. RESULTS: For the soleus subtendon, the individual suturing technique yielded a smaller side-to-side (injured-uninjured) difference (1.9 ± 14.7 mm) compared to the standard surgery (17.0 ± 11.5 mm, p < 0.0001) at week 1 and week 26 (individual 10.7 ± 14.9 mm, standard 21.5 ± 12.7 mm, p < 0.0001), although there was an increase in the individual suturing from week 1 to week 26, (p < 0.05). The side-to-side difference in gastrocnemius subtendon length was not significantly affected by suturing technique but increased with time for individual suturing from week 1 (-1.5 ± 10.6 mm) to week 26 (9.2 ± 9.4 mm, p < 0.0001), and for standard suturing from week 1 (1.8 ± 11.1 mm) to week 26 (8.4 ± 10.9 mm, p < 0.0001). CONCLUSION: Using an individual suturing approach, soleus and gastrocnemius subtendon lengths were nearly restored to normal values 1 week postoperatively. Subsequent elongation of the soleus subtendon over 6 months was also significantly less with individual suturing than standard surgical repair. LEVEL OF EVIDENCE: Level III.