Abstract The Achilles tendon is the largest tendon in the human body and is affected by many diseases and is vulnerable to many forms of damage due to the heavy loads it must bear. Rupture of the Achilles tendon has become more common in recent times, with an almost four-fold increase in prevalence from 1979–1990 to 1991–2000 and a peak incidence of 19 ruptures per 100 000 of population in 1999 in our epidemiological assessment. The incidences of major complications, re-rupture and deep infection, increased along with primary ruptures, peaking in 1999. The results after successful primary repair are good in over 90% of cases, as we have shown in a randomized study and in a review of the literature, and the result after re-rupture is still good in about 70% of cases, but achieving good performance after deep infection is a highly random matter. Our retrospective survey did not identify any good results, but the deep infection cases in our randomized study showed good performance due to prompt action taken for their treatment. The best method for treating a ruptured Achilles tendon has been under debate for almost 100 years, with surgery and conservative methods advocated to equal extents. We have advocated surgical treatment as the primary choice and conservative treatment is given for selected high risk patients, for example patients with diabetes, skin problems, systemic use of corticosteroids or severe other illness. The type of surgery technique is not a straightforward choice, either, and various forms of open surgery and percutaneous techniques exist. We compared an end-to-end simple suture with the same suture augmented with one central gastrocnemius turn-over flap in a randomized series of 60 patients and found no differences with respect to subjective complaints, calf muscle strength or tendon elongation with time. The end-to-end technique is simpler and is therefore justified as the primary method of choice for the surgical repair of fresh complete Achilles tendon ruptures. The tissue composition has been shown to alter not only with time but also after repeated tearing of the tendon collagen fibres. A normal tendon is mainly composed of type I collagen, but the rupture areas express more type III collagen, which is thinner and withstands loads less effectively. Type III collagen accumulates slowly in the tendon, since its production does not increase very much, a situation that is indicative of microtrauma. Crosslinking of the fibres is important for collagen matrix properties, and we found that there is a change in the quality of crosslinking with age and that this may have role in the observed changes in tendon stiffness, as also noted in other studies. We also studied the appearance of tenascin-C at the rupture site in the Achilles tendon and at two other sites in the same tendon, but found no difference in its expression. It has been proposed that tenascin-C may take part in the tendon’s reaction to loading, but its exact function remains unknown.

Abstract The purposes of the present research were to compare the outcome after Achilles tendon rupture repair in two postoperative regimens, to compare Achilles tendon elongation in two postoperative treatment methods, to compare the effects of two postoperative methods on motor performance aspects such as simple reaction time, choice reaction time, speed of movement, foot tapping speed and coordination, to test the mechanical properties of the recently developed poly-L/D-lactide (PLDLA) sutures and Maxon® sutures when implanted in the Achilles tendons of rabbits, and to study the histological tissue reactions and biodegradation of these sutures under the same conditions. Isokinetic calf muscle strength scores at the last control check-up were excellent in 56% of the patients in the early motion group, good in 32%, fair in 8%, and poor in 4%, whereas the scores in the cast group were excellent in 29% of cases, good in 50% and fair in 21%. The ankle performance scores were excellent or good in 88% of the patients in the early motion group, fair in 4% and poor in 8%, whereas the scores in the cast group were excellent or good in 92% of cases and fair in 8%. No significant differences were seen between the two groups at 3 months and at the last control checkups with regard to pain, stiffness, subjective calf muscle weakness, footwear restrictions, range of ankle motion, isokinetic calf muscle strength or overall outcome. The complications included 1 re-rupture in the early motion group and 1 deep infection and 2 re-ruptures in the cast group. AT elongation occurred in both groups, but was somewhat less marked in the early motion group. The AT elongation curves rose at first and then fell slowly in both groups. The patients who had less AT elongation achieved a better clinical outcome. AT elongation did not correlate significantly with age, body mass index or isokinetic peak torques. The recovery of motor performance functions such as simple reaction time, choice reaction time, speed of movement, foot tapping speed and coordination did not depend on the two postoperative regimens. The motor functions of the operated leg had obviously recovered to the level of the non-operated leg 12 weeks after the operation. Sutures made of PLDLA were used successfully for Achilles tendon repair in rabbits. There was no significant difference between the in vitro and in vivo tensile strength retention of the sutures. By comparison with Maxon®, PLDLA was found to have a lower initial tensile strength but more prolonged strength retention. The breaking strength values of the Achilles tendons repaired with sutures of these types were not significantly different at 6 weeks. Intratendinous PLDLA sutures formed a thinner fibrous capsule during the 12-week follow-up period than did Maxon® sutures of the same diameter. The suture materials had not been totally absorbed by 12 weeks.