Improving calf muscle strength in patients with spastic equinovarus deformity by transfer of the long toe flexors to the Os calcis

The split tibialis anterior tendon transfer (SPLATT), Achilles tendon lengt hening, and toe flexor release are proven and effective procedures for corr ecting a spastic equinovarus deformity of the foot. Paresis is a prominent feature of upper motoneuron syndrome. Lengthening the Achilles tendon, alth ough necessary to correct the equinus, further weakens the gastrocnemius-so leus muscle group. The calf paresis commonly results in the need for an ank le-foot orthosis (AFO) during ambulation. Previous studies have shown that despite the correction of the equinovarus deformity, only one third of pati ents were able to ambulate without an AFO. The need for continued use of an AFO was because of insufficient calf strength to stabilize the tibia durin g late stance when the body mass is anterior to the ankle joint. This study prospectively evaluated the results of transfer of the flexor hallucis lon gus (FHL) and flexor digitorum longus (FDL) to the os calcis in 30 patients . The transfer was done in an effort to augment the strength of the gastroc nemius-soleus muscle complex. Twenty-five patients in group I (the control group) underwent SPLATT, Achilles tendon lengthening, and toe flexor releas e. Thirty patients in group II (the study group) underwent the identical pr ocedures plus the additional FHL and FDL transfer to the os calcis. Postope ratively, the varus and toe flexion deformities were corrected in all feet. In group II, two feet had a mild residual equinus that did not interfere w ith ambulation. Of the 11 patients who were not independent community ambul ators in group I, 7 (64%) improved ambulatory status by at least one level after surgery. Of the 15 patients who were not independent community ambula tors in group II, 14 (93%) improved ambulatory status by at least one level after surgery. In group 1, 10 of 25 (40%) of the patients were brace free at follow-up. In group II, 21 of 30 (70%) were brace free at follow-up (chi (2), P = .025). These results indicate that the addition of an FHL and FDL transfer to the os calcis at the time of SPLATT, Achilles tendon lengthenin g, and toe flexor release improves calf strength and allows greater increas e in function and less reliance on orthotics.