Conventional vs Augmented Reality-Guided Lateral Calcaneal Lengthening Simulated in a Foot Bone Model.

BACKGROUND: Acquired adult flatfoot deformity (AAFD) results in a loss of the medial longitudinal arch of the foot and dysfunction of the posteromedial soft tissues. Hintermann osteotomy (H-O) is often used to treat stage II AAFD. The procedure is challenging because of variations in the subtalar facets and limited intraoperative visibility. We aimed to assess the impact of augmented reality (AR) guidance on surgical accuracy and the facet violation rate. METHODS: Sixty AR-guided and 60 conventional osteotomies were performed on foot bone models. For AR osteotomies, the ideal osteotomy plane was uploaded to a Microsoft HoloLens 1 headset and carried out in strict accordance with the superimposed holographic plane. The conventional osteotomies were performed relying solely on the anatomy of the calcaneal lateral column. The rate and severity of facet joint violation was measured, as well as accuracy of entry and exit points. The results were compared across AR-guided and conventional osteotomies, and between experienced and inexperienced surgeons. RESULTS: Experienced surgeons showed significantly greater accuracy for the osteotomy entry point using AR, with the mean deviation of 1.6 ± 0.9 mm (95% CI 1.26, 1.93) compared to 2.3 ± 1.3 mm (95% CI 1.87, 2.79) in the conventional method (P = .035). The inexperienced had improved accuracy, although not statistically significant (P = .064), with the mean deviation of 2.0 ± 1.5 mm (95% CI 1.47, 2.55) using AR compared with 2.7 ± 1.6 mm (95% CI 2.18, 3.32) in the conventional method. AR helped the experienced surgeons avoid full violation of the posterior facet (P = .011). Inexperienced surgeons had a higher rate of middle and posterior facet injury with both methods (P = .005 and .021). CONCLUSION: Application of AR guidance during H-O was associated with improved accuracy for experienced surgeons, demonstrated by a better accuracy of the osteotomy entry point. More crucially, AR guidance prevented full violation of the posterior facet in the experienced group. Further research is needed to address limitations and test this technology on cadaver feet. Ultimately, the use of AR in surgery has the potential to improve patient and surgeon safety while minimizing radiation exposure. CLINICAL RELEVANCE: Subtalar facet injury during lateral column lengthening osteotomy represents a real problem in clinical orthopaedic practice. Because of limited intraoperative visibility and variable anatomy, it is hard to resolve this issue with conventional means. This study suggests the potential of augmented reality to improve the osteotomy accuracy.

A Smaller Tibiotalar Sector Is a Risk Factor for Recurrent Anterolateral Ankle Instability after a Modified Broström-Gould Procedure.

BACKGROUND: Several demographic and clinical risk factors for recurrent ankle instability have been described. The main objective of this study was to investigate the potential influence of morphologic characteristics of the ankle joint on the occurrence of recurrent instability and the functional outcomes following a modified Broström-Gould procedure for chronic lateral ankle instability. METHODS: Fifty-eight ankles from 58 patients (28 males and 30 females) undergoing a modified Broström-Gould procedure for chronic lateral ankle instability between January 2014 and July 2021 were available for clinical and radiological evaluation. Based on the preoperative radiographs, the following radiographic parameters were measured: talar width (TW), tibial anterior surface (TAS) angle, talar height (TH), talar radius (TR), tibiotalar sector (TTS), and tibial lateral surface (TLS) angle. The history of recurrent ankle instability and the functional outcome using the Karlsson Score were assessed after a minimum follow-up of 2 years. RESULTS: Recurrent ankle instability was reported in 14 patients (24%). The TTS was significantly lower in patients with recurrent ankle instability (69.8 degrees vs 79.3 degrees) (P < .00001). The multivariate logistic regression model confirmed the TTS as an independent risk factor for recurrent ankle instability (OR = 1.64) (P = .003). The receiver operating characteristic curve analysis revealed that patients with a TTS lower than 72 degrees (=low-TTS group) had an 82-fold increased risk for recurrent ankle instability (P = .001). The low-TTS group showed a significantly higher rate of recurrent instability (58% vs 8%; P = .0001) and a significantly lower Karlsson score (65 points vs 85 points; P < .00001). CONCLUSION: A smaller TTS was found to be an independent risk factor for recurrent ankle instability and led to poorer functional outcomes after a modified Broström-Gould procedure. LEVEL OF EVIDENCE: Level IV, retrospective cohort study.

Bilateral External Torque CT Reliably Detects Syndesmotic Lesions in an Experimental Cadaveric Study.

