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Background: Although an association between intercuneiform (C1-C2) joint instability and the recurrence of hallux valgus (HV) deformity after the modified Lapidus procedure has been suggested, there is currently no radiographic evidence to support it. This study aims to investigate radiographic changes in the C1-C2 joint after the modified Lapidus procedure for HV correction, using weightbearing computed tomography (WBCT)., Methods: This retrospective cohort study included 52 feet (50 patients) with HV who underwent modified Lapidus procedure and had preoperative and postoperative WBCT. Patients who had an additional transfixation screw between the first and second ray were excluded. The preoperative and average 6.5 months postoperative C1-C2 distance, C1-C2 angle, and C1-ground angle were measured on coronal multiplanar reconstructed WBCT images. Radiographic parameters between the recurrence group (n = 9) and nonrecurrence group (n = 43) were compared. Recurrence of HV deformity was characterized by a postoperative hallux valgus angle (HVA) greater than 20 degrees., Results: Nine of 52 patients (17.3%) had recurrence of their HV deformity. The recurrence group had greater changes in the C1-C2 distance; the median widening in the recurrence group was 0.7 mm (IQR, 0.6-0.8), whereas the nonrecurrence group was 0.3 mm (IQR, 0.1-0.4, P  < .001). Regression analysis showed that increase in the C1-C2 distance were significantly associated with recurrence (odds ratio, 1.79; 95% CI, 1.18-3.77; P  = .0015). Although no preoperative imaging parameters were associated with a change in the C1-C2 distance, increasing postoperative sesamoid position ( r  = 0.32, P  = .022) and HVA ( r  = 0.28, P  = .046) were correlated with a greater change in the C1-C2 joint gapping., Conclusion: Our study results suggest a possible association between early postoperative widening of the C1-C2 joint and the recurrence of the HV deformity following a modified Lapidus procedure. This raises, but does not answer, the question as to whether the routine stabilization of intercuneiform joint directly or indirectly may help reduce the rate of hallux valgus recurrence when performing the modified Lapidus procedure., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: There are limited data regarding risk factors associated with periprosthetic medial malleolar fractures in total ankle arthroplasty (TAA). This case-control study aimed to identify the risk factors and analyze the effect of prophylactic screw fixation in preventing a medial malleolar fracture after TAA., Methods: A case-control study was conducted on 149 patients who underwent primary TAA. Twenty patients with postoperative medial malleolar fractures >4 weeks postoperatively (cases) were identified. An additional 129 patients (controls) were randomly selected from the TAA database. Radiographic evaluation included tibial component coronal alignment and postoperative medial malleolar width. Demographics and radiographic variables were compared between cohorts. Logistic regression was used to investigate the association between medial malleolar fracture and postoperative coronal alignment, medial malleolar width, and prophylactic fixation of the medial malleolus., Results: Mean (SD) medial malleolar width was significantly smaller in the fracture cohort (8.52 mm [1.6]) than in the control group (11.78 mm [1.74]) ( P < .001). Mean (SD) tibial component coronal alignment was 92.17 degrees (2.77) in the fracture cohort and 90.21 degrees (1.66) in the control group ( P  = .002). Regression analysis identified a significant negative association between postoperative medial malleolar width and the probability of fracture (OR = 0.06, 95% CI 0.01, 0.26, P  < .001). Varus malalignment of the tibial component was positively associated with the probability of fracture (OR = 1.90, 95% CI 1.27, 2.86, P  = .002). Prophylactic screw fixation resulted in more than 90% reduction in the odds of a fracture (OR = 0.04, 95% CI 0.01, 0.45, P  = .01). ROC curve analysis determined a medial malleolar width of 10.3 mm as a potential threshold for predicting fracture., Conclusion: Decreased medial malleolar width and postoperative varus malalignment were associated with an increased risk of postoperative medial malleolar fracture. Therefore, surgeons should consider prophylactic screw fixation in patients with a medial malleolar width <10.3 mm or at risk of postoperative varus deformity., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Constantine A. Demetracopoulos, MD, reports royalties or licenses and consulting fees from Exactech, Inc, and In2Bones, and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Exactech, Inc. Disclosure forms for all authors are available online.

