Midfoot arthritis is a common condition leading to disabling chronic foot pain that affects
activities of daily living. The causes can be primary osteoarthritis (OA), inflammatory or
post-traumatic. We are looking at OA of the lesser (second and/or third) tarsometatarasal
joints (TMTJ). Orthotics, customised shoes or steroid injections are options to treat this
condition nonoperatively. If these measures fail, arthrodesis of the arthritic joints
represents the standard procedure to surgical treatment. Generally, the results of this
procedure are at a satisfactory level for the patients, nevertheless, there is a relevant
amount of patients with residual pain, lack of a normal foot appearance, and the need for
unplanned surgery or use of orthotics postoperatively. Furthermore, patients undergoing an
arthrodesis of the lesser TMTJ usually have to stay in hospital for 4-7 days.
Postoperatively, patients are only allowed to partially weightbear for at least 6 weeks and
need a cast for six weeks as well. During that time thrombosis prophylaxis is administered
for about 6 weeks.
The conventional distal minimal-invasive metatarsal osteotomy (DMMO) is an accepted technique
for metatarsal osteotomies. Recently, Schneider et al. presented results of a modification of
the conventional DMMO, the reverse DMMO to treat OA of the lesser TMTJ, thus representing an
alternative treatment to arthrodesis. The procedure has many benefits. It allows outpatient
care, an immobilisation in a cast is not necessary. Instead, patients have to wear a flat
postoperative shoe for 2-3 weeks and are allowed to fully weightbear from day one after
surgery. Therefore, thrombosis prophylaxis is not necessary unless there are specific risk
factors.
However, while the arthrodesis directly addresses the arthritic joints, the R-DMMO alters the
ground reaction force of the metatarsal head leading to less stress at the level of the TMTJ,
but the arthritic joint itself is not approached. Still, the results presented by Schneider
et al. are promising. Since there was no group to compare the treatment with, the small
sample size, and a retrospective design, we would like to prospectively compare these two
surgical procedures directly in order to find out whether or not the R-DMMO can be
recommended as a standard procedure for OA of the lesser TMTJ at a much more convenient level
for patients regarding the whole perioperative protocol. No vulnerable population is
included. The scientific value is remarkable since this would be the first study to examine
this matter and we are able to provide a high level of evidence due to the
prospective-randomised and comparative design of the study. All legal requirements will be
fulfilled and the ethical standards are guaranteed.
Both procedures have been described and the technique of the DMMO itself is not new, but its
modification (R-DMMO) represents a new approach for this condition. Both procedures are
reliable and safe, which is why the risk category of the study is A according to ClinO, Art.
61.