Clinical biomechanics of the peritalar joint

Preoperative Hindfoot Alignment and Outcomes After High Tibial Osteotomy for Varus Knee Osteoarthritis: We Walk on Our Heel, Not Our Ankle

UPDATE

This article was updated on May 15, 2024 because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 898, in the section entitled "Materials and Methods," the sentence that had read "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the center of the calcaneus (for the GA) or talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." now reads "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the lowest point of the calcaneus (for the GA) or the center of the talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." Likewise, in the legend for Figure 3 on page 899, the sentence that had read "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the center of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." now reads "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the lowest point of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." Finally, on page 903, "HKA" was changed to "HKA angle" in Table III.

BACKGROUND

The hip-to-calcaneus axis, previously known as the ground mechanical axis (GA), ideally passes through the center of the knee joint in the native knee. The aim of this study was to elucidate, with use of hip-to-calcaneus radiographs, changes in knee and hindfoot alignment and changes in outcomes following high tibial osteotomy (HTO).

METHODS

We reviewed the records for 128 patients who underwent HTO between 2018 and 2020. Patients were stratified into 2 groups, a hindfoot valgus group (n = 94) and a hindfoot varus group (n = 34), on the basis of their preoperative hindfoot alignment. The hindfoot alignment was evaluated with use of the hindfoot alignment angle (HAA). To evaluate lower-limb alignment, full-length standing posteroanterior hip-to-calcaneus radiographs were utilized to measure 4 radiographic parameters preoperatively and 2 years postoperatively: the hip-knee-ankle (HKA) angle, hip-knee-calcaneus (HKC) angle, and the weight-bearing line (WBL) ratios of the mechanical axis (MA) and GA.

RESULTS

The mean HAA improved significantly from 5.1° valgus preoperatively to 1.9° valgus postoperatively in the hindfoot valgus group (p < 0.001). In contrast, in the hindfoot varus group, the HAA showed no meaningful improvement in the coronal alignment of the hindfoot following HTO (p = 0.236). The postoperative mean HKC angle in the hindfoot varus group was 2° more varus than that in the hindfoot valgus group (1.0° versus 3.0°; p = 0.001), and the GA in the hindfoot varus group passed across the knee 8.0% more medially than that in the hindfoot valgus group (55% versus 63% from the most medial to the most lateral part of the tibial plateau). The hindfoot varus group had worse postoperative clinical outcomes than the hindfoot valgus group in terms of the mean Knee injury and Osteoarthritis Outcome Score for pain and American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score.

CONCLUSIONS

Although our findings did not provide sufficient evidence to establish clinically relevant differences between the groups, they indicated that the group with a preoperative fixed hindfoot varus deformity had a higher rate of undercorrection and worse clinical outcomes, especially pain, following HTO. Therefore, modification of the procedure to shift the GA more laterally may be required for these patients.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

4D-foot analysis on effect of arch support on ankle, subtalar, and talonavicular joint kinematics

BACKGROUND

It has been difficult to study the effects of arch support on multiple joints simultaneously. Herein, we evaluated foot and ankle kinematics using a fully automated analysis system, "4D-Foot," consisting of a biplane X-ray imager and two-dimensional‒three-dimensional registration, with automated image segmentation and landmark detection tools.

METHODS

We evaluated the effect of arch support on ankle, subtalar, and talonavicular joint kinematics in five healthy female volunteers without a clinical history of foot and ankle disorders. Computed tomography images of the foot and ankle and X-ray videos of walking barefoot and with arch support were acquired. A kinematic analysis using the "4D-Foot" system was performed. The ankle, subtalar, and talonavicular joint kinematics were quantified from heel-strike to foot-off, with and without arch support.

RESULTS

For the ankle joint, significant differences were observed in dorsi/plantarflexion, inversion/eversion, and internal/external rotation in the late midstance phase. The dorsi/plantarflexion and inversion/eversion motions were smaller with arch support. For the subtalar joint, a significant difference was observed in all the dynamic motions in the heel-strike and late midstance phases. For the talonavicular joint, significant differences were observed in inversion/eversion and internal/external rotation in heel-strike and the late midstance phases. For the subtalar and talonavicular joints, the motion was larger with arch support. An extremely strong correlation was observed when the motion of the subtalar and talonavicular joints was compared for each condition and motion.

