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Study design, case-control study: Background, Morton’s extension (ME) is a kind of orthotic that has been used as a conservative treatment of painful hallux rigidus (HR) osteoarthritis, but only their effects on first metatarsophalangeal joint (MPJ) mobility and position in healthy subjects have been studied, but not on its applied pulled tension forces neither in subjects with HR. Objectives: This study sought to understand how ME’s orthotics with three different thicknesses could influence the kinematic first MPJ by measuring hallux dorsiflexion using Jack’s test and a digital algometer with a rigid strip anchored to the iron hook’s extremity and comparing subjects with healthy first MPJ mobility to those with HR. We aimed to clarify whether tension values were different between healthy and HR subjects. Methods: Fifty-eight subjects were selected, of whom thirty were included in the case group according to HR criteria and twenty-eight were included in the control group. A digital algometer (FPX®® 25, Wagner Instruments®®, Greenwich, CT, USA) was used to assess the pulled tension values (kgf) of the first MPJ during Jack’s test. Results: The pulled tension values were highly reliable (ICC > 0.963). There were no statistically significant differences between the pulled tension values for the different ME conditions in the case (p = 0.969) or control (p = 0.718) groups. However, as it’s expected, there were statistically significant differences comparing all pulled tension values between case and control group subjects (p < 0.001). Conclusions: Different ME’s thicknesses had no influence on the pulled effort applied during the dorsiflexion Jack’s test between the healthy and HR groups; therefore, it can be prescribed without joint-care danger. In addition, it is proven that there is greater resistance to performing Jack’s test in the HR group than in the healthy group, regardless of ME’s orthotics. Furthermore, it is shown that the digital algometer device is a valid tool to detect the first MPJ restriction and is more reliable than other tests.