Objective In groups randomly allocated to immediate weight bearing or delayed weight bearing (standard care), to assess the difference in plantar flexor muscle endurance, strength, hop performance, perceived function, and Achilles tendon length at 12-18 months post injury.

Study Design The first phase of this study was implemented by researchers from the Orthopaedic Department at Wellington Regional Hospital. It was a prospective randomised control trial (RCT) with the two treatment groups mentioned above. The second phase utilised the RCT cohort, but otherwise was independently conceived and implemented for this master’s thesis research. It was a cross-sectional design assessing participants 12-18 months post conservatively managed Achilles tendon rupture in an immediate weight bearing (VACOped) group compared to a standard care group.

Background Achilles tendon rupture is a traumatic injury event with increasing incidence and often long-term functional consequences. Ongoing deficits in plantar flexor endurance and strength are often seen 12 months post injury and return to sport rates post Achilles tendon rupture range from 50-70 percent. Hence, a significant amount of people who suffer this injury never return to normal function. There is poor consensus regarding the optimal conservative management strategy to date. Early mobilisation is a possible strategy, but results to date have been inconsistent and there is limited evidence of performance based testing post Achilles tendon rupture.

Method Performance based functional outcomes were measured using the total heel raise work test, maximum voluntary contraction (MVC) of the plantar flexors, single leg hop for distance, single leg hop for height and a lateral movement 30 second continuous hop test. Achilles tendon length was measured using the resting angle method. Perceived function was measured using the Achilles Tendon Rupture Score (ATRS) and the Injury-Psychological Readiness to Return to Sport (I-PRRS).

Results From the initial RCT, 34 participants were recruited (VACOped group: 20; Standard Care group: 14). There was a significant difference (p < 0.05) across limbs for the total heel raise work test, MVC test, hop for distance and height tests. There was no significant group or interaction effect (p > 0.05) observed across all performance based functional outcome measures. There were no significant differences (p > 0.05) across groups in both the ATRS and the I-PRRS. The mean score for the ATRS in the VACOped group was 80 while the mean score in the standard care group was 72. The mean score for the I-PRRS in the VACOped group was 48 compared to 41 in the standard care group. There was a significant difference (p < 0.05) across limbs, but no significant group or interaction effect (p > 0.05) was observed for Achilles tendon length measures. Regarding legs, a mean increase of 29 percent and 32 percent in Achilles resting angle was observed across legs in the VACOped and standard care groups, respectively.

Conclusion Based upon the variables measured, immediate weight bearing did not lead to increased physical performance compared to the delayed weight bearing group at 12-18 months post injury. At this time point, findings highlighted notable and significant deficits in plantar flexor muscle endurance, plantar flexor muscle strength, maximum effort hop tests, and Achilles tendon length across limbs irrespective of group allocation. In line with previous research, secondary findings showed that there were also ongoing deficits in self-perceived function and self-confidence to return to sport post Achilles tendon rupture.