Severe Hallux Valgus Angle Attended With High Incidence of Nonunion in Arthrodesis of the First Metatarsophalangeal Joint: A Follow-Up Study

First Metatarsophalangeal Joint Arthrodesis With Complete Resection of the Subchondral Bone Plate

First metatarsophalangeal arthrodesis is associated with high union rates but there is a wide range of union incidence reported. Whether the subchondral plate is completely resected, is not reported by individual studies and without meticulous care, there is often residual subchondral plate. The primary aim was to report our union rate following first metatarsophalangeal arthrodesis with complete resection of the subchondral plate, locking plate fixation and immediate protected weight bearing. A retrospective case study of 2 surgeons was performed from August 2016 to June 2023. Our study was unique in that all patients had complete resection of the subchondral plate to trabecular bone. One hundred seventeen feet were identified for analysis, in 112 patients following exclusion criteria. Patients were excluded if they had less than 3 months follow-up, revisional surgery or charcot. Demographic data and indications for the procedure were reported. A single construct locking plate with an interfragmentary compression screw through the plate was used in 37 feet and a locking plate with separate interfragmentary compression screw was used in 80 feet. We reported a nonunion incidence of 0.9% (n = 1) with a delayed union incidence of 0.9% (n = 1) and a broken hardware incidence of 0.9% (n = 1). Complete resection of subchondral plate with early weight bearing and locking plate fixation had a high union rate for first metatarsophalangeal arthrodesis. Our results compare favorably with union rates in the literature, where there is often residual subchondral plate.

Factors Associated With Nonunion in Arthrodesis of the First Metatarsophalangeal Joint: A Multicenter Retrospective Cohort Study

BACKGROUND

Arthrodesis of the first metatarsophalangeal joint is the current treatment of choice for symptomatic advanced hallux rigidus and moderate-to-severe hallux valgus. There are different methods to perform arthrodesis, yet no consensus on the best approach. Therefore, this study aimed to determine the effects of preoperative and postoperative hallux valgus angle (HVA), joint preparation and fixation technique, and postoperative immobilization on the incidence of nonunion.

METHODS

A retrospective multicenter cohort study was performed that included 794 patients. Univariate and multiple logistic regression was conducted to determine associations between joint preparation, fixation techniques, postoperative immobilization, weightbearing, and pre- and postoperative HVA with nonunion.

RESULTS

Nonunion incidence was 15.2%, with 11.1% symptomatic and revised. Joint preparation using hand instruments (OR 3.75, CI 1.90-7.42) and convex/concave reamers (OR 2.80, CI 1.52-5.16) were associated with greater odds of a nonunion compared to planar cuts. Joint fixation with crossed screws was associated with greater odds of nonunion (OR 2.00, CI 1.11-3.42), as was greater preoperative HVA (OR 1.02, CI 1.00-1.03). However, the latter effect disappeared after inclusion of postoperative HVA in the model, with a small association identified between residual postoperative HVA and nonunion (OR 1.04, CI 1.01-1.08). Similarly, we found an association between odds of nonunion and higher body weight (OR 1.02, CI 1.01-1.04) but not of body mass index.

CONCLUSION

Based on our results, first metatarsophalangeal joint arthrodesis with planar cuts and fixation with a plate and interfragmentary screw is associated with the lowest odds of resulting in a nonunion. Higher body weight and greater preoperative HVA were associated with slight increase in rates of nonunion. It is crucial to properly correct the hallux valgus deformity during surgery.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

First Metatarsophalangeal Arthrodesis for Hallux Rigidus and Hallux Valgus: A Comparison of Patient Reported and Clinical Outcomes

Few prior studies have compared the patient reported outcomes of first metatarsophalangeal arthrodesis between hallux rigidus and hallux valgus patients. Furthermore, we sought to examine the impact of postoperative radiographic hallux alignment on outcomes scores within each group. A retrospective review of 98 patients who a received primary metatarsophalangeal arthrodesis from January 2010 to March 2020. Clinical complications including nonunion were collected. Patient Reported Outcomes Measurement Information Systems (PROMIS) Physical Function, PROMIS Pain Interference, and the foot function index (FFI) revised short form scores were obtained via telephone. Patients were grouped based on review of preoperative radiographs of the foot and this grouping 37 hallux rigidus and 61 hallux valgus patients. Clinical and patient reported outcomes were compared between these pathologies. No differences in the rate of wound complications, radiographic union, and revision surgery were found between the 2 subgroups. At a median of 2.4 years (3.9 IQR) postoperatively, PROMIS and FFI scores did not vary by pathology group. For both groups, PROMIS scores were similar to the general population of the United States. The postoperative first MTP dorsiflexion angle in the hallux rigidus group was correlated with decreased FFI Pain, FFI Total, and PROMIS Pain Interference domain scores (|r| ≥ 0.40, p < .05 for all). When performing MTP arthrodesis in patients with hallux rigidus, increasing the first MTP dorsiflexion angle may correlate with improved intermediate term patient reported outcomes. However, further studies will need to be done to confirm this theoretical relationship.

General Considerations About Foot and Ankle Arthrodesis. Any Way to Improve Our Results?

Nonunion and adjacent joint osteoarthritis (OA) are known complications after a fusion procedure, and foot and ankle surgeons are commonly exposed to such disabling complications. Determining who is at risk of developing nonunion is essential to reducing nonunion rates and improving patient outcomes. Several evidenced-based modifiable risk factors related to adverse outcomes after foot and ankle arthrodesis have been identified. Patient-related risk factors that can be improved before surgery include smoking cessation, good diabetic control (HbAc1 <7%) and vitamin D supplementation. Intraoperatively, using less invasive techniques, avoiding joint preparation with power tools, using bone grafts or orthobiologics in more complex cases, high-risk patients, nonunion revision surgeries, and filling in bone voids at the arthrodesis site should be considered. Postoperatively, pain management with NSAIDs should be limited to a short period (<2 weeks) and avoided in high-risk patients. Furthermore, early postoperative weight-bearing has shown to be beneficial, and it does not seem to increase postoperative complications. The incidence of surrounding joint OA after foot and ankle fusion seems to increase progressively with time. Owing to its progression and high probability of being symptomatic, patients must be informed consequently, as they may require additional joint fusions, resulting in further loss of ankle/foot motion. In patients with symptomatic adjacent joint OA and unsatisfactory results after an ankle arthrodesis, conversion to total ankle arthroplasty (TAA) has become a potential option in managing these complex and challenging situations.