BACKGROUND: If tibiofibular syndesmotic injury is undetected, chronic instability may lead to persistent pain and osteoarthritis. So far, no reliable diagnostic method has been available. The primary objectives of this study were to determine whether defined lesions of the syndesmosis can be correlated with specific tibiofibular joint displacements caused by external rotational torque and to compare the performance of bilateral external torque computed tomography (BET-CT) and arthroscopy. Secondary objectives included an evaluation of the reliability of CT measurements and the suitability of the healthy contralateral ankle as a reference. METHODS: Seven pairs of healthy, cadaveric lower legs were tested and assigned to 2 groups: (1) supination-external rotation (SER) and (2) pronation-external rotation (PER). In the intact state and after each surgical step, an ankle arthroscopy and 3 CT scans were performed. During the scans, the specimens were placed in an external torque device with 2.5, 5.0, and 7.5 Nm of torque applied. RESULTS: The arthroscopic and CT parameters showed significant correlations in all pairwise comparisons. The receiver operating characteristic (ROC) curve analyses yielded the best prediction of syndesmotic instability with the anterior tibiofibular distance on CT, with a sensitivity of 84.1% and a specificity of 95.2% (area under the curve [AUC], 94.8%; 95% confidence interval [CI], 0.916 to 0.979; p < 0.0001) and with the middle tibiofibular distance on arthroscopy, with a sensitivity of 76.2% and specificity of 92.3% (AUC, 91.2%; 95% CI, 0.837 to 0.987; p < 0.0001). Higher torque amounts increased the rate of true-positive results. CONCLUSIONS: BET-CT reliably detects experimental syndesmotic rotational instability, compared with the healthy side, with greater sensitivity and similar specificity compared with the arthroscopic lateral hook test. Translation of these experimental findings to clinical practice remains to be established. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Talocalcaneal Ligament Reconstruction Kinematic Simulation for Progressive Collapsing Foot Deformity.

BACKGROUND: In progressive collapsing foot deformity (PCFD), an internal and plantar rotation of the talus relative to the calcaneus may result in painful peritalar subluxation. Medial soft tissue procedures (eg, spring ligament repair) aim to correct the talar position via the navicular bone if bony correction alone is not sufficient. The effect of the medial soft tissue reconstruction on the talar reposition remains unclear. We hypothesized that a subtalar talocalcaneal ligament reconstruction might be favorable in PCFD to correct talar internal malposition directly. This pilot study aims to evaluate the anatomical feasibility and kinematic behavior of a subtalar ligament reconstruction in PCFD. METHODS: Three-dimensional surface model from 10 healthy ankles were produced. A total of 1089 different potential ligament courses were evaluated in a standardized manner. A motion of inversion/eversion and talar internal/external in relation to the calcaneus were simulated and the ligament strain, expressed as a positive length variation, for each ligament was analyzed. The optimal combination for the ligament reconstruction with increased length in internal rotation of the talus, isometric kinematic behavior in inversion/eversion, and extraarticular insertion on talus and calcaneus was selected. RESULTS: A laterodistal orientation of the talar insertion point in respect to the subtalar joint axis and laterodistal deviation of the calcaneal insertion point presents the highest ligament lengthening in internal talar rotation (+0.56 mm [3.8% of total length]) and presented a near-isometric performance in inversion/eversion (+0.01 to -0.01 mm [0.1% of total length]). CONCLUSION: This kinematic model shows that a ligament reconstruction in the subtalar space presents a pattern of length variation that may stabilize the internal talar rotation without impeding the physiological subtalar motion. CLINICAL RELEVANCE: This study investigates the optimal location, feasibility, and kinematic behavior of a ligament reconstruction that could help stabilize peritalar subluxation in progressive collapsing foot deformity.[Formula: see text].

Ten-Year Minimum Follow-up Study of First Metatarsophalangeal Joint Fusion in Young vs Old Patients.

BACKGROUND: Painful degenerative joint disease (DJD) of the first metatarsophalangeal joint (MTP I), or hallux rigidus, mainly occurs in later stages of life. For end-stage hallux rigidus, MTP I arthrodesis is considered the gold standard. As young and active patients are affected considerably less frequently, it currently remains unclear, whether they benefit to the same extent. We hypothesized that MTP I arthrodesis in younger patients would lead to an inferior outcome with decreased rates of overall with lower rates of patient postoperative pain and function compared to an older cohort. METHODS: All patients aged <50 years who underwent MTP I arthrodesis at our institution between 1995 and 2012 were included in this study. This group was then matched and compared with a group of patients aged >60 years. Minimum follow-up was 10 years. Outcome measures were Tegner activity score (TAS), a "Virtual Tegner activity score" (VTAS), the visual analog scale (VAS), and the Foot Function index (FFI). RESULTS: Sixty-one MTP I fusions (n = 28 young, n = 33 old) in 46 patients were included in our study at an average of 14 years after surgery. Younger patients experienced significantly more pain relief as reflected by changes in VAS and FFI Pain subscale scores. No difference in functional outcomes was found with change in the FFI function subscale or in the ability to have desired functional outcomes using the ratio of TAS to VTAS. Revision rate did not differ between the two groups apart from hardware removal, which was significantly more likely in the younger group. CONCLUSION: In patients below the age of 50 years with end-stage DJD of the first metatarsal joint, MTP I arthrodesis not only yielded highly satisfactory postoperative results at least equal outcome compared to an older cohort of patients aged >60 years at an average 14 years' follow-up. Based on these findings, we consider first metatarsal joint fusion even for young patients is a valid option to treat end-stage hallux rigidus. LEVEL OF EVIDENCE: Level III, a case-control study.