CONCLUSIONS

The results indicated that the arch support decreased the ankle motion and increased the subtalar and talonavicular joint motions. Additionally, our study demonstrated that the in vivo subtalar and talonavicular joints revealed a strong correlation, suggesting that the navicular and calcaneal bones were moving similarly to the talus and that the arch support stabilizes the ankle joint and compensatively increases the subtalar and talonavicular joint motions.

Effect of Peritalar Subluxation Correction for Progressive Collapsing Foot Deformity on Patient-Reported Outcomes

BACKGROUND

Peritalar subluxation (PTS) is part of progressive collapsing foot deformity (PCFD). This study aimed to evaluate initial deformity correction and PTS optimization in PCFD patients with flexible hindfoot deformity undergoing hindfoot joint-sparing surgical procedures and its relationship with improvements in patient-reported outcome measures (PROMs) at latest follow-up. We hypothesized that significant deformity/PTS correction would be observed postoperatively, positively correlating with improved PROMs.

METHODS

A prospective comparative study was performed with 26 flexible PCFD patients undergoing hindfoot joint-sparing reconstructive procedures, mean age 47.1 years (range, 18-77). We assessed weightbearing computed tomography (WBCT) overall deformity (foot and ankle offset [FAO]) and PTS markers (distance and coverage maps) at 3 months, as well as PROMs at final follow-up. A multivariate regression model assessed the influence of initial deformity correction and PTS optimization in patient-reported outcomes.

RESULTS

Mean follow-up was 19.9 months (6-39), and the average number of procedures performed was 4.8 (2-8). FAO improved from 9.4% (8.4-10.9) to 1.9% (1.1-3.6) postoperatively (P < .0001). Mean coverage improved by 69.6% (P = .012), 12.1% (P = .0343) and 5.2% (P = .0074) in, respectively, the anterior, middle, and posterior facets, whereas the sinus tarsi coverage decreased by an average 57.1% (P < .0001) postoperatively. Improvements in patient-reported outcomes were noted for all scores assessed (P < .03). The multivariate regression analysis demonstrated that improvement in both FAO and PTS measurements significantly influenced the assessed PROMs.

CONCLUSION

This study demonstrated significant improvements in the overall 3D deformity, PTS markers, and PROMs following hindfoot joint-sparing surgical treatment in patients with flexible PCFD. More importantly, initial 3D deformity correction and improvement in subtalar joint coverage and extraarticular impingement have been shown to influence PROMs significantly and positively. Addressing these variables should be considered as goals when treating PCFD.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Ankle Pain After Medial Opening-Wedge High Tibial Osteotomy in Patients With Knee Osteoarthritis and Concurrent Ankle Osteoarthritis

BACKGROUND

Medial opening-wedge high tibial osteotomy (MOWHTO) in patients with varus knee osteoarthritis (OA) causes changes to ankle and hindfoot alignment. However, the compensatory ability of the ankle and hindfoot varies according to the severity of ankle OA.

PURPOSE

To investigate whether the changes in ankle symptoms and ankle and hindfoot alignments differ after MOWHTO according to the severity of preoperative ankle OA.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The data of 130 patients who were followed for ≥4 years were reviewed. Patients were classified into 2 groups according to their severity of ankle OA: group 1, modified Kellgren-Lawrence grade 0 and 1; group 2, grade ≥2. Four radiographic parameters were examined to evaluate ankle alignment: tibial plafond inclination, talar tilt, talar inclination, and tibial surface angle. The hindfoot alignment was evaluated using the varus-valgus angle (VVA) of the calcaneus. A visual analog scale (VAS) was used to evaluate ankle pain. The patient-reported outcome measure of the knee joint was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score.

RESULTS

There were 110 patients in group 1 and 20 patients in group 2. In group 2, the change in talar inclination after MOWHTO was significantly greater and the changes in tibial plafond inclination, talar tilt, and VVA were significantly smaller compared with in group 1 (all P < .05). Ankle pain VAS scores were more severe in group 2 than in group 1 pre- and postoperatively (all P < .05), and group 2 reported that ankle pain worsened postoperatively (P < .05). In both groups, knee WOMAC scores improved, and there were no differences between groups pre- or postoperatively (all P > .05). A multivariate regression analysis demonstrated that a small VVA change (odds ratio, 0.775; P = .027) and severe OA grade of the ankle joint preoperatively (Kellgren-Lawrence grades 2-4 vs 0 and 1; odds ratio, 4.241 [P = .046]) predicted increased ankle pain VAS scores after MOWHTO.

