The Achilles tendon, while the strongest tendon in the human body, is susceptible to complete rupture, occurring most frequently in men 30 to 50 years of age. While the treatment for these ruptures can involve surgical or nonsurgical repair, a consensus has not been reached regarding the optimal intervention. For both interventions the length of the tendon may elongate, with this occurring within 6-12 weeks after surgery. This study was designed to better understand this phenomenon.

Subjects were 75 patients with acute tendon rupture, all presenting for surgical repair. During that procedure, metal beads were implanted on either side of the rupture. After surgery, an orthosis was used for the first six weeks, with three heel wedges placed within the orthosis, with one wedge removed each week to allow for increased dorsiflexion. The participants were randomized to one of three separate rehabilitation regimens, including late weightbearing with immobilization (LWB ＋ IMMOB), late weightbearing with mobilization (LWB ＋ MOB) or early weightbearing with mobilization (EWB ＋ MOB), which involved partial weightbearing from day one and full weightbearing from week five. The primary outcome variable was tissue elongation at rest.

Elongation increased from six to 12 weeks (P<0.01) and from 12 to 26 weeks (P<0 .001), but not from 26 to 52 weeks. There was no group difference in the amount of elongation that occurred. For tendon cross-sectional area, no interaction or group effect was found, but a significant effect of time was noted (P<0.0001)．

This study of patients undergoing surgical repair of a ruptured Achilles tendon found that elongation occurs over the first six months, without being influenced by a patient′s weightbearing or mobilization protocol.