The Unloading Effect of Supramalleolar Versus Sliding Calcaneal Osteotomy for Treatment of Osteochondral Lesions of the Medial Talus: A Biomechanical Study.

Background: In patients with osteochondral lesion, defects of the medial talus, or failed cartilage surgery, a periarticular osteotomy can unload the medial compartment. Purpose: To compare the effects of supramalleolar osteotomy (SMOT) versus sliding calcaneal osteotomy (SCO) for pressure redistribution and unloading of the medial ankle joint in normal, varus-aligned, and valgus-aligned distal tibiae. Study Design: Controlled laboratory study. Methods: Included were 8 cadaveric lower legs with verified neutral ankle alignment (lateral distal tibial angle [LDTA] = 0°) and hindfoot valgus within normal range (0°-10°). SMOT was performed to modify LDTA between 5° valgus, neutral, and 5° varus. In addition, a 10-mm lateral SCO was performed and tested in each position in random order. Axial loading (700 N) of the tibia was applied with the foot in neutral alignment in a customized testing frame. Pressure distribution in the ankle joint and subtalar joint, center of force, and contact area were recorded using high-resolution Tekscan pressure sensors. Results: At neutral tibial alignment, SCO unloaded the medial joint by a mean of 10% ± 10% or 66 ± 51 N (P = .04) compared with 6% ± 12% or 55 ± 72 N with SMOT to 5° valgus (P = .12). The achieved deload was not significantly different (ns) between techniques. In ankles with 5° varus alignment at baseline, SMOT to correct LDTA to neutral insufficiently addressed pressure redistribution and increased medial load by 6% ± 9% or 34 ± 33 N (ns). LDTA correction to 5° valgus (10° SMOT) unloaded the medial joint by 0.4% ± 14% or 20 ± 75 N (ns) compared with 9% ± 11% or 36 ± 45 N with SCO (ns). SCO was significantly superior to 5° SMOT (P = .017) but not 10° SMOT. The subtalar joint was affected by both SCO and SMOT, where SCO unloaded but SMOT loaded the medial side. Conclusion: SCO reliably unloaded the medial compartment of the ankle joint for a neutral tibial axis. Changes in the LDTA by SMOT did not positively affect load distribution, especially in varus alignment. The subtalar joint was affected by SCO and SMOT in opposite ways, which should be considered in the treatment algorithm. Clinical Relevance: SCO may be considered a reliable option for beneficial load-shifting in ankles with neutral alignment or 5° varus malalignment.

[Three-dimensional analysis of posttraumatic tibial shaft malunion and correction based on the healthy, contralateral leg]. / 3-D-Analyse von posttraumatischen Tibiaschaftfehlstellungen und deren Korrektur anhand der gesunden Gegenseite.

OBJECTIVE: Three-dimensional (3D) analysis and implementation with patient-specific cutting and repositioning blocks enables correction of complex tibial malunions. Correction can be planned using the contralateral side or a statistical model. Patient-specific 3D-printed cutting guide blocks enable a precise osteotomy and reduction guide blocks help to achieve anatomical reduction. Depending on the type and extent of correction, fibula osteotomy may need to be considered to achieve the desired reduction. CONTRAINDICATIONS: a) Poor soft tissue (flap surgery, adherent skin in field of operation); b) infection; c) peripheral artery disease (stage III and IV classified according to Fontaine, critical transcutaneous oxygen partial pressure, TcPO2); d) general contraindication to surgery. SURGICAL TECHNIQUE: Before surgery, a 3D model of both lower legs is created based on computed tomography (CT) scans. Analysis of the deformity based on the contralateral side in a 3D computer model (CASPA) and planning of the osteotomy. If the contralateral side also has a deformity, a statistical model can be used. Printing of patient-specific guides made of nylon (PA2200) for the osteotomy and reduction. Surgery is performed in supine position, antibiotic prophylaxis, thigh tourniquet, which is used as needed. Ventrolateral approach to the tibia. Attachment of the patient-specific osteotomy guide, performance of the osteotomy. Reduction using the guide. Fibula osteotomy through a lateral approach is performed if the reduction of the tibia is hindered by the fibula. This can be performed freehand or with patient-specific guides. Wound closure. POSTOPERATIVE MANAGEMENT: Compartment monitoring. Passive mobilization of the ankle in the cast as soon as the wound healing has progressed. Partial weightbearing in a lower leg cast for at least 6-12 weeks, depending on the routinely performed radiographic assessment 6 weeks postoperatively. Thromboprophylaxis with low molecular weight heparin until cast removal. RESULTS: Patient-specific correction of malunions are generally good. This could be confirmed for distal tibial corrections. For tibial shaft deformities, the final results are still pending. Preliminary results, however, show good feasibility with a pseudarthrosis rate of 10% without postoperative infection.

