SLR - September 2015 - Ari Changizi

Mid- to Long-Term Outcome of 96 Corrective Hindfoot Fusions in 84 Patients with Rigid Flatfoot Deformity

Reference: Röhm J, Zwicky L, Horn Lang T, Salentiny Y, Hintermann B, Knupp M.  Mid- to Long-term Outcome of 96 Corrective Hindfoot Fusions in 84 Patients with Rigid Flatfoot Deformity. Bone Joint J.  2015 May;97-B(5):668-74.

Scientific Literature Review

Reviewed By: Ari Changizi, DPM
Residency Program: Medstar Washington Hospital Center, Washington, DC.

Podiatric Relevance: A modified triple or a subtalar and talonavicular joint (double) arthrodesis via a single medial incision for correction of severe pes planovalgus deformity has been a topic of contemporary interest. However, there is little evidence on its medium- to long-term durability. This article evaluates the outcome of patients who underwent a modified triple and its outcome over time, specifically an average of 4.7 years follow up.     

Methods: This is a retrospective review, which looked at 96 modified triple arthrodesis preformed on 84 patients: 27 men and 57 women with average age of 66 (35-85 years old).  The procedures were done by one of two surgeons. Ninety-two of the feet were symptomatic rigid flatfoot or stage III PTTD on the Johnson and Strom classification and four had stage IV with tibotalar tilt on x-ray. Using a single medial incision as originally described by De wachter et al, and Jeng et al., the talonavicular (TN) and subtalar joint (STJ) were exposed and debrided. K wires were used to hold the reduction of hindfoot and 14 feet received an adjunctive medial displacement osteotomy of the calcaneus to completely reduce the valgus deformity. Two or three 5.5 mm cannulated screws and two 7.5 mm screws were used on TN and STJ respectively. One additional screw was used on patients who received a medial displacement osteotomy of the calcaneus. Moreover, eleven patients needed a tarsometatarsal joint fusion due to sagging of medial column.

One surgeon, not involved in any of the operations, evaluated the two months post-operative and final follow-up xrays. AP ankle, and lateral views were compared for talar tilt and Meary's angle (angle between first metatarsal and talus). A decrease of 5 degrees on Meary's angle was defined as loss of correction. Clinically AOFAS and FAOS (five subscales: ADL, Sports/recreation, foot and ankle related quality of life: Qol) were used. VAS scale and modified Coughlin score (very good, good, moderate, and bad) were also employed.

Results: Ninety-five feet where radiographed with one dropping out due to moving overseas. Of these, 86 (90.5 percent) had consistent correction on xrays. Nine feet (9.5 percent) had loss of correction in neighboring joints: three valgus tilt in ankle, three increased Meary's angle, and three had combination of the two deformities. Overall 11 feet had nonunions in TN or STJ, four had nonunion in both of these joints. Five were asymptomatic and six needed revision via iliac crest and screw fixation, which all healed at 12 months. 

Overall three talar dome AVN were noted due to placing screws far posterolaterally in the talar dome. No tobacco or metabolic disease was noted in these patients. One of these three patients died due to unrelated cause and two had TARs. One patient had over correction with painful overload of the lateral side and underwent STJ arthrodesis revision. Eight patients required complete or partial removal of the screws. No patient had calcaneocuboid joint pain.
 
In total eight patients died of unrelated causes, six did not complete follow up questionnaire, and four with TAR or ankle fusion were excluded. So a total of 78 questionnaires were analyzed. Of these 31 percent reported very good satisfaction, 35 percent good, 18 percent moderate, and 16 percent bad. The 16 percent bad results correlated with stage IV PTTD and multiple co-morbidities. The mean AOFAS was 67 points and VAS was 2.4. Mean FAOS pain was 72.6, and the symptoms subscales were 72.7. Each subscale rated from 0-100 as follow: ADL: 75.0, sports/recreation:43.7, QoL:53.5 points. Overall 81 percent of the respondent would have the same surgery again. 

Conclusions: This article discusses modified triple arthrodesis and its radiographic and clinical outcomes over an average of four years and seven months. They discuss potential complications and secondary deformity like flattening of the arch, and clinical outcomes via AOFAS, FAOS, and VAS scales to paint a clear picture for comparison of this procedure to a traditional triple arthrodesis, although no comparison was performed. The authors claim the modified triple has good clinical outcome at mid to long term follow-up. Moreover, they explain nonunions as the most frequent complication and AVN of the talus primarily occurring in stage IV PTTD as rare but one that leads to TAR or ankle fusion; thereby hinting on reserving modified triple only for Stage III PTTD. They also cite previous studies in support of modified triple. Specifically, one showed very good visualization and preparation of the TN and STJ through a single medial incision. The result of this study shows validated clinical outcome measures that a practitioner can rely on while making surgical decision to choose modified triple over a traditional triple arthrodesis. Rest assured the procedure will have comparable durability if proper patient selection and good technique is followed.

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