Subtalar arthrodesis

How many screws are necessary for subtalar fusion? A retrospective study

BACKGROUND

Biomechanical studies have shown a higher compressive force and higher torsional stiffness for fixation with three screws compared to two screws. However, clinical data to compare these fixation techniques is still lacking.

METHODS

A retrospective analysis of 113 patients was performed, who underwent isolated subtalar fusion between January 2006 and April 2018.

RESULTS

Revision arthrodesis was required in 8% (n=6/36) for 3-screw-fixation and 38% (n=35/77) for 2-screw-fixation. For 3-screw-fixation, non-union, was observed in 14% (n=5/36) compared to 35% (n=27/77) in 2-screw fixation. Non-union (p=.025) and revision arthrodesis (p=.034) were significantly more frequent in patients with 2 screws. A body mass index ≥30kg/m² (p=.04, OR=2.6,95%CI:1.1-6.3), prior ankle-fusion (p=.017,OR=4.4,95%CI:1.3-14.5) and diabetes mellitus (p=.04,OR=4.9,95%CI:1.1-17.8) were associated with a higher rate of revision arthrodesis.

CONCLUSIONS

Our findings suggest that successful subtalar fusion is more reliably achieved with use of three screws. However, future prospective studies will be necessary to further specify this recommendation.

Subtalar Joint Distraction Arthrodesis to Correct Calcaneal Valgus in Pediatric Patients with Tarsal Coalition: A Case Series

Subtalar joint middle facet coalitions commonly present in children who have a painful, rigid, pes planovalgus foot type. The middle facet coalition allows rearfoot forces to be distributed medially through the coalition, and this can result in arthritis or lateral tarsal wedging. The senior author has used a wedged bone graft distraction subtalar joint arthrodesis to correct calcaneal valgus and restore the talar height in these patients. The tight, press-fit nature of the tricortical iliac crest allograft provides stability and can negate the need for internal fixation. We retrospectively reviewed 9 pediatric subtalar joint distraction arthrodesis procedures performed on 8 patients during a 6-year period. All patients began weightbearing at 6 weeks after surgery. All patients had osseous union, and no complications developed that required a second surgery. The clinical outcomes, assessed at a mean of 25.5 (range, 6.3 to 75.8) months postoperatively, were satisfactory. The mean American Orthopaedic Foot and Ankle Society score was 90.1 (range, 79 to 94), on a 94-point scale. The wedged distraction arthrodesis technique has not been previously described for correction of pediatric patients with lateral tarsal wedging, but it is an effective option and yields successful outcomes.

Overview of subtalar arthrodesis techniques: options, pitfalls and solutions

BACKGROUND

Subtalar arthrodesis (SA) is the preferred treatment for painful isolated subtalar disease. Although results are generally favourable, analysis of current operative techniques will help optimizing this treatment. The aim was to give an overview of SA-techniques and their pitfalls. Possible solutions were identified.

MATERIALS AND METHODS

A literature search was performed for papers that presented SA operative techniques. The general technique was divided into phases: surgical approach, cartilage removal, bone graft selection, hindfoot deformity correction and fixation.

RESULTS

The published series were invariably retrospective reviews of small heterogenous groups of different hindfoot pathologies. The weighted outcome rate for SA was 85% (68-100%) performed in 766 feet and for SA requiring correction of malalignment 65% (36-96%) in 1001 feet. Non-union (weighted percentage 12%), malalignment (18%), and screw removal (17%) were the prevailing late complications.

PITFALLS

The following pitfalls were identified: 1) early complications related to the incisions made in open approaches, 2) insufficient cartilage removal, improper bone graft selection and fixation techniques, all possibly leading to non-union, 3) morbidity caused by bone graft harvesting and secondary screw removal, 4) under- or overcorrection of the hindfoot possibly due to improper intraoperative verification and 5) inadequate assessment of bony fusion.

SOLUTIONS

The review provides solutions to possibly overcome some pitfalls: 1) if applicable use an arthroscopic approach in combination with distraction devices and new burrs, 2) if possible use local bone graft or allografts, 3) use two screws for fixation to prevent rotational micromotion, and 4) improve assessment of operative outcome by application of appropriate assessment of bony fusion and alignment.

CONCLUSION

The review provides practical suggestions to optimize SA-techniques.

Joint curettage arthrodesis technique in the foot: a histological analysis

Arthrodesis via joint contour preservation using the curettage method has become popular in foot and ankle surgery to avoid segmental shortening and the need to bone graft. Despite its popularity, the effect of joint curettage has never been histologically evaluated. Knowledge of the histological appearance after joint curettage would be helpful to the foot and ankle surgeon to better understand the function of joint surface preparation for arthrodesis. Five cadaver specimens were used to harvest the first metatarsocuneiform and subtalar joints for routine histological analysis after performing joint curettage technique. One specimen was used as a reference, whereas the remaining specimens were processed after joint surface preparation. Results show a residual layer of calcified cartilage overlying the subchondral plate interface on all osteochondral specimens after joint curettage. This suggests there is a natural histological barrier that may interfere with arthrodesis consolidation.

LEVEL OF CLINICAL EVIDENCE

5.

Principles of arthrodesis and advances in fixation for the adult acquired flatfoot

Arthrodesis continues to be the procedure of choice in treatment of the end-stage adult acquired flatfoot. Its goals are to provide pain relief, correct the deformity, and improve function and stability. A better understanding of anatomy and operative technique has led to significant refinements and advances in fixation. These devices have proved useful in arthrodesing and tenodesing procedures. The principles in achieving a sound arthrodesis and the various forms of fixation are discussed in detail.