Typical Complications After Cartilage Repair of the Ankle Using Autologous Matrix-Induced Chondrogenesis (AMIC).

Background: Autologous matrix-induced chondrogenesis (AMIC) for the treatment of osteochondral lesions of the talus (OLT) results in favorable clinical outcomes, yet high reoperation rates. The aim of this study was to report and analyze typical complications and their risk factors after AMIC for OLT. Methods: A total of 127 consecutive patients with 130 AMIC procedures for OLT were retrospectively assessed. All AMIC procedures were performed in an open fashion with 106 (81.5%) cases requiring a malleolar osteotomy (OT) to access the OLT. Seventy-one patients (54.6%) underwent subsequent surgery. These cases were evaluated at a mean follow-up of 3.1 years (±2.5) for complications reviewing postoperative imaging and intraoperative findings during revision surgery. Six patients (8.5%) were lost to follow-up. Regression model analysis was conducted to identify factors that were associated with AMIC-related complications. Results: Among the 65 (50%) patients who required revision surgery, 18 patients (28%) demonstrated AMIC-related complications with deep fissuring (83%) and thinning (17%) of the AMIC graft. Conversely, 47 patients (72%) underwent subsequent surgery due to AMIC-unrelated reasons including isolated removal of symptomatic hardware (n = 17) and surgery addressing concomitant pathologies with (n = 25) and without hardware removal (n = 5). Previous prior cartilage repair surgery was significantly associated with AMIC graft-associated complications in patients undergoing revision surgery (P = .0023). Among age, body mass index, defect size, smoking, and bone grafting, smoking was the only factor showing statistical significance with an odds ratio of 3.7 (95% CI 1.24, 10.9; P = .019) to undergo revision surgery due to graft-related complications, when adjusted for previous cartilage repair surgery. Conclusion: The majority of revision surgeries after AMIC for OLT are unrelated to the performed AMIC graft but frequently address symptomatic hardware and concomitant pathologies. Both smoking and previous cartilage repair surgery seem to significantly increase the risk of undergoing revision surgery due to AMIC-related complications. Level of evidence: Level IV, case series.

Ulcer occurrence on adjacent toes and hallux valgus deformity after amputation of the second toe in diabetic patients.

BACKGROUND: Amputation of the second toe is associated with destabilization of the first toe. Possible consequences are hallux valgus deformity and subsequent pressure ulcers on the lateral side of the first or on the medial side of the third toe. The aim of this study was to investigate the incidence and possible influencing factors of interdigital ulcer development and hallux valgus deformity after second toe amputation. METHODS: Twenty-four cases of amputation of the second toe between 2004 and 2020 (mean age 68 ± 12 years; 79% males) were included with a mean follow-up of 36 ± 15 months. Ulcer development on the first, third, or fourth toe after amputation, the body mass index (BMI) and the amputation level (toe exarticulation versus transmetatarsal amputation) were recorded. Pre- and postoperative foot radiographs were evaluated for the shape of the first metatarsal head (round, flat, chevron-type), the hallux valgus angle, the first-second intermetatarsal angle, the distal metatarsal articular angle and the hallux valgus interphalangeal angle by two orthopedic surgeons for interobserver reliability. RESULTS: After amputation of the second toe, the interdigital ulcer rate on the adjacent toes was 50% and the postoperative hallux valgus rate was 71%. Neither the presence of hallux valgus deformity itself (r = .19, p = .37), nor the BMI (r = .09, p = .68), the shape of the first metatarsal head (r = - .09, p = .67), or the amputation level (r = .09, p = .69) was significantly correlated with ulcer development. The interobserver reliability of radiographic measurements was high, oscillating between 0.978 (p = .01) and 0.999 (p = .01). CONCLUSIONS: The interdigital ulcer rate on the first or third toe after second toe amputation was 50% and hallux valgus development was high. To date, evidence on influencing factors is lacking and this study could not identify parameters such as the BMI, the shape of the first metatarsal head or the amputation level as risk factors for the development of either hallux valgus deformity or ulcer occurrence after second toe amputation. TRIAL REGISTRATION: BASEC-Nr. 2019-01791.

