Background <p>Outcome after an acute Achilles tendon rupture often leaves individual variations in recovery and lingering impairment. Simple and accurate methods to assess healing during early rehabilitation are lacking. In this pilot study, we developed and evaluated a graded assessment procedure based on Thompson´s test. The aim was to examine if foot movement of the injured foot can be reliably assessed with the Four-point Scale of Thompson’s test (FST).</p> Methods <p>The observed foot movement on the injured side, was graded in four categories, zero to three, in relation to the foot movement on the non-injured side. Assessments of foot movement for 24, non-surgically treated, individuals were performed at 2, 4, 8, 10 and 12 weeks after the injury. The movement was visually measured by two examiners, physiotherapists, and simultaneously measured using a marker based three-dimensional motion analysis system (3D-MA). Visual FST measurements were compared with the 3D-MA–based measurements.For each method, intra- and inter-observer agreement as well as between method agreement was evaluated using AC2 agreement measure and difference plots.</p> Results <p>The intra- and inter observer agreement for the FST showed that that the agreement for examiner 1 was 0.94 and for examiner 2, 0.84 while the agreement between 1 and 2 was 0.83. Intra-observer agreement for the 3D-MA measurements for examiner 1 was 0.84 and for examiner 2 were 0.85 while the agreement between examiner 1 and 2 was 0.70. Agreement between methods for examiner 1 was 0.67 and for examiner 2, 0.57. Both measurement methods showed a similar increase of the average foot movement over the follow-up period. </p> Conclusions <p>Our findings suggests that the inter- and intra-examiner agreements were high indicating that the scale is reliable within and between raters. The agreements between FST and 3D-MA was moderate indicating that criterion validity needs further studies against a modified marker-based 3D motion analysis.</p>