Arne Burssens

Measuring hindfoot alignment in weight bearing CT: A novel clinical relevant measurement method

BACKGROUND A precise pre-operative measurement of hindfoot malalignment is paramount to plan and obtain an accurate surgical correction. Hindfoot alignment is currently determined on standard weightbearing radiographs. However this is hampered by the superposition of the skeletal structures. Recent technology developed weightbearing cone beam CT to overcome this problem. The objective is to introduce a clinically relevant and reproducible method to measure hindfoot alignment on weightbearing CT. METHODS Sixty malalignments of the hindfoot were divided in to two groups; group one containing a valgus alignment (n=30) and group two a varus alignment (n=30) of the hindfoot. Imaging techniques used were standard radiographs and a weightbearing CT (pedCAT®). Following angles were measured by two different authors: standard long axial hindfoot angle both on standard radiographs and on CT, clinical hindfoot, novel hindfoot angle, talar shift (distance from a neutral alignment), tibial inclination angle, talar tilt and subtalar vertical angle on CT. RESULTS Hindfoot alignment angles showed to significantly differ from each other (P<0.001). The novel hindfoot alignment angle showed the highest correlation with the clinical measurement method. Correlation of this novel angle with the talar shift showed a Spearmans correlation coefficient=0.87. Interclass correlation coefficient of the novel hindfoot alignment angle=0.72 and was the highest among the hindfoot alignment angles. CONCLUSION Weightbearing CT is allows to objectively assess hindfoot alignment. The proposed novel hindfoot alignment angle showed to be both clinically relevant and reproducible as compared to previous methods. The lateral tibiocalcaneal shift, on which the angle is highly correlated to, can help the surgeon in determining how much translation is necessary to obtain a neutral alignment during a calcaneal osteotomy. LEVEL OF EVIDENCE Level III: retrospective cohort study.

Weightbearing computed tomography of the foot and ankle : emerging technology topical review

In the last decade, cone-beam computed tomography technology with improved designs allowing flexible gantry movements has allowed both supine and standing weight-bearing imaging of the lower extremity. There is an increasing amount of literature describing the use of weightbearing computed tomography in patients with foot and ankle disorders. To date, there is no review article summarizing this imaging modality in the foot and ankle. Therefore, we performed a systematic literature review of relevant clinical studies targeting the use of weightbearing computed tomography in diagnosis of patients with foot and ankle disorders. Furthermore, this review aims to offer insight to those with interest in considering possible future research opportunities with use of this technology. Level of Evidence: Level V, expert opinion.

Weight-bearing cone beam CT scans in the foot and ankle

The 3D anatomical complexity of the foot and ankle and the importance of weight-bearing in diagnosis have required the combination of conventional radiographs and medical CT. Conventional plain radiographs (XR) have demonstrated substantial limitations such as perspective, rotational and fan distortion, as well as poor reproducibility of radiographic installations. Conventional CT produces high levels of radiation exposure and does not offer weight-bearing capabilities. The literature investigating biometrics based on 2D XR has inherent limitations due to the technology itself and thereby can focus only on whether measurements are reproducible, when the real question is whether the radiographs are. Low dose weight-bearing cone beam CT (WBCT) combines 3D and weight-bearing as well as ‘built in’ reliability validated through industry-standardized processes during production and clinical use (quality assurance testing). Research is accumulating to validate measurements based on traditional 2D techniques, and new 3D biometrics are being described and tested. Time- and cost-efficient use in medical imaging will require the use of automatic measurements. Merging WBCT and clinical data will offer new perspectives in terms of research with the help of modern data analysis techniques. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170066

Endoscopic Guided Tibiotalocalcaneal Arthrodesis After Failed Osteosynthesis of Pilon Fractures

Pilon fractures are difficult to treat because of the fracture pattern and are usually associated with significant soft tissue injury, which may result in a series of complications. Patients with diabetes and sensory neuropathy are at even greater risk of fixation failure, skin flap necrosis and deep infection. Treatment of complicated situations in patients is even more challenging and often results in an amputation. We describe a surgical treatment in two steps. First, we recommend an aggressive debridement to eradicate infection. After recovery of soft tissues, hindfoot fusion with a retrograde intramedullary nail helps to obtain a stable fixation. The removal of the cartilage can be performed endoscopically. This minimizes new soft tissue damage and favours wound healing. This treatment provides the patient with a pain-free plantigrade foot for ambulation.

Influence of investigator experience on reliability of adult acquired flatfoot deformity measurements using weightbearing computed tomography

BACKGROUND Our purpose was to assess the reliability of measurements of adult-acquired flatfoot deformity (AAFD) taken by investigators of different levels of clinical experience using weightbearing computed tomography (WBCT). METHODS Nineteen AAFD patients underwent WBCT. Three investigators with different levels of clinical experience made AAFD measurements in axial, coronal, and sagittal planes. Intra- and interobserver reliability were assessed. Mean values for each measurement were compared between investigators. RESULTS After a training protocol, substantial to perfect intra- and interobserver reliability was observed for most measures, regardless of the investigators experience level. Significant differences between investigators were observed in 2 of 21 measured parameters: medial cuneiform-first metatarsal angle (P=0.003) and navicular-medial cuneiform angle (P=0.001). CONCLUSIONS AAFD radiographic measurements can be performed reliably by investigators with different levels of clinical experience using WBCT. LEVEL OF EVIDENCE Level II, prospective comparative study.