Risk Factors for Surgical Site Infections in Elective Orthopedic Foot and Ankle Surgery: The Role of Diabetes Mellitus.

Surgical site infection (SSI) after elective orthopedic foot and ankle surgery is uncommon and may be higher in selected patient groups. Our main aim was to investigate the risk factors for SSI in elective orthopedic foot surgery and the microbiological results of SSI in diabetic and non-diabetic patients, in a tertiary foot center between 2014 and 2022. Overall, 6138 elective surgeries were performed with an SSI risk of 1.88%. The main independent associations with SSI in a multivariate logistic regression analysis were an ASA score of 3-4 points, odds ratio (OR) 1.87 (95% confidence interval (CI) 1.20-2.90), internal, OR 2.33 (95% CI 1.56-3.49), and external material, OR 3.08 (95% CI 1.56-6.07), and more than two previous surgeries, OR 2.86 (95% CI 1.93-4.22). Diabetes mellitus showed an increased risk in the univariate analysis, OR 3.94 (95% CI 2.59-5.99), and in the group comparisons (three-fold risk). In the subgroup of diabetic foot patients, a pre-existing diabetic foot ulcer increased the risk for SSI, OR 2.99 (95% CI 1.21-7.41), compared to non-ulcered diabetic patients. In general, gram-positive cocci were the predominant pathogens in SSI. In contrast, polymicrobial infections with gram-negative bacilli were more common in contaminated foot surgeries. In the latter group, the perioperative antibiotic prophylaxis by second-generation cephalosporins did not cover 31% of future SSI pathogens. Additionally, selected groups of patients revealed differences in the microbiology of the SSI. Prospective studies are required to determine the importance of these findings for optimal perioperative antibiotic prophylactic measures.

Study protocol: short against long antibiotic therapy for infected orthopedic sites - the randomized-controlled SALATIO trials.

BACKGROUND: Few studies address the appropriate duration of post-surgical antibiotic therapy for orthopedic infections; with or without infected residual implants. We perform two similar randomized-clinical trials (RCT) to reduce the antibiotic use and associated adverse events. METHODS: Two unblinded RCTs in adult patients (non-inferiority with a margin of 10%, a power of 80%) with the primary outcomes "remission" and "microbiologically-identical recurrences" after a combined surgical and antibiotic therapy. The main secondary outcome is antibiotic-related adverse events. The RCTs allocate the participants between 3 vs. 6 weeks of post-surgical systemic antibiotic therapy for implant-free infections and between 6 vs. 12 weeks for residual implant-related infections. We need a total of 280 episodes (randomization schemes 1:1) with a minimal follow-up of 12 months. We perform two interim analyses starting approximately after 1 and 2 years. The study approximatively lasts 3 years. DISCUSSION: Both parallel RCTs will enable to prescribe less antibiotics for future orthopedic infections in adult patients. TRIAL REGISTRATION: ClinicalTrial.gov NCT05499481. Registered on 12 August 2022. PROTOCOL VERSION: 2 (19 May 2022).

The Relationship between Frontal, Axial Leg Alignment, and Ankle Joint Line Orientation-a Radiographic Analysis of Healthy Subjects.

OBJECTIVE: Ankle joint line orientation (AJLO) is influenced by the subtalar foot and frontal leg alignment. However, the influence of axial leg alignment on AJLO remains unclear. The study aimed to analyze the influence of frontal, axial leg alignment on AJLO in healthy subjects. METHODS: Thirty healthy subjects (60 legs) without prior surgery underwent standing biplanar long leg radiograph (LLR) between 2016 and 2020. AJLO was measured in standing long-leg radiographs relative to the ground. Meary's angle and calcaneal pitch were measured. Hip-knee-ankle angle (HKA), femoral antetorsion, and tibial torsion were assessed with SterEOS software (EOS Imaging, Paris, France). LLR was acquired with the feet directing straight anteriorly, which corresponds to a neutral foot progression angle (FPA). The influence of subtalar, frontal, and axial alignment on AJLO was analyzed in a multiple regression model. RESULTS: An increase in knee valgus increased relative valgus AJLO by 0.5° (95% CI: 0.2° to 0.7°) per 1° (P < 0.001). A decrease in femoral antetorsion increased relative valgus AJLO by 0.2° (95% CI: 0.1° to 0.2°) per 1° (P < 0.001), whereas Meary's angle and calcaneal pitch did not influence AJLO. CONCLUSION: A link between frontal, axial leg alignment, and AJLO could be demonstrated, indicating that a valgus leg alignment and relative femoral retrotorsion are associated with an increase of valgus AJLO in healthy subjects when placing their feet in a neutral position. Alteration of the frontal, or rotational profile after realignment surgery or by implant positioning might influence the AJLO, when the FPA is kept constant.

