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Purpose: The use of total ankle arthroplasty (TAA) is increasing over time, as so will the need for revision TAAs in the future. Restoration of the ankle joint line (JL) in revision TAA is often difficult due to severe bone loss. This study analyzed the accuracy of a three-dimensional (3D) registration of the contralateral tibia and fibula to restore the ankle joint line (JL) and reported side-to-side differences of anatomical landmarks. Methods: 3D triangular surface models of 96 paired lower legs underwent a surface registration algorithm for superimposition of the mirrored contralateral lower leg onto the original lower leg to approximate the original ankle JL using a proximal, middle and distal segment. Distances of the distal fibular tip, anterior and posterior medial colliculus to the JL were measured and absolute side-to-side differences reported. Anterior lateral distal tibial angle (ADTA) and lateral distal tibial angle (LDTA) were measured. Results: Mean JL approximation was most accurate for the distal segment (0.1 ± 1.4 mm (range: -3.4 to 2.8 mm)) and middle segment (0.1 ± 1.2 mm (range: -2.8 to 2.5 mm)) compared to the proximal segment (-0.2 ± 1.6 mm (range: -3.0 to 4.9 mm)) (p = 0.007). Distance of the distal fibular tip, the anterior, and posterior medial colliculus to the JL, ADTA and LDTA yielded no significant side-to-side differences (n.s.). Conclusion: 3D registration of the contralateral tibia and fibula reliably approximated the original ankle JL. The contralateral distal fibular tip, anterior and posterior medial colliculi, ADTA and LDTA can be used reliably for the planning of revision TAA with small side-to-side differences reported. Level of Evidence: IV. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

An established treatment strategy in surgical site infection after hindfoot and ankle surgery is a two‐stage procedure with debridement and placement of a cement spacer, followed by antibiotic treatment and secondary arthrodesis. However, there is little evidence to favor this treatment over a one‐stage procedure with debridement, followed by primary arthrodesis with an Ilizarov external fixator and antibiotic treatment. We compared the infection control and clinical and radiological outcome of a two‐stage and a one‐stage procedure. In this study, 7 patients with a two‐stage revision and 11 patients with a one‐stage revision between 2005 and 2015 were included. The primary outcome was infection control (absence of the Musculoskeletal Infection Society PJI criteria) 2 years after the ankle or hindfoot arthrodesis. Secondary outcome measures were the AOFAS hindfoot score and radiological consolidation rate. Infection control was 85% (6 out of 7 patients) in the two‐stage group and 81% (9 out of 11 patients) in the one‐stage group (p = 1.0). One patient (14%) of the two‐stage and two patients (18%) in the one‐stage group needed below‐knee amputation. In the two‐stage group, the mean postoperative AOFAS score was 74.8 (SD: ±11.3) versus 71.7 (SD: ±17.8) in the one‐stage group. Radiological consolidation could be achieved in 71% in the spacer group (n = 5) and in 72% in the Ilizarov external fixator group (n = 9). Infection control, AOFAS score, and radiologic consolidation of hindfoot and ankle arthrodesis were comparable in both groups of patients with complicated postsurgical hindfoot or ankle infections. [ABSTRACT FROM AUTHOR]

Axial plane alignment of the talar component in total ankle arthroplasty is poorly understood and remains a major issue, especially since malpositioning results in increased peak pressure and rotational torque. Further profound knowledge regarding individual anatomy of the talus and its relation to proximal and distal osseous structures is therefore needed. Therefore, three‐dimensional (3D) surface models of 50 lower extremities were generated using computed tomography data of patients without ankle osteoarthritis. The talus neck torsion was measured using a novel 3D measurement method. Then, tibial torsion and subtalar joint axis orientation were measured and correlated to the talus neck torsion. Moreover, a 2D measurement method of the talus neck torsion was developed. A statistically significant correlation was found between external tibia torsion and medial talus neck torsion, as well as talus neck axis and subtalar joint axis in the transversal and frontal plane. The novel defined 3D measurement methods indicated excellent inter‐rater and intra‐rater reliability. The 2D measurement method of the talus neck torsion was in good agreement with the 3D method. The results showed that the rotational profiles of the tibia, talus, and adjacent joints are interconnected, which should be considered in total ankle replacement (TAR). Clinical relevance: This study improves the overall understanding of the talar anatomy, as well as its relationship to adjacent osseous structures. The novel 2D measurement method of the talus neck torsion might improve talar component positioning in the axial plane corresponding to the patient's individual anatomy, and therefore improve the survival rate of TAR. [ABSTRACT FROM AUTHOR]

