Early E-modulus of healing Achilles tendons correlates with late function: similar results with or without surgery.

Non-operative treatment of Achilles tendon ruptures is associated with an increased risk of rerupture. We hypothesized that this is due to inferior mechanical properties during an early phase of healing, and performed a randomized trial, using a new method to measure the mechanical properties. Tantalum markers were inserted in the tendon stumps, and tendon strain at different loadings was measured by stereo-radiography (Roentgen stereophotogrammetric analysis) at 3, 7 and 19 weeks and 18 months after injury. Thirty patients were randomized to operative or non-operative treatment. The primary out-come variable was an estimate for the modulus of elasticity at 7 weeks. Strain per force, cross-sectional area and tendon elongation were also measured. The functional outcome variable was the heel-raise index after 18 months. There was no difference in the mean modulus of elasticity or other mechanical or functional variables between operative and non-operative treatments at any time-point, but strain per force at 7 and 19 weeks had a significantly larger variation in the non-operative group. This group, therefore, might contain more outliers with poor healing. The modulus of elasticity at 7 weeks correlated with the heel-raise index after 18 months in both treatment groups (r(2) =0.75; P=0.0001). This correlation is an intriguing finding.

Elevation of systemic matrix metalloproteinases 2 and 7 and tissue inhibitor of metalloproteinase 2 in patients with a history of Achilles tendon rupture: pilot study.

OBJECTIVES: In this study, serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) between patients with a history of Achilles tendon rupture and blood donor controls were compared, and their relation to mechanical properties of the tendons during healing were studied. METHODS: More than 3 years after injury, serum levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9 and MMP-13, TIMP-1 and TIMP-2 in eight patients who had Achilles tendon rupture were measured. Twelve blood donors served as controls. During the early phase of healing, the tendon modulus of elasticity was calculated from radiostereometric data and tendon cross-sectional area. RESULTS: Patients with a history of Achilles tendon rupture had increased levels of MMP-2 (median difference 10%, p=0.01), MMP-7 (median difference 15%, p=0.02) and TIMP-2 (median difference 36%, p=0.02), compared with controls. Levels of MMP-7, measured 3 years after injury, correlated inversely to tendon modulus of elasticity (r(s)=20.83, p=0.02) and positively to tendon elongation (r(s)=0.74, p=0.05) during the early phase of healing. There was a trend towards positive correlation between MMP-7 and cross-sectional area during the early phase of healing (r(s)=0.67, p=0.08). CONCLUSIONS: Patients with a history of Achilles tendon rupture appear to have elevated levels of MMP-2, MMP-7 and TIMP-2 in serum. In these pilot data, the view that the MMP-TIMP system is involved in tendinopathy is supported and that disturbances in proteolytic control might be generalised are suggested.