Effect of the Reversed L-Shaped Osteotomy on the Round Sign: Not All Hallux Valgus Deformities May Need Proximal Derotation to Correct the Radiographic Appearance of Metatarsal Pronation.

Background: Metatarsal pronation has been claimed to be a risk factor for hallux valgus recurrence. A rounded shape of the lateral aspect of the first metatarsal head has been identified as a sign of persistent metatarsal pronation after hallux valgus correction. This study investigated the derotational effect of a reversed L-shaped (ReveL) osteotomy combined with a lateral release to correct metatarsal pronation. The primary hypothesis was that most cases showing a positive round sign are corrected by rebalancing the metatarsal-sesamoid complex. We further assumed that the inability to correct the round sign might be a risk factor for hallux valgus recurrence. Methods: We retrospectively evaluated 266 cases treated with a ReveL osteotomy for hallux valgus deformity. The radiologic measurements were performed on weightbearing foot radiographs preoperatively, at an early follow-up (median, 6.2 weeks), and the most recent follow-up (median, 13 months). Univariate and multivariate logistic regression analyses identified risk factors for hallux valgus recurrence (hallux valgus angle [HVA] ≥ 20 degrees). Results: A preoperative positive radiographic round sign was present in 40.2% of the cases, of which 58.9% turned negative after the ReveL osteotomy (P < .001). Hallux valgus recurred in 8.6%. Risk factors for recurrence were a preoperative HVA >30 degrees (odds ratio [OR] = 5.3, P < .001), metatarsus adductus (OR = 4.0, P = .004), preoperative positive round sign (OR = 3.3, P = .02), postoperative HVA >15 degrees (OR = 74.9; P < .001), and postoperative positive round sign (OR = 5.3, P = .008). Cases with a positive round sign at the most recent follow-up had a significantly higher recurrence rate than those with a negative round sign (22.7% vs 5.9%, P < .001). Conclusion: The ReveL osteotomy corrected a positive round sign in 58.9%, suggesting that not all hallux valgus deformities may need proximal derotation to negate the radiographic appearance of the round sign. A positive round sign was found to be an independent risk factor for hallux valgus recurrence. Further 3-dimensional analyses are necessary to better understand the effects and limitations of distal translational osteotomies to correct metatarsal pronation. Level of Evidence: Level IV, case series.

Corpse decay of wild animals leads to the divergent succession of nrfA-type microbial communities.

Animal carcasses introduce large amounts of nitrates and ammonium into the soil ecosystem. Some of this ammonium is transformed from nitrite through the nrfA-type microbial community. However, it is unclear how nrfA-type microorganisms respond to the decomposition of corpses. This study applied high-throughput sequencing to characterize the ecological succession of nrfA-type microbial communities in grassland soil. Our results showed that Cyclobacterium and Trueperella were the predominant genera for nrfA-type communities in soil with a decomposing corpse (experimental group), while Cyclobacterium and Archangium were dominant in soil without a corpse (control group). The alpha diversity indexes and the resistance and resilience indexes of the microbial communities initially increased and then decreased during decomposition. Compared with the control group, nrfA-encoding community structure in the experimental group gradually became divergent with succession and temporal turnover accelerated. Network analysis revealed that the microbial communities of the experimental group had more complex interactions than those of the control groups. Moreover, the bacterial community assembly in the experimental group was governed by stochastic processes, and the communities of the experimental group had a weaker dispersal capacity than those of the control group. Our results reveal the succession patterns of the nrfA-type microbial communities during degradation of wild animal corpses, which can offer references for demonstrating the ecological mechanism underlying the changes in the nrfA-type microbial community during carcass decay. KEY POINTS: • Corpse decay accelerates the temporal turnover of the nrfA-type community in soil. • Corpse decay changes the ecological succession of the nrfA-type community in soil. • Corpse decay leads to a complex co-occurrence pattern of the nrfA-type community in soil.

Isometric points in lateral ankle ligament reconstruction: A three-dimensional kinematic study.

