Flexor Digitorum Longus Transfer and Medial Displacement Calcaneal Osteotomy for Posterior Tibial Tendon Dysfunction: A Middle-Term Clinical Follow-Up
Authors: Guyton Gregory P. , Jeng Clifford , Krieger Lauren E. , Mann Roger A. 
Published: January 2017

Hypotheses/Purpose: The medial displacement calcaneal osteotomy has recently become a popular addition to flexor digitorum longus transfer for stage II posterior tibial tendon dysfunction. We reviewed the results of 26 patients who had undergone the procedure at an average of 32 months prior to follow-up (range 12 to 70 months) with particular attention to objective functional parameters.

Conclusions/Significance: FDL transfer and medial displacement calcaneal osteotomy provides good functional and symptomatic results in the middle-term. The operation preserves the majority of subtalar motion and is objectively durable as assessed by the continued ability to perform a single-leg toe rise. Although moderate radiographic improvement in the arch is frequent, often patients fail to notice this clinically. A prolonged period of steady improvement in symptoms after surgery is common.

Summary of Methods/Results: Between 1993 and 1998, 26 patients underwent flexor digitorum longus transfer and medial displacement calcaneal osteotomy performed by the senior author. Sixteen returned for the study and were seen for physical exams. Three were included on the basis of chart review including one who was deceased and two who could not be contacted. Five further patients included on the basis of chart review were also contacted for telephone interviews. For the survival analysis, however, their last physical examination was used as the follow-up date. Two patients who had early technical failures were not interviewed but were counted as early failures of the procedure in the survival analysis.

Functionally, all patients except three could perform a single-leg toe rise at follow-up, a maneuver none could perform preoperatively. Of these three, two cases were technical failures with loss of fixation of the FDL transfer early in the postoperative course, ultimately requiring revision procedures including one subtalar fusion. Another patient was a late failure after developing increasing pain and weakness during a pregnancy 69 months after the procedure. Clinically assessed subtalar motion remained 81 ± 15% of the contralateral side in those patients with unilateral disease.

Although improvement in the radiographic alignment of the foot was commonly noted, only 50% of patients felt the conformation of their foot had noticeably changed, and only one (4%) felt the improvement to be significant. Pain relief was rated excellent by 75% and good by 16% the average AOFAS Hindfoot pain subscale score was 35.2 (out of 40 possible). Function was felt to be markedly improved by all patients except the three who were unable to perform a single-leg toe rise. The average score for the four functional symptom categories of the AOFAS score was 26.8 (out of 28 possible).

Most patients noted that although they were able to perform daily activities after their postoperative immobilization was liberalized, there was a prolonged period of steady improvement in symptoms and function after surgery. The median length of time to self-rated maximal medical improvement was 10 months.