CONCLUSION

Although the patient-reported outcome measures for the knee joint improved irrespective of the presence of ankle OA, ankle pain worsened after MOWHTO in patients with ankle OA. Inadequate compensatory change in hindfoot alignment increased ankle pain in these patients.

Screw only versus screw plus plate in isolated talonavicular arthrodesis

BACKGROUND

We aimed to compare outcomes of treatment of isolated talonavicular arthrodesis (ITNA) with screw only or screw plus plate, respectively.

METHODS

We retrospectively evaluated 40 consecutive cases of ITNA [two-screw fixation patients: Group 1 (23 cases); screw-plus-plate fixation patients: Group 2 (17 cases)]. Outcome measures included radiographic findings, Foot and Ankle Outcome Scores (FAOS), and visual analogue scale (VAS) scores.

RESULTS

Nonunion occurred more frequently in group 1 (21.7%) than in group 2 (5.9%), but there was no statistical significance (p = 0.216). Although the preoperative FAOS and VAS score showed similar results between both groups, there were significantly better clinical outcomes in two of five FAOS domains and VAS scores at 3 months postoperative and final follow-up (p < 0.05).

CONCLUSION

Although union rates were not significantly different, nonunion occurred more frequently in screw only group and we obtained more favorable clinical outcomes in screw plus plate group.

The Effect of the Mobile Subtalar Joint on Calcaneal and Supramalleolar Osteotomies

BACKGROUND

The mobile subtalar joint (STJ) may compensate for supra- and inframalleolar deformities and counteract the effect of realigning calcaneal or distal tibial osteotomies. The purpose of this study was to evaluate the compensatory effect of the mobile STJ after supramalleolar osteotomy (SMOT) and calcaneus osteotomy (COT) and whether the extent of the compensation correlates with STJ shape and orientation.

METHODS

In 10 human lower leg cadavers without evidence of deformity or prior trauma 700 Newton load were applied as a simulated standing pose. The center of force (COF) migration, maximum pressure (Pmax), and the area loaded were measured with high-resolution sensors in the ankle before and after 10-mm varus/valgus sliding COT and 10-degree varus / valgus SMOT. A computed tomographic evaluation of subtalar anatomy was conducted to correlate posterior facet curvature, its varus/valgus orientation in the coronal plane, and the effect on COF, Pmax, and area loaded.

RESULTS

The COF migration was significant for both varus and valgus SMOTs (varus SMOT: 1.78 mm, P = .0029; valgus SMOT: 1.85 mm, P = .0018) but not for COT (varus COT: 0.45 mm, P = .85; valgus COT: 1.15 mm, P = .11). Pmax and area loaded changed but not significantly. The radius of the posterior STJ surface showed a moderate correlation (varus SMOT: r = 0.61, P = .063; valgus SMOT: r = 0.28, P = .43, varus COT: r = -0.61, P = .063; valgus COT: r = 0.13, P = .38) and the axis a weak inverse correlation (varus SMOT: r = -0.51, P = .013; valgus SMOT: r = 0.58, P = .079; varus COT: r = -0.51, P = .14; valgus COT: r = 0.38, P = .28) with the COF migration after the osteotomies.

CONCLUSION

The compensatory capacity of a mobile STJ is relatively small but appears to limit the effect of COT more than SMOT. The COT is less effective in influencing ankle joint pressure for realignment purposes than SMOT in mobile STJ and clinically more consistent in stiff STJ. Correlations are moderate to weak, whereas the curvature more than orientation of posterior facet inversely correlates with osteotomy's effects.

LEVEL OF EVIDENCE

Level IV, biomechanical cadaver study.

Alignment of the hindfoot in total knee arthroplasty: a systematic review of clinical and radiological outcomes

AIMS

Patients with a deformity of the hindfoot present a particular challenge when performing total knee arthroplasty (TKA). The literature contains little information about the relationship between TKA and hindfoot alignment. This systematic review aimed to determine from both clinical and radiological studies whether TKA would alter a preoperative hindfoot deformity and whether the outcome of TKA is affected by the presence of a postoperative hindfoot deformity.