BACKGROUND: To optimize the biomechanical outcomes in lateral ankle ligament reconstruction, avoid stiffness or residual laxity, aiming for an isometric reconstruction of the anterior lateral talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) is mandatory. However, the localization of the optimal ligament insertion remains challenging to assess intraoperatively. METHOD: Three-dimensional (3D) surface models from 10 healthy ankles were generated. 30 insertion points of the CFL were defined on the lateral side of the calcaneus each 10% of its total length in the dorsal-to-ventral and proximal-to-distal plane. 6 insertion points were defined at the ventral ridge of fibula from the malleolar tip and 5 insertions were defined along the lateral talar process. The ligament length variation of ATFL and CFL was assessed after a simulation of the flexion/extension around a simulated tibiotalar axis and inversion/eversion around a simulated subtalar axis in 36 different positions. RESULTS: The isometric point of CFL on the calcaneus is located at about 60% along the dorsal-to-ventral and between 60% and 70% along the proximal-to-distal plane. From maximal extension to flexion, these points present respectively a length variation of - 0.8 to - 1.1 mm (p = 0.46) and - 1.1 to - 0.8 mm (p = 0.56). A fibular insertion at 5 mm proximal to the malleolar tip present a length variation ranging from - 0.1-1 mm (p < 0.001) for ATFL and from - 0.7-0.5 mm (p < 0.001) for CFL. A talar insertion point of the ATFL located 5 mm proximal to the subtalar joint present the lowest variation, ranging from - 1.1-0.7 mm (p < 0.001), however an insertion at 20- or 25-mm present isometry (+0.1 to +0.9 mm p = 0.1, and +0.4 to +0.4 mm p = 1 respectively) if the fibular insertion is located at 5 mm proximal to the malleolar tip. CONCLUSION: This study provides anatomical references which are reproducible in daily practice. These insertion points allow to achieve a stable reconstruction while maintaining a tension-free mobilization of the ankle.

Correlation of Postoperative Imaging With MRI and Clinical Outcome After Cartilage Repair of the Ankle: A Systematic Review and Meta-analysis.

Background: Magnetic resonance imaging (MRI) is commonly used for evaluation of ankle cartilage repair, yet its association with clinical outcome is controversial. This study analyzes the correlation between MRI and clinical outcome after cartilage repair of the talus including bone marrow stimulation, cell-based techniques, as well as restoration with allo- or autografting. Methods: A systematic search was performed in MEDLINE, Embase, and Cochrane Collaboration. Articles were screened for correlation of MRI and clinical outcome. Guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) were used. Chi-square test and regression analysis were performed to identify variables that determine correlation between clinical and radiologic outcome. Results: Of 2687 articles, a total of 43 studies (total 1212 cases) were included with a mean Coleman score of 57 (range, 33-70). Overall, 93% were case series, and 5% were retrospective and 2% prospective cohort studies. Associations between clinical outcome and ≥1 imaging variable were found in 21 studies (49%). Of 24 studies (56%) using the composite magnetic resonance observation of cartilage repair tissue (MOCART) score, 7 (29%) reported a correlation of the composite score with clinical outcome. Defect fill was associated with clinical outcome in 5 studies (12%), and 5 studies (50%) reported a correlation of T2 mapping and clinical outcome. Advanced age, shorter follow-up, and larger study size were associated with established correlation between clinical and radiographic outcome (P = .021, P = .028, and P = .033). Conclusion: Interpreting MRI in prediction of clinical outcome in ankle cartilage repair remains challenging; however, it seems to hold some value in reflecting clinical outcome in patients with advanced age and/or at a shorter follow-up. Yet, further research is warranted to optimize postoperative MRI protocols and assessments allowing for a more comprehensive repair tissue evaluation, which eventually reflect clinical outcome in patients after cartilage repair of the ankle.Level of Evidence: Level III, systematic review and meta-analysis.

Restoration of the patient-specific anatomy of the distal fibula based on a novel three-dimensional contralateral registration method.