Background: Isolated subtalar and talonavicular joint arthrodeses have been associated with adjacent joint arthritis and altered hindfoot kinematics during simplified loading scenarios. However, the effect on kinematics during dynamic activity is unknown. This study assessed changes in subtalar and talonavicular kinematics after isolated talonavicular (TN iso ) and subtalar (ST iso ) arthrodesis, respectively, during stance simulations., Methods: Fourteen midtibia specimens received either a TN iso or ST iso arthrodesis, with 7 randomized to each group. A 6-degree-of-freedom robot sequentially simulated the stance phase for the intact and arthrodesis conditions. Bootstrapped bias-corrected 95% CIs of the talonavicular and subtalar joint kinematics were calculated and compared between conditions., Results: The TN iso decreased subtalar inversion, adduction, and plantarflexion in late stance ( P  < .05). The subtalar range of motion in the sagittal and coronal planes decreased by 40% ( P  = .009) and 46% ( P  = .002), respectively. No significant changes in talonavicular joint kinematics were observed after isolated subtalar arthrodesis; however, the range of motion was reduced by 61% ( P  = .007) and 50% ( P  = .003) in the coronal and axial planes, respectively., Conclusion: In this model for arthrodesis, changes in subtalar kinematics and motion restriction were observed after isolated talonavicular arthrodesis, and motion restriction was observed after isolated subtalar arthrodesis. Surprisingly, talonavicular kinematics did not appear to change after isolated subtalar arthrodesis., Clinical Relevance: Both joint fusions substantially decrease the motion of the reciprocal adjacent joint. Surgeons should be aware that the collateral costs with talonavicular fusion appear higher, and it has a significant effect on subtalar kinematics during the toe-off phase of gait., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors report support for the present manuscript from a Paragon 28 research grant contract; Paragon 28 provided screws to perform the arthrodesis conditions and complete the original study that this short report expands on. Disclosure forms for all authors are available online.

Background: Ankle arthritis leads to an elevated joint line compared to the nonarthritic ankle, as measured by the "joint line height ratio" (JLHR). Previous work has shown that the JLHR may remain elevated after total ankle arthroplasty (TAA). However, the clinical impact of this has yet to be determined. This study assessed the correlation between postoperative JLHR, post-TAA range of motion (ROM), and 1-year Patient-Reported Outcome Measurement Information System (PROMIS) scores., Methods: A retrospective review of 150 patients who underwent primary TAA was performed. Preoperative and postoperative JLHR, as well as postoperative dorsiflexion, plantarflexion, and total ROM, was calculated on weightbearing radiographs at a minimum of 1-year follow-up. Correlation between JLHR, post-TAA ROM, and 1-year PROMIS scores was investigated using Pearson correlation and multiple linear regression models. Interobserver reliability for the JLHR was also calculated., Results: Interobserver reliability for the JLHR was excellent ( r  = 0.98). Mean (SD) JLHR changed from 1.66 (0.45) to 1.55 (0.26) after TAA ( P  < .001), indicating that the joint line was lowered after TAA. An elevated joint line was correlated with decreased post-TAA dorsiflexion ( r  = -0.26, P  < .001), total ROM ( r  = -0.18, P  = .025), and worse 1-year PROMIS physical function ( r  = -0.22, P  = .046), pain intensity ( r  = 0.22, P  = .042), and pain interference ( r  = 0.29, P  = .007). There was no correlation between the JLHR and post-TAA plantarflexion ( r  = -0.025, P  = .76). Regression analysis identified a 0.5-degree reduction in post-TAA dorsiflexion with each 0.1-unit increase in JLHR (Coeff. = -5.13, P  = .005)., Conclusion: In this patient cohort, we found that an elevated joint line modestly correlated with decreased postoperative dorsiflexion, total ROM, and worse 1-year PROMIS scores. These data suggest that effort likely should be made toward restoring the native joint line at the time of TAA. In addition, future studies investigating the clinical outcomes after TAA may consider including a measure of joint line height, such as the JLHR, because we found it was associated with patient-reported outcomes., Level of Evidence: Level III, retrospective review of prospectively collected data., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. ICMJE forms for all authors are available online.