METHODS

A systematic literature search was performed in the databases PubMed, EMBASE, Cochrane Library, and Web of Science. Search terms consisted of "total knee arthroplasty/replacement" combined with "hindfoot/ankle alignment". Inclusion criteria were all English language studies analyzing the association between TKA and the alignment of the hindfoot, including the clinical or radiological outcomes. Exclusion criteria consisted of TKA performed with a concomitant extra-articular osteotomy and case reports or expert opinions. An assessment of quality was conducted using the modified Methodological Index for Non-Randomized Studies (MINORS). The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and registered in the PROSPERO database (CRD42019106980).

RESULTS

A total of 17 studies were found to be eligible for review. They included six prospective and ten retrospective studies, and one case-control study. The effects of TKA showed a clinical improvement in the hindfoot deformity in three studies, but did not if there was osteoarthritis (OA) of the ankle (one study) or a persistent deformity of the knee (one study). The radiological alignment of the hindfoot corrected in 11 studies, but did not in the presence of a rigid hindfoot varus deformity (in two studies). The effects of a hindfoot deformity on TKA included a clinical association with instability of the knee in one study, and a shift in the radiological weightbearing axis in two studies. The mean MINORS score was 9.4 out of 16 (7 to 12).

CONCLUSION

TKA improves both the function and alignment of the hindfoot in patients with a preoperative deformity of the hindfoot. This may not apply if there is a persistent deformity of the knee, a rigid hindfoot varus deformity, or OA of the ankle. Moreover, a persistent deformity of the hindfoot may adversely affect the stability and longevity of a TKA. These findings should be interpreted with caution due to the moderate methodological quality of the studies which were included. Therefore, further prospective studies are needed in order to determine at which stage correction of a hindfoot deformity is required to optimize the outcome of a TKA. Cite this article: Bone Joint J 2021;103-B(1):87-97.

Is Lower-limb Alignment Associated with Hindfoot Deformity in the Coronal Plane? A Weightbearing CT Analysis

BACKGROUND

The goals of lower limb reconstruction are to restore alignment, to improve function, and to reduce pain. However, it remains unclear whether alignment of the lower limb and hindfoot are associated because an accurate assessment of hindfoot deformities has been limited by superposition on plain radiography. Consequently, surgeons often overlook hindfoot deformity when planning orthopaedic procedures of the lower limb. Therefore, we used weight-bearing CT to quantify hindfoot deformity related to lower limb alignment in the coronal plane.

QUESTIONS/PURPOSES

(1) Is lower-limb alignment different in varus than in valgus hindfoot deformities for patients with and without tibiotalar joint osteoarthritis? (2) Does a hindfoot deformity correlate with lower-limb alignment in patients with and without tibiotalar joint osteoarthritis? (3) Is joint line orientation different in varus than in valgus hindfoot deformities for patients with tibiotalar joint osteoarthritis? (4) Does a hindfoot deformity correlate with joint line orientation in patients with tibiotalar joint osteoarthritis?

METHODS

Between January 2015 and December 2017, one foot and ankle surgeon obtained weightbearing CT scans as second-line imaging for 184 patients with ankle and hindfoot disorders. In 69% (127 of 184 patients) of this cohort, a combined weightbearing CT and full-leg radiograph was performed when symptomatic hindfoot deformities were present. Of those, 85% (109 of 127 patients) with a median (range) age of 53 years (23 to 75) were confirmed eligible based on the inclusion and exclusion criteria of this retrospective comparative study. The Takakura classification was used to divide the cohort into patients with (n = 74) and without (n = 35) osteoarthritis of the tibiotalar joint. Lower-limb measurements, obtained from the full-leg radiographs, consisted of the mechanical tibiofemoral angle, mechanical tibia angle, and proximal tibial joint line angle. Weightbearing CT images were used to determine the hindfoot's alignment (mechanical hindfoot angle), the tibiotalar joint alignment (distal tibial joint line angle and talar tilt angle) and the subtalar joint alignment (subtalar vertical angle). These values were statistically assessed with an ANOVA and a pairwise comparison was subsequently performed with Tukey's adjustment. A linear regression analysis was performed using the Pearson correlation coefficient (r). A reliability analysis was performed using the intraclass correlation coefficient.

