When treating patients with flexor tendon resection surgery of the hand (FDS, FDP) the treatment best is passive flexion at surgical site and active extension as it would avoid damage to surgical site, but Kisner mentions use of early controlled active motion based on experiment. Which theory should be applied and why post op. Will the approach be the same for mallet finger too?

Abbreviations and definitions: FDS (Flexor Digitorum Superficialis or Sublimis), FDP (Flexor Digitorum Profundus).

Mallet finger (also known as baseball finger, Hannan Finger and more generally as extensor tendon injury), is an injury of the extensor digitorum tendon of the fingers at the distal interphalangeal joint (DIP). It results from hyperflexion of the extensor digitorum tendon and usually occurs when a ball (such as a softball, basketball, volleyball or dodgeball), while being caught, hits an outstretched finger and jams it, creating a ruptured or stretched extensor digitorum tendon. [1]

A 2012 article by Schofll et al, Tendon injuries of the hand, published online in the World Journal of Orthopedics, provides some guidelines to rehabilitative protocols under the heading, post-operative care, of the same article. According to the article, the protocols also apply to mallet finger. The following is an excerpt:

‘… Aftercare of flexor tendon injuries should follow the scheme of dynamic early mobilization…which allows passive flexion carried out by a rubber string and active extension. The wrist flexion of the cast is reduced gradually and after 3 weeks, a Kleinert-bandage with rubber band restraints can be applied. Free functional movement is allowed after 5 weeks and full exposure after 3-4 months. An ‘intrinsic tendon healing’ is sought for, which requires intermittent tension stress, achieved by the ‘early passive movement’ principle. Recently, more progressive aftercare schemes postulate active flexion of the tendon immediately after surgery but are not yet commonly established…’

The article thus corroborates both your observations and Kisner’s recommendation. Therefore, in practice, both theories of rehabilitation in your question can be applied depending on the Therapist’s judgment, the individual clinical scenario presented and the outcomes desired etc. It is also possible that Kisner’s approach, while ‘not commonly established’ in 2012 may be quite a common procedure now. This is because physical therapy practice is a dynamic, evidence-based science and is constantly evolving to be able to offer the best rehabilitative outcomes. New information builds on previous information and current practices are supported by the latest evidence.

Reference 1, Reference 2