Introduction: Haemophilic ankle arthropathy is caused by recurrent spontaneous joint haemorrhaging and leads to pain, deformity and loss of function. In the presence of advanced articular deterioration, therapeutic options are confined to either arthroplasty or arthrodesis, the latter still being referred to as the procedure of choice. However, total ankle replacement (TAR) has recently gained acceptance as an alternative. Aim: To investigate the mid‐ to long‐term results of TAR in haemophilic ankle arthropathy. Materials and Methods: Seventeen TARs in 14 male patients (mean age: 43 years [range, 27.4‐57.6]), implanted between 1998 and 2012, were retrospectively analysed. Implant survival was estimated using Kaplan‐Meier analysis. Haemophilic/viral status, complications and revision surgeries were recorded. Follow‐up assessment of 12 TARs was performed 9.6 years (range, 3.3‐17.8) postoperatively, including clinical examination, pain and satisfaction scales, the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score, and the SF‐36. Radiographic evaluation of pre‐ and follow‐up radiographs was conducted. Results: Estimated implant survival was 94% at 5, 85% at 10 and 70% at 15 years, respectively. Three cases required revision surgery. At follow‐up, 9.6 years (range, 3.3‐17.8) postoperatively, the level of satisfaction was 76% (range, 50‐100) and of pain 2/10 (range, 0‐6) on the VAS. Range of motion had increased significantly (P = .037). The SF‐36 summary scores were comparable to those of a matched standard population. The AOFAS hindfoot score averaged 81 points (range, 73‐90). All radiographs revealed component loosening or periprosthetic radiolucency. Conclusion: Total ankle replacement in the presence of advanced haemophilic arthropathy is a viable treatment option with favourable mid‐/long‐term results, maintaining mobility of the ankle joint. [ABSTRACT FROM AUTHOR]

ABSTRACT Osteoarthritis (OA) of the glenohumeral joint constitutes the most frequent indication for nontraumatic shoulder joint replacement. Recently, a small critical shoulder angle (CSA) was found to be associated with a high prevalence of OA. This study aims to verify the hypothesis that a small CSA leads to higher glenohumeral joint reaction forces during activities of daily living than a normal CSA. A shoulder simulator with simulated deltoid (DLT), supraspinatus (SSP), infraspinatus/teres minor (ISP/TM), and subscapularis (SSC) musculotendinous units was constructed. The DLT wrapping on the humerus was simulated using a pulley that could be horizontally adjusted to simulate the 28° CSA found in OA or the 33° CSA found in disease-free shoulders. Over a range of motion between 6° and 82° of thoracohumeral abduction joint forces were measured using a six-axis load cell. An OA-associated CSA yielded higher net joint reaction forces than a normal CSA over the entire range of motion. The maximum difference of 26.4 N (8.5%) was found at 55° of thoracohumeral abduction. Our model thus suggests that a CSA typical for OA predisposes the glenohumeral joint to higher joint reaction forces and could plausibly play a role in joint overloading and development of OA. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1047-1052, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT Shoulders with rotator cuff tears (RCT) tears are associated with significantly larger critical shoulder angles (CSA) (RCT CSA = 38.2°) than shoulders without RCT (CSA = 32.9°). We hypothesized that larger CSAs increase the ratio of glenohumeral joint shear to joint compression forces, requiring substantially increased compensatory supraspinatus loads to stabilize the arm in abduction. A previously established three dimensional (3D) finite element (FE) model was used. Two acromion shapes mimicked the mean CSA of 38.2° found in patients with RCT and that of a normal CSA (32.9°). In a first step, the moment arms for each muscle segment were obtained for 21 different thoracohumeral abduction angles to simulate a quasi-static abduction in the scapular plane. In a second step, the muscle forces were calculated by minimizing the range of muscle stresses able to compensate an external joint moment caused by the arm weight. If the joint became unstable, additional force was applied by the rotator cuff muscles to restore joint stability. The model showed a higher joint shear to joint compressive force for the RCT CSA (38.2°) for thoracohumeral abduction angles between 40° and 90° with a peak difference of 23% at 50° of abduction. To achieve stability in this case additional rotator cuff forces exceeding physiological values were required. Our results document that a higher CSA tends to destabilize the glenohumeral joint such that higher than normal supraspinatus forces are required to maintain modeled stability during active abduction. This lends strong support to the concept that a high CSA can induce supraspinatus (SSP) overload. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:961-968, 2016. [ABSTRACT FROM AUTHOR]

ABSTRACT Shoulders with supraspinatus (SSP) tears are associated with significantly larger critical shoulder angles (CSA) compared to disease-free shoulders. We hypothesized that larger CSAs increase the ratio of joint shear to joint compression forces (defined as 'instability ratio'), requiring substantially increased compensatory supraspinatus loads. A shoulder simulator with simulated deltoid, supraspinatus, infraspinatus/teres minor, and subscapularis musculotendinous units was constructed. The model was configured to represent either a normal CSA of 33° or a CSA characteristic of shoulders with rotator cuff tears (38°), and the components of the joint forces were measured. The instability ratio increased for the 38° CSA compared with the control CSA (33°) for a range of motion between 6° to 61° of thoracohumeral abduction with the largest differences in instability observed between 33° and 37° of elevation. In this range, SSP force had to be increased by 13-33% (15-23 N) to stabilize the arm in space. Our results support the concept that a high CSA can induce SSP overload particularly at low degrees of active abduction. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:952-957, 2014. [ABSTRACT FROM AUTHOR]