RESULTS

Lower limb alignment differed among patients with hindfoot deformity and among patients with or without tibiotalar joint osteoarthritis. In patients with tibiotalar joint osteoarthritis, we found knee valgus in presence of hindfoot varus deformity and knee varus in presence of hindfoot valgus deformity (mechanical tibiofemoral angle 0.3 ± 2.6° versus -1.8 ± 2.1°; p < 0.001; mechanical tibia angle -1.4 ± 2.2° versus -4.3 ± 1.9°; p < 0.001). Patients without tibiotalar joint osteoarthritis demonstrated knee varus in the presence of hindfoot varus deformity compared with knee valgus in presence of hindfoot valgus deformity (mechanical tibiofemoral angle -2.2 ± 2.2° versus 0.9 ± 2.4°; p < 0.001; mechanical tibia angle -1.8 ± 2.1° versus -4.3 ± 1.9°; p < 0.001). Patients with more valgus deformity in the hindfoot tended to have more tibiofemoral varus (r = -0.38) and tibial varus (r = -0.53), when tibiotalar joint osteoarthritis was present (p < 0.001). Conversely, patients with more valgus deformity in the hindfoot tended to have more tibiofemoral valgus (r = 0.4) and tibial valgus (r = 0.46), when tibiotalar joint osteoarthritis was absent (p < 0.001). The proximal joint line of the tibia had greater varus orientation in patients with a hindfoot valgus deformity compared with greater valgus orientation in patients with a hindfoot varus deformity (proximal tibial joint line angle 88.5 ± 2.0° versus 90.6 ± 2.2°; p < 0.05). Patients with more valgus deformity in the hindfoot tended to have more varus angulation of the proximal tibial joint line angle (r = 0.31; p < 0.05).

CONCLUSIONS

In patients with osteoarthritis of the tibiotalar joint, varus angulation of the knee was associated with hindfoot valgus deformity and valgus angulation of the knee was associated with hindfoot varus deformity. Patients without tibiotalar joint osteoarthritis exhibited the same deviation at the level of the knee and hindfoot. These distinct radiographic findings were most pronounced in the alignment of the tibia relative to the hindfoot deformity. This suggests a detailed examination of hindfoot alignment before knee deformity correction at the level of the proximal tibia, to avoid postoperative increase of pre-existing hindfoot deformity. Other differences detected between the radiographic parameters were less pronounced and varied within the subgroups. Future research could identify prospectively which of these parameters contain clinical relevance by progressing osteoarthritis or deformity and how they can be altered by corrective treatment.

LEVEL OF EVIDENCE

Level III, prognostic study.

Subtalar Joint Biomechanics: From Normal to Pathologic

Subtalar joint biomechanics are primarily driven by the shape of the articulations with contributions from the surrounding soft tissues. The joint motion occurs about a single axis oriented medially and superiorly. Joint contact forces change during different stages of gait and are affected by hindfoot alignment and traumatic alterations to their normal anatomy. A valgus subtalar joint axis is likely a contributing, and perhaps primary, risk factor for progression to adult acquired flat foot. The subtalar joint axis also contributes to the clinical picture of a cavus foot and a special subset of patients with dynamic varus.

Efficiency of locking-plate fixation in isolated talonavicular fusion

INTRODUCTION

Talonavicular (TN) fusion is an effective means of treating hindfoot deformity and pain. At the cost of a certain limited morbidity, it allows lasting stabilization of all of the torque joints. Non-union rates, however, are high, due to insufficient mechanical stability of the fixation. The present study assessed radiological and clinical results in TN fusion fixed by two retrograde compression screws and a dorsal locking plate.

MATERIAL AND METHOD

A retrospective single-surgeon study recruited 26 TN fusions performed in 25 patients (13 male, 12 female; mean age, 54.6±15.4years) between March 1st, 2010 and February 28th, 2014. Mean follow-up was 14.9±8.7months. Bone fusion and anatomic results were assessed on dorsoplantar, lateral and Méary weight-bearing radiographs.

RESULTS

Radiologic fusion was achieved in all cases, at a mean 2.7±0.7months. Mean TN coverage angle was 21.7±10.5° preoperatively and 3.8±1.8° at follow-up. Mean AOFAS score improved significantly, from 37.2±11.8 (range, 20-53) preoperatively to 79.4±11.4 (range, 45-98) at follow-up.

CONCLUSION

TN fusion fixed by two retrograde compression screws and a dorsal locking plate provided a high rate of consolidation without loss of angular correction and with satisfactory clinical results.