Influence of wrist position on maximum grip force in a post-operative orthosis.

Background: Flexor tendon repair in the hand remains challenging in avoiding tendon rupture and adhesion formation. Post-operative mobilization has been shown to be critical in regaining functional range of motion. Objectives: The objective of this study is 2-fold: to assess the influence of wrist position on maximum grip force generated in a post-operative orthosis and to determine the correlation between this maximum grip force and an individual’s grip strength. Study design: Clinical measurement Methods: A total of 30 uninjured wrists of right-handed men were given a post-operative orthosis with an incorporated Caroli-hinge. The maximum grip force was measured according to a different wrist position ranging from −30° extension until 80° of flexion using a 10° interval. These measurements were plotted out on a graph for regression analysis. A correlation was determined between measurements in a neutral wrist position and maximum grip strength generated without an orthosis. To assess the coherence of the measurements, a mean intraclass correlation coefficient was used. Results: The maximum grip force values were statistically significantly different in every wrist position and decreased progressively with an increasing flexion angle (p < 0.05). This relationship is expressed in a logistic regression curve f(x) = −4.98 + 16.92/(1 + (x/8.59))2.24. A wrist position of 4.4° of flexion was derived from this function to cause a maximum grip force reduction of 33%. Further analysis showed a force decrease of 50% at 23.2° and 66% at 51.8° of wrist flexion. The grip strength measured without an orthosis showed a positive correlation with previous measurements (Spearman’s correlation coefficient = 0.74 for the right hand and 0.72 for the left hand (p < 0.001)). Conclusions: The obtained logistic function allowed to derive the wrist position needed in a post-operative orthosis to obtain a desired amount of maximum grip force reduction. Clinical relevance Measuring a high grip force in a clinical setting of flexor tendon repair on the contralateral non-affected hand could indicate the use of an increased flexion angle in a post-operative orthosis. This reduces the load transferred on the tendon repair when involuntary contractions take place, for example, during sleeping when positioned in a post-operative orthosis.

Weightbearing CT in normal hindfoot alignment: Presence of a constitutional valgus?

BACKGROUND The normal hindfoot angle is estimated between 2° and 6° of valgus in the general population. These results are solely based on clinical findings and plain radiographs. The purpose of this study is to assess the hindfoot alignment using weightbear CT. METHODS Forty-eight patients, mean age of 39.6±13.2 years, with clinical and radiological absence of hindfoot pathology were included. A weightbear CT was obtained and allowed to measure the anatomical tibia axis (TAx) and the hindfoot alignment (HA). The HA was firstly determined using the inferior point of the calcaneus (HAIC). A density measurement of this area was subsequently performed to analyze if this point concurred with an increased ossification, indicating a higher load exposure. Secondly the HA was determined by dividing the calcaneus in the long axial view (HALA) and compared to the (HAIC) to point out any possible differences attributed to the measurement method. Reliability was assessed using an intra class correlation coefficient (ICC). RESULTS The mean HAIC equaled 0.79° of valgus±3.2 (ICCHA IC=0.73) with a mean TAx of 2.7° varus±2.1 (ICCTA=0.76). The HALA equaled 9.1° of valgus±4.8 (ICCHA LA=0.71) and differed significantly by a P<0.001 from the HAIC, which showed a more neutral alignment. Correlation between both was shown to be good by a Spearmans correlation coefficient of 0.74. The mean density of the inferior calcaneal area equaled 271.3±84.1 and was significantly higher than the regional calcaneal area (P<0.001). CONCLUSIONS These results show a more neutral alignment of the hindfoot in this group of non-symptomatic feet as opposed to the generally accepted constitutional valgus. This could have repercussion on hindfoot position during fusion or in quantifying the correction of a malalignment. The inferior calcaneus point in this can be used during pre-operative planning of a hindfoot correction as an anatomical landmark due to its shown influence on load transfer.

Reliability and correlation analysis of computed methods to convert conventional 2D radiological hindfoot measurements to a 3D setting using weightbearing CT

PurposeThe exact radiographic assessment of the hindfoot alignment remains challenging. This is reflected in the different measurement methods available. Weightbearing CT (WBCT) has been demonstrated to be more accurate in hindfoot measurements. However, current measurements are still performed in 2D. This study wants to assess the use of computed methods to convert the former uniplanar hindfoot measurements obtained after WBCT towards a 3D setting.MethodsForty-eight patients, mean age of 39.6 ± 13.2 years, with absence of hindfoot pathology were included. A WBCT was obtained, and images were subsequently segmented and analyzed using computer-aided design operations. In addition to the hindfoot angle (HA), other ankle and hindfoot parameters such as the anatomical tibia axis, talocalcaneal axis (TCA), talocrural angle, tibial inclination (TI), talar tilt, and subtalar vertical angle were determined in 2D and 3D.ResultsThe mean

Percutaneous Bunionette Correction: A Cadaveric Study

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