PURPOSE: Posttraumatic fibular malunion alters ankle joint biomechanics and may lead to pain, stiffness, and premature osteoarthritis. The accurate restoration is key for success of reconstructive surgeries. The aim of this study was to analyze the accuracy of a novel three-dimensional (3D) registration algorithm using different segments of the contralateral anatomy to restore the distal fibula. METHODS: Triangular 3D surface models were reconstructed from computed tomographic data of 96 paired lower legs. Four segments were defined: 25% tibia, 50% tibia, 75% fibula, and 75% fibula and tibia. A surface registration algorithm was used to superimpose the mirrored contralateral model on the original model. The accuracy of distal fibula restoration was measured. RESULTS: The median rotation error, 3D distance (Euclidean distance), and 3D angle (Euler's angle) using the distal 25% tibia segment for the registration were 0.8° (- 1.7-4.8), 2.1 mm (1.4-2.9), and 2.9° (1.9-5.4), respectively. The restoration showed the highest errors using the 75% fibula segment (rotation error 3.2° (0.1-8.3); Euclidean distance 4.2 mm (3.1-5.8); Euler's angle 5.8° (3.4-9.2)). The translation error did not differ significantly between segments. CONCLUSION: 3D registration of the contralateral tibia and fibula reliably approximated the premorbid anatomy of the distal fibula. Registration of the 25% distal tibia, including distinct anatomical landmarks of the fibular notch and malleolar colliculi, restored the anatomy with increasing accuracy, minimizing both rotational and translational errors. This new method of evaluating malreductions could reduce morbidity in patients with ankle fractures. LEVEL OF EVIDENCE: IV.

The Integrated Effect of Microbial Inoculants and Biochar Types on Soil Biological Properties, and Plant Growth of Lettuce (Lactuca sativa L.).

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development.

A Biomechanical Analysis of Peroneus Brevis Split Lesions, Repair, and Partial Resection.

BACKGROUND: Peroneus brevis tendon tears are associated with chronic ankle pain and instability following sprain injuries. The aim of this study is to elucidate the biomechanical changes induced by a peroneus brevis split and surgical treatment by tubularizing suture or partial resection. METHODS: Nine human lower leg specimens were biomechanically tested. Preexisting tendon pathology was ruled out by magnetic resonance imaging and histology. Specimens were subjected to sequential testing of 4 conditions of the peroneus brevis tendon: (1) native, (2) longitudinal lesion, (3) tubularizing suture, and (4) 50% resection. The outcome parameters were the tendon stiffness (N/mm) and the length variation of the split portion at 5 N load. RESULTS: The median specimen age at death was 55.8 years (range 50-64 years). The longitudinal tendon split led to an elongation by 1.21 ± 1.15 mm, which was significantly reduced by tubularizing suture to 0.24 ± 0.97 mm (P = .021). Furthermore, 50% resection of the tendon elongated it by a mean 2.45 ± 1.9 mm (P = .01) and significantly reduced its stiffness compared to the intact condition (4.7 ± 1.17 N/mm, P = .024) and sutured condition (4.76 ± 1.04 N/mm, P = .011). CONCLUSION: Longitudinal split and 50% resection of the peroneus brevis tendon led to elongation and loss of tendon stiffness. These properties were improved by tubularizing suture. The significance of these changes in the clinical setting needs further investigation. CLINICAL RELEVANCE: Tubularizing suture of a peroneus brevis split can restore biomechanical properties to almost native condition, potentially aiding ankle stability in symptomatic cases. A split lesion and partial resection of the tendon showed reduced stiffness and increased elongation.

Talus morphology differs between flatfeet and controls, but its variety has no influence on extent of surgical deformity correction.

BACKGROUND: Progressive collapsing foot deformity (PCFD) is a complex 3-dimensional (3-D) deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot varus. The first aim of this study was to perform a 3-D analysis of the talus morphology between symptomatic PCFD patients that underwent operative flatfoot correction and controls. The second aim was to investigate if there is an impact of individual talus morphology on the success of operative flatfoot correction. METHODS: We reviewed all patients that underwent lateral calcaneal lengthening for correction of PCFD between 2008 and 2018 at our clinic. Radiographic flatfoot parameters on preoperative and postoperative radiographs were assessed. Additionally, 3-D surface models of the tali were generated using computed tomography (CT) data. The talus morphology of 44 flatfeet was compared to 3-D models of 50 controls without foot or ankle pain of any kind. RESULTS: Groups were comparable regarding demographics. Talus morphology differed significantly between PCFD and controls in multiple aspects. There was a 2.6° increased plantar flexion (22.3° versus 26°; p = 0.02) and medial deviation (31.7° and 33.5°; p = 0.04) of the talar head in relation to the body in PCFD patients compared to controls. Moreover, PCFD were characterized by an increased valgus (difference of 4.6°; p = 0.01) alignment of the subtalar joint. Satisfactory correction was achieved in all cases, with an improvement of the talometatarsal-angle and the talonavicular uncoverage angle of 5.6° ± 9.7 (p = 0.02) and 9.9° ± 16.3 (p = 0.001), respectively. No statistically significant correlation was found between talus morphology and the correction achieved or loss of correction one year postoperatively. CONCLUSION: The different morphological features mentioned above might be contributing or risk factors for progression to PCFD. However, despite the variety of talar morphology, which is different compared to controls, the surgical outcome of calcaneal lengthening osteotomy was not affected. LEVEL OF EVIDENCE: III.