LEVEL OF EVIDENCE

IV.

TYPE OF STUDY

Retrospective.

Missed peritalar injuries: an analysis of factors in cases of known delayed diagnosis and methods for improving identification

Because of the complex anatomy of the foot, rarity of fractures of the foot, and subtle radiographic cues, foot injuries are commonly overlooked and mis/undiagnosed. This study seeks to investigate a patient population whose peritalar injuries, including fractures and dislocations, were missed on initial examination, in order to analyze factors of known, missed injuries and provide insight into methods for reducing the incidence of missed diagnoses. Surgical cases between January 1999 and May 2011 were queried and retrospectively reviewed to identify missed peritalar injuries. Of 1682 surgical cases reviewed, 27 patients with missed peritalar injury(ies), which were subsequently confirmed by imaging studies, were identified. Using the Orthopaedic Trauma Association classification, fracture and dislocation subtypes were classified. A medical record review was performed to assess demographic and surgical data elements. In this study population, 7 types of peritalar injuries (talus, calcaneal, navicular, and cuboid fractures as well as subtalar, calcaneocuboid, and talonavicular joint dislocations) were diagnosed in 27 patients. All patients required surgical intervention. Talus fractures were the most commonly missed injury. In patients with multiple peritalar injuries, there was a strong correlation between talus and navicular fractures (r = -0.60; P < .01) as well as a moderate correlation between talus fractures and calcaneocuboid dislocations (r = -0.46; P = .02). The presence of a calcaneal fracture significantly decreased the time to definitive diagnosis (P = .01). Male patients' diagnoses were delayed an average of 324 days and females 105 days (P = .04). A moderate correlation was found between patient age at injury and time to diagnosis (r = -0.47; P = .04), with a decreased time to diagnosis as patient age increased. Significant factors were identified in this patient population, including patient sex and age, which may contribute to missed or delayed diagnosis in the clinical setting. Prompt and accurate diagnosis of peritalar injuries may improve long-term outcomes.

LEVELS OF EVIDENCE

Care Management, Level V.

Accessory talar facet impingement in pathologic conditions of the peritalar region in adults

INTRODUCTION

Associations between accessory anterolateral talar facet (AALTF) and sinus tarsi pain in adults have not been reported. This study aimed to investigate the clinical and imaging characteristics of pathologic conditions of the peritalar region in adults with painful accessory talar facet impingement (ATFI).

METHODS

We included 31 patients (aged 19-75 years) with persistent sinus tarsi pain who underwent surgery and had pathologic conditions of the peritalar region, including adult acquired flatfoot deformity (AAFD; 18 patients), ankle osteoarthritis (8 patients), and ankle instability (5 patients). Continuity between the articular surface of the posterior facet of the talus and AALTF was identified on preoperative computed tomography and magnetic resonance imaging (MRI) of the cartilage. In addition, focal abutting bone marrow edema (FABME) of the talus and calcaneal neck around the AALTF on short TI inversion recovery sequence MRI was confirmed. Subtalar arthroscopy was used to evaluate the AALTF surface characteristics. Pre- and postoperative objective scores were compared. Eight pre- and postoperative radiographic parameters were compared to confirm the effect of foot alignment changes after reconstructions on sinus tarsi pain with ATFI. Pre- and postoperative changes in FABME were compared with 17.1 (7-60) months of follow-up.

RESULTS

Subjects underwent accessory facet resection with balancing reconstruction. Arthroscopically, 66% of patients showed a focal defect on the AALTF cartilage surface, and 83% showed attenuation of the posterior capsular ligament. All x-ray parameters in AAFD patients showed significant improvement postoperatively (P < .001). Mean objective scores improved from 54.0 preoperatively to 91.0 postoperatively (P < .001). Sinus tarsi pain and FABME were absent in all cases at the final follow-up.

CONCLUSION

AALTF represents a new etiology of subsequent painful intra-articular talocalcaneal impingement. When addressing sinus tarsi pain, it is important to detect the signs of AALTF on MRI of the cartilage and accompanying FABME.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Gait analysis in orthopedic foot and ankle surgery--topical review, part 1: principles and uses of gait analysis

Gait analysis, the systematic study of human walking, is a field that has been studied for well over 100 years. With the technological and scientific advancements of the last several decades, there has been substantial improvement in our understanding of the mechanics of human walking. Particularly important has been the advancement in understanding of the differences between normal and pathological gait. The purpose of this paper is to review the principles of gait analysis, with a particular focus on the underlying methods and science. This will assist orthopedic foot and ankle surgeons in better understanding the methods and meaning of gait research and the publications that commonly appear in the orthopedic foot and ankle surgery literature.

LEVEL OF EVIDENCE

Level V, expert opinion.

Arthrodesis of the talonavicular joint using angle-stable mini-plates: a prospective study

PURPOSE

The talonavicular joint is a central connection of the human foot. Symptomatic talonavicular arthritis can be adequately addressed by isolated talonavicular fusion. However, non-union remains a relevant clinical challenge to the orthopaedic surgeon. The aim of this study was to analyse the clinicoradiological outcome of talonavicular fusion using angle-stable mini-plates.

METHODS

We performed 30 talonavicular fusions in 30 patients (12 male, 18 female) with a mean age of 58.8 years (range, 22-74) between 2005 and 2007. Osseous joint fusion was achieved using mono- and multidirectional angle-stable mini-plates. The patients followed a standardised immobilisation and weight bearing protocol. The mean postoperative follow up was 15.8 months (6.1-23.8).

RESULTS

The American Orthopedic Foot and Ankle Society AOFAS score increased significantly from 31.7 (19-42) to 82.3 points (55-97) (p < 0.001). Neither age at operation nor gender influenced the score results significantly, while the aetiology of talonavicular degeneration showed a significant effect. Mean visual analogue scale (VAS) pain intensity (0-10) reduced from 8.6 to 1.7 (p < 0.001). Good or excellent results were achieved in 26 patients, while two patients reported fair and another two poor results. Complete osseous fusion was observed at a mean of 10.9 weeks (8-13) postoperatively.

CONCLUSIONS

For the treatment of talonavicular arthritis, the application of mono- and multidirectional angle-stable mini-plates provided a strong fixation that led to high union rates and good to excellent overall outcome.

Chronic ankle instability: biomechanics and pathomechanics of ligaments injury and associated lesions

The objective of this study was to evaluate the conditions of ankle stability and the morphological and/or lesional factors in sprains that determine when instability becomes chronic. It is based on a review of the literature and the data from the 2008 Sofcot symposium. The biomechanics of the ankle cannot be reduced to a simple flexion-extension movement with one degree of freedom as characterized by the talocrural joint: its function cannot be dissociated from the subtalar joint, allowing the foot to adapt to the ground surface. Functional stability is related to the combination of the particular biometry of the joint surfaces and a multiaxial ligament system. The bone morphology of the talus, shaped like a truncated cone, explains the potential instability in plantar flexion; the radii of curvature of the talar dome have a variable mediolateral distribution: most often the medial radius of curvature is inferior to the lateral radius of curvature (66%), sometimes equal (19%), or inverted (15%). Joint kinematics, combining rotation and slide, can therefore be modulated by the talar morphology, explaining the occurrence of at-risk ankles. Ligament stability relies on the organization in three parts of the lateral collateral ligament and the specific subtalar ligaments: the cervical and the talocalcaneal interosseous ligament. The different injury mechanisms are largely responsible for the sequence of ligament lesions: the most frequent is inversion. The first ligament stabilizers correspond to the cervical and anterior talofibular ligaments; the talocalcaneal ligament, by its oblique orientation, is solicited when there is a dorsal varus-flexion component. In chronic instability, these mechanisms explain the onset of associated lesions (impingement, osteochondral lesions, fibular tendon pathology), which can play a role in instability syndrome. Ligament lesions determine laxity, characteristic of mechanical instability. Functional instability goes along with proprioceptive deficiency. There are postural factors such as varus of the hindfoot that favor instability. Knowledge of all these factors, often associated, will provide a precise lesional assessment and treatment adapted to the instability.

Biomechanics and clinical analysis of the adult acquired flatfoot

The adult acquired flatfoot is a deformity that results from the loss of dynamic and static supportive structures of the medial longitudinal arch. The severity of the deformity is dependent upon the role of ligamentous disruption on the hindfoot that can be determined by careful clinical examination. Treatment of the adult flatfoot requires an understanding of the biomechanical effects of deforming forces, tendon dysfunction, ligament disruption, and joint sublaxation.